docs: Improve installation instructions, focus on LuaRocks installation (#454)

Update CI

.github/workflows/build.yml

@@ -8,27 +8,32 @@ on:
 
 jobs:
   build:
-    name: Test build on Linux
+    name: Test ${{ matrix.luaVersion }} on ${{ matrix.platform }}
     strategy:
       fail-fast: false
       matrix:
-        luaVersion: [ "5.4", "5.3", "5.2", "5.1", "luajit", "luajit-openresty"]
-        platform: [ "ubuntu-20.04", "macos-11" ] # "windows-2022" not supported by gh-actions-lua
+        luaVersion: [ "5.4", "5.3", "5.2", "5.1", "luajit", "luajit-openresty" ]
+        platform: [ "ubuntu-22.04", "macos-14", "windows-2022" ]
     runs-on: ${{ matrix.platform }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
+      - name: Setup ’msvc’
+        if: ${{ startsWith(matrix.platform, 'windows') && !startsWith(matrix.luaVersion, 'luajit') }}
+        uses: ilammy/msvc-dev-cmd@v1
       - name: Setup ‘lua’
-        uses: leafo/gh-actions-lua@v9
+        uses: luarocks/gh-actions-lua@v10
         with:
           luaVersion: ${{ matrix.luaVersion }}
       - name: Setup ‘luarocks’
-        uses: leafo/gh-actions-luarocks@v4
+        uses: luarocks/gh-actions-luarocks@v5
       - name: Make and install
         run: |
-          export DEBUG=DEBUG
           luarocks make -- luasocket-scm-3.rockspec
+        env:
+          DEBUG: DEBUG
       - name: Run regression tests
+        shell: bash
         run: |
           cd test
           lua hello.lua

.github/workflows/luacheck.yml

@@ -5,9 +5,9 @@ on: [push, pull_request]
 jobs:
 
   luacheck:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Luacheck
-        uses: lunarmodules/luacheck@v0
+        uses: lunarmodules/luacheck@v1

.luacheckrc

@@ -15,8 +15,6 @@ include_files = {
 }
 
 exclude_files = {
-    "etc/*.lua",
-    "etc/**/*.lua",
     "test/*.lua",
     "test/**/*.lua",
     "samples/*.lua",

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## [v3.1.0](https://github.com/lunarmodules/luasocket/releases/v3.1.0) — 2022-07-27
+
+* Add support for TCP Defer Accept – @Zash
+* Add support for TCP Fast Open – @Zash
+* Fix Windows (mingw32) builds – @goldenstein64
+* Avoid build warnings on 64-bit Windows – @rpatters1
+
 ## [v3.0.0](https://github.com/lunarmodules/luasocket/releases/v3.0.0) — 2022-03-25
 
 The last time LuaSocket had a stable release tag was 14 years ago when 2.0.2 was tagged.

FIX

@@ -1,28 +0,0 @@
-
-
-
-
-
-
-http was preserving old host header during redirects
-fix smtp.send hang on source error
-add create field to FTP and SMTP and fix HTTP ugliness
-clean timeout argument to open functions in SMTP, HTTP and FTP
-eliminate globals from namespaces created by module().
-url.absolute was not working when base_url was already parsed
-http.request was redirecting even when the location header was empty
-tcp{client}:shutdown() was checking for group instead of class.
-tcp{client}:send() now returns i+sent-1...
-get rid of a = socket.try() in the manual, except for protected cases. replace it with assert.
-get rid of "base." kludge in package.loaded
-check all "require("http")" etc in the manual.
-make sure sock_gethostname.*  only return success if the hp is not null!
-change 'l' prefix in C libraries to 'c' to avoid clash with LHF libraries
-    don't forget the declarations in luasocket.h and mime.h!!!
-setpeername was using udp{unconnected}
-fixed a bug in http.lua that caused some requests to fail (Florian Berger)
-fixed a bug in select.c that prevented sockets with descriptor 0 from working (Renato Maia)
-fixed a "bug" that caused dns.toip to crash under uLinux
-fixed a "bug" that caused a crash in gethostbyname under VMS
-DEBUG and VERSION became _DEBUG and _VERSION
-send returns the right value if input is "". Alexander Marinov

README.md

@@ -1,8 +1,8 @@
 # LuaSocket
 
 
-[![Build](https://img.shields.io/github/workflow/status/lunarmodules/luasocket/Build?label=Build=Lua)](https://github.com/lunarmodules/luasocket/actions?workflow=Build)
-[![Luacheck](https://img.shields.io/github/workflow/status/lunarmodules/luasocket/Luacheck?label=Luacheck&logo=Lua)](https://github.com/lunarmodules/luasocket/actions?workflow=Luacheck)
+[![Build](https://img.shields.io/github/actions/workflow/status/lunarmodules/luasocket/build.yml?branch=master&label=Build&logo=Lua)](https://github.com/lunarmodules/luasocket/actions?workflow=Build)
+[![Luacheck](https://img.shields.io/github/actions/workflow/status/lunarmodules/luasocket/luacheck.yml?branch=master&label=Luacheck&logo=Lua)](https://github.com/lunarmodules/luasocket/actions?workflow=Luacheck)
 [![GitHub tag (latest SemVer)](https://img.shields.io/github/v/tag/lunarmodules/luasocket?label=Tag&logo=GitHub)](https://github.com/lunarmodules/luasocket/releases)
 [![Luarocks](https://img.shields.io/luarocks/v/lunarmodules/luasocket?label=Luarocks&logo=Lua)](https://luarocks.org/modules/lunarmodules/luasocket)
 

TODO

@@ -1,81 +0,0 @@
-- bizarre default values for getnameinfo should throw error instead!
-
-> It's just too bad it can't talk to gmail -
-> reason 1: they absolutely want TLS
-> reason 2: unlike all the other SMTP implementations, they
-> don't
-> tolerate missing < > around adresses
-
-- document the new bind and connect behavior.
-- shouldn't we instead make the code compatible to Lua 5.2
-  without any compat stuff, and use a compatibility layer to
-  make it work on 5.1?
-- add what's new to manual
-- should there be an equivalent to tohostname for IPv6?
-- should we add service name resolution as well to getaddrinfo?
-- Maybe the sockaddr to presentation conversion should be done with getnameinfo()? 
-
-- add http POST sample to manual
-  people keep asking stupid questions
-- documentation of dirty/getfd/setfd is problematic because of portability
-  same for unix and serial.
-  what to do about this? add a stronger disclaimer?
-- fix makefile with decent defaults?
-
-Done:
-
-- added IPv6 support to getsockname
-- simplified getpeername implementation 
-- added family to return of getsockname and getpeername
-  and added modification to the manual to describe
-
-- connect and bind try all adresses returned by getaddrinfo
-- document headers.lua?
-- update copyright date everywhere? 
-- remove RCSID from files?
-- move version to 2.1 rather than 2.1.1?
-- fixed url package to support ipv6 hosts 
-- changed domain to family
-- implement getfamily methods.
-
-- remove references to Lua 5.0 from documentation, add 5.2?
-- update lua and luasocket version in samples in documentation
-- document ipv5_v6only default option being set?
-- document tcp6 and udp6
-- document dns.getaddrinfo 
-- documented zero-sized datagram change?
-  no.
-- document unix socket and serial socket? add raw support?
-  no.
-- document getoption
-- merge luaL_typeerror into auxiliar to avoid using luaL prefix? 
-
-
-
-
-
-
-
-
-
-
-replace \r\n with \0xD\0xA in everything
-New mime support
-
-ftp send should return server replies?
-make sure there are no object files in the distribution tarball
-http handling of 100-continue, see DB patch
-DB ftp.lua bug.
-test unix.c to return just a function and works with require"unix"
-get rid of setmetatable(, nil) since packages don't need this anymore in 5.1
-compat-5.1 novo
-ajeitar pra lua-5.1
-
-adicionar exemplos de expansão: pipe, local, named pipe
-testar os options!
-
-
-- Thread-unsafe functions to protect
-    gethostbyname(), gethostbyaddr(), gethostent(),
-inet_ntoa(), strerror(), 
-    

TODO.md

@@ -0,0 +1,135 @@
+## FIX
+
+http was preserving old host header during redirects
+fix smtp.send hang on source error
+add create field to FTP and SMTP and fix HTTP ugliness
+clean timeout argument to open functions in SMTP, HTTP and FTP
+eliminate globals from namespaces created by module().
+url.absolute was not working when base_url was already parsed
+http.request was redirecting even when the location header was empty
+tcp{client}:shutdown() was checking for group instead of class.
+tcp{client}:send() now returns i+sent-1...
+get rid of a = socket.try() in the manual, except for protected cases. replace it with assert.
+get rid of "base." kludge in package.loaded
+check all "require("http")" etc in the manual.
+make sure sock_gethostname.*  only return success if the hp is not null!
+change 'l' prefix in C libraries to 'c' to avoid clash with LHF libraries
+    don't forget the declarations in luasocket.h and mime.h!!!
+setpeername was using udp{unconnected}
+fixed a bug in http.lua that caused some requests to fail (Florian Berger)
+fixed a bug in select.c that prevented sockets with descriptor 0 from working (Renato Maia)
+fixed a "bug" that caused dns.toip to crash under uLinux
+fixed a "bug" that caused a crash in gethostbyname under VMS
+DEBUG and VERSION became _DEBUG and _VERSION
+send returns the right value if input is "". Alexander Marinov
+
+
+## WISH
+
+... as an l-value to get all results of a function call?
+at least ...[i] and #...
+extend to full tuples?
+
+__and __or __not metamethods
+
+lua_tostring, lua_tonumber, lua_touseradta etc push values in stack
+__tostring,__tonumber, __touserdata metamethods are checked
+and expected to push an object of correct type on stack
+
+lua_rawtostring, lua_rawtonumber, lua_rawtouserdata don't
+push anything on stack, return data of appropriate type,
+skip metamethods and throw error if object not of exact type
+
+package.findfile exported
+module not polluting the global namespace
+
+coxpcall with a coroutine pool for efficiency (reusing coroutines)
+
+exception mechanism formalized? just like the package system was.
+
+a nice bitlib in the core
+
+
+## TODO
+
+- bizarre default values for getnameinfo should throw error instead!
+
+> It's just too bad it can't talk to gmail -
+> reason 1: they absolutely want TLS
+> reason 2: unlike all the other SMTP implementations, they
+> don't
+> tolerate missing < > around adresses
+
+- document the new bind and connect behavior.
+- shouldn't we instead make the code compatible to Lua 5.2
+  without any compat stuff, and use a compatibility layer to
+  make it work on 5.1?
+- add what's new to manual
+- should there be an equivalent to tohostname for IPv6?
+- should we add service name resolution as well to getaddrinfo?
+- Maybe the sockaddr to presentation conversion should be done with getnameinfo()?
+
+- add http POST sample to manual
+  people keep asking stupid questions
+- documentation of dirty/getfd/setfd is problematic because of portability
+  same for unix and serial.
+  what to do about this? add a stronger disclaimer?
+- fix makefile with decent defaults?
+
+## Done:
+
+- added IPv6 support to getsockname
+- simplified getpeername implementation
+- added family to return of getsockname and getpeername
+  and added modification to the manual to describe
+
+- connect and bind try all adresses returned by getaddrinfo
+- document headers.lua?
+- update copyright date everywhere?
+- remove RCSID from files?
+- move version to 2.1 rather than 2.1.1?
+- fixed url package to support ipv6 hosts
+- changed domain to family
+- implement getfamily methods.
+
+- remove references to Lua 5.0 from documentation, add 5.2?
+- update lua and luasocket version in samples in documentation
+- document ipv5_v6only default option being set?
+- document tcp6 and udp6
+- document dns.getaddrinfo
+- documented zero-sized datagram change?
+  no.
+- document unix socket and serial socket? add raw support?
+  no.
+- document getoption
+- merge luaL_typeerror into auxiliar to avoid using luaL prefix?
+
+
+
+
+
+
+
+
+
+
+replace \r\n with \0xD\0xA in everything
+New mime support
+
+ftp send should return server replies?
+make sure there are no object files in the distribution tarball
+http handling of 100-continue, see DB patch
+DB ftp.lua bug.
+test unix.c to return just a function and works with require"unix"
+get rid of setmetatable(, nil) since packages don't need this anymore in 5.1
+compat-5.1 novo
+ajeitar pra lua-5.1
+
+adicionar exemplos de expans<6E>o: pipe, local, named pipe
+testar os options!
+
+
+- Thread-unsafe functions to protect
+    gethostbyname(), gethostbyaddr(), gethostent(),
+inet_ntoa(), strerror(),
+

WISH

@@ -1,22 +0,0 @@
-... as an l-value to get all results of a function call?
-at least ...[i] and #...
-extend to full tuples?
-
-__and __or __not metamethods
-
-lua_tostring, lua_tonumber, lua_touseradta etc push values in stack
-__tostring,__tonumber, __touserdata metamethods are checked
-and expected to push an object of correct type on stack
-
-lua_rawtostring, lua_rawtonumber, lua_rawtouserdata don't
-push anything on stack, return data of appropriate type, 
-skip metamethods and throw error if object not of exact type
-
-package.findfile exported
-module not polluting the global namespace
-
-coxpcall with a coroutine pool for efficiency (reusing coroutines)
-
-exception mechanism formalized? just like the package system was.
-
-a nice bitlib in the core

docs/ftp.html

@@ -55,7 +55,7 @@ protocol.  For that, check the implementation.
 
 <p>
 To really benefit from this module, a good understanding of
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">
 LTN012, Filters sources and sinks</a> is necessary.
 </p>
 
@@ -122,7 +122,7 @@ expects at least the fields <tt>host</tt>, <tt>sink</tt>, and one of
 <tt>argument</tt> or <tt>path</tt> (<tt>argument</tt> takes
 precedence). <tt>Host</tt> is the server to connect to. <tt>Sink</tt> is
 the <em>simple</em>
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 sink that will receive the downloaded data. <tt>Argument</tt> or
 <tt>path</tt> give the target path to the resource in the server. The
 optional arguments are the following:
@@ -136,7 +136,7 @@ authentication. Defaults to "<tt>ftp:anonymous@anonymous.org</tt>";</li>
 <li><tt>type</tt>: The transfer mode. Can take values "<tt>i</tt>" or
 "<tt>a</tt>". Defaults to whatever is the server default;</li>
 <li><tt>step</tt>:
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 pump step function used to pass data from the
 server to the sink. Defaults to the LTN12 <tt>pump.step</tt> function;</li>
 <li><tt>create</tt>: An optional function to be used instead of
@@ -206,7 +206,7 @@ expects at least the fields <tt>host</tt>, <tt>source</tt>, and one of
 <tt>argument</tt> or <tt>path</tt> (<tt>argument</tt> takes
 precedence). <tt>Host</tt> is the server to connect to. <tt>Source</tt> is
 the <em>simple</em>
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 source that will provide the contents to be uploaded.
 <tt>Argument</tt> or
 <tt>path</tt> give the target path to the resource in the server. The
@@ -221,7 +221,7 @@ authentication. Defaults to "<tt>ftp:anonymous@anonymous.org</tt>";</li>
 <li><tt>type</tt>: The transfer mode. Can take values "<tt>i</tt>" or
 "<tt>a</tt>". Defaults to whatever is the server default;</li>
 <li><tt>step</tt>:
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 pump step function used to pass data from the
 server to the sink. Defaults to the LTN12 <tt>pump.step</tt> function;</li>
 <li><tt>create</tt>: An optional function to be used instead of

docs/http.html

@@ -52,7 +52,7 @@ implementation    conforms     to    the    HTTP/1.1     standard,
 The module exports functions that provide HTTP functionality in different
 levels of abstraction. From the simple
 string oriented requests, through generic
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a> based, down to even lower-level if you bother to look through the source code.
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a> based, down to even lower-level if you bother to look through the source code.
 </p>
 
 <p>
@@ -144,7 +144,7 @@ http.<b>request{</b><br>
 The request function has two forms. The simple form downloads
 a URL using the <tt>GET</tt> or <tt>POST</tt> method and is based
 on strings. The generic form performs any HTTP method and is
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a> based.
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a> based.
 </p>
 
 <p class="parameters">
@@ -158,7 +158,7 @@ in the <tt>url</tt>. Otherwise, it performs a <tt>GET</tt> in the
 <p class="parameters">
 If the first argument is instead a table, the most important fields are
 the <tt>url</tt> and the <em>simple</em>
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 <tt>sink</tt> that will receive the downloaded content.
 Any part of the <tt>url</tt> can be overridden by including
 the appropriate field in the request table.
@@ -172,13 +172,13 @@ following:
 <li><tt>method</tt>: The HTTP request method. Defaults to "GET";</li>
 <li><tt>headers</tt>: Any additional HTTP headers to send with the request;</li>
 <li><tt>source</tt>: <em>simple</em>
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 source to provide the request body. If there
 is a body, you need to provide an appropriate "<tt>content-length</tt>"
 request header field, or the function will attempt to send the body as
 "<tt>chunked</tt>" (something few servers support). Defaults to the empty source;</li>
 <li><tt>step</tt>:
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 pump step function used to move data.
 Defaults to the LTN12 <tt>pump.step</tt> function.</li>
 <li><tt>proxy</tt>: The URL of a proxy server to use. Defaults to no proxy;</li>

docs/index.html

@@ -87,7 +87,7 @@ Author: <a href="http://www.impa.br/~diego">Diego Nehab</a>
 <h2 id="download">Download</h2>
 
 <p>
-LuaSocket version 3.0.0 is now available for download!
+LuaSocket version 3.1.0 is now available for download!
 It is compatible with Lua&nbsp;5.1 through 5.4.
 Chances are it works well on most UNIX distributions and Windows flavors.
 </p>

docs/installation.html

@@ -1,11 +1,11 @@
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" 
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
     "http://www.w3.org/TR/html4/strict.dtd">
 <html>
 
 <head>
 <meta name="description" content="LuaSocket: Introduction to the core">
 <meta name="keywords" content="Lua, LuaSocket, TCP, UDP, Network, Support,
-Installation"> 
+Installation">
 <title>LuaSocket: Installation</title>
 <link rel="stylesheet" href="reference.css" type="text/css">
 </head>
@@ -29,7 +29,7 @@ Installation">
 <a href="index.html#download">download</a> &middot;
 <a href="installation.html">installation</a> &middot;
 <a href="introduction.html">introduction</a> &middot;
-<a href="reference.html">reference</a> 
+<a href="reference.html">reference</a>
 </p>
 </center>
 <hr>
@@ -37,70 +37,30 @@ Installation">
 
 <!-- installation ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
 
-<h2>Installation</h2>
+<h2>Installation via luarocks</h2>
 
-<p> Here we describe the standard distribution.  If the
-standard doesn't meet your needs, we refer you to the Lua
-discussion list, where any question about the package scheme
-will likely already have been answered.  </p>
 
-<h3>Directory structure</h3>
 
-<p> On Unix systems, the standard distribution uses two base
-directories, one for system dependent files, and another for system
-independent files. Let's call these directories <tt>&lt;CDIR&gt;</tt> 
-and <tt>&lt;LDIR&gt;</tt>, respectively. 
-For example, in my laptp, Lua&nbsp;5.1 is configured to
-use '<tt>/usr/local/lib/lua/5.1</tt>' for
-<tt>&lt;CDIR&gt;</tt> and '<tt>/usr/local/share/lua/5.1</tt>' for
-<tt>&lt;LDIR&gt;</tt>. On Windows, <tt>&lt;CDIR&gt;</tt>
-usually points to the directory where the Lua executable is
-found, and <tt>&lt;LDIR&gt;</tt> points to a
-<tt>lua/</tt> directory inside <tt>&lt;CDIR&gt;</tt>. (These
-settings can be overridden by environment variables 
-<tt>LUA_PATH</tt> and <tt>LUA_CPATH</tt>. See the Lua
-documentation for details.) Here is the standard LuaSocket 
-distribution directory structure:</p>
+<p>LuaSocket can be easily installed using <a href="https://luarocks.org/" target="_blank">LuaRocks</a>, the Lua package manager.</p>
 
+<h3>Installing via LuaRocks</h3>
+
+<p>Run the following command in your terminal:</p>
 <pre class=example>
-&lt;LDIR&gt;/ltn12.lua
-&lt;LDIR&gt;/socket.lua
-&lt;CDIR&gt;/socket/core.dll
-&lt;LDIR&gt;/socket/http.lua
-&lt;LDIR&gt;/socket/tp.lua
-&lt;LDIR&gt;/socket/ftp.lua
-&lt;LDIR&gt;/socket/smtp.lua
-&lt;LDIR&gt;/socket/url.lua
-&lt;LDIR&gt;/mime.lua
-&lt;CDIR&gt;/mime/core.dll
+luarocks install luasocket
 </pre>
 
-<p> Naturally, on Unix systems, <tt>core.dll</tt>
-would be replaced by <tt>core.so</tt>.  
-</p>
+<h3>Verification</h3>
+    <p>To verify that LuaSocket is installed correctly, open Lua and run:</p>
+    <pre class=example><code>
+   local socket = require("socket")
+   print(socket._VERSION)
+    </code></pre>
 
-<h3>Using LuaSocket</h3>
+<p>If you see output like <strong>LuaSocket 3.0</strong>, the installation was successful.</p>
 
-<p> With the above setup, and an interpreter with shared library support,
-it should be easy to use LuaSocket. Just fire the interpreter and use the
-<tt>require</tt> function to gain access to whatever module you need:</p>
-
-<pre class=example>
-Lua 5.2.2  Copyright (C) 1994-2013 Lua.org, PUC-Rio
-&gt; socket = require("socket")
-&gt; print(socket._VERSION)
---&gt; LuaSocket 3.0-rc1
-</pre>
-
-<p> Each module loads their dependencies automatically, so you only need to
-load the modules you directly depend upon: </p>
-
-<pre class=example>
-Lua 5.2.2  Copyright (C) 1994-2013 Lua.org, PUC-Rio
-&gt; http = require("socket.http")
-&gt; print(http.request("http://www.impa.br/~diego/software/luasocket"))
---&gt; homepage gets dumped to terminal
-</pre>
+<h3>More Information</h3>
+<p>For more details, visit the <a href="https://github.com/lunarmodules/luasocket" target="_blank">LuaSocket GitHub repository</a>.</p>
 
 <!-- footer +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
 

docs/introduction.html

@@ -1,11 +1,11 @@
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" 
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
     "http://www.w3.org/TR/html4/strict.dtd">
 <html>
 
 <head>
 <meta name="description" content="LuaSocket: Introduction to the core">
 <meta name="keywords" content="Lua, LuaSocket, TCP, UDP, Network,
-Library, Support"> 
+Library, Support">
 <title>LuaSocket: Introduction to the core</title>
 <link rel="stylesheet" href="reference.css" type="text/css">
 </head>
@@ -29,7 +29,7 @@ Library, Support">
 <a href="index.html#download">download</a> &middot;
 <a href="installation.html">installation</a> &middot;
 <a href="introduction.html">introduction</a> &middot;
-<a href="reference.html">reference</a> 
+<a href="reference.html">reference</a>
 </p>
 </center>
 <hr>
@@ -61,23 +61,23 @@ interface to I/O across different domains and operating systems.
 The API design had two goals in mind. First, users
 experienced with the C API to sockets should feel comfortable using LuaSocket.
 Second, the simplicity and the feel of the Lua language should be
-preserved. To achieve these goals, the LuaSocket API keeps the function names and semantics the C API whenever possible, but their usage in Lua has been greatly simplified.  
+preserved. To achieve these goals, the LuaSocket API keeps the function names and semantics the C API whenever possible, but their usage in Lua has been greatly simplified.
 </p>
 
 
 <p>
 One of the simplifications is the receive pattern capability.
-Applications can read  data from stream domains (such as TCP) 
+Applications can read  data from stream domains (such as TCP)
 line  by line, block  by block, or until the connection  is closed.
 All I/O reads are buffered and the performance differences between
-different receive patterns are negligible.  
+different receive patterns are negligible.
 </p>
 
 <p>
 Another advantage is the flexible timeout control
 mechanism. As in C, all I/O  operations are blocking by default. For
-example, the  <a href=tcp.html#send><tt>send</tt></a>,  
-<a href=tcp.html#receive><tt>receive</tt></a> and 
+example, the  <a href=tcp.html#send><tt>send</tt></a>,
+<a href=tcp.html#receive><tt>receive</tt></a> and
 <a href=tcp.html#accept><tt>accept</tt></a> methods
 of the TCP domain will block  the  caller application  until
 the operation  is completed (if ever!). However, with a call to the
@@ -87,7 +87,7 @@ the time it can  be blocked by LuaSocket (the "<tt>total</tt>" timeout), on
 the time  LuaSocket can  internally be  blocked by  any OS call (the
 "<tt>block</tt>" timeout) or a combination of the  two.  Each LuaSocket
 call might perform several OS calls, so that the two timeout values are
-<em>not</em> equivalent.  
+<em>not</em> equivalent.
 </p>
 
 <p>
@@ -95,10 +95,10 @@ Finally,  the host  name  resolution   is  transparent,  meaning  that  most
 functions and methods accept both  IP addresses and host names. In  case a
 host name is given, the  library  queries the  system's  resolver  and
 tries  the main IP address returned. Note that direct use of IP addresses
-is more efficient, of course. The 
-<a href=dns.html#toip><tt>toip</tt></a> 
-and <a href=dns.html#tohostname><tt>tohostname</tt></a> 
-functions from the DNS module are provided to convert between host names and IP addresses. 
+is more efficient, of course. The
+<a href=dns.html#toip><tt>toip</tt></a>
+and <a href=dns.html#tohostname><tt>tohostname</tt></a>
+functions from the DNS module are provided to convert between host names and IP addresses.
 </p>
 
 <p>
@@ -118,47 +118,47 @@ reassembled transparently on  the other end. There are  no boundaries in
 the  data transfers.  The library  allows users  to read  data from  the
 sockets in  several different granularities: patterns  are available for
 lines, arbitrary sized blocks  or "read up to connection closed", all with
-good performance. 
+good performance.
 </p>
 
 <p>
-The library distinguishes  three types of TCP sockets:  <em>master</em>, 
-<em>client</em> and <em>server</em> sockets. 
+The library distinguishes  three types of TCP sockets:  <em>master</em>,
+<em>client</em> and <em>server</em> sockets.
 </p>
 
 <p>
 Master sockets are newly created TCP sockets returned by the function
-<a href=tcp.html#tcp><tt>socket.tcp</tt></a>. A master socket is 
+<a href=tcp.html#tcp><tt>socket.tcp</tt></a>. A master socket is
 transformed into a server socket
 after it is associated with a <em>local</em> address by a call to the
-<a href=tcp.html#bind><tt>bind</tt></a> method followed by a call to the 
-<a href=tcp.html#listen><tt>listen</tt></a>. Conversely, a master socket 
-can be changed into a client socket with the method 
-<a href=tcp.html#connect><tt>connect</tt></a>, 
-which associates it with a <em>remote</em> address. 
+<a href=tcp.html#bind><tt>bind</tt></a> method followed by a call to the
+<a href=tcp.html#listen><tt>listen</tt></a>. Conversely, a master socket
+can be changed into a client socket with the method
+<a href=tcp.html#connect><tt>connect</tt></a>,
+which associates it with a <em>remote</em> address.
 </p>
 
 <p>
-On server sockets, applications can use the 
+On server sockets, applications can use the
 <a href=tcp.html#accept><tt>accept</tt></a> method
 to wait for a client connection. Once a  connection is established, a
 client socket object  is  returned representing  this  connection.  The
 other methods available   for   server   socket  objects   are
-<a href=tcp.html#getsockname><tt>getsockname</tt></a>,  
+<a href=tcp.html#getsockname><tt>getsockname</tt></a>,
 <a href=tcp.html#setoption><tt>setoption</tt></a>,
-<a href=tcp.html#settimeout><tt>settimeout</tt></a>, and 
-<a href=tcp.html#close><tt>close</tt></a>. 
+<a href=tcp.html#settimeout><tt>settimeout</tt></a>, and
+<a href=tcp.html#close><tt>close</tt></a>.
 </p>
 
 <p>
 Client sockets are  used to exchange data between  two applications over
-the Internet. Applications can call the  methods 
+the Internet. Applications can call the  methods
 <a href=tcp.html#send><tt>send</tt></a> and
-<a href=tcp.html#receive><tt>receive</tt></a> 
+<a href=tcp.html#receive><tt>receive</tt></a>
 to send and  receive data.  The other methods
-available for  client socket objects are 
+available for  client socket objects are
 <a href=tcp.html#getsockname><tt>getsockname</tt></a>,
-<a href=tcp.html#getpeername><tt>getpeername</tt></a>, 
+<a href=tcp.html#getpeername><tt>getpeername</tt></a>,
 <a href=tcp.html#setoption><tt>setoption</tt></a>,
 <a href=tcp.html#settimeout><tt>settimeout</tt></a>,
 <a href=tcp.html#shutdown><tt>shutdown</tt></a>, and
@@ -175,7 +175,7 @@ port (one that is chosen by the  operating system) on the local host and
 awaits client connections on that port. When a connection is established,
 the program reads a line from the  remote end and sends it back, closing
 the  connection immediately. You  can  test it  using the  telnet
-program. 
+program.
 </p>
 
 <pre class=example>
@@ -217,68 +217,68 @@ error free. Data  transfers are atomic, one datagram at  a time. Reading
 only  part of  a  datagram discards  the  rest, so  that  the following read
 operation  will  act  on  the  next  datagram.  The  advantages  are  in
 simplicity (no connection  setup) and performance (no  error checking or
-error correction). 
+error correction).
 </p>
 
 <p>
 Note that although no guarantees are made, these days
-networks are so good that, under normal circumstances, few errors 
+networks are so good that, under normal circumstances, few errors
 happen in practice.
 </p>
 
 <p>
-An UDP socket object is  created by the 
+An UDP socket object is  created by the
 <a href=udp.html#udp><tt>socket.udp</tt></a> function. UDP
 sockets  do   not  need   to  be  connected   before  use.   The  method
-<a href=udp.html#sendto><tt>sendto</tt></a>  
+<a href=udp.html#sendto><tt>sendto</tt></a>
 can  be  used  immediately after  creation  to
 send  a datagram to  IP address and port. Host names  are not allowed
 because performing name resolution for each packet would be forbiddingly
-slow.  Methods 
-<a href=udp.html#receive><tt>receive</tt></a>  and 
+slow.  Methods
+<a href=udp.html#receive><tt>receive</tt></a>  and
 <a href=udp.html#receivefrom><tt>receivefrom</tt></a>
 can be used to retrieve datagrams, the latter returning the IP and port of
 the  sender  as  extra  return  values (thus being  slightly  less
-efficient). 
+efficient).
 </p>
 
 <p>
 When  communication  is performed  repeatedly  with  a single  peer,  an
-application  should call  the 
+application  should call  the
 <a href=udp.html#setpeername><tt>setpeername</tt></a> method to specify a
-permanent partner.  Methods 
+permanent partner.  Methods
 <a href=udp.html#sendto><tt>sendto</tt></a> and
-<a href=udp.html#receivefrom><tt>receivefrom</tt></a> 
+<a href=udp.html#receivefrom><tt>receivefrom</tt></a>
 can no longer be used, but the method
-<a href=udp.html#send><tt>send</tt></a> can be used to send data 
-directly  to   the   peer, and the method 
-<a href=udp.html#receive><tt>receive</tt></a> 
+<a href=udp.html#send><tt>send</tt></a> can be used to send data
+directly  to   the   peer, and the method
+<a href=udp.html#receive><tt>receive</tt></a>
 will  only return  datagrams originating
 from that peer. There is about 30% performance gain due to this practice.
 </p>
 
 <p>
-To associate  an UDP socket with  a local address, an  application calls the   
-<a href=udp.html#setsockname><tt>setsockname</tt></a> 
+To associate  an UDP socket with  a local address, an  application calls the
+<a href=udp.html#setsockname><tt>setsockname</tt></a>
 method <em>before</em> sending any datagrams.   Otherwise, the socket is
 automatically  bound  to an  ephemeral  address  before the  first  data
-transmission and once bound the local address cannot be changed.  
+transmission and once bound the local address cannot be changed.
 The   other  methods   available  for  UDP   sockets  are
-<a href=udp.html#getpeername><tt>getpeername</tt></a>,  
-<a href=udp.html#getsockname><tt>getsockname</tt></a>, 
+<a href=udp.html#getpeername><tt>getpeername</tt></a>,
+<a href=udp.html#getsockname><tt>getsockname</tt></a>,
 <a href=udp.html#settimeout><tt>settimeout</tt></a>,
-<a href=udp.html#setoption><tt>setoption</tt></a> and 
-<a href=udp.html#close><tt>close</tt></a>. 
+<a href=udp.html#setoption><tt>setoption</tt></a> and
+<a href=udp.html#close><tt>close</tt></a>.
 </p>
 
 <p>
-Example: 
+Example:
 </p>
 <blockquote>
 <p>
 A simple daytime client, using LuaSocket. The program connects to a remote
 server and tries to retrieve the daytime, printing the answer it got or an
-error message. 
+error message.
 </p>
 
 <pre class=example>
@@ -301,11 +301,11 @@ io.write(assert(udp:receive()))
 
 <h3 id=more>Support modules</h3>
 
-<p> Although not covered in the introduction, LuaSocket offers 
+<p> Although not covered in the introduction, LuaSocket offers
 much more than TCP and UDP functionality. As the library
 evolved, support for <a href=http.html>HTTP</a>, <a href=ftp.html>FTP</a>,
 and <a href=smtp.html>SMTP</a> were built on top of these. These modules
-and many others are covered by the <a href=reference.html>reference manual</a>. 
+and many others are covered by the <a href=reference.html>reference manual</a>.
 </p>
 
 <!-- footer +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->

docs/ltn12.html

@@ -40,7 +40,7 @@ Pump, Support, Library">
 <h2 id="ltn12">LTN12</h2>
 
 <p> The <tt>ltn12</tt> namespace implements the ideas described in
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">
 LTN012, Filters sources and sinks</a>. This manual simply describes the
 functions. Please refer to the LTN for a deeper explanation of the
 functionality provided by this module.

docs/mime.html

@@ -54,7 +54,7 @@ MIME is described mainly in
 <p>
 All functionality provided by the MIME module
 follows the ideas presented in
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">
 LTN012, Filters sources and sinks</a>.
 </p>
 

docs/smtp.html

@@ -57,7 +57,7 @@ of the MIME standard, but described mainly
 in <a href="http://www.ietf.org/rfc/rfc2046.txt">RFC 2046</a>.</p>
 
 <p> In the description below, good understanding of <a
-href="http://lua-users.org/wiki/FiltersSourcesAndSinks"> LTN012, Filters
+href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md"> LTN012, Filters
 sources and sinks</a> and the  <a href="mime.html">MIME</a> module is
 assumed.  In fact, the SMTP module was the main reason for their
 creation. </p>
@@ -122,7 +122,7 @@ smtp.<b>message(</b>mesgt<b>)</b>
 
 <p class="description">
 Returns a <em>simple</em>
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a> source that sends an SMTP message body, possibly multipart (arbitrarily deep).
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a> source that sends an SMTP message body, possibly multipart (arbitrarily deep).
 </p>
 
 <p class="parameters">
@@ -155,7 +155,7 @@ multipart-mesgt = {<br>
 For a simple message, all that is needed is a set of <tt>headers</tt>
 and the <tt>body</tt>. The message <tt>body</tt> can be given as a string
 or as a <em>simple</em>
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 source. For multipart messages, the body is a table that
 recursively defines each part as an independent message, plus an optional
 <tt>preamble</tt> and <tt>epilogue</tt>.
@@ -163,7 +163,7 @@ recursively defines each part as an independent message, plus an optional
 
 <p class="return">
 The function returns a <em>simple</em>
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 source that produces the
 message contents as defined by <tt>mesgt</tt>, chunk by chunk.
 Hopefully, the following
@@ -264,7 +264,7 @@ The sender is given by the e-mail address in the <tt>from</tt> field.
 address, or a string
 in case there is just one recipient.
 The contents of the message are given by a <em>simple</em>
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 <tt>source</tt>. Several arguments are optional:
 </p>
 <ul>
@@ -276,7 +276,7 @@ methods if supported by the server (both are unsafe);</li>
 <li> <tt>domain</tt>: Domain name used to greet the server; Defaults to the
 local machine host name;</li>
 <li> <tt>step</tt>:
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 pump step function used to pass data from the
 source to the server. Defaults to the LTN12 <tt>pump.step</tt> function;</li>
 <li><tt>create</tt>: An optional function to be used instead of
@@ -308,7 +308,7 @@ Only recipients specified in the <tt>rcpt</tt> list will receive a copy of the
 message.  Each recipient of an SMTP mail message receives a copy of the
 message body along with the headers, and nothing more.  The headers
 <em>are</em> part of the message and should be produced by the
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 <tt>source</tt> function. The <tt>rcpt</tt> list is <em>not</em>
 part of the message and will not be sent to anyone.
 </p>

docs/socket.html

@@ -164,6 +164,9 @@ Creates and returns a <em>clean</em>
 <a href="#try"><tt>try</tt></a>
 function that allows for cleanup before the exception
 is  raised.
+This implements the ideas described in
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn013.md">
+LTN012, Using finalized exceptions</a>.
 </p>
 
 <p class="parameters">
@@ -207,6 +210,9 @@ Converts a function that throws exceptions into a safe function. This
 function only catches exceptions thrown by the <a href="#try"><tt>try</tt></a>
 and <a href="#newtry"><tt>newtry</tt></a> functions. It does not catch normal
 Lua errors.
+This implements the ideas described in
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn013.md">
+LTN012, Using finalized exceptions</a>.
 </p>
 
 <p class="parameters">
@@ -305,7 +311,7 @@ socket.<b>sink(</b>mode, socket<b>)</b>
 
 <p class="description">
 Creates an
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 sink from a stream socket object.
 </p>
 
@@ -380,7 +386,7 @@ socket.<b>source(</b>mode, socket [, length]<b>)</b>
 
 <p class="description">
 Creates an
-<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn012.md">LTN12</a>
 source from a stream socket object.
 </p>
 
@@ -425,6 +431,9 @@ socket.<b>try(</b>ret<sub>1</sub> [, ret<sub>2</sub> ... ret<sub>N</sub>]<b>)</b
 Throws an exception in case <tt>ret<sub>1</sub></tt> is falsy, using
 <tt>ret<sub>2</sub></tt> as the error message. The exception is supposed to be caught
 by a <a href="#protect"><tt>protect</tt></a>ed function only.
+This implements the ideas described in
+<a href="https://github.com/lunarmodules/luasocket/blob/master/ltn013.md">
+LTN012, Using finalized exceptions</a>.
 </p>
 
 <p class="parameters">

docs/tcp.html

@@ -485,6 +485,12 @@ disables the Nagle's algorithm for the connection;</li>
 
 <li> '<tt>tcp-keepintvl</tt>': value for <tt>TCP_KEEPINTVL</tt> Linux only!!</li>
 
+<li> '<tt>tcp-defer-accept</tt>': value for <tt>TCP_DEFER_ACCEPT</tt> Linux only!!</li>
+
+<li> '<tt>tcp-fastopen</tt>': value for <tt>TCP_FASTOPEN</tt> Linux only!!</li>
+
+<li> '<tt>tcp-fastopen-connect</tt>': value for <tt>TCP_FASTOPEN_CONNECT</tt> Linux only!!</li>
+
 <li> '<tt>ipv6-v6only</tt>':
 Setting this option to <tt>true</tt> restricts an <tt>inet6</tt> socket to
 sending and receiving only IPv6 packets.</li>

docs/udp.html

@@ -149,8 +149,8 @@ wild-card address).
 <!-- gettimeout +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
 
 <p class="name" id="gettimeout">
-connected:<b>settimeout(</b>value<b>)</b><br>
-unconnected:<b>settimeout(</b>value<b>)</b>
+connected:<b>gettimeout()</b><br>
+unconnected:<b>gettimeout()</b>
 </p>
 
 <p class="description">

docs/url.html

@@ -1,10 +1,10 @@
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" 
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
     "http://www.w3.org/TR/html4/strict.dtd">
 <html>
 
 <head>
 <meta name="description" content="LuaSocket: URL manipulation">
-<meta name="keywords" content="Lua, LuaSocket, URL, Library, Link, Network, Support"> 
+<meta name="keywords" content="Lua, LuaSocket, URL, Library, Link, Network, Support">
 <title>LuaSocket: URL support</title>
 <link rel="stylesheet" href="reference.css" type="text/css">
 </head>
@@ -28,7 +28,7 @@
 <a href="index.html#download">download</a> &middot;
 <a href="installation.html">installation</a> &middot;
 <a href="introduction.html">introduction</a> &middot;
-<a href="reference.html">reference</a> 
+<a href="reference.html">reference</a>
 </p>
 </center>
 <hr>
@@ -36,21 +36,21 @@
 
 <!-- url ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
 
-<h2 id="url">URL</h2> 
+<h2 id="url">URL</h2>
 
 <p>
 The  <tt>url</tt>  namespace provides  functions  to  parse,  protect,
 and build URLs, as well  as functions to compose  absolute URLs
-from base and relative URLs, according to 
+from base and relative URLs, according to
 <a href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>.
 </p>
 
-<p> 
+<p>
 To obtain the <tt>url</tt> namespace, run:
 </p>
 
 <pre class=example>
--- loads the URL module 
+-- loads the URL module
 local url = require("socket.url")
 </pre>
 
@@ -74,7 +74,7 @@ url.<b>absolute(</b>base, relative<b>)</b>
 </p>
 
 <p class=description>
-Builds an absolute URL from a base URL and a relative URL. 
+Builds an absolute URL from a base URL and a relative URL.
 </p>
 
 <p class=parameters>
@@ -130,14 +130,14 @@ url.<b>build(</b>parsed_url<b>)</b>
 </p>
 
 <p class=description>
-Rebuilds an URL from its parts. 
+Rebuilds an URL from its parts.
 </p>
 
 <p class=parameters>
 <tt>Parsed_url</tt> is a table with same components returned by
 <a href="#parse"><tt>parse</tt></a>.
 Lower level components, if specified,
-take  precedence over  high level  components of  the URL grammar. 
+take  precedence over  high level  components of  the URL grammar.
 </p>
 
 <p class=return>
@@ -152,10 +152,10 @@ url.<b>build_path(</b>segments, unsafe<b>)</b>
 
 <p class=description>
 Builds a <tt>&lt;path&gt;</tt> component from  a list of
-<tt>&lt;segment&gt;</tt> parts. 
+<tt>&lt;segment&gt;</tt> parts.
 Before composition, any reserved characters found in a segment are escaped into
 their protected  form, so that  the resulting path  is a valid  URL path
-component.  
+component.
 </p>
 
 <p class=parameters>
@@ -165,8 +165,8 @@ characters are left untouched.
 </p>
 
 <p class=return>
-The  function  returns   a string with the  
-built <tt>&lt;path&gt;</tt> component. 
+The  function  returns   a string with the
+built <tt>&lt;path&gt;</tt> component.
 </p>
 
 <!-- escape +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
@@ -178,7 +178,7 @@ url.<b>escape(</b>content<b>)</b>
 <p class=description>
 Applies the URL escaping content coding to a string
 Each byte is encoded as a percent character followed
-by the two byte hexadecimal representation of its integer 
+by the two byte hexadecimal representation of its integer
 value.
 </p>
 
@@ -270,8 +270,8 @@ url.<b>parse_path(</b>path<b>)</b>
 </p>
 
 <p class=description>
-Breaks a <tt>&lt;path&gt;</tt> URL component into all its 
-<tt>&lt;segment&gt;</tt> parts. 
+Breaks a <tt>&lt;path&gt;</tt> URL component into all its
+<tt>&lt;segment&gt;</tt> parts.
 </p>
 
 <p class=description>
@@ -282,7 +282,7 @@ Breaks a <tt>&lt;path&gt;</tt> URL component into all its
 Since  some characters   are   reserved   in   URLs,  they must be escaped
 whenever present in a <tt>&lt;path&gt;</tt> component. Therefore, before
 returning a list with all the parsed segments, the function removes
-escaping from all of them. 
+escaping from all of them.
 </p>
 
 <!-- unescape +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
@@ -300,7 +300,7 @@ Removes  the   URL   escaping    content   coding   from   a string.
 </p>
 
 <p class=return>
-The function returns the decoded string. 
+The function returns the decoded string.
 </p>
 
 <!-- footer +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->

etc/README

@@ -1,89 +0,0 @@
-This directory contains code that is more useful than the
-samples. This code *is* supported.
-
-    tftp.lua                -- Trivial FTP client
-
-This module implements file retrieval by the TFTP protocol.
-Its main use was to test the UDP code, but since someone
-found it usefull, I turned it into a module that is almost
-official (no uploads, yet).
-
-    dict.lua                -- Dict client
-
-The dict.lua  module started with  a cool  simple client
-for the  DICT protocol, written by Luiz Henrique Figueiredo.
-This new version has been converted into a library, similar
-to the HTTP  and FTP libraries, that can be used from within
-any luasocket application. Take  a look on the  source code
-and you will be able to figure out how to use it.
-
-    lp.lua                  -- LPD client library
-
-The lp.lua module implements the client part of the Line
-Printer Daemon protocol, used to print files on Unix
-machines. It is courtesy of David Burgess!  See the source
-code and the lpr.lua in the examples directory.
-
-    b64.lua
-    qp.lua
-    eol.lua
-
-These are tiny programs that perform Base64,
-Quoted-Printable and end-of-line marker conversions.
-
-    get.lua                 -- file retriever
-
-This little  program is  a client  that uses  the FTP  and
-HTTP  code to implement a  command line  file graber. Just
-run 
-
-	lua get.lua <remote-file> [<local-file>]
-
-to download  a remote file (either  ftp:// or http://) to
-the specified local file.  The program  also prints  the
-download  throughput, elapsed time, bytes already downloaded
-etc during download.
-
-    check-memory.lua        -- checks memory consumption
-
-This is just to see how much memory each module uses.
-
-    dispatch.lua            -- coroutine based dispatcher
-
-This is a first try at a coroutine based non-blocking
-dispatcher for LuaSocket. Take a look at 'check-links.lua'
-and at 'forward.lua' to see how to use it.
-
-	check-links.lua			-- HTML link checker program
-
-This little program scans a HTML file and checks for broken
-links. It is similar to check-links.pl by Jamie Zawinski,
-but uses all facilities of the LuaSocket library and the Lua
-language. It has not been thoroughly tested, but it should
-work. Just run
-
-	lua check-links.lua [-n] {<url>} > output
-
-and open the result to see a list of broken links. Make sure
-you check the '-n' switch. It runs in non-blocking mode,
-using coroutines, and is MUCH faster!
-
-    forward.lua             -- coroutine based forward server
-
-This is a forward server that can accept several connections
-and transfers simultaneously using non-blocking I/O and the
-coroutine-based dispatcher. You can run, for example
-
-    lua forward.lua 8080:proxy.com:3128 
-
-to redirect all local conections to port 8080 to the host 
-'proxy.com' at port 3128.
-
-    unix.c and unix.h
-
-This is an implementation of Unix local domain sockets and
-demonstrates how to extend LuaSocket with a new type of
-transport. It has been tested on Linux and on Mac OS X.
-
-Good luck,
-Diego.

gem/ex1.lua

@@ -1,4 +0,0 @@
-local CRLF = "\013\010"
-local input = source.chain(source.file(io.stdin), normalize(CRLF))
-local output = sink.file(io.stdout)
-pump.all(input, output)

gem/ex10.lua

@@ -1,17 +0,0 @@
-function pump.step(src, snk)
-  local chunk, src_err = src()
-  local ret, snk_err = snk(chunk, src_err)
-  if chunk and ret then return 1
-  else return nil, src_err or snk_err end
-end
-
-function pump.all(src, snk, step)
-    step = step or pump.step
-    while true do
-        local ret, err = step(src, snk)
-        if not ret then
-            if err then return nil, err
-            else return 1 end
-        end
-    end
-end

gem/ex11.lua

@@ -1,7 +0,0 @@
-local input = source.chain(
-  source.file(io.open("input.bin", "rb")),
-  encode("base64"))
-local output = sink.chain(
-  wrap(76),
-  sink.file(io.open("output.b64", "w")))
-pump.all(input, output)

gem/ex12.lua

@@ -1,34 +0,0 @@
-local smtp = require"socket.smtp"
-local mime = require"mime"
-local ltn12 = require"ltn12"
-
-CRLF = "\013\010"
-
-local message = smtp.message{
-  headers = {
-    from = "Sicrano <sicrano@example.com>",
-    to = "Fulano <fulano@example.com>",
-    subject = "A message with an attachment"},
-  body = {
-    preamble = "Hope you can see the attachment" .. CRLF,
-    [1] = {
-      body = "Here is our logo" .. CRLF},
-    [2] = {
-      headers = {
-        ["content-type"] = 'image/png; name="luasocket.png"',
-        ["content-disposition"] =
-          'attachment; filename="luasocket.png"',
-        ["content-description"] = 'LuaSocket logo',
-        ["content-transfer-encoding"] = "BASE64"},
-      body = ltn12.source.chain(
-        ltn12.source.file(io.open("luasocket.png", "rb")),
-        ltn12.filter.chain(
-          mime.encode("base64"),
-          mime.wrap()))}}}
-
-assert(smtp.send{
-  rcpt = "<diego@cs.princeton.edu>",
-  from = "<diego@cs.princeton.edu>",
-  server = "localhost",
-  port = 2525,
-  source = message})

gem/ex2.lua

@@ -1,11 +0,0 @@
-function filter.cycle(lowlevel, context, extra)
-  return function(chunk)
-    local ret
-    ret, context = lowlevel(context, chunk, extra)
-    return ret
-  end
-end
-
-function normalize(marker)
-  return filter.cycle(eol, 0, marker)
-end

gem/ex3.lua

@@ -1,15 +0,0 @@
-local function chainpair(f1, f2)
-  return function(chunk)
-    local ret = f2(f1(chunk))
-    if chunk then return ret
-    else return (ret or "") .. (f2() or "") end
-  end
-end
-
-function filter.chain(...)
-  local f = select(1, ...)
-  for i = 2, select('#', ...) do
-    f = chainpair(f, select(i, ...))
-  end
-  return f
-end

gem/ex4.lua

@@ -1,5 +0,0 @@
-local qp = filter.chain(normalize(CRLF), encode("quoted-printable"),
-  wrap("quoted-printable"))
-local input = source.chain(source.file(io.stdin), qp)
-local output = sink.file(io.stdout)
-pump.all(input, output)

gem/ex5.lua

@@ -1,15 +0,0 @@
-function source.empty(err)
-  return function()
-    return nil, err
-  end
-end
-
-function source.file(handle, io_err)
-  if handle then
-    return function()
-      local chunk = handle:read(20)
-      if not chunk then handle:close() end
-      return chunk
-    end
-  else return source.empty(io_err or "unable to open file") end
-end

gem/ex6.lua

@@ -1,14 +0,0 @@
-function source.chain(src, f)
-  return function()
-    if not src then
-      return nil
-    end
-    local chunk, err = src()
-    if not chunk then
-      src = nil
-      return f(nil)
-    else
-      return f(chunk)
-    end
-  end
-end

gem/ex7.lua

@@ -1,16 +0,0 @@
-function sink.table(t)
-  t = t or {}
-  local f = function(chunk, err)
-    if chunk then table.insert(t, chunk) end
-    return 1
-  end
-  return f, t
-end
-
-local function null()
-  return 1
-end
-
-function sink.null()
-  return null
-end

gem/ex8.lua

@@ -1,5 +0,0 @@
-local input = source.file(io.stdin)
-local output, t = sink.table()
-output = sink.chain(normalize(CRLF), output)
-pump.all(input, output)
-io.write(table.concat(t))

gem/ex9.lua

@@ -1,3 +0,0 @@
-for chunk in source.file(io.stdin) do
-  io.write(chunk)
-end

gem/gem.c

@@ -1,54 +0,0 @@
-#include "lua.h"
-#include "lauxlib.h"
-
-#define CR '\xD'
-#define LF '\xA'
-#define CRLF "\xD\xA"
-
-#define candidate(c) (c == CR || c == LF)
-static int pushchar(int c, int last, const char *marker, 
-    luaL_Buffer *buffer) {
-  if (candidate(c)) {
-    if (candidate(last)) {
-      if (c == last) 
-        luaL_addstring(buffer, marker);
-      return 0;
-    } else {
-      luaL_addstring(buffer, marker);
-      return c;
-    }
-  } else {
-    luaL_putchar(buffer, c);
-    return 0;
-  }
-}
-
-static int eol(lua_State *L) {
-  int context = luaL_checkint(L, 1);
-  size_t isize = 0;
-  const char *input = luaL_optlstring(L, 2, NULL, &isize);
-  const char *last = input + isize;
-  const char *marker = luaL_optstring(L, 3, CRLF);
-  luaL_Buffer buffer;
-  luaL_buffinit(L, &buffer);
-  if (!input) {
-    lua_pushnil(L);
-    lua_pushnumber(L, 0);
-    return 2;
-  }
-  while (input < last)
-    context = pushchar(*input++, context, marker, &buffer);
-  luaL_pushresult(&buffer);
-  lua_pushnumber(L, context);
-  return 2;
-}
-
-static luaL_reg func[] = {
-    { "eol", eol },
-    { NULL, NULL }
-};
-
-int luaopen_gem(lua_State *L) {
-    luaL_openlib(L, "gem", func, 0);
-	return 0;
-}

gem/gt.b64

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gem/ltn012.tex

@@ -1,695 +0,0 @@
-\documentclass[10pt]{article}
-\usepackage{fancyvrb}
-\usepackage{url}
-\DefineVerbatimEnvironment{lua}{Verbatim}{fontsize=\small,commandchars=\@\#\%}
-\DefineVerbatimEnvironment{C}{Verbatim}{fontsize=\small,commandchars=\@\#\%}
-\DefineVerbatimEnvironment{mime}{Verbatim}{fontsize=\small,commandchars=\$\#\%}
-\newcommand{\stick}[1]{\vbox{\setlength{\parskip}{0pt}#1}}
-\newcommand{\bl}{\ensuremath{\mathtt{\backslash}}}
-\newcommand{\CR}{\texttt{CR}}
-\newcommand{\LF}{\texttt{LF}}
-\newcommand{\CRLF}{\texttt{CR~LF}}
-\newcommand{\nil}{\texttt{nil}}
-
-\title{Filters, sources, sinks, and pumps\\
-      {\large or Functional programming for the rest of us}}
-\author{Diego Nehab}
-
-\begin{document}
-
-\maketitle
-
-\begin{abstract}
-Certain data processing operations can be implemented in the
-form of filters. A filter is a function that can process
-data received in consecutive invocations, returning partial
-results each time it is called.  Examples of operations that
-can be implemented as filters include the end-of-line
-normalization for text, Base64 and Quoted-Printable transfer
-content encodings, the breaking of text into lines, SMTP
-dot-stuffing, and there are many others.  Filters become
-even more powerful when we allow them to be chained together
-to create composite filters. In this context, filters can be
-seen as the internal links in a chain of data transformations.
-Sources and sinks are the corresponding end points in these
-chains. A source is a function that produces data, chunk by
-chunk, and a sink is a function that takes data, chunk by
-chunk. Finally, pumps are procedures that actively drive
-data from a source to a sink, and indirectly through all 
-intervening filters.  In this article, we describe the design of an
-elegant interface for filters, sources, sinks, chains, and
-pumps, and we illustrate each step with concrete examples. 
-\end{abstract}
-
-\section{Introduction}
-
-Within the realm of networking applications, we are often
-required to apply transformations to streams of data. Examples
-include the end-of-line normalization for text, Base64 and
-Quoted-Printable transfer content encodings, breaking text
-into lines with a maximum number of columns, SMTP
-dot-stuffing, \texttt{gzip} compression, HTTP chunked
-transfer coding, and the list goes on.
-
-Many complex tasks require a combination of two or more such
-transformations, and therefore a general mechanism for
-promoting reuse is desirable. In the process of designing
-\texttt{LuaSocket~2.0}, we repeatedly faced this problem.
-The solution we reached proved to be very general and
-convenient. It is based on the concepts of filters, sources,
-sinks, and pumps, which we introduce below. 
-
-\emph{Filters} are functions that can be repeatedly invoked
-with chunks of input, successively returning processed
-chunks of output. Naturally, the result of
-concatenating all the output chunks must be the same as the
-result of applying the filter to the concatenation of all
-input chunks. In fancier language, filters \emph{commute}
-with the concatenation operator. More importantly, filters
-must handle input data correctly no matter how the stream
-has been split into chunks. 
-
-A \emph{chain} is a function that transparently combines the
-effect of one or more filters. The interface of a chain is
-indistinguishable from the interface of its component
-filters.  This  allows a chained filter to be used wherever
-an atomic filter is accepted. In particular, chains can be
-themselves chained to create arbitrarily complex operations.
-
-Filters can be seen as internal nodes in a network through
-which data will flow, potentially being transformed many
-times along the way.  Chains connect these nodes together.
-The initial and final nodes of the network are
-\emph{sources} and \emph{sinks}, respectively.  Less
-abstractly, a source is a function that produces new chunks
-of data every time it is invoked.  Conversely, sinks are
-functions that give a final destination to the chunks of
-data they receive in sucessive calls.  Naturally, sources
-and sinks can also be chained with filters to produce
-filtered sources and sinks.
-
-Finally, filters, chains, sources, and sinks are all passive
-entities: they must be repeatedly invoked in order for
-anything to happen.  \emph{Pumps} provide the driving force
-that pushes data through the network, from a source to a
-sink, and indirectly through all intervening filters.
-
-In the following sections, we start with a simplified
-interface, which we later refine. The evolution we present
-is not contrived: it recreates the steps we ourselves
-followed as we consolidated our understanding of these
-concepts within our application domain. 
-
-\subsection{A simple example}
-
-The end-of-line normalization of text is a good
-example to motivate our initial filter interface. 
-Assume we are given text in an unknown end-of-line
-convention (including possibly mixed conventions) out of the
-commonly found Unix (\LF), Mac OS (\CR), and
-DOS (\CRLF) conventions. We would like to be able to 
-use the folowing code to normalize the end-of-line markers: 
-\begin{quote}
-\begin{lua}
-@stick#
-local CRLF = "\013\010"
-local input = source.chain(source.file(io.stdin), normalize(CRLF))
-local output = sink.file(io.stdout)
-pump.all(input, output)
-%
-\end{lua}
-\end{quote}
-
-This program should read data from the standard input stream
-and normalize the end-of-line markers to the canonic
-\CRLF\ marker, as defined by the MIME standard. 
-Finally, the normalized text should be sent to the standard output
-stream.  We use a \emph{file source} that produces data from
-standard input, and chain it with a filter that normalizes
-the data. The pump then repeatedly obtains data from the
-source, and passes it to the \emph{file sink}, which sends
-it to the standard output.
-
-In the code above, the \texttt{normalize} \emph{factory} is a
-function that creates our normalization filter, which 
-replaces any end-of-line marker with the canonic marker. 
-The initial filter interface is
-trivial: a filter function receives a chunk of input data,
-and returns a chunk of processed data.  When there are no
-more input data left, the caller notifies the filter by invoking
-it with a \nil\ chunk. The filter responds by returning
-the final chunk of processed data (which could of course be
-the empty string).
-
-Although the interface is extremely simple, the
-implementation is not so obvious. A normalization filter
-respecting this interface needs to keep some kind of context
-between calls. This is because a chunk boundary may lie between 
-the \CR\ and \LF\ characters marking the end of a single line. This
-need for contextual storage motivates the use of
-factories: each time the factory is invoked, it returns a
-filter with its own context so that we can have several
-independent filters being used at the same time.  For
-efficiency reasons, we must avoid the obvious solution of 
-concatenating all the input into the context before
-producing any output chunks. 
-
-To that end, we break the implementation into two parts:
-a low-level filter, and a factory of high-level filters. The
-low-level filter is implemented in C and does not maintain
-any context between function calls. The high-level filter
-factory, implemented in Lua, creates and returns a
-high-level filter that maintains whatever context the low-level
-filter needs, but isolates the user from its internal
-details. That way, we take advantage of C's efficiency to
-perform the hard work, and take advantage of Lua's
-simplicity for the bookkeeping.
-
-\subsection{The Lua part of the filter}
-
-Below is the complete implementation of the factory of high-level
-end-of-line normalization filters:
-\begin{quote}
-\begin{lua}
-@stick#
-function filter.cycle(lowlevel, context, extra)
-  return function(chunk)
-    local ret
-    ret, context = lowlevel(context, chunk, extra)
-    return ret
-  end
-end
-%
-
-@stick#
-function normalize(marker)
-  return filter.cycle(eol, 0, marker)
-end
-%
-\end{lua}
-\end{quote}
-
-The \texttt{normalize} factory simply calls a more generic
-factory, the \texttt{cycle}~factory, passing the low-level
-filter~\texttt{eol}. The \texttt{cycle}~factory receives a
-low-level filter, an initial context, and an extra
-parameter, and returns a new high-level filter.  Each time
-the high-level filer is passed a new chunk, it invokes the
-low-level filter with the previous context, the new chunk,
-and the extra argument.  It is the low-level filter that
-does all the work, producing the chunk of processed data and
-a new context. The high-level filter then replaces its
-internal context, and returns the processed chunk of data to
-the user.  Notice that we take advantage of Lua's lexical
-scoping to store the context in a closure between function
-calls.  
-
-\subsection{The C part of the filter}
-
-As for the low-level filter, we must first accept
-that there is no perfect solution to the end-of-line marker
-normalization problem. The difficulty comes from an
-inherent ambiguity in the definition of empty lines within
-mixed input. However, the following solution works well for
-any consistent input, as well as for non-empty lines in
-mixed input. It also does a reasonable job with empty lines
-and serves as a good example of how to implement a low-level
-filter.
-
-The idea is to consider both \CR\ and~\LF\ as end-of-line
-\emph{candidates}.  We issue a single break if any candidate
-is seen alone, or if it is followed by a different
-candidate.  In other words, \CR~\CR~and \LF~\LF\ each issue
-two end-of-line markers, whereas \CR~\LF~and \LF~\CR\ issue
-only one marker each.  It is easy to see that this method
-correctly handles the most common end-of-line conventions.
-
-With this in mind, we divide the low-level filter into two
-simple functions.  The inner function~\texttt{pushchar} performs the
-normalization itself. It takes each input character in turn,
-deciding what to output and how to modify the context. The
-context tells if the last processed character was an
-end-of-line candidate, and if so, which candidate it was.
-For efficiency, we use Lua's auxiliary library's buffer
-interface: 
-\begin{quote}
-\begin{C}
-@stick#
-@#define candidate(c) (c == CR || c == LF)
-static int pushchar(int c, int last, const char *marker, 
-    luaL_Buffer *buffer) {
-  if (candidate(c)) {
-    if (candidate(last)) {
-      if (c == last) 
-        luaL_addstring(buffer, marker);
-      return 0;
-    } else {
-      luaL_addstring(buffer, marker);
-      return c;
-    }
-  } else {
-    luaL_pushchar(buffer, c);
-    return 0;
-  }
-}
-%
-\end{C}
-\end{quote}
-
-The outer function~\texttt{eol} simply interfaces with Lua.
-It receives the context and input chunk (as well as an
-optional custom end-of-line marker), and returns the
-transformed output chunk and the new context.
-Notice that if the input chunk is \nil, the operation
-is considered to be finished. In that case, the loop will
-not execute a single time and the context is reset to the
-initial state.  This allows the filter to be reused many
-times: 
-\begin{quote}
-\begin{C}
-@stick#
-static int eol(lua_State *L) {
-  int context = luaL_checkint(L, 1);
-  size_t isize = 0;
-  const char *input = luaL_optlstring(L, 2, NULL, &isize);
-  const char *last = input + isize;
-  const char *marker = luaL_optstring(L, 3, CRLF);
-  luaL_Buffer buffer;
-  luaL_buffinit(L, &buffer);
-  if (!input) {
-    lua_pushnil(L);
-    lua_pushnumber(L, 0);
-    return 2;
-  }
-  while (input < last)
-    context = pushchar(*input++, context, marker, &buffer);
-  luaL_pushresult(&buffer);
-  lua_pushnumber(L, context);
-  return 2;
-}
-%
-\end{C}
-\end{quote}
-
-When designing filters, the challenging part is usually 
-deciding what to store in the context. For line breaking, for
-instance, it could be the number of bytes that still fit in the
-current line.  For Base64 encoding, it could be a string
-with the bytes that remain after the division of the input
-into 3-byte atoms. The MIME module in the \texttt{LuaSocket}
-distribution has many other examples. 
-
-\section{Filter chains}
-
-Chains greatly increase the power of filters.  For example,
-according to the standard for Quoted-Printable encoding,
-text should be normalized to a canonic end-of-line marker
-prior to encoding.  After encoding, the resulting text must
-be broken into lines of no more than 76 characters, with the
-use of soft line breaks (a line terminated by the \texttt{=}
-sign).  To help specifying complex transformations like
-this, we define a chain factory that creates a composite
-filter from one or more filters.  A chained filter passes
-data through all its components, and can be used wherever a
-primitive filter is accepted.
-
-The chaining factory is very simple. The auxiliary
-function~\texttt{chainpair} chains two filters together,
-taking special care if the chunk is the last.  This is
-because the final \nil\ chunk notification has to be
-pushed through both filters in turn:  
-\begin{quote}
-\begin{lua}
-@stick#
-local function chainpair(f1, f2)
-  return function(chunk)
-    local ret = f2(f1(chunk))
-    if chunk then return ret
-    else return ret .. f2() end
-  end
-end
-%
-
-@stick#
-function filter.chain(...)
-  local f = select(1, ...) 
-  for i = 2, select('@#', ...) do
-    f = chainpair(f, select(i, ...))
-  end
-  return f
-end
-%
-\end{lua}
-\end{quote}
-
-Thanks to the chain factory, we can
-define the Quoted-Printable conversion as such:
-\begin{quote}
-\begin{lua}
-@stick#
-local qp = filter.chain(normalize(CRLF), encode("quoted-printable"), 
-  wrap("quoted-printable"))
-local input = source.chain(source.file(io.stdin), qp)
-local output = sink.file(io.stdout)
-pump.all(input, output)
-%
-\end{lua}
-\end{quote}
-
-\section{Sources, sinks, and pumps}
-
-The filters we introduced so far act as the internal nodes
-in a network of transformations. Information flows from node
-to node (or rather from one filter to the next) and is
-transformed along the way. Chaining filters together is our
-way to connect nodes in this network. As the starting point
-for the network, we need a source node that produces the
-data. In the end of the network, we need a sink node that
-gives a final destination to the data.
-
-\subsection{Sources}
-
-A source returns the next chunk of data each time it is
-invoked. When there is no more data, it simply returns~\nil.  
-In the event of an error, the source can inform the
-caller by returning \nil\ followed by the error message.
-
-Below are two simple source factories. The \texttt{empty} source
-returns no data, possibly returning an associated error
-message. The \texttt{file} source yields the contents of a file 
-in a chunk by chunk fashion:
-\begin{quote}
-\begin{lua}
-@stick#
-function source.empty(err)
-  return function()
-    return nil, err
-  end
-end
-%
-
-@stick#
-function source.file(handle, io_err)
-  if handle then 
-    return function()
-      local chunk = handle:read(2048)
-      if not chunk then handle:close() end
-      return chunk
-    end
-  else return source.empty(io_err or "unable to open file") end
-end
-%
-\end{lua}
-\end{quote}
-
-\subsection{Filtered sources}
-
-A filtered source passes its data through the
-associated filter before returning it to the caller. 
-Filtered sources are useful when working with
-functions that get their input data from a source (such as
-the pumps in our examples). By chaining a source with one or
-more filters, such functions can be transparently provided
-with filtered data, with no need to change their interfaces. 
-Here is a factory that does the job:
-\begin{quote}
-\begin{lua}
-@stick#
-function source.chain(src, f)
-  return function()
-    if not src then 
-      return nil 
-    end
-    local chunk, err = src()
-    if not chunk then 
-      src = nil
-      return f(nil)
-    else 
-      return f(chunk) 
-    end
-  end
-end
-%
-\end{lua}
-\end{quote}
-
-\subsection{Sinks}
-
-Just as we defined an interface for a source of data, we can
-also define an interface for a data destination.  We call
-any function respecting this interface a sink. In our first
-example, we used a file sink connected to the standard
-output. 
-
-Sinks receive consecutive chunks of data, until the end of
-data is signaled by a \nil\ input chunk. A sink can be
-notified of an error with an optional extra argument that
-contains the error message, following a \nil\ chunk.  
-If a sink detects an error itself, and
-wishes not to be called again, it can return \nil,
-followed by an error message. A return value that
-is not \nil\ means the sink will accept more data.
-
-Below are two useful sink factories. 
-The table factory creates a sink that stores
-individual chunks into an array. The data can later be
-efficiently concatenated into a single string with Lua's
-\texttt{table.concat} library function. The \texttt{null} sink 
-simply discards the chunks it receives:
-\begin{quote}
-\begin{lua}
-@stick#
-function sink.table(t)
-  t = t or {}
-  local f = function(chunk, err)
-    if chunk then table.insert(t, chunk) end
-    return 1
-  end
-  return f, t
-end
-%
-
-@stick#
-local function null()
-  return 1
-end
-
-function sink.null()
-  return null
-end
-%
-\end{lua}
-\end{quote}
-
-Naturally, filtered sinks are just as useful as filtered
-sources. A filtered sink passes each chunk it receives
-through the associated filter before handing it down to the
-original sink.  In the following example, we use a source
-that reads from the standard input.  The input chunks are
-sent to a table sink, which has been coupled with a
-normalization filter.  The filtered chunks are then
-concatenated from the output array, and finally sent to
-standard out:
-\begin{quote}
-\begin{lua}
-@stick#
-local input = source.file(io.stdin)
-local output, t = sink.table()
-output = sink.chain(normalize(CRLF), output)
-pump.all(input, output)
-io.write(table.concat(t))
-%
-\end{lua}
-\end{quote}
-
-\subsection{Pumps}
-
-Although not on purpose, our interface for sources is
-compatible with Lua iterators. That is, a source can be
-neatly used in conjunction with \texttt{for} loops.  Using
-our file source as an iterator, we can write the following
-code:
-\begin{quote}
-\begin{lua}
-@stick#
-for chunk in source.file(io.stdin) do
-  io.write(chunk)
-end
-%
-\end{lua}
-\end{quote}
-
-Loops like this will always be present because everything 
-we designed so far is passive. Sources, sinks, filters: none
-of them can do anything on their own. The operation of
-pumping all data a source can provide into a sink is so
-common that it deserves its own function:
-\begin{quote}
-\begin{lua}
-@stick#
-function pump.step(src, snk)
-  local chunk, src_err = src()
-  local ret, snk_err = snk(chunk, src_err)
-  if chunk and ret then return 1
-  else return nil, src_err or snk_err end
-end
-%
-
-@stick#
-function pump.all(src, snk, step)
-    step = step or pump.step
-    while true do
-        local ret, err = step(src, snk)
-        if not ret then
-            if err then return nil, err
-            else return 1 end
-        end 
-    end
-end
-%
-\end{lua}
-\end{quote}
-
-The \texttt{pump.step} function moves one chunk of data from
-the source to the sink. The \texttt{pump.all} function takes
-an optional \texttt{step} function and uses it to pump all the
-data from the source to the sink. 
-Here is an example that uses the Base64 and the
-line wrapping filters from the \texttt{LuaSocket}
-distribution.  The program reads a binary file from
-disk and stores it in another file, after encoding it to the
-Base64 transfer content encoding:
-\begin{quote}
-\begin{lua}
-@stick#
-local input = source.chain(
-  source.file(io.open("input.bin", "rb")), 
-  encode("base64"))
-local output = sink.chain(
-  wrap(76),
-  sink.file(io.open("output.b64", "w")))
-pump.all(input, output)
-%
-\end{lua}
-\end{quote}
-
-The way we split the filters here is not intuitive, on
-purpose.  Alternatively, we could have chained the Base64
-encode filter and the line-wrap filter together, and then
-chain the resulting filter with either the file source or
-the file sink. It doesn't really matter. 
-
-\section{Exploding filters}
-
-Our current filter interface has one serious shortcoming.
-Consider for example a \texttt{gzip} decompression filter.
-During decompression, a small input chunk can be exploded
-into a huge amount of data. To address this problem, we
-decided to change the filter interface and allow exploding
-filters to return large quantities of output data in a chunk
-by chunk manner. 
-
-More specifically, after passing each chunk of input to
-a filter, and collecting the first chunk of output, the
-user must now loop to receive other chunks from the filter until no
-filtered data is left. Within these secondary calls, the
-caller passes an empty string to the filter. The filter
-responds with an empty string when it is ready for the next
-input chunk. In the end, after the user passes a
-\nil\ chunk notifying the filter that there is no
-more input data, the filter might still have to produce too
-much output data to return in a single chunk. The user has
-to loop again, now passing \nil\ to the filter each time,
-until the filter itself returns \nil\ to notify the
-user it is finally done.
-
-Fortunately, it is very easy to modify a filter to respect
-the new interface. In fact, the end-of-line translation
-filter we presented earlier already conforms to it.  The
-complexity is encapsulated within the chaining functions,
-which must now include a loop. Since these functions only
-have to be written once, the user is rarely affected.
-Interestingly, the modifications do not have a measurable
-negative impact in the performance of filters that do
-not need the added flexibility. On the other hand, for a
-small price in complexity, the changes make exploding
-filters practical.
-
-\section{A complex example}
-
-The LTN12 module in the \texttt{LuaSocket} distribution
-implements all the ideas we have described. The MIME
-and SMTP modules are tightly integrated with LTN12, 
-and can be used to showcase the expressive power of filters,
-sources, sinks, and pumps. Below is an example 
-of how a user would proceed to define and send a
-multipart message, with attachments, using \texttt{LuaSocket}:
-\begin{quote}
-\begin{mime}
-local smtp = require"socket.smtp"
-local mime = require"mime"
-local ltn12 = require"ltn12"
-
-local message = smtp.message{
-  headers = {
-    from = "Sicrano <sicrano@example.com>",
-    to = "Fulano <fulano@example.com>",
-    subject = "A message with an attachment"},
-  body = {
-    preamble = "Hope you can see the attachment" .. CRLF,
-    [1] = {
-      body = "Here is our logo" .. CRLF},
-    [2] = {
-      headers = {
-        ["content-type"] = 'image/png; name="luasocket.png"',
-        ["content-disposition"] = 
-          'attachment; filename="luasocket.png"',
-        ["content-description"] = 'LuaSocket logo',
-        ["content-transfer-encoding"] = "BASE64"},
-      body = ltn12.source.chain(
-        ltn12.source.file(io.open("luasocket.png", "rb")),
-        ltn12.filter.chain(
-          mime.encode("base64"),
-          mime.wrap()))}}}
-
-assert(smtp.send{
-  rcpt = "<fulano@example.com>",
-  from = "<sicrano@example.com>",
-  source = message})
-\end{mime}
-\end{quote}
-
-The \texttt{smtp.message} function receives a table
-describing the message, and returns a source. The
-\texttt{smtp.send} function takes this source, chains it with the
-SMTP dot-stuffing filter, connects a socket sink
-with the server, and simply pumps the data. The message is never 
-assembled in memory.  Everything is produced on demand, 
-transformed in small pieces, and sent to the server in chunks, 
-including the file attachment which is loaded from disk and 
-encoded on the fly. It just works.
-
-\section{Conclusions}
-
-In this article, we introduced the concepts of filters,
-sources, sinks, and pumps to the Lua language. These are
-useful tools for stream processing in general. Sources provide
-a simple abstraction for data acquisition. Sinks provide an
-abstraction for final data destinations. Filters define an
-interface for data transformations.  The chaining of
-filters, sources and sinks provides an elegant way to create
-arbitrarily complex data transformations from simpler
-components. Pumps simply push the data through.  
-
-\section{Acknowledgements}
-
-The concepts described in this text are the result of  long
-discussions with David Burgess. A version of this text has
-been released on-line as the Lua Technical Note 012, hence
-the name of the corresponding LuaSocket module, LTN12.  Wim
-Couwenberg contributed to the implementation of the module,
-and Adrian Sietsma was the first to notice the
-correspondence between sources and Lua iterators. 
-
-
-\end{document}

gem/makefile

@@ -1,14 +0,0 @@
-ltn012.pdf: ltn012.ps
-	./myps2pdf ltn012.ps
-
-ltn012.ps: ltn012.dvi
-	dvips -G0 -t letter -o ltn012.ps ltn012.dvi
-
-ltn012.dvi: ltn012.tex
-	latex ltn012
-
-clean:
-	rm -f *~ *.log *.aux *.bbl *.blg ltn012.pdf ltn012.ps ltn012.dvi ltn012.lof ltn012.toc ltn012.lot
-
-pdf: ltn012.pdf
-	open ltn012.pdf

gem/myps2pdf

@@ -1,113 +0,0 @@
-#!/bin/sh -
-do_opt=1
-best=0
-rot=0
-a4=0
-eps=0
-usage="Usage: $0 [-no_opt] [-best] [-rot] [-a4] [-eps] in.ps [out.pdf]"
-
-case "x$1" in
-"x-no_opt") do_opt=0 ; shift ;;
-esac
-
-case "x$1" in
-"x-best") best=1 ; shift ;;
-esac
-
-case "x$1" in
-"x-rot") rot=1 ; shift ;;
-esac
-
-case "x$1" in
-"x-a4") a4=1 ; shift ;;
-esac
-
-case "x$1" in
-"x-eps") eps=1 ; shift ;;
-esac
-
-case $# in
-2) ifilename=$1 ; ofilename=$2 ;;
-1) ifilename=$1
-   if `echo $1 | grep -i '\.e*ps$' > /dev/null`
-   then
-      ofilename=`echo $1 | sed 's/\..*$/.pdf/'`
-   else
-      echo "$usage" 1>&2
-      exit 1
-   fi ;;
-*) echo "$usage" 1>&2 ; exit 1 ;;
-esac
-
-if [ $best == 1 ]
-then
-	options="-dPDFSETTINGS=/prepress \
-	-r1200 \
-	-dMonoImageResolution=1200 \
-	-dGrayImageResolution=1200 \
-	-dColorImageResolution=1200 \
-	-dDownsampleMonoImages=false \
-	-dDownsampleGrayImages=false \
-	-dDownsampleColorImages=false \
-	-dAutoFilterMonoImages=false \
-	-dAutoFilterGrayImages=false \
-	-dAutoFilterColorImages=false \
-	-dMonoImageFilter=/FlateEncode \
-	-dGrayImageFilter=/FlateEncode \
-	-dColorImageFilter=/FlateEncode"
-else
-	options="-dPDFSETTINGS=/prepress \
-	-r600 \
-	-dDownsampleMonoImages=true \
-	-dDownsampleGrayImages=true \
-	-dDownsampleColorImages=true \
-	-dMonoImageDownsampleThreshold=2.0 \
-	-dGrayImageDownsampleThreshold=1.5 \
-	-dColorImageDownsampleThreshold=1.5 \
-	-dMonoImageResolution=600 \
-	-dGrayImageResolution=600 \
-	-dColorImageResolution=600 \
-	-dAutoFilterMonoImages=false \
-	-dMonoImageFilter=/FlateEncode \
-	-dAutoFilterGrayImages=true \
-	-dAutoFilterColorImages=true"
-fi
-
-if [ $rot == 1 ]
-then
-	options="$options -dAutoRotatePages=/PageByPage"
-fi
-
-if [ $eps == 1 ]
-then
-	options="$options -dEPSCrop"
-fi
-
-set -x
-
-if [ $a4 == 1 ]
-then
-	# Resize from A4 to letter size
-	psresize -Pa4 -pletter "$ifilename" myps2pdf.temp.ps
-	ifilename=myps2pdf.temp.ps
-fi
-
-gs -q -dSAFER -dNOPAUSE -dBATCH  \
-	-sDEVICE=pdfwrite -sPAPERSIZE=letter -sOutputFile=myps2pdf.temp.pdf \
-	-dCompatibilityLevel=1.3 \
-	$options \
-	-dMaxSubsetPct=100 \
-	-dSubsetFonts=true \
-	-dEmbedAllFonts=true \
-	-dColorConversionStrategy=/LeaveColorUnchanged \
-	-dDoThumbnails=true \
-	-dPreserveEPSInfo=true \
-	-c .setpdfwrite -f "$ifilename"
-
-if [ $do_opt == 1 ]
-then
-	pdfopt myps2pdf.temp.pdf $ofilename
-else
-	mv myps2pdf.temp.pdf $ofilename
-fi
-rm -f myps2pdf.temp.pdf myps2pdf.temp.ps

gem/t1.lua

@@ -1,25 +0,0 @@
-source = {}
-sink = {}
-pump = {}
-filter = {}
-
--- source.chain
-dofile("ex6.lua")
-
--- source.file
-dofile("ex5.lua")
-
--- normalize
-require"gem"
-eol = gem.eol
-dofile("ex2.lua")
-
--- sink.file
-require"ltn12"
-sink.file = ltn12.sink.file
-
--- pump.all
-dofile("ex10.lua")
-
--- run test
-dofile("ex1.lua")

gem/t1lf.txt

@@ -1,5 +0,0 @@
-this is a test file
-it should have been saved as lf eol
-but t1.lua will convert it to crlf eol
-otherwise it is broken!
-

gem/t2.lua

@@ -1,36 +0,0 @@
-source = {}
-sink = {}
-pump = {}
-filter = {}
-
--- filter.chain
-dofile("ex3.lua")
-
--- normalize
-require"gem"
-eol = gem.eol
-dofile("ex2.lua")
-
--- encode
-require"mime"
-encode = mime.encode
-
--- wrap
-wrap = mime.wrap
-
--- source.chain
-dofile("ex6.lua")
-
--- source.file
-dofile("ex5.lua")
-
--- sink.file
-require"ltn12"
-sink.file = ltn12.sink.file
-
--- pump.all
-dofile("ex10.lua")
-
--- run test
-CRLF = "\013\010"
-dofile("ex4.lua")

gem/t2.txt

@@ -1,4 +0,0 @@
-esse é um texto com acentos
-quoted-printable tem que quebrar linhas longas, com mais que 76 linhas de texto
-fora que as quebras de linhas têm que ser normalizadas
-vamos ver o que dá isso aqui

gem/t2gt.qp

@@ -1,5 +0,0 @@
-esse =E9 um texto com acentos
-quoted-printable tem que quebrar linhas longas, com mais que 76 linhas de t=
-exto
-fora que as quebras de linhas t=EAm que ser normalizadas
-vamos ver o que d=E1 isso aqui

gem/t3.lua

@@ -1,25 +0,0 @@
-source = {}
-sink = {}
-pump = {}
-filter = {}
-
--- source.file
-dofile("ex5.lua")
-
--- sink.table
-dofile("ex7.lua")
-
--- sink.chain
-require"ltn12"
-sink.chain = ltn12.sink.chain
-
--- normalize
-require"gem"
-eol = gem.eol
-dofile("ex2.lua")
-
--- pump.all
-dofile("ex10.lua")
-
--- run test
-dofile("ex8.lua")

gem/t4.lua

@@ -1,10 +0,0 @@
-source = {}
-sink = {}
-pump = {}
-filter = {}
-
--- source.file
-dofile("ex5.lua")
-
--- run test
-dofile("ex9.lua")

gem/t5.lua

@@ -1,30 +0,0 @@
-source = {}
-sink = {}
-pump = {}
-filter = {}
-
--- source.chain
-dofile("ex6.lua")
-
--- source.file
-dofile("ex5.lua")
-
--- encode
-require"mime"
-encode = mime.encode
-
--- sink.chain
-require"ltn12"
-sink.chain = ltn12.sink.chain
-
--- wrap
-wrap = mime.wrap
-
--- sink.file
-sink.file = ltn12.sink.file
-
--- pump.all
-dofile("ex10.lua")
-
--- run test
-dofile("ex11.lua")

gem/test.lua

@@ -1,46 +0,0 @@
-function readfile(n)
-    local f = io.open(n, "rb")
-    local s = f:read("*a")
-    f:close()
-    return s
-end
-
-lf = readfile("t1lf.txt")
-os.remove("t1crlf.txt")
-os.execute("lua t1.lua < t1lf.txt > t1crlf.txt")
-crlf = readfile("t1crlf.txt")
-assert(crlf == string.gsub(lf, "\010", "\013\010"), "broken")
-
-gt = readfile("t2gt.qp")
-os.remove("t2.qp")
-os.execute("lua t2.lua < t2.txt > t2.qp")
-t2 = readfile("t2.qp")
-assert(gt == t2, "broken")
-
-os.remove("t1crlf.txt")
-os.execute("lua t3.lua < t1lf.txt > t1crlf.txt")
-crlf = readfile("t1crlf.txt")
-assert(crlf == string.gsub(lf, "\010", "\013\010"), "broken")
-
-t = readfile("test.lua")
-os.execute("lua t4.lua < test.lua > t")
-t2 = readfile("t")
-assert(t == t2, "broken")
-
-os.remove("output.b64")
-gt = readfile("gt.b64")
-os.execute("lua t5.lua")
-t5 = readfile("output.b64")
-assert(gt == t5, "failed")
-
-print("1 2 5 6 10 passed")
-print("2 3 4 5 6 10 passed")
-print("2 5 6 7 8 10 passed")
-print("5 9 passed")
-print("5 6 10 11 passed")
-
-os.remove("t")
-os.remove("t2.qp")
-os.remove("t1crlf.txt")
-os.remove("t11.b64")
-os.remove("output.b64")

ltn012.md

@@ -0,0 +1,390 @@
+# Filters, sources and sinks: design, motivation and examples
+### or Functional programming for the rest of us
+by DiegoNehab
+
+## Abstract
+
+Certain operations can be implemented in the form of filters. A filter is a function that processes data received in consecutive function calls, returning partial results chunk by chunk. Examples of operations that can be implemented as filters include the end-of-line normalization for text, Base64 and Quoted-Printable transfer content encodings, the breaking of text into lines, SMTP byte stuffing, and there are many others. Filters become even more powerful when we allow them to be chained together to create composite filters. Filters can be seen as middle nodes in a chain of data transformations. Sources an sinks are the corresponding end points of these chains. A source is a function that produces data, chunk by chunk, and a sink is a function that takes data, chunk by chunk. In this technical note, we define an elegant interface for filters, sources, sinks and chaining. We evolve our interface progressively, until we reach a high degree of generality. We discuss difficulties that arise during the implementation of this interface and we provide solutions and examples.
+
+## Introduction
+
+Applications sometimes have too much information to process to fit in memory and are thus forced to process data in smaller parts. Even when there is enough memory, processing all the data atomically may take long enough to frustrate a user that wants to interact with the application. Furthermore, complex transformations can often be defined as series of simpler operations. Several different complex transformations might share the same simpler operations, so that an uniform interface to combine them is desirable. The following concepts constitute our solution to these problems.
+
+"Filters" are functions that accept successive chunks of input, and produce successive chunks of output. Furthermore, the result of concatenating all the output data is the same as the result of applying the filter over the concatenation of the input data. As a consequence, boundaries are irrelevant: filters have to handle input data split arbitrarily by the user.
+
+A "chain" is a function that combines the effect of two (or more) other functions, but whose interface is indistinguishable from the interface of one of its components. Thus, a chained filter can be used wherever an atomic filter can be used. However, its effect on data is the combined effect of its component filters. Note that, as a consequence, chains can be chained themselves to create arbitrarily complex operations that can be used just like atomic operations.
+
+Filters can be seen as internal nodes in a network through which data flows, potentially being transformed along its way. Chains connect these nodes together. To complete the picture, we need "sources" and "sinks" as initial and final nodes of the network, respectively. Less abstractly, a source is a function that produces new data every time it is called. On the other hand, sinks are functions that give a final destination to the data they receive. Naturally, sources and sinks can be chained with filters.
+
+Finally, filters, chains, sources, and sinks are all passive entities: they need to be repeatedly called in order for something to happen. "Pumps" provide the driving force that pushes data through the network, from a source to a sink.
+
+ Hopefully, these concepts will become clear with examples. In the following sections, we start with simplified interfaces, which we improve several times until we can find no obvious shortcomings. The evolution we present is not contrived: it follows the steps we followed ourselves as we consolidated our understanding of these concepts.
+
+### A concrete example
+
+Some data transformations are easier to implement as filters than others. Examples of operations that can be implemented as filters include the end-of-line normalization for text, the Base64 and Quoted-Printable transfer content encodings, the breaking of text into lines, SMTP byte stuffing, and many others. Let's use the end-of-line normalization as an example to define our initial filter interface. We later discuss why the implementation might not be trivial.
+
+Assume we are given text in an unknown end-of-line convention (including possibly mixed conventions) out of the commonly found Unix (LF), Mac OS (CR), and DOS (CRLF) conventions. We would like to be able to write code like the following:
+```lua
+input = source.chain(source.file(io.stdin), normalize("\r\n"))
+output = sink.file(io.stdout)
+pump(input, output)
+```
+
+This program should read data from the standard input stream and normalize the end-of-line markers to the canonic CRLF marker defined by the MIME standard, finally sending the results to the standard output stream. For that, we use a "file source" to produce data from standard input, and chain it with a filter that normalizes the data. The pump then repeatedly gets data from the source, and moves it to the "file sink" that sends it to standard output.
+
+To make the discussion even more concrete, we start by discussing the implementation of the normalization filter. The `normalize` "factory" is a function that creates such a filter. Our initial filter interface is as follows: the filter receives a chunk of input data, and returns a chunk of processed data. When there is no more input data, the user notifies the filter by invoking it with a `nil` chunk. The filter then returns the final chunk of processed data.
+
+Although the interface is extremely simple, the implementation doesn't seem so obvious. Any filter respecting this interface needs to keep some kind of context between calls. This is because chunks can be broken between the CR and LF characters marking the end of a line. This need for context storage is what motivates the use of factories: each time the factory is called, it returns a filter with its own context so that we can have several independent filters being used at the same time. For the normalization filter, we know that the obvious solution (i.e. concatenating all the input into the context before producing any output) is not good enough, so we will have to find another way.
+
+We will break the implementation in two parts: a low-level filter, and a factory of high-level filters. The low-level filter will be implemented in C and will not carry any context between function calls. The high-level filter factory, implemented in Lua, will create and return a high-level filter that keeps whatever context the low-level filter needs, but isolates the user from its internal details. That way, we take advantage of C's efficiency to perform the dirty work, and take advantage of Lua's simplicity for the bookkeeping.
+
+### The Lua part of the implementation
+
+Below is the implementation of the factory of high-level end-of-line normalization filters:
+```lua
+function filter.cycle(low, ctx, extra)
+    return function(chunk)
+        local ret
+        ret, ctx = low(ctx, chunk, extra)
+        return ret
+    end
+end
+
+function normalize(marker)
+    return cycle(eol, 0, marker)
+end
+```
+
+The `normalize` factory simply calls a more generic factory, the `cycle` factory. This factory receives a low-level filter, an initial context and some extra value and returns the corresponding high-level filter. Each time the high level filer is called with a new chunk, it calls the low-level filter passing the previous context, the new chunk and the extra argument. The low-level filter produces the chunk of processed data and a new context. Finally, the high-level filter updates its internal context and returns the processed chunk of data to the user. It is the low-level filter that does all the work. Notice that this implementation takes advantage of the Lua 5.0 lexical scoping rules to store the context locally, between function calls.
+
+Moving to the low-level filter, we notice there is no perfect solution to the end-of-line marker normalization problem itself. The difficulty comes from an inherent ambiguity on the definition of empty lines within mixed input. However, the following solution works well for any consistent input, as well as for non-empty lines in mixed input. It also does a reasonable job with empty lines and serves as a good example of how to implement a low-level filter.
+
+Here is what we do: CR and LF are considered candidates for line break. We issue "one" end-of-line line marker if one of the candidates is seen alone, or followed by a "different" candidate. That is, CR CR and LF LF issue two end of line markers each, but CR LF and LF CR issue only one marker. This idea takes care of Mac OS, Mac OS X, VMS and Unix, DOS and MIME, as well as probably other more obscure conventions.
+
+### The C part of the implementation
+
+The low-level filter is divided into two simple functions. The inner function actually does the conversion. It takes each input character in turn, deciding what to output and how to modify the context. The context tells if the last character seen was a candidate and, if so, which candidate it was.
+```c
+#define candidate(c) (c == CR || c == LF)
+static int process(int c, int last, const char *marker, luaL_Buffer *buffer) {
+    if (candidate(c)) {
+        if (candidate(last)) {
+            if (c == last) luaL_addstring(buffer, marker);
+            return 0;
+        } else {
+            luaL_addstring(buffer, marker);
+            return c;
+        }
+    } else {
+        luaL_putchar(buffer, c);
+        return 0;
+    }
+}
+```
+
+The inner function makes use of Lua's auxiliary library's buffer interface for its efficiency and ease of use. The outer function simply interfaces with Lua. It receives the context and the input chunk (as well as an optional end-of-line marker), and returns the transformed output and the new context.
+```c
+static int eol(lua_State *L) {
+    int ctx = luaL_checkint(L, 1);
+    size_t isize = 0;
+    const char *input = luaL_optlstring(L, 2, NULL, &isize);
+    const char *last = input + isize;
+    const char *marker = luaL_optstring(L, 3, CRLF);
+    luaL_Buffer buffer;
+    luaL_buffinit(L, &buffer);
+    if (!input) {
+       lua_pushnil(L);
+       lua_pushnumber(L, 0);
+       return 2;
+    }
+    while (input < last)
+        ctx = process(*input++, ctx, marker, &buffer);
+    luaL_pushresult(&buffer);
+    lua_pushnumber(L, ctx);
+    return 2;
+}
+```
+
+Notice that if the input chunk is `nil`, the operation is considered to be finished. In that case, the loop will not execute a single time and the context is reset to the initial state. This allows the filter to be reused indefinitely. It is a good idea to write filters like this, when possible.
+
+Besides the end-of-line normalization filter shown above, many other filters can be implemented with the same ideas. Examples include Base64 and Quoted-Printable transfer content encodings, the breaking of text into lines, SMTP byte stuffing etc. The challenging part is to decide what will be the context. For line breaking, for instance, it could be the number of bytes left in the current line. For Base64 encoding, it could be the bytes that remain in the division of the input into 3-byte atoms.
+
+## Chaining
+
+Filters become more powerful when the concept of chaining is introduced. Suppose you have a filter for Quoted-Printable encoding and you want to encode some text. According to the standard, the text has to be normalized into its canonic form prior to encoding. A nice interface that simplifies this task is a factory that creates a composite filter that passes data through multiple filters, but that can be used wherever a primitive filter is used.
+```lua
+local function chain2(f1, f2)
+    return function(chunk)
+        local ret = f2(f1(chunk))
+        if chunk then return ret
+        else return ret .. f2() end
+    end
+end
+
+function filter.chain(...)
+    local arg = {...}
+    local f = arg[1]
+    for i = 2, #arg do
+        f = chain2(f, arg[i])
+    end
+    return f
+end
+
+local chain = filter.chain(normalize("\r\n"), encode("quoted-printable"))
+while 1 do
+    local chunk = io.read(2048)
+    io.write(chain(chunk))
+    if not chunk then break end
+end
+```
+
+The chaining factory is very simple. All it does is return a function that passes data through all filters and returns the result to the user. It uses the simpler auxiliary function that knows how to chain two filters together. In the auxiliary function, special care must be taken if the chunk is final. This is because the final chunk notification has to be pushed through both filters in turn. Thanks to the chain factory, it is easy to perform the Quoted-Printable conversion, as the above example shows.
+
+## Sources, sinks, and pumps
+
+As we noted in the introduction, the filters we introduced so far act as the internal nodes in a network of transformations. Information flows from node to node (or rather from one filter to the next) and is transformed on its way out. Chaining filters together is the way we found to connect nodes in the network. But what about the end nodes?  In the beginning of the network, we need a node that provides the data, a source. In the end of the network, we need a node that takes in the data, a sink.
+
+### Sources
+
+We start with two simple sources. The first is the `empty` source: It simply returns no data, possibly returning an error message. The second is the `file` source, which produces the contents of a file in a chunk by chunk fashion, closing the file handle when done.
+```lua
+function source.empty(err)
+    return function()
+        return nil, err
+    end
+end
+
+function source.file(handle, io_err)
+    if handle then
+        return function()
+            local chunk = handle:read(2048)
+            if not chunk then handle:close() end
+            return chunk
+        end
+    else return source.empty(io_err or "unable to open file") end
+end
+```
+
+A source returns the next chunk of data each time it is called. When there is no more data, it just returns `nil`. If there is an error, the source can inform the caller by returning `nil` followed by an error message. Adrian Sietsma noticed that, although not on purpose, the interface for sources is compatible with the idea of iterators in Lua 5.0. That is, a data source can be nicely used in conjunction with `for` loops. Using our file source as an iterator, we can rewrite our first example:
+```lua
+local process = normalize("\r\n")
+for chunk in source.file(io.stdin) do
+    io.write(process(chunk))
+end
+io.write(process(nil))
+```
+
+Notice that the last call to the filter obtains the last chunk of processed data. The loop terminates when the source returns `nil` and therefore we need that final call outside of the loop.
+
+### Maintaining state between calls
+
+It is often the case that a source needs to change its behavior after some event. One simple example would be a file source that wants to make sure it returns `nil` regardless of how many times it is called after the end of file, avoiding attempts to read past the end of the file. Another example would be a source that returns the contents of several files, as if they were concatenated, moving from one file to the next until the end of the last file is reached.
+
+One way to implement this kind of source is to have the factory declare extra state variables that the source can use via lexical scoping. Our file source could set the file handle itself to `nil` when it detects the end-of-file. Then, every time the source is called, it could check if the handle is still valid and act accordingly:
+```lua
+function source.file(handle, io_err)
+    if handle then
+        return function()
+            if not handle then return nil end
+            local chunk = handle:read(2048)
+            if not chunk then
+                handle:close()
+                handle = nil
+            end
+            return chunk
+        end
+    else return source.empty(io_err or "unable to open file") end
+end
+```
+
+Another way to implement this behavior involves a change in the source interface to makes it more flexible. Let's allow a source to return a second value, besides the next chunk of data. If the returned chunk is `nil`, the extra return value tells us what happened. A second `nil` means that there is just no more data and the source is empty. Any other value is considered to be an error message. On the other hand, if the chunk was "not" `nil`, the second return value tells us whether the source wants to be replaced. If it is `nil`, we should proceed using the same source. Otherwise it has to be another source, which we have to use from then on, to get the remaining data.
+
+This extra freedom is good for someone writing a source function, but it is a pain for those that have to use it. Fortunately, given one of these "fancy" sources, we can transform it into a simple source that never needs to be replaced, using the following factory.
+```lua
+function source.simplify(src)
+    return function()
+        local chunk, err_or_new = src()
+        src = err_or_new or src
+        if not chunk then return nil, err_or_new
+        else return chunk end
+    end
+end
+```
+
+The simplification factory allows us to write fancy sources and use them as if they were simple. Therefore, our next functions will only produce simple sources, and functions that take sources will assume they are simple.
+
+Going back to our file source, the extended interface allows for a more elegant implementation. The new source just asks to be replaced by an empty source as soon as there is no more data. There is no repeated checking of the handle. To make things simpler to the user, the factory itself simplifies the the fancy file source before returning it to the user:
+```lua
+function source.file(handle, io_err)
+    if handle then
+        return source.simplify(function()
+            local chunk = handle:read(2048)
+            if not chunk then
+                handle:close()
+                return "", source.empty()
+            end
+            return chunk
+        end)
+    else return source.empty(io_err or "unable to open file") end
+end
+```
+
+We can make these ideas even more powerful if we use a new feature of Lua 5.0: coroutines. Coroutines suffer from a great lack of advertisement, and I am going to play my part here. Just like lexical scoping, coroutines taste odd at first, but once you get used with the concept, it can save your day. I have to admit that using coroutines to implement our file source would be overkill, so let's implement a concatenated source factory instead.
+```lua
+function source.cat(...)
+    local arg = {...}
+    local co = coroutine.create(function()
+        local i = 1
+        while i <= #arg do
+            local chunk, err = arg[i]()
+            if chunk then coroutine.yield(chunk)
+            elseif err then return nil, err
+            else i = i + 1 end
+        end
+    end)
+    return function()
+        return shift(coroutine.resume(co))
+    end
+end
+```
+
+The factory creates two functions. The first is an auxiliary that does all the work, in the form of a coroutine. It reads a chunk from one of the sources. If the chunk is `nil`, it moves to the next source, otherwise it just yields returning the chunk. When it is resumed, it continues from where it stopped and tries to read the next chunk. The second function is the source itself, and just resumes the execution of the auxiliary coroutine, returning to the user whatever chunks it returns (skipping the first result that tells us if the coroutine terminated). Imagine writing the same function without coroutines and you will notice the simplicity of this implementation. We will use coroutines again when we make the filter interface more powerful.
+
+### Chaining Sources
+
+What does it mean to chain a source with a filter?  The most useful interpretation is that the combined source-filter is a new source that produces data and passes it through the filter before returning it. Here is a factory that does it:
+```lua
+function source.chain(src, f)
+    return source.simplify(function()
+        local chunk, err = src()
+        if not chunk then return f(nil), source.empty(err)
+        else return f(chunk) end
+    end)
+end
+```
+
+Our motivating example in the introduction chains a source with a filter. The idea of chaining a source with a filter is useful when one thinks about functions that might get their input data from a source. By chaining a simple source with one or more filters, the same function can be provided with filtered data even though it is unaware of the filtering that is happening behind its back.
+
+### Sinks
+
+Just as we defined an interface for an initial source of data, we can also define an interface for a final destination of data. We call any function respecting that interface a "sink". Below are two simple factories that return sinks. The table factory creates a sink that stores all obtained data into a table. The data can later be efficiently concatenated into a single string with the `table.concat` library function. As another example, we introduce the `null` sink: A sink that simply discards the data it receives.
+```lua
+function sink.table(t)
+    t = t or {}
+    local f = function(chunk, err)
+        if chunk then table.insert(t, chunk) end
+        return 1
+    end
+    return f, t
+end
+
+local function null()
+    return 1
+end
+
+function sink.null()
+    return null
+end
+```
+
+Sinks receive consecutive chunks of data, until the end of data is notified with a `nil` chunk. An error is notified by an extra argument giving an error message after the `nil` chunk. If a sink detects an error itself and wishes not to be called again, it should return `nil`, optionally followed by an error message. A return value that is not `nil` means the source will accept more data. Finally, just as sources can choose to be replaced, so can sinks, following the same interface. Once again, it is easy to implement a `sink.simplify` factory that transforms a fancy sink into a simple sink.
+
+As an example, let's create a source that reads from the standard input, then chain it with a filter that normalizes the end-of-line convention and let's use a sink to place all data into a table, printing the result in the end.
+```lua
+local load = source.chain(source.file(io.stdin), normalize("\r\n"))
+local store, t = sink.table()
+while 1 do
+    local chunk = load()
+    store(chunk)
+    if not chunk then break end
+end
+print(table.concat(t))
+```
+
+Again, just as we created a factory that produces a chained source-filter from a source and a filter, it is easy to create a factory that produces a new sink given a sink and a filter. The new sink passes all data it receives through the filter before handing it in to the original sink. Here is the implementation:
+```lua
+function sink.chain(f, snk)
+    return function(chunk, err)
+        local r, e = snk(f(chunk))
+        if not r then return nil, e end
+        if not chunk then return snk(nil, err) end
+        return 1
+    end
+end
+```
+
+### Pumps
+
+There is a while loop that has been around for too long in our examples. It's always there because everything that we designed so far is passive. Sources, sinks, filters: None of them will do anything on their own. The operation of pumping all data a source can provide into a sink is so common that we will provide a couple helper functions to do that for us.
+```lua
+function pump.step(src, snk)
+    local chunk, src_err = src()
+    local ret, snk_err = snk(chunk, src_err)
+    return chunk and ret and not src_err and not snk_err, src_err or snk_err
+end
+
+function pump.all(src, snk, step)
+    step = step or pump.step
+    while true do
+        local ret, err = step(src, snk)
+        if not ret then return not err, err end
+    end
+end
+```
+
+The `pump.step` function moves one chunk of data from the source to the sink. The `pump.all` function takes an optional `step` function and uses it to pump all the data from the source to the sink. We can now use everything we have to write a program that reads a binary file from disk and stores it in another file, after encoding it to the Base64 transfer content encoding:
+```lua
+local load = source.chain(
+    source.file(io.open("input.bin", "rb")),
+    encode("base64")
+)
+local store = sink.chain(
+    wrap(76),
+    sink.file(io.open("output.b64", "w")),
+)
+pump.all(load, store)
+```
+
+The way we split the filters here is not intuitive, on purpose. Alternatively, we could have chained the Base64 encode filter and the line-wrap filter together, and then chain the resulting filter with either the file source or the file sink. It doesn't really matter.
+
+## One last important change
+
+Turns out we still have a problem. When David Burgess was writing his gzip filter, he noticed that the decompression filter can explode a small input chunk into a huge amount of data. Although we wished we could ignore this problem, we soon agreed we couldn't. The only solution is to allow filters to return partial results, and that is what we chose to do. After invoking the filter to pass input data, the user now has to loop invoking the filter to find out if it has more output data to return. Note that these extra calls can't pass more data to the filter.
+
+More specifically, after passing a chunk of input data to a filter and collecting the first chunk of output data, the user invokes the filter repeatedly, passing the empty string, to get extra output chunks. When the filter itself returns an empty string, the user knows there is no more output data, and can proceed to pass the next input chunk. In the end, after the user passes a `nil` notifying the filter that there is no more input data, the filter might still have produced too much output data to return in a single chunk. The user has to loop again, this time passing `nil` each time, until the filter itself returns `nil` to notify the user it is finally done.
+
+Most filters won't need this extra freedom. Fortunately, the new filter interface is easy to implement. In fact, the end-of-line translation filter we created in the introduction already conforms to it. On the other hand, the chaining function becomes much more complicated. If it wasn't for coroutines, I wouldn't be happy to implement it. Let me know if you can find a simpler implementation that does not use coroutines!
+```lua
+local function chain2(f1, f2)
+    local co = coroutine.create(function(chunk)
+        while true do
+            local filtered1 = f1(chunk)
+            local filtered2 = f2(filtered1)
+            local done2 = filtered1 and ""
+            while true do
+                if filtered2 == "" or filtered2 == nil then break end
+                coroutine.yield(filtered2)
+                filtered2 = f2(done2)
+            end
+            if filtered1 == "" then chunk = coroutine.yield(filtered1)
+            elseif filtered1 == nil then return nil
+            else chunk = chunk and "" end
+        end
+    end)
+    return function(chunk)
+        local _, res = coroutine.resume(co, chunk)
+        return res
+    end
+end
+```
+
+Chaining sources also becomes more complicated, but a similar solution is possible with coroutines. Chaining sinks is just as simple as it has always been. Interestingly, these modifications do not have a measurable negative impact in the the performance of filters that didn't need the added flexibility. They do severely improve the efficiency of filters like the gzip filter, though, and that is why we are keeping them.
+
+## Final considerations
+
+These ideas were created during the development of [LuaSocket](https://github.com/lunarmodules/luasocket) 2.0, and are available as the LTN12 module. As a result, [LuaSocket](https://github.com/lunarmodules/luasocket) implementation was greatly simplified and became much more powerful. The MIME module is especially integrated to LTN12 and provides many other filters. We felt these concepts deserved to be made public even to those that don't care about [LuaSocket](https://github.com/lunarmodules/luasocket), hence the LTN.
+
+One extra application that deserves mentioning makes use of an identity filter. Suppose you want to provide some feedback to the user while a file is being downloaded into a sink. Chaining the sink with an identity filter (a filter that simply returns the received data unaltered), you can update a progress counter on the fly. The original sink doesn't have to be modified. Another interesting idea is that of a T sink: A sink that sends data to two other sinks. In summary, there appears to be enough room for many other interesting ideas.
+
+In this technical note we introduced filters, sources, sinks, and pumps. These are useful tools for data processing in general. Sources provide a simple abstraction for data acquisition. Sinks provide an abstraction for final data destinations. Filters define an interface for data transformations. The chaining of filters, sources and sinks provides an elegant way to create arbitrarily complex data transformation from simpler transformations. Pumps just put the machinery to work.

ltn012.wiki

@@ -1,393 +0,0 @@
-===Filters, sources and sinks: design, motivation and examples===
-==or Functional programming for the rest of us==
-by DiegoNehab
-
-{{{
-
-}}}
-
-===Abstract===
-Certain operations can be implemented in the form of filters. A filter is a function that processes data received in consecutive function calls, returning partial results chunk by chunk.  Examples of operations that can be implemented as filters include the end-of-line normalization for text, Base64 and Quoted-Printable transfer content encodings, the breaking of text into lines, SMTP byte stuffing, and there are many others.  Filters become even more powerful when we allow them to be chained together to create composite filters. Filters can be seen as middle nodes in a chain of data transformations. Sources an sinks are the corresponding end points of these chains. A source is a function that produces data, chunk by chunk, and a sink is a function that takes data, chunk by chunk. In this technical note, we define an elegant interface for filters, sources, sinks and chaining. We evolve our interface progressively, until we reach a high degree of generality. We discuss difficulties that arise during the implementation of this interface and we provide solutions and examples. 
-
-===Introduction===
-
-Applications sometimes have too much information to process to fit in memory and are thus forced to process data in smaller parts.  Even when there is enough memory, processing all the data atomically may take long enough to frustrate a user that wants to interact with the application.  Furthermore, complex transformations can often be defined as series of simpler operations. Several different complex transformations might share the same simpler operations, so that an uniform interface to combine them is desirable. The following concepts constitute our solution to these problems. 
-
-''Filters'' are functions that accept successive chunks of input, and produce successive chunks of output. Furthermore, the result of concatenating all the output data is the same as the result of applying the filter over the concatenation of the input data. As a consequence, boundaries are irrelevant: filters have to handle input data split arbitrarily by the user. 
-
-A ''chain'' is a function that combines the effect of two (or more) other functions, but whose interface is indistinguishable from the interface of one of its components.  Thus, a chained filter can be used wherever an atomic filter can be used.  However, its effect on data is the combined effect of its component filters. Note that, as a consequence, chains can be chained themselves to create arbitrarily complex operations that can be used just like atomic operations.
-
-Filters can be seen as internal nodes in a network through which data flows, potentially being transformed along its way.  Chains connect these nodes together. To complete the picture, we need ''sources'' and ''sinks'' as initial and final nodes of the network, respectively.  Less abstractly, a source is a function that produces new data every time it is called.  On the other hand, sinks are functions that give a final destination to the data they receive.  Naturally, sources and sinks can be chained with filters.
-
-Finally, filters, chains, sources, and sinks are all passive entities: they need to be repeatedly called in order for something to happen.  ''Pumps'' provide the driving force that pushes data through the network, from a source to a sink.
-
- Hopefully, these concepts will become clear with examples. In the following sections, we start with simplified interfaces, which we improve several times until we can find no obvious shortcomings. The evolution we present is not contrived: it follows the steps we followed ourselves as we consolidated our understanding of these concepts. 
-
-== A concrete example ==
-
-Some data transformations are easier to implement as filters than others.  Examples of operations that can be implemented as filters include the end-of-line normalization for text, the Base64 and Quoted-Printable transfer content encodings, the breaking of text into lines, SMTP byte stuffing, and many others. Let's use the end-of-line normalization as an example to define our initial filter interface. We later discuss why the implementation might not be trivial.
-
-Assume we are given text in an unknown end-of-line convention (including possibly mixed conventions) out of the commonly found Unix (LF), Mac OS (CR), and DOS (CRLF) conventions. We would like to be able to write code like the following:
-        {{{
-input = source.chain(source.file(io.stdin), normalize("\r\n"))
-output = sink.file(io.stdout)
-pump(input, output)
-}}}
-
-This program should read data from the standard input stream and normalize the end-of-line markers to the canonic CRLF marker defined by the MIME standard, finally sending the results to the standard output stream.  For that, we use a ''file source'' to produce data from standard input, and chain it with a filter that normalizes the data. The pump then repeatedly gets data from the source, and moves it to the ''file sink'' that sends it to standard output.
-
-To make the discussion even more concrete, we start by discussing the implementation of the normalization filter. The {{normalize}} ''factory'' is a function that creates such a filter. Our initial filter interface is as follows: the filter receives a chunk of input data, and returns a chunk of processed data. When there is no more input data, the user notifies the filter by invoking it with a {{nil}} chunk. The filter then returns the final chunk of processed data.
-
-Although the interface is extremely simple, the implementation doesn't seem so obvious. Any filter respecting this interface needs to keep some kind of context between calls. This is because chunks can be broken between the CR and LF characters marking the end of a line.  This need for context storage is what motivates the use of factories: each time the factory is called, it returns a filter with its own context so that we can have several independent filters being used at the same time.  For the normalization filter, we know that the obvious solution (i.e.  concatenating all the input into the context before producing any output) is not good enough, so we will have to find another way.
-
-We will break the implementation in two parts: a low-level filter, and a factory of high-level filters. The low-level filter will be implemented in C and will not carry any context between function calls. The high-level filter factory, implemented in Lua, will create and return a high-level filter that keeps whatever context the low-level filter needs, but isolates the user from its internal details. That way, we take advantage of C's efficiency to perform the dirty work, and take advantage of Lua's simplicity for the bookkeeping.
-
-==The Lua part of the implementation==
-
-Below is the implementation of the factory of high-level end-of-line normalization filters:
-        {{{
-function filter.cycle(low, ctx, extra)
-    return function(chunk)
-        local ret
-        ret, ctx = low(ctx, chunk, extra)
-        return ret
-    end
-end
-
-function normalize(marker)
-    return cycle(eol, 0, marker)
-end
-}}}
-
-The {{normalize}} factory simply calls a more generic factory, the {{cycle}} factory. This factory receives a low-level filter, an initial context and some extra value and returns the corresponding high-level filter. Each time the high level filer is called with a new chunk, it calls the low-level filter passing the previous context, the new chunk and the extra argument. The low-level filter produces the chunk of processed data and a new context. Finally, the high-level filter updates its internal context and returns the processed chunk of data to the user.  It is the low-level filter that does all the work.  Notice that this implementation takes advantage of the Lua 5.0 lexical scoping rules to store the context locally, between function calls.  
-
-Moving to the low-level filter, we notice there is no perfect solution to the end-of-line marker normalization problem itself. The difficulty comes from an inherent ambiguity on the definition of empty lines within mixed input. However, the following solution works well for any consistent input, as well as for non-empty lines in mixed input. It also does a reasonable job with empty lines and serves as a good example of how to implement a low-level filter.
-
-Here is what we do: CR and LF are considered candidates for line break.  We issue ''one'' end-of-line line marker if one of the candidates is seen alone, or followed by a ''different'' candidate.  That is, CR CR and LF LF issue two end of line markers each, but CR LF and LF CR issue only one marker.  This idea takes care of Mac OS, Mac OS X, VMS and Unix, DOS and MIME, as well as probably other more obscure conventions.
-
-==The C part of the implementation==
-
-The low-level filter is divided into two simple functions. The inner function actually does the conversion. It takes each input character in turn, deciding what to output and how to modify the context. The context tells if the last character seen was a candidate and, if so, which candidate it was.
-        {{{
-#define candidate(c) (c == CR || c == LF)
-static int process(int c, int last, const char *marker, luaL_Buffer *buffer) {
-    if (candidate(c)) {
-        if (candidate(last)) {
-            if (c == last) luaL_addstring(buffer, marker);
-            return 0;
-        } else {
-            luaL_addstring(buffer, marker);
-            return c;
-        }
-    } else {
-        luaL_putchar(buffer, c);
-        return 0;
-    }
-}
-}}}
-
-The inner function makes use of Lua's auxiliary library's buffer interface for its efficiency and ease of use. The outer function simply interfaces with Lua.  It receives the context and the input chunk (as well as an optional end-of-line marker), and returns the transformed output and the new context.
-        {{{
-static int eol(lua_State *L) {
-    int ctx = luaL_checkint(L, 1);
-    size_t isize = 0;
-    const char *input = luaL_optlstring(L, 2, NULL, &isize);
-    const char *last = input + isize;
-    const char *marker = luaL_optstring(L, 3, CRLF);
-    luaL_Buffer buffer;
-    luaL_buffinit(L, &buffer);
-    if (!input) {
-       lua_pushnil(L);
-       lua_pushnumber(L, 0);
-       return 2;
-    }
-    while (input < last)
-        ctx = process(*input++, ctx, marker, &buffer);
-    luaL_pushresult(&buffer);
-    lua_pushnumber(L, ctx);
-    return 2;
-}
-}}}
-
-Notice that if the input chunk is {{nil}}, the operation is considered to be finished. In that case, the loop will not execute a single time and the context is reset to the initial state.  This allows the filter to be reused indefinitely. It is a good idea to write filters like this, when possible. 
-
-Besides the end-of-line normalization filter shown above, many other filters can be implemented with the same ideas. Examples include Base64 and Quoted-Printable transfer content encodings, the breaking of text into lines, SMTP byte stuffing etc. The challenging part is to decide what will be the context. For line breaking, for instance, it could be the number of bytes left in the current line.  For Base64 encoding, it could be the bytes that remain in the division of the input into 3-byte atoms. 
-
-===Chaining===
-
-Filters become more powerful when the concept of chaining is introduced. Suppose you have a filter for Quoted-Printable encoding and you want to encode some text. According to the standard, the text has to be normalized into its canonic form prior to encoding.  A nice interface that simplifies this task is a factory that creates a composite filter that passes data through multiple filters, but that can be used wherever a primitive filter is used.
-        {{{
-local function chain2(f1, f2)
-    return function(chunk)
-        local ret = f2(f1(chunk))
-        if chunk then return ret
-        else return ret .. f2() end
-    end
-end
-
-function filter.chain(...)
-    local arg = {...}
-    local f = arg[1]
-    for i = 2, #arg do
-        f = chain2(f, arg[i])
-    end
-    return f
-end
-
-local chain = filter.chain(normalize("\r\n"), encode("quoted-printable"))
-while 1 do
-    local chunk = io.read(2048)
-    io.write(chain(chunk))
-    if not chunk then break end
-end
-}}}
-
-The chaining factory is very simple. All it does is return a function that passes data through all filters and returns the result to the user.  It uses the simpler auxiliary function that knows how to chain two filters together. In the auxiliary function, special care must be taken if the chunk is final. This is because the final chunk notification has to be pushed through both filters in turn. Thanks to the chain factory, it is easy to perform the Quoted-Printable conversion, as the above example shows.
-
-===Sources, sinks, and pumps===
-
-As we noted in the introduction, the filters we introduced so far act as the internal nodes in a network of transformations. Information flows from node to node (or rather from one filter to the next) and is transformed on its way out. Chaining filters together is the way we found to connect nodes in the network. But what about the end nodes?  In the beginning of the network, we need a node that provides the data, a source. In the end of the network, we need a node that takes in the data, a sink.
-
-==Sources==
-
-We start with two simple sources. The first is the {{empty}} source: It simply returns no data, possibly returning an error message. The second is the {{file}} source, which produces the contents of a file in a chunk by chunk fashion, closing the file handle when done.
-        {{{
-function source.empty(err)
-    return function()
-        return nil, err
-    end
-end
-
-function source.file(handle, io_err)
-    if handle then 
-        return function()
-            local chunk = handle:read(2048)
-            if not chunk then handle:close() end
-            return chunk
-        end
-    else return source.empty(io_err or "unable to open file") end
-end
-}}}
-
-A source returns the next chunk of data each time it is called. When there is no more data, it just returns {{nil}}.  If there is an error, the source can inform the caller by returning {{nil}} followed by an error message. Adrian Sietsma noticed that, although not on purpose, the interface for sources is compatible with the idea of iterators in Lua 5.0. That is, a data source can be nicely used in conjunction with {{for}} loops.  Using our file source as an iterator, we can rewrite our first example:
-        {{{
-local process = normalize("\r\n")
-for chunk in source.file(io.stdin) do
-    io.write(process(chunk))
-end
-io.write(process(nil))
-}}}
-
-Notice that the last call to the filter obtains the last chunk of processed data. The loop terminates when the source returns {{nil}} and therefore we need that final call outside of the loop.
-
-==Maintaining state between calls==
-
-It is often the case that a source needs to change its behavior after some event. One simple example would be a file source that wants to make sure it returns {{nil}} regardless of how many times it is called after the end of file, avoiding attempts to read past the end of the file.  Another example would be a source that returns the contents of several files, as if they were concatenated, moving from one file to the next until the end of the last file is reached.
-
-One way to implement this kind of source is to have the factory declare extra state variables that the source can use via lexical scoping. Our file source could set the file handle itself to {{nil}} when it detects the end-of-file.  Then, every time the source is called, it could check if the handle is still valid and act accordingly:
-        {{{
-function source.file(handle, io_err)
-    if handle then 
-        return function()
-            if not handle then return nil end
-            local chunk = handle:read(2048)
-            if not chunk then 
-                handle:close() 
-                handle = nil
-            end
-            return chunk
-        end
-    else return source.empty(io_err or "unable to open file") end
-end
-}}}
-
-Another way to implement this behavior involves a change in the source interface to makes it more flexible. Let's allow a source to return a second value, besides the next chunk of data.  If the returned chunk is {{nil}}, the extra return value tells us what happened. A second {{nil}} means that there is just no more data and the source is empty.  Any other value is considered to be an error message.  On the other hand, if the chunk was ''not'' {{nil}}, the second return value tells us whether the source wants to be replaced. If it is {{nil}}, we should proceed using the same source.  Otherwise it has to be another source, which we have to use from then on, to get the remaining data. 
-
-This extra freedom is good for someone writing a source function, but it is a pain for those that have to use it.  Fortunately, given one of these ''fancy'' sources, we can transform it into a simple source that never needs to be replaced, using the following factory.
-        {{{
-function source.simplify(src)
-    return function()
-        local chunk, err_or_new = src()
-        src = err_or_new or src
-        if not chunk then return nil, err_or_new
-        else return chunk end
-    end
-end
-}}}
-
-The simplification factory allows us to write fancy sources and use them as if they were simple. Therefore, our next functions will only produce simple sources, and functions that take sources will assume they are simple.
-
-Going back to our file source, the extended interface allows for a more elegant implementation. The new source just asks to be replaced by an empty source as soon as there is no more data. There is no repeated checking of the handle. To make things simpler to the user, the factory itself simplifies the the fancy file source before returning it to the user:
-        {{{
-function source.file(handle, io_err)
-    if handle then 
-        return source.simplify(function()
-            local chunk = handle:read(2048)
-            if not chunk then 
-                handle:close()
-                return "", source.empty() 
-            end
-            return chunk
-        end)
-    else return source.empty(io_err or "unable to open file") end
-end
-}}}
-
-We can make these ideas even more powerful if we use a new feature of Lua 5.0: coroutines.  Coroutines suffer from a great lack of advertisement, and I am going to play my part here.  Just like lexical scoping, coroutines taste odd at first, but once you get used with the concept, it can save your day. I have to admit that using coroutines to implement our file source would be overkill, so let's implement a concatenated source factory instead.
-        {{{
-function source.cat(...)
-    local arg = {...}
-    local co = coroutine.create(function()
-        local i = 1
-        while i <= #arg do
-            local chunk, err = arg[i]()
-            if chunk then coroutine.yield(chunk)
-            elseif err then return nil, err 
-            else i = i + 1 end 
-        end
-    end)
-    return function()
-        return shift(coroutine.resume(co))
-    end
-end
-}}}
-
-The factory creates two functions. The first is an auxiliary that does all the work, in the form of a coroutine. It reads a chunk from one of the sources. If the chunk is {{nil}}, it moves to the next source, otherwise it just yields returning the chunk. When it is resumed, it continues from where it stopped and tries to read the next chunk.  The second function is the source itself, and just resumes the execution of the auxiliary coroutine, returning to the user whatever chunks it returns (skipping the first result that tells us if the coroutine terminated). Imagine writing the same function without coroutines and you will notice the simplicity of this implementation. We will use coroutines again when we make the filter interface more powerful. 
-
-==Chaining Sources==
-
-What does it mean to chain a source with a filter?  The most useful interpretation is that the combined source-filter is a new source that produces data and passes it through the filter before returning it. Here is a factory that does it:
-        {{{
-function source.chain(src, f)
-    return source.simplify(function()
-        local chunk, err = src()
-        if not chunk then return f(nil), source.empty(err)
-        else return f(chunk) end
-    end)
-end
-}}}
-
-Our motivating example in the introduction chains a source with a filter. The idea of chaining a source with a filter is useful when one thinks about functions that might get their input data from a source. By chaining a simple source with one or more filters, the same function can be provided with filtered data even though it is unaware of the filtering that is happening behind its back.
-
-==Sinks==
-
-Just as we defined an interface for an initial source of data, we can also define an interface for a final destination of data. We call any function respecting that interface a ''sink''. Below are two simple factories that return sinks. The table factory creates a sink that stores all obtained data into a table. The data can later be efficiently concatenated into a single string with the {{table.concat}} library function. As another example, we introduce the {{null}} sink: A sink that simply discards the data it receives.
-        {{{
-function sink.table(t)
-    t = t or {}
-    local f = function(chunk, err)
-        if chunk then table.insert(t, chunk) end
-        return 1
-    end
-    return f, t
-end
-
-local function null()
-    return 1
-end
-
-function sink.null()
-    return null
-end
-}}}
-
-Sinks receive consecutive chunks of data, until the end of data is notified with a {{nil}} chunk. An error is notified by an extra argument giving an error message after the {{nil}} chunk.  If a sink detects an error itself and wishes not to be called again, it should return {{nil}}, optionally followed by an error message. A return value that is not {{nil}} means the source will accept more data. Finally, just as sources can choose to be replaced, so can sinks, following the same interface. Once again, it is easy to implement a {{sink.simplify}} factory that transforms a fancy sink into a simple sink.
-
-As an example, let's create a source that reads from the standard input, then chain it with a filter that normalizes the end-of-line convention and let's use a sink to place all data into a table, printing the result in the end.
-        {{{
-local load = source.chain(source.file(io.stdin), normalize("\r\n"))
-local store, t = sink.table()
-while 1 do
-    local chunk = load()
-    store(chunk)
-    if not chunk then break end
-end
-print(table.concat(t))
-}}}
-
-Again, just as we created a factory that produces a chained source-filter from a source and a filter, it is easy to create a factory that produces a new sink given a sink and a filter.  The new sink passes all data it receives through the filter before handing it in to the original sink. Here is the implementation: 
-        {{{
-function sink.chain(f, snk)
-    return function(chunk, err)
-        local r, e = snk(f(chunk))
-        if not r then return nil, e end
-        if not chunk then return snk(nil, err) end
-        return 1
-    end
-end
-}}}
-
-==Pumps==
-
-There is a while loop that has been around for too long in our examples.  It's always there because everything that we designed so far is passive.  Sources, sinks, filters: None of them will do anything on their own. The operation of pumping all data a source can provide into a sink is so common that we will provide a couple helper functions to do that for us.
-        {{{
-function pump.step(src, snk)
-    local chunk, src_err = src()
-    local ret, snk_err = snk(chunk, src_err)
-    return chunk and ret and not src_err and not snk_err, src_err or snk_err
-end
-
-function pump.all(src, snk, step)
-    step = step or pump.step
-    while true do
-        local ret, err = step(src, snk)
-        if not ret then return not err, err end
-    end
-end
-}}}
-
-The {{pump.step}} function moves one chunk of data from the source to the sink. The {{pump.all}} function takes an optional {{step}} function and uses it to pump all the data from the source to the sink. We can now use everything we have to write a program that reads a binary file from disk and stores it in another file, after encoding it to the Base64 transfer content encoding:
-        {{{
-local load = source.chain(
-    source.file(io.open("input.bin", "rb")), 
-    encode("base64")
-)
-local store = sink.chain(
-    wrap(76),
-    sink.file(io.open("output.b64", "w")), 
-)
-pump.all(load, store)
-}}}
-
-The way we split the filters here is not intuitive, on purpose.  Alternatively, we could have chained the Base64 encode filter and the line-wrap filter together, and then chain the resulting filter with either the file source or the file sink. It doesn't really matter.
-
-===One last important change===
-
-Turns out we still have a problem. When David Burgess was writing his gzip filter, he noticed that the decompression filter can explode a small input chunk into a huge amount of data. Although we wished we could ignore this problem, we soon agreed we couldn't. The only solution is to allow filters to return partial results, and that is what we chose to do.  After invoking the filter to pass input data, the user now has to loop invoking the filter to find out if it has more output data to return.  Note that these extra calls can't pass more data to the filter. 
-
-More specifically, after passing a chunk of input data to a filter and collecting the first chunk of output data, the user invokes the filter repeatedly, passing the empty string, to get extra output chunks. When the filter itself returns an empty string, the user knows there is no more output data, and can proceed to pass the next input chunk. In the end, after the user passes a {{nil}} notifying the filter that there is no more input data, the filter might still have produced too much output data to return in a single chunk. The user has to loop again, this time passing {{nil}} each time, until the filter itself returns {{nil}} to notify the user it is finally done.
-
-Most filters won't need this extra freedom. Fortunately, the new filter interface is easy to implement. In fact, the end-of-line translation filter we created in the introduction already conforms to it. On the other hand, the chaining function becomes much more complicated. If it wasn't for coroutines, I wouldn't be happy to implement it. Let me know if you can find a simpler implementation that does not use coroutines!
-        {{{
-local function chain2(f1, f2)
-    local co = coroutine.create(function(chunk)
-        while true do
-            local filtered1 = f1(chunk)
-            local filtered2 = f2(filtered1)
-            local done2 = filtered1 and ""
-            while true do
-                if filtered2 == "" or filtered2 == nil then break end
-                coroutine.yield(filtered2)
-                filtered2 = f2(done2)
-            end
-            if filtered1 == "" then chunk = coroutine.yield(filtered1)
-            elseif filtered1 == nil then return nil
-            else chunk = chunk and "" end
-        end
-    end)
-    return function(chunk)
-        local _, res = coroutine.resume(co, chunk)
-        return res
-    end
-end
-}}}
-
-Chaining sources also becomes more complicated, but a similar solution is possible with coroutines. Chaining sinks is just as simple as it has always been. Interestingly, these modifications do not have a measurable negative impact in the the performance of filters that didn't need the added flexibility. They do severely improve the efficiency of filters like the gzip filter, though, and that is why we are keeping them.
-
-===Final considerations===
-
-These ideas were created during the development of {{LuaSocket}}[http://www.tecgraf.puc-rio.br/luasocket] 2.0, and are available as the LTN12 module.  As a result, {{LuaSocket}}[http://www.tecgraf.puc-rio.br/luasocket] implementation was greatly simplified and became much more powerful.  The MIME module is especially integrated to LTN12 and provides many other filters. We felt these concepts deserved to be made public even to those that don't care about {{LuaSocket}}[http://www.tecgraf.puc-rio.br/luasocket], hence the LTN. 
-
-One extra application that deserves mentioning makes use of an identity filter.  Suppose you want to provide some feedback to the user while a file is being downloaded into a sink. Chaining the sink with an identity filter (a filter that simply returns the received data unaltered), you can update a progress counter on the fly. The original sink doesn't have to be modified.  Another interesting idea is that of a T sink: A sink that sends data to two other sinks. In summary, there appears to be enough room for many other interesting ideas.
-
-In this technical note we introduced filters, sources, sinks, and pumps.  These are useful tools for data processing in general. Sources provide a simple abstraction for data acquisition. Sinks provide an abstraction for final data destinations. Filters define an interface for data transformations.  The chaining of filters, sources and sinks provides an elegant way to create arbitrarily complex data transformation from simpler transformations. Pumps just put the machinery to work.  

ltn013.md

@@ -0,0 +1,191 @@
+# Using finalized exceptions
+### or How to get rid of all those if statements
+by DiegoNehab
+
+
+## Abstract
+This little LTN describes a simple exception scheme that greatly simplifies error checking in Lua programs. All the needed functionality ships standard with Lua, but is hidden between the `assert` and `pcall` functions. To make it more evident, we stick to a convenient standard (you probably already use anyways) for Lua function return values, and define two very simple helper functions (either in C or in Lua itself).
+
+## Introduction
+
+Most Lua functions return `nil` in case of error, followed by a message describing the error. If you don't use this convention, you probably have good reasons. Hopefully, after reading on, you will realize your reasons are not good enough.
+
+If you are like me, you hate error checking. Most nice little code snippets that look beautiful when you first write them lose some of their charm when you add all that error checking code. Yet, error checking is as important as  the rest of the code. How sad.
+
+Even if you stick to a return convention, any complex task involving several function calls makes error checking both boring and error-prone (do you see the "error" below?)
+```lua
+function task(arg1, arg2, ...)
+    local ret1, err = task1(arg1)
+    if not ret1 then
+        cleanup1()
+        return nil, error
+    end
+    local ret2, err = task2(arg2)
+    if not ret then
+        cleanup2()
+        return nil, error
+    end
+    ...
+end
+```
+
+The standard `assert` function provides an interesting alternative. To use it, simply nest every function call to  be error checked with a call to `assert`. The `assert` function checks the value of its first argument. If it is `nil`, `assert` throws the second argument as an error message. Otherwise, `assert` lets all arguments through as if had not been there. The idea greatly simplifies error checking:
+```lua
+function task(arg1, arg2, ...)
+    local ret1 = assert(task1(arg1))
+    local ret2 = assert(task2(arg2))
+    ...
+end
+```
+
+If any task fails, the execution is aborted by `assert` and the error message is displayed to the user as the cause of the problem. If no error happens, the task completes as before. There isn't a single `if` statement and this is great. However, there are some problems with the idea.
+
+First, the topmost `task` function doesn't respect the protocol followed by the lower-level tasks: It raises an error instead of returning `nil` followed by the error messages. Here is where the standard `pcall` comes in handy.
+```lua
+function xtask(arg1, arg2, ...)
+    local ret1 = assert(task1(arg1))
+    local ret2 = assert(task2(arg2))
+    ...
+end
+
+function task(arg1, arg2, ...)
+    local ok, ret_or_err = pcall(xtask, arg1, arg2, ...)
+    if ok then return ret_or_err
+    else return nil, ret_or_err end
+end
+```
+
+Our new `task` function is well behaved. `Pcall` catches any error raised by the calls to `assert` and returns it after the status code. That way, errors don't get propagated to the user of the high level `task` function.
+
+These are the main ideas for our exception scheme, but there are still a few glitches to fix:
+
+* Directly using `pcall` ruined the simplicity of the code;
+* What happened to the cleanup function calls? What if we have to, say, close a file?
+* `Assert` messes with the error message before raising the error (it adds line number information).
+
+Fortunately, all these problems are very easy to solve and that's what we do in the following sections.
+
+## Introducing the `protect` factory
+
+We used the `pcall` function to shield the user from errors that could be raised by the underlying implementation. Instead of directly using `pcall` (and thus duplicating code) every time we prefer a factory that does the same job:
+```lua
+local function pack(ok, ...)
+    return ok, {...}
+end
+
+function protect(f)
+    return function(...)
+        local ok, ret = pack(pcall(f, ...))
+        if ok then return unpack(ret)
+        else return nil, ret[1] end
+    end
+end
+```
+
+The `protect` factory receives a function that might raise exceptions and returns a function that respects our return value convention. Now we can rewrite the top-level `task` function in a much cleaner way:
+```lua
+task = protect(function(arg1, arg2, ...)
+    local ret1 = assert(task1(arg1))
+    local ret2 = assert(task2(arg2))
+    ...
+end)
+```
+
+The Lua implementation of the `protect` factory suffers with the creation of tables to hold multiple arguments and return values. It is possible (and easy) to implement the same function in C, without any table creation.
+```c
+static int safecall(lua_State *L) {
+    lua_pushvalue(L, lua_upvalueindex(1));
+    lua_insert(L, 1);
+    if (lua_pcall(L, lua_gettop(L) - 1, LUA_MULTRET, 0) != 0) {
+        lua_pushnil(L);
+        lua_insert(L, 1);
+        return 2;
+    } else return lua_gettop(L);
+}
+
+static int protect(lua_State *L) {
+    lua_pushcclosure(L, safecall, 1);
+    return 1;
+}
+```
+
+## The `newtry` factory
+
+Let's solve the two remaining issues with a single shot and use a concrete example to illustrate the proposed solution. Suppose you want to write a function to download an HTTP document. You have to connect, send the request and read the reply. Each of these tasks can fail, but if something goes wrong after you connected, you have to close the connection before returning the error message.
+```lua
+get = protect(function(host, path)
+    local c
+    -- create a try function with a finalizer to close the socket
+    local try = newtry(function()
+        if c then c:close() end
+    end)
+    -- connect and send request
+    c = try(connect(host, 80))
+    try(c:send("GET " .. path .. " HTTP/1.0\r\n\r\n"))
+    -- get headers
+    local h = {}
+    while 1 do
+        l = try(c:receive())
+        if l == "" then break end
+        table.insert(h, l)
+    end
+    -- get body
+    local b = try(c:receive("*a"))
+    c:close()
+    return b, h
+end)
+```
+
+The `newtry` factory returns a function that works just like `assert`. The differences are that the `try` function doesn't mess with the error message and it calls an optional "finalizer" before raising the error. In our example, the finalizer simply closes the socket.
+
+Even with a simple example like this, we see that the finalized exceptions simplified our life. Let's see what we gain in general, not just in this example:
+
+* We don't need to declare dummy variables to hold error messages in case any ever shows up;
+* We avoid using a variable to hold something that could either be a return value or an error message;
+* We didn't have to use several "if" statements to check for errors;
+* If an error happens, we know our finalizer is going to be invoked automatically;
+* Exceptions get propagated, so we don't repeat these "if" statements until the error reaches the user.
+
+Try writing the same function without the tricks we used above and you will see that the code gets ugly. Longer sequences of operations with error checking would get even uglier. So let's implement the `newtry` function in Lua:
+```lua
+function newtry(f)
+    return function(...)
+        if not arg[1] then
+            if f then f() end
+            error(arg[2], 0)
+        else
+            return ...
+        end
+    end
+end
+```
+
+Again, the implementation suffers from the creation of tables at each function call, so we prefer the C version:
+```lua
+static int finalize(lua_State *L) {
+    if (!lua_toboolean(L, 1)) {
+        lua_pushvalue(L, lua_upvalueindex(1));
+        lua_pcall(L, 0, 0, 0);
+        lua_settop(L, 2);
+        lua_error(L);
+        return 0;
+    } else return lua_gettop(L);
+}
+
+static int do_nothing(lua_State *L) {
+    (void) L;
+    return 0;
+}
+
+static int newtry(lua_State *L) {
+    lua_settop(L, 1);
+    if (lua_isnil(L, 1))
+        lua_pushcfunction(L, do_nothing);
+    lua_pushcclosure(L, finalize, 1);
+    return 1;
+}
+```
+
+## Final considerations
+
+The `protect` and `newtry` functions saved a "lot" of work in the implementation of [LuaSocket](https://github.com/lunarmodules/luasocket). The size of some modules was cut in half by the these ideas. It's true the scheme is not as generic as the exception mechanism of programming languages like C++ or Java, but the power/simplicity ratio is favorable and I hope it serves you as well as it served [LuaSocket](https://github.com/lunarmodules/luasocket).

ltn013.wiki

@@ -1,194 +0,0 @@
-===Using finalized exceptions===
-==or How to get rid of all those if statements==
-by DiegoNehab
-
-{{{
-
-}}}
-
-===Abstract===
-This little LTN describes a simple exception scheme that greatly simplifies error checking in Lua programs. All the needed functionality ships standard with Lua, but is hidden between the {{assert}} and {{pcall}} functions.  To make it more evident, we stick to a convenient standard (you probably already use anyways) for Lua function return values, and define two very simple helper functions (either in C or in Lua itself). 
-
-===Introduction===
-
-Most Lua functions return {{nil}} in case of error, followed by a message describing the error. If you don't use this convention, you probably have good reasons. Hopefully, after reading on, you will realize your reasons are not good enough. 
-
-If you are like me, you hate error checking. Most nice little code snippets that look beautiful when you first write them lose some of their charm when you add all that error checking code.  Yet, error checking is as important as  the rest of the code. How sad.
-
-Even if you stick to a return convention, any complex task involving several function calls makes error checking both boring and error-prone (do you see the ''error'' below?)
-        {{{
-function task(arg1, arg2, ...)
-    local ret1, err = task1(arg1)
-    if not ret1 then 
-        cleanup1()
-        return nil, error 
-    end
-    local ret2, err = task2(arg2)
-    if not ret then 
-        cleanup2()
-        return nil, error 
-    end
-    ...
-end
-}}}
-
-The standard {{assert}} function provides an interesting alternative.  To use it, simply nest every function call to  be error checked with a call to {{assert}}. The {{assert}} function checks the value of its first argument.  If it is {{nil}}, {{assert}} throws the second argument as an error message. Otherwise, {{assert}} lets all arguments through as if had not been there. The idea greatly simplifies error checking: 
-        {{{
-function task(arg1, arg2, ...)
-    local ret1 = assert(task1(arg1))
-    local ret2 = assert(task2(arg2))
-    ...
-end
-}}}
-
-If any task fails, the execution is aborted by {{assert}} and the error message is displayed to the user as the cause of the problem.  If no error happens, the task completes as before. There isn't a single {{if}} statement and this is great. However, there are some problems with the idea.
-
-First, the topmost {{task}} function doesn't respect the protocol followed by the lower-level tasks: It raises an error instead of returning {{nil}} followed by the error messages. Here is where the standard {{pcall}} comes in handy. 
-        {{{
-function xtask(arg1, arg2, ...)
-    local ret1 = assert(task1(arg1))
-    local ret2 = assert(task2(arg2))
-    ...
-end
-
-function task(arg1, arg2, ...)
-    local ok, ret_or_err = pcall(xtask, arg1, arg2, ...)
-    if ok then return ret_or_err
-    else return nil, ret_or_err end
-end
-}}}
-
-Our new {{task}} function is well behaved. {{Pcall}} catches any error raised by the calls to {{assert}} and returns it after the status code. That way, errors don't get propagated to the user of the high level {{task}} function. 
-
-These are the main ideas for our exception scheme, but there are still a few glitches to fix: 
-
-        * Directly using {{pcall}} ruined the simplicity of the code;
-        * What happened to the cleanup function calls? What if we have to, say, close a file?
-        * {{Assert}} messes with the error message before raising the error (it adds line number information).
-
-Fortunately, all these problems are very easy to solve and that's what we do in the following sections. 
-
-== Introducing the {{protect}} factory ==
-
-We used the {{pcall}} function to shield the user from errors that could be raised by the underlying implementation.  Instead of directly using {{pcall}} (and thus duplicating code) every time we prefer a factory that does the same job:
-        {{{
-local function pack(ok, ...)
-    return ok, {...}
-end
-
-function protect(f)
-    return function(...)
-        local ok, ret = pack(pcall(f, ...))
-        if ok then return unpack(ret)
-        else return nil, ret[1] end
-    end
-end
-}}}
-
-The {{protect}} factory receives a function that might raise exceptions and returns a function that respects our return value convention. Now we can rewrite the top-level {{task}} function in a much cleaner way:
-        {{{
-task = protect(function(arg1, arg2, ...)
-    local ret1 = assert(task1(arg1))
-    local ret2 = assert(task2(arg2))
-    ...
-end)
-}}}
-
-The Lua implementation of the {{protect}} factory suffers with the creation of tables to hold multiple arguments and return values.  It is possible (and easy) to implement the same function in C, without any table creation. 
-        {{{
-static int safecall(lua_State *L) {
-    lua_pushvalue(L, lua_upvalueindex(1));
-    lua_insert(L, 1);
-    if (lua_pcall(L, lua_gettop(L) - 1, LUA_MULTRET, 0) != 0) {
-        lua_pushnil(L);
-        lua_insert(L, 1);
-        return 2;
-    } else return lua_gettop(L);
-}
-
-static int protect(lua_State *L) {
-    lua_pushcclosure(L, safecall, 1);
-    return 1;
-}
-}}}
-
-===The {{newtry}} factory===
-
-Let's solve the two remaining issues with a single shot and use a concrete example to illustrate the proposed solution. Suppose you want to write a function to download an HTTP document. You have to connect, send the request and read the reply. Each of these tasks can fail, but if something goes wrong after you connected, you have to close the connection before returning the error message.
-        {{{
-get = protect(function(host, path)
-    local c
-    -- create a try function with a finalizer to close the socket
-    local try = newtry(function() 
-        if c then c:close() end 
-    end)
-    -- connect and send request
-    c = try(connect(host, 80))
-    try(c:send("GET " .. path .. " HTTP/1.0\r\n\r\n"))
-    -- get headers
-    local h = {}
-    while 1 do
-        l = try(c:receive())
-        if l == "" then break end
-        table.insert(h, l)
-    end
-    -- get body
-    local b = try(c:receive("*a"))
-    c:close()
-    return b, h
-end)
-}}}
-
-The {{newtry}} factory returns a function that works just like {{assert}}. The differences are that the {{try}} function doesn't mess with the error message and it calls an optional ''finalizer'' before raising the error. In our example, the finalizer simply closes the socket.
-
-Even with a simple example like this, we see that the finalized exceptions simplified our life. Let's see what we gain in general, not just in this example: 
-
-        * We don't need to declare dummy variables to hold error messages in case any ever shows up; 
-        * We avoid using a variable to hold something that could either be a return value or an error message; 
-        * We didn't have to use several ''if'' statements to check for errors;
-        * If an error happens, we know our finalizer is going to be invoked automatically;
-        * Exceptions get propagated, so we don't repeat these ''if'' statements until the error reaches the user.
-
-Try writing the same function without the tricks we used above and you will see that the code gets ugly. Longer sequences of operations with error checking would get even uglier. So let's implement the {{newtry}} function in Lua:
-        {{{
-function newtry(f)
-    return function(...) 
-        if not arg[1] then 
-            if f then f() end 
-            error(arg[2], 0)  
-        else 
-            return ...
-        end
-    end
-end
-}}}
-
-Again, the implementation suffers from the creation of tables at each function call, so we prefer the C version:
-        {{{
-static int finalize(lua_State *L) {
-    if (!lua_toboolean(L, 1)) {
-        lua_pushvalue(L, lua_upvalueindex(1));
-        lua_pcall(L, 0, 0, 0);
-        lua_settop(L, 2);
-        lua_error(L);
-        return 0;
-    } else return lua_gettop(L);
-}
-
-static int do_nothing(lua_State *L) {
-    (void) L;
-    return 0;
-}
-
-static int newtry(lua_State *L) {
-    lua_settop(L, 1);
-    if (lua_isnil(L, 1)) 
-        lua_pushcfunction(L, do_nothing);
-    lua_pushcclosure(L, finalize, 1);
-    return 1;
-}
-}}}
-
-===Final considerations===
-
-The {{protect}} and {{newtry}} functions saved a ''lot'' of work in the implementation of {{LuaSocket}}[http://www.tecgraf.puc-rio.br/luasocket].  The size of some modules was cut in half by the these ideas.  It's true the scheme is not as generic as the exception mechanism of programming languages like C++ or Java, but the power/simplicity ratio is favorable and I hope it serves you as well as it served {{LuaSocket}}.

luasocket-scm-3.rockspec

@@ -34,7 +34,7 @@ local function make_plat(plat)
     },
     mingw32 = {
       "LUASOCKET_DEBUG",
-      "LUASOCKET_INET_PTON",
+      -- "LUASOCKET_INET_PTON",
       "WINVER=0x0501"
     }
   }
@@ -69,6 +69,7 @@ local function make_plat(plat)
     ["socket.smtp"]    = "src/smtp.lua",
     ltn12              = "src/ltn12.lua",
     socket             = "src/socket.lua",
+    mbox               = "src/mbox.lua",
     mime               = "src/mime.lua"
   }
   if plat == "unix"
@@ -113,6 +114,7 @@ local function make_plat(plat)
   then
     modules["socket.core"].sources[#modules["socket.core"].sources+1] = "src/wsocket.c"
     modules["socket.core"].libraries = { "ws2_32" }
+    modules["socket.core"].libdirs = {}
   end
   return { modules = modules }
 end
@@ -129,6 +131,5 @@ build = {
   copy_directories = {
     "docs"
     , "samples"
-    , "etc"
     , "test" }
 }

makefile.dist

@@ -1,7 +1,7 @@
 #--------------------------------------------------------------------------
 # Distribution makefile
 #--------------------------------------------------------------------------
-DIST = luasocket-3.0-rc1
+DIST = luasocket-3.1.0
 
 TEST = \
 	test/README \
@@ -22,20 +22,17 @@ SAMPLES = \
 	samples/lpr.lua \
 	samples/talker.lua \
 	samples/tinyirc.lua
-
-ETC = \
-	etc/README \
-	etc/b64.lua \
-	etc/check-links.lua \
-	etc/check-memory.lua \
-	etc/dict.lua \
-	etc/dispatch.lua \
-	etc/eol.lua \
-	etc/forward.lua \
-	etc/get.lua \
-	etc/lp.lua \
-	etc/qp.lua \
-	etc/tftp.lua
+	samples/b64.lua \
+	samples/check-links.lua \
+	samples/check-memory.lua \
+	samples/dict.lua \
+	samples/dispatch.lua \
+	samples/eol.lua \
+	samples/forward.lua \
+	samples/get.lua \
+	samples/lp.lua \
+	samples/qp.lua \
+	samples/tftp.lua
 
 SRC = \
 	src/makefile \
@@ -117,9 +114,6 @@ dist:
 	cp -vf README.md $(DIST)
 	cp -vf $(MAKE) $(DIST)
 
-	mkdir -p $(DIST)/etc
-	cp -vf $(ETC) $(DIST)/etc
-
 	mkdir -p $(DIST)/src
 	cp -vf $(SRC) $(DIST)/src
 

rockspecs/luasocket-3.1.0-1.rockspec

@@ -0,0 +1,135 @@
+package = "LuaSocket"
+version = "3.1.0-1"
+source = {
+  url = "git+https://github.com/lunarmodules/luasocket.git",
+  tag = "v3.1.0"
+}
+description = {
+  summary = "Network support for the Lua language",
+  detailed = [[
+      LuaSocket is a Lua extension library composed of two parts: a set of C
+      modules that provide support for the TCP and UDP transport layers, and a
+      set of Lua modules that provide functions commonly needed by applications
+      that deal with the Internet.
+   ]],
+  homepage = "https://github.com/lunarmodules/luasocket",
+  license = "MIT"
+}
+dependencies = {
+  "lua >= 5.1"
+}
+
+local function make_plat(plat)
+  local defines = {
+    unix = {
+      "LUASOCKET_DEBUG"
+    },
+    macosx = {
+      "LUASOCKET_DEBUG",
+      "UNIX_HAS_SUN_LEN"
+    },
+    win32 = {
+      "LUASOCKET_DEBUG",
+      "NDEBUG"
+    },
+    mingw32 = {
+      "LUASOCKET_DEBUG",
+      -- "LUASOCKET_INET_PTON",
+      "WINVER=0x0501"
+    }
+  }
+  local modules = {
+    ["socket.core"] = {
+      sources = {
+        "src/luasocket.c"
+        , "src/timeout.c"
+        , "src/buffer.c"
+        , "src/io.c"
+        , "src/auxiliar.c"
+        , "src/options.c"
+        , "src/inet.c"
+        , "src/except.c"
+        , "src/select.c"
+        , "src/tcp.c"
+        , "src/udp.c"
+        , "src/compat.c" },
+      defines = defines[plat],
+      incdir = "/src"
+    },
+    ["mime.core"] = {
+      sources = { "src/mime.c", "src/compat.c" },
+      defines = defines[plat],
+      incdir = "/src"
+    },
+    ["socket.http"]    = "src/http.lua",
+    ["socket.url"]     = "src/url.lua",
+    ["socket.tp"]      = "src/tp.lua",
+    ["socket.ftp"]     = "src/ftp.lua",
+    ["socket.headers"] = "src/headers.lua",
+    ["socket.smtp"]    = "src/smtp.lua",
+    ltn12              = "src/ltn12.lua",
+    socket             = "src/socket.lua",
+    mime               = "src/mime.lua"
+  }
+  if plat == "unix"
+    or plat == "macosx"
+    or plat == "haiku"
+  then
+    modules["socket.core"].sources[#modules["socket.core"].sources+1] = "src/usocket.c"
+    if plat == "haiku" then
+      modules["socket.core"].libraries = {"network"}
+    end
+    modules["socket.unix"] = {
+      sources = {
+        "src/buffer.c"
+        , "src/compat.c"
+        , "src/auxiliar.c"
+        , "src/options.c"
+        , "src/timeout.c"
+        , "src/io.c"
+        , "src/usocket.c"
+        , "src/unix.c"
+        , "src/unixdgram.c"
+        , "src/unixstream.c" },
+      defines = defines[plat],
+      incdir = "/src"
+    }
+    modules["socket.serial"] = {
+      sources = {
+        "src/buffer.c"
+        , "src/compat.c"
+        , "src/auxiliar.c"
+        , "src/options.c"
+        , "src/timeout.c"
+        , "src/io.c"
+        , "src/usocket.c"
+        , "src/serial.c" },
+      defines = defines[plat],
+      incdir = "/src"
+    }
+  end
+  if  plat == "win32"
+    or plat == "mingw32"
+  then
+    modules["socket.core"].sources[#modules["socket.core"].sources+1] = "src/wsocket.c"
+    modules["socket.core"].libraries = { "ws2_32" }
+    modules["socket.core"].libdirs = {}
+  end
+  return { modules = modules }
+end
+
+build = {
+  type = "builtin",
+  platforms = {
+    unix = make_plat("unix"),
+    macosx = make_plat("macosx"),
+    haiku = make_plat("haiku"),
+    win32 = make_plat("win32"),
+    mingw32 = make_plat("mingw32")
+  },
+  copy_directories = {
+    "docs"
+    , "samples"
+    , "etc"
+    , "test" }
+}

samples/README

@@ -1,11 +1,95 @@
 This directory contains some sample programs using
 LuaSocket. This code is not supported.
 
+    tftp.lua                -- Trivial FTP client
+
+This module implements file retrieval by the TFTP protocol.
+Its main use was to test the UDP code, but since someone
+found it usefull, I turned it into a module that is almost
+official (no uploads, yet).
+
+    dict.lua                -- Dict client
+
+The dict.lua  module started with  a cool  simple client
+for the  DICT protocol, written by Luiz Henrique Figueiredo.
+This new version has been converted into a library, similar
+to the HTTP  and FTP libraries, that can be used from within
+any luasocket application. Take  a look on the  source code
+and you will be able to figure out how to use it.
+
+    lp.lua                  -- LPD client library
+
+The lp.lua module implements the client part of the Line
+Printer Daemon protocol, used to print files on Unix
+machines. It is courtesy of David Burgess!  See the source
+code and the lpr.lua in the examples directory.
+
+    b64.lua
+    qp.lua
+    eol.lua
+
+These are tiny programs that perform Base64,
+Quoted-Printable and end-of-line marker conversions.
+
+    get.lua                 -- file retriever
+
+This little  program is  a client  that uses  the FTP  and
+HTTP  code to implement a  command line  file graber. Just
+run
+
+	lua get.lua <remote-file> [<local-file>]
+
+to download  a remote file (either  ftp:// or http://) to
+the specified local file.  The program  also prints  the
+download  throughput, elapsed time, bytes already downloaded
+etc during download.
+
+    check-memory.lua        -- checks memory consumption
+
+This is just to see how much memory each module uses.
+
+    dispatch.lua            -- coroutine based dispatcher
+
+This is a first try at a coroutine based non-blocking
+dispatcher for LuaSocket. Take a look at 'check-links.lua'
+and at 'forward.lua' to see how to use it.
+
+	check-links.lua			-- HTML link checker program
+
+This little program scans a HTML file and checks for broken
+links. It is similar to check-links.pl by Jamie Zawinski,
+but uses all facilities of the LuaSocket library and the Lua
+language. It has not been thoroughly tested, but it should
+work. Just run
+
+	lua check-links.lua [-n] {<url>} > output
+
+and open the result to see a list of broken links. Make sure
+you check the '-n' switch. It runs in non-blocking mode,
+using coroutines, and is MUCH faster!
+
+    forward.lua             -- coroutine based forward server
+
+This is a forward server that can accept several connections
+and transfers simultaneously using non-blocking I/O and the
+coroutine-based dispatcher. You can run, for example
+
+    lua forward.lua 8080:proxy.com:3128
+
+to redirect all local conections to port 8080 to the host
+'proxy.com' at port 3128.
+
+    unix.c and unix.h
+
+This is an implementation of Unix local domain sockets and
+demonstrates how to extend LuaSocket with a new type of
+transport. It has been tested on Linux and on Mac OS X.
+
     listener.lua            -- socket to stdout
     talker.lua              -- stdin to socket
 
 listener.lua and talker.lua are about  the simplest
-applications you can write  using  LuaSocket.  Run   
+applications you can write  using  LuaSocket.  Run
 
 	'lua listener.lua'  and  'lua talker.lua'
 
@@ -17,13 +101,13 @@ be printed by listen.lua.
 This is a cool program written by David Burgess to print
 files using the Line Printer Daemon protocol, widely used in
 Unix machines.  It uses the lp.lua implementation, in the
-etc directory.  Just run 'lua lpr.lua <filename>
+samples directory.  Just run 'lua lpr.lua <filename>
 queue=<printername>' and the file will print!
 
     cddb.lua                -- CDDB client
 
 This is the first try on a simple CDDB client. Not really
-useful, but one day it might become a module. 
+useful, but one day it might become a module.
 
     daytimeclnt.lua         -- day time client
 

src/http.lua

@@ -54,7 +54,7 @@ local function receiveheaders(sock, headers)
     while line ~= "" do
         -- get field-name and value
         name, value = socket.skip(2, string.find(line, "^(.-):%s*(.*)"))
-        if not (name and value) then return nil, "malformed reponse headers" end
+        if not (name and value) then return nil, "malformed response headers" end
         name = string.lower(name)
         -- get next line (value might be folded)
         line, err  = sock:receive()
@@ -62,7 +62,7 @@ local function receiveheaders(sock, headers)
         -- unfold any folded values
         while string.find(line, "^%s") do
             value = value .. line
-            line = sock:receive()
+            line, err = sock:receive()
             if err then return nil, err end
         end
         -- save pair in table
@@ -81,7 +81,7 @@ socket.sourcet["http-chunked"] = function(sock, headers)
         dirty = function() return sock:dirty() end
     }, {
         __call = function()
-            -- get chunk size, skip extention
+            -- get chunk size, skip extension
             local line, err = sock:receive()
             if err then return nil, err end
             local size = base.tonumber(string.gsub(line, ";.*", ""), 16)
@@ -219,9 +219,11 @@ local function adjustproxy(reqt)
     local proxy = reqt.proxy or _M.PROXY
     if proxy then
         proxy = url.parse(proxy)
-        return proxy.host, proxy.port or 3128
+        proxy.port = proxy.port or 3128
+        proxy.create = SCHEMES[proxy.scheme].create(reqt)
+        return proxy.host, proxy.port, proxy.create
     else
-        return reqt.host, reqt.port
+        return reqt.host, reqt.port, reqt.create
     end
 end
 
@@ -279,7 +281,7 @@ local function adjustrequest(reqt)
     if not (host and host ~= "") then
         socket.try(nil, "invalid host '" .. base.tostring(nreqt.host) .. "'")
     end
-    -- compute uri if user hasn't overriden
+    -- compute uri if user hasn't overridden
     nreqt.uri = reqt.uri or adjusturi(nreqt)
     -- adjust headers in request
     nreqt.headers = adjustheaders(nreqt)
@@ -291,7 +293,10 @@ local function adjustrequest(reqt)
     end
 
     -- ajust host and port if there is a proxy
-    nreqt.host, nreqt.port = adjustproxy(nreqt)
+    local proxy_create
+    nreqt.host, nreqt.port, proxy_create = adjustproxy(nreqt)
+    if not reqt.create then nreqt.create = proxy_create end
+
     return nreqt
 end
 
@@ -300,6 +305,8 @@ local function shouldredirect(reqt, code, headers)
     if not location then return false end
     location = string.gsub(location, "%s", "")
     if location == "" then return false end
+    -- the RFC says the redirect URL may be relative
+    location = url.absolute(reqt.url, location)
     local scheme = url.parse(location).scheme
     if scheme and (not SCHEMES[scheme]) then return false end
     -- avoid https downgrades
@@ -323,8 +330,7 @@ end
 local trequest, tredirect
 
 --[[local]] function tredirect(reqt, location)
-    -- the RFC says the redirect URL has to be absolute, but some
-    -- servers do not respect that
+    -- the RFC says the redirect URL may be relative
     local newurl = url.absolute(reqt.url, location)
     -- if switching schemes, reset port and create function
     if url.parse(newurl).scheme ~= reqt.scheme then

src/inet.c

@@ -253,7 +253,7 @@ int inet_meth_getpeername(lua_State *L, p_socket ps, int family)
         port, sizeof(port), NI_NUMERICHOST | NI_NUMERICSERV);
     if (err) {
         lua_pushnil(L);
-        lua_pushstring(L, gai_strerror(err));
+        lua_pushstring(L, LUA_GAI_STRERROR(err));
         return 2;
     }
     lua_pushstring(L, name);
@@ -286,11 +286,11 @@ int inet_meth_getsockname(lua_State *L, p_socket ps, int family)
 		name, INET6_ADDRSTRLEN, port, 6, NI_NUMERICHOST | NI_NUMERICSERV);
     if (err) {
         lua_pushnil(L);
-        lua_pushstring(L, gai_strerror(err));
+        lua_pushstring(L, LUA_GAI_STRERROR(err));
         return 2;
     }
     lua_pushstring(L, name);
-    lua_pushstring(L, port);
+    lua_pushinteger(L, (int) strtol(port, (char **) NULL, 10));
     switch (family) {
         case AF_INET: lua_pushliteral(L, "inet"); break;
         case AF_INET6: lua_pushliteral(L, "inet6"); break;

src/luasocket.h

@@ -10,7 +10,7 @@
 /*-------------------------------------------------------------------------* \
 * Current socket library version
 \*-------------------------------------------------------------------------*/
-#define LUASOCKET_VERSION    "LuaSocket 3.0-rc1"
+#define LUASOCKET_VERSION    "LuaSocket 3.1.0"
 #define LUASOCKET_COPYRIGHT  "Copyright (C) 1999-2013 Diego Nehab"
 
 /*-------------------------------------------------------------------------*\

src/makefile

@@ -1,6 +1,6 @@
 # luasocket src/makefile
 #
-# Definitions in this section can be overriden on the command line or in the
+# Definitions in this section can be overridden on the command line or in the
 # environment.
 #
 # These are equivalent:
@@ -272,7 +272,7 @@ SOCKET_win64=wsocket.obj
 #
 SO=$(SO_$(PLAT))
 O=$(O_$(PLAT))
-SOCKET_V=3.0-rc1
+SOCKET_V=3.1.0
 MIME_V=1.0.3
 SOCKET_SO=socket-$(SOCKET_V).$(SO)
 MIME_SO=mime-$(MIME_V).$(SO)

src/options.c

@@ -54,6 +54,33 @@ int opt_meth_getoption(lua_State *L, p_opt opt, p_socket ps)
     return opt->func(L, ps);
 }
 
+/*------------------------------------------------------*/
+/* binds socket to network interface */
+int opt_set_bindtodevice(lua_State *L, p_socket ps)
+{
+#ifndef SO_BINDTODEVICE
+    return luaL_error(L, "SO_BINDTODEVICE is not supported on this operating system");
+#else
+    const char *dev = luaL_checkstring(L, 3);
+    return opt_set(L, ps, SOL_SOCKET, SO_BINDTODEVICE, (char*)dev, strlen(dev)+1);
+#endif
+}
+
+int opt_get_bindtodevice(lua_State *L, p_socket ps)
+{
+#ifndef SO_BINDTODEVICE
+    return luaL_error(L, "SO_BINDTODEVICE is not supported on this operating system");
+#else
+    char dev[IFNAMSIZ];
+    int len = sizeof(dev);
+    int err = opt_get(L, ps, SOL_SOCKET, SO_BINDTODEVICE, &dev, &len);
+    if (err)
+        return err;
+    lua_pushstring(L, dev);
+    return 1;
+#endif
+}
+
 /*------------------------------------------------------*/
 /* enables reuse of local address */
 int opt_set_reuseaddr(lua_State *L, p_socket ps)
@@ -190,6 +217,31 @@ int opt_set_send_buf_size(lua_State *L, p_socket ps)
 	return opt_setint(L, ps, SOL_SOCKET, SO_SNDBUF);
 }
 
+/*------------------------------------------------------*/
+
+#ifdef TCP_FASTOPEN
+int opt_set_tcp_fastopen(lua_State *L, p_socket ps)
+{
+    return opt_setint(L, ps, IPPROTO_TCP, TCP_FASTOPEN);
+}
+#endif
+
+#ifdef TCP_FASTOPEN_CONNECT
+int opt_set_tcp_fastopen_connect(lua_State *L, p_socket ps)
+{
+    return opt_setint(L, ps, IPPROTO_TCP, TCP_FASTOPEN_CONNECT);
+}
+#endif
+
+/*------------------------------------------------------*/
+
+#ifdef TCP_DEFER_ACCEPT
+int opt_set_tcp_defer_accept(lua_State *L, p_socket ps)
+{
+    return opt_setint(L, ps, IPPROTO_TCP, TCP_DEFER_ACCEPT);
+}
+#endif
+
 /*------------------------------------------------------*/
 int opt_set_ip6_unicast_hops(lua_State *L, p_socket ps)
 {

src/options.h

@@ -49,6 +49,13 @@ int opt_set_tcp_keepintvl(lua_State *L, p_socket ps);
 int opt_get_tcp_keepintvl(lua_State *L, p_socket ps);
 #endif
 
+#ifdef TCP_DEFER_ACCEPT
+int opt_set_tcp_defer_accept(lua_State *L, p_socket ps);
+#endif
+
+int opt_set_bindtodevice(lua_State *L, p_socket ps);
+int opt_get_bindtodevice(lua_State *L, p_socket ps);
+
 int opt_set_keepalive(lua_State *L, p_socket ps);
 int opt_get_keepalive(lua_State *L, p_socket ps);
 
@@ -64,6 +71,13 @@ int opt_get_recv_buf_size(lua_State *L, p_socket ps);
 int opt_set_send_buf_size(lua_State *L, p_socket ps);
 int opt_get_send_buf_size(lua_State *L, p_socket ps);
 
+#ifdef TCP_FASTOPEN
+int opt_set_tcp_fastopen(lua_State *L, p_socket ps);
+#endif
+#ifdef TCP_FASTOPEN_CONNECT
+int opt_set_tcp_fastopen_connect(lua_State *L, p_socket ps);
+#endif
+
 int opt_set_ip6_unicast_hops(lua_State *L, p_socket ps);
 int opt_get_ip6_unicast_hops(lua_State *L, p_socket ps);
 

src/smtp.lua

@@ -225,7 +225,7 @@ local function adjust_headers(mesgt)
     lower["date"] = lower["date"] or
         os.date("!%a, %d %b %Y %H:%M:%S ") .. (mesgt.zone or _M.ZONE)
     lower["x-mailer"] = lower["x-mailer"] or socket._VERSION
-    -- this can't be overriden
+    -- this can't be overridden
     lower["mime-version"] = "1.0"
     return lower
 end
@@ -253,4 +253,4 @@ _M.send = socket.protect(function(mailt)
     return s:close()
 end)
 
-return _M
+return _M

src/socket.h

@@ -16,8 +16,10 @@
 \*=========================================================================*/
 #ifdef _WIN32
 #include "wsocket.h"
+#define LUA_GAI_STRERROR gai_strerrorA
 #else
 #include "usocket.h"
+#define LUA_GAI_STRERROR gai_strerror
 #endif
 
 /*=========================================================================*\

src/tcp.c

@@ -71,6 +71,7 @@ static luaL_Reg tcp_methods[] = {
 
 /* socket option handlers */
 static t_opt optget[] = {
+    {"bindtodevice", opt_get_bindtodevice},
     {"keepalive",   opt_get_keepalive},
     {"reuseaddr",   opt_get_reuseaddr},
     {"reuseport",   opt_get_reuseport},
@@ -92,6 +93,7 @@ static t_opt optget[] = {
 };
 
 static t_opt optset[] = {
+    {"bindtodevice", opt_set_bindtodevice},
     {"keepalive",   opt_set_keepalive},
     {"reuseaddr",   opt_set_reuseaddr},
     {"reuseport",   opt_set_reuseport},
@@ -109,6 +111,15 @@ static t_opt optset[] = {
     {"linger",      opt_set_linger},
 	{"recv-buffer-size",     opt_set_recv_buf_size},
 	{"send-buffer-size",     opt_set_send_buf_size},
+#ifdef TCP_DEFER_ACCEPT
+    {"tcp-defer-accept", opt_set_tcp_defer_accept},
+#endif
+#ifdef TCP_FASTOPEN
+    {"tcp-fastopen", opt_set_tcp_fastopen},
+#endif
+#ifdef TCP_FASTOPEN_CONNECT
+    {"tcp-fastopen-connect", opt_set_tcp_fastopen_connect},
+#endif
     {NULL,          NULL}
 };
 

src/udp.c

@@ -191,7 +191,7 @@ static int meth_sendto(lua_State *L) {
     err = getaddrinfo(ip, port, &aihint, &ai);
 	if (err) {
         lua_pushnil(L);
-        lua_pushstring(L, gai_strerror(err));
+        lua_pushstring(L, LUA_GAI_STRERROR(err));
         return 2;
     }
 
@@ -290,7 +290,7 @@ static int meth_receivefrom(lua_State *L) {
         INET6_ADDRSTRLEN, portstr, 6, NI_NUMERICHOST | NI_NUMERICSERV);
 	if (err) {
         lua_pushnil(L);
-        lua_pushstring(L, gai_strerror(err));
+        lua_pushstring(L, LUA_GAI_STRERROR(err));
         if (wanted > sizeof(buf)) free(dgram);
         return 2;
     }

src/unixdgram.c

@@ -16,13 +16,6 @@
 
 #define UNIXDGRAM_DATAGRAMSIZE 8192
 
-/* provide a SUN_LEN macro if sys/un.h doesn't (e.g. Android) */
-#ifndef SUN_LEN
-#define SUN_LEN(ptr) \
-  ((size_t) (((struct sockaddr_un *) 0)->sun_path)  \
-   + strlen ((ptr)->sun_path))
-#endif
-
 /*=========================================================================*\
 * Internal function prototypes
 \*=========================================================================*/
@@ -42,8 +35,8 @@ static int meth_receivefrom(lua_State *L);
 static int meth_sendto(lua_State *L);
 static int meth_getsockname(lua_State *L);
 
-static const char *unixdgram_tryconnect(p_unix un, const char *path);
-static const char *unixdgram_trybind(p_unix un, const char *path);
+static const char *unixdgram_tryconnect(p_unix un, const char *path, size_t len);
+static const char *unixdgram_trybind(p_unix un, const char *path, size_t len);
 
 /* unixdgram object methods */
 static luaL_Reg unixdgram_methods[] = {
@@ -133,13 +126,12 @@ static int meth_send(lua_State *L)
 static int meth_sendto(lua_State *L)
 {
     p_unix un = (p_unix) auxiliar_checkclass(L, "unixdgram{unconnected}", 1);
-    size_t count, sent = 0;
+    size_t count, sent, len = 0;
     const char *data = luaL_checklstring(L, 2, &count);
-    const char *path = luaL_checkstring(L, 3);
+    const char *path = luaL_checklstring(L, 3, &len);
     p_timeout tm = &un->tm;
     int err;
     struct sockaddr_un remote;
-    size_t len = strlen(path);
 
     if (len >= sizeof(remote.sun_path)) {
 		lua_pushnil(L);
@@ -148,7 +140,7 @@ static int meth_sendto(lua_State *L)
 	}
 
     memset(&remote, 0, sizeof(remote));
-    strcpy(remote.sun_path, path);
+    memcpy(remote.sun_path, path, len);
     remote.sun_family = AF_UNIX;
     timeout_markstart(tm);
 #ifdef UNIX_HAS_SUN_LEN
@@ -264,18 +256,22 @@ static int meth_dirty(lua_State *L) {
 /*-------------------------------------------------------------------------*\
 * Binds an object to an address
 \*-------------------------------------------------------------------------*/
-static const char *unixdgram_trybind(p_unix un, const char *path) {
+static const char *unixdgram_trybind(p_unix un, const char *path, size_t len) {
     struct sockaddr_un local;
-    size_t len = strlen(path);
+    int err;
     if (len >= sizeof(local.sun_path)) return "path too long";
     memset(&local, 0, sizeof(local));
-    strcpy(local.sun_path, path);
+    memcpy(local.sun_path, path, len);
     local.sun_family = AF_UNIX;
-    size_t addrlen = SUN_LEN(&local);
 #ifdef UNIX_HAS_SUN_LEN
-    local.sun_len = addrlen + 1;
+    local.sun_len = sizeof(local.sun_family) + sizeof(local.sun_len)
+        + len + 1;
+    err = socket_bind(&un->sock, (SA *) &local, local.sun_len);
+
+#else
+    err = socket_bind(&un->sock, (SA *) &local,
+            sizeof(local.sun_family) + len);
 #endif
-    int err = socket_bind(&un->sock, (SA *) &local, addrlen);
     if (err != IO_DONE) socket_destroy(&un->sock);
     return socket_strerror(err);
 }
@@ -283,8 +279,9 @@ static const char *unixdgram_trybind(p_unix un, const char *path) {
 static int meth_bind(lua_State *L)
 {
     p_unix un = (p_unix) auxiliar_checkclass(L, "unixdgram{unconnected}", 1);
-    const char *path =  luaL_checkstring(L, 2);
-    const char *err = unixdgram_trybind(un, path);
+    size_t len;
+    const char *path =  luaL_checklstring(L, 2, &len);
+    const char *err = unixdgram_trybind(un, path, len);
     if (err) {
         lua_pushnil(L);
         lua_pushstring(L, err);
@@ -313,20 +310,23 @@ static int meth_getsockname(lua_State *L)
 /*-------------------------------------------------------------------------*\
 * Turns a master unixdgram object into a client object.
 \*-------------------------------------------------------------------------*/
-static const char *unixdgram_tryconnect(p_unix un, const char *path)
+static const char *unixdgram_tryconnect(p_unix un, const char *path, size_t len)
 {
     struct sockaddr_un remote;
-    size_t len = strlen(path);
+    int err;
     if (len >= sizeof(remote.sun_path)) return "path too long";
     memset(&remote, 0, sizeof(remote));
-    strcpy(remote.sun_path, path);
+    memcpy(remote.sun_path, path, len);
     remote.sun_family = AF_UNIX;
     timeout_markstart(&un->tm);
-    size_t addrlen = SUN_LEN(&remote);
 #ifdef UNIX_HAS_SUN_LEN
-    remote.sun_len = addrlen + 1;
+    remote.sun_len = sizeof(remote.sun_family) + sizeof(remote.sun_len)
+        + len + 1;
+    err = socket_connect(&un->sock, (SA *) &remote, remote.sun_len, &un->tm);
+#else
+    err = socket_connect(&un->sock, (SA *) &remote,
+            sizeof(remote.sun_family) + len, &un->tm);
 #endif
-    int err = socket_connect(&un->sock, (SA *) &remote, addrlen, &un->tm);
     if (err != IO_DONE) socket_destroy(&un->sock);
     return socket_strerror(err);
 }
@@ -334,8 +334,9 @@ static const char *unixdgram_tryconnect(p_unix un, const char *path)
 static int meth_connect(lua_State *L)
 {
     p_unix un = (p_unix) auxiliar_checkgroup(L, "unixdgram{any}", 1);
-    const char *path =  luaL_checkstring(L, 2);
-    const char *err = unixdgram_tryconnect(un, path);
+    size_t len;
+    const char *path =  luaL_checklstring(L, 2, &len);
+    const char *err = unixdgram_tryconnect(un, path, len);
     if (err) {
         lua_pushnil(L);
         lua_pushstring(L, err);

src/unixstream.c

@@ -33,8 +33,8 @@ static int meth_getstats(lua_State *L);
 static int meth_setstats(lua_State *L);
 static int meth_getsockname(lua_State *L);
 
-static const char *unixstream_tryconnect(p_unix un, const char *path);
-static const char *unixstream_trybind(p_unix un, const char *path);
+static const char *unixstream_tryconnect(p_unix un, const char *path, size_t len);
+static const char *unixstream_trybind(p_unix un, const char *path, size_t len);
 
 /* unixstream object methods */
 static luaL_Reg unixstream_methods[] = {
@@ -181,13 +181,12 @@ static int meth_accept(lua_State *L) {
 /*-------------------------------------------------------------------------*\
 * Binds an object to an address
 \*-------------------------------------------------------------------------*/
-static const char *unixstream_trybind(p_unix un, const char *path) {
+static const char *unixstream_trybind(p_unix un, const char *path, size_t len) {
     struct sockaddr_un local;
-    size_t len = strlen(path);
     int err;
     if (len >= sizeof(local.sun_path)) return "path too long";
     memset(&local, 0, sizeof(local));
-    strcpy(local.sun_path, path);
+    memcpy(local.sun_path, path, len);
     local.sun_family = AF_UNIX;
 #ifdef UNIX_HAS_SUN_LEN
     local.sun_len = sizeof(local.sun_family) + sizeof(local.sun_len)
@@ -204,8 +203,9 @@ static const char *unixstream_trybind(p_unix un, const char *path) {
 
 static int meth_bind(lua_State *L) {
     p_unix un = (p_unix) auxiliar_checkclass(L, "unixstream{master}", 1);
-    const char *path =  luaL_checkstring(L, 2);
-    const char *err = unixstream_trybind(un, path);
+    size_t len;
+    const char *path =  luaL_checklstring(L, 2, &len);
+    const char *err = unixstream_trybind(un, path, len);
     if (err) {
         lua_pushnil(L);
         lua_pushstring(L, err);
@@ -234,14 +234,13 @@ static int meth_getsockname(lua_State *L)
 /*-------------------------------------------------------------------------*\
 * Turns a master unixstream object into a client object.
 \*-------------------------------------------------------------------------*/
-static const char *unixstream_tryconnect(p_unix un, const char *path)
+static const char *unixstream_tryconnect(p_unix un, const char *path, size_t len)
 {
     struct sockaddr_un remote;
     int err;
-    size_t len = strlen(path);
     if (len >= sizeof(remote.sun_path)) return "path too long";
     memset(&remote, 0, sizeof(remote));
-    strcpy(remote.sun_path, path);
+    memcpy(remote.sun_path, path, len);
     remote.sun_family = AF_UNIX;
     timeout_markstart(&un->tm);
 #ifdef UNIX_HAS_SUN_LEN
@@ -259,8 +258,9 @@ static const char *unixstream_tryconnect(p_unix un, const char *path)
 static int meth_connect(lua_State *L)
 {
     p_unix un = (p_unix) auxiliar_checkclass(L, "unixstream{master}", 1);
-    const char *path =  luaL_checkstring(L, 2);
-    const char *err = unixstream_tryconnect(un, path);
+    size_t len;
+    const char *path =  luaL_checklstring(L, 2, &len);
+    const char *err = unixstream_tryconnect(un, path, len);
     if (err) {
         lua_pushnil(L);
         lua_pushstring(L, err);

src/url.lua

@@ -152,7 +152,7 @@ function _M.parse(url, default)
     url = string.gsub(url, "^([%w][%w%+%-%.]*)%:",
         function(s) parsed.scheme = s; return "" end)
     -- get authority
-    url = string.gsub(url, "^//([^/]*)", function(n)
+    url = string.gsub(url, "^//([^/%?#]*)", function(n)
         parsed.authority = n
         return ""
     end)

src/usocket.c

@@ -236,7 +236,7 @@ int socket_sendto(p_socket ps, const char *data, size_t count, size_t *sent,
     *sent = 0;
     if (*ps == SOCKET_INVALID) return IO_CLOSED;
     for ( ;; ) {
-        long put = (long) sendto(*ps, data, count, 0, addr, len); 
+        long put = (long) sendto(*ps, data, count, 0, addr, len);
         if (put >= 0) {
             *sent = put;
             return IO_DONE;
@@ -449,6 +449,6 @@ const char *socket_gaistrerror(int err) {
         case EAI_SERVICE: return PIE_SERVICE;
         case EAI_SOCKTYPE: return PIE_SOCKTYPE;
         case EAI_SYSTEM: return strerror(errno);
-        default: return gai_strerror(err);
+        default: return LUA_GAI_STRERROR(err);
     }
 }

src/wsocket.c

@@ -262,6 +262,7 @@ int socket_recv(p_socket ps, char *data, size_t count, size_t *got,
         if (err != WSAEWOULDBLOCK) {
             if (err != WSAECONNRESET || prev == WSAECONNRESET) return err;
             prev = err;
+            continue;
         }
         if ((err = socket_waitfd(ps, WAITFD_R, tm)) != IO_DONE) return err;
     }
@@ -291,6 +292,7 @@ int socket_recvfrom(p_socket ps, char *data, size_t count, size_t *got,
         if (err != WSAEWOULDBLOCK) {
             if (err != WSAECONNRESET || prev == WSAECONNRESET) return err;
             prev = err;
+            continue;
         }
         if ((err = socket_waitfd(ps, WAITFD_R, tm)) != IO_DONE) return err;
     }
@@ -429,6 +431,6 @@ const char *socket_gaistrerror(int err) {
 #ifdef EAI_SYSTEM
         case EAI_SYSTEM: return strerror(errno);
 #endif
-        default: return gai_strerror(err);
+        default: return LUA_GAI_STRERROR(err);
     }
 }

test/httptest.lua

@@ -265,6 +265,37 @@ ignore = {
 }
 check_request(request, expect, ignore)
 
+-- Use https://httpbin.org/#/Dynamic_data/get_base64__value_ for testing
+-----------------------------------------------------
+io.write("testing absolute https redirection: ")
+request = {
+    url = "https://httpbin.org/redirect-to?url=https://httpbin.org/base64/THVhIFNvY2tldA=="
+}
+expect = {
+    code = 200,
+    body = "Lua Socket"
+}
+ignore = {
+    status = 1,
+    headers = 1
+}
+check_request(request, expect, ignore)
+
+-----------------------------------------------------
+io.write("testing relative https redirection: ")
+request = {
+    url = "https://httpbin.org/redirect-to?url=/base64/THVhIFNvY2tldA=="
+}
+expect = {
+    code = 200,
+    body = "Lua Socket"
+}
+ignore = {
+    status = 1,
+    headers = 1
+}
+check_request(request, expect, ignore)
+
 ------------------------------------------------------------------------
 --[[
 io.write("testing proxy with redirection: ")