luasocket/etc/get.lua

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-----------------------------------------------------------------------------
-- Little program to download files from URLs
-- LuaSocket sample files
-- Author: Diego Nehab
-- RCS ID: $Id$
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-----------------------------------------------------------------------------
-- formats a number of seconds into human readable form
function nicetime(s)
local l = "s"
if s > 60 then
s = s / 60
l = "m"
if s > 60 then
s = s / 60
l = "h"
if s > 24 then
s = s / 24
l = "d" -- hmmm
end
end
end
if l == "s" then return string.format("%5.0f%s", s, l)
else return string.format("%5.2f%s", s, l) end
end
-- formats a number of bytes into human readable form
function nicesize(b)
local l = "B"
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if b > 1024 then
b = b / 1024
l = "KB"
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if b > 1024 then
b = b / 1024
l = "MB"
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if b > 1024 then
b = b / 1024
l = "GB" -- hmmm
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end
end
end
return string.format("%7.2f%2s", b, l)
end
-- returns a string with the current state of the download
local remaining_s = "%s received, %s/s throughput, %2.0f%% done, %s remaining"
local elapsed_s = "%s received, %s/s throughput, %s elapsed "
function gauge(got, delta, size)
local rate = got / delta
if size and size >= 1 then
return string.format(remaining_s, nicesize(got), nicesize(rate),
100*got/size, nicetime((size-got)/rate))
else
return string.format(elapsed_s, nicesize(got),
nicesize(rate), nicetime(delta))
end
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end
-- creates a new instance of a receive_cb that saves to disk
-- kind of copied from luasocket's manual callback examples
function stats(size)
local start = socket.time()
local got = 0
return function(chunk)
-- elapsed time since start
local delta = socket.time() - start
if chunk then
-- total bytes received
got = got + string.len(chunk)
-- not enough time for estimate
if delta > 0.1 then
io.stderr:write("\r", gauge(got, delta, size))
io.stderr:flush()
end
else
-- close up
io.stderr:write("\r", gauge(got, delta), "\n")
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end
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return chunk
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end
end
-- determines the size of a http file
function gethttpsize(url)
local respt = socket.http.request {method = "HEAD", url = url}
if respt.code == 200 then
return tonumber(respt.headers["content-length"])
end
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end
-- downloads a file using the http protocol
function getbyhttp(url, file)
local save = ltn12.sink.file(file or io.stdout)
-- only print feedback if output is not stdout
if file then save = ltn12.sink.chain(stats(gethttpsize(url)), save) end
local respt = socket.http.request {url = url, sink = save }
if respt.code ~= 200 then print(respt.status or respt.error) end
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end
-- downloads a file using the ftp protocol
function getbyftp(url, file)
local save = ltn12.sink.file(file or io.stdout)
-- only print feedback if output is not stdout
-- and we don't know how big the file is
if file then save = ltn12.sink.chain(stats(), save) end
local ret, err = socket.ftp.get {url = url, sink = save, type = "i"}
if err then print(err) end
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end
-- determines the scheme
function getscheme(url)
-- this is an heuristic to solve a common invalid url poblem
if not string.find(url, "//") then url = "//" .. url end
local parsed = socket.url.parse(url, {scheme = "http"})
return parsed.scheme
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end
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-- gets a file either by http or ftp, saving as <name>
function get(url, name)
local fout = name and io.open(name, "wb")
local scheme = getscheme(url)
if scheme == "ftp" then getbyftp(url, fout)
elseif scheme == "http" then getbyhttp(url, fout)
else print("unknown scheme" .. scheme) end
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end
-- main program
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arg = arg or {}
if table.getn(arg) < 1 then
io.write("Usage:\n luasocket get.lua <remote-url> [<local-file>]\n")
os.exit(1)
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else get(arg[1], arg[2]) end