Be tolerant of zero-page jobs

https://github.com/OpenPrinting/cups-filters/issues/117

CMakeLists.txt

@@ -116,15 +116,17 @@ add_executable(brdecode EXCLUDE_FROM_ALL src/brdecode.cc)
 add_executable(test_lest test/test_lest.cc)
 add_executable(test_line test/test_line.cc src/line.cc)
 add_executable(test_block test/test_block.cc)
+add_executable(test_job test/test_job.cc src/job.cc src/line.cc)
 
 enable_testing()
 add_test(test_lest test_lest)
 add_test(test_line test_line)
 add_test(test_block test_block)
+add_test(test_job test_job)
 
 # Autotools-style "make check" command
 add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND})
-add_dependencies(check test_lest test_line test_block)
+add_dependencies(check test_lest test_line test_block test_job)
 
 
 # Installation

src/job.cc

@@ -26,17 +26,18 @@
 job::job(FILE *out, const std::string &job_name)
     : out_(out),
       job_name_(job_name),
-      page_params_() {
+      page_params_(),
+      pages_(0) {
   // Delete dubious characters from job name
   std::replace_if(job_name_.begin(), job_name_.end(), [](char c) {
       return c < 32 || c >= 127 || c == '"' || c == '\\';
     }, ' ');
-
-  begin_job();
 }
 
 job::~job() {
+  if (pages_ != 0) {
     end_job();
+  }
 }
 
 void job::begin_job() {
@@ -86,6 +87,11 @@ void job::encode_page(const page_params &page_params,
                       int lines,
                       int linesize,
                       nextline_fn nextline) {
+  if (pages_ == 0) {
+    begin_job();
+  }
+  ++pages_;
+
   if (!(page_params_ == page_params)) {
     page_params_ = page_params;
     write_page_header();

src/job.h

@@ -55,6 +55,10 @@ class job {
                    int linesize,
                    nextline_fn nextline);
 
+  int pages() const {
+    return pages_;
+  }
+
  private:
   void begin_job();
   void end_job();
@@ -63,6 +67,7 @@ class job {
   FILE *out_;
   std::string job_name_;
   page_params page_params_;
+  int pages_;
 };
 
 #endif  // JOB_H

src/main.cc

@@ -170,7 +170,6 @@ int main(int argc, char *argv[]) {
     return 1;
   }
 
-  int pages = 0;
   {
     job job(stdout, ascii_job_name(job_id, job_user, job_name));
     cups_page_header2_t header;
@@ -179,11 +178,11 @@ int main(int argc, char *argv[]) {
           || header.cupsBitsPerColor != 1
           || header.cupsNumColors != 1
           || header.cupsBytesPerLine > 10000) {
-        fprintf(stderr, "ERROR: " PACKAGE ": Page %d: Bogus raster data.\n", pages + 1);
+        fprintf(stderr, "ERROR: " PACKAGE ": Page %d: Bogus raster data.\n", job.pages() + 1);
         dump_page_header(header);
         return 1;
       }
-      if (pages == 0) {
+      if (job.pages() == 0) {
         fprintf(stderr, "DEBUG: " PACKAGE ": Page header of first page\n");
         dump_page_header(header);
       }
@@ -191,13 +190,12 @@ int main(int argc, char *argv[]) {
                       header.cupsHeight,
                       header.cupsBytesPerLine,
                       next_line);
-      fprintf(stderr, "PAGE: %d %d\n", ++pages, header.NumCopies);
-    }
+      fprintf(stderr, "PAGE: %d %d\n", job.pages(), header.NumCopies);
     }
 
-  if (pages == 0) {
+    if (job.pages() == 0) {
       fprintf(stderr, "ERROR: " PACKAGE ": No pages were found.\n");
-    return 1;
+    }
   }
 
   fflush(stdout);

test/test_job.cc

@@ -0,0 +1,35 @@
+// This file is part of the brlaser printer driver.
+//
+// Copyright 2020 Peter De Wachter
+//
+// brlaser is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 2 of the License, or
+// (at your option) any later version.
+//
+// brlaser is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with brlaser.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "lest.hpp"
+#include "tempfile.h"
+#include "../src/job.h"
+
+const lest::test specification[] = {
+  "An empty job produces no output",
+  [] {
+    tempfile f;
+    {
+      job j(f.file(), "name");
+    }
+    EXPECT(f.data().empty());
+  },
+};
+
+int main() {
+  return lest::run(specification);
+}