Refactor cjpeg.c to provide test interface

cjpeg.c contains a standalone program to encode JPEG images. One use
of cjpeg is to generate input for libjpeg-turbo unit tests.

This commit refactors cjpeg.c to provide an interface to run the
cjpeg code programmatically. A gtest wrapper containing JPEG
compression unit tests will be introduced in a subsequent commit.

Bug: 993876
Change-Id: Ia6ee40042f7953acb5ae6b5b0bc0e08b630f5393

2 files changed, 12 insertions, 8 deletions

diff --git a/README.chromium b/README.chromium
index e4d3b2f..1bade66 100644
--- a/README.chromium
+++ b/README.chromium
@@ -78,6 +78,7 @@ following changes which are not merged to upstream:
   - Add gtest wrapper for tjbench tests
   - Move tbench logs from stdout to stderr
   - Write tjunittest output files to sdcard on Android
+  - Refactor cjpeg.c to provide test interface
 
 Refer to working-with-nested-repos [1] for details of how to setup your git
 svn client to update the code (for making local changes, cherry picking from
diff --git a/cjpeg.c b/cjpeg.c
index 07e7db1..e807510 100644
--- a/cjpeg.c
+++ b/cjpeg.c
@@ -501,7 +501,11 @@ parse_switches(j_compress_ptr cinfo, int argc, char **argv,
  */
 
 int
+#ifdef GTEST
+cjpeg(int argc, char **argv)
+#else
 main(int argc, char **argv)
+#endif
 {
   struct jpeg_compress_struct cinfo;
   struct jpeg_error_mgr jerr;
@@ -583,7 +587,7 @@ main(int argc, char **argv)
   if (file_index < argc) {
     if ((input_file = fopen(argv[file_index], READ_BINARY)) == NULL) {
       fprintf(stderr, "%s: can't open %s\n", progname, argv[file_index]);
-      exit(EXIT_FAILURE);
+      return EXIT_FAILURE;
     }
   } else {
     /* default input file is stdin */
@@ -594,7 +598,7 @@ main(int argc, char **argv)
   if (outfilename != NULL) {
     if ((output_file = fopen(outfilename, WRITE_BINARY)) == NULL) {
       fprintf(stderr, "%s: can't open %s\n", progname, outfilename);
-      exit(EXIT_FAILURE);
+      return EXIT_FAILURE;
     }
   } else if (!memdst) {
     /* default output file is stdout */
@@ -604,26 +608,26 @@ main(int argc, char **argv)
   if (icc_filename != NULL) {
     if ((icc_file = fopen(icc_filename, READ_BINARY)) == NULL) {
       fprintf(stderr, "%s: can't open %s\n", progname, icc_filename);
-      exit(EXIT_FAILURE);
+      return EXIT_FAILURE;
     }
     if (fseek(icc_file, 0, SEEK_END) < 0 ||
         (icc_len = ftell(icc_file)) < 1 ||
         fseek(icc_file, 0, SEEK_SET) < 0) {
       fprintf(stderr, "%s: can't determine size of %s\n", progname,
               icc_filename);
-      exit(EXIT_FAILURE);
+      return EXIT_FAILURE;
     }
     if ((icc_profile = (JOCTET *)malloc(icc_len)) == NULL) {
       fprintf(stderr, "%s: can't allocate memory for ICC profile\n", progname);
       fclose(icc_file);
-      exit(EXIT_FAILURE);
+      return EXIT_FAILURE;
     }
     if (fread(icc_profile, icc_len, 1, icc_file) < 1) {
       fprintf(stderr, "%s: can't read ICC profile from %s\n", progname,
               icc_filename);
       free(icc_profile);
       fclose(icc_file);
-      exit(EXIT_FAILURE);
+      return EXIT_FAILURE;
     }
     fclose(icc_file);
   }
@@ -690,6 +694,5 @@ main(int argc, char **argv)
     free(icc_profile);
 
   /* All done. */
-  exit(jerr.num_warnings ? EXIT_WARNING : EXIT_SUCCESS);
-  return 0;                     /* suppress no-return-value warnings */
+  return (jerr.num_warnings ? EXIT_WARNING : EXIT_SUCCESS);
 }