[libpng16] Cause pngtest --strict to fail on any warning from libpng (not just

errors) and cause it not to fail at the comparison step if libpng lacks support
for writing chunks that it reads from the input (currently only implemented
for compressed text chunks).

ANNOUNCE

@@ -425,6 +425,12 @@ Version 1.6.0beta27 [August 10, 2012]
   Insist on autotools 1.12.1 for git builds because there are security issues
     with 1.12 and insisting on anything less would allow 1.12 to be used.
   Removed info_ptr->signature[8] from WRITE-only builds.
+  Add some conditions for compiling png_fixed().  This is a small function
+    but it requires "-lm" on some platforms.
+  Cause pngtest --strict to fail on any warning from libpng (not just errors)
+    and cause it not to fail at the comparison step if libpng lacks support
+    for writing chunks that it reads from the input (currently only implemented
+    for compressed text chunks).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CHANGES

@@ -4176,6 +4176,12 @@ Version 1.6.0beta27 [August 10, 2012]
   Insist on autotools 1.12.1 for git builds because there are security issues
     with 1.12 and insisting on anything less would allow 1.12 to be used.
   Removed info_ptr->signature[8] from WRITE-only builds.
+  Add some conditions for compiling png_fixed().  This is a small function
+    but it requires "-lm" on some platforms.
+  Cause pngtest --strict to fail on any warning from libpng (not just errors)
+    and cause it not to fail at the comparison step if libpng lacks support
+    for writing chunks that it reads from the input (currently only implemented
+    for compressed text chunks).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

pngtest.c

@@ -88,6 +88,9 @@ static char tIME_string[PNG_tIME_STRING_LENGTH] = "tIME chunk is not present";
 
 static int verbose = 0;
 static int strict = 0;
+static int unsupported_chunks = 0; /* chunk unsupported by libpng in input */
+static int error_count = 0; /* count calls to png_error */
+static int warning_count = 0; /* count calls to png_warning */
 
 #ifdef __TURBOC__
 #include <mem.h>
@@ -391,6 +394,8 @@ pngtest_warning(png_structp png_ptr, png_const_charp message)
    char *test;
    test = png_get_error_ptr(png_ptr);
 
+   ++warning_count;
+
    if (test == NULL)
      fprintf(STDERR, "%s: libpng warning: %s\n", name, message);
 
@@ -406,6 +411,8 @@ pngtest_warning(png_structp png_ptr, png_const_charp message)
 static void PNGCBAPI
 pngtest_error(png_structp png_ptr, png_const_charp message)
 {
+   ++error_count;
+
    pngtest_warning(png_ptr, message);
    /* We can return because png_error calls the default handler, which is
     * actually OK in this case.
@@ -625,6 +632,45 @@ static int PNGCBAPI read_user_chunk_callback(png_struct *png_ptr,
 #endif
 /* END of code to demonstrate user chunk support */
 
+/* START of code to check that libpng has the required text support; this only
+ * checks for the write support because if read support is missing the chunk
+ * will simply not be reported back to pngtest.
+ */
+#ifdef PNG_TEXT_SUPPORTED
+static void
+pngtest_check_text_support(png_const_structp png_ptr, png_textp text_ptr,
+   int num_text)
+{
+   while (num_text > 0)
+   {
+      switch (text_ptr[--num_text].compression)
+      {
+         case PNG_TEXT_COMPRESSION_NONE:
+            break;
+
+         case PNG_TEXT_COMPRESSION_zTXt:
+#           ifndef PNG_WRITE_zTXt_SUPPORTED
+               ++unsupported_chunks;
+#           endif
+            break;
+
+         case PNG_ITXT_COMPRESSION_NONE:
+         case PNG_ITXT_COMPRESSION_zTXt:
+#           ifndef PNG_WRITE_iTXt_SUPPORTED
+               ++unsupported_chunks;
+#           endif
+            break;
+
+         default:
+            /* This is an error */
+            png_error(png_ptr, "invalid text chunk compression field");
+            break;
+      }
+   }
+}
+#endif
+/* END of code to check that libpng has the required text support */
+
 /* Test one file */
 static int
 test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
@@ -1022,6 +1068,8 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       {
          pngtest_debug1("Handling %d iTXt/tEXt/zTXt chunks", num_text);
 
+         pngtest_check_text_support(read_ptr, text_ptr, num_text);
+
          if (verbose)
          {
             int i;
@@ -1231,6 +1279,8 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       {
          pngtest_debug1("Handling %d iTXt/tEXt/zTXt chunks", num_text);
 
+         pngtest_check_text_support(read_ptr, text_ptr, num_text);
+
          if (verbose)
          {
             int i;
@@ -1324,6 +1374,37 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
    FCLOSE(fpin);
    FCLOSE(fpout);
 
+   /* Summarize any warnings or errors and in 'strict' mode fail the test.
+    * Unsupported chunks can result in warnings, in that case ignore the strict
+    * setting, otherwise fail the test on warnings as well as errors.
+    */
+   if (error_count > 0)
+   {
+      /* We don't really expect to get here because of the setjmp handling
+       * above, but this is safe.
+       */
+      fprintf(STDERR, "%s: %d libpng errors found (%d warnings)\n",
+         inname, error_count, warning_count);
+
+      if (strict != 0)
+         return (1);
+   }
+
+   else if (unsupported_chunks > 0)
+   {
+      fprintf(STDERR, "%s: unsupported chunks (%d)%s\n",
+         inname, unsupported_chunks, strict ? ": IGNORED --strict!" : "");
+   }
+
+   else if (warning_count > 0)
+   {
+      fprintf(STDERR, "%s: %d libpng warnings found\n",
+         inname, warning_count);
+
+      if (strict != 0)
+         return (1);
+   }
+
    pngtest_debug("Opening files for comparison");
    if ((fpin = fopen(inname, "rb")) == NULL)
    {
@@ -1350,7 +1431,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          fprintf(STDERR, "\nFiles %s and %s are of a different size\n",
                  inname, outname);
 
-         if (wrote_question == 0)
+         if (wrote_question == 0 && unsupported_chunks == 0)
          {
             fprintf(STDERR,
          "   Was %s written with the same maximum IDAT chunk size (%d bytes),",
@@ -1366,7 +1447,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          FCLOSE(fpin);
          FCLOSE(fpout);
 
-         if (strict != 0)
+         if (strict != 0 && unsupported_chunks == 0)
            return (1);
 
          else
@@ -1380,7 +1461,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       {
          fprintf(STDERR, "\nFiles %s and %s are different\n", inname, outname);
 
-         if (wrote_question == 0)
+         if (wrote_question == 0 && unsupported_chunks == 0)
          {
             fprintf(STDERR,
          "   Was %s written with the same maximum IDAT chunk size (%d bytes),",
@@ -1396,7 +1477,12 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          FCLOSE(fpin);
          FCLOSE(fpout);
 
-         if (strict != 0)
+         /* NOTE: the unsupported_chunks escape is permitted here because
+          * unsupported text chunk compression will result in the compression
+          * mode being changed (to NONE) yet, in the test case, the result can
+          * be exactly the same size!
+          */
+         if (strict != 0 && unsupported_chunks == 0)
            return (1);
 
          else