[libpng16] Use a user warning handler in contrib/gregbook/readpng2.c

instead of the default.

ANNOUNCE

 
-Libpng 1.6.10beta02 - February 20, 2014
+Libpng 1.6.10beta02 - February 21, 2014
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -55,7 +55,7 @@ Version 1.6.10beta01 [February 9, 2014]
     and it adds corresponding code to pngimage.c to handle such options
     by not attempting to test them.
 
-Version 1.6.10beta02 [February 20, 2014]
+Version 1.6.10beta02 [February 21, 2014]
   Moved redefines of png_error(), png_warning(), png_chunk_error(),
     and png_chunk_warning() from pngpriv.h to png.h to make them visible
     to libpng-calling applications.
@@ -72,6 +72,9 @@ Version 1.6.10beta02 [February 20, 2014]
     it more robust against future programming errors.
   Check for __has_extension before using it in pngconf.h, to
     support older Clang versions (Jeremy Sequoia).
+  Treat CRC error handling with png_set_crc_action(), instead of with
+    png_set_benign_errors(), which has been the case since libpng-1.6.0beta18.
+  Use a user warning handler in contrib/gregbook/readpng2.c instead of default.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CHANGES

@@ -4829,7 +4829,7 @@ Version 1.6.10beta01 [February 9, 2014]
     and it adds corresponding code to pngimage.c to handle such options
     by not attempting to test them.
 
-Version 1.6.10beta02 [February 20, 2014]
+Version 1.6.10beta02 [February 21, 2014]
   Moved redefines of png_error(), png_warning(), png_chunk_error(),
     and png_chunk_warning() from pngpriv.h to png.h to make them visible
     to libpng-calling applications.
@@ -4846,6 +4846,9 @@ Version 1.6.10beta02 [February 20, 2014]
     it more robust against future programming errors.
   Check for __has_extension before using it in pngconf.h, to
     support older Clang versions (Jeremy Sequoia).
+  Treat CRC error handling with png_set_crc_action(), instead of with
+    png_set_benign_errors(), which has been the case since libpng-1.6.0beta18.
+  Use a user warning handler in contrib/gregbook/readpng2.c instead of default.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

contrib/gregbook/readpng2.c

@@ -69,6 +69,7 @@ static void readpng2_row_callback(png_structp png_ptr, png_bytep new_row,
                                  png_uint_32 row_num, int pass);
 static void readpng2_end_callback(png_structp png_ptr, png_infop info_ptr);
 static void readpng2_error_handler(png_structp png_ptr, png_const_charp msg);
+static void readpng2_warning_handler(png_structp png_ptr, png_const_charp msg);
 
 
 
@@ -104,7 +105,7 @@ int readpng2_init(mainprog_info *mainprog_ptr)
     /* could also replace libpng warning-handler (final NULL), but no need: */
 
     png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, mainprog_ptr,
-      readpng2_error_handler, NULL);
+      readpng2_error_handler, readpng2_warning_handler);
     if (!png_ptr)
         return 4;   /* out of memory */
 
@@ -467,7 +468,11 @@ void readpng2_cleanup(mainprog_info *mainprog_ptr)
 }
 
 
-
+static void readpng2_warning_handler(png_structp png_ptr, png_const_charp msg)
+{
+    fprintf(stderr, "readpng2 libpng warning: %s\n", msg);
+    fflush(stderr);
+}
 
 
 static void readpng2_error_handler(png_structp png_ptr, png_const_charp msg)