[libpng16] Revert ADLER32 error handling in pngrutil.c and pngpread.c.

ANNOUNCE

-Libpng 1.6.27beta02 - November 2, 2016
+Libpng 1.6.27beta02 - November 8, 2016
 
 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.
@@ -31,7 +31,8 @@ Version 1.6.27beta01 [November 2, 2016]
     entire PNG image instead of rejecting just the iCCP chunk with a warning,
     if built with zlib-1.2.8.1.
 
-Version 1.6.27beta02 [November 2, 2016]
+Version 1.6.27beta02 [November 8, 2016]
+  Revert ADLER32 error handling in pngrutil.c and pngpread.c.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CHANGES

@@ -5760,7 +5760,8 @@ Version 1.6.27beta01 [November 2, 2016]
     entire PNG image instead of rejecting just the iCCP chunk with a warning,
     if built with zlib-1.2.8.1.
 
-Version 1.6.27beta02 [November 2, 2016]
+Version 1.6.27beta02 [November 8, 2016]
+  Revert ADLER32 error handling in pngrutil.c and pngpread.c.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

pngpread.c

@@ -684,12 +684,7 @@ png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
             png_warning(png_ptr, "Truncated compressed data in IDAT");
 
          else
-         {
-            if (ret == Z_DATA_ERROR)
-               png_benign_error(png_ptr, "IDAT: ADLER32 checksum mismatch");
-            else
-               png_error(png_ptr, "Decompression error in IDAT");
-         }
+            png_error(png_ptr, "Decompression error in IDAT");
 
          /* Skip the check on unprocessed input */
          return;

pngrutil.c

@@ -4108,15 +4108,7 @@ png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
          png_zstream_error(png_ptr, ret);
 
          if (output != NULL)
-         {
-            if(!strncmp(png_ptr->zstream.msg,"incorrect data check",20))
-            {
-               png_chunk_benign_error(png_ptr, "ADLER32 checksum mismatch");
-               continue;
-            }
-            else
-               png_chunk_error(png_ptr, png_ptr->zstream.msg);
-         }
+            png_chunk_error(png_ptr, png_ptr->zstream.msg);
 
          else /* checking */
          {