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src/Source/LibPNG/pngrutil.c  view on Meta::CPAN

      /* Now store the chunk in the chunk list if appropriate, and if the limits
       * permit it.
       */
      if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
         (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
          PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
      {
#     ifdef PNG_USER_LIMITS_SUPPORTED
         switch (png_ptr->user_chunk_cache_max)
         {
            case 2:
               png_ptr->user_chunk_cache_max = 1;
               png_chunk_benign_error(png_ptr, "no space in chunk cache");
               /* FALL THROUGH */
            case 1:
               /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
                * chunk being skipped, now there will be a hard error below.
                */
               break;

            default: /* not at limit */
               --(png_ptr->user_chunk_cache_max);
               /* FALL THROUGH */
            case 0: /* no limit */
#     endif /* USER_LIMITS */
               /* Here when the limit isn't reached or when limits are compiled
                * out; store the chunk.
                */
               png_set_unknown_chunks(png_ptr, info_ptr,
                  &png_ptr->unknown_chunk, 1);
               handled = 1;
#     ifdef PNG_USER_LIMITS_SUPPORTED
               break;
         }
#     endif
      }
#  else /* no store support: the chunk must be handled by the user callback */
      PNG_UNUSED(info_ptr)
#  endif

   /* Regardless of the error handling below the cached data (if any) can be
    * freed now.  Notice that the data is not freed if there is a png_error, but
    * it will be freed by destroy_read_struct.
    */
   if (png_ptr->unknown_chunk.data != NULL)
      png_free(png_ptr, png_ptr->unknown_chunk.data);
   png_ptr->unknown_chunk.data = NULL;

#else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
   /* There is no support to read an unknown chunk, so just skip it. */
   png_crc_finish(png_ptr, length);
   PNG_UNUSED(info_ptr)
   PNG_UNUSED(keep)
#endif /* !READ_UNKNOWN_CHUNKS */

   /* Check for unhandled critical chunks */
   if (handled == 0 && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
      png_chunk_error(png_ptr, "unhandled critical chunk");
}

/* This function is called to verify that a chunk name is valid.
 * This function can't have the "critical chunk check" incorporated
 * into it, since in the future we will need to be able to call user
 * functions to handle unknown critical chunks after we check that
 * the chunk name itself is valid.
 */

/* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
 *
 * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
 */

void /* PRIVATE */
png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
{
   int i;

   png_debug(1, "in png_check_chunk_name");

   for (i=1; i<=4; ++i)
   {
      int c = chunk_name & 0xff;

      if (c < 65 || c > 122 || (c > 90 && c < 97))
         png_chunk_error(png_ptr, "invalid chunk type");

      chunk_name >>= 8;
   }
}

/* Combines the row recently read in with the existing pixels in the row.  This
 * routine takes care of alpha and transparency if requested.  This routine also
 * handles the two methods of progressive display of interlaced images,
 * depending on the 'display' value; if 'display' is true then the whole row
 * (dp) is filled from the start by replicating the available pixels.  If
 * 'display' is false only those pixels present in the pass are filled in.
 */
void /* PRIVATE */
png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
{
   unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
   png_const_bytep sp = png_ptr->row_buf + 1;
   png_alloc_size_t row_width = png_ptr->width;
   unsigned int pass = png_ptr->pass;
   png_bytep end_ptr = 0;
   png_byte end_byte = 0;
   unsigned int end_mask;

   png_debug(1, "in png_combine_row");

   /* Added in 1.5.6: it should not be possible to enter this routine until at
    * least one row has been read from the PNG data and transformed.
    */
   if (pixel_depth == 0)
      png_error(png_ptr, "internal row logic error");

   /* Added in 1.5.4: the pixel depth should match the information returned by
    * any call to png_read_update_info at this point.  Do not continue if we got
    * this wrong.
    */
   if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=