pngrutil.c

hl2 source code. Do not use it illegal.

            {
               text_size = key_size + sizeof(msg) + 1;
               text = (png_charp)png_malloc(png_ptr, (png_uint_32)text_size);
               png_memcpy(text, key, key_size);
            }

            text[text_size - 1] = 0x00;

            /* Copy what we can of the error message into the text chunk */
            text_size = (png_size_t)(slength - (text - key) - 1);
            text_size = sizeof(msg) > text_size ? text_size : sizeof(msg);
            png_memcpy(text + key_size, msg, text_size + 1);
            break;
         }
         if (!png_ptr->zstream.avail_out || ret == Z_STREAM_END)
         {
            if (text == NULL)
            {
               text = (png_charp)png_malloc(png_ptr,
                  (png_uint_32)(png_ptr->zbuf_size - png_ptr->zstream.avail_out
                     + key_size + 1));
               png_memcpy(text + key_size, png_ptr->zbuf,
                  png_ptr->zbuf_size - png_ptr->zstream.avail_out);
               png_memcpy(text, key, key_size);
               text_size = key_size + png_ptr->zbuf_size -
                  png_ptr->zstream.avail_out;
               *(text + text_size) = 0x00;
            }
            else
            {
               png_charp tmp;

               tmp = text;
               text = (png_charp)png_malloc(png_ptr, (png_uint_32)(text_size +
                  png_ptr->zbuf_size - png_ptr->zstream.avail_out + 1));
               png_memcpy(text, tmp, text_size);
               png_free(png_ptr, tmp);
               png_memcpy(text + text_size, png_ptr->zbuf,
                  (png_ptr->zbuf_size - png_ptr->zstream.avail_out));
               text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
               *(text + text_size) = 0x00;
            }
            if (ret != Z_STREAM_END)
            {
               png_ptr->zstream.next_out = png_ptr->zbuf;
               png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
            }
            else
            {
               break;
            }
         }
      }

      inflateReset(&png_ptr->zstream);
      png_ptr->zstream.avail_in = 0;

      png_free(png_ptr, key);
      key = text;
      text += key_size;
   }
   else /* if (comp_type >= PNG_TEXT_COMPRESSION_LAST) */
   {
      png_size_t text_size;
#if !defined(PNG_NO_STDIO)
      char umsg[50];

      sprintf(umsg, "Unknown zTXt compression type %d", comp_type);
      png_warning(png_ptr, umsg);
#else
      png_warning(png_ptr, "Unknown zTXt compression type");
#endif

      /* Copy what we can of the error message into the text chunk */
      text_size = (png_size_t)(slength - (text - key) - 1);
      text_size = sizeof(msg) > text_size ? text_size : sizeof(msg);
      png_memcpy(text, msg, text_size + 1);
   }

   text_ptr = (png_textp)png_malloc(png_ptr, (png_uint_32)sizeof(png_text));
   text_ptr->compression = comp_type;
   text_ptr->key = key;
   text_ptr->text = text;

   png_set_text(png_ptr, info_ptr, text_ptr, 1);

   png_free(png_ptr, text_ptr);
}
#endif

/* This function is called when we haven't found a handler for a
   chunk.  If there isn't a problem with the chunk itself (ie bad
   chunk name, CRC, or a critical chunk), the chunk is silently ignored. */
void
png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
   png_debug(1, "in png_handle_unknown\n");

   /* In the future we can have code here that calls user-supplied
    * callback functions for unknown chunks before they are ignored or
    * cause an error.
    */
   png_check_chunk_name(png_ptr, png_ptr->chunk_name);

   if (!(png_ptr->chunk_name[0] & 0x20))
   {
      png_chunk_error(png_ptr, "unknown critical chunk");

      /* to quiet compiler warnings about unused info_ptr */
      if (info_ptr == NULL)
         return;
   }

   if (png_ptr->mode & PNG_HAVE_IDAT)
      png_ptr->mode |= PNG_AFTER_IDAT;

   png_crc_finish(png_ptr, length);

}

/* 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. */

#define isnonalpha(c) ((c) < 41 || (c) > 122 || ((c) > 90 && (c) < 97))

void
png_check_chunk_name(png_structp png_ptr, png_bytep chunk_name)
{
   png_debug(1, "in png_check_chunk_name\n");
   if (isnonalpha(chunk_name[0]) || isnonalpha(chunk_name[1]) ||
       isnonalpha(chunk_name[2]) || isnonalpha(chunk_name[3]))
   {
      png_chunk_error(png_ptr, "invalid chunk type");
   }
}

/* 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 mask value.
   The mask value describes which pixels are to be combined with
   the row.  The pattern always repeats every 8 pixels, so just 8
   bits are needed.  A one indicates the pixel is to be combined,
   a zero indicates the pixel is to be skipped.  This is in addition
   to any alpha or transparency value associated with the pixel.  If
   you want all pixels to be combined, pass 0xff (255) in mask.  */
void
png_combine_row(png_structp png_ptr, png_bytep row,
   int mask)
{
   png_debug(1,"in png_combine_row\n");
   if (mask == 0xff)
   {
      png_memcpy(row, png_ptr->row_buf + 1,
         (png_size_t)((png_ptr->width *
         png_ptr->row_info.pixel_depth + 7) >> 3));
   }
   else
   {
      switch (png_ptr->row_info.pixel_depth)
      {
         case 1:
         {
            png_bytep sp = png_ptr->row_buf + 1;
            png_bytep dp = row;
            int s_inc, s_start, s_end;
            int m = 0x80;
            int shift;
            png_uint_32 i;
            png_uint_32 row_width = png_ptr->width;

#if defined(PNG_READ_PACKSWAP_SUPPORTED)
            if (png_ptr->transformations & PNG_PACKSWAP)
            {
                s_start = 0;
                s_end = 7;
                s_inc = 1;
            }
            else
#endif
            {
                s_start = 7;
                s_end = 0;
                s_inc = -1;
            }

            shift = s_start;

            for (i = 0; i < row_width; i++)
            {
               if (m & mask)
               {
                  int value;

                  value = (*sp >> shift) & 0x1;
                  *dp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);
                  *dp |= (png_byte)(value << shift);
               }

               if (shift == s_end)
               {
                  shift = s_start;
                  sp++;
                  dp++;
               }
               else
                  shift += s_inc;

               if (m == 1)
                  m = 0x80;
               else
                  m >>= 1;
            }
            break;
         }
         case 2:
         {
            png_bytep sp = png_ptr->row_buf + 1;
            png_bytep dp = row;
            int s_start, s_end, s_inc;
            int m = 0x80;
            int shift;
            png_uint_32 i;
            png_uint_32 row_width = png_ptr->width;
            int value;

#if defined(PNG_READ_PACKSWAP_SUPPORTED)
            if (png_ptr->transformations & PNG_PACKSWAP)
            {
               s_start = 0;
               s_end = 6;
               s_inc = 2;
            }
            else
#endif
            {
               s_start = 6;
               s_end = 0;
               s_inc = -2;
            }

            shift = s_start;

            for (i = 0; i < row_width; i++)
            {
               if (m & mask)
               {
                  value = (*sp >> shift) & 0x3;
                  *dp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
                  *dp |= (png_byte)(value << shift);
               }

               if (shift == s_end)
               {
                  shift = s_start;
                  sp++;
                  dp++;
               }
               else
                  shift += s_inc;
               if (m == 1)
                  m = 0x80;
               else
                  m >>= 1;
            }
            break;
         }
         case 4:
         {
            png_bytep sp = png_ptr->row_buf + 1;
            png_bytep dp = row;
            int s_start, s_end, s_inc;
            int m = 0x80;
            int shift;
            png_uint_32 i;
            png_uint_32 row_width = png_ptr->width;
            int value;

#if defined(PNG_READ_PACKSWAP_SUPPORTED)
            if (png_ptr->transformations & PNG_PACKSWAP)
            {
               s_start = 0;
               s_end = 4;
               s_inc = 4;
            }
            else
#endif
            {
               s_start = 4;
               s_end = 0;
               s_inc = -4;
            }
            shift = s_start;

            for (i = 0; i < row_width; i++)
            {
               if (m & mask)
               {
                  value = (*sp >> shift) & 0xf;
                  *dp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
                  *dp |= (png_byte)(value << shift);
               }

               if (shift == s_end)
               {
                  shift = s_start;
                  sp++;
                  dp++;
               }
               else
                  shift += s_inc;
               if (m == 1)
                  m = 0x80;
               else
                  m >>= 1;
            }
            break;
         }
         default:
         {
            png_bytep sp = png_ptr->row_buf + 1;
            png_bytep dp = row;
            png_size_t pixel_bytes = (png_ptr->row_info.pixel_depth >> 3);
            png_uint_32 i;
            png_uint_32 row_width = png_ptr->width;
            png_byte m = 0x80;


            for (i = 0; i < row_width; i++)
            {
               if (m & mask)
               {
                  png_memcpy(dp, sp, pixel_bytes);
               }

               sp += pixel_bytes;
               dp += pixel_bytes;

               if (m == 1)
                  m = 0x80;
               else
                  m >>= 1;
            }
            break;
         }
      }
   }
}

#if defined(PNG_READ_INTERLACING_SUPPORTED)
void
png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
   png_uint_32 transformations)
{
   png_debug(1,"in png_do_read_interlace\n");
   if (row != NULL && row_info != NULL)
   {
      png_uint_32 final_width;

      final_width = row_info->width * png_pass_inc[pass];

      switch (row_info->pixel_depth)
      {
         case 1:
         {
            png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);
            png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);
            int sshift, dshift;
            int s_start, s_end, s_inc;
            int jstop = png_pass_inc[pass];
            png_byte v;
            png_uint_32 i;
            int j;

#if defined(PNG_READ_PACKSWAP_SUPPORTED)
            if (transformations & PNG_PACKSWAP)
            {
                sshift = (int)((row_info->width + 7) & 7);
                dshift = (int)((final_width + 7) & 7);
                s_start = 7;
                s_end = 0;
                s_inc = -1;
            }
            else
#endif
            {
                sshift = 7 - (int)((row_info->width + 7) & 7);
                dshift = 7 - (int)((final_width + 7) & 7);
                s_start = 0;
                s_end = 7;
                s_inc = 1;
            }

            for (i = 0; i < row_info->width; i++)
            {
               v = (png_byte)((*sp >> sshift) & 0x1);
               for (j = 0; j < jstop; j++)
               {
                  *dp &= (png_byte)((0x7f7f >> (7 - dshift)) & 0xff);
                  *dp |= (png_byte)(v << dshift);
                  if (dshift == s_end)
                  {
                     dshift = s_start;
                     dp--;
                  }
                  else
                     dshift += s_inc;
               }
               if (sshift == s_end)
               {
                  sshift = s_start;
                  sp--;
               }
               else
                  sshift += s_inc;
            }
            break;
         }
         case 2:
         {
            png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
            png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
            int sshift, dshift;
            int s_start, s_end, s_inc;
            int jstop = png_pass_inc[pass];
            png_uint_32 i;

#if defined(PNG_READ_PACKSWAP_SUPPORTED)
            if (transformations & PNG_PACKSWAP)
            {
               sshift = (int)(((row_info->width + 3) & 3) << 1);
               dshift = (int)(((final_width + 3) & 3) << 1);
               s_start = 6;
               s_end = 0;
               s_inc = -2;
            }
            else
#endif
            {
               sshift = (int)((3 - ((row_info->width + 3) & 3)) << 1);
               dshift = (int)((3 - ((final_width + 3) & 3)) << 1);