The Tor Browser: media/libpng/pngpread.c@97036ab72558 (annotated)

media/libpng/pngpread.c@97036ab72558 (annotated)

media/libpng/pngpread.c

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* pngpread.c - read a png file in push mode
  *
  * Last changed in libpng 1.6.10 [March 6, 2014]
  * Copyright (c) 1998-2014 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  */
 #include "pngpriv.h"
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 /* Push model modes */
 #define PNG_READ_SIG_MODE   0
 #define PNG_READ_CHUNK_MODE 1
 #define PNG_READ_IDAT_MODE  2
 #define PNG_SKIP_MODE       3
 #define PNG_READ_tEXt_MODE  4
 #define PNG_READ_zTXt_MODE  5
 #define PNG_READ_DONE_MODE  6
 #define PNG_READ_iTXt_MODE  7
 #define PNG_ERROR_MODE      8
 void PNGAPI
 png_process_data(png_structrp png_ptr, png_inforp info_ptr,
     png_bytep buffer, png_size_t buffer_size)
 {
    if (png_ptr == NULL || info_ptr == NULL)
       return;
    png_push_restore_buffer(png_ptr, buffer, buffer_size);
    while (png_ptr->buffer_size)
    {
       png_process_some_data(png_ptr, info_ptr);
    }
 }
 png_size_t PNGAPI
 png_process_data_pause(png_structrp png_ptr, int save)
 {
    if (png_ptr != NULL)
    {
       /* It's easiest for the caller if we do the save, then the caller doesn't
        * have to supply the same data again:
        */
       if (save)
          png_push_save_buffer(png_ptr);
       else
       {
          /* This includes any pending saved bytes: */
          png_size_t remaining = png_ptr->buffer_size;
          png_ptr->buffer_size = 0;
          /* So subtract the saved buffer size, unless all the data
           * is actually 'saved', in which case we just return 0
           */
          if (png_ptr->save_buffer_size < remaining)
             return remaining - png_ptr->save_buffer_size;
       }
    }
    return 0;
 }
 png_uint_32 PNGAPI
 png_process_data_skip(png_structrp png_ptr)
 {
    png_uint_32 remaining = 0;
    if (png_ptr != NULL && png_ptr->process_mode == PNG_SKIP_MODE &&
       png_ptr->skip_length > 0)
    {
       /* At the end of png_process_data the buffer size must be 0 (see the loop
        * above) so we can detect a broken call here:
        */
       if (png_ptr->buffer_size != 0)
          png_error(png_ptr,
             "png_process_data_skip called inside png_process_data");
       /* If is impossible for there to be a saved buffer at this point -
        * otherwise we could not be in SKIP mode.  This will also happen if
        * png_process_skip is called inside png_process_data (but only very
        * rarely.)
        */
       if (png_ptr->save_buffer_size != 0)
          png_error(png_ptr, "png_process_data_skip called with saved data");
       remaining = png_ptr->skip_length;
       png_ptr->skip_length = 0;
       png_ptr->process_mode = PNG_READ_CHUNK_MODE;
    }
    return remaining;
 }
 /* What we do with the incoming data depends on what we were previously
  * doing before we ran out of data...
  */
 void /* PRIVATE */
 png_process_some_data(png_structrp png_ptr, png_inforp info_ptr)
 {
    if (png_ptr == NULL)
       return;
    switch (png_ptr->process_mode)
    {
       case PNG_READ_SIG_MODE:
       {
          png_push_read_sig(png_ptr, info_ptr);
          break;
       }
       case PNG_READ_CHUNK_MODE:
       {
          png_push_read_chunk(png_ptr, info_ptr);
          break;
       }
       case PNG_READ_IDAT_MODE:
       {
          png_push_read_IDAT(png_ptr);
          break;
       }
       case PNG_SKIP_MODE:
       {
          png_push_crc_finish(png_ptr);
          break;
       }
       default:
       {
          png_ptr->buffer_size = 0;
          break;
       }
    }
 }
 /* Read any remaining signature bytes from the stream and compare them with
  * the correct PNG signature.  It is possible that this routine is called
  * with bytes already read from the signature, either because they have been
  * checked by the calling application, or because of multiple calls to this
  * routine.
  */
 void /* PRIVATE */
 png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
 {
    png_size_t num_checked = png_ptr->sig_bytes, /* SAFE, does not exceed 8 */
              num_to_check = 8 - num_checked;
    if (png_ptr->buffer_size < num_to_check)
    {
       num_to_check = png_ptr->buffer_size;
    }
    png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
        num_to_check);
    png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);
    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
    {
       if (num_checked < 4 &&
           png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
          png_error(png_ptr, "Not a PNG file");
       else
          png_error(png_ptr, "PNG file corrupted by ASCII conversion");
    }
    else
    {
       if (png_ptr->sig_bytes >= 8)
       {
          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
       }
    }
 }
 void /* PRIVATE */
 png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
 {
    png_uint_32 chunk_name;
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
    int keep; /* unknown handling method */
 #endif
    /* First we make sure we have enough data for the 4 byte chunk name
     * and the 4 byte chunk length before proceeding with decoding the
     * chunk data.  To fully decode each of these chunks, we also make
     * sure we have enough data in the buffer for the 4 byte CRC at the
     * end of every chunk (except IDAT, which is handled separately).
     */
    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
    {
       png_byte chunk_length[4];
       png_byte chunk_tag[4];
       if (png_ptr->buffer_size < 8)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_push_fill_buffer(png_ptr, chunk_length, 4);
       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
       png_reset_crc(png_ptr);
       png_crc_read(png_ptr, chunk_tag, 4);
       png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
       png_check_chunk_name(png_ptr, png_ptr->chunk_name);
       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
    }
    chunk_name = png_ptr->chunk_name;
 #ifdef PNG_READ_APNG_SUPPORTED
    if (png_ptr->num_frames_read > 0 &&
        png_ptr->num_frames_read < info_ptr->num_frames)
    {
       if (chunk_name == png_IDAT)
       {
          /* Discard trailing IDATs for the first frame */
          if (png_ptr->mode & PNG_HAVE_fcTL || png_ptr->num_frames_read > 1)
             png_error(png_ptr, "out of place IDAT");
          if (png_ptr->push_length + 4 > png_ptr->buffer_size)
          {
             png_push_save_buffer(png_ptr);
             return;
          }
          png_push_crc_skip(png_ptr, png_ptr->push_length);
          png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
          return;
       }
       else if (chunk_name == png_fdAT)
       {
          if (png_ptr->buffer_size < 4)
          {
             png_push_save_buffer(png_ptr);
             return;
          }
          png_ensure_sequence_number(png_ptr, 4);
          if (!(png_ptr->mode & PNG_HAVE_fcTL))
          {
             /* Discard trailing fdATs for frames other than the first */
             if (png_ptr->num_frames_read < 2)
                png_error(png_ptr, "out of place fdAT");
             if (png_ptr->push_length + 4 > png_ptr->buffer_size)
             {
                png_push_save_buffer(png_ptr);
                return;
             }
             png_push_crc_skip(png_ptr, png_ptr->push_length);
             png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
             return;
          }
          else
          {
             /* frame data follows */
             png_ptr->idat_size = png_ptr->push_length - 4;
             png_ptr->mode |= PNG_HAVE_IDAT;
             png_ptr->process_mode = PNG_READ_IDAT_MODE;
             return;
          }
       }
       else if (chunk_name == png_fcTL)
       {
          if (png_ptr->push_length + 4 > png_ptr->buffer_size)
          {
             png_push_save_buffer(png_ptr);
             return;
          }
          png_read_reset(png_ptr);
          png_ptr->mode &= ~PNG_HAVE_fcTL;
          png_handle_fcTL(png_ptr, info_ptr, png_ptr->push_length);
          if (!(png_ptr->mode & PNG_HAVE_fcTL))
             png_error(png_ptr, "missing required fcTL chunk");
          png_read_reinit(png_ptr, info_ptr);
          png_progressive_read_reset(png_ptr);
          if (png_ptr->frame_info_fn != NULL)
             (*(png_ptr->frame_info_fn))(png_ptr, png_ptr->num_frames_read);
          png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
          return;
       }
       else
       {
          if (png_ptr->push_length + 4 > png_ptr->buffer_size)
          {
             png_push_save_buffer(png_ptr);
             return;
          }
          png_warning(png_ptr, "Skipped (ignored) a chunk "
                               "between APNG chunks");
          png_push_crc_skip(png_ptr, png_ptr->push_length);
          png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
          return;
       }
       return;
    }
 #endif /* PNG_READ_APNG_SUPPORTED */
    if (chunk_name == png_IDAT)
    {
       if (png_ptr->mode & PNG_AFTER_IDAT)
          png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
       /* If we reach an IDAT chunk, this means we have read all of the
        * header chunks, and we can start reading the image (or if this
        * is called after the image has been read - we have an error).
        */
       if (!(png_ptr->mode & PNG_HAVE_IHDR))
          png_error(png_ptr, "Missing IHDR before IDAT");
       else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
           !(png_ptr->mode & PNG_HAVE_PLTE))
          png_error(png_ptr, "Missing PLTE before IDAT");
       png_ptr->mode |= PNG_HAVE_IDAT;
       png_ptr->process_mode = PNG_READ_IDAT_MODE;
       if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
          if (png_ptr->push_length == 0)
             return;
       if (png_ptr->mode & PNG_AFTER_IDAT)
          png_benign_error(png_ptr, "Too many IDATs found");
    }
    if (chunk_name == png_IHDR)
    {
       if (png_ptr->push_length != 13)
          png_error(png_ptr, "Invalid IHDR length");
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
    }
    else if (chunk_name == png_IEND)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
       png_ptr->process_mode = PNG_READ_DONE_MODE;
       png_push_have_end(png_ptr, info_ptr);
    }
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
    else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep);
       if (chunk_name == png_PLTE)
          png_ptr->mode |= PNG_HAVE_PLTE;
    }
 #endif
    else if (chunk_name == png_PLTE)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
    }
    else if (chunk_name == png_IDAT)
    {
 #ifdef PNG_READ_APNG_SUPPORTED
       png_have_info(png_ptr, info_ptr);
 #endif
       png_ptr->idat_size = png_ptr->push_length;
       png_ptr->process_mode = PNG_READ_IDAT_MODE;
       png_push_have_info(png_ptr, info_ptr);
       png_ptr->zstream.avail_out =
           (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
           png_ptr->iwidth) + 1;
       png_ptr->zstream.next_out = png_ptr->row_buf;
       return;
    }
 #ifdef PNG_READ_gAMA_SUPPORTED
    else if (png_ptr->chunk_name == png_gAMA)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_sBIT_SUPPORTED
    else if (png_ptr->chunk_name == png_sBIT)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_cHRM_SUPPORTED
    else if (png_ptr->chunk_name == png_cHRM)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_sRGB_SUPPORTED
    else if (chunk_name == png_sRGB)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_iCCP_SUPPORTED
    else if (png_ptr->chunk_name == png_iCCP)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_sPLT_SUPPORTED
    else if (chunk_name == png_sPLT)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_tRNS_SUPPORTED
    else if (chunk_name == png_tRNS)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_bKGD_SUPPORTED
    else if (chunk_name == png_bKGD)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_hIST_SUPPORTED
    else if (chunk_name == png_hIST)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_pHYs_SUPPORTED
    else if (chunk_name == png_pHYs)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_oFFs_SUPPORTED
    else if (chunk_name == png_oFFs)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_pCAL_SUPPORTED
    else if (chunk_name == png_pCAL)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_sCAL_SUPPORTED
    else if (chunk_name == png_sCAL)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_tIME_SUPPORTED
    else if (chunk_name == png_tIME)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_tEXt_SUPPORTED
    else if (chunk_name == png_tEXt)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_zTXt_SUPPORTED
    else if (chunk_name == png_zTXt)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_iTXt_SUPPORTED
    else if (chunk_name == png_iTXt)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
 #ifdef PNG_READ_APNG_SUPPORTED
    else if (chunk_name == png_acTL)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_acTL(png_ptr, info_ptr, png_ptr->push_length);
    }
    else if (chunk_name == png_fcTL)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_fcTL(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif /* PNG_READ_APNG_SUPPORTED */
    else
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
          PNG_HANDLE_CHUNK_AS_DEFAULT);
    }
    png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 }
 void /* PRIVATE */
 png_push_crc_skip(png_structrp png_ptr, png_uint_32 skip)
 {
    png_ptr->process_mode = PNG_SKIP_MODE;
    png_ptr->skip_length = skip;
 }
 void /* PRIVATE */
 png_push_crc_finish(png_structrp png_ptr)
 {
    if (png_ptr->skip_length && png_ptr->save_buffer_size)
    {
       png_size_t save_size = png_ptr->save_buffer_size;
       png_uint_32 skip_length = png_ptr->skip_length;
       /* We want the smaller of 'skip_length' and 'save_buffer_size', but
        * they are of different types and we don't know which variable has the
        * fewest bits.  Carefully select the smaller and cast it to the type of
        * the larger - this cannot overflow.  Do not cast in the following test
        * - it will break on either 16 or 64 bit platforms.
        */
       if (skip_length < save_size)
          save_size = (png_size_t)skip_length;
       else
          skip_length = (png_uint_32)save_size;
       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
       png_ptr->skip_length -= skip_length;
       png_ptr->buffer_size -= save_size;
       png_ptr->save_buffer_size -= save_size;
       png_ptr->save_buffer_ptr += save_size;
    }
    if (png_ptr->skip_length && png_ptr->current_buffer_size)
    {
       png_size_t save_size = png_ptr->current_buffer_size;
       png_uint_32 skip_length = png_ptr->skip_length;
       /* We want the smaller of 'skip_length' and 'current_buffer_size', here,
        * the same problem exists as above and the same solution.
        */
       if (skip_length < save_size)
          save_size = (png_size_t)skip_length;
       else
          skip_length = (png_uint_32)save_size;
       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
       png_ptr->skip_length -= skip_length;
       png_ptr->buffer_size -= save_size;
       png_ptr->current_buffer_size -= save_size;
       png_ptr->current_buffer_ptr += save_size;
    }
    if (!png_ptr->skip_length)
    {
       if (png_ptr->buffer_size < 4)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_crc_finish(png_ptr, 0);
       png_ptr->process_mode = PNG_READ_CHUNK_MODE;
    }
 }
 void PNGCBAPI
 png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
 {
    png_bytep ptr;
    if (png_ptr == NULL)
       return;
    ptr = buffer;
    if (png_ptr->save_buffer_size)
    {
       png_size_t save_size;
       if (length < png_ptr->save_buffer_size)
          save_size = length;
       else
          save_size = png_ptr->save_buffer_size;
       memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
       length -= save_size;
       ptr += save_size;
       png_ptr->buffer_size -= save_size;
       png_ptr->save_buffer_size -= save_size;
       png_ptr->save_buffer_ptr += save_size;
    }
    if (length && png_ptr->current_buffer_size)
    {
       png_size_t save_size;
       if (length < png_ptr->current_buffer_size)
          save_size = length;
       else
          save_size = png_ptr->current_buffer_size;
       memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
       png_ptr->buffer_size -= save_size;
       png_ptr->current_buffer_size -= save_size;
       png_ptr->current_buffer_ptr += save_size;
    }
 }
 void /* PRIVATE */
 png_push_save_buffer(png_structrp png_ptr)
 {
    if (png_ptr->save_buffer_size)
    {
       if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
       {
          png_size_t i, istop;
          png_bytep sp;
          png_bytep dp;
          istop = png_ptr->save_buffer_size;
          for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
              i < istop; i++, sp++, dp++)
          {
             *dp = *sp;
          }
       }
    }
    if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
        png_ptr->save_buffer_max)
    {
       png_size_t new_max;
       png_bytep old_buffer;
       if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
           (png_ptr->current_buffer_size + 256))
       {
          png_error(png_ptr, "Potential overflow of save_buffer");
       }
       new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
       old_buffer = png_ptr->save_buffer;
       png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
           (png_size_t)new_max);
       if (png_ptr->save_buffer == NULL)
       {
          png_free(png_ptr, old_buffer);
          png_error(png_ptr, "Insufficient memory for save_buffer");
       }
       memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
       png_free(png_ptr, old_buffer);
       png_ptr->save_buffer_max = new_max;
    }
    if (png_ptr->current_buffer_size)
    {
       memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
          png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
       png_ptr->save_buffer_size += png_ptr->current_buffer_size;
       png_ptr->current_buffer_size = 0;
    }
    png_ptr->save_buffer_ptr = png_ptr->save_buffer;
    png_ptr->buffer_size = 0;
 }
 void /* PRIVATE */
 png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
    png_size_t buffer_length)
 {
    png_ptr->current_buffer = buffer;
    png_ptr->current_buffer_size = buffer_length;
    png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
    png_ptr->current_buffer_ptr = png_ptr->current_buffer;
 }
 void /* PRIVATE */
 png_push_read_IDAT(png_structrp png_ptr)
 {
    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
    {
       png_byte chunk_length[4];
       png_byte chunk_tag[4];
       /* TODO: this code can be commoned up with the same code in push_read */
 #ifdef PNG_READ_APNG_SUPPORTED
       if (png_ptr->buffer_size < 12)
 #else
       if (png_ptr->buffer_size < 8)
 #endif
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_push_fill_buffer(png_ptr, chunk_length, 4);
       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
       png_reset_crc(png_ptr);
       png_crc_read(png_ptr, chunk_tag, 4);
       png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 #ifdef PNG_READ_APNG_SUPPORTED
       if (png_ptr->chunk_name != png_fdAT && png_ptr->num_frames_read > 0)
       {
           if (png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED)
           {
               png_ptr->process_mode = PNG_READ_CHUNK_MODE;
               if (png_ptr->frame_end_fn != NULL)
                  (*(png_ptr->frame_end_fn))(png_ptr, png_ptr->num_frames_read);
               png_ptr->num_frames_read++;
               return;
           }
           else
           {
               if (png_ptr->chunk_name == png_IEND)
                   png_error(png_ptr, "Not enough image data");
               if (png_ptr->push_length + 4 > png_ptr->buffer_size)
               {
                  png_push_save_buffer(png_ptr);
                  return;
               }
               png_warning(png_ptr, "Skipping (ignoring) a chunk between "
                                    "APNG chunks");
               png_crc_finish(png_ptr, png_ptr->push_length);
               png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
               return;
           }
       }
       else
 #endif
 #ifdef PNG_READ_APNG_SUPPORTED
       if (png_ptr->chunk_name != png_IDAT && png_ptr->num_frames_read == 0)
 #else
       if (png_ptr->chunk_name != png_IDAT)
 #endif
       {
          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
          if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
             png_error(png_ptr, "Not enough compressed data");
 #ifdef PNG_READ_APNG_SUPPORTED
          if (png_ptr->frame_end_fn != NULL)
             (*(png_ptr->frame_end_fn))(png_ptr, png_ptr->num_frames_read);
          png_ptr->num_frames_read++;
 #endif
          return;
       }
       png_ptr->idat_size = png_ptr->push_length;
 #ifdef PNG_READ_APNG_SUPPORTED
       if (png_ptr->num_frames_read > 0)
       {
          png_ensure_sequence_number(png_ptr, 4);
          png_ptr->idat_size -= 4;
       }
 #endif
    }
    if (png_ptr->idat_size && png_ptr->save_buffer_size)
    {
       png_size_t save_size = png_ptr->save_buffer_size;
       png_uint_32 idat_size = png_ptr->idat_size;
       /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
        * are of different types and we don't know which variable has the fewest
        * bits.  Carefully select the smaller and cast it to the type of the
        * larger - this cannot overflow.  Do not cast in the following test - it
        * will break on either 16 or 64 bit platforms.
        */
       if (idat_size < save_size)
          save_size = (png_size_t)idat_size;
       else
          idat_size = (png_uint_32)save_size;
       png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);
       png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);
       png_ptr->idat_size -= idat_size;
       png_ptr->buffer_size -= save_size;
       png_ptr->save_buffer_size -= save_size;
       png_ptr->save_buffer_ptr += save_size;
    }
    if (png_ptr->idat_size && png_ptr->current_buffer_size)
    {
       png_size_t save_size = png_ptr->current_buffer_size;
       png_uint_32 idat_size = png_ptr->idat_size;
       /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
        * are of different types and we don't know which variable has the fewest
        * bits.  Carefully select the smaller and cast it to the type of the
        * larger - this cannot overflow.
        */
       if (idat_size < save_size)
          save_size = (png_size_t)idat_size;
       else
          idat_size = (png_uint_32)save_size;
       png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
       png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);
       png_ptr->idat_size -= idat_size;
       png_ptr->buffer_size -= save_size;
       png_ptr->current_buffer_size -= save_size;
       png_ptr->current_buffer_ptr += save_size;
    }
    if (!png_ptr->idat_size)
    {
       if (png_ptr->buffer_size < 4)
       {
          png_push_save_buffer(png_ptr);
          return;
       }
       png_crc_finish(png_ptr, 0);
       png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
       png_ptr->mode |= PNG_AFTER_IDAT;
       png_ptr->zowner = 0;
    }
 }
 void /* PRIVATE */
 png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
    png_size_t buffer_length)
 {
    /* The caller checks for a non-zero buffer length. */
    if (!(buffer_length > 0) || buffer == NULL)
       png_error(png_ptr, "No IDAT data (internal error)");
 #ifdef PNG_READ_APNG_SUPPORTED
    /* If the app is not APNG-aware, decode only the first frame */
    if (!(png_ptr->apng_flags & PNG_APNG_APP) && png_ptr->num_frames_read > 0)
    {
      png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
      return;
    }
 #endif
    /* This routine must process all the data it has been given
     * before returning, calling the row callback as required to
     * handle the uncompressed results.
     */
    png_ptr->zstream.next_in = buffer;
    /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
    png_ptr->zstream.avail_in = (uInt)buffer_length;
    /* Keep going until the decompressed data is all processed
     * or the stream marked as finished.
     */
    while (png_ptr->zstream.avail_in > 0 &&
       !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
    {
       int ret;
       /* We have data for zlib, but we must check that zlib
        * has someplace to put the results.  It doesn't matter
        * if we don't expect any results -- it may be the input
        * data is just the LZ end code.
        */
       if (!(png_ptr->zstream.avail_out > 0))
       {
          /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
          png_ptr->zstream.avail_out = (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
              png_ptr->iwidth) + 1);
          png_ptr->zstream.next_out = png_ptr->row_buf;
       }
       /* Using Z_SYNC_FLUSH here means that an unterminated
        * LZ stream (a stream with a missing end code) can still
        * be handled, otherwise (Z_NO_FLUSH) a future zlib
        * implementation might defer output and therefore
        * change the current behavior (see comments in inflate.c
        * for why this doesn't happen at present with zlib 1.2.5).
        */
       ret = inflate(&png_ptr->zstream, Z_SYNC_FLUSH);
       /* Check for any failure before proceeding. */
       if (ret != Z_OK && ret != Z_STREAM_END)
       {
          /* Terminate the decompression. */
          png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
          png_ptr->zowner = 0;
          /* This may be a truncated stream (missing or
           * damaged end code).  Treat that as a warning.
           */
          if (png_ptr->row_number >= png_ptr->num_rows ||
              png_ptr->pass > 6)
             png_warning(png_ptr, "Truncated compressed data in IDAT");
          else
             png_error(png_ptr, "Decompression error in IDAT");
          /* Skip the check on unprocessed input */
          return;
       }
       /* Did inflate output any data? */
       if (png_ptr->zstream.next_out != png_ptr->row_buf)
       {
          /* Is this unexpected data after the last row?
           * If it is, artificially terminate the LZ output
           * here.
           */
          if (png_ptr->row_number >= png_ptr->num_rows ||
              png_ptr->pass > 6)
          {
             /* Extra data. */
             png_warning(png_ptr, "Extra compressed data in IDAT");
             png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
             png_ptr->zowner = 0;
             /* Do no more processing; skip the unprocessed
              * input check below.
              */
             return;
          }
          /* Do we have a complete row? */
          if (png_ptr->zstream.avail_out == 0)
             png_push_process_row(png_ptr);
       }
       /* And check for the end of the stream. */
       if (ret == Z_STREAM_END)
          png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
    }
    /* All the data should have been processed, if anything
     * is left at this point we have bytes of IDAT data
     * after the zlib end code.
     */
    if (png_ptr->zstream.avail_in > 0)
       png_warning(png_ptr, "Extra compression data in IDAT");
 }
 void /* PRIVATE */
 png_push_process_row(png_structrp png_ptr)
 {
    /* 1.5.6: row_info moved out of png_struct to a local here. */
    png_row_info row_info;
    row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
    row_info.color_type = png_ptr->color_type;
    row_info.bit_depth = png_ptr->bit_depth;
    row_info.channels = png_ptr->channels;
    row_info.pixel_depth = png_ptr->pixel_depth;
    row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
    if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
    {
       if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
          png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
             png_ptr->prev_row + 1, png_ptr->row_buf[0]);
       else
          png_error(png_ptr, "bad adaptive filter value");
    }
    /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
     * 1.5.6, while the buffer really is this big in current versions of libpng
     * it may not be in the future, so this was changed just to copy the
     * interlaced row count:
     */
    memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
    if (png_ptr->transformations)
       png_do_read_transformations(png_ptr, &row_info);
 #endif
    /* The transformed pixel depth should match the depth now in row_info. */
    if (png_ptr->transformed_pixel_depth == 0)
    {
       png_ptr->transformed_pixel_depth = row_info.pixel_depth;
       if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
          png_error(png_ptr, "progressive row overflow");
    }
    else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
       png_error(png_ptr, "internal progressive row size calculation error");
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Blow up interlaced rows to full size */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
       if (png_ptr->pass < 6)
          png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
             png_ptr->transformations);
     switch (png_ptr->pass)
     {
          case 0:
          {
             int i;
             for (i = 0; i < 8 && png_ptr->pass == 0; i++)
             {
                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */
             }
             if (png_ptr->pass == 2) /* Pass 1 might be empty */
             {
                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
                {
                   png_push_have_row(png_ptr, NULL);
                   png_read_push_finish_row(png_ptr);
                }
             }
             if (png_ptr->pass == 4 && png_ptr->height <= 4)
             {
                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
                {
                   png_push_have_row(png_ptr, NULL);
                   png_read_push_finish_row(png_ptr);
                }
             }
             if (png_ptr->pass == 6 && png_ptr->height <= 4)
             {
                 png_push_have_row(png_ptr, NULL);
                 png_read_push_finish_row(png_ptr);
             }
             break;
          }
          case 1:
          {
             int i;
             for (i = 0; i < 8 && png_ptr->pass == 1; i++)
             {
                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                png_read_push_finish_row(png_ptr);
             }
             if (png_ptr->pass == 2) /* Skip top 4 generated rows */
             {
                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
                {
                   png_push_have_row(png_ptr, NULL);
                   png_read_push_finish_row(png_ptr);
                }
             }
             break;
          }
          case 2:
          {
             int i;
             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
             {
                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                png_read_push_finish_row(png_ptr);
             }
             for (i = 0; i < 4 && png_ptr->pass == 2; i++)
             {
                png_push_have_row(png_ptr, NULL);
                png_read_push_finish_row(png_ptr);
             }
             if (png_ptr->pass == 4) /* Pass 3 might be empty */
             {
                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
                {
                   png_push_have_row(png_ptr, NULL);
                   png_read_push_finish_row(png_ptr);
                }
             }
             break;
          }
          case 3:
          {
             int i;
             for (i = 0; i < 4 && png_ptr->pass == 3; i++)
             {
                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                png_read_push_finish_row(png_ptr);
             }
             if (png_ptr->pass == 4) /* Skip top two generated rows */
             {
                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
                {
                   png_push_have_row(png_ptr, NULL);
                   png_read_push_finish_row(png_ptr);
                }
             }
             break;
          }
          case 4:
          {
             int i;
             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
             {
                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                png_read_push_finish_row(png_ptr);
             }
             for (i = 0; i < 2 && png_ptr->pass == 4; i++)
             {
                png_push_have_row(png_ptr, NULL);
                png_read_push_finish_row(png_ptr);
             }
             if (png_ptr->pass == 6) /* Pass 5 might be empty */
             {
                png_push_have_row(png_ptr, NULL);
                png_read_push_finish_row(png_ptr);
             }
             break;
          }
          case 5:
          {
             int i;
             for (i = 0; i < 2 && png_ptr->pass == 5; i++)
             {
                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                png_read_push_finish_row(png_ptr);
             }
             if (png_ptr->pass == 6) /* Skip top generated row */
             {
                png_push_have_row(png_ptr, NULL);
                png_read_push_finish_row(png_ptr);
             }
             break;
          }
          default:
          case 6:
          {
             png_push_have_row(png_ptr, png_ptr->row_buf + 1);
             png_read_push_finish_row(png_ptr);
             if (png_ptr->pass != 6)
                break;
             png_push_have_row(png_ptr, NULL);
             png_read_push_finish_row(png_ptr);
          }
       }
    }
    else
 #endif
    {
       png_push_have_row(png_ptr, png_ptr->row_buf + 1);
       png_read_push_finish_row(png_ptr);
    }
 }
 void /* PRIVATE */
 png_read_push_finish_row(png_structrp png_ptr)
 {
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
    /* Start of interlace block */
    static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
    /* Offset to next interlace block */
    static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
    /* Start of interlace block in the y direction */
    static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
    /* Offset to next interlace block in the y direction */
    static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
    /* Height of interlace block.  This is not currently used - if you need
     * it, uncomment it here and in png.h
    static PNG_CONST png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
    */
 #endif
    png_ptr->row_number++;
    if (png_ptr->row_number < png_ptr->num_rows)
       return;
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    if (png_ptr->interlaced)
    {
       png_ptr->row_number = 0;
       memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
       do
       {
          png_ptr->pass++;
          if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
              (png_ptr->pass == 3 && png_ptr->width < 3) ||
              (png_ptr->pass == 5 && png_ptr->width < 2))
             png_ptr->pass++;
          if (png_ptr->pass > 7)
             png_ptr->pass--;
          if (png_ptr->pass >= 7)
             break;
          png_ptr->iwidth = (png_ptr->width +
              png_pass_inc[png_ptr->pass] - 1 -
              png_pass_start[png_ptr->pass]) /
              png_pass_inc[png_ptr->pass];
          if (png_ptr->transformations & PNG_INTERLACE)
             break;
          png_ptr->num_rows = (png_ptr->height +
              png_pass_yinc[png_ptr->pass] - 1 -
              png_pass_ystart[png_ptr->pass]) /
              png_pass_yinc[png_ptr->pass];
       } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
    }
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
 }
 void /* PRIVATE */
 png_push_have_info(png_structrp png_ptr, png_inforp info_ptr)
 {
    if (png_ptr->info_fn != NULL)
       (*(png_ptr->info_fn))(png_ptr, info_ptr);
 }
 void /* PRIVATE */
 png_push_have_end(png_structrp png_ptr, png_inforp info_ptr)
 {
    if (png_ptr->end_fn != NULL)
       (*(png_ptr->end_fn))(png_ptr, info_ptr);
 }
 void /* PRIVATE */
 png_push_have_row(png_structrp png_ptr, png_bytep row)
 {
    if (png_ptr->row_fn != NULL)
       (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
          (int)png_ptr->pass);
 }
 #ifdef PNG_READ_INTERLACING_SUPPORTED
 void PNGAPI
 png_progressive_combine_row(png_const_structrp png_ptr, png_bytep old_row,
     png_const_bytep new_row)
 {
    if (png_ptr == NULL)
       return;
    /* new_row is a flag here - if it is NULL then the app callback was called
     * from an empty row (see the calls to png_struct::row_fn below), otherwise
     * it must be png_ptr->row_buf+1
     */
    if (new_row != NULL)
       png_combine_row(png_ptr, old_row, 1/*display*/);
 }
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
 void PNGAPI
 png_set_progressive_read_fn(png_structrp png_ptr, png_voidp progressive_ptr,
     png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
     png_progressive_end_ptr end_fn)
 {
    if (png_ptr == NULL)
       return;
    png_ptr->info_fn = info_fn;
    png_ptr->row_fn = row_fn;
    png_ptr->end_fn = end_fn;
    png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
 }
 #ifdef PNG_READ_APNG_SUPPORTED
 void PNGAPI
 png_set_progressive_frame_fn(png_structp png_ptr,
    png_progressive_frame_ptr frame_info_fn,
    png_progressive_frame_ptr frame_end_fn)
 {
    png_ptr->frame_info_fn = frame_info_fn;
    png_ptr->frame_end_fn = frame_end_fn;
    png_ptr->apng_flags |= PNG_APNG_APP;
 }
 #endif
 png_voidp PNGAPI
 png_get_progressive_ptr(png_const_structrp png_ptr)
 {
    if (png_ptr == NULL)
       return (NULL);
    return png_ptr->io_ptr;
 }
 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */

The Tor Browser / annotate

media/libpng/pngpread.c@97036ab72558 (annotated)

media/libpng/pngpread.c