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pngpread.c
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pngpread.c
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/* pngpread.c - read a png file in push mode
*
* Copyright (c) 2018-2024 Cosmin Truta
* Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
* Copyright (c) 1996-1997 Andreas Dilger
* 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_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
#define PNG_PUSH_SAVE_BUFFER_IF_FULL \
if (png_ptr->push_length + 4 > png_ptr->buffer_size) \
{ png_push_save_buffer(png_ptr); return; }
#define PNG_PUSH_SAVE_BUFFER_IF_LT(N) \
if (png_ptr->buffer_size < N) \
{ png_push_save_buffer(png_ptr); return; }
#ifdef PNG_READ_INTERLACING_SUPPORTED
/* Arrays to facilitate interlacing - use pass (0 - 6) as index. */
/* Start of interlace block */
static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
/* Offset to next interlace block */
static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
/* Start of interlace block in the y direction */
static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
/* Offset to next interlace block in the y direction */
static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
/* TODO: Move these arrays to a common utility module to avoid duplication. */
#endif
void PNGAPI
png_process_data(png_structrp png_ptr, png_inforp info_ptr,
png_bytep buffer, 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);
}
}
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 != 0)
png_push_save_buffer(png_ptr);
else
{
/* This includes any pending saved bytes: */
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)
{
/* TODO: Deprecate and remove this API.
* Somewhere the implementation of this seems to have been lost,
* or abandoned. It was only to support some internal back-door access
* to png_struct) in libpng-1.4.x.
*/
png_app_warning(png_ptr,
"png_process_data_skip is not implemented in any current version of libpng");
return 0;
}
/* 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;
}
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)
{
size_t num_checked = png_ptr->sig_bytes; /* SAFE, does not exceed 8 */
size_t 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) != 0)
{
if (num_checked < 4 &&
png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4) != 0)
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) == 0)
{
png_byte chunk_length[4];
png_byte chunk_tag[4];
PNG_PUSH_SAVE_BUFFER_IF_LT(8)
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_check_chunk_length(png_ptr, png_ptr->push_length);
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) != 0 ||
png_ptr->num_frames_read > 1)
png_error(png_ptr, "out of place IDAT");
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_crc_finish(png_ptr, png_ptr->push_length);
png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
}
else if (chunk_name == png_fdAT)
{
PNG_PUSH_SAVE_BUFFER_IF_LT(4)
png_ensure_sequence_number(png_ptr, 4);
if ((png_ptr->mode & PNG_HAVE_fcTL) == 0)
{
/* Discard trailing fdATs for frames other than the first */
if (png_ptr->num_frames_read < 2)
png_error(png_ptr, "out of place fdAT");
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_crc_finish(png_ptr, png_ptr->push_length);
png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
}
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;
}
}
else if (chunk_name == png_fcTL)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
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) == 0)
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;
}
else if (chunk_name == png_IEND)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_warning(png_ptr, "Number of actual frames fewer than expected");
png_crc_finish(png_ptr, png_ptr->push_length);
png_ptr->process_mode = PNG_READ_DONE_MODE;
png_push_have_end(png_ptr, info_ptr);
}
else
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_warning(png_ptr, "Skipped (ignored) a chunk "
"between APNG chunks");
png_crc_finish(png_ptr, png_ptr->push_length);
png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
}
return;
}
#endif /* READ_APNG */
if (chunk_name == png_IDAT)
{
if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
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) == 0)
png_error(png_ptr, "Missing IHDR before IDAT");
else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
(png_ptr->mode & PNG_HAVE_PLTE) == 0)
png_error(png_ptr, "Missing PLTE before IDAT");
png_ptr->process_mode = PNG_READ_IDAT_MODE;
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0)
if (png_ptr->push_length == 0)
return;
png_ptr->mode |= PNG_HAVE_IDAT;
if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
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");
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
}
else if (chunk_name == png_IEND)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
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)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
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)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
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)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
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)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
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)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_eXIf_SUPPORTED
else if (png_ptr->chunk_name == png_eXIf)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_eXIf(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_sRGB_SUPPORTED
else if (chunk_name == png_sRGB)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
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)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_sPLT_SUPPORTED
else if (chunk_name == png_sPLT)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_tRNS_SUPPORTED
else if (chunk_name == png_tRNS)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_bKGD_SUPPORTED
else if (chunk_name == png_bKGD)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_hIST_SUPPORTED
else if (chunk_name == png_hIST)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_pHYs_SUPPORTED
else if (chunk_name == png_pHYs)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_oFFs_SUPPORTED
else if (chunk_name == png_oFFs)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_pCAL_SUPPORTED
else if (chunk_name == png_pCAL)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_sCAL_SUPPORTED
else if (chunk_name == png_sCAL)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_tIME_SUPPORTED
else if (chunk_name == png_tIME)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_tEXt_SUPPORTED
else if (chunk_name == png_tEXt)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_zTXt_SUPPORTED
else if (chunk_name == png_zTXt)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_iTXt_SUPPORTED
else if (chunk_name == png_iTXt)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
}
#endif
#ifdef PNG_READ_APNG_SUPPORTED
else if (chunk_name == png_acTL)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_acTL(png_ptr, info_ptr, png_ptr->push_length);
}
else if (chunk_name == png_fcTL)
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_fcTL(png_ptr, info_ptr, png_ptr->push_length);
}
#endif /* READ_APNG */
else
{
PNG_PUSH_SAVE_BUFFER_IF_FULL
png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
PNG_HANDLE_CHUNK_AS_DEFAULT);
}
png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
}
void PNGCBAPI
png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, size_t length)
{
png_bytep ptr;
if (png_ptr == NULL)
return;
ptr = buffer;
if (png_ptr->save_buffer_size != 0)
{
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 != 0 && png_ptr->current_buffer_size != 0)
{
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 != 0)
{
if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
{
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)
{
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,
(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");
}
if (old_buffer)
memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
else if (png_ptr->save_buffer_size)
png_error(png_ptr, "save_buffer error");
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,
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) == 0)
{
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
PNG_PUSH_SAVE_BUFFER_IF_LT(12)
#else
PNG_PUSH_SAVE_BUFFER_IF_LT(8)
#endif
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) != 0)
{
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");
PNG_PUSH_SAVE_BUFFER_IF_FULL
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) == 0)
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 != 0 && png_ptr->save_buffer_size != 0)
{
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-bit or 64-bit platforms.
*/
if (idat_size < save_size)
save_size = (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 != 0 && png_ptr->current_buffer_size != 0)
{
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 = (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 == 0)
{
PNG_PUSH_SAVE_BUFFER_IF_LT(4)
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,
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) == 0 &&
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) == 0)
{
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 = PNG_INFLATE(png_ptr, 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
{
if (ret == Z_DATA_ERROR)
png_benign_error(png_ptr, "IDAT: ADLER32 checksum mismatch");
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 != 0)
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
/* Expand interlaced rows to full size */
if (png_ptr->interlaced != 0 &&
(png_ptr->transformations & PNG_INTERLACE) != 0)
{
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);
}
}