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[master] Moved reading of file signature into png_read_sig (Cosmin)

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This commit is contained in:
Glenn Randers-Pehrson
2010-11-20 15:50:51 -06:00
parent 820a8d1de9
commit 1f5a0b9fa6
4 changed files with 62 additions and 63 deletions
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62
pngrutil.c
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@@ -69,6 +69,39 @@ png_get_uint_16 (png_bytep buf)
}
#endif /* PNG_USE_READ_MACROS */
/* Read and check the PNG file signature */
void /* PRIVATE */
png_read_sig(png_structp png_ptr, png_infop info_ptr)
{
png_size_t num_checked, num_to_check;
/* Exit if the user application does not expect a signature. */
if (png_ptr->sig_bytes >= 8)
return;
num_checked = png_ptr->sig_bytes;
num_to_check = 8 - num_checked;
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
#endif
/* The signature must be serialized in a single I/O call. */
png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
png_ptr->sig_bytes = 8;
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");
}
if (num_checked < 3)
png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
}
/* Read the chunk header (length + type name).
* Put the type name into png_ptr->chunk_name, and return the length.
*/
@@ -79,32 +112,31 @@ png_read_chunk_header(png_structp png_ptr)
png_uint_32 length;
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the chunk header is being read.
* PNG_IO_CHUNK_HDR requires a single I/O call.
*/
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
#endif
/* Read the length and the chunk name */
/* Read the length and the chunk name.
* This must be performed in a single I/O call.
*/
png_read_data(png_ptr, buf, 8);
length = png_get_uint_31(png_ptr, buf);
/* Put the chunk name into png_ptr->chunk_name */
/* Put the chunk name into png_ptr->chunk_name. */
png_memcpy(png_ptr->chunk_name, buf + 4, 4);
png_debug2(0, "Reading %s chunk, length = %lu",
png_ptr->chunk_name, length);
/* Reset the crc and run it over the chunk name */
/* Reset the crc and run it over the chunk name. */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, png_ptr->chunk_name, 4);
/* Check to see if chunk name is valid */
/* Check to see if chunk name is valid. */
png_check_chunk_name(png_ptr, png_ptr->chunk_name);
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that chunk data will (possibly) be read.
* PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
/* It is unspecified how many I/O calls will be performed
* during the serialization of the chunk data.
*/
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
#endif
@@ -185,11 +217,10 @@ png_crc_error(png_structp png_ptr)
}
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the chunk CRC is being read */
/* PNG_IO_CHUNK_CRC requires the I/O to be done at once */
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
#endif
/* The chunk CRC must be serialized in a single I/O call. */
png_read_data(png_ptr, crc_bytes, 4);
if (need_crc)
@@ -3108,17 +3139,10 @@ png_read_finish_row(png_structp png_ptr)
{
while (!png_ptr->idat_size)
{
png_byte chunk_length[4];
png_crc_finish(png_ptr, 0);
png_read_data(png_ptr, chunk_length, 4);
png_ptr->idat_size = png_get_uint_31(png_ptr, chunk_length);
png_reset_crc(png_ptr);
png_crc_read(png_ptr, png_ptr->chunk_name, 4);
png_ptr->idat_size = png_read_chunk_header(png_ptr);
if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
png_error(png_ptr, "Not enough image data");
}
png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
png_ptr->zstream.next_in = png_ptr->zbuf;