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skia / third_party / libpng / 8c542ad9dfc3e7f8a8c790343a43d9cffbc54fd8 / . / pngrutil.c
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/* pngrutil.c - utilities to read a PNG file
*
* Copyright (c) 2018 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
*
* This file contains routines that are only called from within
* libpng itself during the course of reading an image.
*/
#include "pngpriv.h"
#ifdef PNG_READ_SUPPORTED
png_uint_32 PNGAPI
png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf);
if (uval > PNG_UINT_31_MAX)
png_error(png_ptr, "PNG unsigned integer out of range");
return (uval);
}
#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
/* The following is a variation on the above for use with the fixed
* point values used for gAMA and cHRM. Instead of png_error it
* issues a warning and returns (-1) - an invalid value because both
* gAMA and cHRM use *unsigned* integers for fixed point values.
*/
#define PNG_FIXED_ERROR (-1)
static png_fixed_point /* PRIVATE */
png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf);
if (uval <= PNG_UINT_31_MAX)
return (png_fixed_point)uval; /* known to be in range */
/* The caller can turn off the warning by passing NULL. */
if (png_ptr != NULL)
png_warning(png_ptr, "PNG fixed point integer out of range");
return PNG_FIXED_ERROR;
}
#endif
#ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
/* NOTE: the read macros will obscure these definitions, so that if
* PNG_USE_READ_MACROS is set the library will not use them internally,
* but the APIs will still be available externally.
*
* The parentheses around "PNGAPI function_name" in the following three
* functions are necessary because they allow the macros to co-exist with
* these (unused but exported) functions.
*/
/* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
png_uint_32 (PNGAPI
png_get_uint_32)(png_const_bytep buf)
{
png_uint_32 uval =
((png_uint_32)(*(buf )) << 24) +
((png_uint_32)(*(buf + 1)) << 16) +
((png_uint_32)(*(buf + 2)) << 8) +
((png_uint_32)(*(buf + 3)) ) ;
return uval;
}
/* Grab a signed 32-bit integer from a buffer in big-endian format. The
* data is stored in the PNG file in two's complement format and there
* is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
* the following code does a two's complement to native conversion.
*/
png_int_32 (PNGAPI
png_get_int_32)(png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf);
if ((uval & 0x80000000) == 0) /* non-negative */
return (png_int_32)uval;
uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */
if ((uval & 0x80000000) == 0) /* no overflow */
return -(png_int_32)uval;
/* The following has to be safe; this function only gets called on PNG data
* and if we get here that data is invalid. 0 is the most safe value and
* if not then an attacker would surely just generate a PNG with 0 instead.
*/
return 0;
}
/* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
png_uint_16 (PNGAPI
png_get_uint_16)(png_const_bytep buf)
{
/* ANSI-C requires an int value to accommodate at least 16 bits so this
* works and allows the compiler not to worry about possible narrowing
* on 32-bit systems. (Pre-ANSI systems did not make integers smaller
* than 16 bits either.)
*/
unsigned int val =
((unsigned int)(*buf) << 8) +
((unsigned int)(*(buf + 1)));
return (png_uint_16)val;
}
#endif /* READ_INT_FUNCTIONS */
/* Read and check the PNG file signature */
void /* PRIVATE */
png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
{
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) != 0)
{
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.
*/
png_uint_32 /* PRIVATE */
png_read_chunk_header(png_structrp png_ptr)
{
png_byte buf[8];
png_uint_32 length;
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
#endif
/* 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. */
png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
png_debug2(0, "Reading %lx chunk, length = %lu",
(unsigned long)png_ptr->chunk_name, (unsigned long)length);
/* Reset the crc and run it over the chunk name. */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, buf + 4, 4);
/* Check to see if chunk name is valid. */
png_check_chunk_name(png_ptr, png_ptr->chunk_name);
/* Check for too-large chunk length */
png_check_chunk_length(png_ptr, length);
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
#endif
return length;
}
/* Read data, and (optionally) run it through the CRC. */
void /* PRIVATE */
png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
{
if (png_ptr == NULL)
return;
png_read_data(png_ptr, buf, length);
png_calculate_crc(png_ptr, buf, length);
}
/* Optionally skip data and then check the CRC. Depending on whether we
* are reading an ancillary or critical chunk, and how the program has set
* things up, we may calculate the CRC on the data and print a message.
* Returns '1' if there was a CRC error, '0' otherwise.
*/
int /* PRIVATE */
png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
{
/* The size of the local buffer for inflate is a good guess as to a
* reasonable size to use for buffering reads from the application.
*/
while (skip > 0)
{
png_uint_32 len;
png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
len = (sizeof tmpbuf);
if (len > skip)
len = skip;
skip -= len;
png_crc_read(png_ptr, tmpbuf, len);
}
if (png_crc_error(png_ptr) != 0)
{
if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0 ?
(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0 :
(png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE) != 0)
{
png_chunk_warning(png_ptr, "CRC error");
}
else
png_chunk_error(png_ptr, "CRC error");
return (1);
}
return (0);
}
/* Compare the CRC stored in the PNG file with that calculated by libpng from
* the data it has read thus far.
*/
int /* PRIVATE */
png_crc_error(png_structrp png_ptr)
{
png_byte crc_bytes[4];
png_uint_32 crc;
int need_crc = 1;
if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
{
if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
(PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
need_crc = 0;
}
else /* critical */
{
if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
need_crc = 0;
}
#ifdef PNG_IO_STATE_SUPPORTED
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 != 0)
{
crc = png_get_uint_32(crc_bytes);
return ((int)(crc != png_ptr->crc));
}
else
return (0);
}
#if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\
defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\
defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\
defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED)
/* Manage the read buffer; this simply reallocates the buffer if it is not small
* enough (or if it is not allocated). The routine returns a pointer to the
* buffer; if an error occurs and 'warn' is set the routine returns NULL, else
* it will call png_error (via png_malloc) on failure. (warn == 2 means
* 'silent').
*/
static png_bytep
png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
{
png_bytep buffer = png_ptr->read_buffer;
if (buffer != NULL && new_size > png_ptr->read_buffer_size)
{
png_ptr->read_buffer = NULL;
png_ptr->read_buffer_size = 0;
png_free(png_ptr, buffer);
buffer = NULL;
}
if (buffer == NULL)
{
buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
if (buffer != NULL)
{
memset(buffer, 0, new_size); /* just in case */
png_ptr->read_buffer = buffer;
png_ptr->read_buffer_size = new_size;
}
else if (warn < 2) /* else silent */
{
if (warn != 0)
png_chunk_warning(png_ptr, "insufficient memory to read chunk");
else
png_chunk_error(png_ptr, "insufficient memory to read chunk");
}
}
return buffer;
}
#endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */
/* png_inflate_claim: claim the zstream for some nefarious purpose that involves
* decompression. Returns Z_OK on success, else a zlib error code. It checks
* the owner but, in final release builds, just issues a warning if some other
* chunk apparently owns the stream. Prior to release it does a png_error.
*/
static int
png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
{
if (png_ptr->zowner != 0)
{
char msg[64];
PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
/* So the message that results is "<chunk> using zstream"; this is an
* internal error, but is very useful for debugging. i18n requirements
* are minimal.
*/
(void)png_safecat(msg, (sizeof msg), 4, " using zstream");
#if PNG_RELEASE_BUILD
png_chunk_warning(png_ptr, msg);
png_ptr->zowner = 0;
#else
png_chunk_error(png_ptr, msg);
#endif
}
/* Implementation note: unlike 'png_deflate_claim' this internal function
* does not take the size of the data as an argument. Some efficiency could
* be gained by using this when it is known *if* the zlib stream itself does
* not record the number; however, this is an illusion: the original writer
* of the PNG may have selected a lower window size, and we really must
* follow that because, for systems with with limited capabilities, we
* would otherwise reject the application's attempts to use a smaller window
* size (zlib doesn't have an interface to say "this or lower"!).
*
* inflateReset2 was added to zlib 1.2.4; before this the window could not be
* reset, therefore it is necessary to always allocate the maximum window
* size with earlier zlibs just in case later compressed chunks need it.
*/
{
int ret; /* zlib return code */
#if ZLIB_VERNUM >= 0x1240
int window_bits = 0;
# if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_MAXIMUM_INFLATE_WINDOW)
if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
PNG_OPTION_ON)
{
window_bits = 15;
png_ptr->zstream_start = 0; /* fixed window size */
}
else
{
png_ptr->zstream_start = 1;
}
# endif
#endif /* ZLIB_VERNUM >= 0x1240 */
/* Set this for safety, just in case the previous owner left pointers to
* memory allocations.
*/
png_ptr->zstream.next_in = NULL;
png_ptr->zstream.avail_in = 0;
png_ptr->zstream.next_out = NULL;
png_ptr->zstream.avail_out = 0;
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
{
#if ZLIB_VERNUM >= 0x1240
ret = inflateReset2(&png_ptr->zstream, window_bits);
#else
ret = inflateReset(&png_ptr->zstream);
#endif
}
else
{
#if ZLIB_VERNUM >= 0x1240
ret = inflateInit2(&png_ptr->zstream, window_bits);
#else
ret = inflateInit(&png_ptr->zstream);
#endif
if (ret == Z_OK)
png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
}
#if ZLIB_VERNUM >= 0x1290 && \
defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_IGNORE_ADLER32)
if (((png_ptr->options >> PNG_IGNORE_ADLER32) & 3) == PNG_OPTION_ON)
/* Turn off validation of the ADLER32 checksum in IDAT chunks */
ret = inflateValidate(&png_ptr->zstream, 0);
#endif
if (ret == Z_OK)
png_ptr->zowner = owner;
else
png_zstream_error(png_ptr, ret);
return ret;
}
#ifdef window_bits
# undef window_bits
#endif
}
#if ZLIB_VERNUM >= 0x1240
/* Handle the start of the inflate stream if we called inflateInit2(strm,0);
* in this case some zlib versions skip validation of the CINFO field and, in
* certain circumstances, libpng may end up displaying an invalid image, in
* contrast to implementations that call zlib in the normal way (e.g. libpng
* 1.5).
*/
int /* PRIVATE */
png_zlib_inflate(png_structrp png_ptr, int flush)
{
if (png_ptr->zstream_start && png_ptr->zstream.avail_in > 0)
{
if ((*png_ptr->zstream.next_in >> 4) > 7)
{
png_ptr->zstream.msg = "invalid window size (libpng)";
return Z_DATA_ERROR;
}
png_ptr->zstream_start = 0;
}
return inflate(&png_ptr->zstream, flush);
}
#endif /* Zlib >= 1.2.4 */
#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
#if defined(PNG_READ_zTXt_SUPPORTED) || defined (PNG_READ_iTXt_SUPPORTED)
/* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
* allow the caller to do multiple calls if required. If the 'finish' flag is
* set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
* be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
* Z_OK or Z_STREAM_END will be returned on success.
*
* The input and output sizes are updated to the actual amounts of data consumed
* or written, not the amount available (as in a z_stream). The data pointers
* are not changed, so the next input is (data+input_size) and the next
* available output is (output+output_size).
*/
static int
png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
/* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
/* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
{
if (png_ptr->zowner == owner) /* Else not claimed */
{
int ret;
png_alloc_size_t avail_out = *output_size_ptr;
png_uint_32 avail_in = *input_size_ptr;
/* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
* can't even necessarily handle 65536 bytes) because the type uInt is
* "16 bits or more". Consequently it is necessary to chunk the input to
* zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
* maximum value that can be stored in a uInt.) It is possible to set
* ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
* a performance advantage, because it reduces the amount of data accessed
* at each step and that may give the OS more time to page it in.
*/
png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
/* avail_in and avail_out are set below from 'size' */
png_ptr->zstream.avail_in = 0;
png_ptr->zstream.avail_out = 0;
/* Read directly into the output if it is available (this is set to
* a local buffer below if output is NULL).
*/
if (output != NULL)
png_ptr->zstream.next_out = output;
do
{
uInt avail;
Byte local_buffer[PNG_INFLATE_BUF_SIZE];
/* zlib INPUT BUFFER */
/* The setting of 'avail_in' used to be outside the loop; by setting it
* inside it is possible to chunk the input to zlib and simply rely on
* zlib to advance the 'next_in' pointer. This allows arbitrary
* amounts of data to be passed through zlib at the unavoidable cost of
* requiring a window save (memcpy of up to 32768 output bytes)
* every ZLIB_IO_MAX input bytes.
*/
avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
avail = ZLIB_IO_MAX;
if (avail_in < avail)
avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
avail_in -= avail;
png_ptr->zstream.avail_in = avail;
/* zlib OUTPUT BUFFER */
avail_out += png_ptr->zstream.avail_out; /* not written last time */
avail = ZLIB_IO_MAX; /* maximum zlib can process */
if (output == NULL)
{
/* Reset the output buffer each time round if output is NULL and
* make available the full buffer, up to 'remaining_space'
*/
png_ptr->zstream.next_out = local_buffer;
if ((sizeof local_buffer) < avail)
avail = (sizeof local_buffer);
}
if (avail_out < avail)
avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
png_ptr->zstream.avail_out = avail;
avail_out -= avail;
/* zlib inflate call */
/* In fact 'avail_out' may be 0 at this point, that happens at the end
* of the read when the final LZ end code was not passed at the end of
* the previous chunk of input data. Tell zlib if we have reached the
* end of the output buffer.
*/
ret = PNG_INFLATE(png_ptr, avail_out > 0 ? Z_NO_FLUSH :
(finish ? Z_FINISH : Z_SYNC_FLUSH));
} while (ret == Z_OK);
/* For safety kill the local buffer pointer now */
if (output == NULL)
png_ptr->zstream.next_out = NULL;
/* Claw back the 'size' and 'remaining_space' byte counts. */
avail_in += png_ptr->zstream.avail_in;
avail_out += png_ptr->zstream.avail_out;
/* Update the input and output sizes; the updated values are the amount
* consumed or written, effectively the inverse of what zlib uses.
*/
if (avail_out > 0)
*output_size_ptr -= avail_out;
if (avail_in > 0)
*input_size_ptr -= avail_in;
/* Ensure png_ptr->zstream.msg is set (even in the success case!) */
png_zstream_error(png_ptr, ret);
return ret;
}
else
{
/* This is a bad internal error. The recovery assigns to the zstream msg
* pointer, which is not owned by the caller, but this is safe; it's only
* used on errors!
*/
png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
return Z_STREAM_ERROR;
}
}
/*
* Decompress trailing data in a chunk. The assumption is that read_buffer
* points at an allocated area holding the contents of a chunk with a
* trailing compressed part. What we get back is an allocated area
* holding the original prefix part and an uncompressed version of the
* trailing part (the malloc area passed in is freed).
*/
static int
png_decompress_chunk(png_structrp png_ptr,
png_uint_32 chunklength, png_uint_32 prefix_size,
png_alloc_size_t *newlength /* must be initialized to the maximum! */,
int terminate /*add a '\0' to the end of the uncompressed data*/)
{
/* TODO: implement different limits for different types of chunk.
*
* The caller supplies *newlength set to the maximum length of the
* uncompressed data, but this routine allocates space for the prefix and
* maybe a '\0' terminator too. We have to assume that 'prefix_size' is
* limited only by the maximum chunk size.
*/
png_alloc_size_t limit = PNG_SIZE_MAX;
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_malloc_max > 0 &&
png_ptr->user_chunk_malloc_max < limit)
limit = png_ptr->user_chunk_malloc_max;
# elif PNG_USER_CHUNK_MALLOC_MAX > 0
if (PNG_USER_CHUNK_MALLOC_MAX < limit)
limit = PNG_USER_CHUNK_MALLOC_MAX;
# endif
if (limit >= prefix_size + (terminate != 0))
{
int ret;
limit -= prefix_size + (terminate != 0);
if (limit < *newlength)
*newlength = limit;
/* Now try to claim the stream. */
ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
if (ret == Z_OK)
{
png_uint_32 lzsize = chunklength - prefix_size;
ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
/* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
/* output: */ NULL, newlength);
if (ret == Z_STREAM_END)
{
/* Use 'inflateReset' here, not 'inflateReset2' because this
* preserves the previously decided window size (otherwise it would
* be necessary to store the previous window size.) In practice
* this doesn't matter anyway, because png_inflate will call inflate
* with Z_FINISH in almost all cases, so the window will not be
* maintained.
*/
if (inflateReset(&png_ptr->zstream) == Z_OK)
{
/* Because of the limit checks above we know that the new,
* expanded, size will fit in a size_t (let alone an
* png_alloc_size_t). Use png_malloc_base here to avoid an
* extra OOM message.
*/
png_alloc_size_t new_size = *newlength;
png_alloc_size_t buffer_size = prefix_size + new_size +
(terminate != 0);
png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
buffer_size));
if (text != NULL)
{
memset(text, 0, buffer_size);
ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
png_ptr->read_buffer + prefix_size, &lzsize,
text + prefix_size, newlength);
if (ret == Z_STREAM_END)
{
if (new_size == *newlength)
{
if (terminate != 0)
text[prefix_size + *newlength] = 0;
if (prefix_size > 0)
memcpy(text, png_ptr->read_buffer, prefix_size);
{
png_bytep old_ptr = png_ptr->read_buffer;
png_ptr->read_buffer = text;
png_ptr->read_buffer_size = buffer_size;
text = old_ptr; /* freed below */
}
}
else
{
/* The size changed on the second read, there can be no
* guarantee that anything is correct at this point.
* The 'msg' pointer has been set to "unexpected end of
* LZ stream", which is fine, but return an error code
* that the caller won't accept.
*/
ret = PNG_UNEXPECTED_ZLIB_RETURN;
}
}
else if (ret == Z_OK)
ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
/* Free the text pointer (this is the old read_buffer on
* success)
*/
png_free(png_ptr, text);
/* This really is very benign, but it's still an error because
* the extra space may otherwise be used as a Trojan Horse.
*/
if (ret == Z_STREAM_END &&
chunklength - prefix_size != lzsize)
png_chunk_benign_error(png_ptr, "extra compressed data");
}
else
{
/* Out of memory allocating the buffer */
ret = Z_MEM_ERROR;
png_zstream_error(png_ptr, Z_MEM_ERROR);
}
}
else
{
/* inflateReset failed, store the error message */
png_zstream_error(png_ptr, ret);
ret = PNG_UNEXPECTED_ZLIB_RETURN;
}
}
else if (ret == Z_OK)
ret = PNG_UNEXPECTED_ZLIB_RETURN;
/* Release the claimed stream */
png_ptr->zowner = 0;
}
else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
ret = PNG_UNEXPECTED_ZLIB_RETURN;
return ret;
}
else
{
/* Application/configuration limits exceeded */
png_zstream_error(png_ptr, Z_MEM_ERROR);
return Z_MEM_ERROR;
}
}
#endif /* READ_zTXt || READ_iTXt */
#endif /* READ_COMPRESSED_TEXT */
#ifdef PNG_READ_iCCP_SUPPORTED
/* Perform a partial read and decompress, producing 'avail_out' bytes and
* reading from the current chunk as required.
*/
static int
png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
int finish)
{
if (png_ptr->zowner == png_ptr->chunk_name)
{
int ret;
/* next_in and avail_in must have been initialized by the caller. */
png_ptr->zstream.next_out = next_out;
png_ptr->zstream.avail_out = 0; /* set in the loop */
do
{
if (png_ptr->zstream.avail_in == 0)
{
if (read_size > *chunk_bytes)
read_size = (uInt)*chunk_bytes;
*chunk_bytes -= read_size;
if (read_size > 0)
png_crc_read(png_ptr, read_buffer, read_size);
png_ptr->zstream.next_in = read_buffer;
png_ptr->zstream.avail_in = read_size;
}
if (png_ptr->zstream.avail_out == 0)
{
uInt avail = ZLIB_IO_MAX;
if (avail > *out_size)
avail = (uInt)*out_size;
*out_size -= avail;
png_ptr->zstream.avail_out = avail;
}
/* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
* the available output is produced; this allows reading of truncated
* streams.
*/
ret = PNG_INFLATE(png_ptr, *chunk_bytes > 0 ?
Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
}
while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
*out_size += png_ptr->zstream.avail_out;
png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
/* Ensure the error message pointer is always set: */
png_zstream_error(png_ptr, ret);
return ret;
}
else
{
png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
return Z_STREAM_ERROR;
}
}
#endif /* READ_iCCP */
/* Read and check the IDHR chunk */
void /* PRIVATE */
png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_byte buf[13];
png_uint_32 width, height;
int bit_depth, color_type, compression_type, filter_type;
int interlace_type;
png_debug(1, "in png_handle_IHDR");
if ((png_ptr->mode & PNG_HAVE_IHDR) != 0)
png_chunk_error(png_ptr, "out of place");
/* Check the length */
if (length != 13)
png_chunk_error(png_ptr, "invalid");
png_ptr->mode |= PNG_HAVE_IHDR;
png_crc_read(png_ptr, buf, 13);
png_crc_finish(png_ptr, 0);
width = png_get_uint_31(png_ptr, buf);
height = png_get_uint_31(png_ptr, buf + 4);
bit_depth = buf[8];
color_type = buf[9];
compression_type = buf[10];
filter_type = buf[11];
interlace_type = buf[12];
/* Set internal variables */
png_ptr->width = width;
png_ptr->height = height;
png_ptr->bit_depth = (png_byte)bit_depth;
png_ptr->interlaced = (png_byte)interlace_type;
png_ptr->color_type = (png_byte)color_type;
#ifdef PNG_MNG_FEATURES_SUPPORTED
png_ptr->filter_type = (png_byte)filter_type;
#endif
png_ptr->compression_type = (png_byte)compression_type;
/* Find number of channels */
switch (png_ptr->color_type)
{
default: /* invalid, png_set_IHDR calls png_error */
case PNG_COLOR_TYPE_GRAY:
case PNG_COLOR_TYPE_PALETTE:
png_ptr->channels = 1;
break;
case PNG_COLOR_TYPE_RGB:
png_ptr->channels = 3;
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
png_ptr->channels = 2;
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
png_ptr->channels = 4;
break;
}
/* Set up other useful info */
png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth * png_ptr->channels);
png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
png_debug1(3, "channels = %d", png_ptr->channels);
png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
color_type, interlace_type, compression_type, filter_type);
}
/* Read and check the palette */
void /* PRIVATE */
png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_color palette[PNG_MAX_PALETTE_LENGTH];
int max_palette_length, num, i;
#ifdef PNG_POINTER_INDEXING_SUPPORTED
png_colorp pal_ptr;
#endif
png_debug(1, "in png_handle_PLTE");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
/* Moved to before the 'after IDAT' check below because otherwise duplicate
* PLTE chunks are potentially ignored (the spec says there shall not be more
* than one PLTE, the error is not treated as benign, so this check trumps
* the requirement that PLTE appears before IDAT.)
*/
else if ((png_ptr->mode & PNG_HAVE_PLTE) != 0)
png_chunk_error(png_ptr, "duplicate");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{
/* This is benign because the non-benign error happened before, when an
* IDAT was encountered in a color-mapped image with no PLTE.
*/
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
png_ptr->mode |= PNG_HAVE_PLTE;
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
return;
}
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
{
png_crc_finish(png_ptr, length);
return;
}
#endif
if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
{
png_crc_finish(png_ptr, length);
if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
png_chunk_benign_error(png_ptr, "invalid");
else
png_chunk_error(png_ptr, "invalid");
return;
}
/* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
num = (int)length / 3;
/* If the palette has 256 or fewer entries but is too large for the bit
* depth, we don't issue an error, to preserve the behavior of previous
* libpng versions. We silently truncate the unused extra palette entries
* here.
*/
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
max_palette_length = (1 << png_ptr->bit_depth);
else
max_palette_length = PNG_MAX_PALETTE_LENGTH;
if (num > max_palette_length)
num = max_palette_length;
#ifdef PNG_POINTER_INDEXING_SUPPORTED
for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
{
png_byte buf[3];
png_crc_read(png_ptr, buf, 3);
pal_ptr->red = buf[0];
pal_ptr->green = buf[1];
pal_ptr->blue = buf[2];
}
#else
for (i = 0; i < num; i++)
{
png_byte buf[3];
png_crc_read(png_ptr, buf, 3);
/* Don't depend upon png_color being any order */
palette[i].red = buf[0];
palette[i].green = buf[1];
palette[i].blue = buf[2];
}
#endif
/* If we actually need the PLTE chunk (ie for a paletted image), we do
* whatever the normal CRC configuration tells us. However, if we
* have an RGB image, the PLTE can be considered ancillary, so
* we will act as though it is.
*/
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
#endif
{
png_crc_finish(png_ptr, (png_uint_32) (length - (unsigned int)num * 3));
}
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
else if (png_crc_error(png_ptr) != 0) /* Only if we have a CRC error */
{
/* If we don't want to use the data from an ancillary chunk,
* we have two options: an error abort, or a warning and we
* ignore the data in this chunk (which should be OK, since
* it's considered ancillary for a RGB or RGBA image).
*
* IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
* chunk type to determine whether to check the ancillary or the critical
* flags.
*/
if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE) == 0)
{
if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) != 0)
return;
else
png_chunk_error(png_ptr, "CRC error");
}
/* Otherwise, we (optionally) emit a warning and use the chunk. */
else if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0)
png_chunk_warning(png_ptr, "CRC error");
}
#endif
/* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
* own copy of the palette. This has the side effect that when png_start_row
* is called (this happens after any call to png_read_update_info) the
* info_ptr palette gets changed. This is extremely unexpected and
* confusing.
*
* Fix this by not sharing the palette in this way.
*/
png_set_PLTE(png_ptr, info_ptr, palette, num);
/* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
* IDAT. Prior to 1.6.0 this was not checked; instead the code merely
* checked the apparent validity of a tRNS chunk inserted before PLTE on a
* palette PNG. 1.6.0 attempts to rigorously follow the standard and
* therefore does a benign error if the erroneous condition is detected *and*
* cancels the tRNS if the benign error returns. The alternative is to
* amend the standard since it would be rather hypocritical of the standards
* maintainers to ignore it.
*/
#ifdef PNG_READ_tRNS_SUPPORTED
if (png_ptr->num_trans > 0 ||
(info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
{
/* Cancel this because otherwise it would be used if the transforms
* require it. Don't cancel the 'valid' flag because this would prevent
* detection of duplicate chunks.
*/
png_ptr->num_trans = 0;
if (info_ptr != NULL)
info_ptr->num_trans = 0;
png_chunk_benign_error(png_ptr, "tRNS must be after");
}
#endif
#ifdef PNG_READ_hIST_SUPPORTED
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
png_chunk_benign_error(png_ptr, "hIST must be after");
#endif
#ifdef PNG_READ_bKGD_SUPPORTED
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
png_chunk_benign_error(png_ptr, "bKGD must be after");
#endif
}
void /* PRIVATE */
png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_debug(1, "in png_handle_IEND");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0 ||
(png_ptr->mode & PNG_HAVE_IDAT) == 0)
png_chunk_error(png_ptr, "out of place");
png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
png_crc_finish(png_ptr, length);
if (length != 0)
png_chunk_benign_error(png_ptr, "invalid");
PNG_UNUSED(info_ptr)
}
#ifdef PNG_READ_gAMA_SUPPORTED
void /* PRIVATE */
png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_fixed_point igamma;
png_byte buf[4];
png_debug(1, "in png_handle_gAMA");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
if (length != 4)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, buf, 4);
if (png_crc_finish(png_ptr, 0) != 0)
return;
igamma = png_get_fixed_point(NULL, buf);
png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
png_colorspace_sync(png_ptr, info_ptr);
}
#endif
#ifdef PNG_READ_sBIT_SUPPORTED
void /* PRIVATE */
png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
unsigned int truelen, i;
png_byte sample_depth;
png_byte buf[4];
png_debug(1, "in png_handle_sBIT");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
truelen = 3;
sample_depth = 8;
}
else
{
truelen = png_ptr->channels;
sample_depth = png_ptr->bit_depth;
}
if (length != truelen || length > 4)
{
png_chunk_benign_error(png_ptr, "invalid");
png_crc_finish(png_ptr, length);
return;
}
buf[0] = buf[1] = buf[2] = buf[3] = sample_depth;
png_crc_read(png_ptr, buf, truelen);
if (png_crc_finish(png_ptr, 0) != 0)
return;
for (i=0; i<truelen; ++i)
{
if (buf[i] == 0 || buf[i] > sample_depth)
{
png_chunk_benign_error(png_ptr, "invalid");
return;
}
}
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
{
png_ptr->sig_bit.red = buf[0];
png_ptr->sig_bit.green = buf[1];
png_ptr->sig_bit.blue = buf[2];
png_ptr->sig_bit.alpha = buf[3];
}
else
{
png_ptr->sig_bit.gray = buf[0];
png_ptr->sig_bit.red = buf[0];
png_ptr->sig_bit.green = buf[0];
png_ptr->sig_bit.blue = buf[0];
png_ptr->sig_bit.alpha = buf[1];
}
png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
}
#endif
#ifdef PNG_READ_cHRM_SUPPORTED
void /* PRIVATE */
png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_byte buf[32];
png_xy xy;
png_debug(1, "in png_handle_cHRM");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
if (length != 32)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, buf, 32);
if (png_crc_finish(png_ptr, 0) != 0)
return;
xy.whitex = png_get_fixed_point(NULL, buf);
xy.whitey = png_get_fixed_point(NULL, buf + 4);
xy.redx = png_get_fixed_point(NULL, buf + 8);
xy.redy = png_get_fixed_point(NULL, buf + 12);
xy.greenx = png_get_fixed_point(NULL, buf + 16);
xy.greeny = png_get_fixed_point(NULL, buf + 20);
xy.bluex = png_get_fixed_point(NULL, buf + 24);
xy.bluey = png_get_fixed_point(NULL, buf + 28);
if (xy.whitex == PNG_FIXED_ERROR ||
xy.whitey == PNG_FIXED_ERROR ||
xy.redx == PNG_FIXED_ERROR ||
xy.redy == PNG_FIXED_ERROR ||
xy.greenx == PNG_FIXED_ERROR ||
xy.greeny == PNG_FIXED_ERROR ||
xy.bluex == PNG_FIXED_ERROR ||
xy.bluey == PNG_FIXED_ERROR)
{
png_chunk_benign_error(png_ptr, "invalid values");
return;
}
/* If a colorspace error has already been output skip this chunk */
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
return;
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0)
{
png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
png_colorspace_sync(png_ptr, info_ptr);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
(void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
1/*prefer cHRM values*/);
png_colorspace_sync(png_ptr, info_ptr);
}
#endif
#ifdef PNG_READ_sRGB_SUPPORTED
void /* PRIVATE */
png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_byte intent;
png_debug(1, "in png_handle_sRGB");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
if (length != 1)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, &intent, 1);
if (png_crc_finish(png_ptr, 0) != 0)
return;
/* If a colorspace error has already been output skip this chunk */
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
return;
/* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
* this.
*/
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) != 0)
{
png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
png_colorspace_sync(png_ptr, info_ptr);
png_chunk_benign_error(png_ptr, "too many profiles");
return;
}
(void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
png_colorspace_sync(png_ptr, info_ptr);
}
#endif /* READ_sRGB */
#ifdef PNG_READ_iCCP_SUPPORTED
void /* PRIVATE */
png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
/* Note: this does not properly handle profiles that are > 64K under DOS */
{
png_const_charp errmsg = NULL; /* error message output, or no error */
int finished = 0; /* crc checked */
png_debug(1, "in png_handle_iCCP");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
/* Consistent with all the above colorspace handling an obviously *invalid*
* chunk is just ignored, so does not invalidate the color space. An
* alternative is to set the 'invalid' flags at the start of this routine
* and only clear them in they were not set before and all the tests pass.
*/
/* The keyword must be at least one character and there is a
* terminator (0) byte and the compression method byte, and the
* 'zlib' datastream is at least 11 bytes.
*/
if (length < 14)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too short");
return;
}
/* If a colorspace error has already been output skip this chunk */
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
{
png_crc_finish(png_ptr, length);
return;
}
/* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
* this.
*/
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
{
uInt read_length, keyword_length;
char keyword[81];
/* Find the keyword; the keyword plus separator and compression method
* bytes can be at most 81 characters long.
*/
read_length = 81; /* maximum */
if (read_length > length)
read_length = (uInt)length;
png_crc_read(png_ptr, (png_bytep)keyword, read_length);
length -= read_length;
/* The minimum 'zlib' stream is assumed to be just the 2 byte header,
* 5 bytes minimum 'deflate' stream, and the 4 byte checksum.
*/
if (length < 11)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too short");
return;
}
keyword_length = 0;
while (keyword_length < 80 && keyword_length < read_length &&
keyword[keyword_length] != 0)
++keyword_length;
/* TODO: make the keyword checking common */
if (keyword_length >= 1 && keyword_length <= 79)
{
/* We only understand '0' compression - deflate - so if we get a
* different value we can't safely decode the chunk.
*/
if (keyword_length+1 < read_length &&
keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
{
read_length -= keyword_length+2;
if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
{
Byte profile_header[132]={0};
Byte local_buffer[PNG_INFLATE_BUF_SIZE];
png_alloc_size_t size = (sizeof profile_header);
png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
png_ptr->zstream.avail_in = read_length;
(void)png_inflate_read(png_ptr, local_buffer,
(sizeof local_buffer), &length, profile_header, &size,
0/*finish: don't, because the output is too small*/);
if (size == 0)
{
/* We have the ICC profile header; do the basic header checks.
*/
png_uint_32 profile_length = png_get_uint_32(profile_header);
if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
keyword, profile_length) != 0)
{
/* The length is apparently ok, so we can check the 132
* byte header.
*/
if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
keyword, profile_length, profile_header,
png_ptr->color_type) != 0)
{
/* Now read the tag table; a variable size buffer is
* needed at this point, allocate one for the whole
* profile. The header check has already validated
* that none of this stuff will overflow.
*/
png_uint_32 tag_count =
png_get_uint_32(profile_header + 128);
png_bytep profile = png_read_buffer(png_ptr,
profile_length, 2/*silent*/);
if (profile != NULL)
{
memcpy(profile, profile_header,
(sizeof profile_header));
size = 12 * tag_count;
(void)png_inflate_read(png_ptr, local_buffer,
(sizeof local_buffer), &length,
profile + (sizeof profile_header), &size, 0);
/* Still expect a buffer error because we expect
* there to be some tag data!
*/
if (size == 0)
{
if (png_icc_check_tag_table(png_ptr,
&png_ptr->colorspace, keyword, profile_length,
profile) != 0)
{
/* The profile has been validated for basic
* security issues, so read the whole thing in.
*/
size = profile_length - (sizeof profile_header)
- 12 * tag_count;
(void)png_inflate_read(png_ptr, local_buffer,
(sizeof local_buffer), &length,
profile + (sizeof profile_header) +
12 * tag_count, &size, 1/*finish*/);
if (length > 0 && !(png_ptr->flags &
PNG_FLAG_BENIGN_ERRORS_WARN))
errmsg = "extra compressed data";
/* But otherwise allow extra data: */
else if (size == 0)
{
if (length > 0)
{
/* This can be handled completely, so
* keep going.
*/
png_chunk_warning(png_ptr,
"extra compressed data");
}
png_crc_finish(png_ptr, length);
finished = 1;
# if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
/* Check for a match against sRGB */
png_icc_set_sRGB(png_ptr,
&png_ptr->colorspace, profile,
png_ptr->zstream.adler);
# endif
/* Steal the profile for info_ptr. */
if (info_ptr != NULL)
{
png_free_data(png_ptr, info_ptr,
PNG_FREE_ICCP, 0);
info_ptr->iccp_name = png_voidcast(char*,
png_malloc_base(png_ptr,
keyword_length+1));
if (info_ptr->iccp_name != NULL)
{
memcpy(info_ptr->iccp_name, keyword,
keyword_length+1);
info_ptr->iccp_proflen =
profile_length;
info_ptr->iccp_profile = profile;
png_ptr->read_buffer = NULL; /*steal*/
info_ptr->free_me |= PNG_FREE_ICCP;
info_ptr->valid |= PNG_INFO_iCCP;
}
else
{
png_ptr->colorspace.flags |=
PNG_COLORSPACE_INVALID;
errmsg = "out of memory";
}
}
/* else the profile remains in the read
* buffer which gets reused for subsequent
* chunks.
*/
if (info_ptr != NULL)
png_colorspace_sync(png_ptr, info_ptr);
if (errmsg == NULL)
{
png_ptr->zowner = 0;
return;
}
}
if (errmsg == NULL)
errmsg = png_ptr->zstream.msg;
}
/* else png_icc_check_tag_table output an error */
}
else /* profile truncated */
errmsg = png_ptr->zstream.msg;
}
else
errmsg = "out of memory";
}
/* else png_icc_check_header output an error */
}
/* else png_icc_check_length output an error */
}
else /* profile truncated */
errmsg = png_ptr->zstream.msg;
/* Release the stream */
png_ptr->zowner = 0;
}
else /* png_inflate_claim failed */
errmsg = png_ptr->zstream.msg;
}
else
errmsg = "bad compression method"; /* or missing */
}
else
errmsg = "bad keyword";
}
else
errmsg = "too many profiles";
/* Failure: the reason is in 'errmsg' */
if (finished == 0)
png_crc_finish(png_ptr, length);
png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
png_colorspace_sync(png_ptr, info_ptr);
if (errmsg != NULL) /* else already output */
png_chunk_benign_error(png_ptr, errmsg);
}
#endif /* READ_iCCP */
#ifdef PNG_READ_sPLT_SUPPORTED
void /* PRIVATE */
png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
/* Note: this does not properly handle chunks that are > 64K under DOS */
{
png_bytep entry_start, buffer;
png_sPLT_t new_palette;
png_sPLT_entryp pp;
png_uint_32 data_length;
int entry_size, i;
png_uint_32 skip = 0;
png_uint_32 dl;
size_t max_dl;
png_debug(1, "in png_handle_sPLT");
#ifdef PNG_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_cache_max != 0)
{
if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_warning(png_ptr, "No space in chunk cache for sPLT");
png_crc_finish(png_ptr, length);
return;
}
}
#endif
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
#ifdef PNG_MAX_MALLOC_64K
if (length > 65535U)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too large to fit in memory");
return;
}
#endif
buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return;
}
/* WARNING: this may break if size_t is less than 32 bits; it is assumed
* that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
* potential breakage point if the types in pngconf.h aren't exactly right.
*/
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, skip) != 0)
return;
buffer[length] = 0;
for (entry_start = buffer; *entry_start; entry_start++)
/* Empty loop to find end of name */ ;
++entry_start;
/* A sample depth should follow the separator, and we should be on it */
if (length < 2U || entry_start > buffer + (length - 2U))
{
png_warning(png_ptr, "malformed sPLT chunk");
return;
}
new_palette.depth = *entry_start++;
entry_size = (new_palette.depth == 8 ? 6 : 10);
/* This must fit in a png_uint_32 because it is derived from the original
* chunk data length.
*/
data_length = length - (png_uint_32)(entry_start - buffer);
/* Integrity-check the data length */
if ((data_length % (unsigned int)entry_size) != 0)
{
png_warning(png_ptr, "sPLT chunk has bad length");
return;
}
dl = (png_uint_32)(data_length / (unsigned int)entry_size);
max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
if (dl > max_dl)
{
png_warning(png_ptr, "sPLT chunk too long");
return;
}
new_palette.nentries = (png_int_32)(data_length / (unsigned int)entry_size);
new_palette.entries = (png_sPLT_entryp)png_malloc_warn(png_ptr,
(png_alloc_size_t) new_palette.nentries * (sizeof (png_sPLT_entry)));
if (new_palette.entries == NULL)
{
png_warning(png_ptr, "sPLT chunk requires too much memory");
return;
}
#ifdef PNG_POINTER_INDEXING_SUPPORTED
for (i = 0; i < new_palette.nentries; i++)
{
pp = new_palette.entries + i;
if (new_palette.depth == 8)
{
pp->red = *entry_start++;
pp->green = *entry_start++;
pp->blue = *entry_start++;
pp->alpha = *entry_start++;
}
else
{
pp->red = png_get_uint_16(entry_start); entry_start += 2;
pp->green = png_get_uint_16(entry_start); entry_start += 2;
pp->blue = png_get_uint_16(entry_start); entry_start += 2;
pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
}
pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
}
#else
pp = new_palette.entries;
for (i = 0; i < new_palette.nentries; i++)
{
if (new_palette.depth == 8)
{
pp[i].red = *entry_start++;
pp[i].green = *entry_start++;
pp[i].blue = *entry_start++;
pp[i].alpha = *entry_start++;
}
else
{
pp[i].red = png_get_uint_16(entry_start); entry_start += 2;
pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
pp[i].blue = png_get_uint_16(entry_start); entry_start += 2;
pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
}
pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
}
#endif
/* Discard all chunk data except the name and stash that */
new_palette.name = (png_charp)buffer;
png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
png_free(png_ptr, new_palette.entries);
}
#endif /* READ_sPLT */
#ifdef PNG_READ_tRNS_SUPPORTED
void /* PRIVATE */
png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
png_debug(1, "in png_handle_tRNS");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
{
png_byte buf[2];
if (length != 2)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, buf, 2);
png_ptr->num_trans = 1;
png_ptr->trans_color.gray = png_get_uint_16(buf);
}
else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
{
png_byte buf[6];
if (length != 6)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, buf, length);
png_ptr->num_trans = 1;
png_ptr->trans_color.red = png_get_uint_16(buf);
png_ptr->trans_color.green = png_get_uint_16(buf + 2);
png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
}
else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
if ((png_ptr->mode & PNG_HAVE_PLTE) == 0)
{
/* TODO: is this actually an error in the ISO spec? */
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
if (length > (unsigned int) png_ptr->num_palette ||
length > (unsigned int) PNG_MAX_PALETTE_LENGTH ||
length == 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, readbuf, length);
png_ptr->num_trans = (png_uint_16)length;
}
else
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid with alpha channel");
return;
}
if (png_crc_finish(png_ptr, 0) != 0)
{
png_ptr->num_trans = 0;
return;
}
/* TODO: this is a horrible side effect in the palette case because the
* png_struct ends up with a pointer to the tRNS buffer owned by the
* png_info. Fix this.
*/
png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
&(png_ptr->trans_color));
}
#endif
#ifdef PNG_READ_bKGD_SUPPORTED
void /* PRIVATE */
png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
unsigned int truelen;
png_byte buf[6];
png_color_16 background;
png_debug(1, "in png_handle_bKGD");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
(png_ptr->mode & PNG_HAVE_PLTE) == 0))
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
truelen = 1;
else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
truelen = 6;
else
truelen = 2;
if (length != truelen)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, buf, truelen);
if (png_crc_finish(png_ptr, 0) != 0)
return;
/* We convert the index value into RGB components so that we can allow
* arbitrary RGB values for background when we have transparency, and
* so it is easy to determine the RGB values of the background color
* from the info_ptr struct.
*/
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
background.index = buf[0];
if (info_ptr != NULL && info_ptr->num_palette != 0)
{
if (buf[0] >= info_ptr->num_palette)
{
png_chunk_benign_error(png_ptr, "invalid index");
return;
}
background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
}
else
background.red = background.green = background.blue = 0;
background.gray = 0;
}
else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) /* GRAY */
{
if (png_ptr->bit_depth <= 8)
{
if (buf[0] != 0 || buf[1] >= (unsigned int)(1 << png_ptr->bit_depth))
{
png_chunk_benign_error(png_ptr, "invalid gray level");
return;
}
}
background.index = 0;
background.red =
background.green =
background.blue =
background.gray = png_get_uint_16(buf);
}
else
{
if (png_ptr->bit_depth <= 8)
{
if (buf[0] != 0 || buf[2] != 0 || buf[4] != 0)
{
png_chunk_benign_error(png_ptr, "invalid color");
return;
}
}
background.index = 0;
background.red = png_get_uint_16(buf);
background.green = png_get_uint_16(buf + 2);
background.blue = png_get_uint_16(buf + 4);
background.gray = 0;
}
png_set_bKGD(png_ptr, info_ptr, &background);
}
#endif
#ifdef PNG_READ_eXIf_SUPPORTED
void /* PRIVATE */
png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
unsigned int i;
png_debug(1, "in png_handle_eXIf");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
if (length < 2)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too short");
return;
}
else if (info_ptr == NULL || (info_ptr->valid & PNG_INFO_eXIf) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
info_ptr->free_me |= PNG_FREE_EXIF;
info_ptr->eXIf_buf = png_voidcast(png_bytep,
png_malloc_warn(png_ptr, length));
if (info_ptr->eXIf_buf == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return;
}
for (i = 0; i < length; i++)
{
png_byte buf[1];
png_crc_read(png_ptr, buf, 1);
info_ptr->eXIf_buf[i] = buf[0];
if (i == 1 && buf[0] != 'M' && buf[0] != 'I'
&& info_ptr->eXIf_buf[0] != buf[0])
{
png_crc_finish(png_ptr, length-i-1);
png_chunk_benign_error(png_ptr, "incorrect byte-order specifier");
png_free(png_ptr, info_ptr->eXIf_buf);
info_ptr->eXIf_buf = NULL;
return;
}
}
if (png_crc_finish(png_ptr, 0) == 0)
png_set_eXIf_1(png_ptr, info_ptr, length, info_ptr->eXIf_buf);
png_free(png_ptr, info_ptr->eXIf_buf);
info_ptr->eXIf_buf = NULL;
}
#endif
#ifdef PNG_READ_hIST_SUPPORTED
void /* PRIVATE */
png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
unsigned int num, i;
png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
png_debug(1, "in png_handle_hIST");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
(png_ptr->mode & PNG_HAVE_PLTE) == 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
num = length / 2 ;
if (num != (unsigned int) png_ptr->num_palette ||
num > (unsigned int) PNG_MAX_PALETTE_LENGTH)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
for (i = 0; i < num; i++)
{
png_byte buf[2];
png_crc_read(png_ptr, buf, 2);
readbuf[i] = png_get_uint_16(buf);
}
if (png_crc_finish(png_ptr, 0) != 0)
return;
png_set_hIST(png_ptr, info_ptr, readbuf);
}
#endif
#ifdef PNG_READ_pHYs_SUPPORTED
void /* PRIVATE */
png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_byte buf[9];
png_uint_32 res_x, res_y;
int unit_type;
png_debug(1, "in png_handle_pHYs");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
if (length != 9)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, buf, 9);
if (png_crc_finish(png_ptr, 0) != 0)
return;
res_x = png_get_uint_32(buf);
res_y = png_get_uint_32(buf + 4);
unit_type = buf[8];
png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
}
#endif
#ifdef PNG_READ_oFFs_SUPPORTED
void /* PRIVATE */
png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_byte buf[9];
png_int_32 offset_x, offset_y;
int unit_type;
png_debug(1, "in png_handle_oFFs");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
if (length != 9)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, buf, 9);
if (png_crc_finish(png_ptr, 0) != 0)
return;
offset_x = png_get_int_32(buf);
offset_y = png_get_int_32(buf + 4);
unit_type = buf[8];
png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
}
#endif
#ifdef PNG_READ_pCAL_SUPPORTED
/* Read the pCAL chunk (described in the PNG Extensions document) */
void /* PRIVATE */
png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_int_32 X0, X1;
png_byte type, nparams;
png_bytep buffer, buf, units, endptr;
png_charpp params;
int i;
png_debug(1, "in png_handle_pCAL");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
length + 1);
buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0) != 0)
return;
buffer[length] = 0; /* Null terminate the last string */
png_debug(3, "Finding end of pCAL purpose string");
for (buf = buffer; *buf; buf++)
/* Empty loop */ ;
endptr = buffer + length;
/* We need to have at least 12 bytes after the purpose string
* in order to get the parameter information.
*/
if (endptr - buf <= 12)
{
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
X0 = png_get_int_32((png_bytep)buf+1);
X1 = png_get_int_32((png_bytep)buf+5);
type = buf[9];
nparams = buf[10];
units = buf + 11;
png_debug(3, "Checking pCAL equation type and number of parameters");
/* Check that we have the right number of parameters for known
* equation types.
*/
if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
(type == PNG_EQUATION_BASE_E && nparams != 3) ||
(type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
(type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
{
png_chunk_benign_error(png_ptr, "invalid parameter count");
return;
}
else if (type >= PNG_EQUATION_LAST)
{
png_chunk_benign_error(png_ptr, "unrecognized equation type");
}
for (buf = units; *buf; buf++)
/* Empty loop to move past the units string. */ ;
png_debug(3, "Allocating pCAL parameters array");
params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
nparams * (sizeof (png_charp))));
if (params == NULL)
{
png_chunk_benign_error(png_ptr, "out of memory");
return;
}
/* Get pointers to the start of each parameter string. */
for (i = 0; i < nparams; i++)
{
buf++; /* Skip the null string terminator from previous parameter. */
png_debug1(3, "Reading pCAL parameter %d", i);
for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
/* Empty loop to move past each parameter string */ ;
/* Make sure we haven't run out of data yet */
if (buf > endptr)
{
png_free(png_ptr, params);
png_chunk_benign_error(png_ptr, "invalid data");
return;
}
}
png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
(png_charp)units, params);
png_free(png_ptr, params);
}
#endif
#ifdef PNG_READ_sCAL_SUPPORTED
/* Read the sCAL chunk */
void /* PRIVATE */
png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_bytep buffer;
size_t i;
int state;
png_debug(1, "in png_handle_sCAL");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return;
}
else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
/* Need unit type, width, \0, height: minimum 4 bytes */
else if (length < 4)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
length + 1);
buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
if (buffer == NULL)
{
png_chunk_benign_error(png_ptr, "out of memory");
png_crc_finish(png_ptr, length);
return;
}
png_crc_read(png_ptr, buffer, length);
buffer[length] = 0; /* Null terminate the last string */
if (png_crc_finish(png_ptr, 0) != 0)
return;
/* Validate the unit. */
if (buffer[0] != 1 && buffer[0] != 2)
{
png_chunk_benign_error(png_ptr, "invalid unit");
return;
}
/* Validate the ASCII numbers, need two ASCII numbers separated by
* a '\0' and they need to fit exactly in the chunk data.
*/
i = 1;
state = 0;
if (png_check_fp_number((png_const_charp)buffer, length, &state, &i) == 0 ||
i >= length || buffer[i++] != 0)
png_chunk_benign_error(png_ptr, "bad width format");
else if (PNG_FP_IS_POSITIVE(state) == 0)
png_chunk_benign_error(png_ptr, "non-positive width");
else
{
size_t heighti = i;
state = 0;
if (png_check_fp_number((png_const_charp)buffer, length,
&state, &i) == 0 || i != length)
png_chunk_benign_error(png_ptr, "bad height format");
else if (PNG_FP_IS_POSITIVE(state) == 0)
png_chunk_benign_error(png_ptr, "non-positive height");
else
/* This is the (only) success case. */
png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
(png_charp)buffer+1, (png_charp)buffer+heighti);
}
}
#endif
#ifdef PNG_READ_tIME_SUPPORTED
void /* PRIVATE */
png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_byte buf[7];
png_time mod_time;
png_debug(1, "in png_handle_tIME");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
png_ptr->mode |= PNG_AFTER_IDAT;
if (length != 7)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, buf, 7);
if (png_crc_finish(png_ptr, 0) != 0)
return;
mod_time.second = buf[6];
mod_time.minute = buf[5];
mod_time.hour = buf[4];
mod_time.day = buf[3];
mod_time.month = buf[2];
mod_time.year = png_get_uint_16(buf);
png_set_tIME(png_ptr, info_ptr, &mod_time);
}
#endif
#ifdef PNG_READ_tEXt_SUPPORTED
/* Note: this does not properly handle chunks that are > 64K under DOS */
void /* PRIVATE */
png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_text text_info;
png_bytep buffer;
png_charp key;
png_charp text;
png_uint_32 skip = 0;
png_debug(1, "in png_handle_tEXt");
#ifdef PNG_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_cache_max != 0)
{
if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "no space in chunk cache");
return;
}
}
#endif
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
png_ptr->mode |= PNG_AFTER_IDAT;
#ifdef PNG_MAX_MALLOC_64K
if (length > 65535U)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too large to fit in memory");
return;
}
#endif
buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
if (buffer == NULL)
{
png_chunk_benign_error(png_ptr, "out of memory");
return;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, skip) != 0)
return;
key = (png_charp)buffer;
key[length] = 0;
for (text = key; *text; text++)
/* Empty loop to find end of key */ ;
if (text != key + length)
text++;
text_info.compression = PNG_TEXT_COMPRESSION_NONE;
text_info.key = key;
text_info.lang = NULL;
text_info.lang_key = NULL;
text_info.itxt_length = 0;
text_info.text = text;
text_info.text_length = strlen(text);
if (png_set_text_2(png_ptr, info_ptr, &text_info, 1) != 0)
png_warning(png_ptr, "Insufficient memory to process text chunk");
}
#endif
#ifdef PNG_READ_zTXt_SUPPORTED
/* Note: this does not correctly handle chunks that are > 64K under DOS */
void /* PRIVATE */
png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_const_charp errmsg = NULL;
png_bytep buffer;
png_uint_32 keyword_length;
png_debug(1, "in png_handle_zTXt");
#ifdef PNG_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_cache_max != 0)
{
if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "no space in chunk cache");
return;
}
}
#endif
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
png_ptr->mode |= PNG_AFTER_IDAT;
/* Note, "length" is sufficient here; we won't be adding
* a null terminator later.
*/
buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0) != 0)
return;
/* TODO: also check that the keyword contents match the spec! */
for (keyword_length = 0;
keyword_length < length && buffer[keyword_length] != 0;
++keyword_length)
/* Empty loop to find end of name */ ;
if (keyword_length > 79 || keyword_length < 1)
errmsg = "bad keyword";
/* zTXt must have some LZ data after the keyword, although it may expand to
* zero bytes; we need a '\0' at the end of the keyword, the compression type
* then the LZ data:
*/
else if (keyword_length + 3 > length)
errmsg = "truncated";
else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
errmsg = "unknown compression type";
else
{
png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
/* TODO: at present png_decompress_chunk imposes a single application
* level memory limit, this should be split to different values for iCCP
* and text chunks.
*/
if (png_decompress_chunk(png_ptr, length, keyword_length+2,
&uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
{
png_text text;
if (png_ptr->read_buffer == NULL)
errmsg="Read failure in png_handle_zTXt";
else
{
/* It worked; png_ptr->read_buffer now looks like a tEXt chunk
* except for the extra compression type byte and the fact that
* it isn't necessarily '\0' terminated.
*/
buffer = png_ptr->read_buffer;
buffer[uncompressed_length+(keyword_length+2)] = 0;
text.compression = PNG_TEXT_COMPRESSION_zTXt;
text.key = (png_charp)buffer;
text.text = (png_charp)(buffer + keyword_length+2);
text.text_length = uncompressed_length;
text.itxt_length = 0;
text.lang = NULL;
text.lang_key = NULL;
if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
errmsg = "insufficient memory";
}
}
else
errmsg = png_ptr->zstream.msg;
}
if (errmsg != NULL)
png_chunk_benign_error(png_ptr, errmsg);
}
#endif
#ifdef PNG_READ_iTXt_SUPPORTED
/* Note: this does not correctly handle chunks that are > 64K under DOS */
void /* PRIVATE */
png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_const_charp errmsg = NULL;
png_bytep buffer;
png_uint_32 prefix_length;
png_debug(1, "in png_handle_iTXt");
#ifdef PNG_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_cache_max != 0)
{
if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "no space in chunk cache");
return;
}
}
#endif
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
png_ptr->mode |= PNG_AFTER_IDAT;
buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0) != 0)
return;
/* First the keyword. */
for (prefix_length=0;
prefix_length < length && buffer[prefix_length] != 0;
++prefix_length)
/* Empty loop */ ;
/* Perform a basic check on the keyword length here. */
if (prefix_length > 79 || prefix_length < 1)
errmsg = "bad keyword";
/* Expect keyword, compression flag, compression type, language, translated
* keyword (both may be empty but are 0 terminated) then the text, which may
* be empty.
*/
else if (prefix_length + 5 > length)
errmsg = "truncated";
else if (buffer[prefix_length+1] == 0 ||
(buffer[prefix_length+1] == 1 &&
buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
{
int compressed = buffer[prefix_length+1] != 0;
png_uint_32 language_offset, translated_keyword_offset;
png_alloc_size_t uncompressed_length = 0;
/* Now the language tag */
prefix_length += 3;
language_offset = prefix_length;
for (; prefix_length < length && buffer[prefix_length] != 0;
++prefix_length)
/* Empty loop */ ;
/* WARNING: the length may be invalid here, this is checked below. */
translated_keyword_offset = ++prefix_length;
for (; prefix_length < length && buffer[prefix_length] != 0;
++prefix_length)
/* Empty loop */ ;
/* prefix_length should now be at the trailing '\0' of the translated
* keyword, but it may already be over the end. None of this arithmetic
* can overflow because chunks are at most 2^31 bytes long, but on 16-bit
* systems the available allocation may overflow.
*/
++prefix_length;
if (compressed == 0 && prefix_length <= length)
uncompressed_length = length - prefix_length;
else if (compressed != 0 && prefix_length < length)
{
uncompressed_length = PNG_SIZE_MAX;
/* TODO: at present png_decompress_chunk imposes a single application
* level memory limit, this should be split to different values for
* iCCP and text chunks.
*/
if (png_decompress_chunk(png_ptr, length, prefix_length,
&uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
buffer = png_ptr->read_buffer;
else
errmsg = png_ptr->zstream.msg;
}
else
errmsg = "truncated";
if (errmsg == NULL)
{
png_text text;
buffer[uncompressed_length+prefix_length] = 0;
if (compressed == 0)
text.compression = PNG_ITXT_COMPRESSION_NONE;
else
text.compression = PNG_ITXT_COMPRESSION_zTXt;
text.key = (png_charp)buffer;
text.lang = (png_charp)buffer + language_offset;
text.lang_key = (png_charp)buffer + translated_keyword_offset;
text.text = (png_charp)buffer + prefix_length;
text.text_length = 0;
text.itxt_length = uncompressed_length;
if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
errmsg = "insufficient memory";
}
}
else
errmsg = "bad compression info";
if (errmsg != NULL)
png_chunk_benign_error(png_ptr, errmsg);
}
#endif
#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
/* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
static int
png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
{
png_alloc_size_t limit = PNG_SIZE_MAX;
if (png_ptr->unknown_chunk.data != NULL)
{
png_free(png_ptr, png_ptr->unknown_chunk.data);
png_ptr->unknown_chunk.data = NULL;
}
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_malloc_max > 0 &&
png_ptr->user_chunk_malloc_max < limit)
limit = png_ptr->user_chunk_malloc_max;
# elif PNG_USER_CHUNK_MALLOC_MAX > 0
if (PNG_USER_CHUNK_MALLOC_MAX < limit)
limit = PNG_USER_CHUNK_MALLOC_MAX;
# endif
if (length <= limit)
{
PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
/* The following is safe because of the PNG_SIZE_MAX init above */
png_ptr->unknown_chunk.size = (size_t)length/*SAFE*/;
/* 'mode' is a flag array, only the bottom four bits matter here */
png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
if (length == 0)
png_ptr->unknown_chunk.data = NULL;
else
{
/* Do a 'warn' here - it is handled below. */
png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
png_malloc_warn(png_ptr, length));
}
}
if (png_ptr->unknown_chunk.data == NULL && length > 0)
{
/* This is benign because we clean up correctly */
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
return 0;
}
else
{
if (length > 0)
png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
png_crc_finish(png_ptr, 0);
return 1;
}
}
#endif /* READ_UNKNOWN_CHUNKS */
/* Handle an unknown, or known but disabled, chunk */
void /* PRIVATE */
png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
png_uint_32 length, int keep)
{
int handled = 0; /* the chunk was handled */
png_debug(1, "in png_handle_unknown");
#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
/* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
* the bug which meant that setting a non-default behavior for a specific
* chunk would be ignored (the default was always used unless a user
* callback was installed).
*
* 'keep' is the value from the png_chunk_unknown_handling, the setting for
* this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
* will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
* This is just an optimization to avoid multiple calls to the lookup
* function.
*/
# ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
# ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
# endif
# endif
/* One of the following methods will read the chunk or skip it (at least one
* of these is always defined because this is the only way to switch on
* PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
*/
# ifdef PNG_READ_USER_CHUNKS_SUPPORTED
/* The user callback takes precedence over the chunk keep value, but the
* keep value is still required to validate a save of a critical chunk.
*/
if (png_ptr->read_user_chunk_fn != NULL)
{
if (png_cache_unknown_chunk(png_ptr, length) != 0)
{
/* Callback to user unknown chunk handler */
int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
&png_ptr->unknown_chunk);
/* ret is:
* negative: An error occurred; png_chunk_error will be called.
* zero: The chunk was not handled, the chunk will be discarded
* unless png_set_keep_unknown_chunks has been used to set
* a 'keep' behavior for this particular chunk, in which
* case that will be used. A critical chunk will cause an
* error at this point unless it is to be saved.
* positive: The chunk was handled, libpng will ignore/discard it.
*/
if (ret < 0)
png_chunk_error(png_ptr, "error in user chunk");
else if (ret == 0)
{
/* If the keep value is 'default' or 'never' override it, but
* still error out on critical chunks unless the keep value is
* 'always' While this is weird it is the behavior in 1.4.12.
* A possible improvement would be to obey the value set for the
* chunk, but this would be an API change that would probably
* damage some applications.
*
* The png_app_warning below catches the case that matters, where
* the application has not set specific save or ignore for this
* chunk or global save or ignore.
*/
if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
{
# ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
{
png_chunk_warning(png_ptr, "Saving unknown chunk:");
png_app_warning(png_ptr,
"forcing save of an unhandled chunk;"
" please call png_set_keep_unknown_chunks");
/* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
}
# endif
keep = PNG_HANDLE_CHUNK_IF_SAFE;
}
}
else /* chunk was handled */
{
handled = 1;
/* Critical chunks can be safely discarded at this point. */
keep = PNG_HANDLE_CHUNK_NEVER;
}
}
else
keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
}
else
/* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
# endif /* READ_USER_CHUNKS */
# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
{
/* keep is currently just the per-chunk setting, if there was no
* setting change it to the global default now (not that this may
* still be AS_DEFAULT) then obtain the cache of the chunk if required,
* if not simply skip the chunk.
*/
if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
keep = png_ptr->unknown_default;
if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
(keep == PNG_HANDLE_CHUNK_IF_SAFE &&
PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
{
if (png_cache_unknown_chunk(png_ptr, length) == 0)
keep = PNG_HANDLE_CHUNK_NEVER;
}
else
png_crc_finish(png_ptr, length);
}
# else
# ifndef PNG_READ_USER_CHUNKS_SUPPORTED
# error no method to support READ_UNKNOWN_CHUNKS
# endif
{
/* If here there is no read callback pointer set and no support is
* compiled in to just save the unknown chunks, so simply skip this
* chunk. If 'keep' is something other than AS_DEFAULT or NEVER then
* the app has erroneously asked for unknown chunk saving when there
* is no support.
*/
if (keep > PNG_HANDLE_CHUNK_NEVER)
png_app_error(png_ptr, "no unknown chunk support available");
png_crc_finish(png_ptr, length);
}
# endif
# ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
/* 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");
/* FALLTHROUGH */
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);
/* FALLTHROUGH */
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_const_structrp png_ptr, png_uint_32 chunk_name)
{
int i;
png_uint_32 cn=chunk_name;
png_debug(1, "in png_check_chunk_name");
for (i=1; i<=4; ++i)
{
int c = cn & 0xff;
if (c < 65 || c > 122 || (c > 90 && c < 97))
png_chunk_error(png_ptr, "invalid chunk type");
cn >>= 8;
}
}
void /* PRIVATE */
png_check_chunk_length(png_const_structrp png_ptr, png_uint_32 length)
{
png_alloc_size_t limit = PNG_UINT_31_MAX;
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_malloc_max > 0 &&
png_ptr->user_chunk_malloc_max < limit)
limit = png_ptr->user_chunk_malloc_max;
# elif PNG_USER_CHUNK_MALLOC_MAX > 0
if (PNG_USER_CHUNK_MALLOC_MAX < limit)
limit = PNG_USER_CHUNK_MALLOC_MAX;
# endif
if (png_ptr->chunk_name == png_IDAT)
{
png_alloc_size_t idat_limit = PNG_UINT_31_MAX;
size_t row_factor =
(size_t)png_ptr->width
* (size_t)png_ptr->channels
* (png_ptr->bit_depth > 8? 2: 1)
+ 1
+ (png_ptr->interlaced? 6: 0);
if (png_ptr->height > PNG_UINT_32_MAX/row_factor)
idat_limit = PNG_UINT_31_MAX;
else
idat_limit = png_ptr->height * row_factor;
row_factor = row_factor > 32566? 32566 : row_factor;
idat_limit += 6 + 5*(idat_limit/row_factor+1); /* zlib+deflate overhead */
idat_limit=idat_limit < PNG_UINT_31_MAX? idat_limit : PNG_UINT_31_MAX;