/* pngrutil.c - utilities to read a PNG file
*
* 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
*
* 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
/* The minimum 'zlib' stream is assumed to be just the 2 byte header, 5 bytes
* minimum 'deflate' stream, and the 4 byte checksum.
*/
#define LZ77Min (2U+5U+4U)
#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
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;
}
#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) != 0)
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;
}
/* This function is called to verify that a chunk name is valid.
* Do this using the bit-whacking approach from contrib/tools/pngfix.c
*
* Copied from libpng 1.7.
*/
static int
check_chunk_name(png_uint_32 name)
{
png_uint_32 t;
/* Remove bit 5 from all but the reserved byte; this means
* every 8-bit unit must be in the range 65-90 to be valid.
* So bit 5 must be zero, bit 6 must be set and bit 7 zero.
*/
name &= ~PNG_U32(32,32,0,32);
t = (name & ~0x1f1f1f1fU) ^ 0x40404040U;
/* Subtract 65 for each 8-bit quantity, this must not
* overflow and each byte must then be in the range 0-25.
*/
name -= PNG_U32(65,65,65,65);
t |= name;
/* Subtract 26, handling the overflow which should set the
* top three bits of each byte.
*/
name -= PNG_U32(25,25,25,26);
t |= ~name;
return (t & 0xe0e0e0e0U) == 0U;
}
/* 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 chunk_name, 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. png_struct::chunk_name is immediately
* updated even if they are detectably wrong. This aids error message
* handling by allowing png_chunk_error to be used.
*/
png_read_data(png_ptr, buf, 8);
length = png_get_uint_31(png_ptr, buf);
png_ptr->chunk_name = chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
/* Reset the crc and run it over the chunk name. */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, buf + 4, 4);
png_debug2(0, "Reading chunk typeid = 0x%lx, length = %lu",
(unsigned long)png_ptr->chunk_name, (unsigned long)length);
/* Sanity check the length (first by <= 0x80) and the chunk name. An error
* here indicates a broken stream and libpng has no recovery from this.
*/
if (buf[0] >= 0x80U)
png_chunk_error(png_ptr, "bad header (invalid length)");
/* Check to see if chunk name is valid. */
if (!check_chunk_name(chunk_name))
png_chunk_error(png_ptr, "bad header (invalid type)");
#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);
}
/* Compare the CRC stored in the PNG file with that calculated by libpng from
* the data it has read thus far.
*/
static int
png_crc_error(png_structrp png_ptr, int handle_as_ancillary)
{
png_byte crc_bytes[4];
png_uint_32 crc;
int need_crc = 1;
/* There are four flags two for ancillary and two for critical chunks. The
* default setting of these flags is all zero.
*
* PNG_FLAG_CRC_ANCILLARY_USE
* PNG_FLAG_CRC_ANCILLARY_NOWARN
* USE+NOWARN: no CRC calculation (implemented here), else;
* NOWARN: png_chunk_error on error (implemented in png_crc_finish)
* else: png_chunk_warning on error (implemented in png_crc_finish)
* This is the default.
*
* I.e. NOWARN without USE produces png_chunk_error. The default setting
* where neither are set does the same thing.
*
* PNG_FLAG_CRC_CRITICAL_USE
* PNG_FLAG_CRC_CRITICAL_IGNORE
* IGNORE: no CRC calculation (implemented here), else;
* USE: png_chunk_warning on error (implemented in png_crc_finish)
* else: png_chunk_error on error (implemented in png_crc_finish)
* This is the default.
*
* This arose because of original mis-implementation and has persisted for
* compatibility reasons.
*
* TODO: the flag names are internal so maybe this can be changed to
* something comprehensible.
*/
if (handle_as_ancillary || 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 crc != png_ptr->crc;
}
else
return 0;
}
/* 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.
*
* There is one public version which is used in most places and another which
* takes the value for the 'critical' flag to check. This allows PLTE and IEND
* handling code to ignore the CRC error and removes some confusing code
* duplication.
*/
static int
png_crc_finish_critical(png_structrp png_ptr, png_uint_32 skip,
int handle_as_ancillary)
{
/* 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 'handle_as_ancillary' has been requested and this is a critical chunk
* but PNG_FLAG_CRC_CRITICAL_IGNORE was set then png_read_crc did not, in
* fact, calculate the CRC so the ANCILLARY settings should not be used
* instead.
*/
if (handle_as_ancillary &&
(png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
handle_as_ancillary = 0;
/* TODO: this might be more comprehensible if png_crc_error was inlined here.
*/
if (png_crc_error(png_ptr, handle_as_ancillary) != 0)
{
/* See above for the explanation of how the flags work. */
if (handle_as_ancillary || 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;
}
int /* PRIVATE */
png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
{
return png_crc_finish_critical(png_ptr, skip, 0/*critical handling*/);
}
#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_READ_eXIf_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 on failure.
*/
static png_bytep
png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size)
{
png_bytep buffer = png_ptr->read_buffer;
if (new_size > png_chunk_max(png_ptr)) return NULL;
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)
{
# ifndef PNG_NO_MEMZERO /* for detecting UIM bugs **only** */
memset(buffer, 0, new_size); /* just in case */
# endif
png_ptr->read_buffer = buffer;
png_ptr->read_buffer_size = new_size;
}
}
return buffer;
}
#endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|eXIf|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;
}
#ifdef PNG_DISABLE_ADLER32_CHECK_SUPPORTED
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_chunk_max(png_ptr);
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 */
/* CHUNK HANDLING */
/* Read and check the IDHR chunk */
static png_handle_result_code
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");
/* Length and position are checked by the caller. */
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);
/* Rely on png_set_IHDR to completely validate the data and call png_error if
* it's wrong.
*/
png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
color_type, interlace_type, compression_type, filter_type);
return handled_ok;
PNG_UNUSED(length)
}
/* Read and check the palette */
/* TODO: there are several obvious errors in this code when handling
* out-of-place chunks and there is much over-complexity caused by trying to
* patch up the problems.
*/
static png_handle_result_code
png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_const_charp errmsg = NULL;
png_debug(1, "in png_handle_PLTE");
/* 1.6.47: consistency. This used to be especially treated as a critical
* error even in an image which is not colour mapped, there isn't a good
* justification for treating some errors here one way and others another so
* everything uses the same logic.
*/
if ((png_ptr->mode & PNG_HAVE_PLTE) != 0)
errmsg = "duplicate";
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
errmsg = "out of place";
else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
errmsg = "ignored in grayscale PNG";
else if (length > 3*PNG_MAX_PALETTE_LENGTH || (length % 3) != 0)
errmsg = "invalid";
/* This drops PLTE in favour of tRNS or bKGD because both of those chunks
* can have an effect on the rendering of the image whereas PLTE only matters
* in the case of an 8-bit display with a decoder which controls the palette.
*
* The alternative here is to ignore the error and store the palette anyway;
* destroying the tRNS will definately cause problems.
*
* NOTE: the case of PNG_COLOR_TYPE_PALETTE need not be considered because
* the png_handle_ routines for the three 'after PLTE' chunks tRNS, bKGD and
* hIST all check for a preceding PLTE in these cases.
*/
else if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE &&
(png_has_chunk(png_ptr, tRNS) || png_has_chunk(png_ptr, bKGD)))
errmsg = "out of place";
else
{
/* 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.
*/
const unsigned max_palette_length =
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
1U << png_ptr->bit_depth : PNG_MAX_PALETTE_LENGTH;
/* The cast is safe because 'length' is less than
* 3*PNG_MAX_PALETTE_LENGTH
*/
const unsigned num = (length > 3U*max_palette_length) ?
max_palette_length : (unsigned)length / 3U;
unsigned i, j;
png_byte buf[3*PNG_MAX_PALETTE_LENGTH];
png_color palette[PNG_MAX_PALETTE_LENGTH];
/* Read the chunk into the buffer then read to the end of the chunk. */
png_crc_read(png_ptr, buf, num*3U);
png_crc_finish_critical(png_ptr, length - 3U*num,
/* Handle as ancillary if PLTE is optional: */
png_ptr->color_type != PNG_COLOR_TYPE_PALETTE);
for (i = 0U, j = 0U; i < num; i++)
{
palette[i].red = buf[j++];
palette[i].green = buf[j++];
palette[i].blue = buf[j++];
}
/* A valid PLTE chunk has been read */
png_ptr->mode |= PNG_HAVE_PLTE;
/* 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.
*
* REVIEW: there have been consistent bugs in the past about gamma and
* similar transforms to colour mapped images being useless because the
* modified palette cannot be accessed because of the above.
*
* CONSIDER: Fix this by not sharing the palette in this way. But does
* this completely fix the problem?
*/
png_set_PLTE(png_ptr, info_ptr, palette, num);
return handled_ok;
}
/* Here on error: errmsg is non NULL. */
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
png_crc_finish(png_ptr, length);
png_chunk_error(png_ptr, errmsg);
}
else /* not critical to this image */
{
png_crc_finish_critical(png_ptr, length, 1/*handle as ancillary*/);
png_chunk_benign_error(png_ptr, errmsg);
}
/* Because PNG_UNUSED(errmsg) does not work if all the uses are compiled out
* (this does happen).
*/
return errmsg != NULL ? handled_error : handled_error;
}
/* On read the IDAT chunk is always handled specially, even if marked for
* unknown handling (this is allowed), so:
*/
#define png_handle_IDAT NULL
static png_handle_result_code
png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_debug(1, "in png_handle_IEND");
png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
if (length != 0)
png_chunk_benign_error(png_ptr, "invalid");
png_crc_finish_critical(png_ptr, length, 1/*handle as ancillary*/);
return handled_ok;
PNG_UNUSED(info_ptr)
}
#ifdef PNG_READ_gAMA_SUPPORTED
static png_handle_result_code
png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_uint_32 ugamma;
png_byte buf[4];
png_debug(1, "in png_handle_gAMA");
png_crc_read(png_ptr, buf, 4);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
ugamma = png_get_uint_32(buf);
if (ugamma > PNG_UINT_31_MAX)
{
png_chunk_benign_error(png_ptr, "invalid");
return handled_error;
}
png_set_gAMA_fixed(png_ptr, info_ptr, (png_fixed_point)/*SAFE*/ugamma);
#ifdef PNG_READ_GAMMA_SUPPORTED
/* PNGv3: chunk precedence for gamma is cICP, [iCCP], sRGB, gAMA. gAMA is
* at the end of the chain so simply check for an unset value.
*/
if (png_ptr->chunk_gamma == 0)
png_ptr->chunk_gamma = (png_fixed_point)/*SAFE*/ugamma;
#endif /*READ_GAMMA*/
return handled_ok;
PNG_UNUSED(length)
}
#else
# define png_handle_gAMA NULL
#endif
#ifdef PNG_READ_sBIT_SUPPORTED
static png_handle_result_code /* 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->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)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "bad length");
return handled_error;
}
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 handled_error;
for (i=0; i<truelen; ++i)
{
if (buf[i] == 0 || buf[i] > sample_depth)
{
png_chunk_benign_error(png_ptr, "invalid");
return handled_error;
}
}
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 /* grayscale */
{
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));
return handled_ok;
}
#else
# define png_handle_sBIT NULL
#endif
#ifdef PNG_READ_cHRM_SUPPORTED
static png_int_32
png_get_int_32_checked(png_const_bytep buf, int *error)
{
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;
/* This version of png_get_int_32 has a way of returning the error to the
* caller, so:
*/
*error = 1;
return 0; /* Safe */
}
static png_handle_result_code /* PRIVATE */
png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
int error = 0;
png_xy xy;
png_byte buf[32];
png_debug(1, "in png_handle_cHRM");
png_crc_read(png_ptr, buf, 32);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
xy.whitex = png_get_int_32_checked(buf + 0, &error);
xy.whitey = png_get_int_32_checked(buf + 4, &error);
xy.redx = png_get_int_32_checked(buf + 8, &error);
xy.redy = png_get_int_32_checked(buf + 12, &error);
xy.greenx = png_get_int_32_checked(buf + 16, &error);
xy.greeny = png_get_int_32_checked(buf + 20, &error);
xy.bluex = png_get_int_32_checked(buf + 24, &error);
xy.bluey = png_get_int_32_checked(buf + 28, &error);
if (error)
{
png_chunk_benign_error(png_ptr, "invalid");
return handled_error;
}
/* png_set_cHRM may complain about some of the values but this doesn't matter
* because it was a cHRM and it did have vaguely (if, perhaps, ridiculous)
* values. Ridiculousity will be checked if the values are used later.
*/
png_set_cHRM_fixed(png_ptr, info_ptr, xy.whitex, xy.whitey, xy.redx, xy.redy,
xy.greenx, xy.greeny, xy.bluex, xy.bluey);
/* We only use 'chromaticities' for RGB to gray */
# ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
/* There is no need to check sRGB here, cICP is NYI and iCCP is not
* supported so just check mDCV.
*/
if (!png_has_chunk(png_ptr, mDCV))
{
png_ptr->chromaticities = xy;
}
# endif /* READ_RGB_TO_GRAY */
return handled_ok;
PNG_UNUSED(length)
}
#else
# define png_handle_cHRM NULL
#endif
#ifdef PNG_READ_sRGB_SUPPORTED
static png_handle_result_code /* 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");
png_crc_read(png_ptr, &intent, 1);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
/* This checks the range of the "rendering intent" because it is specified in
* the PNG spec itself; the "reserved" values will result in the chunk not
* being accepted, just as they do with the various "reserved" values in
* IHDR.
*/
if (intent > 3/*PNGv3 spec*/)
{
png_chunk_benign_error(png_ptr, "invalid");
return handled_error;
}
png_set_sRGB(png_ptr, info_ptr, intent);
/* NOTE: png_struct::chromaticities is not set here because the RGB to gray
* coefficients are known without a need for the chromaticities.
*/
#ifdef PNG_READ_GAMMA_SUPPORTED
/* PNGv3: chunk precedence for gamma is cICP, [iCCP], sRGB, gAMA. iCCP is
* not supported by libpng so the only requirement is to check for cICP
* setting the gamma (this is NYI, but this check is safe.)
*/
if (!png_has_chunk(png_ptr, cICP) || png_ptr->chunk_gamma == 0)
png_ptr->chunk_gamma = PNG_GAMMA_sRGB_INVERSE;
#endif /*READ_GAMMA*/
return handled_ok;
PNG_UNUSED(length)
}
#else
# define png_handle_sRGB NULL
#endif /* READ_sRGB */
#ifdef PNG_READ_iCCP_SUPPORTED
static png_handle_result_code /* 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");
/* PNGv3: allow PNG files with both sRGB and iCCP because the PNG spec only
* ever said that there "should" be only one, not "shall" and the PNGv3
* colour chunk precedence rules give a handling for this case anyway.
*/
{
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)/*SAFE*/length;
png_crc_read(png_ptr, (png_bytep)keyword, read_length);
length -= read_length;
if (length < LZ77Min)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too short");
return handled_error;
}
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, keyword, profile_length) !=
0)
{
/* The length is apparently ok, so we can check the 132
* byte header.
*/
if (png_icc_check_header(png_ptr, 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);
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,
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;
/* 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
errmsg = "out of memory";
}
/* else the profile remains in the read
* buffer which gets reused for subsequent
* chunks.
*/
if (errmsg == NULL)
{
png_ptr->zowner = 0;
return handled_ok;
}
}
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";
}
/* Failure: the reason is in 'errmsg' */
if (finished == 0)
png_crc_finish(png_ptr, length);
if (errmsg != NULL) /* else already output */
png_chunk_benign_error(png_ptr, errmsg);
return handled_error;
}
#else
# define png_handle_iCCP NULL
#endif /* READ_iCCP */
#ifdef PNG_READ_sPLT_SUPPORTED
static png_handle_result_code /* 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 handled_error;
}
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 handled_error;
}
}
#endif
buffer = png_read_buffer(png_ptr, length+1);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return handled_error;
}
/* 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 handled_error;
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 handled_error;
}
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 handled_error;
}
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 handled_error;
}
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 handled_error;
}
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;
}
/* 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);
return handled_ok;
}
#else
# define png_handle_sPLT NULL
#endif /* READ_sPLT */
#ifdef PNG_READ_tRNS_SUPPORTED
static png_handle_result_code /* 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->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 handled_error;
}
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 handled_error;
}
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)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return handled_error;
}
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 handled_error;
}
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 handled_error;
}
if (png_crc_finish(png_ptr, 0) != 0)
{
png_ptr->num_trans = 0;
return handled_error;
}
/* 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));
return handled_ok;
}
#else
# define png_handle_tRNS NULL
#endif
#ifdef PNG_READ_bKGD_SUPPORTED
static png_handle_result_code /* 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->color_type == PNG_COLOR_TYPE_PALETTE)
{
if ((png_ptr->mode & PNG_HAVE_PLTE) == 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place");
return handled_error;
}
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 handled_error;
}
png_crc_read(png_ptr, buf, truelen);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
/* 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 handled_error;
}
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 handled_error;
}
}
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 handled_error;
}
}
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);
return handled_ok;
}
#else
# define png_handle_bKGD NULL
#endif
#ifdef PNG_READ_cICP_SUPPORTED
static png_handle_result_code /* PRIVATE */
png_handle_cICP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_byte buf[4];
png_debug(1, "in png_handle_cICP");
png_crc_read(png_ptr, buf, 4);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
png_set_cICP(png_ptr, info_ptr, buf[0], buf[1], buf[2], buf[3]);
/* We only use 'chromaticities' for RGB to gray */
# ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
if (!png_has_chunk(png_ptr, mDCV))
{
/* TODO: png_ptr->chromaticities = chromaticities; */
}
# endif /* READ_RGB_TO_GRAY */
#ifdef PNG_READ_GAMMA_SUPPORTED
/* PNGv3: chunk precedence for gamma is cICP, [iCCP], sRGB, gAMA. cICP is
* at the head so simply set the gamma if it can be determined. If not
* chunk_gamma remains unchanged; sRGB and gAMA handling check it for
* being zero.
*/
/* TODO: set png_struct::chunk_gamma when possible */
#endif /*READ_GAMMA*/
return handled_ok;
PNG_UNUSED(length)
}
#else
# define png_handle_cICP NULL
#endif
#ifdef PNG_READ_cLLI_SUPPORTED
static png_handle_result_code /* PRIVATE */
png_handle_cLLI(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_byte buf[8];
png_debug(1, "in png_handle_cLLI");
png_crc_read(png_ptr, buf, 8);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
/* The error checking happens here, this puts it in just one place: */
png_set_cLLI_fixed(png_ptr, info_ptr, png_get_uint_32(buf),
png_get_uint_32(buf+4));
return handled_ok;
PNG_UNUSED(length)
}
#else
# define png_handle_cLLI NULL
#endif
#ifdef PNG_READ_mDCV_SUPPORTED
static png_handle_result_code /* PRIVATE */
png_handle_mDCV(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_xy chromaticities;
png_byte buf[24];
png_debug(1, "in png_handle_mDCV");
png_crc_read(png_ptr, buf, 24);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
/* The error checking happens here, this puts it in just one place. The
* odd /50000 scaling factor makes it more difficult but the (x.y) values are
* only two bytes so a <<1 is safe.
*
* WARNING: the PNG specification defines the cHRM chunk to **start** with
* the white point (x,y). The W3C PNG v3 specification puts the white point
* **after* R,G,B. The x,y values in mDCV are also scaled by 50,000 and
* stored in just two bytes, whereas those in cHRM are scaled by 100,000 and
* stored in four bytes. This is very, very confusing. These APIs remove
* the confusion by copying the existing, well established, API.
*/
chromaticities.redx = png_get_uint_16(buf+ 0U) << 1; /* red x */
chromaticities.redy = png_get_uint_16(buf+ 2U) << 1; /* red y */
chromaticities.greenx = png_get_uint_16(buf+ 4U) << 1; /* green x */
chromaticities.greeny = png_get_uint_16(buf+ 6U) << 1; /* green y */
chromaticities.bluex = png_get_uint_16(buf+ 8U) << 1; /* blue x */
chromaticities.bluey = png_get_uint_16(buf+10U) << 1; /* blue y */
chromaticities.whitex = png_get_uint_16(buf+12U) << 1; /* white x */
chromaticities.whitey = png_get_uint_16(buf+14U) << 1; /* white y */
png_set_mDCV_fixed(png_ptr, info_ptr,
chromaticities.whitex, chromaticities.whitey,
chromaticities.redx, chromaticities.redy,
chromaticities.greenx, chromaticities.greeny,
chromaticities.bluex, chromaticities.bluey,
png_get_uint_32(buf+16U), /* peak luminance */
png_get_uint_32(buf+20U));/* minimum perceivable luminance */
/* We only use 'chromaticities' for RGB to gray */
# ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
png_ptr->chromaticities = chromaticities;
# endif /* READ_RGB_TO_GRAY */
return handled_ok;
PNG_UNUSED(length)
}
#else
# define png_handle_mDCV NULL
#endif
#ifdef PNG_READ_eXIf_SUPPORTED
static png_handle_result_code /* PRIVATE */
png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_bytep buffer = NULL;
png_debug(1, "in png_handle_eXIf");
buffer = png_read_buffer(png_ptr, length);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return handled_error;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
/* PNGv3: the code used to check the byte order mark at the start for MM or
* II, however PNGv3 states that the the first 4 bytes should be checked.
* The caller ensures that there are four bytes available.
*/
{
png_uint_32 header = png_get_uint_32(buffer);
/* These numbers are copied from the PNGv3 spec: */
if (header != 0x49492A00 && header != 0x4D4D002A)
{
png_chunk_benign_error(png_ptr, "invalid");
return handled_error;
}
}
png_set_eXIf_1(png_ptr, info_ptr, length, buffer);
return handled_ok;
}
#else
# define png_handle_eXIf NULL
#endif
#ifdef PNG_READ_hIST_SUPPORTED
static png_handle_result_code /* 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");
/* This cast is safe because the chunk definition limits the length to a
* maximum of 1024 bytes.
*
* TODO: maybe use png_uint_32 anyway, not unsigned int, to reduce the
* casts.
*/
num = (unsigned int)length / 2 ;
if (length != num * 2 ||
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 handled_error;
}
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 handled_error;
png_set_hIST(png_ptr, info_ptr, readbuf);
return handled_ok;
}
#else
# define png_handle_hIST NULL
#endif
#ifdef PNG_READ_pHYs_SUPPORTED
static png_handle_result_code /* 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");
png_crc_read(png_ptr, buf, 9);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
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);
return handled_ok;
PNG_UNUSED(length)
}
#else
# define png_handle_pHYs NULL
#endif
#ifdef PNG_READ_oFFs_SUPPORTED
static png_handle_result_code /* 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");
png_crc_read(png_ptr, buf, 9);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
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);
return handled_ok;
PNG_UNUSED(length)
}
#else
# define png_handle_oFFs NULL
#endif
#ifdef PNG_READ_pCAL_SUPPORTED
/* Read the pCAL chunk (described in the PNG Extensions document) */
static png_handle_result_code /* 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");
png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
length + 1);
buffer = png_read_buffer(png_ptr, length+1);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return handled_error;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
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 handled_error;
}
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 handled_error;
}
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 handled_error;
}
/* 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 handled_error;
}
}
png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
(png_charp)units, params);
/* TODO: BUG: png_set_pCAL calls png_chunk_report which, in this case, calls
* png_benign_error and that can error out.
*
* png_read_buffer needs to be allocated with space for both nparams and the
* parameter strings. Not hard to do.
*/
png_free(png_ptr, params);
return handled_ok;
}
#else
# define png_handle_pCAL NULL
#endif
#ifdef PNG_READ_sCAL_SUPPORTED
/* Read the sCAL chunk */
static png_handle_result_code /* 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");
png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
length + 1);
buffer = png_read_buffer(png_ptr, length+1);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return handled_error;
}
png_crc_read(png_ptr, buffer, length);
buffer[length] = 0; /* Null terminate the last string */
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
/* Validate the unit. */
if (buffer[0] != 1 && buffer[0] != 2)
{
png_chunk_benign_error(png_ptr, "invalid unit");
return handled_error;
}
/* 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);
return handled_ok;
}
}
return handled_error;
}
#else
# define png_handle_sCAL NULL
#endif
#ifdef PNG_READ_tIME_SUPPORTED
static png_handle_result_code /* 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");
/* TODO: what is this doing here? It should be happened in pngread.c and
* pngpread.c, although it could be moved to png_handle_chunk below and
* thereby avoid some code duplication.
*/
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
png_ptr->mode |= PNG_AFTER_IDAT;
png_crc_read(png_ptr, buf, 7);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
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);
return handled_ok;
PNG_UNUSED(length)
}
#else
# define png_handle_tIME NULL
#endif
#ifdef PNG_READ_tEXt_SUPPORTED
/* Note: this does not properly handle chunks that are > 64K under DOS */
static png_handle_result_code /* 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 handled_error;
}
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 handled_error;
}
}
#endif
/* TODO: this doesn't work and shouldn't be necessary. */
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
png_ptr->mode |= PNG_AFTER_IDAT;
buffer = png_read_buffer(png_ptr, length+1);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return handled_error;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, skip) != 0)
return handled_error;
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)
return handled_ok;
png_chunk_benign_error(png_ptr, "out of memory");
return handled_error;
}
#else
# define png_handle_tEXt NULL
#endif
#ifdef PNG_READ_zTXt_SUPPORTED
/* Note: this does not correctly handle chunks that are > 64K under DOS */
static png_handle_result_code /* 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 handled_error;
}
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 handled_error;
}
}
#endif
/* TODO: should not be necessary. */
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. The limit check in png_handle_chunk should be
* sufficient.
*/
buffer = png_read_buffer(png_ptr, length);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return handled_error;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
/* 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)
return handled_ok;
errmsg = "out of memory";
}
}
else
errmsg = png_ptr->zstream.msg;
}
png_chunk_benign_error(png_ptr, errmsg);
return handled_error;
}
#else
# define png_handle_zTXt NULL
#endif
#ifdef PNG_READ_iTXt_SUPPORTED
/* Note: this does not correctly handle chunks that are > 64K under DOS */
static png_handle_result_code /* 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 handled_error;
}
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 handled_error;
}
}
#endif
/* TODO: should not be necessary. */
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
png_ptr->mode |= PNG_AFTER_IDAT;
buffer = png_read_buffer(png_ptr, length+1);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return handled_error;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0) != 0)
return handled_error;
/* 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)
return handled_ok;
errmsg = "out of memory";
}
}
else
errmsg = "bad compression info";
if (errmsg != NULL)
png_chunk_benign_error(png_ptr, errmsg);
return handled_error;
}
#else
# define png_handle_iTXt NULL
#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)
{
const png_alloc_size_t limit = png_chunk_max(png_ptr);
if (png_ptr->unknown_chunk.data != NULL)
{
png_free(png_ptr, png_ptr->unknown_chunk.data);
png_ptr->unknown_chunk.data = NULL;
}
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 */
png_handle_result_code /*PRIVATE*/
png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
png_uint_32 length, int keep)
{
png_handle_result_code handled = handled_discarded; /* the default */
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) /* handled_error */
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 = handled_ok;
/* 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 = handled_saved;
# 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 < handled_saved && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
png_chunk_error(png_ptr, "unhandled critical chunk");
return handled;
}
/* APNG handling: the minimal implementation of APNG handling in libpng 1.6
* requires that those significant applications which already handle APNG not
* get hosed. To do this ensure the code here will have to ensure than APNG
* data by default (at least in 1.6) gets stored in the unknown chunk list.
* Maybe this can be relaxed in a few years but at present it's just the only
* safe way.
*
* ATM just cause unknown handling for all three chunks:
*/
#define png_handle_acTL NULL
#define png_handle_fcTL NULL
#define png_handle_fdAT NULL
/*
* 1.6.47: This is the new table driven interface to all the chunk handling.
*
* The table describes the PNG standard rules for **reading** known chunks -
* every chunk which has an entry in PNG_KNOWN_CHUNKS. The table contains an
* entry for each PNG_INDEX_cHNK describing the rules.
*
* In this initial version the only information in the entry is the
* png_handle_cHNK function for the chunk in question. When chunk support is
* compiled out the entry will be NULL.
*/
static const struct
{
png_handle_result_code (*handler)(
png_structrp, png_inforp, png_uint_32 length);
/* A chunk-specific 'handler', NULL if the chunk is not supported in this
* build.
*/
/* Crushing these values helps on modern 32-bit architectures because the
* pointer and the following bit fields both end up requiring 32 bits.
* Typically this will halve the table size. On 64-bit architectures the
* table entries will typically be 8 bytes.
*/
png_uint_32 max_length :12; /* Length min, max in bytes */
png_uint_32 min_length :8;
/* Length errors on critical chunks have special handling to preserve the
* existing behaviour in libpng 1.6. Anciallary chunks are checked below
* and produce a 'benign' error.
*/
png_uint_32 pos_before :4; /* PNG_HAVE_ values chunk must precede */
png_uint_32 pos_after :4; /* PNG_HAVE_ values chunk must follow */
/* NOTE: PLTE, tRNS and bKGD require special handling which depends on
* the colour type of the base image.
*/
png_uint_32 multiple :1; /* Multiple occurences permitted */
/* This is enabled for PLTE because PLTE may, in practice, be optional */
}
read_chunks[PNG_INDEX_unknown] =
{
/* Definitions as above but done indirectly by #define so that
* PNG_KNOWN_CHUNKS can be used safely to build the table in order.
*
* Each CDcHNK definition lists the values for the parameters **after**
* the first, 'handler', function. 'handler' is NULL when the chunk has no
* compiled in support.
*/
# define NoCheck 0x801U /* Do not check the maximum length */
# define Limit 0x802U /* Limit to png_chunk_max bytes */
# define LKMin 3U+LZ77Min /* Minimum length of keyword+LZ77 */
#define hIHDR PNG_HAVE_IHDR
#define hPLTE PNG_HAVE_PLTE
#define hIDAT PNG_HAVE_IDAT
/* For the two chunks, tRNS and bKGD which can occur in PNGs without a PLTE
* but must occur after the PLTE use this and put the check in the handler
* routine for colour mapped images were PLTE is required. Also put a check
* in PLTE for other image types to drop the PLTE if tRNS or bKGD have been
* seen.
*/
#define hCOL (PNG_HAVE_PLTE|PNG_HAVE_IDAT)
/* Used for the decoding chunks which must be before PLTE. */
#define aIDAT PNG_AFTER_IDAT
/* Chunks from W3C PNG v3: */
/* cHNK max_len, min, before, after, multiple */
# define CDIHDR 13U, 13U, hIHDR, 0, 0
# define CDPLTE NoCheck, 0U, 0, hIHDR, 1
/* PLTE errors are only critical for colour-map images, consequently the
* hander does all the checks.
*/
# define CDIDAT NoCheck, 0U, aIDAT, hIHDR, 1
# define CDIEND NoCheck, 0U, 0, aIDAT, 0
/* Historically data was allowed in IEND */
# define CDtRNS 256U, 0U, hIDAT, hIHDR, 0
# define CDcHRM 32U, 32U, hCOL, hIHDR, 0
# define CDgAMA 4U, 4U, hCOL, hIHDR, 0
# define CDiCCP NoCheck, LKMin, hCOL, hIHDR, 0
# define CDsBIT 4U, 1U, hCOL, hIHDR, 0
# define CDsRGB 1U, 1U, hCOL, hIHDR, 0
# define CDcICP 4U, 4U, hCOL, hIHDR, 0
# define CDmDCV 24U, 24U, hCOL, hIHDR, 0
# define CDeXIf Limit, 4U, 0, hIHDR, 0
# define CDcLLI 8U, 8U, hCOL, hIHDR, 0
# define CDtEXt NoCheck, 2U, 0, hIHDR, 1
/* Allocates 'length+1'; checked in the handler */
# define CDzTXt Limit, LKMin, 0, hIHDR, 1
# define CDiTXt NoCheck, 6U, 0, hIHDR, 1
/* Allocates 'length+1'; checked in the handler */
# define CDbKGD 6U, 1U, hIDAT, hIHDR, 0
# define CDhIST 1024U, 0U, hPLTE, hIHDR, 0
# define CDpHYs 9U, 9U, hIDAT, hIHDR, 0
# define CDsPLT NoCheck, 3U, hIDAT, hIHDR, 1
/* Allocates 'length+1'; checked in the handler */
# define CDtIME 7U, 7U, 0, hIHDR, 0
# define CDacTL 8U, 8U, hIDAT, hIHDR, 0
# define CDfcTL 25U, 26U, 0, hIHDR, 1
# define CDfdAT Limit, 4U, hIDAT, hIHDR, 1
/* Supported chunks from PNG extensions 1.5.0, NYI so limit */
# define CDoFFs 9U, 9U, hIDAT, hIHDR, 0
# define CDpCAL NoCheck, 14U, hIDAT, hIHDR, 0
/* Allocates 'length+1'; checked in the handler */
# define CDsCAL Limit, 4U, hIDAT, hIHDR, 0
/* Allocates 'length+1'; checked in the handler */
# define PNG_CHUNK(cHNK, index) { png_handle_ ## cHNK, CD ## cHNK },
PNG_KNOWN_CHUNKS
# undef PNG_CHUNK
};
static png_index
png_chunk_index_from_name(png_uint_32 chunk_name)
{
/* For chunk png_cHNK return PNG_INDEX_cHNK. Return PNG_INDEX_unknown if
* chunk_name is not known. Notice that in a particular build "known" does
* not necessarily mean "supported", although the inverse applies.
*/
switch (chunk_name)
{
# define PNG_CHUNK(cHNK, index)\
case png_ ## cHNK: return PNG_INDEX_ ## cHNK; /* == index */
PNG_KNOWN_CHUNKS
# undef PNG_CHUNK
default: return PNG_INDEX_unknown;
}
}
png_handle_result_code /*PRIVATE*/
png_handle_chunk(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
/* CSE: these things don't change, these autos are just to save typing and
* make the code more clear.
*/
const png_uint_32 chunk_name = png_ptr->chunk_name;
const png_index chunk_index = png_chunk_index_from_name(chunk_name);
png_handle_result_code handled = handled_error;
png_const_charp errmsg = NULL;
/* Is this a known chunk? If not there are no checks performed here;
* png_handle_unknown does the correct checks. This means that the values
* for known but unsupported chunks in the above table are not used here
* however the chunks_seen fields in png_struct are still set.
*/
if (chunk_index == PNG_INDEX_unknown ||
read_chunks[chunk_index].handler == NULL)
{
handled = png_handle_unknown(
png_ptr, info_ptr, length, PNG_HANDLE_CHUNK_AS_DEFAULT);
}
/* First check the position. The first check is historical; the stream must
* start with IHDR and anything else causes libpng to give up immediately.
*/
else if (chunk_index != PNG_INDEX_IHDR &&
(png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR"); /* NORETURN */
/* Before all the pos_before chunks, after all the pos_after chunks. */
else if (((png_ptr->mode & read_chunks[chunk_index].pos_before) != 0) ||
((png_ptr->mode & read_chunks[chunk_index].pos_after) !=
read_chunks[chunk_index].pos_after))
{
errmsg = "out of place";
}
/* Now check for duplicates: duplicated critical chunks also produce a
* full error.
*/
else if (read_chunks[chunk_index].multiple == 0 &&
png_file_has_chunk(png_ptr, chunk_index))
{
errmsg = "duplicate";
}
else if (length < read_chunks[chunk_index].min_length)
errmsg = "too short";
else
{
/* NOTE: apart from IHDR the critical chunks (PLTE, IDAT and IEND) are set
* up above not to do any length checks.
*
* The png_chunk_max check ensures that the variable length chunks are
* always checked at this point for being within the system allocation
* limits.
*/
unsigned max_length = read_chunks[chunk_index].max_length;
switch (max_length)
{
case Limit:
/* png_read_chunk_header has already png_error'ed chunks with a
* length exceeding the 31-bit PNG limit, so just check the memory
* limit:
*/
if (length <= png_chunk_max(png_ptr))
goto MeetsLimit;
errmsg = "length exceeds libpng limit";
break;
default:
if (length <= max_length)
goto MeetsLimit;
errmsg = "too long";
break;
case NoCheck:
MeetsLimit:
handled = read_chunks[chunk_index].handler(
png_ptr, info_ptr, length);
break;
}
}
/* If there was an error or the chunk was simply skipped it is not counted as
* 'seen'.
*/
if (errmsg != NULL)
{
if (PNG_CHUNK_CRITICAL(chunk_name)) /* stop immediately */
png_chunk_error(png_ptr, errmsg);
else /* ancillary chunk */
{
/* The chunk data is skipped: */
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, errmsg);
}
}
else if (handled >= handled_saved)
{
if (chunk_index != PNG_INDEX_unknown)
png_file_add_chunk(png_ptr, chunk_index);
}
return handled;
}
/* Combines the row recently read in with the existing pixels in the row. This
* routine takes care of alpha and transparency if requested. This routine also
* handles the two methods of progressive display of interlaced images,
* depending on the 'display' value; if 'display' is true then the whole row
* (dp) is filled from the start by replicating the available pixels. If
* 'display' is false only those pixels present in the pass are filled in.
*/
void /* PRIVATE */
png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
{
unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
png_const_bytep sp = png_ptr->row_buf + 1;
png_alloc_size_t row_width = png_ptr->width;
unsigned int pass = png_ptr->pass;
png_bytep end_ptr = 0;
png_byte end_byte = 0;
unsigned int end_mask;
png_debug(1, "in png_combine_row");
/* Added in 1.5.6: it should not be possible to enter this routine until at
* least one row has been read from the PNG data and transformed.
*/
if (pixel_depth == 0)
png_error(png_ptr, "internal row logic error");
/* Added in 1.5.4: the pixel depth should match the information returned by
* any call to png_read_update_info at this point. Do not continue if we got
* this wrong.
*/
if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
PNG_ROWBYTES(pixel_depth, row_width))
png_error(png_ptr, "internal row size calculation error");
/* Don't expect this to ever happen: */
if (row_width == 0)
png_error(png_ptr, "internal row width error");
/* Preserve the last byte in cases where only part of it will be overwritten,
* the multiply below may overflow, we don't care because ANSI-C guarantees
* we get the low bits.
*/
end_mask = (pixel_depth * row_width) & 7;
if (end_mask != 0)
{
/* end_ptr == NULL is a flag to say do nothing */
end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
end_byte = *end_ptr;
# ifdef PNG_READ_PACKSWAP_SUPPORTED
if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
/* little-endian byte */
end_mask = (unsigned int)(0xff << end_mask);
else /* big-endian byte */
# endif
end_mask = 0xff >> end_mask;
/* end_mask is now the bits to *keep* from the destination row */
}
/* For non-interlaced images this reduces to a memcpy(). A memcpy()
* will also happen if interlacing isn't supported or if the application
* does not call png_set_interlace_handling(). In the latter cases the
* caller just gets a sequence of the unexpanded rows from each interlace
* pass.
*/
#ifdef PNG_READ_INTERLACING_SUPPORTED
if (png_ptr->interlaced != 0 &&
(png_ptr->transformations & PNG_INTERLACE) != 0 &&
pass < 6 && (display == 0 ||
/* The following copies everything for 'display' on passes 0, 2 and 4. */
(display == 1 && (pass & 1) != 0)))
{
/* Narrow images may have no bits in a pass; the caller should handle
* this, but this test is cheap:
*/
if (row_width <= PNG_PASS_START_COL(pass))
return;
if (pixel_depth < 8)
{
/* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
* into 32 bits, then a single loop over the bytes using the four byte
* values in the 32-bit mask can be used. For the 'display' option the
* expanded mask may also not require any masking within a byte. To
* make this work the PACKSWAP option must be taken into account - it
* simply requires the pixels to be reversed in each byte.
*
* The 'regular' case requires a mask for each of the first 6 passes,
* the 'display' case does a copy for the even passes in the range
* 0..6. This has already been handled in the test above.
*
* The masks are arranged as four bytes with the first byte to use in
* the lowest bits (little-endian) regardless of the order (PACKSWAP or
* not) of the pixels in each byte.
*
* NOTE: the whole of this logic depends on the caller of this function
* only calling it on rows appropriate to the pass. This function only
* understands the 'x' logic; the 'y' logic is handled by the caller.
*
* The following defines allow generation of compile time constant bit
* masks for each pixel depth and each possibility of swapped or not
* swapped bytes. Pass 'p' is in the range 0..6; 'x', a pixel index,
* is in the range 0..7; and the result is 1 if the pixel is to be
* copied in the pass, 0 if not. 'S' is for the sparkle method, 'B'
* for the block method.
*
* With some compilers a compile time expression of the general form:
*
* (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
*
* Produces warnings with values of 'shift' in the range 33 to 63
* because the right hand side of the ?: expression is evaluated by
* the compiler even though it isn't used. Microsoft Visual C (various
* versions) and the Intel C compiler are known to do this. To avoid
* this the following macros are used in 1.5.6. This is a temporary
* solution to avoid destabilizing the code during the release process.
*/
# if PNG_USE_COMPILE_TIME_MASKS
# define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
# define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
# else
# define PNG_LSR(x,s) ((x)>>(s))
# define PNG_LSL(x,s) ((x)<<(s))
# endif
# define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
# define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
/* Return a mask for pass 'p' pixel 'x' at depth 'd'. The mask is
* little endian - the first pixel is at bit 0 - however the extra
* parameter 's' can be set to cause the mask position to be swapped
* within each byte, to match the PNG format. This is done by XOR of
* the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
*/
# define PIXEL_MASK(p,x,d,s) \
(PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
/* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
*/
# define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
# define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
/* Combine 8 of these to get the full mask. For the 1-bpp and 2-bpp
* cases the result needs replicating, for the 4-bpp case the above
* generates a full 32 bits.
*/
# define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
# define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
# define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
#if PNG_USE_COMPILE_TIME_MASKS
/* Utility macros to construct all the masks for a depth/swap
* combination. The 's' parameter says whether the format is PNG
* (big endian bytes) or not. Only the three odd-numbered passes are
* required for the display/block algorithm.
*/
# define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
# define B_MASKS(d,s) { B_MASK(1,d,s), B_MASK(3,d,s), B_MASK(5,d,s) }
# define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
/* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
* then pass:
*/
static const png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
{
/* Little-endian byte masks for PACKSWAP */
{ S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
/* Normal (big-endian byte) masks - PNG format */
{ S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
};
/* display_mask has only three entries for the odd passes, so index by
* pass>>1.
*/
static const png_uint_32 display_mask[2][3][3] =
{
/* Little-endian byte masks for PACKSWAP */
{ B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
/* Normal (big-endian byte) masks - PNG format */
{ B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
};
# define MASK(pass,depth,display,png)\
((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
row_mask[png][DEPTH_INDEX(depth)][pass])
#else /* !PNG_USE_COMPILE_TIME_MASKS */
/* This is the runtime alternative: it seems unlikely that this will
* ever be either smaller or faster than the compile time approach.
*/
# define MASK(pass,depth,display,png)\
((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
#endif /* !USE_COMPILE_TIME_MASKS */
/* Use the appropriate mask to copy the required bits. In some cases
* the byte mask will be 0 or 0xff; optimize these cases. row_width is
* the number of pixels, but the code copies bytes, so it is necessary
* to special case the end.
*/
png_uint_32 pixels_per_byte = 8 / pixel_depth;
png_uint_32 mask;
# ifdef PNG_READ_PACKSWAP_SUPPORTED
if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
mask = MASK(pass, pixel_depth, display, 0);
else
# endif
mask = MASK(pass, pixel_depth, display, 1);
for (;;)
{
png_uint_32 m;
/* It doesn't matter in the following if png_uint_32 has more than
* 32 bits because the high bits always match those in m<<24; it is,
* however, essential to use OR here, not +, because of this.
*/
m = mask;
mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
m &= 0xff;
if (m != 0) /* something to copy */
{
if (m != 0xff)
*dp = (png_byte)((*dp & ~m) | (*sp & m));
else
*dp = *sp;
}
/* NOTE: this may overwrite the last byte with garbage if the image
* is not an exact number of bytes wide; libpng has always done
* this.
*/
if (row_width <= pixels_per_byte)
break; /* May need to restore part of the last byte */
row_width -= pixels_per_byte;
++dp;
++sp;
}
}
else /* pixel_depth >= 8 */
{
unsigned int bytes_to_copy, bytes_to_jump;
/* Validate the depth - it must be a multiple of 8 */
if (pixel_depth & 7)
png_error(png_ptr, "invalid user transform pixel depth");
pixel_depth >>= 3; /* now in bytes */
row_width *= pixel_depth;
/* Regardless of pass number the Adam 7 interlace always results in a
* fixed number of pixels to copy then to skip. There may be a
* different number of pixels to skip at the start though.
*/
{
unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
row_width -= offset;
dp += offset;
sp += offset;
}
/* Work out the bytes to copy. */
if (display != 0)
{
/* When doing the 'block' algorithm the pixel in the pass gets
* replicated to adjacent pixels. This is why the even (0,2,4,6)
* passes are skipped above - the entire expanded row is copied.
*/
bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
/* But don't allow this number to exceed the actual row width. */
if (bytes_to_copy > row_width)
bytes_to_copy = (unsigned int)/*SAFE*/row_width;
}
else /* normal row; Adam7 only ever gives us one pixel to copy. */
bytes_to_copy = pixel_depth;
/* In Adam7 there is a constant offset between where the pixels go. */
bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
/* And simply copy these bytes. Some optimization is possible here,
* depending on the value of 'bytes_to_copy'. Special case the low
* byte counts, which we know to be frequent.
*
* Notice that these cases all 'return' rather than 'break' - this
* avoids an unnecessary test on whether to restore the last byte
* below.
*/
switch (bytes_to_copy)
{
case 1:
for (;;)
{
*dp = *sp;
if (row_width <= bytes_to_jump)
return;
dp += bytes_to_jump;
sp += bytes_to_jump;
row_width -= bytes_to_jump;
}
case 2:
/* There is a possibility of a partial copy at the end here; this
* slows the code down somewhat.
*/
do
{
dp[0] = sp[0]; dp[1] = sp[1];
if (row_width <= bytes_to_jump)
return;
sp += bytes_to_jump;
dp += bytes_to_jump;
row_width -= bytes_to_jump;
}
while (row_width > 1);
/* And there can only be one byte left at this point: */
*dp = *sp;
return;
case 3:
/* This can only be the RGB case, so each copy is exactly one
* pixel and it is not necessary to check for a partial copy.
*/
for (;;)
{
dp[0] = sp[0]; dp[1] = sp[1]; dp[2] = sp[2];
if (row_width <= bytes_to_jump)
return;
sp += bytes_to_jump;
dp += bytes_to_jump;
row_width -= bytes_to_jump;
}
default:
#if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
/* Check for double byte alignment and, if possible, use a
* 16-bit copy. Don't attempt this for narrow images - ones that
* are less than an interlace panel wide. Don't attempt it for
* wide bytes_to_copy either - use the memcpy there.
*/
if (bytes_to_copy < 16 /*else use memcpy*/ &&
png_isaligned(dp, png_uint_16) &&
png_isaligned(sp, png_uint_16) &&
bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
bytes_to_jump % (sizeof (png_uint_16)) == 0)
{
/* Everything is aligned for png_uint_16 copies, but try for
* png_uint_32 first.
*/
if (png_isaligned(dp, png_uint_32) &&
png_isaligned(sp, png_uint_32) &&
bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
bytes_to_jump % (sizeof (png_uint_32)) == 0)
{
png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
png_const_uint_32p sp32 = png_aligncastconst(
png_const_uint_32p, sp);
size_t skip = (bytes_to_jump-bytes_to_copy) /
(sizeof (png_uint_32));
do
{
size_t c = bytes_to_copy;
do
{
*dp32++ = *sp32++;
c -= (sizeof (png_uint_32));
}
while (c > 0);
if (row_width <= bytes_to_jump)
return;
dp32 += skip;
sp32 += skip;
row_width -= bytes_to_jump;
}
while (bytes_to_copy <= row_width);
/* Get to here when the row_width truncates the final copy.
* There will be 1-3 bytes left to copy, so don't try the
* 16-bit loop below.
*/
dp = (png_bytep)dp32;
sp = (png_const_bytep)sp32;
do
*dp++ = *sp++;
while (--row_width > 0);
return;
}
/* Else do it in 16-bit quantities, but only if the size is
* not too large.
*/
else
{
png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
png_const_uint_16p sp16 = png_aligncastconst(
png_const_uint_16p, sp);
size_t skip = (bytes_to_jump-bytes_to_copy) /
(sizeof (png_uint_16));
do
{
size_t c = bytes_to_copy;
do
{
*dp16++ = *sp16++;
c -= (sizeof (png_uint_16));
}
while (c > 0);
if (row_width <= bytes_to_jump)
return;
dp16 += skip;
sp16 += skip;
row_width -= bytes_to_jump;
}
while (bytes_to_copy <= row_width);
/* End of row - 1 byte left, bytes_to_copy > row_width: */
dp = (png_bytep)dp16;
sp = (png_const_bytep)sp16;
do
*dp++ = *sp++;
while (--row_width > 0);
return;
}
}
#endif /* ALIGN_TYPE code */
/* The true default - use a memcpy: */
for (;;)
{
memcpy(dp, sp, bytes_to_copy);
if (row_width <= bytes_to_jump)
return;
sp += bytes_to_jump;
dp += bytes_to_jump;
row_width -= bytes_to_jump;
if (bytes_to_copy > row_width)
bytes_to_copy = (unsigned int)/*SAFE*/row_width;
}
}
/* NOT REACHED*/
} /* pixel_depth >= 8 */
/* Here if pixel_depth < 8 to check 'end_ptr' below. */
}
else
#endif /* READ_INTERLACING */
/* If here then the switch above wasn't used so just memcpy the whole row
* from the temporary row buffer (notice that this overwrites the end of the
* destination row if it is a partial byte.)
*/
memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
/* Restore the overwritten bits from the last byte if necessary. */
if (end_ptr != NULL)
*end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
}
#ifdef PNG_READ_INTERLACING_SUPPORTED
void /* PRIVATE */
png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
png_uint_32 transformations /* Because these may affect the byte layout */)
{
png_debug(1, "in png_do_read_interlace");
if (row != NULL && row_info != NULL)
{
png_uint_32 final_width;
final_width = row_info->width * png_pass_inc[pass];
switch (row_info->pixel_depth)
{
case 1:
{
png_bytep sp = row + (size_t)((row_info->width - 1) >> 3);
png_bytep dp = row + (size_t)((final_width - 1) >> 3);
unsigned int sshift, dshift;
unsigned int s_start, s_end;
int s_inc;
int jstop = (int)png_pass_inc[pass];
png_byte v;
png_uint_32 i;
int j;
#ifdef PNG_READ_PACKSWAP_SUPPORTED
if ((transformations & PNG_PACKSWAP) != 0)
{
sshift = ((row_info->width + 7) & 0x07);
dshift = ((final_width + 7) & 0x07);
s_start = 7;
s_end = 0;
s_inc = -1;
}
else
#endif
{
sshift = 7 - ((row_info->width + 7) & 0x07);
dshift = 7 - ((final_width + 7) & 0x07);
s_start = 0;
s_end = 7;
s_inc = 1;
}
for (i = 0; i < row_info->width; i++)
{
v = (png_byte)((*sp >> sshift) & 0x01);
for (j = 0; j < jstop; j++)
{
unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
tmp |= (unsigned int)(v << dshift);
*dp = (png_byte)(tmp & 0xff);
if (dshift == s_end)
{
dshift = s_start;
dp--;
}
else
dshift = (unsigned int)((int)dshift + s_inc);
}
if (sshift == s_end)
{
sshift = s_start;
sp--;
}
else
sshift = (unsigned int)((int)sshift + s_inc);
}
break;
}
case 2:
{
png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
unsigned int sshift, dshift;
unsigned int s_start, s_end;
int s_inc;
int jstop = (int)png_pass_inc[pass];
png_uint_32 i;
#ifdef PNG_READ_PACKSWAP_SUPPORTED
if ((transformations & PNG_PACKSWAP) != 0)
{
sshift = (((row_info->width + 3) & 0x03) << 1);
dshift = (((final_width + 3) & 0x03) << 1);
s_start = 6;
s_end = 0;
s_inc = -2;
}
else
#endif
{
sshift = ((3 - ((row_info->width + 3) & 0x03)) << 1);
dshift = ((3 - ((final_width + 3) & 0x03)) << 1);
s_start = 0;
s_end = 6;
s_inc = 2;
}
for (i = 0; i < row_info->width; i++)
{
png_byte v;
int j;
v = (png_byte)((*sp >> sshift) & 0x03);
for (j = 0; j < jstop; j++)
{
unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
tmp |= (unsigned int)(v << dshift);
*dp = (png_byte)(tmp & 0xff);
if (dshift == s_end)
{
dshift = s_start;
dp--;
}
else
dshift = (unsigned int)((int)dshift + s_inc);
}
if (sshift == s_end)
{
sshift = s_start;
sp--;
}
else
sshift = (unsigned int)((int)sshift + s_inc);
}
break;
}
case 4:
{
png_bytep sp = row + (size_t)((row_info->width - 1) >> 1);
png_bytep dp = row + (size_t)((final_width - 1) >> 1);
unsigned int sshift, dshift;
unsigned int s_start, s_end;
int s_inc;
png_uint_32 i;
int jstop = (int)png_pass_inc[pass];
#ifdef PNG_READ_PACKSWAP_SUPPORTED
if ((transformations & PNG_PACKSWAP) != 0)
{
sshift = (((row_info->width + 1) & 0x01) << 2);
dshift = (((final_width + 1) & 0x01) << 2);
s_start = 4;
s_end = 0;
s_inc = -4;
}
else
#endif
{
sshift = ((1 - ((row_info->width + 1) & 0x01)) << 2);
dshift = ((1 - ((final_width + 1) & 0x01)) << 2);
s_start = 0;
s_end = 4;
s_inc = 4;
}
for (i = 0; i < row_info->width; i++)
{
png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
int j;
for (j = 0; j < jstop; j++)
{
unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
tmp |= (unsigned int)(v << dshift);
*dp = (png_byte)(tmp & 0xff);
if (dshift == s_end)
{
dshift = s_start;
dp--;
}
else
dshift = (unsigned int)((int)dshift + s_inc);
}
if (sshift == s_end)
{
sshift = s_start;
sp--;
}
else
sshift = (unsigned int)((int)sshift + s_inc);
}
break;
}
default:
{
size_t pixel_bytes = (row_info->pixel_depth >> 3);
png_bytep sp = row + (size_t)(row_info->width - 1)
* pixel_bytes;
png_bytep dp = row + (size_t)(final_width - 1) * pixel_bytes;
int jstop = (int)png_pass_inc[pass];
png_uint_32 i;
for (i = 0; i < row_info->width; i++)
{
png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */
int j;
memcpy(v, sp, pixel_bytes);
for (j = 0; j < jstop; j++)
{
memcpy(dp, v, pixel_bytes);
dp -= pixel_bytes;
}
sp -= pixel_bytes;
}
break;
}
}
row_info->width = final_width;
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
}
#ifndef PNG_READ_PACKSWAP_SUPPORTED
PNG_UNUSED(transformations) /* Silence compiler warning */
#endif
}
#endif /* READ_INTERLACING */
static void
png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
png_const_bytep prev_row)
{
size_t i;
size_t istop = row_info->rowbytes;
unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
png_bytep rp = row + bpp;
PNG_UNUSED(prev_row)
for (i = bpp; i < istop; i++)
{
*rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
rp++;
}
}
static void
png_read_filter_row_up(png_row_infop row_info, png_bytep row,
png_const_bytep prev_row)
{
size_t i;
size_t istop = row_info->rowbytes;
png_bytep rp = row;
png_const_bytep pp = prev_row;
for (i = 0; i < istop; i++)
{
*rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
rp++;
}
}
static void
png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
png_const_bytep prev_row)
{
size_t i;
png_bytep rp = row;
png_const_bytep pp = prev_row;
unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
size_t istop = row_info->rowbytes - bpp;
for (i = 0; i < bpp; i++)
{
*rp = (png_byte)(((int)(*rp) +
((int)(*pp++) / 2 )) & 0xff);
rp++;
}
for (i = 0; i < istop; i++)
{
*rp = (png_byte)(((int)(*rp) +
(int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
rp++;
}
}
static void
png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
png_const_bytep prev_row)
{
png_bytep rp_end = row + row_info->rowbytes;
int a, c;
/* First pixel/byte */
c = *prev_row++;
a = *row + c;
*row++ = (png_byte)a;
/* Remainder */
while (row < rp_end)
{
int b, pa, pb, pc, p;
a &= 0xff; /* From previous iteration or start */
b = *prev_row++;
p = b - c;
pc = a - c;
#ifdef PNG_USE_ABS
pa = abs(p);
pb = abs(pc);
pc = abs(p + pc);
#else
pa = p < 0 ? -p : p;
pb = pc < 0 ? -pc : pc;
pc = (p + pc) < 0 ? -(p + pc) : p + pc;
#endif
/* Find the best predictor, the least of pa, pb, pc favoring the earlier
* ones in the case of a tie.
*/
if (pb < pa)
{
pa = pb; a = b;
}
if (pc < pa) a = c;
/* Calculate the current pixel in a, and move the previous row pixel to c
* for the next time round the loop
*/
c = b;
a += *row;
*row++ = (png_byte)a;
}
}
static void
png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
png_const_bytep prev_row)
{
unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
png_bytep rp_end = row + bpp;
/* Process the first pixel in the row completely (this is the same as 'up'
* because there is only one candidate predictor for the first row).
*/
while (row < rp_end)
{
int a = *row + *prev_row++;
*row++ = (png_byte)a;
}
/* Remainder */
rp_end = rp_end + (row_info->rowbytes - bpp);
while (row < rp_end)
{
int a, b, c, pa, pb, pc, p;
c = *(prev_row - bpp);
a = *(row - bpp);
b = *prev_row++;
p = b - c;
pc = a - c;
#ifdef PNG_USE_ABS
pa = abs(p);
pb = abs(pc);
pc = abs(p + pc);
#else
pa = p < 0 ? -p : p;
pb = pc < 0 ? -pc : pc;
pc = (p + pc) < 0 ? -(p + pc) : p + pc;
#endif
if (pb < pa)
{
pa = pb; a = b;
}
if (pc < pa) a = c;
a += *row;
*row++ = (png_byte)a;
}
}
static void
png_init_filter_functions(png_structrp pp)
/* This function is called once for every PNG image (except for PNG images
* that only use PNG_FILTER_VALUE_NONE for all rows) to set the
* implementations required to reverse the filtering of PNG rows. Reversing
* the filter is the first transformation performed on the row data. It is
* performed in place, therefore an implementation can be selected based on
* the image pixel format. If the implementation depends on image width then
* take care to ensure that it works correctly if the image is interlaced -
* interlacing causes the actual row width to vary.
*/
{
unsigned int bpp = (pp->pixel_depth + 7) >> 3;
pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
if (bpp == 1)
pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
png_read_filter_row_paeth_1byte_pixel;
else
pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
png_read_filter_row_paeth_multibyte_pixel;
#ifdef PNG_FILTER_OPTIMIZATIONS
/* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
* call to install hardware optimizations for the above functions; simply
* replace whatever elements of the pp->read_filter[] array with a hardware
* specific (or, for that matter, generic) optimization.
*
* To see an example of this examine what configure.ac does when
* --enable-arm-neon is specified on the command line.
*/
PNG_FILTER_OPTIMIZATIONS(pp, bpp);
#endif
}
void /* PRIVATE */
png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
png_const_bytep prev_row, int filter)
{
/* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
* PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
* implementations. See png_init_filter_functions above.
*/
if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
{
if (pp->read_filter[0] == NULL)
png_init_filter_functions(pp);
pp->read_filter[filter-1](row_info, row, prev_row);
}
}
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
void /* PRIVATE */
png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
png_alloc_size_t avail_out)
{
/* Loop reading IDATs and decompressing the result into output[avail_out] */
png_ptr->zstream.next_out = output;
png_ptr->zstream.avail_out = 0; /* safety: set below */
if (output == NULL)
avail_out = 0;
do
{
int ret;
png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
if (png_ptr->zstream.avail_in == 0)
{
uInt avail_in;
png_bytep buffer;
while (png_ptr->idat_size == 0)
{
png_crc_finish(png_ptr, 0);
png_ptr->idat_size = png_read_chunk_header(png_ptr);
/* This is an error even in the 'check' case because the code just
* consumed a non-IDAT header.
*/
if (png_ptr->chunk_name != png_IDAT)
png_error(png_ptr, "Not enough image data");
}
avail_in = png_ptr->IDAT_read_size;
if (avail_in > png_chunk_max(png_ptr))
avail_in = (uInt)/*SAFE*/png_chunk_max(png_ptr);
if (avail_in > png_ptr->idat_size)
avail_in = (uInt)png_ptr->idat_size;
/* A PNG with a gradually increasing IDAT size will defeat this attempt
* to minimize memory usage by causing lots of re-allocs, but
* realistically doing IDAT_read_size re-allocs is not likely to be a
* big problem.
*
* An error here corresponds to the system being out of memory.
*/
buffer = png_read_buffer(png_ptr, avail_in);
if (buffer == NULL)
png_chunk_error(png_ptr, "out of memory");
png_crc_read(png_ptr, buffer, avail_in);
png_ptr->idat_size -= avail_in;
png_ptr->zstream.next_in = buffer;
png_ptr->zstream.avail_in = avail_in;
}
/* And set up the output side. */
if (output != NULL) /* standard read */
{
uInt out = ZLIB_IO_MAX;
if (out > avail_out)
out = (uInt)avail_out;
avail_out -= out;
png_ptr->zstream.avail_out = out;
}
else /* after last row, checking for end */
{
png_ptr->zstream.next_out = tmpbuf;
png_ptr->zstream.avail_out = (sizeof tmpbuf);
}
/* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
* process. If the LZ stream is truncated the sequential reader will
* terminally damage the stream, above, by reading the chunk header of the
* following chunk (it then exits with png_error).
*
* TODO: deal more elegantly with truncated IDAT lists.
*/
ret = PNG_INFLATE(png_ptr, Z_NO_FLUSH);
/* Take the unconsumed output back. */
if (output != NULL)
avail_out += png_ptr->zstream.avail_out;
else /* avail_out counts the extra bytes */
avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
png_ptr->zstream.avail_out = 0;
if (ret == Z_STREAM_END)
{
/* Do this for safety; we won't read any more into this row. */
png_ptr->zstream.next_out = NULL;
png_ptr->mode |= PNG_AFTER_IDAT;
png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
png_chunk_benign_error(png_ptr, "Extra compressed data");
break;
}
if (ret != Z_OK)
{
png_zstream_error(png_ptr, ret);
if (output != NULL)
png_chunk_error(png_ptr, png_ptr->zstream.msg);
else /* checking */
{
png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
return;
}
}
} while (avail_out > 0);
if (avail_out > 0)
{
/* The stream ended before the image; this is the same as too few IDATs so
* should be handled the same way.
*/
if (output != NULL)
png_error(png_ptr, "Not enough image data");
else /* the deflate stream contained extra data */
png_chunk_benign_error(png_ptr, "Too much image data");
}
}
void /* PRIVATE */
png_read_finish_IDAT(png_structrp png_ptr)
{
/* We don't need any more data and the stream should have ended, however the
* LZ end code may actually not have been processed. In this case we must
* read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
* may still remain to be consumed.
*/
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
{
/* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
* the compressed stream, but the stream may be damaged too, so even after
* this call we may need to terminate the zstream ownership.
*/
png_read_IDAT_data(png_ptr, NULL, 0);
png_ptr->zstream.next_out = NULL; /* safety */
/* Now clear everything out for safety; the following may not have been
* done.
*/
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
{
png_ptr->mode |= PNG_AFTER_IDAT;
png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
}
}
/* If the zstream has not been released do it now *and* terminate the reading
* of the final IDAT chunk.
*/
if (png_ptr->zowner == png_IDAT)
{
/* Always do this; the pointers otherwise point into the read buffer. */
png_ptr->zstream.next_in = NULL;
png_ptr->zstream.avail_in = 0;
/* Now we no longer own the zstream. */
png_ptr->zowner = 0;
/* The slightly weird semantics of the sequential IDAT reading is that we
* are always in or at the end of an IDAT chunk, so we always need to do a
* crc_finish here. If idat_size is non-zero we also need to read the
* spurious bytes at the end of the chunk now.
*/
(void)png_crc_finish(png_ptr, png_ptr->idat_size);
}
}
void /* PRIVATE */
png_read_finish_row(png_structrp png_ptr)
{
png_debug(1, "in png_read_finish_row");
png_ptr->row_number++;
if (png_ptr->row_number < png_ptr->num_rows)
return;
if (png_ptr->interlaced != 0)
{
png_ptr->row_number = 0;
/* TO DO: don't do this if prev_row isn't needed (requires
* read-ahead of the next row's filter byte.
*/
memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
do
{
png_ptr->pass++;
if (png_ptr->pass >= 7)
break;
png_ptr->iwidth = (png_ptr->width +
png_pass_inc[png_ptr->pass] - 1 -
png_pass_start[png_ptr->pass]) /
png_pass_inc[png_ptr->pass];
if ((png_ptr->transformations & PNG_INTERLACE) == 0)
{
png_ptr->num_rows = (png_ptr->height +
png_pass_yinc[png_ptr->pass] - 1 -
png_pass_ystart[png_ptr->pass]) /
png_pass_yinc[png_ptr->pass];
}
else /* if (png_ptr->transformations & PNG_INTERLACE) */
break; /* libpng deinterlacing sees every row */
} while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
if (png_ptr->pass < 7)
return;
}
/* Here after at the end of the last row of the last pass. */
png_read_finish_IDAT(png_ptr);
}
#endif /* SEQUENTIAL_READ */
void /* PRIVATE */
png_read_start_row(png_structrp png_ptr)
{
unsigned int max_pixel_depth;
size_t row_bytes;
png_debug(1, "in png_read_start_row");
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
png_init_read_transformations(png_ptr);
#endif
if (png_ptr->interlaced != 0)
{
if ((png_ptr->transformations & PNG_INTERLACE) == 0)
png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
png_pass_ystart[0]) / png_pass_yinc[0];
else
png_ptr->num_rows = png_ptr->height;
png_ptr->iwidth = (png_ptr->width +
png_pass_inc[png_ptr->pass] - 1 -
png_pass_start[png_ptr->pass]) /
png_pass_inc[png_ptr->pass];
}
else
{
png_ptr->num_rows = png_ptr->height;
png_ptr->iwidth = png_ptr->width;
}
max_pixel_depth = (unsigned int)png_ptr->pixel_depth;
/* WARNING: * png_read_transform_info (pngrtran.c) performs a simpler set of
* calculations to calculate the final pixel depth, then
* png_do_read_transforms actually does the transforms. This means that the
* code which effectively calculates this value is actually repeated in three
* separate places. They must all match. Innocent changes to the order of
* transformations can and will break libpng in a way that causes memory
* overwrites.
*
* TODO: fix this.
*/
#ifdef PNG_READ_PACK_SUPPORTED
if ((png_ptr->transformations & PNG_PACK) != 0 && png_ptr->bit_depth < 8)
max_pixel_depth = 8;
#endif
#ifdef PNG_READ_EXPAND_SUPPORTED
if ((png_ptr->transformations & PNG_EXPAND) != 0)
{
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
if (png_ptr->num_trans != 0)
max_pixel_depth = 32;
else
max_pixel_depth = 24;
}
else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
{
if (max_pixel_depth < 8)
max_pixel_depth = 8;
if (png_ptr->num_trans != 0)
max_pixel_depth *= 2;
}
else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
{
if (png_ptr->num_trans != 0)
{
max_pixel_depth *= 4;
max_pixel_depth /= 3;
}
}
}
#endif
#ifdef PNG_READ_EXPAND_16_SUPPORTED
if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
{
# ifdef PNG_READ_EXPAND_SUPPORTED
/* In fact it is an error if it isn't supported, but checking is
* the safe way.
*/
if ((png_ptr->transformations & PNG_EXPAND) != 0)
{
if (png_ptr->bit_depth < 16)
max_pixel_depth *= 2;
}
else
# endif
png_ptr->transformations &= ~PNG_EXPAND_16;
}
#endif
#ifdef PNG_READ_FILLER_SUPPORTED
if ((png_ptr->transformations & (PNG_FILLER)) != 0)
{
if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
{
if (max_pixel_depth <= 8)
max_pixel_depth = 16;
else
max_pixel_depth = 32;
}
else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
if (max_pixel_depth <= 32)
max_pixel_depth = 32;
else
max_pixel_depth = 64;
}
}
#endif
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
{
if (
#ifdef PNG_READ_EXPAND_SUPPORTED
(png_ptr->num_trans != 0 &&
(png_ptr->transformations & PNG_EXPAND) != 0) ||
#endif
#ifdef PNG_READ_FILLER_SUPPORTED
(png_ptr->transformations & (PNG_FILLER)) != 0 ||
#endif
png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
{
if (max_pixel_depth <= 16)
max_pixel_depth = 32;
else
max_pixel_depth = 64;
}
else
{
if (max_pixel_depth <= 8)
{
if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
max_pixel_depth = 32;
else
max_pixel_depth = 24;
}
else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
max_pixel_depth = 64;
else
max_pixel_depth = 48;
}
}
#endif
#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
{
unsigned int user_pixel_depth = png_ptr->user_transform_depth *
png_ptr->user_transform_channels;
if (user_pixel_depth > max_pixel_depth)
max_pixel_depth = user_pixel_depth;
}
#endif
/* This value is stored in png_struct and double checked in the row read
* code.
*/
png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
/* Align the width on the next larger 8 pixels. Mainly used
* for interlacing
*/
row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
/* Calculate the maximum bytes needed, adding a byte and a pixel
* for safety's sake
*/
row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
1 + ((max_pixel_depth + 7) >> 3U);
#ifdef PNG_MAX_MALLOC_64K
if (row_bytes > (png_uint_32)65536L)
png_error(png_ptr, "This image requires a row greater than 64KB");
#endif
if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
{
png_free(png_ptr, png_ptr->big_row_buf);
png_free(png_ptr, png_ptr->big_prev_row);
if (png_ptr->interlaced != 0)
png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
row_bytes + 48);
else
png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
#ifdef PNG_ALIGNED_MEMORY_SUPPORTED
/* Use 16-byte aligned memory for row_buf with at least 16 bytes
* of padding before and after row_buf; treat prev_row similarly.
* NOTE: the alignment is to the start of the pixels, one beyond the start
* of the buffer, because of the filter byte. Prior to libpng 1.5.6 this
* was incorrect; the filter byte was aligned, which had the exact
* opposite effect of that intended.
*/
{
png_bytep temp = png_ptr->big_row_buf + 32;
size_t extra = (size_t)temp & 0x0f;
png_ptr->row_buf = temp - extra - 1/*filter byte*/;
temp = png_ptr->big_prev_row + 32;
extra = (size_t)temp & 0x0f;
png_ptr->prev_row = temp - extra - 1/*filter byte*/;
}
#else
/* Use 31 bytes of padding before and 17 bytes after row_buf. */
png_ptr->row_buf = png_ptr->big_row_buf + 31;
png_ptr->prev_row = png_ptr->big_prev_row + 31;
#endif
png_ptr->old_big_row_buf_size = row_bytes + 48;
}
#ifdef PNG_MAX_MALLOC_64K
if (png_ptr->rowbytes > 65535)
png_error(png_ptr, "This image requires a row greater than 64KB");
#endif
if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
png_error(png_ptr, "Row has too many bytes to allocate in memory");
memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
png_debug1(3, "width = %u,", png_ptr->width);
png_debug1(3, "height = %u,", png_ptr->height);
png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
png_debug1(3, "irowbytes = %lu",
(unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
/* The sequential reader needs a buffer for IDAT, but the progressive reader
* does not, so free the read buffer now regardless; the sequential reader
* reallocates it on demand.
*/
if (png_ptr->read_buffer != NULL)
{
png_bytep buffer = png_ptr->read_buffer;
png_ptr->read_buffer_size = 0;
png_ptr->read_buffer = NULL;
png_free(png_ptr, buffer);
}
/* Finally claim the zstream for the inflate of the IDAT data, use the bits
* value from the stream (note that this will result in a fatal error if the
* IDAT stream has a bogus deflate header window_bits value, but this should
* not be happening any longer!)
*/
if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
png_error(png_ptr, png_ptr->zstream.msg);
png_ptr->flags |= PNG_FLAG_ROW_INIT;
}
#endif /* READ */