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libpng/pngrutil.c
Glenn Randers-Pehrson 97c4072cce [libpng17] Clean up coding style in png_set_PLTE()
2015-11-05 11:20:12 -06:00

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/* pngrutil.c - utilities to read a PNG file
*
* Last changed in libpng 1.7.0 [(PENDING RELEASE)]
* Copyright (c) 1998-2015 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*
* This file contains routines that are only called from within
* libpng itself during the course of reading an image.
*/
#include "pngpriv.h"
#define PNG_SRC_FILE PNG_SRC_FILE_pngrutil
#ifdef PNG_READ_SUPPORTED
#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
/* The following is a variation on the above for use with the fixed
* point values used for gAMA and cHRM. Instead of png_error it
* issues a warning and returns (-1) - an invalid value because both
* gAMA and cHRM use *unsigned* integers for fixed point values.
*/
#define PNG_FIXED_ERROR (-1)
static png_fixed_point /* PRIVATE */
png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf);
if (uval <= PNG_UINT_31_MAX)
return (png_fixed_point)uval; /* known to be in range */
/* The caller can turn off the warning by passing NULL. */
if (png_ptr != NULL)
png_warning(png_ptr, "PNG fixed point integer out of range");
return PNG_FIXED_ERROR;
}
#endif /* READ_gAMA or READ_cHRM */
#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)
{
return PNG_U32(buf[0], buf[1], buf[2], buf[3]);
}
/* 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)
{
return PNG_S32(buf[0], buf[1], buf[2], buf[3]);
}
/* 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)
{
return PNG_U16(buf[0], buf[1]);
}
#endif /* READ_INT_FUNCTIONS */
/* This is an exported function however its error handling is too harsh for most
* internal use. For example if it were used for reading the chunk parameters
* it would error out even on ancillary chunks that can be ignored.
*/
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;
}
/* Read and check the PNG file signature */
void /* PRIVATE */
png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
{
png_size_t num_checked, num_to_check;
/* Exit if the user application does not expect a signature. */
if (png_ptr->sig_bytes >= 8)
return;
num_checked = png_ptr->sig_bytes;
num_to_check = 8 - num_checked;
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
#endif
/* The signature must be serialized in a single I/O call. */
png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
png_ptr->sig_bytes = 8;
if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
{
if (num_checked < 4 &&
png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
png_error(png_ptr, "Not a PNG file");
else
png_error(png_ptr, "PNG file corrupted by ASCII conversion");
}
if (num_checked < 3)
png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
}
/* Read 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)
{
png_byte crc_bytes[4];
png_uint_32 crc;
int need_crc = 1;
if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))
{
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)
need_crc = 0;
}
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
#endif
/* The chunk CRC must be serialized in a single I/O call. */
png_read_data(png_ptr, crc_bytes, 4);
if (need_crc != 0)
{
crc = png_get_uint_32(crc_bytes);
return ((int)(crc != png_ptr->crc));
}
else
return (0);
}
/* Optionally skip data and then check the CRC. Depending on whether we
* are reading an ancillary or critical chunk, and how the program has set
* things up, we may calculate the CRC on the data and print a message.
* Returns '1' if there was a CRC error, '0' otherwise.
*/
int /* PRIVATE */
png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
{
/* The size of the local buffer for inflate is a good guess as to a
* reasonable size to use for buffering reads from the application.
*/
while (skip > 0)
{
png_uint_32 len;
png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
len = (sizeof tmpbuf);
if (len > skip)
len = skip;
skip -= len;
png_crc_read(png_ptr, tmpbuf, len);
}
if (png_crc_error(png_ptr))
{
if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) ?
(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);
}
#if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\
defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\
defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\
defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED)
/* Manage the read buffer; this simply reallocates the buffer if it is not small
* enough (or if it is not allocated). The routine returns a pointer to the
* buffer; if an error occurs and 'warn' is set the routine returns NULL, else
* it will call png_error (via png_malloc) on failure. (warn == 2 means
* 'silent').
*/
png_bytep /* PRIVATE */
png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
{
png_bytep buffer = png_ptr->read_buffer;
if (buffer != NULL && new_size > png_ptr->read_buffer_size)
{
png_ptr->read_buffer = NULL;
png_ptr->read_buffer_size = 0;
png_free(png_ptr, buffer);
buffer = NULL;
}
if (buffer == NULL)
{
buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
if (buffer != NULL)
{
png_ptr->read_buffer = buffer;
png_ptr->read_buffer_size = new_size;
}
else if (warn < 2) /* else silent */
{
if (warn != 0)
png_chunk_warning(png_ptr, "insufficient memory to read chunk");
else
png_chunk_error(png_ptr, "insufficient memory to read chunk");
}
}
return buffer;
}
#endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */
/* png_inflate_claim: claim the zstream for some nefarious purpose that involves
* decompression. Returns Z_OK on success, else a zlib error code. It checks
* the owner but, in final release builds, just issues a warning if some other
* chunk apparently owns the stream. Prior to release it does a png_error.
*/
static int
png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
{
if (png_ptr->zowner != 0)
{
char msg[64];
PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
/* So the message that results is "<chunk> using zstream"; this is an
* internal error, but is very useful for debugging. i18n requirements
* are minimal.
*/
(void)png_safecat(msg, (sizeof msg), 4, " using zstream");
# if PNG_RELEASE_BUILD
png_chunk_warning(png_ptr, msg);
png_ptr->zowner = 0;
# else
png_chunk_error(png_ptr, msg);
# endif
}
/* Implementation note: unlike 'png_deflate_claim' this internal function
* does not take the size of the data as an argument. Some efficiency could
* be gained by using this when it is known *if* the zlib stream itself does
* not record the number; however, this is an illusion: the original writer
* of the PNG may have selected a lower window size, and we really must
* follow that because, for systems with with limited capabilities, we
* would otherwise reject the application's attempts to use a smaller window
* size (zlib doesn't have an interface to say "this or lower"!).
*
* inflateReset2 was added to zlib 1.2.4; before this the window could not be
* reset, therefore it is necessary to always allocate the maximum window
* size with earlier zlibs just in case later compressed chunks need it.
*/
{
int ret; /* zlib return code */
# if PNG_ZLIB_VERNUM >= 0x1240
# if defined(PNG_SET_OPTION_SUPPORTED) && \
defined(PNG_MAXIMUM_INFLATE_WINDOW)
int window_bits;
if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
PNG_OPTION_ON)
window_bits = 15;
else
window_bits = 0;
# else
# define window_bits 0
# endif
# endif
/* 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_struct::zstream has been used before for decompression it does
* not need to be re-initialized, just reset.
*/
if (png_ptr->zstream.state != NULL)
{
# if PNG_ZLIB_VERNUM < 0x1240
ret = inflateReset(&png_ptr->zstream);
# else
ret = inflateReset2(&png_ptr->zstream, window_bits);
# endif
}
else
{
# if PNG_ZLIB_VERNUM < 0x1240
ret = inflateInit(&png_ptr->zstream);
# else
ret = inflateInit2(&png_ptr->zstream, window_bits);
# endif
}
if (ret == Z_OK && png_ptr->zstream.state != NULL)
{
png_ptr->zowner = owner;
png_ptr->zstream_ended = 0;
}
else
{
png_zstream_error(png_ptr, ret);
png_ptr->zstream_ended = 1;
}
return ret;
}
# ifdef window_bits
# undef window_bits
# endif
}
/* This is a wrapper for the zlib deflate call which will handle larger buffer
* sizes than uInt. The input is limited to png_uint_32, because invariably
* the input comes from a chunk which has a 31-bit length, the output can be
* anything that fits in a png_alloc_size_t.
*
* This internal function sets png_struct::zstream_ended when the end of the
* decoded data has been encountered; this includes both a normal end and
* error conditions.
*/
static int
png_zlib_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
/* INPUT: */ png_const_bytep *next_in_ptr, png_uint_32p avail_in_ptr,
/* OUTPUT: */ png_bytep *next_out_ptr, png_alloc_size_t *avail_out_ptr)
{
if (png_ptr->zowner == owner) /* Else not claimed */
{
int ret;
png_alloc_size_t avail_out = *avail_out_ptr;
png_uint_32 avail_in = *avail_in_ptr;
png_bytep output = *next_out_ptr;
png_const_bytep input = *next_in_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 = inflate(&png_ptr->zstream, 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.
*/
*avail_out_ptr = avail_out;
if (output != NULL)
*next_out_ptr = png_ptr->zstream.next_out;
*avail_in_ptr = avail_in;
*next_in_ptr = png_ptr->zstream.next_in;
/* Ensure png_ptr->zstream.msg is set, ret can't be Z_OK at this point.
*/
debug(ret != Z_OK);
if (ret != Z_BUF_ERROR)
png_ptr->zstream_ended = 1;
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! (The {next,avail}_{in,out} values are not changed.)
*/
png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
return Z_STREAM_ERROR;
}
}
#ifdef PNG_READ_COMPRESSED_TEXT_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)
{
png_uint_32 avail_in = *input_size_ptr;
png_alloc_size_t avail_out = *output_size_ptr;
int ret = png_zlib_inflate(png_ptr, owner, finish,
&input, &avail_in, &output, &avail_out);
/* And implement the non-zlib semantics (the size values are updated to the
* amounts consumed and written, not the amount remaining.)
*/
*input_size_ptr -= avail_in;
*output_size_ptr -= avail_out;
return ret;
}
/* Decompress trailing data in a chunk. The assumption is that read_buffer
* points at an allocated area holding the contents of a chunk with a
* trailing compressed part. What we get back is an allocated area
* holding the original prefix part and an uncompressed version of the
* trailing part (the malloc area passed in is freed).
*/
static int
png_decompress_chunk(png_structrp png_ptr,
png_uint_32 chunklength, png_uint_32 prefix_size,
png_alloc_size_t *newlength /* must be initialized to the maximum! */,
int terminate /*add a '\0' to the end of the uncompressed data*/)
{
/* TODO: implement different limits for different types of chunk.
*
* The caller supplies *newlength set to the maximum length of the
* uncompressed data, but this routine allocates space for the prefix and
* maybe a '\0' terminator too. We have to assume that 'prefix_size' is
* limited only by the maximum chunk size.
*/
png_alloc_size_t limit = PNG_SIZE_MAX;
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_malloc_max > 0 &&
png_ptr->user_chunk_malloc_max < limit)
limit = png_ptr->user_chunk_malloc_max;
# elif PNG_USER_CHUNK_MALLOC_MAX > 0
if (PNG_USER_CHUNK_MALLOC_MAX < limit)
limit = PNG_USER_CHUNK_MALLOC_MAX;
# endif
if (limit >= prefix_size + (terminate != 0))
{
int ret;
limit -= prefix_size + (terminate != 0);
if (limit < *newlength)
*newlength = limit;
/* Now try to claim the stream. */
ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
if (ret == Z_OK)
{
png_uint_32 lzsize = chunklength - prefix_size;
ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
/* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
/* output: */ NULL, newlength);
if (ret == Z_STREAM_END)
{
/* Use 'inflateReset' here, not 'inflateReset2' because this
* preserves the previously decided window size (otherwise it would
* be necessary to store the previous window size.) In practice
* this doesn't matter anyway, because png_inflate will call inflate
* with Z_FINISH in almost all cases, so the window will not be
* maintained.
*/
if (inflateReset(&png_ptr->zstream) == Z_OK)
{
/* Because of the limit checks above we know that the new,
* expanded, size will fit in a size_t (let alone an
* png_alloc_size_t). Use png_malloc_base here to avoid an
* extra OOM message.
*/
png_alloc_size_t new_size = *newlength;
png_alloc_size_t buffer_size = prefix_size + new_size +
(terminate != 0);
png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
buffer_size));
if (text != NULL)
{
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);
if (ret == Z_STREAM_END)
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_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 = inflate(&png_ptr->zstream,
*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 error handlers and utilities: */
/* Utility to read the chunk data from the start without processing it;
* a skip function.
*/
static void
png_handle_skip(png_structrp png_ptr)
/* Skip the entire chunk after the name,length header has been read: */
{
png_crc_finish(png_ptr, png_ptr->chunk_length);
}
static void
png_handle_error(png_structrp png_ptr
# ifdef PNG_ERROR_TEXT_SUPPORTED
, png_const_charp error
# else
# define png_handle_error(pp,e) png_handle_error(pp)
# endif
)
/* Handle an error detected immediately after the chunk header has been
* read; this skips the rest of the chunk data and the CRC then signals
* a *benign* chunk error.
*/
{
png_handle_skip(png_ptr);
png_chunk_benign_error(png_ptr, error);
}
static void
png_handle_bad_length(png_structrp png_ptr)
{
png_handle_error(png_ptr, "invalid length");
}
/* Read and check the IDHR chunk */
static void
png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr)
{
png_byte buf[13];
png_uint_32 width, height;
png_byte bit_depth, color_type, compression_type, filter_method;
png_byte interlace_type;
png_debug(1, "in png_handle_IHDR");
/* Check the length (this is a chunk error; not benign) */
if (png_ptr->chunk_length != 13)
png_chunk_error(png_ptr, "invalid length");
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_method = buf[11];
interlace_type = buf[12];
/* Set internal variables */
png_ptr->width = width;
png_ptr->height = height;
png_ptr->bit_depth = bit_depth;
png_ptr->interlaced = interlace_type;
png_ptr->color_type = color_type;
png_ptr->filter_method = filter_method;
png_ptr->compression_type = compression_type;
png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
color_type, interlace_type, compression_type, filter_method);
}
/* Read and check the palette */
static void
png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr)
{
png_color palette[PNG_MAX_PALETTE_LENGTH];
png_uint_32 length = png_ptr->chunk_length;
int max_palette_length, num, i;
png_colorp pal_ptr;
png_debug(1, "in png_handle_PLTE");
if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
{
png_handle_error(png_ptr, "ignored in grayscale PNG");
return;
}
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
{
png_handle_skip(png_ptr);
return;
}
#endif
if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
{
png_crc_finish(png_ptr, length);
png_chunk_report(png_ptr, "invalid length",
((png_ptr->color_type != PNG_COLOR_TYPE_PALETTE) ? PNG_CHUNK_ERROR :
PNG_CHUNK_FATAL));
return;
}
/* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
num = (int)length / 3;
/* If the palette has 256 or fewer entries but is too large for the bit
* depth, we don't issue an error, to preserve the behavior of previous
* libpng versions. We silently truncate the unused extra palette entries
* here.
*/
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
max_palette_length = (1 << png_ptr->bit_depth);
else
max_palette_length = PNG_MAX_PALETTE_LENGTH;
if (num > max_palette_length)
num = max_palette_length;
for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
{
png_byte buf[3];
png_crc_read(png_ptr, buf, 3);
pal_ptr->red = buf[0];
pal_ptr->green = buf[1];
pal_ptr->blue = buf[2];
}
/* If we actually need the PLTE chunk (ie for a paletted image), we do
* whatever the normal CRC configuration tells us. However, if we
* have an RGB image, the PLTE can be considered ancillary, so
* we will act as though it is.
*/
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
#endif
png_crc_finish(png_ptr, (int) length - num * 3);
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
else if (png_crc_error(png_ptr)) /* Only if we have a CRC error */
{
/* If we don't want to use the data from an ancillary chunk,
* we have two options: an error abort, or a warning and we
* ignore the data in this chunk (which should be OK, since
* it's considered ancillary for a RGB or RGBA image).
*
* IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
* chunk type to determine whether to check the ancillary or the critical
* flags.
*/
if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
{
if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
return;
else
png_chunk_error(png_ptr, "CRC error");
}
/* Otherwise, we (optionally) emit a warning and use the chunk. */
else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
{
png_chunk_warning(png_ptr, "CRC error");
}
}
#endif /* READ_OPT_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.
*
* Fix this by not sharing the palette in this way.
*/
png_set_PLTE(png_ptr, info_ptr, palette, num);
/* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
* IDAT. Prior to 1.6.0 this was not checked; instead the code merely
* checked the apparent validity of a tRNS chunk inserted before PLTE on a
* palette PNG. 1.6.0 attempts to rigorously follow the standard and
* therefore does a benign error if the erroneous condition is detected *and*
* cancels the tRNS if the benign error returns. The alternative is to
* amend the standard since it would be rather hypocritical of the standards
* maintainers to ignore it.
*/
#ifdef PNG_READ_tRNS_SUPPORTED
if (png_ptr->num_trans > 0 ||
(info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
{
/* Cancel this because otherwise it would be used if the transforms
* require it. Don't cancel the 'valid' flag because this would prevent
* detection of duplicate chunks.
*/
png_ptr->num_trans = 0;
if (info_ptr != NULL)
info_ptr->num_trans = 0;
png_chunk_benign_error(png_ptr, "tRNS must be after");
}
#endif /* READ_tRNS */
#ifdef PNG_READ_hIST_SUPPORTED
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
png_chunk_benign_error(png_ptr, "hIST must be after");
#endif /* READ_hIST */
#ifdef PNG_READ_bKGD_SUPPORTED
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
png_chunk_benign_error(png_ptr, "bKGD must be after");
#endif /* READ_bKGD */
}
static void
png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr)
{
png_debug(1, "in png_handle_IEND");
png_crc_finish(png_ptr, png_ptr->chunk_length);
/* Treat this as benign and terminate the PNG anyway: */
if (png_ptr->chunk_length != 0)
png_chunk_benign_error(png_ptr, "invalid length");
PNG_UNUSED(info_ptr)
}
#ifdef PNG_READ_gAMA_SUPPORTED
static void
png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr)
{
png_fixed_point igamma;
png_byte buf[4];
png_debug(1, "in png_handle_gAMA");
if (png_ptr->chunk_length != 4)
{
png_handle_bad_length(png_ptr);
return;
}
png_crc_read(png_ptr, buf, 4);
if (png_crc_finish(png_ptr, 0))
return;
igamma = png_get_fixed_point(NULL, buf);
png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
png_colorspace_sync(png_ptr, info_ptr);
}
#else
# define png_handle_gAMA NULL
#endif /* READ_gAMA */
#ifdef PNG_READ_sBIT_SUPPORTED
static void
png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr)
{
unsigned int truelen, i;
png_byte sample_depth;
png_byte buf[4];
png_debug(1, "in png_handle_sBIT");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
{
png_handle_error(png_ptr, "duplicate");
return;
}
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
truelen = 3;
sample_depth = 8;
}
else
{
truelen = PNG_CHANNELS(*png_ptr);
sample_depth = png_ptr->bit_depth;
affirm(truelen <= 4);
}
if (png_ptr->chunk_length != truelen)
{
png_handle_bad_length(png_ptr);
return;
}
buf[0] = buf[1] = buf[2] = buf[3] = sample_depth;
png_crc_read(png_ptr, buf, truelen);
if (png_crc_finish(png_ptr, 0))
return;
for (i=0; i<truelen; ++i)
if (buf[i] == 0 || buf[i] > sample_depth)
{
png_chunk_benign_error(png_ptr, "invalid");
return;
}
if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
{
png_ptr->sig_bit.red = buf[0];
png_ptr->sig_bit.green = buf[1];
png_ptr->sig_bit.blue = buf[2];
png_ptr->sig_bit.alpha = buf[3];
}
else
{
png_ptr->sig_bit.gray = buf[0];
png_ptr->sig_bit.red = buf[0];
png_ptr->sig_bit.green = buf[0];
png_ptr->sig_bit.blue = buf[0];
png_ptr->sig_bit.alpha = buf[1];
}
png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
}
#else
# define png_handle_sBIT NULL
#endif /* READ_sBIT */
#ifdef PNG_READ_cHRM_SUPPORTED
static void
png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr)
{
png_byte buf[32];
png_xy xy;
png_debug(1, "in png_handle_cHRM");
if (png_ptr->chunk_length != 32)
{
png_handle_bad_length(png_ptr);
return;
}
png_crc_read(png_ptr, buf, 32);
if (png_crc_finish(png_ptr, 0))
return;
xy.whitex = png_get_fixed_point(NULL, buf);
xy.whitey = png_get_fixed_point(NULL, buf + 4);
xy.redx = png_get_fixed_point(NULL, buf + 8);
xy.redy = png_get_fixed_point(NULL, buf + 12);
xy.greenx = png_get_fixed_point(NULL, buf + 16);
xy.greeny = png_get_fixed_point(NULL, buf + 20);
xy.bluex = png_get_fixed_point(NULL, buf + 24);
xy.bluey = png_get_fixed_point(NULL, buf + 28);
if (xy.whitex == PNG_FIXED_ERROR ||
xy.whitey == PNG_FIXED_ERROR ||
xy.redx == PNG_FIXED_ERROR ||
xy.redy == PNG_FIXED_ERROR ||
xy.greenx == PNG_FIXED_ERROR ||
xy.greeny == PNG_FIXED_ERROR ||
xy.bluex == PNG_FIXED_ERROR ||
xy.bluey == PNG_FIXED_ERROR)
{
png_chunk_benign_error(png_ptr, "invalid");
return;
}
/* If a colorspace error has already been output skip this chunk */
if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
return;
if (png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM)
{
png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
png_colorspace_sync(png_ptr, info_ptr);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
(void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
1/*prefer cHRM values*/);
png_colorspace_sync(png_ptr, info_ptr);
}
#else
# define png_handle_cHRM NULL
#endif /* READ_cHRM */
#ifdef PNG_READ_sRGB_SUPPORTED
static void
png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr)
{
png_byte intent;
png_debug(1, "in png_handle_sRGB");
if (png_ptr->chunk_length != 1)
{
png_handle_bad_length(png_ptr);
return;
}
png_crc_read(png_ptr, &intent, 1);
if (png_crc_finish(png_ptr, 0))
return;
/* If a colorspace error has already been output skip this chunk */
if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
return;
/* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
* this.
*/
if (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT)
{
png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
png_colorspace_sync(png_ptr, info_ptr);
png_chunk_benign_error(png_ptr, "too many profiles");
return;
}
(void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
png_colorspace_sync(png_ptr, info_ptr);
}
#else
# define png_handle_sRGB NULL
#endif /* READ_sRGB */
#ifdef PNG_READ_iCCP_SUPPORTED
static void
png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr)
/* Note: this does not properly handle profiles that are > 64K under DOS */
{
png_const_charp errmsg = NULL; /* error message output, or no error */
png_uint_32 length = png_ptr->chunk_length;
int finished = 0; /* crc checked */
png_debug(1, "in png_handle_iCCP");
/* Consistent with all the above colorspace handling an obviously *invalid*
* chunk is just ignored, so does not invalidate the color space. An
* alternative is to set the 'invalid' flags at the start of this routine
* and only clear them in they were not set before and all the tests pass.
* The minimum 'deflate' stream is assumed to be just the 2 byte header and
* 4 byte checksum. The keyword must be at least one character and there is
* a terminator (0) byte and the compression method.
*/
if (length < 9)
{
png_handle_bad_length(png_ptr);
return;
}
/* If a colorspace error has already been output skip this chunk */
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
{
png_crc_finish(png_ptr, length);
return;
}
/* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
* this.
*/
if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
{
uInt read_length, keyword_length;
char keyword[81];
/* Find the keyword; the keyword plus separator and compression method
* bytes can be at most 81 characters long.
*/
read_length = 81; /* maximum */
if (read_length > length)
read_length = (uInt)/*SAFE*/length;
png_crc_read(png_ptr, (png_bytep)keyword, read_length);
length -= read_length;
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];
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.
*/
const png_uint_32 profile_length =
png_get_uint_32(profile_header);
if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
keyword, profile_length))
{
/* The length is apparently ok, so we can check the 132
* byte header.
*/
if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
keyword, profile_length, profile_header,
(png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 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 these stuff will overflow.
*/
const png_uint_32 tag_count = png_get_uint_32(
profile_header+128);
png_bytep profile = png_read_buffer(png_ptr,
profile_length, 2/*silent*/);
if (profile != NULL)
{
memcpy(profile, profile_header,
(sizeof profile_header));
size = 12 * tag_count;
(void)png_inflate_read(png_ptr, local_buffer,
(sizeof local_buffer), &length,
profile + (sizeof profile_header), &size, 0);
/* Still expect a buffer error because we expect
* there to be some tag data!
*/
if (size == 0)
{
if (png_icc_check_tag_table(png_ptr,
&png_ptr->colorspace, keyword, profile_length,
profile))
{
/* 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;
# ifdef PNG_sRGB_SUPPORTED
/* Check for a match against sRGB */
png_icc_set_sRGB(png_ptr,
&png_ptr->colorspace, profile,
png_ptr->zstream.adler);
# endif
/* Steal the profile for info_ptr. */
if (info_ptr != NULL)
{
png_free_data(png_ptr, info_ptr,
PNG_FREE_ICCP, 0);
info_ptr->iccp_name = png_voidcast(char*,
png_malloc_base(png_ptr,
keyword_length+1));
if (info_ptr->iccp_name != NULL)
{
memcpy(info_ptr->iccp_name, keyword,
keyword_length+1);
info_ptr->iccp_proflen =
profile_length;
info_ptr->iccp_profile = profile;
png_ptr->read_buffer = NULL; /*steal*/
info_ptr->free_me |= PNG_FREE_ICCP;
info_ptr->valid |= PNG_INFO_iCCP;
}
else
{
png_ptr->colorspace.flags |=
PNG_COLORSPACE_INVALID;
errmsg = "out of memory";
}
}
/* else the profile remains in the read
* buffer which gets reused for subsequent
* chunks.
*/
if (info_ptr != NULL)
png_colorspace_sync(png_ptr, info_ptr);
if (errmsg == NULL)
{
png_ptr->zowner = 0;
return;
}
}
else if (size > 0)
errmsg = "truncated";
}
/* else png_icc_check_tag_table output an error */
}
else /* profile truncated */
errmsg = png_ptr->zstream.msg;
}
else
errmsg = "out of memory";
}
/* else png_icc_check_header output an error */
}
/* else png_icc_check_length output an error */
}
else /* profile truncated */
errmsg = png_ptr->zstream.msg;
/* Release the stream */
png_ptr->zowner = 0;
}
else /* png_inflate_claim failed */
errmsg = png_ptr->zstream.msg;
}
else
errmsg = "bad compression method"; /* or missing */
}
else
errmsg = "bad keyword";
}
else
errmsg = "too many profiles";
/* Failure: the reason is in 'errmsg' */
if (finished == 0)
png_crc_finish(png_ptr, length);
png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
png_colorspace_sync(png_ptr, info_ptr);
if (errmsg != NULL) /* else already output */
png_chunk_benign_error(png_ptr, errmsg);
}
#else
# define png_handle_iCCP NULL
#endif /* READ_iCCP */
#ifdef PNG_READ_sPLT_SUPPORTED
static void
png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr)
/* Note: this does not properly handle chunks that are > 64K under DOS */
{
png_uint_32 length = png_ptr->chunk_length;
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;
png_size_t max_dl;
png_debug(1, "in png_handle_sPLT");
#ifdef PNG_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_cache_max != 0)
{
if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
/* Warn the first time */
png_chunk_benign_error(png_ptr, "no space in chunk cache");
png_crc_finish(png_ptr, length);
return;
}
}
#endif /* USER_LIMITS */
buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory");
return;
}
/* WARNING: this may break if size_t is less than 32 bits; it is assumed
* that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
* potential breakage point if the types in pngconf.h aren't exactly right.
*/
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, skip))
return;
buffer[length] = 0;
for (entry_start = buffer; *entry_start; entry_start++)
/* Empty loop to find end of name */ ;
++entry_start;
/* A sample depth should follow the separator, and we should be on it */
if (entry_start > buffer + length - 2)
{
png_chunk_benign_error(png_ptr, "malformed");
return;
}
new_palette.depth = *entry_start++;
entry_size = (new_palette.depth == 8 ? 6 : 10);
/* This must fit in a png_uint_32 because it is derived from the original
* chunk data length.
*/
data_length = length - (png_uint_32)(entry_start - buffer);
/* Integrity-check the data length */
if (data_length % entry_size)
{
png_chunk_benign_error(png_ptr, "invalid length");
return;
}
dl = (png_int_32)(data_length / entry_size);
max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
if (dl > max_dl)
{
png_chunk_benign_error(png_ptr, "exceeds system limits");
return;
}
new_palette.nentries = (png_int_32)(data_length / entry_size);
new_palette.entries = png_voidcast(png_sPLT_entryp, png_malloc_base(
png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry))));
if (new_palette.entries == NULL)
{
png_chunk_benign_error(png_ptr, "out of memory");
return;
}
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);
}
#else
# define png_handle_sPLT NULL
#endif /* READ_sPLT */
#ifdef PNG_READ_tRNS_SUPPORTED
static void
png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr)
{
png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
png_debug(1, "in png_handle_tRNS");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
{
/* libpng 1.7.0: this used to be a benign error, but it doesn't look very
* benign because it has security implications; libpng ignores the second
* tRNS, so if you can find something that ignores the first instead you
* can choose which image the user sees depending on the PNG decoder.
*/
png_crc_finish(png_ptr, png_ptr->chunk_length);
png_chunk_error(png_ptr, "duplicate");
return;
}
if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
{
png_byte buf[2];
if (png_ptr->chunk_length != 2)
{
png_handle_bad_length(png_ptr);
return;
}
png_crc_read(png_ptr, buf, 2);
png_ptr->num_trans = 1;
png_ptr->trans_color.gray = png_get_uint_16(buf);
}
else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
{
png_byte buf[6];
if (png_ptr->chunk_length != 6)
{
png_handle_bad_length(png_ptr);
return;
}
png_crc_read(png_ptr, buf, 6);
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)
{
png_uint_32 length;
/* png_find_chunk_op checks this: */
debug(png_ptr->mode & PNG_HAVE_PLTE);
length = png_ptr->chunk_length;
if (length > png_ptr->num_palette || length == 0)
{
png_handle_bad_length(png_ptr);
return;
}
png_crc_read(png_ptr, readbuf, length);
png_ptr->num_trans = length & 0x1FF;
}
else
{
png_handle_error(png_ptr, "invalid");
return;
}
if (png_crc_finish(png_ptr, 0))
{
png_ptr->num_trans = 0;
return;
}
/* TODO: this is a horrible side effect in the palette case because the
* png_struct ends up with a pointer to the tRNS buffer owned by the
* png_info. Fix this.
*/
png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
&(png_ptr->trans_color));
if (info_ptr != NULL)
png_ptr->trans_alpha = info_ptr->trans_alpha;
}
#else
# define png_handle_tRNS NULL
#endif /* READ_tRNS */
#ifdef PNG_READ_bKGD_SUPPORTED
static void
png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr)
{
unsigned int truelen;
png_byte buf[6];
png_color_16 background;
png_debug(1, "in png_handle_bKGD");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
{
png_handle_error(png_ptr, "duplicate");
return;
}
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
truelen = 1;
else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
truelen = 6;
else
truelen = 2;
if (png_ptr->chunk_length != truelen)
{
png_handle_bad_length(png_ptr);
return;
}
png_crc_read(png_ptr, buf, truelen);
if (png_crc_finish(png_ptr, 0))
return;
/* We convert the index value into RGB components so that we can allow
* arbitrary RGB values for background when we have transparency, and
* so it is easy to determine the RGB values of the background color
* from the info_ptr struct.
*/
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
background.index = buf[0];
if (info_ptr && info_ptr->num_palette)
{
if (buf[0] >= info_ptr->num_palette)
{
png_chunk_benign_error(png_ptr, "invalid index");
return;
}
background.red = png_check_u16(png_ptr, png_ptr->palette[buf[0]].red);
background.green =
png_check_u16(png_ptr, png_ptr->palette[buf[0]].green);
background.blue =
png_check_u16(png_ptr, 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)) /* GRAY */
{
background.index = 0;
background.red =
background.green =
background.blue =
background.gray = png_get_uint_16(buf);
}
else
{
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);
}
#else
# define png_handle_bKGD NULL
#endif /* READ_bKGD */
#ifdef PNG_READ_hIST_SUPPORTED
static void
png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr)
{
unsigned int num, i;
png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
png_debug(1, "in png_handle_hIST");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
{
png_handle_error(png_ptr, "duplicate");
return;
}
num = png_ptr->chunk_length / 2;
if (num != png_ptr->num_palette || 2*num != png_ptr->chunk_length)
{
png_handle_bad_length(png_ptr);
return;
}
for (i = 0; i < num; i++)
{
png_byte buf[2];
png_crc_read(png_ptr, buf, 2);
readbuf[i] = png_get_uint_16(buf);
}
if (png_crc_finish(png_ptr, 0))
return;
png_set_hIST(png_ptr, info_ptr, readbuf);
}
#else
# define png_handle_hIST NULL
#endif /* READ_hIST */
#ifdef PNG_READ_pHYs_SUPPORTED
static void
png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr)
{
png_byte buf[9];
png_uint_32 res_x, res_y;
int unit_type;
png_debug(1, "in png_handle_pHYs");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
{
png_handle_error(png_ptr, "duplicate");
return;
}
if (png_ptr->chunk_length != 9)
{
png_handle_bad_length(png_ptr);
return;
}
png_crc_read(png_ptr, buf, 9);
if (png_crc_finish(png_ptr, 0))
return;
res_x = png_get_uint_32(buf);
res_y = png_get_uint_32(buf + 4);
unit_type = buf[8];
png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
}
#else
# define png_handle_pHYs NULL
#endif /* READ_pHYs */
#ifdef PNG_READ_oFFs_SUPPORTED /* EXTENSION, before IDAT, no duplicates */
static void
png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr)
{
png_byte buf[9];
png_int_32 offset_x, offset_y;
int unit_type;
png_debug(1, "in png_handle_oFFs");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
{
png_handle_error(png_ptr, "duplicate");
return;
}
if (png_ptr->chunk_length != 9)
{
png_handle_bad_length(png_ptr);
return;
}
png_crc_read(png_ptr, buf, 9);
if (png_crc_finish(png_ptr, 0))
return;
offset_x = png_get_int_32(buf);
offset_y = png_get_int_32(buf + 4);
unit_type = buf[8];
png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
}
#else
# define png_handle_oFFs NULL
#endif /* READ_oFFs */
#ifdef PNG_READ_pCAL_SUPPORTED /* EXTENSION: before IDAT, no duplicates */
static void
png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr)
{
png_int_32 X0, X1;
png_byte type, nparams;
png_bytep buffer, buf, units, endptr;
png_charpp params;
int i;
png_debug(1, "in png_handle_pCAL");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
{
png_handle_error(png_ptr, "duplicate");
return;
}
png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
png_ptr->chunk_length + 1);
buffer = png_read_buffer(png_ptr, png_ptr->chunk_length+1, 2/*silent*/);
if (buffer == NULL)
{
png_handle_error(png_ptr, "out of memory");
return;
}
png_crc_read(png_ptr, buffer, png_ptr->chunk_length);
if (png_crc_finish(png_ptr, 0))
return;
buffer[png_ptr->chunk_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 + png_ptr->chunk_length;
/* We need to have at least 12 bytes after the purpose string
* in order to get the parameter information.
*/
if (endptr <= buf + 12)
{
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
X0 = png_get_int_32((png_bytep)buf+1);
X1 = png_get_int_32((png_bytep)buf+5);
type = buf[9];
nparams = buf[10];
units = buf + 11;
png_debug(3, "Checking pCAL equation type and number of parameters");
/* Check that we have the right number of parameters for known
* equation types.
*/
if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
(type == PNG_EQUATION_BASE_E && nparams != 3) ||
(type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
(type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
{
png_chunk_benign_error(png_ptr, "invalid parameter count");
return;
}
else if (type >= PNG_EQUATION_LAST)
{
png_chunk_benign_error(png_ptr, "unrecognized equation type");
return;
}
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_base(png_ptr,
nparams * (sizeof (png_charp))));
if (params == NULL)
{
png_chunk_benign_error(png_ptr, "out of memory");
return;
}
/* Get pointers to the start of each parameter string. */
for (i = 0; i < nparams; i++)
{
buf++; /* Skip the null string terminator from previous parameter. */
png_debug1(3, "Reading pCAL parameter %d", i);
for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
/* Empty loop to move past each parameter string */ ;
/* Make sure we haven't run out of data yet */
if (buf > endptr)
{
png_free(png_ptr, params);
png_chunk_benign_error(png_ptr, "invalid data");
return;
}
}
png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
(png_charp)units, params);
png_free(png_ptr, params);
}
#else
# define png_handle_pCAL NULL
#endif /* READ_pCAL */
#ifdef PNG_READ_sCAL_SUPPORTED
/* Read the sCAL chunk */
static void
png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr)
{
png_uint_32 length = png_ptr->chunk_length;
png_bytep buffer;
png_size_t i;
int state;
png_debug(1, "in png_handle_sCAL");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
{
png_handle_error(png_ptr, "duplicate");
return;
}
/* Need unit type, width, \0, height: minimum 4 bytes */
if (length < 4)
{
png_handle_bad_length(png_ptr);
return;
}
png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
length + 1);
buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
if (buffer == NULL)
{
png_handle_error(png_ptr, "out of memory");
return;
}
png_crc_read(png_ptr, buffer, length);
buffer[length] = 0; /* Null terminate the last string */
if (png_crc_finish(png_ptr, 0))
return;
/* Validate the unit. */
if (buffer[0] != 1 && buffer[0] != 2)
{
png_chunk_benign_error(png_ptr, "invalid unit");
return;
}
/* Validate the ASCII numbers, need two ASCII numbers separated by
* a '\0' and they need to fit exactly in the chunk data.
*/
i = 1;
state = 0;
if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
i >= length || buffer[i++] != 0)
png_chunk_benign_error(png_ptr, "bad width format");
else if (!PNG_FP_IS_POSITIVE(state))
png_chunk_benign_error(png_ptr, "non-positive width");
else
{
png_size_t heighti = i;
state = 0;
if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
i != length)
png_chunk_benign_error(png_ptr, "bad height format");
else if (!PNG_FP_IS_POSITIVE(state))
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);
}
}
#else
# define png_handle_sCAL NULL
#endif /* READ_sCAL */
#ifdef PNG_READ_tIME_SUPPORTED
static void
png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr)
{
png_byte buf[7];
png_time mod_time;
png_debug(1, "in png_handle_tIME");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
{
png_handle_error(png_ptr, "duplicate");
return;
}
if (png_ptr->chunk_length != 7)
{
png_handle_bad_length(png_ptr);
return;
}
png_crc_read(png_ptr, buf, 7);
if (png_crc_finish(png_ptr, 0))
return;
mod_time.second = buf[6];
mod_time.minute = buf[5];
mod_time.hour = buf[4];
mod_time.day = buf[3];
mod_time.month = buf[2];
mod_time.year = png_get_uint_16(buf);
png_set_tIME(png_ptr, info_ptr, &mod_time);
}
#else
# define png_handle_tIME NULL
#endif /* READ_tIME */
#ifdef PNG_READ_tEXt_SUPPORTED
static void
png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr)
{
png_uint_32 length = png_ptr->chunk_length;
png_text text_info;
png_bytep buffer;
png_charp key;
png_charp text;
png_uint_32 skip = 0;
png_debug(1, "in png_handle_tEXt");
#ifdef PNG_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_cache_max != 0)
{
if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_handle_error(png_ptr, "no space in chunk cache");
return;
}
}
#endif /* USER_LIMITS */
buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
if (buffer == NULL)
{
png_handle_error(png_ptr, "out of memory");
return;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, skip))
return;
key = (png_charp)buffer;
key[length] = 0;
for (text = key; *text; text++)
/* Empty loop to find end of key */ ;
if (text != key + length)
text++;
text_info.compression = PNG_TEXT_COMPRESSION_NONE;
text_info.key = key;
text_info.lang = NULL;
text_info.lang_key = NULL;
text_info.itxt_length = 0;
text_info.text = text;
text_info.text_length = strlen(text);
if (png_set_text_2(png_ptr, info_ptr, &text_info, 1))
png_warning(png_ptr, "Insufficient memory to process text chunk");
}
#else
# define png_handle_tEXt NULL
#endif /* READ_tEXt */
#ifdef PNG_READ_zTXt_SUPPORTED
static void
png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr)
{
png_uint_32 length = png_ptr->chunk_length;
png_const_charp errmsg = NULL;
png_bytep buffer;
png_uint_32 keyword_length;
png_debug(1, "in png_handle_zTXt");
#ifdef PNG_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_cache_max != 0)
{
if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_handle_error(png_ptr, "no space in chunk cache");
return;
}
}
#endif /* USER_LIMITS */
buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
if (buffer == NULL)
{
png_handle_error(png_ptr, "out of memory");
return;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0))
return;
/* TODO: also check that the keyword contents match the spec! */
for (keyword_length = 0;
keyword_length < length && buffer[keyword_length] != 0;
++keyword_length)
/* Empty loop to find end of name */ ;
if (keyword_length > 79 || keyword_length < 1)
errmsg = "bad keyword";
/* zTXt must have some LZ data after the keyword, although it may expand to
* zero bytes; we need a '\0' at the end of the keyword, the compression type
* then the LZ data:
*/
else if (keyword_length + 3 > length)
errmsg = "truncated";
else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
errmsg = "unknown compression type";
else
{
png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
/* TODO: at present png_decompress_chunk imposes a single application
* level memory limit, this should be split to different values for iCCP
* and text chunks.
*/
if (png_decompress_chunk(png_ptr, length, keyword_length+2,
&uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
{
png_text text;
/* 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))
errmsg = "insufficient memory";
}
else
errmsg = png_ptr->zstream.msg;
}
if (errmsg != NULL)
png_chunk_benign_error(png_ptr, errmsg);
}
#else
# define png_handle_zTXt NULL
#endif /* READ_zTXt */
#ifdef PNG_READ_iTXt_SUPPORTED
static void
png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr)
{
png_uint_32 length = png_ptr->chunk_length;
png_const_charp errmsg = NULL;
png_bytep buffer;
png_uint_32 prefix_length;
png_debug(1, "in png_handle_iTXt");
#ifdef PNG_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_cache_max != 0)
{
if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_handle_error(png_ptr, "no space in chunk cache");
return;
}
}
#endif /* USER_LIMITS */
buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
if (buffer == NULL)
{
png_handle_error(png_ptr, "out of memory");
return;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0))
return;
/* First the keyword. */
for (prefix_length=0;
prefix_length < length && buffer[prefix_length] != 0;
++prefix_length)
/* Empty loop */ ;
/* Perform a basic check on the keyword length here. */
if (prefix_length > 79 || prefix_length < 1)
errmsg = "bad keyword";
/* Expect keyword, compression flag, compression type, language, translated
* keyword (both may be empty but are 0 terminated) then the text, which may
* be empty.
*/
else if (prefix_length + 5 > length)
errmsg = "truncated";
else if (buffer[prefix_length+1] == 0 ||
(buffer[prefix_length+1] == 1 &&
buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
{
int compressed = buffer[prefix_length+1] != 0;
png_uint_32 language_offset, translated_keyword_offset;
png_alloc_size_t uncompressed_length = 0;
/* Now the language tag */
prefix_length += 3;
language_offset = prefix_length;
for (; prefix_length < length && buffer[prefix_length] != 0;
++prefix_length)
/* Empty loop */ ;
/* WARNING: the length may be invalid here, this is checked below. */
translated_keyword_offset = ++prefix_length;
for (; prefix_length < length && buffer[prefix_length] != 0;
++prefix_length)
/* Empty loop */ ;
/* prefix_length should now be at the trailing '\0' of the translated
* keyword, but it may already be over the end. None of this arithmetic
* can overflow because chunks are at most 2^31 bytes long, but on 16-bit
* systems the available allocation may overflow.
*/
++prefix_length;
if (!compressed && prefix_length <= length)
uncompressed_length = length - prefix_length;
else if (compressed && 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))
errmsg = "insufficient memory";
}
}
else
errmsg = "bad compression info";
if (errmsg != NULL)
png_chunk_benign_error(png_ptr, errmsg);
}
#else
# define png_handle_iTXt NULL
#endif /* READ_iTXt */
/* UNSUPPORTED CHUNKS */
#define png_handle_sTER NULL
#define png_handle_fRAc NULL
#define png_handle_gIFg NULL
#define png_handle_gIFt NULL
#define png_handle_gIFx NULL
#define png_handle_dSIG NULL
/* IDAT has special treatment below */
#define png_handle_IDAT NULL
/******************************************************************************
* UNKNOWN HANDLING LOGIC
*
* There are three ways an unknown chunk may arise:
*
* 1) Chunks not in the spec.
* 2) Chunks in the spec where libpng support doesn't exist or has been compiled
* out. These are recognized, for a very small performance benefit at the
* cost of maintaining a png_known_chunks entry for each one.
* 3) Chunks supported by libpng which have been marked as 'unknown' by the
* application.
*
* Prior to 1.7.0 all three cases are handled the same way, in 1.7.0 some
* attempt is made to optimize (2) and (3) by storing flags in
* png_struct::known_unknown for chunks in the spec which have been marked for
* unknown handling.
*
* There are three things libpng can do with an unknown chunk, in order of
* preference:
*
* 1) If PNG_READ_USER_CHUNKS_SUPPORTED call an application supplied callback
* with all the chunk data. If this doesn't handle the chunk in prior
* versions of libpng the chunk would be stored if safe otherwise skipped.
* In 1.7.0 the specified chunk unknown handling is used.
* 2) If PNG_SAVE_UNKNOWN_CHUNKS_SUPPOPRTED the chunk may be saved in the
* info_struct (if there is one.)
* 3) The chunk can be skipped.
*
* In effect libpng tries each option in turn. (2) looks at any per-chunk
* unknown handling then, if one wasn't specified, the overall default.
*
* IHDR and IEND cannot be treated as unknown. PLTE and IDAT can. Prior to
* 1.7.0 they couldn't be skipped without a png_error. 1.7.0 adds an extension
* which allows any critical chunk to be skipped so long as IDAT is skipped; the
* logic for failing on critical chunks only applies if the image data is being
* processed.
*
* The default behavior is (3); unknown chunks are simply skipped. 1.7.0 uses
* this to optimize the read code when possible.
*
* In the read code PNG_READ_UNKNOWN_CHUNKS_SUPPORTED is set only if either (1)
* or (2) or both are supported.
*
*****************************************************************************/
#ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
static int
png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name)
{
png_byte chunk_string[5];
PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
return png_handle_as_unknown(png_ptr, chunk_string);
}
#endif /* SAVE_UNKNOWN_CHUNKS */
#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
/* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
static void
png_make_unknown_chunk(png_structrp png_ptr, png_unknown_chunkp chunk,
png_bytep data)
{
chunk->data = data;
chunk->size = png_ptr->chunk_length;
PNG_CSTRING_FROM_CHUNK(chunk->name, png_ptr->chunk_name);
/* 'mode' is a flag array, only three of the bottom four bits are public: */
chunk->location =
png_ptr->mode & (PNG_HAVE_IHDR+PNG_HAVE_PLTE+PNG_AFTER_IDAT);
}
/* Handle an unknown, or known but disabled, chunk */
void /* PRIVATE */
png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
png_bytep chunk_data)
{
png_debug(1, "in png_handle_unknown");
/* 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.
*
* 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 handling option: */
if (png_ptr->read_user_chunk_fn != NULL)
{
png_unknown_chunk unknown_chunk;
int ret;
/* Callback to user unknown chunk handler */
png_make_unknown_chunk(png_ptr, &unknown_chunk, chunk_data);
ret = png_ptr->read_user_chunk_fn(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)
return;
else if (ret < 0)
png_chunk_error(png_ptr, "application error");
/* Else: use the default handling. */
}
# endif /* READ_USER_CHUNKS */
# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
{
int keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
/* keep is currently just the per-chunk setting, if there was no
* setting change it to the global default now (note 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)))
# 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");
/* FALL THROUGH */
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);
/* FALL THROUGH */
case 0: /* no limit */
# endif /* USER_LIMITS */
/* Here when the limit isn't reached or when limits are
* compiled out; store the chunk.
*/
{
png_unknown_chunk unknown_chunk;
png_make_unknown_chunk(png_ptr, &unknown_chunk,
chunk_data);
png_set_unknown_chunks(png_ptr, info_ptr, &unknown_chunk,
1);
return;
}
# ifdef PNG_USER_LIMITS_SUPPORTED
}
# endif /* USER_LIMITS */
}
# else /* !SAVE_UNKNOWN_CHUNKS */
PNG_UNUSED(info_ptr)
# endif /* !SAVE_UNKNOWN_CHUNKS */
/* This is the 'skip' case, where the read callback (if any) returned 0 and
* the save code did not save the chunk.
*/
if (PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
png_chunk_error(png_ptr, "unhandled critical chunk");
}
#endif /* READ_UNKNOWN_CHUNKS */
/* This function is called to verify that a chunk name is valid.
* This function can't have the "critical chunk check" incorporated
* into it, since in the future we will need to be able to call user
* functions to handle unknown critical chunks after we check that
* the chunk name itself is valid.
*/
/* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
*
* ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
*/
static void
png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
{
int i;
png_debug(1, "in png_check_chunk_name");
for (i=1; i<=4; ++i)
{
int c = chunk_name & 0xff;
/* This is unrecoverable at present because it most likely indicates
* a broken stream.
*/
if (c < 65 || c > 122 || (c > 90 && c < 97))
png_chunk_error(png_ptr, "invalid chunk type");
chunk_name >>= 8;
}
}
/* This is the known chunk table; it contains an entry for each supported
* chunk.
*/
static const struct
{
void (*handle)(png_structrp png_ptr, png_infop info_ptr);
png_uint_32 name;
unsigned int before :5;
unsigned int after :5;
}
png_known_chunks[] =
/* To make the code easier to write the following defines are used, note that
* before_end should never trip - it would indicate that libpng attempted to
* read beyond the IEND chunk.
*
* 'within_IDAT' is used for IDAT chunks; PNG_AFTER_IDAT must not be set, but
* PNG_HAVE_IDAT may be set.
*/
#define before_end PNG_HAVE_IEND /* Should be impossible */
#define within_IDAT (before_end+PNG_AFTER_IDAT)
#define before_IDAT (within_IDAT+PNG_HAVE_IDAT)
#define before_PLTE (before_IDAT+PNG_HAVE_PLTE)
#define before_start (before_PLTE+PNG_HAVE_IHDR)
#define at_start 0
#define after_start PNG_HAVE_IHDR
#define after_PLTE (after_start+PNG_HAVE_PLTE) /* NOTE: PLTE optional */
#define after_IDAT (after_PLTE+PNG_AFTER_IDAT) /* NOTE: PLTE optional */
/* See pngchunk.h for how this works: */
#define PNG_CHUNK_END(n, c1, c2, c3, c4, before, after)\
{ png_handle_ ## n, png_ ##n, before, after }
#define PNG_CHUNK(n, c1, c2, c3, c4, before, after)\
PNG_CHUNK_END(n, c1, c2, c3, c4, before, after),
#define PNG_CHUNK_BEGIN(n, c1, c2, c3, c4, before, after)\
PNG_CHUNK_END(n, c1, c2, c3, c4, before, after),
{
# include "pngchunk.h"
};
#undef PNG_CHUNK_START
#undef PNG_CHUNK
#undef PNG_CHUNK_END
#define C_KNOWN ((sizeof png_known_chunks)/(sizeof png_known_chunks[0]))
/* See: scripts/chunkhash.c for code to generate this. This reads the same
* description file (pngchunk.h) as is included above. Whenever
* that file is changed chunkhash needs to be re-run to generate the lines
* following this comment.
*
* PNG_CHUNK_HASH modifes its argument and returns an index. png_chunk_index is
* a function which does the same thing without modifying the value of the
* argument. Both macro and function always return a valid index; to detect
* known chunks it is necessary to check png_known_chunks[index].name against
* the hashed name.
*/
static const png_byte png_chunk_lut[64] =
{
10, 20, 7, 3, 0, 23, 8, 0, 0, 11, 24, 0, 0, 0, 0, 4,
12, 0, 0, 0, 13, 0, 0, 0, 25, 0, 0, 0, 2, 0, 0, 0,
0, 6, 17, 0, 15, 0, 5, 19, 26, 0, 0, 0, 18, 0, 0, 9,
1, 0, 21, 0, 22, 14, 0, 0, 0, 0, 0, 0, 16, 0, 0, 0
};
#define PNG_CHUNK_HASH(n)\
png_chunk_lut[0x3f & (((n += n >> 2),n += n >> 8),n += n >> 16)]
static png_byte
png_chunk_index(png_uint_32 name)
{
name += name >> 2;
name += name >> 8;
name += name >> 16;
return png_chunk_lut[name & 0x3f];
}
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
/* Mark a known chunk to be handled as unknown. */
void /*PRIVATE*/
png_cache_known_unknown(png_structrp png_ptr, png_const_bytep add, int keep)
/* Update the png_struct::known_unknown bit cache which stores whether each
* known chunk should be treated as unknown.
*
* This cache exists to avoid doing the search loop on every chunk while
* handling chunks. This code is only ever used if unknown handling is
* invoked, and the loop is isolated code; the function is called from
* add_one_chunk in pngset.c once for each unknown and while this is
* happening no other code is being run in this thread.
*/
{
/* The cache only stores whether or not to handle the chunk; specifically
* whether or not keep is 0.
*/
png_uint_32 name = PNG_CHUNK_FROM_STRING(add);
debug(PNG_HANDLE_CHUNK_AS_DEFAULT == 0 && C_KNOWN <= 32);
/* But do not treat IHDR or IEND as unknown. This is historical; it
* always was this way, it's not clear if PLTE can always safely be
* treated as unknown, but it is allowed.
*/
if (name != png_IHDR && name != png_IEND)
{
png_byte i = png_chunk_index(name);
if (png_known_chunks[i].name == name)
{
{
if (keep != PNG_HANDLE_CHUNK_AS_DEFAULT)
{
png_ptr->known_unknown |= 1U << i;
# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
(keep == PNG_HANDLE_CHUNK_IF_SAFE &&
PNG_CHUNK_ANCILLARY(name)))
png_ptr->save_unknown |= 1U << i;
else /* PNG_HANDLE_CHUNK_NEVER || !SAFE */
png_ptr->save_unknown &= ~(1U << i);
# endif /* SAVE_UNKNOWN_CHUNKS */
}
else
png_ptr->known_unknown &= ~(1U << i);
}
}
/* else this is not a known chunk */
}
else /* 1.7.0: inform the app writer; */
png_app_warning(png_ptr, "IHDR, IEND cannot be treated as unknown");
}
#endif /* HANDLE_AS_UNKNOWN */
/* Handle chunk position requirements in a consistent way. The chunk must
* come after 'after' and before 'before', either of which may be 0. If it
* does the function returns true, if it does not an appropriate chunk error
* is issued; benign for non-critical chunks, fatal for critical ones.
*/
static int
png_handle_position(png_const_structrp png_ptr, unsigned int chunk)
{
unsigned int before = png_known_chunks[chunk].before;
unsigned int after = png_known_chunks[chunk].after;
# ifdef PNG_ERROR_TEXT_SUPPORTED
png_const_charp error = NULL;
# endif /* ERROR_TEXT */
/* PLTE is optional with all color types except PALETTE, so for the other
* color types clear it from the 'after' bits.
*
* TODO: find some better way of recognizing the case where there is a PLTE
* and it follows after_PLTE chunks (see the complex stuff in handle_PLTE.)
*/
if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
after &= PNG_BIC_MASK(PNG_HAVE_PLTE);
if ((png_ptr->mode & before) == 0 &&
(png_ptr->mode & after) == after)
return 1;
/* The error case; do before first (it is normally more important) */
# ifdef PNG_ERROR_TEXT_SUPPORTED
switch (before & -before) /* Lowest set bit */
{
case 0:
/* Check 'after'; only one bit set. */
switch (after)
{
case PNG_HAVE_IHDR:
error = "missing IHDR";
break;
case PNG_HAVE_PLTE:
error = "must occur after PLTE";
break;
case PNG_AFTER_IDAT:
error = "must come after IDAT";
break;
default:
impossible("invalid 'after' position");
}
break;
case PNG_HAVE_IHDR:
error = "must occur first";
break;
case PNG_HAVE_PLTE:
error = "must come before PLTE";
break;
case PNG_HAVE_IDAT:
error = "must come before IDAT";
break;
default:
impossible("invalid 'before' position");
}
# endif /* ERROR_TEXT */
png_chunk_report(png_ptr, error, PNG_CHUNK_CRITICAL(png_ptr->chunk_name) ?
PNG_CHUNK_FATAL : PNG_CHUNK_ERROR);
return 0;
}
/* This is the shared chunk handling function, used for both the sequential and
* progressive reader.
*/
png_chunk_op /* PRIVATE */
png_find_chunk_op(png_structrp png_ptr)
{
/* Given a chunk in png_struct::{chunk_name,chunk_length} validate the name
* and work out how it should be handled. This function checks the chunk
* location using png_struct::mode and will set the PNG_AFTER_IDAT bit if
* appropriate but otherwise makes no changes to the stream read state.
*
* png_chunk_skip Skip this chunk
* png_chunk_unknown This is an unknown chunk which can't be skipped;
* the unknown handler must be called with all the
* chunk data.
* png_chunk_process_all The caller must call png_chunk_handle to handle
* the chunk, when this call is made all the chunk
* data must be available to the handler.
* png_chunk_process_part The handler expects data in png_struct::zstream.
* {next,avail}_in and does not require all of the
* data at once (as png_read_process_IDAT).
*/
png_uint_32 chunk_name = png_ptr->chunk_name;
unsigned int mode = png_ptr->mode;
unsigned int index;
/* This function should never be called if IEND has been set:
*/
debug((mode & PNG_HAVE_IEND) == 0);
/* IDAT logic: we are only *after* IDAT when we start reading the first
* following (non-IDAT) chunk, this may already have been set in the IDAT
* handling code, but if IDAT is handled as unknown this doesn't happen.
*/
if (chunk_name != png_IDAT && (mode & PNG_HAVE_IDAT) != 0)
mode = png_ptr->mode |= PNG_AFTER_IDAT;
index = png_chunk_index(chunk_name);
if (png_known_chunks[index].name == chunk_name)
{
/* Known chunks have a position requirement; check it, badly positioned
* chunks that do not error out in png_handle_position are simply skipped.
*
* API CHANGE: libpng 1.7.0: prior versions of libpng did not check
* ordering requirements for known chunks where the support for reading
* them had been configured out of libpng. This seems dangerous; the
* user chunk callback could still see them and crash as a result.
*/
if (!png_handle_position(png_ptr, index))
return png_chunk_skip;
/* Do the mode update.
*
* API CHANGE 1.7.0: the 'HAVE' flags are now consistently set *before*
* the chunk is handled. Previously only IDAT was handled this way. This
* can only affect an app that was previously handling PLTE itself in a
* callback, however this seems to be impossible.
*/
switch (chunk_name)
{
case png_IHDR: png_ptr->mode |= PNG_HAVE_IHDR; break;
case png_PLTE: png_ptr->mode |= PNG_HAVE_PLTE; break;
case png_IDAT: png_ptr->mode |= PNG_HAVE_IDAT; break;
case png_IEND: png_ptr->mode |= PNG_HAVE_IEND; break;
default: break;
}
# ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
/* A known chunk may still be treated as unknown. Check for that. */
if (!((png_ptr->known_unknown >> index) & 1U))
# endif /* HANDLE_AS_UNKNOWN */
{
/* This is a known chunk that is not being treated as unknown. If
* it is IDAT then partial processing is done, otherwise (at present)
* the whole thing is processed in one shot
*
* TODO: this is a feature of the legacy use of the sequential read
* code in the handlers, fix this.
*/
if (chunk_name == png_IDAT)
return png_chunk_process_part;
/* Check for a known chunk where support has been compiled out of
* libpng. We know it cannot be a critical chunk; support for those
* cannot be removed.
*/
if (png_known_chunks[index].handle != NULL)
return png_chunk_process_all;
# ifdef PNG_READ_USER_CHUNKS_SUPPORTED
if (png_ptr->read_user_chunk_fn != NULL)
return png_chunk_unknown;
# endif /* READ_USER_CHUNKS */
# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
/* There is no per-chunk special handling set for this chunk
* (because of the test on known_unknown above) so only the
* default unknown handling behavior matters. We skip the chunk
* if the behavior is 'NEVER' or 'DEFAULT'. This is irrelevant
* if SAVE_UNKNOWN_CHUNKS is not supported.
*/
if (png_ptr->unknown_default > PNG_HANDLE_CHUNK_NEVER)
return png_chunk_unknown;
# endif /* SAVE_UNKNOWN_CHUNKS */
return png_chunk_skip;
}
# ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
else
{
/* Else this is a known chunk that is being treated as unknown. If
* there is a user callback the whole shebang is required:
*/
# ifdef PNG_READ_USER_CHUNKS_SUPPORTED
if (png_ptr->read_user_chunk_fn != NULL)
return png_chunk_unknown;
# endif /* READ_USER_CHUNKS */
/* No user callback, there is a possibility that we can skip this
* chunk:
*/
# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
if ((png_ptr->save_unknown >> index) & 1U)
return png_chunk_unknown;
# endif /* SAVE_UNKNOWN_CHUNKS */
/* If this is a critical chunk and IDAT is not being skipped then
* this is an error. The only possibility here is PLTE on an
* image which is palette mapped. If the app ignores this error
* then there will be a more definate one in png_handle_unknown.
*/
if (chunk_name == png_PLTE &&
png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
png_app_error(png_ptr, "skipping PLTE on palette image");
return png_chunk_skip;
}
# endif /* HANDLE_AS_UNKNOWN */
}
else /* unknown chunk */
{
/* The code above implicitly validates the chunk name, however if a chunk
* name/type is not recognized it is necessary to validate it to ensure
* that the PNG stream isn't hopelessly damaged:
*/
png_check_chunk_name(png_ptr, chunk_name);
# ifdef PNG_READ_USER_CHUNKS_SUPPORTED
if (png_ptr->read_user_chunk_fn != NULL)
return png_chunk_unknown;
# endif /* READ_USER_CHUNKS */
# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
/* There may be per-chunk handling, otherwise the default is used, this
* is the one place where the list needs to be searched:
*/
{
int keep = png_chunk_unknown_handling(png_ptr, chunk_name);
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(chunk_name)))
return png_chunk_unknown;
}
# endif /* SAVE_UNKNOWN_CHUNKS */
/* The chunk will be skipped so it must not be a critical chunk, unless
* IDATs are being skipped too.
*/
if (PNG_CHUNK_CRITICAL(chunk_name)
# ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
&& !png_IDATs_skipped(png_ptr)
# endif /* HANDLE_AS_UNKNOWN */
)
png_chunk_error(png_ptr, "unhandled critical chunk");
return png_chunk_skip;
}
}
void /* PRIVATE */
png_handle_chunk(png_structrp png_ptr, png_inforp info_ptr)
/* The chunk to handle is in png_struct::chunk_name,chunk_length.
*
* NOTE: at present it is only valid to call this after png_find_chunk_op
* has returned png_chunk_process_all and all the data is available for
* png_handle_chunk (via the libpng read callback.)
*/
{
png_uint_32 chunk_name = png_ptr->chunk_name;
unsigned int index = png_chunk_index(chunk_name);
/* So this must be true: */
affirm(png_known_chunks[index].name == chunk_name &&
png_known_chunks[index].handle != NULL);
png_known_chunks[index].handle(png_ptr, info_ptr);
}
void /* PRIVATE */
png_copy_row(png_const_structrp png_ptr, png_bytep dp)
/* Copy the row in row_buffer; this is the 'simple' case of png_combine_row
* where no adjustment to the pixel spacing is required.
*/
{
unsigned int pixel_depth =
# ifdef PNG_TRANSFORM_MECH_SUPPORTED
png_ptr->row_bit_depth * PNG_FORMAT_CHANNELS(png_ptr->row_format);
# else
PNG_PIXEL_DEPTH(*png_ptr);
# endif
png_alloc_size_t cb = png_ptr->width;
unsigned int remaining; /* remaining bits in a partial byte */
/* 1.7.0: png_combine_row used to copy data equal to the whole row even if
* the deinterlace transform had not been performed. This must be an error
* and possibly a security issue:
*/
if (png_ptr->interlaced)
cb = PNG_PASS_COLS(cb, png_ptr->pass);
/* Copy 'cb' pixels, but take care with the last byte because it may
* be partially written.
*/
switch (pixel_depth)
{
case 1: remaining = cb & 7U; cb >>= 3; break;
case 2: remaining = (cb << 1) & 6U; cb >>= 2; break;
case 4: remaining = (cb << 2) & 4U; cb >>= 1; break;
default: remaining = 0U; cb *= pixel_depth >> 3; break;
}
memcpy(dp, png_ptr->row_buffer, cb);
if (remaining > 0)
{
/* 'remaining' is the number of bits still to be copied. */
# ifdef PNG_READ_PACKSWAP_SUPPORTED
/* Format may be little endian; bits to copy in the bottom of 's' */
if ((png_ptr->row_format & PNG_FORMAT_FLAG_SWAPPED) != 0)
remaining = 0xffU << remaining;
else
# endif /* READ_PACKSWAP */
remaining = 0xffU >> remaining;
/* remaining is now the bits to *keep* from the destination byte */
dp[cb] = png_check_byte(png_ptr,
(dp[cb] & remaining) | (png_ptr->row_buffer[cb] & ~remaining));
}
}
#ifdef PNG_READ_DEINTERLACE_SUPPORTED
void /* PRIVATE */
png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
/* 1.7.0: API CHANGE: prior to 1.7.0 read de-interlace was done in two steps,
* the first would expand a narrow pass by replicating pixels according to
* the inter-pixel spacing of the pixels from the pass in the image. It did
* not take account of any offset from the start of the image row of the
* first pixel. The second step happened in png_combine_row where the result
* was merged into the output rows.
*
* In 1.7.0 this is no longer done. Instead all the work happens here. This
* is only an API change for the progressive reader if the app didn't call
* png_combine_row, but rather expected an expanded row. It's not obvious
* why any user of the progressive reader would want this, particularly given
* the weird non-offseting of the start in the original
* 'png_do_read_interlace'; the behavior was completely undocumented.
*
* In 1.7.0 png_combine_row does all the work. It expects a raw
* uncompressed, de-filtered, transformed row and it either copies it if:
*
* 1) It is not interlaced.
* 2) libpng isn't handling the de-interlace.
* 3) This is pass 7 (i.e. '6' using the libpng 0-based numbering).
*
* The input data comes from png_struct:
*
* png_struct::row_buffer; the row data
* png_struct::pass; the pass
* png_struct::row_number; the row number in the *image*
* png_struct::row_bit_depth,
* png_struct::row_format; the pixel format, if TRANSFORM_MECH, else:
* png_struct::bit_depth,
* png_struct::color_type; the pixel format otherwise
*
* The destination pointer (but not size) and how to handle intermediate
* passes are arguments to the API. 'display' is interpreted as:
*
* 0: only overwrite destination pixels that will correspond to the source
* pixel in the final image. 'sparkle' mode.
* 1: overwrite the corresponding destination pixel and all following
* pixels (horizontally and, eventually, vertically) that will come
* from *later* passes. 'block' mode.
*/
{
png_debug(1, "in png_combine_row");
/* Factor out the copy case first, the 'display' argument is irrelevant in
* these cases:
*/
if (!png_ptr->do_interlace || png_ptr->pass == 6)
{
png_copy_row(png_ptr, dp);
return;
}
else /* not a simple copy */
{
unsigned int pixel_depth =
# ifdef PNG_TRANSFORM_MECH_SUPPORTED
png_ptr->row_bit_depth * PNG_IMAGE_PIXEL_CHANNELS(png_ptr->row_format);
# else
PNG_PIXEL_DEPTH(*png_ptr);
# endif
const unsigned int pass = png_ptr->pass;
png_const_bytep sp = png_ptr->row_buffer;
png_uint_32 row_width = png_ptr->width; /* output width */
/* The first source pixel is written to PNG_PASS_START_COL of the
* destination:
*/
unsigned int dstart = PNG_PASS_START_COL(pass); /* in pixels */
/* Subsequent pixels are written PNG_PASS_COL_OFFSET further on: */
unsigned int doffset = PNG_PASS_COL_OFFSET(pass); /* in pixels */
/* In 'block' mode when dstart is 0 (PNG passes 1,3,5,7) the same pixel is
* replicated doffset times, when dstart is non-zero (PNG passes 2,4,6) it
* is replicated dstart times. For 'sparkle' mode only one copy of the
* pixel is written:
*/
unsigned int drep = display ? (dstart ? dstart : doffset) : 1;
/* The caller should have excluded the narrow cases: */
affirm(row_width > dstart);
row_width -= dstart;
/* So each source pixel sp[i] is written to:
*
* dp[dstart + i*doffset]..dp[dstart + i*doffset + (drep-1)]
*
* Until we get to row_width. This is easy for pixels that are 8 or more
* bits deep; whole bytes are read and written, slightly more difficult
* when pixel_depth * drep is at least 8 bits, because then dstart *
* pixel_depth will always be a whole byte and most complex when source
* and destination require sub-byte addressing.
*
* Cherry pick the easy cases:
*/
if (pixel_depth > 8)
{
affirm((pixel_depth & 7) == 0);
/* Convert to bytes: */
pixel_depth >>= 3;
dp += dstart * pixel_depth;
for (;;)
{
unsigned int c;
if (drep > row_width)
drep = row_width;
for (c=0; c<drep; ++c)
memcpy(dp, sp, pixel_depth), dp += pixel_depth;
if (doffset >= row_width)
break;
row_width -= doffset;
dp += (doffset-drep) * pixel_depth;
sp += pixel_depth;
}
}
else if (pixel_depth == 8)
{
/* Optimize the common 1-byte per pixel case (typical case for palette
* mapped images):
*/
dp += dstart;
for (;;)
{
if (drep > row_width)
drep = row_width;
memset(dp, *sp++, drep);
if (doffset >= row_width)
break;
row_width -= doffset;
dp += doffset;
}
}
else /* pixel_depth < 8 */
{
/* Pixels are 1, 2 or 4 bits in size. */
unsigned int spixel = *sp++;
unsigned int dbrep = pixel_depth * drep;
unsigned int spos = 0;
# ifdef PNG_READ_PACKSWAP_SUPPORTED
const int lsb =
(png_ptr->row_format & PNG_FORMAT_FLAG_SWAPPED) != 0;
# endif /* READ_PACKSWAP */
if (dbrep >= 8)
{
/* brep must be greater than 1, the destination does not require
* sub-byte addressing except, maybe, at the end.
*
* db is the count of bytes required to replicate the source pixel
* drep times.
*/
affirm((dbrep & 7) == 0);
dbrep >>= 3;
affirm((dstart * pixel_depth & 7) == 0);
dp += (dstart * pixel_depth) >> 3;
for (;;)
{
/* Fill a byte with copies of the next pixel: */
unsigned int spixel_rep = spixel;
# ifdef PNG_READ_PACKSWAP_SUPPORTED
if (lsb)
spixel_rep >>= spos;
else
# endif /* READ_PACKSWAP */
spixel_rep >>= (8-pixel_depth)-spos;
switch (pixel_depth)
{
case 1: spixel_rep &= 1; spixel_rep |= spixel_rep << 1;
/*FALL THROUGH*/
case 2: spixel_rep &= 3; spixel_rep |= spixel_rep << 2;
/*FALL THROUGH*/
case 4: spixel_rep &= 15; spixel_rep |= spixel_rep << 4;
/*FALL THROUGH*/
default:
break;
}
/* This may leave some pixels unwritten when there is a partial
* byte write required at the end:
*/
if (drep > row_width)
drep = row_width, dbrep = (pixel_depth * drep) >> 3;
memset(dp, spixel_rep, dbrep);
if (doffset >= row_width)
{
/* End condition; were all 'drep' pixels written at the end?
*/
drep = (pixel_depth * drep - (dbrep << 3));
if (drep)
{
unsigned int mask;
affirm(drep < 8);
dp += dbrep;
/* Set 'mask' to have 0's where *dp must be overwritten
* with spixel_rep:
*/
# ifdef PNG_READ_PACKSWAP_SUPPORTED
if (lsb)
mask = 0xff << drep;
else
# endif /* READ_PACKSWAP */
mask = 0xff >> drep;
*dp = png_check_byte(png_ptr,
(*dp & mask) | (spixel_rep & ~mask));
}
break;
}
row_width -= doffset;
dp += (doffset * pixel_depth) >> 3;
spos += pixel_depth;
if (spos == 8)
spixel = *sp++, spos = 0;
} /* for (;;) */
} /* pixel_depth * drep >= 8 */
else /* pixel_depth * drep < 8 */
{
/* brep may be 1, pixel_depth may be 1, 2 or 4, dbrep is the number
* of bits to set.
*/
unsigned int dpixel;
dstart *= pixel_depth;
dp += dstart >> 3;
dstart &= 7;
dpixel = *dp;
/* dpixel: current *dp, being modified
* dstart: bit offset within dpixel
* drep: pixel size to write (used as a check against row_width)
* doffset: pixel step to next written destination
*
* spixel: current *sp, being read, and:
* spixel_rep: current pixel, replicated to fill a byte
* spos: bit offset within spixel
*
* Set dbrep to a mask for the bits to set:
*/
dbrep = (1<<dbrep)-1;
for (;;)
{
/* Fill a byte with copies of the next pixel: */
unsigned int spixel_rep = spixel;
# ifdef PNG_READ_PACKSWAP_SUPPORTED
if (lsb)
spixel_rep >>= spos;
else
# endif /* READ_PACKSWAP */
spixel_rep >>= (8-pixel_depth)-spos;
switch (pixel_depth)
{
case 1: spixel_rep &= 1; spixel_rep |= spixel_rep << 1;
/*FALL THROUGH*/
case 2: spixel_rep &= 3; spixel_rep |= spixel_rep << 2;
/*FALL THROUGH*/
case 4: spixel_rep &= 15; spixel_rep |= spixel_rep << 4;
/*FALL THROUGH*/
default:
break;
}
/* This may leave some pixels unwritten when there is a partial
* byte write required at the end:
*/
if (drep > row_width)
drep = row_width, dbrep = (1<<(pixel_depth*drep))-1;
{
unsigned int mask;
/* Mask dbrep bits at dstart: */
# ifdef PNG_READ_PACKSWAP_SUPPORTED
if (lsb)
mask = dstart;
else
# endif /* READ_PACKSWAP */
mask = (8-pixel_depth)-dstart;
mask = dbrep << mask;
dpixel &= ~mask;
dpixel |= spixel_rep & mask;
}
if (doffset >= row_width)
{
*dp = png_check_byte(png_ptr, dpixel);
break;
}
row_width -= doffset;
dstart += doffset * pixel_depth;
if (dstart >= 8)
{
*dp = png_check_byte(png_ptr, dpixel);
dp += dstart >> 3;
dstart &= 7;
dpixel = *dp;
}
spos += pixel_depth;
if (spos == 8)
spixel = *sp++, spos = 0;
} /* for (;;) */
} /* pixel_depth * drep < 8 */
} /* pixel_depth < 8 */
} /* not a simple copy */
}
#endif /* READ_DEINTERLACE */
static void
png_read_filter_row_sub(png_alloc_size_t istop, unsigned int bpp,
png_bytep row, png_const_bytep prev_row)
{
png_alloc_size_t i;
png_bytep rp = row + bpp;
PNG_UNUSED(prev_row)
for (i = bpp; i < istop; i++)
{
*rp = PNG_BYTE(*rp + *(rp-bpp));
rp++;
}
}
static void
png_read_filter_row_up(png_alloc_size_t istop, unsigned int bpp,
png_bytep row, png_const_bytep prev_row)
{
png_alloc_size_t i;
png_bytep rp = row;
png_const_bytep pp = prev_row;
for (i = 0; i < istop; i++)
{
*rp = PNG_BYTE(*rp + *pp++);
rp++;
}
PNG_UNUSED(bpp)
}
static void
png_read_filter_row_avg(png_alloc_size_t istop, unsigned int bpp,
png_bytep row, png_const_bytep prev_row)
{
png_alloc_size_t i;
png_bytep rp = row;
png_const_bytep pp = prev_row;
istop -= bpp;
for (i = 0; i < bpp; i++)
{
*rp = PNG_BYTE(*rp + (*pp++ / 2));
rp++;
}
for (i = 0; i < istop; i++)
{
*rp = PNG_BYTE(*rp + (*pp++ + *(rp-bpp)) / 2);
rp++;
}
}
static void
png_read_filter_row_paeth_1byte_pixel(png_alloc_size_t row_bytes,
unsigned int bpp, png_bytep row, png_const_bytep prev_row)
{
png_bytep rp_end = row + row_bytes;
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;
}
PNG_UNUSED(bpp)
}
static void
png_read_filter_row_paeth_multibyte_pixel(png_alloc_size_t row_bytes,
unsigned int bpp, png_bytep row, png_const_bytep prev_row)
{
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 += row_bytes - 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, unsigned int bpp)
/* 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.
*/
{
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
}
/* This is an IDAT specific wrapper for png_zlib_inflate; the input is already
* in png_ptr->zstream.{next,avail}_in however the output uses the full
* capabilities of png_zlib_inflate, returning a byte count of bytes read.
* This is just a convenience for IDAT processing.
*
* NOTE: this function works just fine after the zstream has ended, it just
* fills the buffer with zeros (outputing an error message once.)
*/
static png_alloc_size_t
png_inflate_IDAT(png_structrp png_ptr, int finish,
/* OUTPUT: */ png_bytep output, png_alloc_size_t output_size)
{
/* Expect Z_OK if !finsh and Z_STREAM_END if finish; if Z_STREAM_END is
* delivered when finish is not set the IDAT stream is truncated, if Z_OK is
* delivered when finish is set this is harmless and indicates that the
* stream end code has not been read.
*
* finish should be set as follows:
*
* 0: not reading the last row, stream not expected to end
* 1: reading the last row, stream expected to end
* 2: looking for stream end after the last row has been read, expect no
* more output and stream end.
*/
png_alloc_size_t original_size = output_size;
int ret = Z_STREAM_END; /* In case it ended ok before. */
if (!png_ptr->zstream_ended)
{
png_const_bytep next_in = png_ptr->zstream.next_in;
png_uint_32 avail_in = png_ptr->zstream.avail_in;
ret = png_zlib_inflate(png_ptr, png_IDAT, finish,
&next_in, &avail_in, &output, &output_size/*remaining*/);
debug(next_in == png_ptr->zstream.next_in);
debug(avail_in == png_ptr->zstream.avail_in);
debug(output == png_ptr->zstream.next_out);
/* But zstream.avail_out may be truncated to uInt */
switch (ret)
{
case Z_STREAM_END:
/* The caller must set finish on the last row of the image (not
* the last row of the pass!)
*/
debug(png_ptr->zstream_ended);
if (!finish) /* early end */
break;
if (output_size > 0) /* incomplete read */
{
if (finish == 2) /* looking for end; it has been found */
return original_size - output_size;
/* else those bytes are really needed: */
break;
}
/* else: FALL THROUGH: success */
case Z_BUF_ERROR:
/* this is the success case: output or input is empty: */
original_size -= output_size; /* bytes written */
if (output_size > 0)
{
/* Some output still needed; if the next chunk is known
* to not be an IDAT then this is the truncation case.
*/
affirm(avail_in == 0);
if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
{
/* Zlib doesn't know we are out of data, so this must be
* done here:
*/
png_ptr->zstream_ended = 1;
break;
}
}
return original_size; /* bytes written */
default:
/* error */
break;
}
/* The 'ended' flag should always be set if we get here, the success
* cases where the LZ stream hasn't reached an end or an error leave
* the function at the return above.
*/
debug(png_ptr->zstream_ended);
}
/* This is the error return case; there was missing data, or an error.
* Either continue with a warning (once; hence the zstream_error flag)
* or png_error. The 'warn' setting has to be turned on and benign errors
* have to be turned off (made warnings.) The logic of this is that this
* is a pretty serious error; PNG is about images and we don't know that the
* image is correct.
*/
if (!png_ptr->zstream_error) /* first time */
{
if ((png_ptr->flags & PNG_FLAG_IDAT_ERRORS_WARN) != 0)
png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
else
png_chunk_error(png_ptr, png_ptr->zstream.msg);
/* And prevent the report about too many IDATs on streams with internal
* LZ errors:
*/
png_ptr->zstream_error = 1;
}
/* This is the error recovery case; fill the buffer with zeros. This is
* safe because it makes the filter byte 'NONE' and the row fairly innocent.
*/
memset(output, 0, output_size);
return original_size;
}
/* SHARED IDAT HANDLING.
*
* This is the 1.7+ common read code; shared by both the progressive and
* sequential readers.
*/
/* Initialize the row buffers, etc. */
void /* PRIVATE */
png_read_start_IDAT(png_structrp png_ptr)
{
# ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
/* This won't work at all if the app turned on unknown handling for IDAT
* chunks; the first IDAT has already been consumed!
*/
if (png_ptr->known_unknown & 1U)
png_error(png_ptr, "Attempt to read image with unknown IDAT");
# endif /* HANDLE_AS_UNKNOWN */
/* This is a missing read of the header information; we still haven't
* countered the first IDAT chunk. This can only happen in the sequential
* reader if the app didn't call png_read_info.
*/
if (png_ptr->chunk_name != png_IDAT)
png_error(png_ptr, "Missing call to png_read_info");
/* Two things need to happen: first work out the effect of any
* transformations (if supported) on the row size, second, allocate
* row_buffer and claim the zstream.
*/
png_init_row_info(png_ptr);
/* Now allocate the row buffer and, if that succeeds, claim the zstream.
*/
png_ptr->row_buffer = png_voidcast(png_bytep,
png_malloc(png_ptr, png_ptr->row_allocated_bytes));
if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
png_error(png_ptr, png_ptr->zstream.msg);
}
/* The process function gets called when there is some IDAT data to process
* and it just does the right thing with it. The zstream must have been claimed
* (owner png_IDAT) and the input data is in zstream.{next,avail}_in. The
* output next_{in,out} must not be changed by the caller; it is used
* internally.
*
* Result codes are as follows:
*
* png_row_incomplete: Insufficient IDAT data (from zstream) was present to
* process the next row. zstream.avail_in will be 0.
* png_row_process: A new row is available in the input buffer, it should be
* handled before the next call (if any) to this function.
* png_row_repeat: For interlaced images (only) this row is not in the pass,
* however the existing buffer may be displayed in lieu; if doing the
* 'blocky' (not 'sparkle') display the row should be displayed,
* otherwise treat as:
* png_row_skip: For interlaced images (only) the interlace pass has no data
* appropriate to this row, it should be skipped.
*
* In both of the two cases zstream.avail_in may be non-0, indicating that some
* IDAT data at zstream.next_in remains to be consumed. This data must be
* preserved and preset at the next call to the function.
*
* The function may also call png_error if an unrecoverable error occurs.
*/
png_row_op /*PRIVATE*/
png_read_process_IDAT(png_structrp png_ptr)
{
png_uint_32 width = png_ptr->width;
png_uint_32 row_number = png_ptr->row_number;
unsigned int pass = png_ptr->pass;
const unsigned int interlaced = png_ptr->interlaced != PNG_INTERLACE_NONE;
enum anonymous {
start_of_pass = 0U, /* at start of pass, no filter byte */
need_filter_byte = 1U, /* need the filter byte *after* this row */
need_row_bytes = 2U, /* reading the row */
processing_row = 3U, /* control returned to caller to process the row */
start_read_row_bytes, /* start read a row (internal) */
transform_row /* transform an unfiltered row (internal) */
} state = png_upcast(enum anonymous, png_ptr->row_state);
/* The caller is responsible for calling png_read_start_IDAT: */
affirm(png_ptr->zowner == png_IDAT);
for (;;) switch (state)
{
case processing_row:
/* When there was a previous row (not at the start of the image) the
* row number needs to be updated and, possibly, the pass number.
*/
if (++row_number == png_ptr->height)
{
affirm(interlaced && pass < 6); /* else too many calls */
/* Start a new pass: there never is a pending filter byte so it
* is always necessary to read the filter byte of the next row.
*/
png_ptr->pass = ++pass & 0x7;
row_number = 0;
}
png_ptr->row_number = row_number;
/* This is a new row, but it may not be in the pass data so it
* may be possible to simply return control to the caller to
* skip it or use the previous row as appropriate.
*/
if (interlaced)
{
png_uint_32 pass_width = width;
debug(pass <= 6);
/* This macro cannot overflow because the PNG width (and height)
* have already been checked to ensure that they are less than
* 2^31 (i.e. they are 31-bit values, not 32-bit values.)
*/
pass_width = PNG_PASS_COLS(pass_width, pass);
/* On average most rows are skipped, so do this first: */
if (pass_width == 0 ||
!PNG_ROW_IN_INTERLACE_PASS(row_number, pass))
{
/* Using the PNG specification numbering (pass+1), passes 1,
* 2, 4, 6 contribute to all the rows in 'block' interlaced
* filling mode. Pass 3 contributes to four rows (5,6,7,8),
* pass 5 to two rows (3,4 then 7,8) and pass 7 only to one
* (the one on which it is processed). have_row must be set
* appropriately; it is set when a row is processed (end of
* this function) and remains set while the 'block' mode of
* interlace handling should reuse the previous row for this
* row.
*
* Each pass row can be used in a fixed number of rows, shown
* in 'rows' below, the '*' indicates that the row is actually
* in the pass, the '^' that the previous '*' row is used in
* block display update and the '@' that the pass doesn't
* contribte at all to that row in block display mode:
*
* PASS: 0 1 2 3 4 5 6
* rows: 8 8 4 4 2 2 1
* 0: * * @ * @ * @
* 1: ^ ^ @ ^ @ ^ *
* 2: ^ ^ @ ^ * * @
* 3: ^ ^ @ ^ ^ ^ *
* 4: ^ ^ * * @ * @
* 5: ^ ^ ^ ^ @ ^ *
* 6: ^ ^ ^ ^ * * @
* 7: ^ ^ ^ ^ ^ ^ *
*
* The '@' signs are the interesting thing, since we know that
* this row isn't present in the pass data. Rewriting the
* above table with '1' for '@', little endian (i.e. row 0 at
* the LSB end):
*
* row: 76543210
* Pass 0: 00000000 0x00 [bit 3, 0x8 of row unset (always)]
* Pass 1: 00000000 0x00
* Pass 2: 00001111 0x0F [bit 2, 0x4 of row unset]
* Pass 3: 00000000 0x00
* Pass 4: 00110011 0x33 [bit 1, 0x2 of row unset]
* Pass 5: 00000000 0x00
* Pass 6: 01010101 0x55 [bit 0, 0x1 of row unset]
*
* PNG_PASS_BLOCK_SKIP(pass, row) can be written two ways;
*
* As a shift and a mask:
* (0x55330F00 >> ((pass >> 1) + (row & 7))) & ~pass & 1
*
* And, somewhat simpler, as a bit check on the low bits of
* row:
*
* ~((row) >> (3-(pass >> 1))) & ~pass & 1
*/
# define PNG_PASS_BLOCK_SKIP(pass, row)\
(~((row) >> (3U-((pass) >> 1))) & ~(pass) & 0x1U)
/* Hence: */
png_ptr->row_state = processing_row;
return pass_width == 0 || PNG_PASS_BLOCK_SKIP(pass,
row_number) ? png_row_skip : png_row_repeat;
} /* skipped row */
/* processed; fall through to start_read_row_bytes unless this is
* the first row in this pass, in which case the filter byte has
* not been read.
*/
if (row_number == PNG_PASS_START_ROW(pass))
{
state = start_of_pass;
continue;
}
} /* interlaced */
else /* not interlaced */ if (row_number == 0)
{
/* On the first row it is necessary to read a filter byte: */
state = start_of_pass;
continue; /* get the filter byte */
}
/* FALL THROUGH */
case start_read_row_bytes:
/* The row is always read into png_struct::row_buffer, however if the
* row filter (png_struct::next_filter) requires the previous row it
* is necessary to make sure that the read does not overwrite it (the
* previous row:)
*/
if (png_ptr->next_filter > PNG_FILTER_VALUE_SUB &&
!png_ptr->prev_in_alt)
{
/* Swap the buffers: */
png_bytep pb = png_ptr->alt_buffer;
/* Check this first before assignment, otherwise the same buffer
* will be stored in two members of png_struct and we will do a
* double free on an OOM in png_malloc:
*/
if (pb == NULL)
{
pb = png_voidcast(png_bytep,
png_malloc(png_ptr, png_ptr->row_allocated_bytes));
/* SECURITY: hide the heap contents: */
memset(pb, 0, png_ptr->row_allocated_bytes);
}
png_ptr->alt_buffer = png_ptr->row_buffer;
png_ptr->row_buffer = pb;
png_ptr->prev_in_alt = 1; /* until the filter has been undone */
}
/* Now png_ptr::zstream can be set, the code below sets avail_out each
* time, but next_out is used as a progress pointer so must be reset
* once at the start:
*/
png_ptr->zstream.next_out = png_ptr->row_buffer;
/* state = need_row_bytes; [not used below] */
/* FALL THROUGH */
case need_row_bytes:
{
png_alloc_size_t row_bytes;
png_uint_32 pass_width = width;
int last_pass_row;
png_byte row_filter;
if (interlaced)
pass_width = PNG_PASS_COLS(pass_width, pass);
/* Find out how many bytes are expected for this row, this relies on
* color_type, bit_depth and png_ptr->width having been validated
* for potential overflow in png_read_start_IDAT:
*/
row_bytes = PNG_ROWBYTES(PNG_PIXEL_DEPTH(*png_ptr), pass_width);
/* Check this every time, it's fast and safe: */
affirm(row_bytes <= png_ptr->row_allocated_bytes);
{ /* get expanded row bytes until the row is full */
png_alloc_size_t avail_out;
png_bytep next_out = png_ptr->zstream.next_out;
/* The affirm will fire if something tampers with next_out and
* sets it to somewhere other than row_buffer, or if it is not
* reset between passes or at the end of a row.
*/
avail_out = next_out - png_ptr->row_buffer; /*unsigned*/
affirm(avail_out < row_bytes);
avail_out = row_bytes - avail_out; /* 1..row_bytes */
{ /* expand (deflate) the available IDAT input */
int finish;
png_alloc_size_t cb;
{ /* calculate 'finish' and 'last_pass_row' */
png_uint_32 height = png_ptr->height;
/* last_pass_row indicates that this is the last row in
* this pass and, therefore, that the filter byte for the
* next row is irrelevant (or, indeed, may not be there if
* this is the last pass.) This is trival for
* non-interlaced images and more complex for interlaced
* ones.
*
* The test is optimized for the non-interlaced case.
*/
last_pass_row = row_number+1 >= height || (interlaced &&
PNG_LAST_PASS_ROW(row_number, pass, height));
/* Set 'finish' if this is the last row in the last pass
* of the image.
*/
finish = last_pass_row && (!interlaced || pass >=
PNG_LAST_PASS(width, height));
} /* calculate 'finish' and 'last_pass_row' */
cb = png_inflate_IDAT(png_ptr, finish, next_out, avail_out);
if (cb < avail_out)
{
png_ptr->row_state = need_row_bytes;
return png_row_incomplete;
}
} /* expand (inflate) the availble IDAT input */
} /* get expanded row bytes until the row is full */
/* The row is now complete; the return immediately above ended this
* function call if insufficient IDAT data was available.
*
* At this point all the required information to process the row has
* been read from the input stream and the original, filtered, row
* data is held in png_struct::row_buffer.
*
* png_struct::next_filter must contain the filter for *this* row,
* use this to reverse the filter:
*/
row_filter = png_ptr->next_filter;
if (row_filter > PNG_FILTER_VALUE_NONE)
{
const unsigned int bpp = (PNG_PIXEL_DEPTH(*png_ptr)+0x7)>>3;
/* This is checked in the read code below: */
debug(row_filter < PNG_FILTER_VALUE_LAST);
if (png_ptr->read_filter[0] == NULL)
png_init_filter_functions(png_ptr, bpp);
/* If the filter code needs the previous row, it must have been
* saved previously:
*/
affirm(row_filter <= PNG_FILTER_SUB ||
(png_ptr->prev_in_alt && png_ptr->alt_buffer != NULL));
png_ptr->read_filter[row_filter-1](row_bytes, bpp,
png_ptr->row_buffer, png_ptr->alt_buffer);
}
/* The row has been read and is now the 'previous' row for the
* next line, we need the next filter byte to determine whether
* this needs to be saved or can be overwritten if there are row
* transformations.
*/
png_ptr->prev_in_alt = 0;
if (last_pass_row)
{
/* No next line, so no need to store this row: */
png_ptr->next_filter = PNG_FILTER_VALUE_NONE;
state = transform_row;
continue;
}
} /* need_row_bytes */
state = need_filter_byte; /* as opposed to 'start_of_pass' */
/* FALL THROUGH */
case need_filter_byte: /* for the next row */
case start_of_pass: /* so the first byte is for the upcoming row */
{ /* read filter byte */
png_byte row_filter;
/* This is the filter byte that precedes the *next* row, or, at
* start_of_pass, the first row:
*/
png_alloc_size_t cb = png_inflate_IDAT(png_ptr, 0/*finish*/,
&png_ptr->next_filter, 1);
/* This can be temporary; it verifies the invariants on how
* png_inflate_IDAT updates the {next,avail}_out fields:
*/
#ifndef __COVERITY__ /* Suppress bogus Coverity complaint */
debug(png_ptr->zstream.avail_out == 1-cb &&
png_ptr->zstream.next_out == cb + &png_ptr->next_filter);
#endif
/* next_out points into png_struct, for security do this: */
png_ptr->zstream.next_out = NULL;
png_ptr->zstream.avail_out = 0;
/* One byte, so we either got it or have to get more input data: */
if (cb != 1)
{
affirm(cb == 0 && png_ptr->zstream.avail_in == 0);
png_ptr->row_state = state & 3U;
return png_row_incomplete;
}
/* Check the filter byte. */
row_filter = png_ptr->next_filter;
if (row_filter >= PNG_FILTER_VALUE_LAST)
png_chunk_error(png_ptr, "invalid PNG filter");
if (state == start_of_pass)
{
/* The filter is followed by the row data, but first check the
* filter byte; the spec requires that we invent an empty row
* if the first row of a pass requires it.
*/
if (row_filter >= PNG_FILTER_VALUE_UP)
{
/* x-0 == x, so do this optimization: */
if (row_filter == PNG_FILTER_VALUE_UP)
png_ptr->next_filter = PNG_FILTER_VALUE_NONE;
/* The Paeth predictor is always the preceding (leftwards)
* value, so this is the same as sub:
*/
else if (row_filter == PNG_FILTER_VALUE_PAETH)
png_ptr->next_filter = PNG_FILTER_VALUE_SUB;
else /* PNG_FILTER_VALUE_AVG */
{
/* It would be possible to 'invent' a new filter that did
* AVG using only the previous byte; it's 'SUB' of half the
* preceding value, but this seems pointless.
*/
png_bytep pb = png_ptr->alt_buffer;
if (pb == NULL)
{
png_ptr->alt_buffer = pb = png_voidcast(png_bytep,
png_malloc(png_ptr, png_ptr->row_allocated_bytes));
/* SECURITY: hide the heap contents: */
memset(pb, 0, png_ptr->row_allocated_bytes);
}
else
{
png_uint_32 pass_width = width;
png_alloc_size_t row_bytes;
if (interlaced)
pass_width = PNG_PASS_COLS(pass_width, pass);
/* Be safe here: this avoids a memory overwrite in a
* place where we are relying on previously validated
* values (NOTE: the row_bytes value may be truncated,
* that's a safe bug!)
*/
row_bytes = PNG_ROWBYTES(PNG_PIXEL_DEPTH(*png_ptr),
pass_width);
affirm(row_bytes <= png_ptr->row_allocated_bytes);
/* Just zero the bytes that are needed; */
memset(pb, 0, row_bytes);
}
png_ptr->prev_in_alt = 1;
}
} /* silly first line filter */
/* Proceed to read the row bytes: */
state = start_read_row_bytes;
continue;
} /* start_of_pass */
/* else state == need_filter_byte:
* png_struct::next_filter is the filter byte for the next row.
*/
} /* read filter byte */
case transform_row:
/* The entire row has been read and png_struct::next_filter is the
* filter for the next line or PNG_FILTER_VALUE_NONE if there is no
* next line. Do we have read transforms to perform?
*/
# ifdef PNG_TRANSFORM_MECH_SUPPORTED
if (png_ptr->transform_list != NULL)
{
unsigned int max_depth;
png_transform_control tc;
png_init_transform_control(&tc, png_ptr);
if (interlaced)
tc.width = PNG_PASS_COLS(width, pass);
else
tc.width = width;
tc.sp = tc.dp = png_ptr->row_buffer; /* assume overwrite ok */
/* Look at the filter for the *next* row, if it uses the previous
* row (this row) then row_buffer must be preserved.
*/
if (png_ptr->next_filter > PNG_FILTER_VALUE_SUB)
{
/* 'row_buffer' is the location of what will become the
* *previous* row. Depending on the transforms it may or may
* not also be the transformed row.
*/
tc.dp = png_ptr->alt_buffer; /* Transformed row */
if (tc.dp == NULL)
{
/* Lazy allocation; this is where alt_buffer is
* allocated if there *are* transforms to perform.
*/
png_ptr->alt_buffer = png_voidcast(png_bytep, tc.dp =
png_malloc(png_ptr, png_ptr->row_allocated_bytes));
}
}
/* Run the list. It is ok if it doesn't end up doing anything;
* this can happen with a lazy init, but that may mean that
* alt_buffer is allocated when it doesn't need to be.
*/
max_depth = png_run_transform_list_forwards(png_ptr, &tc);
/* This is too late, a memory overwrite has already happened, but
* it may still prevent exploits:
*/
affirm(max_depth <= png_ptr->row_max_pixel);
/* This check used to be performed in png_combine_row, above;
* do it here to detect the bug earlier on (this is quite common
* while making changes to the transform code!)
*/
affirm(png_ptr->row_format == tc.format &&
png_ptr->row_range == tc.range &&
png_ptr->row_bit_depth == tc.bit_depth);
# ifdef PNG_READ_GAMMA_SUPPORTED
affirm(png_ptr->row_gamma == tc.gamma);
# endif /* READ_GAMMA */
/* If the transformed data ended up in alt_buffer then swap it
* back to row_buffer; this allows the caller to always look in
* row_buffer for the output data.
*/
if (tc.sp == png_ptr->alt_buffer)
{
png_bytep pb = png_ptr->alt_buffer;
png_ptr->alt_buffer = png_ptr->row_buffer;
png_ptr->row_buffer = pb;
png_ptr->prev_in_alt = 1; /* else it is in row_buffer */
}
}
# endif
png_ptr->row_state = processing_row;
return png_row_process;
default:
impossible("bad row state");
} /* forever switch */
}
/* Complete reading of the IDAT chunks. This returns 0 if more data is to
* be read, 1 if the zlib stream has terminated. Call this routine with
* zstream.avail_in greater than zero unless there is no more input data.
* When zstream_avail_in is 0 on entry and the stream does not terminate
* an "IDAT truncated" error will be output.
*/
int /* PRIVATE */
png_read_finish_IDAT(png_structrp png_ptr)
{
enum
{
no_error = 0,
LZ_too_long,
IDAT_too_long,
IDAT_truncated
} error = no_error;
/* Release row_buffer and alt_buffer first; they can use considerable
* amounts of memory.
*/
if (png_ptr->row_buffer != NULL)
{
if (png_ptr->alt_buffer != NULL)
{
png_free(png_ptr, png_ptr->alt_buffer);
png_ptr->alt_buffer = NULL;
}
png_free(png_ptr, png_ptr->row_buffer);
png_ptr->row_buffer = NULL;
png_ptr->row_allocated_bytes = 0;
}
affirm(png_ptr->zowner == png_IDAT); /* else this should not be called */
/* 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->zstream_ended)
{
int end_of_IDAT = png_ptr->zstream.avail_in == 0;
png_byte b[1];
png_alloc_size_t cb = png_inflate_IDAT(png_ptr, 2/*finish*/, b, 1);
debug(png_ptr->zstream.avail_out == 1-cb &&
png_ptr->zstream.next_out == cb + b);
/* As above, for safety do this: */
png_ptr->zstream.next_out = NULL;
png_ptr->zstream.avail_out = 0;
/* No data is expected, either compressed or in the IDAT: */
if (cb != 0)
error = LZ_too_long;
else if (png_ptr->zstream.avail_in == 0 /* && cb == 0 */)
{
/* This is the normal case but there may still be some waiting codes
* (including the adler32 that follow the LZ77 end code; so we can
* have at least 5 bytes after the end of the row data before the
* end of the stream.
*/
if (!png_ptr->zstream_ended)
{
if (!end_of_IDAT)
return 0; /* keep reading, no detectable error yet */
error = IDAT_truncated;
}
/* Else there may still be an error; too much IDAT, but we can't
* tell.
*/
}
}
/* If there is still pending zstream input then there was too much IDAT
* data:
*/
if (!error && png_ptr->zstream.avail_in > 0)
error = IDAT_too_long;
/* Either this is the success case or an error has been detected and
* warned about.
*/
{
int ret = inflateEnd(&png_ptr->zstream);
/* In fact we expect this to always succeed, so it is a good idea to
* catch it in pre-release builds:
*/
debug_handled(ret == Z_OK);
if (ret != Z_OK)
{
/* This is just a warning; it's safe, and the zstream_error flag is
* not set.
*/
png_zstream_error(png_ptr, ret);
png_chunk_warning(png_ptr, png_ptr->zstream.msg);
}
}
/* Output an error message if required: */
if (error && !png_ptr->zstream_error)
{
switch (error)
{
case LZ_too_long:
png_benign_error(png_ptr, "compressed data too long");
break;
case IDAT_too_long:
png_benign_error(png_ptr, "uncompressed data too long");
break;
case IDAT_truncated:
png_benign_error(png_ptr, "data truncated");
break;
default:
case no_error: /* Satisfy the compiler */
break;
}
png_ptr->zstream_error = 1;
}
/* WARNING: leave {next,avail}_in set here, the progressive reader uses these
* to complete the PNG chunk CRC calculation.
*/
png_ptr->zstream_ended = 1;
png_ptr->zowner = 0;
return 1; /* end of stream */
}
/* Optional call to update the users info_ptr structure, can be used from both
* the progressive and sequential reader, but the app must call it.
*/
void PNGAPI
png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
{
png_debug(1, "in png_read_update_info");
if (png_ptr != NULL)
{
if (png_ptr->zowner != png_IDAT)
{
png_read_start_IDAT(png_ptr);
# ifdef PNG_READ_TRANSFORMS_SUPPORTED
png_read_transform_info(png_ptr, info_ptr);
# else
PNG_UNUSED(info_ptr)
# endif
}
/* New in 1.6.0 this avoids the bug of doing the initializations twice */
else
png_app_error(png_ptr,
"png_read_update_info/png_start_read_image: duplicate call");
}
}
#endif /* READ */
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