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pngrutil.c
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/* pngrutil.c - utilities to read a PNG file
*
* Last changed in libpng 1.5.10 [March 8, 2012]
* Copyright (c) 1998-2012 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"
#ifdef PNG_READ_SUPPORTED
#define png_strtod(p,a,b) strtod(a,b)
png_uint_32 PNGAPI
png_get_uint_31(png_structp png_ptr, png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf);
if (uval > PNG_UINT_31_MAX)
png_error(png_ptr, "PNG unsigned integer out of range");
return (uval);
}
#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
/* The following is a variation on the above for use with the fixed
* point values used for gAMA and cHRM. Instead of png_error it
* issues a warning and returns (-1) - an invalid value because both
* gAMA and cHRM use *unsigned* integers for fixed point values.
*/
#define PNG_FIXED_ERROR (-1)
static png_fixed_point /* PRIVATE */
png_get_fixed_point(png_structp png_ptr, png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf);
if (uval <= PNG_UINT_31_MAX)
return (png_fixed_point)uval; /* known to be in range */
/* The caller can turn off the warning by passing NULL. */
if (png_ptr != NULL)
png_warning(png_ptr, "PNG fixed point integer out of range");
return PNG_FIXED_ERROR;
}
#endif
#ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
/* NOTE: the read macros will obscure these definitions, so that if
* PNG_USE_READ_MACROS is set the library will not use them internally,
* but the APIs will still be available externally.
*
* The parentheses around "PNGAPI function_name" in the following three
* functions are necessary because they allow the macros to co-exist with
* these (unused but exported) functions.
*/
/* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
png_uint_32 (PNGAPI
png_get_uint_32)(png_const_bytep buf)
{
png_uint_32 uval =
((png_uint_32)(*(buf )) << 24) +
((png_uint_32)(*(buf + 1)) << 16) +
((png_uint_32)(*(buf + 2)) << 8) +
((png_uint_32)(*(buf + 3)) ) ;
return uval;
}
/* Grab a signed 32-bit integer from a buffer in big-endian format. The
* data is stored in the PNG file in two's complement format and there
* is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
* the following code does a two's complement to native conversion.
*/
png_int_32 (PNGAPI
png_get_int_32)(png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf);
if ((uval & 0x80000000) == 0) /* non-negative */
return uval;
uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */
return -(png_int_32)uval;
}
/* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
png_uint_16 (PNGAPI
png_get_uint_16)(png_const_bytep buf)
{
/* ANSI-C requires an int value to accomodate at least 16 bits so this
* works and allows the compiler not to worry about possible narrowing
* on 32 bit systems. (Pre-ANSI systems did not make integers smaller
* than 16 bits either.)
*/
unsigned int val =
((unsigned int)(*buf) << 8) +
((unsigned int)(*(buf + 1)));
return (png_uint_16)val;
}
#endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */
/* Read and check the PNG file signature */
void /* PRIVATE */
png_read_sig(png_structp png_ptr, png_infop info_ptr)
{
png_size_t num_checked, num_to_check;
/* Exit if the user application does not expect a signature. */
if (png_ptr->sig_bytes >= 8)
return;
num_checked = png_ptr->sig_bytes;
num_to_check = 8 - num_checked;
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
#endif
/* The signature must be serialized in a single I/O call. */
png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
png_ptr->sig_bytes = 8;
if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
{
if (num_checked < 4 &&
png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
png_error(png_ptr, "Not a PNG file");
else
png_error(png_ptr, "PNG file corrupted by ASCII conversion");
}
if (num_checked < 3)
png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
}
/* Read the chunk header (length + type name).
* Put the type name into png_ptr->chunk_name, and return the length.
*/
png_uint_32 /* PRIVATE */
png_read_chunk_header(png_structp png_ptr)
{
png_byte buf[8];
png_uint_32 length;
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
#endif
/* Read the length and the chunk name.
* This must be performed in a single I/O call.
*/
png_read_data(png_ptr, buf, 8);
length = png_get_uint_31(png_ptr, buf);
/* Put the chunk name into png_ptr->chunk_name. */
png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
png_debug2(0, "Reading %lx chunk, length = %lu",
(unsigned long)png_ptr->chunk_name, (unsigned long)length);
/* Reset the crc and run it over the chunk name. */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, buf + 4, 4);
/* Check to see if chunk name is valid. */
png_check_chunk_name(png_ptr, png_ptr->chunk_name);
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
#endif
return length;
}
/* Read data, and (optionally) run it through the CRC. */
void /* PRIVATE */
png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
{
if (png_ptr == NULL)
return;
png_read_data(png_ptr, buf, length);
png_calculate_crc(png_ptr, buf, length);
}
/* Optionally skip data and then check the CRC. Depending on whether we
* are reading a 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_structp png_ptr, png_uint_32 skip)
{
png_size_t i;
png_size_t istop = png_ptr->zbuf_size;
for (i = (png_size_t)skip; i > istop; i -= istop)
{
png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
}
if (i)
{
png_crc_read(png_ptr, png_ptr->zbuf, i);
}
if (png_crc_error(png_ptr))
{
if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name) ?
!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :
(png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
{
png_chunk_warning(png_ptr, "CRC error");
}
else
{
png_chunk_benign_error(png_ptr, "CRC error");
return (0);
}
return (1);
}
return (0);
}
/* Compare the CRC stored in the PNG file with that calculated by libpng from
* the data it has read thus far.
*/
int /* PRIVATE */
png_crc_error(png_structp png_ptr)
{
png_byte crc_bytes[4];
png_uint_32 crc;
int need_crc = 1;
if (PNG_CHUNK_ANCILLIARY(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)
{
crc = png_get_uint_32(crc_bytes);
return ((int)(crc != png_ptr->crc));
}
else
return (0);
}
#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
static png_size_t
png_inflate(png_structp png_ptr, png_bytep data, png_size_t size,
png_bytep output, png_size_t output_size)
{
png_size_t count = 0;
/* 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 forces access of the input data to be separated from
* at least some of the use by some period of time.
*/
png_ptr->zstream.next_in = data;
/* avail_in is set below from 'size' */
png_ptr->zstream.avail_in = 0;
while (1)
{
int ret, avail;
/* 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 o
* 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.
*/
if (png_ptr->zstream.avail_in == 0 && size > 0)
{
if (size <= ZLIB_IO_MAX)
{
/* The value is less than ZLIB_IO_MAX so the cast is safe: */
png_ptr->zstream.avail_in = (uInt)size;
size = 0;
}
else
{
png_ptr->zstream.avail_in = ZLIB_IO_MAX;
size -= ZLIB_IO_MAX;
}
}
/* Reset the output buffer each time round - we empty it
* after every inflate call.
*/
png_ptr->zstream.next_out = png_ptr->zbuf;
png_ptr->zstream.avail_out = png_ptr->zbuf_size;
ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
avail = png_ptr->zbuf_size - png_ptr->zstream.avail_out;
/* First copy/count any new output - but only if we didn't
* get an error code.
*/
if ((ret == Z_OK || ret == Z_STREAM_END) && avail > 0)
{
png_size_t space = avail; /* > 0, see above */
if (output != 0 && output_size > count)
{
png_size_t copy = output_size - count;
if (space < copy)
copy = space;
png_memcpy(output + count, png_ptr->zbuf, copy);
}
count += space;
}
if (ret == Z_OK)
continue;
/* Termination conditions - always reset the zstream, it
* must be left in inflateInit state.
*/
png_ptr->zstream.avail_in = 0;
inflateReset(&png_ptr->zstream);
if (ret == Z_STREAM_END)
return count; /* NOTE: may be zero. */
/* Now handle the error codes - the API always returns 0
* and the error message is dumped into the uncompressed
* buffer if available.
*/
# ifdef PNG_WARNINGS_SUPPORTED
{
png_const_charp msg;
if (png_ptr->zstream.msg != 0)
msg = png_ptr->zstream.msg;
else switch (ret)
{
case Z_BUF_ERROR:
msg = "Buffer error in compressed datastream";
break;
case Z_DATA_ERROR:
msg = "Data error in compressed datastream";
break;
default:
msg = "Incomplete compressed datastream";
break;
}
png_chunk_warning(png_ptr, msg);
}
# endif
/* 0 means an error - notice that this code simply ignores
* zero length compressed chunks as a result.
*/
return 0;
}
}
/*
* Decompress trailing data in a chunk. The assumption is that chunkdata
* 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).
*/
void /* PRIVATE */
png_decompress_chunk(png_structp png_ptr, int comp_type,
png_size_t chunklength,
png_size_t prefix_size, png_size_t *newlength)
{
/* The caller should guarantee this */
if (prefix_size > chunklength)
{
/* The recovery is to delete the chunk. */
png_warning(png_ptr, "invalid chunklength");
prefix_size = 0; /* To delete everything */
}
else if (comp_type == PNG_COMPRESSION_TYPE_BASE)
{
png_size_t expanded_size = png_inflate(png_ptr,
(png_bytep)(png_ptr->chunkdata + prefix_size),
chunklength - prefix_size,
0, /* output */
0); /* output size */
/* Now check the limits on this chunk - if the limit fails the
* compressed data will be removed, the prefix will remain.
*/
if (prefix_size >= (~(png_size_t)0) - 1 ||
expanded_size >= (~(png_size_t)0) - 1 - prefix_size
#ifdef PNG_USER_LIMITS_SUPPORTED
|| (png_ptr->user_chunk_malloc_max &&
(prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1))
#else
|| ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&
prefix_size + expanded_size >= PNG_USER_CHUNK_MALLOC_MAX - 1)
#endif
)
png_warning(png_ptr, "Exceeded size limit while expanding chunk");
/* If the size is zero either there was an error and a message
* has already been output (warning) or the size really is zero
* and we have nothing to do - the code will exit through the
* error case below.
*/
else if (expanded_size > 0)
{
/* Success (maybe) - really uncompress the chunk. */
png_size_t new_size = 0;
png_charp text = (png_charp)png_malloc_warn(png_ptr,
prefix_size + expanded_size + 1);
if (text != NULL)
{
png_memcpy(text, png_ptr->chunkdata, prefix_size);
new_size = png_inflate(png_ptr,
(png_bytep)(png_ptr->chunkdata + prefix_size),
chunklength - prefix_size,
(png_bytep)(text + prefix_size), expanded_size);
text[prefix_size + expanded_size] = 0; /* just in case */
if (new_size == expanded_size)
{
png_free(png_ptr, png_ptr->chunkdata);
png_ptr->chunkdata = text;
*newlength = prefix_size + expanded_size;
return; /* The success return! */
}
png_warning(png_ptr, "png_inflate logic error");
png_free(png_ptr, text);
}
else
png_warning(png_ptr, "Not enough memory to decompress chunk");
}
}
else /* if (comp_type != PNG_COMPRESSION_TYPE_BASE) */
{
PNG_WARNING_PARAMETERS(p)
png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d, comp_type);
png_formatted_warning(png_ptr, p, "Unknown compression type @1");
/* The recovery is to simply drop the data. */
}
/* Generic error return - leave the prefix, delete the compressed
* data, reallocate the chunkdata to remove the potentially large
* amount of compressed data.
*/
{
png_charp text = (png_charp)png_malloc_warn(png_ptr, prefix_size + 1);
if (text != NULL)
{
if (prefix_size > 0)
png_memcpy(text, png_ptr->chunkdata, prefix_size);
png_free(png_ptr, png_ptr->chunkdata);
png_ptr->chunkdata = text;
/* This is an extra zero in the 'uncompressed' part. */
*(png_ptr->chunkdata + prefix_size) = 0x00;
}
/* Ignore a malloc error here - it is safe. */
}
*newlength = prefix_size;
}
#endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */
/* Read and check the IDHR chunk */
void /* PRIVATE */
png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
png_byte buf[13];
png_uint_32 width, height;
int bit_depth, color_type, compression_type, filter_type;
int interlace_type;
png_debug(1, "in png_handle_IHDR");
if (png_ptr->mode & PNG_HAVE_IHDR)
png_error(png_ptr, "Out of place IHDR");
/* Check the length */
if (length != 13)
png_error(png_ptr, "Invalid IHDR chunk");
png_ptr->mode |= PNG_HAVE_IHDR;
png_crc_read(png_ptr, buf, 13);
png_crc_finish(png_ptr, 0);
width = png_get_uint_31(png_ptr, buf);
height = png_get_uint_31(png_ptr, buf + 4);
bit_depth = buf[8];
color_type = buf[9];
compression_type = buf[10];
filter_type = buf[11];
interlace_type = buf[12];
/* Set internal variables */
png_ptr->width = width;
png_ptr->height = height;
png_ptr->bit_depth = (png_byte)bit_depth;
png_ptr->interlaced = (png_byte)interlace_type;
png_ptr->color_type = (png_byte)color_type;
#ifdef PNG_MNG_FEATURES_SUPPORTED
png_ptr->filter_type = (png_byte)filter_type;
#endif
png_ptr->compression_type = (png_byte)compression_type;
/* Find number of channels */
switch (png_ptr->color_type)
{
default: /* invalid, png_set_IHDR calls png_error */
case PNG_COLOR_TYPE_GRAY:
case PNG_COLOR_TYPE_PALETTE:
png_ptr->channels = 1;
break;
case PNG_COLOR_TYPE_RGB:
png_ptr->channels = 3;
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
png_ptr->channels = 2;
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
png_ptr->channels = 4;
break;
}
/* Set up other useful info */
png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
png_ptr->channels);
png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
png_debug1(3, "channels = %d", png_ptr->channels);
png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
color_type, interlace_type, compression_type, filter_type);
}
/* Read and check the palette */
void /* PRIVATE */
png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
png_color palette[PNG_MAX_PALETTE_LENGTH];
int num, i;
#ifdef PNG_POINTER_INDEXING_SUPPORTED
png_colorp pal_ptr;
#endif
png_debug(1, "in png_handle_PLTE");
if (!(png_ptr->mode & PNG_HAVE_IHDR))
png_error(png_ptr, "Missing IHDR before PLTE");
else if (png_ptr->mode & PNG_HAVE_IDAT)
{
png_warning(png_ptr, "Invalid PLTE after IDAT");
png_crc_finish(png_ptr, length);
return;
}
else if (png_ptr->mode & PNG_HAVE_PLTE)
png_error(png_ptr, "Duplicate PLTE chunk");
png_ptr->mode |= PNG_HAVE_PLTE;
if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
{
png_warning(png_ptr,
"Ignoring PLTE chunk in grayscale PNG");
png_crc_finish(png_ptr, length);
return;
}
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
{
png_crc_finish(png_ptr, length);
return;
}
#endif
if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
{
if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
{
png_warning(png_ptr, "Invalid palette chunk");
png_crc_finish(png_ptr, length);
return;
}
else
{
png_error(png_ptr, "Invalid palette chunk");
}
}
num = (int)length / 3;
#ifdef PNG_POINTER_INDEXING_SUPPORTED
for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
{
png_byte buf[3];
png_crc_read(png_ptr, buf, 3);
pal_ptr->red = buf[0];
pal_ptr->green = buf[1];
pal_ptr->blue = buf[2];
}
#else
for (i = 0; i < num; i++)
{
png_byte buf[3];
png_crc_read(png_ptr, buf, 3);
/* Don't depend upon png_color being any order */
palette[i].red = buf[0];
palette[i].green = buf[1];
palette[i].blue = buf[2];
}
#endif
/* If we actually need the PLTE chunk (ie for a paletted image), we do
* whatever the normal CRC configuration tells us. However, if we
* have an RGB image, the PLTE can be considered ancillary, so
* we will act as though it is.
*/
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
#endif
{
png_crc_finish(png_ptr, 0);
}
#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).
*/
if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
{
if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
{
png_chunk_benign_error(png_ptr, "CRC error");
}
else
{
png_chunk_warning(png_ptr, "CRC error");
return;
}
}
/* 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
png_set_PLTE(png_ptr, info_ptr, palette, num);
#ifdef PNG_READ_tRNS_SUPPORTED
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
{
if (png_ptr->num_trans > (png_uint_16)num)
{
png_warning(png_ptr, "Truncating incorrect tRNS chunk length");
png_ptr->num_trans = (png_uint_16)num;
}
if (info_ptr->num_trans > (png_uint_16)num)
{
png_warning(png_ptr, "Truncating incorrect info tRNS chunk length");
info_ptr->num_trans = (png_uint_16)num;
}
}
}
#endif
}
void /* PRIVATE */
png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
png_debug(1, "in png_handle_IEND");
if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
{
png_error(png_ptr, "No image in file");
}
png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
if (length != 0)
{
png_warning(png_ptr, "Incorrect IEND chunk length");
}
png_crc_finish(png_ptr, length);
PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
}
#ifdef PNG_READ_gAMA_SUPPORTED
void /* PRIVATE */
png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
png_fixed_point igamma;
png_byte buf[4];
png_debug(1, "in png_handle_gAMA");
if (!(png_ptr->mode & PNG_HAVE_IHDR))
png_error(png_ptr, "Missing IHDR before gAMA");
else if (png_ptr->mode & PNG_HAVE_IDAT)
{
png_warning(png_ptr, "Invalid gAMA after IDAT");
png_crc_finish(png_ptr, length);
return;
}
else if (png_ptr->mode & PNG_HAVE_PLTE)
/* Should be an error, but we can cope with it */
png_warning(png_ptr, "Out of place gAMA chunk");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
#ifdef PNG_READ_sRGB_SUPPORTED
&& !(info_ptr->valid & PNG_INFO_sRGB)
#endif
)
{
png_warning(png_ptr, "Duplicate gAMA chunk");
png_crc_finish(png_ptr, length);
return;
}
if (length != 4)
{
png_warning(png_ptr, "Incorrect gAMA chunk length");
png_crc_finish(png_ptr, length);
return;
}
png_crc_read(png_ptr, buf, 4);
if (png_crc_finish(png_ptr, 0))
return;
igamma = png_get_fixed_point(NULL, buf);
/* Check for zero gamma or an error. */
if (igamma <= 0)
{
png_warning(png_ptr,
"Ignoring gAMA chunk with out of range gamma");
return;
}
# ifdef PNG_READ_sRGB_SUPPORTED
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
{
if (PNG_OUT_OF_RANGE(igamma, 45500, 500))
{
PNG_WARNING_PARAMETERS(p)
png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_fixed, igamma);
png_formatted_warning(png_ptr, p,
"Ignoring incorrect gAMA value @1 when sRGB is also present");
return;
}
}
# endif /* PNG_READ_sRGB_SUPPORTED */
# ifdef PNG_READ_GAMMA_SUPPORTED
/* Gamma correction on read is supported. */
png_ptr->gamma = igamma;
# endif
/* And set the 'info' structure members. */
png_set_gAMA_fixed(png_ptr, info_ptr, igamma);
}
#endif
#ifdef PNG_READ_sBIT_SUPPORTED
void /* PRIVATE */
png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
png_size_t truelen;
png_byte buf[4];
png_debug(1, "in png_handle_sBIT");
buf[0] = buf[1] = buf[2] = buf[3] = 0;
if (!(png_ptr->mode & PNG_HAVE_IHDR))
png_error(png_ptr, "Missing IHDR before sBIT");
else if (png_ptr->mode & PNG_HAVE_IDAT)
{
png_warning(png_ptr, "Invalid sBIT after IDAT");
png_crc_finish(png_ptr, length);
return;
}
else if (png_ptr->mode & PNG_HAVE_PLTE)
{
/* Should be an error, but we can cope with it */
png_warning(png_ptr, "Out of place sBIT chunk");
}
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
{
png_warning(png_ptr, "Duplicate sBIT chunk");
png_crc_finish(png_ptr, length);
return;
}
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
truelen = 3;
else
truelen = (png_size_t)png_ptr->channels;
if (length != truelen || length > 4)
{
png_warning(png_ptr, "Incorrect sBIT chunk length");
png_crc_finish(png_ptr, length);
return;
}
png_crc_read(png_ptr, buf, truelen);
if (png_crc_finish(png_ptr, 0))
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));
}
#endif
#ifdef PNG_READ_cHRM_SUPPORTED
void /* PRIVATE */
png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
png_byte buf[32];
png_fixed_point x_white, y_white, x_red, y_red, x_green, y_green, x_blue,
y_blue;
png_debug(1, "in png_handle_cHRM");
if (!(png_ptr->mode & PNG_HAVE_IHDR))
png_error(png_ptr, "Missing IHDR before cHRM");
else if (png_ptr->mode & PNG_HAVE_IDAT)
{
png_warning(png_ptr, "Invalid cHRM after IDAT");
png_crc_finish(png_ptr, length);
return;
}
else if (png_ptr->mode & PNG_HAVE_PLTE)
/* Should be an error, but we can cope with it */
png_warning(png_ptr, "Out of place cHRM chunk");
if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM)
# ifdef PNG_READ_sRGB_SUPPORTED
&& !(info_ptr->valid & PNG_INFO_sRGB)
# endif
)
{
png_warning(png_ptr, "Duplicate cHRM chunk");
png_crc_finish(png_ptr, length);
return;
}
if (length != 32)
{
png_warning(png_ptr, "Incorrect cHRM chunk length");
png_crc_finish(png_ptr, length);
return;
}
png_crc_read(png_ptr, buf, 32);
if (png_crc_finish(png_ptr, 0))
return;
x_white = png_get_fixed_point(NULL, buf);
y_white = png_get_fixed_point(NULL, buf + 4);
x_red = png_get_fixed_point(NULL, buf + 8);
y_red = png_get_fixed_point(NULL, buf + 12);
x_green = png_get_fixed_point(NULL, buf + 16);
y_green = png_get_fixed_point(NULL, buf + 20);
x_blue = png_get_fixed_point(NULL, buf + 24);
y_blue = png_get_fixed_point(NULL, buf + 28);
if (x_white == PNG_FIXED_ERROR ||
y_white == PNG_FIXED_ERROR ||
x_red == PNG_FIXED_ERROR ||
y_red == PNG_FIXED_ERROR ||
x_green == PNG_FIXED_ERROR ||
y_green == PNG_FIXED_ERROR ||
x_blue == PNG_FIXED_ERROR ||
y_blue == PNG_FIXED_ERROR)
{
png_warning(png_ptr, "Ignoring cHRM chunk with negative chromaticities");
return;
}
#ifdef PNG_READ_sRGB_SUPPORTED
if ((info_ptr != NULL) && (info_ptr->valid & PNG_INFO_sRGB))
{
if (PNG_OUT_OF_RANGE(x_white, 31270, 1000) ||
PNG_OUT_OF_RANGE(y_white, 32900, 1000) ||
PNG_OUT_OF_RANGE(x_red, 64000, 1000) ||
PNG_OUT_OF_RANGE(y_red, 33000, 1000) ||
PNG_OUT_OF_RANGE(x_green, 30000, 1000) ||
PNG_OUT_OF_RANGE(y_green, 60000, 1000) ||
PNG_OUT_OF_RANGE(x_blue, 15000, 1000) ||
PNG_OUT_OF_RANGE(y_blue, 6000, 1000))
{
PNG_WARNING_PARAMETERS(p)