/* pngrutil.c - utilities to read a PNG file * * Copyright (c) 2018-2024 Cosmin Truta * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson * Copyright (c) 1996-1997 Andreas Dilger * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc. * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer * and license in png.h * * This file contains routines that are only called from within * libpng itself during the course of reading an image.
*/
#include"pngpriv.h"
#ifdef PNG_READ_SUPPORTED
#ifdef PNG_READ_INTERLACING_SUPPORTED /* Arrays to facilitate interlacing - use pass (0 - 6) as index. */
/* Start of interlace block */ staticconst png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; /* Offset to next interlace block */ staticconst png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; /* Start of interlace block in the y direction */ staticconst png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1}; /* Offset to next interlace block in the y direction */ staticconst png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
/* TODO: Move these arrays to a common utility module to avoid duplication. */ #endif
if (uval > PNG_UINT_31_MAX)
png_error(png_ptr, "PNG unsigned integer out of range");
return uval;
}
#ifdefined(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)
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 a signed 32-bit integer from a buffer in big-endian format. The * data is stored in the PNG file in two's complement format and there * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore * the following code does a two's complement to native conversion.
*/
png_int_32 (PNGAPI
png_get_int_32)(png_const_bytep buf)
{
png_uint_32 uval = png_get_uint_32(buf); if ((uval & 0x80000000) == 0) /* non-negative */ return (png_int_32)uval;
uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */ if ((uval & 0x80000000) == 0) /* no overflow */ return -(png_int_32)uval; /* The following has to be safe; this function only gets called on PNG data * and if we get here that data is invalid. 0 is the most safe value and * if not then an attacker would surely just generate a PNG with 0 instead.
*/ return 0;
}
/* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
png_uint_16 (PNGAPI
png_get_uint_16)(png_const_bytep buf)
{ /* ANSI-C requires an int value to accommodate at least 16 bits so this * works and allows the compiler not to worry about possible narrowing * on 32-bit systems. (Pre-ANSI systems did not make integers smaller * than 16 bits either.)
*/ unsignedint val =
((unsignedint)(*buf) << 8) +
((unsignedint)(*(buf + 1)));
return (png_uint_16)val;
}
#endif/* READ_INT_FUNCTIONS */
/* Read and check the PNG file signature */ void/* PRIVATE */
png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
{
size_t num_checked, num_to_check;
/* Exit if the user application does not expect a signature. */ if (png_ptr->sig_bytes >= 8) return;
/* The signature must be serialized in a single I/O call. */
png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
png_ptr->sig_bytes = 8;
if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check) != 0)
{ if (num_checked < 4 &&
png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4) != 0)
png_error(png_ptr, "Not a PNG file"); else
png_error(png_ptr, "PNG file corrupted by ASCII conversion");
} if (num_checked < 3)
png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
}
/* Read the chunk header (length + type name). * Put the type name into png_ptr->chunk_name, and return the length.
*/
png_uint_32 /* PRIVATE */
png_read_chunk_header(png_structrp png_ptr)
{
png_byte buf[8];
png_uint_32 length;
/* 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);
/* 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;
/* 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;
/* Compare the CRC stored in the PNG file with that calculated by libpng from * the data it has read thus far.
*/ int/* PRIVATE */
png_crc_error(png_structrp png_ptr)
{
png_byte crc_bytes[4];
png_uint_32 crc; int need_crc = 1;
if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
{ if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
(PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
need_crc = 0;
}
#ifdefined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\ defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\ defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\ defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED) /* Manage the read buffer; this simply reallocates the buffer if it is not small * enough (or if it is not allocated). The routine returns a pointer to the * buffer; if an error occurs and 'warn' is set the routine returns NULL, else * it will call png_error (via png_malloc) on failure. (warn == 2 means * 'silent').
*/ static png_bytep
png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
{
png_bytep buffer = png_ptr->read_buffer;
/* 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.
*/ staticint
png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
{ if (png_ptr->zowner != 0)
{ char msg[64];
PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner); /* So the message that results is "<chunk> using zstream"; this is an * internal error, but is very useful for debugging. i18n requirements * are minimal.
*/
(void)png_safecat(msg, (sizeof msg), 4, " using zstream"); #if PNG_RELEASE_BUILD
png_chunk_warning(png_ptr, msg);
png_ptr->zowner = 0; #else
png_chunk_error(png_ptr, msg); #endif
}
/* Implementation note: unlike 'png_deflate_claim' this internal function * does not take the size of the data as an argument. Some efficiency could * be gained by using this when it is known *if* the zlib stream itself does * not record the number; however, this is an illusion: the original writer * of the PNG may have selected a lower window size, and we really must * follow that because, for systems with with limited capabilities, we * would otherwise reject the application's attempts to use a smaller window * size (zlib doesn't have an interface to say "this or lower"!). * * inflateReset2 was added to zlib 1.2.4; before this the window could not be * reset, therefore it is necessary to always allocate the maximum window * size with earlier zlibs just in case later compressed chunks need it.
*/
{ int ret; /* zlib return code */ #if ZLIB_VERNUM >= 0x1240 int window_bits = 0;
/* Set this for safety, just in case the previous owner left pointers to * memory allocations.
*/
png_ptr->zstream.next_in = NULL;
png_ptr->zstream.avail_in = 0;
png_ptr->zstream.next_out = NULL;
png_ptr->zstream.avail_out = 0;
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
{ #if ZLIB_VERNUM >= 0x1240
ret = inflateReset2(&png_ptr->zstream, window_bits); #else
ret = inflateReset(&png_ptr->zstream); #endif
}
else
{ #if ZLIB_VERNUM >= 0x1240
ret = inflateInit2(&png_ptr->zstream, window_bits); #else
ret = inflateInit(&png_ptr->zstream); #endif
if (ret == Z_OK)
png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
}
#ifdef PNG_DISABLE_ADLER32_CHECK_SUPPORTED if (((png_ptr->options >> PNG_IGNORE_ADLER32) & 3) == PNG_OPTION_ON) /* Turn off validation of the ADLER32 checksum in IDAT chunks */
ret = inflateValidate(&png_ptr->zstream, 0); #endif
if (ret == Z_OK)
png_ptr->zowner = owner;
else
png_zstream_error(png_ptr, ret);
return ret;
}
#ifdef window_bits # undef window_bits #endif
}
#if ZLIB_VERNUM >= 0x1240 /* Handle the start of the inflate stream if we called inflateInit2(strm,0); * in this case some zlib versions skip validation of the CINFO field and, in * certain circumstances, libpng may end up displaying an invalid image, in * contrast to implementations that call zlib in the normal way (e.g. libpng * 1.5).
*/ int/* PRIVATE */
png_zlib_inflate(png_structrp png_ptr, int flush)
{ if (png_ptr->zstream_start && png_ptr->zstream.avail_in > 0)
{ if ((*png_ptr->zstream.next_in >> 4) > 7)
{
png_ptr->zstream.msg = "invalid window size (libpng)"; return Z_DATA_ERROR;
}
#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED #ifdefined(PNG_READ_zTXt_SUPPORTED) || defined (PNG_READ_iTXt_SUPPORTED) /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to * allow the caller to do multiple calls if required. If the 'finish' flag is * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and * Z_OK or Z_STREAM_END will be returned on success. * * The input and output sizes are updated to the actual amounts of data consumed * or written, not the amount available (as in a z_stream). The data pointers * are not changed, so the next input is (data+input_size) and the next * available output is (output+output_size).
*/ staticint
png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish, /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr, /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
{ if (png_ptr->zowner == owner) /* Else not claimed */
{ int ret;
png_alloc_size_t avail_out = *output_size_ptr;
png_uint_32 avail_in = *input_size_ptr;
/* zlib can't necessarily handle more than 65535 bytes at once (i.e. it * can't even necessarily handle 65536 bytes) because the type uInt is * "16 bits or more". Consequently it is necessary to chunk the input to * zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the * maximum value that can be stored in a uInt.) It is possible to set * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have * a performance advantage, because it reduces the amount of data accessed * at each step and that may give the OS more time to page it in.
*/
png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input); /* avail_in and avail_out are set below from 'size' */
png_ptr->zstream.avail_in = 0;
png_ptr->zstream.avail_out = 0;
/* Read directly into the output if it is available (this is set to * a local buffer below if output is NULL).
*/ if (output != NULL)
png_ptr->zstream.next_out = output;
do
{
uInt avail;
Byte local_buffer[PNG_INFLATE_BUF_SIZE];
/* zlib INPUT BUFFER */ /* The setting of 'avail_in' used to be outside the loop; by setting it * inside it is possible to chunk the input to zlib and simply rely on * zlib to advance the 'next_in' pointer. This allows arbitrary * amounts of data to be passed through zlib at the unavoidable cost of * requiring a window save (memcpy of up to 32768 output bytes) * every ZLIB_IO_MAX input bytes.
*/
avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
avail = ZLIB_IO_MAX;
if (avail_in < avail)
avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
/* 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);
}
/* zlib inflate call */ /* In fact 'avail_out' may be 0 at this point, that happens at the end * of the read when the final LZ end code was not passed at the end of * the previous chunk of input data. Tell zlib if we have reached the * end of the output buffer.
*/
ret = PNG_INFLATE(png_ptr, avail_out > 0 ? Z_NO_FLUSH :
(finish ? Z_FINISH : Z_SYNC_FLUSH));
} while (ret == Z_OK);
/* For safety kill the local buffer pointer now */ if (output == NULL)
png_ptr->zstream.next_out = NULL;
/* Claw back the 'size' and 'remaining_space' byte counts. */
avail_in += png_ptr->zstream.avail_in;
avail_out += png_ptr->zstream.avail_out;
/* Update the input and output sizes; the updated values are the amount * consumed or written, effectively the inverse of what zlib uses.
*/ if (avail_out > 0)
*output_size_ptr -= avail_out;
if (avail_in > 0)
*input_size_ptr -= avail_in;
/* Ensure png_ptr->zstream.msg is set (even in the success case!) */
png_zstream_error(png_ptr, ret); return ret;
}
else
{ /* This is a bad internal error. The recovery assigns to the zstream msg * pointer, which is not owned by the caller, but this is safe; it's only * used on errors!
*/
png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed"); return Z_STREAM_ERROR;
}
}
/* * Decompress trailing data in a chunk. The assumption is that read_buffer * points at an allocated area holding the contents of a chunk with a * trailing compressed part. What we get back is an allocated area * holding the original prefix part and an uncompressed version of the * trailing part (the malloc area passed in is freed).
*/ staticint
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;
if (ret == Z_STREAM_END)
{ /* Use 'inflateReset' here, not 'inflateReset2' because this * preserves the previously decided window size (otherwise it would * be necessary to store the previous window size.) In practice * this doesn't matter anyway, because png_inflate will call inflate * with Z_FINISH in almost all cases, so the window will not be * maintained.
*/ if (inflateReset(&png_ptr->zstream) == Z_OK)
{ /* Because of the limit checks above we know that the new, * expanded, size will fit in a size_t (let alone an * png_alloc_size_t). Use png_malloc_base here to avoid an * extra OOM message.
*/
png_alloc_size_t new_size = *newlength;
png_alloc_size_t buffer_size = prefix_size + new_size +
(terminate != 0);
png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
buffer_size));
if (text != NULL)
{
memset(text, 0, buffer_size);
ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
png_ptr->read_buffer + prefix_size, &lzsize,
text + prefix_size, newlength);
if (ret == Z_STREAM_END)
{ if (new_size == *newlength)
{ if (terminate != 0)
text[prefix_size + *newlength] = 0;
if (prefix_size > 0)
memcpy(text, png_ptr->read_buffer, prefix_size);
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;
}
}
elseif (ret == Z_OK)
ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
/* Free the text pointer (this is the old read_buffer on * success)
*/
png_free(png_ptr, text);
/* This really is very benign, but it's still an error because * the extra space may otherwise be used as a Trojan Horse.
*/ if (ret == Z_STREAM_END &&
chunklength - prefix_size != lzsize)
png_chunk_benign_error(png_ptr, "extra compressed data");
}
else
{ /* Out of memory allocating the buffer */
ret = Z_MEM_ERROR;
png_zstream_error(png_ptr, Z_MEM_ERROR);
}
}
else
{ /* inflateReset failed, store the error message */
png_zstream_error(png_ptr, ret);
ret = PNG_UNEXPECTED_ZLIB_RETURN;
}
}
elseif (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;
#ifdef PNG_READ_iCCP_SUPPORTED /* Perform a partial read and decompress, producing 'avail_out' bytes and * reading from the current chunk as required.
*/ staticint
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);
if (png_ptr->zstream.avail_out == 0)
{
uInt avail = ZLIB_IO_MAX; if (avail > *out_size)
avail = (uInt)*out_size;
*out_size -= avail;
png_ptr->zstream.avail_out = avail;
}
/* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all * the available output is produced; this allows reading of truncated * streams.
*/
ret = PNG_INFLATE(png_ptr, *chunk_bytes > 0 ?
Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
} while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
*out_size += png_ptr->zstream.avail_out;
png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
/* Ensure the error message pointer is always set: */
png_zstream_error(png_ptr, ret); return ret;
}
/* Read and check the palette */ void/* PRIVATE */
png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_color palette[PNG_MAX_PALETTE_LENGTH]; int max_palette_length, num, i; #ifdef PNG_POINTER_INDEXING_SUPPORTED
png_colorp pal_ptr; #endif
png_debug(1, "in png_handle_PLTE");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
/* Moved to before the 'after IDAT' check below because otherwise duplicate * PLTE chunks are potentially ignored (the spec says there shall not be more * than one PLTE, the error is not treated as benign, so this check trumps * the requirement that PLTE appears before IDAT.)
*/ elseif ((png_ptr->mode & PNG_HAVE_PLTE) != 0)
png_chunk_error(png_ptr, "duplicate");
elseif ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{ /* This is benign because the non-benign error happened before, when an * IDAT was encountered in a color-mapped image with no PLTE.
*/
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place"); return;
}
png_ptr->mode |= PNG_HAVE_PLTE;
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "ignored in grayscale PNG"); return;
}
if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
png_chunk_benign_error(png_ptr, "invalid");
else
png_chunk_error(png_ptr, "invalid");
return;
}
/* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
num = (int)length / 3;
/* If the palette has 256 or fewer entries but is too large for the bit * depth, we don't issue an error, to preserve the behavior of previous * libpng versions. We silently truncate the unused extra palette entries * here.
*/ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
max_palette_length = (1 << png_ptr->bit_depth); else
max_palette_length = PNG_MAX_PALETTE_LENGTH;
if (num > max_palette_length)
num = max_palette_length;
#ifdef PNG_POINTER_INDEXING_SUPPORTED for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
{
png_byte buf[3];
png_crc_read(png_ptr, buf, 3);
pal_ptr->red = buf[0];
pal_ptr->green = buf[1];
pal_ptr->blue = buf[2];
} #else for (i = 0; i < num; i++)
{
png_byte buf[3];
png_crc_read(png_ptr, buf, 3); /* Don't depend upon png_color being any order */
palette[i].red = buf[0];
palette[i].green = buf[1];
palette[i].blue = buf[2];
} #endif
/* If we actually need the PLTE chunk (ie for a paletted image), we do * whatever the normal CRC configuration tells us. However, if we * have an RGB image, the PLTE can be considered ancillary, so * we will act as though it is.
*/ #ifndef PNG_READ_OPT_PLTE_SUPPORTED if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) #endif
{
png_crc_finish(png_ptr, (png_uint_32) (length - (unsignedint)num * 3));
}
#ifndef PNG_READ_OPT_PLTE_SUPPORTED elseif (png_crc_error(png_ptr) != 0) /* Only if we have a CRC error */
{ /* If we don't want to use the data from an ancillary chunk, * we have two options: an error abort, or a warning and we * ignore the data in this chunk (which should be OK, since * it's considered ancillary for a RGB or RGBA image). * * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the * chunk type to determine whether to check the ancillary or the critical * flags.
*/ if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE) == 0)
{ if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) != 0) return;
else
png_chunk_error(png_ptr, "CRC error");
}
/* Otherwise, we (optionally) emit a warning and use the chunk. */ elseif ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0)
png_chunk_warning(png_ptr, "CRC error");
} #endif
/* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its * own copy of the palette. This has the side effect that when png_start_row * is called (this happens after any call to png_read_update_info) the * info_ptr palette gets changed. This is extremely unexpected and * confusing. * * Fix this by not sharing the palette in this way.
*/
png_set_PLTE(png_ptr, info_ptr, palette, num);
/* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before * IDAT. Prior to 1.6.0 this was not checked; instead the code merely * checked the apparent validity of a tRNS chunk inserted before PLTE on a * palette PNG. 1.6.0 attempts to rigorously follow the standard and * therefore does a benign error if the erroneous condition is detected *and* * cancels the tRNS if the benign error returns. The alternative is to * amend the standard since it would be rather hypocritical of the standards * maintainers to ignore it.
*/ #ifdef PNG_READ_tRNS_SUPPORTED if (png_ptr->num_trans > 0 ||
(info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
{ /* Cancel this because otherwise it would be used if the transforms * require it. Don't cancel the 'valid' flag because this would prevent * detection of duplicate chunks.
*/
png_ptr->num_trans = 0;
if (info_ptr != NULL)
info_ptr->num_trans = 0;
png_chunk_benign_error(png_ptr, "tRNS must be after");
} #endif
#ifdef PNG_READ_hIST_SUPPORTED if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
png_chunk_benign_error(png_ptr, "hIST must be after"); #endif
#ifdef PNG_READ_bKGD_SUPPORTED if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
png_chunk_benign_error(png_ptr, "bKGD must be after"); #endif
}
/* If a colorspace error has already been output skip this chunk */ if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0) return;
/* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect * this.
*/ if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) != 0)
{
png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
png_colorspace_sync(png_ptr, info_ptr);
png_chunk_benign_error(png_ptr, "too many profiles"); return;
}
#ifdef PNG_READ_iCCP_SUPPORTED void/* PRIVATE */
png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) /* Note: this does not properly handle profiles that are > 64K under DOS */
{
png_const_charp errmsg = NULL; /* error message output, or no error */ int finished = 0; /* crc checked */
png_debug(1, "in png_handle_iCCP");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
/* Consistent with all the above colorspace handling an obviously *invalid* * chunk is just ignored, so does not invalidate the color space. An * alternative is to set the 'invalid' flags at the start of this routine * and only clear them in they were not set before and all the tests pass.
*/
/* The keyword must be at least one character and there is a * terminator (0) byte and the compression method byte, and the * 'zlib' datastream is at least 11 bytes.
*/ if (length < 14)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too short"); return;
}
/* If a colorspace error has already been output skip this chunk */ if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
{
png_crc_finish(png_ptr, length); return;
}
/* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect * this.
*/ if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
{
uInt read_length, keyword_length; char keyword[81];
/* Find the keyword; the keyword plus separator and compression method * bytes can be at most 81 characters long.
*/
read_length = 81; /* maximum */ if (read_length > length)
read_length = (uInt)length;
/* The minimum 'zlib' stream is assumed to be just the 2 byte header, * 5 bytes minimum 'deflate' stream, and the 4 byte checksum.
*/ if (length < 11)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too short"); return;
}
/* 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;
png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
png_ptr->zstream.avail_in = read_length;
(void)png_inflate_read(png_ptr, local_buffer,
(sizeof local_buffer), &length, profile_header, &size,
0/*finish: don't, because the output is too small*/);
if (size == 0)
{ /* We have the ICC profile header; do the basic header checks.
*/
png_uint_32 profile_length = png_get_uint_32(profile_header);
if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
keyword, profile_length) != 0)
{ /* The length is apparently ok, so we can check the 132 * byte header.
*/ if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
keyword, profile_length, profile_header,
png_ptr->color_type) != 0)
{ /* Now read the tag table; a variable size buffer is * needed at this point, allocate one for the whole * profile. The header check has already validated * that none of this stuff will overflow.
*/
png_uint_32 tag_count =
png_get_uint_32(profile_header + 128);
png_bytep profile = png_read_buffer(png_ptr,
profile_length, 2/*silent*/);
if (profile != NULL)
{
memcpy(profile, profile_header,
(sizeof profile_header));
/* Still expect a buffer error because we expect * there to be some tag data!
*/ if (size == 0)
{ if (png_icc_check_tag_table(png_ptr,
&png_ptr->colorspace, keyword, profile_length,
profile) != 0)
{ /* The profile has been validated for basic * security issues, so read the whole thing in.
*/
size = profile_length - (sizeof profile_header)
- 12 * tag_count;
/* But otherwise allow extra data: */ elseif (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;
# ifdefined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0 /* Check for a match against sRGB */
png_icc_set_sRGB(png_ptr,
&png_ptr->colorspace, profile,
png_ptr->zstream.adler); # endif
/* Steal the profile for info_ptr. */ if (info_ptr != NULL)
{
png_free_data(png_ptr, info_ptr,
PNG_FREE_ICCP, 0);
#ifdef PNG_READ_sPLT_SUPPORTED void/* PRIVATE */
png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) /* Note: this does not properly handle chunks that are > 64K under DOS */
{
png_bytep entry_start, buffer;
png_sPLT_t new_palette;
png_sPLT_entryp pp;
png_uint_32 data_length; int entry_size, i;
png_uint_32 skip = 0;
png_uint_32 dl;
size_t max_dl;
png_debug(1, "in png_handle_sPLT");
#ifdef PNG_USER_LIMITS_SUPPORTED if (png_ptr->user_chunk_cache_max != 0)
{ if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length); return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_warning(png_ptr, "No space in chunk cache for sPLT");
png_crc_finish(png_ptr, length); return;
}
} #endif
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
#ifdef PNG_MAX_MALLOC_64K if (length > 65535U)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too large to fit in memory"); return;
} #endif
buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/); if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory"); return;
}
/* WARNING: this may break if size_t is less than 32 bits; it is assumed * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a * potential breakage point if the types in pngconf.h aren't exactly right.
*/
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, skip) != 0) return;
buffer[length] = 0;
for (entry_start = buffer; *entry_start; entry_start++) /* Empty loop to find end of name */ ;
++entry_start;
/* A sample depth should follow the separator, and we should be on it */ if (length < 2U || entry_start > buffer + (length - 2U))
{
png_warning(png_ptr, "malformed sPLT chunk"); return;
}
new_palette.depth = *entry_start++;
entry_size = (new_palette.depth == 8 ? 6 : 10); /* This must fit in a png_uint_32 because it is derived from the original * chunk data length.
*/
data_length = length - (png_uint_32)(entry_start - buffer);
/* Integrity-check the data length */ if ((data_length % (unsignedint)entry_size) != 0)
{
png_warning(png_ptr, "sPLT chunk has bad length"); return;
}
elseif (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{ if ((png_ptr->mode & PNG_HAVE_PLTE) == 0)
{ /* TODO: is this actually an error in the ISO spec? */
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of place"); return;
}
/* TODO: this is a horrible side effect in the palette case because the * png_struct ends up with a pointer to the tRNS buffer owned by the * png_info. Fix this.
*/
png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
&(png_ptr->trans_color));
} #endif
/* We convert the index value into RGB components so that we can allow * arbitrary RGB values for background when we have transparency, and * so it is easy to determine the RGB values of the background color * from the info_ptr struct.
*/ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
background.index = buf[0];
if (info_ptr != NULL && info_ptr->num_palette != 0)
{ if (buf[0] >= info_ptr->num_palette)
{
png_chunk_benign_error(png_ptr, "invalid index"); return;
}
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory"); return;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0) != 0) return;
buffer[length] = 0; /* Null terminate the last string */
png_debug(3, "Finding end of pCAL purpose string"); for (buf = buffer; *buf; buf++) /* Empty loop */ ;
endptr = buffer + length;
/* We need to have at least 12 bytes after the purpose string * in order to get the parameter information.
*/ if (endptr - buf <= 12)
{
png_chunk_benign_error(png_ptr, "invalid"); return;
}
png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
X0 = png_get_int_32((png_bytep)buf+1);
X1 = png_get_int_32((png_bytep)buf+5);
type = buf[9];
nparams = buf[10];
units = buf + 11;
png_debug(3, "Checking pCAL equation type and number of parameters"); /* Check that we have the right number of parameters for known * equation types.
*/ if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
(type == PNG_EQUATION_BASE_E && nparams != 3) ||
(type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
(type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
{
png_chunk_benign_error(png_ptr, "invalid parameter count"); return;
}
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;
}
}
#ifdef PNG_READ_tEXt_SUPPORTED /* Note: this does not properly handle chunks that are > 64K under DOS */ void/* PRIVATE */
png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_text text_info;
png_bytep buffer;
png_charp key;
png_charp text;
png_uint_32 skip = 0;
png_debug(1, "in png_handle_tEXt");
#ifdef PNG_USER_LIMITS_SUPPORTED if (png_ptr->user_chunk_cache_max != 0)
{ if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length); return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "no space in chunk cache"); return;
}
} #endif
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
png_ptr->mode |= PNG_AFTER_IDAT;
#ifdef PNG_MAX_MALLOC_64K if (length > 65535U)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "too large to fit in memory"); return;
} #endif
if (png_set_text_2(png_ptr, info_ptr, &text_info, 1) != 0)
png_warning(png_ptr, "Insufficient memory to process text chunk");
} #endif
#ifdef PNG_READ_zTXt_SUPPORTED /* Note: this does not correctly handle chunks that are > 64K under DOS */ void/* PRIVATE */
png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_const_charp errmsg = NULL;
png_bytep buffer;
png_uint_32 keyword_length;
png_debug(1, "in png_handle_zTXt");
#ifdef PNG_USER_LIMITS_SUPPORTED if (png_ptr->user_chunk_cache_max != 0)
{ if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length); return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "no space in chunk cache"); return;
}
} #endif
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
png_ptr->mode |= PNG_AFTER_IDAT;
/* Note, "length" is sufficient here; we won't be adding * a null terminator later.
*/
buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory"); return;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0) != 0) return;
/* TODO: also check that the keyword contents match the spec! */ for (keyword_length = 0;
keyword_length < length && buffer[keyword_length] != 0;
++keyword_length) /* Empty loop to find end of name */ ;
/* 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:
*/ elseif (keyword_length + 3 > length)
errmsg = "truncated";
/* TODO: at present png_decompress_chunk imposes a single application * level memory limit, this should be split to different values for iCCP * and text chunks.
*/ if (png_decompress_chunk(png_ptr, length, keyword_length+2,
&uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
{
png_text text;
if (png_ptr->read_buffer == NULL)
errmsg="Read failure in png_handle_zTXt"; else
{ /* It worked; png_ptr->read_buffer now looks like a tEXt chunk * except for the extra compression type byte and the fact that * it isn't necessarily '\0' terminated.
*/
buffer = png_ptr->read_buffer;
buffer[uncompressed_length+(keyword_length+2)] = 0;
if (errmsg != NULL)
png_chunk_benign_error(png_ptr, errmsg);
} #endif
#ifdef PNG_READ_iTXt_SUPPORTED /* Note: this does not correctly handle chunks that are > 64K under DOS */ void/* PRIVATE */
png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
png_const_charp errmsg = NULL;
png_bytep buffer;
png_uint_32 prefix_length;
png_debug(1, "in png_handle_iTXt");
#ifdef PNG_USER_LIMITS_SUPPORTED if (png_ptr->user_chunk_cache_max != 0)
{ if (png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length); return;
}
if (--png_ptr->user_chunk_cache_max == 1)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "no space in chunk cache"); return;
}
} #endif
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
png_ptr->mode |= PNG_AFTER_IDAT;
if (buffer == NULL)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "out of memory"); return;
}
png_crc_read(png_ptr, buffer, length);
if (png_crc_finish(png_ptr, 0) != 0) return;
/* First the keyword. */ for (prefix_length=0;
prefix_length < length && buffer[prefix_length] != 0;
++prefix_length) /* Empty loop */ ;
/* Perform a basic check on the keyword length here. */ if (prefix_length > 79 || prefix_length < 1)
errmsg = "bad keyword";
/* Expect keyword, compression flag, compression type, language, translated * keyword (both may be empty but are 0 terminated) then the text, which may * be empty.
*/ elseif (prefix_length + 5 > length)
errmsg = "truncated";
/* 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;
/* 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;
num_frames = png_get_uint_31(png_ptr, data);
num_plays = png_get_uint_31(png_ptr, data + 4);
/* the set function will do error checking on num_frames */
didSet = png_set_acTL(png_ptr, info_ptr, num_frames, num_plays); if (didSet != 0)
png_ptr->mode |= PNG_HAVE_acTL;
}
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
{
png_error(png_ptr, "Missing IHDR before fcTL");
} elseif ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{ /* for any frames other then the first this message may be misleading, * but correct. PNG_HAVE_IDAT is unset before the frame head is read
* i can't think of a better message */
png_warning(png_ptr, "Invalid fcTL after IDAT skipped");
png_crc_finish(png_ptr, length-4); return;
} elseif ((png_ptr->mode & PNG_HAVE_fcTL) != 0)
{
png_warning(png_ptr, "Duplicate fcTL within one frame skipped");
png_crc_finish(png_ptr, length-4); return;
} elseif (length != 26)
{
png_warning(png_ptr, "fcTL with invalid length skipped");
png_crc_finish(png_ptr, length-4); return;
}
if (png_ptr->num_frames_read == 0 && (x_offset != 0 || y_offset != 0))
{
png_warning(png_ptr, "fcTL for the first frame must have zero offset"); return;
}
if (info_ptr != NULL)
{ if (png_ptr->num_frames_read == 0 &&
(width != info_ptr->width || height != info_ptr->height))
{
png_warning(png_ptr, "size in first frame's fcTL must match " "the size in IHDR"); return;
}
/* The set function will do more error checking */
png_set_next_frame_fcTL(png_ptr, info_ptr, width, height,
x_offset, y_offset, delay_num, delay_den,
dispose_op, blend_op);
/* This function is only called from png_read_end(), png_read_info(), * and png_push_read_chunk() which means that: * - the user doesn't want to read this frame * - or this is an out-of-place fdAT
* in either case it is safe to ignore the chunk with a warning */
png_warning(png_ptr, "ignoring fdAT chunk");
png_crc_finish(png_ptr, length - 4);
PNG_UNUSED(info_ptr)
}
if (length <= limit)
{
PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name); /* The following is safe because of the PNG_SIZE_MAX init above */
png_ptr->unknown_chunk.size = (size_t)length/*SAFE*/; /* 'mode' is a flag array, only the bottom four bits matter here */
png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
if (length == 0)
png_ptr->unknown_chunk.data = NULL;
else
{ /* Do a 'warn' here - it is handled below. */
png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
png_malloc_warn(png_ptr, length));
}
}
if (png_ptr->unknown_chunk.data == NULL && length > 0)
{ /* This is benign because we clean up correctly */
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits"); return 0;
}
/* Handle an unknown, or known but disabled, chunk */ void/* PRIVATE */
png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
png_uint_32 length, int keep)
{ int handled = 0; /* the chunk was handled */
png_debug(1, "in png_handle_unknown");
#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing * the bug which meant that setting a non-default behavior for a specific * chunk would be ignored (the default was always used unless a user * callback was installed). * * 'keep' is the value from the png_chunk_unknown_handling, the setting for * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here. * This is just an optimization to avoid multiple calls to the lookup * function.
*/ # ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name); # endif # endif
/* One of the following methods will read the chunk or skip it (at least one * of these is always defined because this is the only way to switch on * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
*/ # ifdef PNG_READ_USER_CHUNKS_SUPPORTED /* The user callback takes precedence over the chunk keep value, but the * keep value is still required to validate a save of a critical chunk.
*/ if (png_ptr->read_user_chunk_fn != NULL)
{ if (png_cache_unknown_chunk(png_ptr, length) != 0)
{ /* Callback to user unknown chunk handler */ int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
&png_ptr->unknown_chunk);
/* ret is: * negative: An error occurred; png_chunk_error will be called. * zero: The chunk was not handled, the chunk will be discarded * unless png_set_keep_unknown_chunks has been used to set * a 'keep' behavior for this particular chunk, in which * case that will be used. A critical chunk will cause an * error at this point unless it is to be saved. * positive: The chunk was handled, libpng will ignore/discard it.
*/ if (ret < 0)
png_chunk_error(png_ptr, "error in user chunk");
elseif (ret == 0)
{ /* If the keep value is 'default' or 'never' override it, but * still error out on critical chunks unless the keep value is * 'always' While this is weird it is the behavior in 1.4.12. * A possible improvement would be to obey the value set for the * chunk, but this would be an API change that would probably * damage some applications. * * The png_app_warning below catches the case that matters, where * the application has not set specific save or ignore for this * chunk or global save or ignore.
*/ if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
{ # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
{
png_chunk_warning(png_ptr, "Saving unknown chunk:");
png_app_warning(png_ptr, "forcing save of an unhandled chunk;" " please call png_set_keep_unknown_chunks"); /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
} # endif
keep = PNG_HANDLE_CHUNK_IF_SAFE;
}
}
else/* chunk was handled */
{
handled = 1; /* Critical chunks can be safely discarded at this point. */
keep = PNG_HANDLE_CHUNK_NEVER;
}
}
else /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */ # endif /* READ_USER_CHUNKS */
# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
{ /* keep is currently just the per-chunk setting, if there was no * setting change it to the global default now (not that this may * still be AS_DEFAULT) then obtain the cache of the chunk if required, * if not simply skip the chunk.
*/ if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
keep = png_ptr->unknown_default;
if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
(keep == PNG_HANDLE_CHUNK_IF_SAFE &&
PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
{ if (png_cache_unknown_chunk(png_ptr, length) == 0)
keep = PNG_HANDLE_CHUNK_NEVER;
}
else
png_crc_finish(png_ptr, length);
} # else # ifndef PNG_READ_USER_CHUNKS_SUPPORTED # error no method to support READ_UNKNOWN_CHUNKS # endif
{ /* If here there is no read callback pointer set and no support is * compiled in to just save the unknown chunks, so simply skip this * chunk. If 'keep' is something other than AS_DEFAULT or NEVER then * the app has erroneously asked for unknown chunk saving when there * is no support.
*/ if (keep > PNG_HANDLE_CHUNK_NEVER)
png_app_error(png_ptr, "no unknown chunk support available");
png_crc_finish(png_ptr, length);
} # endif
# ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED /* Now store the chunk in the chunk list if appropriate, and if the limits * permit it.
*/ if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
(keep == PNG_HANDLE_CHUNK_IF_SAFE &&
PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
{ # ifdef PNG_USER_LIMITS_SUPPORTED switch (png_ptr->user_chunk_cache_max)
{ case 2:
png_ptr->user_chunk_cache_max = 1;
png_chunk_benign_error(png_ptr, "no space in chunk cache"); /* FALLTHROUGH */ case 1: /* NOTE: prior to 1.6.0 this case resulted in an unknown critical * chunk being skipped, now there will be a hard error below.
*/ break;
default: /* not at limit */
--(png_ptr->user_chunk_cache_max); /* FALLTHROUGH */ case 0: /* no limit */ # endif /* USER_LIMITS */ /* Here when the limit isn't reached or when limits are compiled * out; store the chunk.
*/
png_set_unknown_chunks(png_ptr, info_ptr,
&png_ptr->unknown_chunk, 1);
handled = 1; # ifdef PNG_USER_LIMITS_SUPPORTED break;
} # endif
} # else/* no store support: the chunk must be handled by the user callback */
PNG_UNUSED(info_ptr) # endif
/* Regardless of the error handling below the cached data (if any) can be * freed now. Notice that the data is not freed if there is a png_error, but * it will be freed by destroy_read_struct.
*/ if (png_ptr->unknown_chunk.data != NULL)
png_free(png_ptr, png_ptr->unknown_chunk.data);
png_ptr->unknown_chunk.data = NULL;
#else/* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */ /* There is no support to read an unknown chunk, so just skip it. */
png_crc_finish(png_ptr, length);
PNG_UNUSED(info_ptr)
PNG_UNUSED(keep) #endif/* !READ_UNKNOWN_CHUNKS */
/* Check for unhandled critical chunks */ if (handled == 0 && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
png_chunk_error(png_ptr, "unhandled critical chunk");
}
/* This function is called to verify that a chunk name is valid. * This function can't have the "critical chunk check" incorporated * into it, since in the future we will need to be able to call user * functions to handle unknown critical chunks after we check that * the chunk name itself is valid.
*/
/* Bit hacking: the test for an invalid byte in the 4 byte chunk name is: * * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
*/
if (length > limit)
{
png_debug2(0," length = %lu, limit = %lu",
(unsignedlong)length,(unsignedlong)limit);
png_benign_error(png_ptr, "chunk data is too large");
}
}
/* Combines the row recently read in with the existing pixels in the row. This * routine takes care of alpha and transparency if requested. This routine also * handles the two methods of progressive display of interlaced images, * depending on the 'display' value; if 'display' is true then the whole row * (dp) is filled from the start by replicating the available pixels. If * 'display' is false only those pixels present in the pass are filled in.
*/ void/* PRIVATE */
png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
{ unsignedint pixel_depth = png_ptr->transformed_pixel_depth;
png_const_bytep sp = png_ptr->row_buf + 1;
png_alloc_size_t row_width = png_ptr->width; unsignedint pass = png_ptr->pass;
png_bytep end_ptr = 0;
png_byte end_byte = 0; unsignedint end_mask;
png_debug(1, "in png_combine_row");
/* Added in 1.5.6: it should not be possible to enter this routine until at * least one row has been read from the PNG data and transformed.
*/ if (pixel_depth == 0)
png_error(png_ptr, "internal row logic error");
/* Added in 1.5.4: the pixel depth should match the information returned by * any call to png_read_update_info at this point. Do not continue if we got * this wrong.
*/ if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
PNG_ROWBYTES(pixel_depth, row_width))
png_error(png_ptr, "internal row size calculation error");
/* Don't expect this to ever happen: */ if (row_width == 0)
png_error(png_ptr, "internal row width error");
/* Preserve the last byte in cases where only part of it will be overwritten, * the multiply below may overflow, we don't care because ANSI-C guarantees * we get the low bits.
*/
end_mask = (pixel_depth * row_width) & 7; if (end_mask != 0)
{ /* end_ptr == NULL is a flag to say do nothing */
end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
end_byte = *end_ptr; # ifdef PNG_READ_PACKSWAP_SUPPORTED if ((png_ptr->transformations & PNG_PACKSWAP) != 0) /* little-endian byte */
end_mask = (unsignedint)(0xff << end_mask);
else/* big-endian byte */ # endif
end_mask = 0xff >> end_mask; /* end_mask is now the bits to *keep* from the destination row */
}
/* For non-interlaced images this reduces to a memcpy(). A memcpy() * will also happen if interlacing isn't supported or if the application * does not call png_set_interlace_handling(). In the latter cases the * caller just gets a sequence of the unexpanded rows from each interlace * pass.
*/ #ifdef PNG_READ_INTERLACING_SUPPORTED if (png_ptr->interlaced != 0 &&
(png_ptr->transformations & PNG_INTERLACE) != 0 &&
pass < 6 && (display == 0 || /* The following copies everything for 'display' on passes 0, 2 and 4. */
(display == 1 && (pass & 1) != 0)))
{ /* Narrow images may have no bits in a pass; the caller should handle * this, but this test is cheap:
*/ if (row_width <= PNG_PASS_START_COL(pass)) return;
if (pixel_depth < 8)
{ /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit * into 32 bits, then a single loop over the bytes using the four byte * values in the 32-bit mask can be used. For the 'display' option the * expanded mask may also not require any masking within a byte. To * make this work the PACKSWAP option must be taken into account - it * simply requires the pixels to be reversed in each byte. * * The 'regular' case requires a mask for each of the first 6 passes, * the 'display' case does a copy for the even passes in the range * 0..6. This has already been handled in the test above. * * The masks are arranged as four bytes with the first byte to use in * the lowest bits (little-endian) regardless of the order (PACKSWAP or * not) of the pixels in each byte. * * NOTE: the whole of this logic depends on the caller of this function * only calling it on rows appropriate to the pass. This function only * understands the 'x' logic; the 'y' logic is handled by the caller. * * The following defines allow generation of compile time constant bit * masks for each pixel depth and each possibility of swapped or not * swapped bytes. Pass 'p' is in the range 0..6; 'x', a pixel index, * is in the range 0..7; and the result is 1 if the pixel is to be * copied in the pass, 0 if not. 'S' is for the sparkle method, 'B' * for the block method. * * With some compilers a compile time expression of the general form: * * (shift >= 32) ? (a >> (shift-32)) : (b >> shift) * * Produces warnings with values of 'shift' in the range 33 to 63 * because the right hand side of the ?: expression is evaluated by * the compiler even though it isn't used. Microsoft Visual C (various * versions) and the Intel C compiler are known to do this. To avoid * this the following macros are used in 1.5.6. This is a temporary * solution to avoid destabilizing the code during the release process.
*/ # if PNG_USE_COMPILE_TIME_MASKS # define PNG_LSR(x,s) ((x)>>((s) & 0x1f)) # define PNG_LSL(x,s) ((x)<<((s) & 0x1f)) # else # define PNG_LSR(x,s) ((x)>>(s)) # define PNG_LSL(x,s) ((x)<<(s)) # endif # define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1) # define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
/* Return a mask for pass 'p' pixel 'x' at depth 'd'. The mask is * little endian - the first pixel is at bit 0 - however the extra * parameter 's' can be set to cause the mask position to be swapped * within each byte, to match the PNG format. This is done by XOR of * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
*/ # define PIXEL_MASK(p,x,d,s) \
(PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
/* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
*/ # define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0) # define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
/* Combine 8 of these to get the full mask. For the 1-bpp and 2-bpp * cases the result needs replicating, for the 4-bpp case the above * generates a full 32 bits.
*/ # define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
#if PNG_USE_COMPILE_TIME_MASKS /* Utility macros to construct all the masks for a depth/swap * combination. The 's' parameter says whether the format is PNG * (big endian bytes) or not. Only the three odd-numbered passes are * required for the display/block algorithm.
*/ # define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
/* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and * then pass:
*/ staticconst png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
{ /* Little-endian byte masks for PACKSWAP */
{ S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) }, /* Normal (big-endian byte) masks - PNG format */
{ S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
};
/* display_mask has only three entries for the odd passes, so index by * pass>>1.
*/ staticconst png_uint_32 display_mask[2][3][3] =
{ /* Little-endian byte masks for PACKSWAP */
{ B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) }, /* Normal (big-endian byte) masks - PNG format */
{ B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
};
#else/* !PNG_USE_COMPILE_TIME_MASKS */ /* This is the runtime alternative: it seems unlikely that this will * ever be either smaller or faster than the compile time approach.
*/ # define MASK(pass,depth,display,png)\
((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png)) #endif/* !USE_COMPILE_TIME_MASKS */
/* Use the appropriate mask to copy the required bits. In some cases * the byte mask will be 0 or 0xff; optimize these cases. row_width is * the number of pixels, but the code copies bytes, so it is necessary * to special case the end.
*/
png_uint_32 pixels_per_byte = 8 / pixel_depth;
png_uint_32 mask;
/* It doesn't matter in the following if png_uint_32 has more than * 32 bits because the high bits always match those in m<<24; it is, * however, essential to use OR here, not +, because of this.
*/
m = mask;
mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
m &= 0xff;
if (m != 0) /* something to copy */
{ if (m != 0xff)
*dp = (png_byte)((*dp & ~m) | (*sp & m)); else
*dp = *sp;
}
/* NOTE: this may overwrite the last byte with garbage if the image * is not an exact number of bytes wide; libpng has always done * this.
*/ if (row_width <= pixels_per_byte) break; /* May need to restore part of the last byte */
/* Validate the depth - it must be a multiple of 8 */ if (pixel_depth & 7)
png_error(png_ptr, "invalid user transform pixel depth");
pixel_depth >>= 3; /* now in bytes */
row_width *= pixel_depth;
/* Regardless of pass number the Adam 7 interlace always results in a * fixed number of pixels to copy then to skip. There may be a * different number of pixels to skip at the start though.
*/
{ unsignedint offset = PNG_PASS_START_COL(pass) * pixel_depth;
/* Work out the bytes to copy. */ if (display != 0)
{ /* When doing the 'block' algorithm the pixel in the pass gets * replicated to adjacent pixels. This is why the even (0,2,4,6) * passes are skipped above - the entire expanded row is copied.
*/
bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
/* But don't allow this number to exceed the actual row width. */ if (bytes_to_copy > row_width)
bytes_to_copy = (unsignedint)/*SAFE*/row_width;
}
else/* normal row; Adam7 only ever gives us one pixel to copy. */
bytes_to_copy = pixel_depth;
/* In Adam7 there is a constant offset between where the pixels go. */
bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
/* And simply copy these bytes. Some optimization is possible here, * depending on the value of 'bytes_to_copy'. Special case the low * byte counts, which we know to be frequent. * * Notice that these cases all 'return' rather than 'break' - this * avoids an unnecessary test on whether to restore the last byte * below.
*/ switch (bytes_to_copy)
{ case 1: for (;;)
{
*dp = *sp;
/* And there can only be one byte left at this point: */
*dp = *sp; return;
case 3: /* This can only be the RGB case, so each copy is exactly one * pixel and it is not necessary to check for a partial copy.
*/ for (;;)
{
dp[0] = sp[0]; dp[1] = sp[1]; dp[2] = sp[2];
/* Get to here when the row_width truncates the final copy. * There will be 1-3 bytes left to copy, so don't try the * 16-bit loop below.
*/
dp = (png_bytep)dp32;
sp = (png_const_bytep)sp32; do
*dp++ = *sp++; while (--row_width > 0); return;
}
/* Else do it in 16-bit quantities, but only if the size is * not too large.
*/ else
{
png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
png_const_uint_16p sp16 = png_aligncastconst(
png_const_uint_16p, sp);
size_t skip = (bytes_to_jump-bytes_to_copy) /
(sizeof (png_uint_16));
do
{
size_t c = bytes_to_copy; do
{
*dp16++ = *sp16++;
c -= (sizeof (png_uint_16));
} while (c > 0);
/* Here if pixel_depth < 8 to check 'end_ptr' below. */
} else #endif/* READ_INTERLACING */
/* If here then the switch above wasn't used so just memcpy the whole row * from the temporary row buffer (notice that this overwrites the end of the * destination row if it is a partial byte.)
*/
memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
/* Restore the overwritten bits from the last byte if necessary. */ if (end_ptr != NULL)
*end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
}
#ifdef PNG_READ_INTERLACING_SUPPORTED void/* PRIVATE */
png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
png_uint_32 transformations /* Because these may affect the byte layout */)
{
png_debug(1, "in png_do_read_interlace"); if (row != NULL && row_info != NULL)
{
png_uint_32 final_width;
for (i = 0; i < bpp; i++)
{
*rp = (png_byte)(((int)(*rp) +
((int)(*pp++) / 2 )) & 0xff);
rp++;
}
for (i = 0; i < istop; i++)
{
*rp = (png_byte)(((int)(*rp) +
(int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
rp++;
}
}
staticvoid
png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
png_const_bytep prev_row)
{
png_bytep rp_end = row + row_info->rowbytes; int a, c;
/* First pixel/byte */
c = *prev_row++;
a = *row + c;
*row++ = (png_byte)a;
/* Remainder */ while (row < rp_end)
{ int b, pa, pb, pc, p;
a &= 0xff; /* From previous iteration or start */
b = *prev_row++;
p = b - c;
pc = a - c;
#ifdef PNG_USE_ABS
pa = abs(p);
pb = abs(pc);
pc = abs(p + pc); #else
pa = p < 0 ? -p : p;
pb = pc < 0 ? -pc : pc;
pc = (p + pc) < 0 ? -(p + pc) : p + pc; #endif
/* Find the best predictor, the least of pa, pb, pc favoring the earlier * ones in the case of a tie.
*/ if (pb < pa)
{
pa = pb; a = b;
} if (pc < pa) a = c;
/* Calculate the current pixel in a, and move the previous row pixel to c * for the next time round the loop
*/
c = b;
a += *row;
*row++ = (png_byte)a;
}
}
/* 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;
}
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;
}
}
staticvoid
png_init_filter_functions(png_structrp pp) /* This function is called once for every PNG image (except for PNG images * that only use PNG_FILTER_VALUE_NONE for all rows) to set the * implementations required to reverse the filtering of PNG rows. Reversing * the filter is the first transformation performed on the row data. It is * performed in place, therefore an implementation can be selected based on * the image pixel format. If the implementation depends on image width then * take care to ensure that it works correctly if the image is interlaced - * interlacing causes the actual row width to vary.
*/
{ unsignedint bpp = (pp->pixel_depth + 7) >> 3;
#ifdef PNG_FILTER_OPTIMIZATIONS /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to * call to install hardware optimizations for the above functions; simply * replace whatever elements of the pp->read_filter[] array with a hardware * specific (or, for that matter, generic) optimization. * * To see an example of this examine what configure.ac does when * --enable-arm-neon is specified on the command line.
*/
PNG_FILTER_OPTIMIZATIONS(pp, bpp); #endif
}
void/* PRIVATE */
png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
png_const_bytep prev_row, int filter)
{ /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic * implementations. See png_init_filter_functions above.
*/ if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
{ if (pp->read_filter[0] == NULL)
png_init_filter_functions(pp);
png_ptr->idat_size = png_read_chunk_header(png_ptr); /* This is an error even in the 'check' case because the code just * consumed a non-IDAT header.
*/ if (png_ptr->chunk_name != png_IDAT)
png_error(png_ptr, "Not enough image data");
} #endif/* READ_APNG */
avail_in = png_ptr->IDAT_read_size;
if (avail_in > png_ptr->idat_size)
avail_in = (uInt)png_ptr->idat_size;
/* A PNG with a gradually increasing IDAT size will defeat this attempt * to minimize memory usage by causing lots of re-allocs, but * realistically doing IDAT_read_size re-allocs is not likely to be a * big problem.
*/
buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
else/* after last row, checking for end */
{
png_ptr->zstream.next_out = tmpbuf;
png_ptr->zstream.avail_out = (sizeof tmpbuf);
}
/* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the * process. If the LZ stream is truncated the sequential reader will * terminally damage the stream, above, by reading the chunk header of the * following chunk (it then exits with png_error). * * TODO: deal more elegantly with truncated IDAT lists.
*/
ret = PNG_INFLATE(png_ptr, Z_NO_FLUSH);
/* Take the unconsumed output back. */ if (output != NULL)
avail_out += png_ptr->zstream.avail_out;
else/* avail_out counts the extra bytes */
avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
png_ptr->zstream.avail_out = 0;
if (ret == Z_STREAM_END)
{ /* Do this for safety; we won't read any more into this row. */
png_ptr->zstream.next_out = NULL;
if (avail_out > 0)
{ /* The stream ended before the image; this is the same as too few IDATs so * should be handled the same way.
*/ if (output != NULL)
png_error(png_ptr, "Not enough image data");
else/* the deflate stream contained extra data */
png_chunk_benign_error(png_ptr, "Too much image data");
}
}
void/* PRIVATE */
png_read_finish_IDAT(png_structrp png_ptr)
{ /* We don't need any more data and the stream should have ended, however the * LZ end code may actually not have been processed. In this case we must * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk * may still remain to be consumed.
*/ if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
{ /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in * the compressed stream, but the stream may be damaged too, so even after * this call we may need to terminate the zstream ownership.
*/
png_read_IDAT_data(png_ptr, NULL, 0);
png_ptr->zstream.next_out = NULL; /* safety */
/* Now clear everything out for safety; the following may not have been * done.
*/ if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
{
png_ptr->mode |= PNG_AFTER_IDAT;
png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
}
}
/* If the zstream has not been released do it now *and* terminate the reading * of the final IDAT chunk.
*/ if (png_ptr->zowner == png_IDAT)
{ /* Always do this; the pointers otherwise point into the read buffer. */
png_ptr->zstream.next_in = NULL;
png_ptr->zstream.avail_in = 0;
/* Now we no longer own the zstream. */
png_ptr->zowner = 0;
/* The slightly weird semantics of the sequential IDAT reading is that we * are always in or at the end of an IDAT chunk, so we always need to do a * crc_finish here. If idat_size is non-zero we also need to read the * spurious bytes at the end of the chunk now.
*/
(void)png_crc_finish(png_ptr, png_ptr->idat_size);
}
}
void/* PRIVATE */
png_read_finish_row(png_structrp png_ptr)
{
png_debug(1, "in png_read_finish_row");
png_ptr->row_number++; if (png_ptr->row_number < png_ptr->num_rows) return;
if (png_ptr->interlaced != 0)
{
png_ptr->row_number = 0;
/* TO DO: don't do this if prev_row isn't needed (requires * read-ahead of the next row's filter byte.
*/
memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
/* WARNING: * png_read_transform_info (pngrtran.c) performs a simpler set of * calculations to calculate the final pixel depth, then * png_do_read_transforms actually does the transforms. This means that the * code which effectively calculates this value is actually repeated in three * separate places. They must all match. Innocent changes to the order of * transformations can and will break libpng in a way that causes memory * overwrites. * * TODO: fix this.
*/ #ifdef PNG_READ_PACK_SUPPORTED if ((png_ptr->transformations & PNG_PACK) != 0 && png_ptr->bit_depth < 8)
max_pixel_depth = 8; #endif
#ifdef PNG_READ_EXPAND_SUPPORTED if ((png_ptr->transformations & PNG_EXPAND) != 0)
{ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{ if (png_ptr->num_trans != 0)
max_pixel_depth = 32;
#ifdef PNG_READ_EXPAND_16_SUPPORTED if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
{ # ifdef PNG_READ_EXPAND_SUPPORTED /* In fact it is an error if it isn't supported, but checking is * the safe way.
*/ if ((png_ptr->transformations & PNG_EXPAND) != 0)
{ if (png_ptr->bit_depth < 16)
max_pixel_depth *= 2;
} else # endif
png_ptr->transformations &= ~PNG_EXPAND_16;
} #endif
#ifdef PNG_READ_FILLER_SUPPORTED if ((png_ptr->transformations & (PNG_FILLER)) != 0)
{ if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
{ if (max_pixel_depth <= 8)
max_pixel_depth = 16;
if (user_pixel_depth > max_pixel_depth)
max_pixel_depth = user_pixel_depth;
} #endif
/* This value is stored in png_struct and double checked in the row read * code.
*/
png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
/* Align the width on the next larger 8 pixels. Mainly used * for interlacing
*/
row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7)); /* Calculate the maximum bytes needed, adding a byte and a pixel * for safety's sake
*/
row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
1 + ((max_pixel_depth + 7) >> 3U);
#ifdef PNG_MAX_MALLOC_64K if (row_bytes > (png_uint_32)65536L)
png_error(png_ptr, "This image requires a row greater than 64KB"); #endif
#ifdef PNG_ALIGNED_MEMORY_SUPPORTED /* Use 16-byte aligned memory for row_buf with at least 16 bytes * of padding before and after row_buf; treat prev_row similarly. * NOTE: the alignment is to the start of the pixels, one beyond the start * of the buffer, because of the filter byte. Prior to libpng 1.5.6 this * was incorrect; the filter byte was aligned, which had the exact * opposite effect of that intended.
*/
{
png_bytep temp = png_ptr->big_row_buf + 32;
size_t extra = (size_t)temp & 0x0f;
png_ptr->row_buf = temp - extra - 1/*filter byte*/;
temp = png_ptr->big_prev_row + 32;
extra = (size_t)temp & 0x0f;
png_ptr->prev_row = temp - extra - 1/*filter byte*/;
} #else /* Use 31 bytes of padding before and 17 bytes after row_buf. */
png_ptr->row_buf = png_ptr->big_row_buf + 31;
png_ptr->prev_row = png_ptr->big_prev_row + 31; #endif
png_ptr->old_big_row_buf_size = row_bytes + 48;
}
#ifdef PNG_MAX_MALLOC_64K if (png_ptr->rowbytes > 65535)
png_error(png_ptr, "This image requires a row greater than 64KB");
#endif if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
png_error(png_ptr, "Row has too many bytes to allocate in memory");
/* The sequential reader needs a buffer for IDAT, but the progressive reader * does not, so free the read buffer now regardless; the sequential reader * reallocates it on demand.
*/ if (png_ptr->read_buffer != NULL)
{
png_bytep buffer = png_ptr->read_buffer;
/* Finally claim the zstream for the inflate of the IDAT data, use the bits * value from the stream (note that this will result in a fatal error if the * IDAT stream has a bogus deflate header window_bits value, but this should * not be happening any longer!)
*/ if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
png_error(png_ptr, png_ptr->zstream.msg);
png_ptr->flags |= PNG_FLAG_ROW_INIT;
}
#ifdef PNG_READ_APNG_SUPPORTED /* This function is to be called after the main IDAT set has been read and * before a new IDAT is read. It resets some parts of png_ptr
* to make them usable by the read functions again */ void/* PRIVATE */
png_read_reset(png_structp png_ptr)
{
png_ptr->mode &= ~PNG_HAVE_IDAT;
png_ptr->mode &= ~PNG_AFTER_IDAT;
png_ptr->row_number = 0;
png_ptr->pass = 0;
}
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED /* same as png_read_reset() but for the progressive reader */ void/* PRIVATE */
png_progressive_read_reset(png_structp png_ptr)
{ #ifdef PNG_READ_INTERLACING_SUPPORTED /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
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