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skia / third_party / libpng / v1.7.0beta77 / . / pngwutil.c
blob: 30a8f945ae5b60d528bd2438518b685d364718bd [file] [log] [blame]
/* pngwutil.c - utilities to write a PNG file
*
* Last changed in libpng 1.7.0 [(PENDING RELEASE)]
* Copyright (c) 1998-2002,2004,2006-2016 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
*/
#include "pngpriv.h"
#define PNG_SRC_FILE PNG_SRC_FILE_pngwutil
#ifdef PNG_WRITE_SUPPORTED
#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
/* Place a 32-bit number into a buffer in PNG byte order. We work
* with unsigned numbers for convenience, although one supported
* ancillary chunk uses signed (two's complement) numbers.
*/
void PNGAPI
png_save_uint_32(png_bytep buf, png_uint_32 i)
{
buf[0] = PNG_BYTE(i >> 24);
buf[1] = PNG_BYTE(i >> 16);
buf[2] = PNG_BYTE(i >> 8);
buf[3] = PNG_BYTE(i);
}
/* Place a 16-bit number into a buffer in PNG byte order.
* The parameter is declared unsigned int, not png_uint_16,
* just to avoid potential problems on pre-ANSI C compilers.
*/
void PNGAPI
png_save_uint_16(png_bytep buf, unsigned int i)
{
buf[0] = PNG_BYTE(i >> 8);
buf[1] = PNG_BYTE(i);
}
#endif /* WRITE_INT_FUNCTIONS */
/* Simple function to write the signature. If we have already written
* the magic bytes of the signature, or more likely, the PNG stream is
* being embedded into another stream and doesn't need its own signature,
* we should call png_set_sig_bytes() to tell libpng how many of the
* bytes have already been written.
*/
void PNGAPI
png_write_sig(png_structrp png_ptr)
{
png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the signature is being written */
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
#endif
/* Write the rest of the 8 byte signature */
png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
(png_size_t)(8 - png_ptr->sig_bytes));
if (png_ptr->sig_bytes < 3)
png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
}
/* Write the start of a PNG chunk. The type is the chunk type.
* The total_length is the sum of the lengths of all the data you will be
* passing in png_write_chunk_data().
*/
static void
png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name,
png_uint_32 length)
{
png_byte buf[8];
#if defined(PNG_DEBUG) && (PNG_DEBUG > 0)
PNG_CSTRING_FROM_CHUNK(buf, chunk_name);
png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);
#endif
if (png_ptr == NULL)
return;
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the chunk header is being written.
* PNG_IO_CHUNK_HDR requires a single I/O call.
*/
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR;
#endif
/* Write the length and the chunk name */
png_save_uint_32(buf, length);
png_save_uint_32(buf + 4, chunk_name);
png_write_data(png_ptr, buf, 8);
/* Put the chunk name into png_ptr->chunk_name */
png_ptr->chunk_name = chunk_name;
/* Reset the crc and run it over the chunk name */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, buf + 4, 4);
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that chunk data will (possibly) be written.
* PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
*/
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA;
#endif
}
void PNGAPI
png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string,
png_uint_32 length)
{
png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);
}
/* Write the data of a PNG chunk started with png_write_chunk_header().
* Note that multiple calls to this function are allowed, and that the
* sum of the lengths from these calls *must* add up to the total_length
* given to png_write_chunk_header().
*/
void PNGAPI
png_write_chunk_data(png_structrp png_ptr, png_const_voidp data,
png_size_t length)
{
/* Write the data, and run the CRC over it */
if (png_ptr == NULL)
return;
if (data != NULL && length > 0)
{
png_write_data(png_ptr, data, length);
/* Update the CRC after writing the data,
* in case the user I/O routine alters it.
*/
png_calculate_crc(png_ptr, data, length);
}
}
/* Finish a chunk started with png_write_chunk_header(). */
void PNGAPI
png_write_chunk_end(png_structrp png_ptr)
{
png_byte buf[4];
if (png_ptr == NULL) return;
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the chunk CRC is being written.
* PNG_IO_CHUNK_CRC requires a single I/O function call.
*/
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;
#endif
/* Write the crc in a single operation */
png_save_uint_32(buf, png_ptr->crc);
png_write_data(png_ptr, buf, (png_size_t)4);
}
/* Write a PNG chunk all at once. The type is an array of ASCII characters
* representing the chunk name. The array must be at least 4 bytes in
* length, and does not need to be null terminated. To be safe, pass the
* pre-defined chunk names here, and if you need a new one, define it
* where the others are defined. The length is the length of the data.
* All the data must be present. If that is not possible, use the
* png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
* functions instead.
*/
static void
png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
png_const_voidp data, png_size_t length)
{
if (png_ptr == NULL)
return;
/* On 64 bit architectures 'length' may not fit in a png_uint_32. */
if (length > PNG_UINT_31_MAX)
png_error(png_ptr, "length exceeds PNG maximum");
png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)/*SAFE*/length);
png_write_chunk_data(png_ptr, data, length);
png_write_chunk_end(png_ptr);
}
/* This is the API that calls the internal function above. */
void PNGAPI
png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
png_const_voidp data, png_size_t length)
{
png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
length);
}
/* This is used below to find the size of an image to pass to png_deflate_claim,
* so it only needs to be accurate if the size is less than 16384 bytes (the
* point at which a lower LZ window size can be used.)
*/
static png_alloc_size_t
png_image_size(png_const_structrp png_ptr)
{
/* Only return sizes up to the maximum of a png_uint_32; do this by limiting
* the width and height used to 15 bits.
*/
const png_uint_32 h = png_ptr->height;
const png_uint_32 w = png_ptr->width;
const unsigned int pd = PNG_PIXEL_DEPTH(*png_ptr);
png_alloc_size_t rowbytes = PNG_ROWBYTES(pd, w);
if (rowbytes < 32768 && h < 32768)
{
if (png_ptr->interlaced != 0)
{
/* Interlacing makes the image larger because of the replication of
* both the filter byte and the padding to a byte boundary.
*/
png_alloc_size_t cb_base;
int pass;
for (cb_base=0, pass=0; pass<PNG_INTERLACE_ADAM7_PASSES; ++pass)
{
png_uint_32 pw = PNG_PASS_COLS(w, pass);
if (pw > 0)
cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass);
}
return cb_base;
}
else
return (rowbytes+1) * h;
}
else
return 0xffffffffU;
}
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
/* This is the code to hack the first two bytes of the deflate stream (the
* deflate header) to correct the windowBits value to match the actual data
* size. Note that the second argument is the *uncompressed* size but the
* first argument is the *compressed* data (and it must be deflate
* compressed.)
*/
static void
optimize_cmf(png_const_structrp png_ptr, png_bytep data,
png_alloc_size_t data_size)
{
/* Optimize the CMF field in the zlib stream. The resultant zlib stream is
* still compliant to the stream specification.
*/
if (data_size <= 16384) /* else windowBits must be 15 */
{
unsigned int z_cmf = data[0]; /* zlib compression method and flags */
if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
{
unsigned int z_cinfo;
unsigned int half_z_window_size;
z_cinfo = z_cmf >> 4;
half_z_window_size = 1U << (z_cinfo + 7);
if (data_size <= half_z_window_size) /* else no change */
{
unsigned int tmp;
do
{
half_z_window_size >>= 1;
--z_cinfo;
}
while (z_cinfo > 0 && data_size <= half_z_window_size);
z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
data[0] = png_check_byte(png_ptr, z_cmf);
tmp = data[1] & 0xe0;
tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
data[1] = png_check_byte(png_ptr, tmp);
}
}
}
PNG_UNUSED(png_ptr)
}
#endif /* WRITE_OPTIMIZE_CMF */
/* Release memory used by the deflate mechanism */
static void
png_deflateEnd(png_const_structrp png_ptr, z_stream *zs, int check)
{
if (zs->state != NULL)
{
int ret = deflateEnd(zs);
/* Z_DATA_ERROR means there was pending output. */
if ((ret != Z_OK && (check || ret != Z_DATA_ERROR)) || zs->state != NULL)
{
png_zstream_error(zs, ret);
if (check)
png_error(png_ptr, zs->msg);
else
png_warning(png_ptr, zs->msg);
zs->state = NULL;
}
}
}
/* compression_buffer (new in 1.6.0) is just a linked list of temporary buffers. * From 1.6.0 it is retained in png_struct so that it will be correctly freed in
* the event of a write error (previous implementations just leaked memory.)
*
* From 1.7.0 the size is fixed to the same as the (uncompressed) row buffer
* size. This avoids allocating a large chunk of memory when compressing small
* images. This type is also opaque outside this file.
*/
typedef struct png_compression_buffer
{
struct png_compression_buffer *next;
png_byte output[PNG_ROW_BUFFER_SIZE];
} png_compression_buffer, *png_compression_bufferp;
/* png_compression_buffer methods */
/* Deleting a compression buffer deletes the whole list: */
static void
png_free_compression_buffer(png_const_structrp png_ptr,
png_compression_bufferp *listp)
{
png_compression_bufferp list = *listp;
if (list != NULL)
{
*listp = NULL;
do
{
png_compression_bufferp next = list->next;
png_free(png_ptr, list);
list = next;
}
while (list != NULL);
}
}
/* Return the next compression buffer in the list, allocating it if necessary.
* The caller must update 'end' if required; this just moves down the list.
*/
static png_compression_bufferp
png_get_compression_buffer(png_const_structrp png_ptr,
png_compression_bufferp *end)
{
png_compression_bufferp next = *end;
if (next == NULL)
{
next = png_voidcast(png_compression_bufferp, png_malloc_base(png_ptr,
sizeof *next));
/* Check for OOM: this is a recoverable error for non-critical chunks, let
* the caller decide what to do rather than issuing a png_error here.
*/
if (next != NULL)
{
next->next = NULL; /* initialize the buffer */
*end = next;
}
}
return next; /* may still be NULL on OOM */
}
/* This structure is used to hold all the data for zlib compression of a single
* stream of data. It may be re-used, it stores the compressed data internally
* and can handle arbitrary input and output.
*
* 'list' is the output data contained in compression buffers, 'end' points to
* list at the start and is advanced down the compression buffer list (extending
* it as required) as the data is written. If 'end' points into a compression
* buffer (does not point to 'list') that is the buffer in use in
* z_stream::{next,avail}_out.
*
* Compression may be performed in multiple steps, '*end' always points to the
* compression buffer *after* the one that is in use, so 'end' is pointing
* *into* the one in use.
*
* end(on entry) .... end ....... end(on exit)
* | | |
* | | |
* V +----V-----+ +-----V----+ +----------+
* list ---> | next --+--> | next --+--> | next |
* | output[] | | output[] | | output[] |
* +----------+ +----------+ +----------+
* [in use] [unused]
*
* These invariants should always hold:
*
* 1) If zs.state is NULL decompression is not in progress, list may be non-NULL
* but end could be anything;
*
* 2) Otherwise if zs.next_out is NULL list will be NULL and end will point at
* list, len, overflow and start will be 0;
*
* 3) Otherwise list is non-NULL and end points at the 'next' element of an
* in-use compression buffer. zs.next_out points into the 'output' element
* of the same buffer. {overflow, len} is the amount of compressed data, len
* being the low 31 bits, overflow being the higher bits. start is used for
* writing and is the index of the first byte in list->output to write,
* {overflow, len} does not include start.
*/
typedef struct
{
z_stream zs; /* zlib compression data */
png_compression_bufferp list; /* Head of the buffer list */
png_compression_bufferp *end; /* Pointer to last 'next' pointer */
png_uint_32 len; /* Bottom 31 bits of data length */
unsigned int overflow; /* Top bits of data length */
unsigned int start; /* Start of data in first block */
} png_zlib_compress, *png_zlib_compressp;
/* png_zlib_compress methods */
/* Initialize the compress structure. The z_stream itself is not initialized,
* however the the 'user' fields are set, including {next,avail}_{in,out}. The
* initialization does not change 'list', however it does set 'end' to point to
* it, effectively truncating the list.
*/
static void
png_zlib_compress_init(png_structrp png_ptr, png_zlib_compressp pz)
{
/* png_zlib_compress z_stream: */
pz->zs.zalloc = png_zalloc;
pz->zs.zfree = png_zfree;
/* NOTE: this does not destroy 'restrict' because in all the functions herein
* *png_ptr is only ever accessed via *either* pz->zs.opaque *or* a passed in
* png_ptr.
*/
pz->zs.opaque = png_ptr;
pz->zs.next_in = NULL;
pz->zs.avail_in = 0U;
pz->zs.total_in = 0U;
pz->zs.next_out = NULL;
pz->zs.avail_out = 0U;
pz->zs.total_out = 0U;
pz->zs.msg = PNGZ_MSG_CAST("zlib success"); /* safety */
/* pz->list preserved */
pz->end = &pz->list;
pz->len = 0U;
pz->overflow = 0U;
pz->start = 0U;
}
/* Return the png_ptr: this is defined here for all the remaining
* png_zlib_compress methods because they are only ever called with zs
* initialized.
*/
#define png_ptr png_voidcast(png_const_structrp, pz->zs.opaque)
#if PNG_RELEASE_BUILD
# define png_zlib_compress_validate(pz, in_use) ((void)0)
#else /* !RELEASE_BUILD */
static void
png_zlib_compress_validate(png_zlib_compressp pz, int in_use)
{
const uInt o_size = sizeof pz->list->output;
affirm(pz->end != NULL && (in_use || (pz->zs.next_in == NULL &&
pz->zs.avail_in == 0U && *pz->end == NULL)));
if (pz->overflow == 0U && pz->len == 0U && pz->start == 0U) /* empty */
{
affirm((pz->end == &pz->list && pz->zs.next_out == NULL
&& pz->zs.avail_out == 0U) ||
(pz->list != NULL && pz->end == &pz->list->next &&
pz->zs.next_out == pz->list->output &&
pz->zs.avail_out == o_size));
}
else /* not empty */
{
png_compression_bufferp *ep = &pz->list, list;
png_uint_32 o, l;
affirm(*ep != NULL && pz->zs.next_out != NULL);
/* Check the list length: */
o = pz->overflow;
l = pz->len;
affirm((l & 0x80000000U) == 0U && (o & 0x80000000U) == 0U);
do
{
list = *ep;
l -= o_size;
if (l & 0x80000000U) --o, l &= 0x7FFFFFFFU;
ep = &list->next;
}
while (ep != pz->end);
l += pz->start;
l += pz->zs.avail_out;
if (l & 0x80000000U) ++o, l &= 0x7FFFFFFFU;
affirm(o == 0U && l == 0U && pz->zs.next_out >= list->output &&
pz->zs.next_out + pz->zs.avail_out == list->output + o_size);
}
}
#endif /* !RELEASE_BUILD */
/* Destroy one zlib compress structure. */
static void
png_zlib_compress_destroy(png_zlib_compressp pz, int check)
{
/* If the 'opaque' pointer is NULL this png_zlib_compress was never
* initialized, so do nothing.
*/
if (png_ptr != NULL)
{
if (pz->zs.state != NULL)
{
if (check)
png_zlib_compress_validate(pz, 0/*in_use*/);
png_deflateEnd(png_ptr, &pz->zs, check);
}
pz->end = &pz->list; /* safety */
png_free_compression_buffer(png_ptr, &pz->list);
}
}
/* Ensure that space is available for output, returns the amount of space
* available, 0 on OOM. This updates pz->zs.avail_out (etc) as required.
*/
static uInt
png_zlib_compress_avail_out(png_zlib_compressp pz)
{
uInt avail_out = pz->zs.avail_out;
png_zlib_compress_validate(pz, 1/*in_use*/);
if (avail_out == 0U)
{
png_compression_bufferp next;
affirm(pz->end == &pz->list || (pz->end != NULL && pz->list != NULL));
next = png_get_compression_buffer(png_ptr, pz->end);
if (next != NULL)
{
pz->zs.next_out = next->output;
pz->zs.avail_out = avail_out = sizeof next->output;
pz->end = &next->next;
}
/* else return 0: OOM */
}
else
affirm(pz->end != NULL && pz->list != NULL);
return avail_out;
}
/* Compress the given data given an initialized png_zlib_compress structure.
* This may be called multiple times, interleaved with writes as required.
*
* The input data is passed in in pz->zs.next_in, however the length of the data
* is in 'input_len' (to avoid the zlib uInt limit) and pz->zs.avail_in is
* overwritten (and left at 0).
*
* The output information is used and the amount of compressed data is added on
* to pz->{overflow,len}.
*
* If 'limit' is a limit on the amount of data to add to the output (not the
* total amount). The function will retun Z_BUF_ERROR if the limit is reached
* and the function will never produce more (additional) compressed data than
* the limit.
*
* All of zstream::next_in[input] is consumed if a success code is returned
* (Z_OK or Z_STREAM_END if flush is Z_FINISH), otherwise next_in may be used to
* determine how much was compressed.
*
* pz->overflow is not checked for overflow, so if 'limit' is not set overflow
* is possible. The caller must guard against this when supplying a limit of 0.
*/
static int
png_compress(
png_zlib_compressp pz,
png_alloc_size_t input_len, /* Length of data to be compressed */
png_uint_32 limit, /* Limit on amount of compressed data made */
int flush) /* Flush parameter at end of input */
{
const int unlimited = (limit == 0U);
/* Sanity checking: */
affirm(pz->zs.state != NULL &&
(pz->zs.next_out == NULL
? pz->end == &pz->list && pz->len == 0U && pz->overflow == 0U
: pz->list != NULL && pz->end != NULL));
implies(pz->zs.next_out == NULL, pz->zs.avail_out == 0);
for (;;)
{
uInt extra;
/* OUTPUT: make sure some space is available: */
if (png_zlib_compress_avail_out(pz) == 0U)
return Z_MEM_ERROR;
/* INPUT: limit the deflate call input to ZLIB_IO_MAX: */
/* Adjust the input counters: */
{
uInt avail_in = ZLIB_IO_MAX;
if (avail_in > input_len)
avail_in = (uInt)/*SAFE*/input_len;
input_len -= avail_in;
pz->zs.avail_in = avail_in;
}
if (!unlimited && pz->zs.avail_out > limit)
{
extra = (uInt)/*SAFE*/(pz->zs.avail_out - limit); /* unused bytes */
pz->zs.avail_out = (uInt)/*SAFE*/limit;
limit = 0U;
}
else
{
extra = 0U;
limit -= pz->zs.avail_out; /* limit >= 0U */
}
pz->len += pz->zs.avail_out; /* maximum that can be produced */
/* Compress the data */
{
int ret = deflate(&pz->zs, input_len > 0U ? Z_NO_FLUSH : flush);
/* Claw back input data that was not consumed (because avail_in is
* reset above every time round the loop) and correct the output
* length.
*/
input_len += pz->zs.avail_in;
pz->zs.avail_in = 0; /* safety */
pz->len -= pz->zs.avail_out;
if (pz->len & 0x80000000U)
++pz->overflow, pz->len &= 0x7FFFFFFFU;
limit += pz->zs.avail_out;
pz->zs.avail_out += extra;
/* Check the error code: */
switch (ret)
{
case Z_OK:
if (pz->zs.avail_out > extra)
{
/* zlib had output space, so all the input should have been
* consumed:
*/
affirm(input_len == 0U /* else unexpected stop */ &&
flush != Z_FINISH/* ret != Z_STREAM_END */);
return Z_OK;
}
else
{
/* zlib ran out of output space, produce some more. If the
* limit is 0 at this point, however, no more space is
* available.
*/
if (unlimited || limit > 0U)
break; /* Allocate more output */
/* No more output space available, but the input may have all
* been consumed.
*/
if (input_len == 0U && flush != Z_FINISH)
return Z_OK;
/* Input all consumed, but insufficient space to flush the
* output; this is the Z_BUF_ERROR case.
*/
return Z_BUF_ERROR;
}
case Z_STREAM_END:
affirm(input_len == 0U && flush == Z_FINISH);
return Z_STREAM_END;
case Z_BUF_ERROR:
/* This means that we are flushing all the output; expect
* avail_out and input_len to be 0.
*/
affirm(input_len == 0U && pz->zs.avail_out == extra);
/* Allocate another buffer */
break;
default:
/* An error */
return ret;
}
}
}
}
#undef png_ptr /* remove definition using a png_zlib_compressp */
/* All the compression state is held here, it is allocated when required. This
* ensures that the read code doesn't carry the overhead of the much less
* frequently used write stuff.
*
* TODO: make png_create_write_struct allocate this stuff after the main
* png_struct.
*/
typedef struct png_zlib_state
{
png_zlib_compress s; /* Primary compression state */
# ifdef PNG_SELECT_FILTER_METHODICALLY_SUPPORTED
/* The 'methodical' method uses up to PNG_FILTER_VALUE_LAST of these to
* test each possible filter:
*/
png_zlib_compress filter[PNG_FILTER_VALUE_LAST];
# endif /* SELECT_FILTER_METHODICALLY */
png_compression_bufferp stash; /* Unused compression buffers */
# ifdef PNG_WRITE_FLUSH_SUPPORTED
png_uint_32 flush_dist; /* how many rows apart to flush, 0 - no flush */
png_uint_32 flush_rows; /* number of rows written since last flush */
# endif /* WRITE_FLUSH */
#ifdef PNG_WRITE_FILTER_SUPPORTED
unsigned int filter_mask :8; /* mask of filters to consider on write */
unsigned int filters :8; /* Filters for current row */
unsigned int filter_oom :1; /* ran out of memory */
#endif /* WRITE_FILTER */
/* Zlib parameters to be used for IDAT and (possibly) text/ICC profile
* compression.
*/
int zlib_level; /* holds zlib compression level */
int zlib_method; /* holds zlib compression method */
int zlib_window_bits; /* holds zlib compression window bits */
int zlib_mem_level; /* holds zlib compression memory level */
int zlib_strategy; /* holds zlib compression strategy */
/* The same, but these are the values actually set into the z_stream: */
int zlib_set_level;
int zlib_set_method;
int zlib_set_window_bits;
int zlib_set_mem_level;
int zlib_set_strategy;
# ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
int zlib_text_level; /* holds zlib compression level */
int zlib_text_method; /* holds zlib compression method */
int zlib_text_window_bits; /* holds zlib compression window bits */
int zlib_text_mem_level; /* holds zlib compression memory level */
int zlib_text_strategy; /* holds zlib compression strategy */
# endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
} png_zlib_state;
/* This returns the zlib compression state and has the side effect of
* initializing it if it does not exist.
*/
static png_zlib_statep
png_get_zlib_state(png_structrp png_ptr)
{
if (png_ptr != NULL)
{
png_zlib_state *ps = png_ptr->zlib_state;
if (ps == NULL && !png_ptr->read_struct)
{
png_ptr->zlib_state = ps = png_voidcast(png_zlib_state*,
png_malloc(png_ptr, sizeof *ps));
/* Clear to NULL/0: */
memset(ps, 0, sizeof *ps);
png_zlib_compress_init(png_ptr, &ps->s);
# ifdef PNG_SELECT_FILTER_METHODICALLY_SUPPORTED
{
unsigned int i;
for (i=0; i<PNG_FILTER_VALUE_LAST; ++i)
ps->filter[i].zs.opaque = NULL;
}
# endif /* SELECT_FILTER_METHODICALLY */
ps->stash = NULL;
# ifdef PNG_WRITE_FLUSH_SUPPORTED
/* Set this to prevent flushing by making it larger than the number
* of rows in the largest interlaced PNG; PNG_UINT_31_MAX times
* (1/8+1/8+1/8+1/4+1/4+1/2+1/2); 1.875, or 15/8
*/
ps->flush_dist = 0xEFFFFFFFU;
ps->flush_rows = 0U;
# endif /* WRITE_FLUSH */
# ifdef PNG_WRITE_FILTER_SUPPORTED
ps->filter_mask = PNG_NO_FILTERS; /* unset */
ps->filters = 0U;
ps->filter_oom = 0U;
# endif /* WRITE_FILTER */
/* Zlib parameters to be used for IDAT and (possibly) text/ICC profile
* compression.
*/
ps->zlib_level = PNG_Z_DEFAULT_COMPRESSION;
ps->zlib_method = Z_DEFLATED;
ps->zlib_window_bits = 15; /* 8..15 permitted, 15 is the default */
ps->zlib_mem_level = 8; /* 1..9 permitted, 8 is the default */
ps->zlib_strategy = -1/*unset (invalid value)*/;
# ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
ps->zlib_text_level = PNG_TEXT_Z_DEFAULT_COMPRESSION;
ps->zlib_text_method = Z_DEFLATED;
ps->zlib_text_window_bits = 15;
ps->zlib_text_mem_level = 8;
ps->zlib_text_strategy = PNG_TEXT_Z_DEFAULT_STRATEGY;
# endif /* WRITE_COMPRESSED_TEXT */
}
return ps;
}
return NULL;
}
/* Internal API to clean up all the deflate related stuff, including the buffer
* lists.
*/
static void /* PRIVATE */
png_deflate_release(png_structrp png_ptr, png_zlib_statep ps, int check)
{
/* This must happen before ps->s is destroyed below because the structures
* may be shared:
*/
# ifdef PNG_SELECT_FILTER_METHODICALLY_SUPPORTED
unsigned int i;
/* Note that png_zlib_compress_destroy checks the 'opaque' pointer and
* does nothing if it is NULL.
*/
for (i=0U; i<PNG_FILTER_VALUE_LAST; ++i)
if (ps->filter[i].zs.state != ps->s.zs.state)
{
png_zlib_compress_destroy(&ps->filter[i], 0/*check*/);
ps->filter[i].zs.opaque = NULL;
}
# endif /* SELECT_FILTER_METHODICALLY */
/* The main z_stream opaque pointer needs to remain set to png_ptr; it is
* only set once.
*/
png_zlib_compress_destroy(&ps->s, check);
png_free_compression_buffer(png_ptr, &ps->stash);
}
void /* PRIVATE */
png_deflate_destroy(png_structrp png_ptr)
{
png_zlib_statep ps = png_ptr->zlib_state;
if (ps != NULL)
{
png_deflate_release(png_ptr, ps, 0/*check*/);
png_ptr->zlib_state = NULL;
png_free(png_ptr, ps);
}
}
/* Initialize the compressor for the appropriate type of compression. */
static png_zlib_statep
png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
png_alloc_size_t data_size)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
affirm(ps != NULL && png_ptr->zowner == 0);
{
int level = ps->zlib_level;
int method = ps->zlib_method;
int windowBits = ps->zlib_window_bits;
int memLevel = ps->zlib_mem_level;
int strategy = ps->zlib_strategy;
int ret; /* zlib return code */
if (owner != png_IDAT)
{
# ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
level = ps->zlib_text_level;
method = ps->zlib_text_method;
windowBits = ps->zlib_text_window_bits;
memLevel = ps->zlib_text_mem_level;
strategy = ps->zlib_text_strategy;
# else /* !WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
/* If customization is not supported the values all come from the
* IDAT values except for the strategy, which is fixed to the
* default. (This is the pre-1.6.0 behavior too, although it was
* implemented in a very different way.)
*/
strategy = Z_DEFAULT_STRATEGY;
# endif /* !WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
}
/* Adjust 'windowBits' down if larger than 'data_size'; to stop this
* happening just pass 32768 as the data_size parameter. Notice that zlib
* requires an extra 262 bytes in the window in addition to the data to be
* able to see the whole of the data, so if data_size+262 takes us to the
* next windowBits size we need to fix up the value later. (Because even
* though deflate needs the extra window, inflate does not!)
*/
if (data_size <= 16384U)
{
/* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to
* work round a Microsoft Visual C misbehavior which, contrary to C-90,
* widens the result of the following shift to 64-bits if (and,
* apparently, only if) it is used in a test.
*/
unsigned int half_window_size = 1U << (windowBits-1);
while (data_size + 262U <= half_window_size)
{
half_window_size >>= 1;
--windowBits;
}
}
/* Check against the previous initialized values, if any. */
if (ps->s.zs.state != NULL &&
(ps->zlib_set_level != level ||
ps->zlib_set_method != method ||
ps->zlib_set_window_bits != windowBits ||
ps->zlib_set_mem_level != memLevel ||
ps->zlib_set_strategy != strategy))
png_deflateEnd(png_ptr, &ps->s.zs, 0/*check*/);
/* For safety clear out the input and output pointers (currently zlib
* doesn't use them on Init, but it might in the future).
*/
ps->s.zs.next_in = NULL;
ps->s.zs.avail_in = 0;
ps->s.zs.next_out = NULL;
ps->s.zs.avail_out = 0;
/* The length fields must be cleared too and the lists reset: */
ps->s.overflow = ps->s.len = ps->s.start = 0U;
if (ps->s.list != NULL) /* error in prior chunk writing */
{
debug(ps->stash == NULL);
ps->stash = ps->s.list;
ps->s.list = NULL;
}
ps->s.end = &ps->s.list;
/* Now initialize if required, setting the new parameters, otherwise just
* do a simple reset to the previous parameters.
*/
if (ps->s.zs.state != NULL)
ret = deflateReset(&ps->s.zs);
else
ret = deflateInit2(&ps->s.zs, level, method, windowBits, memLevel,
strategy);
/* The return code is from either deflateReset or deflateInit2; they have
* pretty much the same set of error codes.
*/
if (ret == Z_OK && ps->s.zs.state != NULL)
png_ptr->zowner = owner;
else
{
png_zstream_error(&ps->s.zs, ret);
png_error(png_ptr, ps->s.zs.msg);
}
}
return ps;
}
#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED /* includes iCCP */
/* Compress the block of data at the end of a chunk. This claims and releases
* png_struct::z_stream. It returns the amount of data in the chunk list or
* zero on error (a zlib stream always contains some bytes!)
*
* prefix_len is the amount of (uncompressed) data before the start of the
* compressed data. The routine will return 0 if the total of the compressed
* data and the prefix exceeds PNG_UINT_MAX_31.
*
* NOTE: this function may not return; it only returns 0 if
* png_chunk_report(PNG_CHUNK_WRITE_ERROR) returns (not the default).
*/
static int /* success */
png_compress_chunk_data(png_structrp png_ptr, png_uint_32 chunk_name,
png_uint_32 prefix_len, png_const_voidp input, png_alloc_size_t input_len)
{
/* To find the length of the output it is necessary to first compress the
* input. The result is buffered rather than using the two-pass algorithm
* that is used on the inflate side; deflate is assumed to be slower and a
* PNG writer is assumed to have more memory available than a PNG reader.
*
* IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an
* upper limit on the output size, but it is always bigger than the input
* size so it is likely to be more efficient to use this linked-list
* approach.
*/
png_zlib_statep ps = png_deflate_claim(png_ptr, chunk_name, input_len);
affirm(ps != NULL);
/* The data compression function always returns so that we can clean up. */
ps->s.zs.next_in = PNGZ_INPUT_CAST(png_voidcast(const Bytef*, input));
/* Use the stash, if available: */
debug(ps->s.list == NULL);
ps->s.list = ps->stash;
ps->stash = NULL;
{
int ret = png_compress(&ps->s, input_len, PNG_UINT_31_MAX-prefix_len,
Z_FINISH);
ps->s.zs.next_out = NULL; /* safety */
ps->s.zs.avail_out = 0;
ps->s.zs.next_in = NULL;
ps->s.zs.avail_in = 0;
png_ptr->zowner = 0; /* release png_ptr::zstream */
/* Since Z_FINISH was passed as the flush parameter any result other than
* Z_STREAM_END is an error. In any case in the event of an error free
* the whole compression state; the only expected error is Z_MEM_ERROR.
*/
if (ret != Z_STREAM_END)
{
png_zlib_compress_destroy(&ps->s, 0/*check*/);
/* This is not very likely given the PNG_UINT_31_MAX limit above, but
* if code is added to limit the size of the chunks produced it can
* start to happen.
*/
if (ret == Z_BUF_ERROR)
ps->s.zs.msg = PNGZ_MSG_CAST("compressed chunk too long");
else
png_zstream_error(&ps->s.zs, ret);
png_chunk_report(png_ptr, ps->s.zs.msg, PNG_CHUNK_WRITE_ERROR);
return 0;
}
}
/* png_compress is meant to guarantee this on a successful return: */
affirm(ps->s.overflow == 0U && ps->s.len <= PNG_UINT_31_MAX - prefix_len);
# ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
/* Fix up the deflate header, if required (and possible): */
if (ps->s.len >= 2U)
optimize_cmf(png_ptr, ps->s.list->output, input_len);
# endif /* WRITE_OPTIMIZE_CMF */
return 1;
}
/* Return the length of the compressed data; this is effectively a debug
* function to catch inconsistencies caused by internal errors. It will
* disappear in a release build.
*/
#if PNG_RELEASE_BUILD
# define png_length_compressed_chunk_data(pp, p) ((pp)->zlib_state->s.len)
#else /* !RELEASE_BUILD */
static png_uint_32
png_length_compressed_chunk_data(png_structrp png_ptr, png_uint_32 p)
{
png_zlib_statep ps = png_ptr->zlib_state;
debug(ps != NULL && ps->s.overflow == 0U && ps->s.len <= PNG_UINT_31_MAX-p);
return ps->s.len;
}
#endif /* !RELEASE_BUILD */
/* Write all the data produced by the above function; the caller must write the
* prefix and chunk header.
*/
static void
png_write_compressed_chunk_data(png_structrp png_ptr)
{
png_zlib_statep ps = png_ptr->zlib_state;
png_compression_bufferp next;
png_uint_32 output_len;
affirm(ps != NULL && ps->s.overflow == 0U);
next = ps->s.list;
for (output_len = ps->s.len; output_len > 0U; next = next->next)
{
png_uint_32 size = PNG_ROW_BUFFER_SIZE;
/* If this affirm fails there is a bug in the calculation of
* output_length above, or in the buffer_limit code in png_compress.
*/
affirm(next != NULL && output_len > 0U);
if (size > output_len)
size = output_len;
png_write_chunk_data(png_ptr, next->output, size);
output_len -= size;
}
/* Release the list back to the stash. */
debug(ps->stash == NULL);
ps->stash = ps->s.list;
ps->s.list = NULL;
ps->s.end = &ps->s.list;
}
#endif /* WRITE_COMPRESSED_TEXT */
#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
* and if invalid, correct the keyword rather than discarding the entire
* chunk. The PNG 1.0 specification requires keywords 1-79 characters in
* length, forbids leading or trailing whitespace, multiple internal spaces,
* and the non-break space (0x80) from ISO 8859-1. Returns keyword length.
*
* The 'new_key' buffer must be at least 80 characters in size (for the keyword
* plus a trailing '\0'). If this routine returns 0 then there was no keyword,
* or a valid one could not be generated, and the caller must CHUNK_WRITE_ERROR.
*/
static unsigned int
png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
{
png_const_charp orig_key = key;
unsigned int key_len = 0;
int bad_character = 0;
int space = 1;
png_debug(1, "in png_check_keyword");
if (key == NULL)
{
*new_key = 0;
return 0;
}
while (*key && key_len < 79)
{
png_byte ch = (png_byte)(0xff & *key++);
if ((ch > 32 && ch <= 126) || (ch >= 161 /*&& ch <= 255*/))
*new_key++ = ch, ++key_len, space = 0;
else if (space == 0)
{
/* A space or an invalid character when one wasn't seen immediately
* before; output just a space.
*/
*new_key++ = 32, ++key_len, space = 1;
/* If the character was not a space then it is invalid. */
if (ch != 32)
bad_character = ch;
}
else if (bad_character == 0)
bad_character = ch; /* just skip it, record the first error */
}
if (key_len > 0 && space != 0) /* trailing space */
{
--key_len, --new_key;
if (bad_character == 0)
bad_character = 32;
}
/* Terminate the keyword */
*new_key = 0;
if (key_len == 0)
return 0;
#ifdef PNG_WARNINGS_SUPPORTED
/* Try to only output one warning per keyword: */
if (*key != 0) /* keyword too long */
png_app_warning(png_ptr, "keyword truncated");
else if (bad_character != 0)
{
PNG_WARNING_PARAMETERS(p)
png_warning_parameter(p, 1, orig_key);
png_warning_parameter_signed(p, 2, PNG_NUMBER_FORMAT_02x, bad_character);
png_formatted_warning(png_ptr, p, "keyword \"@1\": bad character '0x@2'");
}
#endif /* WARNINGS */
return key_len;
}
#endif /* WRITE_TEXT || WRITE_pCAL || WRITE_iCCP || WRITE_sPLT */
/* Write the IHDR chunk, and update the png_struct with the necessary
* information. Note that the rest of this code depends upon this
* information being correct.
*/
void /* PRIVATE */
png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
int bit_depth, int color_type, int compression_type, int filter_method,
int interlace_type)
{
png_byte buf[13]; /* Buffer to store the IHDR info */
png_debug(1, "in png_write_IHDR");
/* Check that we have valid input data from the application info */
switch (color_type)
{
case PNG_COLOR_TYPE_GRAY:
switch (bit_depth)
{
case 1:
case 2:
case 4:
case 8:
#ifdef PNG_WRITE_16BIT_SUPPORTED
case 16:
#endif
break;
default:
png_error(png_ptr, "Invalid bit depth for grayscale image");
}
break;
case PNG_COLOR_TYPE_RGB:
#ifdef PNG_WRITE_16BIT_SUPPORTED
if (bit_depth != 8 && bit_depth != 16)
#else
if (bit_depth != 8)
#endif
png_error(png_ptr, "Invalid bit depth for RGB image");
break;
case PNG_COLOR_TYPE_PALETTE:
switch (bit_depth)
{
case 1:
case 2:
case 4:
case 8:
break;
default:
png_error(png_ptr, "Invalid bit depth for paletted image");
}
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
if (bit_depth != 8 && bit_depth != 16)
png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
#ifdef PNG_WRITE_16BIT_SUPPORTED
if (bit_depth != 8 && bit_depth != 16)
#else
if (bit_depth != 8)
#endif
png_error(png_ptr, "Invalid bit depth for RGBA image");
break;
default:
png_error(png_ptr, "Invalid image color type specified");
}
if (compression_type != PNG_COMPRESSION_TYPE_BASE)
{
png_app_error(png_ptr, "Invalid compression type specified");
compression_type = PNG_COMPRESSION_TYPE_BASE;
}
/* Write filter_method 64 (intrapixel differencing) only if
* 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
* 2. Libpng did not write a PNG signature (this filter_method is only
* used in PNG datastreams that are embedded in MNG datastreams) and
* 3. The application called png_permit_mng_features with a mask that
* included PNG_FLAG_MNG_FILTER_64 and
* 4. The filter_method is 64 and
* 5. The color_type is RGB or RGBA
*/
if (
# ifdef PNG_MNG_FEATURES_SUPPORTED
!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
(color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
(filter_method == PNG_INTRAPIXEL_DIFFERENCING)) &&
# endif /* MNG_FEATURES */
filter_method != PNG_FILTER_TYPE_BASE)
{
png_app_error(png_ptr, "Invalid filter type specified");
filter_method = PNG_FILTER_TYPE_BASE;
}
if (interlace_type != PNG_INTERLACE_NONE &&
interlace_type != PNG_INTERLACE_ADAM7)
{
png_app_error(png_ptr, "Invalid interlace type specified");
interlace_type = PNG_INTERLACE_ADAM7;
}
/* Save the relevant information */
png_ptr->bit_depth = png_check_byte(png_ptr, bit_depth);
png_ptr->color_type = png_check_byte(png_ptr, color_type);
png_ptr->interlaced = png_check_byte(png_ptr, interlace_type);
png_ptr->filter_method = png_check_byte(png_ptr, filter_method);
png_ptr->compression_type = png_check_byte(png_ptr, compression_type);
png_ptr->width = width;
png_ptr->height = height;
/* Pack the header information into the buffer */
png_save_uint_32(buf, width);
png_save_uint_32(buf + 4, height);
buf[8] = png_check_byte(png_ptr, bit_depth);
buf[9] = png_check_byte(png_ptr, color_type);
buf[10] = png_check_byte(png_ptr, compression_type);
buf[11] = png_check_byte(png_ptr, filter_method);
buf[12] = png_check_byte(png_ptr, interlace_type);
/* Write the chunk */
png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
png_ptr->mode |= PNG_HAVE_IHDR;
}
/* Write the palette. We are careful not to trust png_color to be in the
* correct order for PNG, so people can redefine it to any convenient
* structure.
*/
void /* PRIVATE */
png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
unsigned int num_pal)
{
png_uint_32 max_palette_length, i;
png_const_colorp pal_ptr;
png_byte buf[3];
png_debug(1, "in png_write_PLTE");
max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
(1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;
if ((
# ifdef PNG_MNG_FEATURES_SUPPORTED
(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 &&
# endif /* MNG_FEATURES */
num_pal == 0) || num_pal > max_palette_length)
{
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
png_error(png_ptr, "Invalid number of colors in palette");
}
else
{
png_warning(png_ptr, "Invalid number of colors in palette");
return;
}
}
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
{
png_warning(png_ptr,
"Ignoring request to write a PLTE chunk in grayscale PNG");
return;
}
png_ptr->num_palette = png_check_bits(png_ptr, num_pal, 9);
png_debug1(3, "num_palette = %d", png_ptr->num_palette);
png_write_chunk_header(png_ptr, png_PLTE, num_pal * 3U);
for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
{
buf[0] = pal_ptr->red;
buf[1] = pal_ptr->green;
buf[2] = pal_ptr->blue;
png_write_chunk_data(png_ptr, buf, 3U);
}
png_write_chunk_end(png_ptr);
png_ptr->mode |= PNG_HAVE_PLTE;
}
/* Write an IEND chunk */
void /* PRIVATE */
png_write_IEND(png_structrp png_ptr)
{
png_debug(1, "in png_write_IEND");
png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
png_ptr->mode |= PNG_HAVE_IEND;
}
#if defined(PNG_WRITE_gAMA_SUPPORTED) || defined(PNG_WRITE_cHRM_SUPPORTED)
static int
png_save_int_31(png_structrp png_ptr, png_bytep buf, png_int_32 i)
/* Save a signed value as a PNG unsigned value; the argument is required to
* be in the range 0..0x7FFFFFFFU. If not a *warning* is produced and false
* is returned. Because this is only called from png_write_cHRM_fixed and
* png_write_gAMA_fixed below this is safe (we don't need either chunk,
* particularly if the value is bogus.)
*
* The warning is png_app_error; it may return if the app tells it to but the
* app can have it error out. JB 20150821: I believe the checking in png.c
* actually makes this error impossible, but this is safe.
*/
{
#ifndef __COVERITY__
if (i >= 0 && i <= 0x7FFFFFFF)
#else
/* Supress bogus Coverity complaint */
if (i >= 0)
#endif
{
png_save_uint_32(buf, (png_uint_32)/*SAFE*/i);
return 1;
}
else
{
png_chunk_report(png_ptr, "negative value in cHRM or gAMA",
PNG_CHUNK_WRITE_ERROR);
return 0;
}
}
#endif /* WRITE_gAMA || WRITE_cHRM */
#ifdef PNG_WRITE_gAMA_SUPPORTED
/* Write a gAMA chunk */
void /* PRIVATE */
png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma)
{
png_byte buf[4];
png_debug(1, "in png_write_gAMA");
/* file_gamma is saved in 1/100,000ths */
if (png_save_int_31(png_ptr, buf, file_gamma))
png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
}
#endif
#ifdef PNG_WRITE_sRGB_SUPPORTED
/* Write a sRGB chunk */
void /* PRIVATE */
png_write_sRGB(png_structrp png_ptr, int srgb_intent)
{
png_byte buf[1];
png_debug(1, "in png_write_sRGB");
if (srgb_intent >= PNG_sRGB_INTENT_LAST)
png_chunk_report(png_ptr, "Invalid sRGB rendering intent specified",
PNG_CHUNK_WRITE_ERROR);
buf[0] = png_check_byte(png_ptr, srgb_intent);
png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
}
#endif
#ifdef PNG_WRITE_iCCP_SUPPORTED
/* Write an iCCP chunk */
void /* PRIVATE */
png_write_iCCP(png_structrp png_ptr, png_const_charp name,
png_const_voidp profile)
{
png_uint_32 name_len;
png_uint_32 profile_len;
png_byte new_name[81]; /* 1 byte for the compression byte */
png_debug(1, "in png_write_iCCP");
affirm(profile != NULL);
profile_len = png_get_uint_32(profile);
name_len = png_check_keyword(png_ptr, name, new_name);
if (name_len == 0)
{
png_chunk_report(png_ptr, "iCCP: invalid keyword", PNG_CHUNK_WRITE_ERROR);
return;
}
++name_len; /* trailing '\0' */
new_name[name_len++] = PNG_COMPRESSION_TYPE_BASE;
if (png_compress_chunk_data(png_ptr, png_iCCP, name_len, profile,
profile_len))
{
png_write_chunk_header(png_ptr, png_iCCP,
name_len+png_length_compressed_chunk_data(png_ptr, name_len));
png_write_chunk_data(png_ptr, new_name, name_len);
png_write_compressed_chunk_data(png_ptr);
png_write_chunk_end(png_ptr);
}
}
#endif
#ifdef PNG_WRITE_sPLT_SUPPORTED
/* Write a sPLT chunk */
void /* PRIVATE */
png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
{
png_uint_32 name_len;
png_byte new_name[80];
png_byte entrybuf[10];
png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
png_size_t palette_size = entry_size * spalette->nentries;
png_sPLT_entryp ep;
png_debug(1, "in png_write_sPLT");
name_len = png_check_keyword(png_ptr, spalette->name, new_name);
if (name_len == 0)
png_error(png_ptr, "sPLT: invalid keyword");
/* Make sure we include the NULL after the name */
png_write_chunk_header(png_ptr, png_sPLT,
(png_uint_32)(name_len + 2 + palette_size));
png_write_chunk_data(png_ptr, new_name, name_len + 1);
png_write_chunk_data(png_ptr, &spalette->depth, 1);
/* Loop through each palette entry, writing appropriately */
for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
{
if (spalette->depth == 8)
{
entrybuf[0] = png_check_byte(png_ptr, ep->red);
entrybuf[1] = png_check_byte(png_ptr, ep->green);
entrybuf[2] = png_check_byte(png_ptr, ep->blue);
entrybuf[3] = png_check_byte(png_ptr, ep->alpha);
png_save_uint_16(entrybuf + 4, ep->frequency);
}
else
{
png_save_uint_16(entrybuf + 0, ep->red);
png_save_uint_16(entrybuf + 2, ep->green);
png_save_uint_16(entrybuf + 4, ep->blue);
png_save_uint_16(entrybuf + 6, ep->alpha);
png_save_uint_16(entrybuf + 8, ep->frequency);
}
png_write_chunk_data(png_ptr, entrybuf, entry_size);
}
png_write_chunk_end(png_ptr);
}
#endif
#ifdef PNG_WRITE_sBIT_SUPPORTED
/* Write the sBIT chunk */
void /* PRIVATE */
png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
{
png_byte buf[4];
png_size_t size;
png_debug(1, "in png_write_sBIT");
/* Make sure we don't depend upon the order of PNG_COLOR_8 */
if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
{
unsigned int maxbits;
maxbits = color_type==PNG_COLOR_TYPE_PALETTE ? 8 : png_ptr->bit_depth;
if (sbit->red == 0 || sbit->red > maxbits ||
sbit->green == 0 || sbit->green > maxbits ||
sbit->blue == 0 || sbit->blue > maxbits)
{
png_app_error(png_ptr, "Invalid sBIT depth specified");
return;
}
buf[0] = sbit->red;
buf[1] = sbit->green;
buf[2] = sbit->blue;
size = 3;
}
else
{
if (sbit->gray == 0 || sbit->gray > png_ptr->bit_depth)
{
png_app_error(png_ptr, "Invalid sBIT depth specified");
return;
}
buf[0] = sbit->gray;
size = 1;
}
if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
{
if (sbit->alpha == 0 || sbit->alpha > png_ptr->bit_depth)
{
png_app_error(png_ptr, "Invalid sBIT depth specified");
return;
}
buf[size++] = sbit->alpha;
}
png_write_complete_chunk(png_ptr, png_sBIT, buf, size);
}
#endif
#ifdef PNG_WRITE_cHRM_SUPPORTED
/* Write the cHRM chunk */
void /* PRIVATE */
png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy)
{
png_byte buf[32];
png_debug(1, "in png_write_cHRM");
/* Each value is saved in 1/100,000ths */
if (png_save_int_31(png_ptr, buf, xy->whitex) &&
png_save_int_31(png_ptr, buf + 4, xy->whitey) &&
png_save_int_31(png_ptr, buf + 8, xy->redx) &&
png_save_int_31(png_ptr, buf + 12, xy->redy) &&
png_save_int_31(png_ptr, buf + 16, xy->greenx) &&
png_save_int_31(png_ptr, buf + 20, xy->greeny) &&
png_save_int_31(png_ptr, buf + 24, xy->bluex) &&
png_save_int_31(png_ptr, buf + 28, xy->bluey))
png_write_complete_chunk(png_ptr, png_cHRM, buf, 32);
}
#endif
#ifdef PNG_WRITE_tRNS_SUPPORTED
/* Write the tRNS chunk */
void /* PRIVATE */
png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
png_const_color_16p tran, int num_trans, int color_type)
{
png_byte buf[6];
png_debug(1, "in png_write_tRNS");
if (color_type == PNG_COLOR_TYPE_PALETTE)
{
affirm(num_trans > 0 && num_trans <= PNG_MAX_PALETTE_LENGTH);
{
# ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
union
{
png_uint_32 u32[1];
png_byte b8[PNG_MAX_PALETTE_LENGTH];
} inverted_alpha;
/* Invert the alpha channel (in tRNS) if required */
if (png_ptr->write_invert_alpha)
{
int i;
memcpy(inverted_alpha.b8, trans_alpha, num_trans);
for (i=0; 4*i<num_trans; ++i)
inverted_alpha.u32[i] = ~inverted_alpha.u32[i];
trans_alpha = inverted_alpha.b8;
}
# endif /* WRITE_INVERT_ALPHA */
png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha, num_trans);
}
}
else if (color_type == PNG_COLOR_TYPE_GRAY)
{
/* One 16 bit value */
affirm(tran->gray < (1 << png_ptr->bit_depth));
png_save_uint_16(buf, tran->gray);
png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
}
else if (color_type == PNG_COLOR_TYPE_RGB)
{
/* Three 16 bit values */
png_save_uint_16(buf, tran->red);
png_save_uint_16(buf + 2, tran->green);
png_save_uint_16(buf + 4, tran->blue);
affirm(png_ptr->bit_depth == 8 || (buf[0] | buf[2] | buf[4]) == 0);
png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
}
else /* Already checked in png_set_tRNS */
impossible("invalid tRNS");
}
#endif
#ifdef PNG_WRITE_bKGD_SUPPORTED
/* Write the background chunk */
void /* PRIVATE */
png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
{
png_byte buf[6];
png_debug(1, "in png_write_bKGD");
if (color_type == PNG_COLOR_TYPE_PALETTE)
{
if (
# ifdef PNG_MNG_FEATURES_SUPPORTED
(png_ptr->num_palette != 0 ||
(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) &&
# endif /* MNG_FEATURES */
back->index >= png_ptr->num_palette)
{
png_app_error(png_ptr, "Invalid background palette index");
return;
}
buf[0] = back->index;
png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
}
else if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
{
png_save_uint_16(buf, back->red);
png_save_uint_16(buf + 2, back->green);
png_save_uint_16(buf + 4, back->blue);
#ifdef PNG_WRITE_16BIT_SUPPORTED
if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
#else
if ((buf[0] | buf[2] | buf[4]) != 0)
#endif
{
png_app_error(png_ptr,
"Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
return;
}
png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
}
else
{
if (back->gray >= (1 << png_ptr->bit_depth))
{
png_app_error(png_ptr,
"Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
return;
}
png_save_uint_16(buf, back->gray);
png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
}
}
#endif
#ifdef PNG_WRITE_hIST_SUPPORTED
/* Write the histogram */
void /* PRIVATE */
png_write_hIST(png_structrp png_ptr, png_const_uint_16p hist, int num_hist)
{
int i;
png_byte buf[3];
png_debug(1, "in png_write_hIST");
if (num_hist > (int)png_ptr->num_palette)
{
png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,
png_ptr->num_palette);
png_warning(png_ptr, "Invalid number of histogram entries specified");
return;
}
png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));
for (i = 0; i < num_hist; i++)
{
png_save_uint_16(buf, hist[i]);
png_write_chunk_data(png_ptr, buf, (png_size_t)2);
}
png_write_chunk_end(png_ptr);
}
#endif
#ifdef PNG_WRITE_tEXt_SUPPORTED
/* Write a tEXt chunk */
void /* PRIVATE */
png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
png_size_t text_len)
{
unsigned int key_len;
png_byte new_key[80];
png_debug(1, "in png_write_tEXt");
key_len = png_check_keyword(png_ptr, key, new_key);
if (key_len == 0)
{
png_chunk_report(png_ptr, "tEXt: invalid keyword", PNG_CHUNK_WRITE_ERROR);
return;
}
if (text == NULL || *text == '\0')
text_len = 0;
else
text_len = strlen(text);
if (text_len > PNG_UINT_31_MAX - (key_len+1))
{
png_chunk_report(png_ptr, "tEXt: text too long", PNG_CHUNK_WRITE_ERROR);
return;
}
/* Make sure we include the 0 after the key */
png_write_chunk_header(png_ptr, png_tEXt,
(png_uint_32)/*checked above*/(key_len + text_len + 1));
/*
* We leave it to the application to meet PNG-1.0 requirements on the
* contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
* any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
* The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
*/
png_write_chunk_data(png_ptr, new_key, key_len + 1);
if (text_len != 0)
png_write_chunk_data(png_ptr, (png_const_bytep)text, text_len);
png_write_chunk_end(png_ptr);
}
#endif
#ifdef PNG_WRITE_zTXt_SUPPORTED
/* Write a compressed text chunk */
void /* PRIVATE */
png_write_zTXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
int compression)
{
unsigned int key_len;
png_byte new_key[81];
png_debug(1, "in png_write_zTXt");
if (compression != PNG_TEXT_COMPRESSION_zTXt)
png_app_warning(png_ptr, "zTXt: invalid compression type ignored");
key_len = png_check_keyword(png_ptr, key, new_key);
if (key_len == 0)
{
png_chunk_report(png_ptr, "zTXt: invalid keyword", PNG_CHUNK_WRITE_ERROR);
return;
}
/* Add the compression method and 1 for the keyword separator. */
++key_len;
new_key[key_len++] = PNG_COMPRESSION_TYPE_BASE;
if (png_compress_chunk_data(png_ptr, png_zTXt, key_len, text, strlen(text)))
{
png_write_chunk_header(png_ptr, png_zTXt,
key_len+png_length_compressed_chunk_data(png_ptr, key_len));
png_write_chunk_data(png_ptr, new_key, key_len);
png_write_compressed_chunk_data(png_ptr);
png_write_chunk_end(png_ptr);
}
/* else chunk report already issued and ignored */
}
#endif
#ifdef PNG_WRITE_iTXt_SUPPORTED
/* Write an iTXt chunk */
void /* PRIVATE */
png_write_iTXt(png_structrp png_ptr, int compression, png_const_charp key,
png_const_charp lang, png_const_charp lang_key, png_const_charp text)
{
png_uint_32 key_len, prefix_len, data_len;
png_size_t lang_len, lang_key_len, text_len;
png_byte new_key[82]; /* 80 bytes for the key, 2 byte compression info */
png_debug(1, "in png_write_iTXt");
key_len = png_check_keyword(png_ptr, key, new_key);
if (key_len == 0)
{
png_chunk_report(png_ptr, "iTXt: invalid keyword", PNG_CHUNK_WRITE_ERROR);
return;
}
debug(new_key[key_len] == 0);
++key_len; /* terminating 0 added by png_check_keyword */
/* Set the compression flag */
switch (compression)
{
case PNG_ITXT_COMPRESSION_NONE:
case PNG_TEXT_COMPRESSION_NONE:
compression = new_key[key_len++] = 0; /* no compression */
break;
case PNG_TEXT_COMPRESSION_zTXt:
case PNG_ITXT_COMPRESSION_zTXt:
compression = new_key[key_len++] = 1; /* compressed */
break;
default:
png_chunk_report(png_ptr, "iTXt: invalid compression",
PNG_CHUNK_WRITE_ERROR);
return;
}
new_key[key_len++] = PNG_COMPRESSION_TYPE_BASE;
/* We leave it to the application to meet PNG-1.0 requirements on the
* contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
* any non-Latin-1 characters except for NEWLINE (yes, this is really weird
* in an 'international' text string. ISO PNG, however, specifies that the
* text is UTF-8 and this *IS NOT YET CHECKED*, so invalid sequences may be
* present.
*
* The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
*
* TODO: validate the language tag correctly (see the spec.)
*/
if (lang == NULL) lang = ""; /* empty language is valid */
lang_len = strlen(lang)+1U;
if (lang_key == NULL) lang_key = ""; /* may be empty */
lang_key_len = strlen(lang_key)+1U;
if (text == NULL) text = ""; /* may be empty */
if (lang_len > PNG_UINT_31_MAX-key_len ||
lang_key_len > PNG_UINT_31_MAX-key_len-lang_len)
{
png_chunk_report(png_ptr, "iTXt: prefix too long", PNG_CHUNK_WRITE_ERROR);
return;
}
prefix_len = (png_uint_32)/*SAFE*/(key_len+lang_len+lang_key_len);
text_len = strlen(text); /* no trailing '\0' */
if (compression != 0)
{
if (png_compress_chunk_data(png_ptr, png_iTXt, prefix_len, text,
text_len))
data_len = png_length_compressed_chunk_data(png_ptr, prefix_len);
else
return; /* chunk report already issued and ignored */
}
else
{
if (text_len > PNG_UINT_31_MAX-prefix_len)
{
png_chunk_report(png_ptr, "iTXt: text too long",
PNG_CHUNK_WRITE_ERROR);
return;
}
data_len = (png_uint_32)/*SAFE*/text_len;
}
png_write_chunk_header(png_ptr, png_iTXt, prefix_len+data_len);
png_write_chunk_data(png_ptr, new_key, key_len);
png_write_chunk_data(png_ptr, lang, lang_len);
png_write_chunk_data(png_ptr, lang_key, lang_key_len);
if (compression != 0)
png_write_compressed_chunk_data(png_ptr);
else
png_write_chunk_data(png_ptr, text, data_len);
png_write_chunk_end(png_ptr);
}
#endif /* WRITE_iTXt */
#if defined(PNG_WRITE_oFFs_SUPPORTED) ||\
defined(PNG_WRITE_pCAL_SUPPORTED)
/* PNG signed integers are saved in 32-bit 2's complement format. ANSI C-90
* defines a cast of a signed integer to an unsigned integer either to preserve
* the value, if it is positive, or to calculate:
*
* (UNSIGNED_MAX+1) + integer
*
* Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the
* negative integral value is added the result will be an unsigned value
* correspnding to the 2's complement representation.
*/
static int
save_int_32(png_structrp png_ptr, png_bytep buf, png_int_32 j)
{
png_uint_32 i = 0xFFFFFFFFU & (png_uint_32)/*SAFE & CORRECT*/j;
if (i != 0x80000000U/*value not permitted*/)
{
png_save_uint_32(buf, i);
return 1;
}
else
{
png_chunk_report(png_ptr, "invalid value in oFFS or pCAL",
PNG_CHUNK_WRITE_ERROR);
return 0;
}
}
#endif /* WRITE_oFFs || WRITE_pCAL */
#ifdef PNG_WRITE_oFFs_SUPPORTED
/* Write the oFFs chunk */
void /* PRIVATE */
png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
int unit_type)
{
png_byte buf[9];
png_debug(1, "in png_write_oFFs");
if (unit_type >= PNG_OFFSET_LAST)
png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
if (save_int_32(png_ptr, buf, x_offset) &&
save_int_32(png_ptr, buf + 4, y_offset))
{
/* unit type is 0 or 1, this has been checked already so the following
* is safe:
*/
buf[8] = unit_type != 0;
png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
}
}
#endif /* WRITE_oFFs */
#ifdef PNG_WRITE_pCAL_SUPPORTED
/* Write the pCAL chunk (described in the PNG extensions document) */
void /* PRIVATE */
png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0,
png_int_32 X1, int type, int nparams, png_const_charp units,
png_charpp params)
{
png_uint_32 purpose_len;
size_t units_len;
png_byte buf[10];
png_byte new_purpose[80];
png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
if (type >= PNG_EQUATION_LAST)
png_error(png_ptr, "Unrecognized equation type for pCAL chunk");
purpose_len = png_check_keyword(png_ptr, purpose, new_purpose);
if (purpose_len == 0)
png_error(png_ptr, "pCAL: invalid keyword");
++purpose_len; /* terminator */
png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
units_len = strlen(units) + (nparams == 0 ? 0 : 1);
png_debug1(3, "pCAL units length = %d", (int)units_len);
if (save_int_32(png_ptr, buf, X0) &&
save_int_32(png_ptr, buf + 4, X1))
{
png_size_tp params_len = png_voidcast(png_size_tp,
png_malloc(png_ptr, nparams * sizeof (png_size_t)));
int i;
size_t total_len = purpose_len + units_len + 10;
/* Find the length of each parameter, making sure we don't count the
* null terminator for the last parameter.
*/
for (i = 0; i < nparams; i++)
{
params_len[i] = strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
png_debug2(3, "pCAL parameter %d length = %lu", i,
(unsigned long)params_len[i]);
total_len += params_len[i];
}
png_debug1(3, "pCAL total length = %d", (int)total_len);
png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
png_write_chunk_data(png_ptr, new_purpose, purpose_len);
buf[8] = png_check_byte(png_ptr, type);
buf[9] = png_check_byte(png_ptr, nparams);
png_write_chunk_data(png_ptr, buf, (png_size_t)10);
png_write_chunk_data(png_ptr, (png_const_bytep)units,
(png_size_t)units_len);
for (i = 0; i < nparams; i++)
png_write_chunk_data(png_ptr, (png_const_bytep)params[i],
params_len[i]);
png_free(png_ptr, params_len);
png_write_chunk_end(png_ptr);
}
}
#endif /* WRITE_pCAL */
#ifdef PNG_WRITE_sCAL_SUPPORTED
/* Write the sCAL chunk */
void /* PRIVATE */
png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width,
png_const_charp height)
{
png_byte buf[64];
png_size_t wlen, hlen, total_len;
png_debug(1, "in png_write_sCAL_s");
wlen = strlen(width);
hlen = strlen(height);
total_len = wlen + hlen + 2;
if (total_len > 64)
{
png_warning(png_ptr, "Can't write sCAL (buffer too small)");
return;
}
buf[0] = png_check_byte(png_ptr, unit);
memcpy(buf + 1, width, wlen + 1); /* Append the '\0' here */
memcpy(buf + wlen + 2, height, hlen); /* Do NOT append the '\0' here */
png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len);
}
#endif
#ifdef PNG_WRITE_pHYs_SUPPORTED
/* Write the pHYs chunk */
void /* PRIVATE */
png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit,
png_uint_32 y_pixels_per_unit,
int unit_type)
{
png_byte buf[9];
png_debug(1, "in png_write_pHYs");
if (unit_type >= PNG_RESOLUTION_LAST)
png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
png_save_uint_32(buf, x_pixels_per_unit);
png_save_uint_32(buf + 4, y_pixels_per_unit);
buf[8] = png_check_byte(png_ptr, unit_type);
png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
}
#endif
#ifdef PNG_WRITE_tIME_SUPPORTED
/* Write the tIME chunk. Use either png_convert_from_struct_tm()
* or png_convert_from_time_t(), or fill in the structure yourself.
*/
void /* PRIVATE */
png_write_tIME(png_structrp png_ptr, png_const_timep mod_time)
{
png_byte buf[7];
png_debug(1, "in png_write_tIME");
if (mod_time->month > 12 || mod_time->month < 1 ||
mod_time->day > 31 || mod_time->day < 1 ||
mod_time->hour > 23 || mod_time->second > 60)
{
png_warning(png_ptr, "Invalid time specified for tIME chunk");
return;
}
png_save_uint_16(buf, mod_time->year);
buf[2] = mod_time->month;
buf[3] = mod_time->day;
buf[4] = mod_time->hour;
buf[5] = mod_time->minute;
buf[6] = mod_time->second;
png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
}
#endif
/* These two #defines simplify writing code that depends on one or the other of
* the options being both supported and on:
*/
#ifdef PNG_SELECT_FILTER_METHODICALLY_SUPPORTED
# define methodical_option\
((png_ptr->options >> PNG_SELECT_FILTER_METHODICALLY) & 3U)
#else
# define methodical_option PNG_OPTION_OFF
#endif
#ifdef PNG_SELECT_FILTER_HEURISTICALLY_SUPPORTED
# define heuristic_option\
((png_ptr->options >> PNG_SELECT_FILTER_HEURISTICALLY) & 3U)
#else /* !SELECT_FILTER_HEURISTICALLY */
# define heuristic_option PNG_OPTION_OFF
#endif /* !SELECT_FILTER_HEURISTICALLY */
/* Handle the writing of IDAT chunks from the png_zlib_state in
* png_ptr->zlib_state.
*/
static void
png_start_IDAT(png_structrp png_ptr)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
# ifdef PNG_WRITE_FILTER_SUPPORTED
/* Default both filter_mask and zlib_strategy here, now that png_ptr has
* all the IHDR fields set.
*/
if (ps && ps->filter_mask == PNG_NO_FILTERS/*unset*/)
{
/* If there is no filter selection algorithm enabled then the only
* option is PNG_FILTER_NONE.
*/
if (methodical_option == PNG_OPTION_OFF &&
heuristic_option == PNG_OPTION_OFF)
ps->filter_mask = PNG_FILTER_NONE;
else
ps->filter_mask = PNG_ALL_FILTERS;
}
# endif /* WRITE_FILTER */
if (ps && ps->zlib_strategy == (-1)/*unset*/)
{
# ifdef PNG_WRITE_FILTER_SUPPORTED
if (ps->filter_mask != PNG_FILTER_NONE)
ps->zlib_strategy = PNG_Z_DEFAULT_STRATEGY;
else
# endif /* WRITE_FILTER */
/* The default with no filters: */
ps->zlib_strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY;
}
/* This always succeeds or does a png_error: */
png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr));
}
static void
png_end_IDAT(png_structrp png_ptr)
{
png_zlib_statep ps = png_ptr->zlib_state;
png_ptr->zowner = 0U; /* release the stream */
if (ps != NULL)
png_deflate_release(png_ptr, ps, 1/*check*/);
}
static void
png_write_IDAT(png_structrp png_ptr, int flush)
{
png_zlib_statep ps = png_ptr->zlib_state;
/* Check for a correctly initialized list, the requirement that the end
* pointer is NULL means that the end of the list can be easily detected.
*/
affirm(ps != NULL && ps->s.end != NULL && *ps->s.end == NULL);
png_zlib_compress_validate(&png_ptr->zlib_state->s, 0/*in_use*/);
/* Write IDAT chunks while either 'flush' is true or there are at
* least png_ptr->IDAT_size bytes available to be written.
*/
for (;;)
{
png_uint_32 len = png_ptr->IDAT_size;
if (ps->s.overflow == 0U)
{
png_uint_32 avail = ps->s.len;
if (avail < len)
{
/* When end_of_image is true everything gets written, otherwise
* there must be at least IDAT_size bytes available.
*/
if (!flush)
return;
if (avail == 0U)
break;
len = avail;
}
}
png_write_chunk_header(png_ptr, png_IDAT, len);
/* Write bytes from the buffer list, adjusting {overflow,len} as they are
* written.
*/
do
{
png_compression_bufferp next = ps->s.list;
unsigned int avail = sizeof next->output;
unsigned int start = ps->s.start;
unsigned int written;
affirm(next != NULL);
if (next->next == NULL) /* end of list */
{
/* The z_stream should always be pointing into this output buffer,
* the buffer may not be full:
*/
debug(ps->s.zs.next_out + ps->s.zs.avail_out ==
next->output + sizeof next->output);
avail -= ps->s.zs.avail_out;
}
else /* not end of list */
debug((ps->s.zs.next_out < next->output ||
ps->s.zs.next_out > next->output + sizeof next->output) &&
(ps->s.overflow > 0 ||
ps->s.start + ps->s.len >= sizeof next->output));
/* First, if this is the very first IDAT (PNG_HAVE_IDAT not set)
* optimize the CINFO field:
*/
# ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
if ((png_ptr->mode & PNG_HAVE_IDAT) == 0U &&
avail >= start+2U /* enough for the zlib header */)
{
debug(start == 0U);
optimize_cmf(png_ptr, next->output+start,
png_image_size(png_ptr));
}
else /* always expect to see at least 2 bytes: */
debug((png_ptr->mode & PNG_HAVE_IDAT) != 0U);
# endif /* WRITE_OPTIMIZE_CMF */
/* Set this now to prevent the above happening again second time round
* the loop:
*/
png_ptr->mode |= PNG_HAVE_IDAT;
if (avail <= start+len)
{
/* Write all of this buffer: */
affirm(avail > start); /* else overflow on the subtract */
written = avail-start;
png_write_chunk_data(png_ptr, next->output+start, written);
/* At the end there are no buffers in the list but the z_stream
* still points into the old (just released) buffer. This can
* happen when the old buffer is not full if the compressed bytes
* exactly match the IDAT length; it should always happen when
* end_of_image is set.
*/
ps->s.list = next->next;
if (next->next == NULL)
{
debug(avail == start+len);
ps->s.end = &ps->s.list;
ps->s.zs.next_out = NULL;
ps->s.zs.avail_out = 0U;
}
next->next = ps->stash;
ps->stash = next;
ps->s.start = 0U;
}
else /* write only part of this buffer */
{
written = len;
png_write_chunk_data(png_ptr, next->output+start, written);
ps->s.start = (unsigned int)/*SAFE*/(start + written);
}
/* 'written' bytes were written: */
len -= written;
if (written <= ps->s.len)
ps->s.len -= written;
else
{
affirm(ps->s.overflow > 0U);
--ps->s.overflow;
ps->s.len += 0x80000000U - written;
UNTESTED
}
}
while (len > 0U);
png_write_chunk_end(png_ptr);
}
/* avail == 0 && flush */
png_end_IDAT(png_ptr);
png_ptr->mode |= PNG_AFTER_IDAT;
}
/* This is is a convenience wrapper to handle IDAT compression; it takes a
* pointer to the input data and places no limit on the size of the output but
* is otherwise the same as png_compress(). It also handles the use of the
* stash (only used for IDAT compression.)
*/
static int
png_compress_IDAT_data(png_const_structrp png_ptr, png_zlib_statep ps,
png_zlib_compressp pz, png_const_voidp input, uInt input_len, int flush)
{
affirm(png_ptr->zowner == png_IDAT && pz->end != NULL && *pz->end == NULL);
/* z_stream::{next,avail}_out are set by png_compress to point into the
* buffer list. next_in must be set here, avail_in comes from the input_len
* parameter:
*/
pz->zs.next_in = PNGZ_INPUT_CAST(png_voidcast(const Bytef*, input));
*pz->end = ps->stash; /* May be NULL */
ps->stash = NULL;
/* zlib buffers the output, the maximum amount of compressed data that can be
* produced here is governed by the amount of buffering.
*/
{
int ret = png_compress(pz, input_len, 0U/*unlimited*/, flush);
affirm(pz->end != NULL && ps->stash == NULL);
ps->stash = *pz->end; /* May be NULL */
*pz->end = NULL;
/* Z_FINISH should give Z_STREAM_END, everything else should give Z_OK, in
* either case all the input should have been consumed:
*/
implies(ret == Z_OK || ret == Z_FINISH, pz->zs.avail_in == 0U &&
(ret == Z_STREAM_END) == (flush == Z_FINISH));
pz->zs.next_in = NULL;
pz->zs.avail_in = 0U; /* safety */
png_zlib_compress_validate(pz, 0/*in_use*/);
return ret;
}
}
/* Compress some image data using the main png_zlib_compress. Write the result
* out if there is sufficient data. png_start_IDAT must have been called.
*/
static void
png_compress_IDAT(png_structrp png_ptr, png_const_voidp input, uInt input_len,
int flush)
{
png_zlib_statep ps = png_ptr->zlib_state;
int ret = png_compress_IDAT_data(png_ptr, ps, &ps->s, input, input_len,
flush);
/* Check the return code. */
if (ret == Z_OK || ret == Z_STREAM_END)
png_write_IDAT(png_ptr, flush == Z_FINISH);
else /* ret != Z_OK && ret != Z_STREAM_END */
{
/* This is an error condition. It is fatal. */
png_end_IDAT(png_ptr);
png_zstream_error(&ps->s.zs, ret);
png_error(png_ptr, ps->s.zs.msg);
}
}
#ifdef PNG_WRITE_FLUSH_SUPPORTED
/* Set the automatic flush interval or 0 to turn flushing off */
void PNGAPI
png_set_flush(png_structrp png_ptr, int nrows)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
png_debug(1, "in png_set_flush");
if (ps != NULL)
{
if (nrows <= 0)
ps->flush_dist = 0xEFFFFFFFU;
else
ps->flush_dist = nrows;
}
}
/* Flush the current output buffers now */
void PNGAPI
png_write_flush(png_structrp png_ptr)
{
png_debug(1, "in png_write_flush");
/* Before the start of the IDAT and after the end of the image zowner will be
* something other than png_IDAT:
*/
if (png_ptr != NULL && png_ptr->zlib_state != NULL &&
png_ptr->zowner == png_IDAT)
png_ptr->zlib_state->flush_rows = 0xEFFFFFFF;
}
/* Return the correct flush to use */
static int
row_flush(png_zlib_statep ps, unsigned int row_info_flags)
{
if (PNG_IDAT_END(row_info_flags))
return Z_FINISH;
else if ((row_info_flags & png_row_end) != 0 &&
ps->flush_rows >= ps->flush_dist)
return Z_SYNC_FLUSH;
else
return Z_NO_FLUSH;
}
#else /* !WRITE_FLUSH */
# define row_flush(ps, ri) (PNG_IDAT_END(ri) ? Z_FINISH : Z_NO_FLUSH)
#endif /* !WRITE_FLUSH */
static void
write_filtered_row(png_structrp png_ptr, png_const_voidp filtered_row,
unsigned int row_bytes, unsigned int filter /*if at start of row*/,
int flush)
{
/* This handles writing a row that has been filtered, or did not need to be
* filtered. If the data row has a partial pixel it must have been handled
* correctly in the caller; filters generate a full 8 bits even if the pixel
* only has one significant bit!
*/
debug(row_bytes > 0);
affirm(row_bytes <= ZLIB_IO_MAX); /* I.e. it fits in a uInt */
if (filter < PNG_FILTER_VALUE_LAST) /* start of row */
{
png_byte buffer[1];
buffer[0] = PNG_BYTE(filter);
png_compress_IDAT(png_ptr, buffer, 1U/*len*/, Z_NO_FLUSH);
}
png_compress_IDAT(png_ptr, filtered_row, row_bytes, flush);
}
static void
write_unfiltered_rowbits(png_structrp png_ptr, png_const_bytep filtered_row,
unsigned int row_bits, png_byte filter /*if at start of row*/,
int flush)
{
/* Same as above, but it correctly clears the unused bits in a partial
* byte.
*/
const png_uint_32 row_bytes = row_bits >> 3;
debug(filter == PNG_FILTER_VALUE_NONE || filter == PNG_FILTER_VALUE_LAST);
if (row_bytes > 0U)
{
row_bits -= row_bytes << 3;
write_filtered_row(png_ptr, filtered_row, row_bytes, filter,
row_bits == 0U ? flush : Z_NO_FLUSH);
filter = PNG_FILTER_VALUE_LAST; /* written */
}
/* Handle a partial byte. */
if (row_bits > 0U)
{
png_byte buffer[1];
buffer[0] = PNG_BYTE(filtered_row[row_bytes] & ~(0xFFU >> row_bits));
write_filtered_row(png_ptr, buffer, 1U, filter, flush);
}
}
#ifdef PNG_WRITE_FILTER_SUPPORTED
static void
filter_block_singlebyte(unsigned int row_bytes, png_bytep sub_row,
png_bytep up_row, png_bytep avg_row, png_bytep paeth_row,
png_const_bytep row, png_const_bytep prev_row, png_bytep prev_pixels)
{
/* Calculate rows for all four filters where the input has one byte per pixel
* (more accurately per filter-unit).
*/
png_byte a = prev_pixels[0];
png_byte c = prev_pixels[1];
while (row_bytes-- > 0U)
{
const png_byte x = *row++;
const png_byte b = prev_row == NULL ? 0U : *prev_row++;
/* Calculate each filtered byte in turn: */
if (sub_row != NULL) *sub_row++ = 0xFFU & (x - a);
if (up_row != NULL) *up_row++ = 0xFFU & (x - b);
if (avg_row != NULL) *avg_row++ = 0xFFU & (x - (a+b)/2U);
/* Paeth is a little more difficult: */
if (paeth_row != NULL)
{
int pa = b-c; /* a+b-c - a */
int pb = a-c; /* a+b-c - b */
int pc = pa+pb; /* a+b-c - c = b-c + a-c */
png_byte p = a;
pa = abs(pa);
pb = abs(pb);
if (pa > pb) pa = pb, p = b;
if (pa > abs(pc)) p = c;
*paeth_row++ = 0xFFU & (x - p);
}
/* And set a and c for the next pixel: */
a = x;
c = b;
}
/* Store a and c for the next block: */
prev_pixels[0] = a;
prev_pixels[1] = c;
}
static void
filter_block_multibyte(unsigned int row_bytes,
const unsigned int bpp, png_bytep sub_row, png_bytep up_row,
png_bytep avg_row, png_bytep paeth_row, png_const_bytep row,
png_const_bytep prev_row, png_bytep prev_pixels)
{
/* Calculate rows for all four filters, the input is a block of bytes such
* that row_bytes is a multiple of bpp. bpp can be 2, 3, 4, 6 or 8.
* prev_pixels will be updated to the last pixels processed.
*/
while (row_bytes >= bpp)
{
unsigned int i;
for (i=0; i<bpp; ++i)
{
const png_byte a = prev_pixels[i];
const png_byte c = prev_pixels[i+bpp];
const png_byte b = prev_row == NULL ? 0U : *prev_row++;
const png_byte x = *row++;
/* Save for the next pixel: */
prev_pixels[i] = x;
prev_pixels[i+bpp] = b;
/* Calculate each filtered byte in turn: */
if (sub_row != NULL) *sub_row++ = 0xFFU & (x - a);
if (up_row != NULL) *up_row++ = 0xFFU & (x - b);
if (avg_row != NULL) *avg_row++ = 0xFFU & (x - (a+b)/2U);
/* Paeth is a little more difficult: */
if (paeth_row != NULL)
{
int pa = b-c; /* a+b-c - a */
int pb = a-c; /* a+b-c - b */
int pc = pa+pb; /* a+b-c - c = b-c + a-c */
png_byte p = a;
pa = abs(pa);
pb = abs(pb);
if (pa > pb) pa = pb, p = b;
if (pa > abs(pc)) p = c;
*paeth_row++ = 0xFFU & (x - p);
}
}
row_bytes -= i;
}
}
static void
filter_block(png_const_bytep prev_row, png_bytep prev_pixels,
png_const_bytep unfiltered_row, unsigned int row_bits,
const unsigned int bpp, png_bytep sub_row, png_bytep up_row,
png_bytep avg_row, png_bytep paeth_row)
{
const unsigned int row_bytes = row_bits >> 3; /* complete bytes */
if (bpp <= 8U)
{
/* There may be a partial byte at the end. */
if (row_bytes > 0)
filter_block_singlebyte(row_bytes, sub_row, up_row, avg_row, paeth_row,
unfiltered_row, prev_row, prev_pixels);
/* The partial byte must be handled correctly here; both the previous row
* value and the current value need to have non-present bits cleared.
*/
if ((row_bits & 7U) != 0)
{
const png_byte mask = PNG_BYTE(~(0xFFU >> (row_bits & 7U)));
png_byte buffer[2];
buffer[0] = unfiltered_row[row_bytes] & mask;
if (prev_row != NULL)
buffer[1U] = prev_row[row_bytes] & mask;
else
buffer[1U] = 0U;
filter_block_singlebyte(1U,
sub_row == NULL ? NULL : sub_row+row_bytes,
up_row == NULL ? NULL : up_row+row_bytes,
avg_row == NULL ? NULL : avg_row+row_bytes,
paeth_row == NULL ? NULL : paeth_row+row_bytes,
buffer, buffer+1U, prev_pixels);
}
}
else
filter_block_multibyte(row_bytes, bpp >> 3,
sub_row, up_row, avg_row, paeth_row,
unfiltered_row, prev_row, prev_pixels);
}
static void
filter_row(png_structrp png_ptr, png_const_bytep prev_row,
png_bytep prev_pixels, png_const_bytep unfiltered_row,
unsigned int row_bits, unsigned int bpp, unsigned int filter,
int start_of_row, int flush)
{
/* filters_to_try identifies a single filter and it is not PNG_FILTER_NONE.
*/
png_byte filtered_row[PNG_ROW_BUFFER_SIZE];
affirm((row_bits+7U) >> 3 <= PNG_ROW_BUFFER_SIZE &&
filter >= PNG_FILTER_VALUE_SUB && filter <= PNG_FILTER_VALUE_PAETH);
debug((row_bits % bpp) == 0U);
filter_block(prev_row, prev_pixels, unfiltered_row, row_bits, bpp,
filter == PNG_FILTER_VALUE_SUB ? filtered_row : NULL,
filter == PNG_FILTER_VALUE_UP ? filtered_row : NULL,
filter == PNG_FILTER_VALUE_AVG ? filtered_row : NULL,
filter == PNG_FILTER_VALUE_PAETH ? filtered_row : NULL);
write_filtered_row(png_ptr, filtered_row, (row_bits+7U)>>3,
start_of_row ? filter : PNG_FILTER_VALUE_LAST, flush);
}
#ifdef PNG_SELECT_FILTER_HEURISTICALLY_SUPPORTED
static png_byte
select_filter_heuristically(png_structrp png_ptr, unsigned int filters_to_try,
png_const_bytep prev_row, png_bytep prev_pixels,
png_const_bytep unfiltered_row, unsigned int row_bits, unsigned int bpp,
int flush)
{
const unsigned int row_bytes = (row_bits+7U) >> 3;
png_byte test_buffers[4][PNG_ROW_BUFFER_SIZE]; /* for each filter */
affirm(row_bytes <= PNG_ROW_BUFFER_SIZE);
debug((row_bits % bpp) == 0U);
filter_block(prev_row, prev_pixels, unfiltered_row, row_bits, bpp,
test_buffers[PNG_FILTER_VALUE_SUB-1U],
test_buffers[PNG_FILTER_VALUE_UP-1U],
test_buffers[PNG_FILTER_VALUE_AVG-1U],
test_buffers[PNG_FILTER_VALUE_PAETH-1U]);
/* Now check each buffer and the original row to see which is best; this is
* the heuristic. The test is on the number of separate code values in the
* buffer. Since the buffer is either the full row or PNG_ROW_BUFFER_SIZE
* bytes (or slightly less for RGB) we either find the true number of codes
* generated or we expect a count of average 8 per code.
*/
{
unsigned int filter_max = 257U;
png_byte best_filter, test_filter;
png_const_bytep best_row, test_row;
for (best_filter = test_filter = PNG_FILTER_VALUE_NONE,
best_row = test_row = unfiltered_row;
test_filter < PNG_FILTER_VALUE_LAST;
test_row = test_buffers[test_filter], ++test_filter)
if ((filters_to_try & PNG_FILTER_MASK(test_filter)) != 0U)
{
unsigned int count = 1U, x;
png_byte code[256];
memset(code, 0, sizeof code);
code[test_filter] = 1U;
for (x=0U; x < row_bytes; ++x)
{
const png_byte b = test_row[x];
if (code[b] == 0) code[b] = 1U, ++count;
}
if (count < filter_max)
filter_max = count, best_filter = test_filter, best_row = test_row;
}
/* Calling write_unfiltered_rowbits is necessary here to deal with the
* clearly of a partial byte at the end.
*/
if (best_filter == PNG_FILTER_VALUE_NONE)
write_unfiltered_rowbits(png_ptr, unfiltered_row, row_bits,
PNG_FILTER_VALUE_NONE, flush);
else
write_filtered_row(png_ptr, best_row, row_bytes, best_filter,
flush);
return best_filter;
}
}
#endif /* SELECT_FILTER_HEURISTICALLY */
#ifdef PNG_SELECT_FILTER_METHODICALLY_SUPPORTED
/* With the 'methodical' method multiple png_zlib_compress structures exist,
* these functions handle the creation and destruction ('release') of these
* structures. Note that the structures have not been initialized with the
* opaque and alloc functions; this is done on demand and the 'opaque' pointer
* is set to NULL if the compress structure is not in use.
*/
static void
png_zlib_filter_release(png_structrp png_ptr, png_zlib_statep ps, png_byte i)
{
/* Make sure this filter really is in use: */
if (ps->filter[i].zs.opaque != NULL) /* else not initialized */
{
/* First put the buffer list back into the cache, when this function is
* called the list should be correctly terminated at *end.
*/
{
png_compression_bufferp list = ps->filter[i].list;
if (list != NULL)
{
ps->filter[i].list = NULL;
/* Return the list to the stash. */
affirm(ps->filter[i].end != NULL);
/* In the normal case 'end' is the end of this list and it is
* pre-pended to the cache. In the error case (png_error during a
* deflate operation) the list will be the entire stash and the
* stash will be NULL.
*
* If both pointers are non-NULL clean up by making the 'end'
* pointer NULL (freeing anything it points to). This is
* unexpected.
*/
if (ps->stash != NULL)
{
debug(*ps->filter[i].end == NULL);
/* Clean up on error: */
png_free_compression_buffer(png_ptr, ps->filter[i].end);
*ps->filter[i].end = ps->stash;
}
ps->stash = list;
}
ps->filter[i].end = &ps->filter[i].list; /* safety */
}
/* Now use the standard 'destroy' function to handle the z_stream; the
* list has already been made NULL above. If the structure is sharing
* state with the main compress structure do not free it!
*/
if (ps->filter[i].zs.state != ps->s.zs.state)
png_zlib_compress_destroy(&ps->filter[i], 0/*check*/);
/* Then this indicates that the structure is not in use: */
ps->filter[i].zs.opaque = NULL;
}
else
debug(ps->filter[i].list == NULL);
}
static int /* success */
png_zlib_filter_compress(png_structrp png_ptr, png_zlib_statep ps, png_byte i,
png_const_voidp input, uInt input_len, int flush)
{
png_zlib_compressp pz = &ps->filter[i];
int ret = png_compress_IDAT_data(png_ptr, ps, pz, input, input_len, flush);
if (ret == Z_OK || ret == Z_STREAM_END)
return 1; /* success */
else
{
/* If ret is not Z_OK then this stream gets aborted, this is recoverable
* so long as this is not the only stream left. There are only two likely
* causes of failure; an internal libpng bug or out-of-memory. Given an
* assumption of infalibility this means that the app is out of memory and
* it makes sense to release as much as possible. Note that it is
* conceivable that OOM may cause an error other than Z_MEM_ERROR, though
* this is unlikely.
*/
png_zstream_error(&pz->zs, ret);
png_warning(png_ptr, pz->zs.msg);
png_zlib_filter_release(png_ptr, ps, i);
return 0; /* failure */
}
}
static int /* success */
png_zlib_filter_init(png_structrp png_ptr, png_zlib_statep ps, png_byte i,
int copy)
{
png_zlib_compressp pz = &ps->filter[i];
/* Make sure that we don't overwrite previously allocated stuff: */
debug(pz->zs.opaque == NULL && pz->list == NULL);
/* Initialize the list and count fields: */
pz->end = &pz->list;
pz->len = 0U;
pz->overflow = 0U;
pz->start = 0U;
/* If 'copy' is true a complete copy is made of the main z_stream, otherwise
* the stream is shared. deflateCopy actually does a memcpy over the
* destination z_stream, so no further initialization is required.
*/
if (copy)
{
int ret = deflateCopy(&pz->zs, &ps->s.zs);
if (ret != Z_OK)
{
/* If this fails and png_chunk_report returns we can continue because
* the caller handles the error:
*/
pz->zs.opaque = NULL;
png_zstream_error(&pz->zs, ret);
png_chunk_report(png_ptr, pz->zs.msg, PNG_CHUNK_WRITE_ERROR);
return 0;
}
}
else
pz->zs = ps->s.zs; /* see png_zlib_filter_release */
/* Either way the {next,avail}_{in.out} fields got copied, however they must
* not be used so:
*/
ps->filter[i].zs.next_in = ps->filter[i].zs.next_out = NULL;
ps->filter[i].zs.avail_in = ps->filter[i].zs.avail_out = 0U;
ps->filter[i].zs.msg = PNGZ_MSG_CAST("zlib copy ok"); /* safety */
/* If there is a partial buffer in the main stream a partial buffer is
* required here:
*/
{
uInt start = ps->s.zs.avail_out;
if (start > 0U && start < sizeof ps->s.list->output)
{
uInt avail_out;
start = (uInt)/*SAFE*/(sizeof ps->s.list->output) - start;
pz->list = ps->stash;
ps->stash = NULL;
avail_out = png_zlib_compress_avail_out(pz);
ps->stash = *pz->end;
*pz->end = NULL;
if (avail_out >= start)
{
pz->zs.next_out += start;
pz->zs.avail_out -= start;
pz->start = start;
}
else /* OOM */
{
png_warning(png_ptr, "filter selection: out of memory");
png_zlib_filter_release(png_ptr, ps, i);
return 0; /* failure */
}
}
}
/* Finally compress the filter byte into the copied/shared z_stream. */
{
png_byte b[1];
b[0] = i;
return png_zlib_filter_compress(png_ptr, ps, i, b, 1U, Z_NO_FLUSH);
}
}
/* Revert to using the main z_stream. This just moves the given filter (which
* must have been initialized) back to the main stream leaving the filter ready
* to be released.
*/
static void
png_zlib_filter_revert(png_structrp png_ptr, png_zlib_statep ps, png_byte i)
{
png_zlib_compressp pz = &ps->filter[i];
affirm(pz->zs.opaque != NULL);
png_zlib_compress_validate(pz, 0/*in_use*/);
/* First merge the buffer lists. */
if (pz->overflow > 0U || pz->len > 0U)
{
affirm(pz->list != NULL);
debug(ps->s.end != NULL && *ps->s.end == NULL);
/* The deflate operation produced some output, if pz->start is non-zero
* the first buffer in pz->list must be merged with the current buffer in
* the main z_stream, if pz->zs.next_out still points into this buffer the
* pointer must be updated to point to the old buffer.
*/
if (ps->s.zs.avail_out > 0U)
{
affirm(ps->s.zs.avail_out + pz->start == sizeof ps->s.list->output);
/* Copy everything after pz->start into the old buffer. */
memcpy(ps->s.zs.next_out, pz->list->output + pz->start,
ps->s.zs.avail_out);
/* Unlink the remainder of the list, if any, and append it to the
* output.
*/
if (pz->list->next != NULL)
{
debug(pz->end != &pz->list->next);
*ps->s.end = pz->list->next;
pz->list->next = NULL;
ps->s.end = pz->end;
pz->end = &pz->list->next; /* To be deleted later */
}
/* If pz->s.next_out still points into the first buffer (the case for
* the final row of small images) update it to point to the old buffer
* instead so that the copy below works.
*/
if (pz->zs.next_out >= pz->list->output &&
pz->zs.next_out <= pz->list->output + (sizeof pz->list->output))
{
debug(pz->overflow == 0U &&
pz->len + pz->start <= (sizeof pz->list->output) &&
pz->zs.next_out + pz->zs.avail_out ==
pz->list->output + (sizeof pz->list->output) &&
ps->s.zs.avail_out > pz->zs.avail_out);
pz->zs.next_out = ps->s.zs.next_out + ps->s.zs.avail_out -
pz->zs.avail_out;
}
}
else
{
affirm(pz->start == 0U);
/* Nothing to copy, the whole new list is appended to the existing one.
*/
*ps->s.end = pz->list;
pz->list = NULL;
ps->s.end = pz->end;
pz->end = &pz->list;
}
/* Update the length fields; 'start' remains correct. */
ps->s.overflow += pz->overflow;
if (((ps->s.len += pz->len) & 0x80000000U) != 0)
++ps->s.overflow, ps->s.len &= 0x7FFFFFFFU;
}
else
{
/* deflate produced no additional output; all the state is in the
* z_stream. Copy it back without changing anything else.
*/
debug(pz->zs.avail_out == ps->s.zs.avail_out);
pz->zs.next_out = ps->s.zs.next_out;
}
/* The buffer list has been fixed, the z_stream must be copied. All fields
* are relevant. This is done as a simple swap.
*/
{
z_stream zs = ps->s.zs;
ps->s.zs = pz->zs;
png_zlib_compress_validate(&ps->s, 0/*in_use*/);
zs.next_in = zs.next_out = NULL;
zs.avail_in = zs.avail_out = 0U;
zs.msg = PNGZ_MSG_CAST("invalid");
pz->zs = zs;
}
}
/* As above but release all the filters as well. */
static void
png_zlib_filter_revert_and_release(png_structrp png_ptr, png_zlib_statep ps,
png_byte i)
{
/* The other filters must be released first to correctly handle the
* non-copied one:
*/
png_byte f;
for (f=0U; f < PNG_FILTER_VALUE_LAST; ++f)
if (f != i)
png_zlib_filter_release(png_ptr, ps, f);
png_zlib_filter_revert(png_ptr, ps, i);
png_zlib_filter_release(png_ptr, ps, i);
}
static png_byte /* filters being tried */
select_filter_methodically_init(png_structrp png_ptr,
const unsigned int filters_to_try)
{
png_zlib_statep ps = png_ptr->zlib_state;
affirm(ps != NULL);
/* Now activate the decompressor for each filter in the list. Skip the first
* filter; this will share the main state.
*/
{
unsigned int filters = 0U;
png_byte filter, first_filter = PNG_FILTER_VALUE_LAST;
for (filter=0U; filter < PNG_FILTER_VALUE_LAST; ++filter)
if ((filters_to_try & PNG_FILTER_MASK(filter)) != 0U)
{
if (first_filter == PNG_FILTER_VALUE_LAST)
first_filter = filter;
else if (png_zlib_filter_init(png_ptr, ps, filter, 1/*copy*/))
filters |= PNG_FILTER_MASK(filter);
else /* OOM, probably; give up */
{
ps->filter_oom = 1U;
break;
}
}
/* If none of that worked abort the filter selection by returning just the
* first filter. Note that a filter value is returned here.
*/
if (filters == 0U)
return first_filter;
/* Finally initialize the first filter. */
if (png_zlib_filter_init(png_ptr, ps, first_filter, 0/*!copy*/))
return PNG_ALL_FILTERS & (filters | PNG_FILTER_MASK(first_filter));
/* This is an error condition but there is still a working z_stream
* structure. The z_stream has had the filter byte written to it, so teh
* standard code cannot be used. Simply fake the multi-filter case. The
* low three bits ensure that there are multiple bits in the result.
*/
ps->filter_oom = 1U;
return PNG_ALL_FILTERS & (filters | 0x7U);
}
}
static int
select_filter_methodically_better(png_structrp png_ptr, png_zlib_compressp pz,
png_uint_32p op/*high 32 bits*/, png_uint_32p lp/*low 31 bits*/,
Bytef *scratch_out, uInt avail_out, int flush)
/* Called at the end of a row for each filter being tested to work out if
* this filter is apparently producing better results than {*op,*lp}, which
* is preset to a number larger than any possible 63-bit value and then set,
* here, as required to {overflow,len} from a selected filter.
*/
{
/* The pre-check here is that the data already produced by the compression
* engine does not exceed the best count found so far:
*/
png_uint_32 o = pz->overflow, l = pz->len;
png_zlib_compress_validate(pz, 0/*in_use*/);
if (o < *op || (o == *op && l < *lp))
{
/* But if the stream hasn't been flushed this proves nothing; test the
* pending output by using an appropriate flush:
*/
if (flush == Z_NO_FLUSH)
{
int ret;
z_stream zs;
ret = deflateCopy(&zs, &pz->zs);
if (ret == Z_OK)
{
zs.next_in = NULL;
zs.avail_in = 0U;
/* Extract all the output from zlib by doing dummy deflates. Note
* that all the flush possibilites give approximately the same
* result but PARTIAL, SYNC and FULL seem to be mildly better
* probably because they avoid the rounding and block overhead.
*
* Z_PARTIAL_FLUSH 1
* Z_SYNC_FLUSH 2
* Z_FULL_FLUSH 3
* Z_FINISH 4
* Z_BLOCK 5
*/
flush = Z_PARTIAL_FLUSH;
do
{
if (l & 0x80000000U)
++o, l &= 0x7FFFFFFFU;
zs.next_out = scratch_out;
zs.avail_out = avail_out;
l += avail_out;
ret = deflate(&zs, flush);
} while (ret == Z_OK && zs.avail_out == 0U);
#if 0
/* TODO: fix this (Coverity issue Z_STREAM_END is dead code) */
if (ret == (flush == Z_FINISH ? Z_STREAM_END : Z_OK))
#else
if (ret == Z_OK)
#endif /* 0 */
{
/* This cannot underflow because the check above is performed
* before adding 'avail_out' to l:
*/
l -= zs.avail_out;
(void)deflateEnd(&zs);
png_zlib_compress_validate(pz, 0/*in_use*/);
if (l & 0x80000000U)
++o, l &= 0x7FFFFFFFU;
if (o < *op || (o == *op && l < *lp))
{
*op = o;
*lp = l;
return 1;
}
/* No errors but the result was longer (this can't be the first
* filter.)
*/
return 0;
}
else /* problem in deflate */
(void)deflateEnd(&zs);
}
/* We arrive here if there was an error somewhere inside zlib. */
png_zstream_error(&zs, ret);
png_warning(png_ptr, zs.msg);
}
else /* flush already performed */
{
*op = o;
*lp = l;
return 1;
}
}
/* This is the failure case, however if this is the first filter to be tested
* return success anyway, without resetting {op,lp}:
*/
return *op == 0xFFFFFFFFU && *lp == 0xFFFFFFFFU;
}
static void
select_filter_methodically(png_structrp png_ptr, png_const_bytep prev_row,
png_bytep prev_pixels, png_const_bytep unfiltered_row,
unsigned int row_bits, unsigned int bpp, unsigned int filters_to_try,
int end_of_row, int flush)
{
png_zlib_statep ps = png_ptr->zlib_state;
const unsigned int row_bytes = (row_bits+7U) >> 3;
png_byte test_buffers[4][PNG_ROW_BUFFER_SIZE]; /* for each filter */
affirm(row_bytes <= PNG_ROW_BUFFER_SIZE && ps != NULL);
debug((row_bits % bpp) == 0U && filters_to_try > 0x7U);
filter_block(prev_row, prev_pixels, unfiltered_row, row_bits, bpp,
test_buffers[PNG_FILTER_VALUE_SUB-1U],
test_buffers[PNG_FILTER_VALUE_UP-1U],
test_buffers[PNG_FILTER_VALUE_AVG-1U],
test_buffers[PNG_FILTER_VALUE_PAETH-1U]);
/* Add each test buffer, and the unfiltered row if required, to the current
* list.
*/
{
png_byte filter, ok_filter = PNG_FILTER_VALUE_LAST;
for (filter=0U; filter < PNG_FILTER_VALUE_LAST; ++filter)
if ((filters_to_try & PNG_FILTER_MASK(filter)) != 0U)
{
if (png_zlib_filter_compress(png_ptr, ps, filter,
filter == PNG_FILTER_VALUE_NONE ?
unfiltered_row : test_buffers[filter-1], row_bytes, flush))
ok_filter = filter;
else /* remove this filter from the test list: */
filters_to_try &= PNG_BIC_MASK(PNG_FILTER_MASK(filter));
}
/* If nothing worked then there is no recovery possible. */
if (ok_filter == PNG_FILTER_VALUE_LAST)
png_error(png_ptr, "filter selection: everything failed");
/* At end_of_row choose the best filter; it is stored in ok_filter. */
if (end_of_row)
{
png_uint_32 o, l;
o = l = 0xFFFFFFFFU;
ok_filter = PNG_FILTER_VALUE_LAST;
for (filter=0U; filter < PNG_FILTER_VALUE_LAST; ++filter)
if ((filters_to_try & PNG_FILTER_MASK(filter)) != 0U &&
select_filter_methodically_better(png_ptr, &ps->filter[filter],
&o, &l, test_buffers[0], sizeof test_buffers, flush))
ok_filter = filter;
}
/* Keep going if there is more than one filter left, otherwise, if there
* is only one left (because of OOM killing filters) swap back to the
* main-line code using 'ok_filter'.
*/
else if ((filters_to_try & (filters_to_try-1U)) != 0U)
ok_filter = PNG_FILTER_VALUE_LAST; /* keep going */
/* Swap back to the mainline code at end of row or when the available
* filter count drops to one because of OOM.
*/
if (ok_filter < PNG_FILTER_VALUE_LAST)
{
png_zlib_filter_revert_and_release(png_ptr, ps, ok_filter);
png_write_IDAT(png_ptr, flush == Z_FINISH);
ps->filters = ok_filter;
}
else
{
ps->filters = PNG_ALL_FILTERS & (filters_to_try &= PNG_ALL_FILTERS);
debug((filters_to_try & (filters_to_try-1U)) != 0U);
}
}
}
#endif /* SELECT_FILTER_METHODICALLY */
/* This filters the row, chooses which filter to use, if it has not already
* been specified by the application, and then writes the row out with the
* chosen filter.
*/
void /* PRIVATE */
png_write_filter_row(png_structrp png_ptr, png_bytep prev_pixels,
png_const_bytep unfiltered_row, png_uint_32 x,
unsigned int width/*pixels*/, unsigned int row_info_flags)
{
png_zlib_statep ps;
png_bytep prev_row = png_ptr->row_buffer;
const unsigned int bpp = png_ptr->row_output_pixel_depth;
const unsigned int row_bits = width * bpp;
unsigned int filters_to_try;
int flush;
/* These invariants are expected from the caller: */
affirm(width < 65536U && bpp <= 64U && width < 65536U/bpp &&
row_bits <= 8U*PNG_ROW_BUFFER_SIZE);
/* Set up the IDAT zlib compression if not set up yet: */
if (png_ptr->zowner != png_IDAT)
png_start_IDAT(png_ptr);
ps = png_ptr->zlib_state;
affirm(ps != NULL);
flush = row_flush(ps, row_info_flags);
if (x == 0U) /* start of row */
{
/* Now work out the filters to try for this row: */
filters_to_try = ps->filter_mask;
/* If this has a previous row filter in the set to try ensure the row
* buffer exists and ensure it is empty when first allocated and at
* the start of the pass.
*/
if ((filters_to_try & (PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH))
!= 0U)
{
if (prev_row == NULL)
{
/* Just allocate for the total output row bytes; a three-row
* interlaced image requires less, but this is safe.
*/
prev_row = png_voidcast(png_bytep, png_malloc(png_ptr,
png_calc_rowbytes(png_ptr, bpp, png_ptr->width)));
png_ptr->row_buffer = prev_row;
/* If that buffer would have been required for this row issue an
* app warning and disable the filters that would have required
* the data.
*/
if (!(row_info_flags & png_pass_first_row))
{
png_app_warning(png_ptr, "Previous row filters ignored");
/* And always turn off the filters, to prevent using
* uninitialized data.
*/
filters_to_try &= PNG_BIC_MASK(
PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
if (filters_to_try == 0U)
filters_to_try = PNG_FILTER_NONE;
}
}
}
if ((row_info_flags & png_pass_first_row) != 0U)
{
/* On the first row UP and NONE are the same, PAETH and SUB are the
* same, so if both members of a pair occur together eliminate the one
* that depends on the previous row. This will avoid the filter
* selection code while allowing the app to ensure all the filters can
* be used (prev_row is allocated) on the first row.
*/
# define match(mask) (filters_to_try & (mask)) == mask
if (match(PNG_FILTER_NONE+PNG_FILTER_UP))
filters_to_try &= PNG_BIC_MASK(PNG_FILTER_UP);
if (match(PNG_FILTER_SUB+PNG_FILTER_PAETH))
filters_to_try &= PNG_BIC_MASK(PNG_FILTER_PAETH);
# undef match
}
/* If there is no selection algorithm enabled choose the first filter
* in the list, otherwise do algorithm-specific initialization.
*/
if ((filters_to_try & (filters_to_try-1U)) != 0U)
{
/* Multiple filters in the list. */
# ifdef PNG_SELECT_FILTER_METHODICALLY_SUPPORTED
if (!ps->filter_oom &&
(methodical_option == PNG_OPTION_ON ||
(methodical_option != PNG_OPTION_OFF &&
heuristic_option != PNG_OPTION_ON)))
filters_to_try =
select_filter_methodically_init(png_ptr, filters_to_try);
else /* don't do methodical selection */
# endif /* SELECT_FILTER_METHODICALLY */
# ifdef PNG_SELECT_FILTER_HEURISTICALLY_SUPPORTED
if (heuristic_option != PNG_OPTION_OFF) /* use heuristics */
{
/* The heuristic must select a single filter based on the first
* block of pixels; it updates zbuffer_filter to a single filter
* value.
*/
ps->filters = select_filter_heuristically(png_ptr,
filters_to_try,
(row_info_flags & png_pass_first_row) ? NULL : prev_row,
prev_pixels, unfiltered_row, row_bits, bpp, flush);
/* This has selected one filter and has already processed it but
* the current row must still be retained regardless if prev_row
* is non-NULL.
*/
goto copy_row;
}
else /* don't use heuristic selection */
# endif /* SELECT_FILTER_HEURISTICALLY */
filters_to_try &= -filters_to_try;
}
/* If there is just one bit set in filters_to_try convert it to the filter
* value and store that.
*/
if ((filters_to_try & (filters_to_try-1U)) == 0U) switch (filters_to_try)
{
case PNG_FILTER_NONE: filters_to_try = PNG_FILTER_VALUE_NONE; break;
case PNG_FILTER_SUB: filters_to_try = PNG_FILTER_VALUE_SUB; break;
case PNG_FILTER_UP: filters_to_try = PNG_FILTER_VALUE_UP; break;
case PNG_FILTER_AVG: filters_to_try = PNG_FILTER_VALUE_AVG; break;
case PNG_FILTER_PAETH: filters_to_try = PNG_FILTER_VALUE_PAETH; break;
default:
impossible("bad filter mask");
}
ps->filters = PNG_ALL_FILTERS & filters_to_try;
} /* start of row */
else
{
if (prev_row != NULL)
{
/* Advance prev_row to the corresponding pixel above row[x], must use
* png_calc_rowbytes here otherwise the calculation using x might
* overflow.
*/
debug(((x * bpp) & 7U) == 0U);
prev_row += png_calc_rowbytes(png_ptr, bpp, x);
}
filters_to_try = ps->filters;
}
/* Now choose the correct filter implementation according to the number of
* filters in the filters_to_try list. The prev_row parameter is made NULL
* on the first row because it is uninitialized at that point.
*/
if (filters_to_try == PNG_FILTER_VALUE_NONE)
write_unfiltered_rowbits(png_ptr, unfiltered_row, row_bits,
x == 0 ? PNG_FILTER_VALUE_NONE : PNG_FILTER_VALUE_LAST, flush);
else
{
png_const_bytep prev =
(row_info_flags & png_pass_first_row) ? NULL : prev_row;
/* Is just one bit set in 'filters_to_try'? */
if (filters_to_try < PNG_FILTER_VALUE_LAST)
filter_row(png_ptr, prev, prev_pixels, unfiltered_row, row_bits, bpp,
filters_to_try, x == 0, flush);
else
# ifdef PNG_SELECT_FILTER_METHODICALLY_SUPPORTED
select_filter_methodically(png_ptr, prev, prev_pixels,
unfiltered_row, row_bits, bpp, filters_to_try,
(row_info_flags & png_row_end) != 0U, flush);
# else
impossible("bad filter select logic");
# endif /* SELECT_FILTER_METHODICALLY */
}
# ifdef PNG_WRITE_FLUSH_SUPPORTED
if (flush == Z_SYNC_FLUSH)
{
png_flush(png_ptr);
ps->flush_rows = 0U;
}
# endif /* WRITE_FLUSH */
/* Copy the current row into the previous row buffer, if available, unless
* this is the last row in the pass, when there is no point. Note that
* prev_row may have garbage in a partial byte at the end.
*/
copy_row:
if (prev_row != NULL && !(row_info_flags & png_pass_last_row))
memcpy(prev_row, unfiltered_row, (row_bits + 7U) >> 3);
}
/* Allow the application to select one or more row filters to use. */
void PNGAPI
png_set_filter(png_structrp png_ptr, int method, int filtersIn)
{
unsigned int filters;
png_debug(1, "in png_set_filter");
if (png_ptr == NULL)
return;
if (method != png_ptr->filter_method)
{
png_app_error(png_ptr, "png_set_filter: method does not match IHDR");
return;
}
/* PNG and MNG use the same base adaptive filter types: */
if (method != PNG_FILTER_TYPE_BASE && method != PNG_INTRAPIXEL_DIFFERENCING)
{
png_app_error(png_ptr, "png_set_filter: unsupported method");
return;
}
/* Notice that PNG_NO_FILTERS is 0 and passes this test; this is OK
* because filters then gets set to PNG_FILTER_NONE, as is required.
*/
if (filtersIn >= 0 && filtersIn < PNG_FILTER_VALUE_LAST)
filters = 8U << filtersIn;
else if ((filtersIn & PNG_BIC_MASK(PNG_ALL_FILTERS)) == 0)
filters = filtersIn & PNG_ALL_FILTERS;
else
{
png_app_error(png_ptr, "png_set_filter: invalid filters mask/value");
/* Prior to 1.7.0 this ignored the error and just used the bits that
* are present, now it does nothing; this seems a lot safer.
*/
return;
}
debug(filters != 0U && (filters & PNG_BIC_MASK(PNG_ALL_FILTERS)) == 0U);
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
if (ps != NULL)
ps->filter_mask = png_check_bits(png_ptr, filters, 8);
else
png_app_error(png_ptr, "png_set_filter: invalid on read struct");
}
}
#else /* !WRITE_FILTER */
void /* PRIVATE */
png_write_filter_row(png_structrp png_ptr, png_bytep prev_pixels,
png_const_bytep unfiltered_row, png_uint_32 x,
unsigned int width/*pixels*/, unsigned int row_info_flags)
{
const unsigned int bpp = png_ptr->row_output_pixel_depth;
int flush;
png_uint_32 row_bits;
row_bits = width;
row_bits *= bpp;
/* These invariants are expected from the caller: */
affirm(width < 65536U && bpp <= 64U && width < 65536U/bpp &&
row_bits <= 8U*PNG_ROW_BUFFER_SIZE);
/* Set up the IDAT zlib compression if not set up yet: */
if (png_ptr->zowner != png_IDAT)
png_start_IDAT(png_ptr);
affirm(png_ptr->zlib_state != NULL);
flush = row_flush(png_ptr->zlib_state, row_info_flags);
write_unfiltered_rowbits(png_ptr, unfiltered_row, row_bits,
x == 0 ? PNG_FILTER_VALUE_NONE : PNG_FILTER_VALUE_LAST, flush);
# ifdef PNG_WRITE_FLUSH_SUPPORTED
if (flush == Z_SYNC_FLUSH)
{
png_flush(png_ptr);
png_ptr->zlib_state->flush_rows = 0U;
}
# endif /* WRITE_FLUSH */
PNG_UNUSED(prev_pixels);
}
#endif /* !WRITE_FILTER */
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* GRR 970116 */
/* Legacy API that weighted the filter metric by the number of times it had been
* used before.
*/
#ifdef PNG_FLOATING_POINT_SUPPORTED
PNG_FUNCTION(void,PNGAPI
png_set_filter_heuristics,(png_structrp png_ptr, int heuristic_method,
int num_weights, png_const_doublep filter_weights,
png_const_doublep filter_costs),PNG_DEPRECATED)
{
png_app_warning(png_ptr, "weighted filter heuristics not implemented");
PNG_UNUSED(heuristic_method)
PNG_UNUSED(num_weights)
PNG_UNUSED(filter_weights)
PNG_UNUSED(filter_costs)
}
#endif /* FLOATING_POINT */
#ifdef PNG_FIXED_POINT_SUPPORTED
PNG_FUNCTION(void,PNGAPI
png_set_filter_heuristics_fixed,(png_structrp png_ptr, int heuristic_method,
int num_weights, png_const_fixed_point_p filter_weights,
png_const_fixed_point_p filter_costs),PNG_DEPRECATED)
{
png_app_warning(png_ptr, "weighted filter heuristics not implemented");
PNG_UNUSED(heuristic_method)
PNG_UNUSED(num_weights)
PNG_UNUSED(filter_weights)
PNG_UNUSED(filter_costs)
}
#endif /* FIXED_POINT */
#endif /* WRITE_WEIGHTED_FILTER */
#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
void PNGAPI
png_set_compression_level(png_structrp png_ptr, int level)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
png_debug(1, "in png_set_compression_level");
if (ps != NULL)
ps->zlib_level = level;
}
void PNGAPI
png_set_compression_mem_level(png_structrp png_ptr, int mem_level)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
png_debug(1, "in png_set_compression_mem_level");
if (ps != NULL)
ps->zlib_mem_level = mem_level;
}
void PNGAPI
png_set_compression_strategy(png_structrp png_ptr, int strategy)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
png_debug(1, "in png_set_compression_strategy");
if (ps != NULL)
ps->zlib_strategy = strategy;
}
/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
* smaller value of window_bits if it can do so safely.
*/
void PNGAPI
png_set_compression_window_bits(png_structrp png_ptr, int window_bits)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
if (ps != NULL)
{
/* Prior to 1.6.0 this would warn but then set the window_bits value. This
* meant that negative window bits values could be selected that would
* cause libpng to write a non-standard PNG file with raw deflate or gzip
* compressed IDAT or ancillary chunks. Such files can be read and there
* is no warning on read, so this seems like a very bad idea.
*/
if (window_bits > 15)
{
png_app_warning(png_ptr,
"Only compression windows <= 32k supported by PNG");
window_bits = 15;
}
else if (window_bits < 8)
{
png_app_warning(png_ptr,
"Only compression windows >= 256 supported by PNG");
window_bits = 8;
}
ps->zlib_window_bits = window_bits;
}
}
void PNGAPI
png_set_compression_method(png_structrp png_ptr, int method)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
png_debug(1, "in png_set_compression_method");
if (ps != NULL)
{
/* This used to just warn, this seems unhelpful and might result in bogus
* PNG files if zlib starts accepting other methods.
*/
if (method == 8)
ps->zlib_method = method;
else
png_app_error(png_ptr,
"Only compression method 8 is supported by PNG");
}
}
#endif /* WRITE_CUSTOMIZE_COMPRESSION */
/* The following were added to libpng-1.5.4 */
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
void PNGAPI
png_set_text_compression_level(png_structrp png_ptr, int level)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
png_debug(1, "in png_set_text_compression_level");
if (ps != NULL)
ps->zlib_text_level = level;
}
void PNGAPI
png_set_text_compression_mem_level(png_structrp png_ptr, int mem_level)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
png_debug(1, "in png_set_text_compression_mem_level");
if (ps != NULL)
ps->zlib_text_mem_level = mem_level;
}
void PNGAPI
png_set_text_compression_strategy(png_structrp png_ptr, int strategy)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
png_debug(1, "in png_set_text_compression_strategy");
if (ps != NULL)
ps->zlib_text_strategy = strategy;
}
/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
* smaller value of window_bits if it can do so safely.
*/
void PNGAPI
png_set_text_compression_window_bits(png_structrp png_ptr, int window_bits)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
if (ps != NULL)
{
if (window_bits > 15)
{
png_app_warning(png_ptr,
"Only compression windows <= 32k supported by PNG");
window_bits = 15;
}
else if (window_bits < 8)
{
png_app_error(png_ptr,
"Only compression windows >= 256 supported by PNG");
window_bits = 8;
}
ps->zlib_text_window_bits = window_bits;
}
}
void PNGAPI
png_set_text_compression_method(png_structrp png_ptr, int method)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
png_debug(1, "in png_set_text_compression_method");
if (ps != NULL)
{
if (method == 8)
ps->zlib_text_method = method;
else
png_app_error(png_ptr,
"Only compression method 8 is supported by PNG");
}
}
#endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
/* end of API added to libpng-1.5.4 */
#endif /* WRITE */