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skia / third_party / libpng / v1.7.0beta71 / . / pngwutil.c
blob: 671a2f6b0d69c18e88c285d48a2485b9320543dc [file] [log] [blame]
/* pngwutil.c - utilities to write a PNG file
*
* Last changed in libpng 1.7.0 [(PENDING RELEASE)]
* Copyright (c) 1998-2015 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
#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;
}
/* 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;
#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_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(0/*TODO: fixme*/, z_cmf);
tmp = data[1] & 0xe0;
tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
data[1] = png_check_byte(0/*TODO: fixme*/, tmp);
}
}
}
}
#endif /* WRITE_OPTIMIZE_CMF */
/* Initialize the compressor for the appropriate type of compression. */
static int
png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
png_alloc_size_t data_size)
{
if (png_ptr->zowner != 0)
{
#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
char msg[64];
PNG_STRING_FROM_CHUNK(msg, owner);
msg[4] = ':';
msg[5] = ' ';
PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner);
/* So the message that results is "<chunk> using zstream"; this is an
* internal error, but is very useful for debugging. i18n requirements
* are minimal.
*/
(void)png_safecat(msg, (sizeof msg), 10, " using zstream");
#endif
#if PNG_RELEASE_BUILD
png_warning(png_ptr, msg);
/* Attempt sane error recovery */
if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */
{
png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT");
return Z_STREAM_ERROR;
}
png_ptr->zowner = 0;
#else
png_error(png_ptr, msg);
#endif
}
{
int level = png_ptr->zlib_level;
int method = png_ptr->zlib_method;
int windowBits = png_ptr->zlib_window_bits;
int memLevel = png_ptr->zlib_mem_level;
int strategy; /* set below */
int ret; /* zlib return code */
if (owner == png_IDAT)
{
#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0)
strategy = png_ptr->zlib_strategy;
else
#endif /* WRITE_CUSTOMIZE_COMPRESSION */
#ifdef PNG_WRITE_FILTER_SUPPORTED
if (png_ptr->filter_mask != PNG_FILTER_NONE)
strategy = PNG_Z_DEFAULT_STRATEGY;
else
#endif /* WRITE_FILTER */
/* The default with no filters: */
strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY;
}
else
{
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
level = png_ptr->zlib_text_level;
method = png_ptr->zlib_text_method;
windowBits = png_ptr->zlib_text_window_bits;
memLevel = png_ptr->zlib_text_mem_level;
strategy = png_ptr->zlib_text_strategy;
#else
/* 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
}
/* 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 <= 16384)
{
/* 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 + 262 <= half_window_size)
{
half_window_size >>= 1;
--windowBits;
}
}
/* Check against the previous initialized values, if any. */
if (png_ptr->zstream.state != NULL &&
(png_ptr->zlib_set_level != level ||
png_ptr->zlib_set_method != method ||
png_ptr->zlib_set_window_bits != windowBits ||
png_ptr->zlib_set_mem_level != memLevel ||
png_ptr->zlib_set_strategy != strategy))
{
/* This shadows 'ret' deliberately; we ignore failures in deflateEnd:
*/
int ret_end = deflateEnd(&png_ptr->zstream);
if (ret_end != Z_OK || png_ptr->zstream.state != NULL)
{
png_zstream_error(&png_ptr->zstream, ret_end);
png_warning(png_ptr, png_ptr->zstream.msg);
png_ptr->zstream.state = NULL; /* zlib error recovery */
}
}
/* For safety clear out the input and output pointers (currently zlib
* doesn't use them on Init, but it might in the future).
*/
png_ptr->zstream.next_in = NULL;
png_ptr->zstream.avail_in = 0;
png_ptr->zstream.next_out = NULL;
png_ptr->zstream.avail_out = 0;
/* Now initialize if required, setting the new parameters, otherwise just
* to a simple reset to the previous parameters.
*/
if (png_ptr->zstream.state != NULL)
ret = deflateReset(&png_ptr->zstream);
else
ret = deflateInit2(&png_ptr->zstream, 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 && png_ptr->zstream.state != NULL)
png_ptr->zowner = owner;
else
png_zstream_error(&png_ptr->zstream, ret);
return ret;
}
}
/* Clean up (or trim) a linked list of compression buffers. */
static void
png_free_buffer_list(png_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);
}
}
/* Release memory used by the deflate mechanism */
void /* PRIVATE */
png_deflate_destroy(png_structrp png_ptr)
{
/* Free any memory zlib uses */
if (png_ptr->zstream.state != NULL)
{
int ret = deflateEnd(&png_ptr->zstream);
if (ret != Z_OK)
{
png_zstream_error(&png_ptr->zstream, ret);
png_warning(png_ptr, png_ptr->zstream.msg);
}
}
/* Free our memory. png_free checks NULL for us. */
png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
}
/* Compress the given data given a compression buffer list. The passed in
* z_stream must have already been claimed (if required) and the compression
* buffer list pointer initialized to NULL or an existing list.
*
* The caller should use *data_len to work out how many buffers were used.
*
* 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 it is not possible to
* work out how much data was compressed.
*
* If *data_len exceeds PNG_UINT_MAX_31 after a successful deflate call the
* function will return Z_MEM_ERROR. To allow compressed streams longer than
* PNG_UINT_MAX_31 multiple calls can be made and *data_len can be reduced
* between each call (see the IDAT handling for an example of this).
*
* '*ep' is a pointer to the pointer to the next buffer to use:
*
* *ep ---> pointer ---> png_compression_buffer
*
* It is updated before return so that it points to the pointer to the next
* buffer after the one in use. I.e. it points to the 'next' member of the
* current buffer. (Since 'next' is the first element this actually means that
* it points at the current buffer.)
*
* The pointer 'pointer' will be updated if it is NULL, otherwise it is not
* changed. Typically 'pointer' is png_struct::zbuffer_list initially and is
* changed to the 'next' element of the last entry used. E.g:
*
* *ep(on entry) ............. (end) ........ *ep(on exit)
* | | |
* | | |
* V +----V-----+ +-----V----+ +----------+
* png_struct::zbuffer_list --> | next --+--> | next --+--> | next |
* | output[] | | output[] | | output[] |
* +----------+ +----------+ +----------+
* [in use] [unused]
*
* To start compression do this:
*
* png_compression_bufferp end = &png_ptr->buffer_list;
*
* And pass in &end.
*/
static int
png_compress(
png_const_structp png_ptr, /* Just for png_malloc_base! */
z_stream *zs, /* next_{in,out} valid, avail_in is the input
* data and avail_out is actually pass in the
* parameter input_len.
*/
png_compression_bufferp **ep, /* Points to the pointer to the next buffer to
* use. */
png_alloc_size_t input_len, /* Length of data to be compressed */
png_uint_32p data_len, /* Accumulated data size; the number of
* compressed bytes is added to this. */
int flush) /* Flush parameter at end of input */
{
png_compression_bufferp *end = *ep;
/* Sanity checking: */
affirm(end != NULL && zs->avail_in == 0 && zs->next_in != NULL);
debug(data_len != NULL && *data_len <= PNG_UINT_31_MAX);
implies(zs->next_out == NULL, zs->avail_out == 0);
for (;;)
{
/* OUTPUT: make sure some space is available: */
if (zs->avail_out == 0)
{
png_compression_bufferp next;
/* There may already be an unused compression buffer in the list: */
if (*end != NULL)
next = *end;
else
{
next = png_voidcast(png_compression_bufferp,
png_malloc_base(png_ptr, sizeof (png_compression_buffer)));
/* Check for OOM: this is a recoverable error for non-critical
* chunks, let the caller decide what to do:
*/
if (next == NULL)
{
*ep = end;
return Z_MEM_ERROR;
}
next->next = NULL; /* initialize the buffer */
*end = next;
}
end = &next->next;
zs->next_out = next->output; /* not initialized */
zs->avail_out = sizeof next->output;
}
/* 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;
zs->avail_in = avail_in;
}
*data_len += zs->avail_out; /* maximum that can be produced */
/* Compress the data */
{
int ret = deflate(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).
*/
input_len += zs->avail_in;
zs->avail_in = 0; /* safety */
/* Check for overflow of the data length limit. We can't get overflow
* here because zs->avail_out never exceeds PNG_ROW_BUFFER_SIZE, and
* that is under 16 bits.
*/
if ((*data_len -= zs->avail_out) > PNG_UINT_31_MAX)
{
zs->msg = "compressed data too long";
*ep = end;
return Z_MEM_ERROR;
}
/* Check the error code: */
switch (ret)
{
case Z_OK:
/* Check the reason for stopping: */
if (input_len == 0U && flush != Z_FINISH)
{
*ep = end;
return Z_OK;
}
affirm(zs->avail_out == 0U);
/* Allocate another buffer */
break;
case Z_STREAM_END:
affirm(input_len == 0U && flush == Z_FINISH);
*ep = end;
return Z_STREAM_END;
case Z_BUF_ERROR:
/* This means that we are doing a SYNC flush (not Z_NO_FLUSH and
* not Z_FINISH) and that more buffer space is needed to complete
* it.
*/
affirm(flush != Z_NO_FLUSH && flush != Z_FINISH &&
input_len == 0U && zs->avail_out == 0U);
/* Allocate another buffer */
break;
default:
/* An error */
*ep = end;
return ret;
}
}
}
}
#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 png_uint_32
png_compress_chunk_data(png_structp 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.
*/
{
int ret = png_deflate_claim(png_ptr, chunk_name, input_len);
/* This API is only ever used for non-critical chunks.
* PNG_CHUNK_WRITE_ERROR can be ignored by the app and, if it is, the
* write of the chunk will end up being skipped.
*/
if (ret != Z_OK)
{
png_chunk_report(png_ptr, png_ptr->zstream.msg, PNG_CHUNK_WRITE_ERROR);
return 0U;
}
}
/* The data compression function always returns so that we can clean up. */
png_ptr->zstream.next_in = PNGZ_INPUT_CAST(png_voidcast(const Bytef*,input));
{
png_uint_32 output_len = prefix_len;
png_compression_bufferp *end = &png_ptr->zbuffer_list; /* not required */
int ret = png_compress(png_ptr, &png_ptr->zstream, &end, input_len,
&output_len, Z_FINISH);
png_ptr->zstream.next_out = NULL; /* safety */
png_ptr->zstream.avail_out = 0;
png_ptr->zstream.next_in = NULL;
png_ptr->zstream.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 buffer list; the only expected error is Z_MEM_ERROR.
*/
if (ret != Z_STREAM_END)
{
png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
png_zstream_error(&png_ptr->zstream, ret);
png_chunk_report(png_ptr, png_ptr->zstream.msg, PNG_CHUNK_WRITE_ERROR);
return 0U;
}
/* png_compress is meant to guarantee this on a successful return: */
affirm(output_len > prefix_len && output_len <= PNG_UINT_31_MAX);
# ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
/* Fix up the deflate header, if required. */
optimize_cmf(png_ptr->zbuffer_list->output, input_len);
# endif
/* The returned result is just the length of the compressed data: */
return output_len - prefix_len;
}
}
/* 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_structp png_ptr, png_uint_32 output_len)
{
png_compression_bufferp next = png_ptr->zbuffer_list;
for (;;)
{
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 > 0);
if (size > output_len)
size = output_len;
png_write_chunk_data(png_ptr, next->output, size);
output_len -= size;
if (output_len == 0)
return;
next = next->next; /* always wanted to write that */
}
}
#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);
# ifdef PNG_WRITE_FILTER_SUPPORTED
/* TODO: review this setting */
if (png_ptr->filter_mask == PNG_NO_FILTERS /* not yet set */)
{
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
png_ptr->bit_depth < 8)
png_ptr->filter_mask = PNG_FILTER_NONE;
else
png_ptr->filter_mask = PNG_ALL_FILTERS;
}
# endif
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, output_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;
output_len = png_compress_chunk_data(png_ptr, png_iCCP, name_len,
profile, profile_len);
if (output_len > 0)
{
png_write_chunk_header(png_ptr, png_iCCP, name_len+output_len);
png_write_chunk_data(png_ptr, new_name, name_len);
png_write_compressed_chunk_data(png_ptr, output_len);
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)
{
png_uint_32 output_len;
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;
output_len = png_compress_chunk_data(png_ptr, png_zTXt, key_len,
text, strlen(text));
if (output_len > 0)
{
png_write_chunk_header(png_ptr, png_zTXt, key_len+output_len);
png_write_chunk_data(png_ptr, new_key, key_len);
png_write_compressed_chunk_data(png_ptr, output_len);
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)
{
data_len = png_compress_chunk_data(png_ptr, png_iTXt, prefix_len,
text, text_len);
if (data_len == 0)
return; /* chunk report already issued and ignored */
debug(data_len <= PNG_UINT_31_MAX-prefix_len);
}
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, data_len);
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
/* This is similar to png_text_compress, above, except that it does not require
* all of the data at once and, instead of buffering the compressed result,
* writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out
* because it calls the write interface. As a result it does its own error
* reporting and does not return an error code. In the event of error it will
* just call png_error. The input data length may exceed 32-bits. The 'flush'
* parameter is exactly the same as that to deflate, with the following
* meanings:
*
* Z_NO_FLUSH: normal incremental output of compressed data
* Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush
* Z_FINISH: this is the end of the input, do a Z_FINISH and clean up
*
* The routine manages the acquire and release of the png_ptr->zstream by
* checking and (at the end) clearing png_ptr->zowner; it does some sanity
* checks on the 'mode' flags while doing this.
*/
static void
png_start_IDAT(png_structrp png_ptr)
{
/* It is a terminal error if we can't claim the zstream. */
if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK)
png_error(png_ptr, png_ptr->zstream.msg);
/* The following state fields are, effectively, maintained by png_compress,
* except for zbuffer_start which is maintained directly by
* png_compress_IDAT.
*/
png_ptr->zbuffer_start = 0U;
png_ptr->zbuffer_len = 0U;
png_ptr->zbuffer_end = &png_ptr->zbuffer_list;
}
static void
png_write_IDAT(png_structrp png_ptr, int end_of_image)
{
png_compression_bufferp *listp = &png_ptr->zbuffer_list;
png_compression_bufferp list;
png_uint_32 output_len = png_ptr->zbuffer_len;
png_uint_32 start = png_ptr->zbuffer_start;
png_uint_32 size = png_ptr->IDAT_size;
const png_uint_32 min_size = (end_of_image ? 1U : size);
affirm(output_len >= min_size);
/* png_struct::zbuffer_end points to the pointer to the next (unused)
* compression buffer. We don't need those blocks to produce output so
* free them now to save space. This also ensures that *zbuffer_end is
* NULL so can be used to store the list head when wrapping the list.
*/
png_free_buffer_list(png_ptr, png_ptr->zbuffer_end);
/* Write at least one chunk, of size 'size', write chunks until
* 'output_len' is less than 'min_size'.
*/
list = *listp;
/* 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)
{
affirm(start == 0U);
optimize_cmf(list->output, png_image_size(png_ptr));
}
# endif /* WRITE_OPTIMIZE_CMF */
do /* write chunks */
{
/* 'size' is the size of the chunk to write, limited to IDAT_size:
*/
if (size > output_len) /* Z_FINISH */
size = output_len;
debug(size >= min_size);
png_write_chunk_header(png_ptr, png_IDAT, size);
do /* write the data of one chunk */
{
/* The chunk data may be split across multiple compression
* buffers. This loop moves 'list' down the available
* compression buffers.
*/
png_uint_32 avail = PNG_ROW_BUFFER_SIZE - start; /* in *list */
if (avail > output_len) /* valid bytes */
avail = output_len;
if (avail > size) /* bytes needed for chunk */
avail = size;
affirm(list != NULL && avail > 0U &&
start+avail <= PNG_ROW_BUFFER_SIZE);
png_write_chunk_data(png_ptr, list->output+start, avail);
output_len -= avail;
size -= avail;
start += avail;
if (start == PNG_ROW_BUFFER_SIZE)
{
/* End of the buffer. If all the compressed data has been
* consumed (output_len == 0) this will set list to NULL
* because of the png_free_buffer_list call above. At this
* point 'size' should be 0 too and the loop will terminate.
*/
start = 0U;
listp = &list->next;
list = *listp; /* May be NULL at the end */
}
} while (size > 0);
png_write_chunk_end(png_ptr);
size = png_ptr->IDAT_size; /* For the next chunk */
} while (output_len >= min_size);
png_ptr->mode |= PNG_HAVE_IDAT;
png_ptr->zbuffer_len = output_len;
if (output_len > 0U) /* Still got stuff to write */
{
affirm(!end_of_image && list != NULL);
/* If any compression buffers have been completely written move them
* to the end of the list so that they can be re-used and move
* 'list' to the head:
*/
if (listp != &png_ptr->zbuffer_list) /* list not at start */
{
debug(list != png_ptr->zbuffer_list /* obviously */ &&
listp != png_ptr->zbuffer_end /* because *end == NULL */);
*png_ptr->zbuffer_end = png_ptr->zbuffer_list;
*listp = NULL;
png_ptr->zbuffer_list = list;
}
/* 'list' is now at the start, so 'start' can be stored. */
png_ptr->zbuffer_start = start;
png_ptr->zbuffer_len = output_len;
}
else /* output_len == 0U; all compressed data has been written */
{
if (end_of_image)
{
png_ptr->zowner = 0U; /* release z_stream */
png_ptr->mode |= PNG_AFTER_IDAT;
}
/* Else: this is unlikely but possible; the compression code managed
* to exactly fill an IDAT chunk with the data for this block of row
* bytes so nothing is left in the buffer list. Simply reset the
* output pointers to the start of the list. This code is executed
* on Z_FINISH as well just to make the state safe.
*/
png_ptr->zstream.next_out = NULL;
png_ptr->zstream.avail_out = 0U;
png_ptr->zbuffer_start = 0U;
png_ptr->zbuffer_len = 0U;
png_ptr->zbuffer_end = &png_ptr->zbuffer_list;
} /* output_len == 0 */
}
typedef struct
{
png_compression_bufferp *zbuffer_end; /* 'next' field of current buffer */
png_uint_32 zbuffer_len; /* Length of data in list */
} png_IDAT_compression_state;
static int
png_compress_IDAT_test(png_structp png_ptr, z_stream *zstream,
png_compression_bufferp **ep, png_uint_32p output_lenp,
png_const_voidp input, uInt input_len, int flush)
{
png_uint_32 output_len = 0U;
int ret;
/* The stream must have been claimed: */
affirm(png_ptr->zowner == png_IDAT);
/* 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:
*/
zstream->next_in = PNGZ_INPUT_CAST(png_voidcast(const Bytef*, input));
ret = png_compress(png_ptr, zstream, ep, input_len, &output_len, flush);
implies(ret == Z_OK || ret == Z_FINISH, zstream->avail_in == 0U);
zstream->next_in = NULL;
zstream->avail_in = 0U; /* safety */
/* If IDAT_size is set to PNG_UINT_31_MAX the length will be larger, but
* not enough to overflow a png_uint_32.
*/
*output_lenp += output_len;
return ret;
}
static void
png_compress_IDAT(png_structp png_ptr, png_const_voidp input, uInt input_len,
int flush)
{
int ret = png_compress_IDAT_test(png_ptr, &png_ptr->zstream,
&png_ptr->zbuffer_end, &png_ptr->zbuffer_len, input, input_len, flush);
/* Check the return code. */
if (ret == Z_OK || ret == Z_STREAM_END)
{
/* Z_FINISH should give Z_STREAM_END, everything else should give Z_OK,
* so:
*/
debug((ret == Z_STREAM_END) == (flush == Z_FINISH));
/* At this point png_compress has produced (in total) zbuffer_start +
* zbuffer_len compressed bytes in a list of compression buffers starting
* with zbuffer_list and ending with the buffer containing *zbuffer_end,
* which may be NULL or may point to unused compression buffers.
*
* This code has already written out zbuffer_start bytes from the first
* buffer. Can we write more? If flush is Z_FINISH this is the end of
* the stream and there should be final bytes to write. Otherwise wait
* for IDAT_size bytes before writing a chunk. If nothing is to be
* written this function call is complete.
*/
if (flush == Z_FINISH || png_ptr->zbuffer_len >= png_ptr->IDAT_size)
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_zstream_error(&png_ptr->zstream, ret);
png_ptr->zowner = 0U;
png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
png_error(png_ptr, png_ptr->zstream.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_debug(1, "in png_set_flush");
if (png_ptr == NULL)
return;
png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
}
/* Flush the current output buffers now */
void PNGAPI
png_write_flush(png_structrp png_ptr)
{
png_debug(1, "in png_write_flush");
if (png_ptr == NULL)
return;
/* Before the start of the IDAT and after the end of the image zowner will be
* something other than png_IDAT:
*/
if (png_ptr->zowner == png_IDAT)
{
Byte b[1];
png_compress_IDAT(png_ptr, b, 0U, Z_SYNC_FLUSH);
png_ptr->flush_rows = 0;
png_flush(png_ptr);
}
}
#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 end_of_image)
{
/* 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,
end_of_image ? Z_FINISH : Z_NO_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 end_of_image)
{
/* 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,
end_of_image && row_bits == 0U);
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, end_of_image);
}
}
#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 end_of_image)
{
/* 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, end_of_image);
}
/* 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)
static void
select_filter_heuristically(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, int end_of_image)
{
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 filters_to_try = png_ptr->zbuffer_filters;
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;
}
/* Store the best filter found: */
png_ptr->zbuffer_filters = best_filter;
/* 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, end_of_image);
else
write_filtered_row(png_ptr, best_row, row_bytes, best_filter,
end_of_image);
}
}
#else /* !SELECT_FILTER_HEURISTICALLY */
# define heuristic_option PNG_OPTION_OFF
#endif /* !SELECT_FILTER_HEURISTICALLY */
#ifdef PNG_SELECT_FILTER_METHODICALLY_SUPPORTED
static void
select_filters_methodically_init(png_structrp png_ptr)
{
affirm(png_ptr->zbuffer_select == NULL);
}
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, int end_of_row, int end_of_image)
{
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]);
write_unfiltered_rowbits(png_ptr, unfiltered_row, row_bits,
PNG_FILTER_VALUE_LAST, end_of_image);
PNG_UNUSED(end_of_row)
}
#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_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;
/* 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);
if (x == 0U) /* start of row */
{
/* Delaying initialization of the filter stuff. */
if (png_ptr->filter_mask == 0U)
png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
(methodical_option != PNG_OPTION_OFF ||
heuristic_option != PNG_OPTION_OFF) ?
PNG_ALL_FILTERS : PNG_NO_FILTERS);
/* Now work out the filters to try for this row: */
filters_to_try = png_ptr->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.
*/
# ifdef PNG_SELECT_FILTER_METHODICALLY_SUPPORTED
if (methodical_option == PNG_OPTION_ON ||
(methodical_option != PNG_OPTION_OFF &&
heuristic_option != PNG_OPTION_ON))
select_filters_methodically_init(png_ptr);
else /* don't do methodical selection */
# endif /* SELECT_FILTER_METHODICALLY */
# ifdef PNG_SELECT_FILTER_HEURISTICALLY_SUPPORTED
if (heuristic_option == PNG_OPTION_OFF) /* don't use heuristics */
# 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");
}
png_ptr->zbuffer_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 = png_ptr->zbuffer_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,
PNG_IDAT_END(row_info_flags));
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_MASK(0))
filter_row(png_ptr, prev, prev_pixels, unfiltered_row, row_bits, bpp,
filters_to_try, x == 0, PNG_IDAT_END(row_info_flags));
# ifdef PNG_SELECT_FILTER_METHODICALLY_SUPPORTED
else if (png_ptr->zbuffer_select != NULL)
select_filter_methodically(png_ptr, prev, prev_pixels,
unfiltered_row, row_bits, bpp,
(row_info_flags & png_row_end) != 0U,
PNG_IDAT_END(row_info_flags));
# endif /* SELECT_FILTER_METHODICALLY */
# ifdef PNG_SELECT_FILTER_HEURISTICALLY_SUPPORTED
/* The heuristic must select a single filter based on the first block
* of pixels; it updates zbuffer_filter to a single filter value.
*/
else
select_filter_heuristically(png_ptr, prev, prev_pixels,
unfiltered_row, row_bits, bpp, PNG_IDAT_END(row_info_flags));
# else /* !SELECT_FILTER_HEURISTICALLY */
else
impossible("bad filter select logic");
# endif /* !SELECT_FILTER_HEURISTICALLY */
}
/* 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.
*/
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 (png_ptr->read_struct)
{
png_app_error(png_ptr, "png_set_filter: cannot be used when reading");
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_ptr->filter_mask = png_check_bits(png_ptr, filters, 8);
}
#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;
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);
write_unfiltered_rowbits(png_ptr, unfiltered_row, row_bits,
x == 0 ? PNG_FILTER_VALUE_NONE : PNG_FILTER_VALUE_LAST,
PNG_IDAT_END(row_info_flags));
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_debug(1, "in png_set_compression_level");
if (png_ptr == NULL)
return;
png_ptr->zlib_level = level;
}
void PNGAPI
png_set_compression_mem_level(png_structrp png_ptr, int mem_level)
{
png_debug(1, "in png_set_compression_mem_level");
if (png_ptr == NULL)
return;
png_ptr->zlib_mem_level = mem_level;
}
void PNGAPI
png_set_compression_strategy(png_structrp png_ptr, int strategy)
{
png_debug(1, "in png_set_compression_strategy");
if (png_ptr == NULL)
return;
/* The flag setting here prevents the libpng dynamic selection of strategy.
*/
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
png_ptr->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)
{
if (png_ptr == NULL)
return;
/* 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_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
window_bits = 15;
}
else if (window_bits < 8)
{
png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
window_bits = 8;
}
png_ptr->zlib_window_bits = window_bits;
}
void PNGAPI
png_set_compression_method(png_structrp png_ptr, int method)
{
png_debug(1, "in png_set_compression_method");
if (png_ptr == NULL)
return;
/* This would produce an invalid PNG file if it worked, but it doesn't and
* deflate will fault it, so it is harmless to just warn here.
*/
if (method != 8)
png_warning(png_ptr, "Only compression method 8 is supported by PNG");
png_ptr->zlib_method = method;
}
#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_debug(1, "in png_set_text_compression_level");
if (png_ptr == NULL)
return;
png_ptr->zlib_text_level = level;
}
void PNGAPI
png_set_text_compression_mem_level(png_structrp png_ptr, int mem_level)
{
png_debug(1, "in png_set_text_compression_mem_level");
if (png_ptr == NULL)
return;
png_ptr->zlib_text_mem_level = mem_level;
}
void PNGAPI
png_set_text_compression_strategy(png_structrp png_ptr, int strategy)
{
png_debug(1, "in png_set_text_compression_strategy");
if (png_ptr == NULL)
return;
png_ptr->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)
{
if (png_ptr == NULL)
return;
if (window_bits > 15)
{
png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
window_bits = 15;
}
else if (window_bits < 8)
{
png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
window_bits = 8;
}
png_ptr->zlib_text_window_bits = window_bits;
}
void PNGAPI
png_set_text_compression_method(png_structrp png_ptr, int method)
{
png_debug(1, "in png_set_text_compression_method");
if (png_ptr == NULL)
return;
if (method != 8)
png_warning(png_ptr, "Only compression method 8 is supported by PNG");
png_ptr->zlib_text_method = method;
}
#endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
/* end of API added to libpng-1.5.4 */
#endif /* WRITE */