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skia / third_party / libpng / refs/tags/v1.7.0beta80 / . / pngwutil.c
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/* 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);
}
static png_alloc_size_t
png_write_row_buffer_size(png_const_structrp png_ptr)
/* Returns the width of the widest pass in the first row of an interlaced
* image. Passes in the first row are: 0.5.3.5.1.5.3.5, so the widest row is
* normally the one from pass 5. The only exception is if the image is only
* one pixel wide, so:
*/
#define PNG_FIRST_ROW_MAX_WIDTH(w) (w > 1U ? PNG_PASS_COLS(w, 5U) : 1U)
/* For interlaced images the count of pixels is rounded up to a the number of
* pixels in the first pass (numbered 0). This ensures that passes before
* the last can be packed in the buffer without overflow.
*/
{
png_alloc_size_t w;
/* If the image is interlaced adjust 'w' for the interlacing: */
if (png_ptr->interlaced != PNG_INTERLACE_NONE)
{
/* Take advantage of the fact that 1-row interlaced PNGs require half the
* normal row width:
*/
if (png_ptr->height == 1U) /* no pass 6 */
w = PNG_FIRST_ROW_MAX_WIDTH(png_ptr->width);
/* Otherwise round up to a multiple of 8. This may waste a few (less
* than 8) bytes for PNGs with a height less than 57 but this hardly
* matters.
*/
else
w = (png_ptr->width + 7U) & ~7U;
}
else
w = png_ptr->width;
/* The rounding above may leave 'w' exactly 2^31 */
debug(w <= 0x80000000U);
switch (png_ptr->row_output_pixel_depth)
{
/* This would happen if the function is called before png_write_IHDR. */
default: NOT_REACHED; return 0;
case 1: w = (w+7) >> 3; break;
case 2: w = (w+3) >> 2; break;
case 4: w = (w+1) >> 1; break;
case 8: break;
case 16: w <<= 1; break; /* overflow: w is set to 0, which is OK */
/* For the remaining cases the answer is w*bytes; where bytes is 3,4,6
* or 8. This may overflow 32 bits. There is no way to compute the
* result on an arbitrary platform, so test the maximum of a (size_t)
* against w for each possible byte depth:
*/
# define CASE(b)\
case b*8:\
if (w <= (PNG_SIZE_MAX/b)/*compile-time constant*/)\
return w * b;\
return 0;
CASE(3)
CASE(4)
CASE(6)
CASE(8)
# undef CASE
}
/* This is the low bit depth case. The following can never be false on
* systems with a 32-bit or greater size_t:
*/
if (w <= PNG_SIZE_MAX)
return w;
return 0U;
}
/* This is used below to find the size of an image to pass to png_deflate_claim.
* It returns 0xFFFFFFFFU for images whose size would overflow a 32-bit integer
* or have rows which cannot be allocated.
*/
static png_alloc_size_t
png_image_size_checked(png_const_structrp png_ptr)
{
/* The size returned here is limited to PNG_SIZE_MAX, if the size would
* exceed that (or is close to exceeding that) 0 is returned. See below for
* a variant that limits the size of 0xFFFFFFFFU.
*/
const png_uint_32 h = png_ptr->height;
const png_alloc_size_t rowbytes = png_write_row_buffer_size(png_ptr);
/* NON-INTERLACED: (1+rowbytes) * h
* INTERLACED: Each pixel is transmitted exactly once, so the size is
* (rowbytes * h) + the count of filter bytes. Each complete
* block of 8 image rows generates at most 15 output rows
* (less for narrow images), so the filter byte count is
* at most (15*h/8)+14. Because the original rows are split
* extra byte passing may be introduced. Account for this by
* allowing an extra 1 byte per output row; that's two bytes
* including the filer byte.
*
* So:
* NON-INTERLACED: (rowbytes * h) + h
* INTERLACED: < (rowbytes * h) + 2*(15 * h/8) + 2*15
*
* Hence:
*/
if (rowbytes != 0)
{
if (png_ptr->interlaced == PNG_INTERLACE_NONE)
{
const png_alloc_size_t limit = PNG_SIZE_MAX / h;
/* On 16-bit systems the above might be 0, so: */
if (rowbytes </*allow 1 for filter byte*/ limit)
return (rowbytes+1U) * h;
}
else /* INTERLACED */
{
const png_uint_32 w = png_ptr->width;
/* 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)
{
const png_uint_32 pass_w = PNG_PASS_COLS(w, pass);
if (pass_w > 0)
{
const png_uint_32 pass_h = PNG_PASS_ROWS(h, pass);
if (pass_h > 0)
{
/* This is the number of bytes available for each row of this
* pass:
*/
const png_alloc_size_t limit = (PNG_SIZE_MAX - cb_base)/pass_h;
/* This cannot overflow because if it did rowbytes would
* have been 0 above.
*/
const png_alloc_size_t pass_bytes =
PNG_ROWBYTES(png_ptr->row_output_pixel_depth, pass_w);
if (pass_bytes </*allow 1 for filter byte*/ limit)
cb_base += (pass_bytes+1U) * pass_h;
else
return 0U; /* insufficient address space left */
}
}
}
return cb_base;
}
}
/* Failure case: */
return 0U;
}
/* This is used below to find the size of an image to pass to png_deflate_claim.
* It returns 0xFFFFFFFFU for images whose size would overflow a 32-bit integer
* or have rows which cannot be allocated.
*/
static png_alloc_size_t
png_image_size(png_const_structrp png_ptr)
{
png_alloc_size_t size = png_image_size_checked(png_ptr);
if (size > 0U && size < 0xffffffffU)
return size;
return 0xffffffffU;
}
/* 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.
*
* NOTE: if png_compress is called with input_len 0 and flush set
* to Z_NO_FLUSH this affirm will fire because zlib will have no
* work to do.
*/
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 */
png_compression_bufferp stash; /* Unused compression buffers */
# define ps_png_ptr(ps) png_upcast(png_const_structrp, (ps)->s.zs.opaque)
/* A png_ptr, used below in functions that only have a png_zlib_state.
* NOTE: the png_zlib_compress must have been initialized!
*/
png_uint_32 zlib_max_pixels;
/* Maximum number of pixels that zlib can handle at once; the lesser of
* the PNG maximum and the maximum that will fit in (uInt)-1 bytes. This
* number of pixels may not be byte aligned.
*/
png_uint_32 zlib_max_aligned_pixels;
/* The maximum number of pixels that zlib can handle while maintaining a
* buffer byte alignment of PNG_ROW_BUFFER_BYTE_ALIGN; <= the previous
* value.
*/
# ifdef PNG_WRITE_FILTER_SUPPORTED
/* During write libpng needs the previous row when writing a new row with
* up, avg or paeth and one or more image rows when performing filter
* selection. So if performing filter selection typically two or more
* rows are required while if no filter selection is to be done only the
* previous row pointer is required.
*/
png_bytep previous_write_row;
png_alloc_size_t write_row_size; /* Actual size of the buffers */
png_uint_32 save_row_count; /* Total number to be buffered */
# define SAVE_ROW_COUNT_UNSET 0xFFFFFFFFU
unsigned int row_buffer_max_pixels;
/* The maximum number of pixels that can fit in PNG_ROW_BUFFER_SIZE
* bytes; not necessary a whole number of bytes.
*/
unsigned int row_buffer_max_aligned_pixels;
/* The maximum number of pixels that can fit in PNG_ROW_BUFFER_SIZE
* bytes while maintaining PNG_ROW_BUFFER_BYTE_ALIGN alignment.
*/
unsigned int filter_mask :8; /* mask of filters to consider on NEXT row */
unsigned int filters :8; /* Filters for current row */
unsigned int do_select :1; /* Set if filter selection should be done */
# endif /* WRITE_FILTER */
/* Compression settings: see below for how these are encoded. */
png_uint_32 pz_IDAT; /* Settings for the image */
png_uint_32 pz_iCCP; /* Settings for iCCP chunks */
png_uint_32 pz_text; /* Settings for text chunks */
png_uint_32 pz_current; /* Last set settings */
# 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 */
} png_zlib_state;
/* Create the zlib state: */
static void
png_create_zlib_state(png_structrp png_ptr)
{
png_zlib_statep ps = png_voidcast(png_zlib_state*,
png_malloc(png_ptr, sizeof *ps));
/* Clear to NULL/0: */
memset(ps, 0, sizeof *ps);
debug(png_ptr->zlib_state == NULL);
png_ptr->zlib_state = ps;
png_zlib_compress_init(png_ptr, &ps->s);
# ifdef PNG_WRITE_FILTER_SUPPORTED
ps->save_row_count = SAVE_ROW_COUNT_UNSET;
# endif /* WRITE_FILTER */
# 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;
# endif /* WRITE_FLUSH */
}
/* 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)
{
# ifdef PNG_WRITE_FILTER_SUPPORTED
/* Free any mode-specific data that is owned here: */
if (ps->previous_write_row != NULL)
{
/* No saved rows, so the previous row buffer was allocated: */
png_bytep p = ps->previous_write_row;
ps->previous_write_row = NULL;
png_free(png_ptr, p);
}
# endif /* WRITE_FILTER */
/* 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);
}
}
/* Compression settings.
*
* These are stored packed into a png_uint_32 to make comparison with the
* current setting quick. The packing method uses four bits for each setting
* and reserves '0' for unset.
*
* ps_<setting>_base: The lowest valid value (encoded as 1).
* ps_<setting>_max: The highest valid value.
* ps_<setting>_pos: The position in the range 0..3 (shift of 0..12).
*
* The low 16 bits are the zlib compression parameters:
*/
#define pz_level_base (-1)
#define pz_level_max 9
#define pz_level_pos 0
#define pz_windowBits_base 8
#define pz_windowBits_max 15
#define pz_windowBits_pos 1
#define pz_memLevel_base 1
#define pz_memLevel_max 9
#define pz_memLevel_pos 2
#define pz_strategy_base 0
#define pz_strategy_max 4
#define pz_strategy_pos 3
#define pz_zlib_bits 0xFFFFU
/* Anything below this is not used directly by zlib: */
#define pz_png_level_base 0 /* libpng equivalent of zlib level */
#define pz_png_level_max 10
#define pz_png_level_pos 4
#define pz_offset(name) (pz_ ## name ## _base - 1)
/* setting_value == pz_offset(setting)+encoded_value */
#define pz_min(name) pz_ ## name ## _base
#define pz_max(name) pz_ ## name ## _max
#define pz_shift(name) (4 * pz_ ## name ## _pos)
#define pz_bits(name,x) ((int)(((x)>>pz_shift(name))&0xF))
/* the encoded value, or 0 if unset */
/* Enquiries: */
#define pz_isset(name,x) (pz_bits(name,x) != 0)
#define pz_value(name,x) (pz_bits(name,x)+pz_offset(name))
/* Assignments: */
#define pz_clear(name,x) ((x)&~((png_uint_32)0xFU<<pz_shift(name)))
#define pz_encode(name,v) ((png_uint_32)((v)-pz_offset(name))<<pz_shift(name))
#define pz_change(name,x,v) (pz_clear(name,x) | pz_encode(name, v))
/* Direct use/modification: */
#define pz_var(ps, type) ((ps)->pz_ ## type)
#define pz_get(ps, type, name, def)\
(pz_isset(name, pz_var(ps, type)) ? pz_value(name, pz_var(ps, type)) : (def))
/* pz_assign checks for out-of-range values and clears the setting if these are
* given. No warning or error is generated.
*/
#define pz_assign(ps, type, name, value)\
(pz_var(ps, type) = pz_clear(name, pz_var(ps, type)) |\
((value) >= pz_min(name) && (value) <= pz_max(name) ?\
pz_encode(name, value) : 0))
/* There is (as of zlib 1.2.8) a bug in the implementation of compression with a
* window size of 256 which zlib works round by resetting windowBits from 8 to 9
* whenever deflateInit2 is called with that value. Fix this up here.
*/
static void
fix_cinfo(png_zlib_statep ps, png_bytep data, png_alloc_size_t data_size)
{
/* Do this if the CINFO field is '1', meaning windowBits of 9. The first
* byte of the stream is the CMF value, CINFO is in the upper four bits.
*
* If zlib didn't futz with the value then it should match the value in
* pz_current; check this is debug. (See below for why this works in the
* pz_default_settings call.)
*/
# define png_ptr png_voidcast(png_const_structrp, ps->s.zs.opaque)
if (data[0] == 0x18U &&
pz_get(ps, current, windowBits, 0) == 8 /* i.e. it was requested */)
{
/* Double check this here; the fixup only works if the data was 256 bytes
* or shorter *or* the window is never used. For safety repeat the checks
* done in pz_default_settings; technically we should be able to just skip
* this test.
*
* TODO: set a 'fixup' flag in zlib_state to make this quicker?
*/
if (data_size <= 256U ||
pz_get(ps, current, strategy, Z_RLE) == Z_HUFFMAN_ONLY ||
pz_get(ps, current, level, 1) == Z_NO_COMPRESSION)
{
unsigned int d1;
data[0] = 0x08U;
/* The header checksum must be fixed too. The FCHECK (low 5 bits) make
* CMF.FLG a multiple of 31:
*/
d1 = data[1] & 0xE0U; /* top three bits */
d1 += 31U - (0x0800U + d1) % 31U;
data[1] = PNG_BYTE(d1);
}
else /* pz_default_settings is expected to guarantee the above */
NOT_REACHED;
}
else
debug(pz_get(ps, current, windowBits, 0) == 8+(data[0] >> 4));
# undef png_ptr
}
static png_uint_32
pz_default_settings(png_uint_32 settings, png_uint_32 owner,
png_alloc_size_t data_size)
{
int png_level, strategy, zlib_level, windowBits;
/* The png 'level' parameter controls the defaults below, it defaults to
* 6 (at present).
*/
if (!pz_isset(png_level, settings))
png_level = 6U; /* the default */
else
png_level = pz_value(png_level, settings);
/* First default the strategy. At lower data sizes other strategies do as
* well as the zlib default compression strategy but they never seem to
* improve on it with the 1.7 filtering.
*/
if (!pz_isset(strategy, settings))
{
switch (png_level)
{
case 1: /* ultra-fast */
case 2:
/* RLE is as fast as HUFFMAN_ONLY and can reduce size a lot in a few
* cases.
*/
strategy = Z_RLE;
break;
case 3: case 4: case 5: case 6:
/* Z_FILTERED is almost as good as the default and can be
* significantly faster, it biases the algorithm towards smaller
* byte values.
*/
if (owner == png_IDAT || owner == png_iCCP)
strategy = Z_FILTERED;
else /* text chunk */
strategy = Z_FIXED;
break;
default: /* includes the 'no compression' option */
strategy = Z_DEFAULT_STRATEGY;
break;
}
settings |= pz_encode(strategy, strategy);
}
else
strategy = pz_value(strategy, settings);
/* Next the zlib level; this just defaults to the png level, except that for
* Huffman or RLE encoding the level setting for Zlib doesn't matter.
*/
if (!pz_isset(level, settings))
{
switch (strategy)
{
case Z_HUFFMAN_ONLY:
case Z_RLE:
/* The 'level' doesn't make any significant difference to the
* compression with these strategies; in a test set of about 3GByte
* of PNG files the total compressed size changed under 20 bytes
* with libpng 1.6!
*/
zlib_level = 1;
break;
default: /* Z_FIXED, Z_FILTERED, Z_DEFAULT_STRATEGY */
/* Everything that uses the window seems to show rapidly diminishing
* returns above level 6 (at least with libpng 1.6).
* Z_DEFAULT_COMPRESSION is, in fact, level 6 so Mark seems to
* concur.
*/
if (png_level < 9)
zlib_level = png_level;
else /* PNG compression level 10; the ridiculous level */
zlib_level = 9;
break;
}
settings |= pz_encode(level, zlib_level);
}
else
zlib_level = pz_value(level, settings);
/* Now default windowBits. This is probably the most important of the
* settings because it is pretty much the only one that affects decode
* performance. The smaller the better:
*/
if (!pz_isset(windowBits, settings))
{
if (zlib_level == Z_NO_COMPRESSION)
windowBits = 8;
/* If the strategy has been set to something that doesn't benefit from
* higher windowBits values take advantage of this. Note that pz_value
* returns an invalid value if pz_isset is false.
*/
else switch (strategy)
{
png_alloc_size_t test_size;
case Z_HUFFMAN_ONLY:
/* Use the minimum; the window doesn't get used */
windowBits = 8;
break;
case Z_RLE:
/* The longest length code is 258 bytes, the shortest string that
* can achieve this is 259 bytes long; 259 copies of the same byte
* which can be encoded as a code for the byte value then a string
* of length 258 starting at the first byte. So if the data is
* longer than 256 bytes use '9' for the windowBits, otherwise use
* 8:
*/
if (data_size <= 256U)
windowBits = 8;
else
windowBits = 9;
break;
/* By experiment using about 150,000 files the optimal windowBits
* value across a range of files is somewhat less than implied by
* the data size and depends on the zlib level and the strategy
* used, the following values were determined by experiment using
* those files:
*/
case Z_FILTERED:
/* The Z_FILTERED case changes suddenly at (zlib) level 4 to
* benefitt from looking at all the data:
*/
if (zlib_level < 4)
test_size = data_size / 8U;
else
test_size = data_size;
goto check_test_size;
case Z_FIXED:
/* With the fixed Huffman tables better compression only ever comes
* from looking for matches, so, logically:
*/
test_size = data_size;
goto check_test_size;
default:
/* The default algorithm always does better with a window smaller
* than all the data and shows jumps at level 4 and level 8:
*/
switch (zlib_level)
{
case 1: case 2: case 3:
test_size = data_size / 8U;
break;
default:
/* This includes, implicitly, ZLIB_NO_COMPRESSION, but that
* was eliminated in the 'if' above.
*/
test_size = data_size / 4U;
break;
case 8: case 9:
test_size = data_size / 3U;
break;
}
goto check_test_size;
check_test_size:
/* Find the smallest window that covers 'test_size' bytes, subject
* to the constraint that if the actual data size is more than 256
* bytes the minimum windowBits that can be supported is 9:
*/
if (data_size <= 256U)
windowBits = 8;
else
windowBits = 9;
while (windowBits < 15 && (1U << windowBits) < test_size)
++windowBits;
break;
}
settings |= pz_encode(windowBits, windowBits);
}
else
windowBits = pz_value(windowBits, settings);
/* zlib has a problem with 256 byte windows; 512 is used instead.
* We can't work round this if the data size is more than 256 bytes and
* the strategy actually uses the window (everything except huffman-only)
* so fix the problem here.
*/
if (windowBits == 8 && data_size > 256U && strategy != Z_HUFFMAN_ONLY &&
zlib_level != Z_NO_COMPRESSION)
settings = pz_change(windowBits, settings, 9);
/* For memLevel this just increases the memory used but can help with the
* Huffman code generation even to level 9 (the maximum), so just set the
* max. This affects memory used, not (apparently) compression speed so apps
* with limited memory requirements may need to override it.
*/
if (!pz_isset(memLevel, settings))
settings |= pz_encode(memLevel, MAX_MEM_LEVEL/*from zconf.h*/);
return settings;
}
/* 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;
if (png_ptr->zlib_state == NULL)
png_create_zlib_state(png_ptr);
ps = png_ptr->zlib_state;
affirm(ps != NULL && png_ptr->zowner == 0);
{
int ret; /* zlib return code */
png_uint_32 settings;
switch (owner)
{
case png_IDAT:
settings = ps->pz_IDAT;
break;
case png_iCCP:
settings = ps->pz_iCCP;
break;
default: /* text chunk */
settings = ps->pz_text;
break;
}
settings = pz_default_settings(settings, owner, data_size);
/* Check against the previous initialized values, if any. The relevant
* settings are in the low 16 bits.
*/
if (ps->s.zs.state != NULL &&
((settings ^ ps->pz_current) & pz_zlib_bits) != 0U)
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, pz_value(level, settings), Z_DEFLATED,
pz_value(windowBits, settings), pz_value(memLevel, settings),
pz_value(strategy, settings));
ps->pz_current = settings;
/* 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);
/* Correct the zlib CINFO field: */
if (ps->s.len >= 2U)
fix_cinfo(ps, ps->s.list->output, input_len);
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
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)
* fix the Zlib CINFO field if required:
*/
if ((png_ptr->mode & PNG_HAVE_IDAT) == 0U &&
avail >= start+2U /* enough for the zlib header */)
{
debug(start == 0U);
fix_cinfo(ps, 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);
/* 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_structrp png_ptr, png_zlib_statep ps,
png_zlib_compressp pz, png_const_voidp input, uInt input_len, int flush)
{
/* Delay initialize the z_stream. */
if (png_ptr->zowner != png_IDAT)
png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr));
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.
*/
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);
}
}
/* This is called at the end of every row to handle the required callbacks and
* advance png_struct::row_number and png_struct::pass.
*/
static void
png_write_end_row(png_structrp png_ptr, int flush)
{
png_uint_32 row_number = png_ptr->row_number;
unsigned int pass = png_ptr->pass;
debug(pass < 7U);
implies(flush == Z_FINISH, png_ptr->zowner == 0U);
/* API NOTE: the write callback is made before any changes to the row number
* or pass however, in 1.7.0, the zlib stream can be closed before the
* callback is made (this is new). The application flush function happens
* afterward as was the case before. In 1.7.0 this is solely determined by
* the order of the code that follows.
*/
if (png_ptr->write_row_fn != NULL)
png_ptr->write_row_fn(png_ptr, row_number, pass);
# ifdef PNG_WRITE_FLUSH_SUPPORTED
if (flush == Z_SYNC_FLUSH)
{
if (png_ptr->output_flush_fn != NULL)
png_ptr->output_flush_fn(png_ptr);
png_ptr->zlib_state->flush_rows = 0U;
}
# else /* !WRITE_FLUSH */
PNG_UNUSED(flush)
# endif /* !WRITE_FLUSH */
/* Finally advance to the next row/pass: */
if (png_ptr->interlaced == PNG_INTERLACE_NONE)
{
debug(row_number < png_ptr->height);
if (++row_number == png_ptr->height) /* last row */
{
row_number = 0U;
debug(flush == Z_FINISH);
png_ptr->pass = 7U;
}
}
# ifdef PNG_WRITE_INTERLACING_SUPPORTED
else /* interlaced */ if (png_ptr->do_interlace)
{
/* This gets called only for rows that are processed; i.e. rows that
* are in the pass of a pass which is itself in the output.
*/
debug(row_number < png_ptr->height &&
PNG_PASS_IN_IMAGE(png_ptr->width, png_ptr->height, pass) &&
pass <= PNG_LAST_PASS(png_ptr->width, png_ptr->height) &&
PNG_ROW_IN_INTERLACE_PASS(row_number, pass));
/* NOTE: the last row of the original image may not be in the pass, in
* this case the code which skipped the row must do the increment
* below! See 'interlace_row' in pngwrite.c and the code in
* write_png_rows below.
*
* In that case an earlier row will be the last one in the pass (if the
* pass is in the output), check this here:
*/
implies(pass == PNG_LAST_PASS(png_ptr->width, png_ptr->height) &&
PNG_LAST_PASS_ROW(row_number, pass, png_ptr->height),
flush == Z_FINISH);
if (++row_number == png_ptr->height) /* last row */
{
row_number = 0U;
png_ptr->pass = 0x7U & ++pass;
}
}
# endif /* WRITE_INTERLACING */
else /* application does interlace */
{
implies(png_ptr->height == 1U, pass != 6U);
debug(PNG_PASS_IN_IMAGE(png_ptr->width, png_ptr->height, pass) &&
row_number < PNG_PASS_ROWS(png_ptr->height, pass));
if (++row_number == PNG_PASS_ROWS(png_ptr->height, pass))
{
/* last row in this pass, next one may be empty. */
row_number = 0U;
do
++pass;
while (pass < 7U &&
!PNG_PASS_IN_IMAGE(png_ptr->width, png_ptr->height, pass));
implies(png_ptr->height == 1U, pass != 6U);
implies(pass == 7U, flush == Z_FINISH);
png_ptr->pass = 0x7U & pass;
}
}
png_ptr->row_number = row_number;
}
/* This returns the zlib compression state for APIs that may be called before
* the first call to png_write_row (so when the state might not exist). It
* performs initialization as required.
*/
#if defined(PNG_WRITE_FLUSH_SUPPORTED) || defined(PNG_WRITE_FILTER_SUPPORTED)\
|| defined(PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED)\
|| defined(PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED)
static png_zlib_statep
png_get_zlib_state(png_structrp png_ptr)
{
if (png_ptr != NULL)
{
if (png_ptr->zlib_state == NULL)
{
if (png_ptr->read_struct)
png_app_warning(png_ptr, "write API called on read");
else
png_create_zlib_state(png_ptr);
}
return png_ptr->zlib_state;
}
return NULL;
}
#endif /* things that need it */
#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");
/* Force a flush at the end of the current row by setting 'flush_rows' to the
* maximum:
*/
if (png_ptr != NULL && png_ptr->zlib_state != NULL)
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);
}
#if defined(PNG_SELECT_FILTER_HEURISTICALLY_SUPPORTED)
static void
multi_filter_row(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,
png_byte filtered_row[4][PNG_ROW_BUFFER_SIZE])
{
/* filters_to_try identifies multiple filters. */
filter_block(prev_row, prev_pixels, unfiltered_row, row_bits, bpp,
(filters_to_try & PNG_FILTER_SUB) != 0U ?
filtered_row[PNG_FILTER_VALUE_SUB-1U] : NULL,
(filters_to_try & PNG_FILTER_UP) != 0U ?
filtered_row[PNG_FILTER_VALUE_UP-1U] : NULL,
(filters_to_try & PNG_FILTER_AVG) != 0U ?
filtered_row[PNG_FILTER_VALUE_AVG-1U] : NULL,
(filters_to_try & PNG_FILTER_PAETH) != 0U ?
filtered_row[PNG_FILTER_VALUE_PAETH-1U] : NULL);
}
#endif /* SELECT_FILTER_HEURISTICALLY */
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 unsigned int
fls(size_t x)
/* As ffs but find the last set bit; the most significant */
{
unsigned int result = 0U;
unsigned int shift =
(PNG_SIZE_MAX > 0xFFFFFFFFU ? 32U : (PNG_SIZE_MAX > 0xFFFFU ? 16U : 8U));
size_t test = PNG_SIZE_MAX;
do
{
if (x & (test << shift)) result += shift, x >>= shift;
shift >>= 1;
}
while (shift);
/* Returns 0 for both 1U and 0U. */
return result;
}
static unsigned int
log2_metric(size_t x)
{
/* Return an approximation to log2(x). Since a Huffman code necessarily uses
* a whole number of bits for the code for each symbol this is very
* approximate; it uses the first two bits after the most significant to
* approximate the first two fractional bits of the log2.
*/
const unsigned int result = fls(x);
switch (result)
{
default: x >>= result-2U; break;
case 2U: break;
case 1U: x <<= 1; break;
case 0U: return 0U; /* for x == 0 and x == 1 */
}
return result * 4U + (unsigned int)/*SAFE*/(x & 0x3U);
}
static png_alloc_size_t
huffman_metric(png_byte prefix, png_const_bytep data, size_t length)
/* Given a buffer data[length] return an estimate of the length in bits of
* the same byte sequence when the bytes are coded using Huffman codes. The
* estimate is really the length in bits of the corresponding arithmetic
* code, but this is likely to be a good enough metric and it is fast to
* calculate.
*/
{
unsigned int number_of_symbols; /* distinct symbols */
size_t count[256];
/* Build a symbol count array */
memset(count, 0, sizeof count);
count[prefix] = 1U; /* the filter byte */
number_of_symbols = 1U;
{
size_t i;
for (i=0U; i < length; ++i)
if (++count[data[i]] == 1U) /* a new symbol */
++number_of_symbols;
}
++length; /* for the prefix */
/* Estimate the number of bits used to code each symbol optimally:
*
* log2(length/count[symbol])
*
* (The arithmetic code length, I believe, but that is based on my own work
* so it could quite easily be wrong. JB 20160202).
*
* So ideally:
*
* log2(length) - log2(count[symbol])
*
* Although any log base is fine for the metric. pngrtran.c has a fast and
* accurate integer log2 implementation, but that is overkill here. Instead
* the caller passes in a shift (based on log2(length)), this is applied to
* the count (which must be <= length) and the per-symbol metric is looked up
* in a fixed table.
*
* The deflate (RFC1951) coding used in the zlib (RFC1950) format has a
* Huffman code length limit of 15, so any symbol must occupy at least
* 1/32768 of the code space. Zlib also shows some unexpected behavior with
* window size increases; data compression can decrease, leading me (JB
* 20160202) to hypothesize that the addition of extra, infrequently used,
* zlib length codes damages the overall compression by reducing the
* efficiency of the Huffman coding.
*
* This shortens the code for those symbols (to 15 bits) at the cost of
* reducing the code space for the remainder of the symbols by 1/32768 for
* each such symbol.
*
* First bin by the above expression, as returned by the log2_metric
* function. This gives a .2-bit fractional number. Limit the value to 14.5
* for the above reason; place anything at or above 14.5 into the last bin.
*/
{
unsigned int i, step;
const size_t low_count = length / 23170U; /* 2^14.5 */
const unsigned int l2_length = log2_metric(length);
size_t weight;
unsigned int distinct_suffix_count[64];
/* The number of distinct suffices held in this bin. */
size_t total_count_in_data[64];
/* The total number of instances of those distinct suffices. */
size_t bits_used[64];
/* The bits used so far to encode the suffixes in the bin. */
memset(distinct_suffix_count, 0U, sizeof distinct_suffix_count);
memset(total_count_in_data, 0U, sizeof total_count_in_data);
for (i=0; i<256; ++i)
{
size_t c = count[i];
if (c > 0U)
{
const unsigned int symbol_weight =
c > low_count ? l2_length - log2_metric(c) : 63U;
++distinct_suffix_count[symbol_weight];
total_count_in_data[symbol_weight] += c;
}
}
/* Work backward through the bins distributing the suffices between code
* lengths. This approach reflects the Huffman coding method of
* allocating the lowest count first but without the need to sort the
* symbols by count or, indeed, remember the symbols. It is necessarily
* approximate as a result.
*/
memset(bits_used, 0U, sizeof bits_used);
for (i=63U, step=4U; i >= 2U; --i)
{
unsigned int suffix_count = distinct_suffix_count[i];
size_t data_count = total_count_in_data[i];
/* Encode these suffices with 1 bit to divide the bin into two equal
* halves with twice the data count; there may be an odd suffix,
* this is promoted to the next bin.
*/
if ((suffix_count & 1U) != 0U)
{
size_t remainder = data_count / suffix_count;
++distinct_suffix_count[i-1U];
total_count_in_data[i-1U] += remainder;
--suffix_count;
data_count -= remainder;
}
distinct_suffix_count[i-step] = suffix_count >> 1;
total_count_in_data[i-step] += data_count;
bits_used[i-step] += data_count + bits_used[i];
/* This causes bins 3 and 2 to push into bins 1 and 0 respectively. */
if (i == 4U)
step = 2U;
}
{
unsigned int suffix_count = distinct_suffix_count[0];
weight = bits_used[0];
/* There may only be one bin left, check: */
if (distinct_suffix_count[1] > 0)
{
suffix_count += distinct_suffix_count[1];
weight += bits_used[1];
}
/* We still have to encode suffix_count separate suffices: */
if (suffix_count > 1)
{
unsigned int bits = fls(suffix_count);
if ((suffix_count & ~(1U<<bits)) != 0U)
++bits;
weight += bits * (total_count_in_data[0] + total_count_in_data[1]);
}
}
#if !PNG_RELEASE_BUILD
/* If we have number_of_symbols symbols then they can each be encoded in
* ceil(fls(number_of_symbols)) bits, so check this:
*
* TODO: remove this (it gets removed in a release automatically)
*/
if (number_of_symbols < 128U)
{
unsigned int bits = fls(number_of_symbols);
if ((number_of_symbols & ~(1U<<bits)) != 0U)
++bits;
if (bits*4U*length < weight)
{
weight = bits*4U*length;
abort();
}
}
#endif
/* zlib has to encode the Huffman codes themselves. It needs 3 bits per
* code to do this; it just has to record the length for each symbol code,
* so the overhead would be the same in all cases however it uses RLE for
* the table and, very approximately, this makes '0' codes irrelevant.
*
* So add 3 x number_of_symbols:
*/
weight += (3U<<2)*number_of_symbols;
return weight;
}
}
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);
multi_filter_row(prev_row, prev_pixels, unfiltered_row, row_bits, bpp,
filters_to_try, test_buffers);
/* Now check each buffer and the original row to see which is best; this is
* the heuristic. The test is an estimate of the length of the byte sequence
* when coded by the LZ77 Huffman coding.
*/
{
png_alloc_size_t best_cost = (png_alloc_size_t)-1;
png_byte best_filter, test_filter;
png_const_bytep test_row;
for (best_filter = test_filter = PNG_FILTER_VALUE_NONE,
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)
{
png_alloc_size_t test_cost =
huffman_metric(test_filter, test_row, row_bytes);
if (test_cost < best_cost)
best_cost = test_cost, best_filter = test_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, flush);
else
write_filtered_row(png_ptr, test_buffers[best_filter-1], row_bytes,
best_filter, flush);
return best_filter;
}
}
#endif /* SELECT_FILTER_HEURISTICALLY */
/* 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)
{
png_zlib_statep ps = png_get_zlib_state(png_ptr);
png_debug(1, "in png_set_filter");
if (ps == NULL)
return;
/* See png_write_IHDR above; this limits the filter method to one of the
* values permitted in png_write_IHDR unless that has not been called in
* which case only the 'base' method is permitted because that is the initial
* value of png_struct::filter_method (i.e. 0).
*/
if (method != png_ptr->filter_method)
{
ps->filter_mask = 0U; /* safety: uninitialized */
png_app_error(png_ptr, "png_set_filter: method does not match IHDR");
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_NONE)
filtersIn = PNG_FILTER_MASK(filtersIn);
/* PNG_ALL_FILTERS is a constant, unfortunately it is nominally signed, for
* historical reasons, hence the 'unsigned' here. The '&' can be omitted
* anyway because of the check.
*/
if ((filtersIn & PNG_BIC_MASK(PNG_ALL_FILTERS)) == 0)
{
# ifndef PNG_SELECT_FILTER_SUPPORTED
if (filtersIn & (filtersIn-1)) /* remove LSBit */
{
#if TEMPORARY
png_app_warning(png_ptr,
"png_set_filter: filter selection not supported");
#endif
filtersIn &= -filtersIn; /* Use lowest set bit */
}
# endif /* !SELECT_FILTER */
ps->filter_mask = filtersIn & (unsigned)PNG_ALL_FILTERS;
}
else
{
/* Prior to 1.7.0 this ignored the error and just used the bits that
* are present, now it resets to the uninitialized value:
*/
ps->filter_mask = 0U; /* safety: uninitialized */
png_app_error(png_ptr, "png_set_filter: invalid filter mask/value");
}
}
#endif /* WRITE_FILTER */
/* This is the common function to write multiple rows of PNG data. The data is
* in the relevant PNG format but has had no filtering done.
*/
static void
write_png_rows(png_structrp png_ptr, png_const_bytep *rows,
png_uint_32 num_rows)
{
const png_zlib_statep ps = png_ptr->zlib_state;
const unsigned int bpp = png_ptr->row_output_pixel_depth;
# ifdef PNG_WRITE_FILTER_SUPPORTED
const png_byte filter = ps->filters;
png_const_bytep previous_row = ps->previous_write_row;
const png_uint_32 max_pixels = filter == PNG_FILTER_VALUE_NONE ?
ps->zlib_max_pixels : ps->row_buffer_max_pixels;
const png_uint_32 block_pixels = filter == PNG_FILTER_VALUE_NONE ?
ps->row_buffer_max_aligned_pixels : ps->zlib_max_aligned_pixels;
# else /* !WRITE_FILTER */
const png_byte filter = PNG_FILTER_VALUE_NONE;
const png_uint_32 max_pixels = ps->zlib_max_pixels;
const png_uint_32 block_pixels = ps->zlib_max_aligned_pixels;
# endif /* !WRITE_FILTER */
/* Write the given rows handling the png_compress_IDAT argument limitations
* (uInt) and any valid row width.
*/
png_uint_32 last_row_in_pass = 0U; /* Actual last, not last+1! */
png_uint_32 pixels_in_pass = 0U;
unsigned int first_row_in_pass = 0U; /* For do_interlace */
unsigned int pixels_at_end = 0U; /* for a partial byte at the end */
unsigned int row_info_flags = png_row_end;
int pass = -1; /* Invalid: force calculation first time round */
debug(png_ptr->row_output_pixel_depth == PNG_PIXEL_DEPTH(*png_ptr));
while (num_rows-- > 0U)
{
if (png_ptr->pass != pass)
{
/* Recalcuate the row bytes and partial bits */
pass = png_ptr->pass;
pixels_in_pass = png_ptr->width;
if (png_ptr->interlaced == PNG_INTERLACE_NONE)
{
debug(pass == 0);
last_row_in_pass = png_ptr->height - 1U;
row_info_flags |= png_pass_last; /* there is only one */
}
else
{
const png_uint_32 height = png_ptr->height;
last_row_in_pass = PNG_PASS_ROWS(height, pass);
# ifdef PNG_WRITE_INTERLACING_SUPPORTED
if (png_ptr->do_interlace)
{
/* libpng is doing the interlace handling and this is pass 6.
* The row may have to be skipped below.
*/
affirm(pass == 6); /* so pixels_in_pass is correct */
/* This overflows for 1 pixel high PNG, this does not matter;
* the result is 0xffffffff which is fine.
*/
last_row_in_pass =
PNG_ROW_FROM_PASS_ROW(last_row_in_pass-1U, pass);
first_row_in_pass = 1U;
row_info_flags |= png_pass_last; /* if there are any rows */
}
else /* Application handles the interlace */
# endif /* WRITE_INTERLACING */
{
/* The row does exist, so this works without checking the column
* count.
*/
debug(pass < 7 && last_row_in_pass > 0U);
last_row_in_pass -= 1U;
if (pass == PNG_LAST_PASS(pixels_in_pass/*PNG width*/, height))
row_info_flags |= png_pass_last;
/* Finally, adjust pixels_in_pass for the interlacing: */
pixels_in_pass = PNG_PASS_COLS(pixels_in_pass, pass);
}
}
/* Mask out the bits in a partial byte. */
pixels_at_end = pixels_in_pass & PNG_ADDOF(bpp);
# ifdef PNG_WRITE_FILTER_SUPPORTED
/* Reset the previous_row pointer correctly; NULL at the start of
* the pass. If row_number is not 0 then a previous write_rows was
* interrupted in mid-pass and any required buffer should be in
* previous_write_row (set in the initializer).
*/
if (png_ptr->row_number == first_row_in_pass)
previous_row = NULL;
# endif /* WRITE_FILTER */
}
# ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* When libpng is handling the interlace we see rows that must be
* skipped.
*/
if (!png_ptr->do_interlace ||
PNG_ROW_IN_INTERLACE_PASS(png_ptr->row_number, pass))
# endif /* WRITE_INTERLACING */
{
const int flush = row_flush(ps, row_info_flags |
(png_ptr->row_number ==
first_row_in_pass ? png_pass_first_row : 0) |
(png_ptr->row_number == last_row_in_pass ? png_pass_last_row : 0));
png_const_bytep row = *rows;
png_uint_32 pixels_to_go = pixels_in_pass;
/* The row handling uses png_compress_IDAT directly if there is no
* filter to be applied, otherwise it uses filter_row.
*/
# ifdef PNG_WRITE_FILTER_SUPPORTED
if (filter != PNG_FILTER_VALUE_NONE)
{
int start_of_row = 1;
png_byte prev_pixels[4*2*2]; /* 2 pixels up to 4x2-bytes each */
memset(prev_pixels, 0U, sizeof prev_pixels);
while (pixels_to_go > max_pixels)
{
/* Write a block at once to maintain alignment */
filter_row(png_ptr, previous_row, prev_pixels, row,
bpp * block_pixels, bpp, filter, start_of_row,
Z_NO_FLUSH);
if (previous_row != NULL)
previous_row += (block_pixels * bpp) >> 3;
row += (block_pixels * bpp) >> 3;
pixels_to_go -= block_pixels;
start_of_row = 0;
}
/* The filter code handles the partial byte at the end correctly,
* so this is all that is required:
*/
filter_row(png_ptr, previous_row, prev_pixels, row,
bpp * pixels_to_go, bpp, filter, start_of_row,
flush);
}
else
# endif /* WRITE_FILTER */
{
/* The no-filter case. */
const uInt block_bytes = (uInt)/*SAFE*/(
bpp <= 8U ?
block_pixels >> PNG_SHIFTOF(bpp) :
block_pixels * (bpp >> 3));
/* png_write_start_IDAT guarantees this, but double check for
* overflow above in debug:
*/
debug((block_bytes & (PNG_ROW_BUFFER_BYTE_ALIGN-1U)) == 0U);
/* The filter has to be written here: */
png_compress_IDAT(png_ptr, &filter, 1U/*len*/, Z_NO_FLUSH);
/* Process blocks of pixels up to the limit. */
while (pixels_to_go > max_pixels)
{
png_compress_IDAT(png_ptr, row, block_bytes, Z_NO_FLUSH);
row += block_bytes;
pixels_to_go -= block_pixels;
}
/* Now compress the remainder; pixels_to_go <= max_pixels so it will
* fit in a uInt.
*/
{
const png_uint_32 remainder =
bpp <= 8U
? (pixels_to_go-pixels_at_end) >> PNG_SHIFTOF(bpp)
: (pixels_to_go-pixels_at_end) * (bpp >> 3);
if (remainder > 0U)
png_compress_IDAT(png_ptr, row, remainder,
pixels_at_end > 0U ? Z_NO_FLUSH : flush);
else
debug(pixels_at_end > 0U);
if (pixels_at_end > 0U)
{
/* There is a final partial byte. This is PNG format so the
* left-most bits are the most significant.
*/
const png_byte last = PNG_BYTE(row[remainder] &
~(0xFFU >> (pixels_at_end * bpp)));
png_compress_IDAT(png_ptr, &last, 1U, flush);
}
}
}
png_write_end_row(png_ptr, flush);
# ifdef PNG_WRITE_FILTER_SUPPORTED
previous_row = *rows;
# endif /* WRITE_FILTER */
# undef HANDLE
} /* row in pass */
# ifdef PNG_WRITE_INTERLACING_SUPPORTED
else /* row not in pass; just skip it */
{
if (++png_ptr->row_number >= png_ptr->height)
{
debug(png_ptr->row_number == png_ptr->height);
png_ptr->row_number = 0U;
png_ptr->pass = 0x7U & (pass+1U);
}
}
# endif /* WRITE_INTERLACING */
++rows;
} /* while num_rows */
# ifdef PNG_WRITE_FILTER_SUPPORTED
/* previous_row must be copied back unless we don't need it because the
* next row is the first one in the pass (this relies on png_write_end_row
* setting row_number to 0 at the end!)
*
* png_write_start_row (below) creates the buffer if it may be needed.
*
* NOTE: when libpng handles an interlaced image the entire loop may be
* skipped above and previous_row will still be NULL.
*
* TODO: delay this.
*/
if (png_ptr->row_number != 0U && ps->previous_write_row != NULL &&
previous_row != NULL)
memcpy(ps->previous_write_row, previous_row,
png_calc_rowbytes(png_ptr, bpp, pixels_in_pass));
# endif
}
static png_zlib_statep
write_start_IDAT(png_structrp png_ptr)
/* Shared code which does everything except the filter support */
{
png_zlib_statep ps = png_ptr->zlib_state;
/* Set up the IDAT compression state. Expect the state to have been released
* by the previous owner, but it doesn't much matter if there was an error.
* Note that the stream is not claimed yet.
*/
debug(png_ptr->zowner == 0U);
/* Create the zlib state if ncessary: */
if (ps == NULL)
png_create_zlib_state(png_ptr), ps = png_ptr->zlib_state;
/* Delayed initialization of the zlib state maxima; this is not done above in
* case the zlib_state is created before the IHDR has been written, which
* would lead to the various png_struct fields used below being
* uninitialized.
*/
{
/* Initialization of the buffer size constants. */
const unsigned int bpp = PNG_PIXEL_DEPTH(*png_ptr);
const unsigned int byte_pp = bpp >> 3; /* May be 0 */
const unsigned int pixel_block =
/* Number of pixels required to maintain PNG_ROW_BUFFER_BYTE_ALIGN
* alignment. For multi-byte pixels use the first set bit to determine
* if the pixels have a greater alignment already.
*/
bpp < 8U ?
PNG_ROW_BUFFER_BYTE_ALIGN * (8U/bpp) :
PNG_ROW_BUFFER_BYTE_ALIGN <= (byte_pp & -byte_pp) ?
1U :
PNG_ROW_BUFFER_BYTE_ALIGN / (byte_pp & -byte_pp);
/* pixel_block must always be a power of two: */
debug(bpp > 0 && pixel_block > 0 &&
(pixel_block & -pixel_block) == pixel_block &&
((8U*PNG_ROW_BUFFER_BYTE_ALIGN-1U) & (pixel_block*bpp)) == 0U);
/* Zlib maxima */
{
png_uint_32 max = (uInt)-1; /* max bytes */
if (bpp <= 8U)
{
/* Maximum number of bytes PNG can generate in the lower bit depth
* cases:
*/
png_uint_32 png_max =
(0x7FFFFFFF + PNG_ADDOF(bpp)) >> PNG_SHIFTOF(bpp);
if (png_max < max)
max = 0x7FFFFFFF;
}
else /* bpp > 8U */
{
max /= byte_pp;
if (max > 0x7FFFFFFF)
max = 0x7FFFFFFF;
}
/* So this is the maximum number of pixels regardless of alignment: */
ps->zlib_max_pixels = max;
/* For byte alignment the value has to be a multiple of pixel_block and
* that is a power of 2, so:
*/
ps->zlib_max_aligned_pixels = max & ~(pixel_block-1U);
}
# ifdef PNG_WRITE_FILTER_SUPPORTED
/* PNG_ROW_BUFFER maxima; this is easier because PNG_ROW_BUFFER_SIZE is
* limited so that the number of bits fits in any ANSI-C
* (unsigned int).
*/
{
const unsigned int max = (8U * PNG_ROW_BUFFER_SIZE) / bpp;
ps->row_buffer_max_pixels = max;
ps->row_buffer_max_aligned_pixels = max & ~(pixel_block-1U);
}
# endif /* WRITE_FILTER */
}
{
const png_alloc_size_t image_size = png_image_size_checked(png_ptr);
const png_uint_32 settings = pz_default_settings(ps->pz_IDAT, png_IDAT,
image_size > 0 && image_size < 0xffffffffU ? image_size : 0xffffffffU);
/* Freeze the settings now; this avoids the need to call
* pz_default_settings again when the zlib stream is initialized. Also,
* the caller relies on this.
*/
ps->pz_IDAT = settings;
}
return ps;
}
#ifdef PNG_WRITE_FILTER_SUPPORTED
void /* PRIVATE */
png_write_start_IDAT(png_structrp png_ptr)
{
png_zlib_statep ps = write_start_IDAT(png_ptr);
png_byte mask;
{
/* Now default the filter mask if it hasn't been set already: */
mask = ps->filter_mask;
if (mask == 0)
{
# ifdef PNG_SELECT_FILTER_SUPPORTED
/* The result depends on the png compression level: */
const int png_level = pz_value(png_level, ps->pz_IDAT);
if (png_level < 4)
mask = PNG_FILTER_NONE; /* NOTE: the mask, not the value! */
else if (png_level < 7)
mask = PNG_FAST_FILTERS;
else
mask = PNG_ALL_FILTERS;
# else /* !SELECT_FILTER */
mask = PNG_FILTER_NONE;
# endif /* !SELECT_FILTER */
ps->filter_mask = mask;
}
}
{
const png_alloc_size_t write_row_size =
png_write_row_buffer_size(png_ptr); /* may be 0 */
png_uint_32 src = ps->save_row_count; /* may be set by the app */;
ps->write_row_size = write_row_size;
/* If the row is too long to buffer on this system skip the allocation;
* the per-row code will handle the absence of the buffer.
*/
if (write_row_size == 0U) /* row too large to buffer */
ps->save_row_count = 0U;/* no buffering; filters will be NONE or SUB */
/* If unset no filter selection is required (or, maybe, available),
* respect the app setting if the buffering has been set to 'off' or
* 'previous row':
*/
if (src >= 2U)
{
/* This is slightly more complicated. The previous-row filters only
* actually require a previous row after the first row in the pass, so
* only if height is 2 or more in a non-interlaced image and 3 or more
* in an interlaced image. Set save_row_count to 1 or 0 as
* appropriate:
*
* If the app set save_row_count to 2 or more then filter selection is
* compiled out, use the same logic to check height:
*/
ps->save_row_count =
(src < SAVE_ROW_COUNT_UNSET /* app setting */ ||
(src == SAVE_ROW_COUNT_UNSET /* default */ &&
(mask & (PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH)) != 0U))
&& png_ptr->height > 1U+(png_ptr->interlaced != PNG_INTERLACE_NONE);
}
}
/* Don't allocate anything yet. png_write_rows_internal (pngwrite.c) may end
* up passing the whole pass or the whole image, in which case extra
* buffering is not required.
*/
}
static void
png_write_start_row(png_zlib_statep ps)
/* Called at the start of a row to set up anything required for filter
* handling in the row. Sets png_zlib_state::filters to a single filter.
*
* NOTE: this is not called at the start of *every* row. If multiple rows
* are processed at once it is only called once.
*/
{
/* No filter selection, so choose the first filter */
unsigned int mask = ps->filter_mask;
if (ps->save_row_count < 1U) /* no previous row support */
mask &= PNG_BIC_MASK(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
/* Convert the lowest set bit into the corresponding value. If no bits
* are set select NONE. After this switch statement the value of
* ps->filters is guaranteed to just be a single filter.
*/
switch (mask & -mask)
{
default: ps->filters = PNG_FILTER_VALUE_NONE; break;
case PNG_FILTER_SUB: ps->filters = PNG_FILTER_VALUE_SUB; break;
case PNG_FILTER_UP: ps->filters = PNG_FILTER_VALUE_UP; break;
case PNG_FILTER_AVG: ps->filters = PNG_FILTER_VALUE_AVG; break;
case PNG_FILTER_PAETH: ps->filters = PNG_FILTER_VALUE_PAETH; break;
}
/* If previous row filters are enabled make sure that the previous row
* buffer is allocated.
*/
if (ps->save_row_count != 0U && ps->previous_write_row == NULL)
{
/* OOM is handled silently, as is the case where the row is too large
* to buffer.
*/
ps->previous_write_row = png_voidcast(png_bytep,
png_malloc_base(ps_png_ptr(ps), ps->write_row_size));
if (ps->previous_write_row == NULL)
{
ps->save_row_count = 0U; /* OOM */
if (ps->filters > PNG_FILTER_VALUE_SUB)
ps->filters = PNG_FILTER_VALUE_NONE;
}
}
}
/* 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.
*/
static void
write_png_data(png_structrp png_ptr, png_const_bytep prev_row,
png_bytep prev_pixels, png_const_bytep unfiltered_row, png_uint_32 x,
unsigned int row_bits, unsigned int row_info_flags)
/* This filters the row appropriately and returns an updated prev_row
* (updated for 'x').
*/
{
const png_zlib_statep ps = png_ptr->zlib_state;
const unsigned int bpp = png_ptr->row_output_pixel_depth;
const int flush = row_flush(ps, row_info_flags);
const png_byte filter = ps->filters; /* just one */
/* These invariants are expected from the caller: */
affirm(row_bits <= 8U*PNG_ROW_BUFFER_SIZE);
debug(filter < PNG_FILTER_VALUE_LAST/*sic: last+1*/);
/* 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 (filter == 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
filter_row(png_ptr,
(row_info_flags & png_pass_first_row) ? NULL : prev_row,
prev_pixels, unfiltered_row, row_bits, bpp, filter, x == 0, flush);
/* Handle end of row: */
if ((row_info_flags & png_row_end) != 0)
png_write_end_row(png_ptr, flush);
}
void /* PRIVATE */
png_write_png_data(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 png_zlib_statep ps = png_ptr->zlib_state;
affirm(ps != NULL);
{
const unsigned int bpp = png_ptr->row_output_pixel_depth;
const unsigned int row_bits = width * bpp;
png_bytep prev_row;
debug(bpp <= 64U && width <= 65535U &&
width < 65535U/bpp); /* Expensive: only matters on 16-bit */
/* This is called once before starting a new row here, but below it is
* only called once between starting a new list of rows.
*/
if (x == 0)
png_write_start_row(ps);
/* prev_row is either NULL or the position in the previous row buffer */
prev_row = ps->previous_write_row;
if (prev_row != NULL && x > 0)
prev_row += png_calc_rowbytes(png_ptr, bpp, x);
/* This is the single filter case (no selection): */
write_png_data(png_ptr, prev_row, prev_pixels, unfiltered_row, x,
row_bits, row_info_flags);
/* 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);
}
}
void /*PRIVATE */
png_write_png_rows(png_structrp png_ptr, png_const_bytep *rows,
png_uint_32 num_rows)
/* This is the fast version of the above which receives complete rows. The
* final byte may still require separate handling.
*/
{
const png_zlib_statep ps = png_ptr->zlib_state;
affirm(ps != NULL);
/* Set the filter to use: */
png_write_start_row(ps);
/* Now write all the rows with the same filter: */
write_png_rows(png_ptr, rows, num_rows);
}
#else /* !WRITE_FILTER */
void /* PRIVATE */
png_write_start_IDAT(png_structrp png_ptr)
{
(void)write_start_IDAT(png_ptr);
}
void /* PRIVATE */
png_write_png_data(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);
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);
PNG_UNUSED(prev_pixels);
/* Handle end of row: */
if ((row_info_flags & png_row_end) != 0)
png_write_end_row(png_ptr, flush);
}
void /*PRIVATE */
png_write_png_rows(png_structrp png_ptr, png_const_bytep *rows,
png_uint_32 num_rows)
/* This is the fast version of the above which receives complete rows. The
* final byte may still require separate handling.
*/
{
write_png_rows(png_ptr, rows, num_rows);
}
#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)
pz_assign(ps, IDAT, 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)
pz_assign(ps, IDAT, memLevel, 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)
pz_assign(ps, IDAT, 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)
pz_assign(ps, IDAT, windowBits, window_bits);
}
void PNGAPI
png_set_compression_method(png_structrp png_ptr, int method)
{
png_debug(1, "in png_set_compression_method");
/* This used to just warn, this seems unhelpful and might result in bogus
* PNG files if zlib starts accepting other methods.
*/
if (method != 8)
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)
pz_assign(ps, 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)
pz_assign(ps, text, memLevel, 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)
pz_assign(ps, 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)
pz_assign(ps, text, windowBits, 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 (method != 8)
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 */