/* 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, buf+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; } /* 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. */ struct filter_selector; /* Used only for filter selection */ 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. */ png_alloc_size_t write_row_size; /* Size of the PNG row (without the filter byte) in bytes or 0 if it is * too large to be cached. */ # 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; /* Last row written, if any */ # ifdef PNG_SELECT_FILTER_SUPPORTED png_bytep current_write_row; /* Row being written */ struct filter_selector *selector; /* Data for filter selection */ png_uint_32 filter_select_window; /* The number of bytes of uncompressed PNG data which are assumed to * be relevant when doing filter selection. Limited to 8453377 * (about 2^23); the maximum number of bytes that can be encoded in * the largest deflate window. */ # define PNG_FILTER_SELECT_WINDOW_MAX 8453377U png_byte filter_select_threshold; /* If the number of distinct codes seen in the PNG data are below * this threshold the PNG data will not be filtered (if the 'none' * filter is allowed). If this is still true and a particular * filter does not add new codes that filter will be used. */ png_byte filter_select_threshold2; /* If the number of distinct codes that result by using a particular * filter is below this second threshold that filter will be used. * (When multiple filters pass this criterion the lowest numbered * one producing the lowest number of new codes will be * chosen.) */ # endif /* SELECT_FILTER */ 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 */ # define PREVIOUS_ROW_FILTERS\ (PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH) unsigned int filters :8; /* Filters for current row */ unsigned int save_row :2; /* As below: */ # define SAVE_ROW_UNSET 0U # define SAVE_ROW_OFF 1U /* Previous-row filters will be ignored */ # define SAVE_ROW_DEFAULT 2U /* Default to save rows set by libpng */ # define SAVE_ROW_ON 3U /* Force rows to be saved */ # define SAVE_ROW(ps) ((ps)->save_row >= SAVE_ROW_DEFAULT) # 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->previous_write_row = NULL; # ifdef PNG_SELECT_FILTER_SUPPORTED ps->current_write_row = NULL; ps->selector = NULL; # endif /* SELECT_FILTER */ # 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 */ } static void png_zlib_state_set_buffer_limits(png_const_structrp png_ptr, png_zlib_statep ps) /* 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 */ /* NOTE: this will be 0 for very long rows on 32-bit or less systems */ ps->write_row_size = png_write_row_buffer_size(png_ptr); } static png_zlib_statep get_zlib_state(png_structrp png_ptr) { if (png_ptr->zlib_state == NULL) png_create_zlib_state(png_ptr); return png_ptr->zlib_state; } /* 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) { png_bytep p = ps->previous_write_row; ps->previous_write_row = NULL; png_free(png_ptr, p); } # ifdef PNG_SELECT_FILTER_SUPPORTED if (ps->current_write_row != NULL) { png_bytep p = ps->current_write_row; ps->current_write_row = NULL; png_free(png_ptr, p); } if (ps->selector != NULL) { struct filter_selector *s = ps->selector; ps->selector = NULL; png_free(png_ptr, s); } # endif /* SELECT_FILTER */ # 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__base: The lowest valid value (encoded as 1). * ps__max: The highest valid value. * ps__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 #define pz_png_level_max 6 #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_ ## 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)) static png_int_32 pz_compression_setting(png_structrp png_ptr, png_uint_32 owner, int min, int max, int shift, png_int_32 value, int only_get, int unset) /* This is a support function for png_write_setting below. */ { png_zlib_statep ps; png_uint_32p psettings; /* The value is only required for a 'set', eliminate out-of-range values * first: */ if (!only_get && (value < min || value > max)) return PNG_EDOM; /* If setting a value make sure the state exists: */ if (!only_get) ps = get_zlib_state(png_ptr); else if (owner != 0U) /* ps may be NULL */ ps = png_ptr->zlib_state; else /* get and owner is 0U */ return 0; /* supported */ psettings = NULL; switch (owner) { png_int_32 res; case png_IDAT: if (ps != NULL) psettings = &ps->pz_IDAT; break; case png_iCCP: if (ps != NULL) psettings = &ps->pz_iCCP; break; case 0U: /* All the settings. At this point the 'get' case has returned 0 * above, the value has been checked and the paramter is 0, therefore * valid. Each of the following calls should succeed and it would be * reasonable to eliminate the PNG_FAILED tests in a world where * software engineers never made mistakes. */ res = pz_compression_setting(png_ptr, png_IDAT, min, max, shift, value, 0/*set*/, 1/*iff unset*/); if (PNG_FAILED(res)) return res; res = pz_compression_setting(png_ptr, png_iCCP, min, max, shift, value, 0/*set*/, 1/*iff unset*/); if (PNG_FAILED(res)) return res; /* The text settings are changed regardless of the customize support * because if WRITE_CUSTOMIZE_ZTXT_COMPRESSION is not supported the old * behavior was to use the WRITE_CUSTOMIZE_COMPRESSION setting. * * However, when we get png_zTXt directly (from png_write_setting) and * the support is not compiled in return PNG_ENOSYS. */ unset = 1; /* i.e. only if not already set */ # ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED case png_zTXt: case png_iTXt: # endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */ if (ps != NULL) psettings = &ps->pz_text; break; default: /* Return PNG_ENOSYS, not PNG_EINVAL, to support future addition of new * compressed chunks and the fact that zTXt and iTXt customization can * be disabled. */ return PNG_ENOSYS; } if (psettings == NULL) return PNG_UNSET; /* valid setting that is not set */ { png_uint_32 settings = *psettings; png_uint_32 mask = 0xFU << shift; /* Do not set it if 'only_get' was passed in or if 'unset' is true and the * setting is not currently set: */ if (!only_get && ((settings & mask) == 0U || !unset)) *psettings = (settings & ~mask) + ((png_uint_32)/*SAFE*/(value-min+1) << shift); settings &= mask; if (settings == 0U) return PNG_UNSET; else return (int)/*SAFE*/((settings >> shift)-1U) + min; } } #define compression_setting(pp, owner, setting, value, get)\ pz_compression_setting(pp, owner, pz_min(setting), pz_max(setting),\ pz_shift(setting), value, get, 0/*always*/) /* 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 if (data_size > 0U) { /* Prior to 1.7.0 libpng would shrink the windowBits even if the * application requested a particular value, so: */ unsigned int z_cinfo = data[0] >> 4; unsigned int half_z_window_size = 1U << (z_cinfo + 7); if (data_size <= half_z_window_size && z_cinfo > 0) { unsigned int tmp; do { half_z_window_size >>= 1; --z_cinfo; } while (z_cinfo > 0 && data_size <= half_z_window_size); data[0] = PNG_BYTE((z_cinfo << 4) + 0x8U); tmp = data[1] & 0xE0U; /* top three bits */ tmp += 31U - ((data[0] << 8) + tmp) % 31U; data[1] = PNG_BYTE(tmp); } } else NOT_REACHED; /* invalid data size (0) */ # undef png_ptr } static png_uint_32 pz_default_settings(png_uint_32 settings, const png_uint_32 owner, const png_alloc_size_t data_size, const unsigned int filters/*for IDAT*/) { int png_level, strategy, zlib_level, windowBits; /* The png 'level' parameter controls the defaults below. It uses the same * numbering scheme as the Zlib compression level except that -1 invokes the * set of options and, in some cases, libpng behavior of libpng 1.6 and * earlier. * * In the comments below reference is made to the differences beteen the * legacy compression sizes from libpng 1.6 and earlier and the result of * using the various options. These are quoted as an overall size change in * the compression of 147323 PNG test files. The set of test files is * slightly restricted because pre-1.7 versions of png_read_png leave random * bits into the final byte of a row which ends with a partial byte. This * affects the compression unpredictably so such files were omitted from the * measurements. */ if (!pz_isset(png_level, settings)) { png_level = PNG_DEFAULT_COMPRESSION_LEVEL; settings |= pz_encode(png_level, png_level); } 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 PNG_COMPRESSION_COMPAT: /* Legacy setting */ /* The pre-1.7 code used Z_FILTERED normally but uses * Z_DEFAULT_STRATEGY for palette or low-bit-depth images. * * In fact Z_DEFAULT_STRATEGY works best for filtered images as * well, however the change in results is small: * * Z_DEFAULT_STRATEGY: -0.1% * Z_FILTERED: +0.1% * * NOTE: this happened even if WRITE_FILTER was *not* supported. */ if (owner != png_IDAT || filters == PNG_FILTER_NONE) strategy = Z_DEFAULT_STRATEGY; else strategy = Z_FILTERED; break; case PNG_COMPRESSION_HIGH_SPEED: /* RLE is as fast as HUFFMAN_ONLY and can reduce size a lot in a few * cases. */ strategy = Z_RLE; break; default: /* For GCC */ case PNG_COMPRESSION_LOW: case PNG_COMPRESSION_MEDIUM: /* Z_FILTERED is almost as good as the default and can be * significantly faster. It biases the algorithm towards smaller * byte values. * * Using Z_DEFAULT_STRATEGY here, rather than Z_FILTERED, benefits * smaller 8 and 16-bit gray and larger 8 and 16-bit RGB images, * however the overall gain is only 0.1% because it is offset by * losses in larger 8-bit gray and alpha images. It is extremely * difficult to deduce a pattern other than biases in the test set * of images. * * Looking at the pattern of behavior with the 1.6 filter selection * algorithm (none of palette or low-bit-depth, else all) produces * results as follows: */ if (owner == png_IDAT) { if (filters == PNG_FILTER_NONE) strategy = Z_DEFAULT_STRATEGY; else strategy = Z_FILTERED; } else if (owner == png_iCCP) strategy = Z_DEFAULT_STRATEGY; /* TODO: investigate this, the observed behavior is suspicious: */ else /* text chunk */ strategy = Z_FILTERED; /* Always better for some reason */ break; case PNG_COMPRESSION_LOW_MEMORY: /* Reduce memory at all costs, speed doesn't matter. */ case PNG_COMPRESSION_HIGH_READ_SPEED: case PNG_COMPRESSION_HIGH: if (owner == png_IDAT || owner == png_iCCP) strategy = Z_DEFAULT_STRATEGY; else strategy = Z_FILTERED; 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. With libpng 1.6 the following results were obtained * using the full test set of files (including those with a partial * byte at the end of the row) and just varying the zlib level: * * LEVEL SIZE(bytes) CHANGE TIME(s) CHANGE METRIC * 9 2550246600 -1.19% 1972 +227% -77% * 8 2556675866 -0.94% 1215 +101% -59% * 7 2572685552 -0.32% 679 +12% -15% * 6 2581196708 0% 604 0% 0% * 5 2602831249 +0.84% 414 -30% +87% * 4 2625206800 +1.71% 358 -40% +153% * 3 2674752349 +3.62% 298 -50% +303% * 2 2716261483 +5.23% 262 -56% +537% * 1 2749875805 +6.53% 251 -57% +662% * 0 7174488347 202 -66% * * The CHANGE columns express the change in compressed size * (positive is an increase; a decrease in compression) and time * (positive is an increase; an increase in time) relative to level * 6. The METRIC column is a measure of the compression-per-second * relative to level 6; positive is an increase in * compression-per-second. * * The metric is derived by assuming the difference in time between * level 0 (which does no compression) and the level being * considered is spent doing the compression. (Reasonable, since * only the level changed). Just the inverse of the product of the * size and the time difference is a measure of compression per * second. It can be seen that time dominates the metric; * compression only varies slightly (under 8%) across the level * range. */ switch (png_level) { case PNG_COMPRESSION_COMPAT: zlib_level = Z_DEFAULT_COMPRESSION; /* NOTE: -1 */ break; case PNG_COMPRESSION_HIGH_SPEED: zlib_level = 1; break; default: /* For GCC */ case PNG_COMPRESSION_LOW: zlib_level = 3; break; case PNG_COMPRESSION_MEDIUM: zlib_level = 6; /* Old default! */ break; case PNG_COMPRESSION_LOW_MEMORY: case PNG_COMPRESSION_HIGH_READ_SPEED: case PNG_COMPRESSION_HIGH: zlib_level = 9; break; } 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 (png_level == PNG_COMPRESSION_COMPAT/* Legacy */) { /* This is the libpng16 calculation (it is wrong; a misunderstanding of * what zlib actually requires!) * * Using the code below with the legacy choice of Z_FILTERED or * Z_DEFAULT_STRATEGY increases the size of the test files by only * 0.04%, however the settings below considerably reduce the windowBits * used potentially benefitting read code a lot. * * NOTE: the algorithm below was determined by experiment and * observation with the same set of test files; there is some * considerable possibility that a different set might show different * results. Obtaining large, representative, test sets is both a * considerable amount of work and very error prone. [JB 20160518] */ windowBits = 15; if (data_size <= 16384U) { unsigned int half_window_size = 1U << (windowBits-1); while (data_size + 262U <= half_window_size) { half_window_size >>= 1; --windowBits; } } } /* The window size affects the memory used on both read and write but also * the time on write (but not normally read). Handle the low memory * requirement first: */ else if (zlib_level == Z_NO_COMPRESSION || png_level == PNG_COMPRESSION_LOW_MEMORY) 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. * * The only png_level that affects this decision is HIGH_SPEED, because * a smaller windowBits should speed up the search, however the code above * chose zlib_level based on this so ignore that consideration and just * use zlib_level below. */ 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 * benefit from looking at all the data: */ if (zlib_level < 4 && zlib_level != Z_DEFAULT_COMPRESSION/*-1: 6*/) 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. The * net effect with the test set of images is a very minor overall * improvement compared to the pre-1.7 calculation (data size + * 262). The benefit is less than 0.01%, however smaller window * sizes reduce the memory zlib has to allocate in the decoder. */ switch (zlib_level) { case 1: case 2: case 3: test_size = data_size / 8U; break; default: /* -1(Z_DEFAULT_COMPRESSION) == 6, 4..7 */ /* 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 * the only relevant png_level is LOW_MEMORY. * * The legacy setting is '8'; this is the level that Zlib defaults to because * 16-bit iAPX86 systems could not handle '9'. Because MAX_MEM_LEVEL is used * below this does not matter; zconf.h selects 8 or 9 as appropriate. * * In fact using '9' with the legacy settings increases the size of the test * set minutely; +0.007%. This is hardly significant; 0.007% of the test * images equals 10 images. (Nevertheless it is interesting, just as the * observation that decreasing windowBits can result in smaller compressed * sizes is interesting.) */ if (!pz_isset(memLevel, settings)) { int memLevel; switch (png_level) { case PNG_COMPRESSION_COMPAT: memLevel = 8; break; case PNG_COMPRESSION_LOW_MEMORY: memLevel = 1; break; default: memLevel = MAX_MEM_LEVEL/*from zconf.h*/; break; } settings |= pz_encode(memLevel, memLevel); } return settings; } /* This is used below to find the size of an image to pass to png_deflate_claim. * It returns 0 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) { /* 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_alloc_size_t rowbytes = png_ptr->zlib_state->write_row_size; /* 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) { const png_uint_32 h = png_ptr->height; 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 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 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 zowner == 0); { int ret; /* zlib return code */ unsigned int filters = 0U; png_uint_32 settings; switch (owner) { case png_IDAT: debug(data_size == 0U); data_size = png_image_size(png_ptr); if (data_size == 0U) data_size = PNG_SIZE_MAX; settings = ps->pz_IDAT; # ifdef PNG_WRITE_FILTER_SUPPORTED filters = ps->filter_mask; debug(filters != 0U); # else /* !WRITE_FILTER */ filters = PNG_FILTER_NONE; # endif /* !WRITE_FILTER */ 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, filters); /* 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->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; epentries + 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*igray < (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; png_uint_32 IDAT_size; /* 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*/); IDAT_size = png_ptr->IDAT_size; if (IDAT_size == 0U) { switch (pz_get(ps, IDAT, png_level, PNG_DEFAULT_COMPRESSION_LEVEL)) { case PNG_COMPRESSION_COMPAT: /* Legacy */ IDAT_size = 8192U; break; case PNG_COMPRESSION_LOW_MEMORY: case PNG_COMPRESSION_HIGH_SPEED: case PNG_COMPRESSION_LOW: /* png_compress uses PNG_ROW_BUFFER_SIZE buffers for the compressed * data. Optimize to allocate only one of these: */ IDAT_size = PNG_ROW_BUFFER_SIZE; break; default: case PNG_COMPRESSION_MEDIUM: IDAT_size = PNG_ZBUF_SIZE; break; case PNG_COMPRESSION_HIGH_READ_SPEED: /* Assume the reader reads partial IDAT chunks (pretty much a * requirement given that some PNG encoders produce just one IDAT) */ case PNG_COMPRESSION_HIGH: /* This doesn't control the amount of memory allocated unless the * PNG IDAT data really is this big. * * TODO: review handling out-of-memory from png_compress() by * flushing an IDAT. */ IDAT_size = PNG_UINT_31_MAX; break; } } /* 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 = 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, 0U); 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 * png_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; } #ifdef PNG_WRITE_FLUSH_SUPPORTED /* 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 pb) pa = pb, p = b; if (pa > abs(pc)) p = c; *paeth_row++ = 0xFFU & (x - p); } } row_bytes -= i; } } static void filter_block(png_const_bytep prev_row, png_bytep prev_pixels, png_const_bytep unfiltered_row, unsigned int row_bits, const unsigned int bpp, png_bytep sub_row, png_bytep up_row, png_bytep avg_row, png_bytep paeth_row) { const unsigned int row_bytes = row_bits >> 3; /* complete bytes */ if (bpp <= 8U) { /* There may be a partial byte at the end. */ if (row_bytes > 0) filter_block_singlebyte(row_bytes, sub_row, up_row, avg_row, paeth_row, unfiltered_row, prev_row, prev_pixels); /* The partial byte must be handled correctly here; both the previous row * value and the current value need to have non-present bits cleared. */ if ((row_bits & 7U) != 0) { const png_byte mask = PNG_BYTE(~(0xFFU >> (row_bits & 7U))); png_byte buffer[2]; buffer[0] = unfiltered_row[row_bytes] & mask; if (prev_row != NULL) buffer[1U] = prev_row[row_bytes] & mask; else buffer[1U] = 0U; filter_block_singlebyte(1U, sub_row == NULL ? NULL : sub_row+row_bytes, up_row == NULL ? NULL : up_row+row_bytes, avg_row == NULL ? NULL : avg_row+row_bytes, paeth_row == NULL ? NULL : paeth_row+row_bytes, buffer, buffer+1U, prev_pixels); } } else filter_block_multibyte(row_bytes, bpp >> 3, sub_row, up_row, avg_row, paeth_row, unfiltered_row, prev_row, prev_pixels); } static void filter_row(png_structrp png_ptr, png_const_bytep prev_row, png_bytep prev_pixels, png_const_bytep unfiltered_row, unsigned int row_bits, unsigned int bpp, unsigned int filter, int start_of_row, int flush) { /* filters_to_try identifies a single filter and it is not PNG_FILTER_NONE. */ png_byte filtered_row[PNG_ROW_BUFFER_SIZE]; affirm((row_bits+7U) >> 3 <= PNG_ROW_BUFFER_SIZE && filter >= PNG_FILTER_VALUE_SUB && filter <= PNG_FILTER_VALUE_PAETH); debug((row_bits % bpp) == 0U); filter_block(prev_row, prev_pixels, unfiltered_row, row_bits, bpp, filter == PNG_FILTER_VALUE_SUB ? filtered_row : NULL, filter == PNG_FILTER_VALUE_UP ? filtered_row : NULL, filter == PNG_FILTER_VALUE_AVG ? filtered_row : NULL, filter == PNG_FILTER_VALUE_PAETH ? filtered_row : NULL); write_filtered_row(png_ptr, filtered_row, (row_bits+7U)>>3, start_of_row ? filter : PNG_FILTER_VALUE_LAST, flush); } /* Allow the application to select one or more row filters to use. */ static png_int_32 set_filter(png_zlib_statep ps, unsigned int filtersIn) { /* 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. * * The argument to this routine is actually an (int), but conversion to * (unsigned int) is safe because it leaves the top bits set which results in * PNG_EDOM below. */ if (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 PNG_BIC_MASK here. */ if ((filtersIn & PNG_BIC_MASK(PNG_ALL_FILTERS)) == 0U) { # ifndef PNG_SELECT_FILTER_SUPPORTED filtersIn &= -filtersIn; /* Use lowest set bit */ # endif /* !SELECT_FILTER */ return ps->filter_mask = filtersIn & PNG_ALL_FILTERS; } else /* Out-of-range filtersIn: */ return PNG_EDOM; } #endif /* WRITE_FILTER */ #ifdef PNG_WRITE_FILTER_SUPPORTED void /* PRIVATE */ png_write_start_IDAT(png_structrp png_ptr) { png_zlib_statep ps = get_zlib_state(png_ptr); /* 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); /* This sets the buffer limits and write_row_size, which is used below. */ png_zlib_state_set_buffer_limits(png_ptr, ps); if (ps->filter_mask == 0) { # ifdef PNG_SELECT_FILTER_SUPPORTED /* Now default the filter mask if it hasn't been set already: */ int png_level = pz_get(ps, IDAT, png_level, PNG_DEFAULT_COMPRESSION_LEVEL); /* If the bit depth is less than 8, so pixels are not byte aligned, PNG * filtering hardly ever helps because there is no correlation between * the bytes on which the filter works and the actual pixel values. * Note that GIF is a whole lot better at this because it uses LZW to * compress a bit-stream, not a byte stream as in the deflate * implementation of LZ77. * * If the row size is less than 256 bytes filter selection algorithms * are flakey because the restricted range of codes in each row can * lead to poor selection of filters, particularly if the bytes in the * image are themselves limited. (This happens when a low bit-depth * image is encoded with 8-bit channels.) * * By experiment with the test set of images the breakpoint between * not filtering and filtering based on which gives best compression by * row size is as follows: * * NONE FAST ALL * PAL <=anything [even 8-bit palette images larger if filtered] * G<8 <=anything [low bit depth gray images] * G8 <=16 [+~1%] >16 * G16 <=128 [+~1%] >128 * GA8 <=64 [+~1%] >64 * GA16 <=anything [always better without filtering!] * RGB8 <=32 [+0-2%(1)] >32 * RGB16 <=1024 [+~1%] >1024 * RGBA8 <=64 [+~~1%] >64 * RGBA16 <=128 {+~0.5%] >128 * * (1) The largest 24-bit RGB image (RGB8) faired better, by 1.3%, * with 'fast' filters. This is assumed to be random. * * Aggregated across all color types and bit depths the breakpoint for * filtering is >16 bytes, but the size increase only exceeds 0.5% for * images with rows between 64 and 128 bytes, hence the choices below. * * Across all the test images that change (not including selecting just * the 'fast' filters by default) does not change the compressed size * significantly (+0.06% across the whole test set), however it does * substantially increase the number of images without filtering. * * Using just none and sub filters results in overall compressed sizes * somewhere around the geometric mean of no filtering and 'fast'. * * The image size also plays a part. Filtering is not an advantage for * images of size <= 512 bytes. This is also reflected below. * * NOTE: the libpng 1.6 (and earlier) algorithm seems to work * because it biases the byte codes in the output towards 0 and 255. * Zlib doesn't care what the codes are, but Huffman encoding always * benefits from a biased distribution and the filters themselves were * designed to produce values in this range. * * In a raw comparison with the legacy code selection of specific sets * of filters always increased the compressed size of the test set, as * follows: * * PNG_ALL_FILTERS: +0.26% * PNG_FAST_FILTERS: +1.9% * NONE+SUB: +5.8% * PNG_NO_FILTERS: +14% * * This mainly proves that a static selection of filters (without * considering the PNG format) is always worse than the legacy * algorithm below. * * NOTE: ps->filter_mask must be set to a mask value, not a simple * PNG_FILTER_VALUE_ number. */ if (ps->write_row_size == 0U /* row cannot be buffered */) ps->filter_mask = PNG_FILTER_NONE; else if (png_level == PNG_COMPRESSION_COMPAT/* Legacy */) { if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE || png_ptr->bit_depth < 8U) ps->filter_mask = PNG_FILTER_NONE; else ps->filter_mask = PNG_ALL_FILTERS; } /* NOTE: overall with the following size tests (row and image size) the * test set of images end up 0.06% larger, however some color types are * smaller and some larger; the differences are minute. If the test is * <=128 (which means <=129 bytes per row with the filter byte) the * resultant inclusion of 32x32 RGBA images results in significantly * increased compressed size. * * The test on png_level captures the following settings: * * PNG_COMPRESSION_LOW_MEMORY * PNG_COMPRESSION_HIGH_SPEED * PNG_COMPRESSION_HIGH_READ_SPEED * * NOTE: this relies on the exact values in png.h! */ else if (png_level <= PNG_COMPRESSION_HIGH_READ_SPEED || png_ptr->color_type == PNG_COLOR_TYPE_PALETTE || png_ptr->bit_depth < 8U || ps->write_row_size/*does not include filter*/ < 128U || png_image_size(png_ptr) <= 512U) ps->filter_mask = PNG_FILTER_NONE; /* ELSE: there are at least 128 bytes in every row and the pixels * are multiples of a byte. */ else switch (png_level) { default: /* For GCC */ case PNG_COMPRESSION_LOW: ps->filter_mask = PNG_FILTER_NONE+PNG_FILTER_SUB; break; case PNG_COMPRESSION_MEDIUM: ps->filter_mask = PNG_FAST_FILTERS; break; case PNG_COMPRESSION_HIGH: ps->filter_mask = PNG_ALL_FILTERS; break; } # else /* !SELECT_FILTER */ ps->filter_mask = PNG_FILTER_NONE; # endif /* !SELECT_FILTER */ } } static png_byte png_write_start_row(png_zlib_statep ps, int start_of_pass, int no_previous_row) /* 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. */ { unsigned int mask = ps->filter_mask; /* If we see a previous-row filter in mask and png_zlib_state::save_row is * still unset set it. This means that the first time a previous-row filter * is seen row-saving gets turned on. */ if (ps->save_row == SAVE_ROW_UNSET && (mask & PREVIOUS_ROW_FILTERS) != 0U) ps->save_row = SAVE_ROW_DEFAULT; if ((no_previous_row /* row not stored */ && !start_of_pass) || ps->save_row == SAVE_ROW_OFF /* disabled by app */ || ps->write_row_size == 0U /* row too large to buffer */) mask &= PNG_BIC_MASK(PREVIOUS_ROW_FILTERS); /* On the first row of a pass Paeth is equivalent to sub and up is equivalent * to none, so try to simplify the mask in in this case. */ else if (start_of_pass) { # define MATCH(flags) ((mask & (flags)) == (flags)) if (MATCH(PNG_FILTER_NONE|PNG_FILTER_UP)) mask &= PNG_BIC_MASK(PNG_FILTER_UP); if (MATCH(PNG_FILTER_SUB|PNG_FILTER_PAETH)) mask &= PNG_BIC_MASK(PNG_FILTER_PAETH); # undef MATCH } # ifdef PNG_SELECT_FILTER_SUPPORTED if ((mask & (mask-1U)) == 0U /* single bit set */ || ps->write_row_size == 0U /* row cannot be buffered */) # endif /* SELECT_FILTER */ /* 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: mask = PNG_FILTER_VALUE_NONE; break; case PNG_FILTER_SUB: mask = PNG_FILTER_VALUE_SUB; break; case PNG_FILTER_UP: mask = PNG_FILTER_VALUE_UP; break; case PNG_FILTER_AVG: mask = PNG_FILTER_VALUE_AVG; break; case PNG_FILTER_PAETH: mask = PNG_FILTER_VALUE_PAETH; break; } return ps->filters = PNG_BYTE(mask); } static png_bytep allocate_row(png_structrp png_ptr, png_const_bytep data, png_alloc_size_t size) /* Utility to allocate and save some row bytes. If the result is NULL the * allocation failed and the png_zlib_struct will have been updated to * prevent further allocation attempts. */ { const png_zlib_statep ps = png_ptr->zlib_state; png_bytep buffer; debug(ps->write_row_size > 0U); /* OOM is handled silently, as is the case where the row is too large to * buffer. */ buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, ps->write_row_size)); /* Setting write_row_size to 0 switches on the code for handling a row that * is too large to buffer. This will kick in next time round, i.e. on the * next row. */ if (buffer == NULL) ps->write_row_size = 0U; else memcpy(buffer, data, size); return buffer; } #endif /* WRITE_FILTER */ #ifdef PNG_SELECT_FILTER_SUPPORTED /* Bit set operations. Not in ANSI C-90 but commonly available in highly * optimized versions, hence the ifndef. These operations just work on bitsets * of size 256. The second argument (the code index) may be evaluated multiple * times. */ #ifndef PNG_CODE_SET /* Can be set in pngpriv.h */ typedef png_uint_32 png_codeset[8]; # define PNG_CODE_MASK(i) (((png_uint_32)1U) << ((i) & 0x1FU)) # define PNG_CODE_IS_SET(c,i) (((c)[(i) >> 5] & PNG_CODE_MASK(i))) # define PNG_CODE_SET(c,i) (((c)[(i) >> 5] |= PNG_CODE_MASK(i))) # define PNG_CODE_CLEAR(c,i) (((c)[(i) >> 5] &= ~PNG_CODE_MASK(i))) #endif /* !PNG_CODE_SET */ typedef struct filter_selector { /* Persistent filter selection information (stored across row boundaries). * A code is not considered if it last occured more than 'window' bytes ago. * The deflate algorithm means that 'window' cannot exceed 8453377, however * practical versions may be far less. When 'distance' reaches 'window' any * code where: * * distance - code_distance[code] > window * * at the end of a row 'code' is removed from codeset. Otherwise * (rearranging the above): * * distance - window <= code_distance[code] * * and so the distances of the still active codes can be reduced: * * code_distance[code] -= distance-window * distance = window * * This prevents any wrap of 'distance' on a row which is shorter than * 2^32-window. * * However when then row is 2^32-window or more bytes long (the row can be up * to just under 2^34 bytes long) this algorithm doesn't work; 'distance' * will overflow in the middle of the row and all codes are relevant. This * is handled below simply by reseting the set of present codes at the start * of the row and ignoring the overflow. */ unsigned int code_count; /* Number of distinct codes seen */ int png_level; /* Cached compression level */ png_uint_32 filter_select_max_width; /* The maximum number of pixels which can be fitted in the window without * filling the entire window (i.e. the maximum number that can be fitted * in (window-1) bytes). */ png_uint_32 sum_bias[PNG_FILTER_VALUE_LAST]; /* For each filter a measure of its cost in the filter sum calculation. * This allows filter selection based on the sum-of-absolute-dfferences * method to be biased to favour particular filters. There was no such * bias before 1.7 and the filter byte was ignored. */ png_uint_32 distance; /* Distance from beginning */ png_codeset codeset; /* Set of seen codes */ png_uint_32 code_distance[256]; /* Distance at last occurence */ } filter_selector; static const filter_selector * png_start_filter_select(png_zlib_statep ps, unsigned int bpp) { # define png_ptr ps_png_ptr(ps) filter_selector *fs = ps->selector; if (fs == NULL) { fs = png_voidcast(filter_selector*, png_malloc_base(png_ptr, sizeof *fs)); if (fs != NULL) { png_uint_32 window = ps->filter_select_window; fs->png_level = pz_get(ps, IDAT, png_level, PNG_DEFAULT_COMPRESSION_LEVEL); /* Delay initialize this here: */ if (window < 3U || window > PNG_FILTER_SELECT_WINDOW_MAX) ps->filter_select_window = window = PNG_FILTER_SELECT_WINDOW_MAX; fs->code_count = 0; switch (fs->png_level) { default: /* TODO: investigate other settings */ { unsigned int f; for (f=0; fsum_bias[f] = f; } ps->filter_select_threshold = 64U; /* 6bit RGB */ ps->filter_select_threshold2 = 50U; /* TODO: experiment! */ break; case PNG_COMPRESSION_COMPAT: /* Legacy */ memset(fs->sum_bias, 0U, sizeof fs->sum_bias); ps->filter_select_threshold = 1U; /* disabled */ ps->filter_select_threshold2 = 1U; break; } /* This is the maximum row width, in pixels, of a row which fits and * leaves 1 byte free in the window. For any bigger row filter * selection ignores the previous rows. */ fs->filter_select_max_width = ((window-2U/*filter+last byte*/)*8U)/bpp; fs->distance = 0U; memset(fs->codeset, 0U, sizeof fs->codeset); /* fs->code_distance is left uninitialized because fs->codeset says * whether or not each entry has been initialized. */ ps->selector = fs; } else ps->write_row_size = 0U; /* OOM */ } # undef png_ptr return fs; } typedef struct { /* Per-filter data. This remains separate from the above until the filter * selection has been made. It reflects the above however the codeset only * records codes present in this row. * * The 'sum' fields are the sum of the absolute deviation of each code from * 0, the algorithm from 1.6 and earlier. In other words: * * if (code >= 128) * sum += code; * else * sum += 256-code; */ unsigned int code_count; /* Number of distinct codes seen in row */ unsigned int new_code_count; /* Number of new codes seen in row */ png_uint_32 sum_low; /* Low 31 bits of code sum */ png_uint_32 sum_high; /* High 32 bits of code sum */ png_codeset codeset; /* Set of codes seen in this row */ png_uint_32 code_distance[256]; /* Distance at last occurence in this row */ } filter_data; static void filter_data_init(filter_data *fd, png_uint_32 distance, unsigned int filter, unsigned int code_is_set, png_uint_32 bias) { fd->code_count = 1U; fd->new_code_count = !code_is_set; fd->sum_low = bias; fd->sum_high = 0U; memset(&fd->codeset, 0U, sizeof fd->codeset); PNG_CODE_SET(fd->codeset, filter); fd->code_distance[filter] = distance; } static void add_code(const filter_selector *fs, filter_data *fd, png_uint_32 distance, unsigned int code) { if (!PNG_CODE_IS_SET(fd->codeset, code)) { PNG_CODE_SET(fd->codeset, code); ++(fd->code_count); fd->code_distance[code] = distance; if (!PNG_CODE_IS_SET(fs->codeset, code)) ++(fd->new_code_count); } { png_uint_32 low = fd->sum_low; if (code <= 128U) low += code; else low += 256U-code; /* Handle overflow into the top bit: */ if (low & 0x80000000U) fd->sum_low = low & 0x7FFFFFFFU, ++fd->sum_high; else fd->sum_low = low; } } static png_byte filter_data_select(png_zlib_statep ps, filter_data fd[PNG_FILTER_VALUE_LAST], unsigned int filter, png_uint_32 distance, png_uint_32 w) { # define png_ptr ps_png_ptr(ps) /* Choose how to do this depending on the row and window size. */ filter_selector *fs = ps->selector; png_uint_32 window = ps->filter_select_window; affirm(fs != NULL); /* Check the width against the maximum number of pixels that can fit in a * window without filling it: */ if (w > fs->filter_select_max_width) { /* The cache is not used */ fs->distance = 0U; /* for next row */ fs->code_count = 0U; memset(fs->codeset, 0U, sizeof fs->codeset); } else { /* Merge the two code sets, discounting codes that last occurred before * the start of the window. */ png_uint_32 adjust, code_count; unsigned int code; /* filter_selector::distance is the distance of the first byte in the row * (the filter byte), but 'distance' can wrap on long rows. The above * test is meant to exclude the wrap case by excluding any case where the * row has as many bytes as the window, so: */ affirm(distance > fs->distance && distance - fs->distance < window); /* Set 'adjust' to the current distance of the start of the window. I.e: * * +---------------+--------+ * | before window | window | future data * +---------------+--------+ * A A * | | * adjust + + distance * * If the window isn't full yet 'adjust' will be zero, otherwise all the * distances will be reduced by 'adjust' so that the first byte of the * window has distance 0. */ if (distance > window) adjust = distance-window; else adjust = 0; /* This may be decreased below if some old codes only occured before the * start of the window. */ code_count = fs->code_count + fd->new_code_count; for (code=0U; code<256U; ++code) { if (PNG_CODE_IS_SET(fd[filter].codeset, code)) { PNG_CODE_SET(fs->codeset, code); debug(fd[filter].code_distance[code] >= adjust); fs->code_distance[code] = fd[filter].code_distance[code] - adjust; } else if (PNG_CODE_IS_SET(fs->codeset, code) && adjust > 0) { /* The code did not occur in this row, the old distance may now be * outside the window (because adjust is non-zero). */ const png_uint_32 d = fs->code_distance[code]; if (d >= adjust) fs->code_distance[code] = d-adjust; else PNG_CODE_CLEAR(fs->codeset, code), --code_count; } } fs->code_count = code_count; fs->distance = distance - adjust; /* I.e. either distance or window! */ } return ps->filters = PNG_BYTE(filter); # undef png_ptr } static png_byte select_filter(png_zlib_statep ps, png_const_bytep row, png_const_bytep prev, unsigned int bpp, png_uint_32 width, int start_of_pass) /* Select a filter from the list provided by png_write_start_row. */ { png_byte filters = png_write_start_row(ps, start_of_pass, prev == NULL); # define png_ptr ps_png_ptr(ps) if (filters >= PNG_FILTER_NONE) /* multiple filters to test */ { const png_uint_32 max_pixels = ps->row_buffer_max_pixels; const png_uint_32 block_pixels = ps->row_buffer_max_aligned_pixels; const filter_selector *fs = ps->selector; png_uint_32 pixels_to_go = width; png_uint_32 distance; unsigned int bits_at_end = 0U; png_byte prev_pixels[4*2*2]; /* 2 pixels up to 4x2-bytes each */ filter_data fd[PNG_FILTER_VALUE_LAST]; debug((filters & (filters-1)) != 0U); /* Expect more than one bit! */ if (fs == NULL) { /* Delay initialize with a quiet OOM handler */ fs = png_start_filter_select(ps, bpp); if (fs == NULL) { ps->filters = PNG_FILTER_VALUE_NONE; return PNG_FILTER_VALUE_NONE; } } /* If PNG_FILTER_NONE is in the list check it first. */ if (filters & PNG_FILTER_NONE) { png_const_bytep rp = row; png_uint_32 w = width; distance = fs->distance; filter_data_init(fd+PNG_FILTER_VALUE_NONE, distance++, PNG_FILTER_VALUE_NONE, PNG_CODE_IS_SET(fs->codeset, PNG_FILTER_VALUE_NONE), fs->sum_bias[PNG_FILTER_VALUE_NONE]); if (bpp >= 8) /* complete bytes */ { const unsigned int bytes = bpp/8U; while (w > 0) { unsigned int b; for (b=0; b= ppb) { add_code(fs, fd+PNG_FILTER_VALUE_NONE, distance++, *rp++); w -= ppb; } if (w > 0) /* partial byte at end */ add_code(fs, fd+PNG_FILTER_VALUE_NONE, distance++, *rp & (0xFFU >> (w*bpp) /* zero unused bits */)); } /* For PNG data with a small number of codes it is worth skipping the * filtering because it almost always increases the code count * significantly. This is controlled by * png_zlib_state::filter_select_threshold and causes an early return * here. */ if (fd[PNG_FILTER_VALUE_NONE].new_code_count + fs->code_count < ps->filter_select_threshold) return filter_data_select(ps, fd, PNG_FILTER_VALUE_NONE, distance, width); } /* PNG_FILTER_NONE */ memset(prev_pixels, 0U, sizeof prev_pixels); distance = fs->distance; { unsigned int i; for (i=PNG_FILTER_VALUE_NONE+1U; icodeset, i), fs->sum_bias[i]); } ++distance; while (pixels_to_go || bits_at_end) { unsigned int bits, i; union { PNG_ROW_BUFFER_ALIGN_TYPE force_buffer_alignment; png_byte row[4][PNG_ROW_BUFFER_SIZE]; } filtered; union { PNG_ROW_BUFFER_ALIGN_TYPE force_buffer_alignment; png_byte byte; } last; if (pixels_to_go) { if (pixels_to_go > max_pixels) { /* Maintain alignment by consuming on block_pixels at once */ bits = block_pixels * bpp; pixels_to_go -= block_pixels; /* May be 0 */ } else { bits = pixels_to_go * bpp; bits_at_end = bits & 0x7U; bits -= bits_at_end; pixels_to_go = 0U; /* +bits_at_end */ } } else /* incomplete byte at the end of the pixel */ { /* Make sure the unused bits are cleared (to zero, although this is * an arbitrary choice): */ last.byte = PNG_BYTE(*row & ~(0xFFU >> bits_at_end)); row = &last.byte; bits = bits_at_end; bits_at_end = 0U; } filter_block(prev, prev_pixels, row, bits, bpp, filtered.row[0/*sub*/], filtered.row[1/*up*/], filtered.row[2/*avg*/], filtered.row[3/*Paeth*/]); /* A block of (bits+7)/8 bytes is now available to process. */ for (i=0; 8U*i < bits; ++i, ++distance) { unsigned int f; for (f=PNG_FILTER_VALUE_NONE+1U; f> 3; row += bits >> 3; } /* Now look at the candidate filters, including 'none' and select the * best. We know that 'none' increases the code count beyond the * threshold, so if the old code count is below the threshold and there is * a filter which does not increase the code count select it; doing so * should do no harm to the overall compression. */ if (fs->code_count < ps->filter_select_threshold) { unsigned int f, min_new_count = 257U, min_f = PNG_FILTER_VALUE_NONE; for (f=PNG_FILTER_VALUE_NONE+1U; fcode_count + min_new_count < ps->filter_select_threshold2) return filter_data_select(ps, fd, min_f, distance, width); } /* Now fall back to the libpng 1.6 and earlier algorithm. This favours * the filter which produces least deviation in the codes from 0. When * this works it does so by reducing the distribution of code values. The * filters implicitly encode the difference between a predictor based on * adjacent values, the assumption is that this will result in values * close to 0. */ { png_uint_32 high = -1; png_uint_32 low = -1; unsigned int min_f = 0 /*unset, but safe*/; unsigned int f; for (f=PNG_FILTER_VALUE_NONE; ffilters = filters; # undef png_ptr } #else /* !SELECT_FILTER */ /* Filter selection not being done, just call png_write_start_row: */ # define select_filter(ps, rp, pp, bpp, width, start_of_pass)\ png_write_start_row((ps), (start_of_pass), (pp) == NULL) #endif /* !SELECT_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. */ void /* PRIVATE */ png_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 png_const_bytep previous_row = ps->previous_write_row; # else /* !WRITE_FILTER */ /* These are constant in the no-filer case: */ 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 base_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; base_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); debug(pass >= 0 && pass < 7); # ifdef PNG_WRITE_INTERLACING_SUPPORTED if (png_ptr->do_interlace) { /* libpng is doing the interlace handling, the row number is * actually the row in the image. * * This overflows when the PNG height is such that the are no * rows in this pass. This does not matter; because there are * no rows the value doesn't get used. */ last_row_in_pass = PNG_ROW_FROM_PASS_ROW(last_row_in_pass-1U, pass); first_row_in_pass = PNG_PASS_START_ROW(pass); } else /* Application handles the interlace */ # endif /* WRITE_INTERLACING */ { /* The row does exist, so this works without checking the column * count. */ debug(last_row_in_pass > 0U); last_row_in_pass -= 1U; } if (pass == PNG_LAST_PASS(pixels_in_pass/*PNG width*/, height)) base_info_flags |= png_pass_last; /* Finally, adjust pixels_in_pass for the interlacing (skip the * final pass; it is full width). */ if (pass < 6) 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 unsigned int row_info_flags = base_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); const int flush = row_flush(ps, row_info_flags); png_const_bytep row = *rows; png_uint_32 pixels_to_go = pixels_in_pass; # ifdef PNG_WRITE_FILTER_SUPPORTED /* The filter can change each time round. Call png_write_start_row * to resolve any changes. Note that when this function is used to * do filter selection from png_write_png_data on the first row * png_write_start_row will get called twice. */ const png_byte filter = select_filter(ps, row, previous_row, bpp, pixels_in_pass, png_ptr->row_number == first_row_in_pass); 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->zlib_max_aligned_pixels : ps->row_buffer_max_aligned_pixels; /* The row handling uses png_compress_IDAT directly if there is no * filter to be applied, otherwise it uses filter_row. */ 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: */ if (pixels_to_go > 0) 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!) */ if (png_ptr->row_number != 0U && previous_row != NULL && SAVE_ROW(ps) && ps->previous_write_row != previous_row/*all rows skipped*/) { # ifdef PNG_SELECT_FILTER_SUPPORTED /* We might be able to avoid any copy. */ if (ps->current_write_row == previous_row) { png_bytep old = ps->previous_write_row; ps->previous_write_row = ps->current_write_row; ps->current_write_row = old; /* may be NULL */ } else # endif /* SELECT_FILTER */ if (ps->previous_write_row != NULL) memcpy(ps->previous_write_row, previous_row, png_calc_rowbytes(png_ptr, bpp, pixels_in_pass)); else ps->previous_write_row = allocate_row(png_ptr, previous_row, png_calc_rowbytes(png_ptr, bpp, pixels_in_pass)); } # endif /* WRITE_FILTER */ } #ifdef PNG_WRITE_FILTER_SUPPORTED /* 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 = ps->previous_write_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, (row_info_flags & png_pass_first_row) != 0, prev_row == NULL); /* If filter selection is required the filter will have at least one mask * bit set. */ # ifdef PNG_SELECT_FILTER_SUPPORTED if (ps->filters >= PNG_FILTER_NONE/*lowest mask bit*/) { /* If the entire row is passed in the input process it via * immediately, otherwise the row must be buffered for later * analysis. */ png_const_bytep row; if (x > 0 || (row_info_flags & png_row_end) == 0) { /* The row must be saved for later. */ png_bytep buffer = ps->current_write_row; /* png_write_start row should always check this: */ debug(ps->write_row_size > 0U); if (buffer != NULL) memcpy(buffer + png_calc_rowbytes(png_ptr, bpp, x), unfiltered_row, (row_bits + 7U) >> 3); else if (x == 0U) ps->current_write_row = buffer = allocate_row(png_ptr, unfiltered_row, (row_bits + 7U) >> 3); row = buffer; } else row = unfiltered_row; if (row != NULL) /* else out of memory */ { /* At row end, process the save buffer. */ if ((row_info_flags & png_row_end) != 0) png_write_png_rows(png_ptr, &row, 1U); /* Early return to skip the single-filter code */ return; } /* Caching the row failed, so process the row using the lowest set * filter. The allocation error should only ever happen at the * start of the row. If this goes wrong the output will have been * damaged. */ affirm(x == 0U); } # endif /* SELECT_FILTER */ /* prev_row is either NULL or the position in the previous row buffer */ 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 * write_previous_row may have garbage in a partial byte at the end as a * result of this memcpy. */ if (!(row_info_flags & png_pass_last_row) && SAVE_ROW(ps)) { if (prev_row != NULL) memcpy(prev_row, unfiltered_row, (row_bits + 7U) >> 3); /* NOTE: if the application sets png_zlib_state::save_row in a callback * it isn't possible to do the save until the next row. allocate_row * handles OOM silently by turning off the save. */ else if (x == 0) /* can allocate the save buffer */ ps->previous_write_row = allocate_row(png_ptr, unfiltered_row, (row_bits + 7U) >> 3); } } } #else /* !WRITE_FILTER */ void /* PRIVATE */ png_write_start_IDAT(png_structrp png_ptr) { png_zlib_statep ps = get_zlib_state(png_ptr); /* 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); /* This sets the buffer limits and write_row_size, which is used below. */ png_zlib_state_set_buffer_limits(png_ptr, ps); } 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); } #endif /* !WRITE_FILTER */ png_int_32 /* PRIVATE */ png_write_setting(png_structrp png_ptr, png_uint_32 setting, png_uint_32 parameter, png_int_32 value) { /* Caller checks the arguments for basic validity */ int only_get = (setting & PNG_SF_GET) != 0U; setting &= ~PNG_SF_GET; switch (setting) { /* Settings in png_struct: */ case PNG_SW_IDAT_size: if (parameter > 0 && parameter <= PNG_UINT_31_MAX) { if (!only_get) png_ptr->IDAT_size = parameter; return 0; /* set ok */ } else return PNG_EINVAL; /* Settings in zlib_state: */ case PNG_SW_COMPRESS_png_level: return compression_setting(png_ptr, parameter, png_level, value, only_get); # ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED case PNG_SW_COMPRESS_zlib_level: return compression_setting(png_ptr, parameter, level, value, only_get); case PNG_SW_COMPRESS_windowBits: return compression_setting(png_ptr, parameter, windowBits, value, only_get); case PNG_SW_COMPRESS_memLevel: return compression_setting(png_ptr, parameter, memLevel, value, only_get); case PNG_SW_COMPRESS_strategy: return compression_setting(png_ptr, parameter, strategy, value, only_get); case PNG_SW_COMPRESS_method: if (value != 8) /* Only supported method */ return PNG_EINVAL; return 8; /* old method */ # endif /* WRITE_CUSTOMIZE_COMPRESSION */ # ifdef PNG_WRITE_FILTER_SUPPORTED case PNG_SW_COMPRESS_filters: /* The method must match that in the IHDR: */ if (parameter == png_ptr->filter_method) { if (!only_get) return set_filter(get_zlib_state(png_ptr), value); else if (png_ptr->zlib_state != NULL && png_ptr->zlib_state->filter_mask != 0U/*unset*/) return png_ptr->zlib_state->filter_mask; else return PNG_UNSET; } else /* Invalid filter method */ return PNG_EINVAL; case PNG_SW_COMPRESS_row_buffers: /* New in 1.7.0: direct control of the buffering. */ switch (parameter) { case 0: if (!only_get) get_zlib_state(png_ptr)->save_row = SAVE_ROW_OFF; return 0; case 1: if (!only_get) get_zlib_state(png_ptr)->save_row = SAVE_ROW_ON; return 1; default: return PNG_ENOSYS; /* no support for bigger values */ } # endif /* WRITE_FILTER */ # ifdef PNG_WRITE_FLUSH_SUPPORTED case PNG_SW_FLUSH: /* Set the automatic flush interval or 0 to turn flushing off */ if (!only_get) get_zlib_state(png_ptr)->flush_dist = value <= 0 ? 0xEFFFFFFFU : (png_uint_32)/*SAFE*/value; return 0; # endif /* WRITE_FLUSH */ # ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED case PNG_SRW_CHECK_FOR_INVALID_INDEX: /* The 'enabled' value is a FORTRAN style three-state: */ if (value > 0) png_ptr->palette_index_check = PNG_PALETTE_CHECK_ON; else if (value < 0) png_ptr->palette_index_check = PNG_PALETTE_CHECK_OFF; else png_ptr->palette_index_check = PNG_PALETTE_CHECK_DEFAULT; return 0; # endif /* WRITE_CHECK_FOR_INVALID_INDEX */ # ifdef PNG_BENIGN_WRITE_ERRORS_SUPPORTED case PNG_SRW_ERROR_HANDLING: /* The parameter is a bit mask of what to set, the value is what to * set it to. PNG_IDAT_ERRORS is ignored on write. */ if (value >= PNG_IGNORE && value <= PNG_ERROR && parameter <= PNG_ALL_ERRORS) { if ((parameter & PNG_BENIGN_ERRORS) != 0U) png_ptr->benign_error_action = value & 0x3U; if ((parameter & PNG_APP_WARNINGS) != 0U) png_ptr->app_warning_action = value & 0x3U; if ((parameter & PNG_APP_ERRORS) != 0U) png_ptr->app_error_action = value & 0x3U; return 0; } return PNG_EINVAL; # endif /* BENIGN_WRITE_ERRORS */ default: return PNG_ENOSYS; /* not supported (whatever it is) */ } } #endif /* WRITE */