/* pngwutil.c - utilities to write a PNG file * * Last changed in libpng 1.7.0 [(PENDING RELEASE)] * Copyright (c) 1998-2015 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer * and license in png.h */ #include "pngpriv.h" #define PNG_SRC_FILE PNG_SRC_FILE_pngwutil #ifdef PNG_WRITE_SUPPORTED #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED /* Place a 32-bit number into a buffer in PNG byte order. We work * with unsigned numbers for convenience, although one supported * ancillary chunk uses signed (two's complement) numbers. */ void PNGAPI png_save_uint_32(png_bytep buf, png_uint_32 i) { buf[0] = PNG_BYTE(i >> 24); buf[1] = PNG_BYTE(i >> 16); buf[2] = PNG_BYTE(i >> 8); buf[3] = PNG_BYTE(i); } /* Place a 16-bit number into a buffer in PNG byte order. * The parameter is declared unsigned int, not png_uint_16, * just to avoid potential problems on pre-ANSI C compilers. */ void PNGAPI png_save_uint_16(png_bytep buf, unsigned int i) { buf[0] = PNG_BYTE(i >> 8); buf[1] = PNG_BYTE(i); } #endif /* WRITE_INT_FUNCTIONS */ /* Simple function to write the signature. If we have already written * the magic bytes of the signature, or more likely, the PNG stream is * being embedded into another stream and doesn't need its own signature, * we should call png_set_sig_bytes() to tell libpng how many of the * bytes have already been written. */ void PNGAPI png_write_sig(png_structrp png_ptr) { png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10}; #ifdef PNG_IO_STATE_SUPPORTED /* Inform the I/O callback that the signature is being written */ png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE; #endif /* Write the rest of the 8 byte signature */ png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes], (png_size_t)(8 - png_ptr->sig_bytes)); if (png_ptr->sig_bytes < 3) png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE; } /* Write the start of a PNG chunk. The type is the chunk type. * The total_length is the sum of the lengths of all the data you will be * passing in png_write_chunk_data(). */ static void png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name, png_uint_32 length) { png_byte buf[8]; #if defined(PNG_DEBUG) && (PNG_DEBUG > 0) PNG_CSTRING_FROM_CHUNK(buf, chunk_name); png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length); #endif if (png_ptr == NULL) return; #ifdef PNG_IO_STATE_SUPPORTED /* Inform the I/O callback that the chunk header is being written. * PNG_IO_CHUNK_HDR requires a single I/O call. */ png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR; #endif /* Write the length and the chunk name */ png_save_uint_32(buf, length); png_save_uint_32(buf + 4, chunk_name); png_write_data(png_ptr, buf, 8); /* Put the chunk name into png_ptr->chunk_name */ png_ptr->chunk_name = chunk_name; /* Reset the crc and run it over the chunk name */ png_reset_crc(png_ptr); png_calculate_crc(png_ptr, buf + 4, 4); #ifdef PNG_IO_STATE_SUPPORTED /* Inform the I/O callback that chunk data will (possibly) be written. * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls. */ png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA; #endif } void PNGAPI png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string, png_uint_32 length) { png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length); } /* Write the data of a PNG chunk started with png_write_chunk_header(). * Note that multiple calls to this function are allowed, and that the * sum of the lengths from these calls *must* add up to the total_length * given to png_write_chunk_header(). */ void PNGAPI png_write_chunk_data(png_structrp png_ptr, png_const_voidp data, png_size_t length) { /* Write the data, and run the CRC over it */ if (png_ptr == NULL) return; if (data != NULL && length > 0) { png_write_data(png_ptr, data, length); /* Update the CRC after writing the data, * in case the user I/O routine alters it. */ png_calculate_crc(png_ptr, data, length); } } /* Finish a chunk started with png_write_chunk_header(). */ void PNGAPI png_write_chunk_end(png_structrp png_ptr) { png_byte buf[4]; if (png_ptr == NULL) return; #ifdef PNG_IO_STATE_SUPPORTED /* Inform the I/O callback that the chunk CRC is being written. * PNG_IO_CHUNK_CRC requires a single I/O function call. */ png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC; #endif /* Write the crc in a single operation */ png_save_uint_32(buf, png_ptr->crc); png_write_data(png_ptr, buf, (png_size_t)4); } /* Write a PNG chunk all at once. The type is an array of ASCII characters * representing the chunk name. The array must be at least 4 bytes in * length, and does not need to be null terminated. To be safe, pass the * pre-defined chunk names here, and if you need a new one, define it * where the others are defined. The length is the length of the data. * All the data must be present. If that is not possible, use the * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end() * functions instead. */ static void png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name, png_const_voidp data, png_size_t length) { if (png_ptr == NULL) return; /* On 64 bit architectures 'length' may not fit in a png_uint_32. */ if (length > PNG_UINT_31_MAX) png_error(png_ptr, "length exceeds PNG maximum"); png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)/*SAFE*/length); png_write_chunk_data(png_ptr, data, length); png_write_chunk_end(png_ptr); } /* This is the API that calls the internal function above. */ void PNGAPI png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string, png_const_voidp data, png_size_t length) { png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data, length); } /* This is used below to find the size of an image to pass to png_deflate_claim, * so it only needs to be accurate if the size is less than 16384 bytes (the * point at which a lower LZ window size can be used.) */ static png_alloc_size_t png_image_size(png_const_structrp png_ptr) { /* Only return sizes up to the maximum of a png_uint_32; do this by limiting * the width and height used to 15 bits. */ const png_uint_32 h = png_ptr->height; const png_uint_32 w = png_ptr->width; const unsigned int pd = PNG_PIXEL_DEPTH(*png_ptr); png_alloc_size_t rowbytes = PNG_ROWBYTES(pd, w); if (rowbytes < 32768 && h < 32768) { if (png_ptr->interlaced != 0) { /* Interlacing makes the image larger because of the replication of * both the filter byte and the padding to a byte boundary. */ png_alloc_size_t cb_base; int pass; for (cb_base=0, pass=0; pass 0) cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass); } return cb_base; } else return (rowbytes+1) * h; } else return 0xffffffffU; } /* compression_buffer (new in 1.6.0) is just a linked list of temporary buffers. * From 1.6.0 it is retained in png_struct so that it will be correctly freed in * the event of a write error (previous implementations just leaked memory.) * * From 1.7.0 the size is fixed to the same as the (uncompressed) row buffer * size. This avoids allocating a large chunk of memory when compressing small * images. This type is also opaque outside this file. */ typedef struct png_compression_buffer { struct png_compression_buffer *next; png_byte output[PNG_ROW_BUFFER_SIZE]; } png_compression_buffer; #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED /* This is the code to hack the first two bytes of the deflate stream (the * deflate header) to correct the windowBits value to match the actual data * size. Note that the second argument is the *uncompressed* size but the * first argument is the *compressed* data (and it must be deflate * compressed.) */ static void optimize_cmf(png_bytep data, png_alloc_size_t data_size) { /* Optimize the CMF field in the zlib stream. The resultant zlib stream is * still compliant to the stream specification. */ if (data_size <= 16384) /* else windowBits must be 15 */ { unsigned int z_cmf = data[0]; /* zlib compression method and flags */ if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70) { unsigned int z_cinfo; unsigned int half_z_window_size; z_cinfo = z_cmf >> 4; half_z_window_size = 1U << (z_cinfo + 7); if (data_size <= half_z_window_size) /* else no change */ { unsigned int tmp; do { half_z_window_size >>= 1; --z_cinfo; } while (z_cinfo > 0 && data_size <= half_z_window_size); z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4); data[0] = png_check_byte(0/*TODO: fixme*/, z_cmf); tmp = data[1] & 0xe0; tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f; data[1] = png_check_byte(0/*TODO: fixme*/, tmp); } } } } #endif /* WRITE_OPTIMIZE_CMF */ /* Initialize the compressor for the appropriate type of compression. */ static int png_deflate_claim(png_structrp png_ptr, png_uint_32 owner, png_alloc_size_t data_size) { if (png_ptr->zowner != 0) { #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED) char msg[64]; PNG_STRING_FROM_CHUNK(msg, owner); msg[4] = ':'; msg[5] = ' '; PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner); /* So the message that results is " using zstream"; this is an * internal error, but is very useful for debugging. i18n requirements * are minimal. */ (void)png_safecat(msg, (sizeof msg), 10, " using zstream"); #endif #if PNG_RELEASE_BUILD png_warning(png_ptr, msg); /* Attempt sane error recovery */ if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */ { png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT"); return Z_STREAM_ERROR; } png_ptr->zowner = 0; #else png_error(png_ptr, msg); #endif } { int level = png_ptr->zlib_level; int method = png_ptr->zlib_method; int windowBits = png_ptr->zlib_window_bits; int memLevel = png_ptr->zlib_mem_level; int strategy; /* set below */ int ret; /* zlib return code */ if (owner == png_IDAT) { #ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0) strategy = png_ptr->zlib_strategy; else #endif /* WRITE_CUSTOMIZE_COMPRESSION */ #ifdef PNG_WRITE_FILTER_SUPPORTED if (png_ptr->filter_mask != PNG_FILTER_NONE) strategy = PNG_Z_DEFAULT_STRATEGY; else #endif /* WRITE_FILTER */ /* The default with no filters: */ strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY; } else { #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED level = png_ptr->zlib_text_level; method = png_ptr->zlib_text_method; windowBits = png_ptr->zlib_text_window_bits; memLevel = png_ptr->zlib_text_mem_level; strategy = png_ptr->zlib_text_strategy; #else /* If customization is not supported the values all come from the * IDAT values except for the strategy, which is fixed to the * default. (This is the pre-1.6.0 behavior too, although it was * implemented in a very different way.) */ strategy = Z_DEFAULT_STRATEGY; #endif } /* Adjust 'windowBits' down if larger than 'data_size'; to stop this * happening just pass 32768 as the data_size parameter. Notice that zlib * requires an extra 262 bytes in the window in addition to the data to be * able to see the whole of the data, so if data_size+262 takes us to the * next windowBits size we need to fix up the value later. (Because even * though deflate needs the extra window, inflate does not!) */ if (data_size <= 16384) { /* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to * work round a Microsoft Visual C misbehavior which, contrary to C-90, * widens the result of the following shift to 64-bits if (and, * apparently, only if) it is used in a test. */ unsigned int half_window_size = 1U << (windowBits-1); while (data_size + 262 <= half_window_size) { half_window_size >>= 1; --windowBits; } } /* Check against the previous initialized values, if any. */ if (png_ptr->zstream.state != NULL && (png_ptr->zlib_set_level != level || png_ptr->zlib_set_method != method || png_ptr->zlib_set_window_bits != windowBits || png_ptr->zlib_set_mem_level != memLevel || png_ptr->zlib_set_strategy != strategy)) { /* This shadows 'ret' deliberately; we ignore failures in deflateEnd: */ int ret_end = deflateEnd(&png_ptr->zstream); if (ret_end != Z_OK || png_ptr->zstream.state != NULL) { png_zstream_error(&png_ptr->zstream, ret_end); png_warning(png_ptr, png_ptr->zstream.msg); png_ptr->zstream.state = NULL; /* zlib error recovery */ } } /* For safety clear out the input and output pointers (currently zlib * doesn't use them on Init, but it might in the future). */ png_ptr->zstream.next_in = NULL; png_ptr->zstream.avail_in = 0; png_ptr->zstream.next_out = NULL; png_ptr->zstream.avail_out = 0; /* Now initialize if required, setting the new parameters, otherwise just * to a simple reset to the previous parameters. */ if (png_ptr->zstream.state != NULL) ret = deflateReset(&png_ptr->zstream); else ret = deflateInit2(&png_ptr->zstream, level, method, windowBits, memLevel, strategy); /* The return code is from either deflateReset or deflateInit2; they have * pretty much the same set of error codes. */ if (ret == Z_OK && png_ptr->zstream.state != NULL) png_ptr->zowner = owner; else png_zstream_error(&png_ptr->zstream, ret); return ret; } } /* Clean up (or trim) a linked list of compression buffers. */ void /* PRIVATE */ png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp) { png_compression_bufferp list = *listp; if (list != NULL) { *listp = NULL; do { png_compression_bufferp next = list->next; png_free(png_ptr, list); list = next; } while (list != NULL); } } /* Compress the given data given a compression buffer list. The passed in * z_stream must have already been claimed (if required) and the compression * buffer list pointer initialized to NULL or an existing list. * * The caller should use *data_len to work out how many buffers were used. * * All of zstream::next_in[input] is consumed if a success code is returned * (Z_OK or Z_STREAM_END if flush is Z_FINISH), otherwise it is not possible to * work out how much data was compressed. * * If *data_len exceeds PNG_UINT_MAX_31 after a successful deflate call the * function will return Z_MEM_ERROR. To allow compressed streams longer than * PNG_UINT_MAX_31 multiple calls can be made and *data_len can be reduced * between each call (see the IDAT handling for an example of this). * * '*ep' is a pointer to the pointer to the next buffer to use: * * *ep ---> pointer ---> png_compression_buffer * * It is updated before return so that it points to the pointer to the next * buffer after the one in use. I.e. it points to the 'next' member of the * current buffer. (Since 'next' is the first element this actually means that * it points at the current buffer.) * * The pointer 'pointer' will be updated if it is NULL, otherwise it is not * changed. Typically 'pointer' is png_struct::zbuffer_list initially and is * changed to the 'next' element of the last entry used. E.g: * * *ep(on entry) ............. (end) ........ *ep(on exit) * | | | * | | | * V +----V-----+ +-----V----+ +----------+ * png_struct::zbuffer_list --> | next --+--> | next --+--> | next | * | output[] | | output[] | | output[] | * +----------+ +----------+ +----------+ * [in use] [unused] * * To start compression do this: * * png_compression_bufferp end = &png_ptr->buffer_list; * * And pass in &end. */ static int png_compress( png_const_structp png_ptr, /* Just for png_malloc_base! */ z_stream *zs, /* next_{in,out} valid, avail_in is the input * data and avail_out is actually pass in the * parameter input_len. */ png_compression_bufferp **ep, /* Points to the pointer to the next buffer to * use. */ png_alloc_size_t input_len, /* Length of data to be compressed */ png_uint_32p data_len, /* Accumulated data size; the number of * compressed bytes is added to this. */ int flush) /* Flush parameter at end of input */ { png_compression_bufferp *end = *ep; /* Sanity checking: */ affirm(end != NULL && zs->avail_in == 0 && zs->next_in != NULL); debug(data_len != NULL && *data_len <= PNG_UINT_31_MAX); implies(zs->next_out == NULL, zs->avail_out == 0); for (;;) { /* OUTPUT: make sure some space is available: */ if (zs->avail_out == 0) { png_compression_bufferp next; /* There may already be an unused compression buffer in the list: */ if (*end != NULL) next = *end; else { next = png_voidcast(png_compression_bufferp, png_malloc_base(png_ptr, sizeof (png_compression_buffer))); /* Check for OOM: this is a recoverable error for non-critical * chunks, let the caller decide what to do: */ if (next == NULL) { *ep = end; return Z_MEM_ERROR; } next->next = NULL; /* initialize the buffer */ *end = next; } end = &next->next; zs->next_out = next->output; /* not initialized */ zs->avail_out = sizeof next->output; } /* INPUT: limit the deflate call input to ZLIB_IO_MAX: */ /* Adjust the input counters: */ { uInt avail_in = ZLIB_IO_MAX; if (avail_in > input_len) avail_in = (uInt)/*SAFE*/input_len; input_len -= avail_in; zs->avail_in = avail_in; } *data_len += zs->avail_out; /* maximum that can be produced */ /* Compress the data */ { int ret = deflate(zs, input_len > 0U ? Z_NO_FLUSH : flush); /* Claw back input data that was not consumed (because avail_in is * reset above every time round the loop). */ input_len += zs->avail_in; zs->avail_in = 0; /* safety */ /* Check for overflow of the data length limit. We can't get overflow * here because zs->avail_out never exceeds PNG_ROW_BUFFER_SIZE, and * that is under 16 bits. */ if ((*data_len -= zs->avail_out) > PNG_UINT_31_MAX) { zs->msg = "compressed data too long"; *ep = end; return Z_MEM_ERROR; } /* Check the error code: */ switch (ret) { case Z_OK: /* Check the reason for stopping: */ if (input_len == 0U && flush != Z_FINISH) { *ep = end; return Z_OK; } affirm(zs->avail_out == 0U); /* Allocate another buffer */ break; case Z_STREAM_END: affirm(input_len == 0U && flush == Z_FINISH); *ep = end; return Z_STREAM_END; case Z_BUF_ERROR: /* This means that we are doing a SYNC flush (not Z_NO_FLUSH and * not Z_FINISH) and that more buffer space is needed to complete * it. */ affirm(flush != Z_NO_FLUSH && flush != Z_FINISH && input_len == 0U && zs->avail_out == 0U); /* Allocate another buffer */ break; default: /* An error */ *ep = end; return ret; } } } } #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED /* includes iCCP */ /* Compress the block of data at the end of a chunk. This claims and releases * png_struct::z_stream. It returns the amount of data in the chunk list or * zero on error (a zlib stream always contains some bytes!) * * prefix_len is the amount of (uncompressed) data before the start of the * compressed data. The routine will return 0 if the total of the compressed * data and the prefix exceeds PNG_UINT_MAX_31. * * NOTE: this function may not return; it only returns 0 if * png_chunk_report(PNG_CHUNK_WRITE_ERROR) returns (not the default). */ static png_uint_32 png_compress_chunk_data(png_structp png_ptr, png_uint_32 chunk_name, png_uint_32 prefix_len, png_const_voidp input, png_alloc_size_t input_len) { /* To find the length of the output it is necessary to first compress the * input. The result is buffered rather than using the two-pass algorithm * that is used on the inflate side; deflate is assumed to be slower and a * PNG writer is assumed to have more memory available than a PNG reader. * * IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an * upper limit on the output size, but it is always bigger than the input * size so it is likely to be more efficient to use this linked-list * approach. */ { int ret = png_deflate_claim(png_ptr, chunk_name, input_len); /* This API is only ever used for non-critical chunks. * PNG_CHUNK_WRITE_ERROR can be ignored by the app and, if it is, the * write of the chunk will end up being skipped. */ if (ret != Z_OK) { png_chunk_report(png_ptr, png_ptr->zstream.msg, PNG_CHUNK_WRITE_ERROR); return 0U; } } /* The data compression function always returns so that we can clean up. */ png_ptr->zstream.next_in = PNGZ_INPUT_CAST(png_voidcast(const Bytef*,input)); { png_uint_32 output_len = prefix_len; png_compression_bufferp *end = &png_ptr->zbuffer_list; /* not required */ int ret = png_compress(png_ptr, &png_ptr->zstream, &end, input_len, &output_len, Z_FINISH); png_ptr->zstream.next_out = NULL; /* safety */ png_ptr->zstream.avail_out = 0; png_ptr->zstream.next_in = NULL; png_ptr->zstream.avail_in = 0; png_ptr->zowner = 0; /* release png_ptr::zstream */ /* Since Z_FINISH was passed as the flush parameter any result other than * Z_STREAM_END is an error. In any case in the event of an error free * the whole buffer list; the only expected error is Z_MEM_ERROR. */ if (ret != Z_STREAM_END) { png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list); png_zstream_error(&png_ptr->zstream, ret); png_chunk_report(png_ptr, png_ptr->zstream.msg, PNG_CHUNK_WRITE_ERROR); return 0U; } /* png_compress is meant to guarantee this on a successful return: */ affirm(output_len > prefix_len && output_len <= PNG_UINT_31_MAX); # ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED /* Fix up the deflate header, if required. */ optimize_cmf(png_ptr->zbuffer_list->output, input_len); # endif /* The returned result is just the length of the compressed data: */ return output_len - prefix_len; } } /* Write all the data produced by the above function; the caller must write the * prefix and chunk header. */ static void png_write_compressed_chunk_data(png_structp png_ptr, png_uint_32 output_len) { png_compression_bufferp next = png_ptr->zbuffer_list; for (;;) { png_uint_32 size = PNG_ROW_BUFFER_SIZE; /* If this affirm fails there is a bug in the calculation of * output_length above, or in the buffer_limit code in png_compress. */ affirm(next != NULL && output_len > 0); if (size > output_len) size = output_len; png_write_chunk_data(png_ptr, next->output, size); output_len -= size; if (output_len == 0) return; next = next->next; /* always wanted to write that */ } } #endif /* WRITE_COMPRESSED_TEXT */ #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \ defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED) /* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification, * and if invalid, correct the keyword rather than discarding the entire * chunk. The PNG 1.0 specification requires keywords 1-79 characters in * length, forbids leading or trailing whitespace, multiple internal spaces, * and the non-break space (0x80) from ISO 8859-1. Returns keyword length. * * The 'new_key' buffer must be at least 80 characters in size (for the keyword * plus a trailing '\0'). If this routine returns 0 then there was no keyword, * or a valid one could not be generated, and the caller must CHUNK_WRITE_ERROR. */ static unsigned int png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key) { png_const_charp orig_key = key; unsigned int key_len = 0; int bad_character = 0; int space = 1; png_debug(1, "in png_check_keyword"); if (key == NULL) { *new_key = 0; return 0; } while (*key && key_len < 79) { png_byte ch = (png_byte)(0xff & *key++); if ((ch > 32 && ch <= 126) || (ch >= 161 /*&& ch <= 255*/)) *new_key++ = ch, ++key_len, space = 0; else if (space == 0) { /* A space or an invalid character when one wasn't seen immediately * before; output just a space. */ *new_key++ = 32, ++key_len, space = 1; /* If the character was not a space then it is invalid. */ if (ch != 32) bad_character = ch; } else if (bad_character == 0) bad_character = ch; /* just skip it, record the first error */ } if (key_len > 0 && space != 0) /* trailing space */ { --key_len, --new_key; if (bad_character == 0) bad_character = 32; } /* Terminate the keyword */ *new_key = 0; if (key_len == 0) return 0; #ifdef PNG_WARNINGS_SUPPORTED /* Try to only output one warning per keyword: */ if (*key != 0) /* keyword too long */ png_app_warning(png_ptr, "keyword truncated"); else if (bad_character != 0) { PNG_WARNING_PARAMETERS(p) png_warning_parameter(p, 1, orig_key); png_warning_parameter_signed(p, 2, PNG_NUMBER_FORMAT_02x, bad_character); png_formatted_warning(png_ptr, p, "keyword \"@1\": bad character '0x@2'"); } #endif /* WARNINGS */ return key_len; } #endif /* WRITE_TEXT || WRITE_pCAL || WRITE_iCCP || WRITE_sPLT */ /* Write the IHDR chunk, and update the png_struct with the necessary * information. Note that the rest of this code depends upon this * information being correct. */ void /* PRIVATE */ png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height, int bit_depth, int color_type, int compression_type, int filter_method, int interlace_type) { png_byte buf[13]; /* Buffer to store the IHDR info */ png_debug(1, "in png_write_IHDR"); /* Check that we have valid input data from the application info */ switch (color_type) { case PNG_COLOR_TYPE_GRAY: switch (bit_depth) { case 1: case 2: case 4: case 8: #ifdef PNG_WRITE_16BIT_SUPPORTED case 16: #endif break; default: png_error(png_ptr, "Invalid bit depth for grayscale image"); } break; case PNG_COLOR_TYPE_RGB: #ifdef PNG_WRITE_16BIT_SUPPORTED if (bit_depth != 8 && bit_depth != 16) #else if (bit_depth != 8) #endif png_error(png_ptr, "Invalid bit depth for RGB image"); break; case PNG_COLOR_TYPE_PALETTE: switch (bit_depth) { case 1: case 2: case 4: case 8: break; default: png_error(png_ptr, "Invalid bit depth for paletted image"); } break; case PNG_COLOR_TYPE_GRAY_ALPHA: if (bit_depth != 8 && bit_depth != 16) png_error(png_ptr, "Invalid bit depth for grayscale+alpha image"); break; case PNG_COLOR_TYPE_RGB_ALPHA: #ifdef PNG_WRITE_16BIT_SUPPORTED if (bit_depth != 8 && bit_depth != 16) #else if (bit_depth != 8) #endif png_error(png_ptr, "Invalid bit depth for RGBA image"); break; default: png_error(png_ptr, "Invalid image color type specified"); } if (compression_type != PNG_COMPRESSION_TYPE_BASE) { png_app_error(png_ptr, "Invalid compression type specified"); compression_type = PNG_COMPRESSION_TYPE_BASE; } /* Write filter_method 64 (intrapixel differencing) only if * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and * 2. Libpng did not write a PNG signature (this filter_method is only * used in PNG datastreams that are embedded in MNG datastreams) and * 3. The application called png_permit_mng_features with a mask that * included PNG_FLAG_MNG_FILTER_64 and * 4. The filter_method is 64 and * 5. The color_type is RGB or RGBA */ if ( # ifdef PNG_MNG_FEATURES_SUPPORTED !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 && ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) && (color_type == PNG_COLOR_TYPE_RGB || color_type == PNG_COLOR_TYPE_RGB_ALPHA) && (filter_method == PNG_INTRAPIXEL_DIFFERENCING)) && # endif /* MNG_FEATURES */ filter_method != PNG_FILTER_TYPE_BASE) { png_app_error(png_ptr, "Invalid filter type specified"); filter_method = PNG_FILTER_TYPE_BASE; } if (interlace_type != PNG_INTERLACE_NONE && interlace_type != PNG_INTERLACE_ADAM7) { png_app_error(png_ptr, "Invalid interlace type specified"); interlace_type = PNG_INTERLACE_ADAM7; } /* Save the relevant information */ png_ptr->bit_depth = png_check_byte(png_ptr, bit_depth); png_ptr->color_type = png_check_byte(png_ptr, color_type); png_ptr->interlaced = png_check_byte(png_ptr, interlace_type); png_ptr->filter_method = png_check_byte(png_ptr, filter_method); png_ptr->compression_type = png_check_byte(png_ptr, compression_type); png_ptr->width = width; png_ptr->height = height; /* Pack the header information into the buffer */ png_save_uint_32(buf, width); png_save_uint_32(buf + 4, height); buf[8] = png_check_byte(png_ptr, bit_depth); buf[9] = png_check_byte(png_ptr, color_type); buf[10] = png_check_byte(png_ptr, compression_type); buf[11] = png_check_byte(png_ptr, filter_method); buf[12] = png_check_byte(png_ptr, interlace_type); /* Write the chunk */ png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13); # ifdef PNG_WRITE_FILTER_SUPPORTED /* TODO: review this setting */ if (png_ptr->filter_mask == PNG_NO_FILTERS /* not yet set */) { if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE || png_ptr->bit_depth < 8) png_ptr->filter_mask = PNG_FILTER_NONE; else png_ptr->filter_mask = PNG_ALL_FILTERS; } # endif png_ptr->mode |= PNG_HAVE_IHDR; } /* Write the palette. We are careful not to trust png_color to be in the * correct order for PNG, so people can redefine it to any convenient * structure. */ void /* PRIVATE */ png_write_PLTE(png_structrp png_ptr, png_const_colorp palette, unsigned int num_pal) { png_uint_32 max_palette_length, i; png_const_colorp pal_ptr; png_byte buf[3]; png_debug(1, "in png_write_PLTE"); max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ? (1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH; if (( # ifdef PNG_MNG_FEATURES_SUPPORTED (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 && # endif /* MNG_FEATURES */ num_pal == 0) || num_pal > max_palette_length) { if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { png_error(png_ptr, "Invalid number of colors in palette"); } else { png_warning(png_ptr, "Invalid number of colors in palette"); return; } } if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) { png_warning(png_ptr, "Ignoring request to write a PLTE chunk in grayscale PNG"); return; } png_ptr->num_palette = png_check_bits(png_ptr, num_pal, 9); png_debug1(3, "num_palette = %d", png_ptr->num_palette); png_write_chunk_header(png_ptr, png_PLTE, num_pal * 3U); for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++) { buf[0] = pal_ptr->red; buf[1] = pal_ptr->green; buf[2] = pal_ptr->blue; png_write_chunk_data(png_ptr, buf, 3U); } png_write_chunk_end(png_ptr); png_ptr->mode |= PNG_HAVE_PLTE; } /* Write an IEND chunk */ void /* PRIVATE */ png_write_IEND(png_structrp png_ptr) { png_debug(1, "in png_write_IEND"); png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0); png_ptr->mode |= PNG_HAVE_IEND; } #if defined(PNG_WRITE_gAMA_SUPPORTED) || defined(PNG_WRITE_cHRM_SUPPORTED) static int png_save_int_31(png_structrp png_ptr, png_bytep buf, png_int_32 i) /* Save a signed value as a PNG unsigned value; the argument is required to * be in the range 0..0x7FFFFFFFU. If not a *warning* is produced and false * is returned. Because this is only called from png_write_cHRM_fixed and * png_write_gAMA_fixed below this is safe (we don't need either chunk, * particularly if the value is bogus.) * * The warning is png_app_error; it may return if the app tells it to but the * app can have it error out. JB 20150821: I believe the checking in png.c * actually makes this error impossible, but this is safe. */ { #ifndef __COVERITY__ if (i >= 0 && i <= 0x7FFFFFFF) #else /* Supress bogus Coverity complaint */ if (i >= 0) #endif { png_save_uint_32(buf, (png_uint_32)/*SAFE*/i); return 1; } else { png_chunk_report(png_ptr, "negative value in cHRM or gAMA", PNG_CHUNK_WRITE_ERROR); return 0; } } #endif /* WRITE_gAMA || WRITE_cHRM */ #ifdef PNG_WRITE_gAMA_SUPPORTED /* Write a gAMA chunk */ void /* PRIVATE */ png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma) { png_byte buf[4]; png_debug(1, "in png_write_gAMA"); /* file_gamma is saved in 1/100,000ths */ if (png_save_int_31(png_ptr, buf, file_gamma)) png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4); } #endif #ifdef PNG_WRITE_sRGB_SUPPORTED /* Write a sRGB chunk */ void /* PRIVATE */ png_write_sRGB(png_structrp png_ptr, int srgb_intent) { png_byte buf[1]; png_debug(1, "in png_write_sRGB"); if (srgb_intent >= PNG_sRGB_INTENT_LAST) png_chunk_report(png_ptr, "Invalid sRGB rendering intent specified", PNG_CHUNK_WRITE_ERROR); buf[0] = png_check_byte(png_ptr, srgb_intent); png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1); } #endif #ifdef PNG_WRITE_iCCP_SUPPORTED /* Write an iCCP chunk */ void /* PRIVATE */ png_write_iCCP(png_structrp png_ptr, png_const_charp name, png_const_voidp profile) { png_uint_32 name_len, output_len; png_uint_32 profile_len; png_byte new_name[81]; /* 1 byte for the compression byte */ png_debug(1, "in png_write_iCCP"); affirm(profile != NULL); profile_len = png_get_uint_32(profile); name_len = png_check_keyword(png_ptr, name, new_name); if (name_len == 0) { png_chunk_report(png_ptr, "iCCP: invalid keyword", PNG_CHUNK_WRITE_ERROR); return; } ++name_len; /* trailing '\0' */ new_name[name_len++] = PNG_COMPRESSION_TYPE_BASE; output_len = png_compress_chunk_data(png_ptr, png_iCCP, name_len, profile, profile_len); if (output_len > 0) { png_write_chunk_header(png_ptr, png_iCCP, name_len+output_len); png_write_chunk_data(png_ptr, new_name, name_len); png_write_compressed_chunk_data(png_ptr, output_len); png_write_chunk_end(png_ptr); } } #endif #ifdef PNG_WRITE_sPLT_SUPPORTED /* Write a sPLT chunk */ void /* PRIVATE */ png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette) { png_uint_32 name_len; png_byte new_name[80]; png_byte entrybuf[10]; png_size_t entry_size = (spalette->depth == 8 ? 6 : 10); png_size_t palette_size = entry_size * spalette->nentries; png_sPLT_entryp ep; png_debug(1, "in png_write_sPLT"); name_len = png_check_keyword(png_ptr, spalette->name, new_name); if (name_len == 0) png_error(png_ptr, "sPLT: invalid keyword"); /* Make sure we include the NULL after the name */ png_write_chunk_header(png_ptr, png_sPLT, (png_uint_32)(name_len + 2 + palette_size)); png_write_chunk_data(png_ptr, new_name, name_len + 1); png_write_chunk_data(png_ptr, &spalette->depth, 1); /* Loop through each palette entry, writing appropriately */ for (ep = spalette->entries; 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); if ((unsigned int)/*SAFE*/num_trans > png_ptr->num_palette) { /* This is an error which can only be reliably detected late. */ png_app_error(png_ptr, "Invalid number of transparent colors specified"); return; } { # 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) { png_uint_32 output_len; unsigned int key_len; png_byte new_key[81]; png_debug(1, "in png_write_zTXt"); if (compression != PNG_TEXT_COMPRESSION_zTXt) png_app_warning(png_ptr, "zTXt: invalid compression type ignored"); key_len = png_check_keyword(png_ptr, key, new_key); if (key_len == 0) { png_chunk_report(png_ptr, "zTXt: invalid keyword", PNG_CHUNK_WRITE_ERROR); return; } /* Add the compression method and 1 for the keyword separator. */ ++key_len; new_key[key_len++] = PNG_COMPRESSION_TYPE_BASE; output_len = png_compress_chunk_data(png_ptr, png_zTXt, key_len, text, strlen(text)); if (output_len > 0) { png_write_chunk_header(png_ptr, png_zTXt, key_len+output_len); png_write_chunk_data(png_ptr, new_key, key_len); png_write_compressed_chunk_data(png_ptr, output_len); png_write_chunk_end(png_ptr); } /* else chunk report already issued and ignored */ } #endif #ifdef PNG_WRITE_iTXt_SUPPORTED /* Write an iTXt chunk */ void /* PRIVATE */ png_write_iTXt(png_structrp png_ptr, int compression, png_const_charp key, png_const_charp lang, png_const_charp lang_key, png_const_charp text) { png_uint_32 key_len, prefix_len, data_len; png_size_t lang_len, lang_key_len, text_len; png_byte new_key[82]; /* 80 bytes for the key, 2 byte compression info */ png_debug(1, "in png_write_iTXt"); key_len = png_check_keyword(png_ptr, key, new_key); if (key_len == 0) { png_chunk_report(png_ptr, "iTXt: invalid keyword", PNG_CHUNK_WRITE_ERROR); return; } debug(new_key[key_len] == 0); ++key_len; /* terminating 0 added by png_check_keyword */ /* Set the compression flag */ switch (compression) { case PNG_ITXT_COMPRESSION_NONE: case PNG_TEXT_COMPRESSION_NONE: compression = new_key[key_len++] = 0; /* no compression */ break; case PNG_TEXT_COMPRESSION_zTXt: case PNG_ITXT_COMPRESSION_zTXt: compression = new_key[key_len++] = 1; /* compressed */ break; default: png_chunk_report(png_ptr, "iTXt: invalid compression", PNG_CHUNK_WRITE_ERROR); return; } new_key[key_len++] = PNG_COMPRESSION_TYPE_BASE; /* We leave it to the application to meet PNG-1.0 requirements on the * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of * any non-Latin-1 characters except for NEWLINE (yes, this is really weird * in an 'international' text string. ISO PNG, however, specifies that the * text is UTF-8 and this *IS NOT YET CHECKED*, so invalid sequences may be * present. * * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG. * * TODO: validate the language tag correctly (see the spec.) */ if (lang == NULL) lang = ""; /* empty language is valid */ lang_len = strlen(lang)+1U; if (lang_key == NULL) lang_key = ""; /* may be empty */ lang_key_len = strlen(lang_key)+1U; if (text == NULL) text = ""; /* may be empty */ if (lang_len > PNG_UINT_31_MAX-key_len || lang_key_len > PNG_UINT_31_MAX-key_len-lang_len) { png_chunk_report(png_ptr, "iTXt: prefix too long", PNG_CHUNK_WRITE_ERROR); return; } prefix_len = (png_uint_32)/*SAFE*/(key_len+lang_len+lang_key_len); text_len = strlen(text); /* no trailing '\0' */ if (compression != 0) { data_len = png_compress_chunk_data(png_ptr, png_iTXt, prefix_len, text, text_len); if (data_len == 0) return; /* chunk report already issued and ignored */ debug(data_len <= PNG_UINT_31_MAX-prefix_len); } else { if (text_len > PNG_UINT_31_MAX-prefix_len) { png_chunk_report(png_ptr, "iTXt: text too long", PNG_CHUNK_WRITE_ERROR); return; } data_len = (png_uint_32)/*SAFE*/text_len; } png_write_chunk_header(png_ptr, png_iTXt, prefix_len+data_len); png_write_chunk_data(png_ptr, new_key, key_len); png_write_chunk_data(png_ptr, lang, lang_len); png_write_chunk_data(png_ptr, lang_key, lang_key_len); if (compression != 0) png_write_compressed_chunk_data(png_ptr, data_len); else png_write_chunk_data(png_ptr, text, data_len); png_write_chunk_end(png_ptr); } #endif /* WRITE_iTXt */ #if defined(PNG_WRITE_oFFs_SUPPORTED) ||\ defined(PNG_WRITE_pCAL_SUPPORTED) /* PNG signed integers are saved in 32-bit 2's complement format. ANSI C-90 * defines a cast of a signed integer to an unsigned integer either to preserve * the value, if it is positive, or to calculate: * * (UNSIGNED_MAX+1) + integer * * Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the * negative integral value is added the result will be an unsigned value * correspnding to the 2's complement representation. */ static int save_int_32(png_structrp png_ptr, png_bytep buf, png_int_32 j) { png_uint_32 i = 0xFFFFFFFFU & (png_uint_32)/*SAFE & CORRECT*/j; if (i != 0x80000000U/*value not permitted*/) { png_save_uint_32(buf, i); return 1; } else { png_chunk_report(png_ptr, "invalid value in oFFS or pCAL", PNG_CHUNK_WRITE_ERROR); return 0; } } #endif /* WRITE_oFFs || WRITE_pCAL */ #ifdef PNG_WRITE_oFFs_SUPPORTED /* Write the oFFs chunk */ void /* PRIVATE */ png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset, int unit_type) { png_byte buf[9]; png_debug(1, "in png_write_oFFs"); if (unit_type >= PNG_OFFSET_LAST) png_warning(png_ptr, "Unrecognized unit type for oFFs chunk"); if (save_int_32(png_ptr, buf, x_offset) && save_int_32(png_ptr, buf + 4, y_offset)) { /* unit type is 0 or 1, this has been checked already so the following * is safe: */ buf[8] = unit_type != 0; png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9); } } #endif /* WRITE_oFFs */ #ifdef PNG_WRITE_pCAL_SUPPORTED /* Write the pCAL chunk (described in the PNG extensions document) */ void /* PRIVATE */ png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0, png_int_32 X1, int type, int nparams, png_const_charp units, png_charpp params) { png_uint_32 purpose_len; size_t units_len; png_byte buf[10]; png_byte new_purpose[80]; png_debug1(1, "in png_write_pCAL (%d parameters)", nparams); if (type >= PNG_EQUATION_LAST) png_error(png_ptr, "Unrecognized equation type for pCAL chunk"); purpose_len = png_check_keyword(png_ptr, purpose, new_purpose); if (purpose_len == 0) png_error(png_ptr, "pCAL: invalid keyword"); ++purpose_len; /* terminator */ png_debug1(3, "pCAL purpose length = %d", (int)purpose_len); units_len = strlen(units) + (nparams == 0 ? 0 : 1); png_debug1(3, "pCAL units length = %d", (int)units_len); if (save_int_32(png_ptr, buf, X0) && save_int_32(png_ptr, buf + 4, X1)) { png_size_tp params_len = png_voidcast(png_size_tp, png_malloc(png_ptr, nparams * sizeof (png_size_t))); int i; size_t total_len = purpose_len + units_len + 10; /* Find the length of each parameter, making sure we don't count the * null terminator for the last parameter. */ for (i = 0; i < nparams; i++) { params_len[i] = strlen(params[i]) + (i == nparams - 1 ? 0 : 1); png_debug2(3, "pCAL parameter %d length = %lu", i, (unsigned long)params_len[i]); total_len += params_len[i]; } png_debug1(3, "pCAL total length = %d", (int)total_len); png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len); png_write_chunk_data(png_ptr, new_purpose, purpose_len); buf[8] = png_check_byte(png_ptr, type); buf[9] = png_check_byte(png_ptr, nparams); png_write_chunk_data(png_ptr, buf, (png_size_t)10); png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len); for (i = 0; i < nparams; i++) png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]); png_free(png_ptr, params_len); png_write_chunk_end(png_ptr); } } #endif /* WRITE_pCAL */ #ifdef PNG_WRITE_sCAL_SUPPORTED /* Write the sCAL chunk */ void /* PRIVATE */ png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width, png_const_charp height) { png_byte buf[64]; png_size_t wlen, hlen, total_len; png_debug(1, "in png_write_sCAL_s"); wlen = strlen(width); hlen = strlen(height); total_len = wlen + hlen + 2; if (total_len > 64) { png_warning(png_ptr, "Can't write sCAL (buffer too small)"); return; } buf[0] = png_check_byte(png_ptr, unit); memcpy(buf + 1, width, wlen + 1); /* Append the '\0' here */ memcpy(buf + wlen + 2, height, hlen); /* Do NOT append the '\0' here */ png_debug1(3, "sCAL total length = %u", (unsigned int)total_len); png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len); } #endif #ifdef PNG_WRITE_pHYs_SUPPORTED /* Write the pHYs chunk */ void /* PRIVATE */ png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit, int unit_type) { png_byte buf[9]; png_debug(1, "in png_write_pHYs"); if (unit_type >= PNG_RESOLUTION_LAST) png_warning(png_ptr, "Unrecognized unit type for pHYs chunk"); png_save_uint_32(buf, x_pixels_per_unit); png_save_uint_32(buf + 4, y_pixels_per_unit); buf[8] = png_check_byte(png_ptr, unit_type); png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9); } #endif #ifdef PNG_WRITE_tIME_SUPPORTED /* Write the tIME chunk. Use either png_convert_from_struct_tm() * or png_convert_from_time_t(), or fill in the structure yourself. */ void /* PRIVATE */ png_write_tIME(png_structrp png_ptr, png_const_timep mod_time) { png_byte buf[7]; png_debug(1, "in png_write_tIME"); if (mod_time->month > 12 || mod_time->month < 1 || mod_time->day > 31 || mod_time->day < 1 || mod_time->hour > 23 || mod_time->second > 60) { png_warning(png_ptr, "Invalid time specified for tIME chunk"); return; } png_save_uint_16(buf, mod_time->year); buf[2] = mod_time->month; buf[3] = mod_time->day; buf[4] = mod_time->hour; buf[5] = mod_time->minute; buf[6] = mod_time->second; png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7); } #endif /* This is similar to png_text_compress, above, except that it does not require * all of the data at once and, instead of buffering the compressed result, * writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out * because it calls the write interface. As a result it does its own error * reporting and does not return an error code. In the event of error it will * just call png_error. The input data length may exceed 32-bits. The 'flush' * parameter is exactly the same as that to deflate, with the following * meanings: * * Z_NO_FLUSH: normal incremental output of compressed data * Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush * Z_FINISH: this is the end of the input, do a Z_FINISH and clean up * * The routine manages the acquire and release of the png_ptr->zstream by * checking and (at the end) clearing png_ptr->zowner; it does some sanity * checks on the 'mode' flags while doing this. */ static void png_start_IDAT(png_structrp png_ptr) { /* It is a terminal error if we can't claim the zstream. */ if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK) png_error(png_ptr, png_ptr->zstream.msg); /* The following state fields are, effectively, maintained by png_compress, * except for zbuffer_start which is maintained directly by * png_compress_IDAT. */ png_ptr->zbuffer_start = 0U; png_ptr->zbuffer_len = 0U; png_ptr->zbuffer_end = &png_ptr->zbuffer_list; } static void png_compress_IDAT(png_structrp png_ptr, png_const_voidp input, uInt input_len, int flush) { int ret; /* The stream must have been claimed: */ affirm(png_ptr->zowner == png_IDAT); /* z_stream::{next,avail}_out are set by png_compress to point into the * buffer list. next_in must be set here, avail_in comes from the input_len * parameter: */ { png_uint_32 output_len = 0U; png_ptr->zstream.next_in = PNGZ_INPUT_CAST(png_voidcast(const Bytef*,input)); ret = png_compress(png_ptr, &png_ptr->zstream, &png_ptr->zbuffer_end, input_len, &output_len, flush); implies(ret == Z_OK || ret == Z_FINISH, png_ptr->zstream.avail_in == 0U); png_ptr->zstream.next_in = NULL; png_ptr->zstream.avail_in = 0U; /* safety */ /* If IDAT_size is set to PNG_UINT_31_MAX the length will be larger, but * not enough to overflow a png_uint_32. */ png_ptr->zbuffer_len += output_len; } /* Check the return code. */ if (ret == Z_OK || ret == Z_STREAM_END) { /* Z_FINISH should give Z_STREAM_END, everything else should give Z_OK, * so: */ debug((ret == Z_STREAM_END) == (flush == Z_FINISH)); /* At this point png_compress has produced (in total) zbuffer_start + * zbuffer_len compressed bytes in a list of compression buffers starting * with zbuffer_list and ending with the buffer containing *zbuffer_end, * which may be NULL or may point to unused compression buffers. * * This code has already written out zbuffer_start bytes from the first * buffer. Can we write more? If flush is Z_FINISH this is the end of * the stream and there should be final bytes to write. Otherwise wait * for IDAT_size bytes before writing a chunk. If nothing is to be * written this function call is complete. */ if (flush == Z_FINISH || png_ptr->zbuffer_len >= png_ptr->IDAT_size) { png_compression_bufferp *listp = &png_ptr->zbuffer_list; png_compression_bufferp list; png_uint_32 output_len = png_ptr->zbuffer_len; png_uint_32 start = png_ptr->zbuffer_start; png_uint_32 size = png_ptr->IDAT_size; const png_uint_32 min_size = (flush == Z_FINISH ? 1U : size); affirm(output_len >= min_size); /* png_struct::zbuffer_end points to the pointer to the next (unused) * compression buffer. We don't need those blocks to produce output so * free them now to save space. This also ensures that *zbuffer_end is * NULL so can be used to store the list head when wrapping the list. */ png_free_buffer_list(png_ptr, png_ptr->zbuffer_end); /* Write at least one chunk, of size 'size', write chunks until * 'output_len' is less than 'min_size'. */ list = *listp; /* First, if this is the very first IDAT (PNG_HAVE_IDAT not set) * optimize the CINFO field: */ # ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED if ((png_ptr->mode & PNG_HAVE_IDAT) == 0U) { affirm(start == 0U); optimize_cmf(list->output, png_image_size(png_ptr)); } # endif /* WRITE_OPTIMIZE_CMF */ do /* write chunks */ { /* 'size' is the size of the chunk to write, limited to IDAT_size: */ if (size > output_len) /* Z_FINISH */ size = output_len; debug(size >= min_size); png_write_chunk_header(png_ptr, png_IDAT, size); do /* write the data of one chunk */ { /* The chunk data may be split across multiple compression * buffers. This loop moves 'list' down the available * compression buffers. */ png_uint_32 avail = PNG_ROW_BUFFER_SIZE - start; /* in *list */ if (avail > output_len) /* valid bytes */ avail = output_len; if (avail > size) /* bytes needed for chunk */ avail = size; affirm(list != NULL && avail > 0U && start+avail <= PNG_ROW_BUFFER_SIZE); png_write_chunk_data(png_ptr, list->output+start, avail); output_len -= avail; size -= avail; start += avail; if (start == PNG_ROW_BUFFER_SIZE) { /* End of the buffer. If all the compressed data has been * consumed (output_len == 0) this will set list to NULL * because of the png_free_buffer_list call above. At this * point 'size' should be 0 too and the loop will terminate. */ start = 0U; listp = &list->next; list = *listp; /* May be NULL at the end */ } } while (size > 0); png_write_chunk_end(png_ptr); size = png_ptr->IDAT_size; /* For the next chunk */ } while (output_len >= min_size); png_ptr->mode |= PNG_HAVE_IDAT; png_ptr->zbuffer_len = output_len; if (output_len > 0U) /* Still got stuff to write */ { affirm(flush != Z_FINISH && list != NULL); /* If any compression buffers have been completely written move them * to the end of the list so that they can be re-used and move * 'list' to the head: */ if (listp != &png_ptr->zbuffer_list) /* list not at start */ { debug(list != png_ptr->zbuffer_list /* obviously */ && listp != png_ptr->zbuffer_end /* because *end == NULL */); *png_ptr->zbuffer_end = png_ptr->zbuffer_list; *listp = NULL; png_ptr->zbuffer_list = list; } /* 'list' is now at the start, so 'start' can be stored. */ png_ptr->zbuffer_start = start; png_ptr->zbuffer_len = output_len; } else /* output_len == 0U; all compressed data has been written */ { if (flush == Z_FINISH) /* end of data */ { png_ptr->zowner = 0U; /* release z_stream */ png_ptr->mode |= PNG_AFTER_IDAT; } /* Else: this is unlikely but possible; the compression code managed * to exactly fill an IDAT chunk with the data for this block of row * bytes so nothing is left in the buffer list. Simply reset the * output pointers to the start of the list. This code is executed * on Z_FINISH as well just to make the state safe. */ png_ptr->zstream.next_out = NULL; png_ptr->zstream.avail_out = 0U; png_ptr->zbuffer_start = 0U; png_ptr->zbuffer_len = 0U; png_ptr->zbuffer_end = &png_ptr->zbuffer_list; } /* output_len == 0 */ } /* flush == FINISH || png_ptr->zbuffer_len >= png_ptr->IDAT_size */ } else /* ret != Z_OK && ret != Z_STREAM_END */ { /* This is an error condition. It is fatal. */ png_zstream_error(&png_ptr->zstream, ret); png_ptr->zowner = 0U; png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list); png_error(png_ptr, png_ptr->zstream.msg); } } #ifdef PNG_WRITE_FLUSH_SUPPORTED /* Set the automatic flush interval or 0 to turn flushing off */ void PNGAPI png_set_flush(png_structrp png_ptr, int nrows) { png_debug(1, "in png_set_flush"); if (png_ptr == NULL) return; png_ptr->flush_dist = (nrows < 0 ? 0 : nrows); } /* Flush the current output buffers now */ void PNGAPI png_write_flush(png_structrp png_ptr) { png_debug(1, "in png_write_flush"); if (png_ptr == NULL) return; /* Before the start of the IDAT and after the end of the image zowner will be * something other than png_IDAT: */ if (png_ptr->zowner == png_IDAT) { Byte b[1]; png_compress_IDAT(png_ptr, b, 0U, Z_SYNC_FLUSH); png_ptr->flush_rows = 0; png_flush(png_ptr); } } #endif /* WRITE_FLUSH */ static void write_filtered_row(png_structrp png_ptr, png_const_voidp filtered_row, unsigned int row_bytes, png_byte filter /*if at start of row*/, int end_of_image) { /* This handles writing a row that has been filtered, or did not need to be * filtered. If the data row has a partial pixel it must have been handled * correctly in the caller; filters generate a full 8 bits even if the pixel * only has one significant bit! */ debug(row_bytes > 0); affirm(row_bytes <= ZLIB_IO_MAX); /* I.e. it fits in a uInt */ if (filter < PNG_FILTER_VALUE_LAST) /* start of row */ { png_byte buffer[1]; buffer[0] = filter; png_compress_IDAT(png_ptr, buffer, 1U/*len*/, Z_NO_FLUSH); } png_compress_IDAT(png_ptr, filtered_row, row_bytes, end_of_image ? Z_FINISH : Z_NO_FLUSH); } static void write_unfiltered_rowbits(png_structrp png_ptr, png_const_bytep filtered_row, unsigned int row_bits, png_byte filter /*if at start of row*/, int end_of_image) { /* Same as above, but it correctly clears the unused bits in a partial * byte. */ const png_uint_32 row_bytes = row_bits >> 3; debug(filter == PNG_FILTER_VALUE_NONE || filter == PNG_FILTER_VALUE_LAST); if (row_bytes > 0U) { row_bits -= row_bytes << 3; write_filtered_row(png_ptr, filtered_row, row_bytes, filter, end_of_image && row_bits == 0U); filter = PNG_FILTER_VALUE_LAST; /* written */ } /* Handle a partial byte. */ if (row_bits > 0U) { png_byte buffer[1]; buffer[0] = PNG_BYTE(filtered_row[row_bytes] & ~(0xFFU >> row_bits)); write_filtered_row(png_ptr, buffer, 1U, filter, end_of_image); } } #ifdef PNG_WRITE_FILTER_SUPPORTED static void filter_block_singlebyte(unsigned int row_bytes, png_bytep sub_row, png_bytep up_row, png_bytep avg_row, png_bytep paeth_row, png_const_bytep row, png_const_bytep prev_row, png_bytep prev_pixels) { /* Calculate rows for all four filters where the input has one byte per pixel * (more accurately per filter-unit). */ png_byte a = prev_pixels[0]; png_byte c = prev_pixels[1]; while (row_bytes-- > 0U) { const png_byte x = *row++; const png_byte b = prev_row == NULL ? 0U : *prev_row++; /* Calculate each filtered byte in turn: */ if (sub_row != NULL) *sub_row++ = 0xFFU & (x - a); if (up_row != NULL) *up_row++ = 0xFFU & (x - b); if (avg_row != NULL) *avg_row++ = 0xFFU & (x - (a+b)/2U); /* Paeth is a little more difficult: */ if (paeth_row != NULL) { int pa = b-c; /* a+b-c - a */ int pb = a-c; /* a+b-c - b */ int pc = pa+pb; /* a+b-c - c = b-c + a-c */ png_byte p = a; pa = abs(pa); pb = abs(pb); if (pa > pb) pa = pb, p = b; if (pa > abs(pc)) p = c; *paeth_row++ = 0xFFU & (x - p); } /* And set a and c for the next pixel: */ a = x; c = b; } /* Store a and c for the next block: */ prev_pixels[0] = a; prev_pixels[1] = c; } static void filter_block_multibyte(unsigned int row_bytes, const unsigned int bpp, png_bytep sub_row, png_bytep up_row, png_bytep avg_row, png_bytep paeth_row, png_const_bytep row, png_const_bytep prev_row, png_bytep prev_pixels) { /* Calculate rows for all four filters, the input is a block of bytes such * that row_bytes is a multiple of bpp. bpp can be 2, 3, 4, 6 or 8. * prev_pixels will be updated to the last pixels processed. */ while (row_bytes >= bpp) { unsigned int i; for (i=0; i pb) pa = pb, p = b; if (pa > abs(pc)) p = c; *paeth_row++ = 0xFFU & (x - p); } } row_bytes -= i; } } 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 filters_to_try, int start_of_row, int end_of_image) { /* filters_to_try identifies a single filter and it is not PNG_FILTER_NONE. */ unsigned int row_bytes = row_bits >> 3; /* complete bytes */ png_byte filter = PNG_FILTER_VALUE_LAST /* not at start */; png_byte filtered_row[PNG_ROW_BUFFER_SIZE]; debug((row_bits % bpp) == 0U); if (start_of_row) switch (filters_to_try) { case PNG_FILTER_SUB: filter = PNG_FILTER_VALUE_SUB; break; case PNG_FILTER_UP: filter = PNG_FILTER_VALUE_UP; break; case PNG_FILTER_AVG: filter = PNG_FILTER_VALUE_AVG; break; case PNG_FILTER_PAETH: filter = PNG_FILTER_VALUE_PAETH; break; default: impossible("filter list"); } if (bpp <= 8U) { /* There may be a partial byte at the end. */ if (row_bytes > 0) filter_block_singlebyte(row_bytes, filters_to_try & PNG_FILTER_SUB ? filtered_row : NULL, filters_to_try & PNG_FILTER_UP ? filtered_row : NULL, filters_to_try & PNG_FILTER_AVG ? filtered_row : NULL, filters_to_try & PNG_FILTER_PAETH ? filtered_row : NULL, 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, filters_to_try & PNG_FILTER_SUB ? filtered_row+row_bytes : NULL, filters_to_try & PNG_FILTER_UP ? filtered_row+row_bytes : NULL, filters_to_try & PNG_FILTER_AVG ? filtered_row+row_bytes : NULL, filters_to_try & PNG_FILTER_PAETH ? filtered_row+row_bytes : NULL, buffer, buffer+1U, prev_pixels); ++row_bytes; /* for write_filtered_row below */ } } else { debug((bpp & 7U) == 0U && row_bits == (row_bytes << 3)); filter_block_multibyte(row_bytes, bpp >> 3, filters_to_try & PNG_FILTER_SUB ? filtered_row : NULL, filters_to_try & PNG_FILTER_UP ? filtered_row : NULL, filters_to_try & PNG_FILTER_AVG ? filtered_row : NULL, filters_to_try & PNG_FILTER_PAETH ? filtered_row : NULL, unfiltered_row, prev_row, prev_pixels); } write_filtered_row(png_ptr, filtered_row, row_bytes, filter, end_of_image); } static void find_filter(png_structrp png_ptr, png_const_bytep prev_row, png_bytep prev_pixels, png_const_bytep unfiltered_row, unsigned int row_bits, unsigned int bpp, unsigned int filters_to_try, int start_of_row, int end_of_image) { /* filters_to_try identifies multiple filters, up to all five. */ /* TODO: reimplement this, currently this just selects the first filter */ filters_to_try &= -filters_to_try; if (filters_to_try == PNG_FILTER_NONE) write_unfiltered_rowbits(png_ptr, unfiltered_row, row_bits, start_of_row ? PNG_FILTER_VALUE_NONE : PNG_FILTER_VALUE_LAST, end_of_image); else filter_row(png_ptr, prev_row, prev_pixels, unfiltered_row, row_bits, bpp, filters_to_try & -filters_to_try, start_of_row, end_of_image); } /* 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. */ unsigned int /* PRIVATE */ png_write_filter_row(png_structrp png_ptr, png_bytep prev_pixels, png_const_bytep unfiltered_row, png_uint_32 x, unsigned int width/*pixels*/, int first_row_in_pass, int last_pass_row, unsigned int filters_to_try, int end_of_image) { png_bytep prev_row = png_ptr->row_buffer; const unsigned int bpp = png_ptr->row_output_pixel_depth; const unsigned int row_bits = width * bpp; /* These invariants are expected from the caller: */ affirm(width < 65536U && bpp <= 64U && width < 65536U/bpp && row_bits <= 8U*PNG_ROW_BUFFER_SIZE); /* Set up the IDAT zlib compression if not set up yet: */ if (png_ptr->zowner != png_IDAT) png_start_IDAT(png_ptr); if (x == 0U) /* start of row */ { /* Delaying initialization of the filter stuff. */ if (png_ptr->filter_mask == 0U) png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, PNG_ALL_FILTERS); /* Now work out the filters to try for this row: */ filters_to_try = png_ptr->filter_mask; /* else caller must preserve */ /* If this has a previous row filter in the set to try ensure the row * buffer exists and ensure it is empty when first allocated and at * the start of the pass. */ if ((filters_to_try & (PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH)) != 0U) { if (prev_row == NULL) { /* Just allocate for the total output row bytes; a three-row * interlaced image requires less, but this is safe. */ prev_row = png_voidcast(png_bytep, png_malloc(png_ptr, png_calc_rowbytes(png_ptr, bpp, png_ptr->width))); png_ptr->row_buffer = prev_row; /* If that buffer would have been required for this row issue an * app warning and disable the filters that would have required * the data. */ if (!first_row_in_pass) { png_app_warning(png_ptr, "Previous row filters ignored"); /* And always turn off the filters, to prevent using * uninitialized data. */ filters_to_try &= PNG_BIC_MASK( PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH); if (filters_to_try == 0U) filters_to_try = PNG_FILTER_NONE; } } } if (first_row_in_pass) { /* On the first row UP and NONE are the same, PAETH and SUB are the * same, so if both members of a pair occur together eliminate the one * that depends on the previous row. This will avoid the filter * selection code while allowing the app to ensure all the filters can * be used (prev_row is allocated) on the first row. */ # define match(mask) (filters_to_try & (mask)) == mask if (match(PNG_FILTER_NONE+PNG_FILTER_UP)) filters_to_try &= PNG_BIC_MASK(PNG_FILTER_UP); if (match(PNG_FILTER_SUB+PNG_FILTER_PAETH)) filters_to_try &= PNG_BIC_MASK(PNG_FILTER_UP); # undef match } } /* start of row */ else if (prev_row != NULL) { /* Advance prev_row to the corresponding pixel above row[x], must use * png_calc_rowbytes here otherwise the calculation using x might * overflow. */ debug(((x * bpp) & 7U) == 0U); prev_row += png_calc_rowbytes(png_ptr, bpp, x); } /* Now choose the correct filter implementation according to the number of * filters in the filters_to_try list. The prev_row parameter is made NULL * on the first row because it is uninitialized at that point. */ if (filters_to_try == PNG_FILTER_NONE) write_unfiltered_rowbits(png_ptr, unfiltered_row, row_bits, x == 0 ? PNG_FILTER_VALUE_NONE : PNG_FILTER_VALUE_LAST, end_of_image); else if ((filters_to_try & -filters_to_try) == filters_to_try) /* 1 filter */ filter_row(png_ptr, first_row_in_pass ? NULL : prev_row, prev_pixels, unfiltered_row, row_bits, bpp, filters_to_try, x == 0, end_of_image); else find_filter(png_ptr, first_row_in_pass ? NULL : prev_row, prev_pixels, unfiltered_row, row_bits, bpp, filters_to_try, x == 0, end_of_image); /* Copy the current row into the previous row buffer, if available, unless * this is the last row in the pass, when there is no point. Note that * prev_row may have garbage in a partial byte at the end. */ if (prev_row != NULL && !last_pass_row) memcpy(prev_row, unfiltered_row, (row_bits + 7U) >> 3); return filters_to_try; } /* Allow the application to select one or more row filters to use. */ void PNGAPI png_set_filter(png_structrp png_ptr, int method, int filtersIn) { unsigned int filters; png_debug(1, "in png_set_filter"); if (png_ptr == NULL) return; if (png_ptr->read_struct) { png_app_error(png_ptr, "png_set_filter: cannot be used when reading"); return; } if (method != png_ptr->filter_method) { png_app_error(png_ptr, "png_set_filter: method does not match IHDR"); return; } /* PNG and MNG use the same base adaptive filter types: */ if (method != PNG_FILTER_TYPE_BASE && method != PNG_INTRAPIXEL_DIFFERENCING) { png_app_error(png_ptr, "png_set_filter: unsupported method"); return; } /* Notice that PNG_NO_FILTERS is 0 and passes this test; this is OK * because filters then gets set to PNG_FILTER_NONE, as is required. */ if (filtersIn >= 0 && filtersIn < PNG_FILTER_VALUE_LAST) filters = 8U << filtersIn; else if ((filtersIn & PNG_BIC_MASK(PNG_ALL_FILTERS)) == 0) filters = filtersIn & PNG_ALL_FILTERS; else { png_app_error(png_ptr, "png_set_filter: invalid filters mask/value"); /* Prior to 1.7.0 this ignored the error and just used the bits that * are present, now it does nothing; this seems a lot safer. */ return; } debug(filters != 0U && (filters & PNG_BIC_MASK(PNG_ALL_FILTERS)) == 0U); png_ptr->filter_mask = png_check_bits(png_ptr, filters, 8); } #else /* !WRITE_FILTER */ unsigned int /* PRIVATE */ png_write_filter_row(png_structrp png_ptr, png_bytep prev_pixels, png_const_bytep unfiltered_row, png_uint_32 x, unsigned int width/*pixels*/, int first_row_in_pass, int last_pass_row, unsigned int filters_to_try/*from previous call*/, int end_of_image) { const unsigned int bpp = png_ptr->row_output_pixel_depth; png_uint_32 row_bits; row_bits = width; row_bits *= bpp; /* These invariants are expected from the caller: */ affirm(width < 65536U && bpp <= 64U && width < 65536U/bpp && row_bits <= 8U*PNG_ROW_BUFFER_SIZE); /* Set up the IDAT zlib compression if not set up yet: */ if (png_ptr->zowner != png_IDAT) png_start_IDAT(png_ptr); write_unfiltered_rowbits(png_ptr, unfiltered_row, row_bits, x == 0 ? PNG_FILTER_VALUE_NONE : PNG_FILTER_VALUE_LAST, end_of_image); return filters_to_try; PNG_UNUSED(first_row_in_pass); PNG_UNUSED(prev_pixels); PNG_UNUSED(last_pass_row); } #endif /* !WRITE_FILTER */ #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* GRR 970116 */ /* Legacy API that weighted the filter metric by the number of times it had been * used before. */ #ifdef PNG_FLOATING_POINT_SUPPORTED PNG_FUNCTION(void,PNGAPI png_set_filter_heuristics,(png_structrp png_ptr, int heuristic_method, int num_weights, png_const_doublep filter_weights, png_const_doublep filter_costs),PNG_DEPRECATED) { png_app_warning(png_ptr, "weighted filter heuristics not implemented"); PNG_UNUSED(heuristic_method) PNG_UNUSED(num_weights) PNG_UNUSED(filter_weights) PNG_UNUSED(filter_costs) } #endif /* FLOATING_POINT */ #ifdef PNG_FIXED_POINT_SUPPORTED PNG_FUNCTION(void,PNGAPI png_set_filter_heuristics_fixed,(png_structrp png_ptr, int heuristic_method, int num_weights, png_const_fixed_point_p filter_weights, png_const_fixed_point_p filter_costs),PNG_DEPRECATED) { png_app_warning(png_ptr, "weighted filter heuristics not implemented"); PNG_UNUSED(heuristic_method) PNG_UNUSED(num_weights) PNG_UNUSED(filter_weights) PNG_UNUSED(filter_costs) } #endif /* FIXED_POINT */ #endif /* WRITE_WEIGHTED_FILTER */ #ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED void PNGAPI png_set_compression_level(png_structrp png_ptr, int level) { png_debug(1, "in png_set_compression_level"); if (png_ptr == NULL) return; png_ptr->zlib_level = level; } void PNGAPI png_set_compression_mem_level(png_structrp png_ptr, int mem_level) { png_debug(1, "in png_set_compression_mem_level"); if (png_ptr == NULL) return; png_ptr->zlib_mem_level = mem_level; } void PNGAPI png_set_compression_strategy(png_structrp png_ptr, int strategy) { png_debug(1, "in png_set_compression_strategy"); if (png_ptr == NULL) return; /* The flag setting here prevents the libpng dynamic selection of strategy. */ png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY; png_ptr->zlib_strategy = strategy; } /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a * smaller value of window_bits if it can do so safely. */ void PNGAPI png_set_compression_window_bits(png_structrp png_ptr, int window_bits) { if (png_ptr == NULL) return; /* Prior to 1.6.0 this would warn but then set the window_bits value. This * meant that negative window bits values could be selected that would cause * libpng to write a non-standard PNG file with raw deflate or gzip * compressed IDAT or ancillary chunks. Such files can be read and there is * no warning on read, so this seems like a very bad idea. */ if (window_bits > 15) { png_warning(png_ptr, "Only compression windows <= 32k supported by PNG"); window_bits = 15; } else if (window_bits < 8) { png_warning(png_ptr, "Only compression windows >= 256 supported by PNG"); window_bits = 8; } png_ptr->zlib_window_bits = window_bits; } void PNGAPI png_set_compression_method(png_structrp png_ptr, int method) { png_debug(1, "in png_set_compression_method"); if (png_ptr == NULL) return; /* This would produce an invalid PNG file if it worked, but it doesn't and * deflate will fault it, so it is harmless to just warn here. */ if (method != 8) png_warning(png_ptr, "Only compression method 8 is supported by PNG"); png_ptr->zlib_method = method; } #endif /* WRITE_CUSTOMIZE_COMPRESSION */ /* The following were added to libpng-1.5.4 */ #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED void PNGAPI png_set_text_compression_level(png_structrp png_ptr, int level) { png_debug(1, "in png_set_text_compression_level"); if (png_ptr == NULL) return; png_ptr->zlib_text_level = level; } void PNGAPI png_set_text_compression_mem_level(png_structrp png_ptr, int mem_level) { png_debug(1, "in png_set_text_compression_mem_level"); if (png_ptr == NULL) return; png_ptr->zlib_text_mem_level = mem_level; } void PNGAPI png_set_text_compression_strategy(png_structrp png_ptr, int strategy) { png_debug(1, "in png_set_text_compression_strategy"); if (png_ptr == NULL) return; png_ptr->zlib_text_strategy = strategy; } /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a * smaller value of window_bits if it can do so safely. */ void PNGAPI png_set_text_compression_window_bits(png_structrp png_ptr, int window_bits) { if (png_ptr == NULL) return; if (window_bits > 15) { png_warning(png_ptr, "Only compression windows <= 32k supported by PNG"); window_bits = 15; } else if (window_bits < 8) { png_warning(png_ptr, "Only compression windows >= 256 supported by PNG"); window_bits = 8; } png_ptr->zlib_text_window_bits = window_bits; } void PNGAPI png_set_text_compression_method(png_structrp png_ptr, int method) { png_debug(1, "in png_set_text_compression_method"); if (png_ptr == NULL) return; if (method != 8) png_warning(png_ptr, "Only compression method 8 is supported by PNG"); png_ptr->zlib_text_method = method; } #endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */ /* end of API added to libpng-1.5.4 */ #endif /* WRITE */