/* 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_bytep 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_bytep 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)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_bytep 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_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; } #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 if (png_ptr->next_filter != PNG_FILTER_NONE) strategy = PNG_Z_DEFAULT_STRATEGY; else #endif 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, 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, 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); } } #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED /* This pair of functions encapsulates the operation of (a) compressing a * text string, and (b) issuing it later as a series of chunk data writes. * The compression_state structure is shared context for these functions * set up by the caller to allow access to the relevant local variables. * * compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size * 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.) */ typedef struct { png_const_bytep input; /* The uncompressed input data */ png_alloc_size_t input_len; /* Its length */ png_uint_32 output_len; /* Final compressed length */ png_byte output[1024]; /* First block of output */ } compression_state; static void png_text_compress_init(compression_state *comp, png_const_bytep input, png_alloc_size_t input_len) { comp->input = input; comp->input_len = input_len; comp->output_len = 0; } /* Compress the data in the compression state input */ static int png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name, compression_state *comp, png_uint_32 prefix_len) { int ret; /* 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. */ ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len); if (ret != Z_OK) return ret; /* Set up the compression buffers, we need a loop here to avoid overflowing a * uInt. Use ZLIB_IO_MAX to limit the input. The output is always limited * by the output buffer size, so there is no need to check that. Since this * is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits * in size. */ { png_compression_bufferp *end = &png_ptr->zbuffer_list; png_alloc_size_t input_len = comp->input_len; /* may be zero! */ png_uint_32 output_len; /* zlib updates these for us: */ png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input); png_ptr->zstream.avail_in = 0; /* Set below */ png_ptr->zstream.next_out = comp->output; png_ptr->zstream.avail_out = (sizeof comp->output); output_len = png_ptr->zstream.avail_out; do { uInt avail_in = ZLIB_IO_MAX; if (avail_in > input_len) avail_in = (uInt)input_len; input_len -= avail_in; png_ptr->zstream.avail_in = avail_in; if (png_ptr->zstream.avail_out == 0) { png_compression_buffer *next; /* Chunk data is limited to 2^31 bytes in length, so the prefix * length must be counted here. */ if (output_len + prefix_len > PNG_UINT_31_MAX) { ret = Z_MEM_ERROR; break; } /* Need a new (malloc'ed) buffer, but there may be one present * already. */ next = *end; if (next == NULL) { next = png_voidcast(png_compression_bufferp, png_malloc_base (png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr))); if (next == NULL) { ret = Z_MEM_ERROR; break; } /* Link in this buffer (so that it will be freed later) */ next->next = NULL; *end = next; } png_ptr->zstream.next_out = next->output; png_ptr->zstream.avail_out = png_ptr->zbuffer_size; output_len += png_ptr->zstream.avail_out; /* Move 'end' to the next buffer pointer. */ end = &next->next; } /* Compress the data */ ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : Z_FINISH); /* Claw back input data that was not consumed (because avail_in is * reset above every time round the loop). */ input_len += png_ptr->zstream.avail_in; png_ptr->zstream.avail_in = 0; /* safety */ } while (ret == Z_OK); /* There may be some space left in the last output buffer. This needs to * be subtracted from output_len. */ output_len -= png_ptr->zstream.avail_out; png_ptr->zstream.avail_out = 0; /* safety */ comp->output_len = output_len; /* Now double check the output length, put in a custom message if it is * too long. Otherwise ensure the z_stream::msg pointer is set to * something. */ if (output_len + prefix_len >= PNG_UINT_31_MAX) { png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long"); ret = Z_MEM_ERROR; } else png_zstream_error(png_ptr, ret); /* Reset zlib for another zTXt/iTXt or image data */ png_ptr->zowner = 0; /* The only success case is Z_STREAM_END, input_len must be 0; if not this * is an internal error. */ if (ret == Z_STREAM_END && input_len == 0) { #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED /* Fix up the deflate header, if required */ optimize_cmf(comp->output, comp->input_len); #endif /* But Z_OK is returned, not Z_STREAM_END; this allows the claim * function above to return Z_STREAM_END on an error (though it never * does in the current versions of zlib.) */ return Z_OK; } else return ret; } } /* Ship the compressed text out via chunk writes */ static void png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp) { png_uint_32 output_len = comp->output_len; png_const_bytep output = comp->output; png_uint_32 avail = (sizeof comp->output); png_compression_buffer *next = png_ptr->zbuffer_list; for (;;) { if (avail > output_len) avail = output_len; png_write_chunk_data(png_ptr, output, avail); output_len -= avail; if (output_len == 0 || next == NULL) break; avail = png_ptr->zbuffer_size; output = next->output; next = next->next; } /* This is an internal error; 'next' must have been NULL! */ affirm(output_len == 0); } #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 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 png_error. */ static png_uint_32 png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key) { png_const_charp orig_key = key; png_uint_32 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_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->next_filter == PNG_NO_FILTERS /* not yet set */) { if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE || png_ptr->bit_depth < 8) png_ptr->next_filter = PNG_FILTER_NONE; else png_ptr->next_filter = 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 i; png_const_colorp pal_ptr; png_byte buf[3]; png_debug(1, "in png_write_PLTE"); 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 > PNG_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; } /* 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. */ void /* PRIVATE */ png_compress_IDAT(png_structrp png_ptr, png_const_bytep input, png_alloc_size_t input_len, int flush) { if (png_ptr->zowner != png_IDAT) { /* First time. Ensure we have a temporary buffer for compression and * trim the buffer list if it has more than one entry to free memory. * If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been * created at this point, but the check here is quick and safe. */ if (png_ptr->zbuffer_list == NULL) { png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp, png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr))); png_ptr->zbuffer_list->next = NULL; } else png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next); /* 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 output state is maintained in png_ptr->zstream, so it must be * initialized here after the claim. */ png_ptr->zstream.next_out = png_ptr->zbuffer_list->output; png_ptr->zstream.avail_out = png_ptr->zbuffer_size; } /* Now loop reading and writing until all the input is consumed or an error * terminates the operation. The _out values are maintained across calls to * this function, but the input must be reset each time. */ png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input); png_ptr->zstream.avail_in = 0; /* set below */ for (;;) { int ret; /* INPUT: from the row data */ uInt avail = ZLIB_IO_MAX; if (avail > input_len) avail = (uInt)input_len; /* safe because of the check */ png_ptr->zstream.avail_in = avail; input_len -= avail; ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush); /* Include as-yet unconsumed input */ input_len += png_ptr->zstream.avail_in; png_ptr->zstream.avail_in = 0; /* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note * that these two zstream fields are preserved across the calls, therefore * there is no need to set these up on entry to the loop. */ if (png_ptr->zstream.avail_out == 0) { png_bytep data = png_ptr->zbuffer_list->output; uInt size = png_ptr->zbuffer_size; /* Write an IDAT containing the data then reset the buffer. The * first IDAT may need deflate header optimization. */ #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 && png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE) optimize_cmf(data, png_image_size(png_ptr)); #endif png_write_complete_chunk(png_ptr, png_IDAT, data, size); png_ptr->mode |= PNG_HAVE_IDAT; png_ptr->zstream.next_out = data; png_ptr->zstream.avail_out = size; /* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with * the same flush parameter until it has finished output, for NO_FLUSH * it doesn't matter. */ if (ret == Z_OK && flush != Z_NO_FLUSH) continue; } /* The order of these checks doesn't matter much; it just affects which * possible error might be detected if multiple things go wrong at once. */ if (ret == Z_OK) /* most likely return code! */ { /* If all the input has been consumed then just return. If Z_FINISH * was used as the flush parameter something has gone wrong if we get * here. */ if (input_len == 0) { if (flush == Z_FINISH) png_error(png_ptr, "Z_OK on Z_FINISH with output space"); return; } } else if (ret == Z_STREAM_END && flush == Z_FINISH) { /* This is the end of the IDAT data; any pending output must be * flushed. For small PNG files we may still be at the beginning. */ png_bytep data = png_ptr->zbuffer_list->output; uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out; #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 && png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE) optimize_cmf(data, png_image_size(png_ptr)); #endif png_write_complete_chunk(png_ptr, png_IDAT, data, size); png_ptr->zstream.avail_out = 0; png_ptr->zstream.next_out = NULL; png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT; png_ptr->zowner = 0; /* Release the stream */ return; } else { /* This is an error condition. */ png_zstream_error(png_ptr, ret); png_error(png_ptr, png_ptr->zstream.msg); } } } /* 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. */ { if (i >= 0 && i <= 0x7FFFFFFF) { 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_warning(png_ptr, "Invalid sRGB rendering intent specified"); 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_bytep profile) { png_uint_32 name_len; png_uint_32 profile_len; png_byte new_name[81]; /* 1 byte for the compression byte */ compression_state comp; png_debug(1, "in png_write_iCCP"); /* These are all internal problems: the profile should have been checked * before when it was stored. */ affirm(profile != NULL); profile_len = png_get_uint_32(profile); if (profile_len < 132) png_error(png_ptr, "ICC profile too short"); if (profile_len & 0x03) png_error(png_ptr, "ICC profile length invalid (not a multiple of 4)"); { png_uint_32 embedded_profile_len = png_get_uint_32(profile); if (profile_len != embedded_profile_len) png_error(png_ptr, "Profile length does not match profile"); } name_len = png_check_keyword(png_ptr, name, new_name); if (name_len == 0) png_error(png_ptr, "iCCP: invalid keyword"); new_name[++name_len] = PNG_COMPRESSION_TYPE_BASE; /* Make sure we include the NULL after the name and the compression type */ ++name_len; png_text_compress_init(&comp, profile, profile_len); /* Allow for keyword terminator and compression byte */ if (png_text_compress(png_ptr, png_iCCP, &comp, name_len) != Z_OK) png_error(png_ptr, png_ptr->zstream.msg); png_write_chunk_header(png_ptr, png_iCCP, name_len + comp.output_len); png_write_chunk_data(png_ptr, new_name, name_len); png_write_compressed_data_out(png_ptr, &comp); 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) { png_uint_32 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_error(png_ptr, "tEXt: invalid keyword"); if (text == NULL || *text == '\0') text_len = 0; else text_len = strlen(text); if (text_len > PNG_UINT_31_MAX - (key_len+1)) png_error(png_ptr, "tEXt: text too long"); /* 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 key_len; png_byte new_key[81]; compression_state comp; png_debug(1, "in png_write_zTXt"); if (compression == PNG_TEXT_COMPRESSION_NONE) { png_write_tEXt(png_ptr, key, text, 0); return; } if (compression != PNG_TEXT_COMPRESSION_zTXt) png_error(png_ptr, "zTXt: invalid compression type"); key_len = png_check_keyword(png_ptr, key, new_key); if (key_len == 0) png_error(png_ptr, "zTXt: invalid keyword"); /* Add the compression method and 1 for the keyword separator. */ new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE; ++key_len; /* Compute the compressed data; do it now for the length */ png_text_compress_init(&comp, (png_const_bytep)text, text == NULL ? 0 : strlen(text)); if (png_text_compress(png_ptr, png_zTXt, &comp, key_len) != Z_OK) png_error(png_ptr, png_ptr->zstream.msg); /* Write start of chunk */ png_write_chunk_header(png_ptr, png_zTXt, key_len + comp.output_len); /* Write key */ png_write_chunk_data(png_ptr, new_key, key_len); /* Write the compressed data */ png_write_compressed_data_out(png_ptr, &comp); /* Close the chunk */ png_write_chunk_end(png_ptr); } #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; png_size_t lang_len, lang_key_len; png_byte new_key[82]; compression_state comp; png_debug(1, "in png_write_iTXt"); key_len = png_check_keyword(png_ptr, key, new_key); if (key_len == 0) png_error(png_ptr, "iTXt: invalid 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_error(png_ptr, "iTXt: invalid compression"); } new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE; ++key_len; /* for the keywod separator */ /* 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, however, * specifies that the text is UTF-8 and this really doesn't require any * checking. * * 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)+1; if (lang_key == NULL) lang_key = ""; /* may be empty */ lang_key_len = strlen(lang_key)+1; if (text == NULL) text = ""; /* may be empty */ prefix_len = key_len; if (lang_len > PNG_UINT_31_MAX-prefix_len) prefix_len = PNG_UINT_31_MAX; else prefix_len = (png_uint_32)(prefix_len + lang_len); if (lang_key_len > PNG_UINT_31_MAX-prefix_len) prefix_len = PNG_UINT_31_MAX; else prefix_len = (png_uint_32)(prefix_len + lang_key_len); png_text_compress_init(&comp, (png_const_bytep)text, strlen(text)); if (compression != 0) { if (png_text_compress(png_ptr, png_iTXt, &comp, prefix_len) != Z_OK) png_error(png_ptr, png_ptr->zstream.msg); } else { if (comp.input_len > PNG_UINT_31_MAX-prefix_len) png_error(png_ptr, "iTXt: uncompressed text too long"); /* So the string will fit in a chunk: */ comp.output_len = (png_uint_32)/*SAFE*/comp.input_len; } png_write_chunk_header(png_ptr, png_iTXt, comp.output_len + prefix_len); png_write_chunk_data(png_ptr, new_key, key_len); png_write_chunk_data(png_ptr, (png_const_bytep)lang, lang_len); png_write_chunk_data(png_ptr, (png_const_bytep)lang_key, lang_key_len); if (compression != 0) png_write_compressed_data_out(png_ptr, &comp); else png_write_chunk_data(png_ptr, (png_const_bytep)text, comp.output_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 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. */ #ifdef PNG_WRITE_FILTER_SUPPORTED static png_size_t /* PRIVATE */ png_setup_sub_row(const int bpp/*BYTES per pixel*/, const png_alloc_size_t row_bytes, const png_size_t lmins, png_const_bytep rp, png_bytep dp) { png_size_t sum = 0; /* Advance one pixel, or one byte, whichever is greater: */ { int i; for (i = 0; i < bpp; i++, rp++, dp++) { int v = *dp = *rp; sum += (v < 128) ? v : 256 - v; } } /* Do the 'sub' filter on the corresponding preceding byte: */ { png_alloc_size_t i; for (i = bpp; i < row_bytes; i++, rp++, dp++) { int v = *dp = PNG_BYTE(rp[0] - rp[-bpp]); if (lmins) { sum += (v < 128) ? v : 256 - v; if (sum > lmins) /* We are already worse, don't continue. */ break; } } } return sum; } static png_size_t /* PRIVATE */ png_setup_up_row(const png_alloc_size_t row_bytes, const png_size_t lmins, png_const_bytep rp, png_const_bytep pp, png_bytep dp) { png_alloc_size_t i; png_size_t sum = 0; for (i = 0; i < row_bytes; i++, rp++, pp++, dp++) { int v = *dp = PNG_BYTE(*rp - *pp); if (lmins) { sum += (v < 128) ? v : 256 - v; if (sum > lmins) /* We are already worse, don't continue. */ break; } } return sum; } static png_size_t /* PRIVATE */ png_setup_avg_row(const int bpp, const png_alloc_size_t row_bytes, const png_size_t lmins, png_const_bytep rp, png_const_bytep pp, png_bytep dp) { png_size_t sum = 0; { int i; for (i = 0; i < bpp; i++, rp++, pp++, dp++) { unsigned int v = *dp = PNG_BYTE(*rp - *pp / 2); sum += (v < 128) ? v : 256 - v; } } { png_alloc_size_t i; for (i = bpp; i < row_bytes; i++, rp++, pp++, dp++) { unsigned int v = *dp = PNG_BYTE(rp[0] - (*pp + rp[-bpp]) / 2); if (lmins) { sum += (v < 128) ? v : 256 - v; if (sum > lmins) /* We are already worse, don't continue. */ break; } } } return sum; } static png_size_t /* PRIVATE */ png_setup_paeth_row(const int bpp, const png_alloc_size_t row_bytes, const png_size_t lmins, png_const_bytep rp, png_const_bytep pp, png_bytep dp) { png_size_t sum = 0; { int i; for (i = 0; i < bpp; i++, dp++, rp++, pp++) { int v = *dp = PNG_BYTE(*rp - *pp); /* UP for the first pixel */ sum += (v < 128) ? v : 256 - v; } } { png_alloc_size_t i; for (i = bpp; i < row_bytes; i++, pp++, rp++, dp++) { int a, b, c, pa, pb, pc, p, v; b = pp[0]; c = pp[-bpp]; a = rp[-bpp]; p = b - c; pc = a - c; #ifdef PNG_USE_ABS pa = abs(p); pb = abs(pc); pc = abs(p + pc); #else pa = p < 0 ? -p : p; pb = pc < 0 ? -pc : pc; pc = (p + pc) < 0 ? -(p + pc) : p + pc; #endif p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c; v = *dp = PNG_BYTE(*rp - p); if (lmins) { sum += (v < 128) ? v : 256 - v; if (sum > lmins) /* We are already worse, don't continue. */ break; } } } return sum; } static png_bytep test_buffer(png_structrp png_ptr, png_const_bytep in_use) /* Return an output row sized buffer from the two available, but never the * one pointed to by 'in_use'. Dynamically allocates buffers as required. * The buffers are always big enough for a full output row because they are * retained until the whole image has been written. */ { int n = 0; png_bytep p = png_ptr->write_row[n]; debug(in_use != NULL); if (p == in_use) p = png_ptr->write_row[++n]; if (p == NULL) png_ptr->write_row[n] = p = png_voidcast(png_bytep, png_malloc(png_ptr, PNG_ROWBYTES(PNG_PIXEL_DEPTH(*png_ptr), png_ptr->width))); return p; } png_const_bytep /* PRIVATE */ png_write_filter_row(png_structrp png_ptr, png_const_bytep row_buf, int first_pass_row, png_const_bytep prev_row, png_alloc_size_t row_bytes, unsigned int bpp, png_bytep filter_byte) { png_const_bytep best_row; png_size_t mins; unsigned int filter_to_do = png_ptr->next_filter; png_byte best_filter; png_debug(1, "in png_write_find_filter"); /* API CHANGE: 1.7.0: previously it was possible to select AVG, PAETH and UP * on the first row, but this complicates the code. In practice with the * default settings only AVG was tried because 'UP' is the same as 'NONE' and * 'PAETH' is the same as 'SUB' * * There are two cases; the row at the start of pass and the case where * the application set the filters so that libpng did not save the * previous row. The first case switches the filters, the second just * clears them from the list. */ if (first_pass_row) { if (filter_to_do & PNG_FILTER_UP) filter_to_do |= PNG_FILTER_NONE; if (filter_to_do & PNG_FILTER_PAETH) filter_to_do |= PNG_FILTER_SUB; /* AVG not handled */ } if (first_pass_row || prev_row == NULL) filter_to_do &= PNG_BIC_MASK(PNG_FILTER_UP+PNG_FILTER_AVG+PNG_FILTER_PAETH); /* A second optimization is possible for narrow images. If an interlaced * image is 5-12 pixels wide pass 2 will have only one column. 1bpp * grayscale images 8 pixels or less wide only have one byte per row (and the * filter acts on the bytes for low bit depth images.) 1bpp grayscale * interlaced images will only have 1 byte in early passes (1 and 2) when the * image is 64 or fewer pixels wide. In these cases the 'SUB' filter reduces * to 'NONE' */ if (row_bytes <= bpp && (filter_to_do & PNG_FILTER_SUB) != 0) { filter_to_do |= PNG_FILTER_NONE; filter_to_do &= PNG_BIC_MASK(PNG_FILTER_SUB); } mins = PNG_SIZE_MAX - 256/* so we can detect potential overflow of the running sum */; /* The prediction method we use is to find which method provides the * smallest value when summing the absolute values of the distances * from zero, using anything >= 128 as negative numbers. This is known * as the "minimum sum of absolute differences" heuristic. Other * heuristics are the "weighted minimum sum of absolute differences" * (experimental and can in theory improve compression), and the "zlib * predictive" method (not implemented yet), which does test compressions * of lines using different filter methods, and then chooses the * (series of) filter(s) that give minimum compressed data size (VERY * computationally expensive). * * GRR 980525: consider also * * (1) minimum sum of absolute differences from running average (i.e., * keep running sum of non-absolute differences & count of bytes) * [track dispersion, too? restart average if dispersion too large?] * * (1b) minimum sum of absolute differences from sliding average, probably * with window size <= deflate window (usually 32K) * * (2) minimum sum of squared differences from zero or running average * (i.e., ~ root-mean-square approach) */ /* We don't need to test the 'no filter' case if this is the only filter * that has been chosen, as it doesn't actually do anything to the data. */ if (filter_to_do <= PNG_FILTER_NONE) /* no filters to chose from */ { *filter_byte = PNG_FILTER_VALUE_NONE; return row_buf; } best_row = row_buf; best_filter = PNG_FILTER_VALUE_NONE; /* TODO: make this into a loop to avoid all the code replication */ if ((filter_to_do & PNG_FILTER_NONE) != 0) { png_const_bytep rp; png_size_t sum = 0; png_size_t i; int v; if (PNG_SIZE_MAX/128 <= row_bytes) { for (i = 0, rp = row_buf; i < row_bytes; i++, rp++) { /* Check for overflow */ if (sum > PNG_SIZE_MAX/128 - 256) break; v = *rp; sum += (v < 128) ? v : 256 - v; } } else /* Overflow is not possible */ { for (i = 0, rp = row_buf; i < row_bytes; i++, rp++) { v = *rp; sum += (v < 128) ? v : 256 - v; } } mins = sum; } /* Sub filter */ if (filter_to_do == PNG_FILTER_SUB) /* It's the only filter so no testing is needed */ { png_bytep tst_row = test_buffer(png_ptr, best_row); (void)png_setup_sub_row(bpp, row_bytes, 0, row_buf, tst_row); best_row = tst_row; best_filter = PNG_FILTER_VALUE_SUB; } else if ((filter_to_do & PNG_FILTER_SUB) != 0) { png_size_t sum; png_bytep tst_row = test_buffer(png_ptr, best_row); sum = png_setup_sub_row(bpp, row_bytes, mins, row_buf, tst_row); if (sum < mins) { mins = sum; best_row = tst_row; best_filter = PNG_FILTER_VALUE_SUB; } } /* Up filter */ if (filter_to_do == PNG_FILTER_UP) { png_bytep tst_row = test_buffer(png_ptr, best_row); (void)png_setup_up_row(row_bytes, 0, row_buf, prev_row, tst_row); best_row = tst_row; best_filter = PNG_FILTER_VALUE_UP; } else if ((filter_to_do & PNG_FILTER_UP) != 0) { png_size_t sum; png_bytep tst_row = test_buffer(png_ptr, best_row); sum = png_setup_up_row(row_bytes, mins, row_buf, prev_row, tst_row); if (sum < mins) { mins = sum; best_row = tst_row; best_filter = PNG_FILTER_VALUE_UP; } } /* Avg filter */ if (filter_to_do == PNG_FILTER_AVG) { png_bytep tst_row = test_buffer(png_ptr, best_row); (void)png_setup_avg_row(bpp, row_bytes, 0, row_buf, prev_row, tst_row); best_row = tst_row; best_filter = PNG_FILTER_VALUE_AVG; } else if ((filter_to_do & PNG_FILTER_AVG) != 0) { png_size_t sum; png_bytep tst_row = test_buffer(png_ptr, best_row); sum = png_setup_avg_row(bpp, row_bytes, mins, row_buf, prev_row, tst_row); if (sum < mins) { mins = sum; best_row = tst_row; best_filter = PNG_FILTER_VALUE_AVG; } } /* Paeth filter */ if (filter_to_do == PNG_FILTER_PAETH) { png_bytep tst_row = test_buffer(png_ptr, best_row); (void)png_setup_paeth_row(bpp, row_bytes, 0, row_buf, prev_row, tst_row); best_row = tst_row; best_filter = PNG_FILTER_VALUE_PAETH; } else if ((filter_to_do & PNG_FILTER_PAETH) != 0) { png_size_t sum; png_bytep tst_row = test_buffer(png_ptr, best_row); sum = png_setup_paeth_row(bpp, row_bytes, mins, row_buf, prev_row, tst_row); if (sum < mins) { mins = sum; best_row = tst_row; best_filter = PNG_FILTER_VALUE_PAETH; } } /* Do the actual writing of the filtered row data from the chosen filter. */ affirm(best_filter < PNG_FILTER_VALUE_LAST); *filter_byte = best_filter; return best_row; } #endif /* WRITE_FILTER */ #endif /* WRITE */