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Quellcode-Bibliothek pngrutil.c
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/* pngrutil.c - utilities to read a PNG file * * Copyright (c) 2018-2025 Cosmin Truta * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson * Copyright (c) 1996-1997 Andreas Dilger * 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 * * This file contains routines that are only called from within * libpng itself during the course of reading an image. */ #include "pngpriv.h" #ifdef PNG_READ_SUPPORTED /* The minimum 'zlib' stream is assumed to be just the 2 byte header, 5 bytes * minimum 'deflate' stream, and the 4 byte checksum. */ #define LZ77Min (2U+5U+4U) #ifdef PNG_READ_INTERLACING_SUPPORTED /* Arrays to facilitate interlacing - use pass (0 - 6) as index. */ /* Start of interlace block */ static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; /* Offset to next interlace block */ static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; /* Start of interlace block in the y direction */ static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1}; /* Offset to next interlace block in the y direction */ static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2}; /* TODO: Move these arrays to a common utility module to avoid duplication. */ #endif png_uint_32 PNGAPI png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf) { png_uint_32 uval = png_get_uint_32(buf); if (uval > PNG_UINT_31_MAX) png_error(png_ptr, "PNG unsigned integer out of range"); return uval; } #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED /* NOTE: the read macros will obscure these definitions, so that if * PNG_USE_READ_MACROS is set the library will not use them internally, * but the APIs will still be available externally. * * The parentheses around "PNGAPI function_name" in the following three * functions are necessary because they allow the macros to co-exist with * these (unused but exported) functions. */ /* Grab an unsigned 32-bit integer from a buffer in big-endian format. */ png_uint_32 (PNGAPI png_get_uint_32)(png_const_bytep buf) { png_uint_32 uval = ((png_uint_32)(*(buf )) << 24) + ((png_uint_32)(*(buf + 1)) << 16) + ((png_uint_32)(*(buf + 2)) << 8) + ((png_uint_32)(*(buf + 3)) ) ; return uval; } /* Grab a signed 32-bit integer from a buffer in big-endian format. The * data is stored in the PNG file in two's complement format and there * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore * the following code does a two's complement to native conversion. */ png_int_32 (PNGAPI png_get_int_32)(png_const_bytep buf) { png_uint_32 uval = png_get_uint_32(buf); if ((uval & 0x80000000) == 0) /* non-negative */ return (png_int_32)uval; uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */ if ((uval & 0x80000000) == 0) /* no overflow */ return -(png_int_32)uval; /* The following has to be safe; this function only gets called on PNG data * and if we get here that data is invalid. 0 is the most safe value and * if not then an attacker would surely just generate a PNG with 0 instead. */ return 0; } /* Grab an unsigned 16-bit integer from a buffer in big-endian format. */ png_uint_16 (PNGAPI png_get_uint_16)(png_const_bytep buf) { /* ANSI-C requires an int value to accommodate at least 16 bits so this * works and allows the compiler not to worry about possible narrowing * on 32-bit systems. (Pre-ANSI systems did not make integers smaller * than 16 bits either.) */ unsigned int val = ((unsigned int)(*buf) << 8) + ((unsigned int)(*(buf + 1))); return (png_uint_16)val; } #endif /* READ_INT_FUNCTIONS */ /* Read and check the PNG file signature */ void /* PRIVATE */ png_read_sig(png_structrp png_ptr, png_inforp info_ptr) { size_t num_checked, num_to_check; /* Exit if the user application does not expect a signature. */ if (png_ptr->sig_bytes >= 8) return; num_checked = png_ptr->sig_bytes; num_to_check = 8 - num_checked; #ifdef PNG_IO_STATE_SUPPORTED png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE; #endif /* The signature must be serialized in a single I/O call. */ png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check); png_ptr->sig_bytes = 8; if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check) != 0) { if (num_checked < 4 && png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4) != 0) png_error(png_ptr, "Not a PNG file"); else png_error(png_ptr, "PNG file corrupted by ASCII conversion"); } if (num_checked < 3) png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE; } /* This function is called to verify that a chunk name is valid. * Do this using the bit-whacking approach from contrib/tools/pngfix.c * * Copied from libpng 1.7. */ static int check_chunk_name(png_uint_32 name) { png_uint_32 t; /* Remove bit 5 from all but the reserved byte; this means * every 8-bit unit must be in the range 65-90 to be valid. * So bit 5 must be zero, bit 6 must be set and bit 7 zero. */ name &= ~PNG_U32(32,32,0,32); t = (name & ~0x1f1f1f1fU) ^ 0x40404040U; /* Subtract 65 for each 8-bit quantity, this must not * overflow and each byte must then be in the range 0-25. */ name -= PNG_U32(65,65,65,65); t |= name; /* Subtract 26, handling the overflow which should set the * top three bits of each byte. */ name -= PNG_U32(25,25,25,26); t |= ~name; return (t & 0xe0e0e0e0U) == 0U; } /* Read the chunk header (length + type name). * Put the type name into png_ptr->chunk_name, and return the length. */ png_uint_32 /* PRIVATE */ png_read_chunk_header(png_structrp png_ptr) { png_byte buf[8]; png_uint_32 chunk_name, length; #ifdef PNG_IO_STATE_SUPPORTED png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR; #endif /* Read the length and the chunk name. png_struct::chunk_name is immediately * updated even if they are detectably wrong. This aids error message * handling by allowing png_chunk_error to be used. */ png_read_data(png_ptr, buf, 8); length = png_get_uint_31(png_ptr, buf); png_ptr->chunk_name = chunk_name = PNG_CHUNK_FROM_STRING(buf+4); /* Reset the crc and run it over the chunk name. */ png_reset_crc(png_ptr); png_calculate_crc(png_ptr, buf + 4, 4); png_debug2(0, "Reading chunk typeid = 0x%lx, length = %lu", (unsigned long)png_ptr->chunk_name, (unsigned long)length); /* Sanity check the length (first by <= 0x80) and the chunk name. An error * here indicates a broken stream and libpng has no recovery from this. */ if (buf[0] >= 0x80U) png_chunk_error(png_ptr, "bad header (invalid length)"); /* Check to see if chunk name is valid. */ if (!check_chunk_name(chunk_name)) png_chunk_error(png_ptr, "bad header (invalid type)"); #ifdef PNG_IO_STATE_SUPPORTED png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA; #endif return length; } /* Read data, and (optionally) run it through the CRC. */ void /* PRIVATE */ png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length) { if (png_ptr == NULL) return; png_read_data(png_ptr, buf, length); png_calculate_crc(png_ptr, buf, length); } /* Compare the CRC stored in the PNG file with that calculated by libpng from * the data it has read thus far. */ static int png_crc_error(png_structrp png_ptr, int handle_as_ancillary) { png_byte crc_bytes[4]; png_uint_32 crc; int need_crc = 1; /* There are four flags two for ancillary and two for critical chunks. The * default setting of these flags is all zero. * * PNG_FLAG_CRC_ANCILLARY_USE * PNG_FLAG_CRC_ANCILLARY_NOWARN * USE+NOWARN: no CRC calculation (implemented here), else; * NOWARN: png_chunk_error on error (implemented in png_crc_finish) * else: png_chunk_warning on error (implemented in png_crc_finish) * This is the default. * * I.e. NOWARN without USE produces png_chunk_error. The default setting * where neither are set does the same thing. * * PNG_FLAG_CRC_CRITICAL_USE * PNG_FLAG_CRC_CRITICAL_IGNORE * IGNORE: no CRC calculation (implemented here), else; * USE: png_chunk_warning on error (implemented in png_crc_finish) * else: png_chunk_error on error (implemented in png_crc_finish) * This is the default. * * This arose because of original mis-implementation and has persisted for * compatibility reasons. * * TODO: the flag names are internal so maybe this can be changed to * something comprehensible. */ if (handle_as_ancillary || PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0) { if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) == (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN)) need_crc = 0; } else /* critical */ { if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0) need_crc = 0; } #ifdef PNG_IO_STATE_SUPPORTED png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC; #endif /* The chunk CRC must be serialized in a single I/O call. */ png_read_data(png_ptr, crc_bytes, 4); if (need_crc != 0) { crc = png_get_uint_32(crc_bytes); return crc != png_ptr->crc; } else return 0; } /* Optionally skip data and then check the CRC. Depending on whether we * are reading an ancillary or critical chunk, and how the program has set * things up, we may calculate the CRC on the data and print a message. * Returns '1' if there was a CRC error, '0' otherwise. * * There is one public version which is used in most places and another which * takes the value for the 'critical' flag to check. This allows PLTE and IEND * handling code to ignore the CRC error and removes some confusing code * duplication. */ static int png_crc_finish_critical(png_structrp png_ptr, png_uint_32 skip, int handle_as_ancillary) { /* The size of the local buffer for inflate is a good guess as to a * reasonable size to use for buffering reads from the application. */ while (skip > 0) { png_uint_32 len; png_byte tmpbuf[PNG_INFLATE_BUF_SIZE]; len = (sizeof tmpbuf); if (len > skip) len = skip; skip -= len; png_crc_read(png_ptr, tmpbuf, len); } /* If 'handle_as_ancillary' has been requested and this is a critical chunk * but PNG_FLAG_CRC_CRITICAL_IGNORE was set then png_read_crc did not, in * fact, calculate the CRC so the ANCILLARY settings should not be used * instead. */ if (handle_as_ancillary && (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0) handle_as_ancillary = 0; /* TODO: this might be more comprehensible if png_crc_error was inlined here. */ if (png_crc_error(png_ptr, handle_as_ancillary) != 0) { /* See above for the explanation of how the flags work. */ if (handle_as_ancillary || PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0 ? (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0 : (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE) != 0) png_chunk_warning(png_ptr, "CRC error"); else png_chunk_error(png_ptr, "CRC error"); return 1; } return 0; } int /* PRIVATE */ png_crc_finish(png_structrp png_ptr, png_uint_32 skip) { return png_crc_finish_critical(png_ptr, skip, 0/*critical handling*/); } #if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\ defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\ defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\ defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_READ_eXIf_SUPPORTED) ||\ defined(PNG_SEQUENTIAL_READ_SUPPORTED) /* Manage the read buffer; this simply reallocates the buffer if it is not small * enough (or if it is not allocated). The routine returns a pointer to the * buffer; if an error occurs and 'warn' is set the routine returns NULL, else * it will call png_error on failure. */ static png_bytep png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size) { png_bytep buffer = png_ptr->read_buffer; if (new_size > png_chunk_max(png_ptr)) return NULL; if (buffer != NULL && new_size > png_ptr->read_buffer_size) { png_ptr->read_buffer = NULL; png_ptr->read_buffer_size = 0; png_free(png_ptr, buffer); buffer = NULL; } if (buffer == NULL) { buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size)); if (buffer != NULL) { # ifndef PNG_NO_MEMZERO /* for detecting UIM bugs **only** */ memset(buffer, 0, new_size); /* just in case */ # endif png_ptr->read_buffer = buffer; png_ptr->read_buffer_size = new_size; } } return buffer; } #endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|eXIf|SEQUENTIAL_READ */ /* png_inflate_claim: claim the zstream for some nefarious purpose that involves * decompression. Returns Z_OK on success, else a zlib error code. It checks * the owner but, in final release builds, just issues a warning if some other * chunk apparently owns the stream. Prior to release it does a png_error. */ static int png_inflate_claim(png_structrp png_ptr, png_uint_32 owner) { if (png_ptr->zowner != 0) { char msg[64]; PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner); /* So the message that results is "<chunk> using zstream"; this is an * internal error, but is very useful for debugging. i18n requirements * are minimal. */ (void)png_safecat(msg, (sizeof msg), 4, " using zstream"); #if PNG_RELEASE_BUILD png_chunk_warning(png_ptr, msg); png_ptr->zowner = 0; #else png_chunk_error(png_ptr, msg); #endif } /* Implementation note: unlike 'png_deflate_claim' this internal function * does not take the size of the data as an argument. Some efficiency could * be gained by using this when it is known *if* the zlib stream itself does * not record the number; however, this is an illusion: the original writer * of the PNG may have selected a lower window size, and we really must * follow that because, for systems with limited capabilities, we * would otherwise reject the application's attempts to use a smaller window * size (zlib doesn't have an interface to say "this or lower"!). * * inflateReset2 was added to zlib 1.2.4; before this the window could not be * reset, therefore it is necessary to always allocate the maximum window * size with earlier zlibs just in case later compressed chunks need it. */ { int ret; /* zlib return code */ #if ZLIB_VERNUM >= 0x1240 int window_bits = 0; # if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_MAXIMUM_INFLATE_WINDOW) if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) == PNG_OPTION_ON) { window_bits = 15; png_ptr->zstream_start = 0; /* fixed window size */ } else { png_ptr->zstream_start = 1; } # endif #endif /* ZLIB_VERNUM >= 0x1240 */ /* Set this for safety, just in case the previous owner left pointers to * memory allocations. */ png_ptr->zstream.next_in = NULL; png_ptr->zstream.avail_in = 0; png_ptr->zstream.next_out = NULL; png_ptr->zstream.avail_out = 0; if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0) { #if ZLIB_VERNUM >= 0x1240 ret = inflateReset2(&png_ptr->zstream, window_bits); #else ret = inflateReset(&png_ptr->zstream); #endif } else { #if ZLIB_VERNUM >= 0x1240 ret = inflateInit2(&png_ptr->zstream, window_bits); #else ret = inflateInit(&png_ptr->zstream); #endif if (ret == Z_OK) png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED; } #ifdef PNG_DISABLE_ADLER32_CHECK_SUPPORTED if (((png_ptr->options >> PNG_IGNORE_ADLER32) & 3) == PNG_OPTION_ON) /* Turn off validation of the ADLER32 checksum in IDAT chunks */ ret = inflateValidate(&png_ptr->zstream, 0); #endif if (ret == Z_OK) png_ptr->zowner = owner; else png_zstream_error(png_ptr, ret); return ret; } #ifdef window_bits # undef window_bits #endif } #if ZLIB_VERNUM >= 0x1240 /* Handle the start of the inflate stream if we called inflateInit2(strm,0); * in this case some zlib versions skip validation of the CINFO field and, in * certain circumstances, libpng may end up displaying an invalid image, in * contrast to implementations that call zlib in the normal way (e.g. libpng * 1.5). */ int /* PRIVATE */ png_zlib_inflate(png_structrp png_ptr, int flush) { if (png_ptr->zstream_start && png_ptr->zstream.avail_in > 0) { if ((*png_ptr->zstream.next_in >> 4) > 7) { png_ptr->zstream.msg = "invalid window size (libpng)"; return Z_DATA_ERROR; } png_ptr->zstream_start = 0; } return inflate(&png_ptr->zstream, flush); } #endif /* Zlib >= 1.2.4 */ #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED #if defined(PNG_READ_zTXt_SUPPORTED) || defined (PNG_READ_iTXt_SUPPORTED) /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to * allow the caller to do multiple calls if required. If the 'finish' flag is * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and * Z_OK or Z_STREAM_END will be returned on success. * * The input and output sizes are updated to the actual amounts of data consumed * or written, not the amount available (as in a z_stream). The data pointers * are not changed, so the next input is (data+input_size) and the next * available output is (output+output_size). */ static int png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish, /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr, /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr) { if (png_ptr->zowner == owner) /* Else not claimed */ { int ret; png_alloc_size_t avail_out = *output_size_ptr; png_uint_32 avail_in = *input_size_ptr; /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it * can't even necessarily handle 65536 bytes) because the type uInt is * "16 bits or more". Consequently it is necessary to chunk the input to * zlib. This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the * maximum value that can be stored in a uInt.) It is possible to set * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have * a performance advantage, because it reduces the amount of data accessed * at each step and that may give the OS more time to page it in. */ png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input); /* avail_in and avail_out are set below from 'size' */ png_ptr->zstream.avail_in = 0; png_ptr->zstream.avail_out = 0; /* Read directly into the output if it is available (this is set to * a local buffer below if output is NULL). */ if (output != NULL) png_ptr->zstream.next_out = output; do { uInt avail; Byte local_buffer[PNG_INFLATE_BUF_SIZE]; /* zlib INPUT BUFFER */ /* The setting of 'avail_in' used to be outside the loop; by setting it * inside it is possible to chunk the input to zlib and simply rely on * zlib to advance the 'next_in' pointer. This allows arbitrary * amounts of data to be passed through zlib at the unavoidable cost of * requiring a window save (memcpy of up to 32768 output bytes) * every ZLIB_IO_MAX input bytes. */ avail_in += png_ptr->zstream.avail_in; /* not consumed last time */ avail = ZLIB_IO_MAX; if (avail_in < avail) avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */ avail_in -= avail; png_ptr->zstream.avail_in = avail; /* zlib OUTPUT BUFFER */ avail_out += png_ptr->zstream.avail_out; /* not written last time */ avail = ZLIB_IO_MAX; /* maximum zlib can process */ if (output == NULL) { /* Reset the output buffer each time round if output is NULL and * make available the full buffer, up to 'remaining_space' */ png_ptr->zstream.next_out = local_buffer; if ((sizeof local_buffer) < avail) avail = (sizeof local_buffer); } if (avail_out < avail) avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */ png_ptr->zstream.avail_out = avail; avail_out -= avail; /* zlib inflate call */ /* In fact 'avail_out' may be 0 at this point, that happens at the end * of the read when the final LZ end code was not passed at the end of * the previous chunk of input data. Tell zlib if we have reached the * end of the output buffer. */ ret = PNG_INFLATE(png_ptr, avail_out > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH)); } while (ret == Z_OK); /* For safety kill the local buffer pointer now */ if (output == NULL) png_ptr->zstream.next_out = NULL; /* Claw back the 'size' and 'remaining_space' byte counts. */ avail_in += png_ptr->zstream.avail_in; avail_out += png_ptr->zstream.avail_out; /* Update the input and output sizes; the updated values are the amount * consumed or written, effectively the inverse of what zlib uses. */ if (avail_out > 0) *output_size_ptr -= avail_out; if (avail_in > 0) *input_size_ptr -= avail_in; /* Ensure png_ptr->zstream.msg is set (even in the success case!) */ png_zstream_error(png_ptr, ret); return ret; } else { /* This is a bad internal error. The recovery assigns to the zstream msg * pointer, which is not owned by the caller, but this is safe; it's only * used on errors! */ png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed"); return Z_STREAM_ERROR; } } /* * Decompress trailing data in a chunk. The assumption is that read_buffer * points at an allocated area holding the contents of a chunk with a * trailing compressed part. What we get back is an allocated area * holding the original prefix part and an uncompressed version of the * trailing part (the malloc area passed in is freed). */ static int png_decompress_chunk(png_structrp png_ptr, png_uint_32 chunklength, png_uint_32 prefix_size, png_alloc_size_t *newlength /* must be initialized to the maximum! */, int terminate /*add a '\0' to the end of the uncompressed data*/) { /* TODO: implement different limits for different types of chunk. * * The caller supplies *newlength set to the maximum length of the * uncompressed data, but this routine allocates space for the prefix and * maybe a '\0' terminator too. We have to assume that 'prefix_size' is * limited only by the maximum chunk size. */ png_alloc_size_t limit = png_chunk_max(png_ptr); if (limit >= prefix_size + (terminate != 0)) { int ret; limit -= prefix_size + (terminate != 0); if (limit < *newlength) *newlength = limit; /* Now try to claim the stream. */ ret = png_inflate_claim(png_ptr, png_ptr->chunk_name); if (ret == Z_OK) { png_uint_32 lzsize = chunklength - prefix_size; ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/, /* input: */ png_ptr->read_buffer + prefix_size, &lzsize, /* output: */ NULL, newlength); if (ret == Z_STREAM_END) { /* Use 'inflateReset' here, not 'inflateReset2' because this * preserves the previously decided window size (otherwise it would * be necessary to store the previous window size.) In practice * this doesn't matter anyway, because png_inflate will call inflate * with Z_FINISH in almost all cases, so the window will not be * maintained. */ if (inflateReset(&png_ptr->zstream) == Z_OK) { /* Because of the limit checks above we know that the new, * expanded, size will fit in a size_t (let alone an * png_alloc_size_t). Use png_malloc_base here to avoid an * extra OOM message. */ png_alloc_size_t new_size = *newlength; png_alloc_size_t buffer_size = prefix_size + new_size + (terminate != 0); png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr, buffer_size)); if (text != NULL) { memset(text, 0, buffer_size); ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/, png_ptr->read_buffer + prefix_size, &lzsize, text + prefix_size, newlength); if (ret == Z_STREAM_END) { if (new_size == *newlength) { if (terminate != 0) text[prefix_size + *newlength] = 0; if (prefix_size > 0) memcpy(text, png_ptr->read_buffer, prefix_size); { png_bytep old_ptr = png_ptr->read_buffer; png_ptr->read_buffer = text; png_ptr->read_buffer_size = buffer_size; text = old_ptr; /* freed below */ } } else { /* The size changed on the second read, there can be no * guarantee that anything is correct at this point. * The 'msg' pointer has been set to "unexpected end of * LZ stream", which is fine, but return an error code * that the caller won't accept. */ ret = PNG_UNEXPECTED_ZLIB_RETURN; } } else if (ret == Z_OK) ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */ /* Free the text pointer (this is the old read_buffer on * success) */ png_free(png_ptr, text); /* This really is very benign, but it's still an error because * the extra space may otherwise be used as a Trojan Horse. */ if (ret == Z_STREAM_END && chunklength - prefix_size != lzsize) png_chunk_benign_error(png_ptr, "extra compressed data"); } else { /* Out of memory allocating the buffer */ ret = Z_MEM_ERROR; png_zstream_error(png_ptr, Z_MEM_ERROR); } } else { /* inflateReset failed, store the error message */ png_zstream_error(png_ptr, ret); ret = PNG_UNEXPECTED_ZLIB_RETURN; } } else if (ret == Z_OK) ret = PNG_UNEXPECTED_ZLIB_RETURN; /* Release the claimed stream */ png_ptr->zowner = 0; } else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */ ret = PNG_UNEXPECTED_ZLIB_RETURN; return ret; } else { /* Application/configuration limits exceeded */ png_zstream_error(png_ptr, Z_MEM_ERROR); return Z_MEM_ERROR; } } #endif /* READ_zTXt || READ_iTXt */ #endif /* READ_COMPRESSED_TEXT */ #ifdef PNG_READ_iCCP_SUPPORTED /* Perform a partial read and decompress, producing 'avail_out' bytes and * reading from the current chunk as required. */ static int png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size, png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size, int finish) { if (png_ptr->zowner == png_ptr->chunk_name) { int ret; /* next_in and avail_in must have been initialized by the caller. */ png_ptr->zstream.next_out = next_out; png_ptr->zstream.avail_out = 0; /* set in the loop */ do { if (png_ptr->zstream.avail_in == 0) { if (read_size > *chunk_bytes) read_size = (uInt)*chunk_bytes; *chunk_bytes -= read_size; if (read_size > 0) png_crc_read(png_ptr, read_buffer, read_size); png_ptr->zstream.next_in = read_buffer; png_ptr->zstream.avail_in = read_size; } if (png_ptr->zstream.avail_out == 0) { uInt avail = ZLIB_IO_MAX; if (avail > *out_size) avail = (uInt)*out_size; *out_size -= avail; png_ptr->zstream.avail_out = avail; } /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all * the available output is produced; this allows reading of truncated * streams. */ ret = PNG_INFLATE(png_ptr, *chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH)); } while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0)); *out_size += png_ptr->zstream.avail_out; png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */ /* Ensure the error message pointer is always set: */ png_zstream_error(png_ptr, ret); return ret; } else { png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed"); return Z_STREAM_ERROR; } } #endif /* READ_iCCP */ /* CHUNK HANDLING */ /* Read and check the IDHR chunk */ static png_handle_result_code png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_byte buf[13]; png_uint_32 width, height; int bit_depth, color_type, compression_type, filter_type; int interlace_type; png_debug(1, "in png_handle_IHDR"); /* Length and position are checked by the caller. */ png_ptr->mode |= PNG_HAVE_IHDR; png_crc_read(png_ptr, buf, 13); png_crc_finish(png_ptr, 0); width = png_get_uint_31(png_ptr, buf); height = png_get_uint_31(png_ptr, buf + 4); bit_depth = buf[8]; color_type = buf[9]; compression_type = buf[10]; filter_type = buf[11]; interlace_type = buf[12]; #ifdef PNG_READ_APNG_SUPPORTED png_ptr->first_frame_width = width; png_ptr->first_frame_height = height; #endif /* Set internal variables */ png_ptr->width = width; png_ptr->height = height; png_ptr->bit_depth = (png_byte)bit_depth; png_ptr->interlaced = (png_byte)interlace_type; png_ptr->color_type = (png_byte)color_type; #ifdef PNG_MNG_FEATURES_SUPPORTED png_ptr->filter_type = (png_byte)filter_type; #endif png_ptr->compression_type = (png_byte)compression_type; /* Find number of channels */ switch (png_ptr->color_type) { default: /* invalid, png_set_IHDR calls png_error */ case PNG_COLOR_TYPE_GRAY: case PNG_COLOR_TYPE_PALETTE: png_ptr->channels = 1; break; case PNG_COLOR_TYPE_RGB: png_ptr->channels = 3; break; case PNG_COLOR_TYPE_GRAY_ALPHA: png_ptr->channels = 2; break; case PNG_COLOR_TYPE_RGB_ALPHA: png_ptr->channels = 4; break; } /* Set up other useful info */ png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth * png_ptr->channels); png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width); png_debug1(3, "bit_depth = %d", png_ptr->bit_depth); png_debug1(3, "channels = %d", png_ptr->channels); png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes); /* Rely on png_set_IHDR to completely validate the data and call png_error if * it's wrong. */ png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, interlace_type, compression_type, filter_type); return handled_ok; PNG_UNUSED(length) } /* Read and check the palette */ /* TODO: there are several obvious errors in this code when handling * out-of-place chunks and there is much over-complexity caused by trying to * patch up the problems. */ static png_handle_result_code png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_const_charp errmsg = NULL; png_debug(1, "in png_handle_PLTE"); /* 1.6.47: consistency. This used to be especially treated as a critical * error even in an image which is not colour mapped, there isn't a good * justification for treating some errors here one way and others another so * everything uses the same logic. */ if ((png_ptr->mode & PNG_HAVE_PLTE) != 0) errmsg = "duplicate"; else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) errmsg = "out of place"; else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) errmsg = "ignored in grayscale PNG"; else if (length > 3*PNG_MAX_PALETTE_LENGTH || (length % 3) != 0) errmsg = "invalid"; /* This drops PLTE in favour of tRNS or bKGD because both of those chunks * can have an effect on the rendering of the image whereas PLTE only matters * in the case of an 8-bit display with a decoder which controls the palette. * * The alternative here is to ignore the error and store the palette anyway; * destroying the tRNS will definitely cause problems. * * NOTE: the case of PNG_COLOR_TYPE_PALETTE need not be considered because * the png_handle_ routines for the three 'after PLTE' chunks tRNS, bKGD and * hIST all check for a preceding PLTE in these cases. */ else if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE && (png_has_chunk(png_ptr, tRNS) || png_has_chunk(png_ptr, bKGD))) errmsg = "out of place"; else { /* If the palette has 256 or fewer entries but is too large for the bit * depth we don't issue an error to preserve the behavior of previous * libpng versions. We silently truncate the unused extra palette entries * here. */ const unsigned max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ? 1U << png_ptr->bit_depth : PNG_MAX_PALETTE_LENGTH; /* The cast is safe because 'length' is less than * 3*PNG_MAX_PALETTE_LENGTH */ const unsigned num = (length > 3U*max_palette_length) ? max_palette_length : (unsigned)length / 3U; unsigned i, j; png_byte buf[3*PNG_MAX_PALETTE_LENGTH]; png_color palette[PNG_MAX_PALETTE_LENGTH]; /* Read the chunk into the buffer then read to the end of the chunk. */ png_crc_read(png_ptr, buf, num*3U); png_crc_finish_critical(png_ptr, length - 3U*num, /* Handle as ancillary if PLTE is optional: */ png_ptr->color_type != PNG_COLOR_TYPE_PALETTE); for (i = 0U, j = 0U; i < num; i++) { palette[i].red = buf[j++]; palette[i].green = buf[j++]; palette[i].blue = buf[j++]; } /* A valid PLTE chunk has been read */ png_ptr->mode |= PNG_HAVE_PLTE; png_set_PLTE(png_ptr, info_ptr, palette, num); return handled_ok; } /* Here on error: errmsg is non NULL. */ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { png_crc_finish(png_ptr, length); png_chunk_error(png_ptr, errmsg); } else /* not critical to this image */ { png_crc_finish_critical(png_ptr, length, 1/*handle as ancillary*/); png_chunk_benign_error(png_ptr, errmsg); } /* Because PNG_UNUSED(errmsg) does not work if all the uses are compiled out * (this does happen). */ return errmsg != NULL ? handled_error : handled_error; } /* On read the IDAT chunk is always handled specially, even if marked for * unknown handling (this is allowed), so: */ #define png_handle_IDAT NULL static png_handle_result_code png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_debug(1, "in png_handle_IEND"); png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND); if (length != 0) png_chunk_benign_error(png_ptr, "invalid"); png_crc_finish_critical(png_ptr, length, 1/*handle as ancillary*/); return handled_ok; PNG_UNUSED(info_ptr) } #ifdef PNG_READ_gAMA_SUPPORTED static png_handle_result_code png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_uint_32 ugamma; png_byte buf[4]; png_debug(1, "in png_handle_gAMA"); png_crc_read(png_ptr, buf, 4); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; ugamma = png_get_uint_32(buf); if (ugamma > PNG_UINT_31_MAX) { png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } png_set_gAMA_fixed(png_ptr, info_ptr, (png_fixed_point)/*SAFE*/ugamma); #ifdef PNG_READ_GAMMA_SUPPORTED /* PNGv3: chunk precedence for gamma is cICP, [iCCP], sRGB, gAMA. gAMA is * at the end of the chain so simply check for an unset value. */ if (png_ptr->chunk_gamma == 0) png_ptr->chunk_gamma = (png_fixed_point)/*SAFE*/ugamma; #endif /*READ_GAMMA*/ return handled_ok; PNG_UNUSED(length) } #else # define png_handle_gAMA NULL #endif #ifdef PNG_READ_sBIT_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { unsigned int truelen, i; png_byte sample_depth; png_byte buf[4]; png_debug(1, "in png_handle_sBIT"); if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { truelen = 3; sample_depth = 8; } else { truelen = png_ptr->channels; sample_depth = png_ptr->bit_depth; } if (length != truelen) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "bad length"); return handled_error; } buf[0] = buf[1] = buf[2] = buf[3] = sample_depth; png_crc_read(png_ptr, buf, truelen); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; for (i=0; i<truelen; ++i) { if (buf[i] == 0 || buf[i] > sample_depth) { png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } } if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) { png_ptr->sig_bit.red = buf[0]; png_ptr->sig_bit.green = buf[1]; png_ptr->sig_bit.blue = buf[2]; png_ptr->sig_bit.alpha = buf[3]; } else /* grayscale */ { png_ptr->sig_bit.gray = buf[0]; png_ptr->sig_bit.red = buf[0]; png_ptr->sig_bit.green = buf[0]; png_ptr->sig_bit.blue = buf[0]; png_ptr->sig_bit.alpha = buf[1]; } png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit)); return handled_ok; } #else # define png_handle_sBIT NULL #endif #ifdef PNG_READ_cHRM_SUPPORTED static png_int_32 png_get_int_32_checked(png_const_bytep buf, int *error) { png_uint_32 uval = png_get_uint_32(buf); if ((uval & 0x80000000) == 0) /* non-negative */ return (png_int_32)uval; uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */ if ((uval & 0x80000000) == 0) /* no overflow */ return -(png_int_32)uval; /* This version of png_get_int_32 has a way of returning the error to the * caller, so: */ *error = 1; return 0; /* Safe */ } static png_handle_result_code /* PRIVATE */ png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { int error = 0; png_xy xy; png_byte buf[32]; png_debug(1, "in png_handle_cHRM"); png_crc_read(png_ptr, buf, 32); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; xy.whitex = png_get_int_32_checked(buf + 0, &error); xy.whitey = png_get_int_32_checked(buf + 4, &error); xy.redx = png_get_int_32_checked(buf + 8, &error); xy.redy = png_get_int_32_checked(buf + 12, &error); xy.greenx = png_get_int_32_checked(buf + 16, &error); xy.greeny = png_get_int_32_checked(buf + 20, &error); xy.bluex = png_get_int_32_checked(buf + 24, &error); xy.bluey = png_get_int_32_checked(buf + 28, &error); if (error) { png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } /* png_set_cHRM may complain about some of the values but this doesn't matter * because it was a cHRM and it did have vaguely (if, perhaps, ridiculous) * values. Ridiculosity will be checked if the values are used later. */ png_set_cHRM_fixed(png_ptr, info_ptr, xy.whitex, xy.whitey, xy.redx, xy.redy, xy.greenx, xy.greeny, xy.bluex, xy.bluey); /* We only use 'chromaticities' for RGB to gray */ # ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED /* There is no need to check sRGB here, cICP is NYI and iCCP is not * supported so just check mDCV. */ if (!png_has_chunk(png_ptr, mDCV)) { png_ptr->chromaticities = xy; } # endif /* READ_RGB_TO_GRAY */ return handled_ok; PNG_UNUSED(length) } #else # define png_handle_cHRM NULL #endif #ifdef PNG_READ_sRGB_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_byte intent; png_debug(1, "in png_handle_sRGB"); png_crc_read(png_ptr, &intent, 1); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; /* This checks the range of the "rendering intent" because it is specified in * the PNG spec itself; the "reserved" values will result in the chunk not * being accepted, just as they do with the various "reserved" values in * IHDR. */ if (intent > 3/*PNGv3 spec*/) { png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } png_set_sRGB(png_ptr, info_ptr, intent); /* NOTE: png_struct::chromaticities is not set here because the RGB to gray * coefficients are known without a need for the chromaticities. */ #ifdef PNG_READ_GAMMA_SUPPORTED /* PNGv3: chunk precedence for gamma is cICP, [iCCP], sRGB, gAMA. iCCP is * not supported by libpng so the only requirement is to check for cICP * setting the gamma (this is NYI, but this check is safe.) */ if (!png_has_chunk(png_ptr, cICP) || png_ptr->chunk_gamma == 0) png_ptr->chunk_gamma = PNG_GAMMA_sRGB_INVERSE; #endif /*READ_GAMMA*/ return handled_ok; PNG_UNUSED(length) } #else # define png_handle_sRGB NULL #endif /* READ_sRGB */ #ifdef PNG_READ_iCCP_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) /* Note: this does not properly handle profiles that are > 64K under DOS */ { png_const_charp errmsg = NULL; /* error message output, or no error */ int finished = 0; /* crc checked */ png_debug(1, "in png_handle_iCCP"); /* PNGv3: allow PNG files with both sRGB and iCCP because the PNG spec only * ever said that there "should" be only one, not "shall" and the PNGv3 * colour chunk precedence rules give a handling for this case anyway. */ { uInt read_length, keyword_length; char keyword[81]; /* Find the keyword; the keyword plus separator and compression method * bytes can be at most 81 characters long. */ read_length = 81; /* maximum */ if (read_length > length) read_length = (uInt)/*SAFE*/length; png_crc_read(png_ptr, (png_bytep)keyword, read_length); length -= read_length; if (length < LZ77Min) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "too short"); return handled_error; } keyword_length = 0; while (keyword_length < 80 && keyword_length < read_length && keyword[keyword_length] != 0) ++keyword_length; /* TODO: make the keyword checking common */ if (keyword_length >= 1 && keyword_length <= 79) { /* We only understand '0' compression - deflate - so if we get a * different value we can't safely decode the chunk. */ if (keyword_length+1 < read_length && keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE) { read_length -= keyword_length+2; if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK) { Byte profile_header[132]={0}; Byte local_buffer[PNG_INFLATE_BUF_SIZE]; png_alloc_size_t size = (sizeof profile_header); png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2); png_ptr->zstream.avail_in = read_length; (void)png_inflate_read(png_ptr, local_buffer, (sizeof local_buffer), &length, profile_header, &size, 0/*finish: don't, because the output is too small*/); if (size == 0) { /* We have the ICC profile header; do the basic header checks. */ png_uint_32 profile_length = png_get_uint_32(profile_header); if (png_icc_check_length(png_ptr, keyword, profile_length) != 0) { /* The length is apparently ok, so we can check the 132 * byte header. */ if (png_icc_check_header(png_ptr, keyword, profile_length, profile_header, png_ptr->color_type) != 0) { /* Now read the tag table; a variable size buffer is * needed at this point, allocate one for the whole * profile. The header check has already validated * that none of this stuff will overflow. */ png_uint_32 tag_count = png_get_uint_32(profile_header + 128); png_bytep profile = png_read_buffer(png_ptr, profile_length); if (profile != NULL) { memcpy(profile, profile_header, (sizeof profile_header)); size = 12 * tag_count; (void)png_inflate_read(png_ptr, local_buffer, (sizeof local_buffer), &length, profile + (sizeof profile_header), &size, 0); /* Still expect a buffer error because we expect * there to be some tag data! */ if (size == 0) { if (png_icc_check_tag_table(png_ptr, keyword, profile_length, profile) != 0) { /* The profile has been validated for basic * security issues, so read the whole thing in. */ size = profile_length - (sizeof profile_header) - 12 * tag_count; (void)png_inflate_read(png_ptr, local_buffer, (sizeof local_buffer), &length, profile + (sizeof profile_header) + 12 * tag_count, &size, 1/*finish*/); if (length > 0 && !(png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)) errmsg = "extra compressed data"; /* But otherwise allow extra data: */ else if (size == 0) { if (length > 0) { /* This can be handled completely, so * keep going. */ png_chunk_warning(png_ptr, "extra compressed data"); } png_crc_finish(png_ptr, length); finished = 1; /* Steal the profile for info_ptr. */ if (info_ptr != NULL) { png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, 0); info_ptr->iccp_name = png_voidcast(char*, png_malloc_base(png_ptr, keyword_length+1)); if (info_ptr->iccp_name != NULL) { memcpy(info_ptr->iccp_name, keyword, keyword_length+1); info_ptr->iccp_proflen = profile_length; info_ptr->iccp_profile = profile; png_ptr->read_buffer = NULL; /*steal*/ info_ptr->free_me |= PNG_FREE_ICCP; info_ptr->valid |= PNG_INFO_iCCP; } else errmsg = "out of memory"; } /* else the profile remains in the read * buffer which gets reused for subsequent * chunks. */ if (errmsg == NULL) { png_ptr->zowner = 0; return handled_ok; } } if (errmsg == NULL) errmsg = png_ptr->zstream.msg; } /* else png_icc_check_tag_table output an error */ } else /* profile truncated */ errmsg = png_ptr->zstream.msg; } else errmsg = "out of memory"; } /* else png_icc_check_header output an error */ } /* else png_icc_check_length output an error */ } else /* profile truncated */ errmsg = png_ptr->zstream.msg; /* Release the stream */ png_ptr->zowner = 0; } else /* png_inflate_claim failed */ errmsg = png_ptr->zstream.msg; } else errmsg = "bad compression method"; /* or missing */ } else errmsg = "bad keyword"; } /* Failure: the reason is in 'errmsg' */ if (finished == 0) png_crc_finish(png_ptr, length); if (errmsg != NULL) /* else already output */ png_chunk_benign_error(png_ptr, errmsg); return handled_error; } #else # define png_handle_iCCP NULL #endif /* READ_iCCP */ #ifdef PNG_READ_sPLT_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) /* Note: this does not properly handle chunks that are > 64K under DOS */ { png_bytep buffer; png_bytep entry_start; png_sPLT_t new_palette; png_sPLT_entryp pp; png_uint_32 data_length; int entry_size, i; png_uint_32 skip = 0; png_uint_32 dl; size_t max_dl; png_debug(1, "in png_handle_sPLT"); #ifdef PNG_USER_LIMITS_SUPPORTED if (png_ptr->user_chunk_cache_max != 0) { if (png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); return handled_error; } if (--png_ptr->user_chunk_cache_max == 1) { png_warning(png_ptr, "No space in chunk cache for sPLT"); png_crc_finish(png_ptr, length); return handled_error; } } #endif buffer = png_read_buffer(png_ptr, length+1); if (buffer == NULL) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "out of memory"); return handled_error; } /* WARNING: this may break if size_t is less than 32 bits; it is assumed * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a * potential breakage point if the types in pngconf.h aren't exactly right. */ png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, skip) != 0) return handled_error; buffer[length] = 0; for (entry_start = buffer; *entry_start; entry_start++) /* Empty loop to find end of name */ ; ++entry_start; /* A sample depth should follow the separator, and we should be on it */ if (length < 2U || entry_start > buffer + (length - 2U)) { png_warning(png_ptr, "malformed sPLT chunk"); return handled_error; } new_palette.depth = *entry_start++; entry_size = (new_palette.depth == 8 ? 6 : 10); /* This must fit in a png_uint_32 because it is derived from the original * chunk data length. */ data_length = length - (png_uint_32)(entry_start - buffer); /* Integrity-check the data length */ if ((data_length % (unsigned int)entry_size) != 0) { png_warning(png_ptr, "sPLT chunk has bad length"); return handled_error; } dl = (png_uint_32)(data_length / (unsigned int)entry_size); max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry)); if (dl > max_dl) { png_warning(png_ptr, "sPLT chunk too long"); return handled_error; } new_palette.nentries = (png_int_32)(data_length / (unsigned int)entry_size); new_palette.entries = (png_sPLT_entryp)png_malloc_warn(png_ptr, (png_alloc_size_t) new_palette.nentries * (sizeof (png_sPLT_entry))); if (new_palette.entries == NULL) { png_warning(png_ptr, "sPLT chunk requires too much memory"); return handled_error; } for (i = 0; i < new_palette.nentries; i++) { pp = new_palette.entries + i; if (new_palette.depth == 8) { pp->red = *entry_start++; pp->green = *entry_start++; pp->blue = *entry_start++; pp->alpha = *entry_start++; } else { pp->red = png_get_uint_16(entry_start); entry_start += 2; pp->green = png_get_uint_16(entry_start); entry_start += 2; pp->blue = png_get_uint_16(entry_start); entry_start += 2; pp->alpha = png_get_uint_16(entry_start); entry_start += 2; } pp->frequency = png_get_uint_16(entry_start); entry_start += 2; } /* Discard all chunk data except the name and stash that */ new_palette.name = (png_charp)buffer; png_set_sPLT(png_ptr, info_ptr, &new_palette, 1); png_free(png_ptr, new_palette.entries); return handled_ok; } #else # define png_handle_sPLT NULL #endif /* READ_sPLT */ #ifdef PNG_READ_tRNS_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_byte readbuf[PNG_MAX_PALETTE_LENGTH]; png_debug(1, "in png_handle_tRNS"); if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY) { png_byte buf[2]; if (length != 2) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } png_crc_read(png_ptr, buf, 2); png_ptr->num_trans = 1; png_ptr->trans_color.gray = png_get_uint_16(buf); } else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB) { png_byte buf[6]; if (length != 6) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } png_crc_read(png_ptr, buf, length); png_ptr->num_trans = 1; png_ptr->trans_color.red = png_get_uint_16(buf); png_ptr->trans_color.green = png_get_uint_16(buf + 2); png_ptr->trans_color.blue = png_get_uint_16(buf + 4); } else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { if ((png_ptr->mode & PNG_HAVE_PLTE) == 0) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "out of place"); return handled_error; } if (length > (unsigned int) png_ptr->num_palette || length > (unsigned int) PNG_MAX_PALETTE_LENGTH || length == 0) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } png_crc_read(png_ptr, readbuf, length); png_ptr->num_trans = (png_uint_16)length; } else { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid with alpha channel"); return handled_error; } if (png_crc_finish(png_ptr, 0) != 0) { png_ptr->num_trans = 0; return handled_error; } png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans, &(png_ptr->trans_color)); return handled_ok; } #else # define png_handle_tRNS NULL #endif #ifdef PNG_READ_bKGD_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { unsigned int truelen; png_byte buf[6]; png_color_16 background; png_debug(1, "in png_handle_bKGD"); if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { if ((png_ptr->mode & PNG_HAVE_PLTE) == 0) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "out of place"); return handled_error; } truelen = 1; } else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) truelen = 6; else truelen = 2; if (length != truelen) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } png_crc_read(png_ptr, buf, truelen); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; /* We convert the index value into RGB components so that we can allow * arbitrary RGB values for background when we have transparency, and * so it is easy to determine the RGB values of the background color * from the info_ptr struct. */ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { background.index = buf[0]; if (info_ptr != NULL && info_ptr->num_palette != 0) { if (buf[0] >= info_ptr->num_palette) { png_chunk_benign_error(png_ptr, "invalid index"); return handled_error; } background.red = (png_uint_16)png_ptr->palette[buf[0]].red; background.green = (png_uint_16)png_ptr->palette[buf[0]].green; background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue; } else background.red = background.green = background.blue = 0; background.gray = 0; } else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) /* GRAY */ { if (png_ptr->bit_depth <= 8) { if (buf[0] != 0 || buf[1] >= (unsigned int)(1 << png_ptr->bit_depth)) { png_chunk_benign_error(png_ptr, "invalid gray level"); return handled_error; } } background.index = 0; background.red = background.green = background.blue = background.gray = png_get_uint_16(buf); } else { if (png_ptr->bit_depth <= 8) { if (buf[0] != 0 || buf[2] != 0 || buf[4] != 0) { png_chunk_benign_error(png_ptr, "invalid color"); return handled_error; } } background.index = 0; background.red = png_get_uint_16(buf); background.green = png_get_uint_16(buf + 2); background.blue = png_get_uint_16(buf + 4); background.gray = 0; } png_set_bKGD(png_ptr, info_ptr, &background); return handled_ok; } #else # define png_handle_bKGD NULL #endif #ifdef PNG_READ_cICP_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_cICP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_byte buf[4]; png_debug(1, "in png_handle_cICP"); png_crc_read(png_ptr, buf, 4); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; png_set_cICP(png_ptr, info_ptr, buf[0], buf[1], buf[2], buf[3]); /* We only use 'chromaticities' for RGB to gray */ # ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED if (!png_has_chunk(png_ptr, mDCV)) { /* TODO: png_ptr->chromaticities = chromaticities; */ } # endif /* READ_RGB_TO_GRAY */ #ifdef PNG_READ_GAMMA_SUPPORTED /* PNGv3: chunk precedence for gamma is cICP, [iCCP], sRGB, gAMA. cICP is * at the head so simply set the gamma if it can be determined. If not * chunk_gamma remains unchanged; sRGB and gAMA handling check it for * being zero. */ /* TODO: set png_struct::chunk_gamma when possible */ #endif /*READ_GAMMA*/ return handled_ok; PNG_UNUSED(length) } #else # define png_handle_cICP NULL #endif #ifdef PNG_READ_cLLI_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_cLLI(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_byte buf[8]; png_debug(1, "in png_handle_cLLI"); png_crc_read(png_ptr, buf, 8); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; /* The error checking happens here, this puts it in just one place: */ png_set_cLLI_fixed(png_ptr, info_ptr, png_get_uint_32(buf), png_get_uint_32(buf+4)); return handled_ok; PNG_UNUSED(length) } #else # define png_handle_cLLI NULL #endif #ifdef PNG_READ_mDCV_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_mDCV(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_xy chromaticities; png_byte buf[24]; png_debug(1, "in png_handle_mDCV"); png_crc_read(png_ptr, buf, 24); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; /* The error checking happens here, this puts it in just one place. The * odd /50000 scaling factor makes it more difficult but the (x.y) values are * only two bytes so a <<1 is safe. * * WARNING: the PNG specification defines the cHRM chunk to **start** with * the white point (x,y). The W3C PNG v3 specification puts the white point * **after* R,G,B. The x,y values in mDCV are also scaled by 50,000 and * stored in just two bytes, whereas those in cHRM are scaled by 100,000 and * stored in four bytes. This is very, very confusing. These APIs remove * the confusion by copying the existing, well established, API. */ chromaticities.redx = png_get_uint_16(buf+ 0U) << 1; /* red x */ chromaticities.redy = png_get_uint_16(buf+ 2U) << 1; /* red y */ chromaticities.greenx = png_get_uint_16(buf+ 4U) << 1; /* green x */ chromaticities.greeny = png_get_uint_16(buf+ 6U) << 1; /* green y */ chromaticities.bluex = png_get_uint_16(buf+ 8U) << 1; /* blue x */ chromaticities.bluey = png_get_uint_16(buf+10U) << 1; /* blue y */ chromaticities.whitex = png_get_uint_16(buf+12U) << 1; /* white x */ chromaticities.whitey = png_get_uint_16(buf+14U) << 1; /* white y */ png_set_mDCV_fixed(png_ptr, info_ptr, chromaticities.whitex, chromaticities.whitey, chromaticities.redx, chromaticities.redy, chromaticities.greenx, chromaticities.greeny, chromaticities.bluex, chromaticities.bluey, png_get_uint_32(buf+16U), /* peak luminance */ png_get_uint_32(buf+20U));/* minimum perceivable luminance */ /* We only use 'chromaticities' for RGB to gray */ # ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED png_ptr->chromaticities = chromaticities; # endif /* READ_RGB_TO_GRAY */ return handled_ok; PNG_UNUSED(length) } #else # define png_handle_mDCV NULL #endif #ifdef PNG_READ_eXIf_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_bytep buffer = NULL; png_debug(1, "in png_handle_eXIf"); buffer = png_read_buffer(png_ptr, length); if (buffer == NULL) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "out of memory"); return handled_error; } png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; /* PNGv3: the code used to check the byte order mark at the start for MM or * II, however PNGv3 states that the first 4 bytes should be checked. * The caller ensures that there are four bytes available. */ { png_uint_32 header = png_get_uint_32(buffer); /* These numbers are copied from the PNGv3 spec: */ if (header != 0x49492A00 && header != 0x4D4D002A) { png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } } png_set_eXIf_1(png_ptr, info_ptr, length, buffer); return handled_ok; } #else # define png_handle_eXIf NULL #endif #ifdef PNG_READ_hIST_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { unsigned int num, i; png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH]; png_debug(1, "in png_handle_hIST"); /* This cast is safe because the chunk definition limits the length to a * maximum of 1024 bytes. * * TODO: maybe use png_uint_32 anyway, not unsigned int, to reduce the * casts. */ num = (unsigned int)length / 2 ; if (length != num * 2 || num != (unsigned int)png_ptr->num_palette || num > (unsigned int)PNG_MAX_PALETTE_LENGTH) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } for (i = 0; i < num; i++) { png_byte buf[2]; png_crc_read(png_ptr, buf, 2); readbuf[i] = png_get_uint_16(buf); } if (png_crc_finish(png_ptr, 0) != 0) return handled_error; png_set_hIST(png_ptr, info_ptr, readbuf); return handled_ok; } #else # define png_handle_hIST NULL #endif #ifdef PNG_READ_pHYs_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_byte buf[9]; png_uint_32 res_x, res_y; int unit_type; png_debug(1, "in png_handle_pHYs"); png_crc_read(png_ptr, buf, 9); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; res_x = png_get_uint_32(buf); res_y = png_get_uint_32(buf + 4); unit_type = buf[8]; png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type); return handled_ok; PNG_UNUSED(length) } #else # define png_handle_pHYs NULL #endif #ifdef PNG_READ_oFFs_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_byte buf[9]; png_int_32 offset_x, offset_y; int unit_type; png_debug(1, "in png_handle_oFFs"); png_crc_read(png_ptr, buf, 9); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; offset_x = png_get_int_32(buf); offset_y = png_get_int_32(buf + 4); unit_type = buf[8]; png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type); return handled_ok; PNG_UNUSED(length) } #else # define png_handle_oFFs NULL #endif #ifdef PNG_READ_pCAL_SUPPORTED /* Read the pCAL chunk (described in the PNG Extensions document) */ static png_handle_result_code /* PRIVATE */ png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_bytep buffer; png_bytep buf; png_bytep endptr; png_int_32 X0, X1; png_byte type; png_byte nparams; png_byte *units; png_charpp params; int i; png_debug(1, "in png_handle_pCAL"); png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)", length + 1); buffer = png_read_buffer(png_ptr, length+1); if (buffer == NULL) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "out of memory"); return handled_error; } png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; buffer[length] = 0; /* Null terminate the last string */ png_debug(3, "Finding end of pCAL purpose string"); for (buf = buffer; *buf; buf++) /* Empty loop */ ; endptr = buffer + length; /* We need to have at least 12 bytes after the purpose string * in order to get the parameter information. */ if (endptr - buf <= 12) { png_chunk_benign_error(png_ptr, "invalid"); return handled_error; } png_debug(3, "Reading pCAL X0, X1, type, nparams, and units"); X0 = png_get_int_32((png_bytep)buf+1); X1 = png_get_int_32((png_bytep)buf+5); type = buf[9]; nparams = buf[10]; units = buf + 11; png_debug(3, "Checking pCAL equation type and number of parameters"); /* Check that we have the right number of parameters for known * equation types. */ if ((type == PNG_EQUATION_LINEAR && nparams != 2) || (type == PNG_EQUATION_BASE_E && nparams != 3) || (type == PNG_EQUATION_ARBITRARY && nparams != 3) || (type == PNG_EQUATION_HYPERBOLIC && nparams != 4)) { png_chunk_benign_error(png_ptr, "invalid parameter count"); return handled_error; } else if (type >= PNG_EQUATION_LAST) { png_chunk_benign_error(png_ptr, "unrecognized equation type"); } for (buf = units; *buf; buf++) /* Empty loop to move past the units string. */ ; png_debug(3, "Allocating pCAL parameters array"); params = png_voidcast(png_charpp, png_malloc_warn(png_ptr, nparams * (sizeof (png_charp)))); if (params == NULL) { png_chunk_benign_error(png_ptr, "out of memory"); return handled_error; } /* Get pointers to the start of each parameter string. */ for (i = 0; i < nparams; i++) { buf++; /* Skip the null string terminator from previous parameter. */ png_debug1(3, "Reading pCAL parameter %d", i); for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++) /* Empty loop to move past each parameter string */ ; /* Make sure we haven't run out of data yet */ if (buf > endptr) { png_free(png_ptr, params); png_chunk_benign_error(png_ptr, "invalid data"); return handled_error; } } png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams, (png_charp)units, params); /* TODO: BUG: png_set_pCAL calls png_chunk_report which, in this case, calls * png_benign_error and that can error out. * * png_read_buffer needs to be allocated with space for both nparams and the * parameter strings. Not hard to do. */ png_free(png_ptr, params); return handled_ok; } #else # define png_handle_pCAL NULL #endif #ifdef PNG_READ_sCAL_SUPPORTED /* Read the sCAL chunk */ static png_handle_result_code /* PRIVATE */ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_bytep buffer; size_t i; int state; png_debug(1, "in png_handle_sCAL"); png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)", length + 1); buffer = png_read_buffer(png_ptr, length+1); if (buffer == NULL) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "out of memory"); return handled_error; } png_crc_read(png_ptr, buffer, length); buffer[length] = 0; /* Null terminate the last string */ if (png_crc_finish(png_ptr, 0) != 0) return handled_error; /* Validate the unit. */ if (buffer[0] != 1 && buffer[0] != 2) { png_chunk_benign_error(png_ptr, "invalid unit"); return handled_error; } /* Validate the ASCII numbers, need two ASCII numbers separated by * a '\0' and they need to fit exactly in the chunk data. */ i = 1; state = 0; if (png_check_fp_number((png_const_charp)buffer, length, &state, &i) == 0 || i >= length || buffer[i++] != 0) png_chunk_benign_error(png_ptr, "bad width format"); else if (PNG_FP_IS_POSITIVE(state) == 0) png_chunk_benign_error(png_ptr, "non-positive width"); else { size_t heighti = i; state = 0; if (png_check_fp_number((png_const_charp)buffer, length, &state, &i) == 0 || i != length) png_chunk_benign_error(png_ptr, "bad height format"); else if (PNG_FP_IS_POSITIVE(state) == 0) png_chunk_benign_error(png_ptr, "non-positive height"); else { /* This is the (only) success case. */ png_set_sCAL_s(png_ptr, info_ptr, buffer[0], (png_charp)buffer+1, (png_charp)buffer+heighti); return handled_ok; } } return handled_error; } #else # define png_handle_sCAL NULL #endif #ifdef PNG_READ_tIME_SUPPORTED static png_handle_result_code /* PRIVATE */ png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_byte buf[7]; png_time mod_time; png_debug(1, "in png_handle_tIME"); /* TODO: what is this doing here? It should be happened in pngread.c and * pngpread.c, although it could be moved to png_handle_chunk below and * thereby avoid some code duplication. */ if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) png_ptr->mode |= PNG_AFTER_IDAT; png_crc_read(png_ptr, buf, 7); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; mod_time.second = buf[6]; mod_time.minute = buf[5]; mod_time.hour = buf[4]; mod_time.day = buf[3]; mod_time.month = buf[2]; mod_time.year = png_get_uint_16(buf); png_set_tIME(png_ptr, info_ptr, &mod_time); return handled_ok; PNG_UNUSED(length) } #else # define png_handle_tIME NULL #endif #ifdef PNG_READ_tEXt_SUPPORTED /* Note: this does not properly handle chunks that are > 64K under DOS */ static png_handle_result_code /* PRIVATE */ png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_text text_info; png_bytep buffer; png_charp key; png_charp text; png_uint_32 skip = 0; png_debug(1, "in png_handle_tEXt"); #ifdef PNG_USER_LIMITS_SUPPORTED if (png_ptr->user_chunk_cache_max != 0) { if (png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); return handled_error; } if (--png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "no space in chunk cache"); return handled_error; } } #endif buffer = png_read_buffer(png_ptr, length+1); if (buffer == NULL) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "out of memory"); return handled_error; } png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, skip) != 0) return handled_error; key = (png_charp)buffer; key[length] = 0; for (text = key; *text; text++) /* Empty loop to find end of key */ ; if (text != key + length) text++; text_info.compression = PNG_TEXT_COMPRESSION_NONE; text_info.key = key; text_info.lang = NULL; text_info.lang_key = NULL; text_info.itxt_length = 0; text_info.text = text; text_info.text_length = strlen(text); if (png_set_text_2(png_ptr, info_ptr, &text_info, 1) == 0) return handled_ok; png_chunk_benign_error(png_ptr, "out of memory"); return handled_error; } #else # define png_handle_tEXt NULL #endif #ifdef PNG_READ_zTXt_SUPPORTED /* Note: this does not correctly handle chunks that are > 64K under DOS */ static png_handle_result_code /* PRIVATE */ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_const_charp errmsg = NULL; png_bytep buffer; png_uint_32 keyword_length; png_debug(1, "in png_handle_zTXt"); #ifdef PNG_USER_LIMITS_SUPPORTED if (png_ptr->user_chunk_cache_max != 0) { if (png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); return handled_error; } if (--png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "no space in chunk cache"); return handled_error; } } #endif /* Note, "length" is sufficient here; we won't be adding * a null terminator later. The limit check in png_handle_chunk should be * sufficient. */ buffer = png_read_buffer(png_ptr, length); if (buffer == NULL) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "out of memory"); return handled_error; } png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; /* TODO: also check that the keyword contents match the spec! */ for (keyword_length = 0; keyword_length < length && buffer[keyword_length] != 0; ++keyword_length) /* Empty loop to find end of name */ ; if (keyword_length > 79 || keyword_length < 1) errmsg = "bad keyword"; /* zTXt must have some LZ data after the keyword, although it may expand to * zero bytes; we need a '\0' at the end of the keyword, the compression type * then the LZ data: */ else if (keyword_length + 3 > length) errmsg = "truncated"; else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE) errmsg = "unknown compression type"; else { png_alloc_size_t uncompressed_length = PNG_SIZE_MAX; /* TODO: at present png_decompress_chunk imposes a single application * level memory limit, this should be split to different values for iCCP * and text chunks. */ if (png_decompress_chunk(png_ptr, length, keyword_length+2, &uncompressed_length, 1/*terminate*/) == Z_STREAM_END) { png_text text; if (png_ptr->read_buffer == NULL) errmsg="Read failure in png_handle_zTXt"; else { /* It worked; png_ptr->read_buffer now looks like a tEXt chunk * except for the extra compression type byte and the fact that * it isn't necessarily '\0' terminated. */ buffer = png_ptr->read_buffer; buffer[uncompressed_length+(keyword_length+2)] = 0; text.compression = PNG_TEXT_COMPRESSION_zTXt; text.key = (png_charp)buffer; text.text = (png_charp)(buffer + keyword_length+2); text.text_length = uncompressed_length; text.itxt_length = 0; text.lang = NULL; text.lang_key = NULL; if (png_set_text_2(png_ptr, info_ptr, &text, 1) == 0) return handled_ok; errmsg = "out of memory"; } } else errmsg = png_ptr->zstream.msg; } png_chunk_benign_error(png_ptr, errmsg); return handled_error; } #else # define png_handle_zTXt NULL #endif #ifdef PNG_READ_iTXt_SUPPORTED /* Note: this does not correctly handle chunks that are > 64K under DOS */ static png_handle_result_code /* PRIVATE */ png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_const_charp errmsg = NULL; png_bytep buffer; png_uint_32 prefix_length; png_debug(1, "in png_handle_iTXt"); #ifdef PNG_USER_LIMITS_SUPPORTED if (png_ptr->user_chunk_cache_max != 0) { if (png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); return handled_error; } if (--png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "no space in chunk cache"); return handled_error; } } #endif buffer = png_read_buffer(png_ptr, length+1); if (buffer == NULL) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "out of memory"); return handled_error; } png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, 0) != 0) return handled_error; /* First the keyword. */ for (prefix_length=0; prefix_length < length && buffer[prefix_length] != 0; ++prefix_length) /* Empty loop */ ; /* Perform a basic check on the keyword length here. */ if (prefix_length > 79 || prefix_length < 1) errmsg = "bad keyword"; /* Expect keyword, compression flag, compression type, language, translated * keyword (both may be empty but are 0 terminated) then the text, which may * be empty. */ else if (prefix_length + 5 > length) errmsg = "truncated"; else if (buffer[prefix_length+1] == 0 || (buffer[prefix_length+1] == 1 && buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE)) { int compressed = buffer[prefix_length+1] != 0; png_uint_32 language_offset, translated_keyword_offset; png_alloc_size_t uncompressed_length = 0; /* Now the language tag */ prefix_length += 3; language_offset = prefix_length; for (; prefix_length < length && buffer[prefix_length] != 0; ++prefix_length) /* Empty loop */ ; /* WARNING: the length may be invalid here, this is checked below. */ translated_keyword_offset = ++prefix_length; for (; prefix_length < length && buffer[prefix_length] != 0; ++prefix_length) /* Empty loop */ ; /* prefix_length should now be at the trailing '\0' of the translated * keyword, but it may already be over the end. None of this arithmetic * can overflow because chunks are at most 2^31 bytes long, but on 16-bit * systems the available allocation may overflow. */ ++prefix_length; if (compressed == 0 && prefix_length <= length) uncompressed_length = length - prefix_length; else if (compressed != 0 && prefix_length < length) { uncompressed_length = PNG_SIZE_MAX; /* TODO: at present png_decompress_chunk imposes a single application * level memory limit, this should be split to different values for * iCCP and text chunks. */ if (png_decompress_chunk(png_ptr, length, prefix_length, &uncompressed_length, 1/*terminate*/) == Z_STREAM_END) buffer = png_ptr->read_buffer; else errmsg = png_ptr->zstream.msg; } else errmsg = "truncated"; if (errmsg == NULL) { png_text text; buffer[uncompressed_length+prefix_length] = 0; if (compressed == 0) text.compression = PNG_ITXT_COMPRESSION_NONE; else text.compression = PNG_ITXT_COMPRESSION_zTXt; text.key = (png_charp)buffer; text.lang = (png_charp)buffer + language_offset; text.lang_key = (png_charp)buffer + translated_keyword_offset; text.text = (png_charp)buffer + prefix_length; text.text_length = 0; text.itxt_length = uncompressed_length; if (png_set_text_2(png_ptr, info_ptr, &text, 1) == 0) return handled_ok; errmsg = "out of memory"; } } else errmsg = "bad compression info"; if (errmsg != NULL) png_chunk_benign_error(png_ptr, errmsg); return handled_error; } #else # define png_handle_iTXt NULL #endif #ifdef PNG_READ_APNG_SUPPORTED void /* PRIVATE */ png_handle_acTL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length) { png_byte data[8]; png_uint_32 num_frames; png_uint_32 num_plays; png_uint_32 didSet; png_debug(1, "in png_handle_acTL"); if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) { png_error(png_ptr, "Missing IHDR before acTL"); } else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) { png_warning(png_ptr, "Invalid acTL after IDAT skipped"); png_crc_finish(png_ptr, length); return; } else if ((png_ptr->mode & PNG_HAVE_acTL) != 0) { png_warning(png_ptr, "Duplicate acTL skipped"); png_crc_finish(png_ptr, length); return; } else if (length != 8) { png_warning(png_ptr, "acTL with invalid length skipped"); png_crc_finish(png_ptr, length); return; } png_crc_read(png_ptr, data, 8); png_crc_finish(png_ptr, 0); num_frames = png_get_uint_31(png_ptr, data); num_plays = png_get_uint_31(png_ptr, data + 4); /* the set function will do error checking on num_frames */ didSet = png_set_acTL(png_ptr, info_ptr, num_frames, num_plays); if (didSet != 0) png_ptr->mode |= PNG_HAVE_acTL; } void /* PRIVATE */ png_handle_fcTL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length) { png_byte data[22]; png_uint_32 width; png_uint_32 height; png_uint_32 x_offset; png_uint_32 y_offset; png_uint_16 delay_num; png_uint_16 delay_den; png_byte dispose_op; png_byte blend_op; png_debug(1, "in png_handle_fcTL"); png_ensure_sequence_number(png_ptr, length); if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) { png_error(png_ptr, "Missing IHDR before fcTL"); } else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) { /* for any frames other then the first this message may be misleading, * but correct. PNG_HAVE_IDAT is unset before the frame head is read * i can't think of a better message */ png_warning(png_ptr, "Invalid fcTL after IDAT skipped"); png_crc_finish(png_ptr, length-4); return; } else if ((png_ptr->mode & PNG_HAVE_fcTL) != 0) { png_warning(png_ptr, "Duplicate fcTL within one frame skipped"); png_crc_finish(png_ptr, length-4); return; } else if (length != 26) { png_warning(png_ptr, "fcTL with invalid length skipped"); png_crc_finish(png_ptr, length-4); return; } png_crc_read(png_ptr, data, 22); png_crc_finish(png_ptr, 0); width = png_get_uint_31(png_ptr, data); height = png_get_uint_31(png_ptr, data + 4); x_offset = png_get_uint_31(png_ptr, data + 8); y_offset = png_get_uint_31(png_ptr, data + 12); delay_num = png_get_uint_16(data + 16); delay_den = png_get_uint_16(data + 18); dispose_op = data[20]; blend_op = data[21]; if (png_ptr->num_frames_read == 0 && (x_offset != 0 || y_offset != 0)) { png_warning(png_ptr, "fcTL for the first frame must have zero offset"); return; } if (info_ptr != NULL) { if (png_ptr->num_frames_read == 0 && (width != info_ptr->width || height != info_ptr->height)) { png_warning(png_ptr, "size in first frame's fcTL must match " "the size in IHDR"); return; } /* The set function will do more error checking */ png_set_next_frame_fcTL(png_ptr, info_ptr, width, height, x_offset, y_offset, delay_num, delay_den, dispose_op, blend_op); png_read_reinit(png_ptr, info_ptr); png_ptr->mode |= PNG_HAVE_fcTL; } } void /* PRIVATE */ png_have_info(png_structp png_ptr, png_infop info_ptr) { if ((info_ptr->valid & PNG_INFO_acTL) != 0 && (info_ptr->valid & PNG_INFO_fcTL) == 0) { png_ptr->apng_flags |= PNG_FIRST_FRAME_HIDDEN; info_ptr->num_frames++; } } void /* PRIVATE */ png_handle_fdAT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length) { png_ensure_sequence_number(png_ptr, length); /* This function is only called from png_read_end(), png_read_info(), * and png_push_read_chunk() which means that: * - the user doesn't want to read this frame * - or this is an out-of-place fdAT * in either case it is safe to ignore the chunk with a warning */ png_warning(png_ptr, "ignoring fdAT chunk"); png_crc_finish(png_ptr, length - 4); PNG_UNUSED(info_ptr) } void /* PRIVATE */ png_ensure_sequence_number(png_structp png_ptr, png_uint_32 length) { png_byte data[4]; png_uint_32 sequence_number; if (length < 4) png_error(png_ptr, "invalid fcTL or fdAT chunk found"); png_crc_read(png_ptr, data, 4); sequence_number = png_get_uint_31(png_ptr, data); if (sequence_number != png_ptr->next_seq_num) png_error(png_ptr, "fcTL or fdAT chunk with out-of-order sequence " "number found"); png_ptr->next_seq_num++; } #endif /* READ_APNG */ #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED /* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */ static int png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length) { const png_alloc_size_t limit = png_chunk_max(png_ptr); if (png_ptr->unknown_chunk.data != NULL) { png_free(png_ptr, png_ptr->unknown_chunk.data); png_ptr->unknown_chunk.data = NULL; } if (length <= limit) { PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name); /* The following is safe because of the PNG_SIZE_MAX init above */ png_ptr->unknown_chunk.size = (size_t)length/*SAFE*/; /* 'mode' is a flag array, only the bottom four bits matter here */ png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/; if (length == 0) png_ptr->unknown_chunk.data = NULL; else { /* Do a 'warn' here - it is handled below. */ png_ptr->unknown_chunk.data = png_voidcast(png_bytep, png_malloc_warn(png_ptr, length)); } } if (png_ptr->unknown_chunk.data == NULL && length > 0) { /* This is benign because we clean up correctly */ png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits"); return 0; } else { if (length > 0) png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length); png_crc_finish(png_ptr, 0); return 1; } } #endif /* READ_UNKNOWN_CHUNKS */ /* Handle an unknown, or known but disabled, chunk */ png_handle_result_code /*PRIVATE*/ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length, int keep) { png_handle_result_code handled = handled_discarded; /* the default */ png_debug(1, "in png_handle_unknown"); #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing * the bug which meant that setting a non-default behavior for a specific * chunk would be ignored (the default was always used unless a user * callback was installed). * * 'keep' is the value from the png_chunk_unknown_handling, the setting for * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here. * This is just an optimization to avoid multiple calls to the lookup * function. */ # ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name); # endif # endif /* One of the following methods will read the chunk or skip it (at least one * of these is always defined because this is the only way to switch on * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) */ # ifdef PNG_READ_USER_CHUNKS_SUPPORTED /* The user callback takes precedence over the chunk keep value, but the * keep value is still required to validate a save of a critical chunk. */ if (png_ptr->read_user_chunk_fn != NULL) { if (png_cache_unknown_chunk(png_ptr, length) != 0) { /* Callback to user unknown chunk handler */ int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr, &png_ptr->unknown_chunk); /* ret is: * negative: An error occurred; png_chunk_error will be called. * zero: The chunk was not handled, the chunk will be discarded * unless png_set_keep_unknown_chunks has been used to set * a 'keep' behavior for this particular chunk, in which * case that will be used. A critical chunk will cause an * error at this point unless it is to be saved. * positive: The chunk was handled, libpng will ignore/discard it. */ if (ret < 0) /* handled_error */ png_chunk_error(png_ptr, "error in user chunk"); else if (ret == 0) { /* If the keep value is 'default' or 'never' override it, but * still error out on critical chunks unless the keep value is * 'always' While this is weird it is the behavior in 1.4.12. * A possible improvement would be to obey the value set for the * chunk, but this would be an API change that would probably * damage some applications. * * The png_app_warning below catches the case that matters, where * the application has not set specific save or ignore for this * chunk or global save or ignore. */ if (keep < PNG_HANDLE_CHUNK_IF_SAFE) { # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE) { png_chunk_warning(png_ptr, "Saving unknown chunk:"); png_app_warning(png_ptr, "forcing save of an unhandled chunk;" " please call png_set_keep_unknown_chunks"); /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */ } # endif keep = PNG_HANDLE_CHUNK_IF_SAFE; } } else /* chunk was handled */ { handled = handled_ok; /* Critical chunks can be safely discarded at this point. */ keep = PNG_HANDLE_CHUNK_NEVER; } } else keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */ } else /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */ # endif /* READ_USER_CHUNKS */ # ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED { /* keep is currently just the per-chunk setting, if there was no * setting change it to the global default now (not that this may * still be AS_DEFAULT) then obtain the cache of the chunk if required, * if not simply skip the chunk. */ if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT) keep = png_ptr->unknown_default; if (keep == PNG_HANDLE_CHUNK_ALWAYS || (keep == PNG_HANDLE_CHUNK_IF_SAFE && PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))) { if (png_cache_unknown_chunk(png_ptr, length) == 0) keep = PNG_HANDLE_CHUNK_NEVER; } else png_crc_finish(png_ptr, length); } # else # ifndef PNG_READ_USER_CHUNKS_SUPPORTED # error no method to support READ_UNKNOWN_CHUNKS # endif { /* If here there is no read callback pointer set and no support is * compiled in to just save the unknown chunks, so simply skip this * chunk. If 'keep' is something other than AS_DEFAULT or NEVER then * the app has erroneously asked for unknown chunk saving when there * is no support. */ if (keep > PNG_HANDLE_CHUNK_NEVER) png_app_error(png_ptr, "no unknown chunk support available"); png_crc_finish(png_ptr, length); } # endif # ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED /* Now store the chunk in the chunk list if appropriate, and if the limits * permit it. */ if (keep == PNG_HANDLE_CHUNK_ALWAYS || (keep == PNG_HANDLE_CHUNK_IF_SAFE && PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))) { # ifdef PNG_USER_LIMITS_SUPPORTED switch (png_ptr->user_chunk_cache_max) { case 2: png_ptr->user_chunk_cache_max = 1; png_chunk_benign_error(png_ptr, "no space in chunk cache"); /* FALLTHROUGH */ case 1: /* NOTE: prior to 1.6.0 this case resulted in an unknown critical * chunk being skipped, now there will be a hard error below. */ break; default: /* not at limit */ --(png_ptr->user_chunk_cache_max); /* FALLTHROUGH */ case 0: /* no limit */ # endif /* USER_LIMITS */ /* Here when the limit isn't reached or when limits are compiled * out; store the chunk. */ png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1); handled = handled_saved; # ifdef PNG_USER_LIMITS_SUPPORTED break; } # endif } # else /* no store support: the chunk must be handled by the user callback */ PNG_UNUSED(info_ptr) # endif /* Regardless of the error handling below the cached data (if any) can be * freed now. Notice that the data is not freed if there is a png_error, but * it will be freed by destroy_read_struct. */ if (png_ptr->unknown_chunk.data != NULL) png_free(png_ptr, png_ptr->unknown_chunk.data); png_ptr->unknown_chunk.data = NULL; #else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */ /* There is no support to read an unknown chunk, so just skip it. */ png_crc_finish(png_ptr, length); PNG_UNUSED(info_ptr) PNG_UNUSED(keep) #endif /* !READ_UNKNOWN_CHUNKS */ /* Check for unhandled critical chunks */ if (handled < handled_saved && PNG_CHUNK_CRITICAL(png_ptr->chunk_name)) png_chunk_error(png_ptr, "unhandled critical chunk"); return handled; } /* APNG handling: the minimal implementation of APNG handling in libpng 1.6 * requires that those significant applications which already handle APNG not * get hosed. To do this ensure the code here will have to ensure than APNG * data by default (at least in 1.6) gets stored in the unknown chunk list. * Maybe this can be relaxed in a few years but at present it's just the only * safe way. * * ATM just cause unknown handling for all three chunks: */ #define png_handle_acTL NULL #define png_handle_fcTL NULL #define png_handle_fdAT NULL /* * 1.6.47: This is the new table driven interface to all the chunk handling. * * The table describes the PNG standard rules for **reading** known chunks - * every chunk which has an entry in PNG_KNOWN_CHUNKS. The table contains an * entry for each PNG_INDEX_cHNK describing the rules. * * In this initial version the only information in the entry is the * png_handle_cHNK function for the chunk in question. When chunk support is * compiled out the entry will be NULL. */ static const struct { png_handle_result_code (*handler)( png_structrp, png_inforp, png_uint_32 length); /* A chunk-specific 'handler', NULL if the chunk is not supported in this * build. */ /* Crushing these values helps on modern 32-bit architectures because the * pointer and the following bit fields both end up requiring 32 bits. * Typically this will halve the table size. On 64-bit architectures the * table entries will typically be 8 bytes. */ png_uint_32 max_length :12; /* Length min, max in bytes */ png_uint_32 min_length :8; /* Length errors on critical chunks have special handling to preserve the * existing behaviour in libpng 1.6. Ancillary chunks are checked below * and produce a 'benign' error. */ png_uint_32 pos_before :4; /* PNG_HAVE_ values chunk must precede */ png_uint_32 pos_after :4; /* PNG_HAVE_ values chunk must follow */ /* NOTE: PLTE, tRNS and bKGD require special handling which depends on * the colour type of the base image. */ png_uint_32 multiple :1; /* Multiple occurrences permitted */ /* This is enabled for PLTE because PLTE may, in practice, be optional */ } read_chunks[PNG_INDEX_unknown] = { /* Definitions as above but done indirectly by #define so that * PNG_KNOWN_CHUNKS can be used safely to build the table in order. * * Each CDcHNK definition lists the values for the parameters **after** * the first, 'handler', function. 'handler' is NULL when the chunk has no * compiled in support. */ # define NoCheck 0x801U /* Do not check the maximum length */ # define Limit 0x802U /* Limit to png_chunk_max bytes */ # define LKMin 3U+LZ77Min /* Minimum length of keyword+LZ77 */ #define hIHDR PNG_HAVE_IHDR #define hPLTE PNG_HAVE_PLTE #define hIDAT PNG_HAVE_IDAT /* For the two chunks, tRNS and bKGD which can occur in PNGs without a PLTE * but must occur after the PLTE use this and put the check in the handler * routine for colour mapped images were PLTE is required. Also put a check * in PLTE for other image types to drop the PLTE if tRNS or bKGD have been * seen. */ #define hCOL (PNG_HAVE_PLTE|PNG_HAVE_IDAT) /* Used for the decoding chunks which must be before PLTE. */ #define aIDAT PNG_AFTER_IDAT /* Chunks from W3C PNG v3: */ /* cHNK max_len, min, before, after, multiple */ # define CDIHDR 13U, 13U, hIHDR, 0, 0 # define CDPLTE NoCheck, 0U, 0, hIHDR, 1 /* PLTE errors are only critical for colour-map images, consequently the * handler does all the checks. */ # define CDIDAT NoCheck, 0U, aIDAT, hIHDR, 1 # define CDIEND NoCheck, 0U, 0, aIDAT, 0 /* Historically data was allowed in IEND */ # define CDtRNS 256U, 0U, hIDAT, hIHDR, 0 # define CDcHRM 32U, 32U, hCOL, hIHDR, 0 # define CDgAMA 4U, 4U, hCOL, hIHDR, 0 # define CDiCCP NoCheck, LKMin, hCOL, hIHDR, 0 # define CDsBIT 4U, 1U, hCOL, hIHDR, 0 # define CDsRGB 1U, 1U, hCOL, hIHDR, 0 # define CDcICP 4U, 4U, hCOL, hIHDR, 0 # define CDmDCV 24U, 24U, hCOL, hIHDR, 0 # define CDeXIf Limit, 4U, 0, hIHDR, 0 # define CDcLLI 8U, 8U, hCOL, hIHDR, 0 # define CDtEXt NoCheck, 2U, 0, hIHDR, 1 /* Allocates 'length+1'; checked in the handler */ # define CDzTXt Limit, LKMin, 0, hIHDR, 1 # define CDiTXt NoCheck, 6U, 0, hIHDR, 1 /* Allocates 'length+1'; checked in the handler */ # define CDbKGD 6U, 1U, hIDAT, hIHDR, 0 # define CDhIST 1024U, 0U, hPLTE, hIHDR, 0 # define CDpHYs 9U, 9U, hIDAT, hIHDR, 0 # define CDsPLT NoCheck, 3U, hIDAT, hIHDR, 1 /* Allocates 'length+1'; checked in the handler */ # define CDtIME 7U, 7U, 0, hIHDR, 0 # define CDacTL 8U, 8U, hIDAT, hIHDR, 0 # define CDfcTL 25U, 26U, 0, hIHDR, 1 # define CDfdAT Limit, 4U, hIDAT, hIHDR, 1 /* Supported chunks from PNG extensions 1.5.0, NYI so limit */ # define CDoFFs 9U, 9U, hIDAT, hIHDR, 0 # define CDpCAL NoCheck, 14U, hIDAT, hIHDR, 0 /* Allocates 'length+1'; checked in the handler */ # define CDsCAL Limit, 4U, hIDAT, hIHDR, 0 /* Allocates 'length+1'; checked in the handler */ # define PNG_CHUNK(cHNK, index) { png_handle_ ## cHNK, CD ## cHNK }, PNG_KNOWN_CHUNKS # undef PNG_CHUNK }; static png_index png_chunk_index_from_name(png_uint_32 chunk_name) { /* For chunk png_cHNK return PNG_INDEX_cHNK. Return PNG_INDEX_unknown if * chunk_name is not known. Notice that in a particular build "known" does * not necessarily mean "supported", although the inverse applies. */ switch (chunk_name) { # define PNG_CHUNK(cHNK, index)\ case png_ ## cHNK: return PNG_INDEX_ ## cHNK; /* == index */ PNG_KNOWN_CHUNKS # undef PNG_CHUNK default: return PNG_INDEX_unknown; } } png_handle_result_code /*PRIVATE*/ png_handle_chunk(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { /* CSE: these things don't change, these autos are just to save typing and * make the code more clear. */ const png_uint_32 chunk_name = png_ptr->chunk_name; const png_index chunk_index = png_chunk_index_from_name(chunk_name); png_handle_result_code handled = handled_error; png_const_charp errmsg = NULL; /* Is this a known chunk? If not there are no checks performed here; * png_handle_unknown does the correct checks. This means that the values * for known but unsupported chunks in the above table are not used here * however the chunks_seen fields in png_struct are still set. */ if (chunk_index == PNG_INDEX_unknown || read_chunks[chunk_index].handler == NULL) { handled = png_handle_unknown( png_ptr, info_ptr, length, PNG_HANDLE_CHUNK_AS_DEFAULT); } /* First check the position. The first check is historical; the stream must * start with IHDR and anything else causes libpng to give up immediately. */ else if (chunk_index != PNG_INDEX_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0) png_chunk_error(png_ptr, "missing IHDR"); /* NORETURN */ /* Before all the pos_before chunks, after all the pos_after chunks. */ else if (((png_ptr->mode & read_chunks[chunk_index].pos_before) != 0) || ((png_ptr->mode & read_chunks[chunk_index].pos_after) != read_chunks[chunk_index].pos_after)) { errmsg = "out of place"; } /* Now check for duplicates: duplicated critical chunks also produce a * full error. */ else if (read_chunks[chunk_index].multiple == 0 && png_file_has_chunk(png_ptr, chunk_index)) { errmsg = "duplicate"; } else if (length < read_chunks[chunk_index].min_length) errmsg = "too short"; else { /* NOTE: apart from IHDR the critical chunks (PLTE, IDAT and IEND) are set * up above not to do any length checks. * * The png_chunk_max check ensures that the variable length chunks are * always checked at this point for being within the system allocation * limits. */ unsigned max_length = read_chunks[chunk_index].max_length; switch (max_length) { case Limit: /* png_read_chunk_header has already png_error'ed chunks with a * length exceeding the 31-bit PNG limit, so just check the memory * limit: */ if (length <= png_chunk_max(png_ptr)) goto MeetsLimit; errmsg = "length exceeds libpng limit"; break; default: if (length <= max_length) goto MeetsLimit; errmsg = "too long"; break; case NoCheck: MeetsLimit: handled = read_chunks[chunk_index].handler( png_ptr, info_ptr, length); break; } } /* If there was an error or the chunk was simply skipped it is not counted as * 'seen'. */ if (errmsg != NULL) { if (PNG_CHUNK_CRITICAL(chunk_name)) /* stop immediately */ png_chunk_error(png_ptr, errmsg); else /* ancillary chunk */ { /* The chunk data is skipped: */ png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, errmsg); } } else if (handled >= handled_saved) { if (chunk_index != PNG_INDEX_unknown) png_file_add_chunk(png_ptr, chunk_index); } return handled; } /* Combines the row recently read in with the existing pixels in the row. This * routine takes care of alpha and transparency if requested. This routine also * handles the two methods of progressive display of interlaced images, * depending on the 'display' value; if 'display' is true then the whole row * (dp) is filled from the start by replicating the available pixels. If * 'display' is false only those pixels present in the pass are filled in. */ void /* PRIVATE */ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display) { unsigned int pixel_depth = png_ptr->transformed_pixel_depth; png_const_bytep sp = png_ptr->row_buf + 1; png_alloc_size_t row_width = png_ptr->width; unsigned int pass = png_ptr->pass; png_bytep end_ptr = 0; png_byte end_byte = 0; unsigned int end_mask; png_debug(1, "in png_combine_row"); /* Added in 1.5.6: it should not be possible to enter this routine until at * least one row has been read from the PNG data and transformed. */ if (pixel_depth == 0) png_error(png_ptr, "internal row logic error"); /* Added in 1.5.4: the pixel depth should match the information returned by * any call to png_read_update_info at this point. Do not continue if we got * this wrong. */ if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes != PNG_ROWBYTES(pixel_depth, row_width)) png_error(png_ptr, "internal row size calculation error"); /* Don't expect this to ever happen: */ if (row_width == 0) png_error(png_ptr, "internal row width error"); /* Preserve the last byte in cases where only part of it will be overwritten, * the multiply below may overflow, we don't care because ANSI-C guarantees * we get the low bits. */ end_mask = (pixel_depth * row_width) & 7; if (end_mask != 0) { /* end_ptr == NULL is a flag to say do nothing */ end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1; end_byte = *end_ptr; # ifdef PNG_READ_PACKSWAP_SUPPORTED if ((png_ptr->transformations & PNG_PACKSWAP) != 0) /* little-endian byte */ end_mask = (unsigned int)(0xff << end_mask); else /* big-endian byte */ # endif end_mask = 0xff >> end_mask; /* end_mask is now the bits to *keep* from the destination row */ } /* For non-interlaced images this reduces to a memcpy(). A memcpy() * will also happen if interlacing isn't supported or if the application * does not call png_set_interlace_handling(). In the latter cases the * caller just gets a sequence of the unexpanded rows from each interlace * pass. */ #ifdef PNG_READ_INTERLACING_SUPPORTED if (png_ptr->interlaced != 0 && (png_ptr->transformations & PNG_INTERLACE) != 0 && pass < 6 && (display == 0 || /* The following copies everything for 'display' on passes 0, 2 and 4. */ (display == 1 && (pass & 1) != 0))) { /* Narrow images may have no bits in a pass; the caller should handle * this, but this test is cheap: */ if (row_width <= PNG_PASS_START_COL(pass)) return; if (pixel_depth < 8) { /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit * into 32 bits, then a single loop over the bytes using the four byte * values in the 32-bit mask can be used. For the 'display' option the * expanded mask may also not require any masking within a byte. To * make this work the PACKSWAP option must be taken into account - it * simply requires the pixels to be reversed in each byte. * * The 'regular' case requires a mask for each of the first 6 passes, * the 'display' case does a copy for the even passes in the range * 0..6. This has already been handled in the test above. * * The masks are arranged as four bytes with the first byte to use in * the lowest bits (little-endian) regardless of the order (PACKSWAP or * not) of the pixels in each byte. * * NOTE: the whole of this logic depends on the caller of this function * only calling it on rows appropriate to the pass. This function only * understands the 'x' logic; the 'y' logic is handled by the caller. * * The following defines allow generation of compile time constant bit * masks for each pixel depth and each possibility of swapped or not * swapped bytes. Pass 'p' is in the range 0..6; 'x', a pixel index, * is in the range 0..7; and the result is 1 if the pixel is to be * copied in the pass, 0 if not. 'S' is for the sparkle method, 'B' * for the block method. * * With some compilers a compile time expression of the general form: * * (shift >= 32) ? (a >> (shift-32)) : (b >> shift) * * Produces warnings with values of 'shift' in the range 33 to 63 * because the right hand side of the ?: expression is evaluated by * the compiler even though it isn't used. Microsoft Visual C (various * versions) and the Intel C compiler are known to do this. To avoid * this the following macros are used in 1.5.6. This is a temporary * solution to avoid destabilizing the code during the release process. */ # if PNG_USE_COMPILE_TIME_MASKS # define PNG_LSR(x,s) ((x)>>((s) & 0x1f)) # define PNG_LSL(x,s) ((x)<<((s) & 0x1f)) # else # define PNG_LSR(x,s) ((x)>>(s)) # define PNG_LSL(x,s) ((x)<<(s)) # endif # define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\ PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1) # define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\ PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1) /* Return a mask for pass 'p' pixel 'x' at depth 'd'. The mask is * little endian - the first pixel is at bit 0 - however the extra * parameter 's' can be set to cause the mask position to be swapped * within each byte, to match the PNG format. This is done by XOR of * the shift with 7, 6 or 4 for bit depths 1, 2 and 4. */ # define PIXEL_MASK(p,x,d,s) \ (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0)))) /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask. */ # define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0) # define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0) /* Combine 8 of these to get the full mask. For the 1-bpp and 2-bpp * cases the result needs replicating, for the 4-bpp case the above * generates a full 32 bits. */ # define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1))) # define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\ S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\ S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d) # define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\ B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\ B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d) #if PNG_USE_COMPILE_TIME_MASKS /* Utility macros to construct all the masks for a depth/swap * combination. The 's' parameter says whether the format is PNG * (big endian bytes) or not. Only the three odd-numbered passes are * required for the display/block algorithm. */ # define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\ S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) } # define B_MASKS(d,s) { B_MASK(1,d,s), B_MASK(3,d,s), B_MASK(5,d,s) } # define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2)) /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and * then pass: */ static const png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] = { /* Little-endian byte masks for PACKSWAP */ { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) }, /* Normal (big-endian byte) masks - PNG format */ { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) } }; /* display_mask has only three entries for the odd passes, so index by * pass>>1. */ static const png_uint_32 display_mask[2][3][3] = { /* Little-endian byte masks for PACKSWAP */ { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) }, /* Normal (big-endian byte) masks - PNG format */ { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) } }; # define MASK(pass,depth,display,png)\ ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\ row_mask[png][DEPTH_INDEX(depth)][pass]) #else /* !PNG_USE_COMPILE_TIME_MASKS */ /* This is the runtime alternative: it seems unlikely that this will * ever be either smaller or faster than the compile time approach. */ # define MASK(pass,depth,display,png)\ ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png)) #endif /* !USE_COMPILE_TIME_MASKS */ /* Use the appropriate mask to copy the required bits. In some cases * the byte mask will be 0 or 0xff; optimize these cases. row_width is * the number of pixels, but the code copies bytes, so it is necessary * to special case the end. */ png_uint_32 pixels_per_byte = 8 / pixel_depth; png_uint_32 mask; # ifdef PNG_READ_PACKSWAP_SUPPORTED if ((png_ptr->transformations & PNG_PACKSWAP) != 0) mask = MASK(pass, pixel_depth, display, 0); else # endif mask = MASK(pass, pixel_depth, display, 1); for (;;) { png_uint_32 m; /* It doesn't matter in the following if png_uint_32 has more than * 32 bits because the high bits always match those in m<<24; it is, * however, essential to use OR here, not +, because of this. */ m = mask; mask = (m >> 8) | (m << 24); /* rotate right to good compilers */ m &= 0xff; if (m != 0) /* something to copy */ { if (m != 0xff) *dp = (png_byte)((*dp & ~m) | (*sp & m)); else *dp = *sp; } /* NOTE: this may overwrite the last byte with garbage if the image * is not an exact number of bytes wide; libpng has always done * this. */ if (row_width <= pixels_per_byte) break; /* May need to restore part of the last byte */ row_width -= pixels_per_byte; ++dp; ++sp; } } else /* pixel_depth >= 8 */ { unsigned int bytes_to_copy, bytes_to_jump; /* Validate the depth - it must be a multiple of 8 */ if (pixel_depth & 7) png_error(png_ptr, "invalid user transform pixel depth"); pixel_depth >>= 3; /* now in bytes */ row_width *= pixel_depth; /* Regardless of pass number the Adam 7 interlace always results in a * fixed number of pixels to copy then to skip. There may be a * different number of pixels to skip at the start though. */ { unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth; row_width -= offset; dp += offset; sp += offset; } /* Work out the bytes to copy. */ if (display != 0) { /* When doing the 'block' algorithm the pixel in the pass gets * replicated to adjacent pixels. This is why the even (0,2,4,6) * passes are skipped above - the entire expanded row is copied. */ bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth; /* But don't allow this number to exceed the actual row width. */ if (bytes_to_copy > row_width) bytes_to_copy = (unsigned int)/*SAFE*/row_width; } else /* normal row; Adam7 only ever gives us one pixel to copy. */ bytes_to_copy = pixel_depth; /* In Adam7 there is a constant offset between where the pixels go. */ bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth; /* And simply copy these bytes. Some optimization is possible here, * depending on the value of 'bytes_to_copy'. Special case the low * byte counts, which we know to be frequent. * * Notice that these cases all 'return' rather than 'break' - this * avoids an unnecessary test on whether to restore the last byte * below. */ switch (bytes_to_copy) { case 1: for (;;) { *dp = *sp; if (row_width <= bytes_to_jump) return; dp += bytes_to_jump; sp += bytes_to_jump; row_width -= bytes_to_jump; } case 2: /* There is a possibility of a partial copy at the end here; this * slows the code down somewhat. */ do { dp[0] = sp[0]; dp[1] = sp[1]; if (row_width <= bytes_to_jump) return; sp += bytes_to_jump; dp += bytes_to_jump; row_width -= bytes_to_jump; } while (row_width > 1); /* And there can only be one byte left at this point: */ *dp = *sp; return; case 3: /* This can only be the RGB case, so each copy is exactly one * pixel and it is not necessary to check for a partial copy. */ for (;;) { dp[0] = sp[0]; dp[1] = sp[1]; dp[2] = sp[2]; if (row_width <= bytes_to_jump) return; sp += bytes_to_jump; dp += bytes_to_jump; row_width -= bytes_to_jump; } default: #if PNG_ALIGN_TYPE != PNG_ALIGN_NONE /* Check for double byte alignment and, if possible, use a * 16-bit copy. Don't attempt this for narrow images - ones that * are less than an interlace panel wide. Don't attempt it for * wide bytes_to_copy either - use the memcpy there. */ if (bytes_to_copy < 16 /*else use memcpy*/ && png_isaligned(dp, png_uint_16) && png_isaligned(sp, png_uint_16) && bytes_to_copy % (sizeof (png_uint_16)) == 0 && bytes_to_jump % (sizeof (png_uint_16)) == 0) { /* Everything is aligned for png_uint_16 copies, but try for * png_uint_32 first. */ if (png_isaligned(dp, png_uint_32) && png_isaligned(sp, png_uint_32) && bytes_to_copy % (sizeof (png_uint_32)) == 0 && bytes_to_jump % (sizeof (png_uint_32)) == 0) { png_uint_32p dp32 = png_aligncast(png_uint_32p,dp); png_const_uint_32p sp32 = png_aligncastconst( png_const_uint_32p, sp); size_t skip = (bytes_to_jump-bytes_to_copy) / (sizeof (png_uint_32)); do { size_t c = bytes_to_copy; do { *dp32++ = *sp32++; c -= (sizeof (png_uint_32)); } while (c > 0); if (row_width <= bytes_to_jump) return; dp32 += skip; sp32 += skip; row_width -= bytes_to_jump; } while (bytes_to_copy <= row_width); /* Get to here when the row_width truncates the final copy. * There will be 1-3 bytes left to copy, so don't try the * 16-bit loop below. */ dp = (png_bytep)dp32; sp = (png_const_bytep)sp32; do *dp++ = *sp++; while (--row_width > 0); return; } /* Else do it in 16-bit quantities, but only if the size is * not too large. */ else { png_uint_16p dp16 = png_aligncast(png_uint_16p, dp); png_const_uint_16p sp16 = png_aligncastconst( png_const_uint_16p, sp); size_t skip = (bytes_to_jump-bytes_to_copy) / (sizeof (png_uint_16)); do { size_t c = bytes_to_copy; do { *dp16++ = *sp16++; c -= (sizeof (png_uint_16)); } while (c > 0); if (row_width <= bytes_to_jump) return; dp16 += skip; sp16 += skip; row_width -= bytes_to_jump; } while (bytes_to_copy <= row_width); /* End of row - 1 byte left, bytes_to_copy > row_width: */ dp = (png_bytep)dp16; sp = (png_const_bytep)sp16; do *dp++ = *sp++; while (--row_width > 0); return; } } #endif /* ALIGN_TYPE code */ /* The true default - use a memcpy: */ for (;;) { memcpy(dp, sp, bytes_to_copy); if (row_width <= bytes_to_jump) return; sp += bytes_to_jump; dp += bytes_to_jump; row_width -= bytes_to_jump; if (bytes_to_copy > row_width) bytes_to_copy = (unsigned int)/*SAFE*/row_width; } } /* NOT REACHED*/ } /* pixel_depth >= 8 */ /* Here if pixel_depth < 8 to check 'end_ptr' below. */ } else #endif /* READ_INTERLACING */ /* If here then the switch above wasn't used so just memcpy the whole row * from the temporary row buffer (notice that this overwrites the end of the * destination row if it is a partial byte.) */ memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width)); /* Restore the overwritten bits from the last byte if necessary. */ if (end_ptr != NULL) *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask)); } #ifdef PNG_READ_INTERLACING_SUPPORTED void /* PRIVATE */ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass, png_uint_32 transformations /* Because these may affect the byte layout */) { png_debug(1, "in png_do_read_interlace"); if (row != NULL && row_info != NULL) { png_uint_32 final_width; final_width = row_info->width * png_pass_inc[pass]; switch (row_info->pixel_depth) { case 1: { png_bytep sp = row + (size_t)((row_info->width - 1) >> 3); png_bytep dp = row + (size_t)((final_width - 1) >> 3); unsigned int sshift, dshift; unsigned int s_start, s_end; int s_inc; int jstop = (int)png_pass_inc[pass]; png_byte v; png_uint_32 i; int j; #ifdef PNG_READ_PACKSWAP_SUPPORTED if ((transformations & PNG_PACKSWAP) != 0) { sshift = ((row_info->width + 7) & 0x07); dshift = ((final_width + 7) & 0x07); s_start = 7; s_end = 0; s_inc = -1; } else #endif { sshift = 7 - ((row_info->width + 7) & 0x07); dshift = 7 - ((final_width + 7) & 0x07); s_start = 0; s_end = 7; s_inc = 1; } for (i = 0; i < row_info->width; i++) { v = (png_byte)((*sp >> sshift) & 0x01); for (j = 0; j < jstop; j++) { unsigned int tmp = *dp & (0x7f7f >> (7 - dshift)); tmp |= (unsigned int)(v << dshift); *dp = (png_byte)(tmp & 0xff); if (dshift == s_end) { dshift = s_start; dp--; } else dshift = (unsigned int)((int)dshift + s_inc); } if (sshift == s_end) { sshift = s_start; sp--; } else sshift = (unsigned int)((int)sshift + s_inc); } break; } case 2: { png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2); png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2); unsigned int sshift, dshift; unsigned int s_start, s_end; int s_inc; int jstop = (int)png_pass_inc[pass]; png_uint_32 i; #ifdef PNG_READ_PACKSWAP_SUPPORTED if ((transformations & PNG_PACKSWAP) != 0) { sshift = (((row_info->width + 3) & 0x03) << 1); dshift = (((final_width + 3) & 0x03) << 1); s_start = 6; s_end = 0; s_inc = -2; } else #endif { sshift = ((3 - ((row_info->width + 3) & 0x03)) << 1); dshift = ((3 - ((final_width + 3) & 0x03)) << 1); s_start = 0; s_end = 6; s_inc = 2; } for (i = 0; i < row_info->width; i++) { png_byte v; int j; v = (png_byte)((*sp >> sshift) & 0x03); for (j = 0; j < jstop; j++) { unsigned int tmp = *dp & (0x3f3f >> (6 - dshift)); tmp |= (unsigned int)(v << dshift); *dp = (png_byte)(tmp & 0xff); if (dshift == s_end) { dshift = s_start; dp--; } else dshift = (unsigned int)((int)dshift + s_inc); } if (sshift == s_end) { sshift = s_start; sp--; } else sshift = (unsigned int)((int)sshift + s_inc); } break; } case 4: { png_bytep sp = row + (size_t)((row_info->width - 1) >> 1); png_bytep dp = row + (size_t)((final_width - 1) >> 1); unsigned int sshift, dshift; unsigned int s_start, s_end; int s_inc; png_uint_32 i; int jstop = (int)png_pass_inc[pass]; #ifdef PNG_READ_PACKSWAP_SUPPORTED if ((transformations & PNG_PACKSWAP) != 0) { sshift = (((row_info->width + 1) & 0x01) << 2); dshift = (((final_width + 1) & 0x01) << 2); s_start = 4; s_end = 0; s_inc = -4; } else #endif { sshift = ((1 - ((row_info->width + 1) & 0x01)) << 2); dshift = ((1 - ((final_width + 1) & 0x01)) << 2); s_start = 0; s_end = 4; s_inc = 4; } for (i = 0; i < row_info->width; i++) { png_byte v = (png_byte)((*sp >> sshift) & 0x0f); int j; for (j = 0; j < jstop; j++) { unsigned int tmp = *dp & (0xf0f >> (4 - dshift)); tmp |= (unsigned int)(v << dshift); *dp = (png_byte)(tmp & 0xff); if (dshift == s_end) { dshift = s_start; dp--; } else dshift = (unsigned int)((int)dshift + s_inc); } if (sshift == s_end) { sshift = s_start; sp--; } else sshift = (unsigned int)((int)sshift + s_inc); } break; } default: { size_t pixel_bytes = (row_info->pixel_depth >> 3); png_bytep sp = row + (size_t)(row_info->width - 1) * pixel_bytes; png_bytep dp = row + (size_t)(final_width - 1) * pixel_bytes; int jstop = (int)png_pass_inc[pass]; png_uint_32 i; for (i = 0; i < row_info->width; i++) { png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */ int j; memcpy(v, sp, pixel_bytes); for (j = 0; j < jstop; j++) { memcpy(dp, v, pixel_bytes); dp -= pixel_bytes; } sp -= pixel_bytes; } break; } } row_info->width = final_width; row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width); } #ifndef PNG_READ_PACKSWAP_SUPPORTED PNG_UNUSED(transformations) /* Silence compiler warning */ #endif } #endif /* READ_INTERLACING */ static void png_read_filter_row_sub(png_row_infop row_info, png_bytep row, png_const_bytep prev_row) { size_t i; size_t istop = row_info->rowbytes; unsigned int bpp = (row_info->pixel_depth + 7) >> 3; png_bytep rp = row + bpp; PNG_UNUSED(prev_row) for (i = bpp; i < istop; i++) { *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff); rp++; } } static void png_read_filter_row_up(png_row_infop row_info, png_bytep row, png_const_bytep prev_row) { size_t i; size_t istop = row_info->rowbytes; png_bytep rp = row; png_const_bytep pp = prev_row; for (i = 0; i < istop; i++) { *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff); rp++; } } static void png_read_filter_row_avg(png_row_infop row_info, png_bytep row, png_const_bytep prev_row) { size_t i; png_bytep rp = row; png_const_bytep pp = prev_row; unsigned int bpp = (row_info->pixel_depth + 7) >> 3; size_t istop = row_info->rowbytes - bpp; for (i = 0; i < bpp; i++) { *rp = (png_byte)(((int)(*rp) + ((int)(*pp++) / 2 )) & 0xff); rp++; } for (i = 0; i < istop; i++) { *rp = (png_byte)(((int)(*rp) + (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff); rp++; } } static void png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row, png_const_bytep prev_row) { png_bytep rp_end = row + row_info->rowbytes; int a, c; /* First pixel/byte */ c = *prev_row++; a = *row + c; *row++ = (png_byte)a; /* Remainder */ while (row < rp_end) { int b, pa, pb, pc, p; a &= 0xff; /* From previous iteration or start */ b = *prev_row++; 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 /* Find the best predictor, the least of pa, pb, pc favoring the earlier * ones in the case of a tie. */ if (pb < pa) { pa = pb; a = b; } if (pc < pa) a = c; /* Calculate the current pixel in a, and move the previous row pixel to c * for the next time round the loop */ c = b; a += *row; *row++ = (png_byte)a; } } static void png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row, png_const_bytep prev_row) { unsigned int bpp = (row_info->pixel_depth + 7) >> 3; png_bytep rp_end = row + bpp; /* Process the first pixel in the row completely (this is the same as 'up' * because there is only one candidate predictor for the first row). */ while (row < rp_end) { int a = *row + *prev_row++; *row++ = (png_byte)a; } /* Remainder */ rp_end = rp_end + (row_info->rowbytes - bpp); while (row < rp_end) { int a, b, c, pa, pb, pc, p; c = *(prev_row - bpp); a = *(row - bpp); b = *prev_row++; 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 if (pb < pa) { pa = pb; a = b; } if (pc < pa) a = c; a += *row; *row++ = (png_byte)a; } } static void png_init_filter_functions(png_structrp pp) /* This function is called once for every PNG image (except for PNG images * that only use PNG_FILTER_VALUE_NONE for all rows) to set the * implementations required to reverse the filtering of PNG rows. Reversing * the filter is the first transformation performed on the row data. It is * performed in place, therefore an implementation can be selected based on * the image pixel format. If the implementation depends on image width then * take care to ensure that it works correctly if the image is interlaced - * interlacing causes the actual row width to vary. */ { unsigned int bpp = (pp->pixel_depth + 7) >> 3; pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub; pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up; pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg; if (bpp == 1) pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = png_read_filter_row_paeth_1byte_pixel; else pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = png_read_filter_row_paeth_multibyte_pixel; #ifdef PNG_FILTER_OPTIMIZATIONS /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to * call to install hardware optimizations for the above functions; simply * replace whatever elements of the pp->read_filter[] array with a hardware * specific (or, for that matter, generic) optimization. * * To see an example of this examine what configure.ac does when * --enable-arm-neon is specified on the command line. */ PNG_FILTER_OPTIMIZATIONS(pp, bpp); #endif } void /* PRIVATE */ png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row, png_const_bytep prev_row, int filter) { /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic * implementations. See png_init_filter_functions above. */ if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST) { if (pp->read_filter[0] == NULL) png_init_filter_functions(pp); pp->read_filter[filter-1](row_info, row, prev_row); } } #ifdef PNG_SEQUENTIAL_READ_SUPPORTED void /* PRIVATE */ png_read_IDAT_data(png_structrp png_ptr, png_bytep output, png_alloc_size_t avail_out) { /* Loop reading IDATs and decompressing the result into output[avail_out] */ png_ptr->zstream.next_out = output; png_ptr->zstream.avail_out = 0; /* safety: set below */ if (output == NULL) avail_out = 0; do { int ret; png_byte tmpbuf[PNG_INFLATE_BUF_SIZE]; if (png_ptr->zstream.avail_in == 0) { uInt avail_in; png_bytep buffer; #ifdef PNG_READ_APNG_SUPPORTED png_uint_32 bytes_to_skip = 0; while (png_ptr->idat_size == 0 || bytes_to_skip != 0) { png_crc_finish(png_ptr, bytes_to_skip); bytes_to_skip = 0; png_ptr->idat_size = png_read_chunk_header(png_ptr); if (png_ptr->num_frames_read == 0) { if (png_ptr->chunk_name != png_IDAT) png_error(png_ptr, "Not enough image data"); } else { if (png_ptr->chunk_name == png_IEND) png_error(png_ptr, "Not enough image data"); if (png_ptr->chunk_name != png_fdAT) { png_warning(png_ptr, "Skipped (ignored) a chunk " "between APNG chunks"); bytes_to_skip = png_ptr->idat_size; continue; } png_ensure_sequence_number(png_ptr, png_ptr->idat_size); png_ptr->idat_size -= 4; } } #else while (png_ptr->idat_size == 0) { png_crc_finish(png_ptr, 0); png_ptr->idat_size = png_read_chunk_header(png_ptr); /* This is an error even in the 'check' case because the code just * consumed a non-IDAT header. */ if (png_ptr->chunk_name != png_IDAT) png_error(png_ptr, "Not enough image data"); } #endif /* READ_APNG */ avail_in = png_ptr->IDAT_read_size; if (avail_in > png_chunk_max(png_ptr)) avail_in = (uInt)/*SAFE*/png_chunk_max(png_ptr); if (avail_in > png_ptr->idat_size) avail_in = (uInt)png_ptr->idat_size; /* A PNG with a gradually increasing IDAT size will defeat this attempt * to minimize memory usage by causing lots of re-allocs, but * realistically doing IDAT_read_size re-allocs is not likely to be a * big problem. * * An error here corresponds to the system being out of memory. */ buffer = png_read_buffer(png_ptr, avail_in); if (buffer == NULL) png_chunk_error(png_ptr, "out of memory"); png_crc_read(png_ptr, buffer, avail_in); png_ptr->idat_size -= avail_in; png_ptr->zstream.next_in = buffer; png_ptr->zstream.avail_in = avail_in; } /* And set up the output side. */ if (output != NULL) /* standard read */ { uInt out = ZLIB_IO_MAX; if (out > avail_out) out = (uInt)avail_out; avail_out -= out; png_ptr->zstream.avail_out = out; } else /* after last row, checking for end */ { png_ptr->zstream.next_out = tmpbuf; png_ptr->zstream.avail_out = (sizeof tmpbuf); } /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the * process. If the LZ stream is truncated the sequential reader will * terminally damage the stream, above, by reading the chunk header of the * following chunk (it then exits with png_error). * * TODO: deal more elegantly with truncated IDAT lists. */ ret = PNG_INFLATE(png_ptr, Z_NO_FLUSH); /* Take the unconsumed output back. */ if (output != NULL) avail_out += png_ptr->zstream.avail_out; else /* avail_out counts the extra bytes */ avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out; png_ptr->zstream.avail_out = 0; if (ret == Z_STREAM_END) { /* Do this for safety; we won't read any more into this row. */ png_ptr->zstream.next_out = NULL; png_ptr->mode |= PNG_AFTER_IDAT; png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED; #ifdef PNG_READ_APNG_SUPPORTED png_ptr->num_frames_read++; #endif if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0) png_chunk_benign_error(png_ptr, "Extra compressed data"); break; } if (ret != Z_OK) { png_zstream_error(png_ptr, ret); if (output != NULL) png_chunk_error(png_ptr, png_ptr->zstream.msg); else /* checking */ { png_chunk_benign_error(png_ptr, png_ptr->zstream.msg); return; } } } while (avail_out > 0); if (avail_out > 0) { /* The stream ended before the image; this is the same as too few IDATs so * should be handled the same way. */ if (output != NULL) png_error(png_ptr, "Not enough image data"); else /* the deflate stream contained extra data */ png_chunk_benign_error(png_ptr, "Too much image data"); } } void /* PRIVATE */ png_read_finish_IDAT(png_structrp png_ptr) { /* We don't need any more data and the stream should have ended, however the * LZ end code may actually not have been processed. In this case we must * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk * may still remain to be consumed. */ if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0) { /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in * the compressed stream, but the stream may be damaged too, so even after * this call we may need to terminate the zstream ownership. */ png_read_IDAT_data(png_ptr, NULL, 0); png_ptr->zstream.next_out = NULL; /* safety */ /* Now clear everything out for safety; the following may not have been * done. */ if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0) { png_ptr->mode |= PNG_AFTER_IDAT; png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED; } } /* If the zstream has not been released do it now *and* terminate the reading * of the final IDAT chunk. */ if (png_ptr->zowner == png_IDAT) { /* Always do this; the pointers otherwise point into the read buffer. */ png_ptr->zstream.next_in = NULL; png_ptr->zstream.avail_in = 0; /* Now we no longer own the zstream. */ png_ptr->zowner = 0; /* The slightly weird semantics of the sequential IDAT reading is that we * are always in or at the end of an IDAT chunk, so we always need to do a * crc_finish here. If idat_size is non-zero we also need to read the * spurious bytes at the end of the chunk now. */ (void)png_crc_finish(png_ptr, png_ptr->idat_size); } } void /* PRIVATE */ png_read_finish_row(png_structrp png_ptr) { png_debug(1, "in png_read_finish_row"); png_ptr->row_number++; if (png_ptr->row_number < png_ptr->num_rows) return; if (png_ptr->interlaced != 0) { png_ptr->row_number = 0; /* TO DO: don't do this if prev_row isn't needed (requires * read-ahead of the next row's filter byte. */ memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1); do { png_ptr->pass++; if (png_ptr->pass >= 7) break; png_ptr->iwidth = (png_ptr->width + png_pass_inc[png_ptr->pass] - 1 - png_pass_start[png_ptr->pass]) / png_pass_inc[png_ptr->pass]; if ((png_ptr->transformations & PNG_INTERLACE) == 0) { png_ptr->num_rows = (png_ptr->height + png_pass_yinc[png_ptr->pass] - 1 - png_pass_ystart[png_ptr->pass]) / png_pass_yinc[png_ptr->pass]; } else /* if (png_ptr->transformations & PNG_INTERLACE) */ break; /* libpng deinterlacing sees every row */ } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0); if (png_ptr->pass < 7) return; } /* Here after at the end of the last row of the last pass. */ png_read_finish_IDAT(png_ptr); } #endif /* SEQUENTIAL_READ */ void /* PRIVATE */ png_read_start_row(png_structrp png_ptr) { unsigned int max_pixel_depth; size_t row_bytes; png_debug(1, "in png_read_start_row"); #ifdef PNG_READ_TRANSFORMS_SUPPORTED png_init_read_transformations(png_ptr); #endif if (png_ptr->interlaced != 0) { if ((png_ptr->transformations & PNG_INTERLACE) == 0) png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 - png_pass_ystart[0]) / png_pass_yinc[0]; else png_ptr->num_rows = png_ptr->height; png_ptr->iwidth = (png_ptr->width + png_pass_inc[png_ptr->pass] - 1 - png_pass_start[png_ptr->pass]) / png_pass_inc[png_ptr->pass]; } else { png_ptr->num_rows = png_ptr->height; png_ptr->iwidth = png_ptr->width; } max_pixel_depth = (unsigned int)png_ptr->pixel_depth; /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpler set of * calculations to calculate the final pixel depth, then * png_do_read_transforms actually does the transforms. This means that the * code which effectively calculates this value is actually repeated in three * separate places. They must all match. Innocent changes to the order of * transformations can and will break libpng in a way that causes memory * overwrites. * * TODO: fix this. */ #ifdef PNG_READ_PACK_SUPPORTED if ((png_ptr->transformations & PNG_PACK) != 0 && png_ptr->bit_depth < 8) max_pixel_depth = 8; #endif #ifdef PNG_READ_EXPAND_SUPPORTED if ((png_ptr->transformations & PNG_EXPAND) != 0) { if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { if (png_ptr->num_trans != 0) max_pixel_depth = 32; else max_pixel_depth = 24; } else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY) { if (max_pixel_depth < 8) max_pixel_depth = 8; if (png_ptr->num_trans != 0) max_pixel_depth *= 2; } else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB) { if (png_ptr->num_trans != 0) { max_pixel_depth *= 4; max_pixel_depth /= 3; } } } #endif #ifdef PNG_READ_EXPAND_16_SUPPORTED if ((png_ptr->transformations & PNG_EXPAND_16) != 0) { # ifdef PNG_READ_EXPAND_SUPPORTED /* In fact it is an error if it isn't supported, but checking is * the safe way. */ if ((png_ptr->transformations & PNG_EXPAND) != 0) { if (png_ptr->bit_depth < 16) max_pixel_depth *= 2; } else # endif png_ptr->transformations &= ~PNG_EXPAND_16; } #endif #ifdef PNG_READ_FILLER_SUPPORTED if ((png_ptr->transformations & (PNG_FILLER)) != 0) { if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY) { if (max_pixel_depth <= 8) max_pixel_depth = 16; else max_pixel_depth = 32; } else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB || png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { if (max_pixel_depth <= 32) max_pixel_depth = 32; else max_pixel_depth = 64; } } #endif #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0) { if ( #ifdef PNG_READ_EXPAND_SUPPORTED (png_ptr->num_trans != 0 && (png_ptr->transformations & PNG_EXPAND) != 0) || #endif #ifdef PNG_READ_FILLER_SUPPORTED (png_ptr->transformations & (PNG_FILLER)) != 0 || #endif png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) { if (max_pixel_depth <= 16) max_pixel_depth = 32; else max_pixel_depth = 64; } else { if (max_pixel_depth <= 8) { if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA) max_pixel_depth = 32; else max_pixel_depth = 24; } else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA) max_pixel_depth = 64; else max_pixel_depth = 48; } } #endif #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0) { unsigned int user_pixel_depth = png_ptr->user_transform_depth * png_ptr->user_transform_channels; if (user_pixel_depth > max_pixel_depth) max_pixel_depth = user_pixel_depth; } #endif /* This value is stored in png_struct and double checked in the row read * code. */ png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth; png_ptr->transformed_pixel_depth = 0; /* calculated on demand */ /* Align the width on the next larger 8 pixels. Mainly used * for interlacing */ row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7)); /* Calculate the maximum bytes needed, adding a byte and a pixel * for safety's sake */ row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) + 1 + ((max_pixel_depth + 7) >> 3U); #ifdef PNG_MAX_MALLOC_64K if (row_bytes > (png_uint_32)65536L) png_error(png_ptr, "This image requires a row greater than 64KB"); #endif if (row_bytes + 48 > png_ptr->old_big_row_buf_size) { png_free(png_ptr, png_ptr->big_row_buf); png_free(png_ptr, png_ptr->big_prev_row); if (png_ptr->interlaced != 0) png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr, row_bytes + 48); else png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48); png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48); #ifdef PNG_ALIGNED_MEMORY_SUPPORTED /* Use 16-byte aligned memory for row_buf with at least 16 bytes * of padding before and after row_buf; treat prev_row similarly. * NOTE: the alignment is to the start of the pixels, one beyond the start * of the buffer, because of the filter byte. Prior to libpng 1.5.6 this * was incorrect; the filter byte was aligned, which had the exact * opposite effect of that intended. */ { png_bytep temp = png_ptr->big_row_buf + 32; size_t extra = (size_t)temp & 0x0f; png_ptr->row_buf = temp - extra - 1/*filter byte*/; temp = png_ptr->big_prev_row + 32; extra = (size_t)temp & 0x0f; png_ptr->prev_row = temp - extra - 1/*filter byte*/; } #else /* Use 31 bytes of padding before and 17 bytes after row_buf. */ png_ptr->row_buf = png_ptr->big_row_buf + 31; png_ptr->prev_row = png_ptr->big_prev_row + 31; #endif png_ptr->old_big_row_buf_size = row_bytes + 48; } #ifdef PNG_MAX_MALLOC_64K if (png_ptr->rowbytes > 65535) png_error(png_ptr, "This image requires a row greater than 64KB"); #endif if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1)) png_error(png_ptr, "Row has too many bytes to allocate in memory"); memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1); png_debug1(3, "width = %u,", png_ptr->width); png_debug1(3, "height = %u,", png_ptr->height); png_debug1(3, "iwidth = %u,", png_ptr->iwidth); png_debug1(3, "num_rows = %u,", png_ptr->num_rows); png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes); png_debug1(3, "irowbytes = %lu", (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1); /* The sequential reader needs a buffer for IDAT, but the progressive reader * does not, so free the read buffer now regardless; the sequential reader * reallocates it on demand. */ if (png_ptr->read_buffer != NULL) { png_bytep buffer = png_ptr->read_buffer; png_ptr->read_buffer_size = 0; png_ptr->read_buffer = NULL; png_free(png_ptr, buffer); } /* Finally claim the zstream for the inflate of the IDAT data, use the bits * value from the stream (note that this will result in a fatal error if the * IDAT stream has a bogus deflate header window_bits value, but this should * not be happening any longer!) */ if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK) png_error(png_ptr, png_ptr->zstream.msg); png_ptr->flags |= PNG_FLAG_ROW_INIT; } #ifdef PNG_READ_APNG_SUPPORTED /* This function is to be called after the main IDAT set has been read and * before a new IDAT is read. It resets some parts of png_ptr * to make them usable by the read functions again */ void /* PRIVATE */ png_read_reset(png_structp png_ptr) { png_ptr->mode &= ~PNG_HAVE_IDAT; png_ptr->mode &= ~PNG_AFTER_IDAT; png_ptr->row_number = 0; png_ptr->pass = 0; } void /* PRIVATE */ png_read_reinit(png_structp png_ptr, png_infop info_ptr) { png_ptr->width = info_ptr->next_frame_width; png_ptr->height = info_ptr->next_frame_height; png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth,png_ptr->width); png_ptr->info_rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, png_ptr->width); if (png_ptr->prev_row != NULL) memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1); } #ifdef PNG_PROGRESSIVE_READ_SUPPORTED /* same as png_read_reset() but for the progressive reader */ void /* PRIVATE */ png_progressive_read_reset(png_structp png_ptr) { #ifdef PNG_READ_INTERLACING_SUPPORTED /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ /* Start of interlace block */ static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0}; /* Offset to next interlace block */ static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1}; /* Start of interlace block in the y direction */ static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1}; /* Offset to next interlace block in the y direction */ static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2}; if (png_ptr->interlaced != 0) { if ((png_ptr->transformations & PNG_INTERLACE) == 0) png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 - png_pass_ystart[0]) / png_pass_yinc[0]; else png_ptr->num_rows = png_ptr->height; png_ptr->iwidth = (png_ptr->width + png_pass_inc[png_ptr->pass] - 1 - png_pass_start[png_ptr->pass]) / png_pass_inc[png_ptr->pass]; } else #endif /* READ_INTERLACING */ { png_ptr->num_rows = png_ptr->height; png_ptr->iwidth = png_ptr->width; } png_ptr->flags &= ~PNG_FLAG_ZSTREAM_ENDED; if (inflateReset(&(png_ptr->zstream)) != Z_OK) png_error(png_ptr, "inflateReset failed"); png_ptr->zstream.avail_in = 0; png_ptr->zstream.next_in = 0; png_ptr->zstream.next_out = png_ptr->row_buf; png_ptr->zstream.avail_out = (uInt)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1; } #endif /* PROGRESSIVE_READ */ #endif /* READ_APNG */ #endif /* READ */
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2026-10-09