diff options
| author | ManoloFLTK <41016272+ManoloFLTK@users.noreply.github.com> | 2025-09-07 18:06:14 +0200 |
|---|---|---|
| committer | ManoloFLTK <41016272+ManoloFLTK@users.noreply.github.com> | 2025-09-07 18:06:39 +0200 |
| commit | 27e02a1541db180e3d4260732461a080dab593a1 (patch) | |
| tree | 85b14e9d0937a3c8c615c2c3ddc6644b0c58768a /png/pngrutil.c | |
| parent | 1182cd66ec66cc317af2db44d21c2e56b99536e8 (diff) | |
Update bundled libpng to version 1.6.50 dated 2025-07-01
Diffstat (limited to 'png/pngrutil.c')
| -rw-r--r-- | png/pngrutil.c | 1873 |
1 files changed, 944 insertions, 929 deletions
diff --git a/png/pngrutil.c b/png/pngrutil.c index d31dc21da..e7c7bbe48 100644 --- a/png/pngrutil.c +++ b/png/pngrutil.c @@ -1,7 +1,6 @@ - /* pngrutil.c - utilities to read a PNG file * - * Copyright (c) 2018-2024 Cosmin Truta + * 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. @@ -18,6 +17,26 @@ #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) { @@ -29,30 +48,6 @@ png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf) return uval; } -#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED) -/* The following is a variation on the above for use with the fixed - * point values used for gAMA and cHRM. Instead of png_error it - * issues a warning and returns (-1) - an invalid value because both - * gAMA and cHRM use *unsigned* integers for fixed point values. - */ -#define PNG_FIXED_ERROR (-1) - -static png_fixed_point /* PRIVATE */ -png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf) -{ - png_uint_32 uval = png_get_uint_32(buf); - - if (uval <= PNG_UINT_31_MAX) - return (png_fixed_point)uval; /* known to be in range */ - - /* The caller can turn off the warning by passing NULL. */ - if (png_ptr != NULL) - png_warning(png_ptr, "PNG fixed point integer out of range"); - - return PNG_FIXED_ERROR; -} -#endif - #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, @@ -149,6 +144,38 @@ png_read_sig(png_structrp png_ptr, png_inforp info_ptr) 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. */ @@ -156,33 +183,36 @@ png_uint_32 /* PRIVATE */ png_read_chunk_header(png_structrp png_ptr) { png_byte buf[8]; - png_uint_32 length; + 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. - * This must be performed in a single I/O call. + /* 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); - /* Put the chunk name into png_ptr->chunk_name. */ - png_ptr->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); - /* Reset the crc and run it over the chunk name. */ - png_reset_crc(png_ptr); - png_calculate_crc(png_ptr, buf + 4, 4); + /* 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. */ - png_check_chunk_name(png_ptr, png_ptr->chunk_name); - - /* Check for too-large chunk length */ - png_check_chunk_length(png_ptr, length); + 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; @@ -202,13 +232,85 @@ png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 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. */ -int /* PRIVATE */ -png_crc_finish(png_structrp png_ptr, png_uint_32 skip) +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. @@ -226,14 +328,24 @@ png_crc_finish(png_structrp png_ptr, png_uint_32 skip) png_crc_read(png_ptr, tmpbuf, len); } - if (png_crc_error(png_ptr) != 0) + /* 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) { - if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 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"); @@ -244,61 +356,29 @@ png_crc_finish(png_structrp png_ptr, png_uint_32 skip) return 0; } -/* Compare the CRC stored in the PNG file with that calculated by libpng from - * the data it has read thus far. - */ int /* PRIVATE */ -png_crc_error(png_structrp png_ptr) +png_crc_finish(png_structrp png_ptr, png_uint_32 skip) { - png_byte crc_bytes[4]; - png_uint_32 crc; - int need_crc = 1; - - if (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; + 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_SEQUENTIAL_READ_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 (via png_malloc) on failure. (warn == 2 means - * 'silent'). + * it will call png_error on failure. */ static png_bytep -png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn) +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; @@ -313,24 +393,17 @@ png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn) if (buffer != NULL) { - memset(buffer, 0, new_size); /* just in case */ +# 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; } - - else if (warn < 2) /* else silent */ - { - if (warn != 0) - png_chunk_warning(png_ptr, "insufficient memory to read chunk"); - - else - png_chunk_error(png_ptr, "insufficient memory to read chunk"); - } } return buffer; } -#endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */ +#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 @@ -617,16 +690,7 @@ png_decompress_chunk(png_structrp png_ptr, * 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_SIZE_MAX; - -# ifdef PNG_SET_USER_LIMITS_SUPPORTED - if (png_ptr->user_chunk_malloc_max > 0 && - png_ptr->user_chunk_malloc_max < limit) - limit = png_ptr->user_chunk_malloc_max; -# elif PNG_USER_CHUNK_MALLOC_MAX > 0 - if (PNG_USER_CHUNK_MALLOC_MAX < limit) - limit = PNG_USER_CHUNK_MALLOC_MAX; -# endif + png_alloc_size_t limit = png_chunk_max(png_ptr); if (limit >= prefix_size + (terminate != 0)) { @@ -831,9 +895,9 @@ png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size, } #endif /* READ_iCCP */ +/* CHUNK HANDLING */ /* Read and check the IDHR chunk */ - -void /* PRIVATE */ +static png_handle_result_code png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_byte buf[13]; @@ -843,12 +907,7 @@ png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_debug(1, "in png_handle_IHDR"); - if ((png_ptr->mode & PNG_HAVE_IHDR) != 0) - png_chunk_error(png_ptr, "out of place"); - - /* Check the length */ - if (length != 13) - png_chunk_error(png_ptr, "invalid"); + /* Length and position are checked by the caller. */ png_ptr->mode |= PNG_HAVE_IHDR; @@ -902,257 +961,196 @@ png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 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 */ -void /* PRIVATE */ +/* 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_color palette[PNG_MAX_PALETTE_LENGTH]; - int max_palette_length, num, i; -#ifdef PNG_POINTER_INDEXING_SUPPORTED - png_colorp pal_ptr; -#endif + png_const_charp errmsg = NULL; png_debug(1, "in png_handle_PLTE"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - /* Moved to before the 'after IDAT' check below because otherwise duplicate - * PLTE chunks are potentially ignored (the spec says there shall not be more - * than one PLTE, the error is not treated as benign, so this check trumps - * the requirement that PLTE appears before IDAT.) + /* 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. */ - else if ((png_ptr->mode & PNG_HAVE_PLTE) != 0) - png_chunk_error(png_ptr, "duplicate"); + if ((png_ptr->mode & PNG_HAVE_PLTE) != 0) + errmsg = "duplicate"; else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) - { - /* This is benign because the non-benign error happened before, when an - * IDAT was encountered in a color-mapped image with no PLTE. - */ - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } + errmsg = "out of place"; - png_ptr->mode |= PNG_HAVE_PLTE; + else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) + errmsg = "ignored in grayscale PNG"; - if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "ignored in grayscale PNG"); - return; - } + else if (length > 3*PNG_MAX_PALETTE_LENGTH || (length % 3) != 0) + errmsg = "invalid"; -#ifndef PNG_READ_OPT_PLTE_SUPPORTED - if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE) - { - png_crc_finish(png_ptr, length); - return; - } -#endif + /* 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 definately 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"; - if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3) + else { - png_crc_finish(png_ptr, length); - - if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE) - png_chunk_benign_error(png_ptr, "invalid"); - - else - png_chunk_error(png_ptr, "invalid"); - - return; - } + /* 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 */ - num = (int)length / 3; + /* 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; - /* 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. - */ - if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) - max_palette_length = (1 << png_ptr->bit_depth); - else - max_palette_length = PNG_MAX_PALETTE_LENGTH; + unsigned i, j; + png_byte buf[3*PNG_MAX_PALETTE_LENGTH]; + png_color palette[PNG_MAX_PALETTE_LENGTH]; - if (num > max_palette_length) - num = 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); -#ifdef PNG_POINTER_INDEXING_SUPPORTED - for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++) - { - png_byte buf[3]; + for (i = 0U, j = 0U; i < num; i++) + { + palette[i].red = buf[j++]; + palette[i].green = buf[j++]; + palette[i].blue = buf[j++]; + } - png_crc_read(png_ptr, buf, 3); - pal_ptr->red = buf[0]; - pal_ptr->green = buf[1]; - pal_ptr->blue = buf[2]; - } -#else - for (i = 0; i < num; i++) - { - png_byte buf[3]; + /* A valid PLTE chunk has been read */ + png_ptr->mode |= PNG_HAVE_PLTE; - png_crc_read(png_ptr, buf, 3); - /* Don't depend upon png_color being any order */ - palette[i].red = buf[0]; - palette[i].green = buf[1]; - palette[i].blue = buf[2]; + /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to + * its own copy of the palette. This has the side effect that when + * png_start_row is called (this happens after any call to + * png_read_update_info) the info_ptr palette gets changed. This is + * extremely unexpected and confusing. + * + * REVIEW: there have been consistent bugs in the past about gamma and + * similar transforms to colour mapped images being useless because the + * modified palette cannot be accessed because of the above. + * + * CONSIDER: Fix this by not sharing the palette in this way. But does + * this completely fix the problem? + */ + png_set_PLTE(png_ptr, info_ptr, palette, num); + return handled_ok; } -#endif - /* If we actually need the PLTE chunk (ie for a paletted image), we do - * whatever the normal CRC configuration tells us. However, if we - * have an RGB image, the PLTE can be considered ancillary, so - * we will act as though it is. - */ -#ifndef PNG_READ_OPT_PLTE_SUPPORTED + /* Here on error: errmsg is non NULL. */ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) -#endif { - png_crc_finish(png_ptr, (png_uint_32) (length - (unsigned int)num * 3)); + png_crc_finish(png_ptr, length); + png_chunk_error(png_ptr, errmsg); } -#ifndef PNG_READ_OPT_PLTE_SUPPORTED - else if (png_crc_error(png_ptr) != 0) /* Only if we have a CRC error */ + else /* not critical to this image */ { - /* If we don't want to use the data from an ancillary chunk, - * we have two options: an error abort, or a warning and we - * ignore the data in this chunk (which should be OK, since - * it's considered ancillary for a RGB or RGBA image). - * - * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the - * chunk type to determine whether to check the ancillary or the critical - * flags. - */ - if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE) == 0) - { - if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) != 0) - return; - - else - png_chunk_error(png_ptr, "CRC error"); - } - - /* Otherwise, we (optionally) emit a warning and use the chunk. */ - else if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0) - png_chunk_warning(png_ptr, "CRC error"); + png_crc_finish_critical(png_ptr, length, 1/*handle as ancillary*/); + png_chunk_benign_error(png_ptr, errmsg); } -#endif - /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its - * own copy of the palette. This has the side effect that when png_start_row - * is called (this happens after any call to png_read_update_info) the - * info_ptr palette gets changed. This is extremely unexpected and - * confusing. - * - * Fix this by not sharing the palette in this way. - */ - png_set_PLTE(png_ptr, info_ptr, palette, num); - - /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before - * IDAT. Prior to 1.6.0 this was not checked; instead the code merely - * checked the apparent validity of a tRNS chunk inserted before PLTE on a - * palette PNG. 1.6.0 attempts to rigorously follow the standard and - * therefore does a benign error if the erroneous condition is detected *and* - * cancels the tRNS if the benign error returns. The alternative is to - * amend the standard since it would be rather hypocritical of the standards - * maintainers to ignore it. + /* Because PNG_UNUSED(errmsg) does not work if all the uses are compiled out + * (this does happen). */ -#ifdef PNG_READ_tRNS_SUPPORTED - if (png_ptr->num_trans > 0 || - (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0)) - { - /* Cancel this because otherwise it would be used if the transforms - * require it. Don't cancel the 'valid' flag because this would prevent - * detection of duplicate chunks. - */ - png_ptr->num_trans = 0; - - if (info_ptr != NULL) - info_ptr->num_trans = 0; - - png_chunk_benign_error(png_ptr, "tRNS must be after"); - } -#endif - -#ifdef PNG_READ_hIST_SUPPORTED - if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0) - png_chunk_benign_error(png_ptr, "hIST must be after"); -#endif - -#ifdef PNG_READ_bKGD_SUPPORTED - if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0) - png_chunk_benign_error(png_ptr, "bKGD must be after"); -#endif + return errmsg != NULL ? handled_error : handled_error; } -void /* PRIVATE */ +/* 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"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0 || - (png_ptr->mode & PNG_HAVE_IDAT) == 0) - png_chunk_error(png_ptr, "out of place"); - png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND); - png_crc_finish(png_ptr, length); - 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 -void /* PRIVATE */ +static png_handle_result_code png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { - png_fixed_point igamma; + png_uint_32 ugamma; png_byte buf[4]; png_debug(1, "in png_handle_gAMA"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); + png_crc_read(png_ptr, buf, 4); - else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } + if (png_crc_finish(png_ptr, 0) != 0) + return handled_error; - if (length != 4) + ugamma = png_get_uint_32(buf); + + if (ugamma > PNG_UINT_31_MAX) { - png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); - return; + return handled_error; } - png_crc_read(png_ptr, buf, 4); + png_set_gAMA_fixed(png_ptr, info_ptr, (png_fixed_point)/*SAFE*/ugamma); - if (png_crc_finish(png_ptr, 0) != 0) - return; - - igamma = png_get_fixed_point(NULL, buf); +#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*/ - png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma); - png_colorspace_sync(png_ptr, info_ptr); + return handled_ok; + PNG_UNUSED(length) } +#else +# define png_handle_gAMA NULL #endif #ifdef PNG_READ_sBIT_SUPPORTED -void /* PRIVATE */ +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; @@ -1161,23 +1159,6 @@ png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_debug(1, "in png_handle_sBIT"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - - if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "duplicate"); - return; - } - if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { truelen = 3; @@ -1190,25 +1171,25 @@ png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) sample_depth = png_ptr->bit_depth; } - if (length != truelen || length > 4) + if (length != truelen) { - png_chunk_benign_error(png_ptr, "invalid"); png_crc_finish(png_ptr, length); - return; + 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; + 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; + return handled_error; } } @@ -1220,7 +1201,7 @@ png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_ptr->sig_bit.alpha = buf[3]; } - else + else /* grayscale */ { png_ptr->sig_bit.gray = buf[0]; png_ptr->sig_bit.red = buf[0]; @@ -1230,133 +1211,132 @@ png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) } 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 -void /* PRIVATE */ -png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) +static png_int_32 +png_get_int_32_checked(png_const_bytep buf, int *error) { - png_byte buf[32]; - png_xy xy; + png_uint_32 uval = png_get_uint_32(buf); + if ((uval & 0x80000000) == 0) /* non-negative */ + return (png_int_32)uval; - png_debug(1, "in png_handle_cHRM"); + uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */ + if ((uval & 0x80000000) == 0) /* no overflow */ + return -(png_int_32)uval; - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); + /* This version of png_get_int_32 has a way of returning the error to the + * caller, so: + */ + *error = 1; + return 0; /* Safe */ +} - else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } +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]; - if (length != 32) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "invalid"); - return; - } + png_debug(1, "in png_handle_cHRM"); png_crc_read(png_ptr, buf, 32); if (png_crc_finish(png_ptr, 0) != 0) - return; + return handled_error; - xy.whitex = png_get_fixed_point(NULL, buf); - xy.whitey = png_get_fixed_point(NULL, buf + 4); - xy.redx = png_get_fixed_point(NULL, buf + 8); - xy.redy = png_get_fixed_point(NULL, buf + 12); - xy.greenx = png_get_fixed_point(NULL, buf + 16); - xy.greeny = png_get_fixed_point(NULL, buf + 20); - xy.bluex = png_get_fixed_point(NULL, buf + 24); - xy.bluey = png_get_fixed_point(NULL, buf + 28); - - if (xy.whitex == PNG_FIXED_ERROR || - xy.whitey == PNG_FIXED_ERROR || - xy.redx == PNG_FIXED_ERROR || - xy.redy == PNG_FIXED_ERROR || - xy.greenx == PNG_FIXED_ERROR || - xy.greeny == PNG_FIXED_ERROR || - xy.bluex == PNG_FIXED_ERROR || - xy.bluey == PNG_FIXED_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 values"); - return; + png_chunk_benign_error(png_ptr, "invalid"); + return handled_error; } - /* If a colorspace error has already been output skip this chunk */ - if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0) - return; + /* 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. Ridiculousity 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); - if ((png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0) - { - png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID; - png_colorspace_sync(png_ptr, info_ptr); - png_chunk_benign_error(png_ptr, "duplicate"); - return; - } + /* 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 */ - png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM; - (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy, - 1/*prefer cHRM values*/); - png_colorspace_sync(png_ptr, info_ptr); + return handled_ok; + PNG_UNUSED(length) } +#else +# define png_handle_cHRM NULL #endif #ifdef PNG_READ_sRGB_SUPPORTED -void /* PRIVATE */ +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"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - - if (length != 1) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "invalid"); - return; - } - png_crc_read(png_ptr, &intent, 1); if (png_crc_finish(png_ptr, 0) != 0) - return; - - /* If a colorspace error has already been output skip this chunk */ - if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0) - return; + return handled_error; - /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect - * this. + /* 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 ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) != 0) + if (intent > 3/*PNGv3 spec*/) { - png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID; - png_colorspace_sync(png_ptr, info_ptr); - png_chunk_benign_error(png_ptr, "too many profiles"); - return; + png_chunk_benign_error(png_ptr, "invalid"); + return handled_error; } - (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent); - png_colorspace_sync(png_ptr, info_ptr); + 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 -void /* PRIVATE */ +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 */ { @@ -1365,44 +1345,10 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_debug(1, "in png_handle_iCCP"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - - /* Consistent with all the above colorspace handling an obviously *invalid* - * chunk is just ignored, so does not invalidate the color space. An - * alternative is to set the 'invalid' flags at the start of this routine - * and only clear them in they were not set before and all the tests pass. - */ - - /* The keyword must be at least one character and there is a - * terminator (0) byte and the compression method byte, and the - * 'zlib' datastream is at least 11 bytes. + /* 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. */ - if (length < 14) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "too short"); - return; - } - - /* If a colorspace error has already been output skip this chunk */ - if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0) - { - png_crc_finish(png_ptr, length); - return; - } - - /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect - * this. - */ - if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0) { uInt read_length, keyword_length; char keyword[81]; @@ -1412,19 +1358,16 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) */ read_length = 81; /* maximum */ if (read_length > length) - read_length = (uInt)length; + read_length = (uInt)/*SAFE*/length; png_crc_read(png_ptr, (png_bytep)keyword, read_length); length -= read_length; - /* The minimum 'zlib' stream is assumed to be just the 2 byte header, - * 5 bytes minimum 'deflate' stream, and the 4 byte checksum. - */ - if (length < 11) + if (length < LZ77Min) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "too short"); - return; + return handled_error; } keyword_length = 0; @@ -1461,15 +1404,14 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) */ png_uint_32 profile_length = png_get_uint_32(profile_header); - if (png_icc_check_length(png_ptr, &png_ptr->colorspace, - keyword, profile_length) != 0) + 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, &png_ptr->colorspace, - keyword, profile_length, profile_header, - png_ptr->color_type) != 0) + 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 @@ -1479,7 +1421,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_uint_32 tag_count = png_get_uint_32(profile_header + 128); png_bytep profile = png_read_buffer(png_ptr, - profile_length, 2/*silent*/); + profile_length); if (profile != NULL) { @@ -1498,8 +1440,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (size == 0) { if (png_icc_check_tag_table(png_ptr, - &png_ptr->colorspace, keyword, profile_length, - profile) != 0) + keyword, profile_length, profile) != 0) { /* The profile has been validated for basic * security issues, so read the whole thing in. @@ -1531,13 +1472,6 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_crc_finish(png_ptr, length); finished = 1; -# if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0 - /* Check for a match against sRGB */ - png_icc_set_sRGB(png_ptr, - &png_ptr->colorspace, profile, - png_ptr->zstream.adler); -# endif - /* Steal the profile for info_ptr. */ if (info_ptr != NULL) { @@ -1560,11 +1494,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) } else - { - png_ptr->colorspace.flags |= - PNG_COLORSPACE_INVALID; errmsg = "out of memory"; - } } /* else the profile remains in the read @@ -1572,13 +1502,10 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) * chunks. */ - if (info_ptr != NULL) - png_colorspace_sync(png_ptr, info_ptr); - if (errmsg == NULL) { png_ptr->zowner = 0; - return; + return handled_ok; } } if (errmsg == NULL) @@ -1619,22 +1546,21 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) errmsg = "bad keyword"; } - else - errmsg = "too many profiles"; - /* Failure: the reason is in 'errmsg' */ if (finished == 0) png_crc_finish(png_ptr, length); - png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID; - png_colorspace_sync(png_ptr, info_ptr); 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 -void /* PRIVATE */ +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 */ { @@ -1655,43 +1581,24 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); - return; + 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; + return handled_error; } } #endif - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - -#ifdef PNG_MAX_MALLOC_64K - if (length > 65535U) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "too large to fit in memory"); - return; - } -#endif - - buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/); + 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; + return handled_error; } @@ -1702,7 +1609,7 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, skip) != 0) - return; + return handled_error; buffer[length] = 0; @@ -1715,7 +1622,7 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (length < 2U || entry_start > buffer + (length - 2U)) { png_warning(png_ptr, "malformed sPLT chunk"); - return; + return handled_error; } new_palette.depth = *entry_start++; @@ -1729,7 +1636,7 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if ((data_length % (unsigned int)entry_size) != 0) { png_warning(png_ptr, "sPLT chunk has bad length"); - return; + return handled_error; } dl = (png_uint_32)(data_length / (unsigned int)entry_size); @@ -1738,7 +1645,7 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (dl > max_dl) { png_warning(png_ptr, "sPLT chunk too long"); - return; + return handled_error; } new_palette.nentries = (png_int_32)(data_length / (unsigned int)entry_size); @@ -1749,10 +1656,9 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (new_palette.entries == NULL) { png_warning(png_ptr, "sPLT chunk requires too much memory"); - return; + return handled_error; } -#ifdef PNG_POINTER_INDEXING_SUPPORTED for (i = 0; i < new_palette.nentries; i++) { pp = new_palette.entries + i; @@ -1775,31 +1681,6 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) pp->frequency = png_get_uint_16(entry_start); entry_start += 2; } -#else - pp = new_palette.entries; - - for (i = 0; i < new_palette.nentries; i++) - { - - if (new_palette.depth == 8) - { - pp[i].red = *entry_start++; - pp[i].green = *entry_start++; - pp[i].blue = *entry_start++; - pp[i].alpha = *entry_start++; - } - - else - { - pp[i].red = png_get_uint_16(entry_start); entry_start += 2; - pp[i].green = png_get_uint_16(entry_start); entry_start += 2; - pp[i].blue = png_get_uint_16(entry_start); entry_start += 2; - pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2; - } - - pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2; - } -#endif /* Discard all chunk data except the name and stash that */ new_palette.name = (png_charp)buffer; @@ -1807,34 +1688,20 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 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 -void /* PRIVATE */ +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->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - - else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "duplicate"); - return; - } - if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY) { png_byte buf[2]; @@ -1843,7 +1710,7 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); - return; + return handled_error; } png_crc_read(png_ptr, buf, 2); @@ -1859,7 +1726,7 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); - return; + return handled_error; } png_crc_read(png_ptr, buf, length); @@ -1873,10 +1740,9 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { if ((png_ptr->mode & PNG_HAVE_PLTE) == 0) { - /* TODO: is this actually an error in the ISO spec? */ png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "out of place"); - return; + return handled_error; } if (length > (unsigned int) png_ptr->num_palette || @@ -1885,7 +1751,7 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); - return; + return handled_error; } png_crc_read(png_ptr, readbuf, length); @@ -1896,13 +1762,13 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid with alpha channel"); - return; + return handled_error; } if (png_crc_finish(png_ptr, 0) != 0) { png_ptr->num_trans = 0; - return; + return handled_error; } /* TODO: this is a horrible side effect in the palette case because the @@ -1911,11 +1777,14 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) */ 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 -void /* PRIVATE */ +static png_handle_result_code /* PRIVATE */ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { unsigned int truelen; @@ -1924,27 +1793,17 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_debug(1, "in png_handle_bKGD"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 || - (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && - (png_ptr->mode & PNG_HAVE_PLTE) == 0)) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - - else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0) + if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "duplicate"); - return; - } + 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 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) truelen = 1; + } else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) truelen = 6; @@ -1956,13 +1815,13 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); - return; + return handled_error; } png_crc_read(png_ptr, buf, truelen); if (png_crc_finish(png_ptr, 0) != 0) - return; + 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 @@ -1978,7 +1837,7 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (buf[0] >= info_ptr->num_palette) { png_chunk_benign_error(png_ptr, "invalid index"); - return; + return handled_error; } background.red = (png_uint_16)png_ptr->palette[buf[0]].red; @@ -1999,7 +1858,7 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (buf[0] != 0 || buf[1] >= (unsigned int)(1 << png_ptr->bit_depth)) { png_chunk_benign_error(png_ptr, "invalid gray level"); - return; + return handled_error; } } @@ -2017,7 +1876,7 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (buf[0] != 0 || buf[2] != 0 || buf[4] != 0) { png_chunk_benign_error(png_ptr, "invalid color"); - return; + return handled_error; } } @@ -2029,75 +1888,174 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) } 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 -void /* PRIVATE */ +static png_handle_result_code /* PRIVATE */ png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { - unsigned int i; + png_bytep buffer = NULL; png_debug(1, "in png_handle_eXIf"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); + buffer = png_read_buffer(png_ptr, length); - if (length < 2) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "too short"); - return; - } - - else if (info_ptr == NULL || (info_ptr->valid & PNG_INFO_eXIf) != 0) + if (buffer == NULL) { png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "duplicate"); - return; + png_chunk_benign_error(png_ptr, "out of memory"); + return handled_error; } - info_ptr->free_me |= PNG_FREE_EXIF; + png_crc_read(png_ptr, buffer, length); - info_ptr->eXIf_buf = png_voidcast(png_bytep, - png_malloc_warn(png_ptr, length)); + if (png_crc_finish(png_ptr, 0) != 0) + return handled_error; - if (info_ptr->eXIf_buf == NULL) + /* PNGv3: the code used to check the byte order mark at the start for MM or + * II, however PNGv3 states that the the first 4 bytes should be checked. + * The caller ensures that there are four bytes available. + */ { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of memory"); - return; - } + png_uint_32 header = png_get_uint_32(buffer); - for (i = 0; i < length; i++) - { - png_byte buf[1]; - png_crc_read(png_ptr, buf, 1); - info_ptr->eXIf_buf[i] = buf[0]; - if (i == 1) + /* These numbers are copied from the PNGv3 spec: */ + if (header != 0x49492A00 && header != 0x4D4D002A) { - if ((buf[0] != 'M' && buf[0] != 'I') || - (info_ptr->eXIf_buf[0] != buf[0])) - { - png_crc_finish(png_ptr, length - 2); - png_chunk_benign_error(png_ptr, "incorrect byte-order specifier"); - png_free(png_ptr, info_ptr->eXIf_buf); - info_ptr->eXIf_buf = NULL; - return; - } + png_chunk_benign_error(png_ptr, "invalid"); + return handled_error; } } - if (png_crc_finish(png_ptr, 0) == 0) - png_set_eXIf_1(png_ptr, info_ptr, length, info_ptr->eXIf_buf); - - png_free(png_ptr, info_ptr->eXIf_buf); - info_ptr->eXIf_buf = NULL; + 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 -void /* PRIVATE */ +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; @@ -2105,25 +2063,13 @@ png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_debug(1, "in png_handle_hIST"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 || - (png_ptr->mode & PNG_HAVE_PLTE) == 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - - else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "duplicate"); - return; - } - - num = length / 2 ; + /* 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 || @@ -2131,7 +2077,7 @@ png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_crc_finish(png_ptr, length); png_chunk_benign_error(png_ptr, "invalid"); - return; + return handled_error; } for (i = 0; i < num; i++) @@ -2143,14 +2089,17 @@ png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) } if (png_crc_finish(png_ptr, 0) != 0) - return; + 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 -void /* PRIVATE */ +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]; @@ -2159,44 +2108,24 @@ png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_debug(1, "in png_handle_pHYs"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - - else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "duplicate"); - return; - } - - if (length != 9) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "invalid"); - return; - } - png_crc_read(png_ptr, buf, 9); if (png_crc_finish(png_ptr, 0) != 0) - return; + 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 -void /* PRIVATE */ +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]; @@ -2205,45 +2134,25 @@ png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_debug(1, "in png_handle_oFFs"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - - else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "duplicate"); - return; - } - - if (length != 9) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "invalid"); - return; - } - png_crc_read(png_ptr, buf, 9); if (png_crc_finish(png_ptr, 0) != 0) - return; + 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) */ -void /* PRIVATE */ +static png_handle_result_code /* PRIVATE */ png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_int_32 X0, X1; @@ -2253,40 +2162,22 @@ png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) int i; png_debug(1, "in png_handle_pCAL"); - - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - - else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "duplicate"); - return; - } - png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)", length + 1); - buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/); + 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; + return handled_error; } png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, 0) != 0) - return; + return handled_error; buffer[length] = 0; /* Null terminate the last string */ @@ -2302,7 +2193,7 @@ png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (endptr - buf <= 12) { png_chunk_benign_error(png_ptr, "invalid"); - return; + return handled_error; } png_debug(3, "Reading pCAL X0, X1, type, nparams, and units"); @@ -2322,7 +2213,7 @@ png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) (type == PNG_EQUATION_HYPERBOLIC && nparams != 4)) { png_chunk_benign_error(png_ptr, "invalid parameter count"); - return; + return handled_error; } else if (type >= PNG_EQUATION_LAST) @@ -2341,7 +2232,7 @@ png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (params == NULL) { png_chunk_benign_error(png_ptr, "out of memory"); - return; + return handled_error; } /* Get pointers to the start of each parameter string. */ @@ -2359,20 +2250,29 @@ png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_free(png_ptr, params); png_chunk_benign_error(png_ptr, "invalid data"); - return; + 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 */ -void /* PRIVATE */ +static png_handle_result_code /* PRIVATE */ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { png_bytep buffer; @@ -2380,55 +2280,29 @@ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) int state; png_debug(1, "in png_handle_sCAL"); - - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "out of place"); - return; - } - - else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "duplicate"); - return; - } - - /* Need unit type, width, \0, height: minimum 4 bytes */ - else if (length < 4) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "invalid"); - return; - } - png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)", length + 1); - buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/); + buffer = png_read_buffer(png_ptr, length+1); if (buffer == NULL) { - png_chunk_benign_error(png_ptr, "out of memory"); png_crc_finish(png_ptr, length); - return; + 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; + return handled_error; /* Validate the unit. */ if (buffer[0] != 1 && buffer[0] != 2) { png_chunk_benign_error(png_ptr, "invalid unit"); - return; + return handled_error; } /* Validate the ASCII numbers, need two ASCII numbers separated by @@ -2457,15 +2331,22 @@ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 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 -void /* PRIVATE */ +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]; @@ -2473,30 +2354,17 @@ png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) png_debug(1, "in png_handle_tIME"); - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME) != 0) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "duplicate"); - return; - } - + /* 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; - if (length != 7) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "invalid"); - return; - } - png_crc_read(png_ptr, buf, 7); if (png_crc_finish(png_ptr, 0) != 0) - return; + return handled_error; mod_time.second = buf[6]; mod_time.minute = buf[5]; @@ -2506,12 +2374,16 @@ png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) 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 */ -void /* PRIVATE */ +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; @@ -2528,45 +2400,31 @@ png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); - return; + 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; + return handled_error; } } #endif - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) - png_ptr->mode |= PNG_AFTER_IDAT; - -#ifdef PNG_MAX_MALLOC_64K - if (length > 65535U) - { - png_crc_finish(png_ptr, length); - png_chunk_benign_error(png_ptr, "too large to fit in memory"); - return; - } -#endif - - buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/); + 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; + return handled_error; } png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, skip) != 0) - return; + return handled_error; key = (png_charp)buffer; key[length] = 0; @@ -2585,14 +2443,19 @@ png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) text_info.text = text; text_info.text_length = strlen(text); - if (png_set_text_2(png_ptr, info_ptr, &text_info, 1) != 0) - png_warning(png_ptr, "Insufficient memory to process text chunk"); + 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 */ -void /* PRIVATE */ +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; @@ -2607,40 +2470,35 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); - return; + 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; + return handled_error; } } #endif - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) - png_ptr->mode |= PNG_AFTER_IDAT; - /* Note, "length" is sufficient here; we won't be adding - * a null terminator later. + * a null terminator later. The limit check in png_handle_chunk should be + * sufficient. */ - buffer = png_read_buffer(png_ptr, length, 2/*silent*/); + 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; + return handled_error; } png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, 0) != 0) - return; + return handled_error; /* TODO: also check that the keyword contents match the spec! */ for (keyword_length = 0; @@ -2693,8 +2551,10 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) text.lang = NULL; text.lang_key = NULL; - if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0) - errmsg = "insufficient memory"; + if (png_set_text_2(png_ptr, info_ptr, &text, 1) == 0) + return handled_ok; + + errmsg = "out of memory"; } } @@ -2702,14 +2562,16 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) errmsg = png_ptr->zstream.msg; } - if (errmsg != NULL) - png_chunk_benign_error(png_ptr, errmsg); + 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 */ -void /* PRIVATE */ +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; @@ -2724,37 +2586,31 @@ png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (png_ptr->user_chunk_cache_max == 1) { png_crc_finish(png_ptr, length); - return; + 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; + return handled_error; } } #endif - if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) - png_chunk_error(png_ptr, "missing IHDR"); - - if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) - png_ptr->mode |= PNG_AFTER_IDAT; - - buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/); + 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; + return handled_error; } png_crc_read(png_ptr, buffer, length); if (png_crc_finish(png_ptr, 0) != 0) - return; + return handled_error; /* First the keyword. */ for (prefix_length=0; @@ -2844,8 +2700,10 @@ png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) text.text_length = 0; text.itxt_length = uncompressed_length; - if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0) - errmsg = "insufficient memory"; + if (png_set_text_2(png_ptr, info_ptr, &text, 1) == 0) + return handled_ok; + + errmsg = "out of memory"; } } @@ -2854,7 +2712,10 @@ png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) if (errmsg != NULL) png_chunk_benign_error(png_ptr, errmsg); + return handled_error; } +#else +# define png_handle_iTXt NULL #endif #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED @@ -2862,7 +2723,7 @@ png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) static int png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length) { - png_alloc_size_t limit = PNG_SIZE_MAX; + const png_alloc_size_t limit = png_chunk_max(png_ptr); if (png_ptr->unknown_chunk.data != NULL) { @@ -2870,16 +2731,6 @@ png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length) png_ptr->unknown_chunk.data = NULL; } -# ifdef PNG_SET_USER_LIMITS_SUPPORTED - if (png_ptr->user_chunk_malloc_max > 0 && - png_ptr->user_chunk_malloc_max < limit) - limit = png_ptr->user_chunk_malloc_max; - -# elif PNG_USER_CHUNK_MALLOC_MAX > 0 - if (PNG_USER_CHUNK_MALLOC_MAX < limit) - limit = PNG_USER_CHUNK_MALLOC_MAX; -# endif - if (length <= limit) { PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name); @@ -2918,11 +2769,11 @@ png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length) #endif /* READ_UNKNOWN_CHUNKS */ /* Handle an unknown, or known but disabled, chunk */ -void /* PRIVATE */ +png_handle_result_code /*PRIVATE*/ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length, int keep) { - int handled = 0; /* the chunk was handled */ + png_handle_result_code handled = handled_discarded; /* the default */ png_debug(1, "in png_handle_unknown"); @@ -2969,7 +2820,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr, * error at this point unless it is to be saved. * positive: The chunk was handled, libpng will ignore/discard it. */ - if (ret < 0) + if (ret < 0) /* handled_error */ png_chunk_error(png_ptr, "error in user chunk"); else if (ret == 0) @@ -3003,7 +2854,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr, else /* chunk was handled */ { - handled = 1; + handled = handled_ok; /* Critical chunks can be safely discarded at this point. */ keep = PNG_HANDLE_CHUNK_NEVER; } @@ -3088,7 +2939,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr, */ png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1); - handled = 1; + handled = handled_saved; # ifdef PNG_USER_LIMITS_SUPPORTED break; } @@ -3114,79 +2965,267 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr, #endif /* !READ_UNKNOWN_CHUNKS */ /* Check for unhandled critical chunks */ - if (handled == 0 && PNG_CHUNK_CRITICAL(png_ptr->chunk_name)) + if (handled < handled_saved && PNG_CHUNK_CRITICAL(png_ptr->chunk_name)) png_chunk_error(png_ptr, "unhandled critical chunk"); + + return handled; } -/* This function is called to verify that a chunk name is valid. - * This function can't have the "critical chunk check" incorporated - * into it, since in the future we will need to be able to call user - * functions to handle unknown critical chunks after we check that - * the chunk name itself is valid. +/* 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 -/* Bit hacking: the test for an invalid byte in the 4 byte chunk name is: +/* + * 1.6.47: This is the new table driven interface to all the chunk handling. * - * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97)) + * 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. */ - -void /* PRIVATE */ -png_check_chunk_name(png_const_structrp png_ptr, png_uint_32 chunk_name) +static const struct { - int i; - png_uint_32 cn=chunk_name; - - png_debug(1, "in png_check_chunk_name"); + 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. + */ - for (i=1; i<=4; ++i) + /* 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. Anciallary 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 occurences 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 + * hander 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) { - int c = cn & 0xff; +# define PNG_CHUNK(cHNK, index)\ + case png_ ## cHNK: return PNG_INDEX_ ## cHNK; /* == index */ + + PNG_KNOWN_CHUNKS - if (c < 65 || c > 122 || (c > 90 && c < 97)) - png_chunk_error(png_ptr, "invalid chunk type"); +# undef PNG_CHUNK - cn >>= 8; + default: return PNG_INDEX_unknown; } } -void /* PRIVATE */ -png_check_chunk_length(png_const_structrp png_ptr, png_uint_32 length) +png_handle_result_code /*PRIVATE*/ +png_handle_chunk(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length) { - png_alloc_size_t limit = PNG_UINT_31_MAX; - -# ifdef PNG_SET_USER_LIMITS_SUPPORTED - if (png_ptr->user_chunk_malloc_max > 0 && - png_ptr->user_chunk_malloc_max < limit) - limit = png_ptr->user_chunk_malloc_max; -# elif PNG_USER_CHUNK_MALLOC_MAX > 0 - if (PNG_USER_CHUNK_MALLOC_MAX < limit) - limit = PNG_USER_CHUNK_MALLOC_MAX; -# endif - if (png_ptr->chunk_name == png_IDAT) + /* 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) { - png_alloc_size_t idat_limit = PNG_UINT_31_MAX; - size_t row_factor = - (size_t)png_ptr->width - * (size_t)png_ptr->channels - * (png_ptr->bit_depth > 8? 2: 1) - + 1 - + (png_ptr->interlaced? 6: 0); - if (png_ptr->height > PNG_UINT_32_MAX/row_factor) - idat_limit = PNG_UINT_31_MAX; - else - idat_limit = png_ptr->height * row_factor; - row_factor = row_factor > 32566? 32566 : row_factor; - idat_limit += 6 + 5*(idat_limit/row_factor+1); /* zlib+deflate overhead */ - idat_limit=idat_limit < PNG_UINT_31_MAX? idat_limit : PNG_UINT_31_MAX; - limit = limit < idat_limit? idat_limit : limit; + 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"; } - if (length > limit) + else if (length < read_chunks[chunk_index].min_length) + errmsg = "too short"; + else { - png_debug2(0," length = %lu, limit = %lu", - (unsigned long)length,(unsigned long)limit); - png_benign_error(png_ptr, "chunk data is too large"); + /* 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 @@ -3684,10 +3723,6 @@ 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 */) { - /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ - /* Offset to next interlace block */ - static const unsigned int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; - png_debug(1, "in png_do_read_interlace"); if (row != NULL && row_info != NULL) { @@ -4180,6 +4215,9 @@ png_read_IDAT_data(png_structrp png_ptr, png_bytep output, 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; @@ -4187,8 +4225,13 @@ png_read_IDAT_data(png_structrp png_ptr, png_bytep output, * 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, 0/*error*/); + 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; @@ -4325,20 +4368,6 @@ png_read_finish_IDAT(png_structrp png_ptr) void /* PRIVATE */ png_read_finish_row(png_structrp png_ptr) { - /* Arrays to facilitate easy 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}; - png_debug(1, "in png_read_finish_row"); png_ptr->row_number++; if (png_ptr->row_number < png_ptr->num_rows) @@ -4390,20 +4419,6 @@ png_read_finish_row(png_structrp png_ptr) void /* PRIVATE */ png_read_start_row(png_structrp png_ptr) { - /* Arrays to facilitate easy 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}; - unsigned int max_pixel_depth; size_t row_bytes; |