diff options
Diffstat (limited to 'drivers/png/pngread.c')
| -rw-r--r-- | drivers/png/pngread.c | 3736 |
1 files changed, 3305 insertions, 431 deletions
diff --git a/drivers/png/pngread.c b/drivers/png/pngread.c index b90e017e62..0ff6238023 100644 --- a/drivers/png/pngread.c +++ b/drivers/png/pngread.c @@ -1,8 +1,8 @@ /* pngread.c - read a PNG file * - * Last changed in libpng 1.5.23 [July 23, 2015] - * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson + * Last changed in libpng 1.6.23 [June 9, 2016] + * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * @@ -15,6 +15,9 @@ */ #include "pngpriv.h" +#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED) +# include <errno.h> +#endif #ifdef PNG_READ_SUPPORTED @@ -23,10 +26,12 @@ PNG_FUNCTION(png_structp,PNGAPI png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED) { - -#ifdef PNG_USER_MEM_SUPPORTED - return (png_create_read_struct_2(user_png_ver, error_ptr, error_fn, - warn_fn, NULL, NULL, NULL)); +#ifndef PNG_USER_MEM_SUPPORTED + png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, + error_fn, warn_fn, NULL, NULL, NULL); +#else + return png_create_read_struct_2(user_png_ver, error_ptr, error_fn, + warn_fn, NULL, NULL, NULL); } /* Alternate create PNG structure for reading, and allocate any memory @@ -37,131 +42,40 @@ png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED) { -#endif /* PNG_USER_MEM_SUPPORTED */ - -#ifdef PNG_SETJMP_SUPPORTED - volatile -#endif - png_structp png_ptr; - volatile int png_cleanup_needed = 0; - -#ifdef PNG_SETJMP_SUPPORTED -#ifdef USE_FAR_KEYWORD - jmp_buf tmp_jmpbuf; -#endif -#endif - - png_debug(1, "in png_create_read_struct"); - -#ifdef PNG_USER_MEM_SUPPORTED - png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG, - malloc_fn, mem_ptr); -#else - png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG); -#endif - if (png_ptr == NULL) - return (NULL); - - /* Added at libpng-1.2.6 */ -#ifdef PNG_USER_LIMITS_SUPPORTED - png_ptr->user_width_max = PNG_USER_WIDTH_MAX; - png_ptr->user_height_max = PNG_USER_HEIGHT_MAX; - - /* Added at libpng-1.2.43 and 1.4.0 */ - png_ptr->user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX; - - /* Added at libpng-1.2.43 and 1.4.1 */ - png_ptr->user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX; -#endif - -#ifdef PNG_SETJMP_SUPPORTED -/* Applications that neglect to set up their own setjmp() and then - * encounter a png_error() will longjmp here. Since the jmpbuf is - * then meaningless we abort instead of returning. - */ -#ifdef USE_FAR_KEYWORD - if (setjmp(tmp_jmpbuf)) -#else - if (setjmp(png_jmpbuf(png_ptr))) /* Sets longjmp to match setjmp */ -#endif - PNG_ABORT(); -#ifdef USE_FAR_KEYWORD - png_memcpy(png_jmpbuf(png_ptr), tmp_jmpbuf, png_sizeof(jmp_buf)); -#endif -#endif /* PNG_SETJMP_SUPPORTED */ - -#ifdef PNG_USER_MEM_SUPPORTED - png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn); -#endif + png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, + error_fn, warn_fn, mem_ptr, malloc_fn, free_fn); +#endif /* USER_MEM */ - png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn); - - /* Call the general version checker (shared with read and write code): */ - if (!png_user_version_check(png_ptr, user_png_ver)) - png_cleanup_needed = 1; - - if (png_cleanup_needed == 0) + if (png_ptr != NULL) { - /* Initialize zbuf - compression buffer */ - png_ptr->zbuf_size = PNG_ZBUF_SIZE; - png_ptr->zbuf = (png_bytep)png_malloc_warn(png_ptr, png_ptr->zbuf_size); - - if (png_ptr->zbuf == NULL) - png_cleanup_needed = 1; - } - - png_ptr->zstream.zalloc = png_zalloc; - png_ptr->zstream.zfree = png_zfree; - png_ptr->zstream.opaque = (voidpf)png_ptr; + png_ptr->mode = PNG_IS_READ_STRUCT; - if (png_cleanup_needed == 0) - { - switch (inflateInit(&png_ptr->zstream)) - { - case Z_OK: - break; /* Do nothing */ - - case Z_MEM_ERROR: - png_warning(png_ptr, "zlib memory error"); - png_cleanup_needed = 1; - break; - - case Z_STREAM_ERROR: - png_warning(png_ptr, "zlib stream error"); - png_cleanup_needed = 1; - break; - - case Z_VERSION_ERROR: - png_warning(png_ptr, "zlib version error"); - png_cleanup_needed = 1; - break; + /* Added in libpng-1.6.0; this can be used to detect a read structure if + * required (it will be zero in a write structure.) + */ +# ifdef PNG_SEQUENTIAL_READ_SUPPORTED + png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE; +# endif - default: png_warning(png_ptr, "Unknown zlib error"); - png_cleanup_needed = 1; - } - } +# ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED + png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN; - if (png_cleanup_needed != 0) - { - /* Clean up PNG structure and deallocate any memory. */ - png_free(png_ptr, png_ptr->zbuf); - png_ptr->zbuf = NULL; -#ifdef PNG_USER_MEM_SUPPORTED - png_destroy_struct_2((png_voidp)png_ptr, - (png_free_ptr)free_fn, (png_voidp)mem_ptr); -#else - png_destroy_struct((png_voidp)png_ptr); -#endif - return (NULL); + /* In stable builds only warn if an application error can be completely + * handled. + */ +# if PNG_RELEASE_BUILD + png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN; +# endif +# endif + + /* TODO: delay this, it can be done in png_init_io (if the app doesn't + * do it itself) avoiding setting the default function if it is not + * required. + */ + png_set_read_fn(png_ptr, NULL, NULL); } - png_ptr->zstream.next_out = png_ptr->zbuf; - png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; - - png_set_read_fn(png_ptr, NULL, NULL); - - - return (png_ptr); + return png_ptr; } @@ -175,8 +89,12 @@ png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr, * read if it is determined that this isn't a valid PNG file. */ void PNGAPI -png_read_info(png_structp png_ptr, png_infop info_ptr) +png_read_info(png_structrp png_ptr, png_inforp info_ptr) { +#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED + int keep; +#endif + png_debug(1, "in png_read_info"); if (png_ptr == NULL || info_ptr == NULL) @@ -190,13 +108,33 @@ png_read_info(png_structp png_ptr, png_infop info_ptr) png_uint_32 length = png_read_chunk_header(png_ptr); png_uint_32 chunk_name = png_ptr->chunk_name; - /* This should be a binary subdivision search or a hash for - * matching the chunk name rather than a linear search. + /* IDAT logic needs to happen here to simplify getting the two flags + * right. */ if (chunk_name == png_IDAT) - if (png_ptr->mode & PNG_AFTER_IDAT) - png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT; + { + if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) + png_chunk_error(png_ptr, "Missing IHDR before IDAT"); + + else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && + (png_ptr->mode & PNG_HAVE_PLTE) == 0) + png_chunk_error(png_ptr, "Missing PLTE before IDAT"); + + else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0) + png_chunk_benign_error(png_ptr, "Too many IDATs found"); + + png_ptr->mode |= PNG_HAVE_IDAT; + } + + else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) + { + png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT; + png_ptr->mode |= PNG_AFTER_IDAT; + } + /* This should be a binary subdivision search or a hash for + * matching the chunk name rather than a linear search. + */ if (chunk_name == png_IHDR) png_handle_IHDR(png_ptr, info_ptr, length); @@ -204,26 +142,16 @@ png_read_info(png_structp png_ptr, png_infop info_ptr) png_handle_IEND(png_ptr, info_ptr, length); #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED - else if (png_chunk_unknown_handling(png_ptr, chunk_name) != - PNG_HANDLE_CHUNK_AS_DEFAULT) + else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) { - if (chunk_name == png_IDAT) - png_ptr->mode |= PNG_HAVE_IDAT; - - png_handle_unknown(png_ptr, info_ptr, length); + png_handle_unknown(png_ptr, info_ptr, length, keep); if (chunk_name == png_PLTE) png_ptr->mode |= PNG_HAVE_PLTE; else if (chunk_name == png_IDAT) { - if (!(png_ptr->mode & PNG_HAVE_IHDR)) - png_error(png_ptr, "Missing IHDR before IDAT"); - - else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && - !(png_ptr->mode & PNG_HAVE_PLTE)) - png_error(png_ptr, "Missing PLTE before IDAT"); - + png_ptr->idat_size = 0; /* It has been consumed */ break; } } @@ -233,15 +161,7 @@ png_read_info(png_structp png_ptr, png_infop info_ptr) else if (chunk_name == png_IDAT) { - if (!(png_ptr->mode & PNG_HAVE_IHDR)) - png_error(png_ptr, "Missing IHDR before IDAT"); - - else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && - !(png_ptr->mode & PNG_HAVE_PLTE)) - png_error(png_ptr, "Missing PLTE before IDAT"); - png_ptr->idat_size = length; - png_ptr->mode |= PNG_HAVE_IDAT; break; } @@ -331,27 +251,36 @@ png_read_info(png_structp png_ptr, png_infop info_ptr) #endif else - png_handle_unknown(png_ptr, info_ptr, length); + png_handle_unknown(png_ptr, info_ptr, length, + PNG_HANDLE_CHUNK_AS_DEFAULT); } } -#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ +#endif /* SEQUENTIAL_READ */ /* Optional call to update the users info_ptr structure */ void PNGAPI -png_read_update_info(png_structp png_ptr, png_infop info_ptr) +png_read_update_info(png_structrp png_ptr, png_inforp info_ptr) { png_debug(1, "in png_read_update_info"); - if (png_ptr == NULL) - return; + if (png_ptr != NULL) + { + if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) + { + png_read_start_row(png_ptr); - png_read_start_row(png_ptr); +# ifdef PNG_READ_TRANSFORMS_SUPPORTED + png_read_transform_info(png_ptr, info_ptr); +# else + PNG_UNUSED(info_ptr) +# endif + } -#ifdef PNG_READ_TRANSFORMS_SUPPORTED - png_read_transform_info(png_ptr, info_ptr); -#else - PNG_UNUSED(info_ptr) -#endif + /* New in 1.6.0 this avoids the bug of doing the initializations twice */ + else + png_app_error(png_ptr, + "png_read_update_info/png_start_read_image: duplicate call"); + } } #ifdef PNG_SEQUENTIAL_READ_SUPPORTED @@ -361,21 +290,93 @@ png_read_update_info(png_structp png_ptr, png_infop info_ptr) * If the user doesn't call this, we will do it ourselves. */ void PNGAPI -png_start_read_image(png_structp png_ptr) +png_start_read_image(png_structrp png_ptr) { png_debug(1, "in png_start_read_image"); if (png_ptr != NULL) - png_read_start_row(png_ptr); + { + if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) + png_read_start_row(png_ptr); + + /* New in 1.6.0 this avoids the bug of doing the initializations twice */ + else + png_app_error(png_ptr, + "png_start_read_image/png_read_update_info: duplicate call"); + } } -#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ +#endif /* SEQUENTIAL_READ */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED -void PNGAPI -png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) +#ifdef PNG_MNG_FEATURES_SUPPORTED +/* Undoes intrapixel differencing, + * NOTE: this is apparently only supported in the 'sequential' reader. + */ +static void +png_do_read_intrapixel(png_row_infop row_info, png_bytep row) { - int ret; + png_debug(1, "in png_do_read_intrapixel"); + if ( + (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0) + { + int bytes_per_pixel; + png_uint_32 row_width = row_info->width; + + if (row_info->bit_depth == 8) + { + png_bytep rp; + png_uint_32 i; + + if (row_info->color_type == PNG_COLOR_TYPE_RGB) + bytes_per_pixel = 3; + + else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) + bytes_per_pixel = 4; + + else + return; + + for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel) + { + *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff); + *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff); + } + } + else if (row_info->bit_depth == 16) + { + png_bytep rp; + png_uint_32 i; + + if (row_info->color_type == PNG_COLOR_TYPE_RGB) + bytes_per_pixel = 6; + + else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) + bytes_per_pixel = 8; + + else + return; + + for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel) + { + png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1); + png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3); + png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5); + png_uint_32 red = (s0 + s1 + 65536) & 0xffff; + png_uint_32 blue = (s2 + s1 + 65536) & 0xffff; + *(rp ) = (png_byte)((red >> 8) & 0xff); + *(rp + 1) = (png_byte)(red & 0xff); + *(rp + 4) = (png_byte)((blue >> 8) & 0xff); + *(rp + 5) = (png_byte)(blue & 0xff); + } + } + } +} +#endif /* MNG_FEATURES */ + +void PNGAPI +png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row) +{ png_row_info row_info; if (png_ptr == NULL) @@ -387,7 +388,7 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) /* png_read_start_row sets the information (in particular iwidth) for this * interlace pass. */ - if (!(png_ptr->flags & PNG_FLAG_ROW_INIT)) + if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) png_read_start_row(png_ptr); /* 1.5.6: row_info moved out of png_struct to a local here. */ @@ -398,45 +399,47 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) row_info.pixel_depth = png_ptr->pixel_depth; row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width); +#ifdef PNG_WARNINGS_SUPPORTED if (png_ptr->row_number == 0 && png_ptr->pass == 0) { /* Check for transforms that have been set but were defined out */ #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED) - if (png_ptr->transformations & PNG_INVERT_MONO) + if ((png_ptr->transformations & PNG_INVERT_MONO) != 0) png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED) - if (png_ptr->transformations & PNG_FILLER) + if ((png_ptr->transformations & PNG_FILLER) != 0) png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \ !defined(PNG_READ_PACKSWAP_SUPPORTED) - if (png_ptr->transformations & PNG_PACKSWAP) + if ((png_ptr->transformations & PNG_PACKSWAP) != 0) png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED) - if (png_ptr->transformations & PNG_PACK) + if ((png_ptr->transformations & PNG_PACK) != 0) png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED) - if (png_ptr->transformations & PNG_SHIFT) + if ((png_ptr->transformations & PNG_SHIFT) != 0) png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED) - if (png_ptr->transformations & PNG_BGR) + if ((png_ptr->transformations & PNG_BGR) != 0) png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED) - if (png_ptr->transformations & PNG_SWAP_BYTES) + if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0) png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined"); #endif } +#endif /* WARNINGS */ #ifdef PNG_READ_INTERLACING_SUPPORTED /* If interlaced and we do not need a new row, combine row and return. @@ -445,7 +448,8 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) * untransformed) and, because of the libpng API for interlaced images, this * means we must transform before de-interlacing. */ - if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE)) + if (png_ptr->interlaced != 0 && + (png_ptr->transformations & PNG_INTERLACE) != 0) { switch (png_ptr->pass) { @@ -502,6 +506,7 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) return; } break; + case 5: if ((png_ptr->row_number & 1) || png_ptr->width < 2) { @@ -515,7 +520,7 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) default: case 6: - if (!(png_ptr->row_number & 1)) + if ((png_ptr->row_number & 1) == 0) { png_read_finish_row(png_ptr); return; @@ -525,52 +530,11 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) } #endif - if (!(png_ptr->mode & PNG_HAVE_IDAT)) + if ((png_ptr->mode & PNG_HAVE_IDAT) == 0) png_error(png_ptr, "Invalid attempt to read row data"); - 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); - - do - { - if (!(png_ptr->zstream.avail_in)) - { - while (!png_ptr->idat_size) - { - png_crc_finish(png_ptr, 0); - - png_ptr->idat_size = png_read_chunk_header(png_ptr); - if (png_ptr->chunk_name != png_IDAT) - png_error(png_ptr, "Not enough image data"); - } - png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size; - png_ptr->zstream.next_in = png_ptr->zbuf; - if (png_ptr->zbuf_size > png_ptr->idat_size) - png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size; - png_crc_read(png_ptr, png_ptr->zbuf, - (png_size_t)png_ptr->zstream.avail_in); - png_ptr->idat_size -= png_ptr->zstream.avail_in; - } - - ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH); - - if (ret == Z_STREAM_END) - { - if (png_ptr->zstream.avail_out || png_ptr->zstream.avail_in || - png_ptr->idat_size) - png_benign_error(png_ptr, "Extra compressed data"); - png_ptr->mode |= PNG_AFTER_IDAT; - png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED; - break; - } - - if (ret != Z_OK) - png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg : - "Decompression error"); - - } while (png_ptr->zstream.avail_out); + /* Fill the row with IDAT data: */ + png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1); if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE) { @@ -586,10 +550,10 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) * it may not be in the future, so this was changed just to copy the * interlaced count: */ - png_memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1); + memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1); #ifdef PNG_MNG_FEATURES_SUPPORTED - if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) && + if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 && (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING)) { /* Intrapixel differencing */ @@ -597,7 +561,6 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) } #endif - #ifdef PNG_READ_TRANSFORMS_SUPPORTED if (png_ptr->transformations) png_do_read_transformations(png_ptr, &row_info); @@ -615,9 +578,9 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) png_error(png_ptr, "internal sequential row size calculation error"); #ifdef PNG_READ_INTERLACING_SUPPORTED - /* Blow up interlaced rows to full size */ - if (png_ptr->interlaced && - (png_ptr->transformations & PNG_INTERLACE)) + /* Expand interlaced rows to full size */ + if (png_ptr->interlaced != 0 && + (png_ptr->transformations & PNG_INTERLACE) != 0) { if (png_ptr->pass < 6) png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass, @@ -643,8 +606,9 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) if (png_ptr->read_row_fn != NULL) (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass); + } -#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ +#endif /* SEQUENTIAL_READ */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* Read one or more rows of image data. If the image is interlaced, @@ -672,7 +636,7 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row) */ void PNGAPI -png_read_rows(png_structp png_ptr, png_bytepp row, +png_read_rows(png_structrp png_ptr, png_bytepp row, png_bytepp display_row, png_uint_32 num_rows) { png_uint_32 i; @@ -711,7 +675,7 @@ png_read_rows(png_structp png_ptr, png_bytepp row, dp++; } } -#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ +#endif /* SEQUENTIAL_READ */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* Read the entire image. If the image has an alpha channel or a tRNS @@ -727,7 +691,7 @@ png_read_rows(png_structp png_ptr, png_bytepp row, * [*] png_handle_alpha() does not exist yet, as of this version of libpng */ void PNGAPI -png_read_image(png_structp png_ptr, png_bytepp image) +png_read_image(png_structrp png_ptr, png_bytepp image) { png_uint_32 i, image_height; int pass, j; @@ -739,7 +703,7 @@ png_read_image(png_structp png_ptr, png_bytepp image) return; #ifdef PNG_READ_INTERLACING_SUPPORTED - if (!(png_ptr->flags & PNG_FLAG_ROW_INIT)) + if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) { pass = png_set_interlace_handling(png_ptr); /* And make sure transforms are initialized. */ @@ -747,7 +711,8 @@ png_read_image(png_structp png_ptr, png_bytepp image) } else { - if (png_ptr->interlaced && !(png_ptr->transformations & PNG_INTERLACE)) + if (png_ptr->interlaced != 0 && + (png_ptr->transformations & PNG_INTERLACE) == 0) { /* Caller called png_start_read_image or png_read_update_info without * first turning on the PNG_INTERLACE transform. We can fix this here, @@ -784,7 +749,7 @@ png_read_image(png_structp png_ptr, png_bytepp image) } } } -#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ +#endif /* SEQUENTIAL_READ */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* Read the end of the PNG file. Will not read past the end of the @@ -792,14 +757,24 @@ png_read_image(png_structp png_ptr, png_bytepp image) * or time information at the end of the file, if info is not NULL. */ void PNGAPI -png_read_end(png_structp png_ptr, png_infop info_ptr) +png_read_end(png_structrp png_ptr, png_inforp info_ptr) { +#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED + int keep; +#endif + png_debug(1, "in png_read_end"); if (png_ptr == NULL) return; - png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */ + /* If png_read_end is called in the middle of reading the rows there may + * still be pending IDAT data and an owned zstream. Deal with this here. + */ +#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED + if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0) +#endif + png_read_finish_IDAT(png_ptr); #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED /* Report invalid palette index; added at libng-1.5.10 */ @@ -813,22 +788,28 @@ png_read_end(png_structp png_ptr, png_infop info_ptr) png_uint_32 length = png_read_chunk_header(png_ptr); png_uint_32 chunk_name = png_ptr->chunk_name; - if (chunk_name == png_IHDR) - png_handle_IHDR(png_ptr, info_ptr, length); + if (chunk_name != png_IDAT) + png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT; - else if (chunk_name == png_IEND) + if (chunk_name == png_IEND) png_handle_IEND(png_ptr, info_ptr, length); + else if (chunk_name == png_IHDR) + png_handle_IHDR(png_ptr, info_ptr, length); + + else if (info_ptr == NULL) + png_crc_finish(png_ptr, length); + #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED - else if (png_chunk_unknown_handling(png_ptr, chunk_name) != - PNG_HANDLE_CHUNK_AS_DEFAULT) + else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) { if (chunk_name == png_IDAT) { - if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT)) - png_benign_error(png_ptr, "Too many IDATs found"); + if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED)) + || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0) + png_benign_error(png_ptr, ".Too many IDATs found"); } - png_handle_unknown(png_ptr, info_ptr, length); + png_handle_unknown(png_ptr, info_ptr, length, keep); if (chunk_name == png_PLTE) png_ptr->mode |= PNG_HAVE_PLTE; } @@ -837,10 +818,14 @@ png_read_end(png_structp png_ptr, png_infop info_ptr) else if (chunk_name == png_IDAT) { /* Zero length IDATs are legal after the last IDAT has been - * read, but not after other chunks have been read. + * read, but not after other chunks have been read. 1.6 does not + * always read all the deflate data; specifically it cannot be relied + * upon to read the Adler32 at the end. If it doesn't ignore IDAT + * chunks which are longer than zero as well: */ - if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT)) - png_benign_error(png_ptr, "Too many IDATs found"); + if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED)) + || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0) + png_benign_error(png_ptr, "..Too many IDATs found"); png_crc_finish(png_ptr, length); } @@ -933,181 +918,106 @@ png_read_end(png_structp png_ptr, png_infop info_ptr) #endif else - png_handle_unknown(png_ptr, info_ptr, length); - } while (!(png_ptr->mode & PNG_HAVE_IEND)); -} -#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ - -/* Free all memory used by the read */ -void PNGAPI -png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, - png_infopp end_info_ptr_ptr) -{ - png_structp png_ptr = NULL; - png_infop info_ptr = NULL, end_info_ptr = NULL; -#ifdef PNG_USER_MEM_SUPPORTED - png_free_ptr free_fn = NULL; - png_voidp mem_ptr = NULL; -#endif - - png_debug(1, "in png_destroy_read_struct"); - - if (png_ptr_ptr != NULL) - png_ptr = *png_ptr_ptr; - if (png_ptr == NULL) - return; - -#ifdef PNG_USER_MEM_SUPPORTED - free_fn = png_ptr->free_fn; - mem_ptr = png_ptr->mem_ptr; -#endif - - if (info_ptr_ptr != NULL) - info_ptr = *info_ptr_ptr; - - if (end_info_ptr_ptr != NULL) - end_info_ptr = *end_info_ptr_ptr; - - png_read_destroy(png_ptr, info_ptr, end_info_ptr); - - if (info_ptr != NULL) - { -#ifdef PNG_TEXT_SUPPORTED - png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, -1); -#endif - -#ifdef PNG_USER_MEM_SUPPORTED - png_destroy_struct_2((png_voidp)info_ptr, (png_free_ptr)free_fn, - (png_voidp)mem_ptr); -#else - png_destroy_struct((png_voidp)info_ptr); -#endif - *info_ptr_ptr = NULL; - } - - if (end_info_ptr != NULL) - { -#ifdef PNG_READ_TEXT_SUPPORTED - png_free_data(png_ptr, end_info_ptr, PNG_FREE_TEXT, -1); -#endif -#ifdef PNG_USER_MEM_SUPPORTED - png_destroy_struct_2((png_voidp)end_info_ptr, (png_free_ptr)free_fn, - (png_voidp)mem_ptr); -#else - png_destroy_struct((png_voidp)end_info_ptr); -#endif - *end_info_ptr_ptr = NULL; - } - - if (png_ptr != NULL) - { -#ifdef PNG_USER_MEM_SUPPORTED - png_destroy_struct_2((png_voidp)png_ptr, (png_free_ptr)free_fn, - (png_voidp)mem_ptr); -#else - png_destroy_struct((png_voidp)png_ptr); -#endif - *png_ptr_ptr = NULL; - } + png_handle_unknown(png_ptr, info_ptr, length, + PNG_HANDLE_CHUNK_AS_DEFAULT); + } while ((png_ptr->mode & PNG_HAVE_IEND) == 0); } +#endif /* SEQUENTIAL_READ */ -/* Free all memory used by the read (old method) */ -void /* PRIVATE */ -png_read_destroy(png_structp png_ptr, png_infop info_ptr, - png_infop end_info_ptr) +/* Free all memory used in the read struct */ +static void +png_read_destroy(png_structrp png_ptr) { -#ifdef PNG_SETJMP_SUPPORTED - jmp_buf tmp_jmp; -#endif - png_error_ptr error_fn; -#ifdef PNG_WARNINGS_SUPPORTED - png_error_ptr warning_fn; -#endif - png_voidp error_ptr; -#ifdef PNG_USER_MEM_SUPPORTED - png_free_ptr free_fn; -#endif - png_debug(1, "in png_read_destroy"); - if (info_ptr != NULL) - png_info_destroy(png_ptr, info_ptr); - - if (end_info_ptr != NULL) - png_info_destroy(png_ptr, end_info_ptr); - #ifdef PNG_READ_GAMMA_SUPPORTED png_destroy_gamma_table(png_ptr); #endif - png_free(png_ptr, png_ptr->zbuf); png_free(png_ptr, png_ptr->big_row_buf); + png_ptr->big_row_buf = NULL; png_free(png_ptr, png_ptr->big_prev_row); - png_free(png_ptr, png_ptr->chunkdata); + png_ptr->big_prev_row = NULL; + png_free(png_ptr, png_ptr->read_buffer); + png_ptr->read_buffer = NULL; #ifdef PNG_READ_QUANTIZE_SUPPORTED png_free(png_ptr, png_ptr->palette_lookup); + png_ptr->palette_lookup = NULL; png_free(png_ptr, png_ptr->quantize_index); + png_ptr->quantize_index = NULL; #endif - if (png_ptr->free_me & PNG_FREE_PLTE) + if ((png_ptr->free_me & PNG_FREE_PLTE) != 0) + { png_zfree(png_ptr, png_ptr->palette); + png_ptr->palette = NULL; + } png_ptr->free_me &= ~PNG_FREE_PLTE; #if defined(PNG_tRNS_SUPPORTED) || \ defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) - if (png_ptr->free_me & PNG_FREE_TRNS) + if ((png_ptr->free_me & PNG_FREE_TRNS) != 0) + { png_free(png_ptr, png_ptr->trans_alpha); + png_ptr->trans_alpha = NULL; + } png_ptr->free_me &= ~PNG_FREE_TRNS; #endif -#ifdef PNG_READ_hIST_SUPPORTED - if (png_ptr->free_me & PNG_FREE_HIST) - png_free(png_ptr, png_ptr->hist); - png_ptr->free_me &= ~PNG_FREE_HIST; -#endif - inflateEnd(&png_ptr->zstream); #ifdef PNG_PROGRESSIVE_READ_SUPPORTED png_free(png_ptr, png_ptr->save_buffer); + png_ptr->save_buffer = NULL; #endif - /* Save the important info out of the png_struct, in case it is - * being used again. - */ -#ifdef PNG_SETJMP_SUPPORTED - png_memcpy(tmp_jmp, png_ptr->longjmp_buffer, png_sizeof(jmp_buf)); +#if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \ + defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) + png_free(png_ptr, png_ptr->unknown_chunk.data); + png_ptr->unknown_chunk.data = NULL; #endif - error_fn = png_ptr->error_fn; -#ifdef PNG_WARNINGS_SUPPORTED - warning_fn = png_ptr->warning_fn; -#endif - error_ptr = png_ptr->error_ptr; -#ifdef PNG_USER_MEM_SUPPORTED - free_fn = png_ptr->free_fn; +#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED + png_free(png_ptr, png_ptr->chunk_list); + png_ptr->chunk_list = NULL; #endif - png_memset(png_ptr, 0, png_sizeof(png_struct)); + /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error + * callbacks are still set at this point. They are required to complete the + * destruction of the png_struct itself. + */ +} - png_ptr->error_fn = error_fn; -#ifdef PNG_WARNINGS_SUPPORTED - png_ptr->warning_fn = warning_fn; -#endif - png_ptr->error_ptr = error_ptr; -#ifdef PNG_USER_MEM_SUPPORTED - png_ptr->free_fn = free_fn; -#endif +/* Free all memory used by the read */ +void PNGAPI +png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, + png_infopp end_info_ptr_ptr) +{ + png_structrp png_ptr = NULL; -#ifdef PNG_SETJMP_SUPPORTED - png_memcpy(png_ptr->longjmp_buffer, tmp_jmp, png_sizeof(jmp_buf)); -#endif + png_debug(1, "in png_destroy_read_struct"); + + if (png_ptr_ptr != NULL) + png_ptr = *png_ptr_ptr; + + if (png_ptr == NULL) + return; + /* libpng 1.6.0: use the API to destroy info structs to ensure consistent + * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API. + * The extra was, apparently, unnecessary yet this hides memory leak bugs. + */ + png_destroy_info_struct(png_ptr, end_info_ptr_ptr); + png_destroy_info_struct(png_ptr, info_ptr_ptr); + + *png_ptr_ptr = NULL; + png_read_destroy(png_ptr); + png_destroy_png_struct(png_ptr); } void PNGAPI -png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn) +png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn) { if (png_ptr == NULL) return; @@ -1119,11 +1029,10 @@ png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn) #ifdef PNG_SEQUENTIAL_READ_SUPPORTED #ifdef PNG_INFO_IMAGE_SUPPORTED void PNGAPI -png_read_png(png_structp png_ptr, png_infop info_ptr, int transforms, - voidp params) +png_read_png(png_structrp png_ptr, png_inforp info_ptr, + int transforms, + voidp params) { - int row; - if (png_ptr == NULL || info_ptr == NULL) return; @@ -1131,124 +1040,153 @@ png_read_png(png_structp png_ptr, png_infop info_ptr, int transforms, * PNG file before the first IDAT (image data chunk). */ png_read_info(png_ptr, info_ptr); - if (info_ptr->height > PNG_UINT_32_MAX/png_sizeof(png_bytep)) + if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep))) png_error(png_ptr, "Image is too high to process with png_read_png()"); /* -------------- image transformations start here ------------------- */ + /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM + * is not implemented. This will only happen in de-configured (non-default) + * libpng builds. The results can be unexpected - png_read_png may return + * short or mal-formed rows because the transform is skipped. + */ -#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED /* Tell libpng to strip 16-bit/color files down to 8 bits per color. */ - if (transforms & PNG_TRANSFORM_SCALE_16) - { - /* Added at libpng-1.5.4. "strip_16" produces the same result that it - * did in earlier versions, while "scale_16" is now more accurate. - */ + if ((transforms & PNG_TRANSFORM_SCALE_16) != 0) + /* Added at libpng-1.5.4. "strip_16" produces the same result that it + * did in earlier versions, while "scale_16" is now more accurate. + */ +#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED png_set_scale_16(png_ptr); - } +#else + png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported"); #endif -#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED /* If both SCALE and STRIP are required pngrtran will effectively cancel the * latter by doing SCALE first. This is ok and allows apps not to check for * which is supported to get the right answer. */ - if (transforms & PNG_TRANSFORM_STRIP_16) + if ((transforms & PNG_TRANSFORM_STRIP_16) != 0) +#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED png_set_strip_16(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported"); #endif -#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED /* Strip alpha bytes from the input data without combining with * the background (not recommended). */ - if (transforms & PNG_TRANSFORM_STRIP_ALPHA) + if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0) +#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED png_set_strip_alpha(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported"); #endif -#if defined(PNG_READ_PACK_SUPPORTED) && !defined(PNG_READ_EXPAND_SUPPORTED) /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single * byte into separate bytes (useful for paletted and grayscale images). */ - if (transforms & PNG_TRANSFORM_PACKING) + if ((transforms & PNG_TRANSFORM_PACKING) != 0) +#ifdef PNG_READ_PACK_SUPPORTED png_set_packing(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported"); #endif -#ifdef PNG_READ_PACKSWAP_SUPPORTED /* Change the order of packed pixels to least significant bit first * (not useful if you are using png_set_packing). */ - if (transforms & PNG_TRANSFORM_PACKSWAP) + if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0) +#ifdef PNG_READ_PACKSWAP_SUPPORTED png_set_packswap(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported"); #endif -#ifdef PNG_READ_EXPAND_SUPPORTED /* Expand paletted colors into true RGB triplets * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel * Expand paletted or RGB images with transparency to full alpha * channels so the data will be available as RGBA quartets. */ - if (transforms & PNG_TRANSFORM_EXPAND) - if ((png_ptr->bit_depth < 8) || - (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) || - (info_ptr->valid & PNG_INFO_tRNS)) - png_set_expand(png_ptr); + if ((transforms & PNG_TRANSFORM_EXPAND) != 0) +#ifdef PNG_READ_EXPAND_SUPPORTED + png_set_expand(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported"); #endif /* We don't handle background color or gamma transformation or quantizing. */ -#ifdef PNG_READ_INVERT_SUPPORTED /* Invert monochrome files to have 0 as white and 1 as black */ - if (transforms & PNG_TRANSFORM_INVERT_MONO) + if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0) +#ifdef PNG_READ_INVERT_SUPPORTED png_set_invert_mono(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported"); #endif -#ifdef PNG_READ_SHIFT_SUPPORTED /* If you want to shift the pixel values from the range [0,255] or * [0,65535] to the original [0,7] or [0,31], or whatever range the * colors were originally in: */ - if ((transforms & PNG_TRANSFORM_SHIFT) && (info_ptr->valid & PNG_INFO_sBIT)) - png_set_shift(png_ptr, &info_ptr->sig_bit); + if ((transforms & PNG_TRANSFORM_SHIFT) != 0) +#ifdef PNG_READ_SHIFT_SUPPORTED + if ((info_ptr->valid & PNG_INFO_sBIT) != 0) + png_set_shift(png_ptr, &info_ptr->sig_bit); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported"); #endif -#ifdef PNG_READ_BGR_SUPPORTED /* Flip the RGB pixels to BGR (or RGBA to BGRA) */ - if (transforms & PNG_TRANSFORM_BGR) + if ((transforms & PNG_TRANSFORM_BGR) != 0) +#ifdef PNG_READ_BGR_SUPPORTED png_set_bgr(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported"); #endif -#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */ - if (transforms & PNG_TRANSFORM_SWAP_ALPHA) + if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0) +#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED png_set_swap_alpha(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported"); #endif -#ifdef PNG_READ_SWAP_SUPPORTED /* Swap bytes of 16-bit files to least significant byte first */ - if (transforms & PNG_TRANSFORM_SWAP_ENDIAN) + if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0) +#ifdef PNG_READ_SWAP_SUPPORTED png_set_swap(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported"); #endif /* Added at libpng-1.2.41 */ -#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED /* Invert the alpha channel from opacity to transparency */ - if (transforms & PNG_TRANSFORM_INVERT_ALPHA) + if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0) +#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED png_set_invert_alpha(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported"); #endif /* Added at libpng-1.2.41 */ -#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED /* Expand grayscale image to RGB */ - if (transforms & PNG_TRANSFORM_GRAY_TO_RGB) + if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0) +#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED png_set_gray_to_rgb(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported"); #endif /* Added at libpng-1.5.4 */ + if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0) #ifdef PNG_READ_EXPAND_16_SUPPORTED - if (transforms & PNG_TRANSFORM_EXPAND_16) png_set_expand_16(png_ptr); +#else + png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported"); #endif /* We don't handle adding filler bytes */ @@ -1271,16 +1209,17 @@ png_read_png(png_structp png_ptr, png_infop info_ptr, int transforms, { png_uint_32 iptr; - info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr, - info_ptr->height * png_sizeof(png_bytep)); + info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr, + info_ptr->height * (sizeof (png_bytep)))); + for (iptr=0; iptr<info_ptr->height; iptr++) info_ptr->row_pointers[iptr] = NULL; info_ptr->free_me |= PNG_FREE_ROWS; - for (row = 0; row < (int)info_ptr->height; row++) - info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr, - png_get_rowbytes(png_ptr, info_ptr)); + for (iptr = 0; iptr < info_ptr->height; iptr++) + info_ptr->row_pointers[iptr] = png_voidcast(png_bytep, + png_malloc(png_ptr, info_ptr->rowbytes)); } png_read_image(png_ptr, info_ptr->row_pointers); @@ -1289,10 +1228,2945 @@ png_read_png(png_structp png_ptr, png_infop info_ptr, int transforms, /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */ png_read_end(png_ptr, info_ptr); - PNG_UNUSED(transforms) /* Quiet compiler warnings */ PNG_UNUSED(params) +} +#endif /* INFO_IMAGE */ +#endif /* SEQUENTIAL_READ */ + +#ifdef PNG_SIMPLIFIED_READ_SUPPORTED +/* SIMPLIFIED READ + * + * This code currently relies on the sequential reader, though it could easily + * be made to work with the progressive one. + */ +/* Arguments to png_image_finish_read: */ + +/* Encoding of PNG data (used by the color-map code) */ +# define P_NOTSET 0 /* File encoding not yet known */ +# define P_sRGB 1 /* 8-bit encoded to sRGB gamma */ +# define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */ +# define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */ +# define P_LINEAR8 4 /* 8-bit linear: only from a file value */ + +/* Color-map processing: after libpng has run on the PNG image further + * processing may be needed to convert the data to color-map indices. + */ +#define PNG_CMAP_NONE 0 +#define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */ +#define PNG_CMAP_TRANS 2 /* Process GA data to a background index */ +#define PNG_CMAP_RGB 3 /* Process RGB data */ +#define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */ + +/* The following document where the background is for each processing case. */ +#define PNG_CMAP_NONE_BACKGROUND 256 +#define PNG_CMAP_GA_BACKGROUND 231 +#define PNG_CMAP_TRANS_BACKGROUND 254 +#define PNG_CMAP_RGB_BACKGROUND 256 +#define PNG_CMAP_RGB_ALPHA_BACKGROUND 216 + +typedef struct +{ + /* Arguments: */ + png_imagep image; + png_voidp buffer; + png_int_32 row_stride; + png_voidp colormap; + png_const_colorp background; + /* Local variables: */ + png_voidp local_row; + png_voidp first_row; + ptrdiff_t row_bytes; /* step between rows */ + int file_encoding; /* E_ values above */ + png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */ + int colormap_processing; /* PNG_CMAP_ values above */ +} png_image_read_control; + +/* Do all the *safe* initialization - 'safe' means that png_error won't be + * called, so setting up the jmp_buf is not required. This means that anything + * called from here must *not* call png_malloc - it has to call png_malloc_warn + * instead so that control is returned safely back to this routine. + */ +static int +png_image_read_init(png_imagep image) +{ + if (image->opaque == NULL) + { + png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image, + png_safe_error, png_safe_warning); + + /* And set the rest of the structure to NULL to ensure that the various + * fields are consistent. + */ + memset(image, 0, (sizeof *image)); + image->version = PNG_IMAGE_VERSION; + + if (png_ptr != NULL) + { + png_infop info_ptr = png_create_info_struct(png_ptr); + + if (info_ptr != NULL) + { + png_controlp control = png_voidcast(png_controlp, + png_malloc_warn(png_ptr, (sizeof *control))); + + if (control != NULL) + { + memset(control, 0, (sizeof *control)); + + control->png_ptr = png_ptr; + control->info_ptr = info_ptr; + control->for_write = 0; + + image->opaque = control; + return 1; + } + + /* Error clean up */ + png_destroy_info_struct(png_ptr, &info_ptr); + } + + png_destroy_read_struct(&png_ptr, NULL, NULL); + } + + return png_image_error(image, "png_image_read: out of memory"); + } + + return png_image_error(image, "png_image_read: opaque pointer not NULL"); +} + +/* Utility to find the base format of a PNG file from a png_struct. */ +static png_uint_32 +png_image_format(png_structrp png_ptr) +{ + png_uint_32 format = 0; + + if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) + format |= PNG_FORMAT_FLAG_COLOR; + + if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) + format |= PNG_FORMAT_FLAG_ALPHA; + + /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS + * sets the png_struct fields; that's all we are interested in here. The + * precise interaction with an app call to png_set_tRNS and PNG file reading + * is unclear. + */ + else if (png_ptr->num_trans > 0) + format |= PNG_FORMAT_FLAG_ALPHA; + + if (png_ptr->bit_depth == 16) + format |= PNG_FORMAT_FLAG_LINEAR; + + if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0) + format |= PNG_FORMAT_FLAG_COLORMAP; + + return format; +} + +/* Is the given gamma significantly different from sRGB? The test is the same + * one used in pngrtran.c when deciding whether to do gamma correction. The + * arithmetic optimizes the division by using the fact that the inverse of the + * file sRGB gamma is 2.2 + */ +static int +png_gamma_not_sRGB(png_fixed_point g) +{ + if (g < PNG_FP_1) + { + /* An uninitialized gamma is assumed to be sRGB for the simplified API. */ + if (g == 0) + return 0; + + return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */); + } + + return 1; +} + +/* Do the main body of a 'png_image_begin_read' function; read the PNG file + * header and fill in all the information. This is executed in a safe context, + * unlike the init routine above. + */ +static int +png_image_read_header(png_voidp argument) +{ + png_imagep image = png_voidcast(png_imagep, argument); + png_structrp png_ptr = image->opaque->png_ptr; + png_inforp info_ptr = image->opaque->info_ptr; + + png_set_benign_errors(png_ptr, 1/*warn*/); + png_read_info(png_ptr, info_ptr); + + /* Do this the fast way; just read directly out of png_struct. */ + image->width = png_ptr->width; + image->height = png_ptr->height; + + { + png_uint_32 format = png_image_format(png_ptr); + + image->format = format; + +#ifdef PNG_COLORSPACE_SUPPORTED + /* Does the colorspace match sRGB? If there is no color endpoint + * (colorant) information assume yes, otherwise require the + * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the + * colorspace has been determined to be invalid ignore it. + */ + if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags + & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB| + PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS)) + image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB; +#endif + } + + /* We need the maximum number of entries regardless of the format the + * application sets here. + */ + { + png_uint_32 cmap_entries; + + switch (png_ptr->color_type) + { + case PNG_COLOR_TYPE_GRAY: + cmap_entries = 1U << png_ptr->bit_depth; + break; + + case PNG_COLOR_TYPE_PALETTE: + cmap_entries = png_ptr->num_palette; + break; + + default: + cmap_entries = 256; + break; + } + + if (cmap_entries > 256) + cmap_entries = 256; + + image->colormap_entries = cmap_entries; + } + + return 1; +} + +#ifdef PNG_STDIO_SUPPORTED +int PNGAPI +png_image_begin_read_from_stdio(png_imagep image, FILE* file) +{ + if (image != NULL && image->version == PNG_IMAGE_VERSION) + { + if (file != NULL) + { + if (png_image_read_init(image) != 0) + { + /* This is slightly evil, but png_init_io doesn't do anything other + * than this and we haven't changed the standard IO functions so + * this saves a 'safe' function. + */ + image->opaque->png_ptr->io_ptr = file; + return png_safe_execute(image, png_image_read_header, image); + } + } + + else + return png_image_error(image, + "png_image_begin_read_from_stdio: invalid argument"); + } + + else if (image != NULL) + return png_image_error(image, + "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION"); + + return 0; +} + +int PNGAPI +png_image_begin_read_from_file(png_imagep image, const char *file_name) +{ + if (image != NULL && image->version == PNG_IMAGE_VERSION) + { + if (file_name != NULL) + { + FILE *fp = fopen(file_name, "rb"); + + if (fp != NULL) + { + if (png_image_read_init(image) != 0) + { + image->opaque->png_ptr->io_ptr = fp; + image->opaque->owned_file = 1; + return png_safe_execute(image, png_image_read_header, image); + } + + /* Clean up: just the opened file. */ + (void)fclose(fp); + } + + else + return png_image_error(image, strerror(errno)); + } + + else + return png_image_error(image, + "png_image_begin_read_from_file: invalid argument"); + } + else if (image != NULL) + return png_image_error(image, + "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION"); + + return 0; +} +#endif /* STDIO */ + +static void PNGCBAPI +png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need) +{ + if (png_ptr != NULL) + { + png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr); + if (image != NULL) + { + png_controlp cp = image->opaque; + if (cp != NULL) + { + png_const_bytep memory = cp->memory; + png_size_t size = cp->size; + + if (memory != NULL && size >= need) + { + memcpy(out, memory, need); + cp->memory = memory + need; + cp->size = size - need; + return; + } + + png_error(png_ptr, "read beyond end of data"); + } + } + + png_error(png_ptr, "invalid memory read"); + } +} + +int PNGAPI png_image_begin_read_from_memory(png_imagep image, + png_const_voidp memory, png_size_t size) +{ + if (image != NULL && image->version == PNG_IMAGE_VERSION) + { + if (memory != NULL && size > 0) + { + if (png_image_read_init(image) != 0) + { + /* Now set the IO functions to read from the memory buffer and + * store it into io_ptr. Again do this in-place to avoid calling a + * libpng function that requires error handling. + */ + image->opaque->memory = png_voidcast(png_const_bytep, memory); + image->opaque->size = size; + image->opaque->png_ptr->io_ptr = image; + image->opaque->png_ptr->read_data_fn = png_image_memory_read; + + return png_safe_execute(image, png_image_read_header, image); + } + } + + else + return png_image_error(image, + "png_image_begin_read_from_memory: invalid argument"); + } + + else if (image != NULL) + return png_image_error(image, + "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION"); + + return 0; } -#endif /* PNG_INFO_IMAGE_SUPPORTED */ -#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */ -#endif /* PNG_READ_SUPPORTED */ + +/* Utility function to skip chunks that are not used by the simplified image + * read functions and an appropriate macro to call it. + */ +#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED +static void +png_image_skip_unused_chunks(png_structrp png_ptr) +{ + /* Prepare the reader to ignore all recognized chunks whose data will not + * be used, i.e., all chunks recognized by libpng except for those + * involved in basic image reading: + * + * IHDR, PLTE, IDAT, IEND + * + * Or image data handling: + * + * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT. + * + * This provides a small performance improvement and eliminates any + * potential vulnerability to security problems in the unused chunks. + * + * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored + * too. This allows the simplified API to be compiled without iCCP support, + * however if the support is there the chunk is still checked to detect + * errors (which are unfortunately quite common.) + */ + { + static PNG_CONST png_byte chunks_to_process[] = { + 98, 75, 71, 68, '\0', /* bKGD */ + 99, 72, 82, 77, '\0', /* cHRM */ + 103, 65, 77, 65, '\0', /* gAMA */ +# ifdef PNG_READ_iCCP_SUPPORTED + 105, 67, 67, 80, '\0', /* iCCP */ +# endif + 115, 66, 73, 84, '\0', /* sBIT */ + 115, 82, 71, 66, '\0', /* sRGB */ + }; + + /* Ignore unknown chunks and all other chunks except for the + * IHDR, PLTE, tRNS, IDAT, and IEND chunks. + */ + png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER, + NULL, -1); + + /* But do not ignore image data handling chunks */ + png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT, + chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5); + } +} + +# define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p) +#else +# define PNG_SKIP_CHUNKS(p) ((void)0) +#endif /* HANDLE_AS_UNKNOWN */ + +/* The following macro gives the exact rounded answer for all values in the + * range 0..255 (it actually divides by 51.2, but the rounding still generates + * the correct numbers 0..5 + */ +#define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8) + +/* Utility functions to make particular color-maps */ +static void +set_file_encoding(png_image_read_control *display) +{ + png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma; + if (png_gamma_significant(g) != 0) + { + if (png_gamma_not_sRGB(g) != 0) + { + display->file_encoding = P_FILE; + display->gamma_to_linear = png_reciprocal(g); + } + + else + display->file_encoding = P_sRGB; + } + + else + display->file_encoding = P_LINEAR8; +} + +static unsigned int +decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding) +{ + if (encoding == P_FILE) /* double check */ + encoding = display->file_encoding; + + if (encoding == P_NOTSET) /* must be the file encoding */ + { + set_file_encoding(display); + encoding = display->file_encoding; + } + + switch (encoding) + { + case P_FILE: + value = png_gamma_16bit_correct(value*257, display->gamma_to_linear); + break; + + case P_sRGB: + value = png_sRGB_table[value]; + break; + + case P_LINEAR: + break; + + case P_LINEAR8: + value *= 257; + break; + +#ifdef __GNUC__ + default: + png_error(display->image->opaque->png_ptr, + "unexpected encoding (internal error)"); +#endif + } + + return value; +} + +static png_uint_32 +png_colormap_compose(png_image_read_control *display, + png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha, + png_uint_32 background, int encoding) +{ + /* The file value is composed on the background, the background has the given + * encoding and so does the result, the file is encoded with P_FILE and the + * file and alpha are 8-bit values. The (output) encoding will always be + * P_LINEAR or P_sRGB. + */ + png_uint_32 f = decode_gamma(display, foreground, foreground_encoding); + png_uint_32 b = decode_gamma(display, background, encoding); + + /* The alpha is always an 8-bit value (it comes from the palette), the value + * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires. + */ + f = f * alpha + b * (255-alpha); + + if (encoding == P_LINEAR) + { + /* Scale to 65535; divide by 255, approximately (in fact this is extremely + * accurate, it divides by 255.00000005937181414556, with no overflow.) + */ + f *= 257; /* Now scaled by 65535 */ + f += f >> 16; + f = (f+32768) >> 16; + } + + else /* P_sRGB */ + f = PNG_sRGB_FROM_LINEAR(f); + + return f; +} + +/* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must + * be 8-bit. + */ +static void +png_create_colormap_entry(png_image_read_control *display, + png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue, + png_uint_32 alpha, int encoding) +{ + png_imagep image = display->image; + const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ? + P_LINEAR : P_sRGB; + const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 && + (red != green || green != blue); + + if (ip > 255) + png_error(image->opaque->png_ptr, "color-map index out of range"); + + /* Update the cache with whether the file gamma is significantly different + * from sRGB. + */ + if (encoding == P_FILE) + { + if (display->file_encoding == P_NOTSET) + set_file_encoding(display); + + /* Note that the cached value may be P_FILE too, but if it is then the + * gamma_to_linear member has been set. + */ + encoding = display->file_encoding; + } + + if (encoding == P_FILE) + { + png_fixed_point g = display->gamma_to_linear; + + red = png_gamma_16bit_correct(red*257, g); + green = png_gamma_16bit_correct(green*257, g); + blue = png_gamma_16bit_correct(blue*257, g); + + if (convert_to_Y != 0 || output_encoding == P_LINEAR) + { + alpha *= 257; + encoding = P_LINEAR; + } + + else + { + red = PNG_sRGB_FROM_LINEAR(red * 255); + green = PNG_sRGB_FROM_LINEAR(green * 255); + blue = PNG_sRGB_FROM_LINEAR(blue * 255); + encoding = P_sRGB; + } + } + + else if (encoding == P_LINEAR8) + { + /* This encoding occurs quite frequently in test cases because PngSuite + * includes a gAMA 1.0 chunk with most images. + */ + red *= 257; + green *= 257; + blue *= 257; + alpha *= 257; + encoding = P_LINEAR; + } + + else if (encoding == P_sRGB && + (convert_to_Y != 0 || output_encoding == P_LINEAR)) + { + /* The values are 8-bit sRGB values, but must be converted to 16-bit + * linear. + */ + red = png_sRGB_table[red]; + green = png_sRGB_table[green]; + blue = png_sRGB_table[blue]; + alpha *= 257; + encoding = P_LINEAR; + } + + /* This is set if the color isn't gray but the output is. */ + if (encoding == P_LINEAR) + { + if (convert_to_Y != 0) + { + /* NOTE: these values are copied from png_do_rgb_to_gray */ + png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green + + (png_uint_32)2366 * blue; + + if (output_encoding == P_LINEAR) + y = (y + 16384) >> 15; + + else + { + /* y is scaled by 32768, we need it scaled by 255: */ + y = (y + 128) >> 8; + y *= 255; + y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7); + alpha = PNG_DIV257(alpha); + encoding = P_sRGB; + } + + blue = red = green = y; + } + + else if (output_encoding == P_sRGB) + { + red = PNG_sRGB_FROM_LINEAR(red * 255); + green = PNG_sRGB_FROM_LINEAR(green * 255); + blue = PNG_sRGB_FROM_LINEAR(blue * 255); + alpha = PNG_DIV257(alpha); + encoding = P_sRGB; + } + } + + if (encoding != output_encoding) + png_error(image->opaque->png_ptr, "bad encoding (internal error)"); + + /* Store the value. */ + { +# ifdef PNG_FORMAT_AFIRST_SUPPORTED + const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 && + (image->format & PNG_FORMAT_FLAG_ALPHA) != 0; +# else +# define afirst 0 +# endif +# ifdef PNG_FORMAT_BGR_SUPPORTED + const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0; +# else +# define bgr 0 +# endif + + if (output_encoding == P_LINEAR) + { + png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap); + + entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); + + /* The linear 16-bit values must be pre-multiplied by the alpha channel + * value, if less than 65535 (this is, effectively, composite on black + * if the alpha channel is removed.) + */ + switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) + { + case 4: + entry[afirst ? 0 : 3] = (png_uint_16)alpha; + /* FALL THROUGH */ + + case 3: + if (alpha < 65535) + { + if (alpha > 0) + { + blue = (blue * alpha + 32767U)/65535U; + green = (green * alpha + 32767U)/65535U; + red = (red * alpha + 32767U)/65535U; + } + + else + red = green = blue = 0; + } + entry[afirst + (2 ^ bgr)] = (png_uint_16)blue; + entry[afirst + 1] = (png_uint_16)green; + entry[afirst + bgr] = (png_uint_16)red; + break; + + case 2: + entry[1 ^ afirst] = (png_uint_16)alpha; + /* FALL THROUGH */ + + case 1: + if (alpha < 65535) + { + if (alpha > 0) + green = (green * alpha + 32767U)/65535U; + + else + green = 0; + } + entry[afirst] = (png_uint_16)green; + break; + + default: + break; + } + } + + else /* output encoding is P_sRGB */ + { + png_bytep entry = png_voidcast(png_bytep, display->colormap); + + entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); + + switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) + { + case 4: + entry[afirst ? 0 : 3] = (png_byte)alpha; + case 3: + entry[afirst + (2 ^ bgr)] = (png_byte)blue; + entry[afirst + 1] = (png_byte)green; + entry[afirst + bgr] = (png_byte)red; + break; + + case 2: + entry[1 ^ afirst] = (png_byte)alpha; + case 1: + entry[afirst] = (png_byte)green; + break; + + default: + break; + } + } + +# ifdef afirst +# undef afirst +# endif +# ifdef bgr +# undef bgr +# endif + } +} + +static int +make_gray_file_colormap(png_image_read_control *display) +{ + unsigned int i; + + for (i=0; i<256; ++i) + png_create_colormap_entry(display, i, i, i, i, 255, P_FILE); + + return i; +} + +static int +make_gray_colormap(png_image_read_control *display) +{ + unsigned int i; + + for (i=0; i<256; ++i) + png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB); + + return i; +} +#define PNG_GRAY_COLORMAP_ENTRIES 256 + +static int +make_ga_colormap(png_image_read_control *display) +{ + unsigned int i, a; + + /* Alpha is retained, the output will be a color-map with entries + * selected by six levels of alpha. One transparent entry, 6 gray + * levels for all the intermediate alpha values, leaving 230 entries + * for the opaque grays. The color-map entries are the six values + * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the + * relevant entry. + * + * if (alpha > 229) // opaque + * { + * // The 231 entries are selected to make the math below work: + * base = 0; + * entry = (231 * gray + 128) >> 8; + * } + * else if (alpha < 26) // transparent + * { + * base = 231; + * entry = 0; + * } + * else // partially opaque + * { + * base = 226 + 6 * PNG_DIV51(alpha); + * entry = PNG_DIV51(gray); + * } + */ + i = 0; + while (i < 231) + { + unsigned int gray = (i * 256 + 115) / 231; + png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB); + } + + /* 255 is used here for the component values for consistency with the code + * that undoes premultiplication in pngwrite.c. + */ + png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB); + + for (a=1; a<5; ++a) + { + unsigned int g; + + for (g=0; g<6; ++g) + png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51, + P_sRGB); + } + + return i; +} + +#define PNG_GA_COLORMAP_ENTRIES 256 + +static int +make_rgb_colormap(png_image_read_control *display) +{ + unsigned int i, r; + + /* Build a 6x6x6 opaque RGB cube */ + for (i=r=0; r<6; ++r) + { + unsigned int g; + + for (g=0; g<6; ++g) + { + unsigned int b; + + for (b=0; b<6; ++b) + png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255, + P_sRGB); + } + } + + return i; +} + +#define PNG_RGB_COLORMAP_ENTRIES 216 + +/* Return a palette index to the above palette given three 8-bit sRGB values. */ +#define PNG_RGB_INDEX(r,g,b) \ + ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b))) + +static int +png_image_read_colormap(png_voidp argument) +{ + png_image_read_control *display = + png_voidcast(png_image_read_control*, argument); + const png_imagep image = display->image; + + const png_structrp png_ptr = image->opaque->png_ptr; + const png_uint_32 output_format = image->format; + const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ? + P_LINEAR : P_sRGB; + + unsigned int cmap_entries; + unsigned int output_processing; /* Output processing option */ + unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */ + + /* Background information; the background color and the index of this color + * in the color-map if it exists (else 256). + */ + unsigned int background_index = 256; + png_uint_32 back_r, back_g, back_b; + + /* Flags to accumulate things that need to be done to the input. */ + int expand_tRNS = 0; + + /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is + * very difficult to do, the results look awful, and it is difficult to see + * what possible use it is because the application can't control the + * color-map. + */ + if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 || + png_ptr->num_trans > 0) /* alpha in input */ && + ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */) + { + if (output_encoding == P_LINEAR) /* compose on black */ + back_b = back_g = back_r = 0; + + else if (display->background == NULL /* no way to remove it */) + png_error(png_ptr, + "a background color must be supplied to remove alpha/transparency"); + + /* Get a copy of the background color (this avoids repeating the checks + * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the + * output format. + */ + else + { + back_g = display->background->green; + if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0) + { + back_r = display->background->red; + back_b = display->background->blue; + } + else + back_b = back_r = back_g; + } + } + + else if (output_encoding == P_LINEAR) + back_b = back_r = back_g = 65535; + + else + back_b = back_r = back_g = 255; + + /* Default the input file gamma if required - this is necessary because + * libpng assumes that if no gamma information is present the data is in the + * output format, but the simplified API deduces the gamma from the input + * format. + */ + if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0) + { + /* Do this directly, not using the png_colorspace functions, to ensure + * that it happens even if the colorspace is invalid (though probably if + * it is the setting will be ignored) Note that the same thing can be + * achieved at the application interface with png_set_gAMA. + */ + if (png_ptr->bit_depth == 16 && + (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) + png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR; + + else + png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE; + + png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; + } + + /* Decide what to do based on the PNG color type of the input data. The + * utility function png_create_colormap_entry deals with most aspects of the + * output transformations; this code works out how to produce bytes of + * color-map entries from the original format. + */ + switch (png_ptr->color_type) + { + case PNG_COLOR_TYPE_GRAY: + if (png_ptr->bit_depth <= 8) + { + /* There at most 256 colors in the output, regardless of + * transparency. + */ + unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0; + + cmap_entries = 1U << png_ptr->bit_depth; + if (cmap_entries > image->colormap_entries) + png_error(png_ptr, "gray[8] color-map: too few entries"); + + step = 255 / (cmap_entries - 1); + output_processing = PNG_CMAP_NONE; + + /* If there is a tRNS chunk then this either selects a transparent + * value or, if the output has no alpha, the background color. + */ + if (png_ptr->num_trans > 0) + { + trans = png_ptr->trans_color.gray; + + if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) + back_alpha = output_encoding == P_LINEAR ? 65535 : 255; + } + + /* png_create_colormap_entry just takes an RGBA and writes the + * corresponding color-map entry using the format from 'image', + * including the required conversion to sRGB or linear as + * appropriate. The input values are always either sRGB (if the + * gamma correction flag is 0) or 0..255 scaled file encoded values + * (if the function must gamma correct them). + */ + for (i=val=0; i<cmap_entries; ++i, val += step) + { + /* 'i' is a file value. While this will result in duplicated + * entries for 8-bit non-sRGB encoded files it is necessary to + * have non-gamma corrected values to do tRNS handling. + */ + if (i != trans) + png_create_colormap_entry(display, i, val, val, val, 255, + P_FILE/*8-bit with file gamma*/); + + /* Else this entry is transparent. The colors don't matter if + * there is an alpha channel (back_alpha == 0), but it does no + * harm to pass them in; the values are not set above so this + * passes in white. + * + * NOTE: this preserves the full precision of the application + * supplied background color when it is used. + */ + else + png_create_colormap_entry(display, i, back_r, back_g, back_b, + back_alpha, output_encoding); + } + + /* We need libpng to preserve the original encoding. */ + data_encoding = P_FILE; + + /* The rows from libpng, while technically gray values, are now also + * color-map indices; however, they may need to be expanded to 1 + * byte per pixel. This is what png_set_packing does (i.e., it + * unpacks the bit values into bytes.) + */ + if (png_ptr->bit_depth < 8) + png_set_packing(png_ptr); + } + + else /* bit depth is 16 */ + { + /* The 16-bit input values can be converted directly to 8-bit gamma + * encoded values; however, if a tRNS chunk is present 257 color-map + * entries are required. This means that the extra entry requires + * special processing; add an alpha channel, sacrifice gray level + * 254 and convert transparent (alpha==0) entries to that. + * + * Use libpng to chop the data to 8 bits. Convert it to sRGB at the + * same time to minimize quality loss. If a tRNS chunk is present + * this means libpng must handle it too; otherwise it is impossible + * to do the exact match on the 16-bit value. + * + * If the output has no alpha channel *and* the background color is + * gray then it is possible to let libpng handle the substitution by + * ensuring that the corresponding gray level matches the background + * color exactly. + */ + data_encoding = P_sRGB; + + if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) + png_error(png_ptr, "gray[16] color-map: too few entries"); + + cmap_entries = make_gray_colormap(display); + + if (png_ptr->num_trans > 0) + { + unsigned int back_alpha; + + if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) + back_alpha = 0; + + else + { + if (back_r == back_g && back_g == back_b) + { + /* Background is gray; no special processing will be + * required. + */ + png_color_16 c; + png_uint_32 gray = back_g; + + if (output_encoding == P_LINEAR) + { + gray = PNG_sRGB_FROM_LINEAR(gray * 255); + + /* And make sure the corresponding palette entry + * matches. + */ + png_create_colormap_entry(display, gray, back_g, back_g, + back_g, 65535, P_LINEAR); + } + + /* The background passed to libpng, however, must be the + * sRGB value. + */ + c.index = 0; /*unused*/ + c.gray = c.red = c.green = c.blue = (png_uint_16)gray; + + /* NOTE: does this work without expanding tRNS to alpha? + * It should be the color->gray case below apparently + * doesn't. + */ + png_set_background_fixed(png_ptr, &c, + PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, + 0/*gamma: not used*/); + + output_processing = PNG_CMAP_NONE; + break; + } +#ifdef __COVERITY__ + /* Coverity claims that output_encoding cannot be 2 (P_LINEAR) + * here. + */ + back_alpha = 255; +#else + back_alpha = output_encoding == P_LINEAR ? 65535 : 255; +#endif + } + + /* output_processing means that the libpng-processed row will be + * 8-bit GA and it has to be processing to single byte color-map + * values. Entry 254 is replaced by either a completely + * transparent entry or by the background color at full + * precision (and the background color is not a simple gray + * level in this case.) + */ + expand_tRNS = 1; + output_processing = PNG_CMAP_TRANS; + background_index = 254; + + /* And set (overwrite) color-map entry 254 to the actual + * background color at full precision. + */ + png_create_colormap_entry(display, 254, back_r, back_g, back_b, + back_alpha, output_encoding); + } + + else + output_processing = PNG_CMAP_NONE; + } + break; + + case PNG_COLOR_TYPE_GRAY_ALPHA: + /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum + * of 65536 combinations. If, however, the alpha channel is to be + * removed there are only 256 possibilities if the background is gray. + * (Otherwise there is a subset of the 65536 possibilities defined by + * the triangle between black, white and the background color.) + * + * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to + * worry about tRNS matching - tRNS is ignored if there is an alpha + * channel. + */ + data_encoding = P_sRGB; + + if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) + { + if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) + png_error(png_ptr, "gray+alpha color-map: too few entries"); + + cmap_entries = make_ga_colormap(display); + + background_index = PNG_CMAP_GA_BACKGROUND; + output_processing = PNG_CMAP_GA; + } + + else /* alpha is removed */ + { + /* Alpha must be removed as the PNG data is processed when the + * background is a color because the G and A channels are + * independent and the vector addition (non-parallel vectors) is a + * 2-D problem. + * + * This can be reduced to the same algorithm as above by making a + * colormap containing gray levels (for the opaque grays), a + * background entry (for a transparent pixel) and a set of four six + * level color values, one set for each intermediate alpha value. + * See the comments in make_ga_colormap for how this works in the + * per-pixel processing. + * + * If the background is gray, however, we only need a 256 entry gray + * level color map. It is sufficient to make the entry generated + * for the background color be exactly the color specified. + */ + if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 || + (back_r == back_g && back_g == back_b)) + { + /* Background is gray; no special processing will be required. */ + png_color_16 c; + png_uint_32 gray = back_g; + + if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) + png_error(png_ptr, "gray-alpha color-map: too few entries"); + + cmap_entries = make_gray_colormap(display); + + if (output_encoding == P_LINEAR) + { + gray = PNG_sRGB_FROM_LINEAR(gray * 255); + + /* And make sure the corresponding palette entry matches. */ + png_create_colormap_entry(display, gray, back_g, back_g, + back_g, 65535, P_LINEAR); + } + + /* The background passed to libpng, however, must be the sRGB + * value. + */ + c.index = 0; /*unused*/ + c.gray = c.red = c.green = c.blue = (png_uint_16)gray; + + png_set_background_fixed(png_ptr, &c, + PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, + 0/*gamma: not used*/); + + output_processing = PNG_CMAP_NONE; + } + + else + { + png_uint_32 i, a; + + /* This is the same as png_make_ga_colormap, above, except that + * the entries are all opaque. + */ + if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) + png_error(png_ptr, "ga-alpha color-map: too few entries"); + + i = 0; + while (i < 231) + { + png_uint_32 gray = (i * 256 + 115) / 231; + png_create_colormap_entry(display, i++, gray, gray, gray, + 255, P_sRGB); + } + + /* NOTE: this preserves the full precision of the application + * background color. + */ + background_index = i; + png_create_colormap_entry(display, i++, back_r, back_g, back_b, +#ifdef __COVERITY__ + /* Coverity claims that output_encoding cannot be 2 (P_LINEAR) + * here. + */ 255U, +#else + output_encoding == P_LINEAR ? 65535U : 255U, +#endif + output_encoding); + + /* For non-opaque input composite on the sRGB background - this + * requires inverting the encoding for each component. The input + * is still converted to the sRGB encoding because this is a + * reasonable approximate to the logarithmic curve of human + * visual sensitivity, at least over the narrow range which PNG + * represents. Consequently 'G' is always sRGB encoded, while + * 'A' is linear. We need the linear background colors. + */ + if (output_encoding == P_sRGB) /* else already linear */ + { + /* This may produce a value not exactly matching the + * background, but that's ok because these numbers are only + * used when alpha != 0 + */ + back_r = png_sRGB_table[back_r]; + back_g = png_sRGB_table[back_g]; + back_b = png_sRGB_table[back_b]; + } + + for (a=1; a<5; ++a) + { + unsigned int g; + + /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled + * by an 8-bit alpha value (0..255). + */ + png_uint_32 alpha = 51 * a; + png_uint_32 back_rx = (255-alpha) * back_r; + png_uint_32 back_gx = (255-alpha) * back_g; + png_uint_32 back_bx = (255-alpha) * back_b; + + for (g=0; g<6; ++g) + { + png_uint_32 gray = png_sRGB_table[g*51] * alpha; + + png_create_colormap_entry(display, i++, + PNG_sRGB_FROM_LINEAR(gray + back_rx), + PNG_sRGB_FROM_LINEAR(gray + back_gx), + PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB); + } + } + + cmap_entries = i; + output_processing = PNG_CMAP_GA; + } + } + break; + + case PNG_COLOR_TYPE_RGB: + case PNG_COLOR_TYPE_RGB_ALPHA: + /* Exclude the case where the output is gray; we can always handle this + * with the cases above. + */ + if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0) + { + /* The color-map will be grayscale, so we may as well convert the + * input RGB values to a simple grayscale and use the grayscale + * code above. + * + * NOTE: calling this apparently damages the recognition of the + * transparent color in background color handling; call + * png_set_tRNS_to_alpha before png_set_background_fixed. + */ + png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1, + -1); + data_encoding = P_sRGB; + + /* The output will now be one or two 8-bit gray or gray+alpha + * channels. The more complex case arises when the input has alpha. + */ + if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || + png_ptr->num_trans > 0) && + (output_format & PNG_FORMAT_FLAG_ALPHA) != 0) + { + /* Both input and output have an alpha channel, so no background + * processing is required; just map the GA bytes to the right + * color-map entry. + */ + expand_tRNS = 1; + + if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) + png_error(png_ptr, "rgb[ga] color-map: too few entries"); + + cmap_entries = make_ga_colormap(display); + background_index = PNG_CMAP_GA_BACKGROUND; + output_processing = PNG_CMAP_GA; + } + + else + { + /* Either the input or the output has no alpha channel, so there + * will be no non-opaque pixels in the color-map; it will just be + * grayscale. + */ + if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) + png_error(png_ptr, "rgb[gray] color-map: too few entries"); + + /* Ideally this code would use libpng to do the gamma correction, + * but if an input alpha channel is to be removed we will hit the + * libpng bug in gamma+compose+rgb-to-gray (the double gamma + * correction bug). Fix this by dropping the gamma correction in + * this case and doing it in the palette; this will result in + * duplicate palette entries, but that's better than the + * alternative of double gamma correction. + */ + if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || + png_ptr->num_trans > 0) && + png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0) + { + cmap_entries = make_gray_file_colormap(display); + data_encoding = P_FILE; + } + + else + cmap_entries = make_gray_colormap(display); + + /* But if the input has alpha or transparency it must be removed + */ + if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || + png_ptr->num_trans > 0) + { + png_color_16 c; + png_uint_32 gray = back_g; + + /* We need to ensure that the application background exists in + * the colormap and that completely transparent pixels map to + * it. Achieve this simply by ensuring that the entry + * selected for the background really is the background color. + */ + if (data_encoding == P_FILE) /* from the fixup above */ + { + /* The app supplied a gray which is in output_encoding, we + * need to convert it to a value of the input (P_FILE) + * encoding then set this palette entry to the required + * output encoding. + */ + if (output_encoding == P_sRGB) + gray = png_sRGB_table[gray]; /* now P_LINEAR */ + + gray = PNG_DIV257(png_gamma_16bit_correct(gray, + png_ptr->colorspace.gamma)); /* now P_FILE */ + + /* And make sure the corresponding palette entry contains + * exactly the required sRGB value. + */ + png_create_colormap_entry(display, gray, back_g, back_g, + back_g, 0/*unused*/, output_encoding); + } + + else if (output_encoding == P_LINEAR) + { + gray = PNG_sRGB_FROM_LINEAR(gray * 255); + + /* And make sure the corresponding palette entry matches. + */ + png_create_colormap_entry(display, gray, back_g, back_g, + back_g, 0/*unused*/, P_LINEAR); + } + + /* The background passed to libpng, however, must be the + * output (normally sRGB) value. + */ + c.index = 0; /*unused*/ + c.gray = c.red = c.green = c.blue = (png_uint_16)gray; + + /* NOTE: the following is apparently a bug in libpng. Without + * it the transparent color recognition in + * png_set_background_fixed seems to go wrong. + */ + expand_tRNS = 1; + png_set_background_fixed(png_ptr, &c, + PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, + 0/*gamma: not used*/); + } + + output_processing = PNG_CMAP_NONE; + } + } + + else /* output is color */ + { + /* We could use png_quantize here so long as there is no transparent + * color or alpha; png_quantize ignores alpha. Easier overall just + * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube. + * Consequently we always want libpng to produce sRGB data. + */ + data_encoding = P_sRGB; + + /* Is there any transparency or alpha? */ + if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || + png_ptr->num_trans > 0) + { + /* Is there alpha in the output too? If so all four channels are + * processed into a special RGB cube with alpha support. + */ + if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) + { + png_uint_32 r; + + if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) + png_error(png_ptr, "rgb+alpha color-map: too few entries"); + + cmap_entries = make_rgb_colormap(display); + + /* Add a transparent entry. */ + png_create_colormap_entry(display, cmap_entries, 255, 255, + 255, 0, P_sRGB); + + /* This is stored as the background index for the processing + * algorithm. + */ + background_index = cmap_entries++; + + /* Add 27 r,g,b entries each with alpha 0.5. */ + for (r=0; r<256; r = (r << 1) | 0x7f) + { + png_uint_32 g; + + for (g=0; g<256; g = (g << 1) | 0x7f) + { + png_uint_32 b; + + /* This generates components with the values 0, 127 and + * 255 + */ + for (b=0; b<256; b = (b << 1) | 0x7f) + png_create_colormap_entry(display, cmap_entries++, + r, g, b, 128, P_sRGB); + } + } + + expand_tRNS = 1; + output_processing = PNG_CMAP_RGB_ALPHA; + } + + else + { + /* Alpha/transparency must be removed. The background must + * exist in the color map (achieved by setting adding it after + * the 666 color-map). If the standard processing code will + * pick up this entry automatically that's all that is + * required; libpng can be called to do the background + * processing. + */ + unsigned int sample_size = + PNG_IMAGE_SAMPLE_SIZE(output_format); + png_uint_32 r, g, b; /* sRGB background */ + + if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) + png_error(png_ptr, "rgb-alpha color-map: too few entries"); + + cmap_entries = make_rgb_colormap(display); + + png_create_colormap_entry(display, cmap_entries, back_r, + back_g, back_b, 0/*unused*/, output_encoding); + + if (output_encoding == P_LINEAR) + { + r = PNG_sRGB_FROM_LINEAR(back_r * 255); + g = PNG_sRGB_FROM_LINEAR(back_g * 255); + b = PNG_sRGB_FROM_LINEAR(back_b * 255); + } + + else + { + r = back_r; + g = back_g; + b = back_g; + } + + /* Compare the newly-created color-map entry with the one the + * PNG_CMAP_RGB algorithm will use. If the two entries don't + * match, add the new one and set this as the background + * index. + */ + if (memcmp((png_const_bytep)display->colormap + + sample_size * cmap_entries, + (png_const_bytep)display->colormap + + sample_size * PNG_RGB_INDEX(r,g,b), + sample_size) != 0) + { + /* The background color must be added. */ + background_index = cmap_entries++; + + /* Add 27 r,g,b entries each with created by composing with + * the background at alpha 0.5. + */ + for (r=0; r<256; r = (r << 1) | 0x7f) + { + for (g=0; g<256; g = (g << 1) | 0x7f) + { + /* This generates components with the values 0, 127 + * and 255 + */ + for (b=0; b<256; b = (b << 1) | 0x7f) + png_create_colormap_entry(display, cmap_entries++, + png_colormap_compose(display, r, P_sRGB, 128, + back_r, output_encoding), + png_colormap_compose(display, g, P_sRGB, 128, + back_g, output_encoding), + png_colormap_compose(display, b, P_sRGB, 128, + back_b, output_encoding), + 0/*unused*/, output_encoding); + } + } + + expand_tRNS = 1; + output_processing = PNG_CMAP_RGB_ALPHA; + } + + else /* background color is in the standard color-map */ + { + png_color_16 c; + + c.index = 0; /*unused*/ + c.red = (png_uint_16)back_r; + c.gray = c.green = (png_uint_16)back_g; + c.blue = (png_uint_16)back_b; + + png_set_background_fixed(png_ptr, &c, + PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, + 0/*gamma: not used*/); + + output_processing = PNG_CMAP_RGB; + } + } + } + + else /* no alpha or transparency in the input */ + { + /* Alpha in the output is irrelevant, simply map the opaque input + * pixels to the 6x6x6 color-map. + */ + if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries) + png_error(png_ptr, "rgb color-map: too few entries"); + + cmap_entries = make_rgb_colormap(display); + output_processing = PNG_CMAP_RGB; + } + } + break; + + case PNG_COLOR_TYPE_PALETTE: + /* It's already got a color-map. It may be necessary to eliminate the + * tRNS entries though. + */ + { + unsigned int num_trans = png_ptr->num_trans; + png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL; + png_const_colorp colormap = png_ptr->palette; + const int do_background = trans != NULL && + (output_format & PNG_FORMAT_FLAG_ALPHA) == 0; + unsigned int i; + + /* Just in case: */ + if (trans == NULL) + num_trans = 0; + + output_processing = PNG_CMAP_NONE; + data_encoding = P_FILE; /* Don't change from color-map indices */ + cmap_entries = png_ptr->num_palette; + if (cmap_entries > 256) + cmap_entries = 256; + + if (cmap_entries > image->colormap_entries) + png_error(png_ptr, "palette color-map: too few entries"); + + for (i=0; i < cmap_entries; ++i) + { + if (do_background != 0 && i < num_trans && trans[i] < 255) + { + if (trans[i] == 0) + png_create_colormap_entry(display, i, back_r, back_g, + back_b, 0, output_encoding); + + else + { + /* Must compose the PNG file color in the color-map entry + * on the sRGB color in 'back'. + */ + png_create_colormap_entry(display, i, + png_colormap_compose(display, colormap[i].red, P_FILE, + trans[i], back_r, output_encoding), + png_colormap_compose(display, colormap[i].green, P_FILE, + trans[i], back_g, output_encoding), + png_colormap_compose(display, colormap[i].blue, P_FILE, + trans[i], back_b, output_encoding), + output_encoding == P_LINEAR ? trans[i] * 257U : + trans[i], + output_encoding); + } + } + + else + png_create_colormap_entry(display, i, colormap[i].red, + colormap[i].green, colormap[i].blue, + i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/); + } + + /* The PNG data may have indices packed in fewer than 8 bits, it + * must be expanded if so. + */ + if (png_ptr->bit_depth < 8) + png_set_packing(png_ptr); + } + break; + + default: + png_error(png_ptr, "invalid PNG color type"); + /*NOT REACHED*/ + } + + /* Now deal with the output processing */ + if (expand_tRNS != 0 && png_ptr->num_trans > 0 && + (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0) + png_set_tRNS_to_alpha(png_ptr); + + switch (data_encoding) + { + case P_sRGB: + /* Change to 8-bit sRGB */ + png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB); + /* FALL THROUGH */ + + case P_FILE: + if (png_ptr->bit_depth > 8) + png_set_scale_16(png_ptr); + break; + +#ifdef __GNUC__ + default: + png_error(png_ptr, "bad data option (internal error)"); +#endif + } + + if (cmap_entries > 256 || cmap_entries > image->colormap_entries) + png_error(png_ptr, "color map overflow (BAD internal error)"); + + image->colormap_entries = cmap_entries; + + /* Double check using the recorded background index */ + switch (output_processing) + { + case PNG_CMAP_NONE: + if (background_index != PNG_CMAP_NONE_BACKGROUND) + goto bad_background; + break; + + case PNG_CMAP_GA: + if (background_index != PNG_CMAP_GA_BACKGROUND) + goto bad_background; + break; + + case PNG_CMAP_TRANS: + if (background_index >= cmap_entries || + background_index != PNG_CMAP_TRANS_BACKGROUND) + goto bad_background; + break; + + case PNG_CMAP_RGB: + if (background_index != PNG_CMAP_RGB_BACKGROUND) + goto bad_background; + break; + + case PNG_CMAP_RGB_ALPHA: + if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND) + goto bad_background; + break; + + default: + png_error(png_ptr, "bad processing option (internal error)"); + + bad_background: + png_error(png_ptr, "bad background index (internal error)"); + } + + display->colormap_processing = output_processing; + + return 1/*ok*/; +} + +/* The final part of the color-map read called from png_image_finish_read. */ +static int +png_image_read_and_map(png_voidp argument) +{ + png_image_read_control *display = png_voidcast(png_image_read_control*, + argument); + png_imagep image = display->image; + png_structrp png_ptr = image->opaque->png_ptr; + int passes; + + /* Called when the libpng data must be transformed into the color-mapped + * form. There is a local row buffer in display->local and this routine must + * do the interlace handling. + */ + switch (png_ptr->interlaced) + { + case PNG_INTERLACE_NONE: + passes = 1; + break; + + case PNG_INTERLACE_ADAM7: + passes = PNG_INTERLACE_ADAM7_PASSES; + break; + + default: + png_error(png_ptr, "unknown interlace type"); + } + + { + png_uint_32 height = image->height; + png_uint_32 width = image->width; + int proc = display->colormap_processing; + png_bytep first_row = png_voidcast(png_bytep, display->first_row); + ptrdiff_t step_row = display->row_bytes; + int pass; + + for (pass = 0; pass < passes; ++pass) + { + unsigned int startx, stepx, stepy; + png_uint_32 y; + + if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) + { + /* The row may be empty for a short image: */ + if (PNG_PASS_COLS(width, pass) == 0) + continue; + + startx = PNG_PASS_START_COL(pass); + stepx = PNG_PASS_COL_OFFSET(pass); + y = PNG_PASS_START_ROW(pass); + stepy = PNG_PASS_ROW_OFFSET(pass); + } + + else + { + y = 0; + startx = 0; + stepx = stepy = 1; + } + + for (; y<height; y += stepy) + { + png_bytep inrow = png_voidcast(png_bytep, display->local_row); + png_bytep outrow = first_row + y * step_row; + png_const_bytep end_row = outrow + width; + + /* Read read the libpng data into the temporary buffer. */ + png_read_row(png_ptr, inrow, NULL); + + /* Now process the row according to the processing option, note + * that the caller verifies that the format of the libpng output + * data is as required. + */ + outrow += startx; + switch (proc) + { + case PNG_CMAP_GA: + for (; outrow < end_row; outrow += stepx) + { + /* The data is always in the PNG order */ + unsigned int gray = *inrow++; + unsigned int alpha = *inrow++; + unsigned int entry; + + /* NOTE: this code is copied as a comment in + * make_ga_colormap above. Please update the + * comment if you change this code! + */ + if (alpha > 229) /* opaque */ + { + entry = (231 * gray + 128) >> 8; + } + else if (alpha < 26) /* transparent */ + { + entry = 231; + } + else /* partially opaque */ + { + entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray); + } + + *outrow = (png_byte)entry; + } + break; + + case PNG_CMAP_TRANS: + for (; outrow < end_row; outrow += stepx) + { + png_byte gray = *inrow++; + png_byte alpha = *inrow++; + + if (alpha == 0) + *outrow = PNG_CMAP_TRANS_BACKGROUND; + + else if (gray != PNG_CMAP_TRANS_BACKGROUND) + *outrow = gray; + + else + *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1); + } + break; + + case PNG_CMAP_RGB: + for (; outrow < end_row; outrow += stepx) + { + *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]); + inrow += 3; + } + break; + + case PNG_CMAP_RGB_ALPHA: + for (; outrow < end_row; outrow += stepx) + { + unsigned int alpha = inrow[3]; + + /* Because the alpha entries only hold alpha==0.5 values + * split the processing at alpha==0.25 (64) and 0.75 + * (196). + */ + + if (alpha >= 196) + *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], + inrow[2]); + + else if (alpha < 64) + *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND; + + else + { + /* Likewise there are three entries for each of r, g + * and b. We could select the entry by popcount on + * the top two bits on those architectures that + * support it, this is what the code below does, + * crudely. + */ + unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1; + + /* Here are how the values map: + * + * 0x00 .. 0x3f -> 0 + * 0x40 .. 0xbf -> 1 + * 0xc0 .. 0xff -> 2 + * + * So, as above with the explicit alpha checks, the + * breakpoints are at 64 and 196. + */ + if (inrow[0] & 0x80) back_i += 9; /* red */ + if (inrow[0] & 0x40) back_i += 9; + if (inrow[0] & 0x80) back_i += 3; /* green */ + if (inrow[0] & 0x40) back_i += 3; + if (inrow[0] & 0x80) back_i += 1; /* blue */ + if (inrow[0] & 0x40) back_i += 1; + + *outrow = (png_byte)back_i; + } + + inrow += 4; + } + break; + + default: + break; + } + } + } + } + + return 1; +} + +static int +png_image_read_colormapped(png_voidp argument) +{ + png_image_read_control *display = png_voidcast(png_image_read_control*, + argument); + png_imagep image = display->image; + png_controlp control = image->opaque; + png_structrp png_ptr = control->png_ptr; + png_inforp info_ptr = control->info_ptr; + + int passes = 0; /* As a flag */ + + PNG_SKIP_CHUNKS(png_ptr); + + /* Update the 'info' structure and make sure the result is as required; first + * make sure to turn on the interlace handling if it will be required + * (because it can't be turned on *after* the call to png_read_update_info!) + */ + if (display->colormap_processing == PNG_CMAP_NONE) + passes = png_set_interlace_handling(png_ptr); + + png_read_update_info(png_ptr, info_ptr); + + /* The expected output can be deduced from the colormap_processing option. */ + switch (display->colormap_processing) + { + case PNG_CMAP_NONE: + /* Output must be one channel and one byte per pixel, the output + * encoding can be anything. + */ + if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE || + info_ptr->color_type == PNG_COLOR_TYPE_GRAY) && + info_ptr->bit_depth == 8) + break; + + goto bad_output; + + case PNG_CMAP_TRANS: + case PNG_CMAP_GA: + /* Output must be two channels and the 'G' one must be sRGB, the latter + * can be checked with an exact number because it should have been set + * to this number above! + */ + if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA && + info_ptr->bit_depth == 8 && + png_ptr->screen_gamma == PNG_GAMMA_sRGB && + image->colormap_entries == 256) + break; + + goto bad_output; + + case PNG_CMAP_RGB: + /* Output must be 8-bit sRGB encoded RGB */ + if (info_ptr->color_type == PNG_COLOR_TYPE_RGB && + info_ptr->bit_depth == 8 && + png_ptr->screen_gamma == PNG_GAMMA_sRGB && + image->colormap_entries == 216) + break; + + goto bad_output; + + case PNG_CMAP_RGB_ALPHA: + /* Output must be 8-bit sRGB encoded RGBA */ + if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA && + info_ptr->bit_depth == 8 && + png_ptr->screen_gamma == PNG_GAMMA_sRGB && + image->colormap_entries == 244 /* 216 + 1 + 27 */) + break; + + /* goto bad_output; */ + /* FALL THROUGH */ + + default: + bad_output: + png_error(png_ptr, "bad color-map processing (internal error)"); + } + + /* Now read the rows. Do this here if it is possible to read directly into + * the output buffer, otherwise allocate a local row buffer of the maximum + * size libpng requires and call the relevant processing routine safely. + */ + { + png_voidp first_row = display->buffer; + ptrdiff_t row_bytes = display->row_stride; + + /* The following expression is designed to work correctly whether it gives + * a signed or an unsigned result. + */ + if (row_bytes < 0) + { + char *ptr = png_voidcast(char*, first_row); + ptr += (image->height-1) * (-row_bytes); + first_row = png_voidcast(png_voidp, ptr); + } + + display->first_row = first_row; + display->row_bytes = row_bytes; + } + + if (passes == 0) + { + int result; + png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); + + display->local_row = row; + result = png_safe_execute(image, png_image_read_and_map, display); + display->local_row = NULL; + png_free(png_ptr, row); + + return result; + } + + else + { + png_alloc_size_t row_bytes = display->row_bytes; + + while (--passes >= 0) + { + png_uint_32 y = image->height; + png_bytep row = png_voidcast(png_bytep, display->first_row); + + while (y-- > 0) + { + png_read_row(png_ptr, row, NULL); + row += row_bytes; + } + } + + return 1; + } +} + +/* Just the row reading part of png_image_read. */ +static int +png_image_read_composite(png_voidp argument) +{ + png_image_read_control *display = png_voidcast(png_image_read_control*, + argument); + png_imagep image = display->image; + png_structrp png_ptr = image->opaque->png_ptr; + int passes; + + switch (png_ptr->interlaced) + { + case PNG_INTERLACE_NONE: + passes = 1; + break; + + case PNG_INTERLACE_ADAM7: + passes = PNG_INTERLACE_ADAM7_PASSES; + break; + + default: + png_error(png_ptr, "unknown interlace type"); + } + + { + png_uint_32 height = image->height; + png_uint_32 width = image->width; + ptrdiff_t step_row = display->row_bytes; + unsigned int channels = + (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1; + int pass; + + for (pass = 0; pass < passes; ++pass) + { + unsigned int startx, stepx, stepy; + png_uint_32 y; + + if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) + { + /* The row may be empty for a short image: */ + if (PNG_PASS_COLS(width, pass) == 0) + continue; + + startx = PNG_PASS_START_COL(pass) * channels; + stepx = PNG_PASS_COL_OFFSET(pass) * channels; + y = PNG_PASS_START_ROW(pass); + stepy = PNG_PASS_ROW_OFFSET(pass); + } + + else + { + y = 0; + startx = 0; + stepx = channels; + stepy = 1; + } + + for (; y<height; y += stepy) + { + png_bytep inrow = png_voidcast(png_bytep, display->local_row); + png_bytep outrow; + png_const_bytep end_row; + + /* Read the row, which is packed: */ + png_read_row(png_ptr, inrow, NULL); + + outrow = png_voidcast(png_bytep, display->first_row); + outrow += y * step_row; + end_row = outrow + width * channels; + + /* Now do the composition on each pixel in this row. */ + outrow += startx; + for (; outrow < end_row; outrow += stepx) + { + png_byte alpha = inrow[channels]; + + if (alpha > 0) /* else no change to the output */ + { + unsigned int c; + + for (c=0; c<channels; ++c) + { + png_uint_32 component = inrow[c]; + + if (alpha < 255) /* else just use component */ + { + /* This is PNG_OPTIMIZED_ALPHA, the component value + * is a linear 8-bit value. Combine this with the + * current outrow[c] value which is sRGB encoded. + * Arithmetic here is 16-bits to preserve the output + * values correctly. + */ + component *= 257*255; /* =65535 */ + component += (255-alpha)*png_sRGB_table[outrow[c]]; + + /* So 'component' is scaled by 255*65535 and is + * therefore appropriate for the sRGB to linear + * conversion table. + */ + component = PNG_sRGB_FROM_LINEAR(component); + } + + outrow[c] = (png_byte)component; + } + } + + inrow += channels+1; /* components and alpha channel */ + } + } + } + } + + return 1; +} + +/* The do_local_background case; called when all the following transforms are to + * be done: + * + * PNG_RGB_TO_GRAY + * PNG_COMPOSITE + * PNG_GAMMA + * + * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and + * PNG_COMPOSITE code performs gamma correction, so we get double gamma + * correction. The fix-up is to prevent the PNG_COMPOSITE operation from + * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha + * row and handles the removal or pre-multiplication of the alpha channel. + */ +static int +png_image_read_background(png_voidp argument) +{ + png_image_read_control *display = png_voidcast(png_image_read_control*, + argument); + png_imagep image = display->image; + png_structrp png_ptr = image->opaque->png_ptr; + png_inforp info_ptr = image->opaque->info_ptr; + png_uint_32 height = image->height; + png_uint_32 width = image->width; + int pass, passes; + + /* Double check the convoluted logic below. We expect to get here with + * libpng doing rgb to gray and gamma correction but background processing + * left to the png_image_read_background function. The rows libpng produce + * might be 8 or 16-bit but should always have two channels; gray plus alpha. + */ + if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0) + png_error(png_ptr, "lost rgb to gray"); + + if ((png_ptr->transformations & PNG_COMPOSE) != 0) + png_error(png_ptr, "unexpected compose"); + + if (png_get_channels(png_ptr, info_ptr) != 2) + png_error(png_ptr, "lost/gained channels"); + + /* Expect the 8-bit case to always remove the alpha channel */ + if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 && + (image->format & PNG_FORMAT_FLAG_ALPHA) != 0) + png_error(png_ptr, "unexpected 8-bit transformation"); + + switch (png_ptr->interlaced) + { + case PNG_INTERLACE_NONE: + passes = 1; + break; + + case PNG_INTERLACE_ADAM7: + passes = PNG_INTERLACE_ADAM7_PASSES; + break; + + default: + png_error(png_ptr, "unknown interlace type"); + } + + /* Use direct access to info_ptr here because otherwise the simplified API + * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is + * checking the value after libpng expansions, not the original value in the + * PNG. + */ + switch (info_ptr->bit_depth) + { + case 8: + /* 8-bit sRGB gray values with an alpha channel; the alpha channel is + * to be removed by composing on a background: either the row if + * display->background is NULL or display->background->green if not. + * Unlike the code above ALPHA_OPTIMIZED has *not* been done. + */ + { + png_bytep first_row = png_voidcast(png_bytep, display->first_row); + ptrdiff_t step_row = display->row_bytes; + + for (pass = 0; pass < passes; ++pass) + { + png_bytep row = png_voidcast(png_bytep, + display->first_row); + unsigned int startx, stepx, stepy; + png_uint_32 y; + + if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) + { + /* The row may be empty for a short image: */ + if (PNG_PASS_COLS(width, pass) == 0) + continue; + + startx = PNG_PASS_START_COL(pass); + stepx = PNG_PASS_COL_OFFSET(pass); + y = PNG_PASS_START_ROW(pass); + stepy = PNG_PASS_ROW_OFFSET(pass); + } + + else + { + y = 0; + startx = 0; + stepx = stepy = 1; + } + + if (display->background == NULL) + { + for (; y<height; y += stepy) + { + png_bytep inrow = png_voidcast(png_bytep, + display->local_row); + png_bytep outrow = first_row + y * step_row; + png_const_bytep end_row = outrow + width; + + /* Read the row, which is packed: */ + png_read_row(png_ptr, inrow, NULL); + + /* Now do the composition on each pixel in this row. */ + outrow += startx; + for (; outrow < end_row; outrow += stepx) + { + png_byte alpha = inrow[1]; + + if (alpha > 0) /* else no change to the output */ + { + png_uint_32 component = inrow[0]; + + if (alpha < 255) /* else just use component */ + { + /* Since PNG_OPTIMIZED_ALPHA was not set it is + * necessary to invert the sRGB transfer + * function and multiply the alpha out. + */ + component = png_sRGB_table[component] * alpha; + component += png_sRGB_table[outrow[0]] * + (255-alpha); + component = PNG_sRGB_FROM_LINEAR(component); + } + + outrow[0] = (png_byte)component; + } + + inrow += 2; /* gray and alpha channel */ + } + } + } + + else /* constant background value */ + { + png_byte background8 = display->background->green; + png_uint_16 background = png_sRGB_table[background8]; + + for (; y<height; y += stepy) + { + png_bytep inrow = png_voidcast(png_bytep, + display->local_row); + png_bytep outrow = first_row + y * step_row; + png_const_bytep end_row = outrow + width; + + /* Read the row, which is packed: */ + png_read_row(png_ptr, inrow, NULL); + + /* Now do the composition on each pixel in this row. */ + outrow += startx; + for (; outrow < end_row; outrow += stepx) + { + png_byte alpha = inrow[1]; + + if (alpha > 0) /* else use background */ + { + png_uint_32 component = inrow[0]; + + if (alpha < 255) /* else just use component */ + { + component = png_sRGB_table[component] * alpha; + component += background * (255-alpha); + component = PNG_sRGB_FROM_LINEAR(component); + } + + outrow[0] = (png_byte)component; + } + + else + outrow[0] = background8; + + inrow += 2; /* gray and alpha channel */ + } + + row += display->row_bytes; + } + } + } + } + break; + + case 16: + /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must + * still be done and, maybe, the alpha channel removed. This code also + * handles the alpha-first option. + */ + { + png_uint_16p first_row = png_voidcast(png_uint_16p, + display->first_row); + /* The division by two is safe because the caller passed in a + * stride which was multiplied by 2 (below) to get row_bytes. + */ + ptrdiff_t step_row = display->row_bytes / 2; + int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0; + unsigned int outchannels = 1+preserve_alpha; + int swap_alpha = 0; + +# ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED + if (preserve_alpha != 0 && + (image->format & PNG_FORMAT_FLAG_AFIRST) != 0) + swap_alpha = 1; +# endif + + for (pass = 0; pass < passes; ++pass) + { + unsigned int startx, stepx, stepy; + png_uint_32 y; + + /* The 'x' start and step are adjusted to output components here. + */ + if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) + { + /* The row may be empty for a short image: */ + if (PNG_PASS_COLS(width, pass) == 0) + continue; + + startx = PNG_PASS_START_COL(pass) * outchannels; + stepx = PNG_PASS_COL_OFFSET(pass) * outchannels; + y = PNG_PASS_START_ROW(pass); + stepy = PNG_PASS_ROW_OFFSET(pass); + } + + else + { + y = 0; + startx = 0; + stepx = outchannels; + stepy = 1; + } + + for (; y<height; y += stepy) + { + png_const_uint_16p inrow; + png_uint_16p outrow = first_row + y*step_row; + png_uint_16p end_row = outrow + width * outchannels; + + /* Read the row, which is packed: */ + png_read_row(png_ptr, png_voidcast(png_bytep, + display->local_row), NULL); + inrow = png_voidcast(png_const_uint_16p, display->local_row); + + /* Now do the pre-multiplication on each pixel in this row. + */ + outrow += startx; + for (; outrow < end_row; outrow += stepx) + { + png_uint_32 component = inrow[0]; + png_uint_16 alpha = inrow[1]; + + if (alpha > 0) /* else 0 */ + { + if (alpha < 65535) /* else just use component */ + { + component *= alpha; + component += 32767; + component /= 65535; + } + } + + else + component = 0; + + outrow[swap_alpha] = (png_uint_16)component; + if (preserve_alpha != 0) + outrow[1 ^ swap_alpha] = alpha; + + inrow += 2; /* components and alpha channel */ + } + } + } + } + break; + +#ifdef __GNUC__ + default: + png_error(png_ptr, "unexpected bit depth"); +#endif + } + + return 1; +} + +/* The guts of png_image_finish_read as a png_safe_execute callback. */ +static int +png_image_read_direct(png_voidp argument) +{ + png_image_read_control *display = png_voidcast(png_image_read_control*, + argument); + png_imagep image = display->image; + png_structrp png_ptr = image->opaque->png_ptr; + png_inforp info_ptr = image->opaque->info_ptr; + + png_uint_32 format = image->format; + int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0; + int do_local_compose = 0; + int do_local_background = 0; /* to avoid double gamma correction bug */ + int passes = 0; + + /* Add transforms to ensure the correct output format is produced then check + * that the required implementation support is there. Always expand; always + * need 8 bits minimum, no palette and expanded tRNS. + */ + png_set_expand(png_ptr); + + /* Now check the format to see if it was modified. */ + { + png_uint_32 base_format = png_image_format(png_ptr) & + ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */; + png_uint_32 change = format ^ base_format; + png_fixed_point output_gamma; + int mode; /* alpha mode */ + + /* Do this first so that we have a record if rgb to gray is happening. */ + if ((change & PNG_FORMAT_FLAG_COLOR) != 0) + { + /* gray<->color transformation required. */ + if ((format & PNG_FORMAT_FLAG_COLOR) != 0) + png_set_gray_to_rgb(png_ptr); + + else + { + /* libpng can't do both rgb to gray and + * background/pre-multiplication if there is also significant gamma + * correction, because both operations require linear colors and + * the code only supports one transform doing the gamma correction. + * Handle this by doing the pre-multiplication or background + * operation in this code, if necessary. + * + * TODO: fix this by rewriting pngrtran.c (!) + * + * For the moment (given that fixing this in pngrtran.c is an + * enormous change) 'do_local_background' is used to indicate that + * the problem exists. + */ + if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) + do_local_background = 1/*maybe*/; + + png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, + PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT); + } + + change &= ~PNG_FORMAT_FLAG_COLOR; + } + + /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise. + */ + { + png_fixed_point input_gamma_default; + + if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 && + (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) + input_gamma_default = PNG_GAMMA_LINEAR; + else + input_gamma_default = PNG_DEFAULT_sRGB; + + /* Call png_set_alpha_mode to set the default for the input gamma; the + * output gamma is set by a second call below. + */ + png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default); + } + + if (linear != 0) + { + /* If there *is* an alpha channel in the input it must be multiplied + * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG. + */ + if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) + mode = PNG_ALPHA_STANDARD; /* associated alpha */ + + else + mode = PNG_ALPHA_PNG; + + output_gamma = PNG_GAMMA_LINEAR; + } + + else + { + mode = PNG_ALPHA_PNG; + output_gamma = PNG_DEFAULT_sRGB; + } + + /* If 'do_local_background' is set check for the presence of gamma + * correction; this is part of the work-round for the libpng bug + * described above. + * + * TODO: fix libpng and remove this. + */ + if (do_local_background != 0) + { + png_fixed_point gtest; + + /* This is 'png_gamma_threshold' from pngrtran.c; the test used for + * gamma correction, the screen gamma hasn't been set on png_struct + * yet; it's set below. png_struct::gamma, however, is set to the + * final value. + */ + if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma, + PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0) + do_local_background = 0; + + else if (mode == PNG_ALPHA_STANDARD) + { + do_local_background = 2/*required*/; + mode = PNG_ALPHA_PNG; /* prevent libpng doing it */ + } + + /* else leave as 1 for the checks below */ + } + + /* If the bit-depth changes then handle that here. */ + if ((change & PNG_FORMAT_FLAG_LINEAR) != 0) + { + if (linear != 0 /*16-bit output*/) + png_set_expand_16(png_ptr); + + else /* 8-bit output */ + png_set_scale_16(png_ptr); + + change &= ~PNG_FORMAT_FLAG_LINEAR; + } + + /* Now the background/alpha channel changes. */ + if ((change & PNG_FORMAT_FLAG_ALPHA) != 0) + { + /* Removing an alpha channel requires composition for the 8-bit + * formats; for the 16-bit it is already done, above, by the + * pre-multiplication and the channel just needs to be stripped. + */ + if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) + { + /* If RGB->gray is happening the alpha channel must be left and the + * operation completed locally. + * + * TODO: fix libpng and remove this. + */ + if (do_local_background != 0) + do_local_background = 2/*required*/; + + /* 16-bit output: just remove the channel */ + else if (linear != 0) /* compose on black (well, pre-multiply) */ + png_set_strip_alpha(png_ptr); + + /* 8-bit output: do an appropriate compose */ + else if (display->background != NULL) + { + png_color_16 c; + + c.index = 0; /*unused*/ + c.red = display->background->red; + c.green = display->background->green; + c.blue = display->background->blue; + c.gray = display->background->green; + + /* This is always an 8-bit sRGB value, using the 'green' channel + * for gray is much better than calculating the luminance here; + * we can get off-by-one errors in that calculation relative to + * the app expectations and that will show up in transparent + * pixels. + */ + png_set_background_fixed(png_ptr, &c, + PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, + 0/*gamma: not used*/); + } + + else /* compose on row: implemented below. */ + { + do_local_compose = 1; + /* This leaves the alpha channel in the output, so it has to be + * removed by the code below. Set the encoding to the 'OPTIMIZE' + * one so the code only has to hack on the pixels that require + * composition. + */ + mode = PNG_ALPHA_OPTIMIZED; + } + } + + else /* output needs an alpha channel */ + { + /* This is tricky because it happens before the swap operation has + * been accomplished; however, the swap does *not* swap the added + * alpha channel (weird API), so it must be added in the correct + * place. + */ + png_uint_32 filler; /* opaque filler */ + int where; + + if (linear != 0) + filler = 65535; + + else + filler = 255; + +#ifdef PNG_FORMAT_AFIRST_SUPPORTED + if ((format & PNG_FORMAT_FLAG_AFIRST) != 0) + { + where = PNG_FILLER_BEFORE; + change &= ~PNG_FORMAT_FLAG_AFIRST; + } + + else +#endif + where = PNG_FILLER_AFTER; + + png_set_add_alpha(png_ptr, filler, where); + } + + /* This stops the (irrelevant) call to swap_alpha below. */ + change &= ~PNG_FORMAT_FLAG_ALPHA; + } + + /* Now set the alpha mode correctly; this is always done, even if there is + * no alpha channel in either the input or the output because it correctly + * sets the output gamma. + */ + png_set_alpha_mode_fixed(png_ptr, mode, output_gamma); + +# ifdef PNG_FORMAT_BGR_SUPPORTED + if ((change & PNG_FORMAT_FLAG_BGR) != 0) + { + /* Check only the output format; PNG is never BGR; don't do this if + * the output is gray, but fix up the 'format' value in that case. + */ + if ((format & PNG_FORMAT_FLAG_COLOR) != 0) + png_set_bgr(png_ptr); + + else + format &= ~PNG_FORMAT_FLAG_BGR; + + change &= ~PNG_FORMAT_FLAG_BGR; + } +# endif + +# ifdef PNG_FORMAT_AFIRST_SUPPORTED + if ((change & PNG_FORMAT_FLAG_AFIRST) != 0) + { + /* Only relevant if there is an alpha channel - it's particularly + * important to handle this correctly because do_local_compose may + * be set above and then libpng will keep the alpha channel for this + * code to remove. + */ + if ((format & PNG_FORMAT_FLAG_ALPHA) != 0) + { + /* Disable this if doing a local background, + * TODO: remove this when local background is no longer required. + */ + if (do_local_background != 2) + png_set_swap_alpha(png_ptr); + } + + else + format &= ~PNG_FORMAT_FLAG_AFIRST; + + change &= ~PNG_FORMAT_FLAG_AFIRST; + } +# endif + + /* If the *output* is 16-bit then we need to check for a byte-swap on this + * architecture. + */ + if (linear != 0) + { + PNG_CONST png_uint_16 le = 0x0001; + + if ((*(png_const_bytep) & le) != 0) + png_set_swap(png_ptr); + } + + /* If change is not now 0 some transformation is missing - error out. */ + if (change != 0) + png_error(png_ptr, "png_read_image: unsupported transformation"); + } + + PNG_SKIP_CHUNKS(png_ptr); + + /* Update the 'info' structure and make sure the result is as required; first + * make sure to turn on the interlace handling if it will be required + * (because it can't be turned on *after* the call to png_read_update_info!) + * + * TODO: remove the do_local_background fixup below. + */ + if (do_local_compose == 0 && do_local_background != 2) + passes = png_set_interlace_handling(png_ptr); + + png_read_update_info(png_ptr, info_ptr); + + { + png_uint_32 info_format = 0; + + if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) + info_format |= PNG_FORMAT_FLAG_COLOR; + + if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) + { + /* do_local_compose removes this channel below. */ + if (do_local_compose == 0) + { + /* do_local_background does the same if required. */ + if (do_local_background != 2 || + (format & PNG_FORMAT_FLAG_ALPHA) != 0) + info_format |= PNG_FORMAT_FLAG_ALPHA; + } + } + + else if (do_local_compose != 0) /* internal error */ + png_error(png_ptr, "png_image_read: alpha channel lost"); + + if (info_ptr->bit_depth == 16) + info_format |= PNG_FORMAT_FLAG_LINEAR; + +#ifdef PNG_FORMAT_BGR_SUPPORTED + if ((png_ptr->transformations & PNG_BGR) != 0) + info_format |= PNG_FORMAT_FLAG_BGR; +#endif + +#ifdef PNG_FORMAT_AFIRST_SUPPORTED + if (do_local_background == 2) + { + if ((format & PNG_FORMAT_FLAG_AFIRST) != 0) + info_format |= PNG_FORMAT_FLAG_AFIRST; + } + + if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 || + ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 && + (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0)) + { + if (do_local_background == 2) + png_error(png_ptr, "unexpected alpha swap transformation"); + + info_format |= PNG_FORMAT_FLAG_AFIRST; + } +# endif + + /* This is actually an internal error. */ + if (info_format != format) + png_error(png_ptr, "png_read_image: invalid transformations"); + } + + /* Now read the rows. If do_local_compose is set then it is necessary to use + * a local row buffer. The output will be GA, RGBA or BGRA and must be + * converted to G, RGB or BGR as appropriate. The 'local_row' member of the + * display acts as a flag. + */ + { + png_voidp first_row = display->buffer; + ptrdiff_t row_bytes = display->row_stride; + + if (linear != 0) + row_bytes *= 2; + + /* The following expression is designed to work correctly whether it gives + * a signed or an unsigned result. + */ + if (row_bytes < 0) + { + char *ptr = png_voidcast(char*, first_row); + ptr += (image->height-1) * (-row_bytes); + first_row = png_voidcast(png_voidp, ptr); + } + + display->first_row = first_row; + display->row_bytes = row_bytes; + } + + if (do_local_compose != 0) + { + int result; + png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); + + display->local_row = row; + result = png_safe_execute(image, png_image_read_composite, display); + display->local_row = NULL; + png_free(png_ptr, row); + + return result; + } + + else if (do_local_background == 2) + { + int result; + png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); + + display->local_row = row; + result = png_safe_execute(image, png_image_read_background, display); + display->local_row = NULL; + png_free(png_ptr, row); + + return result; + } + + else + { + png_alloc_size_t row_bytes = display->row_bytes; + + while (--passes >= 0) + { + png_uint_32 y = image->height; + png_bytep row = png_voidcast(png_bytep, display->first_row); + + while (y-- > 0) + { + png_read_row(png_ptr, row, NULL); + row += row_bytes; + } + } + + return 1; + } +} + +int PNGAPI +png_image_finish_read(png_imagep image, png_const_colorp background, + void *buffer, png_int_32 row_stride, void *colormap) +{ + if (image != NULL && image->version == PNG_IMAGE_VERSION) + { + /* Check for row_stride overflow. This check is not performed on the + * original PNG format because it may not occur in the output PNG format + * and libpng deals with the issues of reading the original. + */ + const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format); + + if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */ + { + png_uint_32 check; + const png_uint_32 png_row_stride = image->width * channels; + + if (row_stride == 0) + row_stride = (png_int_32)/*SAFE*/png_row_stride; + + if (row_stride < 0) + check = -row_stride; + + else + check = row_stride; + + if (image->opaque != NULL && buffer != NULL && check >= png_row_stride) + { + /* Now check for overflow of the image buffer calculation; this + * limits the whole image size to 32 bits for API compatibility with + * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro. + */ + if (image->height <= 0xFFFFFFFF/png_row_stride) + { + if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 || + (image->colormap_entries > 0 && colormap != NULL)) + { + int result; + png_image_read_control display; + + memset(&display, 0, (sizeof display)); + display.image = image; + display.buffer = buffer; + display.row_stride = row_stride; + display.colormap = colormap; + display.background = background; + display.local_row = NULL; + + /* Choose the correct 'end' routine; for the color-map case + * all the setup has already been done. + */ + if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0) + result = png_safe_execute(image, + png_image_read_colormap, &display) && + png_safe_execute(image, + png_image_read_colormapped, &display); + + else + result = + png_safe_execute(image, + png_image_read_direct, &display); + + png_image_free(image); + return result; + } + + else + return png_image_error(image, + "png_image_finish_read[color-map]: no color-map"); + } + + else + return png_image_error(image, + "png_image_finish_read: image too large"); + } + + else + return png_image_error(image, + "png_image_finish_read: invalid argument"); + } + + else + return png_image_error(image, + "png_image_finish_read: row_stride too large"); + } + + else if (image != NULL) + return png_image_error(image, + "png_image_finish_read: damaged PNG_IMAGE_VERSION"); + + return 0; +} + +#endif /* SIMPLIFIED_READ */ +#endif /* READ */ |