diff options
Diffstat (limited to 'lisiblepng/src/lisiblepng.c')
| -rw-r--r-- | lisiblepng/src/lisiblepng.c | 334 |
1 files changed, 334 insertions, 0 deletions
diff --git a/lisiblepng/src/lisiblepng.c b/lisiblepng/src/lisiblepng.c new file mode 100644 index 0000000..3dfda24 --- /dev/null +++ b/lisiblepng/src/lisiblepng.c @@ -0,0 +1,334 @@ +#include "lisiblepng.h" +#include "assert.h" +#include "deflate.h" +#include "log.h" +#include <errno.h> +#include <stdbool.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#define PNG_SIGNATURE_LENGTH 8 +const uint8_t PNG_SIGNATURE[PNG_SIGNATURE_LENGTH] = {0x89, 0x50, 0x4E, 0x47, + 0x0D, 0x0A, 0x1A, 0x0A}; +#define IHDR_CHUNK_TYPE 0x49484452 +#define IEND_CHUNK_TYPE 0x49454e44 +#define IDAT_CHUNK_TYPE 0x49444154 + +const uint32_t CRC32_TABLE[256] = { + 0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, + 0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, + 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2, + 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, + 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, + 0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, + 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C, + 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, + 0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, + 0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, + 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106, + 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433, + 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, + 0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, + 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950, + 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, + 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, + 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, + 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA, + 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F, + 0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, + 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, + 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84, + 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, + 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, + 0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, + 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E, + 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, + 0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, + 0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, + 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28, + 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, + 0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, + 0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, + 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242, + 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, + 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, + 0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, + 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC, + 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, + 0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, + 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, + 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D}; + +struct Png { + const uint8_t *data; +}; + +typedef struct { + FILE *stream; +#ifdef LISIBLE_PNG_COMPUTE_CRC + uint32_t computed_crc; +#endif // LISIBLE_PNG_COMPUTE_CRC +} DeflateDecompressor; + +void DeflateDecompressor_init(DeflateDecompressor *ctx, FILE *stream) { + ASSERT(ctx != NULL); + ASSERT(stream != NULL); + ctx->stream = stream; +} + +void ParsingContext_crc_reset(DeflateDecompressor *ctx) { + ASSERT(ctx != NULL); +#ifdef LISIBLE_PNG_COMPUTE_CRC + ctx->computed_crc = 0xFFFFFFFFu; +#endif // LISIBLE_PNG_COMPUTE_CRC +} + +#ifdef LISIBLE_PNG_COMPUTE_CRC +uint32_t ParsingContext_computed_crc(DeflateDecompressor *ctx) { + ASSERT(ctx != NULL); + return ctx->computed_crc ^ 0xFFFFFFFFu; +} +#endif // LISIBLE_PNG_COMPUTE_CRC + +long ParsingContext_cursor_position(DeflateDecompressor *ctx) { + ASSERT(ctx != NULL); + return ftell(ctx->stream); +} + +bool ParsingContext_skip_bytes(DeflateDecompressor *ctx, size_t byte_count) { + ASSERT(ctx != NULL); + if (fseek(ctx->stream, byte_count, SEEK_CUR) != 0) { + LOGN("Couldn't skip bytes: %s", strerror(errno)); + return false; + } + + return true; +} + +bool ParsingContext_parse_bytes(DeflateDecompressor *ctx, size_t byte_count, + uint8_t *output_buffer) { + ASSERT(ctx != NULL); + ASSERT(output_buffer != NULL); + if (fread(output_buffer, 1, byte_count, ctx->stream) < byte_count) { + LOG0("Couldn't parse bytes, EOF reached"); + return false; + } + +#ifdef LISIBLE_PNG_COMPUTE_CRC + for (size_t i = 0; i < byte_count; i++) { + const uint32_t index = (ctx->computed_crc ^ output_buffer[i]) & 0xFF; + ctx->computed_crc = (ctx->computed_crc >> 8) ^ CRC32_TABLE[index]; + } +#endif // LISIBLE_PNG_COMPUTE_CRC + + return true; +} + +bool ParsingContext_parse_uint32_t(DeflateDecompressor *ctx, + uint32_t *output_u32) { + ASSERT(ctx != NULL); + ASSERT(output_u32 != NULL); + uint8_t bytes[4]; + if (!ParsingContext_parse_bytes(ctx, 4, bytes)) { + return false; + } + *output_u32 = + (bytes[0] << 24) + (bytes[1] << 16) + (bytes[2] << 8) + bytes[3]; + return true; +} + +bool ParsingContext_parse_uint8_t(DeflateDecompressor *ctx, + uint8_t *output_u8) { + ASSERT(ctx != NULL); + ASSERT(output_u8 != NULL); + if (!ParsingContext_parse_bytes(ctx, 1, output_u8)) { + return false; + } + return true; +} + +bool matches_png_signature(uint8_t signature[PNG_SIGNATURE_LENGTH]) { + return memcmp(signature, PNG_SIGNATURE, PNG_SIGNATURE_LENGTH) == 0; +} + +#define PARSE_FIELD(type, field) \ + do { \ + if (!ParsingContext_parse_##type(ctx, &field)) { \ + return false; \ + } \ + } while (0) + +typedef struct { + uint32_t width; + uint32_t height; + uint8_t bit_depth; + uint8_t colour_type; + uint8_t compression_method; + uint8_t filter_method; + uint8_t interlace_method; +} ImageHeader; + +typedef struct { + size_t length; + uint8_t *data; +} ImageData; + +void ImageHeader_print_image_header(const ImageHeader *image_header) { + ASSERT(image_header != NULL); + LOGN("Image header:\n" + "- dimensions: %dx%d\n" + "- bit depth: %d\n" + "- colour type: %d\n" + "- compression method: %d\n" + "- filter method: %d\n" + "- interlace method: %d", + image_header->width, image_header->height, image_header->bit_depth, + image_header->colour_type, image_header->compression_method, + image_header->filter_method, image_header->interlace_method); +} + +bool ParsingContext_validate_crc_if_required(DeflateDecompressor *ctx) { +#ifdef LISIBLE_PNG_COMPUTE_CRC + uint32_t computed_crc = ParsingContext_computed_crc(ctx); + uint32_t crc; + PARSE_FIELD(uint32_t, crc); + if (computed_crc != crc) { + LOG0("Invalid CRC checksum"); + return false; + } +#else + ParsingContext_skip_bytes(ctx, sizeof(uint32_t)); +#endif + + return true; +} + +bool parse_IHDR_chunk(DeflateDecompressor *ctx, ImageHeader *image_header) { + ASSERT(ctx != NULL); + ASSERT(image_header != NULL); + + uint32_t length; + PARSE_FIELD(uint32_t, length); + + ParsingContext_crc_reset(ctx); + + uint32_t type; + PARSE_FIELD(uint32_t, type); + if (type != IHDR_CHUNK_TYPE) { + LOG0("Expected IHDR chunk"); + return false; + } + + long data_start = ParsingContext_cursor_position(ctx); + PARSE_FIELD(uint32_t, image_header->width); + PARSE_FIELD(uint32_t, image_header->height); + PARSE_FIELD(uint8_t, image_header->bit_depth); + PARSE_FIELD(uint8_t, image_header->colour_type); + PARSE_FIELD(uint8_t, image_header->compression_method); + PARSE_FIELD(uint8_t, image_header->filter_method); + PARSE_FIELD(uint8_t, image_header->interlace_method); + long read_data_length = ParsingContext_cursor_position(ctx) - data_start; + ASSERT(read_data_length == length); + + if (!ParsingContext_validate_crc_if_required(ctx)) { + return false; + } + + return true; +} + +bool parse_IDAT_chunk(DeflateDecompressor *ctx, uint32_t data_length, + ImageData *image_data) { + ASSERT(ctx != NULL); + ASSERT(image_data != NULL); + + image_data->data = realloc(image_data->data, data_length); + ParsingContext_parse_bytes(ctx, data_length, + &image_data->data[image_data->length]); + image_data->length = data_length; + + if (!ParsingContext_validate_crc_if_required(ctx)) { + return false; + } + + return true; +} + +uint32_t uint32_t_to_le(uint32_t value) { + char *value_bytes = (char *)&value; + return (value_bytes[0] << 24) + (value_bytes[1] << 16) + + (value_bytes[2] << 8) + value_bytes[3]; +} + +Png *lis_Png_parse(FILE *stream) { + Png *png = malloc(sizeof(Png)); + DeflateDecompressor ctx; + + DeflateDecompressor_init(&ctx, stream); + uint8_t parsed_png_signature[PNG_SIGNATURE_LENGTH]; + if (!ParsingContext_parse_bytes(&ctx, PNG_SIGNATURE_LENGTH, + parsed_png_signature)) { + LOG0("Couldn't parse signature"); + goto err; + } + + if (!matches_png_signature(parsed_png_signature)) { + LOG0("Invalid signature"); + goto err; + } + + ImageHeader header; + if (!parse_IHDR_chunk(&ctx, &header)) { + goto err; + } + ImageHeader_print_image_header(&header); + + ImageData image_data = {0}; + bool end_reached = false; + while (!end_reached) { + uint32_t length; + if (!ParsingContext_parse_uint32_t(&ctx, &length)) { + LOG0("Couldn't parse chunk length"); + goto cleanup_data; + } + + ParsingContext_crc_reset(&ctx); + uint32_t type; + if (!ParsingContext_parse_uint32_t(&ctx, &type)) { + LOG0("Couldn't parse chunk type"); + goto cleanup_data; + } + + uint32_t type_le = uint32_t_to_le(type); + LOGN("Parsing %.4s chunk", (char *)&type_le); + switch (type) { + case IDAT_CHUNK_TYPE: + parse_IDAT_chunk(&ctx, length, &image_data); + break; + case IEND_CHUNK_TYPE: + end_reached = true; + ParsingContext_skip_bytes(&ctx, sizeof(uint32_t)); + break; + default: + LOG0("Unknown chunk type, skipping chunk..."); + ParsingContext_skip_bytes(&ctx, length + sizeof(uint32_t)); + break; + } + } + + LOGN("Data length: %zul", image_data.length); + zlib_decompress(image_data.data, image_data.length); + + return png; + +cleanup_data: + free(image_data.data); +err: + return NULL; +} + +#undef PARSE_FIELD +void lis_Png_destroy(Png *png) { free(png); } +void lis_Png_dump_ppm(const Png *png) { ASSERT(png != NULL); } |