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Diffstat (limited to '')
| -rw-r--r-- | bin/pngo.c | 419 |
1 files changed, 419 insertions, 0 deletions
diff --git a/bin/pngo.c b/bin/pngo.c new file mode 100644 index 00000000..88a65de6 --- /dev/null +++ b/bin/pngo.c @@ -0,0 +1,419 @@ +/* Copyright (c) 2018, June McEnroe <programble@gmail.com> + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU Affero General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <arpa/inet.h> +#include <assert.h> +#include <ctype.h> +#include <err.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sysexits.h> +#include <zlib.h> + +#define PACKED __attribute__((packed)) + +#define CRC_INIT (crc32(0, Z_NULL, 0)) + +static void readExpect( + const char *path, FILE *file, + void *ptr, size_t size, + const char *expect +) { + fread(ptr, size, 1, file); + if (ferror(file)) err(EX_IOERR, "%s", path); + if (feof(file)) errx(EX_DATAERR, "%s: missing %s", path, expect); +} + +static const uint8_t SIGNATURE[8] = { + 0x89, 'P', 'N', 'G', '\r', '\n', 0x1A, '\n' +}; + +static void readSignature(const char *path, FILE *file) { + uint8_t signature[8]; + readExpect(path, file, signature, 8, "signature"); + if (memcmp(signature, SIGNATURE, 8)) { + errx(EX_DATAERR, "%s: invalid signature", path); + } +} + +struct PACKED Chunk { + uint32_t size; + char type[4]; +}; + +static const char *typeStr(const struct Chunk *chunk) { + static char buf[5]; + memcpy(buf, chunk->type, 4); + return buf; +} + +static struct Chunk readChunk(const char *path, FILE *file) { + struct Chunk chunk; + readExpect(path, file, &chunk, sizeof(chunk), "chunk"); + chunk.size = ntohl(chunk.size); + return chunk; +} + +static void readCrc(const char *path, FILE *file, uint32_t expected) { + uint32_t found; + readExpect(path, file, &found, sizeof(found), "CRC32"); + if (ntohl(found) != expected) { + errx( + EX_DATAERR, "%s: expected CRC32 %08x, found %08x", + path, expected, found + ); + } +} + +struct PACKED Header { + uint32_t width; + uint32_t height; + uint8_t depth; + enum PACKED { + GRAYSCALE = 0, + TRUECOLOR = 2, + INDEXED = 3, + GRAYSCALE_ALPHA = 4, + TRUECOLOR_ALPHA = 6, + } color; + uint8_t compression; + uint8_t filter; + uint8_t interlace; +}; + +static struct Header readHeader(const char *path, FILE *file) { + struct Chunk ihdr = readChunk(path, file); + if (memcmp(ihdr.type, "IHDR", 4)) { + errx(EX_DATAERR, "%s: expected IHDR, found %s", path, typeStr(&ihdr)); + } + if (ihdr.size != sizeof(struct Header)) { + errx( + EX_DATAERR, "%s: expected IHDR size %zu, found %u", + path, sizeof(struct Header), ihdr.size + ); + } + uint32_t crc = crc32(CRC_INIT, (Bytef *)ihdr.type, sizeof(ihdr.type)); + + struct Header header; + readExpect(path, file, &header, sizeof(header), "IHDR data"); + readCrc(path, file, crc32(crc, (Bytef *)&header, sizeof(header))); + + header.width = ntohl(header.width); + header.height = ntohl(header.height); + + if (!header.width) errx(EX_DATAERR, "%s: invalid width 0", path); + if (!header.height) errx(EX_DATAERR, "%s: invalid height 0", path); + if ( + header.depth != 1 + && header.depth != 2 + && header.depth != 4 + && header.depth != 8 + && header.depth != 16 + ) errx(EX_DATAERR, "%s: invalid bit depth %hhu", path, header.depth); + if ( + header.color != GRAYSCALE + && header.color != TRUECOLOR + && header.color != INDEXED + && header.color != GRAYSCALE_ALPHA + && header.color != TRUECOLOR_ALPHA + ) errx(EX_DATAERR, "%s: invalid color type %hhu", path, header.color); + if (header.compression) { + errx( + EX_DATAERR, "%s: invalid compression method %hhu", + path, header.compression + ); + } + if (header.filter) { + errx(EX_DATAERR, "%s: invalid filter method %hhu", path, header.filter); + } + if (header.interlace > 1) { + errx(EX_DATAERR, "%s: invalid interlace method %hhu", path, header.interlace); + } + + return header; +} + +struct Data { + size_t size; + uint8_t *ptr; +}; + +static struct Data readData(const char *path, FILE *file, struct Chunk idat) { + uint32_t crc = crc32(CRC_INIT, (Bytef *)idat.type, sizeof(idat.type)); + + uint8_t deflate[idat.size]; + readExpect(path, file, deflate, sizeof(deflate), "image data"); + readCrc(path, file, crc32(crc, deflate, sizeof(deflate))); + + z_stream stream = { .next_in = deflate, .avail_in = sizeof(deflate) }; + int error = inflateInit(&stream); + if (error != Z_OK) errx(EX_SOFTWARE, "%s: inflateInit: %s", path, stream.msg); + + // "More typical zlib compression ratios are on the order of 2:1 to 5:1." + // <https://www.zlib.net/zlib_tech.html> + // FIXME: Compression ratio in PNG is usually much higher. + struct Data data = { .size = idat.size * 5 }; + data.ptr = malloc(data.size); + if (!data.ptr) err(EX_OSERR, "malloc(%zu)", data.size); + + for (;;) { + stream.next_out = data.ptr + stream.total_out; + stream.avail_out = data.size - stream.total_out; + + int status = inflate(&stream, Z_SYNC_FLUSH); + if (status == Z_STREAM_END) break; + if (status != Z_OK) errx(EX_DATAERR, "%s: inflate: %s", path, stream.msg); + + fprintf(stderr, "realloc %zu -> %zu\n", data.size, data.size * 2); // FIXME + data.ptr = realloc(data.ptr, data.size *= 2); + if (!data.ptr) err(EX_OSERR, "realloc(%zu)", data.size); + } + + data.size = stream.total_out; + fprintf(stderr, "total_out = %zu\n", data.size); // FIXME + fprintf(stderr, "ratio = %zu\n", data.size / idat.size); // FIXME + return data; +} + +enum PACKED FilterType { + FILT_NONE, + FILT_SUB, + FILT_UP, + FILT_AVERAGE, + FILT_PAETH, +}; + +static uint8_t paethPredictor(uint8_t a, uint8_t b, uint8_t c) { + int32_t p = (int32_t)a + (int32_t)b - (int32_t)c; + int32_t pa = labs(p - (int32_t)a); + int32_t pb = labs(p - (int32_t)b); + int32_t pc = labs(p - (int32_t)c); + if (pa <= pb && pa <= pc) return a; + if (pb < pc) return b; + return c; +} + +static uint8_t recon( + enum FilterType type, + uint8_t x, uint8_t a, uint8_t b, uint8_t c +) { + switch (type) { + case FILT_NONE: return x; + case FILT_SUB: return x + a; + case FILT_UP: return x + b; + case FILT_AVERAGE: return x + ((uint32_t)a + (uint32_t)b) / 2; + case FILT_PAETH: return x + paethPredictor(a, b, c); + } +} + +static uint8_t filt( + enum FilterType type, + uint8_t x, uint8_t a, uint8_t b, uint8_t c +) { + switch (type) { + case FILT_NONE: return x; + case FILT_SUB: return x - a; + case FILT_UP: return x - b; + case FILT_AVERAGE: return x - ((uint32_t)a + (uint32_t)b) / 2; + case FILT_PAETH: return x - paethPredictor(a, b, c); + } +} + +struct Scanline { + enum FilterType *type; + uint8_t *ptr; +}; + +static void reconData(const char *path, struct Header header, struct Data data) { + uint8_t bytes = 3; // TODO + + size_t size = bytes * header.width * header.height; + if (data.size < size) { + errx( + EX_DATAERR, "%s: expected data size %zu, found %zu", + path, size, data.size + ); + } + + struct Scanline lines[header.height]; + uint32_t stride = 1 + bytes * header.width; + for (uint32_t y = 0; y < header.height; ++y) { + lines[y].type = &data.ptr[y * stride]; + lines[y].ptr = &data.ptr[y * stride + 1]; + if (*lines[y].type > FILT_PAETH) { + errx(EX_DATAERR, "%s: invalid filter type %hhu", path, *lines[y].type); + } + } + + for (uint32_t y = 0; y < header.height; ++y) { + for (uint32_t x = 0; x < header.width; ++x) { + for (uint8_t i = 0; i < bytes; ++i) { + lines[y].ptr[x * bytes + i] = recon( + *lines[y].type, + lines[y].ptr[x * bytes + i], + x ? lines[y].ptr[(x - 1) * bytes + i] : 0, + y ? lines[y - 1].ptr[x * bytes + i] : 0, + (x && y) ? lines[y - 1].ptr[(x - 1) * bytes + i] : 0 + ); + *lines[y].type = FILT_NONE; + } + } + } +} + +static void filterData(struct Header header, struct Data data) { + uint8_t bytes = 3; // TODO + + struct Scanline lines[header.height]; + uint32_t stride = 1 + bytes * header.width; + for (uint32_t y = 0; y < header.height; ++y) { + lines[y].type = &data.ptr[y * stride]; + lines[y].ptr = &data.ptr[y * stride + 1]; + assert(*lines[y].type == FILT_NONE); + } + + for (uint32_t ry = 0; ry < header.height; ++ry) { + uint32_t y = header.height - 1 - ry; + for (uint32_t rx = 0; rx < header.width; ++rx) { + uint32_t x = header.width - 1 - rx; + for (uint8_t i = 0; i < bytes; ++i) { + // TODO: Filter type heuristic. + *lines[y].type = FILT_PAETH; + lines[y].ptr[x * bytes + i] = filt( + FILT_PAETH, + lines[y].ptr[x * bytes + i], + x ? lines[y].ptr[(x - 1) * bytes + i] : 0, + y ? lines[y - 1].ptr[x * bytes + i] : 0, + (x && y) ? lines[y - 1].ptr[(x - 1) * bytes + i] : 0 + ); + } + } + } +} + +static void writeExpect(const char *path, FILE *file, const void *ptr, size_t size) { + fwrite(ptr, size, 1, file); + if (ferror(file)) err(EX_IOERR, "%s", path); +} + +static void writeSignature(const char *path, FILE *file) { + writeExpect(path, file, SIGNATURE, sizeof(SIGNATURE)); +} + +static void writeChunk(const char *path, FILE *file, struct Chunk chunk) { + chunk.size = htonl(chunk.size); + writeExpect(path, file, &chunk, sizeof(chunk)); +} + +static void writeCrc(const char *path, FILE *file, uint32_t crc) { + uint32_t net = htonl(crc); + writeExpect(path, file, &net, sizeof(net)); +} + +static void writeHeader(const char *path, FILE *file, struct Header header) { + struct Chunk ihdr = { .size = sizeof(header), .type = { 'I', 'H', 'D', 'R' } }; + writeChunk(path, file, ihdr); + uint32_t crc = crc32(CRC_INIT, (Bytef *)ihdr.type, sizeof(ihdr.type)); + header.width = htonl(header.width); + header.height = htonl(header.height); + writeExpect(path, file, &header, sizeof(header)); + writeCrc(path, file, crc32(crc, (Bytef *)&header, sizeof(header))); +} + +static void writeData(const char *path, FILE *file, struct Data data) { + size_t bound = compressBound(data.size); + uint8_t deflate[bound]; + int error = compress2(deflate, &bound, data.ptr, data.size, Z_BEST_COMPRESSION); + if (error != Z_OK) errx(EX_SOFTWARE, "%s: compress2: %d", path, error); + + struct Chunk idat = { .size = bound, .type = { 'I', 'D', 'A', 'T' } }; + writeChunk(path, file, idat); + uint32_t crc = crc32(CRC_INIT, (Bytef *)idat.type, sizeof(idat.type)); + writeExpect(path, file, deflate, bound); + writeCrc(path, file, crc32(crc, deflate, bound)); +} + +static void writeEnd(const char *path, FILE *file) { + struct Chunk iend = { .size = 0, .type = { 'I', 'E', 'N', 'D' } }; + writeChunk(path, file, iend); + writeCrc(path, file, crc32(CRC_INIT, (Bytef *)iend.type, sizeof(iend.type))); +} + +int main(int argc, char *argv[]) { + const char *path = "stdin"; + FILE *file = stdin; + if (argc > 1) { + path = argv[1]; + file = fopen(path, "r"); + if (!file) err(EX_NOINPUT, "%s", path); + } + + readSignature(path, file); + struct Header header = readHeader(path, file); + if (header.color != TRUECOLOR) { + errx(EX_CONFIG, "%s: unsupported color type %u", path, header.color); + } + if (header.depth != 8) { + errx(EX_CONFIG, "%s: unsupported bit depth %hhu", path, header.depth); + } + + struct Data data = { .size = 0, .ptr = NULL }; + for (;;) { + struct Chunk chunk = readChunk(path, file); + if (!memcmp(chunk.type, "IDAT", 4)) { + if (data.size) { + errx(EX_CONFIG, "%s: unsupported multiple IDAT chunks", path); + } + data = readData(path, file, chunk); + + } else if (!memcmp(chunk.type, "IEND", 4)) { + if (!data.size) errx(EX_DATAERR, "%s: missing IDAT chunk", path); + int error = fclose(file); + if (error) err(EX_IOERR, "%s", path); + break; + + } else if (isupper(chunk.type[0])) { + errx( + EX_CONFIG, "%s: unsupported critical chunk %s", + path, typeStr(&chunk) + ); + + } else { + int error = fseek(file, chunk.size + 4, SEEK_CUR); + if (error) err(EX_IOERR, "%s", path); + } + } + + reconData(path, header, data); + + // TODO: "Optimize". + + filterData(header, data); + + // TODO: -o + path = "stdout"; + file = stdout; + + writeSignature(path, file); + writeHeader(path, file, header); + writeData(path, file, data); + writeEnd(path, file); + + int error = fclose(file); + if (error) err(EX_IOERR, "%s", path); +} |