diff options
Diffstat (limited to 'bin/glitch.c')
| -rw-r--r-- | bin/glitch.c | 605 |
1 files changed, 605 insertions, 0 deletions
diff --git a/bin/glitch.c b/bin/glitch.c new file mode 100644 index 00000000..d0c926f9 --- /dev/null +++ b/bin/glitch.c @@ -0,0 +1,605 @@ +/* Copyright (C) 2018, 2021 June McEnroe <june@causal.agency> + * + * 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 <err.h> +#include <inttypes.h> +#include <limits.h> +#include <stdbool.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sysexits.h> +#include <unistd.h> +#include <zlib.h> + +#define ARRAY_LEN(a) (sizeof(a) / sizeof(a[0])) + +static const char *path; +static FILE *file; +static uint32_t crc; + +static void pngRead(void *ptr, size_t len, const char *desc) { + size_t n = fread(ptr, len, 1, file); + if (!n && ferror(file)) err(EX_IOERR, "%s", path); + if (!n) errx(EX_DATAERR, "%s: missing %s", path, desc); + crc = crc32(crc, ptr, len); +} + +static void pngWrite(const void *ptr, size_t len) { + size_t n = fwrite(ptr, len, 1, file); + if (!n) err(EX_IOERR, "%s", path); + crc = crc32(crc, ptr, len); +} + +static const uint8_t Sig[8] = "\x89PNG\r\n\x1A\n"; + +static void sigRead(void) { + uint8_t sig[sizeof(Sig)]; + pngRead(sig, sizeof(sig), "signature"); + if (memcmp(sig, Sig, sizeof(sig))) { + errx(EX_DATAERR, "%s: invalid signature", path); + } +} + +static void sigWrite(void) { + pngWrite(Sig, sizeof(Sig)); +} + +static uint32_t u32Read(const char *desc) { + uint8_t b[4]; + pngRead(b, sizeof(b), desc); + return (uint32_t)b[0] << 24 | (uint32_t)b[1] << 16 + | (uint32_t)b[2] << 8 | (uint32_t)b[3]; +} + +static void u32Write(uint32_t x) { + uint8_t b[4] = { x >> 24 & 0xFF, x >> 16 & 0xFF, x >> 8 & 0xFF, x & 0xFF }; + pngWrite(b, sizeof(b)); +} + +struct Chunk { + uint32_t len; + char type[5]; +}; + +static struct Chunk chunkRead(void) { + struct Chunk chunk; + chunk.len = u32Read("chunk length"); + crc = crc32(0, Z_NULL, 0); + pngRead(chunk.type, 4, "chunk type"); + chunk.type[4] = 0; + return chunk; +} + +static void chunkWrite(struct Chunk chunk) { + u32Write(chunk.len); + crc = crc32(0, Z_NULL, 0); + pngWrite(chunk.type, 4); +} + +static void crcRead(void) { + uint32_t expect = crc; + uint32_t actual = u32Read("CRC32"); + if (actual == expect) return; + errx( + EX_DATAERR, "%s: expected CRC32 %08X, found %08X", + path, expect, actual + ); +} + +static void crcWrite(void) { + u32Write(crc); +} + +static void chunkSkip(struct Chunk chunk) { + if (!(chunk.type[0] & 0x20)) { + errx(EX_CONFIG, "%s: unsupported critical chunk %s", path, chunk.type); + } + uint8_t buf[4096]; + while (chunk.len > sizeof(buf)) { + pngRead(buf, sizeof(buf), "chunk data"); + chunk.len -= sizeof(buf); + } + if (chunk.len) pngRead(buf, chunk.len, "chunk data"); + crcRead(); +} + +enum Color { + Grayscale = 0, + Truecolor = 2, + Indexed = 3, + GrayscaleAlpha = 4, + TruecolorAlpha = 6, +}; +enum Compression { + Deflate, +}; +enum FilterMethod { + Adaptive, +}; +enum Interlace { + Progressive, + Adam7, +}; + +enum { HeaderLen = 13 }; +static struct { + uint32_t width; + uint32_t height; + uint8_t depth; + uint8_t color; + uint8_t compression; + uint8_t filter; + uint8_t interlace; +} header; + +static size_t pixelLen; +static size_t lineLen; +static size_t dataLen; + +static void recalc(void) { + size_t pixelBits = header.depth; + switch (header.color) { + break; case GrayscaleAlpha: pixelBits *= 2; + break; case Truecolor: pixelBits *= 3; + break; case TruecolorAlpha: pixelBits *= 4; + } + pixelLen = (pixelBits + 7) / 8; + lineLen = (header.width * pixelBits + 7) / 8; + dataLen = (1 + lineLen) * header.height; +} + +static void headerRead(struct Chunk chunk) { + if (chunk.len != HeaderLen) { + errx( + EX_DATAERR, "%s: expected %s length %" PRIu32 ", found %" PRIu32, + path, chunk.type, (uint32_t)HeaderLen, chunk.len + ); + } + header.width = u32Read("header width"); + header.height = u32Read("header height"); + pngRead(&header.depth, 1, "header depth"); + pngRead(&header.color, 1, "header color"); + pngRead(&header.compression, 1, "header compression"); + pngRead(&header.filter, 1, "header filter"); + pngRead(&header.interlace, 1, "header interlace"); + crcRead(); + recalc(); +} + +static void headerWrite(void) { + struct Chunk ihdr = { HeaderLen, "IHDR" }; + chunkWrite(ihdr); + u32Write(header.width); + u32Write(header.height); + pngWrite(&header.depth, 1); + pngWrite(&header.color, 1); + pngWrite(&header.compression, 1); + pngWrite(&header.filter, 1); + pngWrite(&header.interlace, 1); + crcWrite(); +} + +static struct { + uint32_t len; + uint8_t rgb[256][3]; +} pal; + +static struct { + uint32_t len; + uint8_t a[256]; +} trans; + +static void palClear(void) { + pal.len = 0; + trans.len = 0; +} + +static void palRead(struct Chunk chunk) { + if (chunk.len % 3) { + errx( + EX_DATAERR, "%s: %s length %" PRIu32 " not divisible by 3", + path, chunk.type, chunk.len + ); + } + pal.len = chunk.len / 3; + if (pal.len > 256) { + errx( + EX_DATAERR, "%s: %s length %" PRIu32 " > 256", + path, chunk.type, pal.len + ); + } + pngRead(pal.rgb, chunk.len, "palette data"); + crcRead(); +} + +static void palWrite(void) { + struct Chunk plte = { 3 * pal.len, "PLTE" }; + chunkWrite(plte); + pngWrite(pal.rgb, plte.len); + crcWrite(); +} + +static void transRead(struct Chunk chunk) { + trans.len = chunk.len; + if (trans.len > 256) { + errx( + EX_DATAERR, "%s: %s length %" PRIu32 " > 256", + path, chunk.type, trans.len + ); + } + pngRead(trans.a, chunk.len, "transparency data"); + crcRead(); +} + +static void transWrite(void) { + struct Chunk trns = { trans.len, "tRNS" }; + chunkWrite(trns); + pngWrite(trans.a, trns.len); + crcWrite(); +} + +static uint8_t *data; + +static void dataAlloc(void) { + data = malloc(dataLen); + if (!data) err(EX_OSERR, "malloc"); +} + +static void dataRead(struct Chunk chunk) { + z_stream stream = { .next_out = data, .avail_out = dataLen }; + int error = inflateInit(&stream); + if (error != Z_OK) errx(EX_SOFTWARE, "inflateInit: %s", stream.msg); + + for (;;) { + if (strcmp(chunk.type, "IDAT")) { + errx(EX_DATAERR, "%s: missing IDAT chunk", path); + } + + uint8_t *idat = malloc(chunk.len); + if (!idat) err(EX_OSERR, "malloc"); + + pngRead(idat, chunk.len, "image data"); + crcRead(); + + stream.next_in = idat; + stream.avail_in = chunk.len; + error = inflate(&stream, Z_SYNC_FLUSH); + free(idat); + + if (error == Z_STREAM_END) break; + if (error != Z_OK) { + errx(EX_DATAERR, "%s: inflate: %s", path, stream.msg); + } + + chunk = chunkRead(); + } + inflateEnd(&stream); + if ((size_t)stream.total_out != dataLen) { + errx( + EX_DATAERR, "%s: expected data length %zu, found %zu", + path, dataLen, (size_t)stream.total_out + ); + } +} + +static void dataWrite(void) { + z_stream stream = { + .next_in = data, + .avail_in = dataLen, + }; + int error = deflateInit2( + &stream, Z_BEST_COMPRESSION, Z_DEFLATED, 15, 8, Z_FILTERED + ); + if (error != Z_OK) errx(EX_SOFTWARE, "deflateInit2: %s", stream.msg); + + uLong bound = deflateBound(&stream, dataLen); + uint8_t *buf = malloc(bound); + if (!buf) err(EX_OSERR, "malloc"); + + stream.next_out = buf; + stream.avail_out = bound; + deflate(&stream, Z_FINISH); + deflateEnd(&stream); + + struct Chunk idat = { stream.total_out, "IDAT" }; + chunkWrite(idat); + pngWrite(buf, stream.total_out); + crcWrite(); + free(buf); + + struct Chunk iend = { 0, "IEND" }; + chunkWrite(iend); + crcWrite(); +} + +enum Filter { + None, + Sub, + Up, + Average, + Paeth, + FilterCap, +}; + +struct Bytes { + uint8_t x, a, b, c; +}; + +static bool brokenPaeth; +static uint8_t paethPredictor(struct Bytes f) { + int32_t p = (int32_t)f.a + (int32_t)f.b - (int32_t)f.c; + int32_t pa = labs(p - (int32_t)f.a); + int32_t pb = labs(p - (int32_t)f.b); + int32_t pc = labs(p - (int32_t)f.c); + if (pa <= pb && pa <= pc) return f.a; + if (brokenPaeth) { + if (pb < pc) return f.b; + } else { + if (pb <= pc) return f.b; + } + return f.c; +} + +static uint8_t recon(enum Filter type, struct Bytes f) { + switch (type) { + case None: return f.x; + case Sub: return f.x + f.a; + case Up: return f.x + f.b; + case Average: return f.x + ((uint32_t)f.a + (uint32_t)f.b) / 2; + case Paeth: return f.x + paethPredictor(f); + default: abort(); + } +} + +static uint8_t filt(enum Filter type, struct Bytes f) { + switch (type) { + case None: return f.x; + case Sub: return f.x - f.a; + case Up: return f.x - f.b; + case Average: return f.x - ((uint32_t)f.a + (uint32_t)f.b) / 2; + case Paeth: return f.x - paethPredictor(f); + default: abort(); + } +} + +static uint8_t *lineType(uint32_t y) { + return &data[y * (1 + lineLen)]; +} +static uint8_t *lineData(uint32_t y) { + return 1 + lineType(y); +} + +static struct Bytes origBytes(uint32_t y, size_t i) { + bool a = (i >= pixelLen), b = (y > 0), c = (a && b); + return (struct Bytes) { + .x = lineData(y)[i], + .a = (a ? lineData(y)[i-pixelLen] : 0), + .b = (b ? lineData(y-1)[i] : 0), + .c = (c ? lineData(y-1)[i-pixelLen] : 0), + }; +} + +static bool reconFilter; +static void dataRecon(void) { + for (uint32_t y = 0; y < header.height; ++y) { + for (size_t i = 0; i < lineLen; ++i) { + if (reconFilter) { + lineData(y)[i] = filt(*lineType(y), origBytes(y, i)); + } else { + lineData(y)[i] = recon(*lineType(y), origBytes(y, i)); + } + } + *lineType(y) = None; + } +} + +static bool filterRecon; +static size_t applyFilter; +static enum Filter applyFilters[256]; +static size_t declFilter; +static enum Filter declFilters[256]; + +static void dataFilter(void) { + uint8_t *filter[FilterCap]; + for (enum Filter i = None; i < FilterCap; ++i) { + filter[i] = malloc(lineLen); + if (!filter[i]) err(EX_OSERR, "malloc"); + } + for (uint32_t y = header.height-1; y < header.height; --y) { + uint32_t heuristic[FilterCap] = {0}; + enum Filter minType = None; + for (enum Filter type = None; type < FilterCap; ++type) { + for (size_t i = 0; i < lineLen; ++i) { + if (filterRecon) { + filter[type][i] = recon(type, origBytes(y, i)); + } else { + filter[type][i] = filt(type, origBytes(y, i)); + } + heuristic[type] += abs((int8_t)filter[type][i]); + } + if (heuristic[type] < heuristic[minType]) minType = type; + } + if (declFilter) { + *lineType(y) = declFilters[y % declFilter]; + } else { + *lineType(y) = minType; + } + if (applyFilter) { + memcpy(lineData(y), filter[applyFilters[y % applyFilter]], lineLen); + } else { + memcpy(lineData(y), filter[minType], lineLen); + } + } + for (enum Filter i = None; i < FilterCap; ++i) { + free(filter[i]); + } +} + +static bool invertData; +static bool mirrorData; +static bool zeroX; +static bool zeroY; + +static void glitch(const char *inPath, const char *outPath) { + if (inPath) { + path = inPath; + file = fopen(path, "r"); + if (!file) err(EX_NOINPUT, "%s", path); + } else { + path = "stdin"; + file = stdin; + } + + sigRead(); + struct Chunk ihdr = chunkRead(); + if (strcmp(ihdr.type, "IHDR")) { + errx(EX_DATAERR, "%s: expected IHDR, found %s", path, ihdr.type); + } + headerRead(ihdr); + if (header.interlace != Progressive) { + errx(EX_CONFIG, "%s: unsupported interlacing", path); + } + + palClear(); + dataAlloc(); + for (;;) { + struct Chunk chunk = chunkRead(); + if (!strcmp(chunk.type, "PLTE")) { + palRead(chunk); + } else if (!strcmp(chunk.type, "tRNS")) { + transRead(chunk); + } else if (!strcmp(chunk.type, "IDAT")) { + dataRead(chunk); + } else if (!strcmp(chunk.type, "IEND")) { + break; + } else { + chunkSkip(chunk); + } + } + fclose(file); + + dataRecon(); + dataFilter(); + + if (invertData) { + for (uint32_t y = 0; y < header.height; ++y) { + for (size_t i = 0; i < lineLen; ++i) { + lineData(y)[i] ^= 0xFF; + } + } + } + if (mirrorData) { + for (uint32_t y = 0; y < header.height; ++y) { + for (size_t i = 0, j = lineLen-1; i < j; ++i, --j) { + uint8_t x = lineData(y)[i]; + lineData(y)[i] = lineData(y)[j]; + lineData(y)[j] = x; + } + } + } + if (zeroX) { + for (uint32_t y = 0; y < header.height; ++y) { + memset(lineData(y), 0, pixelLen); + } + } + if (zeroY) { + memset(lineData(0), 0, lineLen); + } + + char buf[PATH_MAX]; + if (outPath) { + path = outPath; + if (outPath == inPath) { + snprintf(buf, sizeof(buf), "%sg", outPath); + file = fopen(buf, "wx"); + if (!file) err(EX_CANTCREAT, "%s", buf); + } else { + file = fopen(path, "w"); + if (!file) err(EX_CANTCREAT, "%s", outPath); + } + } else { + path = "stdout"; + file = stdout; + } + + sigWrite(); + headerWrite(); + if (header.color == Indexed) { + palWrite(); + if (trans.len) transWrite(); + } + dataWrite(); + free(data); + int error = fclose(file); + if (error) err(EX_IOERR, "%s", path); + + if (outPath && outPath == inPath) { + error = rename(buf, outPath); + if (error) err(EX_CANTCREAT, "%s", outPath); + } +} + +static enum Filter parseFilter(const char *str) { + switch (str[0]) { + case 'N': case 'n': return None; + case 'S': case 's': return Sub; + case 'U': case 'u': return Up; + case 'A': case 'a': return Average; + case 'P': case 'p': return Paeth; + default: errx(EX_USAGE, "invalid filter type %s", str); + } +} + +static size_t parseFilters(enum Filter *filters, char *str) { + size_t len = 0; + while (str) { + char *filt = strsep(&str, ","); + filters[len++] = parseFilter(filt); + } + return len; +} + +int main(int argc, char *argv[]) { + bool stdio = false; + char *outPath = NULL; + + for (int opt; 0 < (opt = getopt(argc, argv, "a:cd:fimo:prxy"));) { + switch (opt) { + break; case 'a': applyFilter = parseFilters(applyFilters, optarg); + break; case 'c': stdio = true; + break; case 'd': declFilter = parseFilters(declFilters, optarg); + break; case 'f': reconFilter = true; + break; case 'i': invertData = true; + break; case 'm': mirrorData = true; + break; case 'o': outPath = optarg; + break; case 'p': brokenPaeth = true; + break; case 'r': filterRecon = true; + break; case 'x': zeroX = true; + break; case 'y': zeroY = true; + break; default: return EX_USAGE; + } + } + + if (optind < argc) { + for (int i = optind; i < argc; ++i) { + glitch(argv[i], (stdio ? NULL : outPath ? outPath : argv[i])); + } + } else { + glitch(NULL, outPath); + } +} |