134 lines
3.6 KiB
C
134 lines
3.6 KiB
C
//
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// webpinfo.c: acquire information about WebP files in JSON format
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//
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// Copyright (c) 2021, Přemysl Eric Janouch <p@janouch.name>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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//
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#include "info.h"
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#include <jv.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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// --- WebP --------------------------------------------------------------------
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// https://github.com/webmproject/libwebp/blob/master/doc/webp-container-spec.txt
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// https://github.com/webmproject/libwebp/blob/master/doc/webp-lossless-bitstream-spec.txt
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// https://datatracker.ietf.org/doc/html/rfc6386
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//
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// Pretty versions, hopefully not outdated:
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// https://developers.google.com/speed/webp/docs/riff_container
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// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification
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static jv
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parse_webp(jv o, const uint8_t *p, size_t len)
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{
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// libwebp won't let us simply iterate over all chunks, so handroll it.
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if (len < 12 || memcmp(p, "RIFF", 4) || memcmp(p + 8, "WEBP", 4))
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return add_error(o, "not a WEBP file");
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// TODO(p): This can still be parseable.
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// TODO(p): Warn on trailing data.
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uint32_t size = u32le(p + 4);
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if (8 + size < len)
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return add_error(o, "truncated file");
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const uint8_t *end = p + 8 + size;
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p += 12;
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jv chunks = jv_array();
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while (p < end) {
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if (end - p < 8) {
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o = add_warning(o, "framing mismatch");
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printf("%ld", end - p);
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break;
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}
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uint32_t chunk_size = u32le(p + 4);
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uint32_t chunk_advance = (chunk_size + 1) & ~1;
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if (p + 8 + chunk_advance > end) {
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o = add_warning(o, "runaway chunk payload");
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break;
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}
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char fourcc[5] = "";
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memcpy(fourcc, p, 4);
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chunks = jv_array_append(chunks, jv_string(fourcc));
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p += 8;
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// TODO(p): Decode VP8 and VP8L chunk metadata.
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if (!strcmp(fourcc, "EXIF"))
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o = parse_exif(o, p, chunk_size);
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if (!strcmp(fourcc, "ICCP"))
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o = parse_icc(o, p, chunk_size);
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p += chunk_advance;
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}
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return jv_set(o, jv_string("chunks"), chunks);
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}
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// --- I/O ---------------------------------------------------------------------
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static jv
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do_file(const char *filename, jv o)
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{
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const char *err = NULL;
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FILE *fp = fopen(filename, "rb");
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if (!fp) {
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err = strerror(errno);
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goto error;
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}
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uint8_t *data = NULL, buf[256 << 10];
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size_t n, len = 0;
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while ((n = fread(buf, sizeof *buf, sizeof buf / sizeof *buf, fp))) {
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data = realloc(data, len + n);
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memcpy(data + len, buf, n);
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len += n;
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}
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if (ferror(fp)) {
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err = strerror(errno);
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goto error_read;
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}
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o = parse_webp(o, data, len);
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error_read:
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fclose(fp);
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free(data);
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error:
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if (err)
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o = add_error(o, err);
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return o;
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}
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int
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main(int argc, char *argv[])
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{
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(void) parse_psir;
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// XXX: Can't use `xargs -P0`, there's a risk of non-atomic writes.
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// Usage: find . -iname *.png -print0 | xargs -0 ./pnginfo
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for (int i = 1; i < argc; i++) {
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const char *filename = argv[i];
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jv o = jv_object();
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o = jv_object_set(o, jv_string("filename"), jv_string(filename));
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o = do_file(filename, o);
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jv_dumpf(o, stdout, 0 /* Might consider JV_PRINT_SORTED. */);
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fputc('\n', stdout);
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}
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return 0;
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}
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