132 lines
3 KiB
C
132 lines
3 KiB
C
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/* sxiv: exif.c
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* Copyright (c) 2011 Bert Muennich <be.muennich at googlemail.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#define _POSIX_C_SOURCE 200112L
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#include <stdlib.h>
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "exif.h"
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#include "util.h"
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ssize_t s_read(int fd, const char *fn, void *buf, size_t n) {
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ssize_t ret;
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ret = read(fd, buf, n);
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if (ret < n) {
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warn("unexpected end-of-file: %s", fn);
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return -1;
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} else {
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return ret;
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}
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}
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unsigned short btous(unsigned char *buf, byteorder_t order) {
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if (buf == NULL)
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return 0;
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if (order == BO_BIG_ENDIAN)
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return buf[0] << 8 | buf[1];
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else
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return buf[1] << 8 | buf[0];
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}
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unsigned int btoui(unsigned char *buf, byteorder_t order) {
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if (buf == NULL)
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return 0;
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if (order == BO_BIG_ENDIAN)
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return buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
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else
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return buf[3] << 24 | buf[2] << 16 | buf[1] << 8 | buf[0];
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}
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int exif_orientation(const fileinfo_t *file) {
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int fd;
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unsigned char data[EXIF_MAX_LEN];
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byteorder_t order = BO_BIG_ENDIAN;
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unsigned int cnt, len, idx, val;
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if (file == NULL || file->path == NULL)
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return -1;
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fd = open(file->path, O_RDONLY);
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if (fd < 0)
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return -1;
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if (s_read(fd, file->name, data, 4) < 0)
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goto abort;
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if (btous(data, order) != JPEG_MARKER_SOI)
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goto abort;
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if (btous(data + 2, order) != JPEG_MARKER_APP1)
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goto abort;
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if (s_read(fd, file->name, data, 2) < 0)
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goto abort;
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len = btous(data, order);
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if (len < 8)
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goto abort;
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if (s_read(fd, file->name, data, 6) < 0)
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goto abort;
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if (btoui(data, order) != EXIF_HEAD)
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goto abort;
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len -= 8;
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if (len < 12 || len > EXIF_MAX_LEN)
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goto abort;
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if (s_read(fd, file->name, data, len) < 0)
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goto abort;
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switch (btous(data, order)) {
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case EXIF_BO_BIG_ENDIAN:
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order = BO_BIG_ENDIAN;
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break;
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case EXIF_BO_LITTLE_ENDIAN:
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order = BO_LITTLE_ENDIAN;
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break;
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default:
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goto abort;
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break;
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}
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if (btous(data + 2, order) != EXIF_TAG_MARK)
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goto abort;
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idx = btoui(data + 4, order);
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if (idx > len - 2)
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goto abort;
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val = 0;
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cnt = btous(data + idx, order);
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for (idx += 2; cnt > 0 && idx < len - 12; cnt--, idx += 12) {
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if (btous(data + idx, order) == EXIF_TAG_ORIENTATION) {
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val = btous(data + idx + 8, order);
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printf("exif orientation: %s: %u\n", file->name, val);
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break;
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}
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}
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close(fd);
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return val;
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abort:
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close(fd);
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return -1;
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}
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