Added own exif tag handling in files exif.[ch]

1 files changed, 131 insertions, 0 deletions

diff --git a/exif.c b/exif.c
new file mode 100644
index 0000000..4703a66
--- /dev/null
+++ b/exif.c
@@ -0,0 +1,131 @@
+/* sxiv: exif.c
+ * Copyright (c) 2011 Bert Muennich <be.muennich at googlemail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#define _POSIX_C_SOURCE 200112L
+
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "exif.h"
+#include "util.h"
+
+ssize_t s_read(int fd, const char *fn, void *buf, size_t n) {
+	ssize_t ret;
+
+	ret = read(fd, buf, n);
+	if (ret < n) {
+		warn("unexpected end-of-file: %s", fn);
+		return -1;
+	} else {
+		return ret;
+	}
+}
+
+unsigned short btous(unsigned char *buf, byteorder_t order) {
+	if (buf == NULL)
+		return 0;
+	if (order == BO_BIG_ENDIAN)
+		return buf[0] << 8 | buf[1];
+	else
+		return buf[1] << 8 | buf[0];
+}
+
+unsigned int btoui(unsigned char *buf, byteorder_t order) {
+	if (buf == NULL)
+		return 0;
+	if (order == BO_BIG_ENDIAN)
+		return buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
+	else
+		return buf[3] << 24 | buf[2] << 16 | buf[1] << 8 | buf[0];
+}
+
+int exif_orientation(const fileinfo_t *file) {
+	int fd;
+	unsigned char data[EXIF_MAX_LEN];
+	byteorder_t order = BO_BIG_ENDIAN;
+	unsigned int cnt, len, idx, val;
+
+	if (file == NULL || file->path == NULL)
+		return -1;
+
+	fd = open(file->path, O_RDONLY);
+	if (fd < 0)
+		return -1;
+
+	if (s_read(fd, file->name, data, 4) < 0)
+		goto abort;
+	if (btous(data, order) != JPEG_MARKER_SOI)
+		goto abort;
+	if (btous(data + 2, order) != JPEG_MARKER_APP1)
+		goto abort;
+
+	if (s_read(fd, file->name, data, 2) < 0)
+		goto abort;
+	len = btous(data, order);
+	if (len < 8)
+		goto abort;
+
+	if (s_read(fd, file->name, data, 6) < 0)
+		goto abort;
+	if (btoui(data, order) != EXIF_HEAD)
+		goto abort;
+
+	len -= 8;
+	if (len < 12 || len > EXIF_MAX_LEN)
+		goto abort;
+	if (s_read(fd, file->name, data, len) < 0)
+		goto abort;
+
+	switch (btous(data, order)) {
+		case EXIF_BO_BIG_ENDIAN:
+			order = BO_BIG_ENDIAN;
+			break;
+		case EXIF_BO_LITTLE_ENDIAN:
+			order = BO_LITTLE_ENDIAN;
+			break;
+		default:
+			goto abort;
+			break;
+	}
+
+	if (btous(data + 2, order) != EXIF_TAG_MARK)
+		goto abort;
+	idx = btoui(data + 4, order);
+	if (idx > len - 2)
+		goto abort;
+
+	val = 0;
+	cnt = btous(data + idx, order);
+
+	for (idx += 2; cnt > 0 && idx < len - 12; cnt--, idx += 12) {
+		if (btous(data + idx, order) == EXIF_TAG_ORIENTATION) {
+			val = btous(data + idx + 8, order);
+			printf("exif orientation: %s: %u\n", file->name, val);
+			break;
+		}
+	}
+
+	close(fd);
+	return val;
+
+abort:
+	close(fd);
+	return -1;
+}