| 1 | /* sxiv: exif.c |
| 2 | * Copyright (c) 2012 Bert Muennich <be.muennich at googlemail.com> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify it |
| 5 | * under the terms of the GNU General Public License as published by the |
| 6 | * Free Software Foundation; either version 2 of the License, or (at your |
| 7 | * option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, but |
| 10 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | * General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License along |
| 15 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 16 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| 17 | */ |
| 18 | |
| 19 | #define _POSIX_C_SOURCE 200112L |
| 20 | |
| 21 | #include <stdlib.h> |
| 22 | #include <fcntl.h> |
| 23 | #include <sys/stat.h> |
| 24 | #include <unistd.h> |
| 25 | |
| 26 | #include "exif.h" |
| 27 | #include "util.h" |
| 28 | |
| 29 | ssize_t s_read(int fd, const char *fn, void *buf, size_t n) { |
| 30 | ssize_t ret; |
| 31 | |
| 32 | ret = read(fd, buf, n); |
| 33 | if (ret < n) { |
| 34 | warn("unexpected end-of-file: %s", fn); |
| 35 | return -1; |
| 36 | } else { |
| 37 | return ret; |
| 38 | } |
| 39 | } |
| 40 | |
| 41 | unsigned short btous(unsigned char *buf, byteorder_t order) { |
| 42 | if (buf == NULL) |
| 43 | return 0; |
| 44 | if (order == BO_BIG_ENDIAN) |
| 45 | return buf[0] << 8 | buf[1]; |
| 46 | else |
| 47 | return buf[1] << 8 | buf[0]; |
| 48 | } |
| 49 | |
| 50 | unsigned int btoui(unsigned char *buf, byteorder_t order) { |
| 51 | if (buf == NULL) |
| 52 | return 0; |
| 53 | if (order == BO_BIG_ENDIAN) |
| 54 | return buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3]; |
| 55 | else |
| 56 | return buf[3] << 24 | buf[2] << 16 | buf[1] << 8 | buf[0]; |
| 57 | } |
| 58 | |
| 59 | int exif_orientation(const fileinfo_t *file) { |
| 60 | int fd; |
| 61 | unsigned char data[EXIF_MAX_LEN]; |
| 62 | byteorder_t order = BO_BIG_ENDIAN; |
| 63 | unsigned int cnt, len, idx, val; |
| 64 | |
| 65 | if (file == NULL || file->path == NULL) |
| 66 | return -1; |
| 67 | |
| 68 | fd = open(file->path, O_RDONLY); |
| 69 | if (fd < 0) |
| 70 | return -1; |
| 71 | |
| 72 | if (s_read(fd, file->name, data, 4) < 0) |
| 73 | goto abort; |
| 74 | if (btous(data, order) != JPEG_MARKER_SOI) |
| 75 | goto abort; |
| 76 | if (btous(data + 2, order) != JPEG_MARKER_APP1) |
| 77 | goto abort; |
| 78 | |
| 79 | if (s_read(fd, file->name, data, 2) < 0) |
| 80 | goto abort; |
| 81 | len = btous(data, order); |
| 82 | if (len < 8) |
| 83 | goto abort; |
| 84 | |
| 85 | if (s_read(fd, file->name, data, 6) < 0) |
| 86 | goto abort; |
| 87 | if (btoui(data, order) != EXIF_HEAD) |
| 88 | goto abort; |
| 89 | |
| 90 | len -= 8; |
| 91 | if (len < 12 || len > EXIF_MAX_LEN) |
| 92 | goto abort; |
| 93 | if (s_read(fd, file->name, data, len) < 0) |
| 94 | goto abort; |
| 95 | |
| 96 | switch (btous(data, order)) { |
| 97 | case EXIF_BO_BIG_ENDIAN: |
| 98 | order = BO_BIG_ENDIAN; |
| 99 | break; |
| 100 | case EXIF_BO_LITTLE_ENDIAN: |
| 101 | order = BO_LITTLE_ENDIAN; |
| 102 | break; |
| 103 | default: |
| 104 | goto abort; |
| 105 | break; |
| 106 | } |
| 107 | |
| 108 | if (btous(data + 2, order) != EXIF_TAG_MARK) |
| 109 | goto abort; |
| 110 | idx = btoui(data + 4, order); |
| 111 | if (idx > len - 2) |
| 112 | goto abort; |
| 113 | |
| 114 | val = 0; |
| 115 | cnt = btous(data + idx, order); |
| 116 | |
| 117 | for (idx += 2; cnt > 0 && idx < len - 12; cnt--, idx += 12) { |
| 118 | if (btous(data + idx, order) == EXIF_TAG_ORIENTATION) { |
| 119 | val = btous(data + idx + 8, order); |
| 120 | break; |
| 121 | } |
| 122 | } |
| 123 | |
| 124 | close(fd); |
| 125 | return val; |
| 126 | |
| 127 | abort: |
| 128 | close(fd); |
| 129 | return -1; |
| 130 | } |