1/* 2 * write-exif.c 3 * 4 * Placed into the public domain by Daniel Fandrich 5 * 6 * Create a new EXIF data block and write it into a JPEG image file. 7 * 8 * The JPEG image data used in this example is fixed and is guaranteed not 9 * to contain an EXIF tag block already, so it is easy to precompute where 10 * in the file the EXIF data should be. In real life, a library like 11 * libjpeg (included with the exif command-line tool source code) would 12 * be used to write to an existing JPEG file. 13 */ 14 15#include <stdio.h> 16#include <assert.h> 17#include <libexif/exif-data.h> 18 19/* this file will be unilaterally overwritten */ 20#define FILE_NAME "write-exif.jpg" 21 22/* raw JPEG image data */ 23static const unsigned char image_jpg[] = { 24 0xff, 0xd8, 0xff, 0xe0, 0x00, 0x10, 0x4a, 0x46, 0x49, 0x46, 0x00, 0x01, 25 0x01, 0x01, 0x00, 0x48, 0x00, 0x48, 0x00, 0x00, 0xff, 0xdb, 0x00, 0x43, 26 0x00, 0x14, 0x0e, 0x0f, 0x12, 0x0f, 0x0d, 0x14, 0x12, 0x10, 0x12, 0x17, 27 0x15, 0x14, 0x18, 0x1e, 0x32, 0x21, 0x1e, 0x1c, 0x1c, 0x1e, 0x3d, 0x2c, 28 0x2e, 0x24, 0x32, 0x49, 0x40, 0x4c, 0x4b, 0x47, 0x40, 0x46, 0x45, 0x50, 29 0x5a, 0x73, 0x62, 0x50, 0x55, 0x6d, 0x56, 0x45, 0x46, 0x64, 0x88, 0x65, 30 0x6d, 0x77, 0x7b, 0x81, 0x82, 0x81, 0x4e, 0x60, 0x8d, 0x97, 0x8c, 0x7d, 31 0x96, 0x73, 0x7e, 0x81, 0x7c, 0xff, 0xc0, 0x00, 0x0b, 0x08, 0x00, 0x40, 32 0x00, 0x40, 0x01, 0x01, 0x11, 0x00, 0xff, 0xc4, 0x00, 0x1b, 0x00, 0x00, 33 0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 34 0x00, 0x00, 0x00, 0x00, 0x05, 0x06, 0x04, 0x03, 0x07, 0x02, 0x01, 0xff, 35 0xc4, 0x00, 0x2f, 0x10, 0x00, 0x01, 0x03, 0x03, 0x02, 0x05, 0x03, 0x03, 36 0x03, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, 0x11, 37 0x00, 0x04, 0x05, 0x21, 0x31, 0x06, 0x12, 0x41, 0x51, 0x81, 0x61, 0x71, 38 0x91, 0x13, 0x32, 0xa1, 0x14, 0x22, 0xc1, 0x15, 0x23, 0x52, 0xd1, 0xf0, 39 0xff, 0xda, 0x00, 0x08, 0x01, 0x01, 0x00, 0x00, 0x3f, 0x00, 0xb3, 0xa2, 40 0x8a, 0x28, 0xa2, 0x8a, 0x28, 0xa2, 0x97, 0x64, 0x72, 0xd6, 0x58, 0xd4, 41 0x8f, 0xd5, 0x3d, 0xca, 0xa5, 0x7d, 0xa8, 0x4e, 0xaa, 0x3e, 0xb0, 0x3a, 42 0x7a, 0x9d, 0x2b, 0x2d, 0x87, 0x13, 0xe3, 0xaf, 0x9f, 0x0c, 0xb6, 0xb5, 43 0xb6, 0xe2, 0xb4, 0x48, 0x71, 0x30, 0x14, 0x7b, 0x02, 0x09, 0x14, 0xee, 44 0x94, 0x64, 0x38, 0x87, 0x1f, 0x8d, 0x5f, 0xd3, 0x7d, 0xe2, 0xa7, 0x46, 45 0xe8, 0x6c, 0x49, 0x1e, 0xfd, 0x07, 0xb1, 0x33, 0x5f, 0xb8, 0xdc, 0xf5, 46 0x96, 0x51, 0x7c, 0x96, 0xee, 0x14, 0xba, 0x04, 0xf2, 0x2c, 0x42, 0xa3, 47 0xd3, 0x70, 0x7c, 0x1a, 0x6d, 0x45, 0x2c, 0xcd, 0xe5, 0x11, 0x89, 0xb1, 48 0x5b, 0xc4, 0x02, 0xe1, 0xd1, 0xb4, 0xcf, 0xdc, 0xa3, 0xfc, 0x0d, 0xcd, 49 0x41, 0xde, 0xe3, 0xb2, 0x2e, 0xda, 0x1c, 0xbd, 0xe2, 0x4a, 0x90, 0xe9, 50 0x04, 0x95, 0x2b, 0xf7, 0x41, 0xd0, 0x18, 0xe8, 0x36, 0x03, 0xc6, 0x91, 51 0x4a, 0x81, 0x20, 0x82, 0x24, 0x10, 0x66, 0x45, 0x5a, 0xdd, 0xf1, 0x32, 52 0xff, 0x00, 0xa2, 0x5a, 0x8b, 0x62, 0x57, 0x7d, 0x70, 0x80, 0x93, 0x1a, 53 0x94, 0x10, 0x79, 0x4a, 0xa3, 0xb9, 0x20, 0xc0, 0xf3, 0xd3, 0x55, 0x59, 54 0x4e, 0x1c, 0x7a, 0xc7, 0x12, 0x9b, 0xc7, 0x94, 0xa7, 0x2e, 0x14, 0xa9, 55 0x74, 0x0d, 0x42, 0x01, 0x04, 0xc9, 0x3b, 0x93, 0x30, 0x09, 0xdb, 0x5f, 56 0x35, 0x9b, 0x85, 0xad, 0xde, 0x7f, 0x39, 0x6e, 0xa6, 0x82, 0xa1, 0xa5, 57 0x73, 0x2d, 0x40, 0x68, 0x13, 0x06, 0x67, 0xdf, 0x6f, 0x35, 0xe9, 0xb4, 58 0x52, 0x4c, 0xbe, 0x0c, 0x65, 0x72, 0x16, 0xcf, 0x3a, 0xff, 0x00, 0xf6, 59 0x5a, 0xd1, 0x4d, 0x11, 0xa1, 0x13, 0x26, 0x0f, 0x73, 0x00, 0x1f, 0x41, 60 0x5b, 0x72, 0xd6, 0xa2, 0xeb, 0x15, 0x73, 0x6e, 0x13, 0xf7, 0x36, 0x42, 61 0x40, 0xee, 0x04, 0x8f, 0xc8, 0x15, 0xe4, 0xf5, 0x59, 0xc1, 0x16, 0x0d, 62 0x3d, 0x70, 0xed, 0xdb, 0x84, 0x29, 0x6c, 0x40, 0x42, 0x3b, 0x13, 0x3f, 63 0xb8, 0xfc, 0x10, 0x3c, 0xd5, 0xc1, 0x00, 0x88, 0x22, 0x41, 0xef, 0x5f, 64 0x0d, 0xb4, 0x86, 0x81, 0x0d, 0xa1, 0x28, 0x07, 0x52, 0x12, 0x00, 0x06, 65 0xba, 0xd1, 0x45, 0x71, 0xb8, 0xb8, 0x6e, 0xd9, 0x85, 0xbc, 0xf2, 0xb9, 66 0x5b, 0x40, 0x25, 0x47, 0xb0, 0xaf, 0x24, 0x79, 0x48, 0x53, 0xce, 0x29, 67 0xb4, 0x94, 0xa0, 0xa8, 0x94, 0xa7, 0xb0, 0x27, 0x41, 0xf1, 0x54, 0x9c, 68 0x09, 0x71, 0xc9, 0x92, 0x7d, 0x82, 0x74, 0x75, 0xa9, 0x1e, 0xa5, 0x27, 69 0xfd, 0x13, 0x55, 0xd9, 0x3c, 0x83, 0x38, 0xbb, 0x45, 0x5c, 0xbf, 0x3c, 70 0xa1, 0x40, 0x40, 0x02, 0x54, 0x4f, 0x41, 0x3e, 0x4f, 0x83, 0x5a, 0x2d, 71 0xae, 0x1b, 0xba, 0xb7, 0x6d, 0xf6, 0x89, 0x28, 0x71, 0x21, 0x49, 0x24, 72 0x41, 0x83, 0xe9, 0x5d, 0xe9, 0x3f, 0x12, 0x64, 0x97, 0x8b, 0xc6, 0x17, 73 0x59, 0x03, 0xea, 0xa9, 0x61, 0x08, 0x24, 0x48, 0x04, 0xc9, 0x9f, 0x80, 74 0x6a, 0x4b, 0x17, 0xc4, 0xd7, 0xac, 0xdf, 0x36, 0xab, 0xbb, 0x85, 0x39, 75 0x6e, 0xb5, 0x00, 0xe0, 0x50, 0x06, 0x01, 0x3a, 0x91, 0x02, 0x44, 0x6f, 76 0x02, 0xb7, 0x65, 0xb2, 0x0e, 0x71, 0x25, 0xf3, 0x58, 0xdc, 0x72, 0x8f, 77 0xe9, 0xc1, 0xe6, 0x52, 0xe0, 0xc2, 0xa3, 0x72, 0x46, 0xe0, 0x0e, 0x83, 78 0xa9, 0xf1, 0x4b, 0x38, 0x9f, 0x16, 0xde, 0x2e, 0xfd, 0xa4, 0x32, 0x92, 79 0x1a, 0x5b, 0x40, 0x83, 0xdc, 0x8d, 0x0f, 0x9d, 0x01, 0x3e, 0xf5, 0x83, 80 0x17, 0x7a, 0xac, 0x76, 0x41, 0x9b, 0xa4, 0xa7, 0x9b, 0xe9, 0xab, 0x51, 81 0x31, 0x20, 0x82, 0x08, 0xf8, 0x34, 0xf9, 0xdb, 0x97, 0xb8, 0xb7, 0x2c, 82 0xcd, 0xba, 0x12, 0xa6, 0xec, 0xda, 0x3c, 0xca, 0x13, 0x24, 0x0e, 0xa4, 83 0x91, 0xa4, 0x9d, 0x87, 0x69, 0xf7, 0xab, 0x74, 0x21, 0x2d, 0xa1, 0x28, 84 0x4a, 0x42, 0x52, 0x90, 0x02, 0x40, 0xd8, 0x01, 0xb0, 0xae, 0x95, 0x87, 85 0x29, 0x8f, 0x6f, 0x27, 0x64, 0xe5, 0xb3, 0xc4, 0x80, 0xa8, 0x29, 0x50, 86 0xdd, 0x24, 0x6c, 0x47, 0xfd, 0xd4, 0xd4, 0x92, 0x78, 0x1e, 0xef, 0xeb, 87 0x42, 0xae, 0x98, 0x0d, 0x7f, 0x90, 0x0a, 0x27, 0xe2, 0x00, 0xfc, 0xd5, 88 0x4e, 0x27, 0x11, 0x6d, 0x89, 0x60, 0xb7, 0x6e, 0x92, 0x54, 0xa8, 0xe6, 89 0x71, 0x5b, 0xa8, 0xff, 0x00, 0x03, 0xd2, 0xbe, 0x73, 0x38, 0x86, 0x72, 90 0xf6, 0xc1, 0xb7, 0x4f, 0x2a, 0xd1, 0x25, 0x0e, 0x01, 0x25, 0x27, 0xae, 91 0x9d, 0x41, 0xed, 0xed, 0x52, 0xe8, 0xe0, 0x7b, 0xcf, 0xab, 0x0e, 0x5d, 92 0x30, 0x96, 0xe7, 0xee, 0x4f, 0x31, 0x57, 0xc1, 0x00, 0x7e, 0x6a, 0xaf, 93 0x15, 0x8b, 0x63, 0x17, 0x6e, 0x1a, 0x61, 0x24, 0x92, 0x65, 0x6b, 0x3b, 94 0xa8, 0xf7, 0x3e, 0x9d, 0x87, 0x4a, 0x63, 0x45, 0x14, 0x51, 0x45, 0x14, 95 0x51, 0x45, 0x7f, 0xff, 0xd9 96}; 97 98/* length of data in image_jpg */ 99static const unsigned int image_jpg_len = sizeof(image_jpg); 100 101/* dimensions of image */ 102static const unsigned int image_jpg_x = 64; 103static const unsigned int image_jpg_y = 64; 104 105/* start of JPEG image data section */ 106static const unsigned int image_data_offset = 20; 107#define image_data_len (image_jpg_len - image_data_offset) 108 109/* raw EXIF header data */ 110static const unsigned char exif_header[] = { 111 0xff, 0xd8, 0xff, 0xe1 112}; 113/* length of data in exif_header */ 114static const unsigned int exif_header_len = sizeof(exif_header); 115 116/* byte order to use in the EXIF block */ 117#define BYTE_ORDER EXIF_BYTE_ORDER_INTEL 118 119/* Get an existing tag, or create one if it doesn't exist */ 120static ExifEntry *init_tag(ExifData *exif, ExifIfd ifd, ExifTag tag) 121{ 122 ExifEntry *entry; 123 if (!((entry = exif_content_get_entry (exif->ifd[ifd], tag)))) { 124 entry = exif_entry_new (); 125 assert(entry != NULL); /* catch an out of memory condition */ 126 exif_content_add_entry (exif->ifd[ifd], entry); 127 exif_entry_initialize (entry, tag); 128 } 129 return entry; 130} 131 132int main(int argc, char **argv) 133{ 134 int rc = 1; 135 FILE *f; 136 unsigned char *exif_data; 137 unsigned int exif_data_len; 138 ExifEntry *entry; 139 ExifData *exif = exif_data_new(); 140 if (!exif) { 141 fprintf(stderr, "Out of memory\n"); 142 return 2; 143 } 144 145 /* Set the image options */ 146 exif_data_set_option(exif, EXIF_DATA_OPTION_FOLLOW_SPECIFICATION); 147 exif_data_set_data_type(exif, EXIF_DATA_TYPE_COMPRESSED); 148 exif_data_set_byte_order(exif, BYTE_ORDER); 149 150 /* Create the mandatory EXIF fields with default data */ 151 exif_data_fix(exif); 152 153 /* All these tags are created with default values by exif_data_fix() */ 154 /* Change the data to the correct values for this image. */ 155 entry = init_tag(exif, EXIF_IFD_EXIF, EXIF_TAG_PIXEL_X_DIMENSION); 156 exif_set_long(entry->data, BYTE_ORDER, image_jpg_x); 157 158 entry = init_tag(exif, EXIF_IFD_EXIF, EXIF_TAG_PIXEL_Y_DIMENSION); 159 exif_set_long(entry->data, BYTE_ORDER, image_jpg_y); 160 161 entry = init_tag(exif, EXIF_IFD_EXIF, EXIF_TAG_COLOR_SPACE); 162 exif_set_short(entry->data, BYTE_ORDER, 1); 163 164 /* A good example to give here would be to add a new tag that isn't 165 * automatically created by exif_data_fix() (such as 166 * EXIF_TAG_USER_COMMENT) which requires allocating memory in 167 * entry->data. This isn't so easy to do, unfortunately. 168 */ 169 170 /* Get a pointer to the EXIF data block we just created */ 171 exif_data_save_data(exif, &exif_data, &exif_data_len); 172 173 f = fopen(FILE_NAME, "wb"); 174 if (!f) { 175 fprintf(stderr, "Error creating file %s\n", FILE_NAME); 176 exif_data_unref(exif); 177 return rc; 178 } 179 /* Write EXIF header */ 180 if (fwrite(exif_header, exif_header_len, 1, f) != 1) { 181 fprintf(stderr, "Error writing to file %s\n", FILE_NAME); 182 goto errout; 183 } 184 /* Write EXIF block length */ 185 if (fputc((exif_data_len+2) >> 8, f) < 0) { 186 fprintf(stderr, "Error writing to file %s\n", FILE_NAME); 187 goto errout; 188 } 189 if (fputc((exif_data_len+2) & 0xff, f) < 0) { 190 fprintf(stderr, "Error writing to file %s\n", FILE_NAME); 191 goto errout; 192 } 193 /* Write EXIF data block */ 194 if (fwrite(exif_data, exif_data_len, 1, f) != 1) { 195 fprintf(stderr, "Error writing to file %s\n", FILE_NAME); 196 goto errout; 197 } 198 /* Write JPEG image data */ 199 if (fwrite(image_jpg+image_data_offset, image_data_len, 1, f) != 1) { 200 fprintf(stderr, "Error writing to file %s\n", FILE_NAME); 201 goto errout; 202 } 203 printf("Wrote file %s\n", FILE_NAME); 204 rc = 0; 205 206errout: 207 if (fclose(f)) { 208 fprintf(stderr, "Error writing to file %s\n", FILE_NAME); 209 rc = 1; 210 } 211 exif_data_unref(exif); 212 213 return rc; 214} 215