1 /* 2 * mount.c, by rmk 3 */ 4 5 #include <sys/mount.h> 6 #include <sys/stat.h> 7 #include <fcntl.h> 8 #include <errno.h> 9 #include <stdio.h> 10 #include <stdlib.h> 11 #include <string.h> 12 #include <unistd.h> 13 14 #include <linux/loop.h> 15 16 #define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0])) 17 18 #define DEFAULT_LOOP_DEVICE "/dev/block/loop0" 19 #define LOOPDEV_MAXLEN 64 20 21 struct mount_opts { 22 const char str[16]; 23 unsigned long rwmask; 24 unsigned long rwset; 25 unsigned long rwnoset; 26 }; 27 28 struct extra_opts { 29 char *str; 30 char *end; 31 int used_size; 32 int alloc_size; 33 }; 34 35 /* 36 * These options define the function of "mount(2)". 37 */ 38 #define MS_TYPE (MS_REMOUNT|MS_BIND|MS_MOVE) 39 40 41 static const struct mount_opts options[] = { 42 /* name mask set noset */ 43 { "async", MS_SYNCHRONOUS, 0, MS_SYNCHRONOUS }, 44 { "atime", MS_NOATIME, 0, MS_NOATIME }, 45 { "bind", MS_TYPE, MS_BIND, 0, }, 46 { "dev", MS_NODEV, 0, MS_NODEV }, 47 { "diratime", MS_NODIRATIME, 0, MS_NODIRATIME }, 48 { "dirsync", MS_DIRSYNC, MS_DIRSYNC, 0 }, 49 { "exec", MS_NOEXEC, 0, MS_NOEXEC }, 50 { "move", MS_TYPE, MS_MOVE, 0 }, 51 { "recurse", MS_REC, MS_REC, 0 }, 52 { "rec", MS_REC, MS_REC, 0 }, 53 { "remount", MS_TYPE, MS_REMOUNT, 0 }, 54 { "ro", MS_RDONLY, MS_RDONLY, 0 }, 55 { "rw", MS_RDONLY, 0, MS_RDONLY }, 56 { "suid", MS_NOSUID, 0, MS_NOSUID }, 57 { "sync", MS_SYNCHRONOUS, MS_SYNCHRONOUS, 0 }, 58 { "verbose", MS_VERBOSE, MS_VERBOSE, 0 }, 59 { "unbindable", MS_UNBINDABLE, MS_UNBINDABLE, 0 }, 60 { "private", MS_PRIVATE, MS_PRIVATE, 0 }, 61 { "slave", MS_SLAVE, MS_SLAVE, 0 }, 62 { "shared", MS_SHARED, MS_SHARED, 0 }, 63 }; 64 65 static void add_extra_option(struct extra_opts *extra, char *s) 66 { 67 int len = strlen(s); 68 int newlen; 69 70 if (extra->str) 71 len++; /* +1 for ',' */ 72 newlen = extra->used_size + len; 73 74 if (newlen >= extra->alloc_size) { 75 char *new; 76 77 new = realloc(extra->str, newlen + 1); /* +1 for NUL */ 78 if (!new) 79 return; 80 81 extra->str = new; 82 extra->end = extra->str + extra->used_size; 83 extra->alloc_size = newlen + 1; 84 } 85 86 if (extra->used_size) { 87 *extra->end = ','; 88 extra->end++; 89 } 90 strcpy(extra->end, s); 91 extra->used_size += len; 92 93 } 94 95 static unsigned long 96 parse_mount_options(char *arg, unsigned long rwflag, struct extra_opts *extra, int* loop, char *loopdev) 97 { 98 char *s; 99 100 *loop = 0; 101 while ((s = strsep(&arg, ",")) != NULL) { 102 char *opt = s; 103 unsigned int i; 104 int res, no = s[0] == 'n' && s[1] == 'o'; 105 106 if (no) 107 s += 2; 108 109 if (strncmp(s, "loop=", 5) == 0) { 110 *loop = 1; 111 strlcpy(loopdev, s + 5, LOOPDEV_MAXLEN); 112 continue; 113 } 114 115 if (strcmp(s, "loop") == 0) { 116 *loop = 1; 117 strlcpy(loopdev, DEFAULT_LOOP_DEVICE, LOOPDEV_MAXLEN); 118 continue; 119 } 120 for (i = 0, res = 1; i < ARRAY_SIZE(options); i++) { 121 res = strcmp(s, options[i].str); 122 123 if (res == 0) { 124 rwflag &= ~options[i].rwmask; 125 if (no) 126 rwflag |= options[i].rwnoset; 127 else 128 rwflag |= options[i].rwset; 129 } 130 if (res <= 0) 131 break; 132 } 133 134 if (res != 0 && s[0]) 135 add_extra_option(extra, opt); 136 } 137 138 return rwflag; 139 } 140 141 /* 142 * Mark the given block device as read-write, using the BLKROSET ioctl. 143 */ 144 static void fs_set_blk_rw(const char *blockdev) 145 { 146 int fd; 147 int OFF = 0; 148 149 fd = open(blockdev, O_RDONLY); 150 if (fd < 0) { 151 // should never happen 152 return; 153 } 154 155 ioctl(fd, BLKROSET, &OFF); 156 close(fd); 157 } 158 159 static char *progname; 160 161 static struct extra_opts extra; 162 static unsigned long rwflag; 163 164 static int 165 do_mount(char *dev, char *dir, char *type, unsigned long rwflag, void *data, int loop, 166 char *loopdev) 167 { 168 char *s; 169 int error = 0; 170 171 if (loop) { 172 int file_fd, device_fd; 173 int flags; 174 175 flags = (rwflag & MS_RDONLY) ? O_RDONLY : O_RDWR; 176 177 file_fd = open(dev, flags); 178 if (file_fd < 0) { 179 perror("open backing file failed"); 180 return 1; 181 } 182 device_fd = open(loopdev, flags); 183 if (device_fd < 0) { 184 perror("open loop device failed"); 185 close(file_fd); 186 return 1; 187 } 188 if (ioctl(device_fd, LOOP_SET_FD, file_fd) < 0) { 189 perror("ioctl LOOP_SET_FD failed"); 190 close(file_fd); 191 close(device_fd); 192 return 1; 193 } 194 195 close(file_fd); 196 close(device_fd); 197 dev = loopdev; 198 } 199 200 if ((rwflag & MS_RDONLY) == 0) { 201 fs_set_blk_rw(dev); 202 } 203 204 while ((s = strsep(&type, ",")) != NULL) { 205 retry: 206 if (mount(dev, dir, s, rwflag, data) == -1) { 207 error = errno; 208 /* 209 * If the filesystem is not found, or the 210 * superblock is invalid, try the next. 211 */ 212 if (error == ENODEV || error == EINVAL) 213 continue; 214 215 /* 216 * If we get EACCESS, and we're trying to 217 * mount readwrite and this isn't a remount, 218 * try read only. 219 */ 220 if (error == EACCES && 221 (rwflag & (MS_REMOUNT|MS_RDONLY)) == 0) { 222 rwflag |= MS_RDONLY; 223 goto retry; 224 } 225 break; 226 } 227 } 228 229 if (error) { 230 errno = error; 231 perror("mount"); 232 return 255; 233 } 234 235 return 0; 236 } 237 238 static int print_mounts() 239 { 240 FILE* f; 241 int length; 242 char buffer[100]; 243 244 f = fopen("/proc/mounts", "r"); 245 if (!f) { 246 fprintf(stdout, "could not open /proc/mounts\n"); 247 return -1; 248 } 249 250 do { 251 length = fread(buffer, 1, 100, f); 252 if (length > 0) 253 fwrite(buffer, 1, length, stdout); 254 } while (length > 0); 255 256 fclose(f); 257 return 0; 258 } 259 260 static int get_mounts_dev_dir(const char *arg, char **dev, char **dir) 261 { 262 FILE *f; 263 char mount_dev[256]; 264 char mount_dir[256]; 265 char mount_type[256]; 266 char mount_opts[256]; 267 int mount_freq; 268 int mount_passno; 269 int match; 270 271 f = fopen("/proc/mounts", "r"); 272 if (!f) { 273 fprintf(stdout, "could not open /proc/mounts\n"); 274 return -1; 275 } 276 277 do { 278 match = fscanf(f, "%255s %255s %255s %255s %d %d\n", 279 mount_dev, mount_dir, mount_type, 280 mount_opts, &mount_freq, &mount_passno); 281 mount_dev[255] = 0; 282 mount_dir[255] = 0; 283 mount_type[255] = 0; 284 mount_opts[255] = 0; 285 if (match == 6 && 286 (strcmp(arg, mount_dev) == 0 || 287 strcmp(arg, mount_dir) == 0)) { 288 *dev = strdup(mount_dev); 289 *dir = strdup(mount_dir); 290 fclose(f); 291 return 0; 292 } 293 } while (match != EOF); 294 295 fclose(f); 296 return -1; 297 } 298 299 int mount_main(int argc, char *argv[]) 300 { 301 char *type = NULL; 302 char *dev = NULL; 303 char *dir = NULL; 304 int c; 305 int loop = 0; 306 char loopdev[LOOPDEV_MAXLEN]; 307 308 progname = argv[0]; 309 rwflag = MS_VERBOSE; 310 311 // mount with no arguments is equivalent to "cat /proc/mounts" 312 if (argc == 1) return print_mounts(); 313 314 do { 315 c = getopt(argc, argv, "o:rt:w"); 316 if (c == EOF) 317 break; 318 switch (c) { 319 case 'o': 320 rwflag = parse_mount_options(optarg, rwflag, &extra, &loop, loopdev); 321 break; 322 case 'r': 323 rwflag |= MS_RDONLY; 324 break; 325 case 't': 326 type = optarg; 327 break; 328 case 'w': 329 rwflag &= ~MS_RDONLY; 330 break; 331 case '?': 332 fprintf(stderr, "%s: invalid option -%c\n", 333 progname, optopt); 334 exit(1); 335 } 336 } while (1); 337 338 /* 339 * If remount, bind or move was specified, then we don't 340 * have a "type" as such. Use the dummy "none" type. 341 */ 342 if (rwflag & MS_TYPE) 343 type = "none"; 344 345 if (optind + 2 == argc) { 346 dev = argv[optind]; 347 dir = argv[optind + 1]; 348 } else if (optind + 1 == argc && rwflag & MS_REMOUNT) { 349 get_mounts_dev_dir(argv[optind], &dev, &dir); 350 } 351 352 if (dev == NULL || dir == NULL || type == NULL) { 353 fprintf(stderr, "Usage: %s [-r] [-w] [-o options] [-t type] " 354 "device directory\n", progname); 355 exit(1); 356 } 357 358 return do_mount(dev, dir, type, rwflag, extra.str, loop, loopdev); 359 /* We leak dev and dir in some cases, but we're about to exit */ 360 } 361
