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[8]; 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 = extra->used_size + len; 69 70 if (extra->str) 71 len++; /* +1 for ',' */ 72 73 if (newlen >= extra->alloc_size) { 74 char *new; 75 76 new = realloc(extra->str, newlen + 1); /* +1 for NUL */ 77 if (!new) 78 return; 79 80 extra->str = new; 81 extra->end = extra->str + extra->used_size; 82 extra->alloc_size = newlen; 83 } 84 85 if (extra->used_size) { 86 *extra->end = ','; 87 extra->end++; 88 } 89 strcpy(extra->end, s); 90 extra->used_size += len; 91 92 } 93 94 static unsigned long 95 parse_mount_options(char *arg, unsigned long rwflag, struct extra_opts *extra, int* loop, char *loopdev) 96 { 97 char *s; 98 99 *loop = 0; 100 while ((s = strsep(&arg, ",")) != NULL) { 101 char *opt = s; 102 unsigned int i; 103 int res, no = s[0] == 'n' && s[1] == 'o'; 104 105 if (no) 106 s += 2; 107 108 if (strncmp(s, "loop=", 5) == 0) { 109 *loop = 1; 110 strlcpy(loopdev, s + 5, LOOPDEV_MAXLEN); 111 continue; 112 } 113 114 if (strcmp(s, "loop") == 0) { 115 *loop = 1; 116 strlcpy(loopdev, DEFAULT_LOOP_DEVICE, LOOPDEV_MAXLEN); 117 continue; 118 } 119 for (i = 0, res = 1; i < ARRAY_SIZE(options); i++) { 120 res = strcmp(s, options[i].str); 121 122 if (res == 0) { 123 rwflag &= ~options[i].rwmask; 124 if (no) 125 rwflag |= options[i].rwnoset; 126 else 127 rwflag |= options[i].rwset; 128 } 129 if (res <= 0) 130 break; 131 } 132 133 if (res != 0 && s[0]) 134 add_extra_option(extra, opt); 135 } 136 137 return rwflag; 138 } 139 140 static char *progname; 141 142 static struct extra_opts extra; 143 static unsigned long rwflag; 144 145 static int 146 do_mount(char *dev, char *dir, char *type, unsigned long rwflag, void *data, int loop, 147 char *loopdev) 148 { 149 char *s; 150 int error = 0; 151 152 if (loop) { 153 int file_fd, device_fd; 154 int flags; 155 156 flags = (rwflag & MS_RDONLY) ? O_RDONLY : O_RDWR; 157 158 file_fd = open(dev, flags); 159 if (file_fd < 0) { 160 perror("open backing file failed"); 161 return 1; 162 } 163 device_fd = open(loopdev, flags); 164 if (device_fd < 0) { 165 perror("open loop device failed"); 166 close(file_fd); 167 return 1; 168 } 169 if (ioctl(device_fd, LOOP_SET_FD, file_fd) < 0) { 170 perror("ioctl LOOP_SET_FD failed"); 171 close(file_fd); 172 close(device_fd); 173 return 1; 174 } 175 176 close(file_fd); 177 close(device_fd); 178 dev = loopdev; 179 } 180 181 while ((s = strsep(&type, ",")) != NULL) { 182 retry: 183 if (mount(dev, dir, s, rwflag, data) == -1) { 184 error = errno; 185 /* 186 * If the filesystem is not found, or the 187 * superblock is invalid, try the next. 188 */ 189 if (error == ENODEV || error == EINVAL) 190 continue; 191 192 /* 193 * If we get EACCESS, and we're trying to 194 * mount readwrite and this isn't a remount, 195 * try read only. 196 */ 197 if (error == EACCES && 198 (rwflag & (MS_REMOUNT|MS_RDONLY)) == 0) { 199 rwflag |= MS_RDONLY; 200 goto retry; 201 } 202 break; 203 } 204 } 205 206 if (error) { 207 errno = error; 208 perror("mount"); 209 return 255; 210 } 211 212 return 0; 213 } 214 215 static int print_mounts() 216 { 217 FILE* f; 218 int length; 219 char buffer[100]; 220 221 f = fopen("/proc/mounts", "r"); 222 if (!f) { 223 fprintf(stdout, "could not open /proc/mounts\n"); 224 return -1; 225 } 226 227 do { 228 length = fread(buffer, 1, 100, f); 229 if (length > 0) 230 fwrite(buffer, 1, length, stdout); 231 } while (length > 0); 232 233 fclose(f); 234 return 0; 235 } 236 237 static int get_mounts_dev_dir(const char *arg, char **dev, char **dir) 238 { 239 FILE *f; 240 char mount_dev[256]; 241 char mount_dir[256]; 242 char mount_type[256]; 243 char mount_opts[256]; 244 int mount_freq; 245 int mount_passno; 246 int match; 247 248 f = fopen("/proc/mounts", "r"); 249 if (!f) { 250 fprintf(stdout, "could not open /proc/mounts\n"); 251 return -1; 252 } 253 254 do { 255 match = fscanf(f, "%255s %255s %255s %255s %d %d\n", 256 mount_dev, mount_dir, mount_type, 257 mount_opts, &mount_freq, &mount_passno); 258 mount_dev[255] = 0; 259 mount_dir[255] = 0; 260 mount_type[255] = 0; 261 mount_opts[255] = 0; 262 if (match == 6 && 263 (strcmp(arg, mount_dev) == 0 || 264 strcmp(arg, mount_dir) == 0)) { 265 *dev = strdup(mount_dev); 266 *dir = strdup(mount_dir); 267 fclose(f); 268 return 0; 269 } 270 } while (match != EOF); 271 272 fclose(f); 273 return -1; 274 } 275 276 int mount_main(int argc, char *argv[]) 277 { 278 char *type = NULL; 279 char *dev = NULL; 280 char *dir = NULL; 281 int c; 282 int loop = 0; 283 char loopdev[LOOPDEV_MAXLEN]; 284 285 progname = argv[0]; 286 rwflag = MS_VERBOSE; 287 288 // mount with no arguments is equivalent to "cat /proc/mounts" 289 if (argc == 1) return print_mounts(); 290 291 do { 292 c = getopt(argc, argv, "o:rt:w"); 293 if (c == EOF) 294 break; 295 switch (c) { 296 case 'o': 297 rwflag = parse_mount_options(optarg, rwflag, &extra, &loop, loopdev); 298 break; 299 case 'r': 300 rwflag |= MS_RDONLY; 301 break; 302 case 't': 303 type = optarg; 304 break; 305 case 'w': 306 rwflag &= ~MS_RDONLY; 307 break; 308 case '?': 309 fprintf(stderr, "%s: invalid option -%c\n", 310 progname, optopt); 311 exit(1); 312 } 313 } while (1); 314 315 /* 316 * If remount, bind or move was specified, then we don't 317 * have a "type" as such. Use the dummy "none" type. 318 */ 319 if (rwflag & MS_TYPE) 320 type = "none"; 321 322 if (optind + 2 == argc) { 323 dev = argv[optind]; 324 dir = argv[optind + 1]; 325 } else if (optind + 1 == argc && rwflag & MS_REMOUNT) { 326 get_mounts_dev_dir(argv[optind], &dev, &dir); 327 } 328 329 if (dev == NULL || dir == NULL || type == NULL) { 330 fprintf(stderr, "Usage: %s [-r] [-w] [-o options] [-t type] " 331 "device directory\n", progname); 332 exit(1); 333 } 334 335 return do_mount(dev, dir, type, rwflag, extra.str, loop, loopdev); 336 /* We leak dev and dir in some cases, but we're about to exit */ 337 } 338
