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 { "remount", MS_TYPE, MS_REMOUNT, 0 }, 53 { "ro", MS_RDONLY, MS_RDONLY, 0 }, 54 { "rw", MS_RDONLY, 0, MS_RDONLY }, 55 { "suid", MS_NOSUID, 0, MS_NOSUID }, 56 { "sync", MS_SYNCHRONOUS, MS_SYNCHRONOUS, 0 }, 57 { "verbose", MS_VERBOSE, MS_VERBOSE, 0 }, 58 }; 59 60 static void add_extra_option(struct extra_opts *extra, char *s) 61 { 62 int len = strlen(s); 63 int newlen = extra->used_size + len; 64 65 if (extra->str) 66 len++; /* +1 for ',' */ 67 68 if (newlen >= extra->alloc_size) { 69 char *new; 70 71 new = realloc(extra->str, newlen + 1); /* +1 for NUL */ 72 if (!new) 73 return; 74 75 extra->str = new; 76 extra->end = extra->str + extra->used_size; 77 extra->alloc_size = newlen; 78 } 79 80 if (extra->used_size) { 81 *extra->end = ','; 82 extra->end++; 83 } 84 strcpy(extra->end, s); 85 extra->used_size += len; 86 87 } 88 89 static unsigned long 90 parse_mount_options(char *arg, unsigned long rwflag, struct extra_opts *extra, int* loop, char *loopdev) 91 { 92 char *s; 93 94 *loop = 0; 95 while ((s = strsep(&arg, ",")) != NULL) { 96 char *opt = s; 97 unsigned int i; 98 int res, no = s[0] == 'n' && s[1] == 'o'; 99 100 if (no) 101 s += 2; 102 103 if (strncmp(s, "loop=", 5) == 0) { 104 *loop = 1; 105 strlcpy(loopdev, s + 5, LOOPDEV_MAXLEN); 106 continue; 107 } 108 109 if (strcmp(s, "loop") == 0) { 110 *loop = 1; 111 strlcpy(loopdev, DEFAULT_LOOP_DEVICE, LOOPDEV_MAXLEN); 112 continue; 113 } 114 for (i = 0, res = 1; i < ARRAY_SIZE(options); i++) { 115 res = strcmp(s, options[i].str); 116 117 if (res == 0) { 118 rwflag &= ~options[i].rwmask; 119 if (no) 120 rwflag |= options[i].rwnoset; 121 else 122 rwflag |= options[i].rwset; 123 } 124 if (res <= 0) 125 break; 126 } 127 128 if (res != 0 && s[0]) 129 add_extra_option(extra, opt); 130 } 131 132 return rwflag; 133 } 134 135 static char *progname; 136 137 static struct extra_opts extra; 138 static unsigned long rwflag; 139 140 static int 141 do_mount(char *dev, char *dir, char *type, unsigned long rwflag, void *data, int loop, 142 char *loopdev) 143 { 144 char *s; 145 int error = 0; 146 147 if (loop) { 148 int file_fd, device_fd; 149 int flags; 150 151 flags = (rwflag & MS_RDONLY) ? O_RDONLY : O_RDWR; 152 153 file_fd = open(dev, flags); 154 if (file_fd < 0) { 155 perror("open backing file failed"); 156 return 1; 157 } 158 device_fd = open(loopdev, flags); 159 if (device_fd < 0) { 160 perror("open loop device failed"); 161 close(file_fd); 162 return 1; 163 } 164 if (ioctl(device_fd, LOOP_SET_FD, file_fd) < 0) { 165 perror("ioctl LOOP_SET_FD failed"); 166 close(file_fd); 167 close(device_fd); 168 return 1; 169 } 170 171 close(file_fd); 172 close(device_fd); 173 dev = loopdev; 174 } 175 176 while ((s = strsep(&type, ",")) != NULL) { 177 retry: 178 if (mount(dev, dir, s, rwflag, data) == -1) { 179 error = errno; 180 /* 181 * If the filesystem is not found, or the 182 * superblock is invalid, try the next. 183 */ 184 if (error == ENODEV || error == EINVAL) 185 continue; 186 187 /* 188 * If we get EACCESS, and we're trying to 189 * mount readwrite and this isn't a remount, 190 * try read only. 191 */ 192 if (error == EACCES && 193 (rwflag & (MS_REMOUNT|MS_RDONLY)) == 0) { 194 rwflag |= MS_RDONLY; 195 goto retry; 196 } 197 break; 198 } 199 } 200 201 if (error) { 202 errno = error; 203 perror("mount"); 204 return 255; 205 } 206 207 return 0; 208 } 209 210 static int print_mounts() 211 { 212 FILE* f; 213 int length; 214 char buffer[100]; 215 216 f = fopen("/proc/mounts", "r"); 217 if (!f) { 218 fprintf(stdout, "could not open /proc/mounts\n"); 219 return -1; 220 } 221 222 do { 223 length = fread(buffer, 1, 100, f); 224 if (length > 0) 225 fwrite(buffer, 1, length, stdout); 226 } while (length > 0); 227 228 fclose(f); 229 return 0; 230 } 231 232 static int get_mounts_dev_dir(const char *arg, char **dev, char **dir) 233 { 234 FILE *f; 235 char mount_dev[256]; 236 char mount_dir[256]; 237 char mount_type[256]; 238 char mount_opts[256]; 239 int mount_freq; 240 int mount_passno; 241 int match; 242 243 f = fopen("/proc/mounts", "r"); 244 if (!f) { 245 fprintf(stdout, "could not open /proc/mounts\n"); 246 return -1; 247 } 248 249 do { 250 match = fscanf(f, "%255s %255s %255s %255s %d %d\n", 251 mount_dev, mount_dir, mount_type, 252 mount_opts, &mount_freq, &mount_passno); 253 mount_dev[255] = 0; 254 mount_dir[255] = 0; 255 mount_type[255] = 0; 256 mount_opts[255] = 0; 257 if (match == 6 && 258 (strcmp(arg, mount_dev) == 0 || 259 strcmp(arg, mount_dir) == 0)) { 260 *dev = strdup(mount_dev); 261 *dir = strdup(mount_dir); 262 fclose(f); 263 return 0; 264 } 265 } while (match != EOF); 266 267 fclose(f); 268 return -1; 269 } 270 271 int mount_main(int argc, char *argv[]) 272 { 273 char *type = NULL; 274 char *dev = NULL; 275 char *dir = NULL; 276 int c; 277 int loop = 0; 278 char loopdev[LOOPDEV_MAXLEN]; 279 280 progname = argv[0]; 281 rwflag = MS_VERBOSE; 282 283 // mount with no arguments is equivalent to "cat /proc/mounts" 284 if (argc == 1) return print_mounts(); 285 286 do { 287 c = getopt(argc, argv, "o:rt:w"); 288 if (c == EOF) 289 break; 290 switch (c) { 291 case 'o': 292 rwflag = parse_mount_options(optarg, rwflag, &extra, &loop, loopdev); 293 break; 294 case 'r': 295 rwflag |= MS_RDONLY; 296 break; 297 case 't': 298 type = optarg; 299 break; 300 case 'w': 301 rwflag &= ~MS_RDONLY; 302 break; 303 case '?': 304 fprintf(stderr, "%s: invalid option -%c\n", 305 progname, optopt); 306 exit(1); 307 } 308 } while (1); 309 310 /* 311 * If remount, bind or move was specified, then we don't 312 * have a "type" as such. Use the dummy "none" type. 313 */ 314 if (rwflag & MS_TYPE) 315 type = "none"; 316 317 if (optind + 2 == argc) { 318 dev = argv[optind]; 319 dir = argv[optind + 1]; 320 } else if (optind + 1 == argc && rwflag & MS_REMOUNT) { 321 get_mounts_dev_dir(argv[optind], &dev, &dir); 322 } 323 324 if (dev == NULL || dir == NULL || type == NULL) { 325 fprintf(stderr, "Usage: %s [-r] [-w] [-o options] [-t type] " 326 "device directory\n", progname); 327 exit(1); 328 } 329 330 return do_mount(dev, dir, type, rwflag, extra.str, loop, loopdev); 331 /* We leak dev and dir in some cases, but we're about to exit */ 332 } 333
