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 // FIXME - only one loop mount is supported at a time 19 #define LOOP_DEVICE "/dev/block/loop0" 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) 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 (strcmp(s, "loop") == 0) { 104 *loop = 1; 105 continue; 106 } 107 for (i = 0, res = 1; i < ARRAY_SIZE(options); i++) { 108 res = strcmp(s, options[i].str); 109 110 if (res == 0) { 111 rwflag &= ~options[i].rwmask; 112 if (no) 113 rwflag |= options[i].rwnoset; 114 else 115 rwflag |= options[i].rwset; 116 } 117 if (res <= 0) 118 break; 119 } 120 121 if (res != 0 && s[0]) 122 add_extra_option(extra, opt); 123 } 124 125 return rwflag; 126 } 127 128 static char *progname; 129 130 static struct extra_opts extra; 131 static unsigned long rwflag; 132 133 static int 134 do_mount(char *dev, char *dir, char *type, unsigned long rwflag, void *data, int loop) 135 { 136 char *s; 137 int error = 0; 138 139 if (loop) { 140 int file_fd, device_fd; 141 int flags; 142 143 flags = (rwflag & MS_RDONLY) ? O_RDONLY : O_RDWR; 144 145 // FIXME - only one loop mount supported at a time 146 file_fd = open(dev, flags); 147 if (file_fd < -1) { 148 perror("open backing file failed"); 149 return 1; 150 } 151 device_fd = open(LOOP_DEVICE, flags); 152 if (device_fd < -1) { 153 perror("open loop device failed"); 154 close(file_fd); 155 return 1; 156 } 157 if (ioctl(device_fd, LOOP_SET_FD, file_fd) < 0) { 158 perror("ioctl LOOP_SET_FD failed"); 159 close(file_fd); 160 close(device_fd); 161 return 1; 162 } 163 164 close(file_fd); 165 close(device_fd); 166 dev = LOOP_DEVICE; 167 } 168 169 while ((s = strsep(&type, ",")) != NULL) { 170 retry: 171 if (mount(dev, dir, s, rwflag, data) == -1) { 172 error = errno; 173 /* 174 * If the filesystem is not found, or the 175 * superblock is invalid, try the next. 176 */ 177 if (error == ENODEV || error == EINVAL) 178 continue; 179 180 /* 181 * If we get EACCESS, and we're trying to 182 * mount readwrite and this isn't a remount, 183 * try read only. 184 */ 185 if (error == EACCES && 186 (rwflag & (MS_REMOUNT|MS_RDONLY)) == 0) { 187 rwflag |= MS_RDONLY; 188 goto retry; 189 } 190 break; 191 } 192 } 193 194 if (error) { 195 errno = error; 196 perror("mount"); 197 return 255; 198 } 199 200 return 0; 201 } 202 203 static int print_mounts() 204 { 205 FILE* f; 206 int length; 207 char buffer[100]; 208 209 f = fopen("/proc/mounts", "r"); 210 if (!f) { 211 fprintf(stdout, "could not open /proc/mounts\n"); 212 return -1; 213 } 214 215 do { 216 length = fread(buffer, 1, 100, f); 217 if (length > 0) 218 fwrite(buffer, 1, length, stdout); 219 } while (length > 0); 220 221 fclose(f); 222 return 0; 223 } 224 225 int mount_main(int argc, char *argv[]) 226 { 227 char *type = NULL; 228 int c; 229 int loop = 0; 230 231 progname = argv[0]; 232 rwflag = MS_VERBOSE; 233 234 // mount with no arguments is equivalent to "cat /proc/mounts" 235 if (argc == 1) return print_mounts(); 236 237 do { 238 c = getopt(argc, argv, "o:rt:w"); 239 if (c == EOF) 240 break; 241 switch (c) { 242 case 'o': 243 rwflag = parse_mount_options(optarg, rwflag, &extra, &loop); 244 break; 245 case 'r': 246 rwflag |= MS_RDONLY; 247 break; 248 case 't': 249 type = optarg; 250 break; 251 case 'w': 252 rwflag &= ~MS_RDONLY; 253 break; 254 case '?': 255 fprintf(stderr, "%s: invalid option -%c\n", 256 progname, optopt); 257 exit(1); 258 } 259 } while (1); 260 261 /* 262 * If remount, bind or move was specified, then we don't 263 * have a "type" as such. Use the dummy "none" type. 264 */ 265 if (rwflag & MS_TYPE) 266 type = "none"; 267 268 if (optind + 2 != argc || type == NULL) { 269 fprintf(stderr, "Usage: %s [-r] [-w] [-o options] [-t type] " 270 "device directory\n", progname); 271 exit(1); 272 } 273 274 return do_mount(argv[optind], argv[optind + 1], type, rwflag, 275 extra.str, loop); 276 } 277
