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
add_extra_option(struct extra_opts * extra,char * s)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
parse_mount_options(char * arg,unsigned long rwflag,struct extra_opts * extra,int * loop,char * loopdev)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
do_mount(char * dev,char * dir,char * type,unsigned long rwflag,void * data,int loop,char * loopdev)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
print_mounts()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
get_mounts_dev_dir(const char * arg,char ** dev,char ** dir)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
mount_main(int argc,char * argv[])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