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- /*
- * mount.c, by rmk
- */
- #include <sys/mount.h>
- #include <sys/stat.h>
- #include <fcntl.h>
- #include <errno.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <unistd.h>
- #include <linux/loop.h>
- #define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))
- #define DEFAULT_LOOP_DEVICE "/dev/block/loop0"
- #define LOOPDEV_MAXLEN 64
- struct mount_opts {
- const char str[16];
- unsigned long rwmask;
- unsigned long rwset;
- unsigned long rwnoset;
- };
- struct extra_opts {
- char *str;
- char *end;
- int used_size;
- int alloc_size;
- };
- /*
- * These options define the function of "mount(2)".
- */
- #define MS_TYPE (MS_REMOUNT|MS_BIND|MS_MOVE)
- static const struct mount_opts options[] = {
- /* name mask set noset */
- { "async", MS_SYNCHRONOUS, 0, MS_SYNCHRONOUS },
- { "atime", MS_NOATIME, 0, MS_NOATIME },
- { "bind", MS_TYPE, MS_BIND, 0, },
- { "dev", MS_NODEV, 0, MS_NODEV },
- { "diratime", MS_NODIRATIME, 0, MS_NODIRATIME },
- { "dirsync", MS_DIRSYNC, MS_DIRSYNC, 0 },
- { "exec", MS_NOEXEC, 0, MS_NOEXEC },
- { "move", MS_TYPE, MS_MOVE, 0 },
- { "recurse", MS_REC, MS_REC, 0 },
- { "rec", MS_REC, MS_REC, 0 },
- { "remount", MS_TYPE, MS_REMOUNT, 0 },
- { "ro", MS_RDONLY, MS_RDONLY, 0 },
- { "rw", MS_RDONLY, 0, MS_RDONLY },
- { "suid", MS_NOSUID, 0, MS_NOSUID },
- { "sync", MS_SYNCHRONOUS, MS_SYNCHRONOUS, 0 },
- { "verbose", MS_SILENT, MS_SILENT, 0 },
- { "unbindable", MS_UNBINDABLE, MS_UNBINDABLE, 0 },
- { "private", MS_PRIVATE, MS_PRIVATE, 0 },
- { "slave", MS_SLAVE, MS_SLAVE, 0 },
- { "shared", MS_SHARED, MS_SHARED, 0 },
- };
- static void add_extra_option(struct extra_opts *extra, char *s)
- {
- int len = strlen(s);
- int newlen;
- if (extra->str)
- len++; /* +1 for ',' */
- newlen = extra->used_size + len;
- if (newlen >= extra->alloc_size) {
- char *new;
- new = realloc(extra->str, newlen + 1); /* +1 for NUL */
- if (!new)
- return;
- extra->str = new;
- extra->end = extra->str + extra->used_size;
- extra->alloc_size = newlen + 1;
- }
- if (extra->used_size) {
- *extra->end = ',';
- extra->end++;
- }
- strcpy(extra->end, s);
- extra->used_size += len;
- }
- static unsigned long
- parse_mount_options(char *arg, unsigned long rwflag, struct extra_opts *extra, int* loop, char *loopdev)
- {
- char *s;
-
- *loop = 0;
- while ((s = strsep(&arg, ",")) != NULL) {
- char *opt = s;
- unsigned int i;
- int res, no = s[0] == 'n' && s[1] == 'o';
- if (no)
- s += 2;
- if (strncmp(s, "loop=", 5) == 0) {
- *loop = 1;
- strlcpy(loopdev, s + 5, LOOPDEV_MAXLEN);
- continue;
- }
- if (strcmp(s, "loop") == 0) {
- *loop = 1;
- strlcpy(loopdev, DEFAULT_LOOP_DEVICE, LOOPDEV_MAXLEN);
- continue;
- }
- for (i = 0, res = 1; i < ARRAY_SIZE(options); i++) {
- res = strcmp(s, options[i].str);
- if (res == 0) {
- rwflag &= ~options[i].rwmask;
- if (no)
- rwflag |= options[i].rwnoset;
- else
- rwflag |= options[i].rwset;
- }
- if (res <= 0)
- break;
- }
- if (res != 0 && s[0])
- add_extra_option(extra, opt);
- }
- return rwflag;
- }
- /*
- * Mark the given block device as read-write, using the BLKROSET ioctl.
- */
- static void fs_set_blk_rw(const char *blockdev)
- {
- int fd;
- int OFF = 0;
- fd = open(blockdev, O_RDONLY);
- if (fd < 0) {
- // should never happen
- return;
- }
- ioctl(fd, BLKROSET, &OFF);
- close(fd);
- }
- static char *progname;
- static struct extra_opts extra;
- static unsigned long rwflag;
- static int
- do_mount(char *dev, char *dir, char *type, unsigned long rwflag, void *data, int loop,
- char *loopdev)
- {
- char *s;
- int error = 0;
- if (loop) {
- int file_fd, device_fd;
- int flags;
- flags = (rwflag & MS_RDONLY) ? O_RDONLY : O_RDWR;
-
- file_fd = open(dev, flags);
- if (file_fd < 0) {
- perror("open backing file failed");
- return 1;
- }
- device_fd = open(loopdev, flags);
- if (device_fd < 0) {
- perror("open loop device failed");
- close(file_fd);
- return 1;
- }
- if (ioctl(device_fd, LOOP_SET_FD, file_fd) < 0) {
- perror("ioctl LOOP_SET_FD failed");
- close(file_fd);
- close(device_fd);
- return 1;
- }
- close(file_fd);
- close(device_fd);
- dev = loopdev;
- }
- if ((rwflag & MS_RDONLY) == 0) {
- fs_set_blk_rw(dev);
- }
- while ((s = strsep(&type, ",")) != NULL) {
- retry:
- if (mount(dev, dir, s, rwflag, data) == -1) {
- error = errno;
- /*
- * If the filesystem is not found, or the
- * superblock is invalid, try the next.
- */
- if (error == ENODEV || error == EINVAL)
- continue;
- /*
- * If we get EACCESS, and we're trying to
- * mount readwrite and this isn't a remount,
- * try read only.
- */
- if (error == EACCES &&
- (rwflag & (MS_REMOUNT|MS_RDONLY)) == 0) {
- rwflag |= MS_RDONLY;
- goto retry;
- }
- break;
- }
- }
- if (error) {
- errno = error;
- perror("mount");
- return 255;
- }
- return 0;
- }
- static int print_mounts()
- {
- FILE* f;
- int length;
- char buffer[100];
-
- f = fopen("/proc/mounts", "r");
- if (!f) {
- fprintf(stdout, "could not open /proc/mounts\n");
- return -1;
- }
- do {
- length = fread(buffer, 1, 100, f);
- if (length > 0)
- fwrite(buffer, 1, length, stdout);
- } while (length > 0);
- fclose(f);
- return 0;
- }
- static int get_mounts_dev_dir(const char *arg, char **dev, char **dir)
- {
- FILE *f;
- char mount_dev[256];
- char mount_dir[256];
- char mount_type[256];
- char mount_opts[256];
- int mount_freq;
- int mount_passno;
- int match;
- f = fopen("/proc/mounts", "r");
- if (!f) {
- fprintf(stdout, "could not open /proc/mounts\n");
- return -1;
- }
- do {
- match = fscanf(f, "%255s %255s %255s %255s %d %d\n",
- mount_dev, mount_dir, mount_type,
- mount_opts, &mount_freq, &mount_passno);
- mount_dev[255] = 0;
- mount_dir[255] = 0;
- mount_type[255] = 0;
- mount_opts[255] = 0;
- if (match == 6 &&
- (strcmp(arg, mount_dev) == 0 ||
- strcmp(arg, mount_dir) == 0)) {
- *dev = strdup(mount_dev);
- *dir = strdup(mount_dir);
- fclose(f);
- return 0;
- }
- } while (match != EOF);
- fclose(f);
- return -1;
- }
- int main(int argc, char *argv[])
- {
- char *type = NULL;
- char *dev = NULL;
- char *dir = NULL;
- int c;
- int loop = 0;
- char loopdev[LOOPDEV_MAXLEN];
- progname = argv[0];
- rwflag = MS_SILENT;
-
- // mount with no arguments is equivalent to "cat /proc/mounts"
- if (argc == 1) return print_mounts();
- do {
- c = getopt(argc, argv, "o:rt:w");
- if (c == EOF)
- break;
- switch (c) {
- case 'o':
- rwflag = parse_mount_options(optarg, rwflag, &extra, &loop, loopdev);
- break;
- case 'r':
- rwflag |= MS_RDONLY;
- break;
- case 't':
- type = optarg;
- break;
- case 'w':
- rwflag &= ~MS_RDONLY;
- break;
- case '?':
- fprintf(stderr, "%s: invalid option -%c\n",
- progname, optopt);
- exit(1);
- }
- } while (1);
- /*
- * If remount, bind or move was specified, then we don't
- * have a "type" as such. Use the dummy "none" type.
- */
- if (rwflag & MS_TYPE)
- type = "none";
- if (optind + 2 == argc) {
- dev = argv[optind];
- dir = argv[optind + 1];
- } else if (optind + 1 == argc && rwflag & MS_REMOUNT) {
- get_mounts_dev_dir(argv[optind], &dev, &dir);
- }
- if (dev == NULL || dir == NULL || type == NULL) {
- fprintf(stderr, "Usage: %s [-r] [-w] [-o options] [-t type] "
- "device directory\n", progname);
- exit(1);
- }
- return do_mount(dev, dir, type, rwflag, extra.str, loop, loopdev);
- /* We leak dev and dir in some cases, but we're about to exit */
- }
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