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