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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]))
// FIXME - only one loop mount is supported at a time
#define LOOP_DEVICE "/dev/block/loop0"
struct mount_opts {
const char str[8];
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 },
{ "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_VERBOSE, MS_VERBOSE, 0 },
};
static void add_extra_option(struct extra_opts *extra, char *s)
{
int len = strlen(s);
int newlen = extra->used_size + len;
if (extra->str)
len++; /* +1 for ',' */
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;
}
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 *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 (strcmp(s, "loop") == 0) {
*loop = 1;
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;
}
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 *s;
int error = 0;
if (loop) {
int file_fd, device_fd;
int flags;
flags = (rwflag & MS_RDONLY) ? O_RDONLY : O_RDWR;
// FIXME - only one loop mount supported at a time
file_fd = open(dev, flags);
if (file_fd < -1) {
perror("open backing file failed");
return 1;
}
device_fd = open(LOOP_DEVICE, flags);
if (device_fd < -1) {
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 = LOOP_DEVICE;
}
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;
}
int mount_main(int argc, char *argv[])
{
char *type = NULL;
int c;
int loop = 0;
progname = argv[0];
rwflag = MS_VERBOSE;
// 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);
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 || type == NULL) {
fprintf(stderr, "Usage: %s [-r] [-w] [-o options] [-t type] "
"device directory\n", progname);
exit(1);
}
return do_mount(argv[optind], argv[optind + 1], type, rwflag,
extra.str, loop);
}
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