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/* umount.c - Unmount a mount point.
*
* Copyright 2012 Rob Landley <rob@landley.net>
*
* See http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/umount.html
*
* Note: -n (/etc/mtab) is obsolete, /proc/mounts replaced it. Neither chroot
* nor per-process mount namespaces can work sanely with mtab. The kernel
* tracks mount points now, a userspace application can't do so anymore.
USE_UMOUNT(NEWTOY(umount, "cndDflrat*v[!na]", TOYFLAG_BIN|TOYFLAG_STAYROOT))
config UMOUNT
bool "umount"
default y
help
usage: umount [-a [-t TYPE[,TYPE...]]] [-vrfD] [DIR...]
Unmount the listed filesystems.
-a Unmount all mounts in /proc/mounts instead of command line list
-D Don't free loopback device(s)
-f Force unmount
-l Lazy unmount (detach from filesystem now, close when last user does)
-n Don't use /proc/mounts
-r Remount read only if unmounting fails
-t Restrict "all" to mounts of TYPE (or use "noTYPE" to skip)
-v Verbose
*/
#define FOR_umount
#include "toys.h"
GLOBALS(
struct arg_list *t;
char *types;
)
// todo (done?)
// borrow df code to identify filesystem?
// umount -a from fstab
// umount when getpid() not 0, according to fstab
// lookup mount: losetup -d, bind, file, block
// loopback delete
// fstab -o user
// TODO
// swapon, swapoff
static void do_umount(char *dir, char *dev, int flags)
{
// is it ok for this user to umount this mount?
if (CFG_TOYBOX_SUID && getuid()) {
struct mtab_list *mt = dlist_terminate(xgetmountlist("/etc/fstab"));
int len, user = 0;
while (mt) {
struct mtab_list *mtemp = mt;
char *s;
if (!strcmp(mt->dir, dir)) while ((s = comma_iterate(&mt->opts, &len))) {
if (len == 4 && strncmp(s, "user", 4)) user = 1;
else if (len == 6 && strncmp(s, "nouser", 6)) user = 0;
}
mt = mt->next;
free(mtemp);
}
if (!user) {
error_msg("not root");
return;
}
}
if (!umount2(dir, flags)) {
if (toys.optflags & FLAG_v) xprintf("%s unmounted\n", dir);
// Attempt to disassociate loopback device. This ioctl should be ignored
// for anything else, because lanana allocated ioctl range 'L' to loopback
if (dev && !(toys.optflags & FLAG_D)) {
int lfd = open(dev, O_RDONLY);
if (lfd != -1) {
// This is LOOP_CLR_FD, fetching it from headers is awkward
if (!ioctl(lfd, 0x4C01) && (toys.optflags & FLAG_v))
xprintf("%s cleared\n", dev);
close(lfd);
}
}
return;
}
if (toys.optflags & FLAG_r) {
if (!mount("", dir, "", MS_REMOUNT|MS_RDONLY, "")) {
if (toys.optflags & FLAG_v) xprintf("%s remounted ro\n", dir);
return;
}
}
perror_msg_raw(dir);
}
void umount_main(void)
{
char **optargs, *pm = "/proc/mounts";
struct mtab_list *mlsave = 0, *mlrev = 0, *ml;
int flags=0;
if (!toys.optc && !(toys.optflags & FLAG_a))
error_exit("Need 1 arg or -a");
if (toys.optflags & FLAG_f) flags |= MNT_FORCE;
if (toys.optflags & FLAG_l) flags |= MNT_DETACH;
// Load /proc/mounts and get a reversed list (newest first)
// We use the list both for -a, and to umount /dev/name or do losetup -d
if (!(toys.optflags & FLAG_n) && !access(pm, R_OK))
mlrev = dlist_terminate(mlsave = xgetmountlist(pm));
// Unmount all: loop through mounted filesystems, skip -t, unmount the rest
if (toys.optflags & FLAG_a) {
char *typestr = 0;
struct arg_list *tal;
for (tal = TT.t; tal; tal = tal->next) comma_collate(&typestr, tal->arg);
for (ml = mlrev; ml; ml = ml->prev)
if (mountlist_istype(ml, typestr)) do_umount(ml->dir, ml->device, flags);
if (CFG_TOYBOX_FREE) {
free(typestr);
llist_traverse(mlsave, free);
}
// TODO: under what circumstances do we umount non-absolute path?
} else for (optargs = toys.optargs; *optargs; optargs++) {
char *abs = xabspath(*optargs, 0);
for (ml = abs ? mlrev : 0; ml; ml = ml->prev) {
if (!strcmp(ml->dir, abs)) break;
if (!strcmp(ml->device, abs)) {
free(abs);
abs = ml->dir;
break;
}
}
do_umount(abs ? abs : *optargs, ml ? ml->device : 0, flags);
if (ml && abs != ml->dir) free(abs);
}
}
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