*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
+//config:config UMOUNT
+//config: bool "umount (4.5 kb)"
+//config: default y
+//config: select PLATFORM_LINUX
+//config: help
+//config: When you want to remove a mounted filesystem from its current mount
+//config: point, for example when you are shutting down the system, the
+//config: 'umount' utility is the tool to use. If you enabled the 'mount'
+//config: utility, you almost certainly also want to enable 'umount'.
+//config:
+//config:config FEATURE_UMOUNT_ALL
+//config: bool "Support -a (unmount all)"
+//config: default y
+//config: depends on UMOUNT
+//config: help
+//config: Support -a option to unmount all currently mounted filesystems.
+
+//applet:IF_UMOUNT(APPLET_NOEXEC(umount, umount, BB_DIR_BIN, BB_SUID_DROP, umount))
+/*
+ * On one hand, in some weird situations you'd want umount
+ * to not do anything surprising, to behave as a usual fork+execed executable.
+ *
+ * OTOH, there can be situations where execing would not succeed, or even hang
+ * (say, if executable is on a filesystem which is in trouble and accesses to it
+ * block in kernel).
+ * In this case, you might be actually happy if your standalone bbox shell
+ * does not fork+exec, but only forks and calls umount_main() which it already has!
+ * Let's go with NOEXEC.
+ *
+ * bb_common_bufsiz1 usage here is safe wrt NOEXEC: not expecting it to be zeroed.
+ */
+
+//kbuild:lib-$(CONFIG_UMOUNT) += umount.o
//usage:#define umount_trivial_usage
//usage: "[OPTIONS] FILESYSTEM|DIRECTORY"
//usage: "\n -l Lazy umount (detach filesystem)"
//usage: "\n -f Force umount (i.e., unreachable NFS server)"
//usage: IF_FEATURE_MOUNT_LOOP(
-//usage: "\n -D Don't free loop device even if it has been used"
+//usage: "\n -d Free loop device if it has been used"
//usage: )
+//usage: "\n -t FSTYPE[,...] Unmount only these filesystem type(s)"
//usage:
//usage:#define umount_example_usage
//usage: "$ umount /dev/hdc1\n"
#include <mntent.h>
#include <sys/mount.h>
+#ifndef MNT_DETACH
+# define MNT_DETACH 0x00000002
+#endif
#include "libbb.h"
+#include "common_bufsiz.h"
#if defined(__dietlibc__)
// TODO: This does not belong here.
}
#endif
-/* Ignored: -v -t -i
- * bbox always acts as if -d is present.
- * -D can be used to suppress it (bbox extension).
- * Rationale:
- * (1) util-linux's umount does it if "loop=..." is seen in /etc/mtab:
- * thus, on many systems, bare umount _does_ drop loop devices.
- * (2) many users request this feature.
- */
-#define OPTION_STRING "fldDnra" "vt:i"
+/* ignored: -c -v -i */
+#define OPTION_STRING "fldnrat:" "cvi"
#define OPT_FORCE (1 << 0) // Same as MNT_FORCE
#define OPT_LAZY (1 << 1) // Same as MNT_DETACH
-//#define OPT_FREE_LOOP (1 << 2) // -d is assumed always present
-#define OPT_DONT_FREE_LOOP (1 << 3)
-#define OPT_NO_MTAB (1 << 4)
-#define OPT_REMOUNT (1 << 5)
-#define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 6) : 0)
+#define OPT_FREELOOP (1 << 2)
+#define OPT_NO_MTAB (1 << 3)
+#define OPT_REMOUNT (1 << 4)
+#define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 5) : 0)
int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int umount_main(int argc UNUSED_PARAM, char **argv)
argv += optind;
// MNT_FORCE and MNT_DETACH (from linux/fs.h) must match
- // OPT_FORCE and OPT_LAZY, otherwise this trick won't work:
- doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
+ // OPT_FORCE and OPT_LAZY.
+ BUILD_BUG_ON(OPT_FORCE != MNT_FORCE || OPT_LAZY != MNT_DETACH);
+ doForce = opt & (OPT_FORCE|OPT_LAZY);
/* Get a list of mount points from mtab. We read them all in now mostly
* for umount -a (so we don't have to worry about the list changing while
if (opt & OPT_ALL)
bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file);
} else {
- while (getmntent_r(fp, &me, bb_common_bufsiz1, sizeof(bb_common_bufsiz1))) {
- /* Match fstype if passed */
- if (!match_fstype(&me, fstype))
+ setup_common_bufsiz();
+ while (getmntent_r(fp, &me, bb_common_bufsiz1, COMMON_BUFSIZE)) {
+ /* Match fstype (fstype==NULL matches always) */
+ if (!fstype_matches(me.mnt_type, fstype))
continue;
m = xzalloc(sizeof(*m));
m->next = mtl;
}
// If we're not umounting all, we need at least one argument.
- if (!(opt & OPT_ALL) && !fstype) {
+ // Note: "-t FSTYPE" does not imply -a.
+ if (!(opt & OPT_ALL)) {
if (!argv[0])
bb_show_usage();
m = NULL;
// umount the directory even if we were given the block device.
if (m) zapit = m->dir;
+// umount from util-linux 2.22.2 does not do this:
+// umount -f uses umount2(MNT_FORCE) immediately,
+// not trying umount() first.
+// (Strangely, umount -fl ignores -f: it is equivalent to umount -l.
+// We do pass both flags in this case)
+#if 0
// Let's ask the thing nicely to unmount.
curstat = umount(zapit);
- // Force the unmount, if necessary.
+ // Unmount with force and/or lazy flags, if necessary.
if (curstat && doForce)
+#endif
curstat = umount2(zapit, doForce);
// If still can't umount, maybe remount read-only?
bb_error_msg(msg, m->device);
} else {
status = EXIT_FAILURE;
- bb_perror_msg("can't %sumount %s", (doForce ? "forcibly " : ""), zapit);
+ bb_perror_msg("can't unmount %s", zapit);
}
} else {
// De-allocate the loop device. This ioctl should be ignored on
// any non-loop block devices.
- if (ENABLE_FEATURE_MOUNT_LOOP && !(opt & OPT_DONT_FREE_LOOP) && m)
+ if (ENABLE_FEATURE_MOUNT_LOOP && (opt & OPT_FREELOOP) && m)
del_loop(m->device);
if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
erase_mtab(m->dir);