*
* 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-$(CONFIG_UMOUNT) += umount.o
+
+//usage:#define umount_trivial_usage
+//usage: "[OPTIONS] FILESYSTEM|DIRECTORY"
+//usage:#define umount_full_usage "\n\n"
+//usage: "Unmount file systems\n"
+//usage: IF_FEATURE_UMOUNT_ALL(
+//usage: "\n -a Unmount all file systems" IF_FEATURE_MTAB_SUPPORT(" in /etc/mtab")
+//usage: )
+//usage: IF_FEATURE_MTAB_SUPPORT(
+//usage: "\n -n Don't erase /etc/mtab entries"
+//usage: )
+//usage: "\n -r Try to remount devices as read-only if mount is busy"
+//usage: "\n -l Lazy umount (detach filesystem)"
+//usage: "\n -f Force umount (i.e., unreachable NFS server)"
+//usage: IF_FEATURE_MOUNT_LOOP(
+//usage: "\n -d Free loop device if it has been used"
+//usage: )
+//usage: "\n -t FSTYPE[,...] Unmount only these filesystem type(s)"
+//usage:
+//usage:#define umount_example_usage
+//usage: "$ umount /dev/hdc1\n"
+
#include <mntent.h>
#include <sys/mount.h>
-/* Make sure we have all the new mount flags we actually try to use. */
-#ifndef MS_BIND
-# define MS_BIND (1 << 12)
-#endif
-#ifndef MS_MOVE
-# define MS_MOVE (1 << 13)
-#endif
-#ifndef MS_RECURSIVE
-# define MS_RECURSIVE (1 << 14)
-#endif
-#ifndef MS_SILENT
-# define MS_SILENT (1 << 15)
-#endif
-/* The shared subtree stuff, which went in around 2.6.15. */
-#ifndef MS_UNBINDABLE
-# define MS_UNBINDABLE (1 << 17)
-#endif
-#ifndef MS_PRIVATE
-# define MS_PRIVATE (1 << 18)
-#endif
-#ifndef MS_SLAVE
-# define MS_SLAVE (1 << 19)
-#endif
-#ifndef MS_SHARED
-# define MS_SHARED (1 << 20)
-#endif
-#ifndef MS_RELATIME
-# define MS_RELATIME (1 << 21)
+#ifndef MNT_DETACH
+# define MNT_DETACH 0x00000002
#endif
#include "libbb.h"
-
+#include "common_bufsiz.h"
#if defined(__dietlibc__)
+// TODO: This does not belong here.
/* 16.12.2006, Sampo Kellomaki (sampo@iki.fi)
* dietlibc-0.30 does not have implementation of getmntent_r() */
static struct mntent *getmntent_r(FILE* stream, struct mntent* result,
}
#endif
-/* ignored: -v -d -t -i */
-#define OPTION_STRING "fldnra" "vdt:i"
-#define OPT_FORCE (1 << 0)
-#define OPT_LAZY (1 << 1)
+/* 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_FREELOOP (1 << 2)
#define OPT_NO_MTAB (1 << 3)
#define OPT_REMOUNT (1 << 4)
#define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 5) : 0)
-// These constants from linux/fs.h must match OPT_FORCE and OPT_LAZY,
-// otherwise "doForce" trick below won't work!
-//#define MNT_FORCE 0x00000001 /* Attempt to forcibly umount */
-//#define MNT_DETACH 0x00000002 /* Just detach from the tree */
-
int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int umount_main(int argc UNUSED_PARAM, char **argv)
{
int doForce;
- char *const buf = xmalloc(4096); /* reducing stack usage */
struct mntent me;
FILE *fp;
char *fstype = NULL;
opt = getopt32(argv, OPTION_STRING, &fstype);
//argc -= optind;
argv += optind;
- doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
+
+ // MNT_FORCE and MNT_DETACH (from linux/fs.h) must match
+ // 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, buf, PATH_MAX * 2 + 128)) {
- /* 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
free(mtl);
mtl = m;
}
- free(buf);
}
return status;
projects / oweals / busybox.git / blobdiff