* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
* Copyright (C) 2005 by Rob Landley <rob@landley.net>
*
- * Licensed under GPL version 2, see file LICENSE in this tarball for details.
+ * 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>
+#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 path = xmalloc(PATH_MAX + 2); /* to save stack */
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
fp = setmntent(bb_path_mtab_file, "r");
if (!fp) {
if (opt & OPT_ALL)
- bb_error_msg_and_die("cannot open %s", bb_path_mtab_file);
+ bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file);
} else {
- while (getmntent_r(fp, &me, path, PATH_MAX)) {
- /* Match fstype if passed */
- if (fstype && 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 = xmalloc(sizeof(struct mtab_list));
+ m = xzalloc(sizeof(*m));
m->next = mtl;
m->device = xstrdup(me.mnt_fsname);
m->dir = xstrdup(me.mnt_dir);
}
// 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;
for (;;) {
int curstat;
char *zapit = *argv;
+ char *path;
// Do we already know what to umount this time through the loop?
if (m)
- safe_strncpy(path, m->dir, PATH_MAX);
+ path = xstrdup(m->dir);
// For umount -a, end of mtab means time to exit.
else if (opt & OPT_ALL)
break;
if (!zapit)
break;
argv++;
- realpath(zapit, path);
- for (m = mtl; m; m = m->next)
- if (!strcmp(path, m->dir) || !strcmp(path, m->device))
- break;
+ path = xmalloc_realpath(zapit);
+ if (path) {
+ for (m = mtl; m; m = m->next)
+ if (strcmp(path, m->dir) == 0 || strcmp(path, m->device) == 0)
+ break;
+ }
}
// If we couldn't find this sucker in /etc/mtab, punt by passing our
// command line argument straight to the umount syscall. Otherwise,
// 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?
const char *msg = "%s busy - remounted read-only";
curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
if (curstat) {
- msg = "cannot remount %s read-only";
+ msg = "can't remount %s read-only";
status = EXIT_FAILURE;
}
bb_error_msg(msg, m->device);
} else {
status = EXIT_FAILURE;
- bb_perror_msg("cannot %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
// Find next matching mtab entry for -a or umount /dev
// Note this means that "umount /dev/blah" will unmount all instances
// of /dev/blah, not just the most recent.
- if (m) while ((m = m->next) != NULL)
- if ((opt & OPT_ALL) || !strcmp(path, m->device))
- break;
+ if (m) {
+ while ((m = m->next) != NULL)
+ // NB: if m is non-NULL, path is non-NULL as well
+ if ((opt & OPT_ALL) || strcmp(path, m->device) == 0)
+ break;
+ }
+ free(path);
}
// Free mtab list if necessary
free(mtl);
mtl = m;
}
- free(path);
}
return status;
projects / oweals / busybox.git / blobdiff