/* vi: set sw=4 ts=4: */ /* * Mini umount implementation for busybox * * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org> * Copyright (C) 2005 by Rob Landley <rob@landley.net> * * 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 option -a" //config: default y //config: depends on UMOUNT //config: help //config: Support -a option to unmount all currently mounted filesystems. //applet:IF_UMOUNT(APPLET(umount, BB_DIR_BIN, BB_SUID_DROP)) //kbuild:lib-$(CONFIG_UMOUNT) += umount.o //usage:#define umount_trivial_usage //usage: "[OPTIONS] FILESYSTEM|DIRECTORY" //usage:#define umount_full_usage "\n\n" //usage: "Unmount file systems\n" //usage: IF_FEATURE_UMOUNT_ALL( //usage: "\n -a Unmount all file systems" IF_FEATURE_MTAB_SUPPORT(" in /etc/mtab") //usage: ) //usage: IF_FEATURE_MTAB_SUPPORT( //usage: "\n -n Don't erase /etc/mtab entries" //usage: ) //usage: "\n -r Try to remount devices as read-only if mount is busy" //usage: "\n -l Lazy umount (detach filesystem)" //usage: "\n -f Force umount (i.e., unreachable NFS server)" //usage: IF_FEATURE_MOUNT_LOOP( //usage: "\n -d Free loop device if it has been used" //usage: ) //usage: //usage:#define umount_example_usage //usage: "$ 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, char* buffer UNUSED_PARAM, int bufsize UNUSED_PARAM) { struct mntent* ment = getmntent(stream); return memcpy(result, ment, sizeof(*ment)); } #endif /* ignored: -v -t -i */ #define OPTION_STRING "fldnra" "vt:i" #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) int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int umount_main(int argc UNUSED_PARAM, char **argv) { int doForce; struct mntent me; FILE *fp; char *fstype = NULL; int status = EXIT_SUCCESS; unsigned opt; struct mtab_list { char *dir; char *device; struct mtab_list *next; } *mtl, *m; opt = getopt32(argv, OPTION_STRING, &fstype); //argc -= optind; argv += optind; // 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 * we iterate over it, or about getting stuck in a loop on the same failing * entry. Notice that this also naturally reverses the list so that -a * umounts the most recent entries first. */ m = mtl = NULL; // If we're umounting all, then m points to the start of the list and // the argument list should be empty (which will match all). fp = setmntent(bb_path_mtab_file, "r"); if (!fp) { if (opt & OPT_ALL) bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file); } else { 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; m->device = xstrdup(me.mnt_fsname); m->dir = xstrdup(me.mnt_dir); mtl = m; } endmntent(fp); } // If we're not umounting all, we need at least one argument. if (!(opt & OPT_ALL) && !fstype) { if (!argv[0]) bb_show_usage(); m = NULL; } // Loop through everything we're supposed to umount, and do so. for (;;) { int curstat; char *zapit = *argv; char *path; // Do we already know what to umount this time through the loop? if (m) path = xstrdup(m->dir); // For umount -a, end of mtab means time to exit. else if (opt & OPT_ALL) break; // Use command line argument (and look it up in mtab list) else { if (!zapit) break; argv++; 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); // 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? if (curstat) { if ((opt & OPT_REMOUNT) && errno == EBUSY && m) { // Note! Even if we succeed here, later we should not // free loop device or erase mtab entry! const char *msg = "%s busy - remounted read-only"; curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL); if (curstat) { msg = "can't remount %s read-only"; status = EXIT_FAILURE; } bb_error_msg(msg, m->device); } else { status = EXIT_FAILURE; 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_FREELOOP) && m) del_loop(m->device); if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m) erase_mtab(m->dir); } // 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) // 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 if (ENABLE_FEATURE_CLEAN_UP) { while (mtl) { m = mtl->next; free(mtl->device); free(mtl->dir); free(mtl); mtl = m; } } return status; }