1/* vi: set sw=4 ts=4: */ 2/* 3 * Mini umount implementation for busybox 4 * 5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org> 6 * Copyright (C) 2005 by Rob Landley <rob@landley.net> 7 * 8 * Licensed under GPL version 2, see file LICENSE in this tarball for details. 9 */ 10 11#include <mntent.h> 12#include <getopt.h> 13#include "libbb.h" 14 15#define OPTION_STRING "flDnravdt:" 16#define OPT_FORCE 1 17#define OPT_LAZY 2 18#define OPT_DONTFREELOOP 4 19#define OPT_NO_MTAB 8 20#define OPT_REMOUNT 16 21#define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? 32 : 0) 22 23int umount_main(int argc, char **argv); 24int umount_main(int argc, char **argv) 25{ 26 int doForce; 27 char path[2*PATH_MAX]; 28 struct mntent me; 29 FILE *fp; 30 char *fstype = 0; 31 int status = EXIT_SUCCESS; 32 unsigned opt; 33 struct mtab_list { 34 char *dir; 35 char *device; 36 struct mtab_list *next; 37 } *mtl, *m; 38 39 /* Parse any options */ 40 41 opt = getopt32(argv, OPTION_STRING, &fstype); 42 43 argc -= optind; 44 argv += optind; 45 46 doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY)); 47 48 /* Get a list of mount points from mtab. We read them all in now mostly 49 * for umount -a (so we don't have to worry about the list changing while 50 * we iterate over it, or about getting stuck in a loop on the same failing 51 * entry. Notice that this also naturally reverses the list so that -a 52 * umounts the most recent entries first. */ 53 54 m = mtl = 0; 55 56 /* If we're umounting all, then m points to the start of the list and 57 * the argument list should be empty (which will match all). */ 58 59 fp = setmntent(bb_path_mtab_file, "r"); 60 if (!fp) { 61 if (opt & OPT_ALL) 62 bb_error_msg_and_die("cannot open %s", bb_path_mtab_file); 63 } else { 64 while (getmntent_r(fp, &me, path, sizeof(path))) { 65 /* Match fstype if passed */ 66 if (fstype && match_fstype(&me, fstype)) 67 continue; 68 m = xmalloc(sizeof(struct mtab_list)); 69 m->next = mtl; 70 m->device = xstrdup(me.mnt_fsname); 71 m->dir = xstrdup(me.mnt_dir); 72 mtl = m; 73 } 74 endmntent(fp); 75 } 76 77 /* If we're not umounting all, we need at least one argument. */ 78 if (!(opt & OPT_ALL) && !fstype) { 79 m = 0; 80 if (!argc) bb_show_usage(); 81 } 82 83 // Loop through everything we're supposed to umount, and do so. 84 for (;;) { 85 int curstat; 86 char *zapit = *argv; 87 88 // Do we already know what to umount this time through the loop? 89 if (m) safe_strncpy(path, m->dir, PATH_MAX); 90 // For umount -a, end of mtab means time to exit. 91 else if (opt & OPT_ALL) break; 92 // Get next command line argument (and look it up in mtab list) 93 else if (!argc--) break; 94 else { 95 argv++; 96 realpath(zapit, path); 97 for (m = mtl; m; m = m->next) 98 if (!strcmp(path, m->dir) || !strcmp(path, m->device)) 99 break; 100 } 101 // If we couldn't find this sucker in /etc/mtab, punt by passing our 102 // command line argument straight to the umount syscall. Otherwise, 103 // umount the directory even if we were given the block device. 104 if (m) zapit = m->dir; 105 106 // Let's ask the thing nicely to unmount. 107 curstat = umount(zapit); 108 109 // Force the unmount, if necessary. 110 if (curstat && doForce) { 111 curstat = umount2(zapit, doForce); 112 if (curstat) 113 bb_error_msg("forced umount of %s failed!", zapit); 114 } 115 116 // If still can't umount, maybe remount read-only? 117 if (curstat && (opt & OPT_REMOUNT) && errno == EBUSY && m) { 118 curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL); 119 bb_error_msg(curstat ? "cannot remount %s read-only" : 120 "%s busy - remounted read-only", m->device); 121 } 122 123 if (curstat) { 124 status = EXIT_FAILURE; 125 bb_perror_msg("cannot umount %s", zapit); 126 } else { 127 /* De-allocate the loop device. This ioctl should be ignored on 128 * any non-loop block devices. */ 129 if (ENABLE_FEATURE_MOUNT_LOOP && !(opt & OPT_DONTFREELOOP) && m) 130 del_loop(m->device); 131 if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m) 132 erase_mtab(m->dir); 133 } 134 135 // Find next matching mtab entry for -a or umount /dev 136 // Note this means that "umount /dev/blah" will unmount all instances 137 // of /dev/blah, not just the most recent. 138 while (m && (m = m->next)) 139 if ((opt & OPT_ALL) || !strcmp(path, m->device)) 140 break; 141 } 142 143 // Free mtab list if necessary 144 145 if (ENABLE_FEATURE_CLEAN_UP) { 146 while (mtl) { 147 m = mtl->next; 148 free(mtl->device); 149 free(mtl->dir); 150 free(mtl); 151 mtl = m; 152 } 153 } 154 155 return status; 156} 157