1/* vi: set sw=4 ts=4: */ 2/* 3 * Mini umount implementation for busybox 4 * 5 * 6 * Copyright (C) 1999,2000,2001 by Lineo, inc. 7 * Written by Erik Andersen <andersen@lineo.com>, <andersee@debian.org> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation; either version 2 of the License, or 12 * (at your option) any later version. 13 * 14 * This program is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 17 * General Public License for more details. 18 * 19 * You should have received a copy of the GNU General Public License 20 * along with this program; if not, write to the Free Software 21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 22 * 23 */ 24 25#include <limits.h> 26#include <stdio.h> 27#include <mntent.h> 28#include <errno.h> 29#include <string.h> 30#include <stdlib.h> 31#include "busybox.h" 32 33/* Teach libc5 about realpath -- it includes it but the 34 * prototype is missing... */ 35#if (__GLIBC__ <= 2) && (__GLIBC_MINOR__ < 1) 36extern char *realpath(const char *path, char *resolved_path); 37#endif 38 39static const int MNT_FORCE = 1; 40static const int MS_MGC_VAL = 0xc0ed0000; /* Magic number indicatng "new" flags */ 41static const int MS_REMOUNT = 32; /* Alter flags of a mounted FS. */ 42static const int MS_RDONLY = 1; /* Mount read-only. */ 43 44extern int mount (__const char *__special_file, __const char *__dir, 45 __const char *__fstype, unsigned long int __rwflag, 46 __const void *__data); 47extern int umount (__const char *__special_file); 48extern int umount2 (__const char *__special_file, int __flags); 49 50struct _mtab_entry_t { 51 char *device; 52 char *mountpt; 53 struct _mtab_entry_t *next; 54}; 55 56static struct _mtab_entry_t *mtab_cache = NULL; 57 58 59 60#if defined BB_FEATURE_MOUNT_FORCE 61static int doForce = FALSE; 62#endif 63#if defined BB_FEATURE_MOUNT_LOOP 64static int freeLoop = TRUE; 65#endif 66#if defined BB_FEATURE_MTAB_SUPPORT 67static int useMtab = TRUE; 68#endif 69static int umountAll = FALSE; 70static int doRemount = FALSE; 71extern const char mtab_file[]; /* Defined in utility.c */ 72 73 74 75/* These functions are here because the getmntent functions do not appear 76 * to be re-entrant, which leads to all sorts of problems when we try to 77 * use them recursively - randolph 78 * 79 * TODO: Perhaps switch to using Glibc's getmntent_r 80 * -Erik 81 */ 82static void mtab_read(void) 83{ 84 struct _mtab_entry_t *entry = NULL; 85 struct mntent *e; 86 FILE *fp; 87 88 if (mtab_cache != NULL) 89 return; 90 91 if ((fp = setmntent(mtab_file, "r")) == NULL) { 92 error_msg("Cannot open %s", mtab_file); 93 return; 94 } 95 while ((e = getmntent(fp))) { 96 entry = xmalloc(sizeof(struct _mtab_entry_t)); 97 entry->device = strdup(e->mnt_fsname); 98 entry->mountpt = strdup(e->mnt_dir); 99 entry->next = mtab_cache; 100 mtab_cache = entry; 101 } 102 endmntent(fp); 103} 104 105static char *mtab_getinfo(const char *match, const char which) 106{ 107 struct _mtab_entry_t *cur = mtab_cache; 108 109 while (cur) { 110 if (strcmp(cur->mountpt, match) == 0 || 111 strcmp(cur->device, match) == 0) { 112 if (which == MTAB_GETMOUNTPT) { 113 return cur->mountpt; 114 } else { 115#if !defined BB_FEATURE_MTAB_SUPPORT 116 if (strcmp(cur->device, "/dev/root") == 0) { 117 /* Adjusts device to be the real root device, 118 * or leaves device alone if it can't find it */ 119 cur->device = find_real_root_device_name(cur->device); 120 } 121#endif 122 return cur->device; 123 } 124 } 125 cur = cur->next; 126 } 127 return NULL; 128} 129 130static char *mtab_next(void **iter) 131{ 132 char *mp; 133 134 if (iter == NULL || *iter == NULL) 135 return NULL; 136 mp = ((struct _mtab_entry_t *) (*iter))->mountpt; 137 *iter = (void *) ((struct _mtab_entry_t *) (*iter))->next; 138 return mp; 139} 140 141static char *mtab_first(void **iter) 142{ 143 struct _mtab_entry_t *mtab_iter; 144 145 if (!iter) 146 return NULL; 147 mtab_iter = mtab_cache; 148 *iter = (void *) mtab_iter; 149 return mtab_next(iter); 150} 151 152/* Don't bother to clean up, since exit() does that 153 * automagically, so we can save a few bytes */ 154#ifdef BB_FEATURE_CLEAN_UP 155static void mtab_free(void) 156{ 157 struct _mtab_entry_t *this, *next; 158 159 this = mtab_cache; 160 while (this) { 161 next = this->next; 162 if (this->device) 163 free(this->device); 164 if (this->mountpt) 165 free(this->mountpt); 166 free(this); 167 this = next; 168 } 169} 170#endif 171 172static int do_umount(const char *name) 173{ 174 int status; 175 char *blockDevice = mtab_getinfo(name, MTAB_GETDEVICE); 176 177 if (blockDevice && strcmp(blockDevice, name) == 0) 178 name = mtab_getinfo(blockDevice, MTAB_GETMOUNTPT); 179 180 status = umount(name); 181 182#if defined BB_FEATURE_MOUNT_LOOP 183 if (freeLoop == TRUE && blockDevice != NULL && !strncmp("/dev/loop", blockDevice, 9)) 184 /* this was a loop device, delete it */ 185 del_loop(blockDevice); 186#endif 187#if defined BB_FEATURE_MOUNT_FORCE 188 if (status != 0 && doForce == TRUE) { 189 status = umount2(blockDevice, MNT_FORCE); 190 if (status != 0) { 191 error_msg_and_die("forced umount of %s failed!", blockDevice); 192 } 193 } 194#endif 195 if (status != 0 && doRemount == TRUE && errno == EBUSY) { 196 status = mount(blockDevice, name, NULL, 197 MS_MGC_VAL | MS_REMOUNT | MS_RDONLY, NULL); 198 if (status == 0) { 199 error_msg("%s busy - remounted read-only", blockDevice); 200 } else { 201 error_msg("Cannot remount %s read-only", blockDevice); 202 } 203 } 204 if (status == 0) { 205#if defined BB_FEATURE_MTAB_SUPPORT 206 if (useMtab == TRUE) 207 erase_mtab(name); 208#endif 209 return (TRUE); 210 } 211 return (FALSE); 212} 213 214static int umount_all(void) 215{ 216 int status = TRUE; 217 char *mountpt; 218 void *iter; 219 220 for (mountpt = mtab_first(&iter); mountpt; mountpt = mtab_next(&iter)) { 221 /* Never umount /proc on a umount -a */ 222 if (strstr(mountpt, "proc")!= NULL) 223 continue; 224 if (!do_umount(mountpt)) { 225 /* Don't bother retrying the umount on busy devices */ 226 if (errno == EBUSY) { 227 perror_msg("%s", mountpt); 228 status = FALSE; 229 continue; 230 } 231 if (!do_umount(mountpt)) { 232 printf("Couldn't umount %s on %s: %s\n", 233 mountpt, mtab_getinfo(mountpt, MTAB_GETDEVICE), 234 strerror(errno)); 235 status = FALSE; 236 } 237 } 238 } 239 return (status); 240} 241 242extern int umount_main(int argc, char **argv) 243{ 244 char path[PATH_MAX]; 245 246 if (argc < 2) { 247 show_usage(); 248 } 249#ifdef BB_FEATURE_CLEAN_UP 250 atexit(mtab_free); 251#endif 252 253 /* Parse any options */ 254 while (--argc > 0 && **(++argv) == '-') { 255 while (*++(*argv)) 256 switch (**argv) { 257 case 'a': 258 umountAll = TRUE; 259 break; 260#if defined BB_FEATURE_MOUNT_LOOP 261 case 'l': 262 freeLoop = FALSE; 263 break; 264#endif 265#ifdef BB_FEATURE_MTAB_SUPPORT 266 case 'n': 267 useMtab = FALSE; 268 break; 269#endif 270#ifdef BB_FEATURE_MOUNT_FORCE 271 case 'f': 272 doForce = TRUE; 273 break; 274#endif 275 case 'r': 276 doRemount = TRUE; 277 break; 278 case 'v': 279 break; /* ignore -v */ 280 default: 281 show_usage(); 282 } 283 } 284 285 mtab_read(); 286 if (umountAll == TRUE) { 287 if (umount_all() == TRUE) 288 return EXIT_SUCCESS; 289 else 290 return EXIT_FAILURE; 291 } 292 if (realpath(*argv, path) == NULL) 293 perror_msg_and_die("%s", path); 294 if (do_umount(path) == TRUE) 295 return EXIT_SUCCESS; 296 perror_msg_and_die("%s", *argv); 297} 298 299