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Unmount utility program for Linux CIFS VFS (virtual filesystem) client
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Copyright (C) 2005 Steve French (sfrench@us.ibm.com)
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <sys/types.h>
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#include <sys/mount.h>
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#include <sys/ioctl.h>
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#define UNMOUNT_CIFS_VERSION_MAJOR "0"
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#define UNMOUNT_CIFS_VERSION_MINOR "6"
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#ifndef UNMOUNT_CIFS_VENDOR_SUFFIX
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#include "include/version.h"
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#ifdef SAMBA_VERSION_VENDOR_SUFFIX
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#define UNMOUNT_CIFS_VENDOR_SUFFIX "-"SAMBA_VERSION_OFFICIAL_STRING"-"SAMBA_VERSION_VENDOR_SUFFIX
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#define UNMOUNT_CIFS_VENDOR_SUFFIX "-"SAMBA_VERSION_OFFICIAL_STRING
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#endif /* SAMBA_VERSION_OFFICIAL_STRING and SAMBA_VERSION_VENDOR_SUFFIX */
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#define UNMOUNT_CIFS_VENDOR_SUFFIX ""
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#endif /* _SAMBA_BUILD_ */
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#endif /* UNMOUNT_CIFS_VENDOR_SUFFIX */
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#define MNT_DETACH 0x02
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#define MNT_EXPIRE 0x04
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#define MOUNTED_LOCK "/etc/mtab~"
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#define MOUNTED_TEMP "/etc/mtab.tmp"
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#define CIFS_IOC_CHECKUMOUNT _IO(0xCF, 2)
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#define CIFS_MAGIC_NUMBER 0xFF534D42 /* the first four bytes of SMB PDU */
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static struct option longopts[] = {
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{ "all", 0, NULL, 'a' },
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{ "help",0, NULL, 'h' },
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{ "read-only", 0, NULL, 'r' },
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{ "ro", 0, NULL, 'r' },
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{ "verbose", 0, NULL, 'v' },
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{ "version", 0, NULL, 'V' },
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{ "expire", 0, NULL, 'e' },
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{ "force", 0, 0, 'f' },
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{ "lazy", 0, 0, 'l' },
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{ "no-mtab", 0, 0, 'n' },
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const char * thisprogram;
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static void umount_cifs_usage(void)
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printf("\nUsage: %s <remotetarget> <dir>\n", thisprogram);
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printf("\nUnmount the specified directory\n");
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printf("\nLess commonly used options:");
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printf("\n\t-r\tIf mount fails, retry with readonly remount.");
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printf("\n\t-n\tDo not write to mtab.");
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printf("\n\t-f\tAttempt a forced unmount, even if the fs is busy.");
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printf("\n\t-l\tAttempt lazy unmount, Unmount now, cleanup later.");
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printf("\n\t-v\tEnable verbose mode (may be useful for debugging).");
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printf("\n\t-h\tDisplay this help.");
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printf("\n\nOptions are described in more detail in the manual page");
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printf("\n\tman 8 umount.cifs\n");
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printf("\nTo display the version number of the cifs umount utility:");
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printf("\n\t%s -V\n",thisprogram);
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printf("\nInvoking the umount utility on cifs mounts, can execute");
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printf(" /sbin/umount.cifs (if present and umount -i is not specified.\n");
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static int umount_check_perm(char * dir)
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/* allow root to unmount, no matter what */
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/* presumably can not chdir into the target as we do on mount */
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fileid = open(dir, O_RDONLY | O_DIRECTORY | O_NOFOLLOW, 0);
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printf("error opening mountpoint %d %s",errno,strerror(errno));
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rc = ioctl(fileid, CIFS_IOC_CHECKUMOUNT, NULL);
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printf("ioctl returned %d with errno %d %s\n",rc,errno,strerror(errno));
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printf("user unmounting via %s is an optional feature of",thisprogram);
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printf(" the cifs filesystem driver (cifs.ko)");
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printf("\n\tand requires cifs.ko version 1.32 or later\n");
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printf("user unmount of %s failed with %d %s\n",dir,errno,strerror(errno));
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static int remove_from_mtab(char * mountpoint)
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struct mntent * mount_entry;
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/* If it is a symlink, e.g. to /proc/mounts, no need to update it. */
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if ((lstat(MOUNTED, &statbuf) == 0) && (S_ISLNK(statbuf.st_mode)))
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/* Do we first need to check if it is writable? */
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printf("Mount table locked\n");
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printf("attempting to remove from mtab\n");
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org_fd = setmntent(MOUNTED, "r");
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printf("Can not open %s\n",MOUNTED);
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new_fd = setmntent(MOUNTED_TEMP,"w");
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printf("Can not open temp file %s", MOUNTED_TEMP);
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/* BB fix so we only remove the last entry that matches BB */
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while((mount_entry = getmntent(org_fd)) != NULL) {
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if(strcmp(mount_entry->mnt_dir, mountpoint) == 0) {
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printf("%d matching entries in mount table\n", num_matches);
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/* Is there a better way to seek back to the first entry in mtab? */
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org_fd = setmntent(MOUNTED, "r");
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printf("Can not open %s\n",MOUNTED);
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while((mount_entry = getmntent(org_fd)) != NULL) {
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if(strcmp(mount_entry->mnt_dir, mountpoint) != 0) {
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addmntent(new_fd, mount_entry);
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if(num_matches != 1) {
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addmntent(new_fd, mount_entry);
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} else if(verboseflg)
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printf("entry not copied (ie entry is removed)\n");
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printf("done updating tmp file\n");
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rc = fchmod (fileno (new_fd), S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
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printf("error %s changing mode of %s\n", strerror(errno),
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rc = rename(MOUNTED_TEMP, MOUNTED);
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printf("failure %s renaming %s to %s\n",strerror(errno),
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MOUNTED_TEMP, MOUNTED);
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/* Make a canonical pathname from PATH. Returns a freshly malloced string.
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It is up the *caller* to ensure that the PATH is sensible. i.e.
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canonicalize ("/dev/fd0/.") returns "/dev/fd0" even though ``/dev/fd0/.''
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is not a legal pathname for ``/dev/fd0'' Anything we cannot parse
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we return unmodified. */
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canonicalize(char *path)
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if (strlen(path) > PATH_MAX) {
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fprintf(stderr, "Mount point string too long\n");
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canonical = (char *)malloc (PATH_MAX + 1);
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fprintf(stderr, "Error! Not enough memory!\n");
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if (realpath (path, canonical))
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strncpy (canonical, path, PATH_MAX);
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canonical[PATH_MAX] = '\0';
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int main(int argc, char ** argv)
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int retry_remount = 0;
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struct statfs statbuf;
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thisprogram = argv[0];
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if(thisprogram == NULL)
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thisprogram = "umount.cifs";
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/* add sharename in opts string as unc= parm */
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while ((c = getopt_long (argc, argv, "afhilnrvV",
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longopts, NULL)) != -1) {
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/* No code to do the following option yet */
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flags |= MNT_DETACH; /* lazy unmount */
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flags |= MNT_EXPIRE; /* gradually timeout */
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printf ("umount.cifs version: %s.%s%s\n",
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UNMOUNT_CIFS_VERSION_MAJOR,
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UNMOUNT_CIFS_VERSION_MINOR,
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UNMOUNT_CIFS_VENDOR_SUFFIX);
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printf("unknown unmount option %c\n",c);
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/* move past the umount options */
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mountpoint = canonicalize(argv[0]);
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if((argc < 1) || (argv[0] == NULL)) {
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printf("\nMissing name of unmount directory\n");
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printf("optind %d unmount dir %s\n",optind, mountpoint);
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/* check if running effectively root */
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printf("Trying to unmount when %s not installed suid\n",thisprogram);
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printf("euid = %d\n",geteuid());
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/* fixup path if needed */
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/* Trim any trailing slashes */
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while ((strlen(mountpoint) > 1) &&
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(mountpoint[strlen(mountpoint)-1] == '/'))
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mountpoint[strlen(mountpoint)-1] = '\0';
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/* make sure that this is a cifs filesystem */
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rc = statfs(mountpoint, &statbuf);
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if(rc || (statbuf.f_type != CIFS_MAGIC_NUMBER)) {
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printf("This utility only unmounts cifs filesystems.\n");
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/* check if our uid was the one who mounted */
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rc = umount_check_perm(mountpoint);
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printf("Not permitted to unmount\n");
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if(umount2(mountpoint, flags)) {
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/* remember to kill daemon on error */
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printf("unmount failed but no error number set\n");
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printf("unmount error %d = %s\n",errno,strerror(errno));
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printf("Refer to the umount.cifs(8) manual page (man 8 umount.cifs)\n");
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printf("umount2 succeeded\n");
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remove_from_mtab(mountpoint);