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