Attachment #62963 for bug #98403




/*
 * 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
 * - added Native Language Support
 * 1999-03-21 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 * - fixed strerr(errno) in gettext calls
 * 2003-08-08 Thomas Hood <jdthood@yahoo.co.uk>
 * - Write through a symlink at /etc/mtab if it doesn't point into /proc/
 */

#include <unistd.h>

#include <sys/stat.h>
#include "mntent.h"
#include "fstab.h"
#include "realpath.h"
#include "sundries.h"
#include "xmalloc.h"
#include "mount_blkid.h"
#include "paths.h"
#include "nls.h"

#define streq(s, t)	(strcmp ((s), (t)) == 0)

#define PROC_MOUNTS		"/proc/mounts"


/* Information about mtab. ------------------------------------*/
/* A 64 bit number can be displayed in 20 decimal digits */
#define LEN_LARGEST_PID 20
#define MTAB_PATH_MAX (PATH_MAX - (sizeof(MTAB_LOCK_SUFFIX) - 1) - LEN_LARGEST_PID)
static char mtab_path[MTAB_PATH_MAX];
static char mtab_lock_path[PATH_MAX];
static char mtab_lock_targ[PATH_MAX];
static char mtab_temp_path[PATH_MAX];

/*
 * Set mtab_path to the real path of the mtab file
 * or to the null string if that path is inaccessible
 *
 * Run this early
 */
void
get_mtab_info(void) {
	struct stat mtab_stat;

	if (lstat(MOUNTED, &mtab_stat)) {
		/* Assume that the lstat error means that the file does not exist */
		/* (Maybe we should check errno here) */
		strcpy(mtab_path, MOUNTED);
	} else if (S_ISLNK(mtab_stat.st_mode)) {
		/* Is a symlink */
		int len;
		char *r = myrealpath(MOUNTED, mtab_path, MTAB_PATH_MAX);
		mtab_path[MTAB_PATH_MAX - 1] = 0; /* Just to be sure */
		len = strlen(mtab_path);
		if (
			r == NULL
			|| len == 0
			|| len >= (MTAB_PATH_MAX - 1)
			|| streqn(mtab_path, PATH_PROC, sizeof(PATH_PROC) - 1)
		) {
			/* Real path invalid or inaccessible */
			mtab_path[0] = '\0';
			return;
		}
		/* mtab_path now contains mtab's real path */
	} else {
		/* Exists and is not a symlink */
		strcpy(mtab_path, MOUNTED);
	}

	sprintf(mtab_lock_path, "%s%s", mtab_path, MTAB_LOCK_SUFFIX);
	sprintf(mtab_lock_targ, "%s%s%d", mtab_path, MTAB_LOCK_SUFFIX, getpid());
	sprintf(mtab_temp_path, "%s%s", mtab_path, MTAB_TEMP_SUFFIX);

	return;
}

/*
 * Tell whether or not the mtab real path is accessible
 *
 * get_mtab_info() must have been run
 */
static int
mtab_is_accessible(void) {
	return (mtab_path[0] != '\0');
}

/*
 * Tell whether or not the mtab file currently exists
 *
 * Note that the answer here is independent of whether or
 * not the file is writable, so if you are planning to create
 * the mtab file then check mtab_is_writable() too.
 *
 * get_mtab_info() must have been run
 */
int
mtab_does_not_exist(void) {
	struct stat mtab_stat;

	if (!mtab_is_accessible())
		return 1;

	if (lstat(mtab_path, &mtab_stat))
		return 1;

	return 0;
}

/*
 * Tell whether or not mtab is writable (whether or not it currently exists)
 *
 * This depends on whether or not the real path is accessible and,
 * if so, whether or not the file can be opened.  This function
 * has the side effect of creating the file if it is writable.
 *
 * get_mtab_info() must have been run
 */
int
mtab_is_writable() {
	static int is_writable = -1;
	int fd;

	if (is_writable != -1)
		return is_writable;

	if (!mtab_is_accessible()) {
		is_writable = 0;
		return is_writable;
	   is not mounted. */
	if (mtab_is_a_symlink())
		return 0;

	if (ret == -1) {
		int fd = open(MOUNTED, O_RDWR | O_CREAT, 0644);
		if (fd >= 0) {
			close(fd);
			ret = 1;
		} else
			ret = 0;
	}

	lock_mtab();
	fd = open(mtab_path, O_RDWR | O_CREAT, 0644);
	if (fd >= 0) {
		close(fd);
		is_writable = 1;
	} else {
		is_writable = 0;
	}
	unlock_mtab();
	return is_writable;
}

/* Contents of mtab and fstab ---------------------------------*/

	got_mtab = 1;
	mc->nxt = mc->prev = NULL;

	fnam = mtab_path;
	mfp = my_setmntent (fnam, "r");
	if (mfp == NULL || mfp->mntent_fp == NULL) {
		int errsv = errno;
		fnam = PATH_PROC_MOUNTS;
		mfp = my_setmntent (fnam, "r");
		if (mfp == NULL || mfp->mntent_fp == NULL) {
			error(_("warning: can't open %s: %s"),
			      mtab_path, strerror (errsv));
			return;
		}
		if (verbose)
			printf (_("mount: could not open %s - "
				  "using %s instead\n"),
				mtab_path, PATH_PROC_MOUNTS);
	}
	read_mntentchn(mfp, fnam, mc);
}

/* Flag for already existing lock file. */
static int we_created_lockfile = 0;

/* Flag to indicate that signals have been set up. */
static int signals_have_been_setup = 0;

/* Ensure that the lock is released if we are interrupted.  */
extern char *strsignal(int sig);	/* not always in <string.h> */


void
unlock_mtab (void) {
	if (we_created_lockfile) {
		unlink (mtab_lock_path);
		we_created_lockfile = 0;
	}
}

/*
 * Create the lock file
 *
 * The lock file will be removed if we catch a signal or when we exit
 */
/* The old code here used flock on a lock file /etc/mtab~ and deleted
   this lock file afterwards. However, as rgooch remarks, that races:
   a second mount may be waiting on the lock which will proceed as
   soon as the lock file is deleted by the first mount; immediately
   afterwards a third mount can come, create a new /etc/mtab~, apply
   flock to that, and also proceed, so that the second and third mount
   now both scribble in /etc/mtab.
   The new code uses a link() instead of a creat(), where we proceed
   only if it was we that created the lock, and hence we always have
   to delete the lock afterwards. Now the use of flock() is in principle
   superfluous, but using it allows us to avoid an arbitrary sleep(). */

/* Where does the link point to? Obvious choices are mtab and mtab~~.
   HJLu points out that the latter leads to races. Right now we use
   mtab~.<pid> instead. Use 20 as upper bound for the length of %d. */
#define MOUNTLOCK_LINKTARGET		MOUNTED_LOCK "%d"
#define MOUNTLOCK_LINKTARGET_LTH	(sizeof(MOUNTED_LOCK)+20)

void
lock_mtab (void) {
	int tries = 3;
	/* Flag to indicate that signals have been set up. */
	static int signals_have_been_setup = 0;

	at_die = unlock_mtab;


		signals_have_been_setup = 1;
	}

	sprintf(linktargetfile, MOUNTLOCK_LINKTARGET, getpid ());

	/* Repeat until it was us who made the link */
	while (!we_created_lockfile) {
		struct flock flock;
		int errsv, fd, i, j;

		i = open (mtab_lock_targ, O_WRONLY|O_CREAT, 0);
		if (i < 0) {
			int errsv = errno;
			/* mtab_lock_targ does not exist (as a file)
			   and we cannot create it. Read-only filesystem?
			   Too many files open in the system?
			   Filesystem full? */
			die (EX_FILEIO, _("can't create lock file %s: %s "
			     "(use -n flag to override)"),
			     mtab_lock_targ, strerror (errsv));
		}
		close(i);

		j = link(mtab_lock_targ, mtab_lock_path);
		errsv = errno;

		(void) unlink(mtab_lock_targ);

		if (j == 0)
			we_created_lockfile = 1;

		if (j < 0 && errsv != EEXIST) {
			die (EX_FILEIO, _("can't link lock file %s: %s "
			     "(use -n flag to override)"),
			     mtab_lock_path, strerror (errsv));
		}

		fd = open (mtab_lock_path, O_WRONLY);

		if (fd < 0) {
			int errsv = errno;

				continue;
			die (EX_FILEIO, _("can't open lock file %s: %s "
			     "(use -n flag to override)"),
			     mtab_lock_path, strerror (errsv));
		}

		flock.l_type = F_WRLCK;

				if (verbose) {
				    int errsv = errno;
				    printf(_("Can't lock lock file %s: %s\n"),
					   mtab_lock_path, strerror (errsv));
				}
				/* proceed anyway */
			}

			if (fcntl (fd, F_SETLKW, &flock) == -1) {
				int errsv = errno;
				die (EX_FILEIO, _("can't lock lock file %s: %s"),
				     mtab_lock_path, (errno == EINTR) ?
				     _("timed out") : strerror (errsv));
			}
			alarm(0);
			/* Limit the number of iterations - maybe there
			   still is some old lock */
			if (tries++ > 3) {
				if (tries > 5)
					die (EX_FILEIO, _("Cannot create link %s\n"
					    "Perhaps there is a stale lock file?\n"),
					     mtab_lock_path);
				sleep(1);
			}
		}

void
update_mtab (const char *dir, struct my_mntent *instead) {
	mntFILE *mfp, *mftmp;
	const char *fnam = mtab_path;
	struct mntentchn mtabhead;	/* dummy */
	struct mntentchn *mc, *mc0, *absent = NULL;

	if (mtab_does_not_exist())
		return;

	lock_mtab();

	/* Having got the lock, we read mtab again */
	mc0 = mc = &mtabhead;
	mc->nxt = mc->prev = NULL;


	}

	/* write chain to mtemp */
	mftmp = my_setmntent (mtab_temp_path, "w");
	if (mftmp == NULL || mftmp->mntent_fp == NULL) {
		int errsv = errno;
		error (_("cannot open %s (%s) - mtab not updated"),
		       mtab_temp_path, strerror (errsv));
		goto leave;
	}


		if (my_addmntent(mftmp, &(mc->m)) == 1) {
			int errsv = errno;
			die (EX_FILEIO, _("error writing %s: %s"),
			     mtab_temp_path, strerror (errsv));
		}
	}


		    S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH) < 0) {
		int errsv = errno;
		fprintf(stderr, _("error changing mode of %s: %s\n"),
			mtab_temp_path, strerror (errsv));
	}
	my_endmntent (mftmp);

	{ /*
	   * If mount is setuid and some non-root user mounts sth,
	   * then the temp file might get the group of this user.
	   * Copy uid/gid from the present mtab before renaming.
	   */
	    struct stat sbuf;
	    if (stat (mtab_path, &sbuf) == 0)
		chown (mtab_temp_path, sbuf.st_uid, sbuf.st_gid);
	}

	/* rename mtemp to mtab */
	if (rename (mtab_temp_path, mtab_path) < 0) {
		int errsv = errno;
		fprintf(stderr, _("can't rename %s to %s: %s\n"),
			mtab_temp_path, mtab_path, strerror(errsv));
	}

 leave:

Lines 22-27 Link Here

(-)util-linux-2.12q/mount/fstab.h (-1 / +5 lines)
22	struct mntentchn getfsuuidspec (const char uuid);	22	struct mntentchn getfsuuidspec (const char uuid);
23	struct mntentchn getfsvolspec (const char label);	23	struct mntentchn getfsvolspec (const char label);
24		24
		25	void get_mtab_info (void);
		26	int mtab_is_writable(void);
		27	int mtab_does_not_exist(void);
		28	int is_mounted_once(const char *name);
25	void lock_mtab (void);	29	void lock_mtab (void);
26	void unlock_mtab (void);	30	void unlock_mtab (void);
27	void update_mtab (const char special, struct my_mntent with);	31	void update_mtab (const char dir, struct my_mntent instead);

Lines 38-43 Link Here

(-)util-linux-2.12q/mount/mount.8 (-64 / +89 lines)
38	.\" 010714, Michael K. Johnson <johnsonm@redhat.com> added -O	38	.\" 010714, Michael K. Johnson <johnsonm@redhat.com> added -O
39	.\" 010725, Nikita Danilov <NikitaDanilov@Yahoo.COM>: reiserfs options	39	.\" 010725, Nikita Danilov <NikitaDanilov@Yahoo.COM>: reiserfs options
40	.\" 011124, Karl Eichwalder <ke@gnu.franken.de>: tmpfs options	40	.\" 011124, Karl Eichwalder <ke@gnu.franken.de>: tmpfs options
		41	.\" 030808, Thomas Hood <jdthood@yahoo.co.uk>: symlinking /etc/mtab
		42	.\" 030809, Thomas Hood <jdthood@yahoo.co.uk>: use 'file system' consistently
41	.\"	43	.\"
42	.TH MOUNT 8 "2004-12-16" "Linux 2.6" "Linux Programmer's Manual"	44	.TH MOUNT 8 "2004-12-16" "Linux 2.6" "Linux Programmer's Manual"
43	.SH NAME	45	.SH NAME
Lines 111-117 Link Here
111	After this call the same contents is accessible in two places.	113	After this call the same contents is accessible in two places.
112	One can also remount a single file (on a single file).	114	One can also remount a single file (on a single file).
113		115
114	This call attaches only (part of) a single filesystem, not possible	116	This call attaches only (part of) a single file system, not possible
115	submounts. The entire file hierarchy including submounts is attached	117	submounts. The entire file hierarchy including submounts is attached
116	a second place using	118	a second place using
117	.RS	119	.RS
Lines 120-126 Link Here
120	.RE	122	.RE
121	.\" available since Linux 2.4.11.	123	.\" available since Linux 2.4.11.
122		124
123	Note that the filesystem mount options will remain the same as those	125	Note that the file system mount options will remain the same as those
124	on the original mount point, and cannot be changed by passing the -o	126	on the original mount point, and cannot be changed by passing the -o
125	option along with --bind/--rbind.	127	option along with --bind/--rbind.
126		128
Lines 172-178 Link Here
172	keyword. Adding the	174	keyword. Adding the
173	.B \-F	175	.B \-F
174	option will make mount fork, so that the	176	option will make mount fork, so that the
175	filesystems are mounted simultaneously.	177	file systems are mounted simultaneously.
176	.LP	178	.LP
177	(ii) When mounting a file system mentioned in	179	(ii) When mounting a file system mentioned in
178	.IR fstab ,	180	.IR fstab ,
Lines 203-209 Link Here
203	.RE	205	.RE
204	For more details, see	206	For more details, see
205	.BR fstab (5).	207	.BR fstab (5).
206	Only the user that mounted a filesystem can unmount it again.	208	Only the user that mounted a file system can unmount it again.
207	If any user should be able to unmount, then use	209	If any user should be able to unmount, then use
208	.B users	210	.B users
209	instead of	211	instead of
Lines 236-260 Link Here
236		238
237	When the	239	When the
238	.I proc	240	.I proc
239	filesystem is mounted (say at	241	file system is mounted (say at
240	.IR /proc ),	242	.IR /proc ),
241	the files	243	the files
242	.I /etc/mtab	244	.I /etc/mtab
243	and	245	and
244	.I /proc/mounts	246	.I /proc/mounts
245	have very similar contents. The former has somewhat	247	have very similar contents. The former contains somewhat
246	more information, such as the mount options used,	248	more information, such as the mount options used,
247	but is not necessarily up-to-date (cf. the	249	but is not necessarily completely accurate (cf. the
248	.B \-n	250	.B \-n
249	option below). It is possible to replace	251	and
		252	.B \-f
		253	options below). It is possible to replace
250	.I /etc/mtab	254	.I /etc/mtab
251	by a symbolic link to	255	by a symbolic link to
252	.IR /proc/mounts ,	256	.IR /proc/mounts ,
253	and especially when you have very large numbers of mounts	257	and especially when you have very large numbers of mounts
254	things will be much faster with that symlink,	258	things will be much faster with that symlink,
255	but some information is lost that way, and in particular	259	but some information is lost that way. As a result,
256	working with the loop device will be less convenient,	260	working with the loop device is less convenient
257	and using the "user" option will fail.	261	and the "user" option does not work.
		262
		263	You can also replace
		264	.I /etc/mtab
		265	by a symbolic link to
		266	another location such as
		267	.IR /var/run/mtab .
		268	This may be useful if your root file system is mounted read-only
		269	but you have another file system such as
		270	.I /var
		271	that is writable where you can store the mtab.
		272	Note that in this case you will have to mount
		273	.I /var
		274	first using the
		275	.B \-n
		276	option. Once the target of the
		277	.I /etc/mtab
		278	symbolic link is writable you can run
		279	.B mount
		280	again with the
		281	.B \-f
		282	option to add the missing entry.
258		283
259	.SH OPTIONS	284	.SH OPTIONS
260	The full set of options used by an invocation of	285	The full set of options used by an invocation of
Lines 282-288 Link Here
282	Verbose mode.	307	Verbose mode.
283	.TP	308	.TP
284	.B \-a	309	.B \-a
285	Mount all filesystems (of the given types) mentioned in	310	Mount all file systems (of the given types) mentioned in
286	.IR fstab .	311	.IR fstab .
287	.TP	312	.TP
288	.B \-F	313	.B \-F
Lines 336-342 Link Here
336	.TP	361	.TP
337	.B \-s	362	.B \-s
338	Tolerate sloppy mount options rather than failing. This will ignore	363	Tolerate sloppy mount options rather than failing. This will ignore
339	mount options not supported by a filesystem type. Not all filesystems	364	mount options not supported by a file system type. Not all file systems
340	support this option. This option exists for support of the Linux	365	support this option. This option exists for support of the Linux
341	autofs\-based automounter.	366	autofs\-based automounter.
342	.TP	367	.TP
Lines 419-425 Link Here
419	.B mount	444	.B mount
420	program has to do is issue a simple	445	program has to do is issue a simple
421	.IR mount (2)	446	.IR mount (2)
422	system call, and no detailed knowledge of the filesystem type is required.	447	system call, and no detailed knowledge of the file system type is required.
423	For a few types however (like nfs, smbfs, ncpfs) ad hoc code is	448	For a few types however (like nfs, smbfs, ncpfs) ad hoc code is
424	necessary. The nfs ad hoc code is built in, but smbfs and ncpfs	449	necessary. The nfs ad hoc code is built in, but smbfs and ncpfs
425	have a separate mount program. In order to make it possible to	450	have a separate mount program. In order to make it possible to
Lines 445-451 Link Here
445	.IR /etc/filesystems ,	470	.IR /etc/filesystems ,
446	or, if that does not exist,	471	or, if that does not exist,
447	.IR /proc/filesystems .	472	.IR /proc/filesystems .
448	All of the filesystem types listed there will be tried,	473	All of the file system types listed there will be tried,
449	except for those that are labeled "nodev" (e.g.,	474	except for those that are labeled "nodev" (e.g.,
450	.IR devpts ,	475	.IR devpts ,
451	.I proc	476	.I proc
Lines 465-471 Link Here
465	can be useful to change the probe order (e.g., to try vfat before msdos	490	can be useful to change the probe order (e.g., to try vfat before msdos
466	or ext3 before ext2) or if you use a kernel module autoloader.	491	or ext3 before ext2) or if you use a kernel module autoloader.
467	Warning: the probing uses a heuristic (the presence of appropriate `magic'),	492	Warning: the probing uses a heuristic (the presence of appropriate `magic'),
468	and could recognize the wrong filesystem type, possibly with catastrophic	493	and could recognize the wrong file system type, possibly with catastrophic
469	consequences. If your data is valuable, don't ask	494	consequences. If your data is valuable, don't ask
470	.B mount	495	.B mount
471	to guess.	496	to guess.
Lines 492-498 Link Here
492	.B \-O	517	.B \-O
493	Used in conjunction with	518	Used in conjunction with
494	.BR \-a ,	519	.BR \-a ,
495	to limit the set of filesystems to which the	520	to limit the set of file systems to which the
496	.B \-a	521	.B \-a
497	is applied. Like	522	is applied. Like
498	.B \-t	523	.B \-t
Lines 523-529 Link Here
523	.RS	548	.RS
524	.B "mount \-a \-t ext2 \-O _netdev"	549	.B "mount \-a \-t ext2 \-O _netdev"
525	.RE	550	.RE
526	mounts all ext2 filesystems with the _netdev option, not all filesystems	551	mounts all ext2 file systems with the _netdev option, not all file systems
527	that are either ext2 or have the _netdev option specified.	552	that are either ext2 or have the _netdev option specified.
528	.RE	553	.RE
529	.TP	554	.TP
Lines 569-580 Link Here
569	.BR group,dev,suid ).	594	.BR group,dev,suid ).
570	.TP	595	.TP
571	.B mand	596	.B mand
572	Allow mandatory locks on this filesystem. See	597	Allow mandatory locks on this file system. See
573	.BR fcntl (2).	598	.BR fcntl (2).
574	.TP	599	.TP
575	.B _netdev	600	.B _netdev
576	The filesystem resides on a device that requires network access	601	The file system resides on a device that requires network access
577	(used to prevent the system from attempting to mount these filesystems	602	(used to prevent the system from attempting to mount these file systems
578	until the network has been enabled on the system).	603	until the network has been enabled on the system).
579	.TP	604	.TP
580	.B noatime	605	.B noatime
Lines 596-602 Link Here
596	/lib/ld*.so /mnt/binary. This trick fails since Linux 2.4.25 / 2.6.0.)	621	/lib/ld*.so /mnt/binary. This trick fails since Linux 2.4.25 / 2.6.0.)
597	.TP	622	.TP
598	.B nomand	623	.B nomand
599	Do not allow mandatory locks on this filesystem.	624	Do not allow mandatory locks on this file system.
600	.TP	625	.TP
601	.B nosuid	626	.B nosuid
602	Do not allow set-user-identifier or set-group-identifier bits to take	627	Do not allow set-user-identifier or set-group-identifier bits to take
Lines 772-778 Link Here
772	.\" Due to a kernel bug, it may be mounted with random mount options	797	.\" Due to a kernel bug, it may be mounted with random mount options
773	.\" (fixed in Linux 2.0.4).	798	.\" (fixed in Linux 2.0.4).
774	Since Linux 2.5.46, for most mount options the default	799	Since Linux 2.5.46, for most mount options the default
775	is determined by the filesystem superblock. Set them with	800	is determined by the file system superblock. Set them with
776	.BR tune2fs (8).	801	.BR tune2fs (8).
777	.TP	802	.TP
778	.BR acl " / " noacl	803	.BR acl " / " noacl
Lines 817-823 Link Here
817	.\" Since 2.3.99-pre3 but before 2.6.0-test7 every string check=foo	842	.\" Since 2.3.99-pre3 but before 2.6.0-test7 every string check=foo
818	.\" was equivalent to just check. Since 2.6.0-test7 only check is accepted.	843	.\" was equivalent to just check. Since 2.6.0-test7 only check is accepted.
819	.BR check	844	.BR check
820	Check filesystem (block and inode bitmaps) at mount time.	845	Check file system (block and inode bitmaps) at mount time.
821	.\" requires CONFIG_EXT2_CHECK	846	.\" requires CONFIG_EXT2_CHECK
822	.TP	847	.TP
823	.BR check=none " / " nocheck	848	.BR check=none " / " nocheck
Lines 833-839 Link Here
833	Define the behaviour when an error is encountered.	858	Define the behaviour when an error is encountered.
834	(Either ignore errors and just mark the file system erroneous and continue,	859	(Either ignore errors and just mark the file system erroneous and continue,
835	or remount the file system read-only, or panic and halt the system.)	860	or remount the file system read-only, or panic and halt the system.)
836	The default is set in the filesystem superblock, and can be	861	The default is set in the file system superblock, and can be
837	changed using	862	changed using
838	.BR tune2fs (8).	863	.BR tune2fs (8).
839	.TP	864	.TP
Lines 872-889 Link Here
872	.BI sb= n	897	.BI sb= n
873	Instead of block 1, use block	898	Instead of block 1, use block
874	.I n	899	.I n
875	as superblock. This could be useful when the filesystem has been damaged.	900	as superblock. This could be useful when the file system has been damaged.
876	(Earlier, copies of the superblock would be made every 8192 blocks: in	901	(Earlier, copies of the superblock would be made every 8192 blocks: in
877	block 1, 8193, 16385, ... (and one got thousands of copies on	902	block 1, 8193, 16385, ... (and one got thousands of copies on
878	a big filesystem). Since version 1.08,	903	a big file system). Since version 1.08,
879	.B mke2fs	904	.B mke2fs
880	has a \-s (sparse superblock) option to reduce the number of backup	905	has a \-s (sparse superblock) option to reduce the number of backup
881	superblocks, and since version 1.15 this is the default. Note	906	superblocks, and since version 1.15 this is the default. Note
882	that this may mean that ext2 filesystems created by a recent	907	that this may mean that ext2 file systems created by a recent
883	.B mke2fs	908	.B mke2fs
884	cannot be mounted r/w under Linux 2.0.*.)	909	cannot be mounted r/w under Linux 2.0.*.)
885	The block number here uses 1k units. Thus, if you want to use logical	910	The block number here uses 1k units. Thus, if you want to use logical
886	block 32768 on a filesystem with 4k blocks, use "sb=131072".	911	block 32768 on a file system with 4k blocks, use "sb=131072".
887	.TP	912	.TP
888	.BR user_xattr " / " nouser_xattr	913	.BR user_xattr " / " nouser_xattr
889	Support "user." extended attributes (or not).	914	Support "user." extended attributes (or not).
Lines 943-954 Link Here
943	.SH "Mount options for fat"	968	.SH "Mount options for fat"
944	(Note:	969	(Note:
945	.I fat	970	.I fat
946	is not a separate filesystem, but a common part of the	971	is not a separate file system, but a common part of the
947	.IR msdos ,	972	.IR msdos ,
948	.I umsdos	973	.I umsdos
949	and	974	and
950	.I vfat	975	.I vfat
951	filesystems.)	976	file systems.)
952	.TP	977	.TP
953	.BR blocksize=512 " / " blocksize=1024 " / " blocksize=2048	978	.BR blocksize=512 " / " blocksize=1024 " / " blocksize=2048
954	Set blocksize (default 512).	979	Set blocksize (default 512).
Lines 999-1005 Link Here
999	.TP	1024	.TP
1000	.BI codepage= value	1025	.BI codepage= value
1001	Sets the codepage for converting to shortname characters on FAT	1026	Sets the codepage for converting to shortname characters on FAT
1002	and VFAT filesystems. By default, codepage 437 is used.	1027	and VFAT file systems. By default, codepage 437 is used.
1003	.TP	1028	.TP
1004	.BR conv=b[inary] " / " conv=t[ext] " / " conv=a[uto]	1029	.BR conv=b[inary] " / " conv=t[ext] " / " conv=a[uto]
1005	The	1030	The
Lines 1127-1136 Link Here
1127	Do not abort mounting when certain consistency checks fail.	1152	Do not abort mounting when certain consistency checks fail.
1128		1153
1129	.SH "Mount options for iso9660"	1154	.SH "Mount options for iso9660"
1130	ISO 9660 is a standard describing a filesystem structure to be used	1155	ISO 9660 is a standard describing a file system structure to be used
1131	on CD-ROMs. (This filesystem type is also seen on some DVDs. See also the	1156	on CD-ROMs. (This file system type is also seen on some DVDs. See also the
1132	.I udf	1157	.I udf
1133	filesystem.)	1158	file system.)
1134		1159
1135	Normal	1160	Normal
1136	.I iso9660	1161	.I iso9660
Lines 1142-1148 Link Here
1142	Rock Ridge is an extension to iso9660 that provides all of these unix like	1167	Rock Ridge is an extension to iso9660 that provides all of these unix like
1143	features. Basically there are extensions to each directory record that	1168	features. Basically there are extensions to each directory record that
1144	supply all of the additional information, and when Rock Ridge is in use,	1169	supply all of the additional information, and when Rock Ridge is in use,
1145	the filesystem is indistinguishable from a normal UNIX file system (except	1170	the file system is indistinguishable from a normal UNIX file system (except
1146	that it is read-only, of course).	1171	that it is read-only, of course).
1147	.TP	1172	.TP
1148	.B norock	1173	.B norock
Lines 1393-1399 Link Here
1393	hard links instead of being suppressed.	1418	hard links instead of being suppressed.
1394	.TP	1419	.TP
1395	\fBuid=\fP\fIvalue\fP, \fBgid=\fP\fIvalue\fP and \fBumask=\fP\fIvalue\fP	1420	\fBuid=\fP\fIvalue\fP, \fBgid=\fP\fIvalue\fP and \fBumask=\fP\fIvalue\fP
1396	Set the file permission on the filesystem.	1421	Set the file permission on the file system.
1397	The umask value is given in octal.	1422	The umask value is given in octal.
1398	By default, the files are owned by root and not readable by somebody else.	1423	By default, the files are owned by root and not readable by somebody else.
1399		1424
Lines 1403-1414 Link Here
1403	These options are recognized, but have no effect as far as I can see.	1428	These options are recognized, but have no effect as far as I can see.
1404		1429
1405	.SH "Mount options for ramfs"	1430	.SH "Mount options for ramfs"
1406	Ramfs is a memory based filesystem. Mount it and you have it. Unmount it	1431	Ramfs is a memory based file system. Mount it and you have it. Unmount it
1407	and it is gone. Present since Linux 2.3.99pre4.	1432	and it is gone. Present since Linux 2.3.99pre4.
1408	There are no mount options.	1433	There are no mount options.
1409		1434
1410	.SH "Mount options for reiserfs"	1435	.SH "Mount options for reiserfs"
1411	Reiserfs is a journaling filesystem.	1436	Reiserfs is a journaling file system.
1412	The reiserfs mount options are more fully described at	1437	The reiserfs mount options are more fully described at
1413	.IR http://www.namesys.com/mount-options.html .	1438	.IR http://www.namesys.com/mount-options.html .
1414	.TP	1439	.TP
Lines 1517-1523 Link Here
1517	for Ki, Mi, Gi (binary kilo, mega and giga) and can be changed on remount.	1542	for Ki, Mi, Gi (binary kilo, mega and giga) and can be changed on remount.
1518	.TP	1543	.TP
1519	.BI size= nbytes	1544	.BI size= nbytes
1520	Override default maximum size of the filesystem.	1545	Override default maximum size of the file system.
1521	The size is given in bytes, and rounded down to entire pages.	1546	The size is given in bytes, and rounded down to entire pages.
1522	The default is half of the memory.	1547	The default is half of the memory.
1523	.TP	1548	.TP
Lines 1531-1537 Link Here
1531	Set initial permissions of the root directory.	1556	Set initial permissions of the root directory.
1532		1557
1533	.SH "Mount options for udf"	1558	.SH "Mount options for udf"
1534	udf is the "Universal Disk Format" filesystem defined by the Optical	1559	udf is the "Universal Disk Format" file system defined by the Optical
1535	Storage Technology Association, and is often used for DVD-ROM.	1560	Storage Technology Association, and is often used for DVD-ROM.
1536	See also	1561	See also
1537	.IR iso9660 .	1562	.IR iso9660 .
Lines 1580-1586 Link Here
1580	Override the PartitionDesc location. (unused)	1605	Override the PartitionDesc location. (unused)
1581	.TP	1606	.TP
1582	.B lastblock=	1607	.B lastblock=
1583	Set the last block of the filesystem.	1608	Set the last block of the file system.
1584	.TP	1609	.TP
1585	.B fileset=	1610	.B fileset=
1586	Override the fileset block location. (unused)	1611	Override the fileset block location. (unused)
Lines 1604-1629 Link Here
1604	(Don't forget to give the \-r option.)	1629	(Don't forget to give the \-r option.)
1605	.TP	1630	.TP
1606	.B 44bsd	1631	.B 44bsd
1607	For filesystems created by a BSD-like system (NetBSD,FreeBSD,OpenBSD).	1632	For file systems created by a BSD-like system (NetBSD,FreeBSD,OpenBSD).
1608	.TP	1633	.TP
1609	.B sun	1634	.B sun
1610	For filesystems created by SunOS or Solaris on Sparc.	1635	For file systems created by SunOS or Solaris on Sparc.
1611	.TP	1636	.TP
1612	.B sunx86	1637	.B sunx86
1613	For filesystems created by Solaris on x86.	1638	For file systems created by Solaris on x86.
1614	.TP	1639	.TP
1615	.B hp	1640	.B hp
1616	For filesystems created by HP-UX, read-only.	1641	For file systems created by HP-UX, read-only.
1617	.TP	1642	.TP
1618	.B nextstep	1643	.B nextstep
1619	For filesystems created by NeXTStep (on NeXT station) (currently read only).	1644	For file systems created by NeXTStep (on NeXT station) (currently read only).
1620	.TP	1645	.TP
1621	.B nextstep-cd	1646	.B nextstep-cd
1622	For NextStep CDROMs (block_size == 2048), read-only.	1647	For NextStep CDROMs (block_size == 2048), read-only.
1623	.TP	1648	.TP
1624	.B openstep	1649	.B openstep
1625	For filesystems created by OpenStep (currently read only).	1650	For file systems created by OpenStep (currently read only).
1626	The same filesystem type is also used by Mac OS X.	1651	The same file system type is also used by Mac OS X.
1627	.RE	1652	.RE
1628		1653
1629	.TP	1654	.TP
Lines 1661-1667 Link Here
1661	This lets you backup and restore filenames that are created with any	1686	This lets you backup and restore filenames that are created with any
1662	Unicode characters. Without this option, a '?' is used when no	1687	Unicode characters. Without this option, a '?' is used when no
1663	translation is possible. The escape character is ':' because it is	1688	translation is possible. The escape character is ':' because it is
1664	otherwise illegal on the vfat filesystem. The escape sequence	1689	otherwise illegal on the vfat file system. The escape sequence
1665	that gets used, where u is the unicode character,	1690	that gets used, where u is the unicode character,
1666	is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12).	1691	is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12).
1667	.TP	1692	.TP
Lines 1674-1681 Link Here
1674	.IR name~num.ext .	1699	.IR name~num.ext .
1675	.TP	1700	.TP
1676	.B utf8	1701	.B utf8
1677	UTF8 is the filesystem safe 8-bit encoding of Unicode that is used	1702	UTF8 is the file system safe 8-bit encoding of Unicode that is used
1678	by the console. It can be be enabled for the filesystem with this option.	1703	by the console. It can be be enabled for the file system with this option.
1679	If `uni_xlate' gets set, UTF8 gets disabled.	1704	If `uni_xlate' gets set, UTF8 gets disabled.
1680	.TP	1705	.TP
1681	.B shortname=[lower\|win95\|winnt\|mixed]	1706	.B shortname=[lower\|win95\|winnt\|mixed]
Lines 1743-1751 Link Here
1743	.BI logbufs= value	1768	.BI logbufs= value
1744	Set the number of in-memory log buffers.	1769	Set the number of in-memory log buffers.
1745	Valid numbers range from 2-8 inclusive.	1770	Valid numbers range from 2-8 inclusive.
1746	The default value is 8 buffers for filesystems with a blocksize of 64K,	1771	The default value is 8 buffers for file systems with a blocksize of 64K,
1747	4 buffers for filesystems with a blocksize of 32K,	1772	4 buffers for file systems with a blocksize of 32K,
1748	3 buffers for filesystems with a blocksize of 16K,	1773	3 buffers for file systems with a blocksize of 16K,
1749	and 2 buffers for all other configurations.	1774	and 2 buffers for all other configurations.
1750	Increasing the number of buffers may increase performance on	1775	Increasing the number of buffers may increase performance on
1751	some workloads at the cost of the memory used for the	1776	some workloads at the cost of the memory used for the
Lines 1759-1765 Link Here
1759	.TP	1784	.TP
1760	\fBlogdev=\fP\fIdevice\fP and \fBrtdev=\fP\fIdevice\fP	1785	\fBlogdev=\fP\fIdevice\fP and \fBrtdev=\fP\fIdevice\fP
1761	Use an external log (metadata journal) and/or real-time device.	1786	Use an external log (metadata journal) and/or real-time device.
1762	An XFS filesystem has up to three parts: a data section, a log section,	1787	An XFS file system has up to three parts: a data section, a log section,
1763	and a real-time section.	1788	and a real-time section.
1764	The real-time section is optional, and the log section can be separate	1789	The real-time section is optional, and the log section can be separate
1765	from the data section or contained within it.	1790	from the data section or contained within it.
Lines 1773-1780 Link Here
1773	Access timestamps are not updated when a file is read.	1798	Access timestamps are not updated when a file is read.
1774	.TP	1799	.TP
1775	.B norecovery	1800	.B norecovery
1776	The filesystem will be mounted without running log recovery.	1801	The file system will be mounted without running log recovery.
1777	If the filesystem was not cleanly unmounted, it is likely to	1802	If the file system was not cleanly unmounted, it is likely to
1778	be inconsistent when mounted in	1803	be inconsistent when mounted in
1779	.B norecovery	1804	.B norecovery
1780	mode.	1805	mode.
Lines 1784-1790 Link Here
1784	must be mounted read-only or the mount will fail.	1809	must be mounted read-only or the mount will fail.
1785	.TP	1810	.TP
1786	.B nouuid	1811	.B nouuid
1787	Ignore the filesystem uuid. This avoids errors for duplicate uuids.	1812	Ignore the file system uuid. This avoids errors for duplicate uuids.
1788	.TP	1813	.TP
1789	.B osyncisdsync	1814	.B osyncisdsync
1790	Make writes to files opened with the O_SYNC flag set behave	1815	Make writes to files opened with the O_SYNC flag set behave
Lines 1805-1817 Link Here
1805	volume.	1830	volume.
1806	.I value	1831	.I value
1807	must be specified in 512-byte block units.	1832	must be specified in 512-byte block units.
1808	If this option is not specified and the filesystem was made on a stripe	1833	If this option is not specified and the file system was made on a stripe
1809	volume or the stripe width or unit were specified for the RAID device at	1834	volume or the stripe width or unit were specified for the RAID device at
1810	mkfs time, then the mount system call will restore the value from the	1835	mkfs time, then the mount system call will restore the value from the
1811	superblock.	1836	superblock.
1812	For filesystems that are made directly on RAID devices, these options can be	1837	For file systems that are made directly on RAID devices, these options can be
1813	used to override the information in the superblock if the underlying disk	1838	used to override the information in the superblock if the underlying disk
1814	layout changes after the filesystem has been created.	1839	layout changes after the file system has been created.
1815	The	1840	The
1816	.B swidth	1841	.B swidth
1817	option is required if the	1842	option is required if the
Lines 1846-1852 Link Here
1846	that are really options to	1871	that are really options to
1847	.BR \%losetup (8).	1872	.BR \%losetup (8).
1848	(These options can be used in addition to those specific	1873	(These options can be used in addition to those specific
1849	to the filesystem type.)	1874	to the file system type.)
1850		1875
1851	If no explicit loop device is mentioned	1876	If no explicit loop device is mentioned
1852	(but just an option `\fB\-o loop\fP' is given), then	1877	(but just an option `\fB\-o loop\fP' is given), then
Lines 1911-1917 Link Here
1911	temporary file	1936	temporary file
1912	.TP	1937	.TP
1913	.I /etc/filesystems	1938	.I /etc/filesystems
1914	a list of filesystem types to try	1939	a list of file system types to try
1915		1940
1916	.SH "SEE ALSO"	1941	.SH "SEE ALSO"
1917	.BR mount (2),	1942	.BR mount (2),

Lines 391-397 Link Here

(-)util-linux-2.12q/mount/mount.c (-2 / +9 lines)
391	return ret;	391	return ret;
392	}	392	}
393		393
394	/* Create mtab with a root entry. */	394	/*
		395	* Create mtab with a root entry.
		396	*
		397	* Caller should check that mtab is writable first
		398	*/
395	static void	399	static void
396	create_mtab (void) {	400	create_mtab (void) {
397	struct mntentchn *fstab;	401	struct mntentchn *fstab;
Lines 1491-1496 Link Here
1491	initproctitle(argc, argv);	1495	initproctitle(argc, argv);
1492	#endif	1496	#endif
1493		1497
		1498	get_mtab_info();
		1499	/* Keep in mind that /etc/mtab may be a symlink */
		1500
1494	while ((c = getopt_long (argc, argv, "afFhilL:no:O:p:rsU:vVwt:",	1501	while ((c = getopt_long (argc, argv, "afFhilL:no:O:p:rsU:vVwt:",
1495	longopts, NULL)) != -1) {	1502	longopts, NULL)) != -1) {
1496	switch (c) {	1503	switch (c) {
Lines 1615-1621 Link Here
1615	die (EX_USAGE, _("mount: only root can do that"));	1622	die (EX_USAGE, _("mount: only root can do that"));
1616	}	1623	}
1617		1624
1618	if (!nomtab && mtab_does_not_exist()) {	1625	if (!nomtab && mtab_does_not_exist() && mtab_is_writable()) {
1619	if (verbose > 1)	1626	if (verbose > 1)
1620	printf(_("mount: no %s found - creating it..\n"),	1627	printf(_("mount: no %s found - creating it..\n"),
1621	MOUNTED);	1628	MOUNTED);

Lines 1-10 Link Here

(-)util-linux-2.12q/mount/paths.h (-6 / +10 lines)
1	#include <mntent.h>	1	#include <mntent.h>
2	#define _PATH_FSTAB "/etc/fstab"	2	#define _PATH_FSTAB "/etc/fstab"
		3	#define PATH_PROC "/proc/"
		4	#define PATH_PROC_MOUNTS PATH_PROC "mounts"
		5	#define MTAB_LOCK_SUFFIX "~"
		6	#define MTAB_TEMP_SUFFIX ".tmp"
3	#ifdef _PATH_MOUNTED	7	#ifdef _PATH_MOUNTED
4	#define MOUNTED_LOCK _PATH_MOUNTED "~"	8	#define MOUNTED_LOCK _PATH_MOUNTED "~"
5	#define MOUNTED_TEMP _PATH_MOUNTED ".tmp"	9	#define MOUNTED_TEMP _PATH_MOUNTED ".tmp"
6	#else	10	#else
7	#define MOUNTED_LOCK "/etc/mtab~"	11	#define MOUNTED_LOCK "/etc/mtab~"
8	#define MOUNTED_TEMP "/etc/mtab.tmp"	12	#define MOUNTED_TEMP "/etc/mtab.tmp"
9	#endif	13	#endif
10	#define LOCK_TIMEOUT 10	14	#define LOCK_TIMEOUT 10

Lines 17-23 Link Here

(-)util-linux-2.12q/mount/sundries.h (-1 / +2 lines)
17	extern int verbose;	17	extern int verbose;
18	extern int sloppy;	18	extern int sloppy;
19		19
20	#define streq(s, t) (strcmp ((s), (t)) == 0)	20	#define streq(s, t) (strcmp ((s), (t)) == 0)
		21	#define streqn(s, t, n) (strncmp((s), (t), (n)) == 0)
21		22
22	/* Functions in sundries.c that are used in mount.c and umount.c */	23	/* Functions in sundries.c that are used in mount.c and umount.c */
23	void block_signals (int how);	24	void block_signals (int how);

Lines 264-271 Link Here

(-)util-linux-2.12q/mount/umount.c (-3 / +9 lines)
264	}	264	}
265	}	265	}
266		266
267	/* Umount a single device. Return a status code, so don't exit	267	/*
268	on a non-fatal error. We lock/unlock around each umount. */	268	* Umount a single device
		269	*
		270	* Returns a status code; doesn't exit on a non-fatal error
		271	*/
269	static int	272	static int
270	umount_one (const char spec, const char node, const char *type,	273	umount_one (const char spec, const char node, const char *type,
271	const char opts, struct mntentchn mc) {	274	const char opts, struct mntentchn mc) {
Lines 355-361 Link Here
355	remnt.mnt_type = remnt.mnt_fsname = NULL;	358	remnt.mnt_type = remnt.mnt_fsname = NULL;
356	remnt.mnt_dir = xstrdup(node);	359	remnt.mnt_dir = xstrdup(node);
357	remnt.mnt_opts = xstrdup("ro");	360	remnt.mnt_opts = xstrdup("ro");
358	update_mtab(node, &remnt);	361	if (!nomtab && mtab_is_writable())
		362	update_mtab(node, &remnt);
359	return 0;	363	return 0;
360	} else if (errno != EBUSY) { /* hmm ... */	364	} else if (errno != EBUSY) { /* hmm ... */
361	perror("remount");	365	perror("remount");
Lines 665-670 Link Here
665		669
666	umask(022);	670	umask(022);
667		671
		672	get_mtab_info();
		673
668	while ((c = getopt_long (argc, argv, "adfhlnrit:O:vV",	674	while ((c = getopt_long (argc, argv, "adfhlnrit:O:vV",
669	longopts, NULL)) != -1)	675	longopts, NULL)) != -1)
670	switch (c) {	676	switch (c) {

Return to bug 98403

Lines 1-7 Link Here

(-)util-linux-2.12q/mount/fstab.c (-92 / +150 lines)
1	/* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>	1	/*
		2	* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
2	* - added Native Language Support	3	* - added Native Language Support
3	* Sun Mar 21 1999 - Arnaldo Carvalho de Melo <acme@conectiva.com.br>	4	* 1999-03-21 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
4	* - fixed strerr(errno) in gettext calls	5	* - fixed strerr(errno) in gettext calls
		6	* 2003-08-08 Thomas Hood <jdthood@yahoo.co.uk>
		7	* - Write through a symlink at /etc/mtab if it doesn't point into /proc/
5	*/	8	*/
6		9
7	#include <unistd.h>	10	#include <unistd.h>
Lines 11-77 Link Here
11	#include <sys/stat.h>	14	#include <sys/stat.h>
12	#include "mntent.h"	15	#include "mntent.h"
13	#include "fstab.h"	16	#include "fstab.h"
		17	#include "realpath.h"
14	#include "sundries.h"	18	#include "sundries.h"
15	#include "xmalloc.h"	19	#include "xmalloc.h"
16	#include "mount_blkid.h"	20	#include "mount_blkid.h"
17	#include "paths.h"	21	#include "paths.h"
18	#include "nls.h"	22	#include "nls.h"
19		23
20	#define streq(s, t) (strcmp ((s), (t)) == 0)
21
22	#define PROC_MOUNTS "/proc/mounts"
23
24
25	/* Information about mtab. ------------------------------------*/	24	/* Information about mtab. ------------------------------------*/
26	static int have_mtab_info = 0;	25	/* A 64 bit number can be displayed in 20 decimal digits */
27	static int var_mtab_does_not_exist = 0;	26	#define LEN_LARGEST_PID 20
28	static int var_mtab_is_a_symlink = 0;	27	#define MTAB_PATH_MAX (PATH_MAX - (sizeof(MTAB_LOCK_SUFFIX) - 1) - LEN_LARGEST_PID)
		28	static char mtab_path[MTAB_PATH_MAX];
		29	static char mtab_lock_path[PATH_MAX];
		30	static char mtab_lock_targ[PATH_MAX];
		31	static char mtab_temp_path[PATH_MAX];
29		32
30	static void	33	/*
		34	* Set mtab_path to the real path of the mtab file
		35	* or to the null string if that path is inaccessible
		36	*
		37	* Run this early
		38	*/
		39	void
31	get_mtab_info(void) {	40	get_mtab_info(void) {
32	struct stat mtab_stat;	41	struct stat mtab_stat;
33		42
34	if (!have_mtab_info) {	43	if (lstat(MOUNTED, &mtab_stat)) {
35	if (lstat(MOUNTED, &mtab_stat))	44	/* Assume that the lstat error means that the file does not exist */
36	var_mtab_does_not_exist = 1;	45	/* (Maybe we should check errno here) */
37	else if (S_ISLNK(mtab_stat.st_mode))	46	strcpy(mtab_path, MOUNTED);
38	var_mtab_is_a_symlink = 1;	47	} else if (S_ISLNK(mtab_stat.st_mode)) {
39	have_mtab_info = 1;	48	/* Is a symlink */
		49	int len;
		50	char *r = myrealpath(MOUNTED, mtab_path, MTAB_PATH_MAX);
		51	mtab_path[MTAB_PATH_MAX - 1] = 0; /* Just to be sure */
		52	len = strlen(mtab_path);
		53	if (
		54	r == NULL
		55	\|\| len == 0
		56	\|\| len >= (MTAB_PATH_MAX - 1)
		57	\|\| streqn(mtab_path, PATH_PROC, sizeof(PATH_PROC) - 1)
		58	) {
		59	/* Real path invalid or inaccessible */
		60	mtab_path[0] = '\0';
		61	return;
		62	}
		63	/* mtab_path now contains mtab's real path */
		64	} else {
		65	/* Exists and is not a symlink */
		66	strcpy(mtab_path, MOUNTED);
40	}	67	}
		68
		69	sprintf(mtab_lock_path, "%s%s", mtab_path, MTAB_LOCK_SUFFIX);
		70	sprintf(mtab_lock_targ, "%s%s%d", mtab_path, MTAB_LOCK_SUFFIX, getpid());
		71	sprintf(mtab_temp_path, "%s%s", mtab_path, MTAB_TEMP_SUFFIX);
		72
		73	return;
41	}	74	}
42		75
43	int	76	/*
44	mtab_does_not_exist(void) {	77	* Tell whether or not the mtab real path is accessible
45	get_mtab_info();	78	*
46	return var_mtab_does_not_exist;	79	* get_mtab_info() must have been run
		80	*/
		81	static int
		82	mtab_is_accessible(void) {
		83	return (mtab_path[0] != '\0');
47	}	84	}
48		85
		86	/*
		87	* Tell whether or not the mtab file currently exists
		88	*
		89	* Note that the answer here is independent of whether or
		90	* not the file is writable, so if you are planning to create
		91	* the mtab file then check mtab_is_writable() too.
		92	*
		93	* get_mtab_info() must have been run
		94	*/
49	int	95	int
50	mtab_is_a_symlink(void) {	96	mtab_does_not_exist(void) {
51	get_mtab_info();	97	struct stat mtab_stat;
52	return var_mtab_is_a_symlink;	98
		99	if (!mtab_is_accessible())
		100	return 1;
		101
		102	if (lstat(mtab_path, &mtab_stat))
		103	return 1;
		104
		105	return 0;
53	}	106	}
54		107
		108	/*
		109	* Tell whether or not mtab is writable (whether or not it currently exists)
		110	*
		111	* This depends on whether or not the real path is accessible and,
		112	* if so, whether or not the file can be opened. This function
		113	* has the side effect of creating the file if it is writable.
		114	*
		115	* get_mtab_info() must have been run
		116	*/
55	int	117	int
56	mtab_is_writable() {	118	mtab_is_writable() {
57	static int ret = -1;	119	static int is_writable = -1;
		120	int fd;
		121
		122	if (is_writable != -1)
		123	return is_writable;
58		124
59	/* Should we write to /etc/mtab upon an update?	125	if (!mtab_is_accessible()) {
60	Probably not if it is a symlink to /proc/mounts, since that	126	is_writable = 0;
61	would create a file /proc/mounts in case the proc filesystem	127	return is_writable;
62	is not mounted. */
63	if (mtab_is_a_symlink())
64	return 0;
65
66	if (ret == -1) {
67	int fd = open(MOUNTED, O_RDWR \| O_CREAT, 0644);
68	if (fd >= 0) {
69	close(fd);
70	ret = 1;
71	} else
72	ret = 0;
73	}	128	}
74	return ret;	129
		130	lock_mtab();
		131	fd = open(mtab_path, O_RDWR \| O_CREAT, 0644);
		132	if (fd >= 0) {
		133	close(fd);
		134	is_writable = 1;
		135	} else {
		136	is_writable = 0;
		137	}
		138	unlock_mtab();
		139	return is_writable;
75	}	140	}
76		141
77	/* Contents of mtab and fstab ---------------------------------*/	142	/* Contents of mtab and fstab ---------------------------------*/
Lines 154-174 Link Here
154	got_mtab = 1;	219	got_mtab = 1;
155	mc->nxt = mc->prev = NULL;	220	mc->nxt = mc->prev = NULL;
156		221
157	fnam = MOUNTED;	222	fnam = mtab_path;
158	mfp = my_setmntent (fnam, "r");	223	mfp = my_setmntent (fnam, "r");
159	if (mfp == NULL \|\| mfp->mntent_fp == NULL) {	224	if (mfp == NULL \|\| mfp->mntent_fp == NULL) {
160	int errsv = errno;	225	int errsv = errno;
161	fnam = PROC_MOUNTS;	226	fnam = PATH_PROC_MOUNTS;
162	mfp = my_setmntent (fnam, "r");	227	mfp = my_setmntent (fnam, "r");
163	if (mfp == NULL \|\| mfp->mntent_fp == NULL) {	228	if (mfp == NULL \|\| mfp->mntent_fp == NULL) {
164	error(_("warning: can't open %s: %s"),	229	error(_("warning: can't open %s: %s"),
165	MOUNTED, strerror (errsv));	230	mtab_path, strerror (errsv));
166	return;	231	return;
167	}	232	}
168	if (verbose)	233	if (verbose)
169	printf (_("mount: could not open %s - "	234	printf (_("mount: could not open %s - "
170	"using %s instead\n"),	235	"using %s instead\n"),
171	MOUNTED, PROC_MOUNTS);	236	mtab_path, PATH_PROC_MOUNTS);
172	}	237	}
173	read_mntentchn(mfp, fnam, mc);	238	read_mntentchn(mfp, fnam, mc);
174	}	239	}
Lines 396-404 Link Here
396	/* Flag for already existing lock file. */	461	/* Flag for already existing lock file. */
397	static int we_created_lockfile = 0;	462	static int we_created_lockfile = 0;
398		463
399	/* Flag to indicate that signals have been set up. */
400	static int signals_have_been_setup = 0;
401
402	/* Ensure that the lock is released if we are interrupted. */	464	/* Ensure that the lock is released if we are interrupted. */
403	extern char strsignal(int sig); / not always in <string.h> */	465	extern char strsignal(int sig); / not always in <string.h> */
404		466
Lines 416-450 Link Here
416	void	478	void
417	unlock_mtab (void) {	479	unlock_mtab (void) {
418	if (we_created_lockfile) {	480	if (we_created_lockfile) {
419	unlink (MOUNTED_LOCK);	481	unlink (mtab_lock_path);
420	we_created_lockfile = 0;	482	we_created_lockfile = 0;
421	}	483	}
422	}	484	}
423		485
424	/* Create the lock file.	486	/*
425	The lock file will be removed if we catch a signal or when we exit. */	487	* Create the lock file
		488	*
		489	* The lock file will be removed if we catch a signal or when we exit
		490	*/
426	/* The old code here used flock on a lock file /etc/mtab~ and deleted	491	/* The old code here used flock on a lock file /etc/mtab~ and deleted
427	this lock file afterwards. However, as rgooch remarks, that has a	492	this lock file afterwards. However, as rgooch remarks, that races:
428	race: a second mount may be waiting on the lock and proceed as	493	a second mount may be waiting on the lock which will proceed as
429	soon as the lock file is deleted by the first mount, and immediately	494	soon as the lock file is deleted by the first mount; immediately
430	afterwards a third mount comes, creates a new /etc/mtab~, applies	495	afterwards a third mount can come, create a new /etc/mtab~, apply
431	flock to that, and also proceeds, so that the second and third mount	496	flock to that, and also proceed, so that the second and third mount
432	now both are scribbling in /etc/mtab.	497	now both scribble in /etc/mtab.
433	The new code uses a link() instead of a creat(), where we proceed	498	The new code uses a link() instead of a creat(), where we proceed
434	only if it was us that created the lock, and hence we always have	499	only if it was we that created the lock, and hence we always have
435	to delete the lock afterwards. Now the use of flock() is in principle	500	to delete the lock afterwards. Now the use of flock() is in principle
436	superfluous, but avoids an arbitrary sleep(). */	501	superfluous, but using it allows us to avoid an arbitrary sleep(). */
437
438	/* Where does the link point to? Obvious choices are mtab and mtab~~.
439	HJLu points out that the latter leads to races. Right now we use
440	mtab~.<pid> instead. Use 20 as upper bound for the length of %d. */
441	#define MOUNTLOCK_LINKTARGET MOUNTED_LOCK "%d"
442	#define MOUNTLOCK_LINKTARGET_LTH (sizeof(MOUNTED_LOCK)+20)
443		502
444	void	503	void
445	lock_mtab (void) {	504	lock_mtab (void) {
446	int tries = 3;	505	int tries = 3;
447	char linktargetfile[MOUNTLOCK_LINKTARGET_LTH];	506	/* Flag to indicate that signals have been set up. */
		507	static int signals_have_been_setup = 0;
448		508
449	at_die = unlock_mtab;	509	at_die = unlock_mtab;
450		510
Lines 467-496 Link Here
467	signals_have_been_setup = 1;	527	signals_have_been_setup = 1;
468	}	528	}
469		529
470	sprintf(linktargetfile, MOUNTLOCK_LINKTARGET, getpid ());
471
472	/* Repeat until it was us who made the link */	530	/* Repeat until it was us who made the link */
473	while (!we_created_lockfile) {	531	while (!we_created_lockfile) {
474	struct flock flock;	532	struct flock flock;
475	int errsv, fd, i, j;	533	int errsv, fd, i, j;
476		534
477	i = open (linktargetfile, O_WRONLY\|O_CREAT, 0);	535	i = open (mtab_lock_targ, O_WRONLY\|O_CREAT, 0);
478	if (i < 0) {	536	if (i < 0) {
479	int errsv = errno;	537	int errsv = errno;
480	/* linktargetfile does not exist (as a file)	538	/* mtab_lock_targ does not exist (as a file)
481	and we cannot create it. Read-only filesystem?	539	and we cannot create it. Read-only filesystem?
482	Too many files open in the system?	540	Too many files open in the system?
483	Filesystem full? */	541	Filesystem full? */
484	die (EX_FILEIO, _("can't create lock file %s: %s "	542	die (EX_FILEIO, _("can't create lock file %s: %s "
485	"(use -n flag to override)"),	543	"(use -n flag to override)"),
486	linktargetfile, strerror (errsv));	544	mtab_lock_targ, strerror (errsv));
487	}	545	}
488	close(i);	546	close(i);
489		547
490	j = link(linktargetfile, MOUNTED_LOCK);	548	j = link(mtab_lock_targ, mtab_lock_path);
491	errsv = errno;	549	errsv = errno;
492		550
493	(void) unlink(linktargetfile);	551	(void) unlink(mtab_lock_targ);
494		552
495	if (j == 0)	553	if (j == 0)
496	we_created_lockfile = 1;	554	we_created_lockfile = 1;
Lines 498-507 Link Here
498	if (j < 0 && errsv != EEXIST) {	556	if (j < 0 && errsv != EEXIST) {
499	die (EX_FILEIO, _("can't link lock file %s: %s "	557	die (EX_FILEIO, _("can't link lock file %s: %s "
500	"(use -n flag to override)"),	558	"(use -n flag to override)"),
501	MOUNTED_LOCK, strerror (errsv));	559	mtab_lock_path, strerror (errsv));
502	}	560	}
503		561
504	fd = open (MOUNTED_LOCK, O_WRONLY);	562	fd = open (mtab_lock_path, O_WRONLY);
505		563
506	if (fd < 0) {	564	if (fd < 0) {
507	int errsv = errno;	565	int errsv = errno;
Lines 510-516 Link Here
510	continue;	568	continue;
511	die (EX_FILEIO, _("can't open lock file %s: %s "	569	die (EX_FILEIO, _("can't open lock file %s: %s "
512	"(use -n flag to override)"),	570	"(use -n flag to override)"),
513	MOUNTED_LOCK, strerror (errsv));	571	mtab_lock_path, strerror (errsv));
514	}	572	}
515		573
516	flock.l_type = F_WRLCK;	574	flock.l_type = F_WRLCK;
Lines 524-530 Link Here
524	if (verbose) {	582	if (verbose) {
525	int errsv = errno;	583	int errsv = errno;
526	printf(_("Can't lock lock file %s: %s\n"),	584	printf(_("Can't lock lock file %s: %s\n"),
527	MOUNTED_LOCK, strerror (errsv));	585	mtab_lock_path, strerror (errsv));
528	}	586	}
529	/* proceed anyway */	587	/* proceed anyway */
530	}	588	}
Lines 536-552 Link Here
536	if (fcntl (fd, F_SETLKW, &flock) == -1) {	594	if (fcntl (fd, F_SETLKW, &flock) == -1) {
537	int errsv = errno;	595	int errsv = errno;
538	die (EX_FILEIO, _("can't lock lock file %s: %s"),	596	die (EX_FILEIO, _("can't lock lock file %s: %s"),
539	MOUNTED_LOCK, (errno == EINTR) ?	597	mtab_lock_path, (errno == EINTR) ?
540	_("timed out") : strerror (errsv));	598	_("timed out") : strerror (errsv));
541	}	599	}
542	alarm(0);	600	alarm(0);
543	/* Limit the number of iterations - maybe there	601	/* Limit the number of iterations - maybe there
544	still is some old /etc/mtab~ */	602	still is some old lock */
545	if (tries++ > 3) {	603	if (tries++ > 3) {
546	if (tries > 5)	604	if (tries > 5)
547	die (EX_FILEIO, _("Cannot create link %s\n"	605	die (EX_FILEIO, _("Cannot create link %s\n"
548	"Perhaps there is a stale lock file?\n"),	606	"Perhaps there is a stale lock file?\n"),
549	MOUNTED_LOCK);	607	mtab_lock_path);
550	sleep(1);	608	sleep(1);
551	}	609	}
552	}	610	}
Lines 568-583 Link Here
568	void	626	void
569	update_mtab (const char dir, struct my_mntent instead) {	627	update_mtab (const char dir, struct my_mntent instead) {
570	mntFILE mfp, mftmp;	628	mntFILE mfp, mftmp;
571	const char *fnam = MOUNTED;	629	const char *fnam = mtab_path;
572	struct mntentchn mtabhead; /* dummy */	630	struct mntentchn mtabhead; /* dummy */
573	struct mntentchn mc, mc0, *absent = NULL;	631	struct mntentchn mc, mc0, *absent = NULL;
574		632
575	if (mtab_does_not_exist() \|\| mtab_is_a_symlink())	633	if (mtab_does_not_exist())
576	return;	634	return;
577		635
578	lock_mtab();	636	lock_mtab();
579		637
580	/* having locked mtab, read it again */	638	/* Having got the lock, we read mtab again */
581	mc0 = mc = &mtabhead;	639	mc0 = mc = &mtabhead;
582	mc->nxt = mc->prev = NULL;	640	mc->nxt = mc->prev = NULL;
583		641
Lines 619-629 Link Here
619	}	677	}
620		678
621	/* write chain to mtemp */	679	/* write chain to mtemp */
622	mftmp = my_setmntent (MOUNTED_TEMP, "w");	680	mftmp = my_setmntent (mtab_temp_path, "w");
623	if (mftmp == NULL \|\| mftmp->mntent_fp == NULL) {	681	if (mftmp == NULL \|\| mftmp->mntent_fp == NULL) {
624	int errsv = errno;	682	int errsv = errno;
625	error (_("cannot open %s (%s) - mtab not updated"),	683	error (_("cannot open %s (%s) - mtab not updated"),
626	MOUNTED_TEMP, strerror (errsv));	684	mtab_temp_path, strerror (errsv));
627	goto leave;	685	goto leave;
628	}	686	}
629		687
Lines 631-637 Link Here
631	if (my_addmntent(mftmp, &(mc->m)) == 1) {	689	if (my_addmntent(mftmp, &(mc->m)) == 1) {
632	int errsv = errno;	690	int errsv = errno;
633	die (EX_FILEIO, _("error writing %s: %s"),	691	die (EX_FILEIO, _("error writing %s: %s"),
634	MOUNTED_TEMP, strerror (errsv));	692	mtab_temp_path, strerror (errsv));
635	}	693	}
636	}	694	}
637		695
Lines 641-665 Link Here
641	S_IRUSR\|S_IWUSR\|S_IRGRP\|S_IROTH) < 0) {	699	S_IRUSR\|S_IWUSR\|S_IRGRP\|S_IROTH) < 0) {
642	int errsv = errno;	700	int errsv = errno;
643	fprintf(stderr, _("error changing mode of %s: %s\n"),	701	fprintf(stderr, _("error changing mode of %s: %s\n"),
644	MOUNTED_TEMP, strerror (errsv));	702	mtab_temp_path, strerror (errsv));
645	}	703	}
646	my_endmntent (mftmp);	704	my_endmntent (mftmp);
647		705
648	{ /*	706	{ /*
649	* If mount is setuid and some non-root user mounts sth,	707	* If mount is setuid and some non-root user mounts sth,
650	* then mtab.tmp might get the group of this user. Copy uid/gid	708	* then the temp file might get the group of this user.
651	* from the present mtab before renaming.	709	* Copy uid/gid from the present mtab before renaming.
652	*/	710	*/
653	struct stat sbuf;	711	struct stat sbuf;
654	if (stat (MOUNTED, &sbuf) == 0)	712	if (stat (mtab_path, &sbuf) == 0)
655	chown (MOUNTED_TEMP, sbuf.st_uid, sbuf.st_gid);	713	chown (mtab_temp_path, sbuf.st_uid, sbuf.st_gid);
656	}	714	}
657		715
658	/* rename mtemp to mtab */	716	/* rename mtemp to mtab */
659	if (rename (MOUNTED_TEMP, MOUNTED) < 0) {	717	if (rename (mtab_temp_path, mtab_path) < 0) {
660	int errsv = errno;	718	int errsv = errno;
661	fprintf(stderr, _("can't rename %s to %s: %s\n"),	719	fprintf(stderr, _("can't rename %s to %s: %s\n"),
662	MOUNTED_TEMP, MOUNTED, strerror(errsv));	720	mtab_temp_path, mtab_path, strerror(errsv));
663	}	721	}
664		722
665	leave:	723	leave: