[unix-history] / usr / src / usr.sbin / amd / config / mtab_file.c

/*
 * Copyright (c) 1990 Jan-Simon Pendry
 * Copyright (c) 1990 Imperial College of Science, Technology & Medicine
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Jan-Simon Pendry at Imperial College, London.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)mtab_file.c	5.3 (Berkeley) 5/12/91
 *
 * $Id: mtab_file.c,v 5.2.1.3 91/05/07 22:19:58 jsp Alpha $
 *
 */

#include "am.h"

#ifdef READ_MTAB_FROM_FILE

#ifdef USE_FCNTL
#include <fcntl.h>
#else
#include <sys/file.h>
#endif /* USE_FCNTL */

#ifdef UPDATE_MTAB

/*
 * Do strict /etc/mtab locking
 */
#define	MTAB_LOCKING

/*
 * Firewall mtab entries
 */
#define	MTAB_STRIPNL

#include <sys/stat.h>
static FILE *mnt_file;

/*
 * If the system is being trashed by something, then
 * opening mtab may fail with ENFILE.  So, go to sleep
 * for a second and try again. (Yes - this has happened to me.)
 *
 * Note that this *may* block the automounter, oh well. 
 * If we get to this state then things are badly wrong anyway...
 *
 * Give the system 10 seconds to recover but then give up.
 * Hopefully something else will exit and free up some file
 * table slots in that time.
 */
#define	NFILE_RETRIES	10 /* seconds */

#ifdef MTAB_LOCKING
#ifdef LOCK_FCNTL
static int lock(fd)
{
	int rc;
	struct flock lk;

	lk.l_type = F_WRLCK;
	lk.l_whence = 0;
	lk.l_start = 0;
	lk.l_len = 0;

again:
	rc = fcntl(fd, F_SETLKW, (caddr_t) &lk);
	if (rc < 0 && (errno == EACCES || errno == EAGAIN)) {
#ifdef DEBUG
		dlog("Blocked, trying to obtain exclusive mtab lock");
#endif /* DEBUG */
		sleep(1);
		goto again;
	}
	return rc;
}
#else
#define lock(fd) (flock((fd), LOCK_EX))
#endif /* LOCK_FCNTL */
#endif /* MTAB_LOCKING */

static FILE *open_locked_mtab(mtab_file, mode, fs)
char *mtab_file;
char *mode;
char *fs;
{
	FILE *mfp = 0;

#ifdef UPDATE_MTAB
	/*
	 * There is a possible race condition if two processes enter
	 * this routine at the same time.  One will be blocked by the
	 * exclusive lock below (or by the shared lock in setmntent)
	 * and by the time the second process has the exclusive lock
	 * it will be on the wrong underlying object.  To check for this
	 * the mtab file is stat'ed before and after all the locking
	 * sequence, and if it is a different file then we assume that
	 * it may be the wrong file (only "may", since there is another
	 * race between the initial stat and the setmntent).
	 *
	 * Simpler solutions to this problem are invited...
	 */
	int racing = 2;
#ifdef MTAB_LOCKING
	int rc;
	int retries = 0;
	struct stat st_before, st_after;
#endif /* MTAB_LOCKING */

	if (mnt_file) {
#ifdef DEBUG
		dlog("Forced close on %s in read_mtab", mtab_file);
#endif /* DEBUG */
		endmntent(mnt_file);
		mnt_file = 0;
	}

#ifdef MTAB_LOCKING
again:
	if (mfp) {
		endmntent(mfp);
		mfp = 0;
	}

	clock_valid = 0;
	if (stat(mtab_file, &st_before) < 0) {
		plog(XLOG_ERROR, "%s: stat: %m", mtab_file);
		if (errno == ESTALE) {
			/* happens occasionally */
			sleep(1);
			goto again;
		}
		return 0;
	}
#endif /* MTAB_LOCKING */
#endif /* UPDATE_MTAB */

eacces:
	mfp = setmntent(mtab_file, mode);
	if (!mfp) {
		/*
		 * Since setmntent locks the descriptor, it
		 * is possible it can fail... so retry if
		 * needed.
		 */
		if (errno == EACCES || errno == EAGAIN) {
#ifdef DEBUG
			dlog("Blocked, trying to obtain exclusive mtab lock");
#endif /* DEBUG */
			goto eacces;
		} else if (errno == ENFILE && retries++ < NFILE_RETRIES) {
			sleep(1);
			goto eacces;
		}

		plog(XLOG_ERROR, "setmntent(\"%s\", \"%s\"): %m", mtab_file, mode);
		return 0;
	}

#ifdef MTAB_LOCKING
#ifdef UPDATE_MTAB
	/*
	 * At this point we have an exclusive lock on the mount list,
	 * but it may be the wrong one so...
	 */

	/*
	 * Need to get an exclusive lock on the current
	 * mount table until we have a new copy written
	 * out, when the lock is released in free_mntlist.
	 * flock is good enough since the mount table is
	 * not shared between machines.
	 */
	do
		rc = lock(fileno(mfp));
	while (rc < 0 && errno == EINTR);
	if (rc < 0) {
		plog(XLOG_ERROR, "Couldn't lock %s: %m", mtab_file);
		endmntent(mfp);
		return 0;
	}
	/*
	 * Now check whether the mtab file has changed under our feet
	 */
	if (stat(mtab_file, &st_after) < 0) {
		plog(XLOG_ERROR, "%s: stat", mtab_file);
		goto again;
	}

	if (st_before.st_dev != st_after.st_dev ||
		st_before.st_ino != st_after.st_ino) {
			struct timeval tv;
			if (racing == 0) {
				/* Sometimes print a warning */
				plog(XLOG_WARNING,
					"Possible mount table race - retrying %s", fs);
			}
			racing = (racing+1) & 3;
			/*
			 * Take a nap.  From: Doug Kingston <dpk@morgan.com>
			 */
			tv.tv_sec = 0;
			tv.tv_usec = (mypid & 0x07) << 17;
			if (tv.tv_usec)
				if (select(0, (voidp) 0, (voidp) 0, (voidp) 0, &tv) < 0)
					plog(XLOG_WARNING, "mtab nap failed: %m");

			goto again;
	}
#endif /* UPDATE_MTAB */
#endif /* MTAB_LOCKING */

	return mfp;
}

/*
 * Unlock the mount table
 */
void unlock_mntlist P((void));
void unlock_mntlist()
{
	/*
	 * Release file lock, by closing the file
	 */
	if (mnt_file) {
		endmntent(mnt_file);
		mnt_file = 0;
	}
}

/*
 * Write out a mount list
 */
void rewrite_mtab(mp)
mntlist *mp;
{
	FILE *mfp;

	/*
	 * Concoct a temporary name in the same
	 * directory as the target mount table
	 * so that rename() will work.
	 */
	char tmpname[64];
	int retries;
	int tmpfd;
	char *cp;
	char *mcp = mtab;
	cp = strrchr(mcp, '/');
	if (cp) {
		bcopy(mcp, tmpname, cp - mcp);
		tmpname[cp-mcp] = '\0';
	} else {
		plog(XLOG_WARNING, "No '/' in mtab (%s), using \".\" as tmp directory", mtab);
		tmpname[0] = '.'; tmpname[1] = '\0';
	}
	strcat(tmpname, "/mtabXXXXXX");
	mktemp(tmpname);
	retries = 0;
enfile1:
	if ((tmpfd = open(tmpname, O_RDWR|O_CREAT|O_TRUNC, 0644)) < 0) {
		if (errno == ENFILE && retries++ < NFILE_RETRIES) {
			sleep(1);
			goto enfile1;
		}
		plog(XLOG_ERROR, "%s: open: %m", tmpname);
		return;
	}
	if (close(tmpfd) < 0)
		plog(XLOG_ERROR, "Couldn't close tmp file descriptor: %m");

	retries = 0;
enfile2:
	mfp = setmntent(tmpname, "w");
	if (!mfp) {
		if (errno == ENFILE && retries++ < NFILE_RETRIES) {
			sleep(1);
			goto enfile2;
		}
		plog(XLOG_ERROR, "setmntent(\"%s\", \"w\"): %m", tmpname);
		return;
	}

	while (mp) {
		if (mp->mnt)
			if (addmntent(mfp, mp->mnt))
				plog(XLOG_ERROR, "Can't write entry to %s", tmpname);
		mp = mp->mnext;
	}

	endmntent(mfp);

	/*
	 * Rename temporary mtab to real mtab
	 */
	if (rename(tmpname, mtab) < 0)
		plog(XLOG_ERROR, "rename %s to %s: %m", tmpname, mtab);
}

#ifdef MTAB_STRIPNL
static void mtab_stripnl(s)
char *s;
{
	do {
		s = strchr(s, '\n');
		if (s)
			*s++ = ' ';
	} while (s);
}
#endif /* MTAB_STRIPNL */

/*
 * Append a mntent structure to the
 * current mount table.
 */
void write_mntent(mp)
struct mntent *mp;
{
	int retries = 0;
	FILE *mfp;
enfile:
	mfp = open_locked_mtab(mtab, "a", mp->mnt_dir);
	if (mfp) {
#ifdef MTAB_STRIPNL
		mtab_stripnl(mp->mnt_opts);
#endif /* MTAB_STRIPNL */
		if (addmntent(mfp, mp))
			plog(XLOG_ERROR, "Couldn't write %s: %m", mtab);
		endmntent(mfp);
	} else {
		if (errno == ENFILE && retries < NFILE_RETRIES) {
			sleep(1);
			goto enfile;
		}
		plog(XLOG_ERROR, "setmntent(\"%s\", \"a\"): %m", mtab);
	}
}

#endif /* UPDATE_MTAB */

static struct mntent *mnt_dup(mp)
struct mntent *mp;
{
	struct mntent *new_mp = ALLOC(mntent);

	new_mp->mnt_fsname = strdup(mp->mnt_fsname);
	new_mp->mnt_dir = strdup(mp->mnt_dir);
	new_mp->mnt_type = strdup(mp->mnt_type);
	new_mp->mnt_opts = strdup(mp->mnt_opts);

	new_mp->mnt_freq = mp->mnt_freq;
	new_mp->mnt_passno = mp->mnt_passno;

#ifdef FIXUP_MNTENT_DUP
	/*
	 * Additional fields get dup'ed here
	 */
	FIXUP_MNTENT_DUP(new_mp, mp);
#endif

	return new_mp;
}

/*
 * Read a mount table into memory
 */
mntlist *read_mtab(fs)
char *fs;
{
	mntlist **mpp, *mhp;

	struct mntent *mep;
	FILE *mfp = open_locked_mtab(mtab, "r+", fs);

	if (!mfp)
		return 0;

	mpp = &mhp;

/*
 * XXX - In SunOS 4 there is (yet another) memory leak
 * which loses 1K the first time getmntent is called.
 * (jsp)
 */
	while (mep = getmntent(mfp)) {
		/*
		 * Allocate a new slot
		 */
		*mpp = ALLOC(mntlist);

		/*
		 * Copy the data returned by getmntent
		 */
		(*mpp)->mnt = mnt_dup(mep);

		/*
		 * Move to next pointer
		 */
		mpp = &(*mpp)->mnext;
	}
	*mpp = 0;

#ifdef UPDATE_MTAB
	/*
	 * If we are not updating the mount table then we
	 * can free the resources held here, otherwise they
	 * must be held until the mount table update is complete
	 */
	mnt_file = mfp;
#else
	endmntent(mfp);
#endif /* UPDATE_MTAB */

	return mhp;
}

#endif /* READ_MTAB_FROM_FILE */
Commit	Line	Data
e1a31032	1	/*
e1a31032 KM	2	* Copyright (c) 1990 Jan-Simon Pendry
	3	* Copyright (c) 1990 Imperial College of Science, Technology & Medicine
	4	* Copyright (c) 1990 The Regents of the University of California.
	5	* All rights reserved.
	6	*
	7	* This code is derived from software contributed to Berkeley by
	8	* Jan-Simon Pendry at Imperial College, London.
	9	*
af359dea C	10	* Redistribution and use in source and binary forms, with or without
	11	* modification, are permitted provided that the following conditions
	12	* are met:
	13	* 1. Redistributions of source code must retain the above copyright
	14	* notice, this list of conditions and the following disclaimer.
	15	* 2. Redistributions in binary form must reproduce the above copyright
	16	* notice, this list of conditions and the following disclaimer in the
	17	* documentation and/or other materials provided with the distribution.
	18	* 3. All advertising materials mentioning features or use of this software
	19	* must display the following acknowledgement:
	20	* This product includes software developed by the University of
	21	* California, Berkeley and its contributors.
	22	* 4. Neither the name of the University nor the names of its contributors
	23	* may be used to endorse or promote products derived from this software
	24	* without specific prior written permission.
	25	*
	26	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	27	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	28	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	29	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	30	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	31	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	32	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	33	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	34	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	35	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	36	* SUCH DAMAGE.
	37	*
	38	* @(#)mtab_file.c 5.3 (Berkeley) 5/12/91
	39	*
	40	* $Id: mtab_file.c,v 5.2.1.3 91/05/07 22:19:58 jsp Alpha $
e1a31032	41	*
e1a31032 KM	42	*/
	43
	44	#include "am.h"
	45
	46	#ifdef READ_MTAB_FROM_FILE
	47
	48	#ifdef USE_FCNTL
	49	#include <fcntl.h>
	50	#else
	51	#include <sys/file.h>
	52	#endif /* USE_FCNTL */
	53
	54	#ifdef UPDATE_MTAB
	55
	56	/*
	57	* Do strict /etc/mtab locking
	58	*/
	59	#define MTAB_LOCKING
	60
	61	/*
	62	* Firewall mtab entries
	63	*/
	64	#define MTAB_STRIPNL
	65
	66	#include <sys/stat.h>
	67	static FILE *mnt_file;
	68
	69	/*
	70	* If the system is being trashed by something, then
	71	* opening mtab may fail with ENFILE. So, go to sleep
	72	* for a second and try again. (Yes - this has happened to me.)
	73	*
	74	* Note that this may block the automounter, oh well.
	75	* If we get to this state then things are badly wrong anyway...
	76	*
	77	* Give the system 10 seconds to recover but then give up.
	78	* Hopefully something else will exit and free up some file
	79	* table slots in that time.
	80	*/
	81	#define NFILE_RETRIES 10 /* seconds */
	82
	83	#ifdef MTAB_LOCKING
	84	#ifdef LOCK_FCNTL
	85	static int lock(fd)
	86	{
	87	int rc;
	88	struct flock lk;
	89
	90	lk.l_type = F_WRLCK;
	91	lk.l_whence = 0;
	92	lk.l_start = 0;
	93	lk.l_len = 0;
	94
	95	again:
	96	rc = fcntl(fd, F_SETLKW, (caddr_t) &lk);
	97	if (rc < 0 && (errno == EACCES \|\| errno == EAGAIN)) {
	98	#ifdef DEBUG
	99	dlog("Blocked, trying to obtain exclusive mtab lock");
	100	#endif /* DEBUG */
	101	sleep(1);
	102	goto again;
	103	}
	104	return rc;
	105	}
106	#else
107	#define lock(fd) (flock((fd), LOCK_EX))
108	#endif /* LOCK_FCNTL */
109	#endif /* MTAB_LOCKING */
110
2f619045 JSP	111	static FILE *open_locked_mtab(mtab_file, mode, fs)
	112	char *mtab_file;
	113	char *mode;
	114	char *fs;
	115	{
	116	FILE *mfp = 0;
	117
	118	#ifdef UPDATE_MTAB
	119	/*
	120	* There is a possible race condition if two processes enter
	121	* this routine at the same time. One will be blocked by the
	122	* exclusive lock below (or by the shared lock in setmntent)
	123	* and by the time the second process has the exclusive lock
	124	* it will be on the wrong underlying object. To check for this
	125	* the mtab file is stat'ed before and after all the locking
	126	* sequence, and if it is a different file then we assume that
	127	* it may be the wrong file (only "may", since there is another
	128	* race between the initial stat and the setmntent).
	129	*
	130	* Simpler solutions to this problem are invited...
	131	*/
	132	int racing = 2;
	133	#ifdef MTAB_LOCKING
	134	int rc;
	135	int retries = 0;
	136	struct stat st_before, st_after;
	137	#endif /* MTAB_LOCKING */
	138
	139	if (mnt_file) {
	140	#ifdef DEBUG
	141	dlog("Forced close on %s in read_mtab", mtab_file);
	142	#endif /* DEBUG */
	143	endmntent(mnt_file);
	144	mnt_file = 0;
	145	}
	146
	147	#ifdef MTAB_LOCKING
	148	again:
	149	if (mfp) {
	150	endmntent(mfp);
	151	mfp = 0;
	152	}
	153
	154	clock_valid = 0;
	155	if (stat(mtab_file, &st_before) < 0) {
	156	plog(XLOG_ERROR, "%s: stat: %m", mtab_file);
	157	if (errno == ESTALE) {
	158	/* happens occasionally */
	159	sleep(1);
	160	goto again;
	161	}
	162	return 0;
	163	}
	164	#endif /* MTAB_LOCKING */
	165	#endif /* UPDATE_MTAB */
	166
	167	eacces:
	168	mfp = setmntent(mtab_file, mode);
	169	if (!mfp) {
	170	/*
	171	* Since setmntent locks the descriptor, it
	172	* is possible it can fail... so retry if
	173	* needed.
	174	*/
175	if (errno == EACCES \|\| errno == EAGAIN) {
176	#ifdef DEBUG
177	dlog("Blocked, trying to obtain exclusive mtab lock");
178	#endif /* DEBUG */
179	goto eacces;
180	} else if (errno == ENFILE && retries++ < NFILE_RETRIES) {
181	sleep(1);
182	goto eacces;
183	}
184
185	plog(XLOG_ERROR, "setmntent(\"%s\", \"%s\"): %m", mtab_file, mode);
186	return 0;
187	}
188
189	#ifdef MTAB_LOCKING
190	#ifdef UPDATE_MTAB
191	/*
192	* At this point we have an exclusive lock on the mount list,
193	* but it may be the wrong one so...
194	*/
195
196	/*
197	* Need to get an exclusive lock on the current
198	* mount table until we have a new copy written
199	* out, when the lock is released in free_mntlist.
200	* flock is good enough since the mount table is
201	* not shared between machines.
202	*/
203	do
204	rc = lock(fileno(mfp));
205	while (rc < 0 && errno == EINTR);
206	if (rc < 0) {
207	plog(XLOG_ERROR, "Couldn't lock %s: %m", mtab_file);
208	endmntent(mfp);
209	return 0;
210	}
211	/*
212	* Now check whether the mtab file has changed under our feet
213	*/
214	if (stat(mtab_file, &st_after) < 0) {
215	plog(XLOG_ERROR, "%s: stat", mtab_file);
216	goto again;
217	}
218
219	if (st_before.st_dev != st_after.st_dev \|\|
220	st_before.st_ino != st_after.st_ino) {
221	struct timeval tv;
222	if (racing == 0) {
223	/* Sometimes print a warning */
224	plog(XLOG_WARNING,
225	"Possible mount table race - retrying %s", fs);
226	}
227	racing = (racing+1) & 3;
228	/*
229	* Take a nap. From: Doug Kingston <dpk@morgan.com>
230	*/
231	tv.tv_sec = 0;
232	tv.tv_usec = (mypid & 0x07) << 17;
233	if (tv.tv_usec)
234	if (select(0, (voidp) 0, (voidp) 0, (voidp) 0, &tv) < 0)
235	plog(XLOG_WARNING, "mtab nap failed: %m");
236
237	goto again;
238	}
239	#endif /* UPDATE_MTAB */
240	#endif /* MTAB_LOCKING */
241
242	return mfp;
243	}
244
e1a31032 KM	245	/*
	246	* Unlock the mount table
	247	*/
2f619045	248	void unlock_mntlist P((void));
e1a31032 KM	249	void unlock_mntlist()
	250	{
	251	/*
	252	* Release file lock, by closing the file
	253	*/
	254	if (mnt_file) {
	255	endmntent(mnt_file);
	256	mnt_file = 0;
	257	}
	258	}
	259
	260	/*
	261	* Write out a mount list
	262	*/
	263	void rewrite_mtab(mp)
	264	mntlist *mp;
	265	{
	266	FILE *mfp;
	267
	268	/*
	269	* Concoct a temporary name in the same
	270	* directory as the target mount table
	271	* so that rename() will work.
	272	*/
	273	char tmpname[64];
	274	int retries;
	275	int tmpfd;
	276	char *cp;
	277	char *mcp = mtab;
	278	cp = strrchr(mcp, '/');
	279	if (cp) {
	280	bcopy(mcp, tmpname, cp - mcp);
	281	tmpname[cp-mcp] = '\0';
	282	} else {
	283	plog(XLOG_WARNING, "No '/' in mtab (%s), using \".\" as tmp directory", mtab);
	284	tmpname[0] = '.'; tmpname[1] = '\0';
	285	}
	286	strcat(tmpname, "/mtabXXXXXX");
	287	mktemp(tmpname);
	288	retries = 0;
	289	enfile1:
	290	if ((tmpfd = open(tmpname, O_RDWR\|O_CREAT\|O_TRUNC, 0644)) < 0) {
	291	if (errno == ENFILE && retries++ < NFILE_RETRIES) {
	292	sleep(1);
	293	goto enfile1;
	294	}
	295	plog(XLOG_ERROR, "%s: open: %m", tmpname);
	296	return;
	297	}
	298	if (close(tmpfd) < 0)
	299	plog(XLOG_ERROR, "Couldn't close tmp file descriptor: %m");
	300
	301	retries = 0;
	302	enfile2:
	303	mfp = setmntent(tmpname, "w");
	304	if (!mfp) {
	305	if (errno == ENFILE && retries++ < NFILE_RETRIES) {
	306	sleep(1);
	307	goto enfile2;
	308	}
	309	plog(XLOG_ERROR, "setmntent(\"%s\", \"w\"): %m", tmpname);
	310	return;
	311	}
	312
313	while (mp) {
314	if (mp->mnt)
315	if (addmntent(mfp, mp->mnt))
316	plog(XLOG_ERROR, "Can't write entry to %s", tmpname);
317	mp = mp->mnext;
318	}
319
320	endmntent(mfp);
321
322	/*
323	* Rename temporary mtab to real mtab
324	*/
325	if (rename(tmpname, mtab) < 0)
326	plog(XLOG_ERROR, "rename %s to %s: %m", tmpname, mtab);
327	}
328
329	#ifdef MTAB_STRIPNL
330	static void mtab_stripnl(s)
331	char *s;
332	{
333	do {
334	s = strchr(s, '\n');
335	if (s)
336	*s++ = ' ';
337	} while (s);
338	}
339	#endif /* MTAB_STRIPNL */
340
341	/*
342	* Append a mntent structure to the
343	* current mount table.
344	*/
345	void write_mntent(mp)
346	struct mntent *mp;
347	{
348	int retries = 0;
349	FILE *mfp;
350	enfile:
2f619045	351	mfp = open_locked_mtab(mtab, "a", mp->mnt_dir);
e1a31032 KM	352	if (mfp) {
	353	#ifdef MTAB_STRIPNL
	354	mtab_stripnl(mp->mnt_opts);
	355	#endif /* MTAB_STRIPNL */
	356	if (addmntent(mfp, mp))
	357	plog(XLOG_ERROR, "Couldn't write %s: %m", mtab);
	358	endmntent(mfp);
	359	} else {
	360	if (errno == ENFILE && retries < NFILE_RETRIES) {
	361	sleep(1);
	362	goto enfile;
	363	}
	364	plog(XLOG_ERROR, "setmntent(\"%s\", \"a\"): %m", mtab);
	365	}
	366	}
	367
	368	#endif /* UPDATE_MTAB */
	369
	370	static struct mntent *mnt_dup(mp)
	371	struct mntent *mp;
	372	{
	373	struct mntent *new_mp = ALLOC(mntent);
	374
	375	new_mp->mnt_fsname = strdup(mp->mnt_fsname);
	376	new_mp->mnt_dir = strdup(mp->mnt_dir);
	377	new_mp->mnt_type = strdup(mp->mnt_type);
	378	new_mp->mnt_opts = strdup(mp->mnt_opts);
	379
	380	new_mp->mnt_freq = mp->mnt_freq;
	381	new_mp->mnt_passno = mp->mnt_passno;
	382
2f619045 JSP	383	#ifdef FIXUP_MNTENT_DUP
	384	/*
	385	* Additional fields get dup'ed here
	386	*/
	387	FIXUP_MNTENT_DUP(new_mp, mp);
	388	#endif
	389
e1a31032 KM	390	return new_mp;
	391	}
	392
	393	/*
	394	* Read a mount table into memory
	395	*/
	396	mntlist *read_mtab(fs)
	397	char *fs;
	398	{
	399	mntlist *mpp, mhp;
	400
	401	struct mntent *mep;
2f619045	402	FILE *mfp = open_locked_mtab(mtab, "r+", fs);
e1a31032	403
2f619045	404	if (!mfp)
e1a31032	405	return 0;
e1a31032 KM	406
	407	mpp = &mhp;
	408
	409	/*
	410	* XXX - In SunOS 4 there is (yet another) memory leak
	411	* which loses 1K the first time getmntent is called.
	412	* (jsp)
	413	*/
	414	while (mep = getmntent(mfp)) {
	415	/*
	416	* Allocate a new slot
	417	*/
	418	*mpp = ALLOC(mntlist);
	419
	420	/*
	421	* Copy the data returned by getmntent
	422	*/
	423	(*mpp)->mnt = mnt_dup(mep);
	424
	425	/*
	426	* Move to next pointer
	427	*/
	428	mpp = &(*mpp)->mnext;
	429	}
	430	*mpp = 0;
	431
	432	#ifdef UPDATE_MTAB
	433	/*
	434	* If we are not updating the mount table then we
	435	* can free the resources held here, otherwise they
	436	* must be held until the mount table update is complete
	437	*/
	438	mnt_file = mfp;
	439	#else
	440	endmntent(mfp);
	441	#endif /* UPDATE_MTAB */
	442
	443	return mhp;
	444	}
	445
	446	#endif /* READ_MTAB_FROM_FILE */