BSD 4.4 Lite usr.sbin Sources

1 files changed, 472 insertions, 0 deletions

diff --git a/usr.sbin/amd/config/mtab_file.c b/usr.sbin/amd/config/mtab_file.c
new file mode 100644
index 0000000..8101f71
--- /dev/null
+++ b/usr.sbin/amd/config/mtab_file.c
@@ -0,0 +1,472 @@
+/*
+ * Copyright (c) 1990 Jan-Simon Pendry
+ * Copyright (c) 1990 Imperial College of Science, Technology & Medicine
+ * Copyright (c) 1990, 1993
+ *	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	8.1 (Berkeley) 6/6/93
+ *
+ * $Id: mtab_file.c,v 5.2.2.1 1992/02/09 15:10:42 jsp beta $
+ *
+ */
+
+#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;
+	int error = 0;
+
+	/*
+	 * 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);
+		error = 1;
+		goto out;
+	}
+
+	while (mp) {
+		if (mp->mnt) {
+			if (addmntent(mfp, mp->mnt)) {
+				plog(XLOG_ERROR, "Can't write entry to %s", tmpname);
+				error = 1;
+				goto out;
+			}
+		}
+		mp = mp->mnext;
+	}
+
+	/*
+	 * SunOS 4.1 manuals say that the return code from entmntent()
+	 * is always 1 and to treat as a void.  That means we need to
+	 * call fflush() to make sure the new mtab file got written.
+	 */
+	if (fflush(mfp)) {
+		plog(XLOG_ERROR, "flush new mtab file: %m");
+		error = 1;
+		goto out;
+	}
+
+	(void) endmntent(mfp);
+
+	/*
+	 * Rename temporary mtab to real mtab
+	 */
+	if (rename(tmpname, mtab) < 0) {
+		plog(XLOG_ERROR, "rename %s to %s: %m", tmpname, mtab);
+		error = 1;
+		goto out;
+	}
+
+out:
+	if (error)
+		(void) unlink(tmpname);
+}
+
+#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);
+		if (fflush(mfp))
+			plog(XLOG_ERROR, "Couldn't flush %s: %m", mtab);
+		(void) 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 */