Introduce uu_lock(), uu_unlock() and uu_lockerr()

into libutil.
Obtained from: FreeBSD
Reviewed by: Theo

src/include/paths.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: paths.h,v 1.9 1997/08/29 18:05:38 mickey Exp $	*/
+/*	$OpenBSD: paths.h,v 1.10 1997/11/09 00:29:02 bri Exp $	*/
 /*	$NetBSD: paths.h,v 1.7 1994/10/26 00:56:12 cgd Exp $	*/
 
 /*
@@ -71,6 +71,7 @@
 #define _PATH_BOOTDIR	"/usr/mdec/"
 #define	_PATH_DEV	"/dev/"
 #define	_PATH_TMP	"/tmp/"
+#define	_PATH_UUCPLOCK	"/var/spool/lock/"
 #define	_PATH_VARDB	"/var/db/"
 #define	_PATH_VARRUN	"/var/run/"
 #define	_PATH_VARTMP	"/var/tmp/"

src/lib/libutil/Makefile

@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.14 1997/06/17 10:10:41 niklas Exp $
+#	$OpenBSD: Makefile,v 1.15 1997/11/09 00:29:13 bri Exp $
 #	$NetBSD: Makefile,v 1.8 1996/05/16 07:03:28 thorpej Exp $
 
 LIB=	util
@@ -6,11 +6,12 @@ CFLAGS+=-DLIBC_SCCS
 
 HDRS=	util.h scsi.h
 SRCS=	getmaxpartitions.c getrawpartition.c login.c login_tty.c logout.c \
-	logwtmp.c opendev.c passwd.c pty.c readlabel.c scsi.c login_fbtab.c
+	logwtmp.c opendev.c passwd.c pty.c readlabel.c scsi.c login_fbtab.c \
+	uucplock.c
 
 # XXX need login_fbtab.3
 MAN=	getmaxpartitions.3 getrawpartition.3 login.3 opendev.3 openpty.3 \
-	pw_init.3 pw_lock.3 readlabelfs.3 scsi.3 pw_getconf.3
+	pw_init.3 pw_lock.3 readlabelfs.3 scsi.3 pw_getconf.3 uucplock.3
 
 MLINKS+=login.3 logout.3
 MLINKS+=login.3 logwtmp.3
@@ -36,6 +37,9 @@ MLINKS+=scsi.3 SCSIREQ_ERROR.3
 MLINKS+=scsi.3 scsi_open.3
 MLINKS+=scsi.3 scsi_debug.3
 MLINKS+=scsi.3 scsi_debug_output.3
+MLINKS+=uucplock.3 uu_lock.3
+MLINKS+=uucplock.3 uu_unlock.3
+MLINKS+=uucplock.3 uu_lockerr.3
 
 includes:
 	@cd ${.CURDIR}; for i in $(HDRS); do \

src/lib/libutil/shlib_version

@@ -1,2 +1,2 @@
 major=4
-minor=0
+minor=1

src/lib/libutil/util.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.h,v 1.6 1997/06/17 10:10:43 niklas Exp $	*/
+/*	$OpenBSD: util.h,v 1.7 1997/11/09 00:29:14 bri Exp $	*/
 /*	$NetBSD: util.h,v 1.2 1996/05/16 07:00:22 thorpej Exp $	*/
 
 /*-
@@ -76,6 +76,18 @@ int	getmaxpartitions __P((void));
 int	getrawpartition __P((void));
 void	login_fbtab __P((char *, uid_t, gid_t));
 char   *readlabelfs __P((char *, int));
+const char *uu_lockerr __P((int _uu_lockresult));
+int     uu_lock __P((const char *_ttyname)); 
+int     uu_unlock __P((const char *_ttyname));
 __END_DECLS
 
+#define UU_LOCK_INUSE (1)
+#define UU_LOCK_OK (0)
+#define UU_LOCK_OPEN_ERR (-1)
+#define UU_LOCK_READ_ERR (-2)
+#define UU_LOCK_CREAT_ERR (-3)
+#define UU_LOCK_WRITE_ERR (-4)
+#define UU_LOCK_LINK_ERR (-5)
+#define UU_LOCK_TRY_ERR (-6)
+
 #endif /* !_UTIL_H_ */

src/lib/libutil/uucplock.3

@@ -0,0 +1,160 @@
+.\" 
+.\" All rights reserved.
+.\" 
+.\" 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.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``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 DEVELOPERS 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.
+.\" 
+.\" $Id: uucplock.3,v 1.1 1997/11/09 00:29:14 bri Exp $
+.\" "
+.Dd March 30, 1997
+.Os
+.Dt uucplock 3
+.Sh NAME
+.Nm uu_lock , 
+.Nm uu_unlock ,
+.Nm uu_lockerr
+.Nd acquire and release control of a serial device
+.Sh SYNOPSIS
+.Fd #include <sys/types.h>
+.Fd #include <libutil.h>
+.Ft int
+.Fn uu_lock "const char *ttyname"
+.Ft int
+.Fn uu_unlock "const char *ttyname"
+.Ft const char *
+.Fn uu_lockerr "int uu_lockresult"
+.Pp
+Link with
+.Va -lutil
+on the
+.Xr cc 1
+command line.
+.Sh DESCRIPTION
+The
+.Fn uu_lock
+function attempts to create a lock file called
+.Pa /var/spool/lock/LCK..
+with a suffix given by the passed
+.Fa ttyname .
+If the file already exists, it is expected to contain the process
+id of the locking program.
+.Pp
+If the file does not already exist, or the owning process given by
+the process id found in the lock file is no longer running,
+.Fn uu_lock
+will write its own process id into the file and return success.
+.Pp
+.Fn uu_unlock
+removes the lockfile created by
+.Fn uu_lock
+for the given
+.Fa ttyname .
+Care should be taken that
+.Fn uu_lock
+was successful before calling
+.Fn uu_unlock .
+.Pp
+.Fn uu_lockerr
+returns an error string representing the error
+.Fa uu_lockresult ,
+as returned from
+.Fn uu_lock .
+.Sh RETURN VALUES
+.Fn uu_unlock
+returns 0 on success and -1 on failure.
+.Pp
+.Fn uu_lock
+may return any of the following values:
+.Pp
+.Dv UU_LOCK_INUSE:
+The lock is in use by another process.
+.Pp
+.Dv UU_LOCK_OK:
+The lock was successfully created.
+.Pp
+.Dv UU_LOCK_OPEN_ERR:
+The lock file could not be opened via
+.Xr open 2 .
+.Pp
+.Dv UU_LOCK_READ_ERR:
+The lock file could not be read via
+.Xr read 2 .
+.Pp
+.Dv UU_LOCK_CREAT_ERR:
+Can't create temporary lock file via
+.Xr creat 2 .
+.Pp
+.Dv UU_LOCK_WRITE_ERR:
+The current process id could not be written to the lock file via a call to
+.Xr write 2 .
+.Pp
+.Dv UU_LOCK_LINK_ERR:
+Can't link temporary lock file via
+.Xr link 2 .
+.Pp
+.Dv UU_LOCK_TRY_ERR:
+Locking attempts are failed after 5 tries.
+.Pp
+If a value of
+.Dv UU_LOCK_OK
+is passed to
+.Fn uu_lockerr ,
+an empty string is returned.
+Otherwise, a string specifying
+the reason for failure is returned.
+.Fn uu_lockerr
+uses the current value of
+.Va errno
+to determine the exact error.  Care should be made not to allow
+.Va errno
+to be changed between calls to
+.Fn uu_lock
+and
+.Fn uu_lockerr .
+.Sh ERRORS
+If
+.Fn uu_lock
+returns one of the four error values above, the global value
+.Va errno
+can be used to determine the cause.  Refer to the respective manual pages
+for further details.
+.Pp
+.Fn uu_unlock
+will set the global variable
+.Va errno
+to reflect the reason that the lock file could not be removed.
+Refer to the description of
+.Xr unlink 2
+for further details.
+.Sh SEE ALSO
+.Xr lseek 2 ,
+.Xr open 2 ,
+.Xr read 2 ,
+.Xr write 2
+.Sh BUGS
+It is possible that a stale lock is not recognised as such if a new
+processes is assigned the same processes id as the program that left
+the stale lock.
+.Pp
+The calling process must have write permissions to the
+.Pa /var/spool/lock
+directory.  There is no mechanism in place to ensure that the
+permissions of this directory are the same as those of the
+serial devices that might be locked.

src/lib/libutil/uucplock.c

@@ -0,0 +1,211 @@
+/*
+ * Copyright (c) 1988, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * 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.
+ *
+ * $Id: uucplock.c,v 1.1 1997/11/09 00:29:15 bri Exp $
+ *
+ */
+
+#ifndef lint
+static const char sccsid[] = "@(#)uucplock.c	8.1 (Berkeley) 6/6/93";
+#endif /* not lint */
+
+#include <sys/types.h>
+#include <sys/file.h>
+#include <dirent.h>
+#include <errno.h>
+#include <unistd.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <paths.h>
+#include <string.h>
+#include "util.h"
+
+#define MAXTRIES 5
+
+#define LOCKTMP "LCKTMP..%d"
+#define LOCKFMT "LCK..%s"
+
+#define GORET(level, val) { err = errno; uuerr = (val); \
+			    goto __CONCAT(ret, level); }
+
+/* Forward declarations */
+static int put_pid __P((int fd, pid_t pid));
+static pid_t get_pid __P((int fd,int *err));
+
+/*
+ * uucp style locking routines
+ */
+
+int
+uu_lock(ttyname)
+	const char *ttyname;
+{
+	int fd, tmpfd, i;
+	pid_t pid;
+	char lckname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN],
+	     lcktmpname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN];
+	int err, uuerr;
+
+	pid = getpid();
+	(void)snprintf(lcktmpname, sizeof(lcktmpname), _PATH_UUCPLOCK LOCKTMP,
+			pid);
+	(void)snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT,
+			ttyname);
+	if ((tmpfd = creat(lcktmpname, 0664)) < 0)
+		GORET(0, UU_LOCK_CREAT_ERR);
+
+	for (i = 0; i < MAXTRIES; i++) {
+		if (link (lcktmpname, lckname) < 0) {
+			if (errno != EEXIST)
+				GORET(1, UU_LOCK_LINK_ERR);
+			/*
+			 * file is already locked
+			 * check to see if the process holding the lock
+			 * still exists
+			 */
+			if ((fd = open(lckname, O_RDONLY)) < 0)
+				GORET(1, UU_LOCK_OPEN_ERR);
+
+			if ((pid = get_pid (fd, &err)) == -1)
+				GORET(2, UU_LOCK_READ_ERR);
+
+			close(fd);
+
+			if (kill(pid, 0) == 0 || errno != ESRCH)
+				GORET(1, UU_LOCK_INUSE);
+			/*
+			 * The process that locked the file isn't running, so
+			 * we'll lock it ourselves
+			 */
+			(void)unlink(lckname);
+		} else {
+			if (!put_pid (tmpfd, pid))
+				GORET(3, UU_LOCK_WRITE_ERR);
+			break;
+		}
+	}
+	GORET(1, (i >= MAXTRIES) ? UU_LOCK_TRY_ERR : UU_LOCK_OK);
+
+ret3:
+	(void)unlink(lckname);
+	goto ret1;
+ret2:
+	(void)close(fd);
+ret1:
+	(void)close(tmpfd);
+	(void)unlink(lcktmpname);
+ret0:
+	errno = err;
+	return uuerr;
+}
+
+int
+uu_unlock(ttyname)
+	const char *ttyname;
+{
+	char tbuf[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN];
+
+	(void)snprintf(tbuf, sizeof(tbuf), _PATH_UUCPLOCK LOCKFMT, ttyname);
+	return unlink(tbuf);
+}
+
+const char *
+uu_lockerr(uu_lockresult)
+	int uu_lockresult;
+{
+	static char errbuf[128];
+	char *fmt;
+
+	switch (uu_lockresult) {
+	case UU_LOCK_INUSE:
+		return "device in use";
+	case UU_LOCK_OK:
+		return "";
+	case UU_LOCK_OPEN_ERR:
+		fmt = "open error: %s";
+		break;
+	case UU_LOCK_READ_ERR:
+		fmt = "read error: %s";
+		break;
+	case UU_LOCK_CREAT_ERR:
+		fmt = "creat error: %s";
+		break;
+	case UU_LOCK_WRITE_ERR:
+		fmt = "write error: %s";
+		break;
+	case UU_LOCK_LINK_ERR:
+		fmt = "link error: %s";
+		break;
+	case UU_LOCK_TRY_ERR:
+		fmt = "too many tries: %s";
+		break;
+	default:
+		fmt = "undefined error: %s";
+		break;
+	}
+
+	(void)snprintf(errbuf, sizeof(errbuf), fmt, strerror(errno));
+	return errbuf;
+}
+
+static int
+put_pid(fd, pid)
+	int fd;
+	pid_t pid;
+{
+	char buf[32];
+	int len;
+
+	len = sprintf (buf, "%10d\n", pid);
+	return write (fd, buf, len) == len && ftruncate(fd, len);
+}
+
+static pid_t
+get_pid(fd, err)
+	int fd;
+	int *err;
+{
+	int bytes_read;
+	char buf[32];
+	pid_t pid;
+
+	bytes_read = read (fd, buf, sizeof (buf) - 1);
+	if (bytes_read > 0) {
+		buf[bytes_read] = '\0';
+		pid = strtoul (buf, (char **) NULL, 10);
+	} else {
+		pid = -1;
+		*err = bytes_read ? errno : EINVAL;
+	}
+	return pid;
+}