Add uu_lock_txfr() for donating locks to another process.

Reviewed by: Theo

src/lib/libutil/Makefile

@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.15 1997/11/09 00:29:13 bri Exp $
+#	$OpenBSD: Makefile,v 1.16 1998/06/08 20:28:23 brian Exp $
 #	$NetBSD: Makefile,v 1.8 1996/05/16 07:03:28 thorpej Exp $
 
 LIB=	util
@@ -40,6 +40,7 @@ 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
+MLINKS+=uucplock.3 uu_lock_txfr.3
 
 includes:
 	@cd ${.CURDIR}; for i in $(HDRS); do \

src/lib/libutil/shlib_version

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

src/lib/libutil/util.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.h,v 1.7 1997/11/09 00:29:14 bri Exp $	*/
+/*	$OpenBSD: util.h,v 1.8 1998/06/08 20:28:28 brian Exp $	*/
 /*	$NetBSD: util.h,v 1.2 1996/05/16 07:00:22 thorpej Exp $	*/
 
 /*-
@@ -78,6 +78,7 @@ 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_lock_txfr __P((const char *_ttyname, pid_t _pid));
 int     uu_unlock __P((const char *_ttyname));
 __END_DECLS
 
@@ -89,5 +90,6 @@ __END_DECLS
 #define UU_LOCK_WRITE_ERR (-4)
 #define UU_LOCK_LINK_ERR (-5)
 #define UU_LOCK_TRY_ERR (-6)
+#define UU_LOCK_OWNER_ERR (-7)
 
 #endif /* !_UTIL_H_ */

src/lib/libutil/uucplock.3

@@ -21,7 +21,7 @@
 .\" (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 $
+.\" $Id: uucplock.3,v 1.2 1998/06/08 20:28:29 brian Exp $
 .\" "
 .Dd March 30, 1997
 .Os
@@ -37,6 +37,8 @@
 .Ft int
 .Fn uu_lock "const char *ttyname"
 .Ft int
+.Fn uu_lock_txfr "const char *ttyname" "pid_t pid"
+.Ft int
 .Fn uu_unlock "const char *ttyname"
 .Ft const char *
 .Fn uu_lockerr "int uu_lockresult"
@@ -61,6 +63,11 @@ 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_lock_txfr
+transfers lock ownership to another process.
+.Fn uu_lock
+must have previously been successful.
+.Pp
 .Fn uu_unlock
 removes the lockfile created by
 .Fn uu_lock
@@ -128,10 +135,24 @@ to be changed between calls to
 .Fn uu_lock
 and
 .Fn uu_lockerr .
+.Pp
+.Fn uu_lock_txfr
+may return any of the following values:
+.Pp
+.Dv UU_LOCK_OK:
+The transfer was successful.  The specified process now holds the device
+lock.
+.Pp
+.Dv UU_LOCK_OWNER_ERR:
+The current process does not already own a lock on the specified device.
+.Pp
+.Dv UU_LOCK_WRITE_ERR:
+The new process id could not be written to the lock file via a call to
+.Xr write 2 .
 .Sh ERRORS
 If
 .Fn uu_lock
-returns one of the four error values above, the global value
+returns one of the error values above, the global value
 .Va errno
 can be used to determine the cause.  Refer to the respective manual pages
 for further details.

src/lib/libutil/uucplock.c

@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: uucplock.c,v 1.2 1997/11/09 04:05:33 bri Exp $
+ * $Id: uucplock.c,v 1.3 1998/06/08 20:28:30 brian Exp $
  *
  */
 
@@ -129,6 +129,28 @@ ret0:
 	return uuerr;
 }
 
+int
+uu_lock_txfr(ttyname, pid)
+	const char *ttyname;
+	pid_t pid;
+{
+	int fd, err;
+	char lckname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN];
+
+	snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT, ttyname);
+
+	if ((fd = open(lckname, O_RDWR)) < 0)
+		return UU_LOCK_OWNER_ERR;
+	if (get_pid(fd, &err) != getpid())
+		return UU_LOCK_OWNER_ERR;
+        lseek(fd, 0, SEEK_SET);
+	if (put_pid(fd, pid))
+		return UU_LOCK_WRITE_ERR;
+	close(fd);
+
+	return UU_LOCK_OK;
+}
+
 int
 uu_unlock(ttyname)
 	const char *ttyname;
@@ -169,6 +191,9 @@ uu_lockerr(uu_lockresult)
 	case UU_LOCK_TRY_ERR:
 		fmt = "too many tries: %s";
 		break;
+	case UU_LOCK_OWNER_ERR:
+		fmt = "not locking process: %s";
+		break;
 	default:
 		fmt = "undefined error: %s";
 		break;