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

into libutil.
Obtained from: FreeBSD
Reviewed by: Theo

1 files changed, 211 insertions, 0 deletions

diff --git a/lib/libutil/uucplock.c b/lib/libutil/uucplock.c
new file mode 100644
index 00000000000..5f879df8290
--- /dev/null
+++ b/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;
+}