1 /* $OpenBSD: uucplock.c,v 1.11 2006/03/16 19:32:46 deraadt Exp $ */
2 /* $NetBSD: uucplock.c,v 1.7 1997/02/11 09:24:08 mrg Exp $ */
3
4 /*-
5 * SPDX-License-Identifier: BSD-3-Clause
6 *
7 * Copyright (c) 1988, 1993
8 * The Regents of the University of California. All rights reserved.
9 *
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. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/types.h>
36 #include <sys/file.h>
37 #include <sys/dirent.h>
38 #include <stdio.h>
39 #include <string.h>
40 #include <signal.h>
41 #include <unistd.h>
42 #include <stdlib.h>
43 #include <errno.h>
44 #include "tip.h"
45 #include "pathnames.h"
46
47 /*
48 * uucp style locking routines
49 * return: 0 - success
50 * -1 - failure
51 */
52
53 int
uu_lock(char * ttyname)54 uu_lock(char *ttyname)
55 {
56 int fd, len;
57 char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN];
58 char text_pid[81];
59 pid_t pid;
60
61 (void)snprintf(tbuf, sizeof tbuf, _PATH_LOCKDIRNAME, ttyname);
62 fd = open(tbuf, O_RDWR|O_CREAT|O_EXCL, 0660);
63 if (fd < 0) {
64 /*
65 * file is already locked
66 * check to see if the process holding the lock still exists
67 */
68 fd = open(tbuf, O_RDWR, 0);
69 if (fd < 0) {
70 perror(tbuf);
71 fprintf(stderr, "Can't open lock file.\n");
72 return(-1);
73 }
74 len = read(fd, text_pid, sizeof(text_pid)-1);
75 if (len<=0) {
76 perror(tbuf);
77 (void)close(fd);
78 fprintf(stderr, "Can't read lock file.\n");
79 return(-1);
80 }
81 text_pid[len] = 0;
82 pid = atol(text_pid);
83
84 if (kill(pid, 0) == 0 || errno != ESRCH) {
85 (void)close(fd); /* process is still running */
86 return(-1);
87 }
88 /*
89 * The process that locked the file isn't running, so
90 * we'll lock it ourselves
91 */
92 fprintf(stderr, "Stale lock on %s PID=%ld... overriding.\n",
93 ttyname, (long)pid);
94 if (lseek(fd, (off_t)0, SEEK_SET) < 0) {
95 perror(tbuf);
96 (void)close(fd);
97 fprintf(stderr, "Can't seek lock file.\n");
98 return(-1);
99 }
100 /* fall out and finish the locking process */
101 }
102 pid = getpid();
103 (void)snprintf(text_pid, sizeof text_pid, "%10ld\n", (long)pid);
104 len = strlen(text_pid);
105 if (write(fd, text_pid, len) != len) {
106 (void)close(fd);
107 (void)unlink(tbuf);
108 perror("lock write");
109 return(-1);
110 }
111 (void)close(fd);
112 return(0);
113 }
114
115 int
uu_unlock(char * ttyname)116 uu_unlock(char *ttyname)
117 {
118 char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN];
119
120 (void)snprintf(tbuf, sizeof tbuf, _PATH_LOCKDIRNAME, ttyname);
121 unexcl();
122 return(unlink(tbuf));
123 }
124