1/*
2 * Copyright (c) 1988, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * $Id: uucplock.c,v 1.10 1998/06/10 00:16:28 brian Exp $
34 *
35 */
36
37#ifndef lint
38static const char sccsid[] = "@(#)uucplock.c 8.1 (Berkeley) 6/6/93";
39#endif /* not lint */
40
41#include <sys/types.h>
42#include <sys/file.h>
43#include <dirent.h>
44#include <errno.h>
45#include <unistd.h>
46#include <signal.h>
47#include <stdio.h>
48#include <stdlib.h>
49#include <paths.h>
50#include <string.h>
51#include "libutil.h"
52
53#define MAXTRIES 5
54
55#define LOCKTMP "LCKTMP..%d"
56#define LOCKFMT "LCK..%s"
57
58#define GORET(level, val) { err = errno; uuerr = (val); \
59 goto __CONCAT(ret, level); }
60
61/* Forward declarations */
62static int put_pid (int fd, pid_t pid);
63static pid_t get_pid (int fd,int *err);
64
65/*
66 * uucp style locking routines
67 */
68
69int
70uu_lock(const char *ttyname)
71{
72 int fd, tmpfd, i;
73 pid_t pid, pid_old;
74 char lckname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN],
75 lcktmpname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN];
76 int err, uuerr;
77
78 pid = getpid();
79 (void)snprintf(lcktmpname, sizeof(lcktmpname), _PATH_UUCPLOCK LOCKTMP,
80 pid);
81 (void)snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT,
82 ttyname);
83 if ((tmpfd = creat(lcktmpname, 0664)) < 0)
84 GORET(0, UU_LOCK_CREAT_ERR);
85
86 for (i = 0; i < MAXTRIES; i++) {
87 if (link (lcktmpname, lckname) < 0) {
88 if (errno != EEXIST)
89 GORET(1, UU_LOCK_LINK_ERR);
90 /*
91 * file is already locked
92 * check to see if the process holding the lock
93 * still exists
94 */
95 if ((fd = open(lckname, O_RDONLY)) < 0)
96 GORET(1, UU_LOCK_OPEN_ERR);
97
98 if ((pid_old = get_pid (fd, &err)) == -1)
99 GORET(2, UU_LOCK_READ_ERR);
100
101 close(fd);
102
103 if (kill(pid_old, 0) == 0 || errno != ESRCH)
104 GORET(1, UU_LOCK_INUSE);
105 /*
106 * The process that locked the file isn't running, so
107 * we'll lock it ourselves
108 */
109 (void)unlink(lckname);
110 } else {
111 if (!put_pid (tmpfd, pid))
112 GORET(3, UU_LOCK_WRITE_ERR);
113 break;
114 }
115 }
116 GORET(1, (i >= MAXTRIES) ? UU_LOCK_TRY_ERR : UU_LOCK_OK);
117
118ret3:
119 (void)unlink(lckname);
120 goto ret1;
121ret2:
122 (void)close(fd);
123ret1:
124 (void)close(tmpfd);
125 (void)unlink(lcktmpname);
126ret0:
127 errno = err;
128 return uuerr;
129}
130
131int
132uu_lock_txfr(const char *ttyname, pid_t pid)
133{
134 int fd, err;
135 char lckname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN];
136
137 snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT, ttyname);
138
139 if ((fd = open(lckname, O_RDWR)) < 0)
140 return UU_LOCK_OWNER_ERR;
141 if (get_pid(fd, &err) != getpid())
142 return UU_LOCK_OWNER_ERR;
143 lseek(fd, 0, SEEK_SET);
144 if (put_pid(fd, pid))
145 return UU_LOCK_WRITE_ERR;
146 close(fd);
147
148 return UU_LOCK_OK;
149}
150
151int
152uu_unlock(const char *ttyname)
153{
154 char tbuf[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN];
155
156 (void)snprintf(tbuf, sizeof(tbuf), _PATH_UUCPLOCK LOCKFMT, ttyname);
157 return unlink(tbuf);
158}
159
160const char *
161uu_lockerr(int uu_lockresult)
162{
163 static char errbuf[128];
164 char *fmt;
165
166 switch (uu_lockresult) {
167 case UU_LOCK_INUSE:
168 return "device in use";
169 case UU_LOCK_OK:
170 return "";
171 case UU_LOCK_OPEN_ERR:
172 fmt = "open error: %s";
173 break;
174 case UU_LOCK_READ_ERR:
175 fmt = "read error: %s";
176 break;
177 case UU_LOCK_CREAT_ERR:
178 fmt = "creat error: %s";
179 break;
180 case UU_LOCK_WRITE_ERR:
181 fmt = "write error: %s";
182 break;
183 case UU_LOCK_LINK_ERR:
184 fmt = "link error: %s";
185 break;
186 case UU_LOCK_TRY_ERR:
187 fmt = "too many tries: %s";
188 break;
189 case UU_LOCK_OWNER_ERR:
190 fmt = "not locking process: %s";
191 break;
192 default:
193 fmt = "undefined error: %s";
194 break;
195 }
196
197 (void)snprintf(errbuf, sizeof(errbuf), fmt, strerror(errno));
198 return errbuf;
199}
200
201static int
202put_pid(int fd, pid_t pid)
203{
204 char buf[32];
205 int len;
206
207 len = sprintf (buf, "%10d\n", (int)pid);
208 return write (fd, buf, len) == len;
209}
210
211static pid_t
212get_pid(int fd, int *err)
213{
214 int bytes_read;
215 char buf[32];
216 pid_t pid;
217
218 bytes_read = read (fd, buf, sizeof (buf) - 1);
219 if (bytes_read > 0) {
220 buf[bytes_read] = '\0';
221 pid = strtol (buf, (char **) NULL, 10);
222 } else {
223 pid = -1;
224 *err = bytes_read ? errno : EINVAL;
225 }
226 return pid;
227}
228
229/* end of uucplock.c */