Commit | Line | Data |
---|---|---|
6cdf4859 WJ |
1 | /* |
2 | * Copyright (c) 1988 The Regents of the University of California. | |
3 | * 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 | ||
34 | #ifndef lint | |
35 | static char sccsid[] = "@(#)uucplock.c 5.5 (Berkeley) 6/1/90"; | |
36 | #endif /* not lint */ | |
37 | ||
38 | #include <sys/types.h> | |
39 | #include <sys/file.h> | |
40 | #include <sys/dir.h> | |
41 | #include <errno.h> | |
42 | #include "pathnames.h" | |
43 | ||
44 | /* | |
45 | * uucp style locking routines | |
46 | * return: 0 - success | |
47 | * -1 - failure | |
48 | */ | |
49 | ||
50 | uu_lock(ttyname) | |
51 | char *ttyname; | |
52 | { | |
53 | extern int errno; | |
54 | int fd, pid; | |
55 | char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN]; | |
56 | off_t lseek(); | |
57 | ||
58 | (void)sprintf(tbuf, _PATH_LOCKDIRNAME, ttyname); | |
59 | fd = open(tbuf, O_RDWR|O_CREAT|O_EXCL, 0660); | |
60 | if (fd < 0) { | |
61 | /* | |
62 | * file is already locked | |
63 | * check to see if the process holding the lock still exists | |
64 | */ | |
65 | fd = open(tbuf, O_RDWR, 0); | |
66 | if (fd < 0) { | |
67 | perror("lock open"); | |
68 | return(-1); | |
69 | } | |
70 | if (read(fd, &pid, sizeof(pid)) != sizeof(pid)) { | |
71 | (void)close(fd); | |
72 | perror("lock read"); | |
73 | return(-1); | |
74 | } | |
75 | ||
76 | if (kill(pid, 0) == 0 || errno != ESRCH) { | |
77 | (void)close(fd); /* process is still running */ | |
78 | return(-1); | |
79 | } | |
80 | /* | |
81 | * The process that locked the file isn't running, so | |
82 | * we'll lock it ourselves | |
83 | */ | |
84 | if (lseek(fd, 0L, L_SET) < 0) { | |
85 | (void)close(fd); | |
86 | perror("lock lseek"); | |
87 | return(-1); | |
88 | } | |
89 | /* fall out and finish the locking process */ | |
90 | } | |
91 | pid = getpid(); | |
92 | if (write(fd, (char *)&pid, sizeof(pid)) != sizeof(pid)) { | |
93 | (void)close(fd); | |
94 | (void)unlink(tbuf); | |
95 | perror("lock write"); | |
96 | return(-1); | |
97 | } | |
98 | (void)close(fd); | |
99 | return(0); | |
100 | } | |
101 | ||
102 | uu_unlock(ttyname) | |
103 | char *ttyname; | |
104 | { | |
105 | char tbuf[sizeof(_PATH_LOCKDIRNAME) + MAXNAMLEN]; | |
106 | ||
107 | (void)sprintf(tbuf, _PATH_LOCKDIRNAME, ttyname); | |
108 | return(unlink(tbuf)); | |
109 | } |