projects / unix-history / blame
| 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 | } |