145 lines
3.9 KiB
C
145 lines
3.9 KiB
C
/*
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* Copyright (c) 1988, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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static char sccsid[] = "@(#)uucplock.c 8.1 (Berkeley) 6/6/93";
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#endif /* not lint */
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#include <sys/types.h>
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#include <sys/file.h>
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#include <sys/dir.h>
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#include <errno.h>
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#include <syslog.h>
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#include <unistd.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <paths.h>
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#define LOCKFMT "LCK..%s"
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/* Forward declarations */
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static int put_pid (int fd, pid_t pid);
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static pid_t get_pid (int fd);
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/*
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* uucp style locking routines
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* return: 0 - success
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* -1 - failure
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*/
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int uu_lock (char *ttyname)
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{
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int fd;
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pid_t pid;
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char tbuf[MAXNAMLEN];
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(void)sprintf(tbuf, _PATH_UUCPLOCK LOCKFMT, ttyname);
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fd = open(tbuf, O_RDWR|O_CREAT|O_EXCL, 0660);
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if (fd < 0) {
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/*
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* file is already locked
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* check to see if the process holding the lock still exists
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*/
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fd = open(tbuf, O_RDWR, 0);
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if (fd < 0) {
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syslog(LOG_ERR, "lock open: %m");
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return(-1);
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}
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if ((pid = get_pid (fd)) == -1) {
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syslog(LOG_ERR, "lock read: %m");
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(void)close(fd);
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return(-1);
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}
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if (kill(pid, 0) == 0 || errno != ESRCH) {
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(void)close(fd); /* process is still running */
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return(-1);
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}
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/*
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* The process that locked the file isn't running, so
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* we'll lock it ourselves
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*/
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if (lseek(fd, 0L, L_SET) < 0) {
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syslog(LOG_ERR, "lock lseek: %m");
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(void)close(fd);
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return(-1);
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}
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/* fall out and finish the locking process */
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}
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pid = getpid();
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if (!put_pid (fd, pid)) {
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syslog(LOG_ERR, "lock write: %m");
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(void)close(fd);
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(void)unlink(tbuf);
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return(-1);
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}
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(void)close(fd);
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return(0);
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}
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int uu_unlock (char *ttyname)
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{
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char tbuf[MAXNAMLEN];
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(void)sprintf(tbuf, _PATH_UUCPLOCK LOCKFMT, ttyname);
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return(unlink(tbuf));
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}
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static int put_pid (int fd, pid_t pid)
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{
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char buf [32];
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int len;
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len = sprintf (buf, "%10ld\n", pid);
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return write (fd, buf, len) == len;
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}
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static pid_t get_pid (int fd)
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{
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int bytes_read;
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char buf [32];
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pid_t pid;
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bytes_read = read (fd, buf, sizeof (buf) - 1);
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if (bytes_read > 0) {
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buf [bytes_read] = '\0';
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pid = strtol (buf, (char **) NULL, 10);
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}
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else
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pid = -1;
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return pid;
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}
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/* end of uucplock.c */
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