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Diffstat (limited to 'sbin/startslip/uucplock.c')
-rw-r--r-- | sbin/startslip/uucplock.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/sbin/startslip/uucplock.c b/sbin/startslip/uucplock.c new file mode 100644 index 0000000..20eafe4 --- /dev/null +++ b/sbin/startslip/uucplock.c @@ -0,0 +1,161 @@ +/* + * Copyright (c) 1988, 1993 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#ifndef lint +static const char sccsid[] = "@(#)uucplock.c 8.1 (Berkeley) 6/6/93"; +#endif /* not lint */ + +#include <sys/types.h> +#include <sys/file.h> +#include <dirent.h> +#include <errno.h> +#ifndef USE_PERROR +#include <syslog.h> +#endif +#include <unistd.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <paths.h> + +#define LOCKFMT "LCK..%s" + +/* Forward declarations */ +static int put_pid (int fd, pid_t pid); +static pid_t get_pid (int fd); + +/* + * uucp style locking routines + * return: 0 - success + * -1 - failure + */ + +int uu_lock (char *ttyname) +{ + int fd; + pid_t pid; + char tbuf[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN]; + + (void)sprintf(tbuf, _PATH_UUCPLOCK LOCKFMT, ttyname); + fd = open(tbuf, O_RDWR|O_CREAT|O_EXCL, 0660); + if (fd < 0) { + /* + * file is already locked + * check to see if the process holding the lock still exists + */ + fd = open(tbuf, O_RDWR, 0); + if (fd < 0) { +#ifndef USE_PERROR + syslog(LOG_ERR, "lock open: %m"); +#else + perror("lock open"); +#endif + return(-1); + } + if ((pid = get_pid (fd)) == -1) { +#ifndef USE_PERROR + syslog(LOG_ERR, "lock read: %m"); +#else + perror("lock read"); +#endif + (void)close(fd); + return(-1); + } + + if (kill(pid, 0) == 0 || errno != ESRCH) { + (void)close(fd); /* process is still running */ + return(-1); + } + /* + * The process that locked the file isn't running, so + * we'll lock it ourselves + */ + if (lseek(fd, (off_t) 0, L_SET) < 0) { +#ifndef USE_PERROR + syslog(LOG_ERR, "lock lseek: %m"); +#else + perror("lock lseek"); +#endif + (void)close(fd); + return(-1); + } + /* fall out and finish the locking process */ + } + pid = getpid(); + if (!put_pid (fd, pid)) { +#ifndef USE_PERROR + syslog(LOG_ERR, "lock write: %m"); +#else + perror("lock write"); +#endif + (void)close(fd); + (void)unlink(tbuf); + return(-1); + } + (void)close(fd); + return(0); +} + +int uu_unlock (char *ttyname) +{ + char tbuf[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN]; + + (void)sprintf(tbuf, _PATH_UUCPLOCK LOCKFMT, ttyname); + return(unlink(tbuf)); +} + +static int put_pid (int fd, pid_t pid) +{ + char buf[32]; + int len; + + len = sprintf (buf, "%10d\n", pid); + return write (fd, buf, len) == len; +} + +static pid_t get_pid (int fd) +{ + int bytes_read; + char buf[32]; + pid_t pid; + + bytes_read = read (fd, buf, sizeof (buf) - 1); + if (bytes_read > 0) { + buf[bytes_read] = '\0'; + pid = strtol (buf, (char **) NULL, 10); + } else + pid = -1; + return pid; +} + +/* end of uucplock.c */ |