/* * 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. * * $Id$ * */ #ifndef lint static const char sccsid[] = "@(#)uucplock.c 8.1 (Berkeley) 6/6/93"; #endif /* not lint */ #include #include #include #include #include #include #include #include #include #include #include "libutil.h" #define LOCKFMT "LCK..%s" /* Forward declarations */ static int put_pid (int fd, pid_t pid); static pid_t get_pid (int fd,int *err); /* * 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]; int err; (void)snprintf(tbuf, sizeof(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) return UU_LOCK_OPEN_ERR; if ((pid = get_pid (fd, &err)) == -1) { (void)close(fd); errno = err; return UU_LOCK_READ_ERR; } if (kill(pid, 0) == 0 || errno != ESRCH) { (void)close(fd); /* process is still running */ return UU_LOCK_INUSE; } /* * The process that locked the file isn't running, so * we'll lock it ourselves */ if (lseek(fd, (off_t) 0, L_SET) < 0) { err = errno; (void)close(fd); errno = err; return UU_LOCK_SEEK_ERR; } /* fall out and finish the locking process */ } pid = getpid(); if (!put_pid (fd, pid)) { err = errno; (void)close(fd); (void)unlink(tbuf); errno = err; return UU_LOCK_WRITE_ERR; } (void)close(fd); return UU_LOCK_OK; } int uu_unlock (char *ttyname) { char tbuf[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN]; (void)snprintf(tbuf, sizeof(tbuf), _PATH_UUCPLOCK LOCKFMT, ttyname); return unlink(tbuf); } char *uu_lockerr (int uu_lockresult) { static char errbuf[128]; char *fmt; switch (uu_lockresult) { case UU_LOCK_INUSE: return "device in use"; case UU_LOCK_OK: return ""; case UU_LOCK_OPEN_ERR: fmt = "open error: %s"; break; case UU_LOCK_READ_ERR: fmt = "read error: %s"; break; case UU_LOCK_SEEK_ERR: fmt = "seek error: %s"; break; case UU_LOCK_WRITE_ERR: fmt = "write error: %s"; break; default: fmt = "undefined error: %s"; break; } (void)snprintf(errbuf, sizeof(errbuf), fmt, strerror(errno)); return errbuf; } 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 *err) { 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; *err = bytes_read ? errno : EINVAL; } return pid; } /* end of uucplock.c */