freebsd-dev/lib/libutil/uucplock.c
Pedro F. Giffuni 8a16b7a18f General further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
2017-11-20 19:49:47 +00:00

230 lines
5.6 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* 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. 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#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>
#include <paths.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "libutil.h"
#define MAXTRIES 5
#define LOCKTMP "LCKTMP..%d"
#define LOCKFMT "LCK..%s"
#define GORET(level, val) { err = errno; uuerr = (val); \
goto __CONCAT(ret, level); }
/* Forward declarations */
static int put_pid (int fd, pid_t pid);
static pid_t get_pid (int fd,int *err);
/*
* uucp style locking routines
*/
int
uu_lock(const char *tty_name)
{
int fd, tmpfd, i;
pid_t pid, pid_old;
char lckname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN],
lcktmpname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN];
int err, uuerr;
pid = getpid();
(void)snprintf(lcktmpname, sizeof(lcktmpname), _PATH_UUCPLOCK LOCKTMP,
pid);
(void)snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT,
tty_name);
if ((tmpfd = open(lcktmpname, O_CREAT | O_TRUNC | O_WRONLY | O_CLOEXEC,
0664)) < 0)
GORET(0, UU_LOCK_CREAT_ERR);
for (i = 0; i < MAXTRIES; i++) {
if (link (lcktmpname, lckname) < 0) {
if (errno != EEXIST)
GORET(1, UU_LOCK_LINK_ERR);
/*
* file is already locked
* check to see if the process holding the lock
* still exists
*/
if ((fd = open(lckname, O_RDONLY | O_CLOEXEC)) < 0)
GORET(1, UU_LOCK_OPEN_ERR);
if ((pid_old = get_pid (fd, &err)) == -1)
GORET(2, UU_LOCK_READ_ERR);
close(fd);
if (kill(pid_old, 0) == 0 || errno != ESRCH)
GORET(1, UU_LOCK_INUSE);
/*
* The process that locked the file isn't running, so
* we'll lock it ourselves
*/
(void)unlink(lckname);
} else {
if (!put_pid (tmpfd, pid))
GORET(3, UU_LOCK_WRITE_ERR);
break;
}
}
GORET(1, (i >= MAXTRIES) ? UU_LOCK_TRY_ERR : UU_LOCK_OK);
ret3:
(void)unlink(lckname);
goto ret1;
ret2:
(void)close(fd);
ret1:
(void)close(tmpfd);
(void)unlink(lcktmpname);
ret0:
errno = err;
return uuerr;
}
int
uu_lock_txfr(const char *tty_name, pid_t pid)
{
int fd, err;
char lckname[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN];
snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT, tty_name);
if ((fd = open(lckname, O_RDWR | O_CLOEXEC)) < 0)
return UU_LOCK_OWNER_ERR;
if (get_pid(fd, &err) != getpid())
err = UU_LOCK_OWNER_ERR;
else {
lseek(fd, (off_t)0, SEEK_SET);
err = put_pid(fd, pid) ? 0 : UU_LOCK_WRITE_ERR;
}
close(fd);
return err;
}
int
uu_unlock(const char *tty_name)
{
char tbuf[sizeof(_PATH_UUCPLOCK) + MAXNAMLEN];
(void)snprintf(tbuf, sizeof(tbuf), _PATH_UUCPLOCK LOCKFMT, tty_name);
return unlink(tbuf);
}
const char *
uu_lockerr(int uu_lockresult)
{
static char errbuf[128];
const 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_CREAT_ERR:
fmt = "creat error: %s";
break;
case UU_LOCK_WRITE_ERR:
fmt = "write error: %s";
break;
case UU_LOCK_LINK_ERR:
fmt = "link error: %s";
break;
case UU_LOCK_TRY_ERR:
fmt = "too many tries: %s";
break;
case UU_LOCK_OWNER_ERR:
fmt = "not locking process: %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", (int)pid);
return write (fd, buf, (size_t)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 = (pid_t)strtol (buf, (char **) NULL, 10);
} else {
pid = -1;
*err = bytes_read ? errno : EINVAL;
}
return pid;
}
/* end of uucplock.c */