diff options
Diffstat (limited to 'lib/libutil/uucplock.c')
| -rw-r--r-- | lib/libutil/uucplock.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/lib/libutil/uucplock.c b/lib/libutil/uucplock.c new file mode 100644 index 0000000..424ac26 --- /dev/null +++ b/lib/libutil/uucplock.c @@ -0,0 +1,227 @@ +/* + * 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. + * 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. + */ + +#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 */ |
