# Buildsheet autogenerated by ravenadm tool -- Do not edit.

NAMEBASE=		lockf
VERSION=		1
REVISION=		3
KEYWORDS=		sysutils
VARIANTS=		standard
SDESC[standard]=	FreeBSD's lockf command
HOMEPAGE=		https://www.freebsd.org/cgi/man.cgi?query=lockf
CONTACT=		nobody

DOWNLOAD_GROUPS=	none
SPKGS[standard]=	single

OPTIONS_AVAILABLE=	none
OPTIONS_STANDARD=	none

B_DEPS[sunos]=		libbsd4sol:single:standard

LICENSE=		BSD2CLAUSE:single
LICENSE_FILE=		BSD2CLAUSE:{{WRKDIR}}/LICENSE_BSD
LICENSE_AWK=		BSD2CLAUSE:"^$$"
LICENSE_SOURCE=		BSD2CLAUSE:{{FILESDIR}}/lockf.c
LICENSE_SCHEME=		solo

VAR_OPSYS[sunos]=	CFLAGS=-I{{LOCALBASE}}/include/bsd
			LDFLAGS=-lbsd

do-extract:
	@${MKDIR} ${WRKSRC}
	${CP} ${FILESDIR}/* ${WRKSRC}

do-build:
	(cd ${WRKSRC} && ${CC} -o lockf lockf.c ${CFLAGS} ${LDFLAGS})

do-install:
	${INSTALL_PROGRAM} ${WRKSRC}/lockf   ${STAGEDIR}${PREFIX}/bin/
	${INSTALL_MAN}     ${WRKSRC}/lockf.1 ${STAGEDIR}${MANPREFIX}/man/man1/

[FILE:166:descriptions/desc.single]
Imported from FreeBSD:
The lockf utility acquires an exclusive lock on a file, creating it if
necessary, and removing the file on exit unless explicitly told not to.


[FILE:36:manifests/plist.single]
bin/lockf
share/man/man1/lockf.1.gz


[FILE:4078:files/lockf.1]
.\"
.\" Copyright (C) 1998 John D. Polstra.  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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY JOHN D. POLSTRA 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 JOHN D. POLSTRA 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.
.\"
.\" $FreeBSD$
.\"
.Dd July 7, 1998
.Dt LOCKF 1
.Os
.Sh NAME
.Nm lockf
.Nd execute a command while holding a file lock
.Sh SYNOPSIS
.Nm
.Op Fl ks
.Op Fl t Ar seconds
.Ar file
.Ar command
.Op Ar arguments
.Sh DESCRIPTION
The
.Nm
utility acquires an exclusive lock on a
.Ar file ,
creating it if necessary,
.Bf Em
and removing the file on exit unless explicitly told not to.
.Ef
While holding the lock, it executes a
.Ar command
with optional
.Ar arguments .
After the
.Ar command
completes,
.Nm
releases the lock, and removes the
.Ar file
unless the
.Fl k
option is specified.
.Bx Ns -style
locking is used, as described in
.Xr flock 2 ;
the mere existence of the
.Ar file
is not considered to constitute a lock.
.Pp
If the
.Nm
utility is being used to facilitate concurrency between a number
of processes, it is recommended that the
.Fl k
option be used.
This will guarantee lock ordering, as well as implement
a performance enhanced algorithm which minimizes CPU load associated
with concurrent unlink, drop and re-acquire activity.
It should be noted
that if the
.Fl k
option is not used, then no guarantees around lock ordering can be made.
.Pp
The following options are supported:
.Bl -tag -width ".Fl t Ar seconds"
.It Fl k
Causes the lock file to be kept (not removed) after the command
completes.
.It Fl s
Causes
.Nm
to operate silently.
Failure to acquire the lock is indicated only in the exit status.
.It Fl t Ar seconds
Specifies a timeout for waiting for the lock.
By default,
.Nm
waits indefinitely to acquire the lock.
If a timeout is specified with this option,
.Nm
will wait at most the given number of
.Ar seconds
before giving up.
A timeout of 0 may be given, in which case
.Nm
will fail unless it can acquire the lock immediately.
When a lock times out,
.Ar command
is
.Em not
executed.
.El
.Pp
In no event will
.Nm
break a lock that is held by another process.
.Sh EXIT STATUS
If
.Nm
successfully acquires the lock, it returns the exit status produced by
.Ar command .
Otherwise, it returns one of the exit codes defined in
.Xr sysexits 3 ,
as follows:
.Bl -tag -width ".Dv EX_CANTCREAT"
.It Dv EX_TEMPFAIL
The specified lock file was already locked by another process.
.It Dv EX_CANTCREAT
The
.Nm
utility
was unable to create the lock file, e.g., because of insufficient access
privileges.
.It Dv EX_USAGE
There was an error on the
.Nm
command line.
.It Dv EX_OSERR
A system call (e.g.,
.Xr fork 2 )
failed unexpectedly.
.It Dv EX_SOFTWARE
The 
.Ar command
did not exit normally,
but may have been signaled or stopped.
.El
.Sh SEE ALSO
.Xr flock 2 ,
.Xr sysexits 3
.Sh HISTORY
A
.Nm
utility first appeared in
.Fx 2.2 .
.Sh AUTHORS
.An John Polstra Aq Mt jdp@polstra.com


[FILE:7017:files/lockf.c]
/*
 * Copyright (C) 1997 John D. Polstra.  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.
 *
 * THIS SOFTWARE IS PROVIDED BY JOHN D. POLSTRA 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 JOHN D. POLSTRA 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>

#include <sys/types.h>
#include <sys/wait.h>
#include <sys/file.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>

#ifndef O_EXLOCK
#define O_EXLOCK	0
#endif

#ifdef __sun__
#define OPEN_MODE	O_RDWR
#else
#define OPEN_MODE	O_RDONLY
#endif

#ifndef __unused
#define __unused	__attribute__((__unused__))
#endif

static int acquire_lock(const char *name, int flags);
static void cleanup(void);
static void killed(int sig);
static void timeout(int sig);
static void usage(void);
static void wait_for_lock(const char *name);

static const char *lockname;
static int lockfd = -1;
static int keep;
static volatile sig_atomic_t timed_out;

/*
 * Execute an arbitrary command while holding a file lock.
 */
int
main(int argc, char **argv)
{
	int ch, silent, status, waitsec;
	pid_t child;

	silent = keep = 0;
	waitsec = -1;	/* Infinite. */
	while ((ch = getopt(argc, argv, "skt:")) != -1) {
		switch (ch) {
		case 'k':
			keep = 1;
			break;
		case 's':
			silent = 1;
			break;
		case 't':
		{
			char *endptr;
			waitsec = strtol(optarg, &endptr, 0);
			if (*optarg == '\0' || *endptr != '\0' || waitsec < 0)
				errx(EX_USAGE,
				    "invalid timeout \"%s\"", optarg);
		}
			break;
		default:
			usage();
		}
	}
	if (argc - optind < 2)
		usage();
	lockname = argv[optind++];
	argc -= optind;
	argv += optind;
	if (waitsec > 0) {		/* Set up a timeout. */
		struct sigaction act;

		act.sa_handler = timeout;
		sigemptyset(&act.sa_mask);
		act.sa_flags = 0;	/* Note that we do not set SA_RESTART. */
		sigaction(SIGALRM, &act, NULL);
		alarm(waitsec);
	}
	/*
	 * If the "-k" option is not given, then we must not block when
	 * acquiring the lock.  If we did, then the lock holder would
	 * unlink the file upon releasing the lock, and we would acquire
	 * a lock on a file with no directory entry.  Then another
	 * process could come along and acquire the same lock.  To avoid
	 * this problem, we separate out the actions of waiting for the
	 * lock to be available and of actually acquiring the lock.
	 *
	 * That approach produces behavior that is technically correct;
	 * however, it causes some performance & ordering problems for
	 * locks that have a lot of contention.  First, it is unfair in
	 * the sense that a released lock isn't necessarily granted to
	 * the process that has been waiting the longest.  A waiter may
	 * be starved out indefinitely.  Second, it creates a thundering
	 * herd situation each time the lock is released.
	 *
	 * When the "-k" option is used, the unlink race no longer
	 * exists.  In that case we can block while acquiring the lock,
	 * avoiding the separate step of waiting for the lock.  This
	 * yields fairness and improved performance.
	 */
	lockfd = acquire_lock(lockname, O_NONBLOCK);
	while (lockfd == -1 && !timed_out && waitsec != 0) {
		if (keep)
			lockfd = acquire_lock(lockname, 0);
		else {
			wait_for_lock(lockname);
			lockfd = acquire_lock(lockname, O_NONBLOCK);
		}
	}
	if (waitsec > 0)
		alarm(0);
	if (lockfd == -1) {		/* We failed to acquire the lock. */
		if (silent)
			exit(EX_TEMPFAIL);
		errx(EX_TEMPFAIL, "%s: already locked", lockname);
	}
	/* At this point, we own the lock. */
	if (atexit(cleanup) == -1)
		err(EX_OSERR, "atexit failed");
	if ((child = fork()) == -1)
		err(EX_OSERR, "cannot fork");
	if (child == 0) {	/* The child process. */
		close(lockfd);
		execvp(argv[0], argv);
		warn("%s", argv[0]);
		_exit(1);
	}
	/* This is the parent process. */
	signal(SIGINT, SIG_IGN);
	signal(SIGQUIT, SIG_IGN);
	signal(SIGTERM, killed);
	if (waitpid(child, &status, 0) == -1)
		err(EX_OSERR, "waitpid failed");
	return (WIFEXITED(status) ? WEXITSTATUS(status) : EX_SOFTWARE);
}

/*
 * Try to acquire a lock on the given file, creating the file if
 * necessary.  The flags argument is O_NONBLOCK or 0, depending on
 * whether we should wait for the lock.  Returns an open file descriptor
 * on success, or -1 on failure.
 */
static int
acquire_lock(const char *name, int flags)
{
	int fd;

	if ((fd = open(name, OPEN_MODE|O_CREAT|O_EXLOCK|flags, 0666)) == -1) {
		if (errno == EAGAIN || errno == EINTR)
			return (-1);
		if (errno == ESTALE) { // NFS stale handle, wait 3.0 secs
			sleep (3);
			return (-1);
		}
		err(EX_CANTCREAT, "cannot open %s", name);
	}
	if (O_EXLOCK == 0) {
		if (flock(fd, LOCK_EX) != 0)
			err(EX_CANTCREAT, "cannot lock %s", name);
	}
	return (fd);
}

/*
 * Remove the lock file.
 */
static void
cleanup(void)
{

	if (keep)
		flock(lockfd, LOCK_UN);
	else
		unlink(lockname);
}

/*
 * Signal handler for SIGTERM.  Cleans up the lock file, then re-raises
 * the signal.
 */
static void
killed(int sig)
{

	cleanup();
	signal(sig, SIG_DFL);
	if (kill(getpid(), sig) == -1)
		err(EX_OSERR, "kill failed");
}

/*
 * Signal handler for SIGALRM.
 */
static void
timeout(int sig __unused)
{

	timed_out = 1;
}

static void
usage(void)
{

	fprintf(stderr,
	    "usage: lockf [-ks] [-t seconds] file command [arguments]\n");
	exit(EX_USAGE);
}

/*
 * Wait until it might be possible to acquire a lock on the given file.
 * If the file does not exist, return immediately without creating it.
 * If a stale NFS handle error comes, also return immediately
 */
static void
wait_for_lock(const char *name)
{
	int fd;

	if ((fd = open(name, OPEN_MODE|O_EXLOCK, 0666)) == -1) {
		if (errno == ENOENT || errno == EINTR || errno == ESTALE)
			return;
		err(EX_CANTCREAT, "cannot open %s", name);
	}
	if (O_EXLOCK == 0) {
		if (flock(fd, LOCK_EX) != 0)
			err(EX_CANTCREAT, "cannot lock %s", name);
	}
	close(fd);
}