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On failure, return various exit codes from <sysexits.h>. In particular,

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return EX_TEMPFAIL if the file was already locked.  This makes it easier
to distinguish between lock collisions and failures within the command
being executed.

Also, don't complain if the unlink() fails in the cleanup handler.  It
doesn't matter anyway, and it obscured the exit status returned from
the command that was executed.
This commit is contained in:
John Polstra 1997-01-09 19:53:21 +00:00
parent 5ef6c2c373
commit ae06cb4d32
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=21462
2 changed files with 34 additions and 17 deletions
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25
usr.bin/lockf/lockf.1
View File

@ -22,7 +22,7 @@
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $Id$
.\" $Id: lockf.1,v 1.1.1.1 1997/01/08 20:12:59 jdp Exp $
.\"
.Dd January 8, 1997
.Os FreeBSD
@ -85,11 +85,28 @@ break a lock that is held by another process.
.Sh DIAGNOSTICS
If
.Nm
is unable to acquire the lock, it returns an exit status of 1.
Otherwise, it returns the exit status produced by
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 F_CANTCREATX
.It Dv EX_TEMPFAIL
The specified lock file was already locked by another process.
.It Dv EX_CANTCREAT
.Nm
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., fork) failed unexpectedly.
.El
.Sh SEE ALSO
.Xr flock 2 .
.Xr flock 2 ,
.Xr sysexits 3 .
.Sh AUTHORS
John Polstra,
.Aq jdp@polstra.com .

26
usr.bin/lockf/lockf.c
View File

@ -22,7 +22,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id$
* $Id: lockf.c,v 1.1.1.1 1997/01/08 20:12:59 jdp Exp $
*/
#include <sys/types.h>
@ -34,6 +34,7 @@
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sysexits.h>
#include <unistd.h>
static int acquire_lock(const char *name);
@ -73,7 +74,7 @@ main(int argc, char **argv)
char *endptr;
waitsec = strtol(optarg, &endptr, 0);
if (*optarg == '\0' || *endptr != '\0' || waitsec < 0)
errx(1, "invalid timeout \"%s\"", optarg);
errx(EX_USAGE, "invalid timeout \"%s\"", optarg);
}
break;
@ -109,17 +110,17 @@ main(int argc, char **argv)
if (lockfd == -1) { /* We failed to acquire the lock. */
if (silent)
exit(1);
errx(1, "%s: already locked", lockname);
exit(EX_TEMPFAIL);
errx(EX_TEMPFAIL, "%s: already locked", lockname);
}
/* At this point, we own the lock. */
if (atexit(cleanup) == -1)
err(1, "atexit failed");
err(EX_OSERR, "atexit failed");
if ((child = fork()) == -1)
err(1, "cannot fork");
err(EX_OSERR, "cannot fork");
if (child == 0) { /* The child process. */
close(lockfd);
@ -135,7 +136,7 @@ main(int argc, char **argv)
signal(SIGTERM, killed);
if (waitpid(child, &status, 0) == -1)
err(1, "waitpid failed");
err(EX_OSERR, "waitpid failed");
return WIFEXITED(status) ? WEXITSTATUS(status) : 1;
}
@ -152,7 +153,7 @@ acquire_lock(const char *name)
if ((fd = open(name, O_RDONLY|O_CREAT|O_EXLOCK|O_NONBLOCK, 0666)) == -1) {
if (errno == EAGAIN || errno == EINTR)
return -1;
err(1, "cannot open %s", name);
err(EX_CANTCREAT, "cannot open %s", name);
}
return fd;
}
@ -163,8 +164,7 @@ acquire_lock(const char *name)
static void
cleanup(void)
{
if (unlink(lockname) == -1 && errno != ENOENT)
err(1, "cannot unlink %s", lockname);
unlink(lockname);
}
/*
@ -177,7 +177,7 @@ killed(int sig)
cleanup();
signal(sig, SIG_DFL);
if (kill(getpid(), sig) == -1)
err(1, "kill failed");
err(EX_OSERR, "kill failed");
}
/*
@ -192,7 +192,7 @@ timeout(int sig)
static void
usage(void)
{
errx(1, "usage: lockf [-s] [-t seconds] file command [arguments]");
errx(EX_USAGE, "usage: lockf [-s] [-t seconds] file command [arguments]");
}
/*
@ -206,7 +206,7 @@ wait_for_lock(const char *name)
if ((fd = open(name, O_RDONLY|O_EXLOCK)) == -1) {
if (errno == ENOENT || errno == EINTR)
return;
err(1, "cannot open %s", name);
err(EX_CANTCREAT, "cannot open %s", name);
}
close(fd);
return;