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Importing usr.bin/shlock

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No Minix-specific changes needed.

Change-Id: I34fb2911de21f91b0c02387e57c3d6fd4502cd43
This commit is contained in:
Thomas Cort 2013-10-30 08:24:41 -04:00
parent b6f0c43626
commit 152a15652d
6 changed files with 520 additions and 2 deletions
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2
distrib/sets/lists/minix/mi
View file

@ -474,6 +474,7 @@
./usr/bin/seq minix-sys
./usr/bin/sha1 minix-sys
./usr/bin/shar minix-sys
./usr/bin/shlock minix-sys
./usr/bin/shuffle minix-sys
./usr/bin/shutdown minix-sys
./usr/bin/size minix-sys binutils
@ -2054,6 +2055,7 @@
./usr/man/man1/sha1.1 minix-sys
./usr/man/man1/shar.1 minix-sys
./usr/man/man1/shift.1 minix-sys
./usr/man/man1/shlock.1 minix-sys
./usr/man/man1/shuffle.1 minix-sys
./usr/man/man1/size.1 minix-sys binutils
./usr/man/man1/sleep.1 minix-sys

1
releasetools/nbsd_ports
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@ -208,6 +208,7 @@
2013/09/28 12:00:00,usr.bin/rev
2010/02/19 16:35:27,usr.bin/sed
2010/05/27 08:40:19,usr.bin/seq
2012/10/17 12:00:00,usr.bin/shlock
2013/06/02 12:00:00,usr.bin/shuffle
2012/10/17 12:00:00,usr.bin/sort
2012/10/17 12:00:00,usr.bin/split

4
usr.bin/Makefile
View file

@ -23,8 +23,8 @@ SUBDIR= asa \
printenv printf pwhash \
renice rev \
\
shuffle sed seq \
sort split stat su \
sed seq shlock \
shuffle sort split stat su \
tee tic tput \
tr tsort tty unexpand unifdef \
toproto \

5
usr.bin/shlock/Makefile Normal file
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@ -0,0 +1,5 @@
# $NetBSD: Makefile,v 1.4 2009/04/14 22:15:26 lukem Exp $
PROG= shlock
.include <bsd.prog.mk>

147
usr.bin/shlock/shlock.1 Normal file
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@ -0,0 +1,147 @@
.\" $NetBSD: shlock.1,v 1.11 2008/04/30 13:11:01 martin Exp $
.\"
.\" Copyright (c) 2006 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Erik E. Fair.
.\"
.\" 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 THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
.\"
.Dd June 29, 1997
.Dt SHLOCK 1
.Os
.Sh NAME
.Nm shlock
.Nd create or verify a lock file for shell scripts
.Sh SYNOPSIS
.Nm
.Op Fl du
.Op Fl p Ar PID
.Fl f
.Ar lockfile
.Sh DESCRIPTION
The
.Nm
command can create or verify a lock file on behalf of a shell or
other script program.
When it attempts to create a lock file, if one already exists,
.Nm
verifies that it is or is not valid.
If valid,
.Nm
will exit with a non-zero exit code.
If invalid,
.Nm
will remove the lock file, and
create a new one.
.Pp
.Nm
uses the
.Xr link 2
system call to make the final target lock file, which is an atomic
operation (i.e. "dot locking", so named for this mechanism's original
use for locking system mailboxes).
It puts the process ID ("PID") from the command line into the
requested lock file.
.Pp
.Nm
verifies that an extant lock file is still valid by
using
.Xr kill 2
with a zero signal to check for the existence of the process that
holds the lock.
.Pp
The
.Fl d
option causes
.Nm
to be verbose about what it is doing.
.Pp
The
.Fl f
argument with
.Ar lockfile
is always required.
.Pp
The
.Fl p
option with
.Ar PID
is given when the program is to create a lock file; when absent,
.Nm
will simply check for the validity of the lock file.
.Pp
The
.Fl u
option causes
.Nm
to read and write the PID as a binary pid_t, instead of as ASCII,
to be compatible with the locks created by UUCP.
.Sh EXIT STATUS
A zero exit code indicates a valid lock file.
.Sh EXAMPLES
.Ss BOURNE SHELL
.Bd -literal
#!/bin/sh
lckfile=/tmp/foo.lock
if shlock -f ${lckfile} -p $$
then
# do what required the lock
rm ${lckfile}
else
echo Lock ${lckfile} already held by `cat ${lckfile}`
fi
.Ed
.Ss C SHELL
.Bd -literal
#!/bin/csh -f
set lckfile=/tmp/foo.lock
shlock -f ${lckfile} -p $$
if ($status == 0) then
# do what required the lock
rm ${lckfile}
else
echo Lock ${lckfile} already held by `cat ${lckfile}`
endif
.Ed
.Pp
The examples assume that the file system where the lock file is to
be created is writable by the user, and has space available.
.Sh HISTORY
.Nm
was written for the first Network News Transfer Protocol (NNTP)
software distribution, released in March 1986.
The algorithm was suggested by Peter Honeyman,
from work he did on HoneyDanBer UUCP.
.Sh AUTHORS
.An Erik E. Fair Aq fair@clock.org
.Sh BUGS
Does not work on NFS or other network file system on different
systems because the disparate systems have disjoint PID spaces.
.Pp
Cannot handle the case where a lock file was not deleted, the
process that created it has exited, and the system has created a
new process with the same PID as in the dead lock file.
The lock file will appear to be valid even though the process is
unrelated to the one that created the lock in the first place.
Always remove your lock files after you're done.

363
usr.bin/shlock/shlock.c Normal file
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@ -0,0 +1,363 @@
/* $NetBSD: shlock.c,v 1.12 2011/09/06 18:30:38 joerg Exp $ */
/*-
* Copyright (c) 2006 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Erik E. Fair.
*
* 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 THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
** Program to produce reliable locks for shell scripts.
** Algorithm suggested by Peter Honeyman, January 1984,
** in connection with HoneyDanBer UUCP.
**
** I tried extending this to handle shared locks in November 1987,
** and ran into to some fundamental problems:
**
** Neither 4.3 BSD nor System V have an open(2) with locking,
** so that you can open a file and have it locked as soon as
** it's real; you have to make two system calls, and there's
** a race...
**
** When removing dead process id's from a list in a file,
** you need to truncate the file (you don't want to create a
** new one; see above); unfortunately for the portability of
** this program, only 4.3 BSD has ftruncate(2).
**
** Erik E. Fair <fair@ucbarpa.berkeley.edu>, November 8, 1987
**
** Extensions for UUCP style locks (i.e. pid is an int in the file,
** rather than an ASCII string). Also fix long standing bug with
** full file systems and temporary files.
**
** Erik E. Fair <fair@apple.com>, November 12, 1989
**
** ANSIfy the code somewhat to make gcc -Wall happy with the code.
** Submit to NetBSD
**
** Erik E. Fair <fair@clock.org>, May 20, 1997
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: shlock.c,v 1.12 2011/09/06 18:30:38 joerg Exp $");
#endif
#include <sys/types.h>
#include <sys/file.h>
#include <fcntl.h> /* Needed on hpux */
#include <stdio.h>
#include <signal.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#define LOCK_SET 0
#define LOCK_FAIL 1
#define LOCK_GOOD 0
#define LOCK_BAD 1
#define FAIL (-1)
#define TRUE 1
#define FALSE 0
static int Debug = FALSE;
static char *Pname;
static const char USAGE[] = "%s: USAGE: %s [-du] [-p PID] -f file\n";
static const char E_unlk[] = "%s: unlink(%s): %s\n";
static const char E_open[] = "%s: open(%s): %s\n";
#define dprintf if (Debug) printf
/*
** Prototypes to make the ANSI compilers happy
** Didn't lint used to do type and argument checking?
** (and wasn't that sufficient?)
*/
/* the following is in case you need to make the prototypes go away. */
static char *xtmpfile(char *, pid_t, int);
static int p_exists(pid_t);
static int cklock(char *, int);
static int mklock(char *, pid_t, int);
__dead static void bad_usage(void);
/*
** Create a temporary file, all ready to lock with.
** The file arg is so we get the filename right, if he
** gave us a full path, instead of using the current directory
** which might not be in the same filesystem.
*/
static char *
xtmpfile(char *file, pid_t pid, int uucpstyle)
{
int fd;
int len;
char *cp, buf[BUFSIZ];
static char tempname[BUFSIZ];
sprintf(buf, "shlock%ld", (u_long)getpid());
if ((cp = strrchr(strcpy(tempname, file), '/')) != NULL) {
*++cp = '\0';
(void) strcat(tempname, buf);
} else
(void) strcpy(tempname, buf);
dprintf("%s: temporary filename: %s\n", Pname, tempname);
sprintf(buf, "%ld\n", (u_long)pid);
len = strlen(buf);
openloop:
if ((fd = open(tempname, O_RDWR|O_CREAT|O_EXCL, 0644)) < 0) {
switch(errno) {
case EEXIST:
dprintf("%s: file %s exists already.\n",
Pname, tempname);
if (unlink(tempname) < 0) {
fprintf(stderr, E_unlk,
Pname, tempname, strerror(errno));
return (NULL);
}
/*
** Further profanity
*/
goto openloop;
default:
fprintf(stderr, E_open,
Pname, tempname, strerror(errno));
return (NULL);
}
}
/*
** Write the PID into the temporary file before attempting to link
** to the actual lock file. That way we have a valid lock the instant
** the link succeeds.
*/
if (uucpstyle ?
(write(fd, &pid, sizeof(pid)) != sizeof(pid)) :
(write(fd, buf, len) < 0))
{
fprintf(stderr, "%s: write(%s,%ld): %s\n",
Pname, tempname, (u_long)pid, strerror(errno));
(void) close(fd);
if (unlink(tempname) < 0) {
fprintf(stderr, E_unlk,
Pname, tempname, strerror(errno));
}
return (NULL);
}
(void) close(fd);
return(tempname);
}
/*
** Does the PID exist?
** Send null signal to find out.
*/
static int
p_exists(pid_t pid)
{
dprintf("%s: process %ld is ", Pname, (u_long)pid);
if (pid <= 0) {
dprintf("invalid\n");
return(FALSE);
}
if (kill(pid, 0) < 0) {
switch(errno) {
case ESRCH:
dprintf("dead\n");
return(FALSE); /* pid does not exist */
case EPERM:
dprintf("alive\n");
return(TRUE); /* pid exists */
default:
dprintf("state unknown: %s\n", strerror(errno));
return(TRUE); /* be conservative */
}
}
dprintf("alive\n");
return(TRUE); /* pid exists */
}
/*
** Check the validity of an existing lock file.
**
** Read the PID out of the lock
** Send a null signal to determine whether that PID still exists
** Existence (or not) determines the validity of the lock.
**
** Two bigs wins to this algorithm:
**
** o Locks do not survive crashes of either the system or the
** application by any appreciable period of time.
**
** o No clean up to do if the system or application crashes.
**
*/
static int
cklock(char *file, int uucpstyle)
{
int fd = open(file, O_RDONLY);
ssize_t len;
pid_t pid;
char buf[BUFSIZ];
dprintf("%s: checking extant lock <%s>\n", Pname, file);
if (fd < 0) {
if (errno != ENOENT)
fprintf(stderr, E_open, Pname, file, strerror(errno));
return(TRUE); /* might or might not; conservatism */
}
if (uucpstyle ?
((len = read(fd, &pid, sizeof(pid))) != sizeof(pid)) :
((len = read(fd, buf, sizeof(buf))) <= 0))
{
close(fd);
dprintf("%s: lock file format error\n", Pname);
return(FALSE);
}
close(fd);
buf[len + 1] = '\0';
return(p_exists(uucpstyle ? pid : atoi(buf)));
}
static int
mklock(char *file, pid_t pid, int uucpstyle)
{
char *tmp;
int retcode = FALSE;
dprintf("%s: trying lock <%s> for process %ld\n", Pname, file,
(u_long)pid);
if ((tmp = xtmpfile(file, pid, uucpstyle)) == NULL)
return(FALSE);
linkloop:
if (link(tmp, file) < 0) {
switch(errno) {
case EEXIST:
dprintf("%s: lock <%s> already exists\n", Pname, file);
if (cklock(file, uucpstyle)) {
dprintf("%s: extant lock is valid\n", Pname);
break;
} else {
dprintf("%s: lock is invalid, removing\n",
Pname);
if (unlink(file) < 0) {
fprintf(stderr, E_unlk,
Pname, file, strerror(errno));
break;
}
}
/*
** I hereby profane the god of structured programming,
** Edsgar Dijkstra
*/
goto linkloop;
default:
fprintf(stderr, "%s: link(%s, %s): %s\n",
Pname, tmp, file, strerror(errno));
break;
}
} else {
dprintf("%s: got lock <%s>\n", Pname, file);
retcode = TRUE;
}
if (unlink(tmp) < 0) {
fprintf(stderr, E_unlk, Pname, tmp, strerror(errno));
}
return(retcode);
}
static void
bad_usage(void)
{
fprintf(stderr, USAGE, Pname, Pname);
exit(LOCK_FAIL);
}
int
main(int ac, char **av)
{
int x;
char *file = NULL;
pid_t pid = 0;
int uucpstyle = FALSE; /* indicating UUCP style locks */
int only_check = TRUE; /* don't make a lock */
Pname = ((Pname = strrchr(av[0], '/')) ? Pname + 1 : av[0]);
for(x = 1; x < ac; x++) {
if (av[x][0] == '-') {
switch(av[x][1]) {
case 'u':
uucpstyle = TRUE;
break;
case 'd':
Debug = TRUE;
break;
case 'p':
if (strlen(av[x]) > 2) {
pid = atoi(&av[x][2]);
} else {
if (++x >= ac) {
bad_usage();
}
pid = atoi(av[x]);
}
only_check = FALSE; /* wants one */
break;
case 'f':
if (strlen(av[x]) > 2) {
file = &av[x][2];
} else {
if (++x >= ac) {
bad_usage();
}
file = av[x];
}
break;
default:
bad_usage();
}
}
}
if (file == NULL || (!only_check && pid <= 0)) {
bad_usage();
}
if (only_check) {
exit(cklock(file, uucpstyle) ? LOCK_GOOD : LOCK_BAD);
}
exit(mklock(file, pid, uucpstyle) ? LOCK_SET : LOCK_FAIL);
}