Importing usr.bin/shlock
No Minix-specific changes needed. Change-Id: I34fb2911de21f91b0c02387e57c3d6fd4502cd43
This commit is contained in:
parent
b6f0c43626
commit
152a15652d
6 changed files with 520 additions and 2 deletions
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@ -474,6 +474,7 @@
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./usr/bin/seq minix-sys
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./usr/bin/seq minix-sys
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./usr/bin/sha1 minix-sys
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./usr/bin/sha1 minix-sys
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./usr/bin/shar minix-sys
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./usr/bin/shar minix-sys
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./usr/bin/shlock minix-sys
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./usr/bin/shuffle minix-sys
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./usr/bin/shuffle minix-sys
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./usr/bin/shutdown minix-sys
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./usr/bin/shutdown minix-sys
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./usr/bin/size minix-sys binutils
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./usr/bin/size minix-sys binutils
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@ -2054,6 +2055,7 @@
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./usr/man/man1/sha1.1 minix-sys
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./usr/man/man1/sha1.1 minix-sys
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./usr/man/man1/shar.1 minix-sys
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./usr/man/man1/shar.1 minix-sys
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./usr/man/man1/shift.1 minix-sys
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./usr/man/man1/shift.1 minix-sys
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./usr/man/man1/shlock.1 minix-sys
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./usr/man/man1/shuffle.1 minix-sys
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./usr/man/man1/shuffle.1 minix-sys
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./usr/man/man1/size.1 minix-sys binutils
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./usr/man/man1/size.1 minix-sys binutils
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./usr/man/man1/sleep.1 minix-sys
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./usr/man/man1/sleep.1 minix-sys
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@ -208,6 +208,7 @@
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2013/09/28 12:00:00,usr.bin/rev
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2013/09/28 12:00:00,usr.bin/rev
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2010/02/19 16:35:27,usr.bin/sed
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2010/02/19 16:35:27,usr.bin/sed
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2010/05/27 08:40:19,usr.bin/seq
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2010/05/27 08:40:19,usr.bin/seq
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2012/10/17 12:00:00,usr.bin/shlock
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2013/06/02 12:00:00,usr.bin/shuffle
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2013/06/02 12:00:00,usr.bin/shuffle
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2012/10/17 12:00:00,usr.bin/sort
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2012/10/17 12:00:00,usr.bin/sort
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2012/10/17 12:00:00,usr.bin/split
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2012/10/17 12:00:00,usr.bin/split
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@ -23,8 +23,8 @@ SUBDIR= asa \
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printenv printf pwhash \
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printenv printf pwhash \
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renice rev \
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renice rev \
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\
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\
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shuffle sed seq \
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sed seq shlock \
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sort split stat su \
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shuffle sort split stat su \
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tee tic tput \
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tee tic tput \
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tr tsort tty unexpand unifdef \
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tr tsort tty unexpand unifdef \
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toproto \
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toproto \
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5
usr.bin/shlock/Makefile
Normal file
5
usr.bin/shlock/Makefile
Normal file
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@ -0,0 +1,5 @@
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# $NetBSD: Makefile,v 1.4 2009/04/14 22:15:26 lukem Exp $
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PROG= shlock
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.include <bsd.prog.mk>
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147
usr.bin/shlock/shlock.1
Normal file
147
usr.bin/shlock/shlock.1
Normal file
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@ -0,0 +1,147 @@
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.\" $NetBSD: shlock.1,v 1.11 2008/04/30 13:11:01 martin Exp $
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.\"
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.\" Copyright (c) 2006 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Erik E. Fair.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd June 29, 1997
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.Dt SHLOCK 1
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.Os
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.Sh NAME
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.Nm shlock
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.Nd create or verify a lock file for shell scripts
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.Sh SYNOPSIS
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.Nm
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.Op Fl du
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.Op Fl p Ar PID
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.Fl f
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.Ar lockfile
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.Sh DESCRIPTION
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The
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.Nm
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command can create or verify a lock file on behalf of a shell or
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other script program.
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When it attempts to create a lock file, if one already exists,
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.Nm
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verifies that it is or is not valid.
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If valid,
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.Nm
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will exit with a non-zero exit code.
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If invalid,
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.Nm
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will remove the lock file, and
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create a new one.
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.Pp
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.Nm
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uses the
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.Xr link 2
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system call to make the final target lock file, which is an atomic
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operation (i.e. "dot locking", so named for this mechanism's original
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use for locking system mailboxes).
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It puts the process ID ("PID") from the command line into the
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requested lock file.
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.Pp
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.Nm
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verifies that an extant lock file is still valid by
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using
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.Xr kill 2
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with a zero signal to check for the existence of the process that
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holds the lock.
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.Pp
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The
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.Fl d
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option causes
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.Nm
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to be verbose about what it is doing.
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.Pp
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The
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.Fl f
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argument with
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.Ar lockfile
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is always required.
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.Pp
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The
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.Fl p
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option with
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.Ar PID
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is given when the program is to create a lock file; when absent,
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.Nm
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will simply check for the validity of the lock file.
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.Pp
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The
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.Fl u
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option causes
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.Nm
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to read and write the PID as a binary pid_t, instead of as ASCII,
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to be compatible with the locks created by UUCP.
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.Sh EXIT STATUS
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A zero exit code indicates a valid lock file.
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.Sh EXAMPLES
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.Ss BOURNE SHELL
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.Bd -literal
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#!/bin/sh
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lckfile=/tmp/foo.lock
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if shlock -f ${lckfile} -p $$
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then
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# do what required the lock
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rm ${lckfile}
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else
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echo Lock ${lckfile} already held by `cat ${lckfile}`
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fi
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.Ed
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.Ss C SHELL
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.Bd -literal
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#!/bin/csh -f
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set lckfile=/tmp/foo.lock
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shlock -f ${lckfile} -p $$
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if ($status == 0) then
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# do what required the lock
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rm ${lckfile}
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else
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echo Lock ${lckfile} already held by `cat ${lckfile}`
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endif
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.Ed
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.Pp
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The examples assume that the file system where the lock file is to
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be created is writable by the user, and has space available.
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.Sh HISTORY
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.Nm
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was written for the first Network News Transfer Protocol (NNTP)
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software distribution, released in March 1986.
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The algorithm was suggested by Peter Honeyman,
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from work he did on HoneyDanBer UUCP.
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.Sh AUTHORS
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.An Erik E. Fair Aq fair@clock.org
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.Sh BUGS
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Does not work on NFS or other network file system on different
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systems because the disparate systems have disjoint PID spaces.
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.Pp
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Cannot handle the case where a lock file was not deleted, the
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process that created it has exited, and the system has created a
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|
new process with the same PID as in the dead lock file.
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The lock file will appear to be valid even though the process is
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unrelated to the one that created the lock in the first place.
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Always remove your lock files after you're done.
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363
usr.bin/shlock/shlock.c
Normal file
363
usr.bin/shlock/shlock.c
Normal file
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@ -0,0 +1,363 @@
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/* $NetBSD: shlock.c,v 1.12 2011/09/06 18:30:38 joerg Exp $ */
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/*-
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* Copyright (c) 2006 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Erik E. Fair.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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||||||
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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||||||
|
* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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** Program to produce reliable locks for shell scripts.
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** Algorithm suggested by Peter Honeyman, January 1984,
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** in connection with HoneyDanBer UUCP.
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**
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** I tried extending this to handle shared locks in November 1987,
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** and ran into to some fundamental problems:
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**
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** Neither 4.3 BSD nor System V have an open(2) with locking,
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** so that you can open a file and have it locked as soon as
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** it's real; you have to make two system calls, and there's
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** a race...
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**
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** When removing dead process id's from a list in a file,
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** you need to truncate the file (you don't want to create a
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|
** new one; see above); unfortunately for the portability of
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** this program, only 4.3 BSD has ftruncate(2).
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**
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** Erik E. Fair <fair@ucbarpa.berkeley.edu>, November 8, 1987
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**
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** Extensions for UUCP style locks (i.e. pid is an int in the file,
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** rather than an ASCII string). Also fix long standing bug with
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** full file systems and temporary files.
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**
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** Erik E. Fair <fair@apple.com>, November 12, 1989
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**
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** ANSIfy the code somewhat to make gcc -Wall happy with the code.
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** Submit to NetBSD
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**
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** Erik E. Fair <fair@clock.org>, May 20, 1997
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*/
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#include <sys/cdefs.h>
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|
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#ifndef lint
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__RCSID("$NetBSD: shlock.c,v 1.12 2011/09/06 18:30:38 joerg Exp $");
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#endif
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|
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#include <sys/types.h>
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|
#include <sys/file.h>
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|
#include <fcntl.h> /* Needed on hpux */
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||||||
|
#include <stdio.h>
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|
#include <signal.h>
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#include <errno.h>
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|
#include <string.h>
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|
#include <unistd.h>
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|
#include <stdlib.h>
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||||||
|
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#define LOCK_SET 0
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#define LOCK_FAIL 1
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||||||
|
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||||||
|
#define LOCK_GOOD 0
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||||||
|
#define LOCK_BAD 1
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||||||
|
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||||||
|
#define FAIL (-1)
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||||||
|
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||||||
|
#define TRUE 1
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||||||
|
#define FALSE 0
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||||||
|
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||||||
|
static int Debug = FALSE;
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|
static char *Pname;
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||||||
|
static const char USAGE[] = "%s: USAGE: %s [-du] [-p PID] -f file\n";
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||||||
|
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);
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||||||
|
|
||||||
|
/*
|
||||||
|
** Create a temporary file, all ready to lock with.
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||||||
|
** The file arg is so we get the filename right, if he
|
||||||
|
** gave us a full path, instead of using the current directory
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|
** which might not be in the same filesystem.
|
||||||
|
*/
|
||||||
|
static char *
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||||||
|
xtmpfile(char *file, pid_t pid, int uucpstyle)
|
||||||
|
{
|
||||||
|
int fd;
|
||||||
|
int len;
|
||||||
|
char *cp, buf[BUFSIZ];
|
||||||
|
static char tempname[BUFSIZ];
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||||||
|
|
||||||
|
sprintf(buf, "shlock%ld", (u_long)getpid());
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||||||
|
if ((cp = strrchr(strcpy(tempname, file), '/')) != NULL) {
|
||||||
|
*++cp = '\0';
|
||||||
|
(void) strcat(tempname, buf);
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||||||
|
} else
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||||||
|
(void) strcpy(tempname, buf);
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|
dprintf("%s: temporary filename: %s\n", Pname, tempname);
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|
|
||||||
|
sprintf(buf, "%ld\n", (u_long)pid);
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|
len = strlen(buf);
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|
openloop:
|
||||||
|
if ((fd = open(tempname, O_RDWR|O_CREAT|O_EXCL, 0644)) < 0) {
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|
switch(errno) {
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|
case EEXIST:
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|
dprintf("%s: file %s exists already.\n",
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|
Pname, tempname);
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|
if (unlink(tempname) < 0) {
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|
fprintf(stderr, E_unlk,
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||||||
|
Pname, tempname, strerror(errno));
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|
return (NULL);
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}
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/*
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||||||
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** Further profanity
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||||||
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*/
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goto openloop;
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default:
|
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|
fprintf(stderr, E_open,
|
||||||
|
Pname, tempname, strerror(errno));
|
||||||
|
return (NULL);
|
||||||
|
}
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||||||
|
}
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|
||||||
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/*
|
||||||
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** Write the PID into the temporary file before attempting to link
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||||||
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** to the actual lock file. That way we have a valid lock the instant
|
||||||
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** the link succeeds.
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*/
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||||||
|
if (uucpstyle ?
|
||||||
|
(write(fd, &pid, sizeof(pid)) != sizeof(pid)) :
|
||||||
|
(write(fd, buf, len) < 0))
|
||||||
|
{
|
||||||
|
fprintf(stderr, "%s: write(%s,%ld): %s\n",
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||||||
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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);
|
||||||
|
}
|
Loading…
Reference in a new issue