85b5c5b8c9
move dotlocking code to dotlock.c. dotlocking code fixed to ignore whether or not the lockfile exists on open(). we only care about whether fcntl() was able to lock it.
90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
/* $Id$
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*
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* isync - IMAP4 to maildir mailbox synchronizer
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* Copyright (C) 2002 Michael R. Elkins <me@mutt.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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* this file contains routines to establish a mutex using a `dotlock' file
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*/
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/stat.h>
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#if TESTING
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#include <stdio.h>
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#endif
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#include "dotlock.h"
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static struct flock lck = { 0, SEEK_SET, 0, 0, 0 };
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static void make_lock (int type)
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{
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lck.l_type = type;
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lck.l_pid = getpid ();
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}
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int dotlock_lock (const char *path, int *fd)
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{
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*fd = open (path, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
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if (*fd == -1)
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return -1;
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make_lock (F_WRLCK);
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if (fcntl (*fd, F_SETLKW, &lck))
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{
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close (*fd);
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*fd = -1;
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return -1;
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}
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return 0;
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}
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int dotlock_unlock (int *fd)
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{
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int r = 0;
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if (*fd != -1)
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{
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make_lock (F_UNLCK);
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if (fcntl (*fd, F_SETLKW, &lck))
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r = -1;
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close (*fd);
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*fd = -1;
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}
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return r;
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}
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#if TESTING
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int main (void)
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{
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int fd;
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if (dotlock_lock ("./lock", &fd))
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{
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perror ("dotlock_lock");
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goto done;
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}
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puts("sleeping for 5 seconds");
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sleep(5);
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if (dotlock_unlock (&fd))
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{
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perror ("dotlock_lock");
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}
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done:
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exit (0);
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}
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#endif
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