150 lines
3.8 KiB
C
150 lines
3.8 KiB
C
/*****************************************************************************
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*
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* $Id: dirlock.c,v 1.1 2005/09/12 13:47:09 mbse Exp $
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* Purpose ...............: Lock a directory
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*
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*****************************************************************************
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* Copyright (C) 1997-2005
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*
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* Michiel Broek FIDO: 2:280/2802
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* Beekmansbos 10
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* 1971 BV IJmuiden
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* the Netherlands
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*
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* This file is part of MBSE BBS.
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*
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* This BBS is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2, or (at your option) any
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* later version.
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*
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* MBSE BBS is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* 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 MBSE BBS; see the file COPYING. If not, write to the Free
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* Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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*****************************************************************************/
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#include "../config.h"
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#include "../lib/mbselib.h"
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#include "dirlock.h"
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#define TMPNAME "TMP."
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#define LCKNAME "LOCKFILE"
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/*
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* Put a lock on a directory.
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*/
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int lockdir(char *directory)
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{
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char *Tmpfile, *lockfile;
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FILE *fp;
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pid_t oldpid;
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Tmpfile = calloc(PATH_MAX, sizeof(char));
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lockfile = calloc(PATH_MAX, sizeof(char));
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snprintf(Tmpfile, PATH_MAX, "%s/", directory);
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strcpy(lockfile, Tmpfile);
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snprintf(Tmpfile + strlen(Tmpfile), PATH_MAX, "%s%u", TMPNAME, getpid());
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snprintf(lockfile + strlen(lockfile), PATH_MAX - strlen(lockfile), "%s", LCKNAME);
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if ((fp = fopen(Tmpfile, "w")) == NULL) {
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WriteError("$Can't create lockfile \"%s\"", Tmpfile);
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free(Tmpfile);
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free(lockfile);
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return FALSE;
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}
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fprintf(fp, "%10u\n", getpid());
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fclose(fp);
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while (TRUE) {
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if (link(Tmpfile, lockfile) == 0) {
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unlink(Tmpfile);
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free(Tmpfile);
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free(lockfile);
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return TRUE;
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}
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if ((fp = fopen(lockfile, "r")) == NULL) {
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WriteError("$Can't open lockfile \"%s\"", Tmpfile);
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unlink(Tmpfile);
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free(Tmpfile);
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free(lockfile);
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return FALSE;
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}
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if (fscanf(fp, "%u", &oldpid) != 1) {
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WriteError("$Can't read old pid from \"%s\"", Tmpfile);
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fclose(fp);
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unlink(Tmpfile);
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free(Tmpfile);
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free(lockfile);
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return FALSE;
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}
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fclose(fp);
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if (kill(oldpid,0) == -1) {
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if (errno == ESRCH) {
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Syslog('+', "Stale lock found for pid %u", oldpid);
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unlink(lockfile);
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/* no return, try lock again */
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} else {
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WriteError("$Kill for %u failed",oldpid);
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unlink(Tmpfile);
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free(Tmpfile);
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free(lockfile);
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return FALSE;
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}
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} else {
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Syslog('+', "Already locked by, pid=%u", oldpid);
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unlink(Tmpfile);
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free(Tmpfile);
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free(lockfile);
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return FALSE;
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}
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}
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}
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/*
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* Unlock directory, make extra check to see if it is our own lock.
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*/
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void ulockdir(char *directory)
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{
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char *lockfile;
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FILE *fp;
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pid_t oldpid;
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lockfile = calloc(PATH_MAX, sizeof(char));
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snprintf(lockfile, PATH_MAX, "%s/", directory);
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snprintf(lockfile + strlen(lockfile), PATH_MAX - strlen(lockfile), "%s", LCKNAME);
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if ((fp = fopen(lockfile, "r")) == NULL) {
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/*
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* No lockfile found, so not removed.
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*/
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free(lockfile);
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return;
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}
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if (fscanf(fp, "%u", &oldpid) != 1) {
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WriteError("$Can't read old pid from \"%s\"", lockfile);
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} else {
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if (getpid() != oldpid) {
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WriteError("Attempt to remove lock %s of pid %d", lockfile, oldpid);
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} else {
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/*
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* Only remove our own lock.
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*/
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unlink(lockfile);
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}
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}
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fclose(fp);
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free(lockfile);
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}
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