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/*
LibRCC - module responsible for application synchronization (write access to
a shared config mainly)
Copyright (C) 2005-2008 Suren A. Chilingaryan <csa@dside.dyndns.org>
This library is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License version 2.1 or later
as published by the Free Software Foundation.
This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <errno.h>
#include "../config.h"
#ifdef HAVE_SYS_FILE_H
# include <sys/file.h>
#endif /* HAVE_SYS_FILE_H */
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif /* HAVE_UNISTD_H */
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif /* HAVE_SYS_TYPES_H */
#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
#endif /* HAVE_SYS_STAT_H */
#ifdef HAVE_FCNTL_H
# include <fcntl.h>
#endif /* HAVE_FCNTL_H */
#include "rcchome.h"
#include "rcclock.h"
static int lockfd = -1;
int rccLock() {
# ifdef HAVE_SYS_FILE_H
int err, i;
int size;
char *stmp;
struct timespec wait = { 0, 10000000 };
if (lockfd>=0) return -1;
size = strlen(rcc_home_dir) + 32;
stmp = (char*)malloc(size*sizeof(char));
if (!stmp) return -1;
sprintf(stmp,"%s/.rcc/", rcc_home_dir);
mkdir(stmp, 00755);
sprintf(stmp,"%s/.rcc/locks/", rcc_home_dir);
mkdir(stmp, 00700);
sprintf(stmp,"%s/.rcc/locks/rcc.lock", rcc_home_dir);
lockfd = open(stmp, O_RDWR|O_CREAT, 0644);
if (lockfd >= 0) {
for (err = -1, i = 0; i < (LIBRCC_LOCK_WAIT/10); i++) {
#if defined(HAVE_FLOCK)
err = flock(lockfd, LOCK_EX|LOCK_NB);
#elif defined(HAVE_LOCKF)
err = lockf(lockfd, F_TLOCK, 1);
#else
# warning "No file locking mechanism is detected"
err = 0; // We must believe in best
#endif
if ((err)&&(errno == EWOULDBLOCK)) nanosleep(&wait, NULL);
else break;
}
if (err) {
close(lockfd);
// Removing invalid lock
if (i == (LIBRCC_LOCK_WAIT/10)) {
remove(stmp);
lockfd = open(stmp, O_RDWR|O_CREAT, 0644);
if (lockfd >= 0) {
for (err = -1, i = 0; i < (LIBRCC_LOCK_WAIT/10); i++) {
#if defined(HAVE_FLOCK)
err = flock(lockfd, LOCK_EX|LOCK_NB);
#elif defined(HAVE_LOCKF)
err = lockf(lockfd, F_TLOCK, 1);
#endif
if ((err)&&(errno == EWOULDBLOCK)) nanosleep(&wait, NULL);
else break;
}
if (err) close(lockfd);
else return 0;
}
}
lockfd = -1;
return -1;
}
return 0;
}
return -1;
# else /* HAVE_SYS_FILE_H */
return 0;
# endif /* HAVE_SYS_FILE_H */
}
void rccUnLock() {
#ifdef HAVE_SYS_FILE_H
int size;
char *stmp;
if (lockfd<0) return;
size = strlen(rcc_home_dir) + 32;
stmp = (char*)malloc(size*sizeof(char));
if (!stmp) return;
sprintf(stmp,"%s/.rcc/locks/rcc.lock", rcc_home_dir);
#if defined(HAVE_FLOCK)
flock(lockfd, LOCK_UN);
#elif defined(HAVE_LOCKF)
lockf(lockfd, F_ULOCK, 1);
#endif
close(lockfd);
lockfd = -1;
#endif /* HAVE_SYS_FILE_H */
}
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