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/* $Id: pid.c 840 2007-09-09 12:17:42Z michael $
* $URL: https://ssl.bulix.org/svn/lcd4linux/trunk/pid.c $
*
* PID file handling
*
* Copyright (C) 1999, 2000 Michael Reinelt <michael@reinelt.co.at>
*
* This file is part of LCD4Linux.
*
* LCD4Linux is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* LCD4Linux 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
/*
* exported functions:
*
* int pid_init (const char *pidfile)
* returns 0 if PID file could be successfully created
* returns PID of an already running process
* returns -1 in case of an error
* int pid_exit (const char *pidfile)
* returns 0 if PID file could be successfully deleted
* otherwise returns error from unlink() call
*
*/
#include "config.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "debug.h"
#include "pid.h"
#include "qprintf.h"
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif
int pid_init(const char *pidfile)
{
char tmpfile[256];
char buffer[16];
int fd, len, pid;
qprintf(tmpfile, sizeof(tmpfile), "%s.%s", pidfile, "XXXXXX");
if ((fd = mkstemp(tmpfile)) == -1) {
error("mkstemp(%s) failed: %s", tmpfile, strerror(errno));
return -1;
}
if (fchmod(fd, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) == -1) {
error("fchmod(%s) failed: %s", tmpfile, strerror(errno));
close(fd);
unlink(tmpfile);
return -1;
}
qprintf(buffer, sizeof(buffer), "%d\n", (int) getpid());
len = strlen(buffer);
if (write(fd, buffer, len) != len) {
error("write(%s) failed: %s", tmpfile, strerror(errno));
close(fd);
unlink(tmpfile);
return -1;
}
close(fd);
while (link(tmpfile, pidfile) == -1) {
if (errno != EEXIST) {
error("link(%s, %s) failed: %s", tmpfile, pidfile, strerror(errno));
unlink(tmpfile);
return -1;
}
if ((fd = open(pidfile, O_RDONLY)) == -1) {
if (errno == ENOENT)
continue; /* pidfile disappared */
error("open(%s) failed: %s", pidfile, strerror(errno));
unlink(tmpfile);
return -1;
}
len = read(fd, buffer, sizeof(buffer) - 1);
if (len < 0) {
error("read(%s) failed: %s", pidfile, strerror(errno));
unlink(tmpfile);
return -1;
}
buffer[len] = '\0';
if (sscanf(buffer, "%d", &pid) != 1 || pid == 0) {
error("scan(%s) failed.", pidfile);
unlink(tmpfile);
return -1;
}
if (pid == getpid()) {
error("%s already locked by us. uh-oh...", pidfile);
unlink(tmpfile);
return 0;
}
if ((kill(pid, 0) == -1) && errno == ESRCH) {
error("removing stale PID file %s", pidfile);
if (unlink(pidfile) == -1 && errno != ENOENT) {
error("unlink(%s) failed: %s", pidfile, strerror(errno));
unlink(tmpfile);
return pid;
}
continue;
}
unlink(tmpfile);
return pid;
}
unlink(tmpfile);
return 0;
}
int pid_exit(const char *pidfile)
{
return unlink(pidfile);
}
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