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/*
pidfile.c - interact with pidfiles
Copyright (c) 1995 Martin Schulze <Martin.Schulze@Linux.DE>
This file is part of the sysklogd package, a kernel and system log daemon.
This program 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 of the License, or
(at your option) any later version.
This program 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.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/* left unaltered for tinc -- Ivo Timmermans */
/*
* Sat Aug 19 13:24:33 MET DST 1995: Martin Schulze
* First version (v0.2) released
*/
#include "system.h"
#include "pidfile.h"
#ifndef HAVE_MINGW
/* read_pid
*
* Reads the specified pidfile and returns the read pid.
* 0 is returned if either there's no pidfile, it's empty
* or no pid can be read.
*/
pid_t read_pid(const char *pidfile) {
FILE *f;
long pid;
if(!(f = fopen(pidfile, "r"))) {
return 0;
}
if(fscanf(f, "%20ld", &pid) != 1) {
pid = 0;
}
fclose(f);
return (pid_t)pid;
}
/* check_pid
*
* Reads the pid using read_pid and looks up the pid in the process
* table (using /proc) to determine if the process already exists. If
* so the pid is returned, otherwise 0.
*/
pid_t check_pid(const char *pidfile) {
pid_t pid = read_pid(pidfile);
/* Amazing ! _I_ am already holding the pid file... */
if((!pid) || (pid == getpid())) {
return 0;
}
/*
* The 'standard' method of doing this is to try and do a 'fake' kill
* of the process. If an ESRCH error is returned the process cannot
* be found -- GW
*/
/* But... errno is usually changed only on error.. */
errno = 0;
if(kill(pid, 0) && errno == ESRCH) {
return 0;
}
return pid;
}
/* write_pid
*
* Writes the pid to the specified file. If that fails 0 is
* returned, otherwise the pid.
*/
pid_t write_pid(const char *pidfile) {
FILE *f;
int fd;
pid_t pid;
if((fd = open(pidfile, O_RDWR | O_CREAT, 0644)) == -1) {
return 0;
}
if((f = fdopen(fd, "r+")) == NULL) {
close(fd);
return 0;
}
#ifdef HAVE_FLOCK
if(flock(fd, LOCK_EX | LOCK_NB) == -1) {
fclose(f);
return 0;
}
#endif
pid = getpid();
if(!fprintf(f, "%ld\n", (long)pid)) {
fclose(f);
return 0;
}
fflush(f);
#ifdef HAVE_FLOCK
if(flock(fd, LOCK_UN) == -1) {
fclose(f);
return 0;
}
#endif
fclose(f);
return pid;
}
/* remove_pid
*
* Remove the the specified file. The result from unlink(2)
* is returned
*/
int remove_pid(const char *pidfile) {
return unlink(pidfile);
}
#endif
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