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eb807027af
to make sure only the minimum number of file handles is left open during a exec call. This is not a 100% solution, as there are also some fopen() calls and, more importantly, file descriptors opened by libraries. But it is better than nothing (and it was quick, at least until we run into platform hell, what we will for sure ;)).
157 lines
3.7 KiB
C
157 lines
3.7 KiB
C
/*
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pidfile.c - interact with pidfiles
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Copyright (c) 1995 Martin Schulze <Martin.Schulze@Linux.DE>
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* This file is part of rsyslog.
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*
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* Rsyslog 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 3 of the License, or
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* (at your option) any later version.
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*
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* Rsyslog 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 Rsyslog. If not, see <http://www.gnu.org/licenses/>.
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*
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* A copy of the GPL can be found in the file "COPYING" in this distribution.
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*/
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#include "config.h"
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#include "rsyslog.h"
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/*
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* Sat Aug 19 13:24:33 MET DST 1995: Martin Schulze
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* First version (v0.2) released
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/file.h>
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#include <string.h>
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#include <errno.h>
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#include <signal.h>
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#ifdef __sun
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#include <fcntl.h>
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#endif
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#include "srUtils.h"
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/* read_pid
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*
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* Reads the specified pidfile and returns the read pid.
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* 0 is returned if either there's no pidfile, it's empty
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* or no pid can be read.
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*/
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int read_pid (char *pidfile)
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{
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FILE *f;
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int pid;
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if (!(f=fopen(pidfile,"r")))
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return 0;
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fscanf(f,"%d", &pid);
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fclose(f);
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return pid;
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}
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/* check_pid
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*
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* Reads the pid using read_pid and looks up the pid in the process
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* table (using /proc) to determine if the process already exists. If
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* so 1 is returned, otherwise 0.
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*/
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int check_pid (char *pidfile)
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{
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int pid = read_pid(pidfile);
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/* Amazing ! _I_ am already holding the pid file... */
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if ((!pid) || (pid == getpid ()))
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return 0;
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/*
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* The 'standard' method of doing this is to try and do a 'fake' kill
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* of the process. If an ESRCH error is returned the process cannot
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* be found -- GW
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*/
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/* But... errno is usually changed only on error.. */
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if (kill(pid, 0) && errno == ESRCH)
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return(0);
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return pid;
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}
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/* write_pid
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*
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* Writes the pid to the specified file. If that fails 0 is
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* returned, otherwise the pid.
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*/
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int write_pid (char *pidfile)
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{
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FILE *f;
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int fd;
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int pid;
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if ( ((fd = open(pidfile, O_RDWR|O_CREAT|O_CLOEXEC, 0644)) == -1)
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|| ((f = fdopen(fd, "r+")) == NULL) ) {
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fprintf(stderr, "Can't open or create %s.\n", pidfile);
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return 0;
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}
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/* It seems to be acceptable that we do not lock the pid file
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* if we run under Solaris. In any case, it is highly unlikely
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* that two instances try to access this file. And flock is really
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* causing me grief on my initial steps on Solaris. Some time later,
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* we might re-enable it (or use some alternate method).
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* 2006-02-16 rgerhards
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*/
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#if HAVE_FLOCK
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if (flock(fd, LOCK_EX|LOCK_NB) == -1) {
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fscanf(f, "%d", &pid);
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fclose(f);
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printf("Can't lock, lock is held by pid %d.\n", pid);
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return 0;
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}
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#endif
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pid = getpid();
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if (!fprintf(f,"%d\n", pid)) {
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char errStr[1024];
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rs_strerror_r(errno, errStr, sizeof(errStr));
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printf("Can't write pid , %s.\n", errStr);
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close(fd);
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return 0;
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}
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fflush(f);
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#if HAVE_FLOCK
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if (flock(fd, LOCK_UN) == -1) {
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char errStr[1024];
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rs_strerror_r(errno, errStr, sizeof(errStr));
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printf("Can't unlock pidfile %s, %s.\n", pidfile, errStr);
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close(fd);
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return 0;
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}
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#endif
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close(fd);
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return pid;
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}
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/* remove_pid
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*
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* Remove the the specified file. The result from unlink(2)
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* is returned
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*/
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int remove_pid (char *pidfile)
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{
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return unlink (pidfile);
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}
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