gvpe/lib/pidfile.c

/*
    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., 59 Temple Place - Suite 330, Boston, MA 02111, USA
*/

/*
 * Sat Aug 19 13:24:33 MET DST 1995: Martin Schulze
 *      First version (v0.2) released
 */

#include <stdio.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#include <sys/types.h>
#include <signal.h>
#include <fcntl.h>

/* 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.
 */
int read_pid (char *pidfile)
{
  FILE *f;
  int pid;

  if (!(f=fopen(pidfile,"r")))
    return 0;
  fscanf(f,"%d", &pid);
  fclose(f);
  return 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 1 is returned, otherwise 0.
 */
int check_pid (char *pidfile)
{
  int 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.
 */
int write_pid (char *pidfile)
{
  FILE *f;
  int fd;
  int pid;

  if ( ((fd = open(pidfile, O_RDWR|O_CREAT, 0644)) == -1)
       || ((f = fdopen(fd, "r+")) == NULL) ) {
      fprintf(stderr, "Can't open or create %s.\n", pidfile);
      return 0;
  }
  
#ifdef HAVE_FLOCK
  if (flock(fd, LOCK_EX|LOCK_NB) == -1) {
      fscanf(f, "%d", &pid);
      fclose(f);
      printf("Can't lock, lock is held by pid %d.\n", pid);
      return 0;
  }
#endif

  pid = getpid();
  if (!fprintf(f,"%d\n", pid)) {
      printf("Can't write pid , %s.\n", strerror(errno));
      close(fd);
      return 0;
  }
  fflush(f);

#ifdef HAVE_FLOCK
  if (flock(fd, LOCK_UN) == -1) {
      printf("Can't unlock pidfile %s, %s.\n", pidfile, strerror(errno));
      close(fd);
      return 0;
  }
#endif
  close(fd);

  return pid;
}

/* remove_pid
 *
 * Remove the the specified file. The result from unlink(2)
 * is returned
 */
int remove_pid (char *pidfile)
{
  return unlink (pidfile);
}
  
Revision:	1.1
Committed:	Sat Mar 1 15:53:02 2003 UTC (21 years, 2 months ago) by pcg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	poll-based-iom, VPE_0_9, VPE_1_2, VPE_1_4, VPE_1_0
Log Message:	* empty log message *
#	User	Rev	Content
1	pcg	1.1	/*
2			pidfile.c - interact with pidfiles
3			Copyright (c) 1995 Martin Schulze <Martin.Schulze@Linux.DE>
4
5			This file is part of the sysklogd package, a kernel and system log daemon.
6
7			This program is free software; you can redistribute it and/or modify
8			it under the terms of the GNU General Public License as published by
9			the Free Software Foundation; either version 2 of the License, or
10			(at your option) any later version.
11
12			This program is distributed in the hope that it will be useful,
13			but WITHOUT ANY WARRANTY; without even the implied warranty of
14			MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15			GNU General Public License for more details.
16
17			You should have received a copy of the GNU General Public License
18			along with this program; if not, write to the Free Software
19			Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA
20			*/
21
22			/*
23			* Sat Aug 19 13:24:33 MET DST 1995: Martin Schulze
24			* First version (v0.2) released
25			*/
26
27			#include <stdio.h>
28			#include <unistd.h>
29			#include <sys/stat.h>
30			#include <sys/file.h>
31			#include <string.h>
32			#include <errno.h>
33			#include <signal.h>
34			#include <sys/types.h>
35			#include <signal.h>
36			#include <fcntl.h>
37
38			/* read_pid
39			*
40			* Reads the specified pidfile and returns the read pid.
41			* 0 is returned if either there's no pidfile, it's empty
42			* or no pid can be read.
43			*/
44			int read_pid (char *pidfile)
45			{
46			FILE *f;
47			int pid;
48
49			if (!(f=fopen(pidfile,"r")))
50			return 0;
51			fscanf(f,"%d", &pid);
52			fclose(f);
53			return pid;
54			}
55
56			/* check_pid
57			*
58			* Reads the pid using read_pid and looks up the pid in the process
59			* table (using /proc) to determine if the process already exists. If
60			* so 1 is returned, otherwise 0.
61			*/
62			int check_pid (char *pidfile)
63			{
64			int pid = read_pid(pidfile);
65
66			/* Amazing ! _I_ am already holding the pid file... */
67			if ((!pid) \|\| (pid == getpid ()))
68			return 0;
69
70			/*
71			* The 'standard' method of doing this is to try and do a 'fake' kill
72			* of the process. If an ESRCH error is returned the process cannot
73			* be found -- GW
74			*/
75			/* But... errno is usually changed only on error.. */
76			errno = 0;
77			if (kill(pid, 0) && errno == ESRCH)
78			return(0);
79
80			return pid;
81			}
82
83			/* write_pid
84			*
85			* Writes the pid to the specified file. If that fails 0 is
86			* returned, otherwise the pid.
87			*/
88			int write_pid (char *pidfile)
89			{
90			FILE *f;
91			int fd;
92			int pid;
93
94			if ( ((fd = open(pidfile, O_RDWR\|O_CREAT, 0644)) == -1)
95			\|\| ((f = fdopen(fd, "r+")) == NULL) ) {
96			fprintf(stderr, "Can't open or create %s.\n", pidfile);
97			return 0;
98			}
99
100			#ifdef HAVE_FLOCK
101			if (flock(fd, LOCK_EX\|LOCK_NB) == -1) {
102			fscanf(f, "%d", &pid);
103			fclose(f);
104			printf("Can't lock, lock is held by pid %d.\n", pid);
105			return 0;
106			}
107			#endif
108
109			pid = getpid();
110			if (!fprintf(f,"%d\n", pid)) {
111			printf("Can't write pid , %s.\n", strerror(errno));
112			close(fd);
113			return 0;
114			}
115			fflush(f);
116
117			#ifdef HAVE_FLOCK
118			if (flock(fd, LOCK_UN) == -1) {
119			printf("Can't unlock pidfile %s, %s.\n", pidfile, strerror(errno));
120			close(fd);
121			return 0;
122			}
123			#endif
124			close(fd);
125
126			return pid;
127			}
128
129			/* remove_pid
130			*
131			* Remove the the specified file. The result from unlink(2)
132			* is returned
133			*/
134			int remove_pid (char *pidfile)
135			{
136			return unlink (pidfile);
137			}
138