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 file is part of GVPE.

    GVPE 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 gvpe; 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 ? pidfile : "(null)");
      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:	1.3
Committed:	Thu Mar 3 16:54:34 2005 UTC (19 years, 2 months ago) by pcg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rel-1_9, rel-1_8, rel-2_01, rel-3_0, rel-2_2, rel-2_0, rel-2_21, rel-2_22, rel-2_25, HEAD
Changes since 1.2:	+4 -2 lines
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	pcg	1.3	This file is part of GVPE.
8
9			GVPE is free software; you can redistribute it and/or modify
10	pcg	1.1	it under the terms of the GNU General Public License as published by
11			the Free Software Foundation; either version 2 of the License, or
12			(at your option) any later version.
13
14			This program is distributed in the hope that it will be useful,
15			but WITHOUT ANY WARRANTY; without even the implied warranty of
16			MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17			GNU General Public License for more details.
18
19			You should have received a copy of the GNU General Public License
20	pcg	1.3	along with gvpe; if not, write to the Free Software
21	pcg	1.1	Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA
22			*/
23
24			/*
25			* Sat Aug 19 13:24:33 MET DST 1995: Martin Schulze
26			* First version (v0.2) released
27			*/
28
29			#include <stdio.h>
30			#include <unistd.h>
31			#include <sys/stat.h>
32			#include <sys/file.h>
33			#include <string.h>
34			#include <errno.h>
35			#include <signal.h>
36			#include <sys/types.h>
37			#include <signal.h>
38			#include <fcntl.h>
39
40			/* read_pid
41			*
42			* Reads the specified pidfile and returns the read pid.
43			* 0 is returned if either there's no pidfile, it's empty
44			* or no pid can be read.
45			*/
46			int read_pid (char *pidfile)
47			{
48			FILE *f;
49			int pid;
50
51			if (!(f=fopen(pidfile,"r")))
52			return 0;
53			fscanf(f,"%d", &pid);
54			fclose(f);
55			return pid;
56			}
57
58			/* check_pid
59			*
60			* Reads the pid using read_pid and looks up the pid in the process
61			* table (using /proc) to determine if the process already exists. If
62			* so 1 is returned, otherwise 0.
63			*/
64			int check_pid (char *pidfile)
65			{
66			int pid = read_pid(pidfile);
67
68			/* Amazing ! _I_ am already holding the pid file... */
69			if ((!pid) \|\| (pid == getpid ()))
70			return 0;
71
72			/*
73			* The 'standard' method of doing this is to try and do a 'fake' kill
74			* of the process. If an ESRCH error is returned the process cannot
75			* be found -- GW
76			*/
77			/* But... errno is usually changed only on error.. */
78			errno = 0;
79			if (kill(pid, 0) && errno == ESRCH)
80			return(0);
81
82			return pid;
83			}
84
85			/* write_pid
86			*
87			* Writes the pid to the specified file. If that fails 0 is
88			* returned, otherwise the pid.
89			*/
90			int write_pid (char *pidfile)
91			{
92			FILE *f;
93			int fd;
94			int pid;
95
96			if ( ((fd = open(pidfile, O_RDWR\|O_CREAT, 0644)) == -1)
97			\|\| ((f = fdopen(fd, "r+")) == NULL) ) {
98	pcg	1.2	fprintf(stderr, "Can't open or create %s.\n", pidfile ? pidfile : "(null)");
99	pcg	1.1	return 0;
100			}
101
102			#ifdef HAVE_FLOCK
103			if (flock(fd, LOCK_EX\|LOCK_NB) == -1) {
104			fscanf(f, "%d", &pid);
105			fclose(f);
106			printf("Can't lock, lock is held by pid %d.\n", pid);
107			return 0;
108			}
109			#endif
110
111			pid = getpid();
112			if (!fprintf(f,"%d\n", pid)) {
113			printf("Can't write pid , %s.\n", strerror(errno));
114			close(fd);
115			return 0;
116			}
117			fflush(f);
118
119			#ifdef HAVE_FLOCK
120			if (flock(fd, LOCK_UN) == -1) {
121			printf("Can't unlock pidfile %s, %s.\n", pidfile, strerror(errno));
122			close(fd);
123			return 0;
124			}
125			#endif
126			close(fd);
127
128			return pid;
129			}
130
131			/* remove_pid
132			*
133			* Remove the the specified file. The result from unlink(2)
134			* is returned
135			*/
136			int remove_pid (char *pidfile)
137			{
138			return unlink (pidfile);
139			}
140