xref: /netbsd/lib/libutil/pidfile.c (revision 6550d01e)
1 /*	$NetBSD: pidfile.c,v 1.8 2008/04/28 20:23:03 martin Exp $	*/
2 
3 /*-
4  * Copyright (c) 1999 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Jason R. Thorpe and Matthias Scheler.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 __RCSID("$NetBSD: pidfile.c,v 1.8 2008/04/28 20:23:03 martin Exp $");
35 #endif
36 
37 #include <sys/param.h>
38 #include <paths.h>
39 #include <stdlib.h>
40 #include <stdio.h>
41 #include <string.h>
42 #include <unistd.h>
43 #include <util.h>
44 
45 static int   pidfile_atexit_done;
46 static pid_t pidfile_pid;
47 static char *pidfile_basename;
48 static char *pidfile_path;
49 
50 static void pidfile_cleanup(void);
51 
52 int
53 pidfile(const char *basename)
54 {
55 	FILE *f;
56 
57 	/*
58 	 * Register handler which will remove the pidfile later.
59 	 */
60 	if (!pidfile_atexit_done) {
61 		if (atexit(pidfile_cleanup) < 0)
62 			return -1;
63 		pidfile_atexit_done = 1;
64 	}
65 
66 	if (basename == NULL)
67 		basename = getprogname();
68 
69 	/*
70 	 * If pidfile has already been created for the supplied basename
71 	 * we don't need to create a pidfile again.
72 	 */
73 	if (pidfile_path != NULL) {
74 		if (strcmp(pidfile_basename, basename) == 0)
75 			return 0;
76 		/*
77 		 * Remove existing pidfile if it was created by this process.
78 		 */
79 		pidfile_cleanup();
80 
81 		free(pidfile_path);
82 		pidfile_path = NULL;
83 		free(pidfile_basename);
84 		pidfile_basename = NULL;
85 	}
86 
87 	pidfile_pid = getpid();
88 
89 	pidfile_basename = strdup(basename);
90 	if (pidfile_basename == NULL)
91 		return -1;
92 
93 	/* _PATH_VARRUN includes trailing / */
94 	(void) asprintf(&pidfile_path, "%s%s.pid", _PATH_VARRUN, basename);
95 	if (pidfile_path == NULL) {
96 		free(pidfile_basename);
97 		pidfile_basename = NULL;
98 		return -1;
99 	}
100 
101 	if ((f = fopen(pidfile_path, "w")) == NULL) {
102 		free(pidfile_path);
103 		pidfile_path = NULL;
104 		free(pidfile_basename);
105 		pidfile_basename = NULL;
106 		return -1;
107 	}
108 
109 	(void) fprintf(f, "%d\n", pidfile_pid);
110 	(void) fclose(f);
111 	return 0;
112 }
113 
114 static void
115 pidfile_cleanup(void)
116 {
117 	/* Only remove the pidfile if it was created by this process. */
118 	if ((pidfile_path != NULL) && (pidfile_pid == getpid()))
119 		(void) unlink(pidfile_path);
120 }
121