1 /* $NetBSD: pidfile.c,v 1.2 2016/04/05 12:28:57 christos 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, Matthias Scheler and Julio Merino.
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 #ifdef HAVE_CONFIG_H
32 #include "config.h"
33 #endif
34
35 #include <sys/cdefs.h>
36 #if defined(LIBC_SCCS) && !defined(lint)
37 __RCSID("$NetBSD: pidfile.c,v 1.2 2016/04/05 12:28:57 christos Exp $");
38 #endif
39
40 #include <sys/param.h>
41
42 #include <paths.h>
43 #include <stdbool.h>
44 #include <stdlib.h>
45 #include <stdio.h>
46 #include <string.h>
47 #include <unistd.h>
48 #ifdef HAVE_LIBUTIL_H
49 #include <libutil.h>
50 #endif
51 #ifdef HAVE_UTIL_H
52 #include <util.h>
53 #endif
54
55 static pid_t pidfile_pid;
56 static char *pidfile_path;
57
58 /* Deletes an existent pidfile iff it was created by this process. */
59 static void
pidfile_cleanup(void)60 pidfile_cleanup(void)
61 {
62
63 if ((pidfile_path != NULL) && (pidfile_pid == getpid()))
64 (void) unlink(pidfile_path);
65 }
66
67 /* Registers an atexit(3) handler to delete the pidfile we have generated.
68 * We only register the handler when we create a pidfile, so we can assume
69 * that the pidfile exists.
70 *
71 * Returns 0 on success or -1 if the handler could not be registered. */
72 static int
register_atexit_handler(void)73 register_atexit_handler(void)
74 {
75 static bool done = false;
76
77 if (!done) {
78 if (atexit(pidfile_cleanup) < 0)
79 return -1;
80 done = true;
81 }
82
83 return 0;
84 }
85
86 /* Given a new pidfile name in 'path', deletes any previously-created pidfile
87 * if the previous file differs to the new one.
88 *
89 * If a previous file is deleted, returns 1, which means that a new pidfile
90 * must be created. Otherwise, this returns 0, which means that the existing
91 * file does not need to be touched. */
92 static int
cleanup_old_pidfile(const char * path)93 cleanup_old_pidfile(const char* path)
94 {
95 if (pidfile_path != NULL) {
96 if (strcmp(pidfile_path, path) != 0) {
97 pidfile_cleanup();
98
99 free(pidfile_path);
100 pidfile_path = NULL;
101
102 return 1;
103 } else
104 return 0;
105 } else
106 return 1;
107 }
108
109 /* Constructs a name for a pidfile in the default location (/var/run). If
110 * 'basename' is NULL, uses the name of the current program for the name of
111 * the pidfile.
112 *
113 * Returns a pointer to a dynamically-allocatd string containing the absolute
114 * path to the pidfile; NULL on failure. */
115 static char *
generate_varrun_path(const char * bname)116 generate_varrun_path(const char *bname)
117 {
118 char *path;
119
120 if (bname == NULL)
121 bname = getprogname();
122
123 /* _PATH_VARRUN includes trailing / */
124 if (asprintf(&path, "%s%s.pid", _PATH_VARRUN, bname) == -1)
125 return NULL;
126 return path;
127 }
128
129 /* Creates a pidfile with the provided name. The new pidfile is "registered"
130 * in the global variables pidfile_path and pidfile_pid so that any further
131 * call to pidfile(3) can check if we are recreating the same file or a new
132 * one.
133 *
134 * Returns 0 on success or -1 if there is any error. */
135 static int
create_pidfile(const char * path)136 create_pidfile(const char* path)
137 {
138 FILE *f;
139
140 if (register_atexit_handler() == -1)
141 return -1;
142
143 if (cleanup_old_pidfile(path) == 0)
144 return 0;
145
146 pidfile_path = strdup(path);
147 if (pidfile_path == NULL)
148 return -1;
149
150 if ((f = fopen(path, "w")) == NULL) {
151 free(pidfile_path);
152 pidfile_path = NULL;
153 return -1;
154 }
155
156 pidfile_pid = getpid();
157
158 (void) fprintf(f, "%d\n", pidfile_pid);
159 (void) fclose(f);
160
161 return 0;
162 }
163
164 int
pidfile(const char * path)165 pidfile(const char *path)
166 {
167
168 if (path == NULL || strchr(path, '/') == NULL) {
169 char *default_path;
170
171 if ((default_path = generate_varrun_path(path)) == NULL)
172 return -1;
173
174 if (create_pidfile(default_path) == -1) {
175 free(default_path);
176 return -1;
177 }
178
179 free(default_path);
180 return 0;
181 } else
182 return create_pidfile(path);
183 }
184