1 /* $NetBSD: pidfile.c,v 1.2 2016/04/05 12:28:57 christos Exp $ */
4 * Copyright (c) 1999 The NetBSD Foundation, Inc.
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe, Matthias Scheler and Julio Merino.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
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.
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.
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 $");
40 #include <sys/param.h>
55 static pid_t pidfile_pid;
56 static char *pidfile_path;
58 /* Deletes an existent pidfile iff it was created by this process. */
63 if ((pidfile_path != NULL) && (pidfile_pid == getpid()))
64 (void) unlink(pidfile_path);
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.
71 * Returns 0 on success or -1 if the handler could not be registered. */
73 register_atexit_handler(void)
75 static bool done = false;
78 if (atexit(pidfile_cleanup) < 0)
86 /* Given a new pidfile name in 'path', deletes any previously-created pidfile
87 * if the previous file differs to the new one.
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. */
93 cleanup_old_pidfile(const char* path)
95 if (pidfile_path != NULL) {
96 if (strcmp(pidfile_path, path) != 0) {
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
113 * Returns a pointer to a dynamically-allocatd string containing the absolute
114 * path to the pidfile; NULL on failure. */
116 generate_varrun_path(const char *bname)
121 bname = getprogname();
123 /* _PATH_VARRUN includes trailing / */
124 if (asprintf(&path, "%s%s.pid", _PATH_VARRUN, bname) == -1)
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
134 * Returns 0 on success or -1 if there is any error. */
136 create_pidfile(const char* path)
140 if (register_atexit_handler() == -1)
143 if (cleanup_old_pidfile(path) == 0)
146 pidfile_path = strdup(path);
147 if (pidfile_path == NULL)
150 if ((f = fopen(path, "w")) == NULL) {
156 pidfile_pid = getpid();
158 (void) fprintf(f, "%d\n", pidfile_pid);
165 pidfile(const char *path)
168 if (path == NULL || strchr(path, '/') == NULL) {
171 if ((default_path = generate_varrun_path(path)) == NULL)
174 if (create_pidfile(default_path) == -1) {
182 return create_pidfile(path);