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pidfile.c revision 1.8.8.2 
      1 /*	$NetBSD: pidfile.c,v 1.8.8.2 2008/04/28 20:23:04 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 1.8.8.2 2008/04/28 20:23:04 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