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pidfile.c revision 1.6 
      1 /*	$NetBSD: pidfile.c,v 1.6 2001/10/20 09:20:28 taca 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  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *        This product includes software developed by the NetBSD
     21  *        Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #if defined(LIBC_SCCS) && !defined(lint)
     41 __RCSID("$NetBSD: pidfile.c,v 1.6 2001/10/20 09:20:28 taca Exp $");
     42 #endif
     43 
     44 #include <sys/param.h>
     45 #include <paths.h>
     46 #include <stdlib.h>
     47 #include <stdio.h>
     48 #include <string.h>
     49 #include <unistd.h>
     50 #include <util.h>
     51 
     52 static int   pidfile_atexit_done;
     53 static pid_t pidfile_pid;
     54 static char *pidfile_basename;
     55 static char *pidfile_path;
     56 
     57 static void pidfile_cleanup(void);
     58 
     59 void
     60 pidfile(const char *basename)
     61 {
     62 	FILE *f;
     63 
     64 	/*
     65 	 * Register handler which will remove the pidfile later.
     66 	 */
     67 	if (!pidfile_atexit_done) {
     68 		if (atexit(pidfile_cleanup) < 0)
     69 			return;
     70 		pidfile_atexit_done = 1;
     71 	}
     72 
     73 	if (basename == NULL)
     74 		basename = getprogname();
     75 
     76 	/*
     77 	 * If pidfile has already been created for the supplied basename
     78 	 * we don't need to create a pidfile again.
     79 	 */
     80 	if (pidfile_path != NULL) {
     81 		if (strcmp(pidfile_basename, basename) == 0)
     82 			return;
     83 		/*
     84 		 * Remove existing pidfile if it was created by this process.
     85 		 */
     86 		pidfile_cleanup();
     87 
     88 		free(pidfile_path);
     89 		pidfile_path = NULL;
     90 		free(pidfile_basename);
     91 		pidfile_basename = NULL;
     92 	}
     93 
     94 	pidfile_pid = getpid();
     95 
     96 	pidfile_basename = strdup(basename);
     97 	if (pidfile_basename == NULL)
     98 		return;
     99 
    100 	/* _PATH_VARRUN includes trailing / */
    101 	(void) asprintf(&pidfile_path, "%s%s.pid", _PATH_VARRUN, basename);
    102 	if (pidfile_path == NULL) {
    103 		free(pidfile_basename);
    104 		pidfile_basename = NULL;
    105 		return;
    106 	}
    107 
    108 	if ((f = fopen(pidfile_path, "w")) == NULL) {
    109 		free(pidfile_path);
    110 		pidfile_path = NULL;
    111 		free(pidfile_basename);
    112 		pidfile_basename = NULL;
    113 		return;
    114 	}
    115 
    116 	(void) fprintf(f, "%d\n", pidfile_pid);
    117 	(void) fclose(f);
    118 }
    119 
    120 static void
    121 pidfile_cleanup(void)
    122 {
    123 	/* Only remove the pidfile if it was created by this process. */
    124 	if ((pidfile_path != NULL) && (pidfile_pid == getpid()))
    125 		(void) unlink(pidfile_path);
    126 }
    127