lib/libutil/pidfile.c

   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 }