external/bsd/blacklist/port/pidfile.c

   1 /*      $NetBSD: pidfile.c,v 1.1 2015/01/22 16:19:53 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 1.1 2015/01/22 16:19:53 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_UTIL_H
  49 #include <util.h>
  50 #endif
  51
  52 static pid_t pidfile_pid;
  53 static char *pidfile_path;
  54
  55 /* Deletes an existent pidfile iff it was created by this process. */
  56 static void
  57 pidfile_cleanup(void)
  58 {
  59
  60         if ((pidfile_path != NULL) && (pidfile_pid == getpid()))
  61                 (void) unlink(pidfile_path);
  62 }
  63
  64 /* Registers an atexit(3) handler to delete the pidfile we have generated.
  65  * We only register the handler when we create a pidfile, so we can assume
  66  * that the pidfile exists.
  67  *
  68  * Returns 0 on success or -1 if the handler could not be registered. */
  69 static int
  70 register_atexit_handler(void)
  71 {
  72         static bool done = false;
  73
  74         if (!done) {
  75                 if (atexit(pidfile_cleanup) < 0)
  76                         return -1;
  77                 done = true;
  78         }
  79
  80         return 0;
  81 }
  82
  83 /* Given a new pidfile name in 'path', deletes any previously-created pidfile
  84  * if the previous file differs to the new one.
  85  *
  86  * If a previous file is deleted, returns 1, which means that a new pidfile
  87  * must be created.  Otherwise, this returns 0, which means that the existing
  88  * file does not need to be touched. */
  89 static int
  90 cleanup_old_pidfile(const char* path)
  91 {
  92         if (pidfile_path != NULL) {
  93                 if (strcmp(pidfile_path, path) != 0) {
  94                         pidfile_cleanup();
  95
  96                         free(pidfile_path);
  97                         pidfile_path = NULL;
  98
  99                         return 1;
 100                 } else
 101                         return 0;
 102         } else
 103                 return 1;
 104 }
 105
 106 /* Constructs a name for a pidfile in the default location (/var/run).  If
 107  * 'basename' is NULL, uses the name of the current program for the name of
 108  * the pidfile.
 109  *
 110  * Returns a pointer to a dynamically-allocatd string containing the absolute
 111  * path to the pidfile; NULL on failure. */
 112 static char *
 113 generate_varrun_path(const char *bname)
 114 {
 115         char *path;
 116
 117         if (bname == NULL)
 118                 bname = getprogname();
 119
 120         /* _PATH_VARRUN includes trailing / */
 121         if (asprintf(&path, "%s%s.pid", _PATH_VARRUN, bname) == -1)
 122                 return NULL;
 123         return path;
 124 }
 125
 126 /* Creates a pidfile with the provided name.  The new pidfile is "registered"
 127  * in the global variables pidfile_path and pidfile_pid so that any further
 128  * call to pidfile(3) can check if we are recreating the same file or a new
 129  * one.
 130  *
 131  * Returns 0 on success or -1 if there is any error. */
 132 static int
 133 create_pidfile(const char* path)
 134 {
 135         FILE *f;
 136
 137         if (register_atexit_handler() == -1)
 138                 return -1;
 139
 140         if (cleanup_old_pidfile(path) == 0)
 141                 return 0;
 142
 143         pidfile_path = strdup(path);
 144         if (pidfile_path == NULL)
 145                 return -1;
 146
 147         if ((f = fopen(path, "w")) == NULL) {
 148                 free(pidfile_path);
 149                 pidfile_path = NULL;
 150                 return -1;
 151         }
 152
 153         pidfile_pid = getpid();
 154
 155         (void) fprintf(f, "%d\n", pidfile_pid);
 156         (void) fclose(f);
 157
 158         return 0;
 159 }
 160
 161 int
 162 pidfile(const char *path)
 163 {
 164
 165         if (path == NULL || strchr(path, '/') == NULL) {
 166                 char *default_path;
 167
 168                 if ((default_path = generate_varrun_path(path)) == NULL)
 169                         return -1;
 170
 171                 if (create_pidfile(default_path) == -1) {
 172                         free(default_path);
 173                         return -1;
 174                 }
 175
 176                 free(default_path);
 177                 return 0;
 178         } else
 179                 return create_pidfile(path);
 180 }