1 /* $NetBSD: pidfile.c,v 1.2 2016/04/05 12:28:57 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 1.2 2016/04/05 12:28:57 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_LIBUTIL_H 49 #include <libutil.h> 50 #endif 51 #ifdef HAVE_UTIL_H 52 #include <util.h> 53 #endif 54 55 static pid_t pidfile_pid; 56 static char *pidfile_path; 57 58 /* Deletes an existent pidfile iff it was created by this process. */ 59 static void 60 pidfile_cleanup(void) 61 { 62 63 if ((pidfile_path != NULL) && (pidfile_pid == getpid())) 64 (void) unlink(pidfile_path); 65 } 66 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. 70 * 71 * Returns 0 on success or -1 if the handler could not be registered. */ 72 static int 73 register_atexit_handler(void) 74 { 75 static bool done = false; 76 77 if (!done) { 78 if (atexit(pidfile_cleanup) < 0) 79 return -1; 80 done = true; 81 } 82 83 return 0; 84 } 85 86 /* Given a new pidfile name in 'path', deletes any previously-created pidfile 87 * if the previous file differs to the new one. 88 * 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. */ 92 static int 93 cleanup_old_pidfile(const char* path) 94 { 95 if (pidfile_path != NULL) { 96 if (strcmp(pidfile_path, path) != 0) { 97 pidfile_cleanup(); 98 99 free(pidfile_path); 100 pidfile_path = NULL; 101 102 return 1; 103 } else 104 return 0; 105 } else 106 return 1; 107 } 108 109 /* 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 111 * the pidfile. 112 * 113 * Returns a pointer to a dynamically-allocatd string containing the absolute 114 * path to the pidfile; NULL on failure. */ 115 static char * 116 generate_varrun_path(const char *bname) 117 { 118 char *path; 119 120 if (bname == NULL) 121 bname = getprogname(); 122 123 /* _PATH_VARRUN includes trailing / */ 124 if (asprintf(&path, "%s%s.pid", _PATH_VARRUN, bname) == -1) 125 return NULL; 126 return path; 127 } 128 129 /* 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 132 * one. 133 * 134 * Returns 0 on success or -1 if there is any error. */ 135 static int 136 create_pidfile(const char* path) 137 { 138 FILE *f; 139 140 if (register_atexit_handler() == -1) 141 return -1; 142 143 if (cleanup_old_pidfile(path) == 0) 144 return 0; 145 146 pidfile_path = strdup(path); 147 if (pidfile_path == NULL) 148 return -1; 149 150 if ((f = fopen(path, "w")) == NULL) { 151 free(pidfile_path); 152 pidfile_path = NULL; 153 return -1; 154 } 155 156 pidfile_pid = getpid(); 157 158 (void) fprintf(f, "%d\n", pidfile_pid); 159 (void) fclose(f); 160 161 return 0; 162 } 163 164 int 165 pidfile(const char *path) 166 { 167 168 if (path == NULL || strchr(path, '/') == NULL) { 169 char *default_path; 170 171 if ((default_path = generate_varrun_path(path)) == NULL) 172 return -1; 173 174 if (create_pidfile(default_path) == -1) { 175 free(default_path); 176 return -1; 177 } 178 179 free(default_path); 180 return 0; 181 } else 182 return create_pidfile(path); 183 } 184