1 /* $NetBSD: pidfile.c,v 1.11 2015/01/22 19:04:28 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 32 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 __RCSID("$NetBSD: pidfile.c,v 1.11 2015/01/22 19:04:28 christos Exp $"); 35 #endif 36 37 #include <sys/param.h> 38 39 #include <paths.h> 40 #include <stdbool.h> 41 #include <stdlib.h> 42 #include <stdio.h> 43 #include <string.h> 44 #include <unistd.h> 45 #include <util.h> 46 47 static pid_t pidfile_pid; 48 static char *pidfile_path; 49 50 /* Deletes an existent pidfile iff it was created by this process. */ 51 static void 52 pidfile_cleanup(void) 53 { 54 55 if ((pidfile_path != NULL) && (pidfile_pid == getpid())) 56 (void) unlink(pidfile_path); 57 } 58 59 /* Registers an atexit(3) handler to delete the pidfile we have generated. 60 * We only register the handler when we create a pidfile, so we can assume 61 * that the pidfile exists. 62 * 63 * Returns 0 on success or -1 if the handler could not be registered. */ 64 static int 65 register_atexit_handler(void) 66 { 67 static bool done = false; 68 69 if (!done) { 70 if (atexit(pidfile_cleanup) < 0) 71 return -1; 72 done = true; 73 } 74 75 return 0; 76 } 77 78 /* Given a new pidfile name in 'path', deletes any previously-created pidfile 79 * if the previous file differs to the new one. 80 * 81 * If a previous file is deleted, returns 1, which means that a new pidfile 82 * must be created. Otherwise, this returns 0, which means that the existing 83 * file does not need to be touched. */ 84 static int 85 cleanup_old_pidfile(const char* path) 86 { 87 if (pidfile_path != NULL) { 88 if (strcmp(pidfile_path, path) != 0) { 89 pidfile_cleanup(); 90 91 free(pidfile_path); 92 pidfile_path = NULL; 93 94 return 1; 95 } else 96 return 0; 97 } else 98 return 1; 99 } 100 101 /* Constructs a name for a pidfile in the default location (/var/run). If 102 * 'bname' is NULL, uses the name of the current program for the name of 103 * the pidfile. 104 * 105 * Returns a pointer to a dynamically-allocatd string containing the absolute 106 * path to the pidfile; NULL on failure. */ 107 static char * 108 generate_varrun_path(const char *bname) 109 { 110 char *path; 111 112 if (bname == NULL) 113 bname = getprogname(); 114 115 /* _PATH_VARRUN includes trailing / */ 116 if (asprintf(&path, "%s%s.pid", _PATH_VARRUN, bname) == -1) 117 return NULL; 118 return path; 119 } 120 121 /* Creates a pidfile with the provided name. The new pidfile is "registered" 122 * in the global variables pidfile_path and pidfile_pid so that any further 123 * call to pidfile(3) can check if we are recreating the same file or a new 124 * one. 125 * 126 * Returns 0 on success or -1 if there is any error. */ 127 static int 128 create_pidfile(const char* path) 129 { 130 FILE *f; 131 132 if (register_atexit_handler() == -1) 133 return -1; 134 135 if (cleanup_old_pidfile(path) == 0) 136 return 0; 137 138 pidfile_path = strdup(path); 139 if (pidfile_path == NULL) 140 return -1; 141 142 if ((f = fopen(path, "w")) == NULL) { 143 free(pidfile_path); 144 pidfile_path = NULL; 145 return -1; 146 } 147 148 pidfile_pid = getpid(); 149 150 (void) fprintf(f, "%d\n", pidfile_pid); 151 (void) fclose(f); 152 153 return 0; 154 } 155 156 int 157 pidfile(const char *path) 158 { 159 160 if (path == NULL || strchr(path, '/') == NULL) { 161 char *default_path; 162 163 if ((default_path = generate_varrun_path(path)) == NULL) 164 return -1; 165 166 if (create_pidfile(default_path) == -1) { 167 free(default_path); 168 return -1; 169 } 170 171 free(default_path); 172 return 0; 173 } else 174 return create_pidfile(path); 175 } 176