/* $NetBSD: pidfile.c,v 1.1.1.1 2020/06/15 01:52:54 christos Exp $ */ /*- * Copyright (c) 1999 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe, Matthias Scheler and Julio Merino. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #if defined(LIBC_SCCS) && !defined(lint) __RCSID("$NetBSD: pidfile.c,v 1.1.1.1 2020/06/15 01:52:54 christos Exp $"); #endif #include #include #include #include #include #include #include #ifdef HAVE_LIBUTIL_H #include #endif #ifdef HAVE_UTIL_H #include #endif static pid_t pidfile_pid; static char *pidfile_path; /* Deletes an existent pidfile iff it was created by this process. */ static void pidfile_cleanup(void) { if ((pidfile_path != NULL) && (pidfile_pid == getpid())) (void) unlink(pidfile_path); } /* Registers an atexit(3) handler to delete the pidfile we have generated. * We only register the handler when we create a pidfile, so we can assume * that the pidfile exists. * * Returns 0 on success or -1 if the handler could not be registered. */ static int register_atexit_handler(void) { static bool done = false; if (!done) { if (atexit(pidfile_cleanup) < 0) return -1; done = true; } return 0; } /* Given a new pidfile name in 'path', deletes any previously-created pidfile * if the previous file differs to the new one. * * If a previous file is deleted, returns 1, which means that a new pidfile * must be created. Otherwise, this returns 0, which means that the existing * file does not need to be touched. */ static int cleanup_old_pidfile(const char* path) { if (pidfile_path != NULL) { if (strcmp(pidfile_path, path) != 0) { pidfile_cleanup(); free(pidfile_path); pidfile_path = NULL; return 1; } else return 0; } else return 1; } /* Constructs a name for a pidfile in the default location (/var/run). If * 'basename' is NULL, uses the name of the current program for the name of * the pidfile. * * Returns a pointer to a dynamically-allocatd string containing the absolute * path to the pidfile; NULL on failure. */ static char * generate_varrun_path(const char *bname) { char *path; if (bname == NULL) bname = getprogname(); /* _PATH_VARRUN includes trailing / */ if (asprintf(&path, "%s%s.pid", _PATH_VARRUN, bname) == -1) return NULL; return path; } /* Creates a pidfile with the provided name. The new pidfile is "registered" * in the global variables pidfile_path and pidfile_pid so that any further * call to pidfile(3) can check if we are recreating the same file or a new * one. * * Returns 0 on success or -1 if there is any error. */ static int create_pidfile(const char* path) { FILE *f; if (register_atexit_handler() == -1) return -1; if (cleanup_old_pidfile(path) == 0) return 0; pidfile_path = strdup(path); if (pidfile_path == NULL) return -1; if ((f = fopen(path, "w")) == NULL) { free(pidfile_path); pidfile_path = NULL; return -1; } pidfile_pid = getpid(); (void) fprintf(f, "%d\n", pidfile_pid); (void) fclose(f); return 0; } int pidfile(const char *path) { if (path == NULL || strchr(path, '/') == NULL) { char *default_path; if ((default_path = generate_varrun_path(path)) == NULL) return -1; if (create_pidfile(default_path) == -1) { free(default_path); return -1; } free(default_path); return 0; } else return create_pidfile(path); }