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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 /*
     22  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
     23  * Use is subject to license terms.
     24  */
     25 
     26 /* LINTLIBRARY */
     27 /* PROTOLIB1 */
     28 
     29 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     30 
     31 /* NFS server */
     32 
     33 #include <sys/param.h>
     34 #include <sys/types.h>
     35 #include <errno.h>
     36 #include <stdio.h>
     37 #include <stdio_ext.h>
     38 #include <stdlib.h>
     39 #include <signal.h>
     40 #include <unistd.h>
     41 #include <sys/wait.h>
     42 #include <sys/stat.h>
     43 #include <fcntl.h>
     44 #include <libscf.h>
     45 
     46 /*
     47  * The parent never returns from this function. It sits
     48  * and waits for the child to send status on whether it
     49  * loaded or not.
     50  *
     51  * We do not close down the standard file descriptors until
     52  * we know the child is going to run.
     53  */
     54 int
     55 daemonize_init(void)
     56 {
     57 	int status, pfds[2];
     58 	sigset_t set, oset;
     59 	pid_t pid;
     60 
     61 	/*
     62 	 * Block all signals prior to the fork and leave them blocked in the
     63 	 * parent so we don't get in a situation where the parent gets SIGINT
     64 	 * and returns non-zero exit status and the child is actually running.
     65 	 * In the child, restore the signal mask once we've done our setsid().
     66 	 */
     67 	(void) sigfillset(&set);
     68 	(void) sigdelset(&set, SIGABRT);
     69 	(void) sigprocmask(SIG_BLOCK, &set, &oset);
     70 
     71 	/*
     72 	 * We need to do this before we open the pipe - it makes things
     73 	 * easier in the long run.
     74 	 */
     75 	closefrom(STDERR_FILENO + 1);
     76 
     77 	if (pipe(pfds) == -1) {
     78 		fprintf(stderr, "failed to create pipe for daemonize");
     79 		exit(SMF_EXIT_ERR_FATAL);
     80 	}
     81 
     82 	if ((pid = fork()) == -1) {
     83 		fprintf(stderr, "failed to fork into background");
     84 		exit(SMF_EXIT_ERR_FATAL);
     85 	}
     86 
     87 	if (pid != 0) {
     88 		(void) close(pfds[1]);
     89 
     90 		if (read(pfds[0], &status, sizeof (status)) == sizeof (status))
     91 			exit(status);
     92 
     93 		if (waitpid(pid, &status, 0) == pid && WIFEXITED(status))
     94 			exit(WEXITSTATUS(status));
     95 
     96 		exit(SMF_EXIT_ERR_FATAL);
     97 	}
     98 
     99 	/*
    100 	 * All child from here on...
    101 	 */
    102 	(void) setsid();
    103 	(void) sigprocmask(SIG_SETMASK, &oset, NULL);
    104 	(void) close(pfds[0]);
    105 
    106 	return (pfds[1]);
    107 }
    108 
    109 /*
    110  * We are only a daemon if the file descriptor is valid.
    111  */
    112 void
    113 daemonize_fini(int fd)
    114 {
    115 	int	status = 0;
    116 
    117 	if (fd != -1) {
    118 		(void) write(fd, &status, sizeof (status));
    119 
    120 		(void) close(fd);
    121 
    122 		if ((fd = open("/dev/null", O_RDWR)) >= 0) {
    123 			(void) fcntl(fd, F_DUP2FD, STDIN_FILENO);
    124 			(void) fcntl(fd, F_DUP2FD, STDOUT_FILENO);
    125 			(void) fcntl(fd, F_DUP2FD, STDERR_FILENO);
    126 			(void) close(fd);
    127 		}
    128 	}
    129 }
    130