usr/src/cmd/fs.d/nfs/lib/daemon.c

   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 }