usr.sbin/daemon/daemon.c

   1 /*-
   2  * Copyright (c) 1999 Berkeley Software Design, Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  * 3. Berkeley Software Design Inc's name may not be used to endorse or
  13  *    promote products derived from this software without specific prior
  14  *    written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  *      From BSDI: daemon.c,v 1.2 1996/08/15 01:11:09 jch Exp
  29  */
  30
  31 #include <sys/cdefs.h>
  32 __FBSDID("$FreeBSD$");
  33
  34 #include <sys/param.h>
  35
  36 #include <err.h>
  37 #include <errno.h>
  38 #include <pwd.h>
  39 #include <libutil.h>
  40 #include <login_cap.h>
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <unistd.h>
  44
  45 static void restrict_process(const char *);
  46 static void usage(void);
  47
  48 int
  49 main(int argc, char *argv[])
  50 {
  51         struct pidfh *pfh = NULL;
  52         int ch, nochdir, noclose, errcode;
  53         const char *pidfile, *user;
  54         pid_t otherpid;
  55
  56         nochdir = noclose = 1;
  57         pidfile = user = NULL;
  58         while ((ch = getopt(argc, argv, "-cfp:u:")) != -1) {
  59                 switch (ch) {
  60                 case 'c':
  61                         nochdir = 0;
  62                         break;
  63                 case 'f':
  64                         noclose = 0;
  65                         break;
  66                 case 'p':
  67                         pidfile = optarg;
  68                         break;
  69                 case 'u':
  70                         user = optarg;
  71                         break;
  72                 default:
  73                         usage();
  74                 }
  75         }
  76         argc -= optind;
  77         argv += optind;
  78
  79         if (argc == 0)
  80                 usage();
  81
  82         if (user != NULL)
  83                 restrict_process(user);
  84
  85         /*
  86          * Try to open the pidfile before calling daemon(3),
  87          * to be able to report the error intelligently
  88          */
  89         if (pidfile) {
  90                 pfh = pidfile_open(pidfile, 0600, &otherpid);
  91                 if (pfh == NULL) {
  92                         if (errno == EEXIST) {
  93                                 errx(3, "process already running, pid: %d",
  94                                     otherpid);
  95                         }
  96                         err(2, "pidfile ``%s''", pidfile);
  97                 }
  98         }
  99
 100         if (daemon(nochdir, noclose) == -1)
 101                 err(1, NULL);
 102
 103         /* Now that we are the child, write out the pid */
 104         if (pidfile)
 105                 pidfile_write(pfh);
 106
 107         execvp(argv[0], argv);
 108
 109         /*
 110          * execvp() failed -- unlink pidfile if any, and
 111          * report the error
 112          */
 113         errcode = errno; /* Preserve errcode -- unlink may reset it */
 114         if (pidfile)
 115                 pidfile_remove(pfh);
 116
 117         /* The child is now running, so the exit status doesn't matter. */
 118         errc(1, errcode, "%s", argv[0]);
 119 }
 120
 121 static void
 122 restrict_process(const char *user)
 123 {
 124         struct passwd *pw = NULL;
 125
 126         pw = getpwnam(user);
 127         if (pw == NULL)
 128                 errx(1, "unknown user: %s", user);
 129
 130         if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0)
 131                 errx(1, "failed to set user environment");
 132 }
 133
 134 static void
 135 usage(void)
 136 {
 137         (void)fprintf(stderr,
 138             "usage: daemon [-cf] [-p pidfile] [-u user] command "
 139                 "arguments ...\n");
 140         exit(1);
 141 }