libc/unistd/daemon.c

   1 /* daemon implementation for uClibc
   2  *
   3  * Copyright (c) 1990, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * 3. <BSD Advertising Clause omitted per the July 22, 1999 licensing change
  16  *              ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change>
  17  *
  18  * 4. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 /*
  36  * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
  37  *
  38  * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
  39  * Modified for uClibc by Erik Andersen <andersen@uclibc.org>
  40  */
  41
  42 #include <stdio.h>
  43 #include <features.h>
  44 #include <fcntl.h>
  45 #include <paths.h>
  46 #include <signal.h>
  47 #include <unistd.h>
  48 #include <not-cancel.h>
  49 #include <errno.h>
  50
  51 #ifdef __UCLIBC_HAS_THREADS_NATIVE__
  52 #include <sys/stat.h>
  53 #endif
  54
  55 #define STAT stat64
  56 #define FSTAT fstat64
  57
  58 #if defined __USE_BSD || (defined __USE_XOPEN && !defined __USE_UNIX98)
  59
  60 #ifndef __ARCH_USE_MMU__
  61 #include <sys/syscall.h>
  62 #include <sched.h>
  63 /* use clone() to get fork() like behavior here -- we just want to disassociate
  64  * from the controlling terminal
  65  */
  66 pid_t _fork_parent(void)
  67 {
  68         INTERNAL_SYSCALL_DECL(err);
  69         register long ret = INTERNAL_SYSCALL(clone, err, 2, CLONE_VM, 0);
  70         if (ret > 0)
  71                 /* parent needs to die now w/out touching stack */
  72                 INTERNAL_SYSCALL(exit, err, 1, 0);
  73         return ret;
  74 }
  75 static inline pid_t fork_parent(void)
  76 {
  77         /* Block all signals to keep the parent from using the stack */
  78         pid_t ret;
  79         sigset_t new_set, old_set;
  80         sigfillset(&new_set);
  81         sigprocmask(SIG_BLOCK, &new_set, &old_set);
  82         ret = _fork_parent();
  83         sigprocmask(SIG_SETMASK, &old_set, NULL);
  84         return ret;
  85 }
  86 #else
  87 static inline pid_t fork_parent(void)
  88 {
  89         switch (fork()) {
  90                 case -1: return -1;
  91                 case 0:  return 0;
  92                 default: _exit(0);
  93         }
  94 }
  95 #endif
  96
  97 int daemon(int nochdir, int noclose)
  98 {
  99         int fd;
 100
 101         if (fork_parent() == -1)
 102                 return -1;
 103
 104         if (setsid() == -1)
 105                 return -1;
 106
 107         if (!nochdir)
 108                 chdir("/");
 109
 110         if (!noclose)
 111         {
 112                 struct STAT st;
 113
 114                 if ((fd = open_not_cancel_2(_PATH_DEVNULL, O_RDWR)) != -1
 115                         && (__builtin_expect (FSTAT (fd, &st), 0) == 0))
 116                 {
 117                         if (__builtin_expect (S_ISCHR (st.st_mode), 1) != 0) {
 118                                 dup2(fd, STDIN_FILENO);
 119                                 dup2(fd, STDOUT_FILENO);
 120                                 dup2(fd, STDERR_FILENO);
 121                                 if (fd > 2)
 122                                         close(fd);
 123                         } else {
 124                                 /* We must set an errno value since no
 125                                    function call actually failed.  */
 126                                 close_not_cancel_no_status (fd);
 127                                 __set_errno (ENODEV);
 128                                 return -1;
 129                         }
 130                 } else {
 131                         close_not_cancel_no_status (fd);
 132                         return -1;
 133                 }
 134         }
 135         return 0;
 136 }
 137 #endif