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glibc  2.9
setsid.c
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00001 /* Copyright (C) 1991, 1995, 1996, 1997 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <errno.h>
00020 #include <unistd.h>
00021 #include <sys/ioctl.h>
00022 #include <sys/types.h>
00023 #include <fcntl.h>
00024 
00025 /* Create a new session with the calling process as its leader.
00026    The process group IDs of the session and the calling process
00027    are set to the process ID of the calling process, which is returned.  */
00028 int
00029 __setsid ()
00030 {
00031   pid_t pid = getpid ();
00032   int tty;
00033   int save = errno;
00034 
00035   if (__getpgid (pid) == pid)
00036     {
00037       /* Already the leader.  */
00038       __set_errno (EPERM);
00039       return -1;
00040     }
00041 
00042   if (setpgid (pid, pid) < 0)
00043     return -1;
00044 
00045   tty = open ("/dev/tty", 0);
00046   if (tty < 0)
00047     {
00048       __set_errno (save);
00049       return 0;
00050     }
00051   (void) __ioctl (tty, TIOCNOTTY, 0);
00052   (void) __close (tty);
00053 
00054   __set_errno (save);
00055   return 0;
00056 }
00057 
00058 weak_alias (__setsid, setsid)