1 /*********************************************************************** 2 * * 3 * This software is part of the ast package * 4 * Copyright (c) 1985-2007 AT&T Knowledge Ventures * 5 * and is licensed under the * 6 * Common Public License, Version 1.0 * 7 * by AT&T Knowledge Ventures * 8 * * 9 * A copy of the License is available at * 10 * http://www.opensource.org/licenses/cpl1.0.txt * 11 * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) * 12 * * 13 * Information and Software Systems Research * 14 * AT&T Research * 15 * Florham Park NJ * 16 * * 17 * Glenn Fowler <gsf@research.att.com> * 18 * David Korn <dgk@research.att.com> * 19 * Phong Vo <kpv@research.att.com> * 20 * * 21 ***********************************************************************/ 22 #pragma prototyped 23 24 #include <ast.h> 25 26 #if _lib_setsid 27 28 NoN(setsid) 29 30 #else 31 32 #include <ast_tty.h> 33 #include <error.h> 34 35 /* 36 * become new process group leader and drop control tty 37 */ 38 39 pid_t 40 setsid(void) 41 { 42 int pg; 43 #ifdef TIOCNOTTY 44 int fd; 45 #endif 46 47 /* 48 * become a new process group leader 49 */ 50 51 if ((pg = getpid()) == getpgrp()) 52 { 53 errno = EPERM; 54 return(-1); 55 } 56 setpgid(pg, pg); 57 #ifdef TIOCNOTTY 58 59 /* 60 * drop the control tty 61 */ 62 63 if ((fd = open("/dev/tty", O_RDONLY)) >= 0) 64 { 65 ioctl(fd, TIOCNOTTY, 0); 66 close(fd); 67 } 68 #else 69 70 /* 71 * second child in s5 to avoid reacquiring the control tty 72 */ 73 74 #if _lib_fork && HUH920711 /* some s5's botch this */ 75 switch (fork()) 76 { 77 case -1: 78 exit(1); 79 case 0: 80 break; 81 default: 82 exit(0); 83 } 84 #endif 85 86 #endif 87 return(pg); 88 } 89 90 #endif 91