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1.1 root 1: /* detach.c
2: Detach from the controlling terminal.
3:
4: Copyright (C) 1992 Ian Lance Taylor
5:
6: This file is part of the Taylor UUCP package.
7:
8: This program is free software; you can redistribute it and/or
9: modify it under the terms of the GNU General Public License as
10: published by the Free Software Foundation; either version 2 of the
11: License, or (at your option) any later version.
12:
13: This program is distributed in the hope that it will be useful, but
14: WITHOUT ANY WARRANTY; without even the implied warranty of
15: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16: General Public License for more details.
17:
18: You should have received a copy of the GNU General Public License
19: along with this program; if not, write to the Free Software
20: Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21:
22: The author of the program may be contacted at [email protected] or
23: c/o Infinity Development Systems, P.O. Box 520, Waltham, MA 02254.
24: */
25:
26: #include "uucp.h"
27:
28: #include "uudefs.h"
29: #include "system.h"
30: #include "sysdep.h"
31:
32: #include <errno.h>
33:
34: #if HAVE_SYS_IOCTL_H
35: #include <sys/ioctl.h>
36: #endif
37:
38: #ifdef TIOCNOTTY
39: #define HAVE_TIOCNOTTY 1
40: #else
41: #define HAVE_TIOCNOTTY 0
42: #endif
43:
44: #if HAVE_FCNTL_H
45: #include <fcntl.h>
46: #else
47: #if HAVE_SYS_FILE_H
48: #include <sys/file.h>
49: #endif
50: #endif
51:
52: #ifndef O_RDONLY
53: #define O_RDONLY 0
54: #define O_WRONLY 1
55: #define O_RDWR 2
56: #endif
57:
58: /* Detach from the controlling terminal. This is called by uucico if
59: it is calling out to another system, so that it can receive SIGHUP
60: signals from the port it calls out on. It is also called by uucico
61: just before it starts uuxqt, so that uuxqt is completely
62: independent of the terminal. */
63:
64: void
65: usysdep_detach ()
66: {
67: #if ! HAVE_BSD_PGRP || ! HAVE_TIOCNOTTY
68:
69: pid_t igrp;
70:
71: /* First make sure we are not a process group leader. If we have
72: TIOCNOTTY, this doesn't matter, since TIOCNOTTY sets our process
73: group to 0 anyhow. */
74:
75: #if HAVE_BSD_PGRP
76: igrp = getpgrp (0);
77: #else
78: igrp = getpgrp ();
79: #endif
80:
81: if (igrp == getpid ())
82: {
83: boolean fignored;
84: pid_t ipid;
85:
86: /* Ignore SIGHUP, since our process group leader is about to
87: die. */
88: usset_signal (SIGHUP, SIG_IGN, FALSE, &fignored);
89:
90: ipid = ixsfork ();
91: if (ipid < 0)
92: ulog (LOG_FATAL, "fork: %s", strerror (errno));
93:
94: if (ipid != 0)
95: _exit (EXIT_SUCCESS);
96:
97: /* We'll always wind up as a child of process number 1, right?
98: Right? We have to wait for our parent to die before
99: reenabling SIGHUP. */
100: while (getppid () != 1)
101: sleep (1);
102:
103: ulog_id (getpid ());
104:
105: /* Restore SIGHUP catcher if it wasn't being ignored. */
106: if (! fignored)
107: usset_signal (SIGHUP, ussignal, TRUE, (boolean *) NULL);
108: }
109:
110: #endif /* ! HAVE_BSD_PGRP || ! HAVE_TIOCNOTTY */
111:
112: #if HAVE_TIOCNOTTY
113: /* Lose the original controlling terminal. If standard input has
114: been reopened to /dev/null, this will do no harm. If another
115: port has been opened to become the controlling terminal, it
116: should have been detached when it was closed. */
117: (void) ioctl (0, TIOCNOTTY, (char *) NULL);
118: #endif
119:
120: /* Close stdin, stdout and stderr and reopen them on /dev/null, to
121: make sure we have no connection at all to the terminal. */
122: (void) close (0);
123: (void) close (1);
124: (void) close (2);
125: if (open ((char *) "/dev/null", O_RDONLY) != 0
126: || open ((char *) "/dev/null", O_WRONLY) != 1
127: || open ((char *) "/dev/null", O_WRONLY) != 2)
128: ulog (LOG_FATAL, "open (/dev/null): %s", strerror (errno));
129:
130: #if HAVE_BSD_PGRP
131:
132: /* Make sure our process group ID is set to 0. On BSD TIOCNOTTY
133: should already have set it 0, so this will do no harm. On System
134: V we presumably did not execute the TIOCNOTTY call, but the
135: System V setpgrp will detach the controlling terminal anyhow.
136: This lets us use the same code on both BSD and System V, provided
137: it compiles correctly, which life easier for the configure
138: script. We don't output an error if we got EPERM because some
139: BSD variants don't permit this usage of setpgrp (which means they
140: don't provide any way to pick up a new controlling terminal). */
141:
142: if (setpgrp (0, 0) < 0)
143: {
144: if (errno != EPERM)
145: ulog (LOG_ERROR, "setpgrp: %s", strerror (errno));
146: }
147:
148: #else /* ! HAVE_BSD_PGRP */
149:
150: #if HAVE_SETSID
151:
152: /* Under POSIX the setsid call creates a new session for which we
153: are the process group leader. It also detaches us from our
154: controlling terminal. I'm using the BSD setpgrp call first
155: because they should be equivalent for my purposes, but it turns
156: out that on Ultrix 4.0 setsid prevents us from ever acquiring
157: another controlling terminal (it does not change our process
158: group, and Ultrix 4.0 prevents us from setting our process group
159: to 0). */
160: (void) setsid ();
161:
162: #else /* ! HAVE_SETSID */
163:
164: #if HAVE_SETPGRP
165:
166: /* Now we assume we have the System V setpgrp, which takes no
167: arguments, and we couldn't compile the HAVE_BSD_PGRP code above
168: because there was a prototype somewhere in scope. On System V
169: setpgrp makes us the leader of a new process group and also
170: detaches the controlling terminal. */
171:
172: if (setpgrp () < 0)
173: ulog (LOG_ERROR, "setpgrp: %s", strerror (errno));
174:
175: #else /* ! HAVE_SETPGRP */
176:
177: #error Must detach from controlling terminal
178:
179: #endif /* HAVE_SETPGRP */
180: #endif /* ! HAVE_SETSID */
181: #endif /* ! HAVE_BSD_PGRP */
182:
183: /* At this point we have completely detached from our controlling
184: terminal. The next terminal device we open will probably become
185: our controlling terminal. */
186: }
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