pty.c revision 92913 
1/*-
2 * Copyright (c) 1990, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <sys/cdefs.h>
35__FBSDID("$FreeBSD: head/lib/libutil/pty.c 92913 2002-03-21 23:39:28Z obrien $");
36
37#if defined(LIBC_SCCS) && !defined(lint)
38#if 0
39static char sccsid[] = "@(#)pty.c	8.3 (Berkeley) 5/16/94";
40#endif
41#endif /* LIBC_SCCS and not lint */
42
43#include <sys/types.h>
44#include <sys/ioctl.h>
45#include <sys/stat.h>
46
47#include <errno.h>
48#include <fcntl.h>
49#include <grp.h>
50#include <stdlib.h>
51#include <string.h>
52#include <termios.h>
53#include <unistd.h>
54#include <libutil.h>
55
56int
57openpty(amaster, aslave, name, termp, winp)
58	int *amaster, *aslave;
59	char *name;
60	struct termios *termp;
61	struct winsize *winp;
62{
63	char line[] = "/dev/ptyXX";
64	const char *cp1, *cp2;
65	int master, slave, ttygid;
66	struct group *gr;
67
68	if ((gr = getgrnam("tty")) != NULL)
69		ttygid = gr->gr_gid;
70	else
71		ttygid = -1;
72
73	for (cp1 = "pqrsPQRS"; *cp1; cp1++) {
74		line[8] = *cp1;
75		for (cp2 = "0123456789abcdefghijklmnopqrstuv"; *cp2; cp2++) {
76			line[5] = 'p';
77			line[9] = *cp2;
78			if ((master = open(line, O_RDWR, 0)) == -1) {
79				if (errno == ENOENT)
80					break; /* try the next pty group */
81			} else {
82				line[5] = 't';
83				(void) chown(line, getuid(), ttygid);
84				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
85				(void) revoke(line);
86				if ((slave = open(line, O_RDWR, 0)) != -1) {
87					*amaster = master;
88					*aslave = slave;
89					if (name)
90						strcpy(name, line);
91					if (termp)
92						(void) tcsetattr(slave,
93							TCSAFLUSH, termp);
94					if (winp)
95						(void) ioctl(slave, TIOCSWINSZ,
96							(char *)winp);
97					return (0);
98				}
99				(void) close(master);
100			}
101		}
102	}
103	errno = ENOENT;	/* out of ptys */
104	return (-1);
105}
106
107int
108forkpty(amaster, name, termp, winp)
109	int *amaster;
110	char *name;
111	struct termios *termp;
112	struct winsize *winp;
113{
114	int master, slave, pid;
115
116	if (openpty(&master, &slave, name, termp, winp) == -1)
117		return (-1);
118	switch (pid = fork()) {
119	case -1:
120		return (-1);
121	case 0:
122		/*
123		 * child
124		 */
125		(void) close(master);
126		login_tty(slave);
127		return (0);
128	}
129	/*
130	 * parent
131	 */
132	*amaster = master;
133	(void) close(slave);
134	return (pid);
135}
136