pty.c revision 28179 
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#if defined(LIBC_SCCS) && !defined(lint)
35#if 0
36static char sccsid[] = "@(#)pty.c	8.3 (Berkeley) 5/16/94";
37#else
38static const char rcsid[] =
39	"$Id$";
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 <stdio.h>
51#include <stdlib.h>
52#include <string.h>
53#include <termios.h>
54#include <unistd.h>
55#include <libutil.h>
56
57int
58openpty(amaster, aslave, name, termp, winp)
59	int *amaster, *aslave;
60	char *name;
61	struct termios *termp;
62	struct winsize *winp;
63{
64	static char line[] = "/dev/ptyXX";
65	register const char *cp1, *cp2;
66	register int master, slave, ttygid;
67	struct group *gr;
68
69	if ((gr = getgrnam("tty")) != NULL)
70		ttygid = gr->gr_gid;
71	else
72		ttygid = -1;
73
74	for (cp1 = "pqrsPQRS"; *cp1; cp1++) {
75		line[8] = *cp1;
76		for (cp2 = "0123456789abcdefghijklmnopqrstuv"; *cp2; cp2++) {
77			line[5] = 'p';
78			line[9] = *cp2;
79			if ((master = open(line, O_RDWR, 0)) == -1) {
80				if (errno == ENOENT)
81					return (-1);	/* out of ptys */
82			} else {
83				line[5] = 't';
84				(void) chown(line, getuid(), ttygid);
85				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
86				(void) revoke(line);
87				if ((slave = open(line, O_RDWR, 0)) != -1) {
88					*amaster = master;
89					*aslave = slave;
90					if (name)
91						strcpy(name, line);
92					if (termp)
93						(void) tcsetattr(slave,
94							TCSAFLUSH, termp);
95					if (winp)
96						(void) ioctl(slave, TIOCSWINSZ,
97							(char *)winp);
98					return (0);
99				}
100				(void) close(master);
101			}
102		}
103	}
104	errno = ENOENT;	/* out of ptys */
105	return (-1);
106}
107
108int
109forkpty(amaster, name, termp, winp)
110	int *amaster;
111	char *name;
112	struct termios *termp;
113	struct winsize *winp;
114{
115	int master, slave, pid;
116
117	if (openpty(&master, &slave, name, termp, winp) == -1)
118		return (-1);
119	switch (pid = fork()) {
120	case -1:
121		return (-1);
122	case 0:
123		/*
124		 * child
125		 */
126		(void) close(master);
127		login_tty(slave);
128		return (0);
129	}
130	/*
131	 * parent
132	 */
133	*amaster = master;
134	(void) close(slave);
135	return (pid);
136}
137