pty.c revision 1574 
1/*-
2 * Copyright (c) 1990, 1993
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)
35static char sccsid[] = "@(#)pty.c	8.1 (Berkeley) 6/4/93";
36#endif /* LIBC_SCCS and not lint */
37
38#include <sys/cdefs.h>
39#include <sys/types.h>
40#include <sys/stat.h>
41#include <sys/ioctl.h>
42#include <fcntl.h>
43#include <termios.h>
44#include <errno.h>
45#include <unistd.h>
46#include <stdio.h>
47#include <string.h>
48#include <grp.h>
49
50openpty(amaster, aslave, name, termp, winp)
51	int *amaster, *aslave;
52	char *name;
53	struct termios *termp;
54	struct winsize *winp;
55{
56	static char line[] = "/dev/ptyXX";
57	register const char *cp1, *cp2;
58	register int master, slave, ttygid;
59	struct group *gr;
60
61	if ((gr = getgrnam("tty")) != NULL)
62		ttygid = gr->gr_gid;
63	else
64		ttygid = -1;
65
66	for (cp1 = "pqrs"; *cp1; cp1++) {
67		line[8] = *cp1;
68		for (cp2 = "0123456789abcdef"; *cp2; cp2++) {
69			line[9] = *cp2;
70			if ((master = open(line, O_RDWR, 0)) == -1) {
71				if (errno == ENOENT)
72					return (-1);	/* out of ptys */
73			} else {
74				line[5] = 't';
75				(void) chown(line, getuid(), ttygid);
76				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
77				(void) revoke(line);
78				if ((slave = open(line, O_RDWR, 0)) != -1) {
79					*amaster = master;
80					*aslave = slave;
81					if (name)
82						strcpy(name, line);
83					if (termp)
84						(void) tcsetattr(slave,
85							TCSAFLUSH, termp);
86					if (winp)
87						(void) ioctl(slave, TIOCSWINSZ,
88							(char *)winp);
89					return (0);
90				}
91				(void) close(master);
92				line[5] = 'p';
93			}
94		}
95	}
96	errno = ENOENT;	/* out of ptys */
97	return (-1);
98}
99
100forkpty(amaster, name, termp, winp)
101	int *amaster;
102	char *name;
103	struct termios *termp;
104	struct winsize *winp;
105{
106	int master, slave, pid;
107
108	if (openpty(&master, &slave, name, termp, winp) == -1)
109		return (-1);
110	switch (pid = fork()) {
111	case -1:
112		return (-1);
113	case 0:
114		/*
115		 * child
116		 */
117		(void) close(master);
118		login_tty(slave);
119		return (0);
120	}
121	/*
122	 * parent
123	 */
124	*amaster = master;
125	(void) close(slave);
126	return (pid);
127}
128