pty.c revision 11681 
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)
35static char sccsid[] = "@(#)pty.c	8.3 (Berkeley) 5/16/94";
36#endif /* LIBC_SCCS and not lint */
37
38#include <sys/types.h>
39#include <sys/ioctl.h>
40#include <sys/stat.h>
41
42#include <errno.h>
43#include <fcntl.h>
44#include <grp.h>
45#include <stdio.h>
46#include <stdlib.h>
47#include <string.h>
48#include <termios.h>
49#include <unistd.h>
50
51openpty(amaster, aslave, name, termp, winp)
52	int *amaster, *aslave;
53	char *name;
54	struct termios *termp;
55	struct winsize *winp;
56{
57	static char line[] = "/dev/ptyXX";
58	register const char *cp1, *cp2;
59	register int master, slave, ttygid;
60	struct group *gr;
61
62	if ((gr = getgrnam("tty")) != NULL)
63		ttygid = gr->gr_gid;
64	else
65		ttygid = -1;
66
67	for (cp1 = "pqrsPQRS"; *cp1; cp1++) {
68		line[8] = *cp1;
69		for (cp2 = "0123456789abcdefghijklmnopqrstuv"; *cp2; cp2++) {
70			line[5] = 'p';
71			line[9] = *cp2;
72			if ((master = open(line, O_RDWR, 0)) == -1) {
73				if (errno == ENOENT)
74					return (-1);	/* out of ptys */
75			} else {
76				line[5] = 't';
77				(void) chown(line, getuid(), ttygid);
78				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
79				(void) revoke(line);
80				if ((slave = open(line, O_RDWR, 0)) != -1) {
81					*amaster = master;
82					*aslave = slave;
83					if (name)
84						strcpy(name, line);
85					if (termp)
86						(void) tcsetattr(slave,
87							TCSAFLUSH, termp);
88					if (winp)
89						(void) ioctl(slave, TIOCSWINSZ,
90							(char *)winp);
91					return (0);
92				}
93				(void) close(master);
94			}
95		}
96	}
97	errno = ENOENT;	/* out of ptys */
98	return (-1);
99}
100
101forkpty(amaster, name, termp, winp)
102	int *amaster;
103	char *name;
104	struct termios *termp;
105	struct winsize *winp;
106{
107	int master, slave, pid;
108
109	if (openpty(&master, &slave, name, termp, winp) == -1)
110		return (-1);
111	switch (pid = fork()) {
112	case -1:
113		return (-1);
114	case 0:
115		/*
116		 * child
117		 */
118		(void) close(master);
119		login_tty(slave);
120		return (0);
121	}
122	/*
123	 * parent
124	 */
125	*amaster = master;
126	(void) close(slave);
127	return (pid);
128}
129