pty.c revision 154835 
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 154835 2006-01-26 01:33:26Z cognet $");
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 <libutil.h>
51#include <stdlib.h>
52#include <string.h>
53#include <termios.h>
54#include <unistd.h>
55
56int __use_pts(void);
57
58static int
59new_openpty(int *amaster, int *aslave, char *name, struct termios *termp,
60    struct winsize *winp)
61{
62	int master, slave;
63
64	master = posix_openpt(O_RDWR);
65	if (master == -1)
66		return (-1);
67
68	if (grantpt(master) == -1) {
69		close(master);
70		return (-1);
71	}
72
73	slave = open(ptsname(master), O_RDWR);
74	if (slave == -1) {
75		close(master);
76		return (-1);
77	}
78
79	if (unlockpt(master) == -1) {
80		close(master);
81		close(slave);
82		return (-1);
83	}
84
85	*amaster = master;
86	*aslave = slave;
87
88	if (name)
89		strcpy(name, ptsname(master));
90	if (termp)
91		tcsetattr(slave, TCSAFLUSH, termp);
92	if (winp)
93		ioctl(slave, TIOCSWINSZ, (char *)winp);
94
95	return (0);
96}
97
98int
99openpty(int *amaster, int *aslave, char *name, struct termios *termp, struct winsize *winp)
100{
101	char line[] = "/dev/ptyXX";
102	const char *cp1, *cp2;
103	int master, slave, ttygid;
104	struct group *gr;
105
106	if (__use_pts())
107		return (new_openpty(amaster, aslave, name, termp, winp));
108
109	if ((gr = getgrnam("tty")) != NULL)
110		ttygid = gr->gr_gid;
111	else
112		ttygid = -1;
113
114	for (cp1 = "pqrsPQRS"; *cp1; cp1++) {
115		line[8] = *cp1;
116		for (cp2 = "0123456789abcdefghijklmnopqrstuv"; *cp2; cp2++) {
117			line[5] = 'p';
118			line[9] = *cp2;
119			if ((master = open(line, O_RDWR, 0)) == -1) {
120				if (errno == ENOENT)
121					break; /* try the next pty group */
122			} else {
123				line[5] = 't';
124				(void) chown(line, getuid(), ttygid);
125				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
126				(void) revoke(line);
127				if ((slave = open(line, O_RDWR, 0)) != -1) {
128					*amaster = master;
129					*aslave = slave;
130					if (name)
131						strcpy(name, line);
132					if (termp)
133						(void) tcsetattr(slave,
134							TCSAFLUSH, termp);
135					if (winp)
136						(void) ioctl(slave, TIOCSWINSZ,
137							(char *)winp);
138					return (0);
139				}
140				(void) close(master);
141			}
142		}
143	}
144	errno = ENOENT;	/* out of ptys */
145	return (-1);
146}
147
148int
149forkpty(int *amaster, char *name, struct termios *termp, struct winsize *winp)
150{
151	int master, slave, pid;
152
153	if (openpty(&master, &slave, name, termp, winp) == -1)
154		return (-1);
155	switch (pid = fork()) {
156	case -1:
157		return (-1);
158	case 0:
159		/*
160		 * child
161		 */
162		(void) close(master);
163		login_tty(slave);
164		return (0);
165	}
166	/*
167	 * parent
168	 */
169	*amaster = master;
170	(void) close(slave);
171	return (pid);
172}
173