pty.c revision 165906 
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 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD: head/lib/libutil/pty.c 165906 2007-01-09 01:02:06Z imp $");
32
33#if defined(LIBC_SCCS) && !defined(lint)
34#if 0
35static char sccsid[] = "@(#)pty.c	8.3 (Berkeley) 5/16/94";
36#endif
37#endif /* LIBC_SCCS and not lint */
38
39#include <sys/types.h>
40#include <sys/ioctl.h>
41#include <sys/stat.h>
42
43#include <errno.h>
44#include <fcntl.h>
45#include <grp.h>
46#include <libutil.h>
47#include <stdlib.h>
48#include <string.h>
49#include <termios.h>
50#include <unistd.h>
51
52int __use_pts(void);
53
54static int
55new_openpty(int *amaster, int *aslave, char *name, struct termios *termp,
56    struct winsize *winp)
57{
58	int master, slave;
59
60	master = posix_openpt(O_RDWR);
61	if (master == -1)
62		return (-1);
63
64	if (grantpt(master) == -1) {
65		close(master);
66		return (-1);
67	}
68
69	slave = open(ptsname(master), O_RDWR);
70	if (slave == -1) {
71		close(master);
72		return (-1);
73	}
74
75	if (unlockpt(master) == -1) {
76		close(master);
77		close(slave);
78		return (-1);
79	}
80
81	*amaster = master;
82	*aslave = slave;
83
84	if (name)
85		strcpy(name, ptsname(master));
86	if (termp)
87		tcsetattr(slave, TCSAFLUSH, termp);
88	if (winp)
89		ioctl(slave, TIOCSWINSZ, (char *)winp);
90
91	return (0);
92}
93
94int
95openpty(int *amaster, int *aslave, char *name, struct termios *termp, struct winsize *winp)
96{
97	char line[] = "/dev/ptyXX";
98	const char *cp1, *cp2;
99	int master, slave, ttygid;
100	struct group *gr;
101
102	if (__use_pts())
103		return (new_openpty(amaster, aslave, name, termp, winp));
104
105	if ((gr = getgrnam("tty")) != NULL)
106		ttygid = gr->gr_gid;
107	else
108		ttygid = -1;
109
110	for (cp1 = "pqrsPQRS"; *cp1; cp1++) {
111		line[8] = *cp1;
112		for (cp2 = "0123456789abcdefghijklmnopqrstuv"; *cp2; cp2++) {
113			line[5] = 'p';
114			line[9] = *cp2;
115			if ((master = open(line, O_RDWR, 0)) == -1) {
116				if (errno == ENOENT)
117					break; /* try the next pty group */
118			} else {
119				line[5] = 't';
120				(void) chown(line, getuid(), ttygid);
121				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
122				(void) revoke(line);
123				if ((slave = open(line, O_RDWR, 0)) != -1) {
124					*amaster = master;
125					*aslave = slave;
126					if (name)
127						strcpy(name, line);
128					if (termp)
129						(void) tcsetattr(slave,
130							TCSAFLUSH, termp);
131					if (winp)
132						(void) ioctl(slave, TIOCSWINSZ,
133							(char *)winp);
134					return (0);
135				}
136				(void) close(master);
137			}
138		}
139	}
140	errno = ENOENT;	/* out of ptys */
141	return (-1);
142}
143
144int
145forkpty(int *amaster, char *name, struct termios *termp, struct winsize *winp)
146{
147	int master, slave, pid;
148
149	if (openpty(&master, &slave, name, termp, winp) == -1)
150		return (-1);
151	switch (pid = fork()) {
152	case -1:
153		return (-1);
154	case 0:
155		/*
156		 * child
157		 */
158		(void) close(master);
159		login_tty(slave);
160		return (0);
161	}
162	/*
163	 * parent
164	 */
165	*amaster = master;
166	(void) close(slave);
167	return (pid);
168}
169