xref: /dragonfly/lib/libutil/pty.c (revision e65bc1c3)
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. 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  * @(#)pty.c	8.3 (Berkeley) 5/16/94
30  * $FreeBSD: src/lib/libutil/pty.c,v 1.10 1999/08/28 00:05:51 peter Exp $
31  * $DragonFly: src/lib/libutil/pty.c,v 1.6 2007/12/30 13:44:33 matthias Exp $
32  */
33 
34 #include <sys/types.h>
35 #include <sys/ioctl.h>
36 #include <sys/stat.h>
37 
38 #include <errno.h>
39 #include <fcntl.h>
40 #include <grp.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <termios.h>
44 #include <unistd.h>
45 
46 #include "libutil.h"
47 
48 #define UNIX98_PTYS	1
49 
50 int
51 openpty(int *amaster, int *aslave, char *name, struct termios *termp,
52 	struct winsize *winp)
53 {
54 	char line[] = "/dev/ptyXX";
55 	const char *cp1, *cp2;
56 	int master, slave, ttygid;
57 	struct group *gr;
58 	const char *slave_name;
59 
60 	if ((gr = getgrnam("tty")) != NULL)
61 		ttygid = gr->gr_gid;
62 	else
63 		ttygid = -1;
64 
65 #ifdef UNIX98_PTYS
66 	master = posix_openpt(O_RDWR|O_NOCTTY);
67 	if (master == -1)
68 		goto fallback;
69 
70 	if (grantpt(master) != 0) {
71 		close(master);
72 		goto fallback;
73 	}
74 
75 	if (unlockpt(master) != 0) {
76 		close(master);
77 		goto fallback;
78 	}
79 
80 	slave_name = ptsname(master);
81 	if (slave_name == NULL) {
82 		close(master);
83 		goto fallback;
84 	}
85 
86 	slave = open(slave_name, O_RDWR);
87 	if (slave == -1) {
88 		close(master);
89 		goto fallback;
90 	}
91 
92 	*amaster = master;
93 	*aslave = slave;
94 
95 	if (name)
96 		strcpy(name, slave_name);
97 	if (termp)
98 		tcsetattr(slave, TCSAFLUSH, termp);
99 	if (winp)
100 		ioctl(slave, TIOCSWINSZ, (char *)winp);
101 
102 	return (0);
103 
104 fallback:
105 #endif
106 
107 	for (cp1 = "pqrsPQRS"; *cp1; cp1++) {
108 		line[8] = *cp1;
109 		for (cp2 = "0123456789abcdefghijklmnopqrstuv"; *cp2; cp2++) {
110 			line[5] = 'p';
111 			line[9] = *cp2;
112 			if ((master = open(line, O_RDWR, 0)) == -1) {
113 				if (errno == ENOENT)
114 					return (-1);	/* out of ptys */
115 			} else {
116 				line[5] = 't';
117 				(void) chown(line, getuid(), ttygid);
118 				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
119 				(void) revoke(line);
120 				if ((slave = open(line, O_RDWR, 0)) != -1) {
121 					*amaster = master;
122 					*aslave = slave;
123 					if (name)
124 						strcpy(name, line);
125 					if (termp)
126 						(void) tcsetattr(slave,
127 							TCSAFLUSH, termp);
128 					if (winp)
129 						(void) ioctl(slave, TIOCSWINSZ,
130 							(char *)winp);
131 					return (0);
132 				}
133 				(void) close(master);
134 			}
135 		}
136 	}
137 	errno = ENOENT;	/* out of ptys */
138 	return (-1);
139 }
140 
141 int
142 forkpty(int *amaster, char *name, struct termios *termp, struct winsize *winp)
143 {
144 	int master, slave, pid;
145 
146 	if (openpty(&master, &slave, name, termp, winp) == -1)
147 		return (-1);
148 	switch (pid = fork()) {
149 	case -1:
150 		return (-1);
151 	case 0:
152 		/*
153 		 * child
154 		 */
155 		(void) close(master);
156 		login_tty(slave);
157 		return (0);
158 	}
159 	/*
160 	 * parent
161 	 */
162 	*amaster = master;
163 	(void) close(slave);
164 	return (pid);
165 }
166