xref: /netbsd-src/lib/libutil/pty.c (revision 0dd5877adce57db949b16ae963e5a6831cccdfb6)
1 /*	$NetBSD: pty.c,v 1.18 2002/02/02 05:48:31 tls Exp $	*/
2 
3 /*-
4  * Copyright (c) 1990, 1993, 1994
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <sys/cdefs.h>
37 #if defined(LIBC_SCCS) && !defined(lint)
38 #if 0
39 static char sccsid[] = "@(#)pty.c	8.3 (Berkeley) 5/16/94";
40 #else
41 __RCSID("$NetBSD: pty.c,v 1.18 2002/02/02 05:48:31 tls Exp $");
42 #endif
43 #endif /* LIBC_SCCS and not lint */
44 
45 #include <sys/types.h>
46 #include <sys/ioctl.h>
47 #include <sys/stat.h>
48 
49 #include <assert.h>
50 #include <errno.h>
51 #include <fcntl.h>
52 #include <grp.h>
53 #include <stdio.h>
54 #include <string.h>
55 #include <termios.h>
56 #include <unistd.h>
57 #include <util.h>
58 
59 /*
60  * XXX: `v' removed until no ports are using console devices which use ttyv0
61  */
62 #define TTY_LETTERS	"pqrstuwxyzPQRST"
63 
64 int
65 openpty(int *amaster, int *aslave, char *name, struct termios *termp,
66 	struct winsize *winp)
67 {
68 	static char line[] = "/dev/XtyXX";
69 	const char *cp1, *cp2;
70 	int master, slave, tries = 0;
71 	gid_t ttygid;
72 	struct group *gr;
73 
74 	_DIAGASSERT(amaster != NULL);
75 	_DIAGASSERT(aslave != NULL);
76 	/* name may be NULL */
77 	/* termp may be NULL */
78 	/* winp may be NULL */
79 
80 	if ((gr = getgrnam("tty")) != NULL)
81 		ttygid = gr->gr_gid;
82 	else
83 		ttygid = (gid_t) -1;
84 
85 	for (cp1 = TTY_LETTERS; *cp1; cp1++) {
86 		tries = 0;
87 try:
88 		line[8] = *cp1;
89 		for (cp2 = !tries ?
90 		     "ghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" :
91 		     "0123456789abcdef" ; *cp2; cp2++) {
92 			line[5] = 'p';
93 			line[9] = *cp2;
94 			if ((master = open(line, O_RDWR, 0)) == -1) {
95 				if ((errno == ENOENT) && tries) {
96 					return (-1); 	/* out of ptys */
97 				}
98 			} else {
99 				line[5] = 't';
100 				(void) chown(line, getuid(), ttygid);
101 				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
102 				(void) revoke(line);
103 				if ((slave = open(line, O_RDWR, 0)) != -1) {
104 					*amaster = master;
105 					*aslave = slave;
106 					if (name)
107 						strcpy(name, line);
108 					if (termp)
109 						(void) tcsetattr(slave,
110 							TCSAFLUSH, termp);
111 					if (winp)
112 						(void) ioctl(slave, TIOCSWINSZ,
113 						    winp);
114 					return (0);
115 				}
116 				(void) close(master);
117 			}
118 			if(!tries) {
119 				tries++;
120 				goto try;
121 			}
122 		}
123 	}
124 	errno = ENOENT;	/* out of ptys */
125 	return (-1);
126 }
127 
128 pid_t
129 forkpty(int *amaster, char *name, struct termios *termp, struct winsize *winp)
130 {
131 	int master, slave;
132 	pid_t pid;
133 
134 	_DIAGASSERT(amaster != NULL);
135 	/* name may be NULL */
136 	/* termp may be NULL */
137 	/* winp may be NULL */
138 
139 	if (openpty(&master, &slave, name, termp, winp) == -1)
140 		return (-1);
141 	switch (pid = fork()) {
142 	case -1:
143 		return (-1);
144 	case 0:
145 		/*
146 		 * child
147 		 */
148 		(void) close(master);
149 		login_tty(slave);
150 		return (0);
151 	}
152 	/*
153 	 * parent
154 	 */
155 	*amaster = master;
156 	(void) close(slave);
157 	return (pid);
158 }
159