xref: /freebsd/lib/libutil/pty.c (revision a220d00e74dd245b4fca59c5eca0c53963686325)
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("$FreeBSD$");
36 
37 #if defined(LIBC_SCCS) && !defined(lint)
38 #if 0
39 static 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 <stdlib.h>
51 #include <string.h>
52 #include <termios.h>
53 #include <unistd.h>
54 #include <libutil.h>
55 
56 int
57 openpty(amaster, aslave, name, termp, winp)
58 	int *amaster, *aslave;
59 	char *name;
60 	struct termios *termp;
61 	struct winsize *winp;
62 {
63 	char line[] = "/dev/ptyXX";
64 	register const char *cp1, *cp2;
65 	register int master, slave, ttygid;
66 	struct group *gr;
67 
68 	if ((gr = getgrnam("tty")) != NULL)
69 		ttygid = gr->gr_gid;
70 	else
71 		ttygid = -1;
72 
73 	for (cp1 = "pqrsPQRS"; *cp1; cp1++) {
74 		line[8] = *cp1;
75 		for (cp2 = "0123456789abcdefghijklmnopqrstuv"; *cp2; cp2++) {
76 			line[5] = 'p';
77 			line[9] = *cp2;
78 			if ((master = open(line, O_RDWR, 0)) == -1) {
79 				if (errno == ENOENT)
80 					break; /* try the next pty group */
81 			} else {
82 				line[5] = 't';
83 				(void) chown(line, getuid(), ttygid);
84 				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
85 				(void) revoke(line);
86 				if ((slave = open(line, O_RDWR, 0)) != -1) {
87 					*amaster = master;
88 					*aslave = slave;
89 					if (name)
90 						strcpy(name, line);
91 					if (termp)
92 						(void) tcsetattr(slave,
93 							TCSAFLUSH, termp);
94 					if (winp)
95 						(void) ioctl(slave, TIOCSWINSZ,
96 							(char *)winp);
97 					return (0);
98 				}
99 				(void) close(master);
100 			}
101 		}
102 	}
103 	errno = ENOENT;	/* out of ptys */
104 	return (-1);
105 }
106 
107 int
108 forkpty(amaster, name, termp, winp)
109 	int *amaster;
110 	char *name;
111 	struct termios *termp;
112 	struct winsize *winp;
113 {
114 	int master, slave, pid;
115 
116 	if (openpty(&master, &slave, name, termp, winp) == -1)
117 		return (-1);
118 	switch (pid = fork()) {
119 	case -1:
120 		return (-1);
121 	case 0:
122 		/*
123 		 * child
124 		 */
125 		(void) close(master);
126 		login_tty(slave);
127 		return (0);
128 	}
129 	/*
130 	 * parent
131 	 */
132 	*amaster = master;
133 	(void) close(slave);
134 	return (pid);
135 }
136