1 /* $OpenBSD: pty.c,v 1.22 2022/04/20 14:00:19 millert Exp $ */
2
3 /*-
4 * Copyright (c) 1990, 1993
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. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/types.h>
33 #include <sys/stat.h>
34 #include <sys/ioctl.h>
35 #include <fcntl.h>
36 #include <termios.h>
37 #include <errno.h>
38 #include <unistd.h>
39 #include <stdio.h>
40 #include <string.h>
41 #include <grp.h>
42 #include <sys/tty.h>
43
44 #include "util.h"
45
46 int
getptmfd(void)47 getptmfd(void)
48 {
49 return (open(PATH_PTMDEV, O_RDWR|O_CLOEXEC));
50 }
51
52 int
openpty(int * amaster,int * aslave,char * name,const struct termios * termp,const struct winsize * winp)53 openpty(int *amaster, int *aslave, char *name, const struct termios *termp,
54 const struct winsize *winp)
55 {
56 int ptmfd;
57
58 if ((ptmfd = getptmfd()) == -1)
59 return (-1);
60 if (fdopenpty(ptmfd, amaster, aslave, name, termp, winp) == -1) {
61 close(ptmfd);
62 return (-1);
63 }
64 close(ptmfd);
65 return (0);
66 }
67
68 int
fdopenpty(int ptmfd,int * amaster,int * aslave,char * name,const struct termios * termp,const struct winsize * winp)69 fdopenpty(int ptmfd, int *amaster, int *aslave, char *name,
70 const struct termios *termp, const struct winsize *winp)
71 {
72 int master, slave;
73 struct ptmget ptm;
74
75 /*
76 * Use /dev/ptm and the PTMGET ioctl to get a properly set up and
77 * owned pty/tty pair.
78 */
79 if (ioctl(ptmfd, PTMGET, &ptm) == -1)
80 return (-1);
81
82 master = ptm.cfd;
83 slave = ptm.sfd;
84 if (name) {
85 /*
86 * Manual page says "at least 16 characters".
87 */
88 strlcpy(name, ptm.sn, 16);
89 }
90 *amaster = master;
91 *aslave = slave;
92 if (termp)
93 (void) tcsetattr(slave, TCSAFLUSH, termp);
94 if (winp)
95 (void) ioctl(slave, TIOCSWINSZ, winp);
96 return (0);
97 }
98
99 pid_t
forkpty(int * amaster,char * name,const struct termios * termp,const struct winsize * winp)100 forkpty(int *amaster, char *name, const struct termios *termp,
101 const struct winsize *winp)
102 {
103 int ptmfd;
104 pid_t pid;
105
106 if ((ptmfd = getptmfd()) == -1)
107 return (-1);
108 if ((pid = fdforkpty(ptmfd, amaster, name, termp, winp)) == -1) {
109 close(ptmfd);
110 return (-1);
111 }
112 close(ptmfd);
113 return (pid);
114 }
115
116 pid_t
fdforkpty(int ptmfd,int * amaster,char * name,const struct termios * termp,const struct winsize * winp)117 fdforkpty(int ptmfd, int *amaster, char *name, const struct termios *termp,
118 const struct winsize *winp)
119 {
120 int master, slave;
121 pid_t pid;
122
123 if (fdopenpty(ptmfd, &master, &slave, name, termp, winp) == -1)
124 return (-1);
125 switch (pid = fork()) {
126 case -1:
127 (void) close(master);
128 (void) close(slave);
129 return (-1);
130 case 0:
131 /*
132 * child
133 */
134 (void) close(master);
135 login_tty(slave);
136 return (0);
137 }
138 /*
139 * parent
140 */
141 *amaster = master;
142 (void) close(slave);
143 return (pid);
144 }
145