xref: /illumos-gate/usr/src/lib/libc/port/gen/pt.c (revision 8b913f79fc4449ba917263a4c79fcb647ed4e0af)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*
28  * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
29  * Copyright 2024 Oxide Computer Company
30  */
31 
32 /*	Copyright (c) 1988 AT&T	*/
33 /*	  All Rights Reserved	*/
34 
35 #pragma weak _ptsname = ptsname
36 #pragma weak _grantpt = grantpt
37 #pragma weak _unlockpt = unlockpt
38 
39 #include "lint.h"
40 #include "libc.h"
41 #include "mtlib.h"
42 #include <sys/types.h>
43 #include <signal.h>
44 #include <sys/param.h>
45 #include <sys/mkdev.h>
46 #include <sys/stream.h>
47 #include <sys/stropts.h>
48 #include <sys/wait.h>
49 #include <sys/signal.h>
50 #include <errno.h>
51 #include <fcntl.h>
52 #include <sys/stat.h>
53 #include <sys/ptms.h>
54 #include <string.h>
55 #include <stdlib.h>
56 #include <unistd.h>
57 #include <wait.h>
58 #include <spawn.h>
59 #include <grp.h>
60 #include "tsd.h"
61 
62 #define	PTSNAME "/dev/pts/"		/* slave name */
63 #define	PTLEN   32			/* slave name length */
64 #define	DEFAULT_TTY_GROUP	"tty"	/* slave device group owner */
65 
66 /*
67  *  Check that fd argument is a file descriptor of an opened master.
68  *  Do this by sending an ISPTM ioctl message down stream. Ioctl()
69  *  will fail if:(1) fd is not a valid file descriptor.(2) the file
70  *  represented by fd does not understand ISPTM(not a master device).
71  *  If we have a valid master, get its minor number via fstat().
72  *  Concatenate it to PTSNAME and return it as the name of the slave
73  *  device.
74  */
75 static dev_t
ptsdev(int fd)76 ptsdev(int fd)
77 {
78 	struct stat64 status;
79 	struct strioctl istr;
80 
81 	istr.ic_cmd = ISPTM;
82 	istr.ic_len = 0;
83 	istr.ic_timout = 0;
84 	istr.ic_dp = NULL;
85 
86 	if (ioctl(fd, I_STR, &istr) < 0 || fstat64(fd, &status) < 0)
87 		return (NODEV);
88 
89 	return (minor(status.st_rdev));
90 }
91 
92 int
ptsname_r(int fd,char * name,size_t len)93 ptsname_r(int fd, char *name, size_t len)
94 {
95 	dev_t dev;
96 
97 	if (name == NULL)
98 		return (EINVAL);
99 
100 	if ((dev = ptsdev(fd)) == NODEV)
101 		return (errno);
102 
103 	if (snprintf(name, len, "%s%d", PTSNAME, dev) >= len)
104 		return (ERANGE);
105 
106 	/*
107 	 * This lookup will create the /dev/pts node (if the corresponding pty
108 	 * exists). POSIX basically never really indicated whether or not
109 	 * ptsname() was allowed to return errors or not, though we did. If we
110 	 * played strictly by the book, this should probably be an EINVAL or
111 	 * ENOTTY return; however, to help someone have a chance of debugging
112 	 * this if something goes wrong we stick with our traditional behavior
113 	 * and return a slightly broader errno set. If this causes portability
114 	 * issues in practice, then it should be changed to just return EINVAL.
115 	 */
116 	if (access(name, F_OK) != 0)
117 		return (errno);
118 
119 	return (0);
120 }
121 
122 char *
ptsname(int fd)123 ptsname(int fd)
124 {
125 	int ret;
126 	char *sname;
127 
128 	sname = tsdalloc(_T_PTSNAME, PTLEN, NULL);
129 	if (sname == NULL)
130 		return (NULL);
131 
132 	if ((ret = ptsname_r(fd, sname, PTLEN)) != 0) {
133 		errno = ret;
134 		return (NULL);
135 	}
136 
137 	return (sname);
138 }
139 
140 /*
141  * Send an ioctl down to the master device requesting the
142  * master/slave pair be unlocked.
143  */
144 int
unlockpt(int fd)145 unlockpt(int fd)
146 {
147 	struct strioctl istr;
148 
149 	istr.ic_cmd = UNLKPT;
150 	istr.ic_len = 0;
151 	istr.ic_timout = 0;
152 	istr.ic_dp = NULL;
153 
154 	if (ioctl(fd, I_STR, &istr) < 0)
155 		return (-1);
156 
157 	return (0);
158 }
159 
160 /*
161  * XPG4v2 requires that open of a slave pseudo terminal device
162  * provides the process with an interface that is identical to
163  * the terminal interface.
164  *
165  * To satisfy this, in strict XPG4v2 mode, this routine also sends
166  * a message down the stream that sets a flag in the kernel module
167  * so that additional actions are performed when opening an
168  * associated slave PTY device. When this happens, modules are
169  * automatically pushed onto the stream to provide terminal
170  * semantics and those modules are then informed that they should
171  * behave in strict XPG4v2 mode which modifies their behaviour. In
172  * particular, in strict XPG4v2 mode, empty blocks will be sent up
173  * the master side of the stream rather than being suppressed.
174  *
175  * Most applications do not expect this behaviour so it is only
176  * enabled for programs compiled in strict XPG4v2 mode (see
177  * stdlib.h).
178  */
179 int
__unlockpt_xpg4(int fd)180 __unlockpt_xpg4(int fd)
181 {
182 	int ret;
183 
184 	if ((ret = unlockpt(fd)) == 0) {
185 		struct strioctl istr;
186 
187 		istr.ic_cmd = PTSSTTY;
188 		istr.ic_len = 0;
189 		istr.ic_timout = 0;
190 		istr.ic_dp = NULL;
191 
192 		if (ioctl(fd, I_STR, &istr) < 0)
193 			ret = -1;
194 	}
195 
196 	return (ret);
197 }
198 
199 int
grantpt(int fd)200 grantpt(int fd)
201 {
202 	struct strioctl istr;
203 	pt_own_t pto;
204 	struct group *gr_name;
205 
206 	/* validate the file descriptor before proceeding */
207 	if (ptsdev(fd) == NODEV)
208 		return (-1);
209 
210 	pto.pto_ruid = getuid();
211 
212 	gr_name = getgrnam(DEFAULT_TTY_GROUP);
213 	if (gr_name)
214 		pto.pto_rgid = gr_name->gr_gid;
215 	else
216 		pto.pto_rgid = getgid();
217 
218 	istr.ic_cmd = OWNERPT;
219 	istr.ic_len = sizeof (pt_own_t);
220 	istr.ic_timout = 0;
221 	istr.ic_dp = (char *)&pto;
222 
223 	if (ioctl(fd, I_STR, &istr) != 0) {
224 		errno = EACCES;
225 		return (-1);
226 	}
227 
228 	return (0);
229 }
230 
231 /*
232  * Send an ioctl down to the master device requesting the master/slave pair
233  * be assigned to the given zone.
234  */
235 int
zonept(int fd,zoneid_t zoneid)236 zonept(int fd, zoneid_t zoneid)
237 {
238 	struct strioctl istr;
239 
240 	istr.ic_cmd = ZONEPT;
241 	istr.ic_len = sizeof (zoneid);
242 	istr.ic_timout = 0;
243 	istr.ic_dp = (char *)&zoneid;
244 
245 	if (ioctl(fd, I_STR, &istr) != 0) {
246 		return (-1);
247 	}
248 	return (0);
249 }
250 
251 
252 /*
253  * added for SUSv3 standard
254  *
255  * Open a pseudo-terminal device.  External interface.
256  */
257 int
posix_openpt(int oflag)258 posix_openpt(int oflag)
259 {
260 	return (open("/dev/ptmx", oflag));
261 }
262