1/* Copyright (C) 1998-2018 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include <errno.h>
20#include <fcntl.h>
21#include <limits.h>
22#include <pty.h>
23#include <stdlib.h>
24#include <string.h>
25#include <termios.h>
26#include <unistd.h>
27#include <sys/types.h>
28
29
30/* Return the result of ptsname_r in the buffer pointed to by PTS,
31 which should be of length BUF_LEN. If it is too long to fit in
32 this buffer, a sufficiently long buffer is allocated using malloc,
33 and returned in PTS. 0 is returned upon success, -1 otherwise. */
34static int
35pts_name (int fd, char **pts, size_t buf_len)
36{
37 int rv;
38 char *buf = *pts;
39
40 for (;;)
41 {
42 char *new_buf;
43
44 if (buf_len)
45 {
46 rv = ptsname_r (fd, buf, buf_len);
47
48 if (rv != 0 || memchr (buf, '\0', buf_len))
49 /* We either got an error, or we succeeded and the
50 returned name fit in the buffer. */
51 break;
52
53 /* Try again with a longer buffer. */
54 buf_len += buf_len; /* Double it */
55 }
56 else
57 /* No initial buffer; start out by mallocing one. */
58 buf_len = 128; /* First time guess. */
59
60 if (buf != *pts)
61 /* We've already malloced another buffer at least once. */
62 new_buf = realloc (buf, buf_len);
63 else
64 new_buf = malloc (buf_len);
65 if (! new_buf)
66 {
67 rv = -1;
68 __set_errno (ENOMEM);
69 break;
70 }
71 buf = new_buf;
72 }
73
74 if (rv == 0)
75 *pts = buf; /* Return buffer to the user. */
76 else if (buf != *pts)
77 free (buf); /* Free what we malloced when returning an error. */
78
79 return rv;
80}
81
82/* Create pseudo tty master slave pair and set terminal attributes
83 according to TERMP and WINP. Return handles for both ends in
84 AMASTER and ASLAVE, and return the name of the slave end in NAME. */
85int
86openpty (int *amaster, int *aslave, char *name,
87 const struct termios *termp, const struct winsize *winp)
88{
89#ifdef PATH_MAX
90 char _buf[PATH_MAX];
91#else
92 char _buf[512];
93#endif
94 char *buf = _buf;
95 int master, ret = -1, slave = -1;
96
97 *buf = '\0';
98
99 master = getpt ();
100 if (master == -1)
101 return -1;
102
103 if (grantpt (master))
104 goto on_error;
105
106 if (unlockpt (master))
107 goto on_error;
108
109#ifdef TIOCGPTPEER
110 /* Try to allocate slave fd solely based on master fd first. */
111 slave = ioctl (master, TIOCGPTPEER, O_RDWR | O_NOCTTY);
112#endif
113 if (slave == -1)
114 {
115 /* Fallback to path-based slave fd allocation in case kernel doesn't
116 * support TIOCGPTPEER.
117 */
118 if (pts_name (master, &buf, sizeof (_buf)))
119 goto on_error;
120
121 slave = open (buf, O_RDWR | O_NOCTTY);
122 if (slave == -1)
123 goto on_error;
124 }
125
126 /* XXX Should we ignore errors here? */
127 if (termp)
128 tcsetattr (slave, TCSAFLUSH, termp);
129#ifdef TIOCSWINSZ
130 if (winp)
131 ioctl (slave, TIOCSWINSZ, winp);
132#endif
133
134 *amaster = master;
135 *aslave = slave;
136 if (name != NULL)
137 {
138 if (*buf == '\0')
139 if (pts_name (master, &buf, sizeof (_buf)))
140 goto on_error;
141
142 strcpy (name, buf);
143 }
144
145 ret = 0;
146
147 on_error:
148 if (ret == -1) {
149 close (master);
150
151 if (slave != -1)
152 close (slave);
153 }
154
155 if (buf != _buf)
156 free (buf);
157
158 return ret;
159}
160libutil_hidden_def (openpty)
161