1/* Copyright (C) 1998-2017 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, slave;
96
97 master = getpt ();
98 if (master == -1)
99 return -1;
100
101 if (grantpt (master))
102 goto fail;
103
104 if (unlockpt (master))
105 goto fail;
106
107 if (pts_name (master, &buf, sizeof (_buf)))
108 goto fail;
109
110 slave = open (buf, O_RDWR | O_NOCTTY);
111 if (slave == -1)
112 {
113 if (buf != _buf)
114 free (buf);
115
116 goto fail;
117 }
118
119 /* XXX Should we ignore errors here? */
120 if (termp)
121 tcsetattr (slave, TCSAFLUSH, termp);
122#ifdef TIOCSWINSZ
123 if (winp)
124 ioctl (slave, TIOCSWINSZ, winp);
125#endif
126
127 *amaster = master;
128 *aslave = slave;
129 if (name != NULL)
130 strcpy (name, buf);
131
132 if (buf != _buf)
133 free (buf);
134 return 0;
135
136 fail:
137 close (master);
138 return -1;
139}
140libutil_hidden_def (openpty)
141