1/* Copyright (C) 1998-2021 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 <https://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#include <shlib-compat.h>
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 multiplexer/terminal pair and set terminal attributes
83 according to TERMP and WINP. Return handles for both ends in
84 *PPTMX and *PTERMINAL, and return the name of the terminal end in NAME. */
85int
86__openpty (int *pptmx, int *pterminal, 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 ptmx, ret = -1, terminal = -1;
96
97 *buf = '\0';
98
99 ptmx = __getpt ();
100 if (ptmx == -1)
101 return -1;
102
103 if (grantpt (ptmx))
104 goto on_error;
105
106 if (unlockpt (ptmx))
107 goto on_error;
108
109#ifdef TIOCGPTPEER
110 /* Try to allocate terminal fd solely based on PTMX fd first. */
111 terminal = __ioctl (ptmx, TIOCGPTPEER, O_RDWR | O_NOCTTY);
112#endif
113 if (terminal == -1)
114 {
115 /* Fallback to path-based terminal fd allocation in case kernel doesn't
116 * support TIOCGPTPEER.
117 */
118 if (pts_name (ptmx, &buf, sizeof (_buf)))
119 goto on_error;
120
121 terminal = __open64 (buf, O_RDWR | O_NOCTTY);
122 if (terminal == -1)
123 goto on_error;
124 }
125
126 /* XXX Should we ignore errors here? */
127 if (termp)
128 tcsetattr (terminal, TCSAFLUSH, termp);
129#ifdef TIOCSWINSZ
130 if (winp)
131 __ioctl (terminal, TIOCSWINSZ, winp);
132#endif
133
134 *pptmx = ptmx;
135 *pterminal = terminal;
136 if (name != NULL)
137 {
138 if (*buf == '\0')
139 if (pts_name (ptmx, &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 (ptmx);
150
151 if (terminal != -1)
152 __close (terminal);
153 }
154
155 if (buf != _buf)
156 free (buf);
157
158 return ret;
159}
160versioned_symbol (libc, __openpty, openpty, GLIBC_2_34);
161libc_hidden_ver (__openpty, openpty)
162
163#if OTHER_SHLIB_COMPAT (libutil, GLIBC_2_0, GLIBC_2_34)
164compat_symbol (libutil, __openpty, openpty, GLIBC_2_0);
165#endif
166