pty.cpp revision 2ea0a58e01c1ed6db1da9dd0314ee053f5a32026 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <errno.h>
30#include <fcntl.h>
31#include <stdio.h>
32#include <stdlib.h>
33#include <sys/ioctl.h>
34#include <termios.h>
35#include <unistd.h>
36
37int getpt(void) {
38  return posix_openpt(O_RDWR|O_NOCTTY);
39}
40
41int grantpt(int) {
42  return 0;
43}
44
45int posix_openpt(int flags) {
46  return open("/dev/ptmx", flags);
47}
48
49char* ptsname(int fd) {
50  static char buf[64];
51  return ptsname_r(fd, buf, sizeof(buf)) == 0 ? buf : NULL;
52}
53
54int ptsname_r(int fd, char* buf, size_t len) {
55  if (buf == NULL) {
56    errno = EINVAL;
57    return errno;
58  }
59
60  unsigned int pty_num;
61  if (ioctl(fd, TIOCGPTN, &pty_num) != 0) {
62    errno = ENOTTY;
63    return errno;
64  }
65
66  if (snprintf(buf, len, "/dev/pts/%u", pty_num) >= static_cast<int>(len)) {
67    errno = ERANGE;
68    return errno;
69  }
70
71  return 0;
72}
73
74char* ttyname(int fd) {
75  static char buf[64];
76  return ttyname_r(fd, buf, sizeof(buf)) == 0 ? buf : NULL;
77}
78
79int ttyname_r(int fd, char* buf, size_t len) {
80  if (buf == NULL) {
81    errno = EINVAL;
82    return errno;
83  }
84
85  if (!isatty(fd)) {
86    return errno;
87  }
88
89  char path[64];
90  snprintf(path, sizeof(path), "/proc/self/fd/%d", fd);
91
92  ssize_t count = readlink(path, buf, len);
93  if (count == -1) {
94    return errno;
95  }
96  if (static_cast<size_t>(count) == len) {
97    errno = ERANGE;
98    return errno;
99  }
100  buf[count] = '\0';
101  return 0;
102}
103
104int unlockpt(int fd) {
105  int unlock = 0;
106  return ioctl(fd, TIOCSPTLCK, &unlock);
107}
108