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 <pty.h>
32#include <stdio.h>
33#include <stdlib.h>
34#include <sys/ioctl.h>
35#include <termios.h>
36#include <unistd.h>
37#include <utmp.h>
38
39#include "private/ThreadLocalBuffer.h"
40
41static ThreadLocalBuffer<char, 32> g_ptsname_tls_buffer;
42static ThreadLocalBuffer<char, 64> g_ttyname_tls_buffer;
43
44int getpt() {
45  return posix_openpt(O_RDWR|O_NOCTTY);
46}
47
48int grantpt(int) {
49  return 0;
50}
51
52int posix_openpt(int flags) {
53  return open("/dev/ptmx", flags);
54}
55
56char* ptsname(int fd) {
57  char* buf = g_ptsname_tls_buffer.get();
58  int error = ptsname_r(fd, buf, g_ptsname_tls_buffer.size());
59  return (error == 0) ? buf : NULL;
60}
61
62int ptsname_r(int fd, char* buf, size_t len) {
63  if (buf == NULL) {
64    errno = EINVAL;
65    return errno;
66  }
67
68  unsigned int pty_num;
69  if (ioctl(fd, TIOCGPTN, &pty_num) != 0) {
70    errno = ENOTTY;
71    return errno;
72  }
73
74  if (snprintf(buf, len, "/dev/pts/%u", pty_num) >= static_cast<int>(len)) {
75    errno = ERANGE;
76    return errno;
77  }
78
79  return 0;
80}
81
82char* ttyname(int fd) {
83  char* buf = g_ttyname_tls_buffer.get();
84  int error = ttyname_r(fd, buf, g_ttyname_tls_buffer.size());
85  return (error == 0) ? buf : NULL;
86}
87
88int ttyname_r(int fd, char* buf, size_t len) {
89  if (buf == NULL) {
90    errno = EINVAL;
91    return errno;
92  }
93
94  if (!isatty(fd)) {
95    return errno;
96  }
97
98  char path[64];
99  snprintf(path, sizeof(path), "/proc/self/fd/%d", fd);
100
101  ssize_t count = readlink(path, buf, len);
102  if (count == -1) {
103    return errno;
104  }
105  if (static_cast<size_t>(count) == len) {
106    errno = ERANGE;
107    return errno;
108  }
109  buf[count] = '\0';
110  return 0;
111}
112
113int unlockpt(int fd) {
114  int unlock = 0;
115  return ioctl(fd, TIOCSPTLCK, &unlock);
116}
117
118int openpty(int* master, int* slave, char* name, const termios* t, const winsize* ws) {
119  *master = getpt();
120  if (*master == -1) {
121    return -1;
122  }
123
124  if (grantpt(*master) == -1 || unlockpt(*master) == -1) {
125    close(*master);
126    return -1;
127  }
128
129  char buf[32];
130  if (name == NULL) {
131    name = buf;
132  }
133  if (ptsname_r(*master, name, sizeof(buf)) != 0) {
134    close(*master);
135    return -1;
136  }
137
138  *slave = open(name, O_RDWR|O_NOCTTY);
139  if (*slave == -1) {
140    close(*master);
141    return -1;
142  }
143
144  if (t != NULL) {
145    tcsetattr(*slave, TCSAFLUSH, t);
146  }
147  if (ws != NULL) {
148    ioctl(*slave, TIOCSWINSZ, ws);
149  }
150
151  return 0;
152}
153
154int forkpty(int* amaster, char* name, const termios* t, const winsize* ws) {
155  int master;
156  int slave;
157  if (openpty(&master, &slave, name, t, ws) == -1) {
158    return -1;
159  }
160
161  pid_t pid = fork();
162  if (pid == -1) {
163    close(master);
164    close(slave);
165    return -1;
166  }
167
168  if (pid == 0) {
169    // Child.
170    *amaster = -1;
171    close(master);
172    if (login_tty(slave) == -1) {
173      _exit(1);
174    }
175    return 0;
176  }
177
178  // Parent.
179  *amaster = master;
180  close(slave);
181  return pid;
182}
183
184int login_tty(int fd) {
185  setsid();
186
187  if (ioctl(fd, TIOCSCTTY, NULL) == -1) {
188    return -1;
189  }
190
191  dup2(fd, STDIN_FILENO);
192  dup2(fd, STDOUT_FILENO);
193  dup2(fd, STDERR_FILENO);
194  if (fd > STDERR_FILENO) {
195    close(fd);
196  }
197
198  return 0;
199}
200