1 //===-- Terminal.cpp ------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "lldb/Host/Terminal.h"
10 
11 #include "lldb/Host/Config.h"
12 #include "lldb/Host/PosixApi.h"
13 #include "llvm/ADT/STLExtras.h"
14 
15 #include <fcntl.h>
16 #include <signal.h>
17 
18 #if LLDB_ENABLE_TERMIOS
19 #include <termios.h>
20 #endif
21 
22 using namespace lldb_private;
23 
24 bool Terminal::IsATerminal() const { return m_fd >= 0 && ::isatty(m_fd); }
25 
26 bool Terminal::SetEcho(bool enabled) {
27   if (FileDescriptorIsValid()) {
28 #if LLDB_ENABLE_TERMIOS
29     if (IsATerminal()) {
30       struct termios fd_termios;
31       if (::tcgetattr(m_fd, &fd_termios) == 0) {
32         bool set_corectly = false;
33         if (enabled) {
34           if (fd_termios.c_lflag & ECHO)
35             set_corectly = true;
36           else
37             fd_termios.c_lflag |= ECHO;
38         } else {
39           if (fd_termios.c_lflag & ECHO)
40             fd_termios.c_lflag &= ~ECHO;
41           else
42             set_corectly = true;
43         }
44 
45         if (set_corectly)
46           return true;
47         return ::tcsetattr(m_fd, TCSANOW, &fd_termios) == 0;
48       }
49     }
50 #endif // #if LLDB_ENABLE_TERMIOS
51   }
52   return false;
53 }
54 
55 bool Terminal::SetCanonical(bool enabled) {
56   if (FileDescriptorIsValid()) {
57 #if LLDB_ENABLE_TERMIOS
58     if (IsATerminal()) {
59       struct termios fd_termios;
60       if (::tcgetattr(m_fd, &fd_termios) == 0) {
61         bool set_corectly = false;
62         if (enabled) {
63           if (fd_termios.c_lflag & ICANON)
64             set_corectly = true;
65           else
66             fd_termios.c_lflag |= ICANON;
67         } else {
68           if (fd_termios.c_lflag & ICANON)
69             fd_termios.c_lflag &= ~ICANON;
70           else
71             set_corectly = true;
72         }
73 
74         if (set_corectly)
75           return true;
76         return ::tcsetattr(m_fd, TCSANOW, &fd_termios) == 0;
77       }
78     }
79 #endif // #if LLDB_ENABLE_TERMIOS
80   }
81   return false;
82 }
83 
84 // Default constructor
85 TerminalState::TerminalState()
86     : m_tty(), m_tflags(-1),
87 #if LLDB_ENABLE_TERMIOS
88       m_termios_up(),
89 #endif
90       m_process_group(-1) {
91 }
92 
93 // Destructor
94 TerminalState::~TerminalState() {}
95 
96 void TerminalState::Clear() {
97   m_tty.Clear();
98   m_tflags = -1;
99 #if LLDB_ENABLE_TERMIOS
100   m_termios_up.reset();
101 #endif
102   m_process_group = -1;
103 }
104 
105 // Save the current state of the TTY for the file descriptor "fd" and if
106 // "save_process_group" is true, attempt to save the process group info for the
107 // TTY.
108 bool TerminalState::Save(int fd, bool save_process_group) {
109   m_tty.SetFileDescriptor(fd);
110   if (m_tty.IsATerminal()) {
111 #if LLDB_ENABLE_POSIX
112     m_tflags = ::fcntl(fd, F_GETFL, 0);
113 #endif
114 #if LLDB_ENABLE_TERMIOS
115     if (m_termios_up == nullptr)
116       m_termios_up.reset(new struct termios);
117     int err = ::tcgetattr(fd, m_termios_up.get());
118     if (err != 0)
119       m_termios_up.reset();
120 #endif // #if LLDB_ENABLE_TERMIOS
121 #if LLDB_ENABLE_POSIX
122     if (save_process_group)
123       m_process_group = ::tcgetpgrp(0);
124     else
125       m_process_group = -1;
126 #endif
127   } else {
128     m_tty.Clear();
129     m_tflags = -1;
130 #if LLDB_ENABLE_TERMIOS
131     m_termios_up.reset();
132 #endif
133     m_process_group = -1;
134   }
135   return IsValid();
136 }
137 
138 // Restore the state of the TTY using the cached values from a previous call to
139 // Save().
140 bool TerminalState::Restore() const {
141 #if LLDB_ENABLE_POSIX
142   if (IsValid()) {
143     const int fd = m_tty.GetFileDescriptor();
144     if (TFlagsIsValid())
145       fcntl(fd, F_SETFL, m_tflags);
146 
147 #if LLDB_ENABLE_TERMIOS
148     if (TTYStateIsValid())
149       tcsetattr(fd, TCSANOW, m_termios_up.get());
150 #endif // #if LLDB_ENABLE_TERMIOS
151 
152     if (ProcessGroupIsValid()) {
153       // Save the original signal handler.
154       void (*saved_sigttou_callback)(int) = nullptr;
155       saved_sigttou_callback = (void (*)(int))signal(SIGTTOU, SIG_IGN);
156       // Set the process group
157       tcsetpgrp(fd, m_process_group);
158       // Restore the original signal handler.
159       signal(SIGTTOU, saved_sigttou_callback);
160     }
161     return true;
162   }
163 #endif
164   return false;
165 }
166 
167 // Returns true if this object has valid saved TTY state settings that can be
168 // used to restore a previous state.
169 bool TerminalState::IsValid() const {
170   return m_tty.FileDescriptorIsValid() &&
171          (TFlagsIsValid() || TTYStateIsValid());
172 }
173 
174 // Returns true if m_tflags is valid
175 bool TerminalState::TFlagsIsValid() const { return m_tflags != -1; }
176 
177 // Returns true if m_ttystate is valid
178 bool TerminalState::TTYStateIsValid() const {
179 #if LLDB_ENABLE_TERMIOS
180   return m_termios_up != nullptr;
181 #else
182   return false;
183 #endif
184 }
185 
186 // Returns true if m_process_group is valid
187 bool TerminalState::ProcessGroupIsValid() const {
188   return static_cast<int32_t>(m_process_group) != -1;
189 }
190 
191 // Constructor
192 TerminalStateSwitcher::TerminalStateSwitcher() : m_currentState(UINT32_MAX) {}
193 
194 // Destructor
195 TerminalStateSwitcher::~TerminalStateSwitcher() {}
196 
197 // Returns the number of states that this switcher contains
198 uint32_t TerminalStateSwitcher::GetNumberOfStates() const {
199   return llvm::array_lengthof(m_ttystates);
200 }
201 
202 // Restore the state at index "idx".
203 //
204 // Returns true if the restore was successful, false otherwise.
205 bool TerminalStateSwitcher::Restore(uint32_t idx) const {
206   const uint32_t num_states = GetNumberOfStates();
207   if (idx >= num_states)
208     return false;
209 
210   // See if we already are in this state?
211   if (m_currentState < num_states && (idx == m_currentState) &&
212       m_ttystates[idx].IsValid())
213     return true;
214 
215   // Set the state to match the index passed in and only update the current
216   // state if there are no errors.
217   if (m_ttystates[idx].Restore()) {
218     m_currentState = idx;
219     return true;
220   }
221 
222   // We failed to set the state. The tty state was invalid or not initialized.
223   return false;
224 }
225 
226 // Save the state at index "idx" for file descriptor "fd" and save the process
227 // group if requested.
228 //
229 // Returns true if the restore was successful, false otherwise.
230 bool TerminalStateSwitcher::Save(uint32_t idx, int fd,
231                                  bool save_process_group) {
232   const uint32_t num_states = GetNumberOfStates();
233   if (idx < num_states)
234     return m_ttystates[idx].Save(fd, save_process_group);
235   return false;
236 }
237