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 <csignal>
16 #include <fcntl.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()
87 #if LLDB_ENABLE_TERMIOS
88       ,
89       m_termios_up()
90 #endif
91 {
92 }
93 
94 // Destructor
95 TerminalState::~TerminalState() = default;
96 
97 void TerminalState::Clear() {
98   m_tty.Clear();
99   m_tflags = -1;
100 #if LLDB_ENABLE_TERMIOS
101   m_termios_up.reset();
102 #endif
103   m_process_group = -1;
104 }
105 
106 // Save the current state of the TTY for the file descriptor "fd" and if
107 // "save_process_group" is true, attempt to save the process group info for the
108 // TTY.
109 bool TerminalState::Save(int fd, bool save_process_group) {
110   m_tty.SetFileDescriptor(fd);
111   if (m_tty.IsATerminal()) {
112 #if LLDB_ENABLE_POSIX
113     m_tflags = ::fcntl(fd, F_GETFL, 0);
114 #endif
115 #if LLDB_ENABLE_TERMIOS
116     if (m_termios_up == nullptr)
117       m_termios_up.reset(new struct termios);
118     int err = ::tcgetattr(fd, m_termios_up.get());
119     if (err != 0)
120       m_termios_up.reset();
121 #endif // #if LLDB_ENABLE_TERMIOS
122 #if LLDB_ENABLE_POSIX
123     if (save_process_group)
124       m_process_group = ::tcgetpgrp(0);
125     else
126       m_process_group = -1;
127 #endif
128   } else {
129     m_tty.Clear();
130     m_tflags = -1;
131 #if LLDB_ENABLE_TERMIOS
132     m_termios_up.reset();
133 #endif
134     m_process_group = -1;
135   }
136   return IsValid();
137 }
138 
139 // Restore the state of the TTY using the cached values from a previous call to
140 // Save().
141 bool TerminalState::Restore() const {
142 #if LLDB_ENABLE_POSIX
143   if (IsValid()) {
144     const int fd = m_tty.GetFileDescriptor();
145     if (TFlagsIsValid())
146       fcntl(fd, F_SETFL, m_tflags);
147 
148 #if LLDB_ENABLE_TERMIOS
149     if (TTYStateIsValid())
150       tcsetattr(fd, TCSANOW, m_termios_up.get());
151 #endif // #if LLDB_ENABLE_TERMIOS
152 
153     if (ProcessGroupIsValid()) {
154       // Save the original signal handler.
155       void (*saved_sigttou_callback)(int) = nullptr;
156       saved_sigttou_callback = (void (*)(int))signal(SIGTTOU, SIG_IGN);
157       // Set the process group
158       tcsetpgrp(fd, m_process_group);
159       // Restore the original signal handler.
160       signal(SIGTTOU, saved_sigttou_callback);
161     }
162     return true;
163   }
164 #endif
165   return false;
166 }
167 
168 // Returns true if this object has valid saved TTY state settings that can be
169 // used to restore a previous state.
170 bool TerminalState::IsValid() const {
171   return m_tty.FileDescriptorIsValid() &&
172          (TFlagsIsValid() || TTYStateIsValid());
173 }
174 
175 // Returns true if m_tflags is valid
176 bool TerminalState::TFlagsIsValid() const { return m_tflags != -1; }
177 
178 // Returns true if m_ttystate is valid
179 bool TerminalState::TTYStateIsValid() const {
180 #if LLDB_ENABLE_TERMIOS
181   return m_termios_up != nullptr;
182 #else
183   return false;
184 #endif
185 }
186 
187 // Returns true if m_process_group is valid
188 bool TerminalState::ProcessGroupIsValid() const {
189   return static_cast<int32_t>(m_process_group) != -1;
190 }
191 
192 // Constructor
193 TerminalStateSwitcher::TerminalStateSwitcher() = default;
194 
195 // Destructor
196 TerminalStateSwitcher::~TerminalStateSwitcher() = default;
197 
198 // Returns the number of states that this switcher contains
199 uint32_t TerminalStateSwitcher::GetNumberOfStates() const {
200   return llvm::array_lengthof(m_ttystates);
201 }
202 
203 // Restore the state at index "idx".
204 //
205 // Returns true if the restore was successful, false otherwise.
206 bool TerminalStateSwitcher::Restore(uint32_t idx) const {
207   const uint32_t num_states = GetNumberOfStates();
208   if (idx >= num_states)
209     return false;
210 
211   // See if we already are in this state?
212   if (m_currentState < num_states && (idx == m_currentState) &&
213       m_ttystates[idx].IsValid())
214     return true;
215 
216   // Set the state to match the index passed in and only update the current
217   // state if there are no errors.
218   if (m_ttystates[idx].Restore()) {
219     m_currentState = idx;
220     return true;
221   }
222 
223   // We failed to set the state. The tty state was invalid or not initialized.
224   return false;
225 }
226 
227 // Save the state at index "idx" for file descriptor "fd" and save the process
228 // group if requested.
229 //
230 // Returns true if the restore was successful, false otherwise.
231 bool TerminalStateSwitcher::Save(uint32_t idx, int fd,
232                                  bool save_process_group) {
233   const uint32_t num_states = GetNumberOfStates();
234   if (idx < num_states)
235     return m_ttystates[idx].Save(fd, save_process_group);
236   return false;
237 }
238