1 //===-- Terminal.h ----------------------------------------------*- C++ -*-===//
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 #ifndef LLDB_HOST_TERMINAL_H
10 #define LLDB_HOST_TERMINAL_H
11 #if defined(__cplusplus)
12 
13 #include "lldb/Host/Config.h"
14 #include "lldb/lldb-private.h"
15 
16 struct termios;
17 
18 namespace lldb_private {
19 
20 class Terminal {
21 public:
22   Terminal(int fd = -1) : m_fd(fd) {}
23 
24   ~Terminal() = default;
25 
26   bool IsATerminal() const;
27 
28   int GetFileDescriptor() const { return m_fd; }
29 
30   void SetFileDescriptor(int fd) { m_fd = fd; }
31 
32   bool FileDescriptorIsValid() const { return m_fd != -1; }
33 
34   void Clear() { m_fd = -1; }
35 
36   bool SetEcho(bool enabled);
37 
38   bool SetCanonical(bool enabled);
39 
40 protected:
41   int m_fd; // This may or may not be a terminal file descriptor
42 };
43 
44 /// \class State Terminal.h "lldb/Host/Terminal.h"
45 /// A terminal state saving/restoring class.
46 ///
47 /// This class can be used to remember the terminal state for a file
48 /// descriptor and later restore that state as it originally was.
49 class TerminalState {
50 public:
51   /// Default constructor
52   TerminalState();
53 
54   /// Destructor
55   ~TerminalState();
56 
57   /// Save the TTY state for \a fd.
58   ///
59   /// Save the current state of the TTY for the file descriptor "fd" and if
60   /// "save_process_group" is true, attempt to save the process group info for
61   /// the TTY.
62   ///
63   /// \param[in] fd
64   ///     The file descriptor to save the state of.
65   ///
66   /// \param[in] save_process_group
67   ///     If \b true, save the process group settings, else do not
68   ///     save the process group settings for a TTY.
69   ///
70   /// \return
71   ///     Returns \b true if \a fd describes a TTY and if the state
72   ///     was able to be saved, \b false otherwise.
73   bool Save(int fd, bool save_process_group);
74 
75   /// Restore the TTY state to the cached state.
76   ///
77   /// Restore the state of the TTY using the cached values from a previous
78   /// call to TerminalState::Save(int,bool).
79   ///
80   /// \return
81   ///     Returns \b true if the TTY state was successfully restored,
82   ///     \b false otherwise.
83   bool Restore() const;
84 
85   /// Test for valid cached TTY state information.
86   ///
87   /// \return
88   ///     Returns \b true if this object has valid saved TTY state
89   ///     settings that can be used to restore a previous state,
90   ///     \b false otherwise.
91   bool IsValid() const;
92 
93   void Clear();
94 
95 protected:
96   /// Test if tflags is valid.
97   ///
98   /// \return
99   ///     Returns \b true if \a m_tflags is valid and can be restored,
100   ///     \b false otherwise.
101   bool TFlagsIsValid() const;
102 
103   /// Test if ttystate is valid.
104   ///
105   /// \return
106   ///     Returns \b true if \a m_ttystate is valid and can be
107   ///     restored, \b false otherwise.
108   bool TTYStateIsValid() const;
109 
110   /// Test if the process group information is valid.
111   ///
112   /// \return
113   ///     Returns \b true if \a m_process_group is valid and can be
114   ///     restored, \b false otherwise.
115   bool ProcessGroupIsValid() const;
116 
117   // Member variables
118   Terminal m_tty; ///< A terminal
119   int m_tflags = -1; ///< Cached tflags information.
120 #if LLDB_ENABLE_TERMIOS
121   std::unique_ptr<struct termios>
122       m_termios_up; ///< Cached terminal state information.
123 #endif
124   lldb::pid_t m_process_group = -1; ///< Cached process group information.
125 };
126 
127 /// \class TerminalStateSwitcher Terminal.h "lldb/Host/Terminal.h"
128 /// A TTY state switching class.
129 ///
130 /// This class can be used to remember 2 TTY states for a given file
131 /// descriptor and switch between the two states.
132 class TerminalStateSwitcher {
133 public:
134   /// Constructor
135   TerminalStateSwitcher();
136 
137   /// Destructor
138   ~TerminalStateSwitcher();
139 
140   /// Get the number of possible states to save.
141   ///
142   /// \return
143   ///     The number of states that this TTY switcher object contains.
144   uint32_t GetNumberOfStates() const;
145 
146   /// Restore the TTY state for state at index \a idx.
147   ///
148   /// \return
149   ///     Returns \b true if the TTY state was successfully restored,
150   ///     \b false otherwise.
151   bool Restore(uint32_t idx) const;
152 
153   /// Save the TTY state information for the state at index \a idx. The TTY
154   /// state is saved for the file descriptor \a fd and the process group
155   /// information will also be saved if requested by \a save_process_group.
156   ///
157   /// \param[in] idx
158   ///     The index into the state array where the state should be
159   ///     saved.
160   ///
161   /// \param[in] fd
162   ///     The file descriptor for which to save the settings.
163   ///
164   /// \param[in] save_process_group
165   ///     If \b true, save the process group information for the TTY.
166   ///
167   /// \return
168   ///     Returns \b true if the save was successful, \b false
169   ///     otherwise.
170   bool Save(uint32_t idx, int fd, bool save_process_group);
171 
172 protected:
173   // Member variables
174   mutable uint32_t m_currentState =
175       UINT32_MAX; ///< The currently active TTY state index.
176   TerminalState
177       m_ttystates[2]; ///< The array of TTY states that holds saved TTY info.
178 };
179 
180 } // namespace lldb_private
181 
182 #endif // #if defined(__cplusplus)
183 #endif // LLDB_HOST_TERMINAL_H
184