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File indexing completed on 2026-05-10 08:42:49
0001 //===-- PseudoTerminal.h ----------------------------------------*- C++ -*-===// 0002 // 0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 0004 // See https://llvm.org/LICENSE.txt for license information. 0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 0006 // 0007 //===----------------------------------------------------------------------===// 0008 0009 #ifndef LLDB_HOST_PSEUDOTERMINAL_H 0010 #define LLDB_HOST_PSEUDOTERMINAL_H 0011 0012 #include "lldb/lldb-defines.h" 0013 #include "llvm/Support/Error.h" 0014 #include <fcntl.h> 0015 #include <string> 0016 0017 namespace lldb_private { 0018 0019 /// \class PseudoTerminal PseudoTerminal.h "lldb/Host/PseudoTerminal.h" 0020 /// A pseudo terminal helper class. 0021 /// 0022 /// The pseudo terminal class abstracts the use of pseudo terminals on the 0023 /// host system. 0024 class PseudoTerminal { 0025 public: 0026 enum { 0027 invalid_fd = -1 ///< Invalid file descriptor value 0028 }; 0029 0030 /// Default constructor 0031 /// 0032 /// Constructs this object with invalid primary and secondary file 0033 /// descriptors. 0034 PseudoTerminal(); 0035 0036 /// Destructor 0037 /// 0038 /// The destructor will close the primary and secondary file descriptors if 0039 /// they are valid and ownership has not been released using one of: @li 0040 /// PseudoTerminal::ReleasePrimaryFileDescriptor() @li 0041 /// PseudoTerminal::ReleaseSaveFileDescriptor() 0042 ~PseudoTerminal(); 0043 0044 /// Close the primary file descriptor if it is valid. 0045 void ClosePrimaryFileDescriptor(); 0046 0047 /// Close the secondary file descriptor if it is valid. 0048 void CloseSecondaryFileDescriptor(); 0049 0050 /// Fork a child process that uses pseudo terminals for its stdio. 0051 /// 0052 /// In the parent process, a call to this function results in a pid being 0053 /// returned. If the pid is valid, the primary file descriptor can be used 0054 /// for read/write access to stdio of the child process. 0055 /// 0056 /// In the child process the stdin/stdout/stderr will already be routed to 0057 /// the secondary pseudo terminal and the primary file descriptor will be 0058 /// closed as it is no longer needed by the child process. 0059 /// 0060 /// This class will close the file descriptors for the primary/secondary when 0061 /// the destructor is called. The file handles can be released using either: 0062 /// @li PseudoTerminal::ReleasePrimaryFileDescriptor() @li 0063 /// PseudoTerminal::ReleaseSaveFileDescriptor() 0064 /// 0065 /// \return 0066 /// \b Parent process: a child process ID that is greater 0067 /// than zero, or an error if the fork fails. 0068 /// \b Child process: zero. 0069 llvm::Expected<lldb::pid_t> Fork(); 0070 0071 /// The primary file descriptor accessor. 0072 /// 0073 /// This object retains ownership of the primary file descriptor when this 0074 /// accessor is used. Users can call the member function 0075 /// PseudoTerminal::ReleasePrimaryFileDescriptor() if this object should 0076 /// release ownership of the secondary file descriptor. 0077 /// 0078 /// \return 0079 /// The primary file descriptor, or PseudoTerminal::invalid_fd 0080 /// if the primary file descriptor is not currently valid. 0081 /// 0082 /// \see PseudoTerminal::ReleasePrimaryFileDescriptor() 0083 int GetPrimaryFileDescriptor() const; 0084 0085 /// The secondary file descriptor accessor. 0086 /// 0087 /// This object retains ownership of the secondary file descriptor when this 0088 /// accessor is used. Users can call the member function 0089 /// PseudoTerminal::ReleaseSecondaryFileDescriptor() if this object should 0090 /// release ownership of the secondary file descriptor. 0091 /// 0092 /// \return 0093 /// The secondary file descriptor, or PseudoTerminal::invalid_fd 0094 /// if the secondary file descriptor is not currently valid. 0095 /// 0096 /// \see PseudoTerminal::ReleaseSecondaryFileDescriptor() 0097 int GetSecondaryFileDescriptor() const; 0098 0099 /// Get the name of the secondary pseudo terminal. 0100 /// 0101 /// A primary pseudo terminal should already be valid prior to 0102 /// calling this function. 0103 /// 0104 /// \return 0105 /// The name of the secondary pseudo terminal. 0106 /// 0107 /// \see PseudoTerminal::OpenFirstAvailablePrimary() 0108 std::string GetSecondaryName() const; 0109 0110 /// Open the first available pseudo terminal. 0111 /// 0112 /// Opens the first available pseudo terminal with \a oflag as the 0113 /// permissions. The opened primary file descriptor is stored in this object 0114 /// and can be accessed by calling the 0115 /// PseudoTerminal::GetPrimaryFileDescriptor() accessor. Clients can call the 0116 /// PseudoTerminal::ReleasePrimaryFileDescriptor() accessor function if they 0117 /// wish to use the primary file descriptor beyond the lifespan of this 0118 /// object. 0119 /// 0120 /// If this object still has a valid primary file descriptor when its 0121 /// destructor is called, it will close it. 0122 /// 0123 /// \param[in] oflag 0124 /// Flags to use when calling \c posix_openpt(\a oflag). 0125 /// A value of "O_RDWR|O_NOCTTY" is suggested. 0126 /// 0127 /// \see PseudoTerminal::GetPrimaryFileDescriptor() @see 0128 /// PseudoTerminal::ReleasePrimaryFileDescriptor() 0129 llvm::Error OpenFirstAvailablePrimary(int oflag); 0130 0131 /// Open the secondary for the current primary pseudo terminal. 0132 /// 0133 /// A primary pseudo terminal should already be valid prior to 0134 /// calling this function. The opened secondary file descriptor is stored in 0135 /// this object and can be accessed by calling the 0136 /// PseudoTerminal::GetSecondaryFileDescriptor() accessor. Clients can call 0137 /// the PseudoTerminal::ReleaseSecondaryFileDescriptor() accessor function if 0138 /// they wish to use the secondary file descriptor beyond the lifespan of this 0139 /// object. 0140 /// 0141 /// If this object still has a valid secondary file descriptor when its 0142 /// destructor is called, it will close it. 0143 /// 0144 /// \param[in] oflag 0145 /// Flags to use when calling \c open(\a oflag). 0146 /// 0147 /// \see PseudoTerminal::OpenFirstAvailablePrimary() @see 0148 /// PseudoTerminal::GetSecondaryFileDescriptor() @see 0149 /// PseudoTerminal::ReleaseSecondaryFileDescriptor() 0150 llvm::Error OpenSecondary(int oflag); 0151 0152 /// Release the primary file descriptor. 0153 /// 0154 /// Releases ownership of the primary pseudo terminal file descriptor without 0155 /// closing it. The destructor for this class will close the primary file 0156 /// descriptor if the ownership isn't released using this call and the 0157 /// primary file descriptor has been opened. 0158 /// 0159 /// \return 0160 /// The primary file descriptor, or PseudoTerminal::invalid_fd 0161 /// if the mast file descriptor is not currently valid. 0162 int ReleasePrimaryFileDescriptor(); 0163 0164 /// Release the secondary file descriptor. 0165 /// 0166 /// Release ownership of the secondary pseudo terminal file descriptor without 0167 /// closing it. The destructor for this class will close the secondary file 0168 /// descriptor if the ownership isn't released using this call and the 0169 /// secondary file descriptor has been opened. 0170 /// 0171 /// \return 0172 /// The secondary file descriptor, or PseudoTerminal::invalid_fd 0173 /// if the secondary file descriptor is not currently valid. 0174 int ReleaseSecondaryFileDescriptor(); 0175 0176 protected: 0177 // Member variables 0178 int m_primary_fd = invalid_fd; ///< The file descriptor for the primary. 0179 int m_secondary_fd = invalid_fd; ///< The file descriptor for the secondary. 0180 0181 private: 0182 PseudoTerminal(const PseudoTerminal &) = delete; 0183 const PseudoTerminal &operator=(const PseudoTerminal &) = delete; 0184 }; 0185 0186 } // namespace lldb_private 0187 0188 #endif // LLDB_HOST_PSEUDOTERMINAL_H
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