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//===-- PseudoTerminal.h ----------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLDB_HOST_PSEUDOTERMINAL_H
#define LLDB_HOST_PSEUDOTERMINAL_H
#include "lldb/lldb-defines.h"
#include "llvm/Support/Error.h"
#include <fcntl.h>
#include <string>
namespace lldb_private {
/// \class PseudoTerminal PseudoTerminal.h "lldb/Host/PseudoTerminal.h"
/// A pseudo terminal helper class.
///
/// The pseudo terminal class abstracts the use of pseudo terminals on the
/// host system.
class PseudoTerminal {
public:
enum {
invalid_fd = -1 ///< Invalid file descriptor value
};
/// Default constructor
///
/// Constructs this object with invalid primary and secondary file
/// descriptors.
PseudoTerminal();
/// Destructor
///
/// The destructor will close the primary and secondary file descriptors if
/// they are valid and ownership has not been released using one of: @li
/// PseudoTerminal::ReleasePrimaryFileDescriptor() @li
/// PseudoTerminal::ReleaseSaveFileDescriptor()
~PseudoTerminal();
/// Close the primary file descriptor if it is valid.
void ClosePrimaryFileDescriptor();
/// Close the secondary file descriptor if it is valid.
void CloseSecondaryFileDescriptor();
/// Fork a child process that uses pseudo terminals for its stdio.
///
/// In the parent process, a call to this function results in a pid being
/// returned. If the pid is valid, the primary file descriptor can be used
/// for read/write access to stdio of the child process.
///
/// In the child process the stdin/stdout/stderr will already be routed to
/// the secondary pseudo terminal and the primary file descriptor will be
/// closed as it is no longer needed by the child process.
///
/// This class will close the file descriptors for the primary/secondary when
/// the destructor is called. The file handles can be released using either:
/// @li PseudoTerminal::ReleasePrimaryFileDescriptor() @li
/// PseudoTerminal::ReleaseSaveFileDescriptor()
///
/// \return
/// \b Parent process: a child process ID that is greater
/// than zero, or an error if the fork fails.
/// \b Child process: zero.
llvm::Expected<lldb::pid_t> Fork();
/// The primary file descriptor accessor.
///
/// This object retains ownership of the primary file descriptor when this
/// accessor is used. Users can call the member function
/// PseudoTerminal::ReleasePrimaryFileDescriptor() if this object should
/// release ownership of the secondary file descriptor.
///
/// \return
/// The primary file descriptor, or PseudoTerminal::invalid_fd
/// if the primary file descriptor is not currently valid.
///
/// \see PseudoTerminal::ReleasePrimaryFileDescriptor()
int GetPrimaryFileDescriptor() const;
/// The secondary file descriptor accessor.
///
/// This object retains ownership of the secondary file descriptor when this
/// accessor is used. Users can call the member function
/// PseudoTerminal::ReleaseSecondaryFileDescriptor() if this object should
/// release ownership of the secondary file descriptor.
///
/// \return
/// The secondary file descriptor, or PseudoTerminal::invalid_fd
/// if the secondary file descriptor is not currently valid.
///
/// \see PseudoTerminal::ReleaseSecondaryFileDescriptor()
int GetSecondaryFileDescriptor() const;
/// Get the name of the secondary pseudo terminal.
///
/// A primary pseudo terminal should already be valid prior to
/// calling this function.
///
/// \return
/// The name of the secondary pseudo terminal.
///
/// \see PseudoTerminal::OpenFirstAvailablePrimary()
std::string GetSecondaryName() const;
/// Open the first available pseudo terminal.
///
/// Opens the first available pseudo terminal with \a oflag as the
/// permissions. The opened primary file descriptor is stored in this object
/// and can be accessed by calling the
/// PseudoTerminal::GetPrimaryFileDescriptor() accessor. Clients can call the
/// PseudoTerminal::ReleasePrimaryFileDescriptor() accessor function if they
/// wish to use the primary file descriptor beyond the lifespan of this
/// object.
///
/// If this object still has a valid primary file descriptor when its
/// destructor is called, it will close it.
///
/// \param[in] oflag
/// Flags to use when calling \c posix_openpt(\a oflag).
/// A value of "O_RDWR|O_NOCTTY" is suggested.
///
/// \see PseudoTerminal::GetPrimaryFileDescriptor() @see
/// PseudoTerminal::ReleasePrimaryFileDescriptor()
llvm::Error OpenFirstAvailablePrimary(int oflag);
/// Open the secondary for the current primary pseudo terminal.
///
/// A primary pseudo terminal should already be valid prior to
/// calling this function. The opened secondary file descriptor is stored in
/// this object and can be accessed by calling the
/// PseudoTerminal::GetSecondaryFileDescriptor() accessor. Clients can call
/// the PseudoTerminal::ReleaseSecondaryFileDescriptor() accessor function if
/// they wish to use the secondary file descriptor beyond the lifespan of this
/// object.
///
/// If this object still has a valid secondary file descriptor when its
/// destructor is called, it will close it.
///
/// \param[in] oflag
/// Flags to use when calling \c open(\a oflag).
///
/// \see PseudoTerminal::OpenFirstAvailablePrimary() @see
/// PseudoTerminal::GetSecondaryFileDescriptor() @see
/// PseudoTerminal::ReleaseSecondaryFileDescriptor()
llvm::Error OpenSecondary(int oflag);
/// Release the primary file descriptor.
///
/// Releases ownership of the primary pseudo terminal file descriptor without
/// closing it. The destructor for this class will close the primary file
/// descriptor if the ownership isn't released using this call and the
/// primary file descriptor has been opened.
///
/// \return
/// The primary file descriptor, or PseudoTerminal::invalid_fd
/// if the mast file descriptor is not currently valid.
int ReleasePrimaryFileDescriptor();
/// Release the secondary file descriptor.
///
/// Release ownership of the secondary pseudo terminal file descriptor without
/// closing it. The destructor for this class will close the secondary file
/// descriptor if the ownership isn't released using this call and the
/// secondary file descriptor has been opened.
///
/// \return
/// The secondary file descriptor, or PseudoTerminal::invalid_fd
/// if the secondary file descriptor is not currently valid.
int ReleaseSecondaryFileDescriptor();
protected:
// Member variables
int m_primary_fd; ///< The file descriptor for the primary.
int m_secondary_fd; ///< The file descriptor for the secondary.
private:
PseudoTerminal(const PseudoTerminal &) = delete;
const PseudoTerminal &operator=(const PseudoTerminal &) = delete;
};
} // namespace lldb_private
#endif // LLDB_HOST_PSEUDOTERMINAL_H
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