340 lines
11 KiB
C++
340 lines
11 KiB
C++
//===-- PseudoTerminal.cpp --------------------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "lldb/Utility/PseudoTerminal.h"
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#if defined(TIOCSCTTY)
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#include <sys/ioctl.h>
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#endif
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using namespace lldb_utility;
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//----------------------------------------------------------------------
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// PseudoTerminal constructor
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//----------------------------------------------------------------------
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PseudoTerminal::PseudoTerminal () :
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m_master_fd(invalid_fd),
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m_slave_fd(invalid_fd)
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{
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}
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//----------------------------------------------------------------------
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// Destructor
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//
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// The destructor will close the master and slave file descriptors
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// if they are valid and ownwership has not been released using the
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// ReleaseMasterFileDescriptor() or the ReleaseSaveFileDescriptor()
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// member functions.
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//----------------------------------------------------------------------
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PseudoTerminal::~PseudoTerminal ()
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{
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CloseMasterFileDescriptor();
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CloseSlaveFileDescriptor();
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}
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//----------------------------------------------------------------------
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// Close the master file descriptor if it is valid.
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//----------------------------------------------------------------------
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void
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PseudoTerminal::CloseMasterFileDescriptor ()
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{
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if (m_master_fd >= 0)
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{
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::close (m_master_fd);
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m_master_fd = invalid_fd;
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}
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}
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//----------------------------------------------------------------------
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// Close the slave file descriptor if it is valid.
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//----------------------------------------------------------------------
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void
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PseudoTerminal::CloseSlaveFileDescriptor ()
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{
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if (m_slave_fd >= 0)
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{
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::close (m_slave_fd);
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m_slave_fd = invalid_fd;
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}
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}
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//----------------------------------------------------------------------
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// Open the first available pseudo terminal with OFLAG as the
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// permissions. The file descriptor is stored in this object and can
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// be accessed with the MasterFileDescriptor() accessor. The
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// ownership of the master file descriptor can be released using
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// the ReleaseMasterFileDescriptor() accessor. If this object has
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// a valid master files descriptor when its destructor is called, it
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// will close the master file descriptor, therefore clients must
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// call ReleaseMasterFileDescriptor() if they wish to use the master
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// file descriptor after this object is out of scope or destroyed.
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//
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// RETURNS:
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// Zero when successful, non-zero indicating an error occurred.
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//----------------------------------------------------------------------
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bool
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PseudoTerminal::OpenFirstAvailableMaster (int oflag, char *error_str, size_t error_len)
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{
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if (error_str)
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error_str[0] = '\0';
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// Open the master side of a pseudo terminal
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m_master_fd = ::posix_openpt (oflag);
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if (m_master_fd < 0)
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{
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if (error_str)
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::strerror_r (errno, error_str, error_len);
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return false;
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}
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// Grant access to the slave pseudo terminal
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if (::grantpt (m_master_fd) < 0)
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{
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if (error_str)
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::strerror_r (errno, error_str, error_len);
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CloseMasterFileDescriptor ();
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return false;
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}
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// Clear the lock flag on the slave pseudo terminal
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if (::unlockpt (m_master_fd) < 0)
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{
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if (error_str)
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::strerror_r (errno, error_str, error_len);
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CloseMasterFileDescriptor ();
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return false;
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}
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return true;
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}
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//----------------------------------------------------------------------
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// Open the slave pseudo terminal for the current master pseudo
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// terminal. A master pseudo terminal should already be valid prior to
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// calling this function (see OpenFirstAvailableMaster()).
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// The file descriptor is stored this object's member variables and can
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// be accessed via the GetSlaveFileDescriptor(), or released using the
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// ReleaseSlaveFileDescriptor() member function.
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//
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// RETURNS:
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// Zero when successful, non-zero indicating an error occurred.
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//----------------------------------------------------------------------
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bool
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PseudoTerminal::OpenSlave (int oflag, char *error_str, size_t error_len)
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{
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if (error_str)
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error_str[0] = '\0';
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CloseSlaveFileDescriptor();
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// Open the master side of a pseudo terminal
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const char *slave_name = GetSlaveName (error_str, error_len);
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if (slave_name == NULL)
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return false;
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m_slave_fd = ::open (slave_name, oflag);
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if (m_slave_fd < 0)
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{
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if (error_str)
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::strerror_r (errno, error_str, error_len);
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return false;
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}
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return true;
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}
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//----------------------------------------------------------------------
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// Get the name of the slave pseudo terminal. A master pseudo terminal
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// should already be valid prior to calling this function (see
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// OpenFirstAvailableMaster()).
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//
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// RETURNS:
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// NULL if no valid master pseudo terminal or if ptsname() fails.
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// The name of the slave pseudo terminal as a NULL terminated C string
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// that comes from static memory, so a copy of the string should be
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// made as subsequent calls can change this value.
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//----------------------------------------------------------------------
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const char*
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PseudoTerminal::GetSlaveName (char *error_str, size_t error_len) const
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{
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if (error_str)
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error_str[0] = '\0';
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if (m_master_fd < 0)
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{
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if (error_str)
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::snprintf (error_str, error_len, "%s", "master file descriptor is invalid");
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return NULL;
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}
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const char *slave_name = ::ptsname (m_master_fd);
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if (error_str && slave_name == NULL)
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::strerror_r (errno, error_str, error_len);
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return slave_name;
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}
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//----------------------------------------------------------------------
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// Fork a child process and have its stdio routed to a pseudo terminal.
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//
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// In the parent process when a valid pid is returned, the master file
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// descriptor can be used as a read/write access to stdio of the
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// child process.
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//
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// In the child process the stdin/stdout/stderr will already be routed
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// to the slave pseudo terminal and the master file descriptor will be
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// closed as it is no longer needed by the child process.
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//
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// This class will close the file descriptors for the master/slave
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// when the destructor is called, so be sure to call
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// ReleaseMasterFileDescriptor() or ReleaseSlaveFileDescriptor() if any
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// file descriptors are going to be used past the lifespan of this
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// object.
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//
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// RETURNS:
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// in the parent process: the pid of the child, or -1 if fork fails
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// in the child process: zero
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//----------------------------------------------------------------------
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lldb::pid_t
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PseudoTerminal::Fork (char *error_str, size_t error_len)
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{
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if (error_str)
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error_str[0] = '\0';
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pid_t pid = LLDB_INVALID_PROCESS_ID;
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if (OpenFirstAvailableMaster (O_RDWR, error_str, error_len))
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{
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// Successfully opened our master pseudo terminal
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pid = ::fork ();
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if (pid < 0)
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{
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// Fork failed
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if (error_str)
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::strerror_r (errno, error_str, error_len);
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}
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else if (pid == 0)
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{
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// Child Process
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::setsid();
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if (OpenSlave (O_RDWR, error_str, error_len))
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{
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// Successfully opened slave
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// We are done with the master in the child process so lets close it
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CloseMasterFileDescriptor ();
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#if defined(TIOCSCTTY)
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// Acquire the controlling terminal
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if (::ioctl (m_slave_fd, TIOCSCTTY, (char *)0) < 0)
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{
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if (error_str)
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::strerror_r (errno, error_str, error_len);
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}
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#endif
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// Duplicate all stdio file descriptors to the slave pseudo terminal
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if (::dup2 (m_slave_fd, STDIN_FILENO) != STDIN_FILENO)
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{
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if (error_str && !error_str[0])
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::strerror_r (errno, error_str, error_len);
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}
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if (::dup2 (m_slave_fd, STDOUT_FILENO) != STDOUT_FILENO)
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{
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if (error_str && !error_str[0])
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::strerror_r (errno, error_str, error_len);
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}
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if (::dup2 (m_slave_fd, STDERR_FILENO) != STDERR_FILENO)
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{
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if (error_str && !error_str[0])
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::strerror_r (errno, error_str, error_len);
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}
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}
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}
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else
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{
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// Parent Process
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// Do nothing and let the pid get returned!
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}
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}
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return pid;
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}
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//----------------------------------------------------------------------
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// The master file descriptor accessor. This object retains ownership
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// of the master file descriptor when this accessor is used. Use
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// ReleaseMasterFileDescriptor() if you wish this object to release
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// ownership of the master file descriptor.
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//
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// Returns the master file descriptor, or -1 if the master file
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// descriptor is not currently valid.
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//----------------------------------------------------------------------
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int
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PseudoTerminal::GetMasterFileDescriptor () const
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{
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return m_master_fd;
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}
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//----------------------------------------------------------------------
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// The slave file descriptor accessor.
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//
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// Returns the slave file descriptor, or -1 if the slave file
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// descriptor is not currently valid.
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//----------------------------------------------------------------------
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int
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PseudoTerminal::GetSlaveFileDescriptor () const
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{
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return m_slave_fd;
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}
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//----------------------------------------------------------------------
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// Release ownership of the master pseudo terminal file descriptor
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// without closing it. The destructor for this class will close the
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// master file descriptor if the ownership isn't released using this
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// call and the master file descriptor has been opened.
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//----------------------------------------------------------------------
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int
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PseudoTerminal::ReleaseMasterFileDescriptor ()
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{
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// Release ownership of the master pseudo terminal file
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// descriptor without closing it. (the destructor for this
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// class will close it otherwise!)
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int fd = m_master_fd;
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m_master_fd = invalid_fd;
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return fd;
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}
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//----------------------------------------------------------------------
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// Release ownership of the slave pseudo terminal file descriptor
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// without closing it. The destructor for this class will close the
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// slave file descriptor if the ownership isn't released using this
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// call and the slave file descriptor has been opened.
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//----------------------------------------------------------------------
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int
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PseudoTerminal::ReleaseSlaveFileDescriptor ()
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{
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// Release ownership of the slave pseudo terminal file
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// descriptor without closing it (the destructor for this
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// class will close it otherwise!)
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int fd = m_slave_fd;
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m_slave_fd = invalid_fd;
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return fd;
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}
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