//----------------------------------------------------------------------
// Open the first available pseudo terminal with OFLAG as the
// permissions. The file descriptor is store in the m_master_fd member
// variable and can be accessed via the MasterFD() or ReleaseMasterFD()
// accessors.
//
// Suggested value for oflag is O_RDWR|O_NOCTTY
//
// RETURNS:
// Zero when successful, non-zero indicating an error occurred.
//----------------------------------------------------------------------
PseudoTerminal::Error
PseudoTerminal::OpenFirstAvailableMaster(int oflag)
{
// Open the master side of a pseudo terminal
m_master_fd = ::posix_openpt (oflag);
if (m_master_fd < 0)
{
return err_posix_openpt_failed;
}
// Grant access to the slave pseudo terminal
if (::grantpt (m_master_fd) < 0)
{
CloseMaster();
return err_grantpt_failed;
}
// Clear the lock flag on the slave pseudo terminal
if (::unlockpt (m_master_fd) < 0)
{
CloseMaster();
return err_unlockpt_failed;
}
return success;
}
pid_t
PseudoTerminal::Fork(PseudoTerminal::Error& error)
{
pid_t pid = invalid_pid;
error = OpenFirstAvailableMaster (O_RDWR|O_NOCTTY);
if (error == 0)
{
// Successfully opened our master pseudo terminal
pid = ::fork ();
if (pid < 0)
{
// Fork failed
error = err_fork_failed;
}
else if (pid == 0)
{
// Child Process
::setsid();
error = OpenSlave (O_RDWR);
if (error == 0)
{
// Successfully opened slave
// We are done with the master in the child process so lets close it
CloseMaster ();
#if defined (TIOCSCTTY)
// Acquire the controlling terminal
if (::ioctl (m_slave_fd, TIOCSCTTY, (char *)0) < 0)
error = err_failed_to_acquire_controlling_terminal;
#endif
// Duplicate all stdio file descriptors to the slave pseudo terminal
if (::dup2 (m_slave_fd, STDIN_FILENO) != STDIN_FILENO)
error = error ? error : err_dup2_failed_on_stdin;
if (::dup2 (m_slave_fd, STDOUT_FILENO) != STDOUT_FILENO)
error = error ? error : err_dup2_failed_on_stdout;
if (::dup2 (m_slave_fd, STDERR_FILENO) != STDERR_FILENO)
error = error ? error : err_dup2_failed_on_stderr;
}
}
else
{
// Parent Process
// Do nothing and let the pid get returned!
}
}
return pid;
}
// Destructor
// The master and slave file descriptors will get closed if they are
// valid. Call the ReleaseMasterFD()/ReleaseSlaveFD() member functions
// to release any file descriptors that are needed beyond the lifespan
// of this object.
PseudoTerminal::~PseudoTerminal() {
CloseMaster();
CloseSlave();
}