lldb/source/Utility/PseudoTerminal.cpp - toolchain/llvm-project - Gitiles

 //===-- PseudoTerminal.cpp --------------------------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//

 #include "lldb/Utility/PseudoTerminal.h"

 #include <errno.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 #if defined(TIOCSCTTY)
 #include <sys/ioctl.h>
 #endif

 #ifdef _WIN32
 #include "lldb/Host/windows/win32.h"
 // empty functions
 int posix_openpt(int flag) { return 0; }

 int strerror_r(int errnum, char *buf, size_t buflen) { return 0; }

 int unlockpt(int fd) { return 0; }
 int grantpt(int fd) { return 0; }
 char *ptsname(int fd) { return 0; }

 pid_t fork(void) { return 0; }
 pid_t setsid(void) { return 0; }
 #endif

 using namespace lldb_utility;

 //----------------------------------------------------------------------
 // PseudoTerminal constructor
 //----------------------------------------------------------------------
 PseudoTerminal::PseudoTerminal () :
     m_master_fd(invalid_fd),
     m_slave_fd(invalid_fd)
 {
 }

 //----------------------------------------------------------------------
 // Destructor
 //
 // The destructor will close the master and slave file descriptors
 // if they are valid and ownwership has not been released using the
 // ReleaseMasterFileDescriptor() or the ReleaseSaveFileDescriptor()
 // member functions.
 //----------------------------------------------------------------------
 PseudoTerminal::~PseudoTerminal ()
 {
     CloseMasterFileDescriptor();
     CloseSlaveFileDescriptor();
 }

 //----------------------------------------------------------------------
 // Close the master file descriptor if it is valid.
 //----------------------------------------------------------------------
 void
 PseudoTerminal::CloseMasterFileDescriptor ()
 {
     if (m_master_fd >= 0)
     {
         ::close (m_master_fd);
         m_master_fd = invalid_fd;
     }
 }

 //----------------------------------------------------------------------
 // Close the slave file descriptor if it is valid.
 //----------------------------------------------------------------------
 void
 PseudoTerminal::CloseSlaveFileDescriptor ()
 {
     if (m_slave_fd >= 0)
     {
         ::close (m_slave_fd);
         m_slave_fd = invalid_fd;
     }
 }

 //----------------------------------------------------------------------
 // Open the first available pseudo terminal with OFLAG as the
 // permissions. The file descriptor is stored in this object and can
 // be accessed with the MasterFileDescriptor() accessor. The
 // ownership of the master file descriptor can be released using
 // the ReleaseMasterFileDescriptor() accessor. If this object has
 // a valid master files descriptor when its destructor is called, it
 // will close the master file descriptor, therefore clients must
 // call ReleaseMasterFileDescriptor() if they wish to use the master
 // file descriptor after this object is out of scope or destroyed.
 //
 // RETURNS:
 //  Zero when successful, non-zero indicating an error occurred.
 //----------------------------------------------------------------------
 bool
 PseudoTerminal::OpenFirstAvailableMaster (int oflag, char *error_str, size_t error_len)
 {
     if (error_str)
         error_str[0] = '\0';

     // Open the master side of a pseudo terminal
     m_master_fd = ::posix_openpt (oflag);
     if (m_master_fd < 0)
     {
         if (error_str)
             ::strerror_r (errno, error_str, error_len);
         return false;
     }

     // Grant access to the slave pseudo terminal
     if (::grantpt (m_master_fd) < 0)
     {
         if (error_str)
             ::strerror_r (errno, error_str, error_len);
         CloseMasterFileDescriptor ();
         return false;
     }

     // Clear the lock flag on the slave pseudo terminal
     if (::unlockpt (m_master_fd) < 0)
     {
         if (error_str)
             ::strerror_r (errno, error_str, error_len);
         CloseMasterFileDescriptor ();
         return false;
     }

     return true;
 }

 //----------------------------------------------------------------------
 // Open the slave pseudo terminal for the current master pseudo
 // terminal. A master pseudo terminal should already be valid prior to
 // calling this function (see OpenFirstAvailableMaster()).
 // The file descriptor is stored this object's member variables and can
 // be accessed via the GetSlaveFileDescriptor(), or released using the
 // ReleaseSlaveFileDescriptor() member function.
 //
 // RETURNS:
 //  Zero when successful, non-zero indicating an error occurred.
 //----------------------------------------------------------------------
 bool
 PseudoTerminal::OpenSlave (int oflag, char *error_str, size_t error_len)
 {
     if (error_str)
         error_str[0] = '\0';

     CloseSlaveFileDescriptor();

     // Open the master side of a pseudo terminal
     const char *slave_name = GetSlaveName (error_str, error_len);

     if (slave_name == nullptr)
         return false;

     m_slave_fd = ::open (slave_name, oflag);

     if (m_slave_fd < 0)
     {
         if (error_str)
             ::strerror_r (errno, error_str, error_len);
         return false;
     }

     return true;
 }


 //----------------------------------------------------------------------
 // Get the name of the slave pseudo terminal. A master pseudo terminal
 // should already be valid prior to calling this function (see
 // OpenFirstAvailableMaster()).
 //
 // RETURNS:
 //  NULL if no valid master pseudo terminal or if ptsname() fails.
 //  The name of the slave pseudo terminal as a NULL terminated C string
 //  that comes from static memory, so a copy of the string should be
 //  made as subsequent calls can change this value.
 //----------------------------------------------------------------------
 const char*
 PseudoTerminal::GetSlaveName (char *error_str, size_t error_len) const
 {
     if (error_str)
         error_str[0] = '\0';

     if (m_master_fd < 0)
     {
         if (error_str)
             ::snprintf (error_str, error_len, "%s", "master file descriptor is invalid");
         return nullptr;
     }
     const char *slave_name = ::ptsname (m_master_fd);

     if (error_str && slave_name == nullptr)
         ::strerror_r (errno, error_str, error_len);

     return slave_name;
 }


 //----------------------------------------------------------------------
 // Fork a child process and have its stdio routed to a pseudo terminal.
 //
 // In the parent process when a valid pid is returned, the master file
 // descriptor can be used as a read/write access to stdio of the
 // child process.
 //
 // In the child process the stdin/stdout/stderr will already be routed
 // to the slave pseudo terminal and the master file descriptor will be
 // closed as it is no longer needed by the child process.
 //
 // This class will close the file descriptors for the master/slave
 // when the destructor is called, so be sure to call
 // ReleaseMasterFileDescriptor() or ReleaseSlaveFileDescriptor() if any
 // file descriptors are going to be used past the lifespan of this
 // object.
 //
 // RETURNS:
 //  in the parent process: the pid of the child, or -1 if fork fails
 //  in the child process: zero
 //----------------------------------------------------------------------
 lldb::pid_t
 PseudoTerminal::Fork (char *error_str, size_t error_len)
 {
     if (error_str)
         error_str[0] = '\0';

     pid_t pid = LLDB_INVALID_PROCESS_ID;
     if (OpenFirstAvailableMaster (O_RDWR, error_str, error_len))
     {
         // Successfully opened our master pseudo terminal

         pid = ::fork ();
         if (pid < 0)
         {
             // Fork failed
             if (error_str)
             ::strerror_r (errno, error_str, error_len);
         }
         else if (pid == 0)
         {
             // Child Process
             ::setsid();

             if (OpenSlave (O_RDWR, error_str, error_len))
             {
                 // Successfully opened slave
                 // We are done with the master in the child process so lets close it
                 CloseMasterFileDescriptor ();

 #if defined(TIOCSCTTY)
                 // Acquire the controlling terminal
                 if (::ioctl (m_slave_fd, TIOCSCTTY, (char *)0) < 0)
                 {
                     if (error_str)
                         ::strerror_r (errno, error_str, error_len);
                 }
 #endif
                 // Duplicate all stdio file descriptors to the slave pseudo terminal
                 if (::dup2 (m_slave_fd, STDIN_FILENO) != STDIN_FILENO)
                 {
                     if (error_str && !error_str[0])
                         ::strerror_r (errno, error_str, error_len);
                 }

                 if (::dup2 (m_slave_fd, STDOUT_FILENO) != STDOUT_FILENO)
                 {
                     if (error_str && !error_str[0])
                         ::strerror_r (errno, error_str, error_len);
                 }

                 if (::dup2 (m_slave_fd, STDERR_FILENO) != STDERR_FILENO)
                 {
                     if (error_str && !error_str[0])
                         ::strerror_r (errno, error_str, error_len);
                 }
             }
         }
         else
         {
             // Parent Process
             // Do nothing and let the pid get returned!
         }
     }
     return pid;
 }

 //----------------------------------------------------------------------
 // The master file descriptor accessor. This object retains ownership
 // of the master file descriptor when this accessor is used. Use
 // ReleaseMasterFileDescriptor() if you wish this object to release
 // ownership of the master file descriptor.
 //
 // Returns the master file descriptor, or -1 if the master file
 // descriptor is not currently valid.
 //----------------------------------------------------------------------
 int
 PseudoTerminal::GetMasterFileDescriptor () const
 {
     return m_master_fd;
 }

 //----------------------------------------------------------------------
 // The slave file descriptor accessor.
 //
 // Returns the slave file descriptor, or -1 if the slave file
 // descriptor is not currently valid.
 //----------------------------------------------------------------------
 int
 PseudoTerminal::GetSlaveFileDescriptor () const
 {
     return m_slave_fd;
 }

 //----------------------------------------------------------------------
 // Release ownership of the master pseudo terminal file descriptor
 // without closing it. The destructor for this class will close the
 // master file descriptor if the ownership isn't released using this
 // call and the master file descriptor has been opened.
 //----------------------------------------------------------------------
 int
 PseudoTerminal::ReleaseMasterFileDescriptor ()
 {
     // Release ownership of the master pseudo terminal file
     // descriptor without closing it. (the destructor for this
     // class will close it otherwise!)
     int fd = m_master_fd;
     m_master_fd = invalid_fd;
     return fd;
 }

 //----------------------------------------------------------------------
 // Release ownership of the slave pseudo terminal file descriptor
 // without closing it. The destructor for this class will close the
 // slave file descriptor if the ownership isn't released using this
 // call and the slave file descriptor has been opened.
 //----------------------------------------------------------------------
 int
 PseudoTerminal::ReleaseSlaveFileDescriptor ()
 {
     // Release ownership of the slave pseudo terminal file
     // descriptor without closing it (the destructor for this
     // class will close it otherwise!)
     int fd = m_slave_fd;
     m_slave_fd = invalid_fd;
     return fd;
 }
	//===-- PseudoTerminal.cpp --------------------------------------- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//

	#include "lldb/Utility/PseudoTerminal.h"

	#include <errno.h>
	#include <stdlib.h>
	#include <string.h>
	#include <stdio.h>
	#if defined(TIOCSCTTY)
	#include <sys/ioctl.h>
	#endif

	#ifdef _WIN32
	#include "lldb/Host/windows/win32.h"
	// empty functions
	int posix_openpt(int flag) { return 0; }

	int strerror_r(int errnum, char *buf, size_t buflen) { return 0; }

	int unlockpt(int fd) { return 0; }
	int grantpt(int fd) { return 0; }
	char *ptsname(int fd) { return 0; }

	pid_t fork(void) { return 0; }
	pid_t setsid(void) { return 0; }
	#endif

	using namespace lldb_utility;

	//----------------------------------------------------------------------
	// PseudoTerminal constructor
	//----------------------------------------------------------------------
	PseudoTerminal::PseudoTerminal () :
	m_master_fd(invalid_fd),
	m_slave_fd(invalid_fd)
	{
	}

	//----------------------------------------------------------------------
	// Destructor
	//
	// The destructor will close the master and slave file descriptors
	// if they are valid and ownwership has not been released using the
	// ReleaseMasterFileDescriptor() or the ReleaseSaveFileDescriptor()
	// member functions.
	//----------------------------------------------------------------------
	PseudoTerminal::~PseudoTerminal ()
	{
	CloseMasterFileDescriptor();
	CloseSlaveFileDescriptor();
	}

	//----------------------------------------------------------------------
	// Close the master file descriptor if it is valid.
	//----------------------------------------------------------------------
	void
	PseudoTerminal::CloseMasterFileDescriptor ()
	{
	if (m_master_fd >= 0)
	{
	::close (m_master_fd);
	m_master_fd = invalid_fd;
	}
	}

	//----------------------------------------------------------------------
	// Close the slave file descriptor if it is valid.
	//----------------------------------------------------------------------
	void
	PseudoTerminal::CloseSlaveFileDescriptor ()
	{
	if (m_slave_fd >= 0)
	{
	::close (m_slave_fd);
	m_slave_fd = invalid_fd;
	}
	}

	//----------------------------------------------------------------------
	// Open the first available pseudo terminal with OFLAG as the
	// permissions. The file descriptor is stored in this object and can
	// be accessed with the MasterFileDescriptor() accessor. The
	// ownership of the master file descriptor can be released using
	// the ReleaseMasterFileDescriptor() accessor. If this object has
	// a valid master files descriptor when its destructor is called, it
	// will close the master file descriptor, therefore clients must
	// call ReleaseMasterFileDescriptor() if they wish to use the master
	// file descriptor after this object is out of scope or destroyed.
	//
	// RETURNS:
	// Zero when successful, non-zero indicating an error occurred.
	//----------------------------------------------------------------------
	bool
	PseudoTerminal::OpenFirstAvailableMaster (int oflag, char *error_str, size_t error_len)
	{
	if (error_str)
	error_str[0] = '\0';

	// Open the master side of a pseudo terminal
	m_master_fd = ::posix_openpt (oflag);
	if (m_master_fd < 0)
	{
	if (error_str)
	::strerror_r (errno, error_str, error_len);
	return false;
	}

	// Grant access to the slave pseudo terminal
	if (::grantpt (m_master_fd) < 0)
	{
	if (error_str)
	::strerror_r (errno, error_str, error_len);
	CloseMasterFileDescriptor ();
	return false;
	}

	// Clear the lock flag on the slave pseudo terminal
	if (::unlockpt (m_master_fd) < 0)
	{
	if (error_str)
	::strerror_r (errno, error_str, error_len);
	CloseMasterFileDescriptor ();
	return false;
	}

	return true;
	}

	//----------------------------------------------------------------------
	// Open the slave pseudo terminal for the current master pseudo
	// terminal. A master pseudo terminal should already be valid prior to
	// calling this function (see OpenFirstAvailableMaster()).
	// The file descriptor is stored this object's member variables and can
	// be accessed via the GetSlaveFileDescriptor(), or released using the
	// ReleaseSlaveFileDescriptor() member function.
	//
	// RETURNS:
	// Zero when successful, non-zero indicating an error occurred.
	//----------------------------------------------------------------------
	bool
	PseudoTerminal::OpenSlave (int oflag, char *error_str, size_t error_len)
	{
	if (error_str)
	error_str[0] = '\0';

	CloseSlaveFileDescriptor();

	// Open the master side of a pseudo terminal
	const char *slave_name = GetSlaveName (error_str, error_len);

	if (slave_name == nullptr)
	return false;

	m_slave_fd = ::open (slave_name, oflag);

	if (m_slave_fd < 0)
	{
	if (error_str)
	::strerror_r (errno, error_str, error_len);
	return false;
	}

	return true;
	}



	//----------------------------------------------------------------------
	// Get the name of the slave pseudo terminal. A master pseudo terminal
	// should already be valid prior to calling this function (see
	// OpenFirstAvailableMaster()).
	//
	// RETURNS:
	// NULL if no valid master pseudo terminal or if ptsname() fails.
	// The name of the slave pseudo terminal as a NULL terminated C string
	// that comes from static memory, so a copy of the string should be
	// made as subsequent calls can change this value.
	//----------------------------------------------------------------------
	const char*
	PseudoTerminal::GetSlaveName (char *error_str, size_t error_len) const
	{
	if (error_str)
	error_str[0] = '\0';

	if (m_master_fd < 0)
	{
	if (error_str)
	::snprintf (error_str, error_len, "%s", "master file descriptor is invalid");
	return nullptr;
	}
	const char *slave_name = ::ptsname (m_master_fd);

	if (error_str && slave_name == nullptr)
	::strerror_r (errno, error_str, error_len);

	return slave_name;
	}


	//----------------------------------------------------------------------
	// Fork a child process and have its stdio routed to a pseudo terminal.
	//
	// In the parent process when a valid pid is returned, the master file
	// descriptor can be used as a read/write access to stdio of the
	// child process.
	//
	// In the child process the stdin/stdout/stderr will already be routed
	// to the slave pseudo terminal and the master file descriptor will be
	// closed as it is no longer needed by the child process.
	//
	// This class will close the file descriptors for the master/slave
	// when the destructor is called, so be sure to call
	// ReleaseMasterFileDescriptor() or ReleaseSlaveFileDescriptor() if any
	// file descriptors are going to be used past the lifespan of this
	// object.
	//
	// RETURNS:
	// in the parent process: the pid of the child, or -1 if fork fails
	// in the child process: zero
	//----------------------------------------------------------------------
	lldb::pid_t
	PseudoTerminal::Fork (char *error_str, size_t error_len)
	{
	if (error_str)
	error_str[0] = '\0';

	pid_t pid = LLDB_INVALID_PROCESS_ID;
	if (OpenFirstAvailableMaster (O_RDWR, error_str, error_len))
	{
	// Successfully opened our master pseudo terminal

	pid = ::fork ();
	if (pid < 0)
	{
	// Fork failed
	if (error_str)
	::strerror_r (errno, error_str, error_len);
	}
	else if (pid == 0)
	{
	// Child Process
	::setsid();

	if (OpenSlave (O_RDWR, error_str, error_len))
	{
	// Successfully opened slave
	// We are done with the master in the child process so lets close it
	CloseMasterFileDescriptor ();

	#if defined(TIOCSCTTY)
	// Acquire the controlling terminal
	if (::ioctl (m_slave_fd, TIOCSCTTY, (char *)0) < 0)
	{
	if (error_str)
	::strerror_r (errno, error_str, error_len);
	}
	#endif
	// Duplicate all stdio file descriptors to the slave pseudo terminal
	if (::dup2 (m_slave_fd, STDIN_FILENO) != STDIN_FILENO)
	{
	if (error_str && !error_str[0])
	::strerror_r (errno, error_str, error_len);
	}

	if (::dup2 (m_slave_fd, STDOUT_FILENO) != STDOUT_FILENO)
	{
	if (error_str && !error_str[0])
	::strerror_r (errno, error_str, error_len);
	}

	if (::dup2 (m_slave_fd, STDERR_FILENO) != STDERR_FILENO)
	{
	if (error_str && !error_str[0])
	::strerror_r (errno, error_str, error_len);
	}
	}
	}
	else
	{
	// Parent Process
	// Do nothing and let the pid get returned!
	}
	}
	return pid;
	}

	//----------------------------------------------------------------------
	// The master file descriptor accessor. This object retains ownership
	// of the master file descriptor when this accessor is used. Use
	// ReleaseMasterFileDescriptor() if you wish this object to release
	// ownership of the master file descriptor.
	//
	// Returns the master file descriptor, or -1 if the master file
	// descriptor is not currently valid.
	//----------------------------------------------------------------------
	int
	PseudoTerminal::GetMasterFileDescriptor () const
	{
	return m_master_fd;
	}

	//----------------------------------------------------------------------
	// The slave file descriptor accessor.
	//
	// Returns the slave file descriptor, or -1 if the slave file
	// descriptor is not currently valid.
	//----------------------------------------------------------------------
	int
	PseudoTerminal::GetSlaveFileDescriptor () const
	{
	return m_slave_fd;
	}

	//----------------------------------------------------------------------
	// Release ownership of the master pseudo terminal file descriptor
	// without closing it. The destructor for this class will close the
	// master file descriptor if the ownership isn't released using this
	// call and the master file descriptor has been opened.
	//----------------------------------------------------------------------
	int
	PseudoTerminal::ReleaseMasterFileDescriptor ()
	{
	// Release ownership of the master pseudo terminal file
	// descriptor without closing it. (the destructor for this
	// class will close it otherwise!)
	int fd = m_master_fd;
	m_master_fd = invalid_fd;
	return fd;
	}

	//----------------------------------------------------------------------
	// Release ownership of the slave pseudo terminal file descriptor
	// without closing it. The destructor for this class will close the
	// slave file descriptor if the ownership isn't released using this
	// call and the slave file descriptor has been opened.
	//----------------------------------------------------------------------
	int
	PseudoTerminal::ReleaseSlaveFileDescriptor ()
	{
	// Release ownership of the slave pseudo terminal file
	// descriptor without closing it (the destructor for this
	// class will close it otherwise!)
	int fd = m_slave_fd;
	m_slave_fd = invalid_fd;
	return fd;
	}