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Diffstat (limited to 'tools/debugserver/source/PseudoTerminal.cpp')
| -rw-r--r-- | tools/debugserver/source/PseudoTerminal.cpp | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/tools/debugserver/source/PseudoTerminal.cpp b/tools/debugserver/source/PseudoTerminal.cpp new file mode 100644 index 0000000000000..f1b505cabd4a2 --- /dev/null +++ b/tools/debugserver/source/PseudoTerminal.cpp @@ -0,0 +1,227 @@ +//===-- PseudoTerminal.cpp --------------------------------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// Created by Greg Clayton on 1/8/08. +// +//===----------------------------------------------------------------------===// + +#include "PseudoTerminal.h" +#include <stdlib.h> +#include <sys/ioctl.h> +#include <unistd.h> + +//---------------------------------------------------------------------- +// PseudoTerminal constructor +//---------------------------------------------------------------------- +PseudoTerminal::PseudoTerminal() : + m_master_fd(invalid_fd), + m_slave_fd(invalid_fd) +{ +} + +//---------------------------------------------------------------------- +// 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(); +} + +//---------------------------------------------------------------------- +// Close the master file descriptor if it is valid. +//---------------------------------------------------------------------- +void +PseudoTerminal::CloseMaster() +{ + 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::CloseSlave() +{ + 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 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; +} + +//---------------------------------------------------------------------- +// 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 PseudoTerminal::OpenFirstAvailableMaster()). +// The file descriptor is stored in the m_slave_fd member variable and +// can be accessed via the SlaveFD() or ReleaseSlaveFD() accessors. +// +// RETURNS: +// Zero when successful, non-zero indicating an error occurred. +//---------------------------------------------------------------------- +PseudoTerminal::Error +PseudoTerminal::OpenSlave(int oflag) +{ + CloseSlave(); + + // Open the master side of a pseudo terminal + const char *slave_name = SlaveName(); + + if (slave_name == NULL) + return err_ptsname_failed; + + m_slave_fd = ::open (slave_name, oflag); + + if (m_slave_fd < 0) + return err_open_slave_failed; + + return success; +} + + + +//---------------------------------------------------------------------- +// Get the name of the slave pseudo terminal. A master pseudo terminal +// should already be valid prior to calling this function (see +// PseudoTerminal::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::SlaveName() const +{ + if (m_master_fd < 0) + return NULL; + return ::ptsname (m_master_fd); +} + + +//---------------------------------------------------------------------- +// Fork a child process that 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 ReleaseMasterFD() +// or ReleaseSlaveFD() 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 +//---------------------------------------------------------------------- + +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; +} |