lldb/tools/debugserver/source/TTYState.cpp

   1 //===-- TTYState.cpp --------------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 //  Created by Greg Clayton on 3/26/07.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "TTYState.h"
  14 #include <fcntl.h>
  15 #include <sys/signal.h>
  16 #include <unistd.h>
  17
  18 TTYState::TTYState()
  19     : m_fd(-1), m_tflags(-1), m_ttystateErr(-1), m_processGroup(-1) {}
  20
  21 TTYState::~TTYState() = default;
  22
  23 bool TTYState::GetTTYState(int fd, bool saveProcessGroup) {
  24   if (fd >= 0 && ::isatty(fd)) {
  25     m_fd = fd;
  26     m_tflags = fcntl(fd, F_GETFL, 0);
  27     m_ttystateErr = tcgetattr(fd, &m_ttystate);
  28     if (saveProcessGroup)
  29       m_processGroup = tcgetpgrp(0);
  30     else
  31       m_processGroup = -1;
  32   } else {
  33     m_fd = -1;
  34     m_tflags = -1;
  35     m_ttystateErr = -1;
  36     m_processGroup = -1;
  37   }
  38   return m_ttystateErr == 0;
  39 }
  40
  41 bool TTYState::SetTTYState() const {
  42   if (IsValid()) {
  43     if (TFlagsValid())
  44       fcntl(m_fd, F_SETFL, m_tflags);
  45
  46     if (TTYStateValid())
  47       tcsetattr(m_fd, TCSANOW, &m_ttystate);
  48
  49     if (ProcessGroupValid()) {
  50       // Save the original signal handler.
  51       void (*saved_sigttou_callback)(int) = NULL;
  52       saved_sigttou_callback = (void (*)(int))signal(SIGTTOU, SIG_IGN);
  53       // Set the process group
  54       tcsetpgrp(m_fd, m_processGroup);
  55       // Restore the original signal handler.
  56       signal(SIGTTOU, saved_sigttou_callback);
  57     }
  58     return true;
  59   }
  60   return false;
  61 }
  62
  63 TTYStateSwitcher::TTYStateSwitcher() : m_currentState(~0) {}
  64
  65 TTYStateSwitcher::~TTYStateSwitcher() = default;
  66
  67 bool TTYStateSwitcher::GetState(uint32_t idx, int fd, bool saveProcessGroup) {
  68   if (ValidStateIndex(idx))
  69     return m_ttystates[idx].GetTTYState(fd, saveProcessGroup);
  70   return false;
  71 }
  72
  73 bool TTYStateSwitcher::SetState(uint32_t idx) const {
  74   if (!ValidStateIndex(idx))
  75     return false;
  76
  77   // See if we already are in this state?
  78   if (ValidStateIndex(m_currentState) && (idx == m_currentState) &&
  79       m_ttystates[idx].IsValid())
  80     return true;
  81
  82   // Set the state to match the index passed in and only update the
  83   // current state if there are no errors.
  84   if (m_ttystates[idx].SetTTYState()) {
  85     m_currentState = idx;
  86     return true;
  87   }
  88
  89   // We failed to set the state. The tty state was invalid or not
  90   // initialized.
  91   return false;
  92 }