Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
       3             :  *
       4             :  *  Use of this source code is governed by a BSD-style license
       5             :  *  that can be found in the LICENSE file in the root of the source
       6             :  *  tree. An additional intellectual property rights grant can be found
       7             :  *  in the file PATENTS.  All contributing project authors may
       8             :  *  be found in the AUTHORS file in the root of the source tree.
       9             :  */
      10             : 
      11             : #include "webrtc/modules/desktop_capture/x11/x_error_trap.h"
      12             : 
      13             : #include <assert.h>
      14             : #include <limits>
      15             : 
      16             : namespace webrtc {
      17             : 
      18             : // static
      19           0 : Bool XErrorTrap::XServerErrorHandler(Display* display, xReply* rep,
      20             :                                      char* /* buf */, int /* len */,
      21             :                                      XPointer data) {
      22           0 :   XErrorTrap* self = reinterpret_cast<XErrorTrap*>(data);
      23             : 
      24           0 :   if (rep->generic.type != X_Error ||
      25             :       // Overflow-safe last_request_read <= last_ignored_request_ for skipping
      26             :       // async replies from requests before XErrorTrap was created.
      27           0 :       self->last_ignored_request_ - display->last_request_read <
      28           0 :       std::numeric_limits<unsigned long>::max() >> 1)
      29           0 :     return False;
      30             : 
      31           0 :   self->last_xserver_error_code_ = rep->error.errorCode;
      32           0 :   return True;
      33             : }
      34             : 
      35           0 : XErrorTrap::XErrorTrap(Display* display)
      36             :     : display_(display),
      37             :       last_xserver_error_code_(0),
      38           0 :       enabled_(true) {
      39             :   // Use async_handlers instead of XSetErrorHandler().  async_handlers can
      40             :   // remain in place and then be safely removed at the right time even if a
      41             :   // handler change happens concurrently on another thread.  async_handlers
      42             :   // are processed first and so can prevent errors reaching the global
      43             :   // XSetErrorHandler handler.  They also will not see errors from or affect
      44             :   // handling of errors on other Displays, which may be processed on other
      45             :   // threads.
      46           0 :   LockDisplay(display);
      47           0 :   async_handler_.next = display->async_handlers;
      48           0 :   async_handler_.handler = XServerErrorHandler;
      49           0 :   async_handler_.data = reinterpret_cast<XPointer>(this);
      50           0 :   display->async_handlers = &async_handler_;
      51           0 :   last_ignored_request_ = display->request;
      52           0 :   UnlockDisplay(display);
      53           0 : }
      54             : 
      55           0 : int XErrorTrap::GetLastErrorAndDisable() {
      56           0 :   assert(enabled_);
      57           0 :   enabled_ = false;
      58           0 :   LockDisplay(display_);
      59           0 :   DeqAsyncHandler(display_, &async_handler_);
      60           0 :   UnlockDisplay(display_);
      61           0 :   return last_xserver_error_code_;
      62             : }
      63             : 
      64           0 : XErrorTrap::~XErrorTrap() {
      65           0 :   if (enabled_)
      66           0 :     GetLastErrorAndDisable();
      67           0 : }
      68             : 
      69             : }  // namespace webrtc