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/*
* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "modules/desktop_capture/linux/x11/x_error_trap.h"
#include <stddef.h>
#include <limits>
#include "rtc_base/checks.h"
namespace webrtc {
Bool XErrorTrap::XServerErrorHandler(Display* display, xReply* rep,
char* /* buf */, int /* len */,
XPointer data) {
XErrorTrap* self = reinterpret_cast<XErrorTrap*>(data);
if (rep->generic.type != X_Error ||
// Overflow-safe last_request_read <= last_ignored_request_ for skipping
// async replies from requests before XErrorTrap was created.
self->last_ignored_request_ - display->last_request_read <
std::numeric_limits<unsigned long>::max() >> 1)
return False;
self->last_xserver_error_code_ = rep->error.errorCode;
return True;
}
XErrorTrap::XErrorTrap(Display* display)
: display_(display),
last_xserver_error_code_(0),
enabled_(true) {
// Use async_handlers instead of XSetErrorHandler(). async_handlers can
// remain in place and then be safely removed at the right time even if a
// handler change happens concurrently on another thread. async_handlers
// are processed first and so can prevent errors reaching the global
// XSetErrorHandler handler. They also will not see errors from or affect
// handling of errors on other Displays, which may be processed on other
// threads.
LockDisplay(display);
async_handler_.next = display->async_handlers;
async_handler_.handler = XServerErrorHandler;
async_handler_.data = reinterpret_cast<XPointer>(this);
display->async_handlers = &async_handler_;
last_ignored_request_ = display->request;
UnlockDisplay(display);
}
int XErrorTrap::GetLastErrorAndDisable() {
assert(enabled_);
enabled_ = false;
LockDisplay(display_);
DeqAsyncHandler(display_, &async_handler_);
UnlockDisplay(display_);
return last_xserver_error_code_;
}
XErrorTrap::~XErrorTrap() {
if (enabled_)
GetLastErrorAndDisable();
}
} // namespace webrtc
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