ui/base/x/selection_requestor.cc

// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/base/x/selection_requestor.h"

#include <algorithm>

#include "base/memory/ref_counted_memory.h"
#include "base/run_loop.h"
#include "ui/base/x/selection_owner.h"
#include "ui/base/x/selection_utils.h"
#include "ui/base/x/x11_util.h"
#include "ui/events/platform/platform_event_source.h"
#include "ui/events/platform/x11/x11_event_source.h"
#include "ui/gfx/x/x11_atom_cache.h"
#include "ui/gfx/x/x11_types.h"
#include "ui/gfx/x/xproto.h"

namespace ui {

namespace {

const char kChromeSelection[] = "CHROME_SELECTION";

// The period of |abort_timer_|. Arbitrary but must be <= than
// kRequestTimeoutMs.
const int KSelectionRequestorTimerPeriodMs = 100;

// The amount of time to wait for a request to complete before aborting it.
const int kRequestTimeoutMs = 10000;

static_assert(KSelectionRequestorTimerPeriodMs <= kRequestTimeoutMs,
              "timer period must be <= request timeout");

// Combines |data| into a single std::vector<uint8_t>.
std::vector<uint8_t> CombineData(
    const std::vector<scoped_refptr<base::RefCountedMemory>>& data) {
  size_t bytes = 0;
  for (const auto& datum : data)
    bytes += datum->size();
  std::vector<uint8_t> combined;
  combined.reserve(bytes);
  for (const auto& datum : data) {
    std::copy(datum->data(), datum->data() + datum->size(),
              std::back_inserter(combined));
  }
  return combined;
}

}  // namespace

SelectionRequestor::SelectionRequestor(x11::Window x_window,
                                       XEventDispatcher* dispatcher)
    : x_window_(x_window),
      x_property_(x11::Atom::None),
      dispatcher_(dispatcher),
      current_request_index_(0u) {
  x_property_ = gfx::GetAtom(kChromeSelection);
}

SelectionRequestor::~SelectionRequestor() = default;

bool SelectionRequestor::PerformBlockingConvertSelection(
    x11::Atom selection,
    x11::Atom target,
    std::vector<uint8_t>* out_data,
    x11::Atom* out_type) {
  base::TimeTicks timeout =
      base::TimeTicks::Now() +
      base::TimeDelta::FromMilliseconds(kRequestTimeoutMs);
  Request request(selection, target, timeout);
  requests_.push_back(&request);
  if (current_request_index_ == (requests_.size() - 1))
    ConvertSelectionForCurrentRequest();
  BlockTillSelectionNotifyForRequest(&request);

  auto request_it = std::find(requests_.begin(), requests_.end(), &request);
  CHECK(request_it != requests_.end());
  if (static_cast<int>(current_request_index_) >
      request_it - requests_.begin()) {
    --current_request_index_;
  }
  requests_.erase(request_it);

  if (requests_.empty())
    abort_timer_.Stop();

  if (request.success) {
    if (out_data)
      *out_data = CombineData(request.out_data);
    if (out_type)
      *out_type = request.out_type;
  }
  return request.success;
}

void SelectionRequestor::PerformBlockingConvertSelectionWithParameter(
    x11::Atom selection,
    x11::Atom target,
    const std::vector<x11::Atom>& parameter) {
  SetAtomArrayProperty(x_window_, kChromeSelection, "ATOM", parameter);
  PerformBlockingConvertSelection(selection, target, nullptr, nullptr);
}

SelectionData SelectionRequestor::RequestAndWaitForTypes(
    x11::Atom selection,
    const std::vector<x11::Atom>& types) {
  for (const x11::Atom& item : types) {
    std::vector<uint8_t> data;
    x11::Atom type = x11::Atom::None;
    if (PerformBlockingConvertSelection(selection, item, &data, &type) &&
        type == item) {
      return SelectionData(type, base::RefCountedBytes::TakeVector(&data));
    }
  }

  return SelectionData();
}

void SelectionRequestor::OnSelectionNotify(
    const x11::SelectionNotifyEvent& selection) {
  Request* request = GetCurrentRequest();
  x11::Atom event_property = selection.property;
  if (!request || request->completed ||
      request->selection != selection.selection ||
      request->target != selection.target) {
    // ICCCM requires us to delete the property passed into SelectionNotify.
    if (event_property != x11::Atom::None)
      ui::DeleteProperty(x_window_, event_property);
    return;
  }

  bool success = false;
  if (event_property == x_property_) {
    scoped_refptr<base::RefCountedMemory> out_data;
    success = ui::GetRawBytesOfProperty(x_window_, x_property_, &out_data,
                                        &request->out_type);
    if (success) {
      request->out_data.clear();
      request->out_data.push_back(out_data);
    }
  }
  if (event_property != x11::Atom::None)
    ui::DeleteProperty(x_window_, event_property);

  if (request->out_type == gfx::GetAtom(kIncr)) {
    request->data_sent_incrementally = true;
    request->out_data.clear();
    request->out_type = x11::Atom::None;
    request->timeout = base::TimeTicks::Now() +
                       base::TimeDelta::FromMilliseconds(kRequestTimeoutMs);
  } else {
    CompleteRequest(current_request_index_, success);
  }
}

bool SelectionRequestor::CanDispatchPropertyEvent(const x11::Event& event) {
  const auto* prop = event.As<x11::PropertyNotifyEvent>();
  return prop->window == x_window_ && prop->atom == x_property_ &&
         prop->state == x11::Property::NewValue;
}

void SelectionRequestor::OnPropertyEvent(const x11::Event& event) {
  Request* request = GetCurrentRequest();
  if (!request || !request->data_sent_incrementally)
    return;

  scoped_refptr<base::RefCountedMemory> out_data;
  x11::Atom out_type = x11::Atom::None;
  bool success =
      ui::GetRawBytesOfProperty(x_window_, x_property_, &out_data, &out_type);
  if (!success) {
    CompleteRequest(current_request_index_, false);
    return;
  }

  if (request->out_type != x11::Atom::None && request->out_type != out_type) {
    CompleteRequest(current_request_index_, false);
    return;
  }

  request->out_data.push_back(out_data);
  request->out_type = out_type;

  // Delete the property to tell the selection owner to send the next chunk.
  ui::DeleteProperty(x_window_, x_property_);

  request->timeout = base::TimeTicks::Now() +
                     base::TimeDelta::FromMilliseconds(kRequestTimeoutMs);

  if (!out_data->size())
    CompleteRequest(current_request_index_, true);
}

void SelectionRequestor::AbortStaleRequests() {
  base::TimeTicks now = base::TimeTicks::Now();
  for (size_t i = current_request_index_; i < requests_.size(); ++i) {
    if (requests_[i]->timeout <= now)
      CompleteRequest(i, false);
  }
}

void SelectionRequestor::CompleteRequest(size_t index, bool success) {
  if (index >= requests_.size())
    return;

  Request* request = requests_[index];
  if (request->completed)
    return;
  request->success = success;
  request->completed = true;

  if (index == current_request_index_) {
    while (GetCurrentRequest() && GetCurrentRequest()->completed)
      ++current_request_index_;
    ConvertSelectionForCurrentRequest();
  }

  if (request->quit_closure)
    std::move(request->quit_closure).Run();
}

void SelectionRequestor::ConvertSelectionForCurrentRequest() {
  Request* request = GetCurrentRequest();
  if (request) {
    x11::Connection::Get()->ConvertSelection({
        .requestor = static_cast<x11::Window>(x_window_),
        .selection = request->selection,
        .target = request->target,
        .property = x_property_,
        .time = x11::Time::CurrentTime,
    });
  }
}

void SelectionRequestor::BlockTillSelectionNotifyForRequest(Request* request) {
  if (X11EventSource::HasInstance()) {
    if (!abort_timer_.IsRunning()) {
      abort_timer_.Start(
          FROM_HERE,
          base::TimeDelta::FromMilliseconds(KSelectionRequestorTimerPeriodMs),
          this, &SelectionRequestor::AbortStaleRequests);
    }

    base::RunLoop run_loop(base::RunLoop::Type::kNestableTasksAllowed);
    request->quit_closure = run_loop.QuitClosure();
    run_loop.Run();

    // We cannot put logic to process the next request here because the RunLoop
    // might be nested. For instance, request 'B' may start a RunLoop while the
    // RunLoop for request 'A' is running. It is not possible to end the RunLoop
    // for request 'A' without first ending the RunLoop for request 'B'.
  } else {
    // This occurs if PerformBlockingConvertSelection() is called during
    // shutdown and the X11EventSource has already been destroyed.
    auto* conn = x11::Connection::Get();
    auto& events = conn->events();
    while (!request->completed && request->timeout > base::TimeTicks::Now()) {
      conn->Flush();
      conn->ReadResponses();
      if (!conn->events().empty()) {
        x11::Event event = std::move(events.front());
        events.pop_front();
        dispatcher_->DispatchXEvent(&event);
      }
    }
  }
}

SelectionRequestor::Request* SelectionRequestor::GetCurrentRequest() {
  return current_request_index_ == requests_.size()
             ? nullptr
             : requests_[current_request_index_];
}

SelectionRequestor::Request::Request(x11::Atom selection,
                                     x11::Atom target,
                                     base::TimeTicks timeout)
    : selection(selection),
      target(target),
      data_sent_incrementally(false),
      out_type(x11::Atom::None),
      success(false),
      timeout(timeout),
      completed(false) {}

SelectionRequestor::Request::~Request() = default;

}  // namespace ui