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// Copyright 2016 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 <set>
#include "base/macros.h"
#include "base/process/port_provider_mac.h"
#include "base/synchronization/lock.h"
#include "mojo/edk/embedder/scoped_platform_handle.h"
#include "mojo/edk/system/channel.h"
namespace mojo {
namespace edk {
// The MachPortRelay is used by a privileged process, usually the root process,
// to manipulate Mach ports in a child process. Ports can be added to and
// extracted from a child process that has registered itself with the
// |base::PortProvider| used by this class.
class MachPortRelay : public base::PortProvider::Observer {
class Observer {
// Called by the MachPortRelay to notify observers that a new process is
// ready for Mach ports to be sent/received. There are no guarantees about
// the thread this is called on, including the presence of a MessageLoop.
// Implementations must not call AddObserver() or RemoveObserver() during
// this function, as doing so will deadlock.
virtual void OnProcessReady(base::ProcessHandle process) = 0;
// Used by a child process to receive Mach ports from a sender (privileged)
// process. Each Mach port in |handles| is interpreted as an intermediate Mach
// port. It replaces each Mach port with the final Mach port received from the
// intermediate port. This method takes ownership of the intermediate Mach
// port and gives ownership of the final Mach port to the caller. Any handles
// that are not Mach ports will remain unchanged, and the number and ordering
// of handles is preserved.
// Returns |false| on failure and there is no guarantee about whether a Mach
// port is intermediate or final.
// See SendPortsToProcess() for the definition of intermediate and final Mach
// ports.
static bool ReceivePorts(PlatformHandleVector* handles);
explicit MachPortRelay(base::PortProvider* port_provider);
~MachPortRelay() override;
// Sends the Mach ports attached to |message| to |process|.
// For each Mach port attached to |message|, a new Mach port, the intermediate
// port, is created in |process|. The message's Mach port is then sent over
// this intermediate port and the message is modified to refer to the name of
// the intermediate port. The Mach port received over the intermediate port in
// the child is referred to as the final Mach port.
// Returns |false| on failure and |message| may contain a mix of actual Mach
// ports and names.
bool SendPortsToProcess(Channel::Message* message,
base::ProcessHandle process);
// Extracts the Mach ports attached to |message| from |process|.
// Any Mach ports attached to |message| are names and not actual Mach ports
// that are valid in this process. For each of those Mach port names, a send
// right is extracted from |process| and the port name is replaced with the
// send right.
// Returns |false| on failure and |message| may contain a mix of actual Mach
// ports and names.
bool ExtractPortRights(Channel::Message* message,
base::ProcessHandle process);
// Observer interface.
void AddObserver(Observer* observer);
void RemoveObserver(Observer* observer);
base::PortProvider* port_provider() const { return port_provider_; }
// base::PortProvider::Observer implementation.
void OnReceivedTaskPort(base::ProcessHandle process) override;
base::PortProvider* const port_provider_;
base::Lock observers_lock_;
std::set<Observer*> observers_;
} // namespace edk
} // namespace mojo