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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.
#ifndef BASE_MAC_MACH_PORT_BROKER_H_
#define BASE_MAC_MACH_PORT_BROKER_H_
#include <mach/mach.h>
#include <map>
#include <memory>
#include <string>
#include "base/base_export.h"
#include "base/mac/dispatch_source_mach.h"
#include "base/mac/scoped_mach_port.h"
#include "base/macros.h"
#include "base/process/port_provider_mac.h"
#include "base/process/process_handle.h"
#include "base/synchronization/lock.h"
namespace base {
// On OS X, the task port of a process is required to collect metrics about the
// process, and to insert Mach ports into the process. Running |task_for_pid()|
// is only allowed for privileged code. However, a process has port rights to
// all its subprocesses, so let the child processes send their Mach port to the
// parent over IPC.
//
// Mach ports can only be sent over Mach IPC, not over the |socketpair()| that
// the regular IPC system uses. Hence, the child processes opens a Mach
// connection shortly after launching and ipc their mach data to the parent
// process. A single |MachPortBroker| with a given name is expected to exist in
// the parent process.
//
// Since this data arrives over a separate channel, it is not available
// immediately after a child process has been started.
class BASE_EXPORT MachPortBroker : public base::PortProvider {
public:
// For use in child processes. This will send the task port of the current
// process over Mach IPC to the port registered by name (via this class) in
// the parent process. Returns true if the message was sent successfully
// and false if otherwise.
static bool ChildSendTaskPortToParent(const std::string& name);
// Returns the Mach port name to use when sending or receiving messages.
// Does the Right Thing in the browser and in child processes.
static std::string GetMachPortName(const std::string& name, bool is_child);
MachPortBroker(const std::string& name);
~MachPortBroker() override;
// Performs any initialization work.
bool Init();
// Adds a placeholder to the map for the given pid with MACH_PORT_NULL.
// Callers are expected to later update the port with FinalizePid(). Callers
// MUST acquire the lock given by GetLock() before calling this method (and
// release the lock afterwards).
void AddPlaceholderForPid(base::ProcessHandle pid);
// Removes |pid| from the task port map. Callers MUST acquire the lock given
// by GetLock() before calling this method (and release the lock afterwards).
void InvalidatePid(base::ProcessHandle pid);
// The lock that protects this MachPortBroker object. Callers MUST acquire
// and release this lock around calls to AddPlaceholderForPid(),
// InvalidatePid(), and FinalizePid();
base::Lock& GetLock() { return lock_; }
// Implement |base::PortProvider|.
mach_port_t TaskForPid(base::ProcessHandle process) const override;
private:
friend class MachPortBrokerTest;
// Message handler that is invoked on |dispatch_source_| when an
// incoming message needs to be received.
void HandleRequest();
// Updates the mapping for |pid| to include the given |mach_info|. Does
// nothing if PlaceholderForPid() has not already been called for the given
// |pid|. Callers MUST acquire the lock given by GetLock() before calling
// this method (and release the lock afterwards).
void FinalizePid(base::ProcessHandle pid, mach_port_t task_port);
// Name used to identify a particular port broker.
const std::string name_;
// The Mach port on which the server listens.
base::mac::ScopedMachReceiveRight server_port_;
// The dispatch source and queue on which Mach messages will be received.
std::unique_ptr<base::DispatchSourceMach> dispatch_source_;
// Stores mach info for every process in the broker.
typedef std::map<base::ProcessHandle, mach_port_t> MachMap;
MachMap mach_map_;
// Mutex that guards |mach_map_|.
mutable base::Lock lock_;
DISALLOW_COPY_AND_ASSIGN(MachPortBroker);
};
} // namespace base
#endif // BASE_MAC_MACH_PORT_BROKER_H_
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