Move non-content specific parts of content::MachBroker into base::MachPortBroker.

base/mac/mach_port_broker.h

+// 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 <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/memory/scoped_ptr.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.
+  scoped_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_