Add MachMultiprocess and its test

util/test/mac/mach_multiprocess.h

Index: util/test/mac/mach_multiprocess.h
diff --git a/util/test/mac/mach_multiprocess.h b/util/test/mac/mach_multiprocess.h
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+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CRASHPAD_UTIL_TEST_MAC_MACH_MULTIPROCESS_H_
+#define CRASHPAD_UTIL_TEST_MAC_MACH_MULTIPROCESS_H_
+
+#include <mach/mach.h>
+#include <unistd.h>
+
+#include "base/basictypes.h"
+
+namespace crashpad {
+namespace test {
+
+//! \brief Manages a Mach-aware multiprocess test.
+//!
+//! These tests are `fork()`-based. The parent process has access to the child
+//! process’ task port. The parent and child processes are able to communicate
+//! via Mach IPC, and the child process can also send messages to the parent
+//! process via a POSIX pipe.
+//!
+//! Subclasses are expected to implement the parent and child by overriding the
+//! appropriate methods.
+class MachMultiprocess {
+ public:
+  MachMultiprocess();
+
+  //! \brief Runs the test.
+  //!
+  //! This method establishes the proper testing environment and calls Parent()
+  //! in the parent process and Child() in the child process.
+  //!
+  //! This method uses gtest assertions to validate the testing environment. If
+  //! the testing environment cannot be set up properly, it is possible that
+  //! Parent() or Child() will not be called. In the parent process, this method
+  //! also waits for the child process to exit after Parent() returns, and
+  //! verifies that it exited cleanly with gtest assertions.
+  void Run();
+
+ protected:
+  ~MachMultiprocess();
+
+  //! \brief The parent routine.
+  //!
+  //! Test failures should be reported via gtest: `EXPECT_*()`, `ASSERT_*()`,
+  //! `FAIL()`, etc.
+  //!
+  //! This method must not use a `wait()`-family system call to wait for the
+  //! child process to exit, as this is handled by Run().
+  //!
+  //! Subclasses must implement this method to define how the parent operates.
+  virtual void Parent() = 0;
+
+  //! \brief The child routine.
+  //!
+  //! Test failures should be reported via gtest: `EXPECT_*()`, `ASSERT_*()`,
+  //! `FAIL()`, etc.
+  //!
+  //! Subclasses must implement this method to define how the child operates.
+  virtual void Child() = 0;
+
+  //! \brief Returns the child process’ process ID.
+  //!
+  //! This method may only be called by the parent process.
+  pid_t ChildPID() const;
+
+  //! \brief Returns the pipe’s file descriptor.
+  //!
+  //! This method may be called by either the parent or the child process. In
+  //! the parent process, the pipe is read-only, and in the child process, it is
+  //! write-only.
+  int PipeFD() const;
+
+  //! \brief Returns a receive right for the local port.
+  //!
+  //! This method may be called by either the parent or the child process. It
+  //! returns a receive right, with a corresponding send right held in the
+  //! opposing process.
+  mach_port_t LocalPort() const;
+
+  //! \brief Returns a send right for the remote port.
+  //!
+  //! This method may be called by either the parent or the child process. It
+  //! returns a send right, with the corresponding receive right held in the
+  //! opposing process.
+  mach_port_t RemotePort() const;
+
+  //! \brief Returns a send right for the child’s task port.
+  //!
+  //! This method may only be called by the parent process.
+  mach_port_t ChildTask() const;
+
+ private:
+  pid_t child_pid_;  // valid only in parent
+  int pipe_fd_;  // read-only in parent, write-only in child
+  mach_port_t local_port_;  // receive right
+  mach_port_t remote_port_;  // send right
+  mach_port_t child_task_;  // valid only in parent
+
+  DISALLOW_COPY_AND_ASSIGN(MachMultiprocess);
+};
+
+}  // namespace test
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_TEST_MAC_MACH_MULTIPROCESS_H_