// Copyright 2005, Google Inc.
	// All rights reserved.
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are
	// met:
	//
	//     * Redistributions of source code must retain the above copyright
	// notice, this list of conditions and the following disclaimer.
	//     * Redistributions in binary form must reproduce the above
	// copyright notice, this list of conditions and the following disclaimer
	// in the documentation and/or other materials provided with the
	// distribution.
	//     * Neither the name of Google Inc. nor the names of its
	// contributors may be used to endorse or promote products derived from
	// this software without specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	
	//
	// This file implements death tests.
	
	#include "gtest/gtest-death-test.h"
	
	#include <utility>
	
	#include "gtest/internal/gtest-port.h"
	#include "gtest/internal/custom/gtest.h"
	
	#if GTEST_HAS_DEATH_TEST
	
	# if GTEST_OS_MAC
	#  include <crt_externs.h>
	# endif  // GTEST_OS_MAC
	
	# include <errno.h>
	# include <fcntl.h>
	# include <limits.h>
	
	# if GTEST_OS_LINUX
	#  include <signal.h>
	# endif  // GTEST_OS_LINUX
	
	# include <stdarg.h>
	
	# if GTEST_OS_WINDOWS
	#  include <windows.h>
	# else
	#  include <sys/mman.h>
	#  include <sys/wait.h>
	# endif  // GTEST_OS_WINDOWS
	
	# if GTEST_OS_QNX
	#  include <spawn.h>
	# endif  // GTEST_OS_QNX
	
	# if GTEST_OS_FUCHSIA
	#  include <lib/fdio/fd.h>
	#  include <lib/fdio/io.h>
	#  include <lib/fdio/spawn.h>
	#  include <lib/zx/channel.h>
	#  include <lib/zx/port.h>
	#  include <lib/zx/process.h>
	#  include <lib/zx/socket.h>
	#  include <zircon/processargs.h>
	#  include <zircon/syscalls.h>
	#  include <zircon/syscalls/policy.h>
	#  include <zircon/syscalls/port.h>
	# endif  // GTEST_OS_FUCHSIA
	
	#endif  // GTEST_HAS_DEATH_TEST
	
	#include "gtest/gtest-message.h"
	#include "gtest/internal/gtest-string.h"
	#include "src/gtest-internal-inl.h"
	
	namespace testing {
	
	// Constants.
	
	// The default death test style.
	//
	// This is defined in internal/gtest-port.h as "fast", but can be overridden by
	// a definition in internal/custom/gtest-port.h. The recommended value, which is
	// used internally at Google, is "threadsafe".
	static const char kDefaultDeathTestStyle[] = GTEST_DEFAULT_DEATH_TEST_STYLE;
	
	GTEST_DEFINE_string_(
	    death_test_style,
	    internal::StringFromGTestEnv("death_test_style", kDefaultDeathTestStyle),
	    "Indicates how to run a death test in a forked child process: "
	    "\"threadsafe\" (child process re-executes the test binary "
	    "from the beginning, running only the specific death test) or "
	    "\"fast\" (child process runs the death test immediately "
	    "after forking).");
	
	GTEST_DEFINE_bool_(
	    death_test_use_fork,
	    internal::BoolFromGTestEnv("death_test_use_fork", false),
	    "Instructs to use fork()/_exit() instead of clone() in death tests. "
	    "Ignored and always uses fork() on POSIX systems where clone() is not "
	    "implemented. Useful when running under valgrind or similar tools if "
	    "those do not support clone(). Valgrind 3.3.1 will just fail if "
	    "it sees an unsupported combination of clone() flags. "
	    "It is not recommended to use this flag w/o valgrind though it will "
	    "work in 99% of the cases. Once valgrind is fixed, this flag will "
	    "most likely be removed.");
	
	namespace internal {
	GTEST_DEFINE_string_(
	    internal_run_death_test, "",
	    "Indicates the file, line number, temporal index of "
	    "the single death test to run, and a file descriptor to "
	    "which a success code may be sent, all separated by "
	    "the '|' characters.  This flag is specified if and only if the current "
	    "process is a sub-process launched for running a thread-safe "
	    "death test.  FOR INTERNAL USE ONLY.");
	}  // namespace internal
	
	#if GTEST_HAS_DEATH_TEST
	
	namespace internal {
	
	// Valid only for fast death tests. Indicates the code is running in the
	// child process of a fast style death test.
	# if !GTEST_OS_WINDOWS && !GTEST_OS_FUCHSIA
	static bool g_in_fast_death_test_child = false;
	# endif
	
	// Returns a Boolean value indicating whether the caller is currently
	// executing in the context of the death test child process.  Tools such as
	// Valgrind heap checkers may need this to modify their behavior in death
	// tests.  IMPORTANT: This is an internal utility.  Using it may break the
	// implementation of death tests.  User code MUST NOT use it.
	bool InDeathTestChild() {
	# if GTEST_OS_WINDOWS || GTEST_OS_FUCHSIA
	
	  // On Windows and Fuchsia, death tests are thread-safe regardless of the value
	  // of the death_test_style flag.
	  return !GTEST_FLAG(internal_run_death_test).empty();
	
	# else
	
	  if (GTEST_FLAG(death_test_style) == "threadsafe")
	    return !GTEST_FLAG(internal_run_death_test).empty();
	  else
	    return g_in_fast_death_test_child;
	#endif
	}
	
	}  // namespace internal
	
	// ExitedWithCode constructor.
	ExitedWithCode::ExitedWithCode(int exit_code) : exit_code_(exit_code) {
	}
	
	// ExitedWithCode function-call operator.
	bool ExitedWithCode::operator()(int exit_status) const {
	# if GTEST_OS_WINDOWS || GTEST_OS_FUCHSIA
	
	  return exit_status == exit_code_;
	
	# else
	
	  return WIFEXITED(exit_status) && WEXITSTATUS(exit_status) == exit_code_;
	
	# endif  // GTEST_OS_WINDOWS || GTEST_OS_FUCHSIA
	}
	
	# if !GTEST_OS_WINDOWS && !GTEST_OS_FUCHSIA
	// KilledBySignal constructor.
	KilledBySignal::KilledBySignal(int signum) : signum_(signum) {
	}
	
	// KilledBySignal function-call operator.
	bool KilledBySignal::operator()(int exit_status) const {
	#  if defined(GTEST_KILLED_BY_SIGNAL_OVERRIDE_)
	  {
	    bool result;
	    if (GTEST_KILLED_BY_SIGNAL_OVERRIDE_(signum_, exit_status, &result)) {
	      return result;
	    }
	  }
	#  endif  // defined(GTEST_KILLED_BY_SIGNAL_OVERRIDE_)
	  return WIFSIGNALED(exit_status) && WTERMSIG(exit_status) == signum_;
	}
	# endif  // !GTEST_OS_WINDOWS && !GTEST_OS_FUCHSIA
	
	namespace internal {
	
	// Utilities needed for death tests.
	
	// Generates a textual description of a given exit code, in the format
	// specified by wait(2).
	static std::string ExitSummary(int exit_code) {
	  Message m;
	
	# if GTEST_OS_WINDOWS || GTEST_OS_FUCHSIA
	
	  m << "Exited with exit status " << exit_code;
	
	# else
	
	  if (WIFEXITED(exit_code)) {
	    m << "Exited with exit status " << WEXITSTATUS(exit_code);
	  } else if (WIFSIGNALED(exit_code)) {
	    m << "Terminated by signal " << WTERMSIG(exit_code);
	  }
	#  ifdef WCOREDUMP
	  if (WCOREDUMP(exit_code)) {
	    m << " (core dumped)";
	  }
	#  endif
	# endif  // GTEST_OS_WINDOWS || GTEST_OS_FUCHSIA
	
	  return m.GetString();
	}
	
	// Returns true if exit_status describes a process that was terminated
	// by a signal, or exited normally with a nonzero exit code.
	bool ExitedUnsuccessfully(int exit_status) {
	  return !ExitedWithCode(0)(exit_status);
	}
	
	# if !GTEST_OS_WINDOWS && !GTEST_OS_FUCHSIA
	// Generates a textual failure message when a death test finds more than
	// one thread running, or cannot determine the number of threads, prior
	// to executing the given statement.  It is the responsibility of the
	// caller not to pass a thread_count of 1.
	static std::string DeathTestThreadWarning(size_t thread_count) {
	  Message msg;
	  msg << "Death tests use fork(), which is unsafe particularly"
	      << " in a threaded context. For this test, " << GTEST_NAME_ << " ";
	  if (thread_count == 0) {
	    msg << "couldn't detect the number of threads.";
	  } else {
	    msg << "detected " << thread_count << " threads.";
	  }
	  msg << " See "
	         "https://github.com/google/googletest/blob/master/googletest/docs/"
	         "advanced.md#death-tests-and-threads"
	      << " for more explanation and suggested solutions, especially if"
	      << " this is the last message you see before your test times out.";
	  return msg.GetString();
	}
	# endif  // !GTEST_OS_WINDOWS && !GTEST_OS_FUCHSIA
	
	// Flag characters for reporting a death test that did not die.
	static const char kDeathTestLived = 'L';
	static const char kDeathTestReturned = 'R';
	static const char kDeathTestThrew = 'T';
	static const char kDeathTestInternalError = 'I';
	
	#if GTEST_OS_FUCHSIA
	
	// File descriptor used for the pipe in the child process.
	static const int kFuchsiaReadPipeFd = 3;
	
	#endif
	
	// An enumeration describing all of the possible ways that a death test can
	// conclude.  DIED means that the process died while executing the test
	// code; LIVED means that process lived beyond the end of the test code;
	// RETURNED means that the test statement attempted to execute a return
	// statement, which is not allowed; THREW means that the test statement
	// returned control by throwing an exception.  IN_PROGRESS means the test
	// has not yet concluded.
	enum DeathTestOutcome { IN_PROGRESS, DIED, LIVED, RETURNED, THREW };
	
	// Routine for aborting the program which is safe to call from an
	// exec-style death test child process, in which case the error
	// message is propagated back to the parent process.  Otherwise, the
	// message is simply printed to stderr.  In either case, the program
	// then exits with status 1.
	static void DeathTestAbort(const std::string& message) {
	  // On a POSIX system, this function may be called from a threadsafe-style
	  // death test child process, which operates on a very small stack.  Use
	  // the heap for any additional non-minuscule memory requirements.
	  const InternalRunDeathTestFlag* const flag =
	      GetUnitTestImpl()->internal_run_death_test_flag();
	  if (flag != nullptr) {
	    FILE* parent = posix::FDOpen(flag->write_fd(), "w");
	    fputc(kDeathTestInternalError, parent);
	    fprintf(parent, "%s", message.c_str());
	    fflush(parent);
	    _exit(1);
	  } else {
	    fprintf(stderr, "%s", message.c_str());
	    fflush(stderr);
	    posix::Abort();
	  }
	}
	
	// A replacement for CHECK that calls DeathTestAbort if the assertion
	// fails.
	# define GTEST_DEATH_TEST_CHECK_(expression) \
	  do { \
	    if (!::testing::internal::IsTrue(expression)) { \
	      DeathTestAbort( \
	          ::std::string("CHECK failed: File ") + __FILE__ +  ", line " \
	          + ::testing::internal::StreamableToString(__LINE__) + ": " \
	          + #expression); \
	    } \
	  } while (::testing::internal::AlwaysFalse())
	
	// This macro is similar to GTEST_DEATH_TEST_CHECK_, but it is meant for
	// evaluating any system call that fulfills two conditions: it must return
	// -1 on failure, and set errno to EINTR when it is interrupted and
	// should be tried again.  The macro expands to a loop that repeatedly
	// evaluates the expression as long as it evaluates to -1 and sets
	// errno to EINTR.  If the expression evaluates to -1 but errno is
	// something other than EINTR, DeathTestAbort is called.
	# define GTEST_DEATH_TEST_CHECK_SYSCALL_(expression) \
	  do { \
	    int gtest_retval; \
	    do { \
	      gtest_retval = (expression); \
	    } while (gtest_retval == -1 && errno == EINTR); \
	    if (gtest_retval == -1) { \
	      DeathTestAbort( \
	          ::std::string("CHECK failed: File ") + __FILE__ + ", line " \
	          + ::testing::internal::StreamableToString(__LINE__) + ": " \
	          + #expression + " != -1"); \
	    } \
	  } while (::testing::internal::AlwaysFalse())
	
	// Returns the message describing the last system error in errno.
	std::string GetLastErrnoDescription() {
	    return errno == 0 ? "" : posix::StrError(errno);
	}
	
	// This is called from a death test parent process to read a failure
	// message from the death test child process and log it with the FATAL
	// severity. On Windows, the message is read from a pipe handle. On other
	// platforms, it is read from a file descriptor.
	static void FailFromInternalError(int fd) {
	  Message error;
	  char buffer[256];
	  int num_read;
	
	  do {
	    while ((num_read = posix::Read(fd, buffer, 255)) > 0) {
	      buffer[num_read] = '\0';
	      error << buffer;
	    }
	  } while (num_read == -1 && errno == EINTR);
	
	  if (num_read == 0) {
	    GTEST_LOG_(FATAL) << error.GetString();
	  } else {
	    const int last_error = errno;
	    GTEST_LOG_(FATAL) << "Error while reading death test internal: "
	                      << GetLastErrnoDescription() << " [" << last_error << "]";
	  }
	}
	
	// Death test constructor.  Increments the running death test count
	// for the current test.
	DeathTest::DeathTest() {
	  TestInfo* const info = GetUnitTestImpl()->current_test_info();
	  if (info == nullptr) {
	    DeathTestAbort("Cannot run a death test outside of a TEST or "
	                   "TEST_F construct");
	  }
	}
	
	// Creates and returns a death test by dispatching to the current
	// death test factory.
	bool DeathTest::Create(const char* statement,
	                       Matcher<const std::string&> matcher, const char* file,
	                       int line, DeathTest** test) {
	  return GetUnitTestImpl()->death_test_factory()->Create(
	      statement, std::move(matcher), file, line, test);
	}
	
	const char* DeathTest::LastMessage() {
	  return last_death_test_message_.c_str();
	}
	
	void DeathTest::set_last_death_test_message(const std::string& message) {
	  last_death_test_message_ = message;
	}
	
	std::string DeathTest::last_death_test_message_;
	
	// Provides cross platform implementation for some death functionality.
	class DeathTestImpl : public DeathTest {
	 protected:
	  DeathTestImpl(const char* a_statement, Matcher<const std::string&> matcher)
	      : statement_(a_statement),
	        matcher_(std::move(matcher)),
	        spawned_(false),
	        status_(-1),
	        outcome_(IN_PROGRESS),
	        read_fd_(-1),
	        write_fd_(-1) {}
	
	  // read_fd_ is expected to be closed and cleared by a derived class.

	  ~DeathTestImpl() override { GTEST_DEATH_TEST_CHECK_(read_fd_ == -1); }
	
	  void Abort(AbortReason reason) override;
	  bool Passed(bool status_ok) override;
	
	  const char* statement() const { return statement_; }
	  bool spawned() const { return spawned_; }
	  void set_spawned(bool is_spawned) { spawned_ = is_spawned; }
	  int status() const { return status_; }
	  void set_status(int a_status) { status_ = a_status; }
	  DeathTestOutcome outcome() const { return outcome_; }
	  void set_outcome(DeathTestOutcome an_outcome) { outcome_ = an_outcome; }
	  int read_fd() const { return read_fd_; }
	  void set_read_fd(int fd) { read_fd_ = fd; }
	  int write_fd() const { return write_fd_; }
	  void set_write_fd(int fd) { write_fd_ = fd; }
	
	  // Called in the parent process only. Reads the result code of the death
	  // test child process via a pipe, interprets it to set the outcome_
	  // member, and closes read_fd_.  Outputs diagnostics and terminates in
	  // case of unexpected codes.
	  void ReadAndInterpretStatusByte();
	
	  // Returns stderr output from the child process.
	  virtual std::string GetErrorLogs();
	
	 private:
	  // The textual content of the code this object is testing.  This class
	  // doesn't own this string and should not attempt to delete it.
	  const char* const statement_;
	  // A matcher that's expected to match the stderr output by the child process.
	  Matcher<const std::string&> matcher_;
	  // True if the death test child process has been successfully spawned.
	  bool spawned_;
	  // The exit status of the child process.
	  int status_;
	  // How the death test concluded.
	  DeathTestOutcome outcome_;
	  // Descriptor to the read end of the pipe to the child process.  It is
	  // always -1 in the child process.  The child keeps its write end of the
	  // pipe in write_fd_.
	  int read_fd_;
	  // Descriptor to the child's write end of the pipe to the parent process.
	  // It is always -1 in the parent process.  The parent keeps its end of the
	  // pipe in read_fd_.
	  int write_fd_;
	};
	
	// Called in the parent process only. Reads the result code of the death
	// test child process via a pipe, interprets it to set the outcome_
	// member, and closes read_fd_.  Outputs diagnostics and terminates in
	// case of unexpected codes.
	void DeathTestImpl::ReadAndInterpretStatusByte() {
	  char flag;
	  int bytes_read;
	
	  // The read() here blocks until data is available (signifying the
	  // failure of the death test) or until the pipe is closed (signifying
	  // its success), so it's okay to call this in the parent before
	  // the child process has exited.
	  do {
	    bytes_read = posix::Read(read_fd(), &flag, 1);
	  } while (bytes_read == -1 && errno == EINTR);
	
	  if (bytes_read == 0) {
	    set_outcome(DIED);
	  } else if (bytes_read == 1) {
	    switch (flag) {
	      case kDeathTestReturned:
	        set_outcome(RETURNED);
	        break;
	      case kDeathTestThrew:
	        set_outcome(THREW);
	        break;
	      case kDeathTestLived:
	        set_outcome(LIVED);
	        break;
	      case kDeathTestInternalError:
	        FailFromInternalError(read_fd());  // Does not return.
	        break;
	      default:
	        GTEST_LOG_(FATAL) << "Death test child process reported "
	                          << "unexpected status byte ("
	                          << static_cast<unsigned int>(flag) << ")";
	    }
	  } else {
	    GTEST_LOG_(FATAL) << "Read from death test child process failed: "
	                      << GetLastErrnoDescription();
	  }
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(posix::Close(read_fd()));
	  set_read_fd(-1);
	}
	
	std::string DeathTestImpl::GetErrorLogs() {
	  return GetCapturedStderr();
	}
	
	// Signals that the death test code which should have exited, didn't.
	// Should be called only in a death test child process.
	// Writes a status byte to the child's status file descriptor, then
	// calls _exit(1).
	void DeathTestImpl::Abort(AbortReason reason) {
	  // The parent process considers the death test to be a failure if
	  // it finds any data in our pipe.  So, here we write a single flag byte
	  // to the pipe, then exit.
	  const char status_ch =
	      reason == TEST_DID_NOT_DIE ? kDeathTestLived :
	      reason == TEST_THREW_EXCEPTION ? kDeathTestThrew : kDeathTestReturned;
	
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(posix::Write(write_fd(), &status_ch, 1));
	  // We are leaking the descriptor here because on some platforms (i.e.,
	  // when built as Windows DLL), destructors of global objects will still
	  // run after calling _exit(). On such systems, write_fd_ will be
	  // indirectly closed from the destructor of UnitTestImpl, causing double
	  // close if it is also closed here. On debug configurations, double close
	  // may assert. As there are no in-process buffers to flush here, we are
	  // relying on the OS to close the descriptor after the process terminates
	  // when the destructors are not run.
	  _exit(1);  // Exits w/o any normal exit hooks (we were supposed to crash)
	}
	
	// Returns an indented copy of stderr output for a death test.
	// This makes distinguishing death test output lines from regular log lines
	// much easier.
	static ::std::string FormatDeathTestOutput(const ::std::string& output) {
	  ::std::string ret;
	  for (size_t at = 0; ; ) {
	    const size_t line_end = output.find('\n', at);
	    ret += "[  DEATH   ] ";
	    if (line_end == ::std::string::npos) {
	      ret += output.substr(at);
	      break;
	    }
	    ret += output.substr(at, line_end + 1 - at);
	    at = line_end + 1;
	  }
	  return ret;
	}
	
	// Assesses the success or failure of a death test, using both private
	// members which have previously been set, and one argument:
	//
	// Private data members:
	//   outcome:  An enumeration describing how the death test
	//             concluded: DIED, LIVED, THREW, or RETURNED.  The death test
	//             fails in the latter three cases.
	//   status:   The exit status of the child process. On *nix, it is in the
	//             in the format specified by wait(2). On Windows, this is the
	//             value supplied to the ExitProcess() API or a numeric code
	//             of the exception that terminated the program.
	//   matcher_: A matcher that's expected to match the stderr output by the child
	//             process.
	//
	// Argument:
	//   status_ok: true if exit_status is acceptable in the context of
	//              this particular death test, which fails if it is false
	//
	// Returns true if all of the above conditions are met.  Otherwise, the
	// first failing condition, in the order given above, is the one that is
	// reported. Also sets the last death test message string.
	bool DeathTestImpl::Passed(bool status_ok) {
	  if (!spawned())
	    return false;
	
	  const std::string error_message = GetErrorLogs();
	
	  bool success = false;
	  Message buffer;
	
	  buffer << "Death test: " << statement() << "\n";
	  switch (outcome()) {
	    case LIVED:
	      buffer << "    Result: failed to die.\n"
	             << " Error msg:\n" << FormatDeathTestOutput(error_message);
	      break;
	    case THREW:
	      buffer << "    Result: threw an exception.\n"
	             << " Error msg:\n" << FormatDeathTestOutput(error_message);
	      break;
	    case RETURNED:
	      buffer << "    Result: illegal return in test statement.\n"
	             << " Error msg:\n" << FormatDeathTestOutput(error_message);
	      break;
	    case DIED:
	      if (status_ok) {
	        if (matcher_.Matches(error_message)) {
	          success = true;
	        } else {
	          std::ostringstream stream;
	          matcher_.DescribeTo(&stream);
	          buffer << "    Result: died but not with expected error.\n"
	                 << "  Expected: " << stream.str() << "\n"
	                 << "Actual msg:\n"
	                 << FormatDeathTestOutput(error_message);
	        }
	      } else {
	        buffer << "    Result: died but not with expected exit code:\n"
	               << "            " << ExitSummary(status()) << "\n"
	               << "Actual msg:\n" << FormatDeathTestOutput(error_message);
	      }
	      break;
	    case IN_PROGRESS:
	    default:
	      GTEST_LOG_(FATAL)
	          << "DeathTest::Passed somehow called before conclusion of test";
	  }
	
	  DeathTest::set_last_death_test_message(buffer.GetString());
	  return success;
	}
	
	# if GTEST_OS_WINDOWS
	// WindowsDeathTest implements death tests on Windows. Due to the
	// specifics of starting new processes on Windows, death tests there are
	// always threadsafe, and Google Test considers the
	// --gtest_death_test_style=fast setting to be equivalent to
	// --gtest_death_test_style=threadsafe there.
	//
	// A few implementation notes:  Like the Linux version, the Windows
	// implementation uses pipes for child-to-parent communication. But due to
	// the specifics of pipes on Windows, some extra steps are required:
	//
	// 1. The parent creates a communication pipe and stores handles to both
	//    ends of it.
	// 2. The parent starts the child and provides it with the information
	//    necessary to acquire the handle to the write end of the pipe.
	// 3. The child acquires the write end of the pipe and signals the parent
	//    using a Windows event.
	// 4. Now the parent can release the write end of the pipe on its side. If
	//    this is done before step 3, the object's reference count goes down to
	//    0 and it is destroyed, preventing the child from acquiring it. The
	//    parent now has to release it, or read operations on the read end of
	//    the pipe will not return when the child terminates.
	// 5. The parent reads child's output through the pipe (outcome code and
	//    any possible error messages) from the pipe, and its stderr and then
	//    determines whether to fail the test.
	//
	// Note: to distinguish Win32 API calls from the local method and function
	// calls, the former are explicitly resolved in the global namespace.
	//
	class WindowsDeathTest : public DeathTestImpl {
	 public:
	  WindowsDeathTest(const char* a_statement, Matcher<const std::string&> matcher,
	                   const char* file, int line)
	      : DeathTestImpl(a_statement, std::move(matcher)),
	        file_(file),
	        line_(line) {}
	
	  // All of these virtual functions are inherited from DeathTest.
	  virtual int Wait();
	  virtual TestRole AssumeRole();
	
	 private:
	  // The name of the file in which the death test is located.
	  const char* const file_;
	  // The line number on which the death test is located.
	  const int line_;
	  // Handle to the write end of the pipe to the child process.
	  AutoHandle write_handle_;
	  // Child process handle.
	  AutoHandle child_handle_;
	  // Event the child process uses to signal the parent that it has
	  // acquired the handle to the write end of the pipe. After seeing this
	  // event the parent can release its own handles to make sure its
	  // ReadFile() calls return when the child terminates.
	  AutoHandle event_handle_;
	};
	
	// Waits for the child in a death test to exit, returning its exit
	// status, or 0 if no child process exists.  As a side effect, sets the
	// outcome data member.
	int WindowsDeathTest::Wait() {
	  if (!spawned())
	    return 0;
	
	  // Wait until the child either signals that it has acquired the write end
	  // of the pipe or it dies.
	  const HANDLE wait_handles[2] = { child_handle_.Get(), event_handle_.Get() };
	  switch (::WaitForMultipleObjects(2,
	                                   wait_handles,
	                                   FALSE,  // Waits for any of the handles.
	                                   INFINITE)) {
	    case WAIT_OBJECT_0:
	    case WAIT_OBJECT_0 + 1:
	      break;
	    default:
	      GTEST_DEATH_TEST_CHECK_(false);  // Should not get here.
	  }
	
	  // The child has acquired the write end of the pipe or exited.
	  // We release the handle on our side and continue.
	  write_handle_.Reset();
	  event_handle_.Reset();
	
	  ReadAndInterpretStatusByte();
	
	  // Waits for the child process to exit if it haven't already. This
	  // returns immediately if the child has already exited, regardless of
	  // whether previous calls to WaitForMultipleObjects synchronized on this
	  // handle or not.
	  GTEST_DEATH_TEST_CHECK_(
	      WAIT_OBJECT_0 == ::WaitForSingleObject(child_handle_.Get(),
	                                             INFINITE));
	  DWORD status_code;
	  GTEST_DEATH_TEST_CHECK_(
	      ::GetExitCodeProcess(child_handle_.Get(), &status_code) != FALSE);
	  child_handle_.Reset();
	  set_status(static_cast<int>(status_code));
	  return status();
	}
	
	// The AssumeRole process for a Windows death test.  It creates a child
	// process with the same executable as the current process to run the
	// death test.  The child process is given the --gtest_filter and
	// --gtest_internal_run_death_test flags such that it knows to run the
	// current death test only.
	DeathTest::TestRole WindowsDeathTest::AssumeRole() {
	  const UnitTestImpl* const impl = GetUnitTestImpl();
	  const InternalRunDeathTestFlag* const flag =
	      impl->internal_run_death_test_flag();
	  const TestInfo* const info = impl->current_test_info();
	  const int death_test_index = info->result()->death_test_count();
	
	  if (flag != nullptr) {
	    // ParseInternalRunDeathTestFlag() has performed all the necessary
	    // processing.
	    set_write_fd(flag->write_fd());
	    return EXECUTE_TEST;
	  }
	
	  // WindowsDeathTest uses an anonymous pipe to communicate results of
	  // a death test.
	  SECURITY_ATTRIBUTES handles_are_inheritable = {sizeof(SECURITY_ATTRIBUTES),
	                                                 nullptr, TRUE};
	  HANDLE read_handle, write_handle;
	  GTEST_DEATH_TEST_CHECK_(
	      ::CreatePipe(&read_handle, &write_handle, &handles_are_inheritable,
	                   0)  // Default buffer size.
	      != FALSE);
	  set_read_fd(::_open_osfhandle(reinterpret_cast<intptr_t>(read_handle),
	                                O_RDONLY));
	  write_handle_.Reset(write_handle);
	  event_handle_.Reset(::CreateEvent(
	      &handles_are_inheritable,
	      TRUE,       // The event will automatically reset to non-signaled state.
	      FALSE,      // The initial state is non-signalled.
	      nullptr));  // The even is unnamed.
	  GTEST_DEATH_TEST_CHECK_(event_handle_.Get() != nullptr);
	  const std::string filter_flag = std::string("--") + GTEST_FLAG_PREFIX_ +
	                                  kFilterFlag + "=" + info->test_suite_name() +
	                                  "." + info->name();
	  const std::string internal_flag =
	      std::string("--") + GTEST_FLAG_PREFIX_ + kInternalRunDeathTestFlag +
	      "=" + file_ + "|" + StreamableToString(line_) + "|" +
	      StreamableToString(death_test_index) + "|" +
	      StreamableToString(static_cast<unsigned int>(::GetCurrentProcessId())) +
	      // size_t has the same width as pointers on both 32-bit and 64-bit
	      // Windows platforms.
	      // See http://msdn.microsoft.com/en-us/library/tcxf1dw6.aspx.
	      "|" + StreamableToString(reinterpret_cast<size_t>(write_handle)) +
	      "|" + StreamableToString(reinterpret_cast<size_t>(event_handle_.Get()));
	
	  char executable_path[_MAX_PATH + 1];  // NOLINT
	  GTEST_DEATH_TEST_CHECK_(_MAX_PATH + 1 != ::GetModuleFileNameA(nullptr,
	                                                                executable_path,
	                                                                _MAX_PATH));
	
	  std::string command_line =
	      std::string(::GetCommandLineA()) + " " + filter_flag + " \"" +
	      internal_flag + "\"";
	
	  DeathTest::set_last_death_test_message("");
	
	  CaptureStderr();
	  // Flush the log buffers since the log streams are shared with the child.
	  FlushInfoLog();
	
	  // The child process will share the standard handles with the parent.
	  STARTUPINFOA startup_info;
	  memset(&startup_info, 0, sizeof(STARTUPINFO));
	  startup_info.dwFlags = STARTF_USESTDHANDLES;
	  startup_info.hStdInput = ::GetStdHandle(STD_INPUT_HANDLE);
	  startup_info.hStdOutput = ::GetStdHandle(STD_OUTPUT_HANDLE);
	  startup_info.hStdError = ::GetStdHandle(STD_ERROR_HANDLE);
	
	  PROCESS_INFORMATION process_info;
	  GTEST_DEATH_TEST_CHECK_(
	      ::CreateProcessA(
	          executable_path, const_cast<char*>(command_line.c_str()),
	          nullptr,  // Retuned process handle is not inheritable.
	          nullptr,  // Retuned thread handle is not inheritable.
	          TRUE,  // Child inherits all inheritable handles (for write_handle_).
	          0x0,   // Default creation flags.
	          nullptr,  // Inherit the parent's environment.
	          UnitTest::GetInstance()->original_working_dir(), &startup_info,
	          &process_info) != FALSE);
	  child_handle_.Reset(process_info.hProcess);
	  ::CloseHandle(process_info.hThread);
	  set_spawned(true);
	  return OVERSEE_TEST;
	}
	
	# elif GTEST_OS_FUCHSIA
	
	class FuchsiaDeathTest : public DeathTestImpl {
	 public:
	  FuchsiaDeathTest(const char* a_statement, Matcher<const std::string&> matcher,
	                   const char* file, int line)
	      : DeathTestImpl(a_statement, std::move(matcher)),
	        file_(file),
	        line_(line) {}
	
	  // All of these virtual functions are inherited from DeathTest.
	  int Wait() override;
	  TestRole AssumeRole() override;
	  std::string GetErrorLogs() override;
	
	 private:
	  // The name of the file in which the death test is located.
	  const char* const file_;
	  // The line number on which the death test is located.
	  const int line_;
	  // The stderr data captured by the child process.
	  std::string captured_stderr_;
	
	  zx::process child_process_;
	  zx::channel exception_channel_;
	  zx::socket stderr_socket_;
	};
	
	// Utility class for accumulating command-line arguments.
	class Arguments {
	 public:
	  Arguments() { args_.push_back(nullptr); }
	
	  ~Arguments() {
	    for (std::vector<char*>::iterator i = args_.begin(); i != args_.end();
	         ++i) {
	      free(*i);
	    }
	  }
	  void AddArgument(const char* argument) {
	    args_.insert(args_.end() - 1, posix::StrDup(argument));
	  }
	
	  template <typename Str>
	  void AddArguments(const ::std::vector<Str>& arguments) {
	    for (typename ::std::vector<Str>::const_iterator i = arguments.begin();
	         i != arguments.end();
	         ++i) {
	      args_.insert(args_.end() - 1, posix::StrDup(i->c_str()));
	    }
	  }
	  char* const* Argv() {
	    return &args_[0];
	  }
	
	  int size() {
	    return args_.size() - 1;
	  }
	
	 private:
	  std::vector<char*> args_;
	};
	
	// Waits for the child in a death test to exit, returning its exit
	// status, or 0 if no child process exists.  As a side effect, sets the
	// outcome data member.
	int FuchsiaDeathTest::Wait() {
	  const int kProcessKey = 0;
	  const int kSocketKey = 1;
	  const int kExceptionKey = 2;
	
	  if (!spawned())
	    return 0;
	
	  // Create a port to wait for socket/task/exception events.
	  zx_status_t status_zx;
	  zx::port port;
	  status_zx = zx::port::create(0, &port);
	  GTEST_DEATH_TEST_CHECK_(status_zx == ZX_OK);
	
	  // Register to wait for the child process to terminate.
	  status_zx = child_process_.wait_async(
	      port, kProcessKey, ZX_PROCESS_TERMINATED, ZX_WAIT_ASYNC_ONCE);
	  GTEST_DEATH_TEST_CHECK_(status_zx == ZX_OK);
	
	  // Register to wait for the socket to be readable or closed.
	  status_zx = stderr_socket_.wait_async(
	      port, kSocketKey, ZX_SOCKET_READABLE | ZX_SOCKET_PEER_CLOSED,
	      ZX_WAIT_ASYNC_ONCE);
	  GTEST_DEATH_TEST_CHECK_(status_zx == ZX_OK);
	
	  // Register to wait for an exception.
	  status_zx = exception_channel_.wait_async(
	      port, kExceptionKey, ZX_CHANNEL_READABLE, ZX_WAIT_ASYNC_ONCE);
	  GTEST_DEATH_TEST_CHECK_(status_zx == ZX_OK);
	
	  bool process_terminated = false;
	  bool socket_closed = false;
	  do {
	    zx_port_packet_t packet = {};
	    status_zx = port.wait(zx::time::infinite(), &packet);
	    GTEST_DEATH_TEST_CHECK_(status_zx == ZX_OK);
	
	    if (packet.key == kExceptionKey) {
	      // Process encountered an exception. Kill it directly rather than
	      // letting other handlers process the event. We will get a kProcessKey
	      // event when the process actually terminates.
	      status_zx = child_process_.kill();
	      GTEST_DEATH_TEST_CHECK_(status_zx == ZX_OK);
	    } else if (packet.key == kProcessKey) {
	      // Process terminated.
	      GTEST_DEATH_TEST_CHECK_(ZX_PKT_IS_SIGNAL_ONE(packet.type));
	      GTEST_DEATH_TEST_CHECK_(packet.signal.observed & ZX_PROCESS_TERMINATED);
	      process_terminated = true;
	    } else if (packet.key == kSocketKey) {
	      GTEST_DEATH_TEST_CHECK_(ZX_PKT_IS_SIGNAL_ONE(packet.type));
	      if (packet.signal.observed & ZX_SOCKET_READABLE) {
	        // Read data from the socket.
	        constexpr size_t kBufferSize = 1024;
	        do {
	          size_t old_length = captured_stderr_.length();
	          size_t bytes_read = 0;
	          captured_stderr_.resize(old_length + kBufferSize);
	          status_zx = stderr_socket_.read(
	              0, &captured_stderr_.front() + old_length, kBufferSize,
	              &bytes_read);
	          captured_stderr_.resize(old_length + bytes_read);
	        } while (status_zx == ZX_OK);
	        if (status_zx == ZX_ERR_PEER_CLOSED) {
	          socket_closed = true;
	        } else {
	          GTEST_DEATH_TEST_CHECK_(status_zx == ZX_ERR_SHOULD_WAIT);
	          status_zx = stderr_socket_.wait_async(
	              port, kSocketKey, ZX_SOCKET_READABLE | ZX_SOCKET_PEER_CLOSED,
	              ZX_WAIT_ASYNC_ONCE);
	          GTEST_DEATH_TEST_CHECK_(status_zx == ZX_OK);
	        }
	      } else {
	        GTEST_DEATH_TEST_CHECK_(packet.signal.observed & ZX_SOCKET_PEER_CLOSED);
	        socket_closed = true;
	      }
	    }
	  } while (!process_terminated && !socket_closed);
	
	  ReadAndInterpretStatusByte();
	
	  zx_info_process_t buffer;
	  status_zx = child_process_.get_info(
	      ZX_INFO_PROCESS, &buffer, sizeof(buffer), nullptr, nullptr);
	  GTEST_DEATH_TEST_CHECK_(status_zx == ZX_OK);
	
	  GTEST_DEATH_TEST_CHECK_(buffer.exited);
	  set_status(buffer.return_code);
	  return status();
	}
	
	// The AssumeRole process for a Fuchsia death test.  It creates a child
	// process with the same executable as the current process to run the
	// death test.  The child process is given the --gtest_filter and
	// --gtest_internal_run_death_test flags such that it knows to run the
	// current death test only.
	DeathTest::TestRole FuchsiaDeathTest::AssumeRole() {
	  const UnitTestImpl* const impl = GetUnitTestImpl();
	  const InternalRunDeathTestFlag* const flag =
	      impl->internal_run_death_test_flag();
	  const TestInfo* const info = impl->current_test_info();
	  const int death_test_index = info->result()->death_test_count();
	
	  if (flag != nullptr) {
	    // ParseInternalRunDeathTestFlag() has performed all the necessary
	    // processing.
	    set_write_fd(kFuchsiaReadPipeFd);
	    return EXECUTE_TEST;
	  }
	
	  // Flush the log buffers since the log streams are shared with the child.
	  FlushInfoLog();
	
	  // Build the child process command line.
	  const std::string filter_flag = std::string("--") + GTEST_FLAG_PREFIX_ +
	                                  kFilterFlag + "=" + info->test_suite_name() +
	                                  "." + info->name();
	  const std::string internal_flag =
	      std::string("--") + GTEST_FLAG_PREFIX_ + kInternalRunDeathTestFlag + "="
	      + file_ + "|"
	      + StreamableToString(line_) + "|"
	      + StreamableToString(death_test_index);
	  Arguments args;
	  args.AddArguments(GetInjectableArgvs());
	  args.AddArgument(filter_flag.c_str());
	  args.AddArgument(internal_flag.c_str());
	
	  // Build the pipe for communication with the child.
	  zx_status_t status;
	  zx_handle_t child_pipe_handle;
	  int child_pipe_fd;
	  status = fdio_pipe_half(&child_pipe_fd, &child_pipe_handle);
	  GTEST_DEATH_TEST_CHECK_(status == ZX_OK);
	  set_read_fd(child_pipe_fd);
	
	  // Set the pipe handle for the child.
	  fdio_spawn_action_t spawn_actions[2] = {};
	  fdio_spawn_action_t* add_handle_action = &spawn_actions[0];
	  add_handle_action->action = FDIO_SPAWN_ACTION_ADD_HANDLE;
	  add_handle_action->h.id = PA_HND(PA_FD, kFuchsiaReadPipeFd);
	  add_handle_action->h.handle = child_pipe_handle;
	
	  // Create a socket pair will be used to receive the child process' stderr.
	  zx::socket stderr_producer_socket;
	  status =
	      zx::socket::create(0, &stderr_producer_socket, &stderr_socket_);
	  GTEST_DEATH_TEST_CHECK_(status >= 0);
	  int stderr_producer_fd = -1;
	  status =
	      fdio_fd_create(stderr_producer_socket.release(), &stderr_producer_fd);
	  GTEST_DEATH_TEST_CHECK_(status >= 0);
	
	  // Make the stderr socket nonblocking.
	  GTEST_DEATH_TEST_CHECK_(fcntl(stderr_producer_fd, F_SETFL, 0) == 0);
	
	  fdio_spawn_action_t* add_stderr_action = &spawn_actions[1];
	  add_stderr_action->action = FDIO_SPAWN_ACTION_CLONE_FD;
	  add_stderr_action->fd.local_fd = stderr_producer_fd;
	  add_stderr_action->fd.target_fd = STDERR_FILENO;
	
	  // Create a child job.
	  zx_handle_t child_job = ZX_HANDLE_INVALID;
	  status = zx_job_create(zx_job_default(), 0, & child_job);
	  GTEST_DEATH_TEST_CHECK_(status == ZX_OK);
	  zx_policy_basic_t policy;
	  policy.condition = ZX_POL_NEW_ANY;
	  policy.policy = ZX_POL_ACTION_ALLOW;
	  status = zx_job_set_policy(
	      child_job, ZX_JOB_POL_RELATIVE, ZX_JOB_POL_BASIC, &policy, 1);
	  GTEST_DEATH_TEST_CHECK_(status == ZX_OK);
	
	  // Create an exception channel attached to the |child_job|, to allow
	  // us to suppress the system default exception handler from firing.
	  status =
	      zx_task_create_exception_channel(
	          child_job, 0, exception_channel_.reset_and_get_address());
	  GTEST_DEATH_TEST_CHECK_(status == ZX_OK);
	
	  // Spawn the child process.
	  status = fdio_spawn_etc(
	      child_job, FDIO_SPAWN_CLONE_ALL, args.Argv()[0], args.Argv(), nullptr,
	      2, spawn_actions, child_process_.reset_and_get_address(), nullptr);
	  GTEST_DEATH_TEST_CHECK_(status == ZX_OK);
	
	  set_spawned(true);
	  return OVERSEE_TEST;
	}
	
	std::string FuchsiaDeathTest::GetErrorLogs() {
	  return captured_stderr_;
	}
	
	#else  // We are neither on Windows, nor on Fuchsia.
	
	// ForkingDeathTest provides implementations for most of the abstract
	// methods of the DeathTest interface.  Only the AssumeRole method is
	// left undefined.
	class ForkingDeathTest : public DeathTestImpl {
	 public:
	  ForkingDeathTest(const char* statement, Matcher<const std::string&> matcher);
	
	  // All of these virtual functions are inherited from DeathTest.
	  int Wait() override;
	
	 protected:
	  void set_child_pid(pid_t child_pid) { child_pid_ = child_pid; }
	
	 private:
	  // PID of child process during death test; 0 in the child process itself.
	  pid_t child_pid_;
	};
	
	// Constructs a ForkingDeathTest.
	ForkingDeathTest::ForkingDeathTest(const char* a_statement,
	                                   Matcher<const std::string&> matcher)
	    : DeathTestImpl(a_statement, std::move(matcher)), child_pid_(-1) {}
	
	// Waits for the child in a death test to exit, returning its exit
	// status, or 0 if no child process exists.  As a side effect, sets the
	// outcome data member.
	int ForkingDeathTest::Wait() {
	  if (!spawned())
	    return 0;
	
	  ReadAndInterpretStatusByte();
	
	  int status_value;
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(waitpid(child_pid_, &status_value, 0));
	  set_status(status_value);
	  return status_value;
	}
	
	// A concrete death test class that forks, then immediately runs the test
	// in the child process.
	class NoExecDeathTest : public ForkingDeathTest {
	 public:
	  NoExecDeathTest(const char* a_statement, Matcher<const std::string&> matcher)
	      : ForkingDeathTest(a_statement, std::move(matcher)) {}
	  TestRole AssumeRole() override;
	};
	
	// The AssumeRole process for a fork-and-run death test.  It implements a
	// straightforward fork, with a simple pipe to transmit the status byte.
	DeathTest::TestRole NoExecDeathTest::AssumeRole() {
	  const size_t thread_count = GetThreadCount();
	  if (thread_count != 1) {
	    GTEST_LOG_(WARNING) << DeathTestThreadWarning(thread_count);
	  }
	
	  int pipe_fd[2];
	  GTEST_DEATH_TEST_CHECK_(pipe(pipe_fd) != -1);
	
	  DeathTest::set_last_death_test_message("");
	  CaptureStderr();
	  // When we fork the process below, the log file buffers are copied, but the
	  // file descriptors are shared.  We flush all log files here so that closing
	  // the file descriptors in the child process doesn't throw off the
	  // synchronization between descriptors and buffers in the parent process.
	  // This is as close to the fork as possible to avoid a race condition in case
	  // there are multiple threads running before the death test, and another
	  // thread writes to the log file.
	  FlushInfoLog();
	
	  const pid_t child_pid = fork();
	  GTEST_DEATH_TEST_CHECK_(child_pid != -1);
	  set_child_pid(child_pid);
	  if (child_pid == 0) {
	    GTEST_DEATH_TEST_CHECK_SYSCALL_(close(pipe_fd[0]));
	    set_write_fd(pipe_fd[1]);
	    // Redirects all logging to stderr in the child process to prevent
	    // concurrent writes to the log files.  We capture stderr in the parent
	    // process and append the child process' output to a log.
	    LogToStderr();
	    // Event forwarding to the listeners of event listener API mush be shut
	    // down in death test subprocesses.
	    GetUnitTestImpl()->listeners()->SuppressEventForwarding();
	    g_in_fast_death_test_child = true;
	    return EXECUTE_TEST;
	  } else {
	    GTEST_DEATH_TEST_CHECK_SYSCALL_(close(pipe_fd[1]));
	    set_read_fd(pipe_fd[0]);
	    set_spawned(true);
	    return OVERSEE_TEST;
	  }
	}
	
	// A concrete death test class that forks and re-executes the main
	// program from the beginning, with command-line flags set that cause
	// only this specific death test to be run.
	class ExecDeathTest : public ForkingDeathTest {
	 public:
	  ExecDeathTest(const char* a_statement, Matcher<const std::string&> matcher,
	                const char* file, int line)
	      : ForkingDeathTest(a_statement, std::move(matcher)),
	        file_(file),
	        line_(line) {}
	  TestRole AssumeRole() override;
	
	 private:
	  static ::std::vector<std::string> GetArgvsForDeathTestChildProcess() {
	    ::std::vector<std::string> args = GetInjectableArgvs();
	#  if defined(GTEST_EXTRA_DEATH_TEST_COMMAND_LINE_ARGS_)
	    ::std::vector<std::string> extra_args =
	        GTEST_EXTRA_DEATH_TEST_COMMAND_LINE_ARGS_();
	    args.insert(args.end(), extra_args.begin(), extra_args.end());
	#  endif  // defined(GTEST_EXTRA_DEATH_TEST_COMMAND_LINE_ARGS_)
	    return args;
	  }
	  // The name of the file in which the death test is located.
	  const char* const file_;
	  // The line number on which the death test is located.
	  const int line_;
	};
	
	// Utility class for accumulating command-line arguments.
	class Arguments {
	 public:
	  Arguments() { args_.push_back(nullptr); }
	
	  ~Arguments() {
	    for (std::vector<char*>::iterator i = args_.begin(); i != args_.end();
	         ++i) {
	      free(*i);
	    }
	  }
	  void AddArgument(const char* argument) {
	    args_.insert(args_.end() - 1, posix::StrDup(argument));
	  }
	
	  template <typename Str>
	  void AddArguments(const ::std::vector<Str>& arguments) {
	    for (typename ::std::vector<Str>::const_iterator i = arguments.begin();
	         i != arguments.end();
	         ++i) {
	      args_.insert(args_.end() - 1, posix::StrDup(i->c_str()));
	    }
	  }
	  char* const* Argv() {
	    return &args_[0];
	  }
	
	 private:
	  std::vector<char*> args_;
	};
	
	// A struct that encompasses the arguments to the child process of a
	// threadsafe-style death test process.
	struct ExecDeathTestArgs {
	  char* const* argv;  // Command-line arguments for the child's call to exec
	  int close_fd;       // File descriptor to close; the read end of a pipe
	};
	
	#  if GTEST_OS_MAC
	inline char** GetEnviron() {
	  // When Google Test is built as a framework on MacOS X, the environ variable
	  // is unavailable. Apple's documentation (man environ) recommends using
	  // _NSGetEnviron() instead.
	  return *_NSGetEnviron();
	}
	#  else
	// Some POSIX platforms expect you to declare environ. extern "C" makes
	// it reside in the global namespace.
	extern "C" char** environ;
	inline char** GetEnviron() { return environ; }
	#  endif  // GTEST_OS_MAC
	
	#  if !GTEST_OS_QNX
	// The main function for a threadsafe-style death test child process.
	// This function is called in a clone()-ed process and thus must avoid
	// any potentially unsafe operations like malloc or libc functions.
	static int ExecDeathTestChildMain(void* child_arg) {
	  ExecDeathTestArgs* const args = static_cast<ExecDeathTestArgs*>(child_arg);
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(close(args->close_fd));
	
	  // We need to execute the test program in the same environment where
	  // it was originally invoked.  Therefore we change to the original
	  // working directory first.
	  const char* const original_dir =
	      UnitTest::GetInstance()->original_working_dir();
	  // We can safely call chdir() as it's a direct system call.
	  if (chdir(original_dir) != 0) {
	    DeathTestAbort(std::string("chdir(\"") + original_dir + "\") failed: " +
	                   GetLastErrnoDescription());
	    return EXIT_FAILURE;
	  }
	
	  // We can safely call execve() as it's a direct system call.  We
	  // cannot use execvp() as it's a libc function and thus potentially
	  // unsafe.  Since execve() doesn't search the PATH, the user must
	  // invoke the test program via a valid path that contains at least
	  // one path separator.
	  execve(args->argv[0], args->argv, GetEnviron());
	  DeathTestAbort(std::string("execve(") + args->argv[0] + ", ...) in " +
	                 original_dir + " failed: " +
	                 GetLastErrnoDescription());
	  return EXIT_FAILURE;
	}
	#  endif  // !GTEST_OS_QNX
	
	#  if GTEST_HAS_CLONE
	// Two utility routines that together determine the direction the stack
	// grows.
	// This could be accomplished more elegantly by a single recursive
	// function, but we want to guard against the unlikely possibility of
	// a smart compiler optimizing the recursion away.
	//
	// GTEST_NO_INLINE_ is required to prevent GCC 4.6 from inlining
	// StackLowerThanAddress into StackGrowsDown, which then doesn't give
	// correct answer.
	static void StackLowerThanAddress(const void* ptr,
	                                  bool* result) GTEST_NO_INLINE_;
	// HWAddressSanitizer add a random tag to the MSB of the local variable address,
	// making comparison result unpredictable.
	GTEST_ATTRIBUTE_NO_SANITIZE_HWADDRESS_
	static void StackLowerThanAddress(const void* ptr, bool* result) {
	  int dummy;
	  *result = (&dummy < ptr);
	}
	
	// Make sure AddressSanitizer does not tamper with the stack here.
	GTEST_ATTRIBUTE_NO_SANITIZE_ADDRESS_
	GTEST_ATTRIBUTE_NO_SANITIZE_HWADDRESS_
	static bool StackGrowsDown() {
	  int dummy;
	  bool result;
	  StackLowerThanAddress(&dummy, &result);
	  return result;
	}
	#  endif  // GTEST_HAS_CLONE
	
	// Spawns a child process with the same executable as the current process in
	// a thread-safe manner and instructs it to run the death test.  The
	// implementation uses fork(2) + exec.  On systems where clone(2) is
	// available, it is used instead, being slightly more thread-safe.  On QNX,
	// fork supports only single-threaded environments, so this function uses
	// spawn(2) there instead.  The function dies with an error message if
	// anything goes wrong.
	static pid_t ExecDeathTestSpawnChild(char* const* argv, int close_fd) {
	  ExecDeathTestArgs args = { argv, close_fd };
	  pid_t child_pid = -1;
	
	#  if GTEST_OS_QNX
	  // Obtains the current directory and sets it to be closed in the child
	  // process.
	  const int cwd_fd = open(".", O_RDONLY);
	  GTEST_DEATH_TEST_CHECK_(cwd_fd != -1);
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(fcntl(cwd_fd, F_SETFD, FD_CLOEXEC));
	  // We need to execute the test program in the same environment where
	  // it was originally invoked.  Therefore we change to the original
	  // working directory first.
	  const char* const original_dir =
	      UnitTest::GetInstance()->original_working_dir();
	  // We can safely call chdir() as it's a direct system call.
	  if (chdir(original_dir) != 0) {
	    DeathTestAbort(std::string("chdir(\"") + original_dir + "\") failed: " +
	                   GetLastErrnoDescription());
	    return EXIT_FAILURE;
	  }
	
	  int fd_flags;
	  // Set close_fd to be closed after spawn.
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(fd_flags = fcntl(close_fd, F_GETFD));
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(fcntl(close_fd, F_SETFD,
	                                        fd_flags | FD_CLOEXEC));
	  struct inheritance inherit = {0};
	  // spawn is a system call.
	  child_pid =
	      spawn(args.argv[0], 0, nullptr, &inherit, args.argv, GetEnviron());
	  // Restores the current working directory.
	  GTEST_DEATH_TEST_CHECK_(fchdir(cwd_fd) != -1);
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(close(cwd_fd));
	
	#  else   // GTEST_OS_QNX
	#   if GTEST_OS_LINUX
	  // When a SIGPROF signal is received while fork() or clone() are executing,
	  // the process may hang. To avoid this, we ignore SIGPROF here and re-enable
	  // it after the call to fork()/clone() is complete.
	  struct sigaction saved_sigprof_action;
	  struct sigaction ignore_sigprof_action;
	  memset(&ignore_sigprof_action, 0, sizeof(ignore_sigprof_action));
	  sigemptyset(&ignore_sigprof_action.sa_mask);
	  ignore_sigprof_action.sa_handler = SIG_IGN;
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(sigaction(
	      SIGPROF, &ignore_sigprof_action, &saved_sigprof_action));
	#   endif  // GTEST_OS_LINUX
	
	#   if GTEST_HAS_CLONE
	  const bool use_fork = GTEST_FLAG(death_test_use_fork);
	
	  if (!use_fork) {
	    static const bool stack_grows_down = StackGrowsDown();
	    const auto stack_size = static_cast<size_t>(getpagesize());
	    // MMAP_ANONYMOUS is not defined on Mac, so we use MAP_ANON instead.
	    void* const stack = mmap(nullptr, stack_size, PROT_READ | PROT_WRITE,
	                             MAP_ANON | MAP_PRIVATE, -1, 0);
	    GTEST_DEATH_TEST_CHECK_(stack != MAP_FAILED);
	
	    // Maximum stack alignment in bytes:  For a downward-growing stack, this
	    // amount is subtracted from size of the stack space to get an address
	    // that is within the stack space and is aligned on all systems we care
	    // about.  As far as I know there is no ABI with stack alignment greater
	    // than 64.  We assume stack and stack_size already have alignment of
	    // kMaxStackAlignment.
	    const size_t kMaxStackAlignment = 64;
	    void* const stack_top =
	        static_cast<char*>(stack) +
	            (stack_grows_down ? stack_size - kMaxStackAlignment : 0);
	    GTEST_DEATH_TEST_CHECK_(
	        static_cast<size_t>(stack_size) > kMaxStackAlignment &&
	        reinterpret_cast<uintptr_t>(stack_top) % kMaxStackAlignment == 0);
	
	    child_pid = clone(&ExecDeathTestChildMain, stack_top, SIGCHLD, &args);
	
	    GTEST_DEATH_TEST_CHECK_(munmap(stack, stack_size) != -1);
	  }
	#   else
	  const bool use_fork = true;
	#   endif  // GTEST_HAS_CLONE
	
	  if (use_fork && (child_pid = fork()) == 0) {
	      ExecDeathTestChildMain(&args);
	      _exit(0);
	  }
	#  endif  // GTEST_OS_QNX
	#  if GTEST_OS_LINUX
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(
	      sigaction(SIGPROF, &saved_sigprof_action, nullptr));
	#  endif  // GTEST_OS_LINUX
	
	  GTEST_DEATH_TEST_CHECK_(child_pid != -1);
	  return child_pid;
	}
	
	// The AssumeRole process for a fork-and-exec death test.  It re-executes the
	// main program from the beginning, setting the --gtest_filter
	// and --gtest_internal_run_death_test flags to cause only the current
	// death test to be re-run.
	DeathTest::TestRole ExecDeathTest::AssumeRole() {
	  const UnitTestImpl* const impl = GetUnitTestImpl();
	  const InternalRunDeathTestFlag* const flag =
	      impl->internal_run_death_test_flag();
	  const TestInfo* const info = impl->current_test_info();
	  const int death_test_index = info->result()->death_test_count();
	
	  if (flag != nullptr) {
	    set_write_fd(flag->write_fd());
	    return EXECUTE_TEST;
	  }
	
	  int pipe_fd[2];
	  GTEST_DEATH_TEST_CHECK_(pipe(pipe_fd) != -1);
	  // Clear the close-on-exec flag on the write end of the pipe, lest
	  // it be closed when the child process does an exec:
	  GTEST_DEATH_TEST_CHECK_(fcntl(pipe_fd[1], F_SETFD, 0) != -1);
	
	  const std::string filter_flag = std::string("--") + GTEST_FLAG_PREFIX_ +
	                                  kFilterFlag + "=" + info->test_suite_name() +
	                                  "." + info->name();
	  const std::string internal_flag =
	      std::string("--") + GTEST_FLAG_PREFIX_ + kInternalRunDeathTestFlag + "="
	      + file_ + "|" + StreamableToString(line_) + "|"
	      + StreamableToString(death_test_index) + "|"
	      + StreamableToString(pipe_fd[1]);
	  Arguments args;
	  args.AddArguments(GetArgvsForDeathTestChildProcess());
	  args.AddArgument(filter_flag.c_str());
	  args.AddArgument(internal_flag.c_str());
	
	  DeathTest::set_last_death_test_message("");
	
	  CaptureStderr();
	  // See the comment in NoExecDeathTest::AssumeRole for why the next line
	  // is necessary.
	  FlushInfoLog();
	
	  const pid_t child_pid = ExecDeathTestSpawnChild(args.Argv(), pipe_fd[0]);
	  GTEST_DEATH_TEST_CHECK_SYSCALL_(close(pipe_fd[1]));
	  set_child_pid(child_pid);
	  set_read_fd(pipe_fd[0]);
	  set_spawned(true);
	  return OVERSEE_TEST;
	}
	
	# endif  // !GTEST_OS_WINDOWS
	
	// Creates a concrete DeathTest-derived class that depends on the
	// --gtest_death_test_style flag, and sets the pointer pointed to
	// by the "test" argument to its address.  If the test should be
	// skipped, sets that pointer to NULL.  Returns true, unless the
	// flag is set to an invalid value.
	bool DefaultDeathTestFactory::Create(const char* statement,
	                                     Matcher<const std::string&> matcher,
	                                     const char* file, int line,
	                                     DeathTest** test) {
	  UnitTestImpl* const impl = GetUnitTestImpl();
	  const InternalRunDeathTestFlag* const flag =
	      impl->internal_run_death_test_flag();
	  const int death_test_index = impl->current_test_info()
	      ->increment_death_test_count();
	
	  if (flag != nullptr) {
	    if (death_test_index > flag->index()) {
	      DeathTest::set_last_death_test_message(
	          "Death test count (" + StreamableToString(death_test_index)
	          + ") somehow exceeded expected maximum ("
	          + StreamableToString(flag->index()) + ")");
	      return false;
	    }
	
	    if (!(flag->file() == file && flag->line() == line &&
	          flag->index() == death_test_index)) {
	      *test = nullptr;
	      return true;
	    }
	  }
	
	# if GTEST_OS_WINDOWS
	
	  if (GTEST_FLAG(death_test_style) == "threadsafe" ||
	      GTEST_FLAG(death_test_style) == "fast") {
	    *test = new WindowsDeathTest(statement, std::move(matcher), file, line);
	  }
	
	# elif GTEST_OS_FUCHSIA
	
	  if (GTEST_FLAG(death_test_style) == "threadsafe" ||
	      GTEST_FLAG(death_test_style) == "fast") {
	    *test = new FuchsiaDeathTest(statement, std::move(matcher), file, line);
	  }
	
	# else
	
	  if (GTEST_FLAG(death_test_style) == "threadsafe") {
	    *test = new ExecDeathTest(statement, std::move(matcher), file, line);
	  } else if (GTEST_FLAG(death_test_style) == "fast") {
	    *test = new NoExecDeathTest(statement, std::move(matcher));
	  }
	
	# endif  // GTEST_OS_WINDOWS
	
	  else {  // NOLINT - this is more readable than unbalanced brackets inside #if.
	    DeathTest::set_last_death_test_message(
	        "Unknown death test style \"" + GTEST_FLAG(death_test_style)
	        + "\" encountered");
	    return false;
	  }
	
	  return true;
	}
	
	# if GTEST_OS_WINDOWS
	// Recreates the pipe and event handles from the provided parameters,
	// signals the event, and returns a file descriptor wrapped around the pipe
	// handle. This function is called in the child process only.
	static int GetStatusFileDescriptor(unsigned int parent_process_id,
	                            size_t write_handle_as_size_t,
	                            size_t event_handle_as_size_t) {
	  AutoHandle parent_process_handle(::OpenProcess(PROCESS_DUP_HANDLE,
	                                                   FALSE,  // Non-inheritable.
	                                                   parent_process_id));
	  if (parent_process_handle.Get() == INVALID_HANDLE_VALUE) {
	    DeathTestAbort("Unable to open parent process " +
	                   StreamableToString(parent_process_id));
	  }
	
	  GTEST_CHECK_(sizeof(HANDLE) <= sizeof(size_t));
	
	  const HANDLE write_handle =
	      reinterpret_cast<HANDLE>(write_handle_as_size_t);
	  HANDLE dup_write_handle;
	
	  // The newly initialized handle is accessible only in the parent
	  // process. To obtain one accessible within the child, we need to use
	  // DuplicateHandle.
	  if (!::DuplicateHandle(parent_process_handle.Get(), write_handle,
	                         ::GetCurrentProcess(), &dup_write_handle,
	                         0x0,    // Requested privileges ignored since
	                                 // DUPLICATE_SAME_ACCESS is used.
	                         FALSE,  // Request non-inheritable handler.
	                         DUPLICATE_SAME_ACCESS)) {
	    DeathTestAbort("Unable to duplicate the pipe handle " +
	                   StreamableToString(write_handle_as_size_t) +
	                   " from the parent process " +
	                   StreamableToString(parent_process_id));
	  }
	
	  const HANDLE event_handle = reinterpret_cast<HANDLE>(event_handle_as_size_t);
	  HANDLE dup_event_handle;
	
	  if (!::DuplicateHandle(parent_process_handle.Get(), event_handle,
	                         ::GetCurrentProcess(), &dup_event_handle,
	                         0x0,
	                         FALSE,
	                         DUPLICATE_SAME_ACCESS)) {
	    DeathTestAbort("Unable to duplicate the event handle " +
	                   StreamableToString(event_handle_as_size_t) +
	                   " from the parent process " +
	                   StreamableToString(parent_process_id));
	  }
	
	  const int write_fd =
	      ::_open_osfhandle(reinterpret_cast<intptr_t>(dup_write_handle), O_APPEND);
	  if (write_fd == -1) {
	    DeathTestAbort("Unable to convert pipe handle " +
	                   StreamableToString(write_handle_as_size_t) +
	                   " to a file descriptor");
	  }
	
	  // Signals the parent that the write end of the pipe has been acquired
	  // so the parent can release its own write end.
	  ::SetEvent(dup_event_handle);
	
	  return write_fd;
	}
	# endif  // GTEST_OS_WINDOWS
	
	// Returns a newly created InternalRunDeathTestFlag object with fields
	// initialized from the GTEST_FLAG(internal_run_death_test) flag if
	// the flag is specified; otherwise returns NULL.
	InternalRunDeathTestFlag* ParseInternalRunDeathTestFlag() {
	  if (GTEST_FLAG(internal_run_death_test) == "") return nullptr;
	
	  // GTEST_HAS_DEATH_TEST implies that we have ::std::string, so we
	  // can use it here.
	  int line = -1;
	  int index = -1;
	  ::std::vector< ::std::string> fields;
	  SplitString(GTEST_FLAG(internal_run_death_test).c_str(), '|', &fields);
	  int write_fd = -1;
	
	# if GTEST_OS_WINDOWS
	
	  unsigned int parent_process_id = 0;
	  size_t write_handle_as_size_t = 0;
	  size_t event_handle_as_size_t = 0;
	
	  if (fields.size() != 6
	      || !ParseNaturalNumber(fields[1], &line)
	      || !ParseNaturalNumber(fields[2], &index)
	      || !ParseNaturalNumber(fields[3], &parent_process_id)
	      || !ParseNaturalNumber(fields[4], &write_handle_as_size_t)
	      || !ParseNaturalNumber(fields[5], &event_handle_as_size_t)) {
	    DeathTestAbort("Bad --gtest_internal_run_death_test flag: " +
	                   GTEST_FLAG(internal_run_death_test));
	  }
	  write_fd = GetStatusFileDescriptor(parent_process_id,
	                                     write_handle_as_size_t,
	                                     event_handle_as_size_t);
	
	# elif GTEST_OS_FUCHSIA
	
	  if (fields.size() != 3
	      || !ParseNaturalNumber(fields[1], &line)
	      || !ParseNaturalNumber(fields[2], &index)) {
	    DeathTestAbort("Bad --gtest_internal_run_death_test flag: "
	        + GTEST_FLAG(internal_run_death_test));
	  }
	
	# else
	
	  if (fields.size() != 4
	      || !ParseNaturalNumber(fields[1], &line)
	      || !ParseNaturalNumber(fields[2], &index)
	      || !ParseNaturalNumber(fields[3], &write_fd)) {
	    DeathTestAbort("Bad --gtest_internal_run_death_test flag: "
	        + GTEST_FLAG(internal_run_death_test));
	  }
	
	# endif  // GTEST_OS_WINDOWS
	
	  return new InternalRunDeathTestFlag(fields[0], line, index, write_fd);
	}
	
	}  // namespace internal
	
	#endif  // GTEST_HAS_DEATH_TEST
	
	}  // namespace testing