duckstation

gtest-death-test.cc (62191B)

---

 // 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 and only 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() * 2);
     // 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