duckstation

gtest-port.cc (46564B)

---

 // Copyright 2008, 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.
 
 
 #include "gtest/internal/gtest-port.h"
 
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <cstdint>
 #include <fstream>
 #include <memory>
 
 #if GTEST_OS_WINDOWS
 # include <windows.h>
 # include <io.h>
 # include <sys/stat.h>
 # include <map>  // Used in ThreadLocal.
 # ifdef _MSC_VER
 #  include <crtdbg.h>
 # endif  // _MSC_VER
 #else
 # include <unistd.h>
 #endif  // GTEST_OS_WINDOWS
 
 #if GTEST_OS_MAC
 # include <mach/mach_init.h>
 # include <mach/task.h>
 # include <mach/vm_map.h>
 #endif  // GTEST_OS_MAC
 
 #if GTEST_OS_DRAGONFLY || GTEST_OS_FREEBSD || GTEST_OS_GNU_KFREEBSD || \
     GTEST_OS_NETBSD || GTEST_OS_OPENBSD
 # include <sys/sysctl.h>
 # if GTEST_OS_DRAGONFLY || GTEST_OS_FREEBSD || GTEST_OS_GNU_KFREEBSD
 #  include <sys/user.h>
 # endif
 #endif
 
 #if GTEST_OS_QNX
 # include <devctl.h>
 # include <fcntl.h>
 # include <sys/procfs.h>
 #endif  // GTEST_OS_QNX
 
 #if GTEST_OS_AIX
 # include <procinfo.h>
 # include <sys/types.h>
 #endif  // GTEST_OS_AIX
 
 #if GTEST_OS_FUCHSIA
 # include <zircon/process.h>
 # include <zircon/syscalls.h>
 #endif  // GTEST_OS_FUCHSIA
 
 #include "gtest/gtest-spi.h"
 #include "gtest/gtest-message.h"
 #include "gtest/internal/gtest-internal.h"
 #include "gtest/internal/gtest-string.h"
 #include "src/gtest-internal-inl.h"
 
 namespace testing {
 namespace internal {
 
 #if defined(_MSC_VER) || defined(__BORLANDC__)
 // MSVC and C++Builder do not provide a definition of STDERR_FILENO.
 const int kStdOutFileno = 1;
 const int kStdErrFileno = 2;
 #else
 const int kStdOutFileno = STDOUT_FILENO;
 const int kStdErrFileno = STDERR_FILENO;
 #endif  // _MSC_VER
 
 #if GTEST_OS_LINUX
 
 namespace {
 template <typename T>
 T ReadProcFileField(const std::string& filename, int field) {
   std::string dummy;
   std::ifstream file(filename.c_str());
   while (field-- > 0) {
     file >> dummy;
   }
   T output = 0;
   file >> output;
   return output;
 }
 }  // namespace
 
 // Returns the number of active threads, or 0 when there is an error.
 size_t GetThreadCount() {
   const std::string filename =
       (Message() << "/proc/" << getpid() << "/stat").GetString();
   return ReadProcFileField<size_t>(filename, 19);
 }
 
 #elif GTEST_OS_MAC
 
 size_t GetThreadCount() {
   const task_t task = mach_task_self();
   mach_msg_type_number_t thread_count;
   thread_act_array_t thread_list;
   const kern_return_t status = task_threads(task, &thread_list, &thread_count);
   if (status == KERN_SUCCESS) {
     // task_threads allocates resources in thread_list and we need to free them
     // to avoid leaks.
     vm_deallocate(task,
                   reinterpret_cast<vm_address_t>(thread_list),
                   sizeof(thread_t) * thread_count);
     return static_cast<size_t>(thread_count);
   } else {
     return 0;
   }
 }
 
 #elif GTEST_OS_DRAGONFLY || GTEST_OS_FREEBSD || GTEST_OS_GNU_KFREEBSD || \
       GTEST_OS_NETBSD
 
 #if GTEST_OS_NETBSD
 #undef KERN_PROC
 #define KERN_PROC KERN_PROC2
 #define kinfo_proc kinfo_proc2
 #endif
 
 #if GTEST_OS_DRAGONFLY
 #define KP_NLWP(kp) (kp.kp_nthreads)
 #elif GTEST_OS_FREEBSD || GTEST_OS_GNU_KFREEBSD
 #define KP_NLWP(kp) (kp.ki_numthreads)
 #elif GTEST_OS_NETBSD
 #define KP_NLWP(kp) (kp.p_nlwps)
 #endif
 
 // Returns the number of threads running in the process, or 0 to indicate that
 // we cannot detect it.
 size_t GetThreadCount() {
   int mib[] = {
     CTL_KERN,
     KERN_PROC,
     KERN_PROC_PID,
     getpid(),
 #if GTEST_OS_NETBSD
     sizeof(struct kinfo_proc),
     1,
 #endif
   };
   u_int miblen = sizeof(mib) / sizeof(mib[0]);
   struct kinfo_proc info;
   size_t size = sizeof(info);
   if (sysctl(mib, miblen, &info, &size, NULL, 0)) {
     return 0;
   }
   return static_cast<size_t>(KP_NLWP(info));
 }
 #elif GTEST_OS_OPENBSD
 
 // Returns the number of threads running in the process, or 0 to indicate that
 // we cannot detect it.
 size_t GetThreadCount() {
   int mib[] = {
     CTL_KERN,
     KERN_PROC,
     KERN_PROC_PID | KERN_PROC_SHOW_THREADS,
     getpid(),
     sizeof(struct kinfo_proc),
     0,
   };
   u_int miblen = sizeof(mib) / sizeof(mib[0]);
 
   // get number of structs
   size_t size;
   if (sysctl(mib, miblen, NULL, &size, NULL, 0)) {
     return 0;
   }
   mib[5] = size / mib[4];
 
   // populate array of structs
   struct kinfo_proc info[mib[5]];
   if (sysctl(mib, miblen, &info, &size, NULL, 0)) {
     return 0;
   }
 
   // exclude empty members
   int nthreads = 0;
   for (int i = 0; i < size / mib[4]; i++) {
     if (info[i].p_tid != -1)
       nthreads++;
   }
   return nthreads;
 }
 
 #elif GTEST_OS_QNX
 
 // Returns the number of threads running in the process, or 0 to indicate that
 // we cannot detect it.
 size_t GetThreadCount() {
   const int fd = open("/proc/self/as", O_RDONLY);
   if (fd < 0) {
     return 0;
   }
   procfs_info process_info;
   const int status =
       devctl(fd, DCMD_PROC_INFO, &process_info, sizeof(process_info), nullptr);
   close(fd);
   if (status == EOK) {
     return static_cast<size_t>(process_info.num_threads);
   } else {
     return 0;
   }
 }
 
 #elif GTEST_OS_AIX
 
 size_t GetThreadCount() {
   struct procentry64 entry;
   pid_t pid = getpid();
   int status = getprocs64(&entry, sizeof(entry), nullptr, 0, &pid, 1);
   if (status == 1) {
     return entry.pi_thcount;
   } else {
     return 0;
   }
 }
 
 #elif GTEST_OS_FUCHSIA
 
 size_t GetThreadCount() {
   int dummy_buffer;
   size_t avail;
   zx_status_t status = zx_object_get_info(
       zx_process_self(),
       ZX_INFO_PROCESS_THREADS,
       &dummy_buffer,
       0,
       nullptr,
       &avail);
   if (status == ZX_OK) {
     return avail;
   } else {
     return 0;
   }
 }
 
 #else
 
 size_t GetThreadCount() {
   // There's no portable way to detect the number of threads, so we just
   // return 0 to indicate that we cannot detect it.
   return 0;
 }
 
 #endif  // GTEST_OS_LINUX
 
 #if GTEST_IS_THREADSAFE && GTEST_OS_WINDOWS
 
 void SleepMilliseconds(int n) {
   ::Sleep(static_cast<DWORD>(n));
 }
 
 AutoHandle::AutoHandle()
     : handle_(INVALID_HANDLE_VALUE) {}
 
 AutoHandle::AutoHandle(Handle handle)
     : handle_(handle) {}
 
 AutoHandle::~AutoHandle() {
   Reset();
 }
 
 AutoHandle::Handle AutoHandle::Get() const {
   return handle_;
 }
 
 void AutoHandle::Reset() {
   Reset(INVALID_HANDLE_VALUE);
 }
 
 void AutoHandle::Reset(HANDLE handle) {
   // Resetting with the same handle we already own is invalid.
   if (handle_ != handle) {
     if (IsCloseable()) {
       ::CloseHandle(handle_);
     }
     handle_ = handle;
   } else {
     GTEST_CHECK_(!IsCloseable())
         << "Resetting a valid handle to itself is likely a programmer error "
             "and thus not allowed.";
   }
 }
 
 bool AutoHandle::IsCloseable() const {
   // Different Windows APIs may use either of these values to represent an
   // invalid handle.
   return handle_ != nullptr && handle_ != INVALID_HANDLE_VALUE;
 }
 
 Notification::Notification()
     : event_(::CreateEvent(nullptr,     // Default security attributes.
                            TRUE,        // Do not reset automatically.
                            FALSE,       // Initially unset.
                            nullptr)) {  // Anonymous event.
   GTEST_CHECK_(event_.Get() != nullptr);
 }
 
 void Notification::Notify() {
   GTEST_CHECK_(::SetEvent(event_.Get()) != FALSE);
 }
 
 void Notification::WaitForNotification() {
   GTEST_CHECK_(
       ::WaitForSingleObject(event_.Get(), INFINITE) == WAIT_OBJECT_0);
 }
 
 Mutex::Mutex()
     : owner_thread_id_(0),
       type_(kDynamic),
       critical_section_init_phase_(0),
       critical_section_(new CRITICAL_SECTION) {
   ::InitializeCriticalSection(critical_section_);
 }
 
 Mutex::~Mutex() {
   // Static mutexes are leaked intentionally. It is not thread-safe to try
   // to clean them up.
   if (type_ == kDynamic) {
     ::DeleteCriticalSection(critical_section_);
     delete critical_section_;
     critical_section_ = nullptr;
   }
 }
 
 void Mutex::Lock() {
   ThreadSafeLazyInit();
   ::EnterCriticalSection(critical_section_);
   owner_thread_id_ = ::GetCurrentThreadId();
 }
 
 void Mutex::Unlock() {
   ThreadSafeLazyInit();
   // We don't protect writing to owner_thread_id_ here, as it's the
   // caller's responsibility to ensure that the current thread holds the
   // mutex when this is called.
   owner_thread_id_ = 0;
   ::LeaveCriticalSection(critical_section_);
 }
 
 // Does nothing if the current thread holds the mutex. Otherwise, crashes
 // with high probability.
 void Mutex::AssertHeld() {
   ThreadSafeLazyInit();
   GTEST_CHECK_(owner_thread_id_ == ::GetCurrentThreadId())
       << "The current thread is not holding the mutex @" << this;
 }
 
 namespace {
 
 #ifdef _MSC_VER
 // Use the RAII idiom to flag mem allocs that are intentionally never
 // deallocated. The motivation is to silence the false positive mem leaks
 // that are reported by the debug version of MS's CRT which can only detect
 // if an alloc is missing a matching deallocation.
 // Example:
 //    MemoryIsNotDeallocated memory_is_not_deallocated;
 //    critical_section_ = new CRITICAL_SECTION;
 //
 class MemoryIsNotDeallocated
 {
  public:
   MemoryIsNotDeallocated() : old_crtdbg_flag_(0) {
     old_crtdbg_flag_ = _CrtSetDbgFlag(_CRTDBG_REPORT_FLAG);
     // Set heap allocation block type to _IGNORE_BLOCK so that MS debug CRT
     // doesn't report mem leak if there's no matching deallocation.
     _CrtSetDbgFlag(old_crtdbg_flag_ & ~_CRTDBG_ALLOC_MEM_DF);
   }
 
   ~MemoryIsNotDeallocated() {
     // Restore the original _CRTDBG_ALLOC_MEM_DF flag
     _CrtSetDbgFlag(old_crtdbg_flag_);
   }
 
  private:
   int old_crtdbg_flag_;
 
   GTEST_DISALLOW_COPY_AND_ASSIGN_(MemoryIsNotDeallocated);
 };
 #endif  // _MSC_VER
 
 }  // namespace
 
 // Initializes owner_thread_id_ and critical_section_ in static mutexes.
 void Mutex::ThreadSafeLazyInit() {
   // Dynamic mutexes are initialized in the constructor.
   if (type_ == kStatic) {
     switch (
         ::InterlockedCompareExchange(&critical_section_init_phase_, 1L, 0L)) {
       case 0:
         // If critical_section_init_phase_ was 0 before the exchange, we
         // are the first to test it and need to perform the initialization.
         owner_thread_id_ = 0;
         {
           // Use RAII to flag that following mem alloc is never deallocated.
 #ifdef _MSC_VER
           MemoryIsNotDeallocated memory_is_not_deallocated;
 #endif  // _MSC_VER
           critical_section_ = new CRITICAL_SECTION;
         }
         ::InitializeCriticalSection(critical_section_);
         // Updates the critical_section_init_phase_ to 2 to signal
         // initialization complete.
         GTEST_CHECK_(::InterlockedCompareExchange(
                           &critical_section_init_phase_, 2L, 1L) ==
                       1L);
         break;
       case 1:
         // Somebody else is already initializing the mutex; spin until they
         // are done.
         while (::InterlockedCompareExchange(&critical_section_init_phase_,
                                             2L,
                                             2L) != 2L) {
           // Possibly yields the rest of the thread's time slice to other
           // threads.
           ::Sleep(0);
         }
         break;
 
       case 2:
         break;  // The mutex is already initialized and ready for use.
 
       default:
         GTEST_CHECK_(false)
             << "Unexpected value of critical_section_init_phase_ "
             << "while initializing a static mutex.";
     }
   }
 }
 
 namespace {
 
 class ThreadWithParamSupport : public ThreadWithParamBase {
  public:
   static HANDLE CreateThread(Runnable* runnable,
                              Notification* thread_can_start) {
     ThreadMainParam* param = new ThreadMainParam(runnable, thread_can_start);
     DWORD thread_id;
     HANDLE thread_handle = ::CreateThread(
         nullptr,  // Default security.
         0,        // Default stack size.
         &ThreadWithParamSupport::ThreadMain,
         param,        // Parameter to ThreadMainStatic
         0x0,          // Default creation flags.
         &thread_id);  // Need a valid pointer for the call to work under Win98.
     GTEST_CHECK_(thread_handle != nullptr)
         << "CreateThread failed with error " << ::GetLastError() << ".";
     if (thread_handle == nullptr) {
       delete param;
     }
     return thread_handle;
   }
 
  private:
   struct ThreadMainParam {
     ThreadMainParam(Runnable* runnable, Notification* thread_can_start)
         : runnable_(runnable),
           thread_can_start_(thread_can_start) {
     }
     std::unique_ptr<Runnable> runnable_;
     // Does not own.
     Notification* thread_can_start_;
   };
 
   static DWORD WINAPI ThreadMain(void* ptr) {
     // Transfers ownership.
     std::unique_ptr<ThreadMainParam> param(static_cast<ThreadMainParam*>(ptr));
     if (param->thread_can_start_ != nullptr)
       param->thread_can_start_->WaitForNotification();
     param->runnable_->Run();
     return 0;
   }
 
   // Prohibit instantiation.
   ThreadWithParamSupport();
 
   GTEST_DISALLOW_COPY_AND_ASSIGN_(ThreadWithParamSupport);
 };
 
 }  // namespace
 
 ThreadWithParamBase::ThreadWithParamBase(Runnable *runnable,
                                          Notification* thread_can_start)
       : thread_(ThreadWithParamSupport::CreateThread(runnable,
                                                      thread_can_start)) {
 }
 
 ThreadWithParamBase::~ThreadWithParamBase() {
   Join();
 }
 
 void ThreadWithParamBase::Join() {
   GTEST_CHECK_(::WaitForSingleObject(thread_.Get(), INFINITE) == WAIT_OBJECT_0)
       << "Failed to join the thread with error " << ::GetLastError() << ".";
 }
 
 // Maps a thread to a set of ThreadIdToThreadLocals that have values
 // instantiated on that thread and notifies them when the thread exits.  A
 // ThreadLocal instance is expected to persist until all threads it has
 // values on have terminated.
 class ThreadLocalRegistryImpl {
  public:
   // Registers thread_local_instance as having value on the current thread.
   // Returns a value that can be used to identify the thread from other threads.
   static ThreadLocalValueHolderBase* GetValueOnCurrentThread(
       const ThreadLocalBase* thread_local_instance) {
 #ifdef _MSC_VER
     MemoryIsNotDeallocated memory_is_not_deallocated;
 #endif  // _MSC_VER
     DWORD current_thread = ::GetCurrentThreadId();
     MutexLock lock(&mutex_);
     ThreadIdToThreadLocals* const thread_to_thread_locals =
         GetThreadLocalsMapLocked();
     ThreadIdToThreadLocals::iterator thread_local_pos =
         thread_to_thread_locals->find(current_thread);
     if (thread_local_pos == thread_to_thread_locals->end()) {
       thread_local_pos = thread_to_thread_locals->insert(
           std::make_pair(current_thread, ThreadLocalValues())).first;
       StartWatcherThreadFor(current_thread);
     }
     ThreadLocalValues& thread_local_values = thread_local_pos->second;
     ThreadLocalValues::iterator value_pos =
         thread_local_values.find(thread_local_instance);
     if (value_pos == thread_local_values.end()) {
       value_pos =
           thread_local_values
               .insert(std::make_pair(
                   thread_local_instance,
                   std::shared_ptr<ThreadLocalValueHolderBase>(
                       thread_local_instance->NewValueForCurrentThread())))
               .first;
     }
     return value_pos->second.get();
   }
 
   static void OnThreadLocalDestroyed(
       const ThreadLocalBase* thread_local_instance) {
     std::vector<std::shared_ptr<ThreadLocalValueHolderBase> > value_holders;
     // Clean up the ThreadLocalValues data structure while holding the lock, but
     // defer the destruction of the ThreadLocalValueHolderBases.
     {
       MutexLock lock(&mutex_);
       ThreadIdToThreadLocals* const thread_to_thread_locals =
           GetThreadLocalsMapLocked();
       for (ThreadIdToThreadLocals::iterator it =
           thread_to_thread_locals->begin();
           it != thread_to_thread_locals->end();
           ++it) {
         ThreadLocalValues& thread_local_values = it->second;
         ThreadLocalValues::iterator value_pos =
             thread_local_values.find(thread_local_instance);
         if (value_pos != thread_local_values.end()) {
           value_holders.push_back(value_pos->second);
           thread_local_values.erase(value_pos);
           // This 'if' can only be successful at most once, so theoretically we
           // could break out of the loop here, but we don't bother doing so.
         }
       }
     }
     // Outside the lock, let the destructor for 'value_holders' deallocate the
     // ThreadLocalValueHolderBases.
   }
 
   static void OnThreadExit(DWORD thread_id) {
     GTEST_CHECK_(thread_id != 0) << ::GetLastError();
     std::vector<std::shared_ptr<ThreadLocalValueHolderBase> > value_holders;
     // Clean up the ThreadIdToThreadLocals data structure while holding the
     // lock, but defer the destruction of the ThreadLocalValueHolderBases.
     {
       MutexLock lock(&mutex_);
       ThreadIdToThreadLocals* const thread_to_thread_locals =
           GetThreadLocalsMapLocked();
       ThreadIdToThreadLocals::iterator thread_local_pos =
           thread_to_thread_locals->find(thread_id);
       if (thread_local_pos != thread_to_thread_locals->end()) {
         ThreadLocalValues& thread_local_values = thread_local_pos->second;
         for (ThreadLocalValues::iterator value_pos =
             thread_local_values.begin();
             value_pos != thread_local_values.end();
             ++value_pos) {
           value_holders.push_back(value_pos->second);
         }
         thread_to_thread_locals->erase(thread_local_pos);
       }
     }
     // Outside the lock, let the destructor for 'value_holders' deallocate the
     // ThreadLocalValueHolderBases.
   }
 
  private:
   // In a particular thread, maps a ThreadLocal object to its value.
   typedef std::map<const ThreadLocalBase*,
                    std::shared_ptr<ThreadLocalValueHolderBase> >
       ThreadLocalValues;
   // Stores all ThreadIdToThreadLocals having values in a thread, indexed by
   // thread's ID.
   typedef std::map<DWORD, ThreadLocalValues> ThreadIdToThreadLocals;
 
   // Holds the thread id and thread handle that we pass from
   // StartWatcherThreadFor to WatcherThreadFunc.
   typedef std::pair<DWORD, HANDLE> ThreadIdAndHandle;
 
   static void StartWatcherThreadFor(DWORD thread_id) {
     // The returned handle will be kept in thread_map and closed by
     // watcher_thread in WatcherThreadFunc.
     HANDLE thread = ::OpenThread(SYNCHRONIZE | THREAD_QUERY_INFORMATION,
                                  FALSE,
                                  thread_id);
     GTEST_CHECK_(thread != nullptr);
     // We need to pass a valid thread ID pointer into CreateThread for it
     // to work correctly under Win98.
     DWORD watcher_thread_id;
     HANDLE watcher_thread = ::CreateThread(
         nullptr,  // Default security.
         0,        // Default stack size
         &ThreadLocalRegistryImpl::WatcherThreadFunc,
         reinterpret_cast<LPVOID>(new ThreadIdAndHandle(thread_id, thread)),
         CREATE_SUSPENDED, &watcher_thread_id);
     GTEST_CHECK_(watcher_thread != nullptr);
     // Give the watcher thread the same priority as ours to avoid being
     // blocked by it.
     ::SetThreadPriority(watcher_thread,
                         ::GetThreadPriority(::GetCurrentThread()));
     ::ResumeThread(watcher_thread);
     ::CloseHandle(watcher_thread);
   }
 
   // Monitors exit from a given thread and notifies those
   // ThreadIdToThreadLocals about thread termination.
   static DWORD WINAPI WatcherThreadFunc(LPVOID param) {
     const ThreadIdAndHandle* tah =
         reinterpret_cast<const ThreadIdAndHandle*>(param);
     GTEST_CHECK_(
         ::WaitForSingleObject(tah->second, INFINITE) == WAIT_OBJECT_0);
     OnThreadExit(tah->first);
     ::CloseHandle(tah->second);
     delete tah;
     return 0;
   }
 
   // Returns map of thread local instances.
   static ThreadIdToThreadLocals* GetThreadLocalsMapLocked() {
     mutex_.AssertHeld();
 #ifdef _MSC_VER
     MemoryIsNotDeallocated memory_is_not_deallocated;
 #endif  // _MSC_VER
     static ThreadIdToThreadLocals* map = new ThreadIdToThreadLocals();
     return map;
   }
 
   // Protects access to GetThreadLocalsMapLocked() and its return value.
   static Mutex mutex_;
   // Protects access to GetThreadMapLocked() and its return value.
   static Mutex thread_map_mutex_;
 };
 
 Mutex ThreadLocalRegistryImpl::mutex_(Mutex::kStaticMutex);
 Mutex ThreadLocalRegistryImpl::thread_map_mutex_(Mutex::kStaticMutex);
 
 ThreadLocalValueHolderBase* ThreadLocalRegistry::GetValueOnCurrentThread(
       const ThreadLocalBase* thread_local_instance) {
   return ThreadLocalRegistryImpl::GetValueOnCurrentThread(
       thread_local_instance);
 }
 
 void ThreadLocalRegistry::OnThreadLocalDestroyed(
       const ThreadLocalBase* thread_local_instance) {
   ThreadLocalRegistryImpl::OnThreadLocalDestroyed(thread_local_instance);
 }
 
 #endif  // GTEST_IS_THREADSAFE && GTEST_OS_WINDOWS
 
 #if GTEST_USES_POSIX_RE
 
 // Implements RE.  Currently only needed for death tests.
 
 RE::~RE() {
   if (is_valid_) {
     // regfree'ing an invalid regex might crash because the content
     // of the regex is undefined. Since the regex's are essentially
     // the same, one cannot be valid (or invalid) without the other
     // being so too.
     regfree(&partial_regex_);
     regfree(&full_regex_);
   }
   free(const_cast<char*>(pattern_));
 }
 
 // Returns true if and only if regular expression re matches the entire str.
 bool RE::FullMatch(const char* str, const RE& re) {
   if (!re.is_valid_) return false;
 
   regmatch_t match;
   return regexec(&re.full_regex_, str, 1, &match, 0) == 0;
 }
 
 // Returns true if and only if regular expression re matches a substring of
 // str (including str itself).
 bool RE::PartialMatch(const char* str, const RE& re) {
   if (!re.is_valid_) return false;
 
   regmatch_t match;
   return regexec(&re.partial_regex_, str, 1, &match, 0) == 0;
 }
 
 // Initializes an RE from its string representation.
 void RE::Init(const char* regex) {
   pattern_ = posix::StrDup(regex);
 
   // Reserves enough bytes to hold the regular expression used for a
   // full match.
   const size_t full_regex_len = strlen(regex) + 10;
   char* const full_pattern = new char[full_regex_len];
 
   snprintf(full_pattern, full_regex_len, "^(%s)$", regex);
   is_valid_ = regcomp(&full_regex_, full_pattern, REG_EXTENDED) == 0;
   // We want to call regcomp(&partial_regex_, ...) even if the
   // previous expression returns false.  Otherwise partial_regex_ may
   // not be properly initialized can may cause trouble when it's
   // freed.
   //
   // Some implementation of POSIX regex (e.g. on at least some
   // versions of Cygwin) doesn't accept the empty string as a valid
   // regex.  We change it to an equivalent form "()" to be safe.
   if (is_valid_) {
     const char* const partial_regex = (*regex == '\0') ? "()" : regex;
     is_valid_ = regcomp(&partial_regex_, partial_regex, REG_EXTENDED) == 0;
   }
   EXPECT_TRUE(is_valid_)
       << "Regular expression \"" << regex
       << "\" is not a valid POSIX Extended regular expression.";
 
   delete[] full_pattern;
 }
 
 #elif GTEST_USES_SIMPLE_RE
 
 // Returns true if and only if ch appears anywhere in str (excluding the
 // terminating '\0' character).
 bool IsInSet(char ch, const char* str) {
   return ch != '\0' && strchr(str, ch) != nullptr;
 }
 
 // Returns true if and only if ch belongs to the given classification.
 // Unlike similar functions in <ctype.h>, these aren't affected by the
 // current locale.
 bool IsAsciiDigit(char ch) { return '0' <= ch && ch <= '9'; }
 bool IsAsciiPunct(char ch) {
   return IsInSet(ch, "^-!\"#$%&'()*+,./:;<=>?@[\\]_`{|}~");
 }
 bool IsRepeat(char ch) { return IsInSet(ch, "?*+"); }
 bool IsAsciiWhiteSpace(char ch) { return IsInSet(ch, " \f\n\r\t\v"); }
 bool IsAsciiWordChar(char ch) {
   return ('a' <= ch && ch <= 'z') || ('A' <= ch && ch <= 'Z') ||
       ('0' <= ch && ch <= '9') || ch == '_';
 }
 
 // Returns true if and only if "\\c" is a supported escape sequence.
 bool IsValidEscape(char c) {
   return (IsAsciiPunct(c) || IsInSet(c, "dDfnrsStvwW"));
 }
 
 // Returns true if and only if the given atom (specified by escaped and
 // pattern) matches ch.  The result is undefined if the atom is invalid.
 bool AtomMatchesChar(bool escaped, char pattern_char, char ch) {
   if (escaped) {  // "\\p" where p is pattern_char.
     switch (pattern_char) {
       case 'd': return IsAsciiDigit(ch);
       case 'D': return !IsAsciiDigit(ch);
       case 'f': return ch == '\f';
       case 'n': return ch == '\n';
       case 'r': return ch == '\r';
       case 's': return IsAsciiWhiteSpace(ch);
       case 'S': return !IsAsciiWhiteSpace(ch);
       case 't': return ch == '\t';
       case 'v': return ch == '\v';
       case 'w': return IsAsciiWordChar(ch);
       case 'W': return !IsAsciiWordChar(ch);
     }
     return IsAsciiPunct(pattern_char) && pattern_char == ch;
   }
 
   return (pattern_char == '.' && ch != '\n') || pattern_char == ch;
 }
 
 // Helper function used by ValidateRegex() to format error messages.
 static std::string FormatRegexSyntaxError(const char* regex, int index) {
   return (Message() << "Syntax error at index " << index
           << " in simple regular expression \"" << regex << "\": ").GetString();
 }
 
 // Generates non-fatal failures and returns false if regex is invalid;
 // otherwise returns true.
 bool ValidateRegex(const char* regex) {
   if (regex == nullptr) {
     ADD_FAILURE() << "NULL is not a valid simple regular expression.";
     return false;
   }
 
   bool is_valid = true;
 
   // True if and only if ?, *, or + can follow the previous atom.
   bool prev_repeatable = false;
   for (int i = 0; regex[i]; i++) {
     if (regex[i] == '\\') {  // An escape sequence
       i++;
       if (regex[i] == '\0') {
         ADD_FAILURE() << FormatRegexSyntaxError(regex, i - 1)
                       << "'\\' cannot appear at the end.";
         return false;
       }
 
       if (!IsValidEscape(regex[i])) {
         ADD_FAILURE() << FormatRegexSyntaxError(regex, i - 1)
                       << "invalid escape sequence \"\\" << regex[i] << "\".";
         is_valid = false;
       }
       prev_repeatable = true;
     } else {  // Not an escape sequence.
       const char ch = regex[i];
 
       if (ch == '^' && i > 0) {
         ADD_FAILURE() << FormatRegexSyntaxError(regex, i)
                       << "'^' can only appear at the beginning.";
         is_valid = false;
       } else if (ch == '$' && regex[i + 1] != '\0') {
         ADD_FAILURE() << FormatRegexSyntaxError(regex, i)
                       << "'$' can only appear at the end.";
         is_valid = false;
       } else if (IsInSet(ch, "()[]{}|")) {
         ADD_FAILURE() << FormatRegexSyntaxError(regex, i)
                       << "'" << ch << "' is unsupported.";
         is_valid = false;
       } else if (IsRepeat(ch) && !prev_repeatable) {
         ADD_FAILURE() << FormatRegexSyntaxError(regex, i)
                       << "'" << ch << "' can only follow a repeatable token.";
         is_valid = false;
       }
 
       prev_repeatable = !IsInSet(ch, "^$?*+");
     }
   }
 
   return is_valid;
 }
 
 // Matches a repeated regex atom followed by a valid simple regular
 // expression.  The regex atom is defined as c if escaped is false,
 // or \c otherwise.  repeat is the repetition meta character (?, *,
 // or +).  The behavior is undefined if str contains too many
 // characters to be indexable by size_t, in which case the test will
 // probably time out anyway.  We are fine with this limitation as
 // std::string has it too.
 bool MatchRepetitionAndRegexAtHead(
     bool escaped, char c, char repeat, const char* regex,
     const char* str) {
   const size_t min_count = (repeat == '+') ? 1 : 0;
   const size_t max_count = (repeat == '?') ? 1 :
       static_cast<size_t>(-1) - 1;
   // We cannot call numeric_limits::max() as it conflicts with the
   // max() macro on Windows.
 
   for (size_t i = 0; i <= max_count; ++i) {
     // We know that the atom matches each of the first i characters in str.
     if (i >= min_count && MatchRegexAtHead(regex, str + i)) {
       // We have enough matches at the head, and the tail matches too.
       // Since we only care about *whether* the pattern matches str
       // (as opposed to *how* it matches), there is no need to find a
       // greedy match.
       return true;
     }
     if (str[i] == '\0' || !AtomMatchesChar(escaped, c, str[i]))
       return false;
   }
   return false;
 }
 
 // Returns true if and only if regex matches a prefix of str. regex must
 // be a valid simple regular expression and not start with "^", or the
 // result is undefined.
 bool MatchRegexAtHead(const char* regex, const char* str) {
   if (*regex == '\0')  // An empty regex matches a prefix of anything.
     return true;
 
   // "$" only matches the end of a string.  Note that regex being
   // valid guarantees that there's nothing after "$" in it.
   if (*regex == '$')
     return *str == '\0';
 
   // Is the first thing in regex an escape sequence?
   const bool escaped = *regex == '\\';
   if (escaped)
     ++regex;
   if (IsRepeat(regex[1])) {
     // MatchRepetitionAndRegexAtHead() calls MatchRegexAtHead(), so
     // here's an indirect recursion.  It terminates as the regex gets
     // shorter in each recursion.
     return MatchRepetitionAndRegexAtHead(
         escaped, regex[0], regex[1], regex + 2, str);
   } else {
     // regex isn't empty, isn't "$", and doesn't start with a
     // repetition.  We match the first atom of regex with the first
     // character of str and recurse.
     return (*str != '\0') && AtomMatchesChar(escaped, *regex, *str) &&
         MatchRegexAtHead(regex + 1, str + 1);
   }
 }
 
 // Returns true if and only if regex matches any substring of str.  regex must
 // be a valid simple regular expression, or the result is undefined.
 //
 // The algorithm is recursive, but the recursion depth doesn't exceed
 // the regex length, so we won't need to worry about running out of
 // stack space normally.  In rare cases the time complexity can be
 // exponential with respect to the regex length + the string length,
 // but usually it's must faster (often close to linear).
 bool MatchRegexAnywhere(const char* regex, const char* str) {
   if (regex == nullptr || str == nullptr) return false;
 
   if (*regex == '^')
     return MatchRegexAtHead(regex + 1, str);
 
   // A successful match can be anywhere in str.
   do {
     if (MatchRegexAtHead(regex, str))
       return true;
   } while (*str++ != '\0');
   return false;
 }
 
 // Implements the RE class.
 
 RE::~RE() {
   free(const_cast<char*>(pattern_));
   free(const_cast<char*>(full_pattern_));
 }
 
 // Returns true if and only if regular expression re matches the entire str.
 bool RE::FullMatch(const char* str, const RE& re) {
   return re.is_valid_ && MatchRegexAnywhere(re.full_pattern_, str);
 }
 
 // Returns true if and only if regular expression re matches a substring of
 // str (including str itself).
 bool RE::PartialMatch(const char* str, const RE& re) {
   return re.is_valid_ && MatchRegexAnywhere(re.pattern_, str);
 }
 
 // Initializes an RE from its string representation.
 void RE::Init(const char* regex) {
   pattern_ = full_pattern_ = nullptr;
   if (regex != nullptr) {
     pattern_ = posix::StrDup(regex);
   }
 
   is_valid_ = ValidateRegex(regex);
   if (!is_valid_) {
     // No need to calculate the full pattern when the regex is invalid.
     return;
   }
 
   const size_t len = strlen(regex);
   // Reserves enough bytes to hold the regular expression used for a
   // full match: we need space to prepend a '^', append a '$', and
   // terminate the string with '\0'.
   char* buffer = static_cast<char*>(malloc(len + 3));
   full_pattern_ = buffer;
 
   if (*regex != '^')
     *buffer++ = '^';  // Makes sure full_pattern_ starts with '^'.
 
   // We don't use snprintf or strncpy, as they trigger a warning when
   // compiled with VC++ 8.0.
   memcpy(buffer, regex, len);
   buffer += len;
 
   if (len == 0 || regex[len - 1] != '$')
     *buffer++ = '$';  // Makes sure full_pattern_ ends with '$'.
 
   *buffer = '\0';
 }
 
 #endif  // GTEST_USES_POSIX_RE
 
 const char kUnknownFile[] = "unknown file";
 
 // Formats a source file path and a line number as they would appear
 // in an error message from the compiler used to compile this code.
 GTEST_API_ ::std::string FormatFileLocation(const char* file, int line) {
   const std::string file_name(file == nullptr ? kUnknownFile : file);
 
   if (line < 0) {
     return file_name + ":";
   }
 #ifdef _MSC_VER
   return file_name + "(" + StreamableToString(line) + "):";
 #else
   return file_name + ":" + StreamableToString(line) + ":";
 #endif  // _MSC_VER
 }
 
 // Formats a file location for compiler-independent XML output.
 // Although this function is not platform dependent, we put it next to
 // FormatFileLocation in order to contrast the two functions.
 // Note that FormatCompilerIndependentFileLocation() does NOT append colon
 // to the file location it produces, unlike FormatFileLocation().
 GTEST_API_ ::std::string FormatCompilerIndependentFileLocation(
     const char* file, int line) {
   const std::string file_name(file == nullptr ? kUnknownFile : file);
 
   if (line < 0)
     return file_name;
   else
     return file_name + ":" + StreamableToString(line);
 }
 
 GTestLog::GTestLog(GTestLogSeverity severity, const char* file, int line)
     : severity_(severity) {
   const char* const marker =
       severity == GTEST_INFO ?    "[  INFO ]" :
       severity == GTEST_WARNING ? "[WARNING]" :
       severity == GTEST_ERROR ?   "[ ERROR ]" : "[ FATAL ]";
   GetStream() << ::std::endl << marker << " "
               << FormatFileLocation(file, line).c_str() << ": ";
 }
 
 // Flushes the buffers and, if severity is GTEST_FATAL, aborts the program.
 GTestLog::~GTestLog() {
   GetStream() << ::std::endl;
   if (severity_ == GTEST_FATAL) {
     fflush(stderr);
     posix::Abort();
   }
 }
 
 // Disable Microsoft deprecation warnings for POSIX functions called from
 // this class (creat, dup, dup2, and close)
 GTEST_DISABLE_MSC_DEPRECATED_PUSH_()
 
 #if GTEST_HAS_STREAM_REDIRECTION
 
 // Object that captures an output stream (stdout/stderr).
 class CapturedStream {
  public:
   // The ctor redirects the stream to a temporary file.
   explicit CapturedStream(int fd) : fd_(fd), uncaptured_fd_(dup(fd)) {
 # if GTEST_OS_WINDOWS
     char temp_dir_path[MAX_PATH + 1] = { '\0' };  // NOLINT
     char temp_file_path[MAX_PATH + 1] = { '\0' };  // NOLINT
 
     ::GetTempPathA(sizeof(temp_dir_path), temp_dir_path);
     const UINT success = ::GetTempFileNameA(temp_dir_path,
                                             "gtest_redir",
                                             0,  // Generate unique file name.
                                             temp_file_path);
     GTEST_CHECK_(success != 0)
         << "Unable to create a temporary file in " << temp_dir_path;
     const int captured_fd = creat(temp_file_path, _S_IREAD | _S_IWRITE);
     GTEST_CHECK_(captured_fd != -1) << "Unable to open temporary file "
                                     << temp_file_path;
     filename_ = temp_file_path;
 # else
     // There's no guarantee that a test has write access to the current
     // directory, so we create the temporary file in the /tmp directory
     // instead. We use /tmp on most systems, and /sdcard on Android.
     // That's because Android doesn't have /tmp.
 #  if GTEST_OS_LINUX_ANDROID
     // Note: Android applications are expected to call the framework's
     // Context.getExternalStorageDirectory() method through JNI to get
     // the location of the world-writable SD Card directory. However,
     // this requires a Context handle, which cannot be retrieved
     // globally from native code. Doing so also precludes running the
     // code as part of a regular standalone executable, which doesn't
     // run in a Dalvik process (e.g. when running it through 'adb shell').
     //
     // The location /data/local/tmp is directly accessible from native code.
     // '/sdcard' and other variants cannot be relied on, as they are not
     // guaranteed to be mounted, or may have a delay in mounting.
     char name_template[] = "/data/local/tmp/gtest_captured_stream.XXXXXX";
 #  else
     char name_template[] = "/tmp/captured_stream.XXXXXX";
 #  endif  // GTEST_OS_LINUX_ANDROID
     const int captured_fd = mkstemp(name_template);
     if (captured_fd == -1) {
       GTEST_LOG_(WARNING)
           << "Failed to create tmp file " << name_template
           << " for test; does the test have access to the /tmp directory?";
     }
     filename_ = name_template;
 # endif  // GTEST_OS_WINDOWS
     fflush(nullptr);
     dup2(captured_fd, fd_);
     close(captured_fd);
   }
 
   ~CapturedStream() {
     remove(filename_.c_str());
   }
 
   std::string GetCapturedString() {
     if (uncaptured_fd_ != -1) {
       // Restores the original stream.
       fflush(nullptr);
       dup2(uncaptured_fd_, fd_);
       close(uncaptured_fd_);
       uncaptured_fd_ = -1;
     }
 
     FILE* const file = posix::FOpen(filename_.c_str(), "r");
     if (file == nullptr) {
       GTEST_LOG_(FATAL) << "Failed to open tmp file " << filename_
                         << " for capturing stream.";
     }
     const std::string content = ReadEntireFile(file);
     posix::FClose(file);
     return content;
   }
 
  private:
   const int fd_;  // A stream to capture.
   int uncaptured_fd_;
   // Name of the temporary file holding the stderr output.
   ::std::string filename_;
 
   GTEST_DISALLOW_COPY_AND_ASSIGN_(CapturedStream);
 };
 
 GTEST_DISABLE_MSC_DEPRECATED_POP_()
 
 static CapturedStream* g_captured_stderr = nullptr;
 static CapturedStream* g_captured_stdout = nullptr;
 
 // Starts capturing an output stream (stdout/stderr).
 static void CaptureStream(int fd, const char* stream_name,
                           CapturedStream** stream) {
   if (*stream != nullptr) {
     GTEST_LOG_(FATAL) << "Only one " << stream_name
                       << " capturer can exist at a time.";
   }
   *stream = new CapturedStream(fd);
 }
 
 // Stops capturing the output stream and returns the captured string.
 static std::string GetCapturedStream(CapturedStream** captured_stream) {
   const std::string content = (*captured_stream)->GetCapturedString();
 
   delete *captured_stream;
   *captured_stream = nullptr;
 
   return content;
 }
 
 // Starts capturing stdout.
 void CaptureStdout() {
   CaptureStream(kStdOutFileno, "stdout", &g_captured_stdout);
 }
 
 // Starts capturing stderr.
 void CaptureStderr() {
   CaptureStream(kStdErrFileno, "stderr", &g_captured_stderr);
 }
 
 // Stops capturing stdout and returns the captured string.
 std::string GetCapturedStdout() {
   return GetCapturedStream(&g_captured_stdout);
 }
 
 // Stops capturing stderr and returns the captured string.
 std::string GetCapturedStderr() {
   return GetCapturedStream(&g_captured_stderr);
 }
 
 #endif  // GTEST_HAS_STREAM_REDIRECTION
 
 
 
 
 
 size_t GetFileSize(FILE* file) {
   fseek(file, 0, SEEK_END);
   return static_cast<size_t>(ftell(file));
 }
 
 std::string ReadEntireFile(FILE* file) {
   const size_t file_size = GetFileSize(file);
   char* const buffer = new char[file_size];
 
   size_t bytes_last_read = 0;  // # of bytes read in the last fread()
   size_t bytes_read = 0;       // # of bytes read so far
 
   fseek(file, 0, SEEK_SET);
 
   // Keeps reading the file until we cannot read further or the
   // pre-determined file size is reached.
   do {
     bytes_last_read = fread(buffer+bytes_read, 1, file_size-bytes_read, file);
     bytes_read += bytes_last_read;
   } while (bytes_last_read > 0 && bytes_read < file_size);
 
   const std::string content(buffer, bytes_read);
   delete[] buffer;
 
   return content;
 }
 
 #if GTEST_HAS_DEATH_TEST
 static const std::vector<std::string>* g_injected_test_argvs =
     nullptr;  // Owned.
 
 std::vector<std::string> GetInjectableArgvs() {
   if (g_injected_test_argvs != nullptr) {
     return *g_injected_test_argvs;
   }
   return GetArgvs();
 }
 
 void SetInjectableArgvs(const std::vector<std::string>* new_argvs) {
   if (g_injected_test_argvs != new_argvs) delete g_injected_test_argvs;
   g_injected_test_argvs = new_argvs;
 }
 
 void SetInjectableArgvs(const std::vector<std::string>& new_argvs) {
   SetInjectableArgvs(
       new std::vector<std::string>(new_argvs.begin(), new_argvs.end()));
 }
 
 void ClearInjectableArgvs() {
   delete g_injected_test_argvs;
   g_injected_test_argvs = nullptr;
 }
 #endif  // GTEST_HAS_DEATH_TEST
 
 #if GTEST_OS_WINDOWS_MOBILE
 namespace posix {
 void Abort() {
   DebugBreak();
   TerminateProcess(GetCurrentProcess(), 1);
 }
 }  // namespace posix
 #endif  // GTEST_OS_WINDOWS_MOBILE
 
 // Returns the name of the environment variable corresponding to the
 // given flag.  For example, FlagToEnvVar("foo") will return
 // "GTEST_FOO" in the open-source version.
 static std::string FlagToEnvVar(const char* flag) {
   const std::string full_flag =
       (Message() << GTEST_FLAG_PREFIX_ << flag).GetString();
 
   Message env_var;
   for (size_t i = 0; i != full_flag.length(); i++) {
     env_var << ToUpper(full_flag.c_str()[i]);
   }
 
   return env_var.GetString();
 }
 
 // Parses 'str' for a 32-bit signed integer.  If successful, writes
 // the result to *value and returns true; otherwise leaves *value
 // unchanged and returns false.
 bool ParseInt32(const Message& src_text, const char* str, int32_t* value) {
   // Parses the environment variable as a decimal integer.
   char* end = nullptr;
   const long long_value = strtol(str, &end, 10);  // NOLINT
 
   // Has strtol() consumed all characters in the string?
   if (*end != '\0') {
     // No - an invalid character was encountered.
     Message msg;
     msg << "WARNING: " << src_text
         << " is expected to be a 32-bit integer, but actually"
         << " has value \"" << str << "\".\n";
     printf("%s", msg.GetString().c_str());
     fflush(stdout);
     return false;
   }
 
   // Is the parsed value in the range of an int32_t?
   const auto result = static_cast<int32_t>(long_value);
   if (long_value == LONG_MAX || long_value == LONG_MIN ||
       // The parsed value overflows as a long.  (strtol() returns
       // LONG_MAX or LONG_MIN when the input overflows.)
       result != long_value
       // The parsed value overflows as an int32_t.
       ) {
     Message msg;
     msg << "WARNING: " << src_text
         << " is expected to be a 32-bit integer, but actually"
         << " has value " << str << ", which overflows.\n";
     printf("%s", msg.GetString().c_str());
     fflush(stdout);
     return false;
   }
 
   *value = result;
   return true;
 }
 
 // Reads and returns the Boolean environment variable corresponding to
 // the given flag; if it's not set, returns default_value.
 //
 // The value is considered true if and only if it's not "0".
 bool BoolFromGTestEnv(const char* flag, bool default_value) {
 #if defined(GTEST_GET_BOOL_FROM_ENV_)
   return GTEST_GET_BOOL_FROM_ENV_(flag, default_value);
 #else
   const std::string env_var = FlagToEnvVar(flag);
   const char* const string_value = posix::GetEnv(env_var.c_str());
   return string_value == nullptr ? default_value
                                  : strcmp(string_value, "0") != 0;
 #endif  // defined(GTEST_GET_BOOL_FROM_ENV_)
 }
 
 // Reads and returns a 32-bit integer stored in the environment
 // variable corresponding to the given flag; if it isn't set or
 // doesn't represent a valid 32-bit integer, returns default_value.
 int32_t Int32FromGTestEnv(const char* flag, int32_t default_value) {
 #if defined(GTEST_GET_INT32_FROM_ENV_)
   return GTEST_GET_INT32_FROM_ENV_(flag, default_value);
 #else
   const std::string env_var = FlagToEnvVar(flag);
   const char* const string_value = posix::GetEnv(env_var.c_str());
   if (string_value == nullptr) {
     // The environment variable is not set.
     return default_value;
   }
 
   int32_t result = default_value;
   if (!ParseInt32(Message() << "Environment variable " << env_var,
                   string_value, &result)) {
     printf("The default value %s is used.\n",
            (Message() << default_value).GetString().c_str());
     fflush(stdout);
     return default_value;
   }
 
   return result;
 #endif  // defined(GTEST_GET_INT32_FROM_ENV_)
 }
 
 // As a special case for the 'output' flag, if GTEST_OUTPUT is not
 // set, we look for XML_OUTPUT_FILE, which is set by the Bazel build
 // system.  The value of XML_OUTPUT_FILE is a filename without the
 // "xml:" prefix of GTEST_OUTPUT.
 // Note that this is meant to be called at the call site so it does
 // not check that the flag is 'output'
 // In essence this checks an env variable called XML_OUTPUT_FILE
 // and if it is set we prepend "xml:" to its value, if it not set we return ""
 std::string OutputFlagAlsoCheckEnvVar(){
   std::string default_value_for_output_flag = "";
   const char* xml_output_file_env = posix::GetEnv("XML_OUTPUT_FILE");
   if (nullptr != xml_output_file_env) {
     default_value_for_output_flag = std::string("xml:") + xml_output_file_env;
   }
   return default_value_for_output_flag;
 }
 
 // Reads and returns the string environment variable corresponding to
 // the given flag; if it's not set, returns default_value.
 const char* StringFromGTestEnv(const char* flag, const char* default_value) {
 #if defined(GTEST_GET_STRING_FROM_ENV_)
   return GTEST_GET_STRING_FROM_ENV_(flag, default_value);
 #else
   const std::string env_var = FlagToEnvVar(flag);
   const char* const value = posix::GetEnv(env_var.c_str());
   return value == nullptr ? default_value : value;
 #endif  // defined(GTEST_GET_STRING_FROM_ENV_)
 }
 
 }  // namespace internal
 }  // namespace testing