tor-browser

gtest-port.cc (48099B)

---

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//
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// modification, are permitted provided that the following conditions are
// met:
//
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// notice, this list of conditions and the following disclaimer.
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// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
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// 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
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#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] = static_cast<int>(size / static_cast<size_t>(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
 size_t nthreads = 0;
 for (size_t i = 0; i < size / static_cast<size_t>(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);  // NOLINT
Mutex ThreadLocalRegistryImpl::thread_map_mutex_(Mutex::kStaticMutex);  // NOLINT

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 a temporary directory.
   std::string name_template;

#  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.
   name_template = "/data/local/tmp/";
#  elif GTEST_OS_IOS
   char user_temp_dir[PATH_MAX + 1];

   // Documented alternative to NSTemporaryDirectory() (for obtaining creating
   // a temporary directory) at
   // https://developer.apple.com/library/archive/documentation/Security/Conceptual/SecureCodingGuide/Articles/RaceConditions.html#//apple_ref/doc/uid/TP40002585-SW10
   //
   // _CS_DARWIN_USER_TEMP_DIR (as well as _CS_DARWIN_USER_CACHE_DIR) is not
   // documented in the confstr() man page at
   // https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/confstr.3.html#//apple_ref/doc/man/3/confstr
   // but are still available, according to the WebKit patches at
   // https://trac.webkit.org/changeset/262004/webkit
   // https://trac.webkit.org/changeset/263705/webkit
   //
   // The confstr() implementation falls back to getenv("TMPDIR"). See
   // https://opensource.apple.com/source/Libc/Libc-1439.100.3/gen/confstr.c.auto.html
   ::confstr(_CS_DARWIN_USER_TEMP_DIR, user_temp_dir, sizeof(user_temp_dir));

   name_template = user_temp_dir;
   if (name_template.back() != GTEST_PATH_SEP_[0])
     name_template.push_back(GTEST_PATH_SEP_[0]);
#  else
   name_template = "/tmp/";
#  endif
   name_template.append("gtest_captured_stream.XXXXXX");

   // mkstemp() modifies the string bytes in place, and does not go beyond the
   // string's length. This results in well-defined behavior in C++17.
   //
   // The const_cast is needed below C++17. The constraints on std::string
   // implementations in C++11 and above make assumption behind the const_cast
   // fairly safe.
   const int captured_fd = ::mkstemp(const_cast<char*>(name_template.data()));
   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_ = std::move(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