// 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 (size_t 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
