void *CRYPTO_THREAD_get_local(CRYPTO_THREAD_LOCAL *key)
{
    DWORD last_error;
    void *ret;

    /*
     * TlsGetValue clears the last error even on success, so that callers may
     * distinguish it successfully returning NULL or failing. It is documented
     * to never fail if the argument is a valid index from TlsAlloc, so we do
     * not need to handle this.
     *
     * However, this error-mangling behavior interferes with the caller's use of
     * GetLastError. In particular SSL_get_error queries the error queue to
     * determine whether the caller should look at the OS's errors. To avoid
     * destroying state, save and restore the Windows error.
     *
     * https://msdn.microsoft.com/en-us/library/windows/desktop/ms686812(v=vs.85).aspx
     */
    last_error = GetLastError();
    ret = TlsGetValue(*key);
    SetLastError(last_error);
    return ret;
}

void *CRYPTO_THREAD_get_local(CRYPTO_THREAD_LOCAL *key)
{
    DWORD last_error;
    void *ret;

    /*
     * TlsGetValue clears the last error even on success, so that callers may
     * distinguish it successfully returning NULL or failing. It is documented
     * to never fail if the argument is a valid index from TlsAlloc, so we do
     * not need to handle this.
     *
     * However, this error-mangling behavior interferes with the caller's use of
     * GetLastError. In particular SSL_get_error queries the error queue to
     * determine whether the caller should look at the OS's errors. To avoid
     * destroying state, save and restore the Windows error.
     *
     * https://msdn.microsoft.com/en-us/library/windows/desktop/ms686812(v=vs.85).aspx
     */
    last_error = GetLastError();
    ret = TlsGetValue(*key);
    SetLastError(last_error);
    return ret;
}
