src/common_test.h

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <dirent.h>
#include <dlfcn.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>

#include "../../external/icu4c/common/unicode/uvernum.h"
#include "base/macros.h"
#include "base/stl_util.h"
#include "base/stringprintf.h"
#include "base/unix_file/fd_file.h"
#include "class_linker.h"
#include "compiler/driver/compiler_driver.h"
#include "dex_file-inl.h"
#include "gtest/gtest.h"
#include "heap.h"
#include "instruction_set.h"
#include "mirror/class_loader.h"
#include "oat_file.h"
#include "object_utils.h"
#include "os.h"
#include "runtime.h"
#include "scoped_thread_state_change.h"
#include "ScopedLocalRef.h"
#include "thread.h"
#include "UniquePtr.h"
#include "well_known_classes.h"

namespace art {

static const byte kBase64Map[256] = {
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255,  62, 255, 255, 255,  63,
  52,  53,  54,  55,  56,  57,  58,  59,  60,  61, 255, 255,
  255, 254, 255, 255, 255,   0,   1,   2,   3,   4,   5,   6,
    7,   8,   9,  10,  11,  12,  13,  14,  15,  16,  17,  18, // NOLINT
   19,  20,  21,  22,  23,  24,  25, 255, 255, 255, 255, 255, // NOLINT
  255,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,
   37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,  48, // NOLINT
   49,  50,  51, 255, 255, 255, 255, 255, 255, 255, 255, 255, // NOLINT
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  255, 255, 255, 255
};

byte* DecodeBase64(const char* src, size_t* dst_size) {
  std::vector<byte> tmp;
  uint32_t t = 0, y = 0;
  int g = 3;
  for (size_t i = 0; src[i] != '\0'; ++i) {
    byte c = kBase64Map[src[i] & 0xFF];
    if (c == 255) continue;
    // the final = symbols are read and used to trim the remaining bytes
    if (c == 254) {
      c = 0;
      // prevent g < 0 which would potentially allow an overflow later
      if (--g < 0) {
        *dst_size = 0;
        return NULL;
      }
    } else if (g != 3) {
      // we only allow = to be at the end
      *dst_size = 0;
      return NULL;
    }
    t = (t << 6) | c;
    if (++y == 4) {
      tmp.push_back((t >> 16) & 255);
      if (g > 1) {
        tmp.push_back((t >> 8) & 255);
      }
      if (g > 2) {
        tmp.push_back(t & 255);
      }
      y = t = 0;
    }
  }
  if (y != 0) {
    *dst_size = 0;
    return NULL;
  }
  UniquePtr<byte[]> dst(new byte[tmp.size()]);
  if (dst_size != NULL) {
    *dst_size = tmp.size();
  } else {
    *dst_size = 0;
  }
  std::copy(tmp.begin(), tmp.end(), dst.get());
  return dst.release();
}

static inline const DexFile* OpenDexFileBase64(const char* base64,
                                               const std::string& location) {
  // decode base64
  CHECK(base64 != NULL);
  size_t length;
  UniquePtr<byte[]> dex_bytes(DecodeBase64(base64, &length));
  CHECK(dex_bytes.get() != NULL);

  // write to provided file
  UniquePtr<File> file(OS::OpenFile(location.c_str(), true));
  CHECK(file.get() != NULL);
  if (!file->WriteFully(dex_bytes.get(), length)) {
    PLOG(FATAL) << "Failed to write base64 as dex file";
  }
  file.reset();

  // read dex file
  const DexFile* dex_file = DexFile::Open(location, location);
  CHECK(dex_file != NULL);
  return dex_file;
}

class ScratchFile {
 public:
  ScratchFile() {
    filename_ = getenv("ANDROID_DATA");
    filename_ += "/TmpFile-XXXXXX";
    int fd = mkstemp(&filename_[0]);
    CHECK_NE(-1, fd);
    file_.reset(new File(fd, GetFilename()));
  }

  ~ScratchFile() {
    int unlink_result = unlink(filename_.c_str());
    CHECK_EQ(0, unlink_result);
  }

  const std::string& GetFilename() const {
    return filename_;
  }

  File* GetFile() const {
    return file_.get();
  }

  int GetFd() const {
    return file_->Fd();
  }

 private:
  std::string filename_;
  UniquePtr<File> file_;
};

class CommonTest : public testing::Test {
 public:
  static void MakeExecutable(const mirror::ByteArray* code_array) {
    CHECK(code_array != NULL);
    MakeExecutable(code_array->GetData(), code_array->GetLength());
  }

  static void MakeExecutable(const std::vector<uint8_t>& code) {
    CHECK_NE(code.size(), 0U);
    MakeExecutable(&code[0], code.size());
  }

  // Create an OatMethod based on pointers (for unit tests)
  OatFile::OatMethod CreateOatMethod(const void* code,
                                     const size_t frame_size_in_bytes,
                                     const uint32_t core_spill_mask,
                                     const uint32_t fp_spill_mask,
                                     const uint32_t* mapping_table,
                                     const uint16_t* vmap_table,
                                     const uint8_t* gc_map) {
      return OatFile::OatMethod(NULL,
                                reinterpret_cast<uint32_t>(code),
                                frame_size_in_bytes,
                                core_spill_mask,
                                fp_spill_mask,
                                reinterpret_cast<uint32_t>(mapping_table),
                                reinterpret_cast<uint32_t>(vmap_table),
                                reinterpret_cast<uint32_t>(gc_map)
#if defined(ART_USE_PORTABLE_COMPILER)
                              , 0
#endif
                                );
  }

  void MakeExecutable(mirror::AbstractMethod* method) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    CHECK(method != NULL);
    LOG(INFO) << "MakeExecutable " << PrettyMethod(method);

    const CompiledMethod* compiled_method = NULL;
    if (!method->IsAbstract()) {
      const mirror::DexCache* dex_cache = method->GetDeclaringClass()->GetDexCache();
      const DexFile& dex_file = *dex_cache->GetDexFile();
      compiled_method =
          compiler_driver_->GetCompiledMethod(CompilerDriver::MethodReference(&dex_file,
                                                                              method->GetDexMethodIndex()));

#ifndef ART_SLOW_MODE
      CHECK(compiled_method != NULL) << PrettyMethod(method);
#endif
    }
    if (compiled_method != NULL) {
      const std::vector<uint8_t>& code = compiled_method->GetCode();
      MakeExecutable(code);
      const void* method_code = CompiledMethod::CodePointer(&code[0],
                                                            compiled_method->GetInstructionSet());
      LOG(INFO) << "MakeExecutable " << PrettyMethod(method) << " code=" << method_code;
      OatFile::OatMethod oat_method = CreateOatMethod(method_code,
                                                      compiled_method->GetFrameSizeInBytes(),
                                                      compiled_method->GetCoreSpillMask(),
                                                      compiled_method->GetFpSpillMask(),
                                                      &compiled_method->GetMappingTable()[0],
                                                      &compiled_method->GetVmapTable()[0],
                                                      NULL);
      oat_method.LinkMethod(method);
    } else {
      const void* method_code;
      if (method->IsAbstract()) {
        MakeExecutable(runtime_->GetAbstractMethodErrorStubArray());
        method_code = runtime_->GetAbstractMethodErrorStubArray()->GetData();
      } else {
        // No code? You must mean to go into the interpreter.
        method_code = GetInterpreterEntryPoint();
      }
      LOG(INFO) << "MakeExecutable " << PrettyMethod(method) << " code=" << method_code;
      OatFile::OatMethod oat_method = CreateOatMethod(method_code,
                                                      kStackAlignment,
                                                      0,
                                                      0,
                                                      NULL,
                                                      NULL,
                                                      NULL);
      oat_method.LinkMethod(method);
    }
  }

  static void MakeExecutable(const void* code_start, size_t code_length) {
    CHECK(code_start != NULL);
    CHECK_NE(code_length, 0U);
    uintptr_t data = reinterpret_cast<uintptr_t>(code_start);
    uintptr_t base = RoundDown(data, kPageSize);
    uintptr_t limit = RoundUp(data + code_length, kPageSize);
    uintptr_t len = limit - base;
    int result = mprotect(reinterpret_cast<void*>(base), len, PROT_READ | PROT_WRITE | PROT_EXEC);
    CHECK_EQ(result, 0);

    // Flush instruction cache
    // Only uses __builtin___clear_cache if GCC >= 4.3.3
#if GCC_VERSION >= 40303
    __builtin___clear_cache(reinterpret_cast<void*>(base), reinterpret_cast<void*>(base + len));
#elif defined(__APPLE__)
    // Currently, only Mac OS builds use GCC 4.2.*. Those host builds do not
    // need to generate clear_cache on x86.
#else
#error unsupported
#endif
  }

  static void SetEnvironmentVariables(std::string& android_data) {
    if (IsHost()) {
      // $ANDROID_ROOT is set on the device, but not on the host.
      // We need to set this so that icu4c can find its locale data.
      std::string root;
      root += getenv("ANDROID_BUILD_TOP");
#if defined(__linux__)
      root += "/out/host/linux-x86";
#elif defined(__APPLE__)
      root += "/out/host/darwin-x86";
#else
#error unsupported OS
#endif
      setenv("ANDROID_ROOT", root.c_str(), 1);
      setenv("LD_LIBRARY_PATH", ":", 0);  // Required by java.lang.System.<clinit>.
    }

    // On target, Cannot use /mnt/sdcard because it is mounted noexec, so use subdir of art-cache
    android_data = (IsHost() ? "/tmp/art-data-XXXXXX" : "/data/art-cache/art-data-XXXXXX");
    if (mkdtemp(&android_data[0]) == NULL) {
      PLOG(FATAL) << "mkdtemp(\"" << &android_data[0] << "\") failed";
    }
    setenv("ANDROID_DATA", android_data.c_str(), 1);
  }

 protected:
  static bool IsHost() {
    return (getenv("ANDROID_BUILD_TOP") != NULL);
  }

  virtual void SetUp() {
    SetEnvironmentVariables(android_data_);
    art_cache_.append(android_data_.c_str());
    art_cache_.append("/art-cache");
    int mkdir_result = mkdir(art_cache_.c_str(), 0700);
    ASSERT_EQ(mkdir_result, 0);

    java_lang_dex_file_ = DexFile::Open(GetLibCoreDexFileName(), GetLibCoreDexFileName());
    boot_class_path_.push_back(java_lang_dex_file_);

    std::string min_heap_string(StringPrintf("-Xms%zdm", Heap::kDefaultInitialSize / MB));
    std::string max_heap_string(StringPrintf("-Xmx%zdm", Heap::kDefaultMaximumSize / MB));

    Runtime::Options options;
    options.push_back(std::make_pair("compiler", reinterpret_cast<void*>(NULL)));
    options.push_back(std::make_pair("bootclasspath", &boot_class_path_));
    options.push_back(std::make_pair("-Xcheck:jni", reinterpret_cast<void*>(NULL)));
    options.push_back(std::make_pair(min_heap_string.c_str(), reinterpret_cast<void*>(NULL)));
    options.push_back(std::make_pair(max_heap_string.c_str(), reinterpret_cast<void*>(NULL)));
    if(!Runtime::Create(options, false)) {
      LOG(FATAL) << "Failed to create runtime";
      return;
    }
    runtime_.reset(Runtime::Current());
    // Runtime::Create acquired the mutator_lock_ that is normally given away when we Runtime::Start,
    // give it away now and then switch to a more managable ScopedObjectAccess.
    Thread::Current()->TransitionFromRunnableToSuspended(kNative);
    // Whilst we're in native take the opportunity to initialize well known classes.
    WellKnownClasses::InitClasses(Thread::Current()->GetJniEnv());
    ScopedObjectAccess soa(Thread::Current());
    ASSERT_TRUE(runtime_.get() != NULL);
    class_linker_ = runtime_->GetClassLinker();

    InstructionSet instruction_set = kNone;
#if defined(__arm__)
    instruction_set = kThumb2;
#elif defined(__mips__)
    instruction_set = kMips;
#elif defined(__i386__)
    instruction_set = kX86;
#endif

    // TODO: make selectable
#if defined(ART_USE_PORTABLE_COMPILER)
    CompilerBackend compiler_backend = kPortable;
#else
    CompilerBackend compiler_backend = kQuick;
#endif

    runtime_->SetJniDlsymLookupStub(CompilerDriver::CreateJniDlsymLookupStub(instruction_set));
    runtime_->SetAbstractMethodErrorStubArray(CompilerDriver::CreateAbstractMethodErrorStub(instruction_set));
    for (int i = 0; i < Runtime::kLastTrampolineMethodType; i++) {
      Runtime::TrampolineType type = Runtime::TrampolineType(i);
      if (!runtime_->HasResolutionStubArray(type)) {
        runtime_->SetResolutionStubArray(
            CompilerDriver::CreateResolutionStub(instruction_set, type), type);
      }
    }
    if (!runtime_->HasResolutionMethod()) {
      runtime_->SetResolutionMethod(runtime_->CreateResolutionMethod());
    }
    for (int i = 0; i < Runtime::kLastCalleeSaveType; i++) {
      Runtime::CalleeSaveType type = Runtime::CalleeSaveType(i);
      if (!runtime_->HasCalleeSaveMethod(type)) {
        runtime_->SetCalleeSaveMethod(
            runtime_->CreateCalleeSaveMethod(instruction_set, type), type);
      }
    }
    class_linker_->FixupDexCaches(runtime_->GetResolutionMethod());
    image_classes_.reset(new std::set<std::string>);
    compiler_driver_.reset(new CompilerDriver(compiler_backend, instruction_set, true, 2, false, image_classes_.get(),
                                              true, true));

    // Create the heap thread pool so that the GC runs in parallel for tests. Normally, the thread
    // pool is created by the runtime.
    runtime_->GetHeap()->CreateThreadPool();

    runtime_->GetHeap()->VerifyHeap();  // Check for heap corruption before the test
  }

  virtual void TearDown() {
    const char* android_data = getenv("ANDROID_DATA");
    ASSERT_TRUE(android_data != NULL);
    DIR* dir = opendir(art_cache_.c_str());
    ASSERT_TRUE(dir != NULL);
    dirent* e;
    while ((e = readdir(dir)) != NULL) {
      if ((strcmp(e->d_name, ".") == 0) || (strcmp(e->d_name, "..") == 0)) {
        continue;
      }
      std::string filename(art_cache_);
      filename.push_back('/');
      filename.append(e->d_name);
      int unlink_result = unlink(filename.c_str());
      ASSERT_EQ(0, unlink_result);
    }
    closedir(dir);
    int rmdir_cache_result = rmdir(art_cache_.c_str());
    ASSERT_EQ(0, rmdir_cache_result);
    int rmdir_data_result = rmdir(android_data_.c_str());
    ASSERT_EQ(0, rmdir_data_result);

    // icu4c has a fixed 10-element array "gCommonICUDataArray".
    // If we run > 10 tests, we fill that array and u_setCommonData fails.
    // There's a function to clear the array, but it's not public...
    typedef void (*IcuCleanupFn)();
    void* sym = dlsym(RTLD_DEFAULT, "u_cleanup_" U_ICU_VERSION_SHORT);
    CHECK(sym != NULL);
    IcuCleanupFn icu_cleanup_fn = reinterpret_cast<IcuCleanupFn>(sym);
    (*icu_cleanup_fn)();

    compiler_driver_.reset();
    image_classes_.reset();
    STLDeleteElements(&opened_dex_files_);

    Runtime::Current()->GetHeap()->VerifyHeap();  // Check for heap corruption after the test
  }

  std::string GetLibCoreDexFileName() {
    return GetDexFileName("core");
  }

  std::string GetDexFileName(const std::string& jar_prefix) {
    if (IsHost()) {
      const char* host_dir = getenv("ANDROID_HOST_OUT");
      CHECK(host_dir != NULL);
      return StringPrintf("%s/framework/%s-hostdex.jar", host_dir, jar_prefix.c_str());
    }
    return StringPrintf("%s/framework/%s.jar", GetAndroidRoot(), jar_prefix.c_str());
  }

  std::string GetTestAndroidRoot() {
    if (IsHost()) {
      const char* host_dir = getenv("ANDROID_HOST_OUT");
      CHECK(host_dir != NULL);
      return host_dir;
    }
    return GetAndroidRoot();
  }

  const DexFile* OpenTestDexFile(const char* name) {
    CHECK(name != NULL);
    std::string filename;
    if (IsHost()) {
      filename += getenv("ANDROID_HOST_OUT");
      filename += "/framework/";
    } else {
      filename += "/data/nativetest/art/";
    }
    filename += "art-test-dex-";
    filename += name;
    filename += ".jar";
    const DexFile* dex_file = DexFile::Open(filename, filename);
    CHECK(dex_file != NULL) << "Failed to open " << filename;
    opened_dex_files_.push_back(dex_file);
    return dex_file;
  }

  jobject LoadDex(const char* dex_name)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    const DexFile* dex_file = OpenTestDexFile(dex_name);
    CHECK(dex_file != NULL);
    class_linker_->RegisterDexFile(*dex_file);
    std::vector<const DexFile*> class_path;
    class_path.push_back(dex_file);
    ScopedObjectAccessUnchecked soa(Thread::Current());
    ScopedLocalRef<jobject> class_loader_local(soa.Env(),
        soa.Env()->AllocObject(WellKnownClasses::dalvik_system_PathClassLoader));
    jobject class_loader = soa.Env()->NewGlobalRef(class_loader_local.get());
    soa.Self()->SetClassLoaderOverride(soa.Decode<mirror::ClassLoader*>(class_loader_local.get()));
    Runtime::Current()->SetCompileTimeClassPath(class_loader, class_path);
    return class_loader;
  }

  void CompileClass(mirror::ClassLoader* class_loader, const char* class_name) {
    std::string class_descriptor(DotToDescriptor(class_name));
    mirror::Class* klass = class_linker_->FindClass(class_descriptor.c_str(), class_loader);
    CHECK(klass != NULL) << "Class not found " << class_name;
    for (size_t i = 0; i < klass->NumDirectMethods(); i++) {
      CompileMethod(klass->GetDirectMethod(i));
    }
    for (size_t i = 0; i < klass->NumVirtualMethods(); i++) {
      CompileMethod(klass->GetVirtualMethod(i));
    }
  }

  void CompileMethod(mirror::AbstractMethod* method) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    CHECK(method != NULL);
    compiler_driver_->CompileOne(method);
    MakeExecutable(method);

    MakeExecutable(runtime_->GetJniDlsymLookupStub());
  }

  void CompileDirectMethod(mirror::ClassLoader* class_loader,
                           const char* class_name,
                           const char* method_name,
                           const char* signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    std::string class_descriptor(DotToDescriptor(class_name));
    mirror::Class* klass = class_linker_->FindClass(class_descriptor.c_str(), class_loader);
    CHECK(klass != NULL) << "Class not found " << class_name;
    mirror::AbstractMethod* method = klass->FindDirectMethod(method_name, signature);
    CHECK(method != NULL) << "Direct method not found: "
                          << class_name << "." << method_name << signature;
    CompileMethod(method);
  }

  void CompileVirtualMethod(mirror::ClassLoader* class_loader,
                            const char* class_name,
                            const char* method_name,
                            const char* signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    std::string class_descriptor(DotToDescriptor(class_name));
    mirror::Class* klass = class_linker_->FindClass(class_descriptor.c_str(), class_loader);
    CHECK(klass != NULL) << "Class not found " << class_name;
    mirror::AbstractMethod* method = klass->FindVirtualMethod(method_name, signature);
    CHECK(method != NULL) << "Virtual method not found: "
                          << class_name << "." << method_name << signature;
    CompileMethod(method);
  }

  void ReserveImageSpace() {
    // Reserve where the image will be loaded up front so that other parts of test set up don't
    // accidentally end up colliding with the fixed memory address when we need to load the image.
    image_reservation_.reset(MemMap::MapAnonymous("image reservation", (byte*)ART_BASE_ADDRESS,
                                                  (size_t)100 * 1024 * 1024,  // 100MB
                                                  PROT_NONE));
  }

  void UnreserveImageSpace() {
    image_reservation_.reset();
  }

  std::string android_data_;
  std::string art_cache_;
  const DexFile* java_lang_dex_file_;  // owned by runtime_
  std::vector<const DexFile*> boot_class_path_;
  UniquePtr<Runtime> runtime_;
  // Owned by the runtime
  ClassLinker* class_linker_;
  UniquePtr<CompilerDriver> compiler_driver_;
  UniquePtr<std::set<std::string> > image_classes_;

 private:
  std::vector<const DexFile*> opened_dex_files_;
  UniquePtr<MemMap> image_reservation_;
};

// Sets a CheckJni abort hook to catch failures. Note that this will cause CheckJNI to carry on
// rather than aborting, so be careful!
class CheckJniAbortCatcher {
 public:
  CheckJniAbortCatcher() : vm_(Runtime::Current()->GetJavaVM()) {
    vm_->check_jni_abort_hook = Hook;
    vm_->check_jni_abort_hook_data = &actual_;
  }

  ~CheckJniAbortCatcher() {
    vm_->check_jni_abort_hook = NULL;
    vm_->check_jni_abort_hook_data = NULL;
    EXPECT_TRUE(actual_.empty()) << actual_;
  }

  void Check(const char* expected_text) {
    EXPECT_TRUE(actual_.find(expected_text) != std::string::npos) << "\n"
        << "Expected to find: " << expected_text << "\n"
        << "In the output   : " << actual_;
    actual_.clear();
  }

 private:
  static void Hook(void* data, const std::string& reason) {
    // We use += because when we're hooking the aborts like this, multiple problems can be found.
    *reinterpret_cast<std::string*>(data) += reason;
  }

  JavaVMExt* vm_;
  std::string actual_;

  DISALLOW_COPY_AND_ASSIGN(CheckJniAbortCatcher);
};

// TODO: These tests were disabled for portable when we went to having
// MCLinker link LLVM ELF output because we no longer just have code
// blobs in memory. We'll need to dlopen to load and relocate
// temporary output to resurrect these tests.
#if defined(ART_USE_PORTABLE_COMPILER)
#define TEST_DISABLED_FOR_PORTABLE() printf("WARNING: TEST DISABLED FOR PORTABLE\n"); return
#else
#define TEST_DISABLED_FOR_PORTABLE()
#endif

}  // namespace art

namespace std {

// TODO: isn't gtest supposed to be able to print STL types for itself?
template <typename T>
std::ostream& operator<<(std::ostream& os, const std::vector<T>& rhs) {
  os << ::art::ToString(rhs);
  return os;
}

}  // namespace std