/*
 * Copyright (C) 2017 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 "dex_file_tracking_registrar.h"

#include <deque>
#include <tuple>

#include <android-base/logging.h>

// For dex tracking through poisoning. Note: Requires forcing sanitization. This is the reason for
// the ifdefs and early include.
#ifdef ART_DEX_FILE_ACCESS_TRACKING
#ifndef ART_ENABLE_ADDRESS_SANITIZER
#define ART_ENABLE_ADDRESS_SANITIZER
#endif
#endif
#include "base/memory_tool.h"

#include "class_accessor-inl.h"
#include "code_item_accessors-inl.h"
#include "dex_file-inl.h"

namespace art {
namespace dex {
namespace tracking {

// If true, poison dex files to track accesses.
static constexpr bool kDexFileAccessTracking =
#ifdef ART_DEX_FILE_ACCESS_TRACKING
    true;
#else
    false;
#endif

// The following are configurations of poisoning certain sections of a Dex File.
// More will be added
enum DexTrackingType {
  // Poisons all of a Dex File when set.
  kWholeDexTracking,
  // Poisons all Code Items of a Dex File when set.
  kCodeItemTracking,
  // Poisons all subsections of a Code Item, except the Insns bytecode array
  // section, when set for all Code Items in a Dex File.
  kCodeItemNonInsnsTracking,
  // Poisons all subsections of a Code Item, except the Insns bytecode array
  // section, when set for all Code Items in a Dex File.
  // Additionally unpoisons the entire Code Item when method is a class
  // initializer.
  kCodeItemNonInsnsNoClinitTracking,
  // Poisons the size and offset information along with the first instruction.
  // This is so that accessing multiple instructions while accessing a code item
  // once will not trigger unnecessary accesses.
  kCodeItemStartTracking,
  // Poisons all String Data Items of a Dex Files when set.
  kStringDataItemTracking,
  // Poisons the first byte of the utf16_size value and the first byte of the
  // data section for all String Data Items of a Dex File.
  kStringDataItemStartTracking,
  // Poisons based on a custom tracking system which can be specified in
  // SetDexSections
  kCustomTracking,
};

// Intended for local changes only.
// Represents the current configuration being run.
static constexpr DexTrackingType kCurrentTrackingSystem = kWholeDexTracking;

// Intended for local changes only.
void DexFileTrackingRegistrar::SetDexSections() {
  if (kDexFileAccessTracking && dex_file_ != nullptr) {
    // Logs the Dex File's location and starting address if tracking is enabled
    LOG(ERROR) << "RegisterDexFile: " << dex_file_->GetLocation() + " @ " << std::hex
               << reinterpret_cast<uintptr_t>(dex_file_->Begin());
    switch (kCurrentTrackingSystem) {
      case kWholeDexTracking:
        SetDexFileRegistration(true);
        break;
      case kCodeItemTracking:
        SetAllCodeItemRegistration(true);
        break;
      case kCodeItemNonInsnsTracking:
        SetAllCodeItemRegistration(true);
        SetAllInsnsRegistration(false);
        break;
      case kCodeItemNonInsnsNoClinitTracking:
        SetAllCodeItemRegistration(true);
        SetAllInsnsRegistration(false);
        SetCodeItemRegistration("<clinit>", false);
        break;
      case kCodeItemStartTracking:
        SetAllCodeItemStartRegistration(true);
        break;
      case kStringDataItemTracking:
        SetAllStringDataRegistration(true);
        break;
      case kStringDataItemStartTracking:
        SetAllStringDataStartRegistration(true);
        break;
      case kCustomTracking:
        // TODO: Add/remove additional calls here to (un)poison sections of
        // dex_file_
        break;
      default:
        break;
    }
  }
}

void RegisterDexFile(const DexFile* dex_file) {
  DexFileTrackingRegistrar dex_tracking_registrar(dex_file);
  dex_tracking_registrar.SetDexSections();
  dex_tracking_registrar.SetCurrentRanges();
}

inline void SetRegistrationRange(const void* begin, size_t size, bool should_poison) {
  if (should_poison) {
    MEMORY_TOOL_MAKE_NOACCESS(begin, size);
  } else {
    // Note: MEMORY_TOOL_MAKE_UNDEFINED has the same functionality with Address
    // Sanitizer.
    // Historical note: The difference has not been tested with Valgrind.
    MEMORY_TOOL_MAKE_DEFINED(begin, size);
  }
}

void DexFileTrackingRegistrar::SetCurrentRanges() {
  // This also empties range_values_ to avoid redundant (un)poisoning upon
  // subsequent calls.
  while (!range_values_.empty()) {
    const std::tuple<const void*, size_t, bool>& current_range = range_values_.front();
    SetRegistrationRange(std::get<0>(current_range),
                         std::get<1>(current_range),
                         std::get<2>(current_range));
    range_values_.pop_front();
  }
}

void DexFileTrackingRegistrar::SetDexFileRegistration(bool should_poison) {
  const void* dex_file_begin = reinterpret_cast<const void*>(dex_file_->Begin());
  size_t dex_file_size = dex_file_->Size();
  range_values_.push_back(std::make_tuple(dex_file_begin, dex_file_size, should_poison));
}

void DexFileTrackingRegistrar::SetAllCodeItemRegistration(bool should_poison) {
  for (ClassAccessor accessor : dex_file_->GetClasses()) {
    for (const ClassAccessor::Method& method : accessor.GetMethods()) {
      const DexFile::CodeItem* code_item = method.GetCodeItem();
      if (code_item != nullptr) {
        const void* code_item_begin = reinterpret_cast<const void*>(code_item);
        size_t code_item_size = dex_file_->GetCodeItemSize(*code_item);
        range_values_.push_back(std::make_tuple(code_item_begin, code_item_size, should_poison));
      }
    }
  }
}

void DexFileTrackingRegistrar::SetAllCodeItemStartRegistration(bool should_poison) {
  for (ClassAccessor class_accessor : dex_file_->GetClasses()) {
    for (const ClassAccessor::Method& method : class_accessor.GetMethods()) {
      const DexFile::CodeItem* code_item = method.GetCodeItem();
      if (code_item != nullptr) {
        const void* code_item_begin = reinterpret_cast<const void*>(code_item);
        size_t code_item_start = reinterpret_cast<size_t>(code_item);
        CodeItemInstructionAccessor accessor(*dex_file_, code_item);
        size_t code_item_start_end = reinterpret_cast<size_t>(accessor.Insns());
        size_t code_item_start_size = code_item_start_end - code_item_start;
        range_values_.push_back(std::make_tuple(code_item_begin,
                                                code_item_start_size,
                                                should_poison));
      }
    }
  }
}

void DexFileTrackingRegistrar::SetAllInsnsRegistration(bool should_poison) {
  for (ClassAccessor class_accessor : dex_file_->GetClasses()) {
    for (const ClassAccessor::Method& method : class_accessor.GetMethods()) {
      const DexFile::CodeItem* code_item = method.GetCodeItem();
      if (code_item != nullptr) {
        CodeItemInstructionAccessor accessor(*dex_file_, code_item);
        const void* insns_begin = reinterpret_cast<const void*>(accessor.Insns());
        // Member insns_size_in_code_units_ is in 2-byte units
        size_t insns_size = accessor.InsnsSizeInCodeUnits() * 2;
        range_values_.push_back(std::make_tuple(insns_begin, insns_size, should_poison));
      }
    }
  }
}

void DexFileTrackingRegistrar::SetCodeItemRegistration(const char* class_name, bool should_poison) {
  for (ClassAccessor accessor : dex_file_->GetClasses()) {
    for (const ClassAccessor::Method& method : accessor.GetMethods()) {
      const DexFile::MethodId& methodid_item = dex_file_->GetMethodId(method.GetIndex());
      const char * methodid_name = dex_file_->GetMethodName(methodid_item);
      const DexFile::CodeItem* code_item = method.GetCodeItem();
      if (code_item != nullptr && strcmp(methodid_name, class_name) == 0) {
        const void* code_item_begin = reinterpret_cast<const void*>(code_item);
        size_t code_item_size = dex_file_->GetCodeItemSize(*code_item);
        range_values_.push_back(std::make_tuple(code_item_begin, code_item_size, should_poison));
      }
    }
  }
}

void DexFileTrackingRegistrar::SetAllStringDataStartRegistration(bool should_poison) {
  for (size_t stringid_ctr = 0; stringid_ctr < dex_file_->NumStringIds(); ++stringid_ctr) {
    const DexFile::StringId & string_id = dex_file_->GetStringId(StringIndex(stringid_ctr));
    const void* string_data_begin = reinterpret_cast<const void*>(dex_file_->Begin() + string_id.string_data_off_);
    // Data Section of String Data Item
    const void* string_data_data_begin = reinterpret_cast<const void*>(dex_file_->GetStringData(string_id));
    range_values_.push_back(std::make_tuple(string_data_begin, 1, should_poison));
    range_values_.push_back(std::make_tuple(string_data_data_begin, 1, should_poison));
  }
}

void DexFileTrackingRegistrar::SetAllStringDataRegistration(bool should_poison) {
  size_t map_offset = dex_file_->GetHeader().map_off_;
  auto map_list = reinterpret_cast<const DexFile::MapList*>(dex_file_->Begin() + map_offset);
  for (size_t map_ctr = 0; map_ctr < map_list->size_; ++map_ctr) {
    const DexFile::MapItem& map_item = map_list->list_[map_ctr];
    if (map_item.type_ == DexFile::kDexTypeStringDataItem) {
      const DexFile::MapItem& next_map_item = map_list->list_[map_ctr + 1];
      const void* string_data_begin = reinterpret_cast<const void*>(dex_file_->Begin() + map_item.offset_);
      size_t string_data_size = next_map_item.offset_ - map_item.offset_;
      range_values_.push_back(std::make_tuple(string_data_begin, string_data_size, should_poison));
    }
  }
}

}  // namespace tracking
}  // namespace dex
}  // namespace art