runtime/openjdkjvmti/fixed_up_dex_file.cc

/* Copyright (C) 2017 The Android Open Source Project
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This file implements interfaces from the file jvmti.h. This implementation
 * is licensed under the same terms as the file jvmti.h.  The
 * copyright and license information for the file jvmti.h follows.
 *
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
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 * particular file as subject to the "Classpath" exception as provided
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 * version 2 for more details (a copy is included in the LICENSE file that
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#include "fixed_up_dex_file.h"
#include "dex_file-inl.h"

// Runtime includes.
#include "dex_to_dex_decompiler.h"
#include "oat_file.h"
#include "vdex_file.h"

namespace openjdkjvmti {

static void RecomputeDexChecksum(art::DexFile* dex_file)
    REQUIRES_SHARED(art::Locks::mutator_lock_) {
  reinterpret_cast<art::DexFile::Header*>(const_cast<uint8_t*>(dex_file->Begin()))->checksum_ =
      dex_file->CalculateChecksum();
}

// TODO This is more complicated then it seems like it should be.
// The fact we don't keep around the data of where in the flat binary log of dex-quickening changes
// each dex file starts means we need to search for it. Since JVMTI is the exception though we are
// not going to put in the effort to optimize for it.
static void DoDexUnquicken(const art::DexFile& new_dex_file,
                           const art::DexFile& original_dex_file)
    REQUIRES_SHARED(art::Locks::mutator_lock_) {
  const art::OatDexFile* oat_dex = original_dex_file.GetOatDexFile();
  if (oat_dex == nullptr) {
    return;
  }
  const art::OatFile* oat_file = oat_dex->GetOatFile();
  if (oat_file == nullptr) {
    return;
  }
  const art::VdexFile* vdex = oat_file->GetVdexFile();
  if (vdex == nullptr || vdex->GetQuickeningInfo().size() == 0) {
    return;
  }
  const art::ArrayRef<const uint8_t> quickening_info(vdex->GetQuickeningInfo());
  const uint8_t* quickening_info_ptr = quickening_info.data();
  for (const art::OatDexFile* cur_oat_dex : oat_file->GetOatDexFiles()) {
    std::string error;
    std::unique_ptr<const art::DexFile> cur_dex_file(cur_oat_dex->OpenDexFile(&error));
    DCHECK(cur_dex_file.get() != nullptr);
    // Is this the dex file we are looking for?
    if (UNLIKELY(cur_dex_file->Begin() == original_dex_file.Begin())) {
      // Simple sanity check.
      CHECK_EQ(new_dex_file.NumClassDefs(), original_dex_file.NumClassDefs());
      for (uint32_t i = 0; i < new_dex_file.NumClassDefs(); ++i) {
        const art::DexFile::ClassDef& class_def = new_dex_file.GetClassDef(i);
        const uint8_t* class_data = new_dex_file.GetClassData(class_def);
        if (class_data == nullptr) {
          continue;
        }
        for (art::ClassDataItemIterator it(new_dex_file, class_data); it.HasNext(); it.Next()) {
          if (it.IsAtMethod() && it.GetMethodCodeItem() != nullptr) {
            uint32_t quickening_size = *reinterpret_cast<const uint32_t*>(quickening_info_ptr);
            quickening_info_ptr += sizeof(uint32_t);
            art::optimizer::ArtDecompileDEX(
                *it.GetMethodCodeItem(),
                art::ArrayRef<const uint8_t>(quickening_info_ptr, quickening_size),
                /*decompile_return_instruction*/true);
            quickening_info_ptr += quickening_size;
          }
        }
      }
      // We don't need to bother looking through the rest of the dex-files.
      break;
    } else {
      // Not the dex file we want. Skip over all the quickening info for all its classes.
      for (uint32_t i = 0; i < cur_dex_file->NumClassDefs(); ++i) {
        const art::DexFile::ClassDef& class_def = cur_dex_file->GetClassDef(i);
        const uint8_t* class_data = cur_dex_file->GetClassData(class_def);
        if (class_data == nullptr) {
          continue;
        }
        for (art::ClassDataItemIterator it(*cur_dex_file, class_data); it.HasNext(); it.Next()) {
          if (it.IsAtMethod() && it.GetMethodCodeItem() != nullptr) {
            uint32_t quickening_size = *reinterpret_cast<const uint32_t*>(quickening_info_ptr);
            quickening_info_ptr += sizeof(uint32_t);
            quickening_info_ptr += quickening_size;
          }
        }
      }
    }
  }
}

std::unique_ptr<FixedUpDexFile> FixedUpDexFile::Create(const art::DexFile& original) {
  // Copy the data into mutable memory.
  std::vector<unsigned char> data;
  data.resize(original.Size());
  memcpy(data.data(), original.Begin(), original.Size());
  std::string error;
  std::unique_ptr<const art::DexFile> new_dex_file(art::DexFile::Open(
      data.data(),
      data.size(),
      /*location*/"Unquickening_dexfile.dex",
      /*location_checksum*/0,
      /*oat_dex_file*/nullptr,
      /*verify*/false,
      /*verify_checksum*/false,
      &error));
  if (new_dex_file.get() == nullptr) {
    LOG(ERROR) << "Unable to open dex file from memory for unquickening! error: " << error;
    return nullptr;
  }

  DoDexUnquicken(*new_dex_file, original);
  RecomputeDexChecksum(const_cast<art::DexFile*>(new_dex_file.get()));
  std::unique_ptr<FixedUpDexFile> ret(new FixedUpDexFile(std::move(new_dex_file), std::move(data)));
  return ret;
}

}  // namespace openjdkjvmti