runtime/dex_file.cc

/*
 * 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 "dex_file.h"

#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>
#include <sys/mman.h>  // For the PROT_* and MAP_* constants.
#include <zlib.h>

#include <memory>
#include <sstream>
#include <type_traits>

#include "android-base/stringprintf.h"

#include "base/enums.h"
#include "base/logging.h"
#include "base/stl_util.h"
#include "dex_file-inl.h"
#include "dex_file_loader.h"
#include "jvalue.h"
#include "leb128.h"
#include "mem_map.h"
#include "os.h"
#include "standard_dex_file.h"
#include "utf-inl.h"
#include "utils.h"

namespace art {

using android::base::StringPrintf;

static_assert(sizeof(dex::StringIndex) == sizeof(uint32_t), "StringIndex size is wrong");
static_assert(std::is_trivially_copyable<dex::StringIndex>::value, "StringIndex not trivial");
static_assert(sizeof(dex::TypeIndex) == sizeof(uint16_t), "TypeIndex size is wrong");
static_assert(std::is_trivially_copyable<dex::TypeIndex>::value, "TypeIndex not trivial");

uint32_t DexFile::CalculateChecksum() const {
  const uint32_t non_sum = OFFSETOF_MEMBER(DexFile::Header, signature_);
  const uint8_t* non_sum_ptr = Begin() + non_sum;
  return adler32(adler32(0L, Z_NULL, 0), non_sum_ptr, Size() - non_sum);
}

struct DexFile::AnnotationValue {
  JValue value_;
  uint8_t type_;
};

int DexFile::GetPermissions() const {
  if (mem_map_.get() == nullptr) {
    return 0;
  } else {
    return mem_map_->GetProtect();
  }
}

bool DexFile::IsReadOnly() const {
  return GetPermissions() == PROT_READ;
}

bool DexFile::EnableWrite() const {
  CHECK(IsReadOnly());
  if (mem_map_.get() == nullptr) {
    return false;
  } else {
    return mem_map_->Protect(PROT_READ | PROT_WRITE);
  }
}

bool DexFile::DisableWrite() const {
  CHECK(!IsReadOnly());
  if (mem_map_.get() == nullptr) {
    return false;
  } else {
    return mem_map_->Protect(PROT_READ);
  }
}

DexFile::DexFile(const uint8_t* base,
                 size_t size,
                 const std::string& location,
                 uint32_t location_checksum,
                 const OatDexFile* oat_dex_file)
    : begin_(base),
      size_(size),
      location_(location),
      location_checksum_(location_checksum),
      header_(reinterpret_cast<const Header*>(base)),
      string_ids_(reinterpret_cast<const StringId*>(base + header_->string_ids_off_)),
      type_ids_(reinterpret_cast<const TypeId*>(base + header_->type_ids_off_)),
      field_ids_(reinterpret_cast<const FieldId*>(base + header_->field_ids_off_)),
      method_ids_(reinterpret_cast<const MethodId*>(base + header_->method_ids_off_)),
      proto_ids_(reinterpret_cast<const ProtoId*>(base + header_->proto_ids_off_)),
      class_defs_(reinterpret_cast<const ClassDef*>(base + header_->class_defs_off_)),
      method_handles_(nullptr),
      num_method_handles_(0),
      call_site_ids_(nullptr),
      num_call_site_ids_(0),
      oat_dex_file_(oat_dex_file) {
  CHECK(begin_ != nullptr) << GetLocation();
  CHECK_GT(size_, 0U) << GetLocation();
  // Check base (=header) alignment.
  // Must be 4-byte aligned to avoid undefined behavior when accessing
  // any of the sections via a pointer.
  CHECK_ALIGNED(begin_, alignof(Header));

  InitializeSectionsFromMapList();
}

DexFile::~DexFile() {
  // We don't call DeleteGlobalRef on dex_object_ because we're only called by DestroyJavaVM, and
  // that's only called after DetachCurrentThread, which means there's no JNIEnv. We could
  // re-attach, but cleaning up these global references is not obviously useful. It's not as if
  // the global reference table is otherwise empty!
}

bool DexFile::Init(std::string* error_msg) {
  if (!CheckMagicAndVersion(error_msg)) {
    return false;
  }
  return true;
}

bool DexFile::CheckMagicAndVersion(std::string* error_msg) const {
  if (!IsMagicValid()) {
    std::ostringstream oss;
    oss << "Unrecognized magic number in "  << GetLocation() << ":"
            << " " << header_->magic_[0]
            << " " << header_->magic_[1]
            << " " << header_->magic_[2]
            << " " << header_->magic_[3];
    *error_msg = oss.str();
    return false;
  }
  if (!IsVersionValid()) {
    std::ostringstream oss;
    oss << "Unrecognized version number in "  << GetLocation() << ":"
            << " " << header_->magic_[4]
            << " " << header_->magic_[5]
            << " " << header_->magic_[6]
            << " " << header_->magic_[7];
    *error_msg = oss.str();
    return false;
  }
  return true;
}

void DexFile::InitializeSectionsFromMapList() {
  const MapList* map_list = reinterpret_cast<const MapList*>(begin_ + header_->map_off_);
  if (header_->map_off_ == 0 || header_->map_off_ > size_) {
    // Bad offset. The dex file verifier runs after this method and will reject the file.
    return;
  }
  const size_t count = map_list->size_;

  size_t map_limit = header_->map_off_ + count * sizeof(MapItem);
  if (header_->map_off_ >= map_limit || map_limit > size_) {
    // Overflow or out out of bounds. The dex file verifier runs after
    // this method and will reject the file as it is malformed.
    return;
  }

  for (size_t i = 0; i < count; ++i) {
    const MapItem& map_item = map_list->list_[i];
    if (map_item.type_ == kDexTypeMethodHandleItem) {
      method_handles_ = reinterpret_cast<const MethodHandleItem*>(begin_ + map_item.offset_);
      num_method_handles_ = map_item.size_;
    } else if (map_item.type_ == kDexTypeCallSiteIdItem) {
      call_site_ids_ = reinterpret_cast<const CallSiteIdItem*>(begin_ + map_item.offset_);
      num_call_site_ids_ = map_item.size_;
    }
  }
}

uint32_t DexFile::Header::GetVersion() const {
  const char* version = reinterpret_cast<const char*>(&magic_[kDexMagicSize]);
  return atoi(version);
}

const DexFile::ClassDef* DexFile::FindClassDef(dex::TypeIndex type_idx) const {
  size_t num_class_defs = NumClassDefs();
  // Fast path for rare no class defs case.
  if (num_class_defs == 0) {
    return nullptr;
  }
  for (size_t i = 0; i < num_class_defs; ++i) {
    const ClassDef& class_def = GetClassDef(i);
    if (class_def.class_idx_ == type_idx) {
      return &class_def;
    }
  }
  return nullptr;
}

uint32_t DexFile::FindCodeItemOffset(const DexFile::ClassDef& class_def,
                                     uint32_t method_idx) const {
  const uint8_t* class_data = GetClassData(class_def);
  CHECK(class_data != nullptr);
  ClassDataItemIterator it(*this, class_data);
  it.SkipAllFields();
  while (it.HasNextDirectMethod()) {
    if (it.GetMemberIndex() == method_idx) {
      return it.GetMethodCodeItemOffset();
    }
    it.Next();
  }
  while (it.HasNextVirtualMethod()) {
    if (it.GetMemberIndex() == method_idx) {
      return it.GetMethodCodeItemOffset();
    }
    it.Next();
  }
  LOG(FATAL) << "Unable to find method " << method_idx;
  UNREACHABLE();
}

uint32_t DexFile::GetCodeItemSize(const DexFile::CodeItem& code_item) {
  uintptr_t code_item_start = reinterpret_cast<uintptr_t>(&code_item);
  uint32_t insns_size = code_item.insns_size_in_code_units_;
  uint32_t tries_size = code_item.tries_size_;
  const uint8_t* handler_data = GetCatchHandlerData(code_item, 0);

  if (tries_size == 0 || handler_data == nullptr) {
    uintptr_t insns_end = reinterpret_cast<uintptr_t>(&code_item.insns_[insns_size]);
    return insns_end - code_item_start;
  } else {
    // Get the start of the handler data.
    uint32_t handlers_size = DecodeUnsignedLeb128(&handler_data);
    // Manually read each handler.
    for (uint32_t i = 0; i < handlers_size; ++i) {
      int32_t uleb128_count = DecodeSignedLeb128(&handler_data) * 2;
      if (uleb128_count <= 0) {
        uleb128_count = -uleb128_count + 1;
      }
      for (int32_t j = 0; j < uleb128_count; ++j) {
        DecodeUnsignedLeb128(&handler_data);
      }
    }
    return reinterpret_cast<uintptr_t>(handler_data) - code_item_start;
  }
}

const DexFile::FieldId* DexFile::FindFieldId(const DexFile::TypeId& declaring_klass,
                                             const DexFile::StringId& name,
                                             const DexFile::TypeId& type) const {
  // Binary search MethodIds knowing that they are sorted by class_idx, name_idx then proto_idx
  const dex::TypeIndex class_idx = GetIndexForTypeId(declaring_klass);
  const dex::StringIndex name_idx = GetIndexForStringId(name);
  const dex::TypeIndex type_idx = GetIndexForTypeId(type);
  int32_t lo = 0;
  int32_t hi = NumFieldIds() - 1;
  while (hi >= lo) {
    int32_t mid = (hi + lo) / 2;
    const DexFile::FieldId& field = GetFieldId(mid);
    if (class_idx > field.class_idx_) {
      lo = mid + 1;
    } else if (class_idx < field.class_idx_) {
      hi = mid - 1;
    } else {
      if (name_idx > field.name_idx_) {
        lo = mid + 1;
      } else if (name_idx < field.name_idx_) {
        hi = mid - 1;
      } else {
        if (type_idx > field.type_idx_) {
          lo = mid + 1;
        } else if (type_idx < field.type_idx_) {
          hi = mid - 1;
        } else {
          return &field;
        }
      }
    }
  }
  return nullptr;
}

const DexFile::MethodId* DexFile::FindMethodId(const DexFile::TypeId& declaring_klass,
                                               const DexFile::StringId& name,
                                               const DexFile::ProtoId& signature) const {
  // Binary search MethodIds knowing that they are sorted by class_idx, name_idx then proto_idx
  const dex::TypeIndex class_idx = GetIndexForTypeId(declaring_klass);
  const dex::StringIndex name_idx = GetIndexForStringId(name);
  const uint16_t proto_idx = GetIndexForProtoId(signature);
  int32_t lo = 0;
  int32_t hi = NumMethodIds() - 1;
  while (hi >= lo) {
    int32_t mid = (hi + lo) / 2;
    const DexFile::MethodId& method = GetMethodId(mid);
    if (class_idx > method.class_idx_) {
      lo = mid + 1;
    } else if (class_idx < method.class_idx_) {
      hi = mid - 1;
    } else {
      if (name_idx > method.name_idx_) {
        lo = mid + 1;
      } else if (name_idx < method.name_idx_) {
        hi = mid - 1;
      } else {
        if (proto_idx > method.proto_idx_) {
          lo = mid + 1;
        } else if (proto_idx < method.proto_idx_) {
          hi = mid - 1;
        } else {
          return &method;
        }
      }
    }
  }
  return nullptr;
}

const DexFile::StringId* DexFile::FindStringId(const char* string) const {
  int32_t lo = 0;
  int32_t hi = NumStringIds() - 1;
  while (hi >= lo) {
    int32_t mid = (hi + lo) / 2;
    const DexFile::StringId& str_id = GetStringId(dex::StringIndex(mid));
    const char* str = GetStringData(str_id);
    int compare = CompareModifiedUtf8ToModifiedUtf8AsUtf16CodePointValues(string, str);
    if (compare > 0) {
      lo = mid + 1;
    } else if (compare < 0) {
      hi = mid - 1;
    } else {
      return &str_id;
    }
  }
  return nullptr;
}

const DexFile::TypeId* DexFile::FindTypeId(const char* string) const {
  int32_t lo = 0;
  int32_t hi = NumTypeIds() - 1;
  while (hi >= lo) {
    int32_t mid = (hi + lo) / 2;
    const TypeId& type_id = GetTypeId(dex::TypeIndex(mid));
    const DexFile::StringId& str_id = GetStringId(type_id.descriptor_idx_);
    const char* str = GetStringData(str_id);
    int compare = CompareModifiedUtf8ToModifiedUtf8AsUtf16CodePointValues(string, str);
    if (compare > 0) {
      lo = mid + 1;
    } else if (compare < 0) {
      hi = mid - 1;
    } else {
      return &type_id;
    }
  }
  return nullptr;
}

const DexFile::StringId* DexFile::FindStringId(const uint16_t* string, size_t length) const {
  int32_t lo = 0;
  int32_t hi = NumStringIds() - 1;
  while (hi >= lo) {
    int32_t mid = (hi + lo) / 2;
    const DexFile::StringId& str_id = GetStringId(dex::StringIndex(mid));
    const char* str = GetStringData(str_id);
    int compare = CompareModifiedUtf8ToUtf16AsCodePointValues(str, string, length);
    if (compare > 0) {
      lo = mid + 1;
    } else if (compare < 0) {
      hi = mid - 1;
    } else {
      return &str_id;
    }
  }
  return nullptr;
}

const DexFile::TypeId* DexFile::FindTypeId(dex::StringIndex string_idx) const {
  int32_t lo = 0;
  int32_t hi = NumTypeIds() - 1;
  while (hi >= lo) {
    int32_t mid = (hi + lo) / 2;
    const TypeId& type_id = GetTypeId(dex::TypeIndex(mid));
    if (string_idx > type_id.descriptor_idx_) {
      lo = mid + 1;
    } else if (string_idx < type_id.descriptor_idx_) {
      hi = mid - 1;
    } else {
      return &type_id;
    }
  }
  return nullptr;
}

const DexFile::ProtoId* DexFile::FindProtoId(dex::TypeIndex return_type_idx,
                                             const dex::TypeIndex* signature_type_idxs,
                                             uint32_t signature_length) const {
  int32_t lo = 0;
  int32_t hi = NumProtoIds() - 1;
  while (hi >= lo) {
    int32_t mid = (hi + lo) / 2;
    const DexFile::ProtoId& proto = GetProtoId(mid);
    int compare = return_type_idx.index_ - proto.return_type_idx_.index_;
    if (compare == 0) {
      DexFileParameterIterator it(*this, proto);
      size_t i = 0;
      while (it.HasNext() && i < signature_length && compare == 0) {
        compare = signature_type_idxs[i].index_ - it.GetTypeIdx().index_;
        it.Next();
        i++;
      }
      if (compare == 0) {
        if (it.HasNext()) {
          compare = -1;
        } else if (i < signature_length) {
          compare = 1;
        }
      }
    }
    if (compare > 0) {
      lo = mid + 1;
    } else if (compare < 0) {
      hi = mid - 1;
    } else {
      return &proto;
    }
  }
  return nullptr;
}

// Given a signature place the type ids into the given vector
bool DexFile::CreateTypeList(const StringPiece& signature,
                             dex::TypeIndex* return_type_idx,
                             std::vector<dex::TypeIndex>* param_type_idxs) const {
  if (signature[0] != '(') {
    return false;
  }
  size_t offset = 1;
  size_t end = signature.size();
  bool process_return = false;
  while (offset < end) {
    size_t start_offset = offset;
    char c = signature[offset];
    offset++;
    if (c == ')') {
      process_return = true;
      continue;
    }
    while (c == '[') {  // process array prefix
      if (offset >= end) {  // expect some descriptor following [
        return false;
      }
      c = signature[offset];
      offset++;
    }
    if (c == 'L') {  // process type descriptors
      do {
        if (offset >= end) {  // unexpected early termination of descriptor
          return false;
        }
        c = signature[offset];
        offset++;
      } while (c != ';');
    }
    // TODO: avoid creating a std::string just to get a 0-terminated char array
    std::string descriptor(signature.data() + start_offset, offset - start_offset);
    const DexFile::TypeId* type_id = FindTypeId(descriptor.c_str());
    if (type_id == nullptr) {
      return false;
    }
    dex::TypeIndex type_idx = GetIndexForTypeId(*type_id);
    if (!process_return) {
      param_type_idxs->push_back(type_idx);
    } else {
      *return_type_idx = type_idx;
      return offset == end;  // return true if the signature had reached a sensible end
    }
  }
  return false;  // failed to correctly parse return type
}

const Signature DexFile::CreateSignature(const StringPiece& signature) const {
  dex::TypeIndex return_type_idx;
  std::vector<dex::TypeIndex> param_type_indices;
  bool success = CreateTypeList(signature, &return_type_idx, &param_type_indices);
  if (!success) {
    return Signature::NoSignature();
  }
  const ProtoId* proto_id = FindProtoId(return_type_idx, param_type_indices);
  if (proto_id == nullptr) {
    return Signature::NoSignature();
  }
  return Signature(this, *proto_id);
}

int32_t DexFile::FindTryItem(const CodeItem &code_item, uint32_t address) {
  // Note: Signed type is important for max and min.
  int32_t min = 0;
  int32_t max = code_item.tries_size_ - 1;

  while (min <= max) {
    int32_t mid = min + ((max - min) / 2);

    const art::DexFile::TryItem* ti = GetTryItems(code_item, mid);
    uint32_t start = ti->start_addr_;
    uint32_t end = start + ti->insn_count_;

    if (address < start) {
      max = mid - 1;
    } else if (address >= end) {
      min = mid + 1;
    } else {  // We have a winner!
      return mid;
    }
  }
  // No match.
  return -1;
}

int32_t DexFile::FindCatchHandlerOffset(const CodeItem &code_item, uint32_t address) {
  int32_t try_item = FindTryItem(code_item, address);
  if (try_item == -1) {
    return -1;
  } else {
    return DexFile::GetTryItems(code_item, try_item)->handler_off_;
  }
}

bool DexFile::DecodeDebugLocalInfo(const CodeItem* code_item, bool is_static, uint32_t method_idx,
                                   DexDebugNewLocalCb local_cb, void* context) const {
  DCHECK(local_cb != nullptr);
  if (code_item == nullptr) {
    return false;
  }
  const uint8_t* stream = GetDebugInfoStream(code_item);
  if (stream == nullptr) {
    return false;
  }
  std::vector<LocalInfo> local_in_reg(code_item->registers_size_);

  uint16_t arg_reg = code_item->registers_size_ - code_item->ins_size_;
  if (!is_static) {
    const char* descriptor = GetMethodDeclaringClassDescriptor(GetMethodId(method_idx));
    local_in_reg[arg_reg].name_ = "this";
    local_in_reg[arg_reg].descriptor_ = descriptor;
    local_in_reg[arg_reg].signature_ = nullptr;
    local_in_reg[arg_reg].start_address_ = 0;
    local_in_reg[arg_reg].reg_ = arg_reg;
    local_in_reg[arg_reg].is_live_ = true;
    arg_reg++;
  }

  DexFileParameterIterator it(*this, GetMethodPrototype(GetMethodId(method_idx)));
  DecodeUnsignedLeb128(&stream);  // Line.
  uint32_t parameters_size = DecodeUnsignedLeb128(&stream);
  uint32_t i;
  for (i = 0; i < parameters_size && it.HasNext(); ++i, it.Next()) {
    if (arg_reg >= code_item->registers_size_) {
      LOG(ERROR) << "invalid stream - arg reg >= reg size (" << arg_reg
                 << " >= " << code_item->registers_size_ << ") in " << GetLocation();
      return false;
    }
    uint32_t name_idx = DecodeUnsignedLeb128P1(&stream);
    const char* descriptor = it.GetDescriptor();
    local_in_reg[arg_reg].name_ = StringDataByIdx(dex::StringIndex(name_idx));
    local_in_reg[arg_reg].descriptor_ = descriptor;
    local_in_reg[arg_reg].signature_ = nullptr;
    local_in_reg[arg_reg].start_address_ = 0;
    local_in_reg[arg_reg].reg_ = arg_reg;
    local_in_reg[arg_reg].is_live_ = true;
    switch (*descriptor) {
      case 'D':
      case 'J':
        arg_reg += 2;
        break;
      default:
        arg_reg += 1;
        break;
    }
  }
  if (i != parameters_size || it.HasNext()) {
    LOG(ERROR) << "invalid stream - problem with parameter iterator in " << GetLocation()
               << " for method " << this->PrettyMethod(method_idx);
    return false;
  }

  uint32_t address = 0;
  for (;;)  {
    uint8_t opcode = *stream++;
    switch (opcode) {
      case DBG_END_SEQUENCE:
        // Emit all variables which are still alive at the end of the method.
        for (uint16_t reg = 0; reg < code_item->registers_size_; reg++) {
          if (local_in_reg[reg].is_live_) {
            local_in_reg[reg].end_address_ = code_item->insns_size_in_code_units_;
            local_cb(context, local_in_reg[reg]);
          }
        }
        return true;
      case DBG_ADVANCE_PC:
        address += DecodeUnsignedLeb128(&stream);
        break;
      case DBG_ADVANCE_LINE:
        DecodeSignedLeb128(&stream);  // Line.
        break;
      case DBG_START_LOCAL:
      case DBG_START_LOCAL_EXTENDED: {
        uint16_t reg = DecodeUnsignedLeb128(&stream);
        if (reg >= code_item->registers_size_) {
          LOG(ERROR) << "invalid stream - reg >= reg size (" << reg << " >= "
                     << code_item->registers_size_ << ") in " << GetLocation();
          return false;
        }

        uint32_t name_idx = DecodeUnsignedLeb128P1(&stream);
        uint16_t descriptor_idx = DecodeUnsignedLeb128P1(&stream);
        uint32_t signature_idx = dex::kDexNoIndex;
        if (opcode == DBG_START_LOCAL_EXTENDED) {
          signature_idx = DecodeUnsignedLeb128P1(&stream);
        }

        // Emit what was previously there, if anything
        if (local_in_reg[reg].is_live_) {
          local_in_reg[reg].end_address_ = address;
          local_cb(context, local_in_reg[reg]);
        }

        local_in_reg[reg].name_ = StringDataByIdx(dex::StringIndex(name_idx));
        local_in_reg[reg].descriptor_ =
            StringByTypeIdx(dex::TypeIndex(dchecked_integral_cast<uint16_t>(descriptor_idx)));;
        local_in_reg[reg].signature_ = StringDataByIdx(dex::StringIndex(signature_idx));
        local_in_reg[reg].start_address_ = address;
        local_in_reg[reg].reg_ = reg;
        local_in_reg[reg].is_live_ = true;
        break;
      }
      case DBG_END_LOCAL: {
        uint16_t reg = DecodeUnsignedLeb128(&stream);
        if (reg >= code_item->registers_size_) {
          LOG(ERROR) << "invalid stream - reg >= reg size (" << reg << " >= "
                     << code_item->registers_size_ << ") in " << GetLocation();
          return false;
        }
        // If the register is live, close it properly. Otherwise, closing an already
        // closed register is sloppy, but harmless if no further action is taken.
        if (local_in_reg[reg].is_live_) {
          local_in_reg[reg].end_address_ = address;
          local_cb(context, local_in_reg[reg]);
          local_in_reg[reg].is_live_ = false;
        }
        break;
      }
      case DBG_RESTART_LOCAL: {
        uint16_t reg = DecodeUnsignedLeb128(&stream);
        if (reg >= code_item->registers_size_) {
          LOG(ERROR) << "invalid stream - reg >= reg size (" << reg << " >= "
                     << code_item->registers_size_ << ") in " << GetLocation();
          return false;
        }
        // If the register is live, the "restart" is superfluous,
        // and we don't want to mess with the existing start address.
        if (!local_in_reg[reg].is_live_) {
          local_in_reg[reg].start_address_ = address;
          local_in_reg[reg].is_live_ = true;
        }
        break;
      }
      case DBG_SET_PROLOGUE_END:
      case DBG_SET_EPILOGUE_BEGIN:
        break;
      case DBG_SET_FILE:
        DecodeUnsignedLeb128P1(&stream);  // name.
        break;
      default:
        address += (opcode - DBG_FIRST_SPECIAL) / DBG_LINE_RANGE;
        break;
    }
  }
}

bool DexFile::DecodeDebugPositionInfo(const CodeItem* code_item, DexDebugNewPositionCb position_cb,
                                      void* context) const {
  DCHECK(position_cb != nullptr);
  if (code_item == nullptr) {
    return false;
  }
  const uint8_t* stream = GetDebugInfoStream(code_item);
  if (stream == nullptr) {
    return false;
  }

  PositionInfo entry = PositionInfo();
  entry.line_ = DecodeUnsignedLeb128(&stream);
  uint32_t parameters_size = DecodeUnsignedLeb128(&stream);
  for (uint32_t i = 0; i < parameters_size; ++i) {
    DecodeUnsignedLeb128P1(&stream);  // Parameter name.
  }

  for (;;)  {
    uint8_t opcode = *stream++;
    switch (opcode) {
      case DBG_END_SEQUENCE:
        return true;  // end of stream.
      case DBG_ADVANCE_PC:
        entry.address_ += DecodeUnsignedLeb128(&stream);
        break;
      case DBG_ADVANCE_LINE:
        entry.line_ += DecodeSignedLeb128(&stream);
        break;
      case DBG_START_LOCAL:
        DecodeUnsignedLeb128(&stream);  // reg.
        DecodeUnsignedLeb128P1(&stream);  // name.
        DecodeUnsignedLeb128P1(&stream);  // descriptor.
        break;
      case DBG_START_LOCAL_EXTENDED:
        DecodeUnsignedLeb128(&stream);  // reg.
        DecodeUnsignedLeb128P1(&stream);  // name.
        DecodeUnsignedLeb128P1(&stream);  // descriptor.
        DecodeUnsignedLeb128P1(&stream);  // signature.
        break;
      case DBG_END_LOCAL:
      case DBG_RESTART_LOCAL:
        DecodeUnsignedLeb128(&stream);  // reg.
        break;
      case DBG_SET_PROLOGUE_END:
        entry.prologue_end_ = true;
        break;
      case DBG_SET_EPILOGUE_BEGIN:
        entry.epilogue_begin_ = true;
        break;
      case DBG_SET_FILE: {
        uint32_t name_idx = DecodeUnsignedLeb128P1(&stream);
        entry.source_file_ = StringDataByIdx(dex::StringIndex(name_idx));
        break;
      }
      default: {
        int adjopcode = opcode - DBG_FIRST_SPECIAL;
        entry.address_ += adjopcode / DBG_LINE_RANGE;
        entry.line_ += DBG_LINE_BASE + (adjopcode % DBG_LINE_RANGE);
        if (position_cb(context, entry)) {
          return true;  // early exit.
        }
        entry.prologue_end_ = false;
        entry.epilogue_begin_ = false;
        break;
      }
    }
  }
}

bool DexFile::LineNumForPcCb(void* raw_context, const PositionInfo& entry) {
  LineNumFromPcContext* context = reinterpret_cast<LineNumFromPcContext*>(raw_context);

  // We know that this callback will be called in
  // ascending address order, so keep going until we find
  // a match or we've just gone past it.
  if (entry.address_ > context->address_) {
    // The line number from the previous positions callback
    // wil be the final result.
    return true;
  } else {
    context->line_num_ = entry.line_;
    return entry.address_ == context->address_;
  }
}

// Read a signed integer.  "zwidth" is the zero-based byte count.
int32_t DexFile::ReadSignedInt(const uint8_t* ptr, int zwidth) {
  int32_t val = 0;
  for (int i = zwidth; i >= 0; --i) {
    val = ((uint32_t)val >> 8) | (((int32_t)*ptr++) << 24);
  }
  val >>= (3 - zwidth) * 8;
  return val;
}

// Read an unsigned integer.  "zwidth" is the zero-based byte count,
// "fill_on_right" indicates which side we want to zero-fill from.
uint32_t DexFile::ReadUnsignedInt(const uint8_t* ptr, int zwidth, bool fill_on_right) {
  uint32_t val = 0;
  for (int i = zwidth; i >= 0; --i) {
    val = (val >> 8) | (((uint32_t)*ptr++) << 24);
  }
  if (!fill_on_right) {
    val >>= (3 - zwidth) * 8;
  }
  return val;
}

// Read a signed long.  "zwidth" is the zero-based byte count.
int64_t DexFile::ReadSignedLong(const uint8_t* ptr, int zwidth) {
  int64_t val = 0;
  for (int i = zwidth; i >= 0; --i) {
    val = ((uint64_t)val >> 8) | (((int64_t)*ptr++) << 56);
  }
  val >>= (7 - zwidth) * 8;
  return val;
}

// Read an unsigned long.  "zwidth" is the zero-based byte count,
// "fill_on_right" indicates which side we want to zero-fill from.
uint64_t DexFile::ReadUnsignedLong(const uint8_t* ptr, int zwidth, bool fill_on_right) {
  uint64_t val = 0;
  for (int i = zwidth; i >= 0; --i) {
    val = (val >> 8) | (((uint64_t)*ptr++) << 56);
  }
  if (!fill_on_right) {
    val >>= (7 - zwidth) * 8;
  }
  return val;
}

std::string DexFile::PrettyMethod(uint32_t method_idx, bool with_signature) const {
  if (method_idx >= NumMethodIds()) {
    return StringPrintf("<<invalid-method-idx-%d>>", method_idx);
  }
  const DexFile::MethodId& method_id = GetMethodId(method_idx);
  std::string result;
  const DexFile::ProtoId* proto_id = with_signature ? &GetProtoId(method_id.proto_idx_) : nullptr;
  if (with_signature) {
    AppendPrettyDescriptor(StringByTypeIdx(proto_id->return_type_idx_), &result);
    result += ' ';
  }
  AppendPrettyDescriptor(GetMethodDeclaringClassDescriptor(method_id), &result);
  result += '.';
  result += GetMethodName(method_id);
  if (with_signature) {
    result += '(';
    const DexFile::TypeList* params = GetProtoParameters(*proto_id);
    if (params != nullptr) {
      const char* separator = "";
      for (uint32_t i = 0u, size = params->Size(); i != size; ++i) {
        result += separator;
        separator = ", ";
        AppendPrettyDescriptor(StringByTypeIdx(params->GetTypeItem(i).type_idx_), &result);
      }
    }
    result += ')';
  }
  return result;
}

std::string DexFile::PrettyField(uint32_t field_idx, bool with_type) const {
  if (field_idx >= NumFieldIds()) {
    return StringPrintf("<<invalid-field-idx-%d>>", field_idx);
  }
  const DexFile::FieldId& field_id = GetFieldId(field_idx);
  std::string result;
  if (with_type) {
    result += GetFieldTypeDescriptor(field_id);
    result += ' ';
  }
  AppendPrettyDescriptor(GetFieldDeclaringClassDescriptor(field_id), &result);
  result += '.';
  result += GetFieldName(field_id);
  return result;
}

std::string DexFile::PrettyType(dex::TypeIndex type_idx) const {
  if (type_idx.index_ >= NumTypeIds()) {
    return StringPrintf("<<invalid-type-idx-%d>>", type_idx.index_);
  }
  const DexFile::TypeId& type_id = GetTypeId(type_idx);
  return PrettyDescriptor(GetTypeDescriptor(type_id));
}

// Checks that visibility is as expected. Includes special behavior for M and
// before to allow runtime and build visibility when expecting runtime.
std::ostream& operator<<(std::ostream& os, const DexFile& dex_file) {
  os << StringPrintf("[DexFile: %s dex-checksum=%08x location-checksum=%08x %p-%p]",
                     dex_file.GetLocation().c_str(),
                     dex_file.GetHeader().checksum_, dex_file.GetLocationChecksum(),
                     dex_file.Begin(), dex_file.Begin() + dex_file.Size());
  return os;
}

std::string Signature::ToString() const {
  if (dex_file_ == nullptr) {
    CHECK(proto_id_ == nullptr);
    return "<no signature>";
  }
  const DexFile::TypeList* params = dex_file_->GetProtoParameters(*proto_id_);
  std::string result;
  if (params == nullptr) {
    result += "()";
  } else {
    result += "(";
    for (uint32_t i = 0; i < params->Size(); ++i) {
      result += dex_file_->StringByTypeIdx(params->GetTypeItem(i).type_idx_);
    }
    result += ")";
  }
  result += dex_file_->StringByTypeIdx(proto_id_->return_type_idx_);
  return result;
}

uint32_t Signature::GetNumberOfParameters() const {
  const DexFile::TypeList* params = dex_file_->GetProtoParameters(*proto_id_);
  return (params != nullptr) ? params->Size() : 0;
}

bool Signature::IsVoid() const {
  const char* return_type = dex_file_->GetReturnTypeDescriptor(*proto_id_);
  return strcmp(return_type, "V") == 0;
}

bool Signature::operator==(const StringPiece& rhs) const {
  if (dex_file_ == nullptr) {
    return false;
  }
  StringPiece tail(rhs);
  if (!tail.starts_with("(")) {
    return false;  // Invalid signature
  }
  tail.remove_prefix(1);  // "(";
  const DexFile::TypeList* params = dex_file_->GetProtoParameters(*proto_id_);
  if (params != nullptr) {
    for (uint32_t i = 0; i < params->Size(); ++i) {
      StringPiece param(dex_file_->StringByTypeIdx(params->GetTypeItem(i).type_idx_));
      if (!tail.starts_with(param)) {
        return false;
      }
      tail.remove_prefix(param.length());
    }
  }
  if (!tail.starts_with(")")) {
    return false;
  }
  tail.remove_prefix(1);  // ")";
  return tail == dex_file_->StringByTypeIdx(proto_id_->return_type_idx_);
}

std::ostream& operator<<(std::ostream& os, const Signature& sig) {
  return os << sig.ToString();
}

// Decodes the header section from the class data bytes.
void ClassDataItemIterator::ReadClassDataHeader() {
  CHECK(ptr_pos_ != nullptr);
  header_.static_fields_size_ = DecodeUnsignedLeb128(&ptr_pos_);
  header_.instance_fields_size_ = DecodeUnsignedLeb128(&ptr_pos_);
  header_.direct_methods_size_ = DecodeUnsignedLeb128(&ptr_pos_);
  header_.virtual_methods_size_ = DecodeUnsignedLeb128(&ptr_pos_);
}

void ClassDataItemIterator::ReadClassDataField() {
  field_.field_idx_delta_ = DecodeUnsignedLeb128(&ptr_pos_);
  field_.access_flags_ = DecodeUnsignedLeb128(&ptr_pos_);
  // The user of the iterator is responsible for checking if there
  // are unordered or duplicate indexes.
}

void ClassDataItemIterator::ReadClassDataMethod() {
  method_.method_idx_delta_ = DecodeUnsignedLeb128(&ptr_pos_);
  method_.access_flags_ = DecodeUnsignedLeb128(&ptr_pos_);
  method_.code_off_ = DecodeUnsignedLeb128(&ptr_pos_);
  if (last_idx_ != 0 && method_.method_idx_delta_ == 0) {
    LOG(WARNING) << "Duplicate method in " << dex_file_.GetLocation();
  }
}

EncodedArrayValueIterator::EncodedArrayValueIterator(const DexFile& dex_file,
                                                     const uint8_t* array_data)
    : dex_file_(dex_file),
      array_size_(),
      pos_(-1),
      ptr_(array_data),
      type_(kByte) {
  array_size_ = (ptr_ != nullptr) ? DecodeUnsignedLeb128(&ptr_) : 0;
  if (array_size_ > 0) {
    Next();
  }
}

void EncodedArrayValueIterator::Next() {
  pos_++;
  if (pos_ >= array_size_) {
    return;
  }
  uint8_t value_type = *ptr_++;
  uint8_t value_arg = value_type >> kEncodedValueArgShift;
  size_t width = value_arg + 1;  // assume and correct later
  type_ = static_cast<ValueType>(value_type & kEncodedValueTypeMask);
  switch (type_) {
  case kBoolean:
    jval_.i = (value_arg != 0) ? 1 : 0;
    width = 0;
    break;
  case kByte:
    jval_.i = DexFile::ReadSignedInt(ptr_, value_arg);
    CHECK(IsInt<8>(jval_.i));
    break;
  case kShort:
    jval_.i = DexFile::ReadSignedInt(ptr_, value_arg);
    CHECK(IsInt<16>(jval_.i));
    break;
  case kChar:
    jval_.i = DexFile::ReadUnsignedInt(ptr_, value_arg, false);
    CHECK(IsUint<16>(jval_.i));
    break;
  case kInt:
    jval_.i = DexFile::ReadSignedInt(ptr_, value_arg);
    break;
  case kLong:
    jval_.j = DexFile::ReadSignedLong(ptr_, value_arg);
    break;
  case kFloat:
    jval_.i = DexFile::ReadUnsignedInt(ptr_, value_arg, true);
    break;
  case kDouble:
    jval_.j = DexFile::ReadUnsignedLong(ptr_, value_arg, true);
    break;
  case kString:
  case kType:
  case kMethodType:
  case kMethodHandle:
    jval_.i = DexFile::ReadUnsignedInt(ptr_, value_arg, false);
    break;
  case kField:
  case kMethod:
  case kEnum:
  case kArray:
  case kAnnotation:
    UNIMPLEMENTED(FATAL) << ": type " << type_;
    UNREACHABLE();
  case kNull:
    jval_.l = nullptr;
    width = 0;
    break;
  default:
    LOG(FATAL) << "Unreached";
    UNREACHABLE();
  }
  ptr_ += width;
}

CatchHandlerIterator::CatchHandlerIterator(const DexFile::CodeItem& code_item, uint32_t address) {
  handler_.address_ = -1;
  int32_t offset = -1;

  // Short-circuit the overwhelmingly common cases.
  switch (code_item.tries_size_) {
    case 0:
      break;
    case 1: {
      const DexFile::TryItem* tries = DexFile::GetTryItems(code_item, 0);
      uint32_t start = tries->start_addr_;
      if (address >= start) {
        uint32_t end = start + tries->insn_count_;
        if (address < end) {
          offset = tries->handler_off_;
        }
      }
      break;
    }
    default:
      offset = DexFile::FindCatchHandlerOffset(code_item, address);
  }
  Init(code_item, offset);
}

CatchHandlerIterator::CatchHandlerIterator(const DexFile::CodeItem& code_item,
                                           const DexFile::TryItem& try_item) {
  handler_.address_ = -1;
  Init(code_item, try_item.handler_off_);
}

void CatchHandlerIterator::Init(const DexFile::CodeItem& code_item,
                                int32_t offset) {
  if (offset >= 0) {
    Init(DexFile::GetCatchHandlerData(code_item, offset));
  } else {
    // Not found, initialize as empty
    current_data_ = nullptr;
    remaining_count_ = -1;
    catch_all_ = false;
    DCHECK(!HasNext());
  }
}

void CatchHandlerIterator::Init(const uint8_t* handler_data) {
  current_data_ = handler_data;
  remaining_count_ = DecodeSignedLeb128(&current_data_);

  // If remaining_count_ is non-positive, then it is the negative of
  // the number of catch types, and the catches are followed by a
  // catch-all handler.
  if (remaining_count_ <= 0) {
    catch_all_ = true;
    remaining_count_ = -remaining_count_;
  } else {
    catch_all_ = false;
  }
  Next();
}

void CatchHandlerIterator::Next() {
  if (remaining_count_ > 0) {
    handler_.type_idx_ = dex::TypeIndex(DecodeUnsignedLeb128(&current_data_));
    handler_.address_  = DecodeUnsignedLeb128(&current_data_);
    remaining_count_--;
    return;
  }

  if (catch_all_) {
    handler_.type_idx_ = dex::TypeIndex(DexFile::kDexNoIndex16);
    handler_.address_  = DecodeUnsignedLeb128(&current_data_);
    catch_all_ = false;
    return;
  }

  // no more handler
  remaining_count_ = -1;
}

namespace dex {

std::ostream& operator<<(std::ostream& os, const StringIndex& index) {
  os << "StringIndex[" << index.index_ << "]";
  return os;
}

std::ostream& operator<<(std::ostream& os, const TypeIndex& index) {
  os << "TypeIndex[" << index.index_ << "]";
  return os;
}

}  // namespace dex

}  // namespace art