/*
 * Copyright (C) 2012 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.
 */

#ifndef ART_RUNTIME_OAT_ELF_FILE_H_
#define ART_RUNTIME_OAT_ELF_FILE_H_

#include <cstddef>
#include <string>
#include <vector>

#include "android-base/logging.h"
#include "base/macros.h"
#include "base/mem_map.h"
#include "base/os.h"
#include "elf/elf_utils.h"

namespace art HIDDEN {

template <typename ElfTypes>
class ElfFileImpl;

// Explicitly instantiated in elf_file.cc
using ElfFileImpl32 = ElfFileImpl<ElfTypes32>;
using ElfFileImpl64 = ElfFileImpl<ElfTypes64>;

// Used for compile time and runtime for ElfFile access. Because of
// the need for use at runtime, cannot directly use LLVM classes such as
// ELFObjectFile.
class ElfFile {
 public:
  // Loads the program headers.
  // Does not take the ownership of the file. It must stay alive during the `Load` call.
  static ElfFile* Open(File* file,
                       off_t start,
                       size_t file_length,
                       const std::string& file_location,
                       bool low_4gb,
                       /*out*/ std::string* error_msg);

  static ElfFile* Open(File* file,
                       bool low_4gb,
                       /*out*/ std::string* error_msg);

  virtual ~ElfFile() = default;

  // Load segments into memory based on PT_LOAD program headers.
  virtual bool Load(bool executable,
                    bool low_4gb,
                    /*inout*/ MemMap* reservation,
                    /*out*/ std::string* error_msg) = 0;

  virtual const uint8_t* FindDynamicSymbolAddress(const std::string& symbol_name) const = 0;

  // Returns the location of the ELF file, for debugging purposes only.
  // Note that the location is not necessarily a path to a file on disk. It can also be a zip entry
  // inside a zip file.
  const std::string& GetFileLocation() const { return file_location_; }

  uint8_t* GetBaseAddress() const { return base_address_; }

  uint8_t* Begin() const { return map_.Begin(); }

  uint8_t* End() const { return map_.End(); }

  size_t Size() const { return map_.Size(); }

  virtual bool GetLoadedSize(size_t* size, std::string* error_msg) const = 0;

  virtual size_t GetElfSegmentAlignmentFromFile() const = 0;

  virtual bool Is64Bit() const = 0;

 protected:
  ElfFile(File* file, off_t start, size_t file_length, const std::string& file_location)
      : file_(file), start_(start), file_length_(file_length), file_location_(file_location) {
    CHECK(file != nullptr);
  }

  File* const file_;
  const off_t start_;
  const size_t file_length_;
  const std::string file_location_;

  // ELF header mapping. If program_header_only_ is false, will
  // actually point to the entire elf file.
  MemMap map_;
  std::vector<MemMap> segments_;

  // Pointer to start of first PT_LOAD program segment after Load()
  // when program_header_only_ is true.
  uint8_t* base_address_ = nullptr;

  // The program header should always available but use GetProgramHeadersStart() to be sure.
  uint8_t* program_headers_start_ = nullptr;

 private:
  DISALLOW_COPY_AND_ASSIGN(ElfFile);
};

}  // namespace art

#endif  // ART_RUNTIME_OAT_ELF_FILE_H_