//===- ELFReader.h --------------------------------------------------------===//
//
//                     The MCLinker Project
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef MCLD_ELF_READER_INTERFACE_H
#define MCLD_ELF_READER_INTERFACE_H
#ifdef ENABLE_UNITTEST
#include <gtest.h>
#endif

#include <llvm/ADT/StringRef.h>
#include <llvm/Support/ELF.h>
#include <llvm/Support/Host.h>

#include <mcld/Module.h>
#include <mcld/LinkerConfig.h>
#include <mcld/MC/MCLDInput.h>
#include <mcld/LD/ResolveInfo.h>
#include <mcld/LD/LDContext.h>
#include <mcld/Target/GNULDBackend.h>
#include <mcld/Support/MemoryRegion.h>
#include <mcld/Support/MemoryArea.h>
#include <mcld/Support/MsgHandling.h>

namespace mcld {

class Module;
class FragmentRef;
class FragmentLinker;
class SectionData;
class LDSection;

/** \class ELFReaderIF
 *  \brief ELFReaderIF provides common interface for all kind of ELF readers.
 */
class ELFReaderIF
{
public:
  ELFReaderIF(GNULDBackend& pBackend)
    : m_Backend(pBackend)
  { }

  virtual ~ELFReaderIF() { }

  /// ELFHeaderSize - return the size of the ELFHeader
  virtual size_t getELFHeaderSize() const = 0;

  /// isELF - is this a ELF file
  virtual bool isELF(void* pELFHeader) const = 0;

  /// isMyEndian - is this ELF file in the same endian to me?
  virtual bool isMyEndian(void* pELFHeader) const = 0;

  /// isMyMachine - is this ELF file generated for the same machine.
  virtual bool isMyMachine(void* pELFHeader) const = 0;

  /// fileType - the file type of this file
  virtual Input::Type fileType(void* pELFHeader) const = 0;

  /// target - the target backend
  const GNULDBackend& target() const { return m_Backend; }
  GNULDBackend&       target()       { return m_Backend; }


  /// readSectionHeaders - read ELF section header table and create LDSections
  virtual bool readSectionHeaders(Input& pInput, void* pELFHeader) const = 0;

  /// readRegularSection - read a regular section and create fragments.
  virtual bool readRegularSection(Input& pInput, SectionData& pSD) const = 0;

  /// readSymbols - read ELF symbols and create LDSymbol
  virtual bool readSymbols(Input& pInput,
                           FragmentLinker& pLinker,
                           const MemoryRegion& pRegion,
                           const char* StrTab) const = 0;

  /// readSignature - read a symbol from the given Input and index in symtab
  /// This is used to get the signature of a group section.
  virtual ResolveInfo* readSignature(Input& pInput,
                                     LDSection& pSymTab,
                                     uint32_t pSymIdx) const = 0;

  /// readRela - read ELF rela and create Relocation
  virtual bool readRela(Input& pInput,
                        FragmentLinker& pLinker,
                        LDSection& pSection,
                        const MemoryRegion& pRegion) const = 0;

  /// readRel - read ELF rel and create Relocation
  virtual bool readRel(Input& pInput,
                       FragmentLinker& pLinker,
                       LDSection& pSection,
                       const MemoryRegion& pRegion) const = 0;

  /// readDynamic - read ELF .dynamic in input dynobj
  virtual bool readDynamic(Input& pInput) const = 0;

protected:
  /// LinkInfo - some section needs sh_link and sh_info, remember them.
  struct LinkInfo {
    LDSection* section;
    uint32_t sh_link;
    uint32_t sh_info;
  };

  typedef std::vector<LinkInfo> LinkInfoList;

protected:
  ResolveInfo::Type getSymType(uint8_t pInfo, uint16_t pShndx) const;

  ResolveInfo::Desc getSymDesc(uint16_t pShndx, const Input& pInput) const;

  ResolveInfo::Binding getSymBinding(uint8_t pBinding,
                                     uint16_t pShndx,
                                     uint8_t pVisibility) const;

  uint64_t getSymValue(uint64_t pValue,
                       uint16_t pShndx,
                       const Input& pInput) const;

  FragmentRef* getSymFragmentRef(Input& pInput,
                                 uint16_t pShndx,
                                 uint32_t pOffset) const;

  ResolveInfo::Visibility getSymVisibility(uint8_t pVis) const;

protected:
  GNULDBackend& m_Backend;
};

/** \class ELFReader
 *  \brief ELFReader is a template scaffolding for partial specification.
 */
template<size_t BIT, bool LITTLEENDIAN>
class ELFReader
{ };

/** \class ELFReader<32, true>
 *  \brief ELFReader<32, true> is a 32-bit, little endian ELFReader.
 */
template<>
class ELFReader<32, true> : public ELFReaderIF
{
public:
  typedef llvm::ELF::Elf32_Ehdr ELFHeader;
  typedef llvm::ELF::Elf32_Shdr SectionHeader;
  typedef llvm::ELF::Elf32_Sym  Symbol;
  typedef llvm::ELF::Elf32_Rel  Rel;
  typedef llvm::ELF::Elf32_Rela Rela;

public:
  ELFReader(GNULDBackend& pBackend);

  ~ELFReader();

  /// ELFHeaderSize - return the size of the ELFHeader
  size_t getELFHeaderSize() const
  { return sizeof(ELFHeader); }

  /// isELF - is this a ELF file
  bool isELF(void* pELFHeader) const;

  /// isMyEndian - is this ELF file in the same endian to me?
  bool isMyEndian(void* pELFHeader) const;

  /// isMyMachine - is this ELF file generated for the same machine.
  bool isMyMachine(void* pELFHeader) const;

  /// fileType - the file type of this file
  Input::Type fileType(void* pELFHeader) const;

  /// readSectionHeaders - read ELF section header table and create LDSections
  bool readSectionHeaders(Input& pInput, void* pELFHeader) const;

  /// readRegularSection - read a regular section and create fragments.
  bool readRegularSection(Input& pInput, SectionData& pSD) const;

  /// readSymbols - read ELF symbols and create LDSymbol
  bool readSymbols(Input& pInput,
                          FragmentLinker& pLinker,
                          const MemoryRegion& pRegion,
                          const char* StrTab) const;

  /// readSignature - read a symbol from the given Input and index in symtab
  /// This is used to get the signature of a group section.
  ResolveInfo* readSignature(Input& pInput,
                                    LDSection& pSymTab,
                                    uint32_t pSymIdx) const;

  /// readRela - read ELF rela and create Relocation
  bool readRela(Input& pInput,
                FragmentLinker& pLinker,
                LDSection& pSection,
                const MemoryRegion& pRegion) const;

  /// readRel - read ELF rel and create Relocation
  bool readRel(Input& pInput,
               FragmentLinker& pLinker,
               LDSection& pSection,
               const MemoryRegion& pRegion) const;

  /// readDynamic - read ELF .dynamic in input dynobj
  bool readDynamic(Input& pInput) const;
};

} // namespace of mcld

#endif