llvm/lib/Object/MachOObjectFile.cpp

//===- MachOObjectFile.cpp - Mach-O object file binding ---------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the MachOObjectFile class, which binds the MachOObject
// class to the generic ObjectFile wrapper.
//
//===----------------------------------------------------------------------===//

#include "llvm/Object/MachO.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Support/DataExtractor.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"
#include <cctype>
#include <cstring>
#include <limits>

using namespace llvm;
using namespace object;

namespace llvm {
namespace object {

struct nlist_base {
  uint32_t n_strx;
  uint8_t n_type;
  uint8_t n_sect;
  uint16_t n_desc;
};

struct section_base {
  char sectname[16];
  char segname[16];
};

template<typename T>
static void SwapValue(T &Value) {
  Value = sys::SwapByteOrder(Value);
}

template<typename T>
static void SwapStruct(T &Value);

template<>
void SwapStruct(MachO::any_relocation_info &H) {
  SwapValue(H.r_word0);
  SwapValue(H.r_word1);
}

template<>
void SwapStruct(MachO::load_command &L) {
  SwapValue(L.cmd);
  SwapValue(L.cmdsize);
}

template<>
void SwapStruct(nlist_base &S) {
  SwapValue(S.n_strx);
  SwapValue(S.n_desc);
}

template<>
void SwapStruct(MachO::section &S) {
  SwapValue(S.addr);
  SwapValue(S.size);
  SwapValue(S.offset);
  SwapValue(S.align);
  SwapValue(S.reloff);
  SwapValue(S.nreloc);
  SwapValue(S.flags);
  SwapValue(S.reserved1);
  SwapValue(S.reserved2);
}

template<>
void SwapStruct(MachO::section_64 &S) {
  SwapValue(S.addr);
  SwapValue(S.size);
  SwapValue(S.offset);
  SwapValue(S.align);
  SwapValue(S.reloff);
  SwapValue(S.nreloc);
  SwapValue(S.flags);
  SwapValue(S.reserved1);
  SwapValue(S.reserved2);
  SwapValue(S.reserved3);
}

template<>
void SwapStruct(MachO::nlist &S) {
  SwapValue(S.n_strx);
  SwapValue(S.n_desc);
  SwapValue(S.n_value);
}

template<>
void SwapStruct(MachO::nlist_64 &S) {
  SwapValue(S.n_strx);
  SwapValue(S.n_desc);
  SwapValue(S.n_value);
}

template<>
void SwapStruct(MachO::mach_header &H) {
  SwapValue(H.magic);
  SwapValue(H.cputype);
  SwapValue(H.cpusubtype);
  SwapValue(H.filetype);
  SwapValue(H.ncmds);
  SwapValue(H.sizeofcmds);
  SwapValue(H.flags);
}

template<>
void SwapStruct(MachO::mach_header_64 &H) {
  SwapValue(H.magic);
  SwapValue(H.cputype);
  SwapValue(H.cpusubtype);
  SwapValue(H.filetype);
  SwapValue(H.ncmds);
  SwapValue(H.sizeofcmds);
  SwapValue(H.flags);
  SwapValue(H.reserved);
}

template<>
void SwapStruct(MachO::symtab_command &C) {
  SwapValue(C.cmd);
  SwapValue(C.cmdsize);
  SwapValue(C.symoff);
  SwapValue(C.nsyms);
  SwapValue(C.stroff);
  SwapValue(C.strsize);
}

template<>
void SwapStruct(MachO::dysymtab_command &C) {
  SwapValue(C.cmd);
  SwapValue(C.cmdsize);
  SwapValue(C.ilocalsym);
  SwapValue(C.nlocalsym);
  SwapValue(C.iextdefsym);
  SwapValue(C.nextdefsym);
  SwapValue(C.iundefsym);
  SwapValue(C.nundefsym);
  SwapValue(C.tocoff);
  SwapValue(C.ntoc);
  SwapValue(C.modtaboff);
  SwapValue(C.nmodtab);
  SwapValue(C.extrefsymoff);
  SwapValue(C.nextrefsyms);
  SwapValue(C.indirectsymoff);
  SwapValue(C.nindirectsyms);
  SwapValue(C.extreloff);
  SwapValue(C.nextrel);
  SwapValue(C.locreloff);
  SwapValue(C.nlocrel);
}

template<>
void SwapStruct(MachO::linkedit_data_command &C) {
  SwapValue(C.cmd);
  SwapValue(C.cmdsize);
  SwapValue(C.dataoff);
  SwapValue(C.datasize);
}

template<>
void SwapStruct(MachO::segment_command &C) {
  SwapValue(C.cmd);
  SwapValue(C.cmdsize);
  SwapValue(C.vmaddr);
  SwapValue(C.vmsize);
  SwapValue(C.fileoff);
  SwapValue(C.filesize);
  SwapValue(C.maxprot);
  SwapValue(C.initprot);
  SwapValue(C.nsects);
  SwapValue(C.flags);
}

template<>
void SwapStruct(MachO::segment_command_64 &C) {
  SwapValue(C.cmd);
  SwapValue(C.cmdsize);
  SwapValue(C.vmaddr);
  SwapValue(C.vmsize);
  SwapValue(C.fileoff);
  SwapValue(C.filesize);
  SwapValue(C.maxprot);
  SwapValue(C.initprot);
  SwapValue(C.nsects);
  SwapValue(C.flags);
}

template<>
void SwapStruct(uint32_t &C) {
  SwapValue(C);
}

template<>
void SwapStruct(MachO::linker_options_command &C) {
  SwapValue(C.cmd);
  SwapValue(C.cmdsize);
  SwapValue(C.count);
}

template<>
void SwapStruct(MachO::version_min_command&C) {
  SwapValue(C.cmd);
  SwapValue(C.cmdsize);
  SwapValue(C.version);
  SwapValue(C.reserved);
}

template<>
void SwapStruct(MachO::data_in_code_entry &C) {
  SwapValue(C.offset);
  SwapValue(C.length);
  SwapValue(C.kind);
}

template<typename T>
T getStruct(const MachOObjectFile *O, const char *P) {
  T Cmd;
  memcpy(&Cmd, P, sizeof(T));
  if (O->isLittleEndian() != sys::IsLittleEndianHost)
    SwapStruct(Cmd);
  return Cmd;
}

static uint32_t
getSegmentLoadCommandNumSections(const MachOObjectFile *O,
                                 const MachOObjectFile::LoadCommandInfo &L) {
  if (O->is64Bit()) {
    MachO::segment_command_64 S = O->getSegment64LoadCommand(L);
    return S.nsects;
  }
  MachO::segment_command S = O->getSegmentLoadCommand(L);
  return S.nsects;
}

static const char *
getSectionPtr(const MachOObjectFile *O, MachOObjectFile::LoadCommandInfo L,
              unsigned Sec) {
  uintptr_t CommandAddr = reinterpret_cast<uintptr_t>(L.Ptr);

  bool Is64 = O->is64Bit();
  unsigned SegmentLoadSize = Is64 ? sizeof(MachO::segment_command_64) :
                                    sizeof(MachO::segment_command);
  unsigned SectionSize = Is64 ? sizeof(MachO::section_64) :
                                sizeof(MachO::section);

  uintptr_t SectionAddr = CommandAddr + SegmentLoadSize + Sec * SectionSize;
  return reinterpret_cast<const char*>(SectionAddr);
}

static const char *getPtr(const MachOObjectFile *O, size_t Offset) {
  return O->getData().substr(Offset, 1).data();
}

static nlist_base
getSymbolTableEntryBase(const MachOObjectFile *O, DataRefImpl DRI) {
  const char *P = reinterpret_cast<const char *>(DRI.p);
  return getStruct<nlist_base>(O, P);
}

static StringRef parseSegmentOrSectionName(const char *P) {
  if (P[15] == 0)
    // Null terminated.
    return P;
  // Not null terminated, so this is a 16 char string.
  return StringRef(P, 16);
}

// Helper to advance a section or symbol iterator multiple increments at a time.
template<class T>
static void advance(T &it, size_t Val) {
  while (Val--)
    ++it;
}

static unsigned getCPUType(const MachOObjectFile *O) {
  return O->getHeader().cputype;
}

static void printRelocationTargetName(const MachOObjectFile *O,
                                      const MachO::any_relocation_info &RE,
                                      raw_string_ostream &fmt) {
  bool IsScattered = O->isRelocationScattered(RE);

  // Target of a scattered relocation is an address.  In the interest of
  // generating pretty output, scan through the symbol table looking for a
  // symbol that aligns with that address.  If we find one, print it.
  // Otherwise, we just print the hex address of the target.
  if (IsScattered) {
    uint32_t Val = O->getPlainRelocationSymbolNum(RE);

    for (const SymbolRef &Symbol : O->symbols()) {
      error_code ec;
      uint64_t Addr;
      StringRef Name;

      if ((ec = Symbol.getAddress(Addr)))
        report_fatal_error(ec.message());
      if (Addr != Val)
        continue;
      if ((ec = Symbol.getName(Name)))
        report_fatal_error(ec.message());
      fmt << Name;
      return;
    }

    // If we couldn't find a symbol that this relocation refers to, try
    // to find a section beginning instead.
    for (const SectionRef &Section : O->sections()) {
      error_code ec;
      uint64_t Addr;
      StringRef Name;

      if ((ec = Section.getAddress(Addr)))
        report_fatal_error(ec.message());
      if (Addr != Val)
        continue;
      if ((ec = Section.getName(Name)))
        report_fatal_error(ec.message());
      fmt << Name;
      return;
    }

    fmt << format("0x%x", Val);
    return;
  }

  StringRef S;
  bool isExtern = O->getPlainRelocationExternal(RE);
  uint64_t Val = O->getPlainRelocationSymbolNum(RE);

  if (isExtern) {
    symbol_iterator SI = O->symbol_begin();
    advance(SI, Val);
    SI->getName(S);
  } else {
    section_iterator SI = O->section_begin();
    // Adjust for the fact that sections are 1-indexed.
    advance(SI, Val - 1);
    SI->getName(S);
  }

  fmt << S;
}

static uint32_t
getPlainRelocationAddress(const MachO::any_relocation_info &RE) {
  return RE.r_word0;
}

static unsigned
getScatteredRelocationAddress(const MachO::any_relocation_info &RE) {
  return RE.r_word0 & 0xffffff;
}

static bool getPlainRelocationPCRel(const MachOObjectFile *O,
                                    const MachO::any_relocation_info &RE) {
  if (O->isLittleEndian())
    return (RE.r_word1 >> 24) & 1;
  return (RE.r_word1 >> 7) & 1;
}

static bool
getScatteredRelocationPCRel(const MachOObjectFile *O,
                            const MachO::any_relocation_info &RE) {
  return (RE.r_word0 >> 30) & 1;
}

static unsigned getPlainRelocationLength(const MachOObjectFile *O,
                                         const MachO::any_relocation_info &RE) {
  if (O->isLittleEndian())
    return (RE.r_word1 >> 25) & 3;
  return (RE.r_word1 >> 5) & 3;
}

static unsigned
getScatteredRelocationLength(const MachO::any_relocation_info &RE) {
  return (RE.r_word0 >> 28) & 3;
}

static unsigned getPlainRelocationType(const MachOObjectFile *O,
                                       const MachO::any_relocation_info &RE) {
  if (O->isLittleEndian())
    return RE.r_word1 >> 28;
  return RE.r_word1 & 0xf;
}

static unsigned
getScatteredRelocationType(const MachO::any_relocation_info &RE) {
  return (RE.r_word0 >> 24) & 0xf;
}

static uint32_t getSectionFlags(const MachOObjectFile *O,
                                DataRefImpl Sec) {
  if (O->is64Bit()) {
    MachO::section_64 Sect = O->getSection64(Sec);
    return Sect.flags;
  }
  MachO::section Sect = O->getSection(Sec);
  return Sect.flags;
}

MachOObjectFile::MachOObjectFile(MemoryBuffer *Object, bool IsLittleEndian,
                                 bool Is64bits, error_code &EC,
                                 bool BufferOwned)
    : ObjectFile(getMachOType(IsLittleEndian, Is64bits), Object, BufferOwned),
      SymtabLoadCmd(nullptr), DysymtabLoadCmd(nullptr),
      DataInCodeLoadCmd(nullptr) {
  uint32_t LoadCommandCount = this->getHeader().ncmds;
  MachO::LoadCommandType SegmentLoadType = is64Bit() ?
    MachO::LC_SEGMENT_64 : MachO::LC_SEGMENT;

  MachOObjectFile::LoadCommandInfo Load = getFirstLoadCommandInfo();
  for (unsigned I = 0; ; ++I) {
    if (Load.C.cmd == MachO::LC_SYMTAB) {
      assert(!SymtabLoadCmd && "Multiple symbol tables");
      SymtabLoadCmd = Load.Ptr;
    } else if (Load.C.cmd == MachO::LC_DYSYMTAB) {
      assert(!DysymtabLoadCmd && "Multiple dynamic symbol tables");
      DysymtabLoadCmd = Load.Ptr;
    } else if (Load.C.cmd == MachO::LC_DATA_IN_CODE) {
      assert(!DataInCodeLoadCmd && "Multiple data in code tables");
      DataInCodeLoadCmd = Load.Ptr;
    } else if (Load.C.cmd == SegmentLoadType) {
      uint32_t NumSections = getSegmentLoadCommandNumSections(this, Load);
      for (unsigned J = 0; J < NumSections; ++J) {
        const char *Sec = getSectionPtr(this, Load, J);
        Sections.push_back(Sec);
      }
    }

    if (I == LoadCommandCount - 1)
      break;
    else
      Load = getNextLoadCommandInfo(Load);
  }
}

void MachOObjectFile::moveSymbolNext(DataRefImpl &Symb) const {
  unsigned SymbolTableEntrySize = is64Bit() ?
    sizeof(MachO::nlist_64) :
    sizeof(MachO::nlist);
  Symb.p += SymbolTableEntrySize;
}

error_code MachOObjectFile::getSymbolName(DataRefImpl Symb,
                                          StringRef &Res) const {
  StringRef StringTable = getStringTableData();
  nlist_base Entry = getSymbolTableEntryBase(this, Symb);
  const char *Start = &StringTable.data()[Entry.n_strx];
  Res = StringRef(Start);
  return object_error::success;
}

error_code MachOObjectFile::getSymbolAddress(DataRefImpl Symb,
                                             uint64_t &Res) const {
  if (is64Bit()) {
    MachO::nlist_64 Entry = getSymbol64TableEntry(Symb);
    Res = Entry.n_value;
  } else {
    MachO::nlist Entry = getSymbolTableEntry(Symb);
    Res = Entry.n_value;
  }
  return object_error::success;
}

error_code MachOObjectFile::getSymbolAlignment(DataRefImpl DRI,
                                               uint32_t &Result) const {
  uint32_t flags = getSymbolFlags(DRI);
  if (flags & SymbolRef::SF_Common) {
    nlist_base Entry = getSymbolTableEntryBase(this, DRI);
    Result = 1 << MachO::GET_COMM_ALIGN(Entry.n_desc);
  } else {
    Result = 0;
  }
  return object_error::success;
}

error_code MachOObjectFile::getSymbolSize(DataRefImpl DRI,
                                          uint64_t &Result) const {
  uint64_t BeginOffset;
  uint64_t EndOffset = 0;
  uint8_t SectionIndex;

  nlist_base Entry = getSymbolTableEntryBase(this, DRI);
  uint64_t Value;
  getSymbolAddress(DRI, Value);

  BeginOffset = Value;

  SectionIndex = Entry.n_sect;
  if (!SectionIndex) {
    uint32_t flags = getSymbolFlags(DRI);
    if (flags & SymbolRef::SF_Common)
      Result = Value;
    else
      Result = UnknownAddressOrSize;
    return object_error::success;
  }
  // Unfortunately symbols are unsorted so we need to touch all
  // symbols from load command
  for (const SymbolRef &Symbol : symbols()) {
    DataRefImpl DRI = Symbol.getRawDataRefImpl();
    Entry = getSymbolTableEntryBase(this, DRI);
    getSymbolAddress(DRI, Value);
    if (Entry.n_sect == SectionIndex && Value > BeginOffset)
      if (!EndOffset || Value < EndOffset)
        EndOffset = Value;
  }
  if (!EndOffset) {
    uint64_t Size;
    DataRefImpl Sec;
    Sec.d.a = SectionIndex-1;
    getSectionSize(Sec, Size);
    getSectionAddress(Sec, EndOffset);
    EndOffset += Size;
  }
  Result = EndOffset - BeginOffset;
  return object_error::success;
}

error_code MachOObjectFile::getSymbolType(DataRefImpl Symb,
                                          SymbolRef::Type &Res) const {
  nlist_base Entry = getSymbolTableEntryBase(this, Symb);
  uint8_t n_type = Entry.n_type;

  Res = SymbolRef::ST_Other;

  // If this is a STAB debugging symbol, we can do nothing more.
  if (n_type & MachO::N_STAB) {
    Res = SymbolRef::ST_Debug;
    return object_error::success;
  }

  switch (n_type & MachO::N_TYPE) {
    case MachO::N_UNDF :
      Res = SymbolRef::ST_Unknown;
      break;
    case MachO::N_SECT :
      Res = SymbolRef::ST_Function;
      break;
  }
  return object_error::success;
}

uint32_t MachOObjectFile::getSymbolFlags(DataRefImpl DRI) const {
  nlist_base Entry = getSymbolTableEntryBase(this, DRI);

  uint8_t MachOType = Entry.n_type;
  uint16_t MachOFlags = Entry.n_desc;

  uint32_t Result = SymbolRef::SF_None;

  if ((MachOType & MachO::N_TYPE) == MachO::N_UNDF)
    Result |= SymbolRef::SF_Undefined;

  if (MachOType & MachO::N_STAB)
    Result |= SymbolRef::SF_FormatSpecific;

  if (MachOType & MachO::N_EXT) {
    Result |= SymbolRef::SF_Global;
    if ((MachOType & MachO::N_TYPE) == MachO::N_UNDF) {
      uint64_t Value;
      getSymbolAddress(DRI, Value);
      if (Value)
        Result |= SymbolRef::SF_Common;
    }
  }

  if (MachOFlags & (MachO::N_WEAK_REF | MachO::N_WEAK_DEF))
    Result |= SymbolRef::SF_Weak;

  if ((MachOType & MachO::N_TYPE) == MachO::N_ABS)
    Result |= SymbolRef::SF_Absolute;

  return Result;
}

error_code
MachOObjectFile::getSymbolSection(DataRefImpl Symb,
                                  section_iterator &Res) const {
  nlist_base Entry = getSymbolTableEntryBase(this, Symb);
  uint8_t index = Entry.n_sect;

  if (index == 0) {
    Res = section_end();
  } else {
    DataRefImpl DRI;
    DRI.d.a = index - 1;
    Res = section_iterator(SectionRef(DRI, this));
  }

  return object_error::success;
}

void MachOObjectFile::moveSectionNext(DataRefImpl &Sec) const {
  Sec.d.a++;
}

error_code
MachOObjectFile::getSectionName(DataRefImpl Sec, StringRef &Result) const {
  ArrayRef<char> Raw = getSectionRawName(Sec);
  Result = parseSegmentOrSectionName(Raw.data());
  return object_error::success;
}

error_code
MachOObjectFile::getSectionAddress(DataRefImpl Sec, uint64_t &Res) const {
  if (is64Bit()) {
    MachO::section_64 Sect = getSection64(Sec);
    Res = Sect.addr;
  } else {
    MachO::section Sect = getSection(Sec);
    Res = Sect.addr;
  }
  return object_error::success;
}

error_code
MachOObjectFile::getSectionSize(DataRefImpl Sec, uint64_t &Res) const {
  if (is64Bit()) {
    MachO::section_64 Sect = getSection64(Sec);
    Res = Sect.size;
  } else {
    MachO::section Sect = getSection(Sec);
    Res = Sect.size;
  }

  return object_error::success;
}

error_code
MachOObjectFile::getSectionContents(DataRefImpl Sec, StringRef &Res) const {
  uint32_t Offset;
  uint64_t Size;

  if (is64Bit()) {
    MachO::section_64 Sect = getSection64(Sec);
    Offset = Sect.offset;
    Size = Sect.size;
  } else {
    MachO::section Sect = getSection(Sec);
    Offset = Sect.offset;
    Size = Sect.size;
  }

  Res = this->getData().substr(Offset, Size);
  return object_error::success;
}

error_code
MachOObjectFile::getSectionAlignment(DataRefImpl Sec, uint64_t &Res) const {
  uint32_t Align;
  if (is64Bit()) {
    MachO::section_64 Sect = getSection64(Sec);
    Align = Sect.align;
  } else {
    MachO::section Sect = getSection(Sec);
    Align = Sect.align;
  }

  Res = uint64_t(1) << Align;
  return object_error::success;
}

error_code
MachOObjectFile::isSectionText(DataRefImpl Sec, bool &Res) const {
  uint32_t Flags = getSectionFlags(this, Sec);
  Res = Flags & MachO::S_ATTR_PURE_INSTRUCTIONS;
  return object_error::success;
}

error_code MachOObjectFile::isSectionData(DataRefImpl Sec, bool &Result) const {
  uint32_t Flags = getSectionFlags(this, Sec);
  unsigned SectionType = Flags & MachO::SECTION_TYPE;
  Result = !(Flags & MachO::S_ATTR_PURE_INSTRUCTIONS) &&
           !(SectionType == MachO::S_ZEROFILL ||
             SectionType == MachO::S_GB_ZEROFILL);
  return object_error::success;
}

error_code MachOObjectFile::isSectionBSS(DataRefImpl Sec, bool &Result) const {
  uint32_t Flags = getSectionFlags(this, Sec);
  unsigned SectionType = Flags & MachO::SECTION_TYPE;
  Result = !(Flags & MachO::S_ATTR_PURE_INSTRUCTIONS) &&
           (SectionType == MachO::S_ZEROFILL ||
            SectionType == MachO::S_GB_ZEROFILL);
  return object_error::success;
}

error_code
MachOObjectFile::isSectionRequiredForExecution(DataRefImpl Sec,
                                               bool &Result) const {
  // FIXME: Unimplemented.
  Result = true;
  return object_error::success;
}

error_code MachOObjectFile::isSectionVirtual(DataRefImpl Sec,
                                             bool &Result) const {
  // FIXME: Unimplemented.
  Result = false;
  return object_error::success;
}

error_code
MachOObjectFile::isSectionZeroInit(DataRefImpl Sec, bool &Res) const {
  uint32_t Flags = getSectionFlags(this, Sec);
  unsigned SectionType = Flags & MachO::SECTION_TYPE;
  Res = SectionType == MachO::S_ZEROFILL ||
    SectionType == MachO::S_GB_ZEROFILL;
  return object_error::success;
}

error_code MachOObjectFile::isSectionReadOnlyData(DataRefImpl Sec,
                                                  bool &Result) const {
  // Consider using the code from isSectionText to look for __const sections.
  // Alternately, emit S_ATTR_PURE_INSTRUCTIONS and/or S_ATTR_SOME_INSTRUCTIONS
  // to use section attributes to distinguish code from data.

  // FIXME: Unimplemented.
  Result = false;
  return object_error::success;
}

error_code
MachOObjectFile::sectionContainsSymbol(DataRefImpl Sec, DataRefImpl Symb,
                                       bool &Result) const {
  SymbolRef::Type ST;
  this->getSymbolType(Symb, ST);
  if (ST == SymbolRef::ST_Unknown) {
    Result = false;
    return object_error::success;
  }

  uint64_t SectBegin, SectEnd;
  getSectionAddress(Sec, SectBegin);
  getSectionSize(Sec, SectEnd);
  SectEnd += SectBegin;

  uint64_t SymAddr;
  getSymbolAddress(Symb, SymAddr);
  Result = (SymAddr >= SectBegin) && (SymAddr < SectEnd);

  return object_error::success;
}

relocation_iterator MachOObjectFile::section_rel_begin(DataRefImpl Sec) const {
  DataRefImpl Ret;
  Ret.d.a = Sec.d.a;
  Ret.d.b = 0;
  return relocation_iterator(RelocationRef(Ret, this));
}

relocation_iterator
MachOObjectFile::section_rel_end(DataRefImpl Sec) const {
  uint32_t Num;
  if (is64Bit()) {
    MachO::section_64 Sect = getSection64(Sec);
    Num = Sect.nreloc;
  } else {
    MachO::section Sect = getSection(Sec);
    Num = Sect.nreloc;
  }

  DataRefImpl Ret;
  Ret.d.a = Sec.d.a;
  Ret.d.b = Num;
  return relocation_iterator(RelocationRef(Ret, this));
}

void MachOObjectFile::moveRelocationNext(DataRefImpl &Rel) const {
  ++Rel.d.b;
}

error_code
MachOObjectFile::getRelocationAddress(DataRefImpl Rel, uint64_t &Res) const {
  uint64_t Offset;
  getRelocationOffset(Rel, Offset);

  DataRefImpl Sec;
  Sec.d.a = Rel.d.a;
  uint64_t SecAddress;
  getSectionAddress(Sec, SecAddress);
  Res = SecAddress + Offset;
  return object_error::success;
}

error_code MachOObjectFile::getRelocationOffset(DataRefImpl Rel,
                                                uint64_t &Res) const {
  assert(getHeader().filetype == MachO::MH_OBJECT &&
         "Only implemented for MH_OBJECT");
  MachO::any_relocation_info RE = getRelocation(Rel);
  Res = getAnyRelocationAddress(RE);
  return object_error::success;
}

symbol_iterator
MachOObjectFile::getRelocationSymbol(DataRefImpl Rel) const {
  MachO::any_relocation_info RE = getRelocation(Rel);
  uint32_t SymbolIdx = getPlainRelocationSymbolNum(RE);
  bool isExtern = getPlainRelocationExternal(RE);
  if (!isExtern)
    return symbol_end();

  MachO::symtab_command S = getSymtabLoadCommand();
  unsigned SymbolTableEntrySize = is64Bit() ?
    sizeof(MachO::nlist_64) :
    sizeof(MachO::nlist);
  uint64_t Offset = S.symoff + SymbolIdx * SymbolTableEntrySize;
  DataRefImpl Sym;
  Sym.p = reinterpret_cast<uintptr_t>(getPtr(this, Offset));
  return symbol_iterator(SymbolRef(Sym, this));
}

error_code MachOObjectFile::getRelocationType(DataRefImpl Rel,
                                              uint64_t &Res) const {
  MachO::any_relocation_info RE = getRelocation(Rel);
  Res = getAnyRelocationType(RE);
  return object_error::success;
}

error_code
MachOObjectFile::getRelocationTypeName(DataRefImpl Rel,
                                       SmallVectorImpl<char> &Result) const {
  StringRef res;
  uint64_t RType;
  getRelocationType(Rel, RType);

  unsigned Arch = this->getArch();

  switch (Arch) {
    case Triple::x86: {
      static const char *const Table[] =  {
        "GENERIC_RELOC_VANILLA",
        "GENERIC_RELOC_PAIR",
        "GENERIC_RELOC_SECTDIFF",
        "GENERIC_RELOC_PB_LA_PTR",
        "GENERIC_RELOC_LOCAL_SECTDIFF",
        "GENERIC_RELOC_TLV" };

      if (RType > 5)
        res = "Unknown";
      else
        res = Table[RType];
      break;
    }
    case Triple::x86_64: {
      static const char *const Table[] =  {
        "X86_64_RELOC_UNSIGNED",
        "X86_64_RELOC_SIGNED",
        "X86_64_RELOC_BRANCH",
        "X86_64_RELOC_GOT_LOAD",
        "X86_64_RELOC_GOT",
        "X86_64_RELOC_SUBTRACTOR",
        "X86_64_RELOC_SIGNED_1",
        "X86_64_RELOC_SIGNED_2",
        "X86_64_RELOC_SIGNED_4",
        "X86_64_RELOC_TLV" };

      if (RType > 9)
        res = "Unknown";
      else
        res = Table[RType];
      break;
    }
    case Triple::arm: {
      static const char *const Table[] =  {
        "ARM_RELOC_VANILLA",
        "ARM_RELOC_PAIR",
        "ARM_RELOC_SECTDIFF",
        "ARM_RELOC_LOCAL_SECTDIFF",
        "ARM_RELOC_PB_LA_PTR",
        "ARM_RELOC_BR24",
        "ARM_THUMB_RELOC_BR22",
        "ARM_THUMB_32BIT_BRANCH",
        "ARM_RELOC_HALF",
        "ARM_RELOC_HALF_SECTDIFF" };

      if (RType > 9)
        res = "Unknown";
      else
        res = Table[RType];
      break;
    }
    case Triple::arm64:
    case Triple::aarch64: {
      static const char *const Table[] = {
        "ARM64_RELOC_UNSIGNED",           "ARM64_RELOC_SUBTRACTOR",
        "ARM64_RELOC_BRANCH26",           "ARM64_RELOC_PAGE21",
        "ARM64_RELOC_PAGEOFF12",          "ARM64_RELOC_GOT_LOAD_PAGE21",
        "ARM64_RELOC_GOT_LOAD_PAGEOFF12", "ARM64_RELOC_POINTER_TO_GOT",
        "ARM64_RELOC_TLVP_LOAD_PAGE21",   "ARM64_RELOC_TLVP_LOAD_PAGEOFF12",
        "ARM64_RELOC_ADDEND"
      };

      if (RType >= array_lengthof(Table))
        res = "Unknown";
      else
        res = Table[RType];
      break;
    }
    case Triple::ppc: {
      static const char *const Table[] =  {
        "PPC_RELOC_VANILLA",
        "PPC_RELOC_PAIR",
        "PPC_RELOC_BR14",
        "PPC_RELOC_BR24",
        "PPC_RELOC_HI16",
        "PPC_RELOC_LO16",
        "PPC_RELOC_HA16",
        "PPC_RELOC_LO14",
        "PPC_RELOC_SECTDIFF",
        "PPC_RELOC_PB_LA_PTR",
        "PPC_RELOC_HI16_SECTDIFF",
        "PPC_RELOC_LO16_SECTDIFF",
        "PPC_RELOC_HA16_SECTDIFF",
        "PPC_RELOC_JBSR",
        "PPC_RELOC_LO14_SECTDIFF",
        "PPC_RELOC_LOCAL_SECTDIFF" };

      if (RType > 15)
        res = "Unknown";
      else
        res = Table[RType];
      break;
    }
    case Triple::UnknownArch:
      res = "Unknown";
      break;
  }
  Result.append(res.begin(), res.end());
  return object_error::success;
}

error_code
MachOObjectFile::getRelocationValueString(DataRefImpl Rel,
                                          SmallVectorImpl<char> &Result) const {
  MachO::any_relocation_info RE = getRelocation(Rel);

  unsigned Arch = this->getArch();

  std::string fmtbuf;
  raw_string_ostream fmt(fmtbuf);
  unsigned Type = this->getAnyRelocationType(RE);
  bool IsPCRel = this->getAnyRelocationPCRel(RE);

  // Determine any addends that should be displayed with the relocation.
  // These require decoding the relocation type, which is triple-specific.

  // X86_64 has entirely custom relocation types.
  if (Arch == Triple::x86_64) {
    bool isPCRel = getAnyRelocationPCRel(RE);

    switch (Type) {
      case MachO::X86_64_RELOC_GOT_LOAD:
      case MachO::X86_64_RELOC_GOT: {
        printRelocationTargetName(this, RE, fmt);
        fmt << "@GOT";
        if (isPCRel) fmt << "PCREL";
        break;
      }
      case MachO::X86_64_RELOC_SUBTRACTOR: {
        DataRefImpl RelNext = Rel;
        moveRelocationNext(RelNext);
        MachO::any_relocation_info RENext = getRelocation(RelNext);

        // X86_64_RELOC_SUBTRACTOR must be followed by a relocation of type
        // X86_64_RELOC_UNSIGNED.
        // NOTE: Scattered relocations don't exist on x86_64.
        unsigned RType = getAnyRelocationType(RENext);
        if (RType != MachO::X86_64_RELOC_UNSIGNED)
          report_fatal_error("Expected X86_64_RELOC_UNSIGNED after "
                             "X86_64_RELOC_SUBTRACTOR.");

        // The X86_64_RELOC_UNSIGNED contains the minuend symbol;
        // X86_64_RELOC_SUBTRACTOR contains the subtrahend.
        printRelocationTargetName(this, RENext, fmt);
        fmt << "-";
        printRelocationTargetName(this, RE, fmt);
        break;
      }
      case MachO::X86_64_RELOC_TLV:
        printRelocationTargetName(this, RE, fmt);
        fmt << "@TLV";
        if (isPCRel) fmt << "P";
        break;
      case MachO::X86_64_RELOC_SIGNED_1:
        printRelocationTargetName(this, RE, fmt);
        fmt << "-1";
        break;
      case MachO::X86_64_RELOC_SIGNED_2:
        printRelocationTargetName(this, RE, fmt);
        fmt << "-2";
        break;
      case MachO::X86_64_RELOC_SIGNED_4:
        printRelocationTargetName(this, RE, fmt);
        fmt << "-4";
        break;
      default:
        printRelocationTargetName(this, RE, fmt);
        break;
    }
  // X86 and ARM share some relocation types in common.
  } else if (Arch == Triple::x86 || Arch == Triple::arm ||
             Arch == Triple::ppc) {
    // Generic relocation types...
    switch (Type) {
      case MachO::GENERIC_RELOC_PAIR: // prints no info
        return object_error::success;
      case MachO::GENERIC_RELOC_SECTDIFF: {
        DataRefImpl RelNext = Rel;
        moveRelocationNext(RelNext);
        MachO::any_relocation_info RENext = getRelocation(RelNext);

        // X86 sect diff's must be followed by a relocation of type
        // GENERIC_RELOC_PAIR.
        unsigned RType = getAnyRelocationType(RENext);

        if (RType != MachO::GENERIC_RELOC_PAIR)
          report_fatal_error("Expected GENERIC_RELOC_PAIR after "
                             "GENERIC_RELOC_SECTDIFF.");

        printRelocationTargetName(this, RE, fmt);
        fmt << "-";
        printRelocationTargetName(this, RENext, fmt);
        break;
      }
    }

    if (Arch == Triple::x86 || Arch == Triple::ppc) {
      switch (Type) {
        case MachO::GENERIC_RELOC_LOCAL_SECTDIFF: {
          DataRefImpl RelNext = Rel;
          moveRelocationNext(RelNext);
          MachO::any_relocation_info RENext = getRelocation(RelNext);

          // X86 sect diff's must be followed by a relocation of type
          // GENERIC_RELOC_PAIR.
          unsigned RType = getAnyRelocationType(RENext);
          if (RType != MachO::GENERIC_RELOC_PAIR)
            report_fatal_error("Expected GENERIC_RELOC_PAIR after "
                               "GENERIC_RELOC_LOCAL_SECTDIFF.");

          printRelocationTargetName(this, RE, fmt);
          fmt << "-";
          printRelocationTargetName(this, RENext, fmt);
          break;
        }
        case MachO::GENERIC_RELOC_TLV: {
          printRelocationTargetName(this, RE, fmt);
          fmt << "@TLV";
          if (IsPCRel) fmt << "P";
          break;
        }
        default:
          printRelocationTargetName(this, RE, fmt);
      }
    } else { // ARM-specific relocations
      switch (Type) {
        case MachO::ARM_RELOC_HALF:
        case MachO::ARM_RELOC_HALF_SECTDIFF: {
          // Half relocations steal a bit from the length field to encode
          // whether this is an upper16 or a lower16 relocation.
          bool isUpper = getAnyRelocationLength(RE) >> 1;

          if (isUpper)
            fmt << ":upper16:(";
          else
            fmt << ":lower16:(";
          printRelocationTargetName(this, RE, fmt);

          DataRefImpl RelNext = Rel;
          moveRelocationNext(RelNext);
          MachO::any_relocation_info RENext = getRelocation(RelNext);

          // ARM half relocs must be followed by a relocation of type
          // ARM_RELOC_PAIR.
          unsigned RType = getAnyRelocationType(RENext);
          if (RType != MachO::ARM_RELOC_PAIR)
            report_fatal_error("Expected ARM_RELOC_PAIR after "
                               "ARM_RELOC_HALF");

          // NOTE: The half of the target virtual address is stashed in the
          // address field of the secondary relocation, but we can't reverse
          // engineer the constant offset from it without decoding the movw/movt
          // instruction to find the other half in its immediate field.

          // ARM_RELOC_HALF_SECTDIFF encodes the second section in the
          // symbol/section pointer of the follow-on relocation.
          if (Type == MachO::ARM_RELOC_HALF_SECTDIFF) {
            fmt << "-";
            printRelocationTargetName(this, RENext, fmt);
          }

          fmt << ")";
          break;
        }
        default: {
          printRelocationTargetName(this, RE, fmt);
        }
      }
    }
  } else
    printRelocationTargetName(this, RE, fmt);

  fmt.flush();
  Result.append(fmtbuf.begin(), fmtbuf.end());
  return object_error::success;
}

error_code
MachOObjectFile::getRelocationHidden(DataRefImpl Rel, bool &Result) const {
  unsigned Arch = getArch();
  uint64_t Type;
  getRelocationType(Rel, Type);

  Result = false;

  // On arches that use the generic relocations, GENERIC_RELOC_PAIR
  // is always hidden.
  if (Arch == Triple::x86 || Arch == Triple::arm || Arch == Triple::ppc) {
    if (Type == MachO::GENERIC_RELOC_PAIR) Result = true;
  } else if (Arch == Triple::x86_64) {
    // On x86_64, X86_64_RELOC_UNSIGNED is hidden only when it follows
    // an X86_64_RELOC_SUBTRACTOR.
    if (Type == MachO::X86_64_RELOC_UNSIGNED && Rel.d.a > 0) {
      DataRefImpl RelPrev = Rel;
      RelPrev.d.a--;
      uint64_t PrevType;
      getRelocationType(RelPrev, PrevType);
      if (PrevType == MachO::X86_64_RELOC_SUBTRACTOR)
        Result = true;
    }
  }

  return object_error::success;
}

error_code MachOObjectFile::getLibraryNext(DataRefImpl LibData,
                                           LibraryRef &Res) const {
  report_fatal_error("Needed libraries unimplemented in MachOObjectFile");
}

error_code MachOObjectFile::getLibraryPath(DataRefImpl LibData,
                                           StringRef &Res) const {
  report_fatal_error("Needed libraries unimplemented in MachOObjectFile");
}

basic_symbol_iterator MachOObjectFile::symbol_begin_impl() const {
  return getSymbolByIndex(0);
}

basic_symbol_iterator MachOObjectFile::symbol_end_impl() const {
  DataRefImpl DRI;
  if (!SymtabLoadCmd)
    return basic_symbol_iterator(SymbolRef(DRI, this));

  MachO::symtab_command Symtab = getSymtabLoadCommand();
  unsigned SymbolTableEntrySize = is64Bit() ?
    sizeof(MachO::nlist_64) :
    sizeof(MachO::nlist);
  unsigned Offset = Symtab.symoff +
    Symtab.nsyms * SymbolTableEntrySize;
  DRI.p = reinterpret_cast<uintptr_t>(getPtr(this, Offset));
  return basic_symbol_iterator(SymbolRef(DRI, this));
}

basic_symbol_iterator MachOObjectFile::getSymbolByIndex(unsigned Index) const {
  DataRefImpl DRI;
  if (!SymtabLoadCmd)
    return basic_symbol_iterator(SymbolRef(DRI, this));

  MachO::symtab_command Symtab = getSymtabLoadCommand();
  assert(Index < Symtab.nsyms && "Requested symbol index is out of range.");
  unsigned SymbolTableEntrySize =
    is64Bit() ? sizeof(MachO::nlist_64) : sizeof(MachO::nlist);
  DRI.p = reinterpret_cast<uintptr_t>(getPtr(this, Symtab.symoff));
  DRI.p += Index * SymbolTableEntrySize;
  return basic_symbol_iterator(SymbolRef(DRI, this));
}

section_iterator MachOObjectFile::section_begin() const {
  DataRefImpl DRI;
  return section_iterator(SectionRef(DRI, this));
}

section_iterator MachOObjectFile::section_end() const {
  DataRefImpl DRI;
  DRI.d.a = Sections.size();
  return section_iterator(SectionRef(DRI, this));
}

library_iterator MachOObjectFile::needed_library_begin() const {
  // TODO: implement
  report_fatal_error("Needed libraries unimplemented in MachOObjectFile");
}

library_iterator MachOObjectFile::needed_library_end() const {
  // TODO: implement
  report_fatal_error("Needed libraries unimplemented in MachOObjectFile");
}

uint8_t MachOObjectFile::getBytesInAddress() const {
  return is64Bit() ? 8 : 4;
}

StringRef MachOObjectFile::getFileFormatName() const {
  unsigned CPUType = getCPUType(this);
  if (!is64Bit()) {
    switch (CPUType) {
    case llvm::MachO::CPU_TYPE_I386:
      return "Mach-O 32-bit i386";
    case llvm::MachO::CPU_TYPE_ARM:
      return "Mach-O arm";
    case llvm::MachO::CPU_TYPE_POWERPC:
      return "Mach-O 32-bit ppc";
    default:
      assert((CPUType & llvm::MachO::CPU_ARCH_ABI64) == 0 &&
             "64-bit object file when we're not 64-bit?");
      return "Mach-O 32-bit unknown";
    }
  }

  // Make sure the cpu type has the correct mask.
  assert((CPUType & llvm::MachO::CPU_ARCH_ABI64)
         == llvm::MachO::CPU_ARCH_ABI64 &&
         "32-bit object file when we're 64-bit?");

  switch (CPUType) {
  case llvm::MachO::CPU_TYPE_X86_64:
    return "Mach-O 64-bit x86-64";
  case llvm::MachO::CPU_TYPE_ARM64:
    return "Mach-O arm64";
  case llvm::MachO::CPU_TYPE_POWERPC64:
    return "Mach-O 64-bit ppc64";
  default:
    return "Mach-O 64-bit unknown";
  }
}

Triple::ArchType MachOObjectFile::getArch(uint32_t CPUType) {
  switch (CPUType) {
  case llvm::MachO::CPU_TYPE_I386:
    return Triple::x86;
  case llvm::MachO::CPU_TYPE_X86_64:
    return Triple::x86_64;
  case llvm::MachO::CPU_TYPE_ARM:
    return Triple::arm;
  case llvm::MachO::CPU_TYPE_ARM64:
    return Triple::arm64;
  case llvm::MachO::CPU_TYPE_POWERPC:
    return Triple::ppc;
  case llvm::MachO::CPU_TYPE_POWERPC64:
    return Triple::ppc64;
  default:
    return Triple::UnknownArch;
  }
}

unsigned MachOObjectFile::getArch() const {
  return getArch(getCPUType(this));
}

StringRef MachOObjectFile::getLoadName() const {
  // TODO: Implement
  report_fatal_error("get_load_name() unimplemented in MachOObjectFile");
}

relocation_iterator MachOObjectFile::section_rel_begin(unsigned Index) const {
  DataRefImpl DRI;
  DRI.d.a = Index;
  return section_rel_begin(DRI);
}

relocation_iterator MachOObjectFile::section_rel_end(unsigned Index) const {
  DataRefImpl DRI;
  DRI.d.a = Index;
  return section_rel_end(DRI);
}

dice_iterator MachOObjectFile::begin_dices() const {
  DataRefImpl DRI;
  if (!DataInCodeLoadCmd)
    return dice_iterator(DiceRef(DRI, this));

  MachO::linkedit_data_command DicLC = getDataInCodeLoadCommand();
  DRI.p = reinterpret_cast<uintptr_t>(getPtr(this, DicLC.dataoff));
  return dice_iterator(DiceRef(DRI, this));
}

dice_iterator MachOObjectFile::end_dices() const {
  DataRefImpl DRI;
  if (!DataInCodeLoadCmd)
    return dice_iterator(DiceRef(DRI, this));

  MachO::linkedit_data_command DicLC = getDataInCodeLoadCommand();
  unsigned Offset = DicLC.dataoff + DicLC.datasize;
  DRI.p = reinterpret_cast<uintptr_t>(getPtr(this, Offset));
  return dice_iterator(DiceRef(DRI, this));
}

StringRef
MachOObjectFile::getSectionFinalSegmentName(DataRefImpl Sec) const {
  ArrayRef<char> Raw = getSectionRawFinalSegmentName(Sec);
  return parseSegmentOrSectionName(Raw.data());
}

ArrayRef<char>
MachOObjectFile::getSectionRawName(DataRefImpl Sec) const {
  const section_base *Base =
    reinterpret_cast<const section_base *>(Sections[Sec.d.a]);
  return ArrayRef<char>(Base->sectname);
}

ArrayRef<char>
MachOObjectFile::getSectionRawFinalSegmentName(DataRefImpl Sec) const {
  const section_base *Base =
    reinterpret_cast<const section_base *>(Sections[Sec.d.a]);
  return ArrayRef<char>(Base->segname);
}

bool
MachOObjectFile::isRelocationScattered(const MachO::any_relocation_info &RE)
  const {
  if (getCPUType(this) == MachO::CPU_TYPE_X86_64)
    return false;
  return getPlainRelocationAddress(RE) & MachO::R_SCATTERED;
}

unsigned MachOObjectFile::getPlainRelocationSymbolNum(
    const MachO::any_relocation_info &RE) const {
  if (isLittleEndian())
    return RE.r_word1 & 0xffffff;
  return RE.r_word1 >> 8;
}

bool MachOObjectFile::getPlainRelocationExternal(
    const MachO::any_relocation_info &RE) const {
  if (isLittleEndian())
    return (RE.r_word1 >> 27) & 1;
  return (RE.r_word1 >> 4) & 1;
}

bool MachOObjectFile::getScatteredRelocationScattered(
    const MachO::any_relocation_info &RE) const {
  return RE.r_word0 >> 31;
}

uint32_t MachOObjectFile::getScatteredRelocationValue(
    const MachO::any_relocation_info &RE) const {
  return RE.r_word1;
}

unsigned MachOObjectFile::getAnyRelocationAddress(
    const MachO::any_relocation_info &RE) const {
  if (isRelocationScattered(RE))
    return getScatteredRelocationAddress(RE);
  return getPlainRelocationAddress(RE);
}

unsigned MachOObjectFile::getAnyRelocationPCRel(
    const MachO::any_relocation_info &RE) const {
  if (isRelocationScattered(RE))
    return getScatteredRelocationPCRel(this, RE);
  return getPlainRelocationPCRel(this, RE);
}

unsigned MachOObjectFile::getAnyRelocationLength(
    const MachO::any_relocation_info &RE) const {
  if (isRelocationScattered(RE))
    return getScatteredRelocationLength(RE);
  return getPlainRelocationLength(this, RE);
}

unsigned
MachOObjectFile::getAnyRelocationType(
                                   const MachO::any_relocation_info &RE) const {
  if (isRelocationScattered(RE))
    return getScatteredRelocationType(RE);
  return getPlainRelocationType(this, RE);
}

SectionRef
MachOObjectFile::getRelocationSection(
                                   const MachO::any_relocation_info &RE) const {
  if (isRelocationScattered(RE) || getPlainRelocationExternal(RE))
    return *section_end();
  unsigned SecNum = getPlainRelocationSymbolNum(RE) - 1;
  DataRefImpl DRI;
  DRI.d.a = SecNum;
  return SectionRef(DRI, this);
}

MachOObjectFile::LoadCommandInfo
MachOObjectFile::getFirstLoadCommandInfo() const {
  MachOObjectFile::LoadCommandInfo Load;

  unsigned HeaderSize = is64Bit() ? sizeof(MachO::mach_header_64) :
                                    sizeof(MachO::mach_header);
  Load.Ptr = getPtr(this, HeaderSize);
  Load.C = getStruct<MachO::load_command>(this, Load.Ptr);
  return Load;
}

MachOObjectFile::LoadCommandInfo
MachOObjectFile::getNextLoadCommandInfo(const LoadCommandInfo &L) const {
  MachOObjectFile::LoadCommandInfo Next;
  Next.Ptr = L.Ptr + L.C.cmdsize;
  Next.C = getStruct<MachO::load_command>(this, Next.Ptr);
  return Next;
}

MachO::section MachOObjectFile::getSection(DataRefImpl DRI) const {
  return getStruct<MachO::section>(this, Sections[DRI.d.a]);
}

MachO::section_64 MachOObjectFile::getSection64(DataRefImpl DRI) const {
  return getStruct<MachO::section_64>(this, Sections[DRI.d.a]);
}

MachO::section MachOObjectFile::getSection(const LoadCommandInfo &L,
                                           unsigned Index) const {
  const char *Sec = getSectionPtr(this, L, Index);
  return getStruct<MachO::section>(this, Sec);
}

MachO::section_64 MachOObjectFile::getSection64(const LoadCommandInfo &L,
                                                unsigned Index) const {
  const char *Sec = getSectionPtr(this, L, Index);
  return getStruct<MachO::section_64>(this, Sec);
}

MachO::nlist
MachOObjectFile::getSymbolTableEntry(DataRefImpl DRI) const {
  const char *P = reinterpret_cast<const char *>(DRI.p);
  return getStruct<MachO::nlist>(this, P);
}

MachO::nlist_64
MachOObjectFile::getSymbol64TableEntry(DataRefImpl DRI) const {
  const char *P = reinterpret_cast<const char *>(DRI.p);
  return getStruct<MachO::nlist_64>(this, P);
}

MachO::linkedit_data_command
MachOObjectFile::getLinkeditDataLoadCommand(const LoadCommandInfo &L) const {
  return getStruct<MachO::linkedit_data_command>(this, L.Ptr);
}

MachO::segment_command
MachOObjectFile::getSegmentLoadCommand(const LoadCommandInfo &L) const {
  return getStruct<MachO::segment_command>(this, L.Ptr);
}

MachO::segment_command_64
MachOObjectFile::getSegment64LoadCommand(const LoadCommandInfo &L) const {
  return getStruct<MachO::segment_command_64>(this, L.Ptr);
}

MachO::linker_options_command
MachOObjectFile::getLinkerOptionsLoadCommand(const LoadCommandInfo &L) const {
  return getStruct<MachO::linker_options_command>(this, L.Ptr);
}

MachO::version_min_command
MachOObjectFile::getVersionMinLoadCommand(const LoadCommandInfo &L) const {
  return getStruct<MachO::version_min_command>(this, L.Ptr);
}

MachO::any_relocation_info
MachOObjectFile::getRelocation(DataRefImpl Rel) const {
  DataRefImpl Sec;
  Sec.d.a = Rel.d.a;
  uint32_t Offset;
  if (is64Bit()) {
    MachO::section_64 Sect = getSection64(Sec);
    Offset = Sect.reloff;
  } else {
    MachO::section Sect = getSection(Sec);
    Offset = Sect.reloff;
  }

  auto P = reinterpret_cast<const MachO::any_relocation_info *>(
      getPtr(this, Offset)) + Rel.d.b;
  return getStruct<MachO::any_relocation_info>(
      this, reinterpret_cast<const char *>(P));
}

MachO::data_in_code_entry
MachOObjectFile::getDice(DataRefImpl Rel) const {
  const char *P = reinterpret_cast<const char *>(Rel.p);
  return getStruct<MachO::data_in_code_entry>(this, P);
}

MachO::mach_header MachOObjectFile::getHeader() const {
  return getStruct<MachO::mach_header>(this, getPtr(this, 0));
}

MachO::mach_header_64 MachOObjectFile::getHeader64() const {
  return getStruct<MachO::mach_header_64>(this, getPtr(this, 0));
}

uint32_t MachOObjectFile::getIndirectSymbolTableEntry(
                                             const MachO::dysymtab_command &DLC,
                                             unsigned Index) const {
  uint64_t Offset = DLC.indirectsymoff + Index * sizeof(uint32_t);
  return getStruct<uint32_t>(this, getPtr(this, Offset));
}

MachO::data_in_code_entry
MachOObjectFile::getDataInCodeTableEntry(uint32_t DataOffset,
                                         unsigned Index) const {
  uint64_t Offset = DataOffset + Index * sizeof(MachO::data_in_code_entry);
  return getStruct<MachO::data_in_code_entry>(this, getPtr(this, Offset));
}

MachO::symtab_command MachOObjectFile::getSymtabLoadCommand() const {
  return getStruct<MachO::symtab_command>(this, SymtabLoadCmd);
}

MachO::dysymtab_command MachOObjectFile::getDysymtabLoadCommand() const {
  return getStruct<MachO::dysymtab_command>(this, DysymtabLoadCmd);
}

MachO::linkedit_data_command
MachOObjectFile::getDataInCodeLoadCommand() const {
  if (DataInCodeLoadCmd)
    return getStruct<MachO::linkedit_data_command>(this, DataInCodeLoadCmd);

  // If there is no DataInCodeLoadCmd return a load command with zero'ed fields.
  MachO::linkedit_data_command Cmd;
  Cmd.cmd = MachO::LC_DATA_IN_CODE;
  Cmd.cmdsize = sizeof(MachO::linkedit_data_command);
  Cmd.dataoff = 0;
  Cmd.datasize = 0;
  return Cmd;
}

StringRef MachOObjectFile::getStringTableData() const {
  MachO::symtab_command S = getSymtabLoadCommand();
  return getData().substr(S.stroff, S.strsize);
}

bool MachOObjectFile::is64Bit() const {
  return getType() == getMachOType(false, true) ||
    getType() == getMachOType(true, true);
}

void MachOObjectFile::ReadULEB128s(uint64_t Index,
                                   SmallVectorImpl<uint64_t> &Out) const {
  DataExtractor extractor(ObjectFile::getData(), true, 0);

  uint32_t offset = Index;
  uint64_t data = 0;
  while (uint64_t delta = extractor.getULEB128(&offset)) {
    data += delta;
    Out.push_back(data);
  }
}

ErrorOr<ObjectFile *> ObjectFile::createMachOObjectFile(MemoryBuffer *Buffer,
                                                        bool BufferOwned) {
  StringRef Magic = Buffer->getBuffer().slice(0, 4);
  error_code EC;
  std::unique_ptr<MachOObjectFile> Ret;
  if (Magic == "\xFE\xED\xFA\xCE")
    Ret.reset(new MachOObjectFile(Buffer, false, false, EC, BufferOwned));
  else if (Magic == "\xCE\xFA\xED\xFE")
    Ret.reset(new MachOObjectFile(Buffer, true, false, EC, BufferOwned));
  else if (Magic == "\xFE\xED\xFA\xCF")
    Ret.reset(new MachOObjectFile(Buffer, false, true, EC, BufferOwned));
  else if (Magic == "\xCF\xFA\xED\xFE")
    Ret.reset(new MachOObjectFile(Buffer, true, true, EC, BufferOwned));
  else {
    delete Buffer;
    return object_error::parse_failed;
  }

  if (EC)
    return EC;
  return Ret.release();
}

} // end namespace object
} // end namespace llvm