llvm-project/lld/lib/ReaderWriter/MachO/MachONormalizedFileYAML.cpp

//===- lib/ReaderWriter/MachO/MachONormalizedFileYAML.cpp -----------------===//
//
//                             The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

///
/// \file For mach-o object files, this implementation uses YAML I/O to
/// provide the convert between YAML and the normalized mach-o (NM).
///
///                  +------------+         +------+ 
///                  | normalized |   <->   | yaml | 
///                  +------------+         +------+ 

#include "MachONormalizedFile.h"

#include "lld/Core/Error.h"
#include "lld/Core/LLVM.h"
#include "lld/ReaderWriter/YamlContext.h"

#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MachO.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/system_error.h"
#include "llvm/Support/YAMLTraits.h"


using llvm::StringRef;
using llvm::error_code;
using llvm::dyn_cast;
using namespace llvm::yaml;
using namespace llvm::MachO;
using namespace lld::mach_o::normalized;
using lld::YamlContext;

LLVM_YAML_IS_SEQUENCE_VECTOR(Segment)
LLVM_YAML_IS_SEQUENCE_VECTOR(DependentDylib)
LLVM_YAML_IS_SEQUENCE_VECTOR(RebaseLocation)
LLVM_YAML_IS_SEQUENCE_VECTOR(BindLocation)
LLVM_YAML_IS_SEQUENCE_VECTOR(Export)
LLVM_YAML_IS_SEQUENCE_VECTOR(StringRef)


// for compatibility with gcc-4.7 in C++11 mode, add extra namespace
namespace llvm {
namespace yaml {

// A vector of Sections is a sequence.
template<>
struct SequenceTraits< std::vector<Section> > {
  static size_t size(IO &io, std::vector<Section> &seq) {
    return seq.size();
  }
  static Section& element(IO &io, std::vector<Section> &seq, size_t index) {
    if ( index >= seq.size() )
      seq.resize(index+1);
    return seq[index];
  }
};

template<>
struct SequenceTraits< std::vector<Symbol> > {
  static size_t size(IO &io, std::vector<Symbol> &seq) {
    return seq.size();
  }
  static Symbol& element(IO &io, std::vector<Symbol> &seq, size_t index) {
    if ( index >= seq.size() )
      seq.resize(index+1);
    return seq[index];
  }
};

// A vector of Relocations is a sequence.
template<>
struct SequenceTraits< Relocations > {
  static size_t size(IO &io, Relocations &seq) {
    return seq.size();
  }
  static Relocation& element(IO &io, Relocations &seq, size_t index) {
    if ( index >= seq.size() )
      seq.resize(index+1);
    return seq[index];
  }
};

// The content for a section is represented as a flow sequence of hex bytes.
template<>
struct SequenceTraits< ContentBytes > {
  static size_t size(IO &io, ContentBytes &seq) {
    return seq.size();
  }
  static Hex8& element(IO &io, ContentBytes &seq, size_t index) {
    if ( index >= seq.size() )
      seq.resize(index+1);
    return seq[index];
  }
  static const bool flow = true;
};

// The indirect symbols for a section is represented as a flow sequence 
// of numbers (symbol table indexes).
template<>
struct SequenceTraits< IndirectSymbols > {
  static size_t size(IO &io, IndirectSymbols &seq) {
    return seq.size();
  }
  static uint32_t& element(IO &io, IndirectSymbols &seq, size_t index) {
    if ( index >= seq.size() )
      seq.resize(index+1);
    return seq[index];
  }
  static const bool flow = true;
};

template <>
struct ScalarEnumerationTraits<lld::MachOLinkingContext::Arch> {
  static void enumeration(IO &io, lld::MachOLinkingContext::Arch &value) {
    io.enumCase(value, "unknown",lld::MachOLinkingContext::arch_unknown);
    io.enumCase(value, "ppc",    lld::MachOLinkingContext::arch_ppc);
    io.enumCase(value, "x86",    lld::MachOLinkingContext::arch_x86);
    io.enumCase(value, "x86_64", lld::MachOLinkingContext::arch_x86_64);
    io.enumCase(value, "armv6",  lld::MachOLinkingContext::arch_armv6);
    io.enumCase(value, "armv7",  lld::MachOLinkingContext::arch_armv7);
    io.enumCase(value, "armv7s", lld::MachOLinkingContext::arch_armv7s);
  }
};

template <>
struct ScalarEnumerationTraits<lld::MachOLinkingContext::OS> {
  static void enumeration(IO &io, lld::MachOLinkingContext::OS &value) {
    io.enumCase(value, "unknown",    
                          lld::MachOLinkingContext::OS::unknown);
    io.enumCase(value, "Mac OS X",    
                          lld::MachOLinkingContext::OS::macOSX);
    io.enumCase(value, "iOS",         
                          lld::MachOLinkingContext::OS::iOS);
    io.enumCase(value, "iOS Simulator", 
                          lld::MachOLinkingContext::OS::iOS_simulator);
  }
};


template <>
struct ScalarEnumerationTraits<HeaderFileType> {
  static void enumeration(IO &io, HeaderFileType &value) {
    io.enumCase(value, "object",      llvm::MachO::MH_OBJECT);
    io.enumCase(value, "dylib",       llvm::MachO::MH_DYLIB);
    io.enumCase(value, "executable",  llvm::MachO::MH_EXECUTE);
    io.enumCase(value, "bundle",      llvm::MachO::MH_BUNDLE);
  }
};


template <>
struct ScalarBitSetTraits<FileFlags> {
  static void bitset(IO &io, FileFlags &value) {
    io.bitSetCase(value, "MH_TWOLEVEL", 
                          llvm::MachO::MH_TWOLEVEL);
    io.bitSetCase(value, "MH_SUBSECTIONS_VIA_SYMBOLS",  
                          llvm::MachO::MH_SUBSECTIONS_VIA_SYMBOLS);
  }
};


template <>
struct ScalarEnumerationTraits<SectionType> {
  static void enumeration(IO &io, SectionType &value) {
    io.enumCase(value, "S_REGULAR",  
                        llvm::MachO::S_REGULAR);
    io.enumCase(value, "S_ZEROFILL", 
                        llvm::MachO::S_ZEROFILL);
    io.enumCase(value, "S_CSTRING_LITERALS", 
                        llvm::MachO::S_CSTRING_LITERALS);
    io.enumCase(value, "S_4BYTE_LITERALS", 
                        llvm::MachO::S_4BYTE_LITERALS);
    io.enumCase(value, "S_8BYTE_LITERALS", 
                        llvm::MachO::S_8BYTE_LITERALS);
    io.enumCase(value, "S_LITERAL_POINTERS", 
                        llvm::MachO::S_LITERAL_POINTERS);
    io.enumCase(value, "S_NON_LAZY_SYMBOL_POINTERS", 
                        llvm::MachO::S_NON_LAZY_SYMBOL_POINTERS);
    io.enumCase(value, "S_LAZY_SYMBOL_POINTERS", 
                        llvm::MachO::S_LAZY_SYMBOL_POINTERS);
    io.enumCase(value, "S_SYMBOL_STUBS", 
                        llvm::MachO::S_SYMBOL_STUBS);
    io.enumCase(value, "S_MOD_INIT_FUNC_POINTERS", 
                        llvm::MachO::S_MOD_INIT_FUNC_POINTERS);
    io.enumCase(value, "S_MOD_TERM_FUNC_POINTERS", 
                        llvm::MachO::S_MOD_TERM_FUNC_POINTERS);
    io.enumCase(value, "S_COALESCED", 
                        llvm::MachO::S_COALESCED);
    io.enumCase(value, "S_GB_ZEROFILL", 
                        llvm::MachO::S_GB_ZEROFILL);
    io.enumCase(value, "S_INTERPOSING", 
                        llvm::MachO::S_INTERPOSING);
    io.enumCase(value, "S_16BYTE_LITERALS", 
                        llvm::MachO::S_16BYTE_LITERALS);
    io.enumCase(value, "S_DTRACE_DOF", 
                        llvm::MachO::S_DTRACE_DOF);
    io.enumCase(value, "S_LAZY_DYLIB_SYMBOL_POINTERS", 
                        llvm::MachO::S_LAZY_DYLIB_SYMBOL_POINTERS);
    io.enumCase(value, "S_THREAD_LOCAL_REGULAR", 
                        llvm::MachO::S_THREAD_LOCAL_REGULAR);
    io.enumCase(value, "S_THREAD_LOCAL_ZEROFILL", 
                        llvm::MachO::S_THREAD_LOCAL_ZEROFILL);
    io.enumCase(value, "S_THREAD_LOCAL_VARIABLES", 
                        llvm::MachO::S_THREAD_LOCAL_VARIABLES);
    io.enumCase(value, "S_THREAD_LOCAL_VARIABLE_POINTERS", 
                        llvm::MachO::S_THREAD_LOCAL_VARIABLE_POINTERS);
    io.enumCase(value, "S_THREAD_LOCAL_INIT_FUNCTION_POINTERS", 
                        llvm::MachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS);
  }
};

template <>
struct ScalarBitSetTraits<SectionAttr> {
  static void bitset(IO &io, SectionAttr &value) {
    io.bitSetCase(value, "S_ATTR_PURE_INSTRUCTIONS", 
                          llvm::MachO::S_ATTR_PURE_INSTRUCTIONS);
    io.bitSetCase(value, "S_ATTR_SOME_INSTRUCTIONS",  
                          llvm::MachO::S_ATTR_SOME_INSTRUCTIONS);
    io.bitSetCase(value, "S_ATTR_NO_DEAD_STRIP",  
                          llvm::MachO::S_ATTR_NO_DEAD_STRIP);
    io.bitSetCase(value, "S_ATTR_EXT_RELOC",  
                          llvm::MachO::S_ATTR_EXT_RELOC);
    io.bitSetCase(value, "S_ATTR_LOC_RELOC",  
                          llvm::MachO::S_ATTR_LOC_RELOC);
  }
};

template <>
struct ScalarEnumerationTraits<NListType> {
  static void enumeration(IO &io, NListType &value) {
    io.enumCase(value, "N_UNDF",  llvm::MachO::N_UNDF);
    io.enumCase(value, "N_ABS",   llvm::MachO::N_ABS);
    io.enumCase(value, "N_SECT",  llvm::MachO::N_SECT);
    io.enumCase(value, "N_PBUD",  llvm::MachO::N_PBUD);
    io.enumCase(value, "N_INDR",  llvm::MachO::N_INDR);
  }
};

template <>
struct ScalarBitSetTraits<SymbolScope> {
  static void bitset(IO &io, SymbolScope &value) {
    io.bitSetCase(value, "N_EXT",   llvm::MachO::N_EXT);
    io.bitSetCase(value, "N_PEXT",  llvm::MachO::N_PEXT);
  }
};

template <>
struct ScalarBitSetTraits<SymbolDesc> {
  static void bitset(IO &io, SymbolDesc &value) {
    io.bitSetCase(value, "N_NO_DEAD_STRIP",   llvm::MachO::N_NO_DEAD_STRIP);
    io.bitSetCase(value, "N_WEAK_REF",        llvm::MachO::N_WEAK_REF);
    io.bitSetCase(value, "N_WEAK_DEF",        llvm::MachO::N_WEAK_DEF);
    io.bitSetCase(value, "N_ARM_THUMB_DEF",   llvm::MachO::N_ARM_THUMB_DEF);
    io.bitSetCase(value, "N_SYMBOL_RESOLVER", llvm::MachO::N_SYMBOL_RESOLVER);
  }
};


template <>
struct MappingTraits<Section> {
  struct NormalizedContentBytes;
  static void mapping(IO &io, Section &sect) {
    io.mapRequired("segment",         sect.segmentName);
    io.mapRequired("section",         sect.sectionName);
    io.mapRequired("type",            sect.type);
    io.mapOptional("attributes",      sect.attributes);
    io.mapOptional("alignment",       sect.alignment, 0U);
    io.mapRequired("address",         sect.address);
    MappingNormalization<NormalizedContent, std::vector<uint8_t>> content(
        io, sect.content);
    io.mapOptional("content",         content->normalizedContent);
    io.mapOptional("relocations",     sect.relocations);
    io.mapOptional("indirect-syms",   sect.indirectSymbols);
  }

  // FIXME: It would be good if we could remove this, so we don't need to copy
  // the content data.
  struct NormalizedContent {
    NormalizedContent(IO &) {}
    NormalizedContent(IO &, std::vector<uint8_t> content) {
      for (auto &c : content) {
        normalizedContent.push_back(c);
      }
    }
    std::vector<uint8_t> denormalize(IO &) {
      std::vector<uint8_t> content;
      for (auto &c : normalizedContent) {
        content.push_back(c);
      }
      return content;
    }
    ContentBytes normalizedContent;
  };
};


template <>
struct MappingTraits<Relocation> {
  static void mapping(IO &io, Relocation &reloc) {
    io.mapRequired("offset",    reloc.offset);
    io.mapOptional("scattered", reloc.scattered, false);
    io.mapRequired("type",      reloc.type);
    io.mapRequired("length",    reloc.length);
    io.mapRequired("pc-rel",    reloc.pcRel);
    if ( !reloc.scattered )
     io.mapRequired("extern",   reloc.isExtern);
    if ( reloc.scattered )
     io.mapRequired("value",    reloc.value);
    if ( !reloc.scattered )
     io.mapRequired("symbol",   reloc.symbol);
  }
};


template <>
struct ScalarEnumerationTraits<RelocationInfoType> {
  static void enumeration(IO &io, RelocationInfoType &value) {
    YamlContext *info = reinterpret_cast<YamlContext *>(io.getContext());
    assert(info != nullptr);
    NormalizedFile *file = info->_normalizeMachOFile;
    assert(file != nullptr);
    switch (file->arch) {
    case lld::MachOLinkingContext::arch_x86_64:
      io.enumCase(value, "X86_64_RELOC_UNSIGNED",  
                                  llvm::MachO::X86_64_RELOC_UNSIGNED);
      io.enumCase(value, "X86_64_RELOC_SIGNED",   
                                  llvm::MachO::X86_64_RELOC_SIGNED);
      io.enumCase(value, "X86_64_RELOC_BRANCH",    
                                  llvm::MachO::X86_64_RELOC_BRANCH);
      io.enumCase(value, "X86_64_RELOC_GOT_LOAD",    
                                  llvm::MachO::X86_64_RELOC_GOT_LOAD);
      io.enumCase(value, "X86_64_RELOC_GOT",    
                                  llvm::MachO::X86_64_RELOC_GOT);
      io.enumCase(value, "X86_64_RELOC_SUBTRACTOR",   
                                  llvm::MachO::X86_64_RELOC_SUBTRACTOR);
      io.enumCase(value, "X86_64_RELOC_SIGNED_1",    
                                  llvm::MachO::X86_64_RELOC_SIGNED_1);
      io.enumCase(value, "X86_64_RELOC_SIGNED_2",    
                                  llvm::MachO::X86_64_RELOC_SIGNED_2);
      io.enumCase(value, "X86_64_RELOC_SIGNED_4",    
                                  llvm::MachO::X86_64_RELOC_SIGNED_4);
      io.enumCase(value, "X86_64_RELOC_TLV",    
                                  llvm::MachO::X86_64_RELOC_TLV);
      break;
    case lld::MachOLinkingContext::arch_x86:
      io.enumCase(value, "GENERIC_RELOC_VANILLA",  
                                  llvm::MachO::GENERIC_RELOC_VANILLA);
      io.enumCase(value, "GENERIC_RELOC_PAIR",   
                                  llvm::MachO::GENERIC_RELOC_PAIR);
      io.enumCase(value, "GENERIC_RELOC_SECTDIFF",  
                                  llvm::MachO::GENERIC_RELOC_SECTDIFF);
      io.enumCase(value, "GENERIC_RELOC_LOCAL_SECTDIFF",   
                                  llvm::MachO::GENERIC_RELOC_LOCAL_SECTDIFF);
      io.enumCase(value, "GENERIC_RELOC_TLV",   
                                  llvm::MachO::GENERIC_RELOC_TLV);
      break;
    case lld::MachOLinkingContext::arch_armv6:
    case lld::MachOLinkingContext::arch_armv7:
    case lld::MachOLinkingContext::arch_armv7s:
       io.enumCase(value, "ARM_RELOC_VANILLA",  
                                  llvm::MachO::ARM_RELOC_VANILLA);
      io.enumCase(value, "ARM_RELOC_PAIR",   
                                  llvm::MachO::ARM_RELOC_PAIR);
      io.enumCase(value, "ARM_RELOC_SECTDIFF",  
                                  llvm::MachO::ARM_RELOC_SECTDIFF);
      io.enumCase(value, "ARM_RELOC_LOCAL_SECTDIFF",   
                                  llvm::MachO::ARM_RELOC_LOCAL_SECTDIFF);
      io.enumCase(value, "ARM_RELOC_BR24",   
                                  llvm::MachO::ARM_RELOC_BR24);
      io.enumCase(value, "ARM_THUMB_RELOC_BR22",   
                                  llvm::MachO::ARM_THUMB_RELOC_BR22);
      io.enumCase(value, "ARM_RELOC_HALF",   
                                  llvm::MachO::ARM_RELOC_HALF);
      io.enumCase(value, "ARM_RELOC_HALF_SECTDIFF",   
                                  llvm::MachO::ARM_RELOC_HALF_SECTDIFF);
      break;
    default:
      llvm_unreachable("unknown architecture");
    }
 }
};


template <>
struct MappingTraits<Symbol> {
  static void mapping(IO &io, Symbol& sym) {
    io.mapRequired("name",    sym.name);
    io.mapRequired("type",    sym.type);
    io.mapOptional("scope",   sym.scope, SymbolScope(0));
    io.mapOptional("sect",    sym.sect, (uint8_t)0);
    io.mapOptional("desc",    sym.desc, SymbolDesc(0));
    io.mapRequired("value",   sym.value);
  }
};

// Custom mapping for VMProtect (e.g. "r-x").
template <>
struct ScalarTraits<VMProtect> {
  static void output(const VMProtect &value, void*, raw_ostream &out) {
    out << ( (value & llvm::MachO::VM_PROT_READ)    ? 'r' : '-');
    out << ( (value & llvm::MachO::VM_PROT_WRITE)   ? 'w' : '-');
    out << ( (value & llvm::MachO::VM_PROT_EXECUTE) ? 'x' : '-');
  }
  static StringRef input(StringRef scalar, void*, VMProtect &value) {
    value = 0;
    if (scalar.size() != 3)
      return "segment access protection must be three chars (e.g. \"r-x\")";
    switch (scalar[0]) {
    case 'r':
      value = llvm::MachO::VM_PROT_READ;
      break;
    case '-':
      break;
    default:
      return "segment access protection first char must be 'r' or '-'";
    }
    switch (scalar[1]) {
    case 'w':
      value = value | llvm::MachO::VM_PROT_WRITE;
      break;
    case '-':
      break;
    default:
      return "segment access protection second char must be 'w' or '-'";
    }
    switch (scalar[2]) {
    case 'x':
      value = value | llvm::MachO::VM_PROT_EXECUTE;
      break;
    case '-':
      break;
    default:
      return "segment access protection third char must be 'x' or '-'";
    }
    // Return the empty string on success,
    return StringRef();
  }
};


template <>
struct MappingTraits<Segment> {
  static void mapping(IO &io, Segment& seg) {
    io.mapRequired("name",      seg.name);
    io.mapRequired("address",   seg.address);
    io.mapRequired("size",      seg.size);
    io.mapRequired("access",    seg.access);
  }
};

template <>
struct ScalarEnumerationTraits<LoadCommandType> {
  static void enumeration(IO &io, LoadCommandType &value) {
    io.enumCase(value, "LC_LOAD_DYLIB",  
                        llvm::MachO::LC_LOAD_DYLIB);
    io.enumCase(value, "LC_LOAD_WEAK_DYLIB",  
                        llvm::MachO::LC_LOAD_WEAK_DYLIB);
    io.enumCase(value, "LC_REEXPORT_DYLIB",  
                        llvm::MachO::LC_REEXPORT_DYLIB);
    io.enumCase(value, "LC_LOAD_UPWARD_DYLIB", 
                        llvm::MachO::LC_LOAD_UPWARD_DYLIB);
    io.enumCase(value, "LC_LAZY_LOAD_DYLIB",  
                        llvm::MachO::LC_LAZY_LOAD_DYLIB);
  }
};

template <>
struct MappingTraits<DependentDylib> {
  static void mapping(IO &io, DependentDylib& dylib) {
    io.mapRequired("path",    dylib.path);
    io.mapOptional("kind",    dylib.kind,       llvm::MachO::LC_LOAD_DYLIB);
  }
};


template <>
struct ScalarEnumerationTraits<RebaseType> {
  static void enumeration(IO &io, RebaseType &value) {
    io.enumCase(value, "REBASE_TYPE_POINTER",  
                        llvm::MachO::REBASE_TYPE_POINTER);
    io.enumCase(value, "REBASE_TYPE_TEXT_PCREL32",  
                        llvm::MachO::REBASE_TYPE_TEXT_PCREL32);
    io.enumCase(value, "REBASE_TYPE_TEXT_ABSOLUTE32",  
                        llvm::MachO::REBASE_TYPE_TEXT_ABSOLUTE32);
  }
};


template <>
struct MappingTraits<RebaseLocation> {
  static void mapping(IO &io, RebaseLocation& rebase) {
    io.mapRequired("segment-index",   rebase.segIndex);
    io.mapRequired("segment-offset",  rebase.segOffset);
    io.mapOptional("kind",            rebase.kind, 
                                      llvm::MachO::REBASE_TYPE_POINTER);
  }
};



template <>
struct ScalarEnumerationTraits<BindType> {
  static void enumeration(IO &io, BindType &value) {
    io.enumCase(value, "BIND_TYPE_POINTER",  
                        llvm::MachO::BIND_TYPE_POINTER);
    io.enumCase(value, "BIND_TYPE_TEXT_ABSOLUTE32",  
                        llvm::MachO::BIND_TYPE_TEXT_ABSOLUTE32);
    io.enumCase(value, "BIND_TYPE_TEXT_PCREL32",  
                        llvm::MachO::BIND_TYPE_TEXT_PCREL32);
  }
};

template <>
struct MappingTraits<BindLocation> {
  static void mapping(IO &io, BindLocation &bind) {
    io.mapRequired("segment-index",   bind.segIndex);
    io.mapRequired("segment-offset",  bind.segOffset);
    io.mapOptional("kind",            bind.kind, 
                                      llvm::MachO::BIND_TYPE_POINTER);
    io.mapOptional("can-be-null",     bind.canBeNull, false);
    io.mapRequired("ordinal",         bind.ordinal);
    io.mapRequired("symbol-name",     bind.symbolName);
    io.mapOptional("addend",          bind.addend, Hex64(0));
  }
};


template <>
struct ScalarEnumerationTraits<ExportSymbolKind> {
  static void enumeration(IO &io, ExportSymbolKind &value) {
    io.enumCase(value, "EXPORT_SYMBOL_FLAGS_KIND_REGULAR",       
                        llvm::MachO::EXPORT_SYMBOL_FLAGS_KIND_REGULAR);
    io.enumCase(value, "EXPORT_SYMBOL_FLAGS_KIND_THREAD_LOCALl",  
                        llvm::MachO::EXPORT_SYMBOL_FLAGS_KIND_THREAD_LOCAL);
  }
};

template <>
struct ScalarBitSetTraits<ExportFlags> {
  static void bitset(IO &io, ExportFlags &value) {
    io.bitSetCase(value, "EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION",   
                          llvm::MachO::EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION);
    io.bitSetCase(value, "EXPORT_SYMBOL_FLAGS_REEXPORT",         
                          llvm::MachO::EXPORT_SYMBOL_FLAGS_REEXPORT);
    io.bitSetCase(value, "EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER",    
                          llvm::MachO::EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER);
  }
};


template <>
struct MappingTraits<Export> {
  static void mapping(IO &io, Export &exp) {
    io.mapRequired("name",         exp.name);
    io.mapRequired("offset",       exp.offset);
    io.mapOptional("kind",         exp.kind, 
                                llvm::MachO::EXPORT_SYMBOL_FLAGS_KIND_REGULAR);
    io.mapOptional("flags",        exp.flags);
    io.mapOptional("other-offset", exp.otherOffset, Hex32(0));
    io.mapOptional("other-name",   exp.otherName, StringRef());
  }
};


template <>
struct MappingTraits<NormalizedFile> {
  static void mapping(IO &io, NormalizedFile &file) {
    io.mapRequired("arch",             file.arch);
    io.mapRequired("file-type",        file.fileType);
    io.mapOptional("flags",            file.flags);
    io.mapOptional("dependents",       file.dependentDylibs);
    io.mapOptional("install-name",     file.installName,    StringRef());
    io.mapOptional("has-UUID",         file.hasUUID,        true);
    io.mapOptional("rpaths",           file.rpaths);
    io.mapOptional("entry-point",      file.entryAddress,   Hex64(0));
    io.mapOptional("source-version",   file.sourceVersion,  Hex64(0));
    io.mapOptional("OS",               file.os);
    io.mapOptional("min-os-version",   file.minOSverson,    Hex32(0));
    io.mapOptional("sdk-version",      file.sdkVersion,     Hex32(0));
    io.mapOptional("segments",         file.segments);
    io.mapOptional("sections",         file.sections);
    io.mapOptional("local-symbols",    file.localSymbols);
    io.mapOptional("global-symbols",   file.globalSymbols);
    io.mapOptional("undefined-symbols",file.undefinedSymbols);
    io.mapOptional("rebasings",        file.rebasingInfo);
    io.mapOptional("bindings",         file.bindingInfo);
    io.mapOptional("weak-bindings",    file.weakBindingInfo);
    io.mapOptional("lazy-bindings",    file.lazyBindingInfo);
    io.mapOptional("exports",          file.exportInfo);
  }
  static StringRef validate(IO &io, NormalizedFile &file) {
    return StringRef();
  }
};

} // namespace llvm
} // namespace yaml


namespace lld {
namespace mach_o {
namespace normalized {

/// Parses a yaml encoded mach-o file to produce an in-memory normalized view.
ErrorOr<std::unique_ptr<NormalizedFile>> 
readYaml(std::unique_ptr<MemoryBuffer> &mb) {
  // Make empty NormalizedFile.
  std::unique_ptr<NormalizedFile> f(new NormalizedFile());

  // Create YAML Input parser.
  YamlContext yamlContext;
  yamlContext._normalizeMachOFile = f.get();
  llvm::yaml::Input yin(mb->getBuffer(), &yamlContext);

  // Fill NormalizedFile by parsing yaml.
  yin >> *f;

  // Return error if there were parsing problems.
  if (yin.error())
    return make_error_code(lld::YamlReaderError::illegal_value);

  // Hand ownership of instantiated NormalizedFile to caller.
  return std::move(f);
}


/// Writes a yaml encoded mach-o files from an in-memory normalized view.
error_code 
writeYaml(const NormalizedFile &file, raw_ostream &out) {
  // YAML I/O is not const aware, so need to cast away ;-(
  NormalizedFile *f = const_cast<NormalizedFile*>(&file);

  // Create yaml Output writer, using yaml options for context.
  YamlContext yamlContext;
  yamlContext._normalizeMachOFile = f;
  llvm::yaml::Output yout(out, &yamlContext);

  // Stream out yaml.
  yout << *f;

  return error_code::success();
}

} // namespace normalized
} // namespace mach_o
} // namespace lld