tools/yaml2obj/yaml2coff.cpp

   1 //===- yaml2coff - Convert YAML to a COFF object file ---------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 ///
  10 /// \file
  11 /// \brief The COFF component of yaml2obj.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "yaml2obj.h"
  16 #include "llvm/ADT/SmallString.h"
  17 #include "llvm/ADT/STLExtras.h"
  18 #include "llvm/ADT/StringExtras.h"
  19 #include "llvm/ADT/StringMap.h"
  20 #include "llvm/ADT/StringSwitch.h"
  21 #include "llvm/Object/COFFYAML.h"
  22 #include "llvm/Object/COFF.h"
  23 #include "llvm/Support/Endian.h"
  24 #include "llvm/Support/MemoryBuffer.h"
  25 #include "llvm/Support/SourceMgr.h"
  26 #include "llvm/Support/raw_ostream.h"
  27 #include <vector>
  28
  29 using namespace llvm;
  30
  31 /// This parses a yaml stream that represents a COFF object file.
  32 /// See docs/yaml2obj for the yaml scheema.
  33 struct COFFParser {
  34   COFFParser(COFFYAML::Object &Obj)
  35       : Obj(Obj), SectionTableStart(0), SectionTableSize(0) {
  36     // A COFF string table always starts with a 4 byte size field. Offsets into
  37     // it include this size, so allocate it now.
  38     StringTable.append(4, char(0));
  39   }
  40
  41   bool useBigObj() const {
  42     return static_cast<int32_t>(Obj.Sections.size()) >
  43            COFF::MaxNumberOfSections16;
  44   }
  45
  46   bool isPE() const { return Obj.OptionalHeader.hasValue(); }
  47   bool is64Bit() const {
  48     return Obj.Header.Machine == COFF::IMAGE_FILE_MACHINE_AMD64;
  49   }
  50
  51   uint32_t getFileAlignment() const {
  52     return Obj.OptionalHeader->Header.FileAlignment;
  53   }
  54
  55   unsigned getHeaderSize() const {
  56     return useBigObj() ? COFF::Header32Size : COFF::Header16Size;
  57   }
  58
  59   unsigned getSymbolSize() const {
  60     return useBigObj() ? COFF::Symbol32Size : COFF::Symbol16Size;
  61   }
  62
  63   bool parseSections() {
  64     for (std::vector<COFFYAML::Section>::iterator i = Obj.Sections.begin(),
  65            e = Obj.Sections.end(); i != e; ++i) {
  66       COFFYAML::Section &Sec = *i;
  67
  68       // If the name is less than 8 bytes, store it in place, otherwise
  69       // store it in the string table.
  70       StringRef Name = Sec.Name;
  71
  72       if (Name.size() <= COFF::NameSize) {
  73         std::copy(Name.begin(), Name.end(), Sec.Header.Name);
  74       } else {
  75         // Add string to the string table and format the index for output.
  76         unsigned Index = getStringIndex(Name);
  77         std::string str = utostr(Index);
  78         if (str.size() > 7) {
  79           errs() << "String table got too large";
  80           return false;
  81         }
  82         Sec.Header.Name[0] = '/';
  83         std::copy(str.begin(), str.end(), Sec.Header.Name + 1);
  84       }
  85
  86       Sec.Header.Characteristics |= (Log2_32(Sec.Alignment) + 1) << 20;
  87     }
  88     return true;
  89   }
  90
  91   bool parseSymbols() {
  92     for (std::vector<COFFYAML::Symbol>::iterator i = Obj.Symbols.begin(),
  93            e = Obj.Symbols.end(); i != e; ++i) {
  94       COFFYAML::Symbol &Sym = *i;
  95
  96       // If the name is less than 8 bytes, store it in place, otherwise
  97       // store it in the string table.
  98       StringRef Name = Sym.Name;
  99       if (Name.size() <= COFF::NameSize) {
 100         std::copy(Name.begin(), Name.end(), Sym.Header.Name);
 101       } else {
 102         // Add string to the string table and format the index for output.
 103         unsigned Index = getStringIndex(Name);
 104         *reinterpret_cast<support::aligned_ulittle32_t*>(
 105             Sym.Header.Name + 4) = Index;
 106       }
 107
 108       Sym.Header.Type = Sym.SimpleType;
 109       Sym.Header.Type |= Sym.ComplexType << COFF::SCT_COMPLEX_TYPE_SHIFT;
 110     }
 111     return true;
 112   }
 113
 114   bool parse() {
 115     if (!parseSections())
 116       return false;
 117     if (!parseSymbols())
 118       return false;
 119     return true;
 120   }
 121
 122   unsigned getStringIndex(StringRef Str) {
 123     StringMap<unsigned>::iterator i = StringTableMap.find(Str);
 124     if (i == StringTableMap.end()) {
 125       unsigned Index = StringTable.size();
 126       StringTable.append(Str.begin(), Str.end());
 127       StringTable.push_back(0);
 128       StringTableMap[Str] = Index;
 129       return Index;
 130     }
 131     return i->second;
 132   }
 133
 134   COFFYAML::Object &Obj;
 135
 136   StringMap<unsigned> StringTableMap;
 137   std::string StringTable;
 138   uint32_t SectionTableStart;
 139   uint32_t SectionTableSize;
 140 };
 141
 142 // Take a CP and assign addresses and sizes to everything. Returns false if the
 143 // layout is not valid to do.
 144 static bool layoutOptionalHeader(COFFParser &CP) {
 145   if (!CP.isPE())
 146     return true;
 147   CP.Obj.Header.SizeOfOptionalHeader =
 148       (CP.is64Bit() ? sizeof(object::pe32plus_header)
 149                     : sizeof(object::pe32_header)) +
 150       (sizeof(object::data_directory) * (COFF::NUM_DATA_DIRECTORIES + 1));
 151   return true;
 152 }
 153
 154 // Take a CP and assign addresses and sizes to everything. Returns false if the
 155 // layout is not valid to do.
 156 static bool layoutCOFF(COFFParser &CP) {
 157   // The section table starts immediately after the header, including the
 158   // optional header.
 159   CP.SectionTableStart =
 160       CP.getHeaderSize() + CP.Obj.Header.SizeOfOptionalHeader;
 161   CP.SectionTableSize = COFF::SectionSize * CP.Obj.Sections.size();
 162
 163   uint32_t CurrentSectionDataOffset =
 164       CP.SectionTableStart + CP.SectionTableSize;
 165
 166   // Assign each section data address consecutively.
 167   for (COFFYAML::Section &S : CP.Obj.Sections) {
 168     if (S.SectionData.binary_size() > 0) {
 169       CurrentSectionDataOffset = RoundUpToAlignment(
 170           CurrentSectionDataOffset, CP.isPE() ? CP.getFileAlignment() : 4);
 171       S.Header.SizeOfRawData = S.SectionData.binary_size();
 172       if (CP.isPE())
 173         S.Header.SizeOfRawData =
 174             RoundUpToAlignment(S.Header.SizeOfRawData, CP.getFileAlignment());
 175       S.Header.PointerToRawData = CurrentSectionDataOffset;
 176       CurrentSectionDataOffset += S.Header.SizeOfRawData;
 177       if (!S.Relocations.empty()) {
 178         S.Header.PointerToRelocations = CurrentSectionDataOffset;
 179         S.Header.NumberOfRelocations = S.Relocations.size();
 180         CurrentSectionDataOffset +=
 181             S.Header.NumberOfRelocations * COFF::RelocationSize;
 182       }
 183     } else {
 184       S.Header.SizeOfRawData = 0;
 185       S.Header.PointerToRawData = 0;
 186     }
 187   }
 188
 189   uint32_t SymbolTableStart = CurrentSectionDataOffset;
 190
 191   // Calculate number of symbols.
 192   uint32_t NumberOfSymbols = 0;
 193   for (std::vector<COFFYAML::Symbol>::iterator i = CP.Obj.Symbols.begin(),
 194                                                e = CP.Obj.Symbols.end();
 195                                                i != e; ++i) {
 196     uint32_t NumberOfAuxSymbols = 0;
 197     if (i->FunctionDefinition)
 198       NumberOfAuxSymbols += 1;
 199     if (i->bfAndefSymbol)
 200       NumberOfAuxSymbols += 1;
 201     if (i->WeakExternal)
 202       NumberOfAuxSymbols += 1;
 203     if (!i->File.empty())
 204       NumberOfAuxSymbols +=
 205           (i->File.size() + CP.getSymbolSize() - 1) / CP.getSymbolSize();
 206     if (i->SectionDefinition)
 207       NumberOfAuxSymbols += 1;
 208     if (i->CLRToken)
 209       NumberOfAuxSymbols += 1;
 210     i->Header.NumberOfAuxSymbols = NumberOfAuxSymbols;
 211     NumberOfSymbols += 1 + NumberOfAuxSymbols;
 212   }
 213
 214   // Store all the allocated start addresses in the header.
 215   CP.Obj.Header.NumberOfSections = CP.Obj.Sections.size();
 216   CP.Obj.Header.NumberOfSymbols = NumberOfSymbols;
 217   if (NumberOfSymbols > 0 || CP.StringTable.size() > 4)
 218     CP.Obj.Header.PointerToSymbolTable = SymbolTableStart;
 219   else
 220     CP.Obj.Header.PointerToSymbolTable = 0;
 221
 222   *reinterpret_cast<support::ulittle32_t *>(&CP.StringTable[0])
 223     = CP.StringTable.size();
 224
 225   return true;
 226 }
 227
 228 template <typename value_type>
 229 struct binary_le_impl {
 230   value_type Value;
 231   binary_le_impl(value_type V) : Value(V) {}
 232 };
 233
 234 template <typename value_type>
 235 raw_ostream &operator <<( raw_ostream &OS
 236                         , const binary_le_impl<value_type> &BLE) {
 237   char Buffer[sizeof(BLE.Value)];
 238   support::endian::write<value_type, support::little, support::unaligned>(
 239     Buffer, BLE.Value);
 240   OS.write(Buffer, sizeof(BLE.Value));
 241   return OS;
 242 }
 243
 244 template <typename value_type>
 245 binary_le_impl<value_type> binary_le(value_type V) {
 246   return binary_le_impl<value_type>(V);
 247 }
 248
 249 template <size_t NumBytes>
 250 struct zeros_impl {
 251   zeros_impl() {}
 252 };
 253
 254 template <size_t NumBytes>
 255 raw_ostream &operator<<(raw_ostream &OS, const zeros_impl<NumBytes> &) {
 256   char Buffer[NumBytes];
 257   memset(Buffer, 0, sizeof(Buffer));
 258   OS.write(Buffer, sizeof(Buffer));
 259   return OS;
 260 }
 261
 262 template <typename T>
 263 zeros_impl<sizeof(T)> zeros(const T &) {
 264   return zeros_impl<sizeof(T)>();
 265 }
 266
 267 struct num_zeros_impl {
 268   size_t N;
 269   num_zeros_impl(size_t N) : N(N) {}
 270 };
 271
 272 raw_ostream &operator<<(raw_ostream &OS, const num_zeros_impl &NZI) {
 273   for (size_t I = 0; I != NZI.N; ++I)
 274     OS.write(0);
 275   return OS;
 276 }
 277
 278 num_zeros_impl num_zeros(size_t N) {
 279   num_zeros_impl NZI(N);
 280   return NZI;
 281 }
 282
 283 template <typename T>
 284 static void initializeOptionalHeader(COFFParser &CP, uint16_t Magic, T Header) {
 285   memset(Header, 0, sizeof(*Header));
 286   Header->Magic = Magic;
 287   Header->SectionAlignment = CP.Obj.OptionalHeader->Header.SectionAlignment;
 288   uint32_t SizeOfCode = 0, SizeOfInitializedData = 0,
 289            SizeOfUninitializedData = 0;
 290   uint32_t SizeOfHeaders = RoundUpToAlignment(
 291       CP.SectionTableStart + CP.SectionTableSize, Header->SectionAlignment);
 292   uint32_t SizeOfImage = SizeOfHeaders;
 293   for (const COFFYAML::Section &S : CP.Obj.Sections) {
 294     if (S.Header.Characteristics & COFF::IMAGE_SCN_CNT_CODE)
 295       SizeOfCode += S.Header.SizeOfRawData;
 296     if (S.Header.Characteristics & COFF::IMAGE_SCN_CNT_INITIALIZED_DATA)
 297       SizeOfInitializedData += S.Header.SizeOfRawData;
 298     if (S.Header.Characteristics & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA)
 299       SizeOfUninitializedData += S.Header.SizeOfRawData;
 300     if (S.Name.equals(".text"))
 301       Header->BaseOfCode = S.Header.VirtualAddress;          // RVA
 302     if (S.Header.VirtualAddress)
 303       SizeOfImage +=
 304           RoundUpToAlignment(S.Header.VirtualSize, Header->SectionAlignment);
 305   }
 306   Header->SizeOfCode = SizeOfCode;
 307   Header->SizeOfInitializedData = SizeOfInitializedData;
 308   Header->SizeOfUninitializedData = SizeOfUninitializedData;
 309   Header->AddressOfEntryPoint =
 310       CP.Obj.OptionalHeader->Header.AddressOfEntryPoint; // RVA
 311   Header->ImageBase = CP.Obj.OptionalHeader->Header.ImageBase;
 312   Header->FileAlignment = CP.Obj.OptionalHeader->Header.FileAlignment;
 313   Header->MajorOperatingSystemVersion =
 314       CP.Obj.OptionalHeader->Header.MajorOperatingSystemVersion;
 315   Header->MinorOperatingSystemVersion =
 316       CP.Obj.OptionalHeader->Header.MinorOperatingSystemVersion;
 317   Header->MajorImageVersion =
 318       CP.Obj.OptionalHeader->Header.MajorImageVersion;
 319   Header->MinorImageVersion =
 320       CP.Obj.OptionalHeader->Header.MinorImageVersion;
 321   Header->MajorSubsystemVersion =
 322       CP.Obj.OptionalHeader->Header.MajorSubsystemVersion;
 323   Header->MinorSubsystemVersion =
 324       CP.Obj.OptionalHeader->Header.MinorSubsystemVersion;
 325   Header->SizeOfImage = SizeOfImage;
 326   Header->SizeOfHeaders = SizeOfHeaders;
 327   Header->Subsystem = CP.Obj.OptionalHeader->Header.Subsystem;
 328   Header->DLLCharacteristics = CP.Obj.OptionalHeader->Header.DLLCharacteristics;
 329   Header->SizeOfStackReserve = CP.Obj.OptionalHeader->Header.SizeOfStackReserve;
 330   Header->SizeOfStackCommit = CP.Obj.OptionalHeader->Header.SizeOfStackCommit;
 331   Header->SizeOfHeapReserve = CP.Obj.OptionalHeader->Header.SizeOfHeapReserve;
 332   Header->SizeOfHeapCommit = CP.Obj.OptionalHeader->Header.SizeOfHeapCommit;
 333   Header->NumberOfRvaAndSize = COFF::NUM_DATA_DIRECTORIES + 1;
 334 }
 335
 336 static bool writeCOFF(COFFParser &CP, raw_ostream &OS) {
 337   if (CP.isPE()) {
 338     // PE files start with a DOS stub.
 339     object::dos_header DH;
 340     memset(&DH, 0, sizeof(DH));
 341
 342     // DOS EXEs start with "MZ" magic.
 343     DH.Magic[0] = 'M';
 344     DH.Magic[1] = 'Z';
 345     // Initializing the AddressOfRelocationTable is strictly optional but
 346     // mollifies certain tools which expect it to have a value greater than
 347     // 0x40.
 348     DH.AddressOfRelocationTable = sizeof(DH);
 349     // This is the address of the PE signature.
 350     DH.AddressOfNewExeHeader = 128;
 351
 352     // Write out our DOS stub.
 353     OS.write(reinterpret_cast<char *>(&DH), sizeof(DH));
 354     // Write padding until we reach the position of where our PE signature
 355     // should live.
 356     OS << num_zeros(DH.AddressOfNewExeHeader - sizeof(DH));
 357     // Write out the PE signature.
 358     OS.write(COFF::PEMagic, sizeof(COFF::PEMagic));
 359   }
 360   if (CP.useBigObj()) {
 361     OS << binary_le(static_cast<uint16_t>(COFF::IMAGE_FILE_MACHINE_UNKNOWN))
 362        << binary_le(static_cast<uint16_t>(0xffff))
 363        << binary_le(static_cast<uint16_t>(COFF::BigObjHeader::MinBigObjectVersion))
 364        << binary_le(CP.Obj.Header.Machine)
 365        << binary_le(CP.Obj.Header.TimeDateStamp);
 366     OS.write(COFF::BigObjMagic, sizeof(COFF::BigObjMagic));
 367     OS << zeros(uint32_t(0))
 368        << zeros(uint32_t(0))
 369        << zeros(uint32_t(0))
 370        << zeros(uint32_t(0))
 371        << binary_le(CP.Obj.Header.NumberOfSections)
 372        << binary_le(CP.Obj.Header.PointerToSymbolTable)
 373        << binary_le(CP.Obj.Header.NumberOfSymbols);
 374   } else {
 375     OS << binary_le(CP.Obj.Header.Machine)
 376        << binary_le(static_cast<int16_t>(CP.Obj.Header.NumberOfSections))
 377        << binary_le(CP.Obj.Header.TimeDateStamp)
 378        << binary_le(CP.Obj.Header.PointerToSymbolTable)
 379        << binary_le(CP.Obj.Header.NumberOfSymbols)
 380        << binary_le(CP.Obj.Header.SizeOfOptionalHeader)
 381        << binary_le(CP.Obj.Header.Characteristics);
 382   }
 383   if (CP.isPE()) {
 384     if (CP.is64Bit()) {
 385       object::pe32plus_header PEH;
 386       initializeOptionalHeader(CP, COFF::PE32Header::PE32_PLUS, &PEH);
 387       OS.write(reinterpret_cast<char *>(&PEH), sizeof(PEH));
 388     } else {
 389       object::pe32_header PEH;
 390       initializeOptionalHeader(CP, COFF::PE32Header::PE32, &PEH);
 391       OS.write(reinterpret_cast<char *>(&PEH), sizeof(PEH));
 392     }
 393     for (const Optional<COFF::DataDirectory> &DD :
 394          CP.Obj.OptionalHeader->DataDirectories) {
 395       if (!DD.hasValue()) {
 396         OS << zeros(uint32_t(0));
 397         OS << zeros(uint32_t(0));
 398       } else {
 399         OS << binary_le(DD->RelativeVirtualAddress);
 400         OS << binary_le(DD->Size);
 401       }
 402     }
 403     OS << zeros(uint32_t(0));
 404     OS << zeros(uint32_t(0));
 405   }
 406
 407   // Output section table.
 408   for (std::vector<COFFYAML::Section>::iterator i = CP.Obj.Sections.begin(),
 409                                                 e = CP.Obj.Sections.end();
 410                                                 i != e; ++i) {
 411     OS.write(i->Header.Name, COFF::NameSize);
 412     OS << binary_le(i->Header.VirtualSize)
 413        << binary_le(i->Header.VirtualAddress)
 414        << binary_le(i->Header.SizeOfRawData)
 415        << binary_le(i->Header.PointerToRawData)
 416        << binary_le(i->Header.PointerToRelocations)
 417        << binary_le(i->Header.PointerToLineNumbers)
 418        << binary_le(i->Header.NumberOfRelocations)
 419        << binary_le(i->Header.NumberOfLineNumbers)
 420        << binary_le(i->Header.Characteristics);
 421   }
 422
 423   unsigned CurSymbol = 0;
 424   StringMap<unsigned> SymbolTableIndexMap;
 425   for (std::vector<COFFYAML::Symbol>::iterator I = CP.Obj.Symbols.begin(),
 426                                                E = CP.Obj.Symbols.end();
 427        I != E; ++I) {
 428     SymbolTableIndexMap[I->Name] = CurSymbol;
 429     CurSymbol += 1 + I->Header.NumberOfAuxSymbols;
 430   }
 431
 432   // Output section data.
 433   for (const COFFYAML::Section &S : CP.Obj.Sections) {
 434     if (!S.Header.SizeOfRawData)
 435       continue;
 436     OS << num_zeros(S.Header.PointerToRawData - OS.tell());
 437     S.SectionData.writeAsBinary(OS);
 438     OS << num_zeros(S.Header.SizeOfRawData - S.SectionData.binary_size());
 439     for (const COFFYAML::Relocation &R : S.Relocations) {
 440       uint32_t SymbolTableIndex = SymbolTableIndexMap[R.SymbolName];
 441       OS << binary_le(R.VirtualAddress)
 442          << binary_le(SymbolTableIndex)
 443          << binary_le(R.Type);
 444     }
 445   }
 446
 447   // Output symbol table.
 448
 449   for (std::vector<COFFYAML::Symbol>::const_iterator i = CP.Obj.Symbols.begin(),
 450                                                      e = CP.Obj.Symbols.end();
 451                                                      i != e; ++i) {
 452     OS.write(i->Header.Name, COFF::NameSize);
 453     OS << binary_le(i->Header.Value);
 454     if (CP.useBigObj())
 455        OS << binary_le(i->Header.SectionNumber);
 456     else
 457        OS << binary_le(static_cast<int16_t>(i->Header.SectionNumber));
 458     OS << binary_le(i->Header.Type)
 459        << binary_le(i->Header.StorageClass)
 460        << binary_le(i->Header.NumberOfAuxSymbols);
 461
 462     if (i->FunctionDefinition)
 463       OS << binary_le(i->FunctionDefinition->TagIndex)
 464          << binary_le(i->FunctionDefinition->TotalSize)
 465          << binary_le(i->FunctionDefinition->PointerToLinenumber)
 466          << binary_le(i->FunctionDefinition->PointerToNextFunction)
 467          << zeros(i->FunctionDefinition->unused)
 468          << num_zeros(CP.getSymbolSize() - COFF::Symbol16Size);
 469     if (i->bfAndefSymbol)
 470       OS << zeros(i->bfAndefSymbol->unused1)
 471          << binary_le(i->bfAndefSymbol->Linenumber)
 472          << zeros(i->bfAndefSymbol->unused2)
 473          << binary_le(i->bfAndefSymbol->PointerToNextFunction)
 474          << zeros(i->bfAndefSymbol->unused3)
 475          << num_zeros(CP.getSymbolSize() - COFF::Symbol16Size);
 476     if (i->WeakExternal)
 477       OS << binary_le(i->WeakExternal->TagIndex)
 478          << binary_le(i->WeakExternal->Characteristics)
 479          << zeros(i->WeakExternal->unused)
 480          << num_zeros(CP.getSymbolSize() - COFF::Symbol16Size);
 481     if (!i->File.empty()) {
 482       unsigned SymbolSize = CP.getSymbolSize();
 483       uint32_t NumberOfAuxRecords =
 484           (i->File.size() + SymbolSize - 1) / SymbolSize;
 485       uint32_t NumberOfAuxBytes = NumberOfAuxRecords * SymbolSize;
 486       uint32_t NumZeros = NumberOfAuxBytes - i->File.size();
 487       OS.write(i->File.data(), i->File.size());
 488       OS << num_zeros(NumZeros);
 489     }
 490     if (i->SectionDefinition)
 491       OS << binary_le(i->SectionDefinition->Length)
 492          << binary_le(i->SectionDefinition->NumberOfRelocations)
 493          << binary_le(i->SectionDefinition->NumberOfLinenumbers)
 494          << binary_le(i->SectionDefinition->CheckSum)
 495          << binary_le(static_cast<int16_t>(i->SectionDefinition->Number))
 496          << binary_le(i->SectionDefinition->Selection)
 497          << zeros(i->SectionDefinition->unused)
 498          << binary_le(static_cast<int16_t>(i->SectionDefinition->Number >> 16))
 499          << num_zeros(CP.getSymbolSize() - COFF::Symbol16Size);
 500     if (i->CLRToken)
 501       OS << binary_le(i->CLRToken->AuxType)
 502          << zeros(i->CLRToken->unused1)
 503          << binary_le(i->CLRToken->SymbolTableIndex)
 504          << zeros(i->CLRToken->unused2)
 505          << num_zeros(CP.getSymbolSize() - COFF::Symbol16Size);
 506   }
 507
 508   // Output string table.
 509   if (CP.Obj.Header.PointerToSymbolTable)
 510     OS.write(&CP.StringTable[0], CP.StringTable.size());
 511   return true;
 512 }
 513
 514 int yaml2coff(yaml::Input &YIn, raw_ostream &Out) {
 515   COFFYAML::Object Doc;
 516   YIn >> Doc;
 517   if (YIn.error()) {
 518     errs() << "yaml2obj: Failed to parse YAML file!\n";
 519     return 1;
 520   }
 521
 522   COFFParser CP(Doc);
 523   if (!CP.parse()) {
 524     errs() << "yaml2obj: Failed to parse YAML file!\n";
 525     return 1;
 526   }
 527
 528   if (!layoutOptionalHeader(CP)) {
 529     errs() << "yaml2obj: Failed to layout optional header for COFF file!\n";
 530     return 1;
 531   }
 532   if (!layoutCOFF(CP)) {
 533     errs() << "yaml2obj: Failed to layout COFF file!\n";
 534     return 1;
 535   }
 536   if (!writeCOFF(CP, Out)) {
 537     errs() << "yaml2obj: Failed to write COFF file!\n";
 538     return 1;
 539   }
 540   return 0;
 541 }