llvm/lib/ObjectYAML/COFFEmitter.cpp

   1 //===- yaml2coff - Convert YAML to a COFF object file ---------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 ///
   9 /// \file
  10 /// The COFF component of yaml2obj.
  11 ///
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/ADT/STLExtras.h"
  15 #include "llvm/ADT/StringExtras.h"
  16 #include "llvm/ADT/StringMap.h"
  17 #include "llvm/DebugInfo/CodeView/DebugStringTableSubsection.h"
  18 #include "llvm/DebugInfo/CodeView/StringsAndChecksums.h"
  19 #include "llvm/Object/COFF.h"
  20 #include "llvm/ObjectYAML/ObjectYAML.h"
  21 #include "llvm/ObjectYAML/yaml2obj.h"
  22 #include "llvm/Support/Endian.h"
  23 #include "llvm/Support/MemoryBuffer.h"
  24 #include "llvm/Support/SourceMgr.h"
  25 #include "llvm/Support/WithColor.h"
  26 #include "llvm/Support/raw_ostream.h"
  27 #include <vector>
  28
  29 using namespace llvm;
  30
  31 namespace {
  32
  33 /// This parses a yaml stream that represents a COFF object file.
  34 /// See docs/yaml2obj for the yaml scheema.
  35 struct COFFParser {
  36   COFFParser(COFFYAML::Object &Obj, yaml::ErrorHandler EH)
  37       : Obj(Obj), SectionTableStart(0), SectionTableSize(0), ErrHandler(EH) {
  38     // A COFF string table always starts with a 4 byte size field. Offsets into
  39     // it include this size, so allocate it now.
  40     StringTable.append(4, char(0));
  41   }
  42
  43   bool useBigObj() const {
  44     return static_cast<int32_t>(Obj.Sections.size()) >
  45            COFF::MaxNumberOfSections16;
  46   }
  47
  48   bool isPE() const { return Obj.OptionalHeader.hasValue(); }
  49   bool is64Bit() const {
  50     return Obj.Header.Machine == COFF::IMAGE_FILE_MACHINE_AMD64 ||
  51            Obj.Header.Machine == COFF::IMAGE_FILE_MACHINE_ARM64;
  52   }
  53
  54   uint32_t getFileAlignment() const {
  55     return Obj.OptionalHeader->Header.FileAlignment;
  56   }
  57
  58   unsigned getHeaderSize() const {
  59     return useBigObj() ? COFF::Header32Size : COFF::Header16Size;
  60   }
  61
  62   unsigned getSymbolSize() const {
  63     return useBigObj() ? COFF::Symbol32Size : COFF::Symbol16Size;
  64   }
  65
  66   bool parseSections() {
  67     for (std::vector<COFFYAML::Section>::iterator i = Obj.Sections.begin(),
  68                                                   e = Obj.Sections.end();
  69          i != e; ++i) {
  70       COFFYAML::Section &Sec = *i;
  71
  72       // If the name is less than 8 bytes, store it in place, otherwise
  73       // store it in the string table.
  74       StringRef Name = Sec.Name;
  75
  76       if (Name.size() <= COFF::NameSize) {
  77         std::copy(Name.begin(), Name.end(), Sec.Header.Name);
  78       } else {
  79         // Add string to the string table and format the index for output.
  80         unsigned Index = getStringIndex(Name);
  81         std::string str = utostr(Index);
  82         if (str.size() > 7) {
  83           ErrHandler("string table got too large");
  84           return false;
  85         }
  86         Sec.Header.Name[0] = '/';
  87         std::copy(str.begin(), str.end(), Sec.Header.Name + 1);
  88       }
  89
  90       if (Sec.Alignment) {
  91         if (Sec.Alignment > 8192) {
  92           ErrHandler("section alignment is too large");
  93           return false;
  94         }
  95         if (!isPowerOf2_32(Sec.Alignment)) {
  96           ErrHandler("section alignment is not a power of 2");
  97           return false;
  98         }
  99         Sec.Header.Characteristics |= (Log2_32(Sec.Alignment) + 1) << 20;
 100       }
 101     }
 102     return true;
 103   }
 104
 105   bool parseSymbols() {
 106     for (std::vector<COFFYAML::Symbol>::iterator i = Obj.Symbols.begin(),
 107                                                  e = Obj.Symbols.end();
 108          i != e; ++i) {
 109       COFFYAML::Symbol &Sym = *i;
 110
 111       // If the name is less than 8 bytes, store it in place, otherwise
 112       // store it in the string table.
 113       StringRef Name = Sym.Name;
 114       if (Name.size() <= COFF::NameSize) {
 115         std::copy(Name.begin(), Name.end(), Sym.Header.Name);
 116       } else {
 117         // Add string to the string table and format the index for output.
 118         unsigned Index = getStringIndex(Name);
 119         *reinterpret_cast<support::aligned_ulittle32_t *>(Sym.Header.Name + 4) =
 120             Index;
 121       }
 122
 123       Sym.Header.Type = Sym.SimpleType;
 124       Sym.Header.Type |= Sym.ComplexType << COFF::SCT_COMPLEX_TYPE_SHIFT;
 125     }
 126     return true;
 127   }
 128
 129   bool parse() {
 130     if (!parseSections())
 131       return false;
 132     if (!parseSymbols())
 133       return false;
 134     return true;
 135   }
 136
 137   unsigned getStringIndex(StringRef Str) {
 138     StringMap<unsigned>::iterator i = StringTableMap.find(Str);
 139     if (i == StringTableMap.end()) {
 140       unsigned Index = StringTable.size();
 141       StringTable.append(Str.begin(), Str.end());
 142       StringTable.push_back(0);
 143       StringTableMap[Str] = Index;
 144       return Index;
 145     }
 146     return i->second;
 147   }
 148
 149   COFFYAML::Object &Obj;
 150
 151   codeview::StringsAndChecksums StringsAndChecksums;
 152   BumpPtrAllocator Allocator;
 153   StringMap<unsigned> StringTableMap;
 154   std::string StringTable;
 155   uint32_t SectionTableStart;
 156   uint32_t SectionTableSize;
 157
 158   yaml::ErrorHandler ErrHandler;
 159 };
 160
 161 enum { DOSStubSize = 128 };
 162
 163 } // end anonymous namespace
 164
 165 // Take a CP and assign addresses and sizes to everything. Returns false if the
 166 // layout is not valid to do.
 167 static bool layoutOptionalHeader(COFFParser &CP) {
 168   if (!CP.isPE())
 169     return true;
 170   unsigned PEHeaderSize = CP.is64Bit() ? sizeof(object::pe32plus_header)
 171                                        : sizeof(object::pe32_header);
 172   CP.Obj.Header.SizeOfOptionalHeader =
 173       PEHeaderSize +
 174       sizeof(object::data_directory) * (COFF::NUM_DATA_DIRECTORIES + 1);
 175   return true;
 176 }
 177
 178 static yaml::BinaryRef
 179 toDebugS(ArrayRef<CodeViewYAML::YAMLDebugSubsection> Subsections,
 180          const codeview::StringsAndChecksums &SC, BumpPtrAllocator &Allocator) {
 181   using namespace codeview;
 182   ExitOnError Err("Error occurred writing .debug$S section");
 183   auto CVSS =
 184       Err(CodeViewYAML::toCodeViewSubsectionList(Allocator, Subsections, SC));
 185
 186   std::vector<DebugSubsectionRecordBuilder> Builders;
 187   uint32_t Size = sizeof(uint32_t);
 188   for (auto &SS : CVSS) {
 189     DebugSubsectionRecordBuilder B(SS);
 190     Size += B.calculateSerializedLength();
 191     Builders.push_back(std::move(B));
 192   }
 193   uint8_t *Buffer = Allocator.Allocate<uint8_t>(Size);
 194   MutableArrayRef<uint8_t> Output(Buffer, Size);
 195   BinaryStreamWriter Writer(Output, support::little);
 196
 197   Err(Writer.writeInteger<uint32_t>(COFF::DEBUG_SECTION_MAGIC));
 198   for (const auto &B : Builders) {
 199     Err(B.commit(Writer, CodeViewContainer::ObjectFile));
 200   }
 201   return {Output};
 202 }
 203
 204 // Take a CP and assign addresses and sizes to everything. Returns false if the
 205 // layout is not valid to do.
 206 static bool layoutCOFF(COFFParser &CP) {
 207   // The section table starts immediately after the header, including the
 208   // optional header.
 209   CP.SectionTableStart =
 210       CP.getHeaderSize() + CP.Obj.Header.SizeOfOptionalHeader;
 211   if (CP.isPE())
 212     CP.SectionTableStart += DOSStubSize + sizeof(COFF::PEMagic);
 213   CP.SectionTableSize = COFF::SectionSize * CP.Obj.Sections.size();
 214
 215   uint32_t CurrentSectionDataOffset =
 216       CP.SectionTableStart + CP.SectionTableSize;
 217
 218   for (COFFYAML::Section &S : CP.Obj.Sections) {
 219     // We support specifying exactly one of SectionData or Subsections.  So if
 220     // there is already some SectionData, then we don't need to do any of this.
 221     if (S.Name == ".debug$S" && S.SectionData.binary_size() == 0) {
 222       CodeViewYAML::initializeStringsAndChecksums(S.DebugS,
 223                                                   CP.StringsAndChecksums);
 224       if (CP.StringsAndChecksums.hasChecksums() &&
 225           CP.StringsAndChecksums.hasStrings())
 226         break;
 227     }
 228   }
 229
 230   // Assign each section data address consecutively.
 231   for (COFFYAML::Section &S : CP.Obj.Sections) {
 232     if (S.Name == ".debug$S") {
 233       if (S.SectionData.binary_size() == 0) {
 234         assert(CP.StringsAndChecksums.hasStrings() &&
 235                "Object file does not have debug string table!");
 236
 237         S.SectionData =
 238             toDebugS(S.DebugS, CP.StringsAndChecksums, CP.Allocator);
 239       }
 240     } else if (S.Name == ".debug$T") {
 241       if (S.SectionData.binary_size() == 0)
 242         S.SectionData = CodeViewYAML::toDebugT(S.DebugT, CP.Allocator, S.Name);
 243     } else if (S.Name == ".debug$P") {
 244       if (S.SectionData.binary_size() == 0)
 245         S.SectionData = CodeViewYAML::toDebugT(S.DebugP, CP.Allocator, S.Name);
 246     } else if (S.Name == ".debug$H") {
 247       if (S.DebugH.hasValue() && S.SectionData.binary_size() == 0)
 248         S.SectionData = CodeViewYAML::toDebugH(*S.DebugH, CP.Allocator);
 249     }
 250
 251     if (S.SectionData.binary_size() > 0) {
 252       CurrentSectionDataOffset = alignTo(CurrentSectionDataOffset,
 253                                          CP.isPE() ? CP.getFileAlignment() : 4);
 254       S.Header.SizeOfRawData = S.SectionData.binary_size();
 255       if (CP.isPE())
 256         S.Header.SizeOfRawData =
 257             alignTo(S.Header.SizeOfRawData, CP.getFileAlignment());
 258       S.Header.PointerToRawData = CurrentSectionDataOffset;
 259       CurrentSectionDataOffset += S.Header.SizeOfRawData;
 260       if (!S.Relocations.empty()) {
 261         S.Header.PointerToRelocations = CurrentSectionDataOffset;
 262         if (S.Header.Characteristics & COFF::IMAGE_SCN_LNK_NRELOC_OVFL) {
 263           S.Header.NumberOfRelocations = 0xffff;
 264           CurrentSectionDataOffset += COFF::RelocationSize;
 265         } else
 266           S.Header.NumberOfRelocations = S.Relocations.size();
 267         CurrentSectionDataOffset += S.Relocations.size() * COFF::RelocationSize;
 268       }
 269     } else {
 270       // Leave SizeOfRawData unaltered. For .bss sections in object files, it
 271       // carries the section size.
 272       S.Header.PointerToRawData = 0;
 273     }
 274   }
 275
 276   uint32_t SymbolTableStart = CurrentSectionDataOffset;
 277
 278   // Calculate number of symbols.
 279   uint32_t NumberOfSymbols = 0;
 280   for (std::vector<COFFYAML::Symbol>::iterator i = CP.Obj.Symbols.begin(),
 281                                                e = CP.Obj.Symbols.end();
 282        i != e; ++i) {
 283     uint32_t NumberOfAuxSymbols = 0;
 284     if (i->FunctionDefinition)
 285       NumberOfAuxSymbols += 1;
 286     if (i->bfAndefSymbol)
 287       NumberOfAuxSymbols += 1;
 288     if (i->WeakExternal)
 289       NumberOfAuxSymbols += 1;
 290     if (!i->File.empty())
 291       NumberOfAuxSymbols +=
 292           (i->File.size() + CP.getSymbolSize() - 1) / CP.getSymbolSize();
 293     if (i->SectionDefinition)
 294       NumberOfAuxSymbols += 1;
 295     if (i->CLRToken)
 296       NumberOfAuxSymbols += 1;
 297     i->Header.NumberOfAuxSymbols = NumberOfAuxSymbols;
 298     NumberOfSymbols += 1 + NumberOfAuxSymbols;
 299   }
 300
 301   // Store all the allocated start addresses in the header.
 302   CP.Obj.Header.NumberOfSections = CP.Obj.Sections.size();
 303   CP.Obj.Header.NumberOfSymbols = NumberOfSymbols;
 304   if (NumberOfSymbols > 0 || CP.StringTable.size() > 4)
 305     CP.Obj.Header.PointerToSymbolTable = SymbolTableStart;
 306   else
 307     CP.Obj.Header.PointerToSymbolTable = 0;
 308
 309   *reinterpret_cast<support::ulittle32_t *>(&CP.StringTable[0]) =
 310       CP.StringTable.size();
 311
 312   return true;
 313 }
 314
 315 template <typename value_type> struct binary_le_impl {
 316   value_type Value;
 317   binary_le_impl(value_type V) : Value(V) {}
 318 };
 319
 320 template <typename value_type>
 321 raw_ostream &operator<<(raw_ostream &OS,
 322                         const binary_le_impl<value_type> &BLE) {
 323   char Buffer[sizeof(BLE.Value)];
 324   support::endian::write<value_type, support::little, support::unaligned>(
 325       Buffer, BLE.Value);
 326   OS.write(Buffer, sizeof(BLE.Value));
 327   return OS;
 328 }
 329
 330 template <typename value_type>
 331 binary_le_impl<value_type> binary_le(value_type V) {
 332   return binary_le_impl<value_type>(V);
 333 }
 334
 335 template <size_t NumBytes> struct zeros_impl {};
 336
 337 template <size_t NumBytes>
 338 raw_ostream &operator<<(raw_ostream &OS, const zeros_impl<NumBytes> &) {
 339   char Buffer[NumBytes];
 340   memset(Buffer, 0, sizeof(Buffer));
 341   OS.write(Buffer, sizeof(Buffer));
 342   return OS;
 343 }
 344
 345 template <typename T> zeros_impl<sizeof(T)> zeros(const T &) {
 346   return zeros_impl<sizeof(T)>();
 347 }
 348
 349 template <typename T>
 350 static uint32_t initializeOptionalHeader(COFFParser &CP, uint16_t Magic,
 351                                          T Header) {
 352   memset(Header, 0, sizeof(*Header));
 353   Header->Magic = Magic;
 354   Header->SectionAlignment = CP.Obj.OptionalHeader->Header.SectionAlignment;
 355   Header->FileAlignment = CP.Obj.OptionalHeader->Header.FileAlignment;
 356   uint32_t SizeOfCode = 0, SizeOfInitializedData = 0,
 357            SizeOfUninitializedData = 0;
 358   uint32_t SizeOfHeaders = alignTo(CP.SectionTableStart + CP.SectionTableSize,
 359                                    Header->FileAlignment);
 360   uint32_t SizeOfImage = alignTo(SizeOfHeaders, Header->SectionAlignment);
 361   uint32_t BaseOfData = 0;
 362   for (const COFFYAML::Section &S : CP.Obj.Sections) {
 363     if (S.Header.Characteristics & COFF::IMAGE_SCN_CNT_CODE)
 364       SizeOfCode += S.Header.SizeOfRawData;
 365     if (S.Header.Characteristics & COFF::IMAGE_SCN_CNT_INITIALIZED_DATA)
 366       SizeOfInitializedData += S.Header.SizeOfRawData;
 367     if (S.Header.Characteristics & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA)
 368       SizeOfUninitializedData += S.Header.SizeOfRawData;
 369     if (S.Name.equals(".text"))
 370       Header->BaseOfCode = S.Header.VirtualAddress; // RVA
 371     else if (S.Name.equals(".data"))
 372       BaseOfData = S.Header.VirtualAddress; // RVA
 373     if (S.Header.VirtualAddress)
 374       SizeOfImage += alignTo(S.Header.VirtualSize, Header->SectionAlignment);
 375   }
 376   Header->SizeOfCode = SizeOfCode;
 377   Header->SizeOfInitializedData = SizeOfInitializedData;
 378   Header->SizeOfUninitializedData = SizeOfUninitializedData;
 379   Header->AddressOfEntryPoint =
 380       CP.Obj.OptionalHeader->Header.AddressOfEntryPoint; // RVA
 381   Header->ImageBase = CP.Obj.OptionalHeader->Header.ImageBase;
 382   Header->MajorOperatingSystemVersion =
 383       CP.Obj.OptionalHeader->Header.MajorOperatingSystemVersion;
 384   Header->MinorOperatingSystemVersion =
 385       CP.Obj.OptionalHeader->Header.MinorOperatingSystemVersion;
 386   Header->MajorImageVersion = CP.Obj.OptionalHeader->Header.MajorImageVersion;
 387   Header->MinorImageVersion = CP.Obj.OptionalHeader->Header.MinorImageVersion;
 388   Header->MajorSubsystemVersion =
 389       CP.Obj.OptionalHeader->Header.MajorSubsystemVersion;
 390   Header->MinorSubsystemVersion =
 391       CP.Obj.OptionalHeader->Header.MinorSubsystemVersion;
 392   Header->SizeOfImage = SizeOfImage;
 393   Header->SizeOfHeaders = SizeOfHeaders;
 394   Header->Subsystem = CP.Obj.OptionalHeader->Header.Subsystem;
 395   Header->DLLCharacteristics = CP.Obj.OptionalHeader->Header.DLLCharacteristics;
 396   Header->SizeOfStackReserve = CP.Obj.OptionalHeader->Header.SizeOfStackReserve;
 397   Header->SizeOfStackCommit = CP.Obj.OptionalHeader->Header.SizeOfStackCommit;
 398   Header->SizeOfHeapReserve = CP.Obj.OptionalHeader->Header.SizeOfHeapReserve;
 399   Header->SizeOfHeapCommit = CP.Obj.OptionalHeader->Header.SizeOfHeapCommit;
 400   Header->NumberOfRvaAndSize = COFF::NUM_DATA_DIRECTORIES + 1;
 401   return BaseOfData;
 402 }
 403
 404 static bool writeCOFF(COFFParser &CP, raw_ostream &OS) {
 405   if (CP.isPE()) {
 406     // PE files start with a DOS stub.
 407     object::dos_header DH;
 408     memset(&DH, 0, sizeof(DH));
 409
 410     // DOS EXEs start with "MZ" magic.
 411     DH.Magic[0] = 'M';
 412     DH.Magic[1] = 'Z';
 413     // Initializing the AddressOfRelocationTable is strictly optional but
 414     // mollifies certain tools which expect it to have a value greater than
 415     // 0x40.
 416     DH.AddressOfRelocationTable = sizeof(DH);
 417     // This is the address of the PE signature.
 418     DH.AddressOfNewExeHeader = DOSStubSize;
 419
 420     // Write out our DOS stub.
 421     OS.write(reinterpret_cast<char *>(&DH), sizeof(DH));
 422     // Write padding until we reach the position of where our PE signature
 423     // should live.
 424     OS.write_zeros(DOSStubSize - sizeof(DH));
 425     // Write out the PE signature.
 426     OS.write(COFF::PEMagic, sizeof(COFF::PEMagic));
 427   }
 428   if (CP.useBigObj()) {
 429     OS << binary_le(static_cast<uint16_t>(COFF::IMAGE_FILE_MACHINE_UNKNOWN))
 430        << binary_le(static_cast<uint16_t>(0xffff))
 431        << binary_le(
 432               static_cast<uint16_t>(COFF::BigObjHeader::MinBigObjectVersion))
 433        << binary_le(CP.Obj.Header.Machine)
 434        << binary_le(CP.Obj.Header.TimeDateStamp);
 435     OS.write(COFF::BigObjMagic, sizeof(COFF::BigObjMagic));
 436     OS << zeros(uint32_t(0)) << zeros(uint32_t(0)) << zeros(uint32_t(0))
 437        << zeros(uint32_t(0)) << binary_le(CP.Obj.Header.NumberOfSections)
 438        << binary_le(CP.Obj.Header.PointerToSymbolTable)
 439        << binary_le(CP.Obj.Header.NumberOfSymbols);
 440   } else {
 441     OS << binary_le(CP.Obj.Header.Machine)
 442        << binary_le(static_cast<int16_t>(CP.Obj.Header.NumberOfSections))
 443        << binary_le(CP.Obj.Header.TimeDateStamp)
 444        << binary_le(CP.Obj.Header.PointerToSymbolTable)
 445        << binary_le(CP.Obj.Header.NumberOfSymbols)
 446        << binary_le(CP.Obj.Header.SizeOfOptionalHeader)
 447        << binary_le(CP.Obj.Header.Characteristics);
 448   }
 449   if (CP.isPE()) {
 450     if (CP.is64Bit()) {
 451       object::pe32plus_header PEH;
 452       initializeOptionalHeader(CP, COFF::PE32Header::PE32_PLUS, &PEH);
 453       OS.write(reinterpret_cast<char *>(&PEH), sizeof(PEH));
 454     } else {
 455       object::pe32_header PEH;
 456       uint32_t BaseOfData =
 457           initializeOptionalHeader(CP, COFF::PE32Header::PE32, &PEH);
 458       PEH.BaseOfData = BaseOfData;
 459       OS.write(reinterpret_cast<char *>(&PEH), sizeof(PEH));
 460     }
 461     for (const Optional<COFF::DataDirectory> &DD :
 462          CP.Obj.OptionalHeader->DataDirectories) {
 463       if (!DD.hasValue()) {
 464         OS << zeros(uint32_t(0));
 465         OS << zeros(uint32_t(0));
 466       } else {
 467         OS << binary_le(DD->RelativeVirtualAddress);
 468         OS << binary_le(DD->Size);
 469       }
 470     }
 471     OS << zeros(uint32_t(0));
 472     OS << zeros(uint32_t(0));
 473   }
 474
 475   assert(OS.tell() == CP.SectionTableStart);
 476   // Output section table.
 477   for (std::vector<COFFYAML::Section>::iterator i = CP.Obj.Sections.begin(),
 478                                                 e = CP.Obj.Sections.end();
 479        i != e; ++i) {
 480     OS.write(i->Header.Name, COFF::NameSize);
 481     OS << binary_le(i->Header.VirtualSize)
 482        << binary_le(i->Header.VirtualAddress)
 483        << binary_le(i->Header.SizeOfRawData)
 484        << binary_le(i->Header.PointerToRawData)
 485        << binary_le(i->Header.PointerToRelocations)
 486        << binary_le(i->Header.PointerToLineNumbers)
 487        << binary_le(i->Header.NumberOfRelocations)
 488        << binary_le(i->Header.NumberOfLineNumbers)
 489        << binary_le(i->Header.Characteristics);
 490   }
 491   assert(OS.tell() == CP.SectionTableStart + CP.SectionTableSize);
 492
 493   unsigned CurSymbol = 0;
 494   StringMap<unsigned> SymbolTableIndexMap;
 495   for (std::vector<COFFYAML::Symbol>::iterator I = CP.Obj.Symbols.begin(),
 496                                                E = CP.Obj.Symbols.end();
 497        I != E; ++I) {
 498     SymbolTableIndexMap[I->Name] = CurSymbol;
 499     CurSymbol += 1 + I->Header.NumberOfAuxSymbols;
 500   }
 501
 502   // Output section data.
 503   for (const COFFYAML::Section &S : CP.Obj.Sections) {
 504     if (S.Header.SizeOfRawData == 0 || S.Header.PointerToRawData == 0)
 505       continue;
 506     assert(S.Header.PointerToRawData >= OS.tell());
 507     OS.write_zeros(S.Header.PointerToRawData - OS.tell());
 508     S.SectionData.writeAsBinary(OS);
 509     assert(S.Header.SizeOfRawData >= S.SectionData.binary_size());
 510     OS.write_zeros(S.Header.SizeOfRawData - S.SectionData.binary_size());
 511     if (S.Header.Characteristics & COFF::IMAGE_SCN_LNK_NRELOC_OVFL)
 512       OS << binary_le<uint32_t>(/*VirtualAddress=*/ S.Relocations.size() + 1)
 513          << binary_le<uint32_t>(/*SymbolTableIndex=*/ 0)
 514          << binary_le<uint16_t>(/*Type=*/ 0);
 515     for (const COFFYAML::Relocation &R : S.Relocations) {
 516       uint32_t SymbolTableIndex;
 517       if (R.SymbolTableIndex) {
 518         if (!R.SymbolName.empty())
 519           WithColor::error()
 520               << "Both SymbolName and SymbolTableIndex specified\n";
 521         SymbolTableIndex = *R.SymbolTableIndex;
 522       } else {
 523         SymbolTableIndex = SymbolTableIndexMap[R.SymbolName];
 524       }
 525       OS << binary_le(R.VirtualAddress) << binary_le(SymbolTableIndex)
 526          << binary_le(R.Type);
 527     }
 528   }
 529
 530   // Output symbol table.
 531
 532   for (std::vector<COFFYAML::Symbol>::const_iterator i = CP.Obj.Symbols.begin(),
 533                                                      e = CP.Obj.Symbols.end();
 534        i != e; ++i) {
 535     OS.write(i->Header.Name, COFF::NameSize);
 536     OS << binary_le(i->Header.Value);
 537     if (CP.useBigObj())
 538       OS << binary_le(i->Header.SectionNumber);
 539     else
 540       OS << binary_le(static_cast<int16_t>(i->Header.SectionNumber));
 541     OS << binary_le(i->Header.Type) << binary_le(i->Header.StorageClass)
 542        << binary_le(i->Header.NumberOfAuxSymbols);
 543
 544     if (i->FunctionDefinition) {
 545       OS << binary_le(i->FunctionDefinition->TagIndex)
 546          << binary_le(i->FunctionDefinition->TotalSize)
 547          << binary_le(i->FunctionDefinition->PointerToLinenumber)
 548          << binary_le(i->FunctionDefinition->PointerToNextFunction)
 549          << zeros(i->FunctionDefinition->unused);
 550       OS.write_zeros(CP.getSymbolSize() - COFF::Symbol16Size);
 551     }
 552     if (i->bfAndefSymbol) {
 553       OS << zeros(i->bfAndefSymbol->unused1)
 554          << binary_le(i->bfAndefSymbol->Linenumber)
 555          << zeros(i->bfAndefSymbol->unused2)
 556          << binary_le(i->bfAndefSymbol->PointerToNextFunction)
 557          << zeros(i->bfAndefSymbol->unused3);
 558       OS.write_zeros(CP.getSymbolSize() - COFF::Symbol16Size);
 559     }
 560     if (i->WeakExternal) {
 561       OS << binary_le(i->WeakExternal->TagIndex)
 562          << binary_le(i->WeakExternal->Characteristics)
 563          << zeros(i->WeakExternal->unused);
 564       OS.write_zeros(CP.getSymbolSize() - COFF::Symbol16Size);
 565     }
 566     if (!i->File.empty()) {
 567       unsigned SymbolSize = CP.getSymbolSize();
 568       uint32_t NumberOfAuxRecords =
 569           (i->File.size() + SymbolSize - 1) / SymbolSize;
 570       uint32_t NumberOfAuxBytes = NumberOfAuxRecords * SymbolSize;
 571       uint32_t NumZeros = NumberOfAuxBytes - i->File.size();
 572       OS.write(i->File.data(), i->File.size());
 573       OS.write_zeros(NumZeros);
 574     }
 575     if (i->SectionDefinition) {
 576       OS << binary_le(i->SectionDefinition->Length)
 577          << binary_le(i->SectionDefinition->NumberOfRelocations)
 578          << binary_le(i->SectionDefinition->NumberOfLinenumbers)
 579          << binary_le(i->SectionDefinition->CheckSum)
 580          << binary_le(static_cast<int16_t>(i->SectionDefinition->Number))
 581          << binary_le(i->SectionDefinition->Selection)
 582          << zeros(i->SectionDefinition->unused)
 583          << binary_le(static_cast<int16_t>(i->SectionDefinition->Number >> 16));
 584       OS.write_zeros(CP.getSymbolSize() - COFF::Symbol16Size);
 585     }
 586     if (i->CLRToken) {
 587       OS << binary_le(i->CLRToken->AuxType) << zeros(i->CLRToken->unused1)
 588          << binary_le(i->CLRToken->SymbolTableIndex)
 589          << zeros(i->CLRToken->unused2);
 590       OS.write_zeros(CP.getSymbolSize() - COFF::Symbol16Size);
 591     }
 592   }
 593
 594   // Output string table.
 595   if (CP.Obj.Header.PointerToSymbolTable)
 596     OS.write(&CP.StringTable[0], CP.StringTable.size());
 597   return true;
 598 }
 599
 600 namespace llvm {
 601 namespace yaml {
 602
 603 bool yaml2coff(llvm::COFFYAML::Object &Doc, raw_ostream &Out,
 604                ErrorHandler ErrHandler) {
 605   COFFParser CP(Doc, ErrHandler);
 606   if (!CP.parse()) {
 607     ErrHandler("failed to parse YAML file");
 608     return false;
 609   }
 610
 611   if (!layoutOptionalHeader(CP)) {
 612     ErrHandler("failed to layout optional header for COFF file");
 613     return false;
 614   }
 615
 616   if (!layoutCOFF(CP)) {
 617     ErrHandler("failed to layout COFF file");
 618     return false;
 619   }
 620   if (!writeCOFF(CP, Out)) {
 621     ErrHandler("failed to write COFF file");
 622     return false;
 623   }
 624   return true;
 625 }
 626
 627 } // namespace yaml
 628 } // namespace llvm