tools/yaml2obj/yaml2elf.cpp

   1 //===- yaml2elf - Convert YAML to a ELF 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 ELF component of yaml2obj.
  11 ///
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "yaml2obj.h"
  15 #include "llvm/ADT/ArrayRef.h"
  16 #include "llvm/BinaryFormat/ELF.h"
  17 #include "llvm/MC/StringTableBuilder.h"
  18 #include "llvm/Object/ELFObjectFile.h"
  19 #include "llvm/ObjectYAML/ELFYAML.h"
  20 #include "llvm/ADT/StringSet.h"
  21 #include "llvm/Support/EndianStream.h"
  22 #include "llvm/Support/MemoryBuffer.h"
  23 #include "llvm/Support/WithColor.h"
  24 #include "llvm/Support/YAMLTraits.h"
  25 #include "llvm/Support/raw_ostream.h"
  26
  27 using namespace llvm;
  28
  29 // This class is used to build up a contiguous binary blob while keeping
  30 // track of an offset in the output (which notionally begins at
  31 // `InitialOffset`).
  32 namespace {
  33 class ContiguousBlobAccumulator {
  34   const uint64_t InitialOffset;
  35   SmallVector<char, 128> Buf;
  36   raw_svector_ostream OS;
  37
  38   /// \returns The new offset.
  39   uint64_t padToAlignment(unsigned Align) {
  40     if (Align == 0)
  41       Align = 1;
  42     uint64_t CurrentOffset = InitialOffset + OS.tell();
  43     uint64_t AlignedOffset = alignTo(CurrentOffset, Align);
  44     OS.write_zeros(AlignedOffset - CurrentOffset);
  45     return AlignedOffset; // == CurrentOffset;
  46   }
  47
  48 public:
  49   ContiguousBlobAccumulator(uint64_t InitialOffset_)
  50       : InitialOffset(InitialOffset_), Buf(), OS(Buf) {}
  51   template <class Integer>
  52   raw_ostream &getOSAndAlignedOffset(Integer &Offset, unsigned Align) {
  53     Offset = padToAlignment(Align);
  54     return OS;
  55   }
  56   void writeBlobToStream(raw_ostream &Out) { Out << OS.str(); }
  57 };
  58 } // end anonymous namespace
  59
  60 // Used to keep track of section and symbol names, so that in the YAML file
  61 // sections and symbols can be referenced by name instead of by index.
  62 namespace {
  63 class NameToIdxMap {
  64   StringMap<unsigned> Map;
  65
  66 public:
  67   /// \Returns false if name is already present in the map.
  68   bool addName(StringRef Name, unsigned Ndx) {
  69     return Map.insert({Name, Ndx}).second;
  70   }
  71   /// \Returns false if name is not present in the map.
  72   bool lookup(StringRef Name, unsigned &Idx) const {
  73     auto I = Map.find(Name);
  74     if (I == Map.end())
  75       return false;
  76     Idx = I->getValue();
  77     return true;
  78   }
  79   /// Asserts if name is not present in the map.
  80   unsigned get(StringRef Name) const {
  81     unsigned Idx;
  82     if (lookup(Name, Idx))
  83       return Idx;
  84     assert(false && "Expected section not found in index");
  85     return 0;
  86   }
  87   unsigned size() const { return Map.size(); }
  88 };
  89 } // end anonymous namespace
  90
  91 template <class T>
  92 static size_t arrayDataSize(ArrayRef<T> A) {
  93   return A.size() * sizeof(T);
  94 }
  95
  96 template <class T>
  97 static void writeArrayData(raw_ostream &OS, ArrayRef<T> A) {
  98   OS.write((const char *)A.data(), arrayDataSize(A));
  99 }
 100
 101 template <class T>
 102 static void zero(T &Obj) {
 103   memset(&Obj, 0, sizeof(Obj));
 104 }
 105
 106 namespace {
 107 /// "Single point of truth" for the ELF file construction.
 108 /// TODO: This class still has a ways to go before it is truly a "single
 109 /// point of truth".
 110 template <class ELFT>
 111 class ELFState {
 112   typedef typename ELFT::Ehdr Elf_Ehdr;
 113   typedef typename ELFT::Phdr Elf_Phdr;
 114   typedef typename ELFT::Shdr Elf_Shdr;
 115   typedef typename ELFT::Sym Elf_Sym;
 116   typedef typename ELFT::Rel Elf_Rel;
 117   typedef typename ELFT::Rela Elf_Rela;
 118   typedef typename ELFT::Relr Elf_Relr;
 119   typedef typename ELFT::Dyn Elf_Dyn;
 120
 121   enum class SymtabType { Static, Dynamic };
 122
 123   /// The future ".strtab" section.
 124   StringTableBuilder DotStrtab{StringTableBuilder::ELF};
 125
 126   /// The future ".shstrtab" section.
 127   StringTableBuilder DotShStrtab{StringTableBuilder::ELF};
 128
 129   /// The future ".dynstr" section.
 130   StringTableBuilder DotDynstr{StringTableBuilder::ELF};
 131
 132   NameToIdxMap SN2I;
 133   NameToIdxMap SymN2I;
 134   ELFYAML::Object &Doc;
 135
 136   bool buildSectionIndex();
 137   bool buildSymbolIndex(ArrayRef<ELFYAML::Symbol> Symbols);
 138   void initELFHeader(Elf_Ehdr &Header);
 139   void initProgramHeaders(std::vector<Elf_Phdr> &PHeaders);
 140   bool initImplicitHeader(ELFState<ELFT> &State, ContiguousBlobAccumulator &CBA,
 141                           Elf_Shdr &Header, StringRef SecName,
 142                           ELFYAML::Section *YAMLSec);
 143   bool initSectionHeaders(ELFState<ELFT> &State,
 144                           std::vector<Elf_Shdr> &SHeaders,
 145                           ContiguousBlobAccumulator &CBA);
 146   void initSymtabSectionHeader(Elf_Shdr &SHeader, SymtabType STType,
 147                                ContiguousBlobAccumulator &CBA,
 148                                ELFYAML::Section *YAMLSec);
 149   void initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
 150                                StringTableBuilder &STB,
 151                                ContiguousBlobAccumulator &CBA,
 152                                ELFYAML::Section *YAMLSec);
 153   void setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
 154                               std::vector<Elf_Shdr> &SHeaders);
 155   bool writeSectionContent(Elf_Shdr &SHeader,
 156                            const ELFYAML::RawContentSection &Section,
 157                            ContiguousBlobAccumulator &CBA);
 158   bool writeSectionContent(Elf_Shdr &SHeader,
 159                            const ELFYAML::RelocationSection &Section,
 160                            ContiguousBlobAccumulator &CBA);
 161   bool writeSectionContent(Elf_Shdr &SHeader, const ELFYAML::Group &Group,
 162                            ContiguousBlobAccumulator &CBA);
 163   bool writeSectionContent(Elf_Shdr &SHeader,
 164                            const ELFYAML::SymverSection &Section,
 165                            ContiguousBlobAccumulator &CBA);
 166   bool writeSectionContent(Elf_Shdr &SHeader,
 167                            const ELFYAML::VerneedSection &Section,
 168                            ContiguousBlobAccumulator &CBA);
 169   bool writeSectionContent(Elf_Shdr &SHeader,
 170                            const ELFYAML::VerdefSection &Section,
 171                            ContiguousBlobAccumulator &CBA);
 172   bool writeSectionContent(Elf_Shdr &SHeader,
 173                            const ELFYAML::MipsABIFlags &Section,
 174                            ContiguousBlobAccumulator &CBA);
 175   bool writeSectionContent(Elf_Shdr &SHeader,
 176                            const ELFYAML::DynamicSection &Section,
 177                            ContiguousBlobAccumulator &CBA);
 178   ELFState(ELFYAML::Object &D);
 179
 180 public:
 181   static int writeELF(raw_ostream &OS, ELFYAML::Object &Doc);
 182
 183 private:
 184   void finalizeStrings();
 185 };
 186 } // end anonymous namespace
 187
 188 template <class ELFT>
 189 ELFState<ELFT>::ELFState(ELFYAML::Object &D) : Doc(D) {
 190   StringSet<> DocSections;
 191   for (std::unique_ptr<ELFYAML::Section> &D : Doc.Sections)
 192     if (!D->Name.empty())
 193       DocSections.insert(D->Name);
 194
 195   // Insert SHT_NULL section implicitly when it is not defined in YAML.
 196   if (Doc.Sections.empty() || Doc.Sections.front()->Type != ELF::SHT_NULL)
 197     Doc.Sections.insert(
 198         Doc.Sections.begin(),
 199         llvm::make_unique<ELFYAML::Section>(
 200           ELFYAML::Section::SectionKind::RawContent, /*IsImplicit=*/true));
 201
 202   std::vector<StringRef> ImplicitSections = {".symtab", ".strtab", ".shstrtab"};
 203   if (!Doc.DynamicSymbols.empty())
 204     ImplicitSections.insert(ImplicitSections.end(), {".dynsym", ".dynstr"});
 205
 206   // Insert placeholders for implicit sections that are not
 207   // defined explicitly in YAML.
 208   for (StringRef SecName : ImplicitSections) {
 209     if (DocSections.count(SecName))
 210       continue;
 211
 212     std::unique_ptr<ELFYAML::Section> Sec = llvm::make_unique<ELFYAML::Section>(
 213         ELFYAML::Section::SectionKind::RawContent, true /*IsImplicit*/);
 214     Sec->Name = SecName;
 215     Doc.Sections.push_back(std::move(Sec));
 216   }
 217 }
 218
 219 template <class ELFT>
 220 void ELFState<ELFT>::initELFHeader(Elf_Ehdr &Header) {
 221   using namespace llvm::ELF;
 222   zero(Header);
 223   Header.e_ident[EI_MAG0] = 0x7f;
 224   Header.e_ident[EI_MAG1] = 'E';
 225   Header.e_ident[EI_MAG2] = 'L';
 226   Header.e_ident[EI_MAG3] = 'F';
 227   Header.e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
 228   Header.e_ident[EI_DATA] = Doc.Header.Data;
 229   Header.e_ident[EI_VERSION] = EV_CURRENT;
 230   Header.e_ident[EI_OSABI] = Doc.Header.OSABI;
 231   Header.e_ident[EI_ABIVERSION] = Doc.Header.ABIVersion;
 232   Header.e_type = Doc.Header.Type;
 233   Header.e_machine = Doc.Header.Machine;
 234   Header.e_version = EV_CURRENT;
 235   Header.e_entry = Doc.Header.Entry;
 236   Header.e_phoff = sizeof(Header);
 237   Header.e_flags = Doc.Header.Flags;
 238   Header.e_ehsize = sizeof(Elf_Ehdr);
 239   Header.e_phentsize = sizeof(Elf_Phdr);
 240   Header.e_phnum = Doc.ProgramHeaders.size();
 241
 242   Header.e_shentsize =
 243       Doc.Header.SHEntSize ? (uint16_t)*Doc.Header.SHEntSize : sizeof(Elf_Shdr);
 244   // Immediately following the ELF header and program headers.
 245   Header.e_shoff =
 246       Doc.Header.SHOffset
 247           ? (typename ELFT::uint)(*Doc.Header.SHOffset)
 248           : sizeof(Header) + sizeof(Elf_Phdr) * Doc.ProgramHeaders.size();
 249   Header.e_shnum =
 250       Doc.Header.SHNum ? (uint16_t)*Doc.Header.SHNum : Doc.Sections.size();
 251   Header.e_shstrndx = Doc.Header.SHStrNdx ? (uint16_t)*Doc.Header.SHStrNdx
 252                                           : SN2I.get(".shstrtab");
 253 }
 254
 255 template <class ELFT>
 256 void ELFState<ELFT>::initProgramHeaders(std::vector<Elf_Phdr> &PHeaders) {
 257   for (const auto &YamlPhdr : Doc.ProgramHeaders) {
 258     Elf_Phdr Phdr;
 259     Phdr.p_type = YamlPhdr.Type;
 260     Phdr.p_flags = YamlPhdr.Flags;
 261     Phdr.p_vaddr = YamlPhdr.VAddr;
 262     Phdr.p_paddr = YamlPhdr.PAddr;
 263     PHeaders.push_back(Phdr);
 264   }
 265 }
 266
 267 static bool convertSectionIndex(NameToIdxMap &SN2I, StringRef SecName,
 268                                 StringRef IndexSrc, unsigned &IndexDest) {
 269   if (!SN2I.lookup(IndexSrc, IndexDest) && !to_integer(IndexSrc, IndexDest)) {
 270     WithColor::error() << "Unknown section referenced: '" << IndexSrc
 271                        << "' at YAML section '" << SecName << "'.\n";
 272     return false;
 273   }
 274   return true;
 275 }
 276
 277 template <class ELFT>
 278 bool ELFState<ELFT>::initImplicitHeader(ELFState<ELFT> &State,
 279                                         ContiguousBlobAccumulator &CBA,
 280                                         Elf_Shdr &Header, StringRef SecName,
 281                                         ELFYAML::Section *YAMLSec) {
 282   // Check if the header was already initialized.
 283   if (Header.sh_offset)
 284     return false;
 285
 286   if (SecName == ".symtab")
 287     State.initSymtabSectionHeader(Header, SymtabType::Static, CBA, YAMLSec);
 288   else if (SecName == ".strtab")
 289     State.initStrtabSectionHeader(Header, SecName, State.DotStrtab, CBA,
 290                                   YAMLSec);
 291   else if (SecName == ".shstrtab")
 292     State.initStrtabSectionHeader(Header, SecName, State.DotShStrtab, CBA,
 293                                   YAMLSec);
 294
 295   else if (SecName == ".dynsym")
 296     State.initSymtabSectionHeader(Header, SymtabType::Dynamic, CBA, YAMLSec);
 297   else if (SecName == ".dynstr")
 298     State.initStrtabSectionHeader(Header, SecName, State.DotDynstr, CBA,
 299                                   YAMLSec);
 300   else
 301     return false;
 302
 303   // Override the sh_offset/sh_size fields if requested.
 304   if (YAMLSec) {
 305     if (YAMLSec->ShOffset)
 306       Header.sh_offset = *YAMLSec->ShOffset;
 307     if (YAMLSec->ShSize)
 308       Header.sh_size = *YAMLSec->ShSize;
 309   }
 310
 311   return true;
 312 }
 313
 314 static StringRef dropUniqueSuffix(StringRef S) {
 315   size_t SuffixPos = S.rfind(" [");
 316   if (SuffixPos == StringRef::npos)
 317     return S;
 318   return S.substr(0, SuffixPos);
 319 }
 320
 321 template <class ELFT>
 322 bool ELFState<ELFT>::initSectionHeaders(ELFState<ELFT> &State,
 323                                         std::vector<Elf_Shdr> &SHeaders,
 324                                         ContiguousBlobAccumulator &CBA) {
 325   // Ensure SHN_UNDEF entry is present. An all-zero section header is a
 326   // valid SHN_UNDEF entry since SHT_NULL == 0.
 327   SHeaders.resize(Doc.Sections.size());
 328
 329   for (size_t I = 0; I < Doc.Sections.size(); ++I) {
 330     ELFYAML::Section *Sec = Doc.Sections[I].get();
 331     if (I == 0 && Sec->IsImplicit)
 332       continue;
 333
 334     // We have a few sections like string or symbol tables that are usually
 335     // added implicitly to the end. However, if they are explicitly specified
 336     // in the YAML, we need to write them here. This ensures the file offset
 337     // remains correct.
 338     Elf_Shdr &SHeader = SHeaders[I];
 339     if (initImplicitHeader(State, CBA, SHeader, Sec->Name,
 340                            Sec->IsImplicit ? nullptr : Sec))
 341       continue;
 342
 343     assert(Sec && "It can't be null unless it is an implicit section. But all "
 344                   "implicit sections should already have been handled above.");
 345
 346     SHeader.sh_name = DotShStrtab.getOffset(dropUniqueSuffix(Sec->Name));
 347     SHeader.sh_type = Sec->Type;
 348     if (Sec->Flags)
 349       SHeader.sh_flags = *Sec->Flags;
 350     SHeader.sh_addr = Sec->Address;
 351     SHeader.sh_addralign = Sec->AddressAlign;
 352
 353     if (!Sec->Link.empty()) {
 354       unsigned Index;
 355       if (!convertSectionIndex(SN2I, Sec->Name, Sec->Link, Index))
 356         return false;
 357       SHeader.sh_link = Index;
 358     }
 359
 360     if (I == 0) {
 361       if (auto RawSec = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
 362         // We do not write any content for special SHN_UNDEF section.
 363         if (RawSec->Size)
 364           SHeader.sh_size = *RawSec->Size;
 365         if (RawSec->Info)
 366           SHeader.sh_info = *RawSec->Info;
 367       }
 368       if (Sec->EntSize)
 369         SHeader.sh_entsize = *Sec->EntSize;
 370     } else if (auto S = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
 371       if (!writeSectionContent(SHeader, *S, CBA))
 372         return false;
 373     } else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec)) {
 374       if (!writeSectionContent(SHeader, *S, CBA))
 375         return false;
 376     } else if (auto S = dyn_cast<ELFYAML::Group>(Sec)) {
 377       if (!writeSectionContent(SHeader, *S, CBA))
 378         return false;
 379     } else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec)) {
 380       if (!writeSectionContent(SHeader, *S, CBA))
 381         return false;
 382     } else if (auto S = dyn_cast<ELFYAML::NoBitsSection>(Sec)) {
 383       SHeader.sh_entsize = 0;
 384       SHeader.sh_size = S->Size;
 385       // SHT_NOBITS section does not have content
 386       // so just to setup the section offset.
 387       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 388     } else if (auto S = dyn_cast<ELFYAML::DynamicSection>(Sec)) {
 389       if (!writeSectionContent(SHeader, *S, CBA))
 390         return false;
 391     } else if (auto S = dyn_cast<ELFYAML::SymverSection>(Sec)) {
 392       if (!writeSectionContent(SHeader, *S, CBA))
 393         return false;
 394     } else if (auto S = dyn_cast<ELFYAML::VerneedSection>(Sec)) {
 395       if (!writeSectionContent(SHeader, *S, CBA))
 396         return false;
 397     } else if (auto S = dyn_cast<ELFYAML::VerdefSection>(Sec)) {
 398       if (!writeSectionContent(SHeader, *S, CBA))
 399         return false;
 400     } else
 401       llvm_unreachable("Unknown section type");
 402
 403     // Override the sh_offset/sh_size fields if requested.
 404     if (Sec) {
 405       if (Sec->ShOffset)
 406         SHeader.sh_offset = *Sec->ShOffset;
 407       if (Sec->ShSize)
 408         SHeader.sh_size = *Sec->ShSize;
 409     }
 410   }
 411
 412   return true;
 413 }
 414
 415 static size_t findFirstNonGlobal(ArrayRef<ELFYAML::Symbol> Symbols) {
 416   for (size_t I = 0; I < Symbols.size(); ++I)
 417     if (Symbols[I].Binding.value != ELF::STB_LOCAL)
 418       return I;
 419   return Symbols.size();
 420 }
 421
 422 static uint64_t writeRawSectionData(raw_ostream &OS,
 423                                     const ELFYAML::RawContentSection &RawSec) {
 424   size_t ContentSize = 0;
 425   if (RawSec.Content) {
 426     RawSec.Content->writeAsBinary(OS);
 427     ContentSize = RawSec.Content->binary_size();
 428   }
 429
 430   if (!RawSec.Size)
 431     return ContentSize;
 432
 433   OS.write_zeros(*RawSec.Size - ContentSize);
 434   return *RawSec.Size;
 435 }
 436
 437 template <class ELFT>
 438 static std::vector<typename ELFT::Sym>
 439 toELFSymbols(NameToIdxMap &SN2I, ArrayRef<ELFYAML::Symbol> Symbols,
 440              const StringTableBuilder &Strtab) {
 441   using Elf_Sym = typename ELFT::Sym;
 442
 443   std::vector<Elf_Sym> Ret;
 444   Ret.resize(Symbols.size() + 1);
 445
 446   size_t I = 0;
 447   for (const auto &Sym : Symbols) {
 448     Elf_Sym &Symbol = Ret[++I];
 449
 450     // If NameIndex, which contains the name offset, is explicitly specified, we
 451     // use it. This is useful for preparing broken objects. Otherwise, we add
 452     // the specified Name to the string table builder to get its offset.
 453     if (Sym.NameIndex)
 454       Symbol.st_name = *Sym.NameIndex;
 455     else if (!Sym.Name.empty())
 456       Symbol.st_name = Strtab.getOffset(dropUniqueSuffix(Sym.Name));
 457
 458     Symbol.setBindingAndType(Sym.Binding, Sym.Type);
 459     if (!Sym.Section.empty()) {
 460       unsigned Index;
 461       if (!SN2I.lookup(Sym.Section, Index)) {
 462         WithColor::error() << "Unknown section referenced: '" << Sym.Section
 463                            << "' by YAML symbol " << Sym.Name << ".\n";
 464         exit(1);
 465       }
 466       Symbol.st_shndx = Index;
 467     } else if (Sym.Index) {
 468       Symbol.st_shndx = *Sym.Index;
 469     }
 470     // else Symbol.st_shndex == SHN_UNDEF (== 0), since it was zero'd earlier.
 471     Symbol.st_value = Sym.Value;
 472     Symbol.st_other = Sym.Other;
 473     Symbol.st_size = Sym.Size;
 474   }
 475
 476   return Ret;
 477 }
 478
 479 template <class ELFT>
 480 void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
 481                                              SymtabType STType,
 482                                              ContiguousBlobAccumulator &CBA,
 483                                              ELFYAML::Section *YAMLSec) {
 484
 485   bool IsStatic = STType == SymtabType::Static;
 486   const auto &Symbols = IsStatic ? Doc.Symbols : Doc.DynamicSymbols;
 487
 488   ELFYAML::RawContentSection *RawSec =
 489       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
 490   if (RawSec && !Symbols.empty() && (RawSec->Content || RawSec->Size)) {
 491     if (RawSec->Content)
 492       WithColor::error() << "Cannot specify both `Content` and " +
 493                                 (IsStatic ? Twine("`Symbols`")
 494                                           : Twine("`DynamicSymbols`")) +
 495                                 " for symbol table section '"
 496                          << RawSec->Name << "'.\n";
 497     if (RawSec->Size)
 498       WithColor::error() << "Cannot specify both `Size` and " +
 499                                 (IsStatic ? Twine("`Symbols`")
 500                                           : Twine("`DynamicSymbols`")) +
 501                                 " for symbol table section '"
 502                          << RawSec->Name << "'.\n";
 503     exit(1);
 504   }
 505
 506   zero(SHeader);
 507   SHeader.sh_name = DotShStrtab.getOffset(IsStatic ? ".symtab" : ".dynsym");
 508
 509   if (YAMLSec)
 510     SHeader.sh_type = YAMLSec->Type;
 511   else
 512     SHeader.sh_type = IsStatic ? ELF::SHT_SYMTAB : ELF::SHT_DYNSYM;
 513
 514   if (RawSec && !RawSec->Link.empty()) {
 515     // If the Link field is explicitly defined in the document,
 516     // we should use it.
 517     unsigned Index;
 518     if (!convertSectionIndex(SN2I, RawSec->Name, RawSec->Link, Index))
 519       return;
 520     SHeader.sh_link = Index;
 521   } else {
 522     // When we describe the .dynsym section in the document explicitly, it is
 523     // allowed to omit the "DynamicSymbols" tag. In this case .dynstr is not
 524     // added implicitly and we should be able to leave the Link zeroed if
 525     // .dynstr is not defined.
 526     unsigned Link = 0;
 527     if (IsStatic)
 528       Link = SN2I.get(".strtab");
 529     else
 530       SN2I.lookup(".dynstr", Link);
 531     SHeader.sh_link = Link;
 532   }
 533
 534   if (YAMLSec && YAMLSec->Flags)
 535     SHeader.sh_flags = *YAMLSec->Flags;
 536   else if (!IsStatic)
 537     SHeader.sh_flags = ELF::SHF_ALLOC;
 538
 539   // If the symbol table section is explicitly described in the YAML
 540   // then we should set the fields requested.
 541   SHeader.sh_info = (RawSec && RawSec->Info) ? (unsigned)(*RawSec->Info)
 542                                              : findFirstNonGlobal(Symbols) + 1;
 543   SHeader.sh_entsize = (YAMLSec && YAMLSec->EntSize)
 544                            ? (uint64_t)(*YAMLSec->EntSize)
 545                            : sizeof(Elf_Sym);
 546   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 8;
 547   SHeader.sh_addr = YAMLSec ? (uint64_t)YAMLSec->Address : 0;
 548
 549   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 550   if (RawSec && (RawSec->Content || RawSec->Size)) {
 551     assert(Symbols.empty());
 552     SHeader.sh_size = writeRawSectionData(OS, *RawSec);
 553     return;
 554   }
 555
 556   std::vector<Elf_Sym> Syms =
 557       toELFSymbols<ELFT>(SN2I, Symbols, IsStatic ? DotStrtab : DotDynstr);
 558   writeArrayData(OS, makeArrayRef(Syms));
 559   SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
 560 }
 561
 562 template <class ELFT>
 563 void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
 564                                              StringTableBuilder &STB,
 565                                              ContiguousBlobAccumulator &CBA,
 566                                              ELFYAML::Section *YAMLSec) {
 567   zero(SHeader);
 568   SHeader.sh_name = DotShStrtab.getOffset(Name);
 569   SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_STRTAB;
 570   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
 571
 572   ELFYAML::RawContentSection *RawSec =
 573       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
 574
 575   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 576   if (RawSec && (RawSec->Content || RawSec->Size)) {
 577     SHeader.sh_size = writeRawSectionData(OS, *RawSec);
 578   } else {
 579     STB.write(OS);
 580     SHeader.sh_size = STB.getSize();
 581   }
 582
 583   if (YAMLSec && YAMLSec->EntSize)
 584     SHeader.sh_entsize = *YAMLSec->EntSize;
 585
 586   if (RawSec && RawSec->Info)
 587     SHeader.sh_info = *RawSec->Info;
 588
 589   if (YAMLSec && YAMLSec->Flags)
 590     SHeader.sh_flags = *YAMLSec->Flags;
 591   else if (Name == ".dynstr")
 592     SHeader.sh_flags = ELF::SHF_ALLOC;
 593
 594   // If the section is explicitly described in the YAML
 595   // then we want to use its section address.
 596   if (YAMLSec)
 597     SHeader.sh_addr = YAMLSec->Address;
 598 }
 599
 600 template <class ELFT>
 601 void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
 602                                             std::vector<Elf_Shdr> &SHeaders) {
 603   uint32_t PhdrIdx = 0;
 604   for (auto &YamlPhdr : Doc.ProgramHeaders) {
 605     Elf_Phdr &PHeader = PHeaders[PhdrIdx++];
 606
 607     std::vector<Elf_Shdr *> Sections;
 608     for (const ELFYAML::SectionName &SecName : YamlPhdr.Sections) {
 609       unsigned Index;
 610       if (!SN2I.lookup(SecName.Section, Index)) {
 611         WithColor::error() << "Unknown section referenced: '" << SecName.Section
 612                            << "' by program header.\n";
 613         exit(1);
 614       }
 615       Sections.push_back(&SHeaders[Index]);
 616     }
 617
 618     if (YamlPhdr.Offset) {
 619       PHeader.p_offset = *YamlPhdr.Offset;
 620     } else {
 621       if (YamlPhdr.Sections.size())
 622         PHeader.p_offset = UINT32_MAX;
 623       else
 624         PHeader.p_offset = 0;
 625
 626       // Find the minimum offset for the program header.
 627       for (Elf_Shdr *SHeader : Sections)
 628         PHeader.p_offset = std::min(PHeader.p_offset, SHeader->sh_offset);
 629     }
 630
 631     // Find the maximum offset of the end of a section in order to set p_filesz,
 632     // if not set explicitly.
 633     if (YamlPhdr.FileSize) {
 634       PHeader.p_filesz = *YamlPhdr.FileSize;
 635     } else {
 636       PHeader.p_filesz = 0;
 637       for (Elf_Shdr *SHeader : Sections) {
 638         uint64_t EndOfSection;
 639         if (SHeader->sh_type == llvm::ELF::SHT_NOBITS)
 640           EndOfSection = SHeader->sh_offset;
 641         else
 642           EndOfSection = SHeader->sh_offset + SHeader->sh_size;
 643         uint64_t EndOfSegment = PHeader.p_offset + PHeader.p_filesz;
 644         EndOfSegment = std::max(EndOfSegment, EndOfSection);
 645         PHeader.p_filesz = EndOfSegment - PHeader.p_offset;
 646       }
 647     }
 648
 649     // If not set explicitly, find the memory size by adding the size of
 650     // sections at the end of the segment. These should be empty (size of zero)
 651     // and NOBITS sections.
 652     if (YamlPhdr.MemSize) {
 653       PHeader.p_memsz = *YamlPhdr.MemSize;
 654     } else {
 655       PHeader.p_memsz = PHeader.p_filesz;
 656       for (Elf_Shdr *SHeader : Sections)
 657         if (SHeader->sh_offset == PHeader.p_offset + PHeader.p_filesz)
 658           PHeader.p_memsz += SHeader->sh_size;
 659     }
 660
 661     // Set the alignment of the segment to be the same as the maximum alignment
 662     // of the sections with the same offset so that by default the segment
 663     // has a valid and sensible alignment.
 664     if (YamlPhdr.Align) {
 665       PHeader.p_align = *YamlPhdr.Align;
 666     } else {
 667       PHeader.p_align = 1;
 668       for (Elf_Shdr *SHeader : Sections)
 669         if (SHeader->sh_offset == PHeader.p_offset)
 670           PHeader.p_align = std::max(PHeader.p_align, SHeader->sh_addralign);
 671     }
 672   }
 673 }
 674
 675 template <class ELFT>
 676 bool ELFState<ELFT>::writeSectionContent(
 677     Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section,
 678     ContiguousBlobAccumulator &CBA) {
 679   raw_ostream &OS =
 680       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 681   SHeader.sh_size = writeRawSectionData(OS, Section);
 682
 683   if (Section.EntSize)
 684     SHeader.sh_entsize = *Section.EntSize;
 685   else if (Section.Type == llvm::ELF::SHT_RELR)
 686     SHeader.sh_entsize = sizeof(Elf_Relr);
 687   else
 688     SHeader.sh_entsize = 0;
 689
 690   if (Section.Info)
 691     SHeader.sh_info = *Section.Info;
 692
 693   return true;
 694 }
 695
 696 static bool isMips64EL(const ELFYAML::Object &Doc) {
 697   return Doc.Header.Machine == ELFYAML::ELF_EM(llvm::ELF::EM_MIPS) &&
 698          Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64) &&
 699          Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
 700 }
 701
 702 template <class ELFT>
 703 bool
 704 ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 705                                     const ELFYAML::RelocationSection &Section,
 706                                     ContiguousBlobAccumulator &CBA) {
 707   assert((Section.Type == llvm::ELF::SHT_REL ||
 708           Section.Type == llvm::ELF::SHT_RELA) &&
 709          "Section type is not SHT_REL nor SHT_RELA");
 710
 711   bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
 712   SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
 713   SHeader.sh_size = SHeader.sh_entsize * Section.Relocations.size();
 714
 715   // For relocation section set link to .symtab by default.
 716   if (Section.Link.empty())
 717     SHeader.sh_link = SN2I.get(".symtab");
 718
 719   unsigned Index = 0;
 720   if (!Section.RelocatableSec.empty() &&
 721       !convertSectionIndex(SN2I, Section.Name, Section.RelocatableSec, Index))
 722     return false;
 723   SHeader.sh_info = Index;
 724
 725   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 726
 727   for (const auto &Rel : Section.Relocations) {
 728     unsigned SymIdx = 0;
 729     // If a relocation references a symbol, try to look one up in the symbol
 730     // table. If it is not there, treat the value as a symbol index.
 731     if (Rel.Symbol && !SymN2I.lookup(*Rel.Symbol, SymIdx) &&
 732         !to_integer(*Rel.Symbol, SymIdx)) {
 733       WithColor::error() << "Unknown symbol referenced: '" << *Rel.Symbol
 734                          << "' at YAML section '" << Section.Name << "'.\n";
 735       return false;
 736     }
 737
 738     if (IsRela) {
 739       Elf_Rela REntry;
 740       zero(REntry);
 741       REntry.r_offset = Rel.Offset;
 742       REntry.r_addend = Rel.Addend;
 743       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
 744       OS.write((const char *)&REntry, sizeof(REntry));
 745     } else {
 746       Elf_Rel REntry;
 747       zero(REntry);
 748       REntry.r_offset = Rel.Offset;
 749       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
 750       OS.write((const char *)&REntry, sizeof(REntry));
 751     }
 752   }
 753   return true;
 754 }
 755
 756 template <class ELFT>
 757 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 758                                          const ELFYAML::Group &Section,
 759                                          ContiguousBlobAccumulator &CBA) {
 760   assert(Section.Type == llvm::ELF::SHT_GROUP &&
 761          "Section type is not SHT_GROUP");
 762
 763   SHeader.sh_entsize = 4;
 764   SHeader.sh_size = SHeader.sh_entsize * Section.Members.size();
 765
 766   unsigned SymIdx;
 767   if (!SymN2I.lookup(Section.Signature, SymIdx) &&
 768       !to_integer(Section.Signature, SymIdx)) {
 769     WithColor::error() << "Unknown symbol referenced: '" << Section.Signature
 770                        << "' at YAML section '" << Section.Name << "'.\n";
 771     return false;
 772   }
 773   SHeader.sh_info = SymIdx;
 774
 775   raw_ostream &OS =
 776       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 777
 778   for (const ELFYAML::SectionOrType &Member : Section.Members) {
 779     unsigned int SectionIndex = 0;
 780     if (Member.sectionNameOrType == "GRP_COMDAT")
 781       SectionIndex = llvm::ELF::GRP_COMDAT;
 782     else if (!convertSectionIndex(SN2I, Section.Name, Member.sectionNameOrType,
 783                                   SectionIndex))
 784       return false;
 785     support::endian::write<uint32_t>(OS, SectionIndex, ELFT::TargetEndianness);
 786   }
 787   return true;
 788 }
 789
 790 template <class ELFT>
 791 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 792                                          const ELFYAML::SymverSection &Section,
 793                                          ContiguousBlobAccumulator &CBA) {
 794   raw_ostream &OS =
 795       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 796   for (uint16_t Version : Section.Entries)
 797     support::endian::write<uint16_t>(OS, Version, ELFT::TargetEndianness);
 798
 799   SHeader.sh_entsize = Section.EntSize ? (uint64_t)*Section.EntSize : 2;
 800   SHeader.sh_size = Section.Entries.size() * SHeader.sh_entsize;
 801   return true;
 802 }
 803
 804 template <class ELFT>
 805 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 806                                          const ELFYAML::VerdefSection &Section,
 807                                          ContiguousBlobAccumulator &CBA) {
 808   typedef typename ELFT::Verdef Elf_Verdef;
 809   typedef typename ELFT::Verdaux Elf_Verdaux;
 810   raw_ostream &OS =
 811       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 812
 813   uint64_t AuxCnt = 0;
 814   for (size_t I = 0; I < Section.Entries.size(); ++I) {
 815     const ELFYAML::VerdefEntry &E = Section.Entries[I];
 816
 817     Elf_Verdef VerDef;
 818     VerDef.vd_version = E.Version;
 819     VerDef.vd_flags = E.Flags;
 820     VerDef.vd_ndx = E.VersionNdx;
 821     VerDef.vd_hash = E.Hash;
 822     VerDef.vd_aux = sizeof(Elf_Verdef);
 823     VerDef.vd_cnt = E.VerNames.size();
 824     if (I == Section.Entries.size() - 1)
 825       VerDef.vd_next = 0;
 826     else
 827       VerDef.vd_next =
 828           sizeof(Elf_Verdef) + E.VerNames.size() * sizeof(Elf_Verdaux);
 829     OS.write((const char *)&VerDef, sizeof(Elf_Verdef));
 830
 831     for (size_t J = 0; J < E.VerNames.size(); ++J, ++AuxCnt) {
 832       Elf_Verdaux VernAux;
 833       VernAux.vda_name = DotDynstr.getOffset(E.VerNames[J]);
 834       if (J == E.VerNames.size() - 1)
 835         VernAux.vda_next = 0;
 836       else
 837         VernAux.vda_next = sizeof(Elf_Verdaux);
 838       OS.write((const char *)&VernAux, sizeof(Elf_Verdaux));
 839     }
 840   }
 841
 842   SHeader.sh_size = Section.Entries.size() * sizeof(Elf_Verdef) +
 843                     AuxCnt * sizeof(Elf_Verdaux);
 844   SHeader.sh_info = Section.Info;
 845
 846   return true;
 847 }
 848
 849 template <class ELFT>
 850 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 851                                          const ELFYAML::VerneedSection &Section,
 852                                          ContiguousBlobAccumulator &CBA) {
 853   typedef typename ELFT::Verneed Elf_Verneed;
 854   typedef typename ELFT::Vernaux Elf_Vernaux;
 855
 856   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 857
 858   uint64_t AuxCnt = 0;
 859   for (size_t I = 0; I < Section.VerneedV.size(); ++I) {
 860     const ELFYAML::VerneedEntry &VE = Section.VerneedV[I];
 861
 862     Elf_Verneed VerNeed;
 863     VerNeed.vn_version = VE.Version;
 864     VerNeed.vn_file = DotDynstr.getOffset(VE.File);
 865     if (I == Section.VerneedV.size() - 1)
 866       VerNeed.vn_next = 0;
 867     else
 868       VerNeed.vn_next =
 869           sizeof(Elf_Verneed) + VE.AuxV.size() * sizeof(Elf_Vernaux);
 870     VerNeed.vn_cnt = VE.AuxV.size();
 871     VerNeed.vn_aux = sizeof(Elf_Verneed);
 872     OS.write((const char *)&VerNeed, sizeof(Elf_Verneed));
 873
 874     for (size_t J = 0; J < VE.AuxV.size(); ++J, ++AuxCnt) {
 875       const ELFYAML::VernauxEntry &VAuxE = VE.AuxV[J];
 876
 877       Elf_Vernaux VernAux;
 878       VernAux.vna_hash = VAuxE.Hash;
 879       VernAux.vna_flags = VAuxE.Flags;
 880       VernAux.vna_other = VAuxE.Other;
 881       VernAux.vna_name = DotDynstr.getOffset(VAuxE.Name);
 882       if (J == VE.AuxV.size() - 1)
 883         VernAux.vna_next = 0;
 884       else
 885         VernAux.vna_next = sizeof(Elf_Vernaux);
 886       OS.write((const char *)&VernAux, sizeof(Elf_Vernaux));
 887     }
 888   }
 889
 890   SHeader.sh_size = Section.VerneedV.size() * sizeof(Elf_Verneed) +
 891                     AuxCnt * sizeof(Elf_Vernaux);
 892   SHeader.sh_info = Section.Info;
 893
 894   return true;
 895 }
 896
 897 template <class ELFT>
 898 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 899                                          const ELFYAML::MipsABIFlags &Section,
 900                                          ContiguousBlobAccumulator &CBA) {
 901   assert(Section.Type == llvm::ELF::SHT_MIPS_ABIFLAGS &&
 902          "Section type is not SHT_MIPS_ABIFLAGS");
 903
 904   object::Elf_Mips_ABIFlags<ELFT> Flags;
 905   zero(Flags);
 906   SHeader.sh_entsize = sizeof(Flags);
 907   SHeader.sh_size = SHeader.sh_entsize;
 908
 909   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 910   Flags.version = Section.Version;
 911   Flags.isa_level = Section.ISALevel;
 912   Flags.isa_rev = Section.ISARevision;
 913   Flags.gpr_size = Section.GPRSize;
 914   Flags.cpr1_size = Section.CPR1Size;
 915   Flags.cpr2_size = Section.CPR2Size;
 916   Flags.fp_abi = Section.FpABI;
 917   Flags.isa_ext = Section.ISAExtension;
 918   Flags.ases = Section.ASEs;
 919   Flags.flags1 = Section.Flags1;
 920   Flags.flags2 = Section.Flags2;
 921   OS.write((const char *)&Flags, sizeof(Flags));
 922
 923   return true;
 924 }
 925
 926 template <class ELFT>
 927 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 928                                          const ELFYAML::DynamicSection &Section,
 929                                          ContiguousBlobAccumulator &CBA) {
 930   typedef typename ELFT::uint uintX_t;
 931
 932   assert(Section.Type == llvm::ELF::SHT_DYNAMIC &&
 933          "Section type is not SHT_DYNAMIC");
 934
 935   if (!Section.Entries.empty() && Section.Content) {
 936     WithColor::error()
 937         << "Cannot specify both raw content and explicit entries "
 938            "for dynamic section '"
 939         << Section.Name << "'.\n";
 940     return false;
 941   }
 942
 943   if (Section.Content)
 944     SHeader.sh_size = Section.Content->binary_size();
 945   else
 946     SHeader.sh_size = 2 * sizeof(uintX_t) * Section.Entries.size();
 947   if (Section.EntSize)
 948     SHeader.sh_entsize = *Section.EntSize;
 949   else
 950     SHeader.sh_entsize = sizeof(Elf_Dyn);
 951
 952   raw_ostream &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 953   for (const ELFYAML::DynamicEntry &DE : Section.Entries) {
 954     support::endian::write<uintX_t>(OS, DE.Tag, ELFT::TargetEndianness);
 955     support::endian::write<uintX_t>(OS, DE.Val, ELFT::TargetEndianness);
 956   }
 957   if (Section.Content)
 958     Section.Content->writeAsBinary(OS);
 959
 960   return true;
 961 }
 962
 963 template <class ELFT> bool ELFState<ELFT>::buildSectionIndex() {
 964   for (unsigned I = 0, E = Doc.Sections.size(); I != E; ++I) {
 965     StringRef Name = Doc.Sections[I]->Name;
 966     if (Name.empty())
 967       continue;
 968
 969     DotShStrtab.add(dropUniqueSuffix(Name));
 970     if (!SN2I.addName(Name, I)) {
 971       WithColor::error() << "Repeated section name: '" << Name
 972                          << "' at YAML section number " << I << ".\n";
 973       return false;
 974     }
 975   }
 976
 977   DotShStrtab.finalize();
 978   return true;
 979 }
 980
 981 template <class ELFT>
 982 bool ELFState<ELFT>::buildSymbolIndex(ArrayRef<ELFYAML::Symbol> Symbols) {
 983   bool GlobalSymbolSeen = false;
 984   std::size_t I = 0;
 985   for (const auto &Sym : Symbols) {
 986     ++I;
 987
 988     StringRef Name = Sym.Name;
 989     if (Sym.Binding.value == ELF::STB_LOCAL && GlobalSymbolSeen) {
 990       WithColor::error() << "Local symbol '" + Name +
 991                                 "' after global in Symbols list.\n";
 992       return false;
 993     }
 994     if (Sym.Binding.value != ELF::STB_LOCAL)
 995       GlobalSymbolSeen = true;
 996
 997     if (!Name.empty() && !SymN2I.addName(Name, I)) {
 998       WithColor::error() << "Repeated symbol name: '" << Name << "'.\n";
 999       return false;
1000     }
1001   }
1002   return true;
1003 }
1004
1005 template <class ELFT> void ELFState<ELFT>::finalizeStrings() {
1006   // Add the regular symbol names to .strtab section.
1007   for (const ELFYAML::Symbol &Sym : Doc.Symbols)
1008     DotStrtab.add(dropUniqueSuffix(Sym.Name));
1009   DotStrtab.finalize();
1010
1011   // Add the dynamic symbol names to .dynstr section.
1012   for (const ELFYAML::Symbol &Sym : Doc.DynamicSymbols)
1013     DotDynstr.add(dropUniqueSuffix(Sym.Name));
1014
1015   // SHT_GNU_verdef and SHT_GNU_verneed sections might also
1016   // add strings to .dynstr section.
1017   for (const std::unique_ptr<ELFYAML::Section> &Sec : Doc.Sections) {
1018     if (auto VerNeed = dyn_cast<ELFYAML::VerneedSection>(Sec.get())) {
1019       for (const ELFYAML::VerneedEntry &VE : VerNeed->VerneedV) {
1020         DotDynstr.add(VE.File);
1021         for (const ELFYAML::VernauxEntry &Aux : VE.AuxV)
1022           DotDynstr.add(Aux.Name);
1023       }
1024     } else if (auto VerDef = dyn_cast<ELFYAML::VerdefSection>(Sec.get())) {
1025       for (const ELFYAML::VerdefEntry &E : VerDef->Entries)
1026         for (StringRef Name : E.VerNames)
1027           DotDynstr.add(Name);
1028     }
1029   }
1030
1031   DotDynstr.finalize();
1032 }
1033
1034 template <class ELFT>
1035 int ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc) {
1036   ELFState<ELFT> State(Doc);
1037
1038   // Finalize .strtab and .dynstr sections. We do that early because want to
1039   // finalize the string table builders before writing the content of the
1040   // sections that might want to use them.
1041   State.finalizeStrings();
1042
1043   if (!State.buildSectionIndex())
1044     return 1;
1045
1046   if (!State.buildSymbolIndex(Doc.Symbols))
1047     return 1;
1048
1049   Elf_Ehdr Header;
1050   State.initELFHeader(Header);
1051
1052   // TODO: Flesh out section header support.
1053
1054   std::vector<Elf_Phdr> PHeaders;
1055   State.initProgramHeaders(PHeaders);
1056
1057   // XXX: This offset is tightly coupled with the order that we write
1058   // things to `OS`.
1059   const size_t SectionContentBeginOffset = Header.e_ehsize +
1060                                            Header.e_phentsize * Header.e_phnum +
1061                                            Header.e_shentsize * Header.e_shnum;
1062   ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
1063
1064   std::vector<Elf_Shdr> SHeaders;
1065   if (!State.initSectionHeaders(State, SHeaders, CBA))
1066     return 1;
1067
1068   // Now we can decide segment offsets
1069   State.setProgramHeaderLayout(PHeaders, SHeaders);
1070
1071   OS.write((const char *)&Header, sizeof(Header));
1072   writeArrayData(OS, makeArrayRef(PHeaders));
1073   writeArrayData(OS, makeArrayRef(SHeaders));
1074   CBA.writeBlobToStream(OS);
1075   return 0;
1076 }
1077
1078 int yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out) {
1079   bool IsLE = Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
1080   bool Is64Bit = Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
1081   if (Is64Bit) {
1082     if (IsLE)
1083       return ELFState<object::ELF64LE>::writeELF(Out, Doc);
1084     return ELFState<object::ELF64BE>::writeELF(Out, Doc);
1085   }
1086   if (IsLE)
1087     return ELFState<object::ELF32LE>::writeELF(Out, Doc);
1088   return ELFState<object::ELF32BE>::writeELF(Out, Doc);
1089 }