lib/ObjectYAML/ELFEmitter.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 "llvm/ADT/ArrayRef.h"
  15 #include "llvm/ADT/StringSet.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/ObjectYAML/yaml2obj.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
  59 // Used to keep track of section and symbol names, so that in the YAML file
  60 // sections and symbols can be referenced by name instead of by index.
  61 class NameToIdxMap {
  62   StringMap<unsigned> Map;
  63
  64 public:
  65   /// \Returns false if name is already present in the map.
  66   bool addName(StringRef Name, unsigned Ndx) {
  67     return Map.insert({Name, Ndx}).second;
  68   }
  69   /// \Returns false if name is not present in the map.
  70   bool lookup(StringRef Name, unsigned &Idx) const {
  71     auto I = Map.find(Name);
  72     if (I == Map.end())
  73       return false;
  74     Idx = I->getValue();
  75     return true;
  76   }
  77   /// Asserts if name is not present in the map.
  78   unsigned get(StringRef Name) const {
  79     unsigned Idx;
  80     if (lookup(Name, Idx))
  81       return Idx;
  82     assert(false && "Expected section not found in index");
  83     return 0;
  84   }
  85   unsigned size() const { return Map.size(); }
  86 };
  87
  88 /// "Single point of truth" for the ELF file construction.
  89 /// TODO: This class still has a ways to go before it is truly a "single
  90 /// point of truth".
  91 template <class ELFT> class ELFState {
  92   typedef typename ELFT::Ehdr Elf_Ehdr;
  93   typedef typename ELFT::Phdr Elf_Phdr;
  94   typedef typename ELFT::Shdr Elf_Shdr;
  95   typedef typename ELFT::Sym Elf_Sym;
  96   typedef typename ELFT::Rel Elf_Rel;
  97   typedef typename ELFT::Rela Elf_Rela;
  98   typedef typename ELFT::Relr Elf_Relr;
  99   typedef typename ELFT::Dyn Elf_Dyn;
 100
 101   enum class SymtabType { Static, Dynamic };
 102
 103   /// The future ".strtab" section.
 104   StringTableBuilder DotStrtab{StringTableBuilder::ELF};
 105
 106   /// The future ".shstrtab" section.
 107   StringTableBuilder DotShStrtab{StringTableBuilder::ELF};
 108
 109   /// The future ".dynstr" section.
 110   StringTableBuilder DotDynstr{StringTableBuilder::ELF};
 111
 112   NameToIdxMap SN2I;
 113   NameToIdxMap SymN2I;
 114   NameToIdxMap DynSymN2I;
 115   ELFYAML::Object &Doc;
 116
 117   bool buildSectionIndex();
 118   bool buildSymbolIndexes();
 119   void initProgramHeaders(std::vector<Elf_Phdr> &PHeaders);
 120   bool initImplicitHeader(ContiguousBlobAccumulator &CBA, Elf_Shdr &Header,
 121                           StringRef SecName, ELFYAML::Section *YAMLSec);
 122   bool initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
 123                           ContiguousBlobAccumulator &CBA);
 124   void initSymtabSectionHeader(Elf_Shdr &SHeader, SymtabType STType,
 125                                ContiguousBlobAccumulator &CBA,
 126                                ELFYAML::Section *YAMLSec);
 127   void initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
 128                                StringTableBuilder &STB,
 129                                ContiguousBlobAccumulator &CBA,
 130                                ELFYAML::Section *YAMLSec);
 131   void setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
 132                               std::vector<Elf_Shdr> &SHeaders);
 133   void finalizeStrings();
 134   void writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS);
 135   bool writeSectionContent(Elf_Shdr &SHeader,
 136                            const ELFYAML::RawContentSection &Section,
 137                            ContiguousBlobAccumulator &CBA);
 138   bool writeSectionContent(Elf_Shdr &SHeader,
 139                            const ELFYAML::RelocationSection &Section,
 140                            ContiguousBlobAccumulator &CBA);
 141   bool writeSectionContent(Elf_Shdr &SHeader, const ELFYAML::Group &Group,
 142                            ContiguousBlobAccumulator &CBA);
 143   bool writeSectionContent(Elf_Shdr &SHeader,
 144                            const ELFYAML::SymtabShndxSection &Shndx,
 145                            ContiguousBlobAccumulator &CBA);
 146   bool writeSectionContent(Elf_Shdr &SHeader,
 147                            const ELFYAML::SymverSection &Section,
 148                            ContiguousBlobAccumulator &CBA);
 149   bool writeSectionContent(Elf_Shdr &SHeader,
 150                            const ELFYAML::VerneedSection &Section,
 151                            ContiguousBlobAccumulator &CBA);
 152   bool writeSectionContent(Elf_Shdr &SHeader,
 153                            const ELFYAML::VerdefSection &Section,
 154                            ContiguousBlobAccumulator &CBA);
 155   bool writeSectionContent(Elf_Shdr &SHeader,
 156                            const ELFYAML::MipsABIFlags &Section,
 157                            ContiguousBlobAccumulator &CBA);
 158   bool writeSectionContent(Elf_Shdr &SHeader,
 159                            const ELFYAML::DynamicSection &Section,
 160                            ContiguousBlobAccumulator &CBA);
 161   ELFState(ELFYAML::Object &D);
 162
 163 public:
 164   static int writeELF(raw_ostream &OS, ELFYAML::Object &Doc);
 165 };
 166 } // end anonymous namespace
 167
 168 template <class T> static size_t arrayDataSize(ArrayRef<T> A) {
 169   return A.size() * sizeof(T);
 170 }
 171
 172 template <class T> static void writeArrayData(raw_ostream &OS, ArrayRef<T> A) {
 173   OS.write((const char *)A.data(), arrayDataSize(A));
 174 }
 175
 176 template <class T> static void zero(T &Obj) { memset(&Obj, 0, sizeof(Obj)); }
 177
 178 template <class ELFT> ELFState<ELFT>::ELFState(ELFYAML::Object &D) : Doc(D) {
 179   StringSet<> DocSections;
 180   for (std::unique_ptr<ELFYAML::Section> &D : Doc.Sections)
 181     if (!D->Name.empty())
 182       DocSections.insert(D->Name);
 183
 184   // Insert SHT_NULL section implicitly when it is not defined in YAML.
 185   if (Doc.Sections.empty() || Doc.Sections.front()->Type != ELF::SHT_NULL)
 186     Doc.Sections.insert(
 187         Doc.Sections.begin(),
 188         std::make_unique<ELFYAML::Section>(
 189             ELFYAML::Section::SectionKind::RawContent, /*IsImplicit=*/true));
 190
 191   std::vector<StringRef> ImplicitSections = {".symtab", ".strtab", ".shstrtab"};
 192   if (!Doc.DynamicSymbols.empty())
 193     ImplicitSections.insert(ImplicitSections.end(), {".dynsym", ".dynstr"});
 194
 195   // Insert placeholders for implicit sections that are not
 196   // defined explicitly in YAML.
 197   for (StringRef SecName : ImplicitSections) {
 198     if (DocSections.count(SecName))
 199       continue;
 200
 201     std::unique_ptr<ELFYAML::Section> Sec = std::make_unique<ELFYAML::Section>(
 202         ELFYAML::Section::SectionKind::RawContent, true /*IsImplicit*/);
 203     Sec->Name = SecName;
 204     Doc.Sections.push_back(std::move(Sec));
 205   }
 206 }
 207
 208 template <class ELFT>
 209 void ELFState<ELFT>::writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS) {
 210   using namespace llvm::ELF;
 211
 212   Elf_Ehdr Header;
 213   zero(Header);
 214   Header.e_ident[EI_MAG0] = 0x7f;
 215   Header.e_ident[EI_MAG1] = 'E';
 216   Header.e_ident[EI_MAG2] = 'L';
 217   Header.e_ident[EI_MAG3] = 'F';
 218   Header.e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
 219   Header.e_ident[EI_DATA] = Doc.Header.Data;
 220   Header.e_ident[EI_VERSION] = EV_CURRENT;
 221   Header.e_ident[EI_OSABI] = Doc.Header.OSABI;
 222   Header.e_ident[EI_ABIVERSION] = Doc.Header.ABIVersion;
 223   Header.e_type = Doc.Header.Type;
 224   Header.e_machine = Doc.Header.Machine;
 225   Header.e_version = EV_CURRENT;
 226   Header.e_entry = Doc.Header.Entry;
 227   Header.e_phoff = Doc.ProgramHeaders.size() ? sizeof(Header) : 0;
 228   Header.e_flags = Doc.Header.Flags;
 229   Header.e_ehsize = sizeof(Elf_Ehdr);
 230   Header.e_phentsize = Doc.ProgramHeaders.size() ? sizeof(Elf_Phdr) : 0;
 231   Header.e_phnum = Doc.ProgramHeaders.size();
 232
 233   Header.e_shentsize =
 234       Doc.Header.SHEntSize ? (uint16_t)*Doc.Header.SHEntSize : sizeof(Elf_Shdr);
 235   // Immediately following the ELF header and program headers.
 236   // Align the start of the section header and write the ELF header.
 237   uint64_t SHOff;
 238   CBA.getOSAndAlignedOffset(SHOff, sizeof(typename ELFT::uint));
 239   Header.e_shoff =
 240       Doc.Header.SHOff ? typename ELFT::uint(*Doc.Header.SHOff) : SHOff;
 241   Header.e_shnum =
 242       Doc.Header.SHNum ? (uint16_t)*Doc.Header.SHNum : Doc.Sections.size();
 243   Header.e_shstrndx = Doc.Header.SHStrNdx ? (uint16_t)*Doc.Header.SHStrNdx
 244                                           : SN2I.get(".shstrtab");
 245
 246   OS.write((const char *)&Header, sizeof(Header));
 247 }
 248
 249 template <class ELFT>
 250 void ELFState<ELFT>::initProgramHeaders(std::vector<Elf_Phdr> &PHeaders) {
 251   for (const auto &YamlPhdr : Doc.ProgramHeaders) {
 252     Elf_Phdr Phdr;
 253     Phdr.p_type = YamlPhdr.Type;
 254     Phdr.p_flags = YamlPhdr.Flags;
 255     Phdr.p_vaddr = YamlPhdr.VAddr;
 256     Phdr.p_paddr = YamlPhdr.PAddr;
 257     PHeaders.push_back(Phdr);
 258   }
 259 }
 260
 261 static bool convertSectionIndex(NameToIdxMap &SN2I, StringRef SecName,
 262                                 StringRef IndexSrc, unsigned &IndexDest) {
 263   if (!SN2I.lookup(IndexSrc, IndexDest) && !to_integer(IndexSrc, IndexDest)) {
 264     WithColor::error() << "Unknown section referenced: '" << IndexSrc
 265                        << "' at YAML section '" << SecName << "'.\n";
 266     return false;
 267   }
 268   return true;
 269 }
 270
 271 template <class ELFT>
 272 bool ELFState<ELFT>::initImplicitHeader(ContiguousBlobAccumulator &CBA,
 273                                         Elf_Shdr &Header, StringRef SecName,
 274                                         ELFYAML::Section *YAMLSec) {
 275   // Check if the header was already initialized.
 276   if (Header.sh_offset)
 277     return false;
 278
 279   if (SecName == ".symtab")
 280     initSymtabSectionHeader(Header, SymtabType::Static, CBA, YAMLSec);
 281   else if (SecName == ".strtab")
 282     initStrtabSectionHeader(Header, SecName, DotStrtab, CBA, YAMLSec);
 283   else if (SecName == ".shstrtab")
 284     initStrtabSectionHeader(Header, SecName, DotShStrtab, CBA, YAMLSec);
 285   else if (SecName == ".dynsym")
 286     initSymtabSectionHeader(Header, SymtabType::Dynamic, CBA, YAMLSec);
 287   else if (SecName == ".dynstr")
 288     initStrtabSectionHeader(Header, SecName, DotDynstr, CBA, YAMLSec);
 289   else
 290     return false;
 291
 292   // Override the fields if requested.
 293   if (YAMLSec) {
 294     if (YAMLSec->ShName)
 295       Header.sh_name = *YAMLSec->ShName;
 296     if (YAMLSec->ShOffset)
 297       Header.sh_offset = *YAMLSec->ShOffset;
 298     if (YAMLSec->ShSize)
 299       Header.sh_size = *YAMLSec->ShSize;
 300   }
 301
 302   return true;
 303 }
 304
 305 static StringRef dropUniqueSuffix(StringRef S) {
 306   size_t SuffixPos = S.rfind(" [");
 307   if (SuffixPos == StringRef::npos)
 308     return S;
 309   return S.substr(0, SuffixPos);
 310 }
 311
 312 template <class ELFT>
 313 bool ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
 314                                         ContiguousBlobAccumulator &CBA) {
 315   // Ensure SHN_UNDEF entry is present. An all-zero section header is a
 316   // valid SHN_UNDEF entry since SHT_NULL == 0.
 317   SHeaders.resize(Doc.Sections.size());
 318
 319   for (size_t I = 0; I < Doc.Sections.size(); ++I) {
 320     ELFYAML::Section *Sec = Doc.Sections[I].get();
 321     if (I == 0 && Sec->IsImplicit)
 322       continue;
 323
 324     // We have a few sections like string or symbol tables that are usually
 325     // added implicitly to the end. However, if they are explicitly specified
 326     // in the YAML, we need to write them here. This ensures the file offset
 327     // remains correct.
 328     Elf_Shdr &SHeader = SHeaders[I];
 329     if (initImplicitHeader(CBA, SHeader, Sec->Name,
 330                            Sec->IsImplicit ? nullptr : Sec))
 331       continue;
 332
 333     assert(Sec && "It can't be null unless it is an implicit section. But all "
 334                   "implicit sections should already have been handled above.");
 335
 336     SHeader.sh_name = DotShStrtab.getOffset(dropUniqueSuffix(Sec->Name));
 337     SHeader.sh_type = Sec->Type;
 338     if (Sec->Flags)
 339       SHeader.sh_flags = *Sec->Flags;
 340     SHeader.sh_addr = Sec->Address;
 341     SHeader.sh_addralign = Sec->AddressAlign;
 342
 343     if (!Sec->Link.empty()) {
 344       unsigned Index;
 345       if (!convertSectionIndex(SN2I, Sec->Name, Sec->Link, Index))
 346         return false;
 347       SHeader.sh_link = Index;
 348     }
 349
 350     if (I == 0) {
 351       if (auto RawSec = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
 352         // We do not write any content for special SHN_UNDEF section.
 353         if (RawSec->Size)
 354           SHeader.sh_size = *RawSec->Size;
 355         if (RawSec->Info)
 356           SHeader.sh_info = *RawSec->Info;
 357       }
 358       if (Sec->EntSize)
 359         SHeader.sh_entsize = *Sec->EntSize;
 360     } else if (auto S = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
 361       if (!writeSectionContent(SHeader, *S, CBA))
 362         return false;
 363     } else if (auto S = dyn_cast<ELFYAML::SymtabShndxSection>(Sec)) {
 364       if (!writeSectionContent(SHeader, *S, CBA))
 365         return false;
 366     } else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec)) {
 367       if (!writeSectionContent(SHeader, *S, CBA))
 368         return false;
 369     } else if (auto S = dyn_cast<ELFYAML::Group>(Sec)) {
 370       if (!writeSectionContent(SHeader, *S, CBA))
 371         return false;
 372     } else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec)) {
 373       if (!writeSectionContent(SHeader, *S, CBA))
 374         return false;
 375     } else if (auto S = dyn_cast<ELFYAML::NoBitsSection>(Sec)) {
 376       SHeader.sh_entsize = 0;
 377       SHeader.sh_size = S->Size;
 378       // SHT_NOBITS section does not have content
 379       // so just to setup the section offset.
 380       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 381     } else if (auto S = dyn_cast<ELFYAML::DynamicSection>(Sec)) {
 382       if (!writeSectionContent(SHeader, *S, CBA))
 383         return false;
 384     } else if (auto S = dyn_cast<ELFYAML::SymverSection>(Sec)) {
 385       if (!writeSectionContent(SHeader, *S, CBA))
 386         return false;
 387     } else if (auto S = dyn_cast<ELFYAML::VerneedSection>(Sec)) {
 388       if (!writeSectionContent(SHeader, *S, CBA))
 389         return false;
 390     } else if (auto S = dyn_cast<ELFYAML::VerdefSection>(Sec)) {
 391       if (!writeSectionContent(SHeader, *S, CBA))
 392         return false;
 393     } else
 394       llvm_unreachable("Unknown section type");
 395
 396     // Override the fields if requested.
 397     if (Sec) {
 398       if (Sec->ShName)
 399         SHeader.sh_name = *Sec->ShName;
 400       if (Sec->ShOffset)
 401         SHeader.sh_offset = *Sec->ShOffset;
 402       if (Sec->ShSize)
 403         SHeader.sh_size = *Sec->ShSize;
 404     }
 405   }
 406
 407   return true;
 408 }
 409
 410 static size_t findFirstNonGlobal(ArrayRef<ELFYAML::Symbol> Symbols) {
 411   for (size_t I = 0; I < Symbols.size(); ++I)
 412     if (Symbols[I].Binding.value != ELF::STB_LOCAL)
 413       return I;
 414   return Symbols.size();
 415 }
 416
 417 static uint64_t writeRawSectionData(raw_ostream &OS,
 418                                     const ELFYAML::RawContentSection &RawSec) {
 419   size_t ContentSize = 0;
 420   if (RawSec.Content) {
 421     RawSec.Content->writeAsBinary(OS);
 422     ContentSize = RawSec.Content->binary_size();
 423   }
 424
 425   if (!RawSec.Size)
 426     return ContentSize;
 427
 428   OS.write_zeros(*RawSec.Size - ContentSize);
 429   return *RawSec.Size;
 430 }
 431
 432 template <class ELFT>
 433 static std::vector<typename ELFT::Sym>
 434 toELFSymbols(NameToIdxMap &SN2I, ArrayRef<ELFYAML::Symbol> Symbols,
 435              const StringTableBuilder &Strtab) {
 436   using Elf_Sym = typename ELFT::Sym;
 437
 438   std::vector<Elf_Sym> Ret;
 439   Ret.resize(Symbols.size() + 1);
 440
 441   size_t I = 0;
 442   for (const auto &Sym : Symbols) {
 443     Elf_Sym &Symbol = Ret[++I];
 444
 445     // If NameIndex, which contains the name offset, is explicitly specified, we
 446     // use it. This is useful for preparing broken objects. Otherwise, we add
 447     // the specified Name to the string table builder to get its offset.
 448     if (Sym.NameIndex)
 449       Symbol.st_name = *Sym.NameIndex;
 450     else if (!Sym.Name.empty())
 451       Symbol.st_name = Strtab.getOffset(dropUniqueSuffix(Sym.Name));
 452
 453     Symbol.setBindingAndType(Sym.Binding, Sym.Type);
 454     if (!Sym.Section.empty()) {
 455       unsigned Index;
 456       if (!SN2I.lookup(Sym.Section, Index)) {
 457         WithColor::error() << "Unknown section referenced: '" << Sym.Section
 458                            << "' by YAML symbol " << Sym.Name << ".\n";
 459         exit(1);
 460       }
 461       Symbol.st_shndx = Index;
 462     } else if (Sym.Index) {
 463       Symbol.st_shndx = *Sym.Index;
 464     }
 465     // else Symbol.st_shndex == SHN_UNDEF (== 0), since it was zero'd earlier.
 466     Symbol.st_value = Sym.Value;
 467     Symbol.st_other = Sym.Other ? *Sym.Other : 0;
 468     Symbol.st_size = Sym.Size;
 469   }
 470
 471   return Ret;
 472 }
 473
 474 template <class ELFT>
 475 void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
 476                                              SymtabType STType,
 477                                              ContiguousBlobAccumulator &CBA,
 478                                              ELFYAML::Section *YAMLSec) {
 479
 480   bool IsStatic = STType == SymtabType::Static;
 481   const auto &Symbols = IsStatic ? Doc.Symbols : Doc.DynamicSymbols;
 482
 483   ELFYAML::RawContentSection *RawSec =
 484       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
 485   if (RawSec && !Symbols.empty() && (RawSec->Content || RawSec->Size)) {
 486     if (RawSec->Content)
 487       WithColor::error() << "Cannot specify both `Content` and " +
 488                                 (IsStatic ? Twine("`Symbols`")
 489                                           : Twine("`DynamicSymbols`")) +
 490                                 " for symbol table section '"
 491                          << RawSec->Name << "'.\n";
 492     if (RawSec->Size)
 493       WithColor::error() << "Cannot specify both `Size` and " +
 494                                 (IsStatic ? Twine("`Symbols`")
 495                                           : Twine("`DynamicSymbols`")) +
 496                                 " for symbol table section '"
 497                          << RawSec->Name << "'.\n";
 498     exit(1);
 499   }
 500
 501   zero(SHeader);
 502   SHeader.sh_name = DotShStrtab.getOffset(IsStatic ? ".symtab" : ".dynsym");
 503
 504   if (YAMLSec)
 505     SHeader.sh_type = YAMLSec->Type;
 506   else
 507     SHeader.sh_type = IsStatic ? ELF::SHT_SYMTAB : ELF::SHT_DYNSYM;
 508
 509   if (RawSec && !RawSec->Link.empty()) {
 510     // If the Link field is explicitly defined in the document,
 511     // we should use it.
 512     unsigned Index;
 513     if (!convertSectionIndex(SN2I, RawSec->Name, RawSec->Link, Index))
 514       return;
 515     SHeader.sh_link = Index;
 516   } else {
 517     // When we describe the .dynsym section in the document explicitly, it is
 518     // allowed to omit the "DynamicSymbols" tag. In this case .dynstr is not
 519     // added implicitly and we should be able to leave the Link zeroed if
 520     // .dynstr is not defined.
 521     unsigned Link = 0;
 522     if (IsStatic)
 523       Link = SN2I.get(".strtab");
 524     else
 525       SN2I.lookup(".dynstr", Link);
 526     SHeader.sh_link = Link;
 527   }
 528
 529   if (YAMLSec && YAMLSec->Flags)
 530     SHeader.sh_flags = *YAMLSec->Flags;
 531   else if (!IsStatic)
 532     SHeader.sh_flags = ELF::SHF_ALLOC;
 533
 534   // If the symbol table section is explicitly described in the YAML
 535   // then we should set the fields requested.
 536   SHeader.sh_info = (RawSec && RawSec->Info) ? (unsigned)(*RawSec->Info)
 537                                              : findFirstNonGlobal(Symbols) + 1;
 538   SHeader.sh_entsize = (YAMLSec && YAMLSec->EntSize)
 539                            ? (uint64_t)(*YAMLSec->EntSize)
 540                            : sizeof(Elf_Sym);
 541   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 8;
 542   SHeader.sh_addr = YAMLSec ? (uint64_t)YAMLSec->Address : 0;
 543
 544   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 545   if (RawSec && (RawSec->Content || RawSec->Size)) {
 546     assert(Symbols.empty());
 547     SHeader.sh_size = writeRawSectionData(OS, *RawSec);
 548     return;
 549   }
 550
 551   std::vector<Elf_Sym> Syms =
 552       toELFSymbols<ELFT>(SN2I, Symbols, IsStatic ? DotStrtab : DotDynstr);
 553   writeArrayData(OS, makeArrayRef(Syms));
 554   SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
 555 }
 556
 557 template <class ELFT>
 558 void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
 559                                              StringTableBuilder &STB,
 560                                              ContiguousBlobAccumulator &CBA,
 561                                              ELFYAML::Section *YAMLSec) {
 562   zero(SHeader);
 563   SHeader.sh_name = DotShStrtab.getOffset(Name);
 564   SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_STRTAB;
 565   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
 566
 567   ELFYAML::RawContentSection *RawSec =
 568       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
 569
 570   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 571   if (RawSec && (RawSec->Content || RawSec->Size)) {
 572     SHeader.sh_size = writeRawSectionData(OS, *RawSec);
 573   } else {
 574     STB.write(OS);
 575     SHeader.sh_size = STB.getSize();
 576   }
 577
 578   if (YAMLSec && YAMLSec->EntSize)
 579     SHeader.sh_entsize = *YAMLSec->EntSize;
 580
 581   if (RawSec && RawSec->Info)
 582     SHeader.sh_info = *RawSec->Info;
 583
 584   if (YAMLSec && YAMLSec->Flags)
 585     SHeader.sh_flags = *YAMLSec->Flags;
 586   else if (Name == ".dynstr")
 587     SHeader.sh_flags = ELF::SHF_ALLOC;
 588
 589   // If the section is explicitly described in the YAML
 590   // then we want to use its section address.
 591   if (YAMLSec)
 592     SHeader.sh_addr = YAMLSec->Address;
 593 }
 594
 595 template <class ELFT>
 596 void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
 597                                             std::vector<Elf_Shdr> &SHeaders) {
 598   uint32_t PhdrIdx = 0;
 599   for (auto &YamlPhdr : Doc.ProgramHeaders) {
 600     Elf_Phdr &PHeader = PHeaders[PhdrIdx++];
 601
 602     std::vector<Elf_Shdr *> Sections;
 603     for (const ELFYAML::SectionName &SecName : YamlPhdr.Sections) {
 604       unsigned Index;
 605       if (!SN2I.lookup(SecName.Section, Index)) {
 606         WithColor::error() << "Unknown section referenced: '" << SecName.Section
 607                            << "' by program header.\n";
 608         exit(1);
 609       }
 610       Sections.push_back(&SHeaders[Index]);
 611     }
 612
 613     if (YamlPhdr.Offset) {
 614       PHeader.p_offset = *YamlPhdr.Offset;
 615     } else {
 616       if (YamlPhdr.Sections.size())
 617         PHeader.p_offset = UINT32_MAX;
 618       else
 619         PHeader.p_offset = 0;
 620
 621       // Find the minimum offset for the program header.
 622       for (Elf_Shdr *SHeader : Sections)
 623         PHeader.p_offset = std::min(PHeader.p_offset, SHeader->sh_offset);
 624     }
 625
 626     // Find the maximum offset of the end of a section in order to set p_filesz,
 627     // if not set explicitly.
 628     if (YamlPhdr.FileSize) {
 629       PHeader.p_filesz = *YamlPhdr.FileSize;
 630     } else {
 631       PHeader.p_filesz = 0;
 632       for (Elf_Shdr *SHeader : Sections) {
 633         uint64_t EndOfSection;
 634         if (SHeader->sh_type == llvm::ELF::SHT_NOBITS)
 635           EndOfSection = SHeader->sh_offset;
 636         else
 637           EndOfSection = SHeader->sh_offset + SHeader->sh_size;
 638         uint64_t EndOfSegment = PHeader.p_offset + PHeader.p_filesz;
 639         EndOfSegment = std::max(EndOfSegment, EndOfSection);
 640         PHeader.p_filesz = EndOfSegment - PHeader.p_offset;
 641       }
 642     }
 643
 644     // If not set explicitly, find the memory size by adding the size of
 645     // sections at the end of the segment. These should be empty (size of zero)
 646     // and NOBITS sections.
 647     if (YamlPhdr.MemSize) {
 648       PHeader.p_memsz = *YamlPhdr.MemSize;
 649     } else {
 650       PHeader.p_memsz = PHeader.p_filesz;
 651       for (Elf_Shdr *SHeader : Sections)
 652         if (SHeader->sh_offset == PHeader.p_offset + PHeader.p_filesz)
 653           PHeader.p_memsz += SHeader->sh_size;
 654     }
 655
 656     // Set the alignment of the segment to be the same as the maximum alignment
 657     // of the sections with the same offset so that by default the segment
 658     // has a valid and sensible alignment.
 659     if (YamlPhdr.Align) {
 660       PHeader.p_align = *YamlPhdr.Align;
 661     } else {
 662       PHeader.p_align = 1;
 663       for (Elf_Shdr *SHeader : Sections)
 664         if (SHeader->sh_offset == PHeader.p_offset)
 665           PHeader.p_align = std::max(PHeader.p_align, SHeader->sh_addralign);
 666     }
 667   }
 668 }
 669
 670 template <class ELFT>
 671 bool ELFState<ELFT>::writeSectionContent(
 672     Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section,
 673     ContiguousBlobAccumulator &CBA) {
 674   raw_ostream &OS =
 675       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 676   SHeader.sh_size = writeRawSectionData(OS, Section);
 677
 678   if (Section.EntSize)
 679     SHeader.sh_entsize = *Section.EntSize;
 680   else if (Section.Type == llvm::ELF::SHT_RELR)
 681     SHeader.sh_entsize = sizeof(Elf_Relr);
 682   else
 683     SHeader.sh_entsize = 0;
 684
 685   if (Section.Info)
 686     SHeader.sh_info = *Section.Info;
 687
 688   return true;
 689 }
 690
 691 static bool isMips64EL(const ELFYAML::Object &Doc) {
 692   return Doc.Header.Machine == ELFYAML::ELF_EM(llvm::ELF::EM_MIPS) &&
 693          Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64) &&
 694          Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
 695 }
 696
 697 template <class ELFT>
 698 bool ELFState<ELFT>::writeSectionContent(
 699     Elf_Shdr &SHeader, const ELFYAML::RelocationSection &Section,
 700     ContiguousBlobAccumulator &CBA) {
 701   assert((Section.Type == llvm::ELF::SHT_REL ||
 702           Section.Type == llvm::ELF::SHT_RELA) &&
 703          "Section type is not SHT_REL nor SHT_RELA");
 704
 705   bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
 706   SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
 707   SHeader.sh_size = SHeader.sh_entsize * Section.Relocations.size();
 708
 709   // For relocation section set link to .symtab by default.
 710   if (Section.Link.empty())
 711     SHeader.sh_link = SN2I.get(".symtab");
 712
 713   unsigned Index = 0;
 714   if (!Section.RelocatableSec.empty() &&
 715       !convertSectionIndex(SN2I, Section.Name, Section.RelocatableSec, Index))
 716     return false;
 717   SHeader.sh_info = Index;
 718
 719   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 720
 721   const NameToIdxMap &SymMap = Section.Link == ".dynsym" ? DynSymN2I : SymN2I;
 722   for (const auto &Rel : Section.Relocations) {
 723     unsigned SymIdx = 0;
 724     // If a relocation references a symbol, try to look one up in the symbol
 725     // table. If it is not there, treat the value as a symbol index.
 726     if (Rel.Symbol && !SymMap.lookup(*Rel.Symbol, SymIdx) &&
 727         !to_integer(*Rel.Symbol, SymIdx)) {
 728       WithColor::error() << "Unknown symbol referenced: '" << *Rel.Symbol
 729                          << "' at YAML section '" << Section.Name << "'.\n";
 730       return false;
 731     }
 732
 733     if (IsRela) {
 734       Elf_Rela REntry;
 735       zero(REntry);
 736       REntry.r_offset = Rel.Offset;
 737       REntry.r_addend = Rel.Addend;
 738       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
 739       OS.write((const char *)&REntry, sizeof(REntry));
 740     } else {
 741       Elf_Rel REntry;
 742       zero(REntry);
 743       REntry.r_offset = Rel.Offset;
 744       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
 745       OS.write((const char *)&REntry, sizeof(REntry));
 746     }
 747   }
 748   return true;
 749 }
 750
 751 template <class ELFT>
 752 bool ELFState<ELFT>::writeSectionContent(
 753     Elf_Shdr &SHeader, const ELFYAML::SymtabShndxSection &Shndx,
 754     ContiguousBlobAccumulator &CBA) {
 755   raw_ostream &OS =
 756       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 757
 758   for (uint32_t E : Shndx.Entries)
 759     support::endian::write<uint32_t>(OS, E, ELFT::TargetEndianness);
 760
 761   SHeader.sh_entsize = Shndx.EntSize ? (uint64_t)*Shndx.EntSize : 4;
 762   SHeader.sh_size = Shndx.Entries.size() * SHeader.sh_entsize;
 763   return true;
 764 }
 765
 766 template <class ELFT>
 767 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 768                                          const ELFYAML::Group &Section,
 769                                          ContiguousBlobAccumulator &CBA) {
 770   assert(Section.Type == llvm::ELF::SHT_GROUP &&
 771          "Section type is not SHT_GROUP");
 772
 773   SHeader.sh_entsize = 4;
 774   SHeader.sh_size = SHeader.sh_entsize * Section.Members.size();
 775
 776   unsigned SymIdx;
 777   if (!SymN2I.lookup(Section.Signature, SymIdx) &&
 778       !to_integer(Section.Signature, SymIdx)) {
 779     WithColor::error() << "Unknown symbol referenced: '" << Section.Signature
 780                        << "' at YAML section '" << Section.Name << "'.\n";
 781     return false;
 782   }
 783   SHeader.sh_info = SymIdx;
 784
 785   raw_ostream &OS =
 786       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 787
 788   for (const ELFYAML::SectionOrType &Member : Section.Members) {
 789     unsigned int SectionIndex = 0;
 790     if (Member.sectionNameOrType == "GRP_COMDAT")
 791       SectionIndex = llvm::ELF::GRP_COMDAT;
 792     else if (!convertSectionIndex(SN2I, Section.Name, Member.sectionNameOrType,
 793                                   SectionIndex))
 794       return false;
 795     support::endian::write<uint32_t>(OS, SectionIndex, ELFT::TargetEndianness);
 796   }
 797   return true;
 798 }
 799
 800 template <class ELFT>
 801 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 802                                          const ELFYAML::SymverSection &Section,
 803                                          ContiguousBlobAccumulator &CBA) {
 804   raw_ostream &OS =
 805       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 806   for (uint16_t Version : Section.Entries)
 807     support::endian::write<uint16_t>(OS, Version, ELFT::TargetEndianness);
 808
 809   SHeader.sh_entsize = Section.EntSize ? (uint64_t)*Section.EntSize : 2;
 810   SHeader.sh_size = Section.Entries.size() * SHeader.sh_entsize;
 811   return true;
 812 }
 813
 814 template <class ELFT>
 815 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 816                                          const ELFYAML::VerdefSection &Section,
 817                                          ContiguousBlobAccumulator &CBA) {
 818   typedef typename ELFT::Verdef Elf_Verdef;
 819   typedef typename ELFT::Verdaux Elf_Verdaux;
 820   raw_ostream &OS =
 821       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 822
 823   uint64_t AuxCnt = 0;
 824   for (size_t I = 0; I < Section.Entries.size(); ++I) {
 825     const ELFYAML::VerdefEntry &E = Section.Entries[I];
 826
 827     Elf_Verdef VerDef;
 828     VerDef.vd_version = E.Version;
 829     VerDef.vd_flags = E.Flags;
 830     VerDef.vd_ndx = E.VersionNdx;
 831     VerDef.vd_hash = E.Hash;
 832     VerDef.vd_aux = sizeof(Elf_Verdef);
 833     VerDef.vd_cnt = E.VerNames.size();
 834     if (I == Section.Entries.size() - 1)
 835       VerDef.vd_next = 0;
 836     else
 837       VerDef.vd_next =
 838           sizeof(Elf_Verdef) + E.VerNames.size() * sizeof(Elf_Verdaux);
 839     OS.write((const char *)&VerDef, sizeof(Elf_Verdef));
 840
 841     for (size_t J = 0; J < E.VerNames.size(); ++J, ++AuxCnt) {
 842       Elf_Verdaux VernAux;
 843       VernAux.vda_name = DotDynstr.getOffset(E.VerNames[J]);
 844       if (J == E.VerNames.size() - 1)
 845         VernAux.vda_next = 0;
 846       else
 847         VernAux.vda_next = sizeof(Elf_Verdaux);
 848       OS.write((const char *)&VernAux, sizeof(Elf_Verdaux));
 849     }
 850   }
 851
 852   SHeader.sh_size = Section.Entries.size() * sizeof(Elf_Verdef) +
 853                     AuxCnt * sizeof(Elf_Verdaux);
 854   SHeader.sh_info = Section.Info;
 855
 856   return true;
 857 }
 858
 859 template <class ELFT>
 860 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 861                                          const ELFYAML::VerneedSection &Section,
 862                                          ContiguousBlobAccumulator &CBA) {
 863   typedef typename ELFT::Verneed Elf_Verneed;
 864   typedef typename ELFT::Vernaux Elf_Vernaux;
 865
 866   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 867
 868   uint64_t AuxCnt = 0;
 869   for (size_t I = 0; I < Section.VerneedV.size(); ++I) {
 870     const ELFYAML::VerneedEntry &VE = Section.VerneedV[I];
 871
 872     Elf_Verneed VerNeed;
 873     VerNeed.vn_version = VE.Version;
 874     VerNeed.vn_file = DotDynstr.getOffset(VE.File);
 875     if (I == Section.VerneedV.size() - 1)
 876       VerNeed.vn_next = 0;
 877     else
 878       VerNeed.vn_next =
 879           sizeof(Elf_Verneed) + VE.AuxV.size() * sizeof(Elf_Vernaux);
 880     VerNeed.vn_cnt = VE.AuxV.size();
 881     VerNeed.vn_aux = sizeof(Elf_Verneed);
 882     OS.write((const char *)&VerNeed, sizeof(Elf_Verneed));
 883
 884     for (size_t J = 0; J < VE.AuxV.size(); ++J, ++AuxCnt) {
 885       const ELFYAML::VernauxEntry &VAuxE = VE.AuxV[J];
 886
 887       Elf_Vernaux VernAux;
 888       VernAux.vna_hash = VAuxE.Hash;
 889       VernAux.vna_flags = VAuxE.Flags;
 890       VernAux.vna_other = VAuxE.Other;
 891       VernAux.vna_name = DotDynstr.getOffset(VAuxE.Name);
 892       if (J == VE.AuxV.size() - 1)
 893         VernAux.vna_next = 0;
 894       else
 895         VernAux.vna_next = sizeof(Elf_Vernaux);
 896       OS.write((const char *)&VernAux, sizeof(Elf_Vernaux));
 897     }
 898   }
 899
 900   SHeader.sh_size = Section.VerneedV.size() * sizeof(Elf_Verneed) +
 901                     AuxCnt * sizeof(Elf_Vernaux);
 902   SHeader.sh_info = Section.Info;
 903
 904   return true;
 905 }
 906
 907 template <class ELFT>
 908 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 909                                          const ELFYAML::MipsABIFlags &Section,
 910                                          ContiguousBlobAccumulator &CBA) {
 911   assert(Section.Type == llvm::ELF::SHT_MIPS_ABIFLAGS &&
 912          "Section type is not SHT_MIPS_ABIFLAGS");
 913
 914   object::Elf_Mips_ABIFlags<ELFT> Flags;
 915   zero(Flags);
 916   SHeader.sh_entsize = sizeof(Flags);
 917   SHeader.sh_size = SHeader.sh_entsize;
 918
 919   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 920   Flags.version = Section.Version;
 921   Flags.isa_level = Section.ISALevel;
 922   Flags.isa_rev = Section.ISARevision;
 923   Flags.gpr_size = Section.GPRSize;
 924   Flags.cpr1_size = Section.CPR1Size;
 925   Flags.cpr2_size = Section.CPR2Size;
 926   Flags.fp_abi = Section.FpABI;
 927   Flags.isa_ext = Section.ISAExtension;
 928   Flags.ases = Section.ASEs;
 929   Flags.flags1 = Section.Flags1;
 930   Flags.flags2 = Section.Flags2;
 931   OS.write((const char *)&Flags, sizeof(Flags));
 932
 933   return true;
 934 }
 935
 936 template <class ELFT>
 937 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 938                                          const ELFYAML::DynamicSection &Section,
 939                                          ContiguousBlobAccumulator &CBA) {
 940   typedef typename ELFT::uint uintX_t;
 941
 942   assert(Section.Type == llvm::ELF::SHT_DYNAMIC &&
 943          "Section type is not SHT_DYNAMIC");
 944
 945   if (!Section.Entries.empty() && Section.Content) {
 946     WithColor::error()
 947         << "Cannot specify both raw content and explicit entries "
 948            "for dynamic section '"
 949         << Section.Name << "'.\n";
 950     return false;
 951   }
 952
 953   if (Section.Content)
 954     SHeader.sh_size = Section.Content->binary_size();
 955   else
 956     SHeader.sh_size = 2 * sizeof(uintX_t) * Section.Entries.size();
 957   if (Section.EntSize)
 958     SHeader.sh_entsize = *Section.EntSize;
 959   else
 960     SHeader.sh_entsize = sizeof(Elf_Dyn);
 961
 962   raw_ostream &OS =
 963       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 964   for (const ELFYAML::DynamicEntry &DE : Section.Entries) {
 965     support::endian::write<uintX_t>(OS, DE.Tag, ELFT::TargetEndianness);
 966     support::endian::write<uintX_t>(OS, DE.Val, ELFT::TargetEndianness);
 967   }
 968   if (Section.Content)
 969     Section.Content->writeAsBinary(OS);
 970
 971   return true;
 972 }
 973
 974 template <class ELFT> bool ELFState<ELFT>::buildSectionIndex() {
 975   for (unsigned I = 0, E = Doc.Sections.size(); I != E; ++I) {
 976     StringRef Name = Doc.Sections[I]->Name;
 977     if (Name.empty())
 978       continue;
 979
 980     DotShStrtab.add(dropUniqueSuffix(Name));
 981     if (!SN2I.addName(Name, I)) {
 982       WithColor::error() << "Repeated section name: '" << Name
 983                          << "' at YAML section number " << I << ".\n";
 984       return false;
 985     }
 986   }
 987
 988   DotShStrtab.finalize();
 989   return true;
 990 }
 991
 992 static bool buildSymbolsMap(ArrayRef<ELFYAML::Symbol> V, NameToIdxMap &Map) {
 993   for (size_t I = 0, S = V.size(); I < S; ++I) {
 994     const ELFYAML::Symbol &Sym = V[I];
 995     if (Sym.Name.empty() || Map.addName(Sym.Name, I + 1))
 996       continue;
 997     WithColor::error() << "Repeated symbol name: '" << Sym.Name << "'.\n";
 998     return false;
 999   }
1000   return true;
1001 }
1002
1003 template <class ELFT> bool ELFState<ELFT>::buildSymbolIndexes() {
1004   return buildSymbolsMap(Doc.Symbols, SymN2I) &&
1005          buildSymbolsMap(Doc.DynamicSymbols, DynSymN2I);
1006 }
1007
1008 template <class ELFT> void ELFState<ELFT>::finalizeStrings() {
1009   // Add the regular symbol names to .strtab section.
1010   for (const ELFYAML::Symbol &Sym : Doc.Symbols)
1011     DotStrtab.add(dropUniqueSuffix(Sym.Name));
1012   DotStrtab.finalize();
1013
1014   // Add the dynamic symbol names to .dynstr section.
1015   for (const ELFYAML::Symbol &Sym : Doc.DynamicSymbols)
1016     DotDynstr.add(dropUniqueSuffix(Sym.Name));
1017
1018   // SHT_GNU_verdef and SHT_GNU_verneed sections might also
1019   // add strings to .dynstr section.
1020   for (const std::unique_ptr<ELFYAML::Section> &Sec : Doc.Sections) {
1021     if (auto VerNeed = dyn_cast<ELFYAML::VerneedSection>(Sec.get())) {
1022       for (const ELFYAML::VerneedEntry &VE : VerNeed->VerneedV) {
1023         DotDynstr.add(VE.File);
1024         for (const ELFYAML::VernauxEntry &Aux : VE.AuxV)
1025           DotDynstr.add(Aux.Name);
1026       }
1027     } else if (auto VerDef = dyn_cast<ELFYAML::VerdefSection>(Sec.get())) {
1028       for (const ELFYAML::VerdefEntry &E : VerDef->Entries)
1029         for (StringRef Name : E.VerNames)
1030           DotDynstr.add(Name);
1031     }
1032   }
1033
1034   DotDynstr.finalize();
1035 }
1036
1037 template <class ELFT>
1038 int ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc) {
1039   ELFState<ELFT> State(Doc);
1040
1041   // Finalize .strtab and .dynstr sections. We do that early because want to
1042   // finalize the string table builders before writing the content of the
1043   // sections that might want to use them.
1044   State.finalizeStrings();
1045
1046   if (!State.buildSectionIndex() || !State.buildSymbolIndexes())
1047     return 1;
1048
1049   std::vector<Elf_Phdr> PHeaders;
1050   State.initProgramHeaders(PHeaders);
1051
1052   // XXX: This offset is tightly coupled with the order that we write
1053   // things to `OS`.
1054   const size_t SectionContentBeginOffset =
1055       sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * Doc.ProgramHeaders.size();
1056   ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
1057
1058   std::vector<Elf_Shdr> SHeaders;
1059   if (!State.initSectionHeaders(SHeaders, CBA))
1060     return 1;
1061
1062   // Now we can decide segment offsets
1063   State.setProgramHeaderLayout(PHeaders, SHeaders);
1064
1065   State.writeELFHeader(CBA, OS);
1066   writeArrayData(OS, makeArrayRef(PHeaders));
1067   CBA.writeBlobToStream(OS);
1068   writeArrayData(OS, makeArrayRef(SHeaders));
1069   return 0;
1070 }
1071
1072 namespace llvm {
1073 namespace yaml {
1074
1075 int yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out) {
1076   bool IsLE = Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
1077   bool Is64Bit = Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
1078   if (Is64Bit) {
1079     if (IsLE)
1080       return ELFState<object::ELF64LE>::writeELF(Out, Doc);
1081     return ELFState<object::ELF64BE>::writeELF(Out, Doc);
1082   }
1083   if (IsLE)
1084     return ELFState<object::ELF32LE>::writeELF(Out, Doc);
1085   return ELFState<object::ELF32BE>::writeELF(Out, Doc);
1086 }
1087
1088 } // namespace yaml
1089 } // namespace llvm