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/LEB128.h"
  23 #include "llvm/Support/MemoryBuffer.h"
  24 #include "llvm/Support/WithColor.h"
  25 #include "llvm/Support/YAMLTraits.h"
  26 #include "llvm/Support/raw_ostream.h"
  27
  28 using namespace llvm;
  29
  30 // This class is used to build up a contiguous binary blob while keeping
  31 // track of an offset in the output (which notionally begins at
  32 // `InitialOffset`).
  33 namespace {
  34 class ContiguousBlobAccumulator {
  35   const uint64_t InitialOffset;
  36   SmallVector<char, 128> Buf;
  37   raw_svector_ostream OS;
  38
  39   /// \returns The new offset.
  40   uint64_t padToAlignment(unsigned Align) {
  41     if (Align == 0)
  42       Align = 1;
  43     uint64_t CurrentOffset = InitialOffset + OS.tell();
  44     uint64_t AlignedOffset = alignTo(CurrentOffset, Align);
  45     OS.write_zeros(AlignedOffset - CurrentOffset);
  46     return AlignedOffset; // == CurrentOffset;
  47   }
  48
  49 public:
  50   ContiguousBlobAccumulator(uint64_t InitialOffset_)
  51       : InitialOffset(InitialOffset_), Buf(), OS(Buf) {}
  52   template <class Integer>
  53   raw_ostream &getOSAndAlignedOffset(Integer &Offset, unsigned Align) {
  54     Offset = padToAlignment(Align);
  55     return OS;
  56   }
  57   void writeBlobToStream(raw_ostream &Out) { Out << OS.str(); }
  58 };
  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 class NameToIdxMap {
  63   StringMap<unsigned> Map;
  64
  65 public:
  66   /// \Returns false if name is already present in the map.
  67   bool addName(StringRef Name, unsigned Ndx) {
  68     return Map.insert({Name, Ndx}).second;
  69   }
  70   /// \Returns false if name is not present in the map.
  71   bool lookup(StringRef Name, unsigned &Idx) const {
  72     auto I = Map.find(Name);
  73     if (I == Map.end())
  74       return false;
  75     Idx = I->getValue();
  76     return true;
  77   }
  78   /// Asserts if name is not present in the map.
  79   unsigned get(StringRef Name) const {
  80     unsigned Idx;
  81     if (lookup(Name, Idx))
  82       return Idx;
  83     assert(false && "Expected section not found in index");
  84     return 0;
  85   }
  86   unsigned size() const { return Map.size(); }
  87 };
  88
  89 /// "Single point of truth" for the ELF file construction.
  90 /// TODO: This class still has a ways to go before it is truly a "single
  91 /// point of truth".
  92 template <class ELFT> class ELFState {
  93   typedef typename ELFT::Ehdr Elf_Ehdr;
  94   typedef typename ELFT::Phdr Elf_Phdr;
  95   typedef typename ELFT::Shdr Elf_Shdr;
  96   typedef typename ELFT::Sym Elf_Sym;
  97   typedef typename ELFT::Rel Elf_Rel;
  98   typedef typename ELFT::Rela Elf_Rela;
  99   typedef typename ELFT::Relr Elf_Relr;
 100   typedef typename ELFT::Dyn Elf_Dyn;
 101
 102   enum class SymtabType { Static, Dynamic };
 103
 104   /// The future ".strtab" section.
 105   StringTableBuilder DotStrtab{StringTableBuilder::ELF};
 106
 107   /// The future ".shstrtab" section.
 108   StringTableBuilder DotShStrtab{StringTableBuilder::ELF};
 109
 110   /// The future ".dynstr" section.
 111   StringTableBuilder DotDynstr{StringTableBuilder::ELF};
 112
 113   NameToIdxMap SN2I;
 114   NameToIdxMap SymN2I;
 115   NameToIdxMap DynSymN2I;
 116   ELFYAML::Object &Doc;
 117
 118   bool HasError = false;
 119   yaml::ErrorHandler ErrHandler;
 120   void reportError(const Twine &Msg);
 121
 122   std::vector<Elf_Sym> toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
 123                                     const StringTableBuilder &Strtab);
 124   unsigned toSectionIndex(StringRef S, StringRef LocSec, StringRef LocSym = "");
 125   unsigned toSymbolIndex(StringRef S, StringRef LocSec, bool IsDynamic);
 126
 127   void buildSectionIndex();
 128   void buildSymbolIndexes();
 129   void initProgramHeaders(std::vector<Elf_Phdr> &PHeaders);
 130   bool initImplicitHeader(ContiguousBlobAccumulator &CBA, Elf_Shdr &Header,
 131                           StringRef SecName, ELFYAML::Section *YAMLSec);
 132   void initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
 133                           ContiguousBlobAccumulator &CBA);
 134   void initSymtabSectionHeader(Elf_Shdr &SHeader, SymtabType STType,
 135                                ContiguousBlobAccumulator &CBA,
 136                                ELFYAML::Section *YAMLSec);
 137   void initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
 138                                StringTableBuilder &STB,
 139                                ContiguousBlobAccumulator &CBA,
 140                                ELFYAML::Section *YAMLSec);
 141   void setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
 142                               std::vector<Elf_Shdr> &SHeaders);
 143   void finalizeStrings();
 144   void writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS);
 145   void writeSectionContent(Elf_Shdr &SHeader,
 146                            const ELFYAML::RawContentSection &Section,
 147                            ContiguousBlobAccumulator &CBA);
 148   void writeSectionContent(Elf_Shdr &SHeader,
 149                            const ELFYAML::RelocationSection &Section,
 150                            ContiguousBlobAccumulator &CBA);
 151   void writeSectionContent(Elf_Shdr &SHeader, const ELFYAML::Group &Group,
 152                            ContiguousBlobAccumulator &CBA);
 153   void writeSectionContent(Elf_Shdr &SHeader,
 154                            const ELFYAML::SymtabShndxSection &Shndx,
 155                            ContiguousBlobAccumulator &CBA);
 156   void writeSectionContent(Elf_Shdr &SHeader,
 157                            const ELFYAML::SymverSection &Section,
 158                            ContiguousBlobAccumulator &CBA);
 159   void writeSectionContent(Elf_Shdr &SHeader,
 160                            const ELFYAML::VerneedSection &Section,
 161                            ContiguousBlobAccumulator &CBA);
 162   void writeSectionContent(Elf_Shdr &SHeader,
 163                            const ELFYAML::VerdefSection &Section,
 164                            ContiguousBlobAccumulator &CBA);
 165   void writeSectionContent(Elf_Shdr &SHeader,
 166                            const ELFYAML::MipsABIFlags &Section,
 167                            ContiguousBlobAccumulator &CBA);
 168   void writeSectionContent(Elf_Shdr &SHeader,
 169                            const ELFYAML::DynamicSection &Section,
 170                            ContiguousBlobAccumulator &CBA);
 171   void writeSectionContent(Elf_Shdr &SHeader,
 172                            const ELFYAML::StackSizesSection &Section,
 173                            ContiguousBlobAccumulator &CBA);
 174   void writeSectionContent(Elf_Shdr &SHeader,
 175                            const ELFYAML::HashSection &Section,
 176                            ContiguousBlobAccumulator &CBA);
 177   void writeSectionContent(Elf_Shdr &SHeader,
 178                            const ELFYAML::AddrsigSection &Section,
 179                            ContiguousBlobAccumulator &CBA);
 180
 181   ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH);
 182
 183 public:
 184   static bool writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
 185                        yaml::ErrorHandler EH);
 186 };
 187 } // end anonymous namespace
 188
 189 template <class T> static size_t arrayDataSize(ArrayRef<T> A) {
 190   return A.size() * sizeof(T);
 191 }
 192
 193 template <class T> static void writeArrayData(raw_ostream &OS, ArrayRef<T> A) {
 194   OS.write((const char *)A.data(), arrayDataSize(A));
 195 }
 196
 197 template <class T> static void zero(T &Obj) { memset(&Obj, 0, sizeof(Obj)); }
 198
 199 template <class ELFT>
 200 ELFState<ELFT>::ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH)
 201     : Doc(D), ErrHandler(EH) {
 202   StringSet<> DocSections;
 203   for (std::unique_ptr<ELFYAML::Section> &D : Doc.Sections)
 204     if (!D->Name.empty())
 205       DocSections.insert(D->Name);
 206
 207   // Insert SHT_NULL section implicitly when it is not defined in YAML.
 208   if (Doc.Sections.empty() || Doc.Sections.front()->Type != ELF::SHT_NULL)
 209     Doc.Sections.insert(
 210         Doc.Sections.begin(),
 211         std::make_unique<ELFYAML::Section>(
 212             ELFYAML::Section::SectionKind::RawContent, /*IsImplicit=*/true));
 213
 214   std::vector<StringRef> ImplicitSections = {".symtab", ".strtab", ".shstrtab"};
 215   if (!Doc.DynamicSymbols.empty())
 216     ImplicitSections.insert(ImplicitSections.end(), {".dynsym", ".dynstr"});
 217
 218   // Insert placeholders for implicit sections that are not
 219   // defined explicitly in YAML.
 220   for (StringRef SecName : ImplicitSections) {
 221     if (DocSections.count(SecName))
 222       continue;
 223
 224     std::unique_ptr<ELFYAML::Section> Sec = std::make_unique<ELFYAML::Section>(
 225         ELFYAML::Section::SectionKind::RawContent, true /*IsImplicit*/);
 226     Sec->Name = SecName;
 227     Doc.Sections.push_back(std::move(Sec));
 228   }
 229 }
 230
 231 template <class ELFT>
 232 void ELFState<ELFT>::writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS) {
 233   using namespace llvm::ELF;
 234
 235   Elf_Ehdr Header;
 236   zero(Header);
 237   Header.e_ident[EI_MAG0] = 0x7f;
 238   Header.e_ident[EI_MAG1] = 'E';
 239   Header.e_ident[EI_MAG2] = 'L';
 240   Header.e_ident[EI_MAG3] = 'F';
 241   Header.e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
 242   Header.e_ident[EI_DATA] = Doc.Header.Data;
 243   Header.e_ident[EI_VERSION] = EV_CURRENT;
 244   Header.e_ident[EI_OSABI] = Doc.Header.OSABI;
 245   Header.e_ident[EI_ABIVERSION] = Doc.Header.ABIVersion;
 246   Header.e_type = Doc.Header.Type;
 247   Header.e_machine = Doc.Header.Machine;
 248   Header.e_version = EV_CURRENT;
 249   Header.e_entry = Doc.Header.Entry;
 250   Header.e_phoff = Doc.ProgramHeaders.size() ? sizeof(Header) : 0;
 251   Header.e_flags = Doc.Header.Flags;
 252   Header.e_ehsize = sizeof(Elf_Ehdr);
 253   Header.e_phentsize = Doc.ProgramHeaders.size() ? sizeof(Elf_Phdr) : 0;
 254   Header.e_phnum = Doc.ProgramHeaders.size();
 255
 256   Header.e_shentsize =
 257       Doc.Header.SHEntSize ? (uint16_t)*Doc.Header.SHEntSize : sizeof(Elf_Shdr);
 258   // Immediately following the ELF header and program headers.
 259   // Align the start of the section header and write the ELF header.
 260   uint64_t SHOff;
 261   CBA.getOSAndAlignedOffset(SHOff, sizeof(typename ELFT::uint));
 262   Header.e_shoff =
 263       Doc.Header.SHOff ? typename ELFT::uint(*Doc.Header.SHOff) : SHOff;
 264   Header.e_shnum =
 265       Doc.Header.SHNum ? (uint16_t)*Doc.Header.SHNum : Doc.Sections.size();
 266   Header.e_shstrndx = Doc.Header.SHStrNdx ? (uint16_t)*Doc.Header.SHStrNdx
 267                                           : SN2I.get(".shstrtab");
 268
 269   OS.write((const char *)&Header, sizeof(Header));
 270 }
 271
 272 template <class ELFT>
 273 void ELFState<ELFT>::initProgramHeaders(std::vector<Elf_Phdr> &PHeaders) {
 274   for (const auto &YamlPhdr : Doc.ProgramHeaders) {
 275     Elf_Phdr Phdr;
 276     Phdr.p_type = YamlPhdr.Type;
 277     Phdr.p_flags = YamlPhdr.Flags;
 278     Phdr.p_vaddr = YamlPhdr.VAddr;
 279     Phdr.p_paddr = YamlPhdr.PAddr;
 280     PHeaders.push_back(Phdr);
 281   }
 282 }
 283
 284 template <class ELFT>
 285 unsigned ELFState<ELFT>::toSectionIndex(StringRef S, StringRef LocSec,
 286                                         StringRef LocSym) {
 287   unsigned Index;
 288   if (SN2I.lookup(S, Index) || to_integer(S, Index))
 289     return Index;
 290
 291   assert(LocSec.empty() || LocSym.empty());
 292   if (!LocSym.empty())
 293     reportError("unknown section referenced: '" + S + "' by YAML symbol '" +
 294                 LocSym + "'");
 295   else
 296     reportError("unknown section referenced: '" + S + "' by YAML section '" +
 297                 LocSec + "'");
 298   return 0;
 299 }
 300
 301 template <class ELFT>
 302 unsigned ELFState<ELFT>::toSymbolIndex(StringRef S, StringRef LocSec,
 303                                        bool IsDynamic) {
 304   const NameToIdxMap &SymMap = IsDynamic ? DynSymN2I : SymN2I;
 305   unsigned Index;
 306   // Here we try to look up S in the symbol table. If it is not there,
 307   // treat its value as a symbol index.
 308   if (!SymMap.lookup(S, Index) && !to_integer(S, Index)) {
 309     reportError("unknown symbol referenced: '" + S + "' by YAML section '" +
 310                 LocSec + "'");
 311     return 0;
 312   }
 313   return Index;
 314 }
 315
 316 template <class ELFT>
 317 bool ELFState<ELFT>::initImplicitHeader(ContiguousBlobAccumulator &CBA,
 318                                         Elf_Shdr &Header, StringRef SecName,
 319                                         ELFYAML::Section *YAMLSec) {
 320   // Check if the header was already initialized.
 321   if (Header.sh_offset)
 322     return false;
 323
 324   if (SecName == ".symtab")
 325     initSymtabSectionHeader(Header, SymtabType::Static, CBA, YAMLSec);
 326   else if (SecName == ".strtab")
 327     initStrtabSectionHeader(Header, SecName, DotStrtab, CBA, YAMLSec);
 328   else if (SecName == ".shstrtab")
 329     initStrtabSectionHeader(Header, SecName, DotShStrtab, CBA, YAMLSec);
 330   else if (SecName == ".dynsym")
 331     initSymtabSectionHeader(Header, SymtabType::Dynamic, CBA, YAMLSec);
 332   else if (SecName == ".dynstr")
 333     initStrtabSectionHeader(Header, SecName, DotDynstr, CBA, YAMLSec);
 334   else
 335     return false;
 336
 337   // Override the fields if requested.
 338   if (YAMLSec) {
 339     if (YAMLSec->ShName)
 340       Header.sh_name = *YAMLSec->ShName;
 341     if (YAMLSec->ShOffset)
 342       Header.sh_offset = *YAMLSec->ShOffset;
 343     if (YAMLSec->ShSize)
 344       Header.sh_size = *YAMLSec->ShSize;
 345   }
 346
 347   return true;
 348 }
 349
 350 StringRef llvm::ELFYAML::dropUniqueSuffix(StringRef S) {
 351   size_t SuffixPos = S.rfind(" [");
 352   if (SuffixPos == StringRef::npos)
 353     return S;
 354   return S.substr(0, SuffixPos);
 355 }
 356
 357 template <class ELFT>
 358 void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
 359                                         ContiguousBlobAccumulator &CBA) {
 360   // Ensure SHN_UNDEF entry is present. An all-zero section header is a
 361   // valid SHN_UNDEF entry since SHT_NULL == 0.
 362   SHeaders.resize(Doc.Sections.size());
 363
 364   for (size_t I = 0; I < Doc.Sections.size(); ++I) {
 365     ELFYAML::Section *Sec = Doc.Sections[I].get();
 366     if (I == 0 && Sec->IsImplicit)
 367       continue;
 368
 369     // We have a few sections like string or symbol tables that are usually
 370     // added implicitly to the end. However, if they are explicitly specified
 371     // in the YAML, we need to write them here. This ensures the file offset
 372     // remains correct.
 373     Elf_Shdr &SHeader = SHeaders[I];
 374     if (initImplicitHeader(CBA, SHeader, Sec->Name,
 375                            Sec->IsImplicit ? nullptr : Sec))
 376       continue;
 377
 378     assert(Sec && "It can't be null unless it is an implicit section. But all "
 379                   "implicit sections should already have been handled above.");
 380
 381     SHeader.sh_name =
 382         DotShStrtab.getOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
 383     SHeader.sh_type = Sec->Type;
 384     if (Sec->Flags)
 385       SHeader.sh_flags = *Sec->Flags;
 386     SHeader.sh_addr = Sec->Address;
 387     SHeader.sh_addralign = Sec->AddressAlign;
 388
 389     if (!Sec->Link.empty())
 390       SHeader.sh_link = toSectionIndex(Sec->Link, Sec->Name);
 391
 392     if (I == 0) {
 393       if (auto RawSec = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
 394         // We do not write any content for special SHN_UNDEF section.
 395         if (RawSec->Size)
 396           SHeader.sh_size = *RawSec->Size;
 397         if (RawSec->Info)
 398           SHeader.sh_info = *RawSec->Info;
 399       }
 400       if (Sec->EntSize)
 401         SHeader.sh_entsize = *Sec->EntSize;
 402     } else if (auto S = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
 403       writeSectionContent(SHeader, *S, CBA);
 404     } else if (auto S = dyn_cast<ELFYAML::SymtabShndxSection>(Sec)) {
 405       writeSectionContent(SHeader, *S, CBA);
 406     } else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec)) {
 407       writeSectionContent(SHeader, *S, CBA);
 408     } else if (auto S = dyn_cast<ELFYAML::Group>(Sec)) {
 409       writeSectionContent(SHeader, *S, CBA);
 410     } else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec)) {
 411       writeSectionContent(SHeader, *S, CBA);
 412     } else if (auto S = dyn_cast<ELFYAML::NoBitsSection>(Sec)) {
 413       SHeader.sh_entsize = 0;
 414       SHeader.sh_size = S->Size;
 415       // SHT_NOBITS section does not have content
 416       // so just to setup the section offset.
 417       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 418     } else if (auto S = dyn_cast<ELFYAML::DynamicSection>(Sec)) {
 419       writeSectionContent(SHeader, *S, CBA);
 420     } else if (auto S = dyn_cast<ELFYAML::SymverSection>(Sec)) {
 421       writeSectionContent(SHeader, *S, CBA);
 422     } else if (auto S = dyn_cast<ELFYAML::VerneedSection>(Sec)) {
 423       writeSectionContent(SHeader, *S, CBA);
 424     } else if (auto S = dyn_cast<ELFYAML::VerdefSection>(Sec)) {
 425       writeSectionContent(SHeader, *S, CBA);
 426     } else if (auto S = dyn_cast<ELFYAML::StackSizesSection>(Sec)) {
 427       writeSectionContent(SHeader, *S, CBA);
 428     } else if (auto S = dyn_cast<ELFYAML::HashSection>(Sec)) {
 429       writeSectionContent(SHeader, *S, CBA);
 430     } else if (auto S = dyn_cast<ELFYAML::AddrsigSection>(Sec)) {
 431       writeSectionContent(SHeader, *S, CBA);
 432     } else {
 433       llvm_unreachable("Unknown section type");
 434     }
 435
 436     // Override the fields if requested.
 437     if (Sec) {
 438       if (Sec->ShName)
 439         SHeader.sh_name = *Sec->ShName;
 440       if (Sec->ShOffset)
 441         SHeader.sh_offset = *Sec->ShOffset;
 442       if (Sec->ShSize)
 443         SHeader.sh_size = *Sec->ShSize;
 444     }
 445   }
 446 }
 447
 448 static size_t findFirstNonGlobal(ArrayRef<ELFYAML::Symbol> Symbols) {
 449   for (size_t I = 0; I < Symbols.size(); ++I)
 450     if (Symbols[I].Binding.value != ELF::STB_LOCAL)
 451       return I;
 452   return Symbols.size();
 453 }
 454
 455 static uint64_t writeContent(raw_ostream &OS,
 456                              const Optional<yaml::BinaryRef> &Content,
 457                              const Optional<llvm::yaml::Hex64> &Size) {
 458   size_t ContentSize = 0;
 459   if (Content) {
 460     Content->writeAsBinary(OS);
 461     ContentSize = Content->binary_size();
 462   }
 463
 464   if (!Size)
 465     return ContentSize;
 466
 467   OS.write_zeros(*Size - ContentSize);
 468   return *Size;
 469 }
 470
 471 template <class ELFT>
 472 std::vector<typename ELFT::Sym>
 473 ELFState<ELFT>::toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
 474                              const StringTableBuilder &Strtab) {
 475   std::vector<Elf_Sym> Ret;
 476   Ret.resize(Symbols.size() + 1);
 477
 478   size_t I = 0;
 479   for (const auto &Sym : Symbols) {
 480     Elf_Sym &Symbol = Ret[++I];
 481
 482     // If NameIndex, which contains the name offset, is explicitly specified, we
 483     // use it. This is useful for preparing broken objects. Otherwise, we add
 484     // the specified Name to the string table builder to get its offset.
 485     if (Sym.NameIndex)
 486       Symbol.st_name = *Sym.NameIndex;
 487     else if (!Sym.Name.empty())
 488       Symbol.st_name = Strtab.getOffset(ELFYAML::dropUniqueSuffix(Sym.Name));
 489
 490     Symbol.setBindingAndType(Sym.Binding, Sym.Type);
 491     if (!Sym.Section.empty())
 492       Symbol.st_shndx = toSectionIndex(Sym.Section, "", Sym.Name);
 493     else if (Sym.Index)
 494       Symbol.st_shndx = *Sym.Index;
 495
 496     Symbol.st_value = Sym.Value;
 497     Symbol.st_other = Sym.Other ? *Sym.Other : 0;
 498     Symbol.st_size = Sym.Size;
 499   }
 500
 501   return Ret;
 502 }
 503
 504 template <class ELFT>
 505 void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
 506                                              SymtabType STType,
 507                                              ContiguousBlobAccumulator &CBA,
 508                                              ELFYAML::Section *YAMLSec) {
 509
 510   bool IsStatic = STType == SymtabType::Static;
 511   const auto &Symbols = IsStatic ? Doc.Symbols : Doc.DynamicSymbols;
 512
 513   ELFYAML::RawContentSection *RawSec =
 514       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
 515   if (RawSec && !Symbols.empty() && (RawSec->Content || RawSec->Size)) {
 516     if (RawSec->Content)
 517       reportError("cannot specify both `Content` and " +
 518                   (IsStatic ? Twine("`Symbols`") : Twine("`DynamicSymbols`")) +
 519                   " for symbol table section '" + RawSec->Name + "'");
 520     if (RawSec->Size)
 521       reportError("cannot specify both `Size` and " +
 522                   (IsStatic ? Twine("`Symbols`") : Twine("`DynamicSymbols`")) +
 523                   " for symbol table section '" + RawSec->Name + "'");
 524     return;
 525   }
 526
 527   zero(SHeader);
 528   SHeader.sh_name = DotShStrtab.getOffset(IsStatic ? ".symtab" : ".dynsym");
 529
 530   if (YAMLSec)
 531     SHeader.sh_type = YAMLSec->Type;
 532   else
 533     SHeader.sh_type = IsStatic ? ELF::SHT_SYMTAB : ELF::SHT_DYNSYM;
 534
 535   if (RawSec && !RawSec->Link.empty()) {
 536     // If the Link field is explicitly defined in the document,
 537     // we should use it.
 538     SHeader.sh_link = toSectionIndex(RawSec->Link, RawSec->Name);
 539   } else {
 540     // When we describe the .dynsym section in the document explicitly, it is
 541     // allowed to omit the "DynamicSymbols" tag. In this case .dynstr is not
 542     // added implicitly and we should be able to leave the Link zeroed if
 543     // .dynstr is not defined.
 544     unsigned Link = 0;
 545     if (IsStatic)
 546       Link = SN2I.get(".strtab");
 547     else
 548       SN2I.lookup(".dynstr", Link);
 549     SHeader.sh_link = Link;
 550   }
 551
 552   if (YAMLSec && YAMLSec->Flags)
 553     SHeader.sh_flags = *YAMLSec->Flags;
 554   else if (!IsStatic)
 555     SHeader.sh_flags = ELF::SHF_ALLOC;
 556
 557   // If the symbol table section is explicitly described in the YAML
 558   // then we should set the fields requested.
 559   SHeader.sh_info = (RawSec && RawSec->Info) ? (unsigned)(*RawSec->Info)
 560                                              : findFirstNonGlobal(Symbols) + 1;
 561   SHeader.sh_entsize = (YAMLSec && YAMLSec->EntSize)
 562                            ? (uint64_t)(*YAMLSec->EntSize)
 563                            : sizeof(Elf_Sym);
 564   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 8;
 565   SHeader.sh_addr = YAMLSec ? (uint64_t)YAMLSec->Address : 0;
 566
 567   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 568   if (RawSec && (RawSec->Content || RawSec->Size)) {
 569     assert(Symbols.empty());
 570     SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
 571     return;
 572   }
 573
 574   std::vector<Elf_Sym> Syms =
 575       toELFSymbols(Symbols, IsStatic ? DotStrtab : DotDynstr);
 576   writeArrayData(OS, makeArrayRef(Syms));
 577   SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
 578 }
 579
 580 template <class ELFT>
 581 void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
 582                                              StringTableBuilder &STB,
 583                                              ContiguousBlobAccumulator &CBA,
 584                                              ELFYAML::Section *YAMLSec) {
 585   zero(SHeader);
 586   SHeader.sh_name = DotShStrtab.getOffset(Name);
 587   SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_STRTAB;
 588   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
 589
 590   ELFYAML::RawContentSection *RawSec =
 591       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
 592
 593   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 594   if (RawSec && (RawSec->Content || RawSec->Size)) {
 595     SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
 596   } else {
 597     STB.write(OS);
 598     SHeader.sh_size = STB.getSize();
 599   }
 600
 601   if (YAMLSec && YAMLSec->EntSize)
 602     SHeader.sh_entsize = *YAMLSec->EntSize;
 603
 604   if (RawSec && RawSec->Info)
 605     SHeader.sh_info = *RawSec->Info;
 606
 607   if (YAMLSec && YAMLSec->Flags)
 608     SHeader.sh_flags = *YAMLSec->Flags;
 609   else if (Name == ".dynstr")
 610     SHeader.sh_flags = ELF::SHF_ALLOC;
 611
 612   // If the section is explicitly described in the YAML
 613   // then we want to use its section address.
 614   if (YAMLSec)
 615     SHeader.sh_addr = YAMLSec->Address;
 616 }
 617
 618 template <class ELFT> void ELFState<ELFT>::reportError(const Twine &Msg) {
 619   ErrHandler(Msg);
 620   HasError = true;
 621 }
 622
 623 template <class ELFT>
 624 void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
 625                                             std::vector<Elf_Shdr> &SHeaders) {
 626   uint32_t PhdrIdx = 0;
 627   for (auto &YamlPhdr : Doc.ProgramHeaders) {
 628     Elf_Phdr &PHeader = PHeaders[PhdrIdx++];
 629
 630     std::vector<Elf_Shdr *> Sections;
 631     for (const ELFYAML::SectionName &SecName : YamlPhdr.Sections) {
 632       unsigned Index;
 633       if (!SN2I.lookup(SecName.Section, Index)) {
 634         reportError("unknown section referenced: '" + SecName.Section +
 635                     "' by program header");
 636         continue;
 637       }
 638       Sections.push_back(&SHeaders[Index]);
 639     }
 640
 641     if (YamlPhdr.Offset) {
 642       PHeader.p_offset = *YamlPhdr.Offset;
 643     } else {
 644       if (YamlPhdr.Sections.size())
 645         PHeader.p_offset = UINT32_MAX;
 646       else
 647         PHeader.p_offset = 0;
 648
 649       // Find the minimum offset for the program header.
 650       for (Elf_Shdr *SHeader : Sections)
 651         PHeader.p_offset = std::min(PHeader.p_offset, SHeader->sh_offset);
 652     }
 653
 654     // Find the maximum offset of the end of a section in order to set p_filesz
 655     // and p_memsz. When setting p_filesz, trailing SHT_NOBITS sections are not
 656     // counted.
 657     uint64_t FileOffset = PHeader.p_offset, MemOffset = PHeader.p_offset;
 658     for (Elf_Shdr *SHeader : Sections) {
 659       uint64_t End = SHeader->sh_offset + SHeader->sh_size;
 660       MemOffset = std::max(MemOffset, End);
 661
 662       if (SHeader->sh_type != llvm::ELF::SHT_NOBITS)
 663         FileOffset = std::max(FileOffset, End);
 664     }
 665
 666     // Set the file size and the memory size if not set explicitly.
 667     PHeader.p_filesz = YamlPhdr.FileSize ? uint64_t(*YamlPhdr.FileSize)
 668                                          : FileOffset - PHeader.p_offset;
 669     PHeader.p_memsz = YamlPhdr.MemSize ? uint64_t(*YamlPhdr.MemSize)
 670                                        : MemOffset - PHeader.p_offset;
 671
 672     if (YamlPhdr.Align) {
 673       PHeader.p_align = *YamlPhdr.Align;
 674     } else {
 675       // Set the alignment of the segment to be the maximum alignment of the
 676       // sections so that by default the segment has a valid and sensible
 677       // alignment.
 678       PHeader.p_align = 1;
 679       for (Elf_Shdr *SHeader : Sections)
 680         PHeader.p_align = std::max(PHeader.p_align, SHeader->sh_addralign);
 681     }
 682   }
 683 }
 684
 685 template <class ELFT>
 686 void ELFState<ELFT>::writeSectionContent(
 687     Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section,
 688     ContiguousBlobAccumulator &CBA) {
 689   raw_ostream &OS =
 690       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 691   SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
 692
 693   if (Section.EntSize)
 694     SHeader.sh_entsize = *Section.EntSize;
 695   else if (Section.Type == llvm::ELF::SHT_RELR)
 696     SHeader.sh_entsize = sizeof(Elf_Relr);
 697   else
 698     SHeader.sh_entsize = 0;
 699
 700   if (Section.Info)
 701     SHeader.sh_info = *Section.Info;
 702 }
 703
 704 static bool isMips64EL(const ELFYAML::Object &Doc) {
 705   return Doc.Header.Machine == ELFYAML::ELF_EM(llvm::ELF::EM_MIPS) &&
 706          Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64) &&
 707          Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
 708 }
 709
 710 template <class ELFT>
 711 void ELFState<ELFT>::writeSectionContent(
 712     Elf_Shdr &SHeader, const ELFYAML::RelocationSection &Section,
 713     ContiguousBlobAccumulator &CBA) {
 714   assert((Section.Type == llvm::ELF::SHT_REL ||
 715           Section.Type == llvm::ELF::SHT_RELA) &&
 716          "Section type is not SHT_REL nor SHT_RELA");
 717
 718   bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
 719   SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
 720   SHeader.sh_size = SHeader.sh_entsize * Section.Relocations.size();
 721
 722   // For relocation section set link to .symtab by default.
 723   if (Section.Link.empty())
 724     SHeader.sh_link = SN2I.get(".symtab");
 725
 726   if (!Section.RelocatableSec.empty())
 727     SHeader.sh_info = toSectionIndex(Section.RelocatableSec, Section.Name);
 728
 729   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 730   for (const auto &Rel : Section.Relocations) {
 731     unsigned SymIdx = Rel.Symbol ? toSymbolIndex(*Rel.Symbol, Section.Name,
 732                                                  Section.Link == ".dynsym")
 733                                  : 0;
 734     if (IsRela) {
 735       Elf_Rela REntry;
 736       zero(REntry);
 737       REntry.r_offset = Rel.Offset;
 738       REntry.r_addend = Rel.Addend;
 739       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
 740       OS.write((const char *)&REntry, sizeof(REntry));
 741     } else {
 742       Elf_Rel REntry;
 743       zero(REntry);
 744       REntry.r_offset = Rel.Offset;
 745       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
 746       OS.write((const char *)&REntry, sizeof(REntry));
 747     }
 748   }
 749 }
 750
 751 template <class ELFT>
 752 void 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 }
 764
 765 template <class ELFT>
 766 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 767                                          const ELFYAML::Group &Section,
 768                                          ContiguousBlobAccumulator &CBA) {
 769   assert(Section.Type == llvm::ELF::SHT_GROUP &&
 770          "Section type is not SHT_GROUP");
 771
 772   SHeader.sh_entsize = 4;
 773   SHeader.sh_size = SHeader.sh_entsize * Section.Members.size();
 774   SHeader.sh_info =
 775       toSymbolIndex(Section.Signature, Section.Name, /*IsDynamic=*/false);
 776
 777   raw_ostream &OS =
 778       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 779
 780   for (const ELFYAML::SectionOrType &Member : Section.Members) {
 781     unsigned int SectionIndex = 0;
 782     if (Member.sectionNameOrType == "GRP_COMDAT")
 783       SectionIndex = llvm::ELF::GRP_COMDAT;
 784     else
 785       SectionIndex = toSectionIndex(Member.sectionNameOrType, Section.Name);
 786     support::endian::write<uint32_t>(OS, SectionIndex, ELFT::TargetEndianness);
 787   }
 788 }
 789
 790 template <class ELFT>
 791 void 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 }
 802
 803 template <class ELFT>
 804 void ELFState<ELFT>::writeSectionContent(
 805     Elf_Shdr &SHeader, const ELFYAML::StackSizesSection &Section,
 806     ContiguousBlobAccumulator &CBA) {
 807   using uintX_t = typename ELFT::uint;
 808   raw_ostream &OS =
 809       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 810
 811   if (Section.Content || Section.Size) {
 812     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
 813     return;
 814   }
 815
 816   for (const ELFYAML::StackSizeEntry &E : *Section.Entries) {
 817     support::endian::write<uintX_t>(OS, E.Address, ELFT::TargetEndianness);
 818     SHeader.sh_size += sizeof(uintX_t) + encodeULEB128(E.Size, OS);
 819   }
 820 }
 821
 822 template <class ELFT>
 823 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 824                                          const ELFYAML::HashSection &Section,
 825                                          ContiguousBlobAccumulator &CBA) {
 826   raw_ostream &OS =
 827       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 828
 829   unsigned Link = 0;
 830   if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
 831     SHeader.sh_link = Link;
 832
 833   if (Section.Content || Section.Size) {
 834     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
 835     return;
 836   }
 837
 838   support::endian::write<uint32_t>(OS, Section.Bucket->size(),
 839                                    ELFT::TargetEndianness);
 840   support::endian::write<uint32_t>(OS, Section.Chain->size(),
 841                                    ELFT::TargetEndianness);
 842   for (uint32_t Val : *Section.Bucket)
 843     support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
 844   for (uint32_t Val : *Section.Chain)
 845     support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
 846
 847   SHeader.sh_size = (2 + Section.Bucket->size() + Section.Chain->size()) * 4;
 848 }
 849
 850 template <class ELFT>
 851 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 852                                          const ELFYAML::VerdefSection &Section,
 853                                          ContiguousBlobAccumulator &CBA) {
 854   typedef typename ELFT::Verdef Elf_Verdef;
 855   typedef typename ELFT::Verdaux Elf_Verdaux;
 856   raw_ostream &OS =
 857       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 858
 859   uint64_t AuxCnt = 0;
 860   for (size_t I = 0; I < Section.Entries.size(); ++I) {
 861     const ELFYAML::VerdefEntry &E = Section.Entries[I];
 862
 863     Elf_Verdef VerDef;
 864     VerDef.vd_version = E.Version;
 865     VerDef.vd_flags = E.Flags;
 866     VerDef.vd_ndx = E.VersionNdx;
 867     VerDef.vd_hash = E.Hash;
 868     VerDef.vd_aux = sizeof(Elf_Verdef);
 869     VerDef.vd_cnt = E.VerNames.size();
 870     if (I == Section.Entries.size() - 1)
 871       VerDef.vd_next = 0;
 872     else
 873       VerDef.vd_next =
 874           sizeof(Elf_Verdef) + E.VerNames.size() * sizeof(Elf_Verdaux);
 875     OS.write((const char *)&VerDef, sizeof(Elf_Verdef));
 876
 877     for (size_t J = 0; J < E.VerNames.size(); ++J, ++AuxCnt) {
 878       Elf_Verdaux VernAux;
 879       VernAux.vda_name = DotDynstr.getOffset(E.VerNames[J]);
 880       if (J == E.VerNames.size() - 1)
 881         VernAux.vda_next = 0;
 882       else
 883         VernAux.vda_next = sizeof(Elf_Verdaux);
 884       OS.write((const char *)&VernAux, sizeof(Elf_Verdaux));
 885     }
 886   }
 887
 888   SHeader.sh_size = Section.Entries.size() * sizeof(Elf_Verdef) +
 889                     AuxCnt * sizeof(Elf_Verdaux);
 890   SHeader.sh_info = Section.Info;
 891 }
 892
 893 template <class ELFT>
 894 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 895                                          const ELFYAML::VerneedSection &Section,
 896                                          ContiguousBlobAccumulator &CBA) {
 897   typedef typename ELFT::Verneed Elf_Verneed;
 898   typedef typename ELFT::Vernaux Elf_Vernaux;
 899
 900   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 901
 902   uint64_t AuxCnt = 0;
 903   for (size_t I = 0; I < Section.VerneedV.size(); ++I) {
 904     const ELFYAML::VerneedEntry &VE = Section.VerneedV[I];
 905
 906     Elf_Verneed VerNeed;
 907     VerNeed.vn_version = VE.Version;
 908     VerNeed.vn_file = DotDynstr.getOffset(VE.File);
 909     if (I == Section.VerneedV.size() - 1)
 910       VerNeed.vn_next = 0;
 911     else
 912       VerNeed.vn_next =
 913           sizeof(Elf_Verneed) + VE.AuxV.size() * sizeof(Elf_Vernaux);
 914     VerNeed.vn_cnt = VE.AuxV.size();
 915     VerNeed.vn_aux = sizeof(Elf_Verneed);
 916     OS.write((const char *)&VerNeed, sizeof(Elf_Verneed));
 917
 918     for (size_t J = 0; J < VE.AuxV.size(); ++J, ++AuxCnt) {
 919       const ELFYAML::VernauxEntry &VAuxE = VE.AuxV[J];
 920
 921       Elf_Vernaux VernAux;
 922       VernAux.vna_hash = VAuxE.Hash;
 923       VernAux.vna_flags = VAuxE.Flags;
 924       VernAux.vna_other = VAuxE.Other;
 925       VernAux.vna_name = DotDynstr.getOffset(VAuxE.Name);
 926       if (J == VE.AuxV.size() - 1)
 927         VernAux.vna_next = 0;
 928       else
 929         VernAux.vna_next = sizeof(Elf_Vernaux);
 930       OS.write((const char *)&VernAux, sizeof(Elf_Vernaux));
 931     }
 932   }
 933
 934   SHeader.sh_size = Section.VerneedV.size() * sizeof(Elf_Verneed) +
 935                     AuxCnt * sizeof(Elf_Vernaux);
 936   SHeader.sh_info = Section.Info;
 937 }
 938
 939 template <class ELFT>
 940 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 941                                          const ELFYAML::MipsABIFlags &Section,
 942                                          ContiguousBlobAccumulator &CBA) {
 943   assert(Section.Type == llvm::ELF::SHT_MIPS_ABIFLAGS &&
 944          "Section type is not SHT_MIPS_ABIFLAGS");
 945
 946   object::Elf_Mips_ABIFlags<ELFT> Flags;
 947   zero(Flags);
 948   SHeader.sh_entsize = sizeof(Flags);
 949   SHeader.sh_size = SHeader.sh_entsize;
 950
 951   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 952   Flags.version = Section.Version;
 953   Flags.isa_level = Section.ISALevel;
 954   Flags.isa_rev = Section.ISARevision;
 955   Flags.gpr_size = Section.GPRSize;
 956   Flags.cpr1_size = Section.CPR1Size;
 957   Flags.cpr2_size = Section.CPR2Size;
 958   Flags.fp_abi = Section.FpABI;
 959   Flags.isa_ext = Section.ISAExtension;
 960   Flags.ases = Section.ASEs;
 961   Flags.flags1 = Section.Flags1;
 962   Flags.flags2 = Section.Flags2;
 963   OS.write((const char *)&Flags, sizeof(Flags));
 964 }
 965
 966 template <class ELFT>
 967 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 968                                          const ELFYAML::DynamicSection &Section,
 969                                          ContiguousBlobAccumulator &CBA) {
 970   typedef typename ELFT::uint uintX_t;
 971
 972   assert(Section.Type == llvm::ELF::SHT_DYNAMIC &&
 973          "Section type is not SHT_DYNAMIC");
 974
 975   if (!Section.Entries.empty() && Section.Content)
 976     reportError("cannot specify both raw content and explicit entries "
 977                 "for dynamic section '" +
 978                 Section.Name + "'");
 979
 980   if (Section.Content)
 981     SHeader.sh_size = Section.Content->binary_size();
 982   else
 983     SHeader.sh_size = 2 * sizeof(uintX_t) * Section.Entries.size();
 984   if (Section.EntSize)
 985     SHeader.sh_entsize = *Section.EntSize;
 986   else
 987     SHeader.sh_entsize = sizeof(Elf_Dyn);
 988
 989   raw_ostream &OS =
 990       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 991   for (const ELFYAML::DynamicEntry &DE : Section.Entries) {
 992     support::endian::write<uintX_t>(OS, DE.Tag, ELFT::TargetEndianness);
 993     support::endian::write<uintX_t>(OS, DE.Val, ELFT::TargetEndianness);
 994   }
 995   if (Section.Content)
 996     Section.Content->writeAsBinary(OS);
 997 }
 998
 999 template <class ELFT>
1000 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
1001                                          const ELFYAML::AddrsigSection &Section,
1002                                          ContiguousBlobAccumulator &CBA) {
1003   raw_ostream &OS =
1004       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1005
1006   unsigned Link = 0;
1007   if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
1008     SHeader.sh_link = Link;
1009
1010   if (Section.Content) {
1011     SHeader.sh_size = writeContent(OS, Section.Content, None);
1012     return;
1013   }
1014
1015   for (const ELFYAML::AddrsigSymbol &Sym : *Section.Symbols) {
1016     uint64_t Val =
1017         Sym.Name ? toSymbolIndex(*Sym.Name, Section.Name, /*IsDynamic=*/false)
1018                  : (uint32_t)*Sym.Index;
1019     SHeader.sh_size += encodeULEB128(Val, OS);
1020   }
1021 }
1022
1023 template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
1024   for (unsigned I = 0, E = Doc.Sections.size(); I != E; ++I) {
1025     StringRef Name = Doc.Sections[I]->Name;
1026     if (Name.empty())
1027       continue;
1028
1029     DotShStrtab.add(ELFYAML::dropUniqueSuffix(Name));
1030     if (!SN2I.addName(Name, I))
1031       reportError("repeated section name: '" + Name +
1032                   "' at YAML section number " + Twine(I));
1033   }
1034
1035   DotShStrtab.finalize();
1036 }
1037
1038 template <class ELFT> void ELFState<ELFT>::buildSymbolIndexes() {
1039   auto Build = [this](ArrayRef<ELFYAML::Symbol> V, NameToIdxMap &Map) {
1040     for (size_t I = 0, S = V.size(); I < S; ++I) {
1041       const ELFYAML::Symbol &Sym = V[I];
1042       if (!Sym.Name.empty() && !Map.addName(Sym.Name, I + 1))
1043         reportError("repeated symbol name: '" + Sym.Name + "'");
1044     }
1045   };
1046
1047   Build(Doc.Symbols, SymN2I);
1048   Build(Doc.DynamicSymbols, DynSymN2I);
1049 }
1050
1051 template <class ELFT> void ELFState<ELFT>::finalizeStrings() {
1052   // Add the regular symbol names to .strtab section.
1053   for (const ELFYAML::Symbol &Sym : Doc.Symbols)
1054     DotStrtab.add(ELFYAML::dropUniqueSuffix(Sym.Name));
1055   DotStrtab.finalize();
1056
1057   // Add the dynamic symbol names to .dynstr section.
1058   for (const ELFYAML::Symbol &Sym : Doc.DynamicSymbols)
1059     DotDynstr.add(ELFYAML::dropUniqueSuffix(Sym.Name));
1060
1061   // SHT_GNU_verdef and SHT_GNU_verneed sections might also
1062   // add strings to .dynstr section.
1063   for (const std::unique_ptr<ELFYAML::Section> &Sec : Doc.Sections) {
1064     if (auto VerNeed = dyn_cast<ELFYAML::VerneedSection>(Sec.get())) {
1065       for (const ELFYAML::VerneedEntry &VE : VerNeed->VerneedV) {
1066         DotDynstr.add(VE.File);
1067         for (const ELFYAML::VernauxEntry &Aux : VE.AuxV)
1068           DotDynstr.add(Aux.Name);
1069       }
1070     } else if (auto VerDef = dyn_cast<ELFYAML::VerdefSection>(Sec.get())) {
1071       for (const ELFYAML::VerdefEntry &E : VerDef->Entries)
1072         for (StringRef Name : E.VerNames)
1073           DotDynstr.add(Name);
1074     }
1075   }
1076
1077   DotDynstr.finalize();
1078 }
1079
1080 template <class ELFT>
1081 bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
1082                               yaml::ErrorHandler EH) {
1083   ELFState<ELFT> State(Doc, EH);
1084
1085   // Finalize .strtab and .dynstr sections. We do that early because want to
1086   // finalize the string table builders before writing the content of the
1087   // sections that might want to use them.
1088   State.finalizeStrings();
1089
1090   State.buildSectionIndex();
1091   State.buildSymbolIndexes();
1092
1093   std::vector<Elf_Phdr> PHeaders;
1094   State.initProgramHeaders(PHeaders);
1095
1096   // XXX: This offset is tightly coupled with the order that we write
1097   // things to `OS`.
1098   const size_t SectionContentBeginOffset =
1099       sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * Doc.ProgramHeaders.size();
1100   ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
1101
1102   std::vector<Elf_Shdr> SHeaders;
1103   State.initSectionHeaders(SHeaders, CBA);
1104
1105   // Now we can decide segment offsets
1106   State.setProgramHeaderLayout(PHeaders, SHeaders);
1107
1108   if (State.HasError)
1109     return false;
1110
1111   State.writeELFHeader(CBA, OS);
1112   writeArrayData(OS, makeArrayRef(PHeaders));
1113   CBA.writeBlobToStream(OS);
1114   writeArrayData(OS, makeArrayRef(SHeaders));
1115   return true;
1116 }
1117
1118 namespace llvm {
1119 namespace yaml {
1120
1121 bool yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out, ErrorHandler EH) {
1122   bool IsLE = Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
1123   bool Is64Bit = Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
1124   if (Is64Bit) {
1125     if (IsLE)
1126       return ELFState<object::ELF64LE>::writeELF(Out, Doc, EH);
1127     return ELFState<object::ELF64BE>::writeELF(Out, Doc, EH);
1128   }
1129   if (IsLE)
1130     return ELFState<object::ELF32LE>::writeELF(Out, Doc, EH);
1131   return ELFState<object::ELF32BE>::writeELF(Out, Doc, EH);
1132 }
1133
1134 } // namespace yaml
1135 } // namespace llvm