xref: /freebsd/contrib/llvm-project/llvm/lib/ObjectYAML/ELFEmitter.cpp (revision 85868e8a1daeaae7a0e48effb2ea2310ae3b02c6) 
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     // Some sections wants to link to .symtab by default.
208     // That means we want to create the symbol table for them.
209     if (D->Type == llvm::ELF::SHT_REL || D->Type == llvm::ELF::SHT_RELA)
210       if (!Doc.Symbols && D->Link.empty())
211         Doc.Symbols.emplace();
212   }
213 
214   // Insert SHT_NULL section implicitly when it is not defined in YAML.
215   if (Doc.Sections.empty() || Doc.Sections.front()->Type != ELF::SHT_NULL)
216     Doc.Sections.insert(
217         Doc.Sections.begin(),
218         std::make_unique<ELFYAML::Section>(
219             ELFYAML::Section::SectionKind::RawContent, /*IsImplicit=*/true));
220 
221   std::vector<StringRef> ImplicitSections;
222   if (Doc.Symbols)
223     ImplicitSections.push_back(".symtab");
224   ImplicitSections.insert(ImplicitSections.end(), {".strtab", ".shstrtab"});
225 
226   if (!Doc.DynamicSymbols.empty())
227     ImplicitSections.insert(ImplicitSections.end(), {".dynsym", ".dynstr"});
228 
229   // Insert placeholders for implicit sections that are not
230   // defined explicitly in YAML.
231   for (StringRef SecName : ImplicitSections) {
232     if (DocSections.count(SecName))
233       continue;
234 
235     std::unique_ptr<ELFYAML::Section> Sec = std::make_unique<ELFYAML::Section>(
236         ELFYAML::Section::SectionKind::RawContent, true /*IsImplicit*/);
237     Sec->Name = SecName;
238     Doc.Sections.push_back(std::move(Sec));
239   }
240 }
241 
242 template <class ELFT>
243 void ELFState<ELFT>::writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS) {
244   using namespace llvm::ELF;
245 
246   Elf_Ehdr Header;
247   zero(Header);
248   Header.e_ident[EI_MAG0] = 0x7f;
249   Header.e_ident[EI_MAG1] = 'E';
250   Header.e_ident[EI_MAG2] = 'L';
251   Header.e_ident[EI_MAG3] = 'F';
252   Header.e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
253   Header.e_ident[EI_DATA] = Doc.Header.Data;
254   Header.e_ident[EI_VERSION] = EV_CURRENT;
255   Header.e_ident[EI_OSABI] = Doc.Header.OSABI;
256   Header.e_ident[EI_ABIVERSION] = Doc.Header.ABIVersion;
257   Header.e_type = Doc.Header.Type;
258   Header.e_machine = Doc.Header.Machine;
259   Header.e_version = EV_CURRENT;
260   Header.e_entry = Doc.Header.Entry;
261   Header.e_phoff = Doc.ProgramHeaders.size() ? sizeof(Header) : 0;
262   Header.e_flags = Doc.Header.Flags;
263   Header.e_ehsize = sizeof(Elf_Ehdr);
264   Header.e_phentsize = Doc.ProgramHeaders.size() ? sizeof(Elf_Phdr) : 0;
265   Header.e_phnum = Doc.ProgramHeaders.size();
266 
267   Header.e_shentsize =
268       Doc.Header.SHEntSize ? (uint16_t)*Doc.Header.SHEntSize : sizeof(Elf_Shdr);
269   // Immediately following the ELF header and program headers.
270   // Align the start of the section header and write the ELF header.
271   uint64_t SHOff;
272   CBA.getOSAndAlignedOffset(SHOff, sizeof(typename ELFT::uint));
273   Header.e_shoff =
274       Doc.Header.SHOff ? typename ELFT::uint(*Doc.Header.SHOff) : SHOff;
275   Header.e_shnum =
276       Doc.Header.SHNum ? (uint16_t)*Doc.Header.SHNum : Doc.Sections.size();
277   Header.e_shstrndx = Doc.Header.SHStrNdx ? (uint16_t)*Doc.Header.SHStrNdx
278                                           : SN2I.get(".shstrtab");
279 
280   OS.write((const char *)&Header, sizeof(Header));
281 }
282 
283 template <class ELFT>
284 void ELFState<ELFT>::initProgramHeaders(std::vector<Elf_Phdr> &PHeaders) {
285   for (const auto &YamlPhdr : Doc.ProgramHeaders) {
286     Elf_Phdr Phdr;
287     Phdr.p_type = YamlPhdr.Type;
288     Phdr.p_flags = YamlPhdr.Flags;
289     Phdr.p_vaddr = YamlPhdr.VAddr;
290     Phdr.p_paddr = YamlPhdr.PAddr;
291     PHeaders.push_back(Phdr);
292   }
293 }
294 
295 template <class ELFT>
296 unsigned ELFState<ELFT>::toSectionIndex(StringRef S, StringRef LocSec,
297                                         StringRef LocSym) {
298   unsigned Index;
299   if (SN2I.lookup(S, Index) || to_integer(S, Index))
300     return Index;
301 
302   assert(LocSec.empty() || LocSym.empty());
303   if (!LocSym.empty())
304     reportError("unknown section referenced: '" + S + "' by YAML symbol '" +
305                 LocSym + "'");
306   else
307     reportError("unknown section referenced: '" + S + "' by YAML section '" +
308                 LocSec + "'");
309   return 0;
310 }
311 
312 template <class ELFT>
313 unsigned ELFState<ELFT>::toSymbolIndex(StringRef S, StringRef LocSec,
314                                        bool IsDynamic) {
315   const NameToIdxMap &SymMap = IsDynamic ? DynSymN2I : SymN2I;
316   unsigned Index;
317   // Here we try to look up S in the symbol table. If it is not there,
318   // treat its value as a symbol index.
319   if (!SymMap.lookup(S, Index) && !to_integer(S, Index)) {
320     reportError("unknown symbol referenced: '" + S + "' by YAML section '" +
321                 LocSec + "'");
322     return 0;
323   }
324   return Index;
325 }
326 
327 template <class ELFT>
328 bool ELFState<ELFT>::initImplicitHeader(ContiguousBlobAccumulator &CBA,
329                                         Elf_Shdr &Header, StringRef SecName,
330                                         ELFYAML::Section *YAMLSec) {
331   // Check if the header was already initialized.
332   if (Header.sh_offset)
333     return false;
334 
335   if (SecName == ".symtab")
336     initSymtabSectionHeader(Header, SymtabType::Static, CBA, YAMLSec);
337   else if (SecName == ".strtab")
338     initStrtabSectionHeader(Header, SecName, DotStrtab, CBA, YAMLSec);
339   else if (SecName == ".shstrtab")
340     initStrtabSectionHeader(Header, SecName, DotShStrtab, CBA, YAMLSec);
341   else if (SecName == ".dynsym")
342     initSymtabSectionHeader(Header, SymtabType::Dynamic, CBA, YAMLSec);
343   else if (SecName == ".dynstr")
344     initStrtabSectionHeader(Header, SecName, DotDynstr, CBA, YAMLSec);
345   else
346     return false;
347 
348   // Override the fields if requested.
349   if (YAMLSec) {
350     if (YAMLSec->ShName)
351       Header.sh_name = *YAMLSec->ShName;
352     if (YAMLSec->ShOffset)
353       Header.sh_offset = *YAMLSec->ShOffset;
354     if (YAMLSec->ShSize)
355       Header.sh_size = *YAMLSec->ShSize;
356   }
357 
358   return true;
359 }
360 
361 StringRef llvm::ELFYAML::dropUniqueSuffix(StringRef S) {
362   size_t SuffixPos = S.rfind(" [");
363   if (SuffixPos == StringRef::npos)
364     return S;
365   return S.substr(0, SuffixPos);
366 }
367 
368 template <class ELFT>
369 void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
370                                         ContiguousBlobAccumulator &CBA) {
371   // Ensure SHN_UNDEF entry is present. An all-zero section header is a
372   // valid SHN_UNDEF entry since SHT_NULL == 0.
373   SHeaders.resize(Doc.Sections.size());
374 
375   for (size_t I = 0; I < Doc.Sections.size(); ++I) {
376     ELFYAML::Section *Sec = Doc.Sections[I].get();
377     if (I == 0 && Sec->IsImplicit)
378       continue;
379 
380     // We have a few sections like string or symbol tables that are usually
381     // added implicitly to the end. However, if they are explicitly specified
382     // in the YAML, we need to write them here. This ensures the file offset
383     // remains correct.
384     Elf_Shdr &SHeader = SHeaders[I];
385     if (initImplicitHeader(CBA, SHeader, Sec->Name,
386                            Sec->IsImplicit ? nullptr : Sec))
387       continue;
388 
389     assert(Sec && "It can't be null unless it is an implicit section. But all "
390                   "implicit sections should already have been handled above.");
391 
392     SHeader.sh_name =
393         DotShStrtab.getOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
394     SHeader.sh_type = Sec->Type;
395     if (Sec->Flags)
396       SHeader.sh_flags = *Sec->Flags;
397     SHeader.sh_addr = Sec->Address;
398     SHeader.sh_addralign = Sec->AddressAlign;
399 
400     if (!Sec->Link.empty())
401       SHeader.sh_link = toSectionIndex(Sec->Link, Sec->Name);
402 
403     if (I == 0) {
404       if (auto RawSec = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
405         // We do not write any content for special SHN_UNDEF section.
406         if (RawSec->Size)
407           SHeader.sh_size = *RawSec->Size;
408         if (RawSec->Info)
409           SHeader.sh_info = *RawSec->Info;
410       }
411       if (Sec->EntSize)
412         SHeader.sh_entsize = *Sec->EntSize;
413     } else if (auto S = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
414       writeSectionContent(SHeader, *S, CBA);
415     } else if (auto S = dyn_cast<ELFYAML::SymtabShndxSection>(Sec)) {
416       writeSectionContent(SHeader, *S, CBA);
417     } else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec)) {
418       writeSectionContent(SHeader, *S, CBA);
419     } else if (auto S = dyn_cast<ELFYAML::Group>(Sec)) {
420       writeSectionContent(SHeader, *S, CBA);
421     } else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec)) {
422       writeSectionContent(SHeader, *S, CBA);
423     } else if (auto S = dyn_cast<ELFYAML::NoBitsSection>(Sec)) {
424       SHeader.sh_entsize = 0;
425       SHeader.sh_size = S->Size;
426       // SHT_NOBITS section does not have content
427       // so just to setup the section offset.
428       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
429     } else if (auto S = dyn_cast<ELFYAML::DynamicSection>(Sec)) {
430       writeSectionContent(SHeader, *S, CBA);
431     } else if (auto S = dyn_cast<ELFYAML::SymverSection>(Sec)) {
432       writeSectionContent(SHeader, *S, CBA);
433     } else if (auto S = dyn_cast<ELFYAML::VerneedSection>(Sec)) {
434       writeSectionContent(SHeader, *S, CBA);
435     } else if (auto S = dyn_cast<ELFYAML::VerdefSection>(Sec)) {
436       writeSectionContent(SHeader, *S, CBA);
437     } else if (auto S = dyn_cast<ELFYAML::StackSizesSection>(Sec)) {
438       writeSectionContent(SHeader, *S, CBA);
439     } else if (auto S = dyn_cast<ELFYAML::HashSection>(Sec)) {
440       writeSectionContent(SHeader, *S, CBA);
441     } else if (auto S = dyn_cast<ELFYAML::AddrsigSection>(Sec)) {
442       writeSectionContent(SHeader, *S, CBA);
443     } else {
444       llvm_unreachable("Unknown section type");
445     }
446 
447     // Override the fields if requested.
448     if (Sec) {
449       if (Sec->ShName)
450         SHeader.sh_name = *Sec->ShName;
451       if (Sec->ShOffset)
452         SHeader.sh_offset = *Sec->ShOffset;
453       if (Sec->ShSize)
454         SHeader.sh_size = *Sec->ShSize;
455     }
456   }
457 }
458 
459 static size_t findFirstNonGlobal(ArrayRef<ELFYAML::Symbol> Symbols) {
460   for (size_t I = 0; I < Symbols.size(); ++I)
461     if (Symbols[I].Binding.value != ELF::STB_LOCAL)
462       return I;
463   return Symbols.size();
464 }
465 
466 static uint64_t writeContent(raw_ostream &OS,
467                              const Optional<yaml::BinaryRef> &Content,
468                              const Optional<llvm::yaml::Hex64> &Size) {
469   size_t ContentSize = 0;
470   if (Content) {
471     Content->writeAsBinary(OS);
472     ContentSize = Content->binary_size();
473   }
474 
475   if (!Size)
476     return ContentSize;
477 
478   OS.write_zeros(*Size - ContentSize);
479   return *Size;
480 }
481 
482 template <class ELFT>
483 std::vector<typename ELFT::Sym>
484 ELFState<ELFT>::toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
485                              const StringTableBuilder &Strtab) {
486   std::vector<Elf_Sym> Ret;
487   Ret.resize(Symbols.size() + 1);
488 
489   size_t I = 0;
490   for (const auto &Sym : Symbols) {
491     Elf_Sym &Symbol = Ret[++I];
492 
493     // If NameIndex, which contains the name offset, is explicitly specified, we
494     // use it. This is useful for preparing broken objects. Otherwise, we add
495     // the specified Name to the string table builder to get its offset.
496     if (Sym.NameIndex)
497       Symbol.st_name = *Sym.NameIndex;
498     else if (!Sym.Name.empty())
499       Symbol.st_name = Strtab.getOffset(ELFYAML::dropUniqueSuffix(Sym.Name));
500 
501     Symbol.setBindingAndType(Sym.Binding, Sym.Type);
502     if (!Sym.Section.empty())
503       Symbol.st_shndx = toSectionIndex(Sym.Section, "", Sym.Name);
504     else if (Sym.Index)
505       Symbol.st_shndx = *Sym.Index;
506 
507     Symbol.st_value = Sym.Value;
508     Symbol.st_other = Sym.Other ? *Sym.Other : 0;
509     Symbol.st_size = Sym.Size;
510   }
511 
512   return Ret;
513 }
514 
515 template <class ELFT>
516 void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
517                                              SymtabType STType,
518                                              ContiguousBlobAccumulator &CBA,
519                                              ELFYAML::Section *YAMLSec) {
520 
521   bool IsStatic = STType == SymtabType::Static;
522   ArrayRef<ELFYAML::Symbol> Symbols;
523   if (IsStatic && Doc.Symbols)
524     Symbols = *Doc.Symbols;
525   else if (!IsStatic)
526     Symbols = Doc.DynamicSymbols;
527 
528   ELFYAML::RawContentSection *RawSec =
529       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
530   if (RawSec && !Symbols.empty() && (RawSec->Content || RawSec->Size)) {
531     if (RawSec->Content)
532       reportError("cannot specify both `Content` and " +
533                   (IsStatic ? Twine("`Symbols`") : Twine("`DynamicSymbols`")) +
534                   " for symbol table section '" + RawSec->Name + "'");
535     if (RawSec->Size)
536       reportError("cannot specify both `Size` and " +
537                   (IsStatic ? Twine("`Symbols`") : Twine("`DynamicSymbols`")) +
538                   " for symbol table section '" + RawSec->Name + "'");
539     return;
540   }
541 
542   zero(SHeader);
543   SHeader.sh_name = DotShStrtab.getOffset(IsStatic ? ".symtab" : ".dynsym");
544 
545   if (YAMLSec)
546     SHeader.sh_type = YAMLSec->Type;
547   else
548     SHeader.sh_type = IsStatic ? ELF::SHT_SYMTAB : ELF::SHT_DYNSYM;
549 
550   if (RawSec && !RawSec->Link.empty()) {
551     // If the Link field is explicitly defined in the document,
552     // we should use it.
553     SHeader.sh_link = toSectionIndex(RawSec->Link, RawSec->Name);
554   } else {
555     // When we describe the .dynsym section in the document explicitly, it is
556     // allowed to omit the "DynamicSymbols" tag. In this case .dynstr is not
557     // added implicitly and we should be able to leave the Link zeroed if
558     // .dynstr is not defined.
559     unsigned Link = 0;
560     if (IsStatic)
561       Link = SN2I.get(".strtab");
562     else
563       SN2I.lookup(".dynstr", Link);
564     SHeader.sh_link = Link;
565   }
566 
567   if (YAMLSec && YAMLSec->Flags)
568     SHeader.sh_flags = *YAMLSec->Flags;
569   else if (!IsStatic)
570     SHeader.sh_flags = ELF::SHF_ALLOC;
571 
572   // If the symbol table section is explicitly described in the YAML
573   // then we should set the fields requested.
574   SHeader.sh_info = (RawSec && RawSec->Info) ? (unsigned)(*RawSec->Info)
575                                              : findFirstNonGlobal(Symbols) + 1;
576   SHeader.sh_entsize = (YAMLSec && YAMLSec->EntSize)
577                            ? (uint64_t)(*YAMLSec->EntSize)
578                            : sizeof(Elf_Sym);
579   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 8;
580   SHeader.sh_addr = YAMLSec ? (uint64_t)YAMLSec->Address : 0;
581 
582   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
583   if (RawSec && (RawSec->Content || RawSec->Size)) {
584     assert(Symbols.empty());
585     SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
586     return;
587   }
588 
589   std::vector<Elf_Sym> Syms =
590       toELFSymbols(Symbols, IsStatic ? DotStrtab : DotDynstr);
591   writeArrayData(OS, makeArrayRef(Syms));
592   SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
593 }
594 
595 template <class ELFT>
596 void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
597                                              StringTableBuilder &STB,
598                                              ContiguousBlobAccumulator &CBA,
599                                              ELFYAML::Section *YAMLSec) {
600   zero(SHeader);
601   SHeader.sh_name = DotShStrtab.getOffset(Name);
602   SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_STRTAB;
603   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
604 
605   ELFYAML::RawContentSection *RawSec =
606       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
607 
608   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
609   if (RawSec && (RawSec->Content || RawSec->Size)) {
610     SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
611   } else {
612     STB.write(OS);
613     SHeader.sh_size = STB.getSize();
614   }
615 
616   if (YAMLSec && YAMLSec->EntSize)
617     SHeader.sh_entsize = *YAMLSec->EntSize;
618 
619   if (RawSec && RawSec->Info)
620     SHeader.sh_info = *RawSec->Info;
621 
622   if (YAMLSec && YAMLSec->Flags)
623     SHeader.sh_flags = *YAMLSec->Flags;
624   else if (Name == ".dynstr")
625     SHeader.sh_flags = ELF::SHF_ALLOC;
626 
627   // If the section is explicitly described in the YAML
628   // then we want to use its section address.
629   if (YAMLSec)
630     SHeader.sh_addr = YAMLSec->Address;
631 }
632 
633 template <class ELFT> void ELFState<ELFT>::reportError(const Twine &Msg) {
634   ErrHandler(Msg);
635   HasError = true;
636 }
637 
638 template <class ELFT>
639 void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
640                                             std::vector<Elf_Shdr> &SHeaders) {
641   uint32_t PhdrIdx = 0;
642   for (auto &YamlPhdr : Doc.ProgramHeaders) {
643     Elf_Phdr &PHeader = PHeaders[PhdrIdx++];
644 
645     std::vector<Elf_Shdr *> Sections;
646     for (const ELFYAML::SectionName &SecName : YamlPhdr.Sections) {
647       unsigned Index;
648       if (!SN2I.lookup(SecName.Section, Index)) {
649         reportError("unknown section referenced: '" + SecName.Section +
650                     "' by program header");
651         continue;
652       }
653       Sections.push_back(&SHeaders[Index]);
654     }
655 
656     if (YamlPhdr.Offset) {
657       PHeader.p_offset = *YamlPhdr.Offset;
658     } else {
659       if (YamlPhdr.Sections.size())
660         PHeader.p_offset = UINT32_MAX;
661       else
662         PHeader.p_offset = 0;
663 
664       // Find the minimum offset for the program header.
665       for (Elf_Shdr *SHeader : Sections)
666         PHeader.p_offset = std::min(PHeader.p_offset, SHeader->sh_offset);
667     }
668 
669     // Find the maximum offset of the end of a section in order to set p_filesz
670     // and p_memsz. When setting p_filesz, trailing SHT_NOBITS sections are not
671     // counted.
672     uint64_t FileOffset = PHeader.p_offset, MemOffset = PHeader.p_offset;
673     for (Elf_Shdr *SHeader : Sections) {
674       uint64_t End = SHeader->sh_offset + SHeader->sh_size;
675       MemOffset = std::max(MemOffset, End);
676 
677       if (SHeader->sh_type != llvm::ELF::SHT_NOBITS)
678         FileOffset = std::max(FileOffset, End);
679     }
680 
681     // Set the file size and the memory size if not set explicitly.
682     PHeader.p_filesz = YamlPhdr.FileSize ? uint64_t(*YamlPhdr.FileSize)
683                                          : FileOffset - PHeader.p_offset;
684     PHeader.p_memsz = YamlPhdr.MemSize ? uint64_t(*YamlPhdr.MemSize)
685                                        : MemOffset - PHeader.p_offset;
686 
687     if (YamlPhdr.Align) {
688       PHeader.p_align = *YamlPhdr.Align;
689     } else {
690       // Set the alignment of the segment to be the maximum alignment of the
691       // sections so that by default the segment has a valid and sensible
692       // alignment.
693       PHeader.p_align = 1;
694       for (Elf_Shdr *SHeader : Sections)
695         PHeader.p_align = std::max(PHeader.p_align, SHeader->sh_addralign);
696     }
697   }
698 }
699 
700 template <class ELFT>
701 void ELFState<ELFT>::writeSectionContent(
702     Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section,
703     ContiguousBlobAccumulator &CBA) {
704   raw_ostream &OS =
705       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
706   SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
707 
708   if (Section.EntSize)
709     SHeader.sh_entsize = *Section.EntSize;
710   else if (Section.Type == llvm::ELF::SHT_RELR)
711     SHeader.sh_entsize = sizeof(Elf_Relr);
712   else
713     SHeader.sh_entsize = 0;
714 
715   if (Section.Info)
716     SHeader.sh_info = *Section.Info;
717 }
718 
719 static bool isMips64EL(const ELFYAML::Object &Doc) {
720   return Doc.Header.Machine == ELFYAML::ELF_EM(llvm::ELF::EM_MIPS) &&
721          Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64) &&
722          Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
723 }
724 
725 template <class ELFT>
726 void ELFState<ELFT>::writeSectionContent(
727     Elf_Shdr &SHeader, const ELFYAML::RelocationSection &Section,
728     ContiguousBlobAccumulator &CBA) {
729   assert((Section.Type == llvm::ELF::SHT_REL ||
730           Section.Type == llvm::ELF::SHT_RELA) &&
731          "Section type is not SHT_REL nor SHT_RELA");
732 
733   bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
734   SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
735   SHeader.sh_size = SHeader.sh_entsize * Section.Relocations.size();
736 
737   // For relocation section set link to .symtab by default.
738   if (Section.Link.empty())
739     SHeader.sh_link = SN2I.get(".symtab");
740 
741   if (!Section.RelocatableSec.empty())
742     SHeader.sh_info = toSectionIndex(Section.RelocatableSec, Section.Name);
743 
744   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
745   for (const auto &Rel : Section.Relocations) {
746     unsigned SymIdx = Rel.Symbol ? toSymbolIndex(*Rel.Symbol, Section.Name,
747                                                  Section.Link == ".dynsym")
748                                  : 0;
749     if (IsRela) {
750       Elf_Rela REntry;
751       zero(REntry);
752       REntry.r_offset = Rel.Offset;
753       REntry.r_addend = Rel.Addend;
754       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
755       OS.write((const char *)&REntry, sizeof(REntry));
756     } else {
757       Elf_Rel REntry;
758       zero(REntry);
759       REntry.r_offset = Rel.Offset;
760       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
761       OS.write((const char *)&REntry, sizeof(REntry));
762     }
763   }
764 }
765 
766 template <class ELFT>
767 void ELFState<ELFT>::writeSectionContent(
768     Elf_Shdr &SHeader, const ELFYAML::SymtabShndxSection &Shndx,
769     ContiguousBlobAccumulator &CBA) {
770   raw_ostream &OS =
771       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
772 
773   for (uint32_t E : Shndx.Entries)
774     support::endian::write<uint32_t>(OS, E, ELFT::TargetEndianness);
775 
776   SHeader.sh_entsize = Shndx.EntSize ? (uint64_t)*Shndx.EntSize : 4;
777   SHeader.sh_size = Shndx.Entries.size() * SHeader.sh_entsize;
778 }
779 
780 template <class ELFT>
781 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
782                                          const ELFYAML::Group &Section,
783                                          ContiguousBlobAccumulator &CBA) {
784   assert(Section.Type == llvm::ELF::SHT_GROUP &&
785          "Section type is not SHT_GROUP");
786 
787   SHeader.sh_entsize = 4;
788   SHeader.sh_size = SHeader.sh_entsize * Section.Members.size();
789   SHeader.sh_info =
790       toSymbolIndex(Section.Signature, Section.Name, /*IsDynamic=*/false);
791 
792   raw_ostream &OS =
793       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
794 
795   for (const ELFYAML::SectionOrType &Member : Section.Members) {
796     unsigned int SectionIndex = 0;
797     if (Member.sectionNameOrType == "GRP_COMDAT")
798       SectionIndex = llvm::ELF::GRP_COMDAT;
799     else
800       SectionIndex = toSectionIndex(Member.sectionNameOrType, Section.Name);
801     support::endian::write<uint32_t>(OS, SectionIndex, ELFT::TargetEndianness);
802   }
803 }
804 
805 template <class ELFT>
806 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
807                                          const ELFYAML::SymverSection &Section,
808                                          ContiguousBlobAccumulator &CBA) {
809   raw_ostream &OS =
810       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
811   for (uint16_t Version : Section.Entries)
812     support::endian::write<uint16_t>(OS, Version, ELFT::TargetEndianness);
813 
814   SHeader.sh_entsize = Section.EntSize ? (uint64_t)*Section.EntSize : 2;
815   SHeader.sh_size = Section.Entries.size() * SHeader.sh_entsize;
816 }
817 
818 template <class ELFT>
819 void ELFState<ELFT>::writeSectionContent(
820     Elf_Shdr &SHeader, const ELFYAML::StackSizesSection &Section,
821     ContiguousBlobAccumulator &CBA) {
822   using uintX_t = typename ELFT::uint;
823   raw_ostream &OS =
824       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
825 
826   if (Section.Content || Section.Size) {
827     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
828     return;
829   }
830 
831   for (const ELFYAML::StackSizeEntry &E : *Section.Entries) {
832     support::endian::write<uintX_t>(OS, E.Address, ELFT::TargetEndianness);
833     SHeader.sh_size += sizeof(uintX_t) + encodeULEB128(E.Size, OS);
834   }
835 }
836 
837 template <class ELFT>
838 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
839                                          const ELFYAML::HashSection &Section,
840                                          ContiguousBlobAccumulator &CBA) {
841   raw_ostream &OS =
842       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
843 
844   unsigned Link = 0;
845   if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
846     SHeader.sh_link = Link;
847 
848   if (Section.Content || Section.Size) {
849     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
850     return;
851   }
852 
853   support::endian::write<uint32_t>(OS, Section.Bucket->size(),
854                                    ELFT::TargetEndianness);
855   support::endian::write<uint32_t>(OS, Section.Chain->size(),
856                                    ELFT::TargetEndianness);
857   for (uint32_t Val : *Section.Bucket)
858     support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
859   for (uint32_t Val : *Section.Chain)
860     support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
861 
862   SHeader.sh_size = (2 + Section.Bucket->size() + Section.Chain->size()) * 4;
863 }
864 
865 template <class ELFT>
866 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
867                                          const ELFYAML::VerdefSection &Section,
868                                          ContiguousBlobAccumulator &CBA) {
869   typedef typename ELFT::Verdef Elf_Verdef;
870   typedef typename ELFT::Verdaux Elf_Verdaux;
871   raw_ostream &OS =
872       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
873 
874   uint64_t AuxCnt = 0;
875   for (size_t I = 0; I < Section.Entries.size(); ++I) {
876     const ELFYAML::VerdefEntry &E = Section.Entries[I];
877 
878     Elf_Verdef VerDef;
879     VerDef.vd_version = E.Version;
880     VerDef.vd_flags = E.Flags;
881     VerDef.vd_ndx = E.VersionNdx;
882     VerDef.vd_hash = E.Hash;
883     VerDef.vd_aux = sizeof(Elf_Verdef);
884     VerDef.vd_cnt = E.VerNames.size();
885     if (I == Section.Entries.size() - 1)
886       VerDef.vd_next = 0;
887     else
888       VerDef.vd_next =
889           sizeof(Elf_Verdef) + E.VerNames.size() * sizeof(Elf_Verdaux);
890     OS.write((const char *)&VerDef, sizeof(Elf_Verdef));
891 
892     for (size_t J = 0; J < E.VerNames.size(); ++J, ++AuxCnt) {
893       Elf_Verdaux VernAux;
894       VernAux.vda_name = DotDynstr.getOffset(E.VerNames[J]);
895       if (J == E.VerNames.size() - 1)
896         VernAux.vda_next = 0;
897       else
898         VernAux.vda_next = sizeof(Elf_Verdaux);
899       OS.write((const char *)&VernAux, sizeof(Elf_Verdaux));
900     }
901   }
902 
903   SHeader.sh_size = Section.Entries.size() * sizeof(Elf_Verdef) +
904                     AuxCnt * sizeof(Elf_Verdaux);
905   SHeader.sh_info = Section.Info;
906 }
907 
908 template <class ELFT>
909 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
910                                          const ELFYAML::VerneedSection &Section,
911                                          ContiguousBlobAccumulator &CBA) {
912   typedef typename ELFT::Verneed Elf_Verneed;
913   typedef typename ELFT::Vernaux Elf_Vernaux;
914 
915   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
916 
917   uint64_t AuxCnt = 0;
918   for (size_t I = 0; I < Section.VerneedV.size(); ++I) {
919     const ELFYAML::VerneedEntry &VE = Section.VerneedV[I];
920 
921     Elf_Verneed VerNeed;
922     VerNeed.vn_version = VE.Version;
923     VerNeed.vn_file = DotDynstr.getOffset(VE.File);
924     if (I == Section.VerneedV.size() - 1)
925       VerNeed.vn_next = 0;
926     else
927       VerNeed.vn_next =
928           sizeof(Elf_Verneed) + VE.AuxV.size() * sizeof(Elf_Vernaux);
929     VerNeed.vn_cnt = VE.AuxV.size();
930     VerNeed.vn_aux = sizeof(Elf_Verneed);
931     OS.write((const char *)&VerNeed, sizeof(Elf_Verneed));
932 
933     for (size_t J = 0; J < VE.AuxV.size(); ++J, ++AuxCnt) {
934       const ELFYAML::VernauxEntry &VAuxE = VE.AuxV[J];
935 
936       Elf_Vernaux VernAux;
937       VernAux.vna_hash = VAuxE.Hash;
938       VernAux.vna_flags = VAuxE.Flags;
939       VernAux.vna_other = VAuxE.Other;
940       VernAux.vna_name = DotDynstr.getOffset(VAuxE.Name);
941       if (J == VE.AuxV.size() - 1)
942         VernAux.vna_next = 0;
943       else
944         VernAux.vna_next = sizeof(Elf_Vernaux);
945       OS.write((const char *)&VernAux, sizeof(Elf_Vernaux));
946     }
947   }
948 
949   SHeader.sh_size = Section.VerneedV.size() * sizeof(Elf_Verneed) +
950                     AuxCnt * sizeof(Elf_Vernaux);
951   SHeader.sh_info = Section.Info;
952 }
953 
954 template <class ELFT>
955 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
956                                          const ELFYAML::MipsABIFlags &Section,
957                                          ContiguousBlobAccumulator &CBA) {
958   assert(Section.Type == llvm::ELF::SHT_MIPS_ABIFLAGS &&
959          "Section type is not SHT_MIPS_ABIFLAGS");
960 
961   object::Elf_Mips_ABIFlags<ELFT> Flags;
962   zero(Flags);
963   SHeader.sh_entsize = sizeof(Flags);
964   SHeader.sh_size = SHeader.sh_entsize;
965 
966   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
967   Flags.version = Section.Version;
968   Flags.isa_level = Section.ISALevel;
969   Flags.isa_rev = Section.ISARevision;
970   Flags.gpr_size = Section.GPRSize;
971   Flags.cpr1_size = Section.CPR1Size;
972   Flags.cpr2_size = Section.CPR2Size;
973   Flags.fp_abi = Section.FpABI;
974   Flags.isa_ext = Section.ISAExtension;
975   Flags.ases = Section.ASEs;
976   Flags.flags1 = Section.Flags1;
977   Flags.flags2 = Section.Flags2;
978   OS.write((const char *)&Flags, sizeof(Flags));
979 }
980 
981 template <class ELFT>
982 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
983                                          const ELFYAML::DynamicSection &Section,
984                                          ContiguousBlobAccumulator &CBA) {
985   typedef typename ELFT::uint uintX_t;
986 
987   assert(Section.Type == llvm::ELF::SHT_DYNAMIC &&
988          "Section type is not SHT_DYNAMIC");
989 
990   if (!Section.Entries.empty() && Section.Content)
991     reportError("cannot specify both raw content and explicit entries "
992                 "for dynamic section '" +
993                 Section.Name + "'");
994 
995   if (Section.Content)
996     SHeader.sh_size = Section.Content->binary_size();
997   else
998     SHeader.sh_size = 2 * sizeof(uintX_t) * Section.Entries.size();
999   if (Section.EntSize)
1000     SHeader.sh_entsize = *Section.EntSize;
1001   else
1002     SHeader.sh_entsize = sizeof(Elf_Dyn);
1003 
1004   raw_ostream &OS =
1005       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1006   for (const ELFYAML::DynamicEntry &DE : Section.Entries) {
1007     support::endian::write<uintX_t>(OS, DE.Tag, ELFT::TargetEndianness);
1008     support::endian::write<uintX_t>(OS, DE.Val, ELFT::TargetEndianness);
1009   }
1010   if (Section.Content)
1011     Section.Content->writeAsBinary(OS);
1012 }
1013 
1014 template <class ELFT>
1015 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
1016                                          const ELFYAML::AddrsigSection &Section,
1017                                          ContiguousBlobAccumulator &CBA) {
1018   raw_ostream &OS =
1019       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1020 
1021   unsigned Link = 0;
1022   if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
1023     SHeader.sh_link = Link;
1024 
1025   if (Section.Content || Section.Size) {
1026     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
1027     return;
1028   }
1029 
1030   for (const ELFYAML::AddrsigSymbol &Sym : *Section.Symbols) {
1031     uint64_t Val =
1032         Sym.Name ? toSymbolIndex(*Sym.Name, Section.Name, /*IsDynamic=*/false)
1033                  : (uint32_t)*Sym.Index;
1034     SHeader.sh_size += encodeULEB128(Val, OS);
1035   }
1036 }
1037 
1038 template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
1039   for (unsigned I = 0, E = Doc.Sections.size(); I != E; ++I) {
1040     StringRef Name = Doc.Sections[I]->Name;
1041     if (Name.empty())
1042       continue;
1043 
1044     DotShStrtab.add(ELFYAML::dropUniqueSuffix(Name));
1045     if (!SN2I.addName(Name, I))
1046       reportError("repeated section name: '" + Name +
1047                   "' at YAML section number " + Twine(I));
1048   }
1049 
1050   DotShStrtab.finalize();
1051 }
1052 
1053 template <class ELFT> void ELFState<ELFT>::buildSymbolIndexes() {
1054   auto Build = [this](ArrayRef<ELFYAML::Symbol> V, NameToIdxMap &Map) {
1055     for (size_t I = 0, S = V.size(); I < S; ++I) {
1056       const ELFYAML::Symbol &Sym = V[I];
1057       if (!Sym.Name.empty() && !Map.addName(Sym.Name, I + 1))
1058         reportError("repeated symbol name: '" + Sym.Name + "'");
1059     }
1060   };
1061 
1062   if (Doc.Symbols)
1063     Build(*Doc.Symbols, SymN2I);
1064   Build(Doc.DynamicSymbols, DynSymN2I);
1065 }
1066 
1067 template <class ELFT> void ELFState<ELFT>::finalizeStrings() {
1068   // Add the regular symbol names to .strtab section.
1069   if (Doc.Symbols)
1070     for (const ELFYAML::Symbol &Sym : *Doc.Symbols)
1071       DotStrtab.add(ELFYAML::dropUniqueSuffix(Sym.Name));
1072   DotStrtab.finalize();
1073 
1074   // Add the dynamic symbol names to .dynstr section.
1075   for (const ELFYAML::Symbol &Sym : Doc.DynamicSymbols)
1076     DotDynstr.add(ELFYAML::dropUniqueSuffix(Sym.Name));
1077 
1078   // SHT_GNU_verdef and SHT_GNU_verneed sections might also
1079   // add strings to .dynstr section.
1080   for (const std::unique_ptr<ELFYAML::Section> &Sec : Doc.Sections) {
1081     if (auto VerNeed = dyn_cast<ELFYAML::VerneedSection>(Sec.get())) {
1082       for (const ELFYAML::VerneedEntry &VE : VerNeed->VerneedV) {
1083         DotDynstr.add(VE.File);
1084         for (const ELFYAML::VernauxEntry &Aux : VE.AuxV)
1085           DotDynstr.add(Aux.Name);
1086       }
1087     } else if (auto VerDef = dyn_cast<ELFYAML::VerdefSection>(Sec.get())) {
1088       for (const ELFYAML::VerdefEntry &E : VerDef->Entries)
1089         for (StringRef Name : E.VerNames)
1090           DotDynstr.add(Name);
1091     }
1092   }
1093 
1094   DotDynstr.finalize();
1095 }
1096 
1097 template <class ELFT>
1098 bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
1099                               yaml::ErrorHandler EH) {
1100   ELFState<ELFT> State(Doc, EH);
1101 
1102   // Finalize .strtab and .dynstr sections. We do that early because want to
1103   // finalize the string table builders before writing the content of the
1104   // sections that might want to use them.
1105   State.finalizeStrings();
1106 
1107   State.buildSectionIndex();
1108   State.buildSymbolIndexes();
1109 
1110   std::vector<Elf_Phdr> PHeaders;
1111   State.initProgramHeaders(PHeaders);
1112 
1113   // XXX: This offset is tightly coupled with the order that we write
1114   // things to `OS`.
1115   const size_t SectionContentBeginOffset =
1116       sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * Doc.ProgramHeaders.size();
1117   ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
1118 
1119   std::vector<Elf_Shdr> SHeaders;
1120   State.initSectionHeaders(SHeaders, CBA);
1121 
1122   // Now we can decide segment offsets
1123   State.setProgramHeaderLayout(PHeaders, SHeaders);
1124 
1125   if (State.HasError)
1126     return false;
1127 
1128   State.writeELFHeader(CBA, OS);
1129   writeArrayData(OS, makeArrayRef(PHeaders));
1130   CBA.writeBlobToStream(OS);
1131   writeArrayData(OS, makeArrayRef(SHeaders));
1132   return true;
1133 }
1134 
1135 namespace llvm {
1136 namespace yaml {
1137 
1138 bool yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out, ErrorHandler EH) {
1139   bool IsLE = Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
1140   bool Is64Bit = Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
1141   if (Is64Bit) {
1142     if (IsLE)
1143       return ELFState<object::ELF64LE>::writeELF(Out, Doc, EH);
1144     return ELFState<object::ELF64BE>::writeELF(Out, Doc, EH);
1145   }
1146   if (IsLE)
1147     return ELFState<object::ELF32LE>::writeELF(Out, Doc, EH);
1148   return ELFState<object::ELF32BE>::writeELF(Out, Doc, EH);
1149 }
1150 
1151 } // namespace yaml
1152 } // namespace llvm
1153