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/DenseMap.h"
16 #include "llvm/ADT/StringSet.h"
17 #include "llvm/BinaryFormat/ELF.h"
18 #include "llvm/MC/StringTableBuilder.h"
19 #include "llvm/Object/ELFObjectFile.h"
20 #include "llvm/ObjectYAML/ELFYAML.h"
21 #include "llvm/ObjectYAML/yaml2obj.h"
22 #include "llvm/Support/EndianStream.h"
23 #include "llvm/Support/LEB128.h"
24 #include "llvm/Support/MemoryBuffer.h"
25 #include "llvm/Support/WithColor.h"
26 #include "llvm/Support/YAMLTraits.h"
27 #include "llvm/Support/raw_ostream.h"
28 
29 using namespace llvm;
30 
31 // This class is used to build up a contiguous binary blob while keeping
32 // track of an offset in the output (which notionally begins at
33 // `InitialOffset`).
34 namespace {
35 class ContiguousBlobAccumulator {
36   const uint64_t InitialOffset;
37   SmallVector<char, 128> Buf;
38   raw_svector_ostream OS;
39 
40 public:
41   ContiguousBlobAccumulator(uint64_t InitialOffset_)
42       : InitialOffset(InitialOffset_), Buf(), OS(Buf) {}
43 
44   template <class Integer>
45   raw_ostream &getOSAndAlignedOffset(Integer &Offset, unsigned Align) {
46     Offset = padToAlignment(Align);
47     return OS;
48   }
49 
50   /// \returns The new offset.
51   uint64_t padToAlignment(unsigned Align) {
52     if (Align == 0)
53       Align = 1;
54     uint64_t CurrentOffset = InitialOffset + OS.tell();
55     uint64_t AlignedOffset = alignTo(CurrentOffset, Align);
56     OS.write_zeros(AlignedOffset - CurrentOffset);
57     return AlignedOffset; // == CurrentOffset;
58   }
59 
60   void writeBlobToStream(raw_ostream &Out) { Out << OS.str(); }
61 };
62 
63 // Used to keep track of section and symbol names, so that in the YAML file
64 // sections and symbols can be referenced by name instead of by index.
65 class NameToIdxMap {
66   StringMap<unsigned> Map;
67 
68 public:
69   /// \Returns false if name is already present in the map.
70   bool addName(StringRef Name, unsigned Ndx) {
71     return Map.insert({Name, Ndx}).second;
72   }
73   /// \Returns false if name is not present in the map.
74   bool lookup(StringRef Name, unsigned &Idx) const {
75     auto I = Map.find(Name);
76     if (I == Map.end())
77       return false;
78     Idx = I->getValue();
79     return true;
80   }
81   /// Asserts if name is not present in the map.
82   unsigned get(StringRef Name) const {
83     unsigned Idx;
84     if (lookup(Name, Idx))
85       return Idx;
86     assert(false && "Expected section not found in index");
87     return 0;
88   }
89   unsigned size() const { return Map.size(); }
90 };
91 
92 namespace {
93 struct Fragment {
94   uint64_t Offset;
95   uint64_t Size;
96   uint32_t Type;
97   uint64_t AddrAlign;
98 };
99 } // namespace
100 
101 /// "Single point of truth" for the ELF file construction.
102 /// TODO: This class still has a ways to go before it is truly a "single
103 /// point of truth".
104 template <class ELFT> class ELFState {
105   typedef typename ELFT::Ehdr Elf_Ehdr;
106   typedef typename ELFT::Phdr Elf_Phdr;
107   typedef typename ELFT::Shdr Elf_Shdr;
108   typedef typename ELFT::Sym Elf_Sym;
109   typedef typename ELFT::Rel Elf_Rel;
110   typedef typename ELFT::Rela Elf_Rela;
111   typedef typename ELFT::Relr Elf_Relr;
112   typedef typename ELFT::Dyn Elf_Dyn;
113   typedef typename ELFT::uint uintX_t;
114 
115   enum class SymtabType { Static, Dynamic };
116 
117   /// The future ".strtab" section.
118   StringTableBuilder DotStrtab{StringTableBuilder::ELF};
119 
120   /// The future ".shstrtab" section.
121   StringTableBuilder DotShStrtab{StringTableBuilder::ELF};
122 
123   /// The future ".dynstr" section.
124   StringTableBuilder DotDynstr{StringTableBuilder::ELF};
125 
126   NameToIdxMap SN2I;
127   NameToIdxMap SymN2I;
128   NameToIdxMap DynSymN2I;
129   ELFYAML::Object &Doc;
130 
131   bool HasError = false;
132   yaml::ErrorHandler ErrHandler;
133   void reportError(const Twine &Msg);
134 
135   std::vector<Elf_Sym> toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
136                                     const StringTableBuilder &Strtab);
137   unsigned toSectionIndex(StringRef S, StringRef LocSec, StringRef LocSym = "");
138   unsigned toSymbolIndex(StringRef S, StringRef LocSec, bool IsDynamic);
139 
140   void buildSectionIndex();
141   void buildSymbolIndexes();
142   void initProgramHeaders(std::vector<Elf_Phdr> &PHeaders);
143   bool initImplicitHeader(ContiguousBlobAccumulator &CBA, Elf_Shdr &Header,
144                           StringRef SecName, ELFYAML::Section *YAMLSec);
145   void initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
146                           ContiguousBlobAccumulator &CBA);
147   void initSymtabSectionHeader(Elf_Shdr &SHeader, SymtabType STType,
148                                ContiguousBlobAccumulator &CBA,
149                                ELFYAML::Section *YAMLSec);
150   void initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
151                                StringTableBuilder &STB,
152                                ContiguousBlobAccumulator &CBA,
153                                ELFYAML::Section *YAMLSec);
154   void setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
155                               std::vector<Elf_Shdr> &SHeaders);
156 
157   std::vector<Fragment>
158   getPhdrFragments(const ELFYAML::ProgramHeader &Phdr,
159                    ArrayRef<typename ELFT::Shdr> SHeaders);
160 
161   void finalizeStrings();
162   void writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS);
163   void writeSectionContent(Elf_Shdr &SHeader,
164                            const ELFYAML::RawContentSection &Section,
165                            ContiguousBlobAccumulator &CBA);
166   void writeSectionContent(Elf_Shdr &SHeader,
167                            const ELFYAML::RelocationSection &Section,
168                            ContiguousBlobAccumulator &CBA);
169   void writeSectionContent(Elf_Shdr &SHeader,
170                            const ELFYAML::RelrSection &Section,
171                            ContiguousBlobAccumulator &CBA);
172   void writeSectionContent(Elf_Shdr &SHeader, const ELFYAML::Group &Group,
173                            ContiguousBlobAccumulator &CBA);
174   void writeSectionContent(Elf_Shdr &SHeader,
175                            const ELFYAML::SymtabShndxSection &Shndx,
176                            ContiguousBlobAccumulator &CBA);
177   void writeSectionContent(Elf_Shdr &SHeader,
178                            const ELFYAML::SymverSection &Section,
179                            ContiguousBlobAccumulator &CBA);
180   void writeSectionContent(Elf_Shdr &SHeader,
181                            const ELFYAML::VerneedSection &Section,
182                            ContiguousBlobAccumulator &CBA);
183   void writeSectionContent(Elf_Shdr &SHeader,
184                            const ELFYAML::VerdefSection &Section,
185                            ContiguousBlobAccumulator &CBA);
186   void writeSectionContent(Elf_Shdr &SHeader,
187                            const ELFYAML::MipsABIFlags &Section,
188                            ContiguousBlobAccumulator &CBA);
189   void writeSectionContent(Elf_Shdr &SHeader,
190                            const ELFYAML::DynamicSection &Section,
191                            ContiguousBlobAccumulator &CBA);
192   void writeSectionContent(Elf_Shdr &SHeader,
193                            const ELFYAML::StackSizesSection &Section,
194                            ContiguousBlobAccumulator &CBA);
195   void writeSectionContent(Elf_Shdr &SHeader,
196                            const ELFYAML::HashSection &Section,
197                            ContiguousBlobAccumulator &CBA);
198   void writeSectionContent(Elf_Shdr &SHeader,
199                            const ELFYAML::AddrsigSection &Section,
200                            ContiguousBlobAccumulator &CBA);
201   void writeSectionContent(Elf_Shdr &SHeader,
202                            const ELFYAML::NoteSection &Section,
203                            ContiguousBlobAccumulator &CBA);
204   void writeSectionContent(Elf_Shdr &SHeader,
205                            const ELFYAML::GnuHashSection &Section,
206                            ContiguousBlobAccumulator &CBA);
207   void writeSectionContent(Elf_Shdr &SHeader,
208                            const ELFYAML::LinkerOptionsSection &Section,
209                            ContiguousBlobAccumulator &CBA);
210   void writeSectionContent(Elf_Shdr &SHeader,
211                            const ELFYAML::DependentLibrariesSection &Section,
212                            ContiguousBlobAccumulator &CBA);
213 
214   void writeFill(ELFYAML::Fill &Fill, ContiguousBlobAccumulator &CBA);
215 
216   ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH);
217 
218 public:
219   static bool writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
220                        yaml::ErrorHandler EH);
221 };
222 } // end anonymous namespace
223 
224 template <class T> static size_t arrayDataSize(ArrayRef<T> A) {
225   return A.size() * sizeof(T);
226 }
227 
228 template <class T> static void writeArrayData(raw_ostream &OS, ArrayRef<T> A) {
229   OS.write((const char *)A.data(), arrayDataSize(A));
230 }
231 
232 template <class T> static void zero(T &Obj) { memset(&Obj, 0, sizeof(Obj)); }
233 
234 template <class ELFT>
235 ELFState<ELFT>::ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH)
236     : Doc(D), ErrHandler(EH) {
237   std::vector<ELFYAML::Section *> Sections = Doc.getSections();
238   StringSet<> DocSections;
239   for (const ELFYAML::Section *Sec : Sections)
240     if (!Sec->Name.empty())
241       DocSections.insert(Sec->Name);
242 
243   // Insert SHT_NULL section implicitly when it is not defined in YAML.
244   if (Sections.empty() || Sections.front()->Type != ELF::SHT_NULL)
245     Doc.Chunks.insert(
246         Doc.Chunks.begin(),
247         std::make_unique<ELFYAML::Section>(
248             ELFYAML::Chunk::ChunkKind::RawContent, /*IsImplicit=*/true));
249 
250   std::vector<StringRef> ImplicitSections;
251   if (Doc.Symbols)
252     ImplicitSections.push_back(".symtab");
253   ImplicitSections.insert(ImplicitSections.end(), {".strtab", ".shstrtab"});
254 
255   if (Doc.DynamicSymbols)
256     ImplicitSections.insert(ImplicitSections.end(), {".dynsym", ".dynstr"});
257 
258   // Insert placeholders for implicit sections that are not
259   // defined explicitly in YAML.
260   for (StringRef SecName : ImplicitSections) {
261     if (DocSections.count(SecName))
262       continue;
263 
264     std::unique_ptr<ELFYAML::Chunk> Sec = std::make_unique<ELFYAML::Section>(
265         ELFYAML::Chunk::ChunkKind::RawContent, true /*IsImplicit*/);
266     Sec->Name = SecName;
267     Doc.Chunks.push_back(std::move(Sec));
268   }
269 }
270 
271 template <class ELFT>
272 void ELFState<ELFT>::writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS) {
273   using namespace llvm::ELF;
274 
275   Elf_Ehdr Header;
276   zero(Header);
277   Header.e_ident[EI_MAG0] = 0x7f;
278   Header.e_ident[EI_MAG1] = 'E';
279   Header.e_ident[EI_MAG2] = 'L';
280   Header.e_ident[EI_MAG3] = 'F';
281   Header.e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
282   Header.e_ident[EI_DATA] = Doc.Header.Data;
283   Header.e_ident[EI_VERSION] = EV_CURRENT;
284   Header.e_ident[EI_OSABI] = Doc.Header.OSABI;
285   Header.e_ident[EI_ABIVERSION] = Doc.Header.ABIVersion;
286   Header.e_type = Doc.Header.Type;
287   Header.e_machine = Doc.Header.Machine;
288   Header.e_version = EV_CURRENT;
289   Header.e_entry = Doc.Header.Entry;
290   Header.e_phoff = Doc.ProgramHeaders.size() ? sizeof(Header) : 0;
291   Header.e_flags = Doc.Header.Flags;
292   Header.e_ehsize = sizeof(Elf_Ehdr);
293   Header.e_phentsize = Doc.ProgramHeaders.size() ? sizeof(Elf_Phdr) : 0;
294   Header.e_phnum = Doc.ProgramHeaders.size();
295 
296   Header.e_shentsize =
297       Doc.Header.SHEntSize ? (uint16_t)*Doc.Header.SHEntSize : sizeof(Elf_Shdr);
298   // Immediately following the ELF header and program headers.
299   // Align the start of the section header and write the ELF header.
300   uint64_t SHOff;
301   CBA.getOSAndAlignedOffset(SHOff, sizeof(typename ELFT::uint));
302   Header.e_shoff =
303       Doc.Header.SHOff ? typename ELFT::uint(*Doc.Header.SHOff) : SHOff;
304   Header.e_shnum =
305       Doc.Header.SHNum ? (uint16_t)*Doc.Header.SHNum : Doc.getSections().size();
306   Header.e_shstrndx = Doc.Header.SHStrNdx ? (uint16_t)*Doc.Header.SHStrNdx
307                                           : SN2I.get(".shstrtab");
308 
309   OS.write((const char *)&Header, sizeof(Header));
310 }
311 
312 template <class ELFT>
313 void ELFState<ELFT>::initProgramHeaders(std::vector<Elf_Phdr> &PHeaders) {
314   for (const auto &YamlPhdr : Doc.ProgramHeaders) {
315     Elf_Phdr Phdr;
316     Phdr.p_type = YamlPhdr.Type;
317     Phdr.p_flags = YamlPhdr.Flags;
318     Phdr.p_vaddr = YamlPhdr.VAddr;
319     Phdr.p_paddr = YamlPhdr.PAddr;
320     PHeaders.push_back(Phdr);
321   }
322 }
323 
324 template <class ELFT>
325 unsigned ELFState<ELFT>::toSectionIndex(StringRef S, StringRef LocSec,
326                                         StringRef LocSym) {
327   unsigned Index;
328   if (SN2I.lookup(S, Index) || to_integer(S, Index))
329     return Index;
330 
331   assert(LocSec.empty() || LocSym.empty());
332   if (!LocSym.empty())
333     reportError("unknown section referenced: '" + S + "' by YAML symbol '" +
334                 LocSym + "'");
335   else
336     reportError("unknown section referenced: '" + S + "' by YAML section '" +
337                 LocSec + "'");
338   return 0;
339 }
340 
341 template <class ELFT>
342 unsigned ELFState<ELFT>::toSymbolIndex(StringRef S, StringRef LocSec,
343                                        bool IsDynamic) {
344   const NameToIdxMap &SymMap = IsDynamic ? DynSymN2I : SymN2I;
345   unsigned Index;
346   // Here we try to look up S in the symbol table. If it is not there,
347   // treat its value as a symbol index.
348   if (!SymMap.lookup(S, Index) && !to_integer(S, Index)) {
349     reportError("unknown symbol referenced: '" + S + "' by YAML section '" +
350                 LocSec + "'");
351     return 0;
352   }
353   return Index;
354 }
355 
356 template <class ELFT>
357 static void overrideFields(ELFYAML::Section *From, typename ELFT::Shdr &To) {
358   if (!From)
359     return;
360   if (From->ShFlags)
361     To.sh_flags = *From->ShFlags;
362   if (From->ShName)
363     To.sh_name = *From->ShName;
364   if (From->ShOffset)
365     To.sh_offset = *From->ShOffset;
366   if (From->ShSize)
367     To.sh_size = *From->ShSize;
368 }
369 
370 template <class ELFT>
371 bool ELFState<ELFT>::initImplicitHeader(ContiguousBlobAccumulator &CBA,
372                                         Elf_Shdr &Header, StringRef SecName,
373                                         ELFYAML::Section *YAMLSec) {
374   // Check if the header was already initialized.
375   if (Header.sh_offset)
376     return false;
377 
378   if (SecName == ".symtab")
379     initSymtabSectionHeader(Header, SymtabType::Static, CBA, YAMLSec);
380   else if (SecName == ".strtab")
381     initStrtabSectionHeader(Header, SecName, DotStrtab, CBA, YAMLSec);
382   else if (SecName == ".shstrtab")
383     initStrtabSectionHeader(Header, SecName, DotShStrtab, CBA, YAMLSec);
384   else if (SecName == ".dynsym")
385     initSymtabSectionHeader(Header, SymtabType::Dynamic, CBA, YAMLSec);
386   else if (SecName == ".dynstr")
387     initStrtabSectionHeader(Header, SecName, DotDynstr, CBA, YAMLSec);
388   else
389     return false;
390 
391   // Override section fields if requested.
392   overrideFields<ELFT>(YAMLSec, Header);
393   return true;
394 }
395 
396 StringRef llvm::ELFYAML::dropUniqueSuffix(StringRef S) {
397   size_t SuffixPos = S.rfind(" [");
398   if (SuffixPos == StringRef::npos)
399     return S;
400   return S.substr(0, SuffixPos);
401 }
402 
403 template <class ELFT>
404 void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
405                                         ContiguousBlobAccumulator &CBA) {
406   // Ensure SHN_UNDEF entry is present. An all-zero section header is a
407   // valid SHN_UNDEF entry since SHT_NULL == 0.
408   SHeaders.resize(Doc.getSections().size());
409 
410   size_t SecNdx = -1;
411   for (const std::unique_ptr<ELFYAML::Chunk> &D : Doc.Chunks) {
412     if (auto S = dyn_cast<ELFYAML::Fill>(D.get())) {
413       writeFill(*S, CBA);
414       continue;
415     }
416 
417     ++SecNdx;
418     ELFYAML::Section *Sec = cast<ELFYAML::Section>(D.get());
419     if (SecNdx == 0 && Sec->IsImplicit)
420       continue;
421 
422     // We have a few sections like string or symbol tables that are usually
423     // added implicitly to the end. However, if they are explicitly specified
424     // in the YAML, we need to write them here. This ensures the file offset
425     // remains correct.
426     Elf_Shdr &SHeader = SHeaders[SecNdx];
427     if (initImplicitHeader(CBA, SHeader, Sec->Name,
428                            Sec->IsImplicit ? nullptr : Sec))
429       continue;
430 
431     assert(Sec && "It can't be null unless it is an implicit section. But all "
432                   "implicit sections should already have been handled above.");
433 
434     SHeader.sh_name =
435         DotShStrtab.getOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
436     SHeader.sh_type = Sec->Type;
437     if (Sec->Flags)
438       SHeader.sh_flags = *Sec->Flags;
439     SHeader.sh_addr = Sec->Address;
440     SHeader.sh_addralign = Sec->AddressAlign;
441 
442     if (!Sec->Link.empty())
443       SHeader.sh_link = toSectionIndex(Sec->Link, Sec->Name);
444 
445     if (SecNdx == 0) {
446       if (auto RawSec = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
447         // We do not write any content for special SHN_UNDEF section.
448         if (RawSec->Size)
449           SHeader.sh_size = *RawSec->Size;
450         if (RawSec->Info)
451           SHeader.sh_info = *RawSec->Info;
452       }
453       if (Sec->EntSize)
454         SHeader.sh_entsize = *Sec->EntSize;
455     } else if (auto S = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
456       writeSectionContent(SHeader, *S, CBA);
457     } else if (auto S = dyn_cast<ELFYAML::SymtabShndxSection>(Sec)) {
458       writeSectionContent(SHeader, *S, CBA);
459     } else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec)) {
460       writeSectionContent(SHeader, *S, CBA);
461     } else if (auto S = dyn_cast<ELFYAML::RelrSection>(Sec)) {
462       writeSectionContent(SHeader, *S, CBA);
463     } else if (auto S = dyn_cast<ELFYAML::Group>(Sec)) {
464       writeSectionContent(SHeader, *S, CBA);
465     } else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec)) {
466       writeSectionContent(SHeader, *S, CBA);
467     } else if (auto S = dyn_cast<ELFYAML::NoBitsSection>(Sec)) {
468       SHeader.sh_entsize = 0;
469       SHeader.sh_size = S->Size;
470       // SHT_NOBITS section does not have content
471       // so just to setup the section offset.
472       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
473     } else if (auto S = dyn_cast<ELFYAML::DynamicSection>(Sec)) {
474       writeSectionContent(SHeader, *S, CBA);
475     } else if (auto S = dyn_cast<ELFYAML::SymverSection>(Sec)) {
476       writeSectionContent(SHeader, *S, CBA);
477     } else if (auto S = dyn_cast<ELFYAML::VerneedSection>(Sec)) {
478       writeSectionContent(SHeader, *S, CBA);
479     } else if (auto S = dyn_cast<ELFYAML::VerdefSection>(Sec)) {
480       writeSectionContent(SHeader, *S, CBA);
481     } else if (auto S = dyn_cast<ELFYAML::StackSizesSection>(Sec)) {
482       writeSectionContent(SHeader, *S, CBA);
483     } else if (auto S = dyn_cast<ELFYAML::HashSection>(Sec)) {
484       writeSectionContent(SHeader, *S, CBA);
485     } else if (auto S = dyn_cast<ELFYAML::AddrsigSection>(Sec)) {
486       writeSectionContent(SHeader, *S, CBA);
487     } else if (auto S = dyn_cast<ELFYAML::LinkerOptionsSection>(Sec)) {
488       writeSectionContent(SHeader, *S, CBA);
489     } else if (auto S = dyn_cast<ELFYAML::NoteSection>(Sec)) {
490       writeSectionContent(SHeader, *S, CBA);
491     } else if (auto S = dyn_cast<ELFYAML::GnuHashSection>(Sec)) {
492       writeSectionContent(SHeader, *S, CBA);
493     } else if (auto S = dyn_cast<ELFYAML::DependentLibrariesSection>(Sec)) {
494       writeSectionContent(SHeader, *S, CBA);
495     } else {
496       llvm_unreachable("Unknown section type");
497     }
498 
499     // Override section fields if requested.
500     overrideFields<ELFT>(Sec, SHeader);
501   }
502 }
503 
504 static size_t findFirstNonGlobal(ArrayRef<ELFYAML::Symbol> Symbols) {
505   for (size_t I = 0; I < Symbols.size(); ++I)
506     if (Symbols[I].Binding.value != ELF::STB_LOCAL)
507       return I;
508   return Symbols.size();
509 }
510 
511 static uint64_t writeContent(raw_ostream &OS,
512                              const Optional<yaml::BinaryRef> &Content,
513                              const Optional<llvm::yaml::Hex64> &Size) {
514   size_t ContentSize = 0;
515   if (Content) {
516     Content->writeAsBinary(OS);
517     ContentSize = Content->binary_size();
518   }
519 
520   if (!Size)
521     return ContentSize;
522 
523   OS.write_zeros(*Size - ContentSize);
524   return *Size;
525 }
526 
527 template <class ELFT>
528 std::vector<typename ELFT::Sym>
529 ELFState<ELFT>::toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
530                              const StringTableBuilder &Strtab) {
531   std::vector<Elf_Sym> Ret;
532   Ret.resize(Symbols.size() + 1);
533 
534   size_t I = 0;
535   for (const ELFYAML::Symbol &Sym : Symbols) {
536     Elf_Sym &Symbol = Ret[++I];
537 
538     // If NameIndex, which contains the name offset, is explicitly specified, we
539     // use it. This is useful for preparing broken objects. Otherwise, we add
540     // the specified Name to the string table builder to get its offset.
541     if (Sym.NameIndex)
542       Symbol.st_name = *Sym.NameIndex;
543     else if (!Sym.Name.empty())
544       Symbol.st_name = Strtab.getOffset(ELFYAML::dropUniqueSuffix(Sym.Name));
545 
546     Symbol.setBindingAndType(Sym.Binding, Sym.Type);
547     if (!Sym.Section.empty())
548       Symbol.st_shndx = toSectionIndex(Sym.Section, "", Sym.Name);
549     else if (Sym.Index)
550       Symbol.st_shndx = *Sym.Index;
551 
552     Symbol.st_value = Sym.Value;
553     Symbol.st_other = Sym.Other ? *Sym.Other : 0;
554     Symbol.st_size = Sym.Size;
555   }
556 
557   return Ret;
558 }
559 
560 template <class ELFT>
561 void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
562                                              SymtabType STType,
563                                              ContiguousBlobAccumulator &CBA,
564                                              ELFYAML::Section *YAMLSec) {
565 
566   bool IsStatic = STType == SymtabType::Static;
567   ArrayRef<ELFYAML::Symbol> Symbols;
568   if (IsStatic && Doc.Symbols)
569     Symbols = *Doc.Symbols;
570   else if (!IsStatic && Doc.DynamicSymbols)
571     Symbols = *Doc.DynamicSymbols;
572 
573   ELFYAML::RawContentSection *RawSec =
574       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
575   if (RawSec && (RawSec->Content || RawSec->Size)) {
576     bool HasSymbolsDescription =
577         (IsStatic && Doc.Symbols) || (!IsStatic && Doc.DynamicSymbols);
578     if (HasSymbolsDescription) {
579       StringRef Property = (IsStatic ? "`Symbols`" : "`DynamicSymbols`");
580       if (RawSec->Content)
581         reportError("cannot specify both `Content` and " + Property +
582                     " for symbol table section '" + RawSec->Name + "'");
583       if (RawSec->Size)
584         reportError("cannot specify both `Size` and " + Property +
585                     " for symbol table section '" + RawSec->Name + "'");
586       return;
587     }
588   }
589 
590   zero(SHeader);
591   SHeader.sh_name = DotShStrtab.getOffset(IsStatic ? ".symtab" : ".dynsym");
592 
593   if (YAMLSec)
594     SHeader.sh_type = YAMLSec->Type;
595   else
596     SHeader.sh_type = IsStatic ? ELF::SHT_SYMTAB : ELF::SHT_DYNSYM;
597 
598   if (RawSec && !RawSec->Link.empty()) {
599     // If the Link field is explicitly defined in the document,
600     // we should use it.
601     SHeader.sh_link = toSectionIndex(RawSec->Link, RawSec->Name);
602   } else {
603     // When we describe the .dynsym section in the document explicitly, it is
604     // allowed to omit the "DynamicSymbols" tag. In this case .dynstr is not
605     // added implicitly and we should be able to leave the Link zeroed if
606     // .dynstr is not defined.
607     unsigned Link = 0;
608     if (IsStatic)
609       Link = SN2I.get(".strtab");
610     else
611       SN2I.lookup(".dynstr", Link);
612     SHeader.sh_link = Link;
613   }
614 
615   if (YAMLSec && YAMLSec->Flags)
616     SHeader.sh_flags = *YAMLSec->Flags;
617   else if (!IsStatic)
618     SHeader.sh_flags = ELF::SHF_ALLOC;
619 
620   // If the symbol table section is explicitly described in the YAML
621   // then we should set the fields requested.
622   SHeader.sh_info = (RawSec && RawSec->Info) ? (unsigned)(*RawSec->Info)
623                                              : findFirstNonGlobal(Symbols) + 1;
624   SHeader.sh_entsize = (YAMLSec && YAMLSec->EntSize)
625                            ? (uint64_t)(*YAMLSec->EntSize)
626                            : sizeof(Elf_Sym);
627   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 8;
628   SHeader.sh_addr = YAMLSec ? (uint64_t)YAMLSec->Address : 0;
629 
630   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
631   if (RawSec && (RawSec->Content || RawSec->Size)) {
632     assert(Symbols.empty());
633     SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
634     return;
635   }
636 
637   std::vector<Elf_Sym> Syms =
638       toELFSymbols(Symbols, IsStatic ? DotStrtab : DotDynstr);
639   writeArrayData(OS, makeArrayRef(Syms));
640   SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
641 }
642 
643 template <class ELFT>
644 void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
645                                              StringTableBuilder &STB,
646                                              ContiguousBlobAccumulator &CBA,
647                                              ELFYAML::Section *YAMLSec) {
648   zero(SHeader);
649   SHeader.sh_name = DotShStrtab.getOffset(Name);
650   SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_STRTAB;
651   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
652 
653   ELFYAML::RawContentSection *RawSec =
654       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
655 
656   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
657   if (RawSec && (RawSec->Content || RawSec->Size)) {
658     SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
659   } else {
660     STB.write(OS);
661     SHeader.sh_size = STB.getSize();
662   }
663 
664   if (YAMLSec && YAMLSec->EntSize)
665     SHeader.sh_entsize = *YAMLSec->EntSize;
666 
667   if (RawSec && RawSec->Info)
668     SHeader.sh_info = *RawSec->Info;
669 
670   if (YAMLSec && YAMLSec->Flags)
671     SHeader.sh_flags = *YAMLSec->Flags;
672   else if (Name == ".dynstr")
673     SHeader.sh_flags = ELF::SHF_ALLOC;
674 
675   // If the section is explicitly described in the YAML
676   // then we want to use its section address.
677   if (YAMLSec)
678     SHeader.sh_addr = YAMLSec->Address;
679 }
680 
681 template <class ELFT> void ELFState<ELFT>::reportError(const Twine &Msg) {
682   ErrHandler(Msg);
683   HasError = true;
684 }
685 
686 template <class ELFT>
687 std::vector<Fragment>
688 ELFState<ELFT>::getPhdrFragments(const ELFYAML::ProgramHeader &Phdr,
689                                  ArrayRef<typename ELFT::Shdr> SHeaders) {
690   DenseMap<StringRef, ELFYAML::Fill *> NameToFill;
691   for (const std::unique_ptr<ELFYAML::Chunk> &D : Doc.Chunks)
692     if (auto S = dyn_cast<ELFYAML::Fill>(D.get()))
693       NameToFill[S->Name] = S;
694 
695   std::vector<Fragment> Ret;
696   for (const ELFYAML::SectionName &SecName : Phdr.Sections) {
697     unsigned Index;
698     if (SN2I.lookup(SecName.Section, Index)) {
699       const typename ELFT::Shdr &H = SHeaders[Index];
700       Ret.push_back({H.sh_offset, H.sh_size, H.sh_type, H.sh_addralign});
701       continue;
702     }
703 
704     if (ELFYAML::Fill *Fill = NameToFill.lookup(SecName.Section)) {
705       Ret.push_back({Fill->ShOffset, Fill->Size, llvm::ELF::SHT_PROGBITS,
706                      /*ShAddrAlign=*/1});
707       continue;
708     }
709 
710     reportError("unknown section or fill referenced: '" + SecName.Section +
711                 "' by program header");
712   }
713 
714   return Ret;
715 }
716 
717 template <class ELFT>
718 void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
719                                             std::vector<Elf_Shdr> &SHeaders) {
720   uint32_t PhdrIdx = 0;
721   for (auto &YamlPhdr : Doc.ProgramHeaders) {
722     Elf_Phdr &PHeader = PHeaders[PhdrIdx++];
723     std::vector<Fragment> Fragments = getPhdrFragments(YamlPhdr, SHeaders);
724 
725     if (YamlPhdr.Offset) {
726       PHeader.p_offset = *YamlPhdr.Offset;
727     } else {
728       if (YamlPhdr.Sections.size())
729         PHeader.p_offset = UINT32_MAX;
730       else
731         PHeader.p_offset = 0;
732 
733       // Find the minimum offset for the program header.
734       for (const Fragment &F : Fragments)
735         PHeader.p_offset = std::min((uint64_t)PHeader.p_offset, F.Offset);
736     }
737 
738     // Find the maximum offset of the end of a section in order to set p_filesz
739     // and p_memsz. When setting p_filesz, trailing SHT_NOBITS sections are not
740     // counted.
741     uint64_t FileOffset = PHeader.p_offset, MemOffset = PHeader.p_offset;
742     for (const Fragment &F : Fragments) {
743       uint64_t End = F.Offset + F.Size;
744       MemOffset = std::max(MemOffset, End);
745 
746       if (F.Type != llvm::ELF::SHT_NOBITS)
747         FileOffset = std::max(FileOffset, End);
748     }
749 
750     // Set the file size and the memory size if not set explicitly.
751     PHeader.p_filesz = YamlPhdr.FileSize ? uint64_t(*YamlPhdr.FileSize)
752                                          : FileOffset - PHeader.p_offset;
753     PHeader.p_memsz = YamlPhdr.MemSize ? uint64_t(*YamlPhdr.MemSize)
754                                        : MemOffset - PHeader.p_offset;
755 
756     if (YamlPhdr.Align) {
757       PHeader.p_align = *YamlPhdr.Align;
758     } else {
759       // Set the alignment of the segment to be the maximum alignment of the
760       // sections so that by default the segment has a valid and sensible
761       // alignment.
762       PHeader.p_align = 1;
763       for (const Fragment &F : Fragments)
764         PHeader.p_align = std::max((uint64_t)PHeader.p_align, F.AddrAlign);
765     }
766   }
767 }
768 
769 template <class ELFT>
770 void ELFState<ELFT>::writeSectionContent(
771     Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section,
772     ContiguousBlobAccumulator &CBA) {
773   raw_ostream &OS =
774       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
775   SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
776 
777   if (Section.EntSize)
778     SHeader.sh_entsize = *Section.EntSize;
779 
780   if (Section.Info)
781     SHeader.sh_info = *Section.Info;
782 }
783 
784 static bool isMips64EL(const ELFYAML::Object &Doc) {
785   return Doc.Header.Machine == ELFYAML::ELF_EM(llvm::ELF::EM_MIPS) &&
786          Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64) &&
787          Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
788 }
789 
790 template <class ELFT>
791 void ELFState<ELFT>::writeSectionContent(
792     Elf_Shdr &SHeader, const ELFYAML::RelocationSection &Section,
793     ContiguousBlobAccumulator &CBA) {
794   assert((Section.Type == llvm::ELF::SHT_REL ||
795           Section.Type == llvm::ELF::SHT_RELA) &&
796          "Section type is not SHT_REL nor SHT_RELA");
797 
798   bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
799   SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
800   SHeader.sh_size = SHeader.sh_entsize * Section.Relocations.size();
801 
802   // For relocation section set link to .symtab by default.
803   unsigned Link = 0;
804   if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
805     SHeader.sh_link = Link;
806 
807   if (!Section.RelocatableSec.empty())
808     SHeader.sh_info = toSectionIndex(Section.RelocatableSec, Section.Name);
809 
810   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
811   for (const auto &Rel : Section.Relocations) {
812     unsigned SymIdx = Rel.Symbol ? toSymbolIndex(*Rel.Symbol, Section.Name,
813                                                  Section.Link == ".dynsym")
814                                  : 0;
815     if (IsRela) {
816       Elf_Rela REntry;
817       zero(REntry);
818       REntry.r_offset = Rel.Offset;
819       REntry.r_addend = Rel.Addend;
820       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
821       OS.write((const char *)&REntry, sizeof(REntry));
822     } else {
823       Elf_Rel REntry;
824       zero(REntry);
825       REntry.r_offset = Rel.Offset;
826       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
827       OS.write((const char *)&REntry, sizeof(REntry));
828     }
829   }
830 }
831 
832 template <class ELFT>
833 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
834                                          const ELFYAML::RelrSection &Section,
835                                          ContiguousBlobAccumulator &CBA) {
836   raw_ostream &OS =
837       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
838   SHeader.sh_entsize =
839       Section.EntSize ? uint64_t(*Section.EntSize) : sizeof(Elf_Relr);
840 
841   if (Section.Content) {
842     SHeader.sh_size = writeContent(OS, Section.Content, None);
843     return;
844   }
845 
846   if (!Section.Entries)
847     return;
848 
849   for (llvm::yaml::Hex64 E : *Section.Entries) {
850     if (!ELFT::Is64Bits && E > UINT32_MAX)
851       reportError(Section.Name + ": the value is too large for 32-bits: 0x" +
852                   Twine::utohexstr(E));
853     support::endian::write<uintX_t>(OS, E, ELFT::TargetEndianness);
854   }
855 
856   SHeader.sh_size = sizeof(uintX_t) * Section.Entries->size();
857 }
858 
859 template <class ELFT>
860 void ELFState<ELFT>::writeSectionContent(
861     Elf_Shdr &SHeader, const ELFYAML::SymtabShndxSection &Shndx,
862     ContiguousBlobAccumulator &CBA) {
863   raw_ostream &OS =
864       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
865 
866   for (uint32_t E : Shndx.Entries)
867     support::endian::write<uint32_t>(OS, E, ELFT::TargetEndianness);
868 
869   SHeader.sh_entsize = Shndx.EntSize ? (uint64_t)*Shndx.EntSize : 4;
870   SHeader.sh_size = Shndx.Entries.size() * SHeader.sh_entsize;
871 }
872 
873 template <class ELFT>
874 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
875                                          const ELFYAML::Group &Section,
876                                          ContiguousBlobAccumulator &CBA) {
877   assert(Section.Type == llvm::ELF::SHT_GROUP &&
878          "Section type is not SHT_GROUP");
879 
880   unsigned Link = 0;
881   if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
882     SHeader.sh_link = Link;
883 
884   SHeader.sh_entsize = 4;
885   SHeader.sh_size = SHeader.sh_entsize * Section.Members.size();
886 
887   if (Section.Signature)
888     SHeader.sh_info =
889         toSymbolIndex(*Section.Signature, Section.Name, /*IsDynamic=*/false);
890 
891   raw_ostream &OS =
892       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
893 
894   for (const ELFYAML::SectionOrType &Member : Section.Members) {
895     unsigned int SectionIndex = 0;
896     if (Member.sectionNameOrType == "GRP_COMDAT")
897       SectionIndex = llvm::ELF::GRP_COMDAT;
898     else
899       SectionIndex = toSectionIndex(Member.sectionNameOrType, Section.Name);
900     support::endian::write<uint32_t>(OS, SectionIndex, ELFT::TargetEndianness);
901   }
902 }
903 
904 template <class ELFT>
905 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
906                                          const ELFYAML::SymverSection &Section,
907                                          ContiguousBlobAccumulator &CBA) {
908   raw_ostream &OS =
909       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
910   for (uint16_t Version : Section.Entries)
911     support::endian::write<uint16_t>(OS, Version, ELFT::TargetEndianness);
912 
913   SHeader.sh_entsize = Section.EntSize ? (uint64_t)*Section.EntSize : 2;
914   SHeader.sh_size = Section.Entries.size() * SHeader.sh_entsize;
915 }
916 
917 template <class ELFT>
918 void ELFState<ELFT>::writeSectionContent(
919     Elf_Shdr &SHeader, const ELFYAML::StackSizesSection &Section,
920     ContiguousBlobAccumulator &CBA) {
921   raw_ostream &OS =
922       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
923 
924   if (Section.Content || Section.Size) {
925     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
926     return;
927   }
928 
929   for (const ELFYAML::StackSizeEntry &E : *Section.Entries) {
930     support::endian::write<uintX_t>(OS, E.Address, ELFT::TargetEndianness);
931     SHeader.sh_size += sizeof(uintX_t) + encodeULEB128(E.Size, OS);
932   }
933 }
934 
935 template <class ELFT>
936 void ELFState<ELFT>::writeSectionContent(
937     Elf_Shdr &SHeader, const ELFYAML::LinkerOptionsSection &Section,
938     ContiguousBlobAccumulator &CBA) {
939   raw_ostream &OS =
940       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
941 
942   if (Section.Content) {
943     SHeader.sh_size = writeContent(OS, Section.Content, None);
944     return;
945   }
946 
947   if (!Section.Options)
948     return;
949 
950   for (const ELFYAML::LinkerOption &LO : *Section.Options) {
951     OS.write(LO.Key.data(), LO.Key.size());
952     OS.write('\0');
953     OS.write(LO.Value.data(), LO.Value.size());
954     OS.write('\0');
955     SHeader.sh_size += (LO.Key.size() + LO.Value.size() + 2);
956   }
957 }
958 
959 template <class ELFT>
960 void ELFState<ELFT>::writeSectionContent(
961     Elf_Shdr &SHeader, const ELFYAML::DependentLibrariesSection &Section,
962     ContiguousBlobAccumulator &CBA) {
963   raw_ostream &OS =
964       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
965 
966   if (Section.Content) {
967     SHeader.sh_size = writeContent(OS, Section.Content, None);
968     return;
969   }
970 
971   if (!Section.Libs)
972     return;
973 
974   for (StringRef Lib : *Section.Libs) {
975     OS.write(Lib.data(), Lib.size());
976     OS.write('\0');
977     SHeader.sh_size += Lib.size() + 1;
978   }
979 }
980 
981 template <class ELFT>
982 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
983                                          const ELFYAML::HashSection &Section,
984                                          ContiguousBlobAccumulator &CBA) {
985   raw_ostream &OS =
986       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
987 
988   unsigned Link = 0;
989   if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
990     SHeader.sh_link = Link;
991 
992   if (Section.Content || Section.Size) {
993     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
994     return;
995   }
996 
997   support::endian::write<uint32_t>(OS, Section.Bucket->size(),
998                                    ELFT::TargetEndianness);
999   support::endian::write<uint32_t>(OS, Section.Chain->size(),
1000                                    ELFT::TargetEndianness);
1001   for (uint32_t Val : *Section.Bucket)
1002     support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
1003   for (uint32_t Val : *Section.Chain)
1004     support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
1005 
1006   SHeader.sh_size = (2 + Section.Bucket->size() + Section.Chain->size()) * 4;
1007 }
1008 
1009 template <class ELFT>
1010 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
1011                                          const ELFYAML::VerdefSection &Section,
1012                                          ContiguousBlobAccumulator &CBA) {
1013   typedef typename ELFT::Verdef Elf_Verdef;
1014   typedef typename ELFT::Verdaux Elf_Verdaux;
1015   raw_ostream &OS =
1016       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1017 
1018   SHeader.sh_info = Section.Info;
1019 
1020   if (Section.Content) {
1021     SHeader.sh_size = writeContent(OS, Section.Content, None);
1022     return;
1023   }
1024 
1025   if (!Section.Entries)
1026     return;
1027 
1028   uint64_t AuxCnt = 0;
1029   for (size_t I = 0; I < Section.Entries->size(); ++I) {
1030     const ELFYAML::VerdefEntry &E = (*Section.Entries)[I];
1031 
1032     Elf_Verdef VerDef;
1033     VerDef.vd_version = E.Version;
1034     VerDef.vd_flags = E.Flags;
1035     VerDef.vd_ndx = E.VersionNdx;
1036     VerDef.vd_hash = E.Hash;
1037     VerDef.vd_aux = sizeof(Elf_Verdef);
1038     VerDef.vd_cnt = E.VerNames.size();
1039     if (I == Section.Entries->size() - 1)
1040       VerDef.vd_next = 0;
1041     else
1042       VerDef.vd_next =
1043           sizeof(Elf_Verdef) + E.VerNames.size() * sizeof(Elf_Verdaux);
1044     OS.write((const char *)&VerDef, sizeof(Elf_Verdef));
1045 
1046     for (size_t J = 0; J < E.VerNames.size(); ++J, ++AuxCnt) {
1047       Elf_Verdaux VernAux;
1048       VernAux.vda_name = DotDynstr.getOffset(E.VerNames[J]);
1049       if (J == E.VerNames.size() - 1)
1050         VernAux.vda_next = 0;
1051       else
1052         VernAux.vda_next = sizeof(Elf_Verdaux);
1053       OS.write((const char *)&VernAux, sizeof(Elf_Verdaux));
1054     }
1055   }
1056 
1057   SHeader.sh_size = Section.Entries->size() * sizeof(Elf_Verdef) +
1058                     AuxCnt * sizeof(Elf_Verdaux);
1059 }
1060 
1061 template <class ELFT>
1062 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
1063                                          const ELFYAML::VerneedSection &Section,
1064                                          ContiguousBlobAccumulator &CBA) {
1065   typedef typename ELFT::Verneed Elf_Verneed;
1066   typedef typename ELFT::Vernaux Elf_Vernaux;
1067 
1068   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1069   SHeader.sh_info = Section.Info;
1070 
1071   if (Section.Content) {
1072     SHeader.sh_size = writeContent(OS, Section.Content, None);
1073     return;
1074   }
1075 
1076   if (!Section.VerneedV)
1077     return;
1078 
1079   uint64_t AuxCnt = 0;
1080   for (size_t I = 0; I < Section.VerneedV->size(); ++I) {
1081     const ELFYAML::VerneedEntry &VE = (*Section.VerneedV)[I];
1082 
1083     Elf_Verneed VerNeed;
1084     VerNeed.vn_version = VE.Version;
1085     VerNeed.vn_file = DotDynstr.getOffset(VE.File);
1086     if (I == Section.VerneedV->size() - 1)
1087       VerNeed.vn_next = 0;
1088     else
1089       VerNeed.vn_next =
1090           sizeof(Elf_Verneed) + VE.AuxV.size() * sizeof(Elf_Vernaux);
1091     VerNeed.vn_cnt = VE.AuxV.size();
1092     VerNeed.vn_aux = sizeof(Elf_Verneed);
1093     OS.write((const char *)&VerNeed, sizeof(Elf_Verneed));
1094 
1095     for (size_t J = 0; J < VE.AuxV.size(); ++J, ++AuxCnt) {
1096       const ELFYAML::VernauxEntry &VAuxE = VE.AuxV[J];
1097 
1098       Elf_Vernaux VernAux;
1099       VernAux.vna_hash = VAuxE.Hash;
1100       VernAux.vna_flags = VAuxE.Flags;
1101       VernAux.vna_other = VAuxE.Other;
1102       VernAux.vna_name = DotDynstr.getOffset(VAuxE.Name);
1103       if (J == VE.AuxV.size() - 1)
1104         VernAux.vna_next = 0;
1105       else
1106         VernAux.vna_next = sizeof(Elf_Vernaux);
1107       OS.write((const char *)&VernAux, sizeof(Elf_Vernaux));
1108     }
1109   }
1110 
1111   SHeader.sh_size = Section.VerneedV->size() * sizeof(Elf_Verneed) +
1112                     AuxCnt * sizeof(Elf_Vernaux);
1113 }
1114 
1115 template <class ELFT>
1116 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
1117                                          const ELFYAML::MipsABIFlags &Section,
1118                                          ContiguousBlobAccumulator &CBA) {
1119   assert(Section.Type == llvm::ELF::SHT_MIPS_ABIFLAGS &&
1120          "Section type is not SHT_MIPS_ABIFLAGS");
1121 
1122   object::Elf_Mips_ABIFlags<ELFT> Flags;
1123   zero(Flags);
1124   SHeader.sh_entsize = sizeof(Flags);
1125   SHeader.sh_size = SHeader.sh_entsize;
1126 
1127   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1128   Flags.version = Section.Version;
1129   Flags.isa_level = Section.ISALevel;
1130   Flags.isa_rev = Section.ISARevision;
1131   Flags.gpr_size = Section.GPRSize;
1132   Flags.cpr1_size = Section.CPR1Size;
1133   Flags.cpr2_size = Section.CPR2Size;
1134   Flags.fp_abi = Section.FpABI;
1135   Flags.isa_ext = Section.ISAExtension;
1136   Flags.ases = Section.ASEs;
1137   Flags.flags1 = Section.Flags1;
1138   Flags.flags2 = Section.Flags2;
1139   OS.write((const char *)&Flags, sizeof(Flags));
1140 }
1141 
1142 template <class ELFT>
1143 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
1144                                          const ELFYAML::DynamicSection &Section,
1145                                          ContiguousBlobAccumulator &CBA) {
1146   assert(Section.Type == llvm::ELF::SHT_DYNAMIC &&
1147          "Section type is not SHT_DYNAMIC");
1148 
1149   if (!Section.Entries.empty() && Section.Content)
1150     reportError("cannot specify both raw content and explicit entries "
1151                 "for dynamic section '" +
1152                 Section.Name + "'");
1153 
1154   if (Section.Content)
1155     SHeader.sh_size = Section.Content->binary_size();
1156   else
1157     SHeader.sh_size = 2 * sizeof(uintX_t) * Section.Entries.size();
1158   if (Section.EntSize)
1159     SHeader.sh_entsize = *Section.EntSize;
1160   else
1161     SHeader.sh_entsize = sizeof(Elf_Dyn);
1162 
1163   raw_ostream &OS =
1164       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1165   for (const ELFYAML::DynamicEntry &DE : Section.Entries) {
1166     support::endian::write<uintX_t>(OS, DE.Tag, ELFT::TargetEndianness);
1167     support::endian::write<uintX_t>(OS, DE.Val, ELFT::TargetEndianness);
1168   }
1169   if (Section.Content)
1170     Section.Content->writeAsBinary(OS);
1171 }
1172 
1173 template <class ELFT>
1174 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
1175                                          const ELFYAML::AddrsigSection &Section,
1176                                          ContiguousBlobAccumulator &CBA) {
1177   raw_ostream &OS =
1178       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1179 
1180   unsigned Link = 0;
1181   if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
1182     SHeader.sh_link = Link;
1183 
1184   if (Section.Content || Section.Size) {
1185     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
1186     return;
1187   }
1188 
1189   for (const ELFYAML::AddrsigSymbol &Sym : *Section.Symbols) {
1190     uint64_t Val =
1191         Sym.Name ? toSymbolIndex(*Sym.Name, Section.Name, /*IsDynamic=*/false)
1192                  : (uint32_t)*Sym.Index;
1193     SHeader.sh_size += encodeULEB128(Val, OS);
1194   }
1195 }
1196 
1197 template <class ELFT>
1198 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
1199                                          const ELFYAML::NoteSection &Section,
1200                                          ContiguousBlobAccumulator &CBA) {
1201   raw_ostream &OS =
1202       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1203   uint64_t Offset = OS.tell();
1204 
1205   if (Section.Content || Section.Size) {
1206     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
1207     return;
1208   }
1209 
1210   for (const ELFYAML::NoteEntry &NE : *Section.Notes) {
1211     // Write name size.
1212     if (NE.Name.empty())
1213       support::endian::write<uint32_t>(OS, 0, ELFT::TargetEndianness);
1214     else
1215       support::endian::write<uint32_t>(OS, NE.Name.size() + 1,
1216                                        ELFT::TargetEndianness);
1217 
1218     // Write description size.
1219     if (NE.Desc.binary_size() == 0)
1220       support::endian::write<uint32_t>(OS, 0, ELFT::TargetEndianness);
1221     else
1222       support::endian::write<uint32_t>(OS, NE.Desc.binary_size(),
1223                                        ELFT::TargetEndianness);
1224 
1225     // Write type.
1226     support::endian::write<uint32_t>(OS, NE.Type, ELFT::TargetEndianness);
1227 
1228     // Write name, null terminator and padding.
1229     if (!NE.Name.empty()) {
1230       support::endian::write<uint8_t>(OS, arrayRefFromStringRef(NE.Name),
1231                                       ELFT::TargetEndianness);
1232       support::endian::write<uint8_t>(OS, 0, ELFT::TargetEndianness);
1233       CBA.padToAlignment(4);
1234     }
1235 
1236     // Write description and padding.
1237     if (NE.Desc.binary_size() != 0) {
1238       NE.Desc.writeAsBinary(OS);
1239       CBA.padToAlignment(4);
1240     }
1241   }
1242 
1243   SHeader.sh_size = OS.tell() - Offset;
1244 }
1245 
1246 template <class ELFT>
1247 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
1248                                          const ELFYAML::GnuHashSection &Section,
1249                                          ContiguousBlobAccumulator &CBA) {
1250   raw_ostream &OS =
1251       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1252 
1253   unsigned Link = 0;
1254   if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
1255     SHeader.sh_link = Link;
1256 
1257   if (Section.Content) {
1258     SHeader.sh_size = writeContent(OS, Section.Content, None);
1259     return;
1260   }
1261 
1262   // We write the header first, starting with the hash buckets count. Normally
1263   // it is the number of entries in HashBuckets, but the "NBuckets" property can
1264   // be used to override this field, which is useful for producing broken
1265   // objects.
1266   if (Section.Header->NBuckets)
1267     support::endian::write<uint32_t>(OS, *Section.Header->NBuckets,
1268                                      ELFT::TargetEndianness);
1269   else
1270     support::endian::write<uint32_t>(OS, Section.HashBuckets->size(),
1271                                      ELFT::TargetEndianness);
1272 
1273   // Write the index of the first symbol in the dynamic symbol table accessible
1274   // via the hash table.
1275   support::endian::write<uint32_t>(OS, Section.Header->SymNdx,
1276                                    ELFT::TargetEndianness);
1277 
1278   // Write the number of words in the Bloom filter. As above, the "MaskWords"
1279   // property can be used to set this field to any value.
1280   if (Section.Header->MaskWords)
1281     support::endian::write<uint32_t>(OS, *Section.Header->MaskWords,
1282                                      ELFT::TargetEndianness);
1283   else
1284     support::endian::write<uint32_t>(OS, Section.BloomFilter->size(),
1285                                      ELFT::TargetEndianness);
1286 
1287   // Write the shift constant used by the Bloom filter.
1288   support::endian::write<uint32_t>(OS, Section.Header->Shift2,
1289                                    ELFT::TargetEndianness);
1290 
1291   // We've finished writing the header. Now write the Bloom filter.
1292   for (llvm::yaml::Hex64 Val : *Section.BloomFilter)
1293     support::endian::write<typename ELFT::uint>(OS, Val,
1294                                                 ELFT::TargetEndianness);
1295 
1296   // Write an array of hash buckets.
1297   for (llvm::yaml::Hex32 Val : *Section.HashBuckets)
1298     support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
1299 
1300   // Write an array of hash values.
1301   for (llvm::yaml::Hex32 Val : *Section.HashValues)
1302     support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
1303 
1304   SHeader.sh_size = 16 /*Header size*/ +
1305                     Section.BloomFilter->size() * sizeof(typename ELFT::uint) +
1306                     Section.HashBuckets->size() * 4 +
1307                     Section.HashValues->size() * 4;
1308 }
1309 
1310 template <class ELFT>
1311 void ELFState<ELFT>::writeFill(ELFYAML::Fill &Fill,
1312                                ContiguousBlobAccumulator &CBA) {
1313   raw_ostream &OS = CBA.getOSAndAlignedOffset(Fill.ShOffset, /*Align=*/1);
1314 
1315   size_t PatternSize = Fill.Pattern ? Fill.Pattern->binary_size() : 0;
1316   if (!PatternSize) {
1317     OS.write_zeros(Fill.Size);
1318     return;
1319   }
1320 
1321   // Fill the content with the specified pattern.
1322   uint64_t Written = 0;
1323   for (; Written + PatternSize <= Fill.Size; Written += PatternSize)
1324     Fill.Pattern->writeAsBinary(OS);
1325   Fill.Pattern->writeAsBinary(OS, Fill.Size - Written);
1326 }
1327 
1328 template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
1329   size_t SecNdx = -1;
1330   StringSet<> Seen;
1331   for (size_t I = 0; I < Doc.Chunks.size(); ++I) {
1332     const std::unique_ptr<ELFYAML::Chunk> &C = Doc.Chunks[I];
1333     bool IsSection = isa<ELFYAML::Section>(C.get());
1334     if (IsSection)
1335       ++SecNdx;
1336 
1337     if (C->Name.empty())
1338       continue;
1339 
1340     if (!Seen.insert(C->Name).second)
1341       reportError("repeated section/fill name: '" + C->Name +
1342                   "' at YAML section/fill number " + Twine(I));
1343     if (!IsSection || HasError)
1344       continue;
1345 
1346     if (!SN2I.addName(C->Name, SecNdx))
1347       llvm_unreachable("buildSectionIndex() failed");
1348     DotShStrtab.add(ELFYAML::dropUniqueSuffix(C->Name));
1349   }
1350 
1351   DotShStrtab.finalize();
1352 }
1353 
1354 template <class ELFT> void ELFState<ELFT>::buildSymbolIndexes() {
1355   auto Build = [this](ArrayRef<ELFYAML::Symbol> V, NameToIdxMap &Map) {
1356     for (size_t I = 0, S = V.size(); I < S; ++I) {
1357       const ELFYAML::Symbol &Sym = V[I];
1358       if (!Sym.Name.empty() && !Map.addName(Sym.Name, I + 1))
1359         reportError("repeated symbol name: '" + Sym.Name + "'");
1360     }
1361   };
1362 
1363   if (Doc.Symbols)
1364     Build(*Doc.Symbols, SymN2I);
1365   if (Doc.DynamicSymbols)
1366     Build(*Doc.DynamicSymbols, DynSymN2I);
1367 }
1368 
1369 template <class ELFT> void ELFState<ELFT>::finalizeStrings() {
1370   // Add the regular symbol names to .strtab section.
1371   if (Doc.Symbols)
1372     for (const ELFYAML::Symbol &Sym : *Doc.Symbols)
1373       DotStrtab.add(ELFYAML::dropUniqueSuffix(Sym.Name));
1374   DotStrtab.finalize();
1375 
1376   // Add the dynamic symbol names to .dynstr section.
1377   if (Doc.DynamicSymbols)
1378     for (const ELFYAML::Symbol &Sym : *Doc.DynamicSymbols)
1379       DotDynstr.add(ELFYAML::dropUniqueSuffix(Sym.Name));
1380 
1381   // SHT_GNU_verdef and SHT_GNU_verneed sections might also
1382   // add strings to .dynstr section.
1383   for (const ELFYAML::Chunk *Sec : Doc.getSections()) {
1384     if (auto VerNeed = dyn_cast<ELFYAML::VerneedSection>(Sec)) {
1385       if (VerNeed->VerneedV) {
1386         for (const ELFYAML::VerneedEntry &VE : *VerNeed->VerneedV) {
1387           DotDynstr.add(VE.File);
1388           for (const ELFYAML::VernauxEntry &Aux : VE.AuxV)
1389             DotDynstr.add(Aux.Name);
1390         }
1391       }
1392     } else if (auto VerDef = dyn_cast<ELFYAML::VerdefSection>(Sec)) {
1393       if (VerDef->Entries)
1394         for (const ELFYAML::VerdefEntry &E : *VerDef->Entries)
1395           for (StringRef Name : E.VerNames)
1396             DotDynstr.add(Name);
1397     }
1398   }
1399 
1400   DotDynstr.finalize();
1401 }
1402 
1403 template <class ELFT>
1404 bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
1405                               yaml::ErrorHandler EH) {
1406   ELFState<ELFT> State(Doc, EH);
1407 
1408   // Finalize .strtab and .dynstr sections. We do that early because want to
1409   // finalize the string table builders before writing the content of the
1410   // sections that might want to use them.
1411   State.finalizeStrings();
1412 
1413   State.buildSectionIndex();
1414   if (State.HasError)
1415     return false;
1416 
1417   State.buildSymbolIndexes();
1418 
1419   std::vector<Elf_Phdr> PHeaders;
1420   State.initProgramHeaders(PHeaders);
1421 
1422   // XXX: This offset is tightly coupled with the order that we write
1423   // things to `OS`.
1424   const size_t SectionContentBeginOffset =
1425       sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * Doc.ProgramHeaders.size();
1426   ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
1427 
1428   std::vector<Elf_Shdr> SHeaders;
1429   State.initSectionHeaders(SHeaders, CBA);
1430 
1431   // Now we can decide segment offsets.
1432   State.setProgramHeaderLayout(PHeaders, SHeaders);
1433 
1434   if (State.HasError)
1435     return false;
1436 
1437   State.writeELFHeader(CBA, OS);
1438   writeArrayData(OS, makeArrayRef(PHeaders));
1439   CBA.writeBlobToStream(OS);
1440   writeArrayData(OS, makeArrayRef(SHeaders));
1441   return true;
1442 }
1443 
1444 namespace llvm {
1445 namespace yaml {
1446 
1447 bool yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out, ErrorHandler EH) {
1448   bool IsLE = Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
1449   bool Is64Bit = Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
1450   if (Is64Bit) {
1451     if (IsLE)
1452       return ELFState<object::ELF64LE>::writeELF(Out, Doc, EH);
1453     return ELFState<object::ELF64BE>::writeELF(Out, Doc, EH);
1454   }
1455   if (IsLE)
1456     return ELFState<object::ELF32LE>::writeELF(Out, Doc, EH);
1457   return ELFState<object::ELF32BE>::writeELF(Out, Doc, EH);
1458 }
1459 
1460 } // namespace yaml
1461 } // namespace llvm
1462