1 //===- yaml2elf - Convert YAML to a ELF object file -----------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 ///
10 /// \file
11 /// \brief The ELF component of yaml2obj.
12 ///
13 //===----------------------------------------------------------------------===//
14 
15 #include "yaml2obj.h"
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/MC/StringTableBuilder.h"
18 #include "llvm/Object/ELFObjectFile.h"
19 #include "llvm/Object/ELFYAML.h"
20 #include "llvm/Support/ELF.h"
21 #include "llvm/Support/MemoryBuffer.h"
22 #include "llvm/Support/YAMLTraits.h"
23 #include "llvm/Support/raw_ostream.h"
24 
25 using namespace llvm;
26 
27 // This class is used to build up a contiguous binary blob while keeping
28 // track of an offset in the output (which notionally begins at
29 // `InitialOffset`).
30 namespace {
31 class ContiguousBlobAccumulator {
32   const uint64_t InitialOffset;
33   SmallVector<char, 128> Buf;
34   raw_svector_ostream OS;
35 
36   /// \returns The new offset.
padToAlignment(unsigned Align)37   uint64_t padToAlignment(unsigned Align) {
38     uint64_t CurrentOffset = InitialOffset + OS.tell();
39     uint64_t AlignedOffset = RoundUpToAlignment(CurrentOffset, Align);
40     for (; CurrentOffset != AlignedOffset; ++CurrentOffset)
41       OS.write('\0');
42     return AlignedOffset; // == CurrentOffset;
43   }
44 
45 public:
ContiguousBlobAccumulator(uint64_t InitialOffset_)46   ContiguousBlobAccumulator(uint64_t InitialOffset_)
47       : InitialOffset(InitialOffset_), Buf(), OS(Buf) {}
48   template <class Integer>
getOSAndAlignedOffset(Integer & Offset,unsigned Align=16)49   raw_ostream &getOSAndAlignedOffset(Integer &Offset, unsigned Align = 16) {
50     Offset = padToAlignment(Align);
51     return OS;
52   }
writeBlobToStream(raw_ostream & Out)53   void writeBlobToStream(raw_ostream &Out) { Out << OS.str(); }
54 };
55 } // end anonymous namespace
56 
57 // Used to keep track of section and symbol names, so that in the YAML file
58 // sections and symbols can be referenced by name instead of by index.
59 namespace {
60 class NameToIdxMap {
61   StringMap<int> Map;
62 public:
63   /// \returns true if name is already present in the map.
addName(StringRef Name,unsigned i)64   bool addName(StringRef Name, unsigned i) {
65     return !Map.insert(std::make_pair(Name, (int)i)).second;
66   }
67   /// \returns true if name is not present in the map
lookup(StringRef Name,unsigned & Idx) const68   bool lookup(StringRef Name, unsigned &Idx) const {
69     StringMap<int>::const_iterator I = Map.find(Name);
70     if (I == Map.end())
71       return true;
72     Idx = I->getValue();
73     return false;
74   }
75 };
76 } // end anonymous namespace
77 
78 template <class T>
arrayDataSize(ArrayRef<T> A)79 static size_t arrayDataSize(ArrayRef<T> A) {
80   return A.size() * sizeof(T);
81 }
82 
83 template <class T>
writeArrayData(raw_ostream & OS,ArrayRef<T> A)84 static void writeArrayData(raw_ostream &OS, ArrayRef<T> A) {
85   OS.write((const char *)A.data(), arrayDataSize(A));
86 }
87 
88 template <class T>
zero(T & Obj)89 static void zero(T &Obj) {
90   memset(&Obj, 0, sizeof(Obj));
91 }
92 
93 namespace {
94 /// \brief "Single point of truth" for the ELF file construction.
95 /// TODO: This class still has a ways to go before it is truly a "single
96 /// point of truth".
97 template <class ELFT>
98 class ELFState {
99   typedef typename object::ELFFile<ELFT>::Elf_Ehdr Elf_Ehdr;
100   typedef typename object::ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
101   typedef typename object::ELFFile<ELFT>::Elf_Sym Elf_Sym;
102   typedef typename object::ELFFile<ELFT>::Elf_Rel Elf_Rel;
103   typedef typename object::ELFFile<ELFT>::Elf_Rela Elf_Rela;
104 
105   /// \brief The future ".strtab" section.
106   StringTableBuilder DotStrtab;
107 
108   /// \brief The future ".shstrtab" section.
109   StringTableBuilder DotShStrtab;
110 
111   NameToIdxMap SN2I;
112   NameToIdxMap SymN2I;
113   const ELFYAML::Object &Doc;
114 
115   bool buildSectionIndex();
116   bool buildSymbolIndex(std::size_t &StartIndex,
117                         const std::vector<ELFYAML::Symbol> &Symbols);
118   void initELFHeader(Elf_Ehdr &Header);
119   bool initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
120                           ContiguousBlobAccumulator &CBA);
121   void initSymtabSectionHeader(Elf_Shdr &SHeader,
122                                ContiguousBlobAccumulator &CBA);
123   void initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
124                                StringTableBuilder &STB,
125                                ContiguousBlobAccumulator &CBA);
126   void addSymbols(const std::vector<ELFYAML::Symbol> &Symbols,
127                   std::vector<Elf_Sym> &Syms, unsigned SymbolBinding);
128   void writeSectionContent(Elf_Shdr &SHeader,
129                            const ELFYAML::RawContentSection &Section,
130                            ContiguousBlobAccumulator &CBA);
131   bool writeSectionContent(Elf_Shdr &SHeader,
132                            const ELFYAML::RelocationSection &Section,
133                            ContiguousBlobAccumulator &CBA);
134   bool writeSectionContent(Elf_Shdr &SHeader, const ELFYAML::Group &Group,
135                            ContiguousBlobAccumulator &CBA);
136 
137   // - SHT_NULL entry (placed first, i.e. 0'th entry)
138   // - symbol table (.symtab) (placed third to last)
139   // - string table (.strtab) (placed second to last)
140   // - section header string table (.shstrtab) (placed last)
getDotSymTabSecNo() const141   unsigned getDotSymTabSecNo() const { return Doc.Sections.size() + 1; }
getDotStrTabSecNo() const142   unsigned getDotStrTabSecNo() const { return Doc.Sections.size() + 2; }
getDotShStrTabSecNo() const143   unsigned getDotShStrTabSecNo() const { return Doc.Sections.size() + 3; }
getSectionCount() const144   unsigned getSectionCount() const { return Doc.Sections.size() + 4; }
145 
ELFState(const ELFYAML::Object & D)146   ELFState(const ELFYAML::Object &D) : Doc(D) {}
147 
148 public:
149   static int writeELF(raw_ostream &OS, const ELFYAML::Object &Doc);
150 };
151 } // end anonymous namespace
152 
153 template <class ELFT>
initELFHeader(Elf_Ehdr & Header)154 void ELFState<ELFT>::initELFHeader(Elf_Ehdr &Header) {
155   using namespace llvm::ELF;
156   zero(Header);
157   Header.e_ident[EI_MAG0] = 0x7f;
158   Header.e_ident[EI_MAG1] = 'E';
159   Header.e_ident[EI_MAG2] = 'L';
160   Header.e_ident[EI_MAG3] = 'F';
161   Header.e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
162   bool IsLittleEndian = ELFT::TargetEndianness == support::little;
163   Header.e_ident[EI_DATA] = IsLittleEndian ? ELFDATA2LSB : ELFDATA2MSB;
164   Header.e_ident[EI_VERSION] = EV_CURRENT;
165   Header.e_ident[EI_OSABI] = Doc.Header.OSABI;
166   Header.e_ident[EI_ABIVERSION] = 0;
167   Header.e_type = Doc.Header.Type;
168   Header.e_machine = Doc.Header.Machine;
169   Header.e_version = EV_CURRENT;
170   Header.e_entry = Doc.Header.Entry;
171   Header.e_flags = Doc.Header.Flags;
172   Header.e_ehsize = sizeof(Elf_Ehdr);
173   Header.e_shentsize = sizeof(Elf_Shdr);
174   // Immediately following the ELF header.
175   Header.e_shoff = sizeof(Header);
176   Header.e_shnum = getSectionCount();
177   Header.e_shstrndx = getDotShStrTabSecNo();
178 }
179 
180 template <class ELFT>
initSectionHeaders(std::vector<Elf_Shdr> & SHeaders,ContiguousBlobAccumulator & CBA)181 bool ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
182                                         ContiguousBlobAccumulator &CBA) {
183   // Ensure SHN_UNDEF entry is present. An all-zero section header is a
184   // valid SHN_UNDEF entry since SHT_NULL == 0.
185   Elf_Shdr SHeader;
186   zero(SHeader);
187   SHeaders.push_back(SHeader);
188 
189   for (const auto &Sec : Doc.Sections)
190     DotShStrtab.add(Sec->Name);
191   DotShStrtab.finalize(StringTableBuilder::ELF);
192 
193   for (const auto &Sec : Doc.Sections) {
194     zero(SHeader);
195     SHeader.sh_name = DotShStrtab.getOffset(Sec->Name);
196     SHeader.sh_type = Sec->Type;
197     SHeader.sh_flags = Sec->Flags;
198     SHeader.sh_addr = Sec->Address;
199     SHeader.sh_addralign = Sec->AddressAlign;
200 
201     if (!Sec->Link.empty()) {
202       unsigned Index;
203       if (SN2I.lookup(Sec->Link, Index)) {
204         errs() << "error: Unknown section referenced: '" << Sec->Link
205                << "' at YAML section '" << Sec->Name << "'.\n";
206         return false;
207       }
208       SHeader.sh_link = Index;
209     }
210 
211     if (auto S = dyn_cast<ELFYAML::RawContentSection>(Sec.get()))
212       writeSectionContent(SHeader, *S, CBA);
213     else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec.get())) {
214       if (S->Link.empty())
215         // For relocation section set link to .symtab by default.
216         SHeader.sh_link = getDotSymTabSecNo();
217 
218       unsigned Index;
219       if (SN2I.lookup(S->Info, Index)) {
220         errs() << "error: Unknown section referenced: '" << S->Info
221                << "' at YAML section '" << S->Name << "'.\n";
222         return false;
223       }
224       SHeader.sh_info = Index;
225 
226       if (!writeSectionContent(SHeader, *S, CBA))
227         return false;
228     } else if (auto S = dyn_cast<ELFYAML::Group>(Sec.get())) {
229       unsigned SymIdx;
230       if (SymN2I.lookup(S->Info, SymIdx)) {
231         errs() << "error: Unknown symbol referenced: '" << S->Info
232                << "' at YAML section '" << S->Name << "'.\n";
233         return false;
234       }
235       SHeader.sh_info = SymIdx;
236       if (!writeSectionContent(SHeader, *S, CBA))
237         return false;
238     } else
239       llvm_unreachable("Unknown section type");
240 
241     SHeaders.push_back(SHeader);
242   }
243   return true;
244 }
245 
246 template <class ELFT>
initSymtabSectionHeader(Elf_Shdr & SHeader,ContiguousBlobAccumulator & CBA)247 void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
248                                              ContiguousBlobAccumulator &CBA) {
249   zero(SHeader);
250   SHeader.sh_name = DotShStrtab.getOffset(".symtab");
251   SHeader.sh_type = ELF::SHT_SYMTAB;
252   SHeader.sh_link = getDotStrTabSecNo();
253   // One greater than symbol table index of the last local symbol.
254   SHeader.sh_info = Doc.Symbols.Local.size() + 1;
255   SHeader.sh_entsize = sizeof(Elf_Sym);
256 
257   std::vector<Elf_Sym> Syms;
258   {
259     // Ensure STN_UNDEF is present
260     Elf_Sym Sym;
261     zero(Sym);
262     Syms.push_back(Sym);
263   }
264 
265   // Add symbol names to .strtab.
266   for (const auto &Sym : Doc.Symbols.Local)
267     DotStrtab.add(Sym.Name);
268   for (const auto &Sym : Doc.Symbols.Global)
269     DotStrtab.add(Sym.Name);
270   for (const auto &Sym : Doc.Symbols.Weak)
271     DotStrtab.add(Sym.Name);
272   DotStrtab.finalize(StringTableBuilder::ELF);
273 
274   addSymbols(Doc.Symbols.Local, Syms, ELF::STB_LOCAL);
275   addSymbols(Doc.Symbols.Global, Syms, ELF::STB_GLOBAL);
276   addSymbols(Doc.Symbols.Weak, Syms, ELF::STB_WEAK);
277 
278   writeArrayData(CBA.getOSAndAlignedOffset(SHeader.sh_offset),
279                  makeArrayRef(Syms));
280   SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
281 }
282 
283 template <class ELFT>
initStrtabSectionHeader(Elf_Shdr & SHeader,StringRef Name,StringTableBuilder & STB,ContiguousBlobAccumulator & CBA)284 void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
285                                              StringTableBuilder &STB,
286                                              ContiguousBlobAccumulator &CBA) {
287   zero(SHeader);
288   SHeader.sh_name = DotShStrtab.getOffset(Name);
289   SHeader.sh_type = ELF::SHT_STRTAB;
290   CBA.getOSAndAlignedOffset(SHeader.sh_offset) << STB.data();
291   SHeader.sh_size = STB.data().size();
292   SHeader.sh_addralign = 1;
293 }
294 
295 template <class ELFT>
addSymbols(const std::vector<ELFYAML::Symbol> & Symbols,std::vector<Elf_Sym> & Syms,unsigned SymbolBinding)296 void ELFState<ELFT>::addSymbols(const std::vector<ELFYAML::Symbol> &Symbols,
297                                 std::vector<Elf_Sym> &Syms,
298                                 unsigned SymbolBinding) {
299   for (const auto &Sym : Symbols) {
300     Elf_Sym Symbol;
301     zero(Symbol);
302     if (!Sym.Name.empty())
303       Symbol.st_name = DotStrtab.getOffset(Sym.Name);
304     Symbol.setBindingAndType(SymbolBinding, Sym.Type);
305     if (!Sym.Section.empty()) {
306       unsigned Index;
307       if (SN2I.lookup(Sym.Section, Index)) {
308         errs() << "error: Unknown section referenced: '" << Sym.Section
309                << "' by YAML symbol " << Sym.Name << ".\n";
310         exit(1);
311       }
312       Symbol.st_shndx = Index;
313     } // else Symbol.st_shndex == SHN_UNDEF (== 0), since it was zero'd earlier.
314     Symbol.st_value = Sym.Value;
315     Symbol.st_other = Sym.Other;
316     Symbol.st_size = Sym.Size;
317     Syms.push_back(Symbol);
318   }
319 }
320 
321 template <class ELFT>
322 void
writeSectionContent(Elf_Shdr & SHeader,const ELFYAML::RawContentSection & Section,ContiguousBlobAccumulator & CBA)323 ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
324                                     const ELFYAML::RawContentSection &Section,
325                                     ContiguousBlobAccumulator &CBA) {
326   assert(Section.Size >= Section.Content.binary_size() &&
327          "Section size and section content are inconsistent");
328   raw_ostream &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset);
329   Section.Content.writeAsBinary(OS);
330   for (auto i = Section.Content.binary_size(); i < Section.Size; ++i)
331     OS.write(0);
332   SHeader.sh_entsize = 0;
333   SHeader.sh_size = Section.Size;
334 }
335 
isMips64EL(const ELFYAML::Object & Doc)336 static bool isMips64EL(const ELFYAML::Object &Doc) {
337   return Doc.Header.Machine == ELFYAML::ELF_EM(llvm::ELF::EM_MIPS) &&
338          Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64) &&
339          Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
340 }
341 
342 template <class ELFT>
343 bool
writeSectionContent(Elf_Shdr & SHeader,const ELFYAML::RelocationSection & Section,ContiguousBlobAccumulator & CBA)344 ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
345                                     const ELFYAML::RelocationSection &Section,
346                                     ContiguousBlobAccumulator &CBA) {
347   if (Section.Type != llvm::ELF::SHT_REL &&
348       Section.Type != llvm::ELF::SHT_RELA) {
349     errs() << "error: Invalid relocation section type.\n";
350     return false;
351   }
352 
353   bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
354   SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
355   SHeader.sh_size = SHeader.sh_entsize * Section.Relocations.size();
356 
357   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset);
358 
359   for (const auto &Rel : Section.Relocations) {
360     unsigned SymIdx;
361     if (SymN2I.lookup(Rel.Symbol, SymIdx)) {
362       errs() << "error: Unknown symbol referenced: '" << Rel.Symbol
363              << "' at YAML relocation.\n";
364       return false;
365     }
366 
367     if (IsRela) {
368       Elf_Rela REntry;
369       zero(REntry);
370       REntry.r_offset = Rel.Offset;
371       REntry.r_addend = Rel.Addend;
372       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
373       OS.write((const char *)&REntry, sizeof(REntry));
374     } else {
375       Elf_Rel REntry;
376       zero(REntry);
377       REntry.r_offset = Rel.Offset;
378       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
379       OS.write((const char *)&REntry, sizeof(REntry));
380     }
381   }
382   return true;
383 }
384 
385 template <class ELFT>
writeSectionContent(Elf_Shdr & SHeader,const ELFYAML::Group & Section,ContiguousBlobAccumulator & CBA)386 bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
387                                          const ELFYAML::Group &Section,
388                                          ContiguousBlobAccumulator &CBA) {
389   typedef typename object::ELFFile<ELFT>::Elf_Word Elf_Word;
390   if (Section.Type != llvm::ELF::SHT_GROUP) {
391     errs() << "error: Invalid section type.\n";
392     return false;
393   }
394 
395   SHeader.sh_entsize = sizeof(Elf_Word);
396   SHeader.sh_size = SHeader.sh_entsize * Section.Members.size();
397 
398   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset);
399 
400   for (auto member : Section.Members) {
401     Elf_Word SIdx;
402     unsigned int sectionIndex = 0;
403     if (member.sectionNameOrType == "GRP_COMDAT")
404       sectionIndex = llvm::ELF::GRP_COMDAT;
405     else if (SN2I.lookup(member.sectionNameOrType, sectionIndex)) {
406       errs() << "error: Unknown section referenced: '"
407              << member.sectionNameOrType << "' at YAML section' "
408              << Section.Name << "\n";
409       return false;
410     }
411     SIdx = sectionIndex;
412     OS.write((const char *)&SIdx, sizeof(SIdx));
413   }
414   return true;
415 }
416 
buildSectionIndex()417 template <class ELFT> bool ELFState<ELFT>::buildSectionIndex() {
418   SN2I.addName(".symtab", getDotSymTabSecNo());
419   SN2I.addName(".strtab", getDotStrTabSecNo());
420   SN2I.addName(".shstrtab", getDotShStrTabSecNo());
421 
422   for (unsigned i = 0, e = Doc.Sections.size(); i != e; ++i) {
423     StringRef Name = Doc.Sections[i]->Name;
424     if (Name.empty())
425       continue;
426     // "+ 1" to take into account the SHT_NULL entry.
427     if (SN2I.addName(Name, i + 1)) {
428       errs() << "error: Repeated section name: '" << Name
429              << "' at YAML section number " << i << ".\n";
430       return false;
431     }
432   }
433   return true;
434 }
435 
436 template <class ELFT>
437 bool
buildSymbolIndex(std::size_t & StartIndex,const std::vector<ELFYAML::Symbol> & Symbols)438 ELFState<ELFT>::buildSymbolIndex(std::size_t &StartIndex,
439                                  const std::vector<ELFYAML::Symbol> &Symbols) {
440   for (const auto &Sym : Symbols) {
441     ++StartIndex;
442     if (Sym.Name.empty())
443       continue;
444     if (SymN2I.addName(Sym.Name, StartIndex)) {
445       errs() << "error: Repeated symbol name: '" << Sym.Name << "'.\n";
446       return false;
447     }
448   }
449   return true;
450 }
451 
452 template <class ELFT>
writeELF(raw_ostream & OS,const ELFYAML::Object & Doc)453 int ELFState<ELFT>::writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
454   ELFState<ELFT> State(Doc);
455   if (!State.buildSectionIndex())
456     return 1;
457 
458   std::size_t StartSymIndex = 0;
459   if (!State.buildSymbolIndex(StartSymIndex, Doc.Symbols.Local) ||
460       !State.buildSymbolIndex(StartSymIndex, Doc.Symbols.Global) ||
461       !State.buildSymbolIndex(StartSymIndex, Doc.Symbols.Weak))
462     return 1;
463 
464   Elf_Ehdr Header;
465   State.initELFHeader(Header);
466 
467   // TODO: Flesh out section header support.
468   // TODO: Program headers.
469 
470   // XXX: This offset is tightly coupled with the order that we write
471   // things to `OS`.
472   const size_t SectionContentBeginOffset =
473       Header.e_ehsize + Header.e_shentsize * Header.e_shnum;
474   ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
475 
476   // Doc might not contain .symtab, .strtab and .shstrtab sections,
477   // but we will emit them, so make sure to add them to ShStrTabSHeader.
478   State.DotShStrtab.add(".symtab");
479   State.DotShStrtab.add(".strtab");
480   State.DotShStrtab.add(".shstrtab");
481 
482   std::vector<Elf_Shdr> SHeaders;
483   if(!State.initSectionHeaders(SHeaders, CBA))
484     return 1;
485 
486   // .symtab section.
487   Elf_Shdr SymtabSHeader;
488   State.initSymtabSectionHeader(SymtabSHeader, CBA);
489   SHeaders.push_back(SymtabSHeader);
490 
491   // .strtab string table header.
492   Elf_Shdr DotStrTabSHeader;
493   State.initStrtabSectionHeader(DotStrTabSHeader, ".strtab", State.DotStrtab,
494                                 CBA);
495   SHeaders.push_back(DotStrTabSHeader);
496 
497   // .shstrtab string table header.
498   Elf_Shdr ShStrTabSHeader;
499   State.initStrtabSectionHeader(ShStrTabSHeader, ".shstrtab", State.DotShStrtab,
500                                 CBA);
501   SHeaders.push_back(ShStrTabSHeader);
502 
503   OS.write((const char *)&Header, sizeof(Header));
504   writeArrayData(OS, makeArrayRef(SHeaders));
505   CBA.writeBlobToStream(OS);
506   return 0;
507 }
508 
is64Bit(const ELFYAML::Object & Doc)509 static bool is64Bit(const ELFYAML::Object &Doc) {
510   return Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
511 }
512 
isLittleEndian(const ELFYAML::Object & Doc)513 static bool isLittleEndian(const ELFYAML::Object &Doc) {
514   return Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
515 }
516 
yaml2elf(yaml::Input & YIn,raw_ostream & Out)517 int yaml2elf(yaml::Input &YIn, raw_ostream &Out) {
518   ELFYAML::Object Doc;
519   YIn >> Doc;
520   if (YIn.error()) {
521     errs() << "yaml2obj: Failed to parse YAML file!\n";
522     return 1;
523   }
524   using object::ELFType;
525   typedef ELFType<support::little, 8, true> LE64;
526   typedef ELFType<support::big, 8, true> BE64;
527   typedef ELFType<support::little, 4, false> LE32;
528   typedef ELFType<support::big, 4, false> BE32;
529   if (is64Bit(Doc)) {
530     if (isLittleEndian(Doc))
531       return ELFState<LE64>::writeELF(Out, Doc);
532     else
533       return ELFState<BE64>::writeELF(Out, Doc);
534   } else {
535     if (isLittleEndian(Doc))
536       return ELFState<LE32>::writeELF(Out, Doc);
537     else
538       return ELFState<BE32>::writeELF(Out, Doc);
539   }
540 }
541