1 //===- ELF.h - ELF object file implementation -------------------*- C++ -*-===//
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 // This file declares the ELFFile template class.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #ifndef LLVM_OBJECT_ELF_H
15 #define LLVM_OBJECT_ELF_H
16
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/Object/ELFTypes.h"
19 #include "llvm/Support/MemoryBuffer.h"
20
21 namespace llvm {
22 namespace object {
23
24 StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type);
25
26 // Subclasses of ELFFile may need this for template instantiation
27 inline std::pair<unsigned char, unsigned char>
getElfArchType(StringRef Object)28 getElfArchType(StringRef Object) {
29 if (Object.size() < ELF::EI_NIDENT)
30 return std::make_pair((uint8_t)ELF::ELFCLASSNONE,
31 (uint8_t)ELF::ELFDATANONE);
32 return std::make_pair((uint8_t)Object[ELF::EI_CLASS],
33 (uint8_t)Object[ELF::EI_DATA]);
34 }
35
36 template <class ELFT>
37 class ELFFile {
38 public:
39 LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
40 typedef typename std::conditional<ELFT::Is64Bits,
41 uint64_t, uint32_t>::type uintX_t;
42
43 typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
44 typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
45 typedef Elf_Sym_Impl<ELFT> Elf_Sym;
46 typedef Elf_Dyn_Impl<ELFT> Elf_Dyn;
47 typedef Elf_Phdr_Impl<ELFT> Elf_Phdr;
48 typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
49 typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
50 typedef Elf_Verdef_Impl<ELFT> Elf_Verdef;
51 typedef Elf_Verdaux_Impl<ELFT> Elf_Verdaux;
52 typedef Elf_Verneed_Impl<ELFT> Elf_Verneed;
53 typedef Elf_Vernaux_Impl<ELFT> Elf_Vernaux;
54 typedef Elf_Versym_Impl<ELFT> Elf_Versym;
55 typedef Elf_Hash_Impl<ELFT> Elf_Hash;
56 typedef Elf_GnuHash_Impl<ELFT> Elf_GnuHash;
57 typedef iterator_range<const Elf_Dyn *> Elf_Dyn_Range;
58 typedef iterator_range<const Elf_Shdr *> Elf_Shdr_Range;
59 typedef iterator_range<const Elf_Sym *> Elf_Sym_Range;
60
base()61 const uint8_t *base() const {
62 return reinterpret_cast<const uint8_t *>(Buf.data());
63 }
64
65 private:
66
67 StringRef Buf;
68
69 const Elf_Ehdr *Header;
70 const Elf_Shdr *SectionHeaderTable = nullptr;
71 StringRef DotShstrtab; // Section header string table.
72
73 public:
74 template<typename T>
75 const T *getEntry(uint32_t Section, uint32_t Entry) const;
76 template <typename T>
77 const T *getEntry(const Elf_Shdr *Section, uint32_t Entry) const;
78
79 ErrorOr<StringRef> getStringTable(const Elf_Shdr *Section) const;
80 ErrorOr<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const;
81
82 ErrorOr<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section) const;
83
84 void VerifyStrTab(const Elf_Shdr *sh) const;
85
86 StringRef getRelocationTypeName(uint32_t Type) const;
87 void getRelocationTypeName(uint32_t Type,
88 SmallVectorImpl<char> &Result) const;
89
90 /// \brief Get the symbol for a given relocation.
91 const Elf_Sym *getRelocationSymbol(const Elf_Rel *Rel,
92 const Elf_Shdr *SymTab) const;
93
94 ELFFile(StringRef Object, std::error_code &EC);
95
isMipsELF64()96 bool isMipsELF64() const {
97 return Header->e_machine == ELF::EM_MIPS &&
98 Header->getFileClass() == ELF::ELFCLASS64;
99 }
100
isMips64EL()101 bool isMips64EL() const {
102 return Header->e_machine == ELF::EM_MIPS &&
103 Header->getFileClass() == ELF::ELFCLASS64 &&
104 Header->getDataEncoding() == ELF::ELFDATA2LSB;
105 }
106
107 ErrorOr<const Elf_Dyn *> dynamic_table_begin(const Elf_Phdr *Phdr) const;
108 ErrorOr<const Elf_Dyn *> dynamic_table_end(const Elf_Phdr *Phdr) const;
dynamic_table(const Elf_Phdr * Phdr)109 ErrorOr<Elf_Dyn_Range> dynamic_table(const Elf_Phdr *Phdr) const {
110 ErrorOr<const Elf_Dyn *> Begin = dynamic_table_begin(Phdr);
111 if (std::error_code EC = Begin.getError())
112 return EC;
113 ErrorOr<const Elf_Dyn *> End = dynamic_table_end(Phdr);
114 if (std::error_code EC = End.getError())
115 return EC;
116 return make_range(*Begin, *End);
117 }
118
119 const Elf_Shdr *section_begin() const;
120 const Elf_Shdr *section_end() const;
sections()121 Elf_Shdr_Range sections() const {
122 return make_range(section_begin(), section_end());
123 }
124
symbol_begin(const Elf_Shdr * Sec)125 const Elf_Sym *symbol_begin(const Elf_Shdr *Sec) const {
126 if (!Sec)
127 return nullptr;
128 if (Sec->sh_entsize != sizeof(Elf_Sym))
129 report_fatal_error("Invalid symbol size");
130 return reinterpret_cast<const Elf_Sym *>(base() + Sec->sh_offset);
131 }
symbol_end(const Elf_Shdr * Sec)132 const Elf_Sym *symbol_end(const Elf_Shdr *Sec) const {
133 if (!Sec)
134 return nullptr;
135 uint64_t Size = Sec->sh_size;
136 if (Size % sizeof(Elf_Sym))
137 report_fatal_error("Invalid symbol table size");
138 return symbol_begin(Sec) + Size / sizeof(Elf_Sym);
139 }
symbols(const Elf_Shdr * Sec)140 Elf_Sym_Range symbols(const Elf_Shdr *Sec) const {
141 return make_range(symbol_begin(Sec), symbol_end(Sec));
142 }
143
144 typedef iterator_range<const Elf_Rela *> Elf_Rela_Range;
145
rela_begin(const Elf_Shdr * sec)146 const Elf_Rela *rela_begin(const Elf_Shdr *sec) const {
147 if (sec->sh_entsize != sizeof(Elf_Rela))
148 report_fatal_error("Invalid relocation entry size");
149 return reinterpret_cast<const Elf_Rela *>(base() + sec->sh_offset);
150 }
151
rela_end(const Elf_Shdr * sec)152 const Elf_Rela *rela_end(const Elf_Shdr *sec) const {
153 uint64_t Size = sec->sh_size;
154 if (Size % sizeof(Elf_Rela))
155 report_fatal_error("Invalid relocation table size");
156 return rela_begin(sec) + Size / sizeof(Elf_Rela);
157 }
158
relas(const Elf_Shdr * Sec)159 Elf_Rela_Range relas(const Elf_Shdr *Sec) const {
160 return make_range(rela_begin(Sec), rela_end(Sec));
161 }
162
rel_begin(const Elf_Shdr * sec)163 const Elf_Rel *rel_begin(const Elf_Shdr *sec) const {
164 if (sec->sh_entsize != sizeof(Elf_Rel))
165 report_fatal_error("Invalid relocation entry size");
166 return reinterpret_cast<const Elf_Rel *>(base() + sec->sh_offset);
167 }
168
rel_end(const Elf_Shdr * sec)169 const Elf_Rel *rel_end(const Elf_Shdr *sec) const {
170 uint64_t Size = sec->sh_size;
171 if (Size % sizeof(Elf_Rel))
172 report_fatal_error("Invalid relocation table size");
173 return rel_begin(sec) + Size / sizeof(Elf_Rel);
174 }
175
176 typedef iterator_range<const Elf_Rel *> Elf_Rel_Range;
rels(const Elf_Shdr * Sec)177 Elf_Rel_Range rels(const Elf_Shdr *Sec) const {
178 return make_range(rel_begin(Sec), rel_end(Sec));
179 }
180
181 /// \brief Iterate over program header table.
program_header_begin()182 const Elf_Phdr *program_header_begin() const {
183 if (Header->e_phnum && Header->e_phentsize != sizeof(Elf_Phdr))
184 report_fatal_error("Invalid program header size");
185 return reinterpret_cast<const Elf_Phdr *>(base() + Header->e_phoff);
186 }
187
program_header_end()188 const Elf_Phdr *program_header_end() const {
189 return program_header_begin() + Header->e_phnum;
190 }
191
192 typedef iterator_range<const Elf_Phdr *> Elf_Phdr_Range;
193
program_headers()194 const Elf_Phdr_Range program_headers() const {
195 return make_range(program_header_begin(), program_header_end());
196 }
197
198 uint64_t getNumSections() const;
199 uintX_t getStringTableIndex() const;
200 uint32_t getExtendedSymbolTableIndex(const Elf_Sym *Sym,
201 const Elf_Shdr *SymTab,
202 ArrayRef<Elf_Word> ShndxTable) const;
getHeader()203 const Elf_Ehdr *getHeader() const { return Header; }
204 ErrorOr<const Elf_Shdr *> getSection(const Elf_Sym *Sym,
205 const Elf_Shdr *SymTab,
206 ArrayRef<Elf_Word> ShndxTable) const;
207 ErrorOr<const Elf_Shdr *> getSection(uint32_t Index) const;
208
getSymbol(const Elf_Shdr * Sec,uint32_t Index)209 const Elf_Sym *getSymbol(const Elf_Shdr *Sec, uint32_t Index) const {
210 return &*(symbol_begin(Sec) + Index);
211 }
212
213 ErrorOr<StringRef> getSectionName(const Elf_Shdr *Section) const;
214 template <typename T>
215 ErrorOr<ArrayRef<T>> getSectionContentsAsArray(const Elf_Shdr *Sec) const;
216 ErrorOr<ArrayRef<uint8_t> > getSectionContents(const Elf_Shdr *Sec) const;
217 };
218
219 typedef ELFFile<ELFType<support::little, false>> ELF32LEFile;
220 typedef ELFFile<ELFType<support::little, true>> ELF64LEFile;
221 typedef ELFFile<ELFType<support::big, false>> ELF32BEFile;
222 typedef ELFFile<ELFType<support::big, true>> ELF64BEFile;
223
224 template <class ELFT>
getExtendedSymbolTableIndex(const Elf_Sym * Sym,const Elf_Shdr * SymTab,ArrayRef<Elf_Word> ShndxTable)225 uint32_t ELFFile<ELFT>::getExtendedSymbolTableIndex(
226 const Elf_Sym *Sym, const Elf_Shdr *SymTab,
227 ArrayRef<Elf_Word> ShndxTable) const {
228 assert(Sym->st_shndx == ELF::SHN_XINDEX);
229 unsigned Index = Sym - symbol_begin(SymTab);
230
231 // The size of the table was checked in getSHNDXTable.
232 return ShndxTable[Index];
233 }
234
235 template <class ELFT>
236 ErrorOr<const typename ELFFile<ELFT>::Elf_Shdr *>
getSection(const Elf_Sym * Sym,const Elf_Shdr * SymTab,ArrayRef<Elf_Word> ShndxTable)237 ELFFile<ELFT>::getSection(const Elf_Sym *Sym, const Elf_Shdr *SymTab,
238 ArrayRef<Elf_Word> ShndxTable) const {
239 uint32_t Index = Sym->st_shndx;
240 if (Index == ELF::SHN_XINDEX)
241 return getSection(getExtendedSymbolTableIndex(Sym, SymTab, ShndxTable));
242
243 if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
244 return nullptr;
245 return getSection(Sym->st_shndx);
246 }
247
248 template <class ELFT>
249 template <typename T>
250 ErrorOr<ArrayRef<T>>
getSectionContentsAsArray(const Elf_Shdr * Sec)251 ELFFile<ELFT>::getSectionContentsAsArray(const Elf_Shdr *Sec) const {
252 uintX_t Offset = Sec->sh_offset;
253 uintX_t Size = Sec->sh_size;
254
255 if (Size % sizeof(T))
256 return object_error::parse_failed;
257 if (Offset + Size > Buf.size())
258 return object_error::parse_failed;
259
260 const T *Start = reinterpret_cast<const T *>(base() + Offset);
261 return makeArrayRef(Start, Size / sizeof(T));
262 }
263
264 template <class ELFT>
265 ErrorOr<ArrayRef<uint8_t>>
getSectionContents(const Elf_Shdr * Sec)266 ELFFile<ELFT>::getSectionContents(const Elf_Shdr *Sec) const {
267 return getSectionContentsAsArray<uint8_t>(Sec);
268 }
269
270 template <class ELFT>
getRelocationTypeName(uint32_t Type)271 StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
272 return getELFRelocationTypeName(Header->e_machine, Type);
273 }
274
275 template <class ELFT>
getRelocationTypeName(uint32_t Type,SmallVectorImpl<char> & Result)276 void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
277 SmallVectorImpl<char> &Result) const {
278 if (!isMipsELF64()) {
279 StringRef Name = getRelocationTypeName(Type);
280 Result.append(Name.begin(), Name.end());
281 } else {
282 // The Mips N64 ABI allows up to three operations to be specified per
283 // relocation record. Unfortunately there's no easy way to test for the
284 // presence of N64 ELFs as they have no special flag that identifies them
285 // as being N64. We can safely assume at the moment that all Mips
286 // ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
287 // information to disambiguate between old vs new ABIs.
288 uint8_t Type1 = (Type >> 0) & 0xFF;
289 uint8_t Type2 = (Type >> 8) & 0xFF;
290 uint8_t Type3 = (Type >> 16) & 0xFF;
291
292 // Concat all three relocation type names.
293 StringRef Name = getRelocationTypeName(Type1);
294 Result.append(Name.begin(), Name.end());
295
296 Name = getRelocationTypeName(Type2);
297 Result.append(1, '/');
298 Result.append(Name.begin(), Name.end());
299
300 Name = getRelocationTypeName(Type3);
301 Result.append(1, '/');
302 Result.append(Name.begin(), Name.end());
303 }
304 }
305
306 template <class ELFT>
307 const typename ELFFile<ELFT>::Elf_Sym *
getRelocationSymbol(const Elf_Rel * Rel,const Elf_Shdr * SymTab)308 ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel *Rel,
309 const Elf_Shdr *SymTab) const {
310 uint32_t Index = Rel->getSymbol(isMips64EL());
311 if (Index == 0)
312 return nullptr;
313 return getEntry<Elf_Sym>(SymTab, Index);
314 }
315
316 template <class ELFT>
getNumSections()317 uint64_t ELFFile<ELFT>::getNumSections() const {
318 assert(Header && "Header not initialized!");
319 if (Header->e_shnum == ELF::SHN_UNDEF && Header->e_shoff > 0) {
320 assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
321 return SectionHeaderTable->sh_size;
322 }
323 return Header->e_shnum;
324 }
325
326 template <class ELFT>
getStringTableIndex()327 typename ELFFile<ELFT>::uintX_t ELFFile<ELFT>::getStringTableIndex() const {
328 if (Header->e_shnum == ELF::SHN_UNDEF) {
329 if (Header->e_shstrndx == ELF::SHN_HIRESERVE)
330 return SectionHeaderTable->sh_link;
331 if (Header->e_shstrndx >= getNumSections())
332 return 0;
333 }
334 return Header->e_shstrndx;
335 }
336
337 template <class ELFT>
ELFFile(StringRef Object,std::error_code & EC)338 ELFFile<ELFT>::ELFFile(StringRef Object, std::error_code &EC)
339 : Buf(Object) {
340 const uint64_t FileSize = Buf.size();
341
342 if (sizeof(Elf_Ehdr) > FileSize) {
343 // File too short!
344 EC = object_error::parse_failed;
345 return;
346 }
347
348 Header = reinterpret_cast<const Elf_Ehdr *>(base());
349
350 if (Header->e_shoff == 0)
351 return;
352
353 const uint64_t SectionTableOffset = Header->e_shoff;
354
355 if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize) {
356 // Section header table goes past end of file!
357 EC = object_error::parse_failed;
358 return;
359 }
360
361 // The getNumSections() call below depends on SectionHeaderTable being set.
362 SectionHeaderTable =
363 reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
364 const uint64_t SectionTableSize = getNumSections() * Header->e_shentsize;
365
366 if (SectionTableOffset + SectionTableSize > FileSize) {
367 // Section table goes past end of file!
368 EC = object_error::parse_failed;
369 return;
370 }
371
372 // Get string table sections.
373 uintX_t StringTableIndex = getStringTableIndex();
374 if (StringTableIndex) {
375 ErrorOr<const Elf_Shdr *> StrTabSecOrErr = getSection(StringTableIndex);
376 if ((EC = StrTabSecOrErr.getError()))
377 return;
378
379 ErrorOr<StringRef> StringTableOrErr = getStringTable(*StrTabSecOrErr);
380 if ((EC = StringTableOrErr.getError()))
381 return;
382 DotShstrtab = *StringTableOrErr;
383 }
384
385 EC = std::error_code();
386 }
387
388 template <class ELFT>
compareAddr(uint64_t VAddr,const Elf_Phdr_Impl<ELFT> * Phdr)389 static bool compareAddr(uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) {
390 return VAddr < Phdr->p_vaddr;
391 }
392
393 template <class ELFT>
section_begin()394 const typename ELFFile<ELFT>::Elf_Shdr *ELFFile<ELFT>::section_begin() const {
395 if (Header->e_shentsize != sizeof(Elf_Shdr))
396 report_fatal_error(
397 "Invalid section header entry size (e_shentsize) in ELF header");
398 return reinterpret_cast<const Elf_Shdr *>(base() + Header->e_shoff);
399 }
400
401 template <class ELFT>
section_end()402 const typename ELFFile<ELFT>::Elf_Shdr *ELFFile<ELFT>::section_end() const {
403 return section_begin() + getNumSections();
404 }
405
406 template <class ELFT>
407 ErrorOr<const typename ELFFile<ELFT>::Elf_Dyn *>
dynamic_table_begin(const Elf_Phdr * Phdr)408 ELFFile<ELFT>::dynamic_table_begin(const Elf_Phdr *Phdr) const {
409 if (!Phdr)
410 return nullptr;
411 assert(Phdr->p_type == ELF::PT_DYNAMIC && "Got the wrong program header");
412 uintX_t Offset = Phdr->p_offset;
413 if (Offset > Buf.size())
414 return object_error::parse_failed;
415 return reinterpret_cast<const Elf_Dyn *>(base() + Offset);
416 }
417
418 template <class ELFT>
419 ErrorOr<const typename ELFFile<ELFT>::Elf_Dyn *>
dynamic_table_end(const Elf_Phdr * Phdr)420 ELFFile<ELFT>::dynamic_table_end(const Elf_Phdr *Phdr) const {
421 if (!Phdr)
422 return nullptr;
423 assert(Phdr->p_type == ELF::PT_DYNAMIC && "Got the wrong program header");
424 uintX_t Size = Phdr->p_filesz;
425 if (Size % sizeof(Elf_Dyn))
426 return object_error::elf_invalid_dynamic_table_size;
427 // FIKME: Check for overflow?
428 uintX_t End = Phdr->p_offset + Size;
429 if (End > Buf.size())
430 return object_error::parse_failed;
431 return reinterpret_cast<const Elf_Dyn *>(base() + End);
432 }
433
434 template <class ELFT>
435 template <typename T>
getEntry(uint32_t Section,uint32_t Entry)436 const T *ELFFile<ELFT>::getEntry(uint32_t Section, uint32_t Entry) const {
437 ErrorOr<const Elf_Shdr *> Sec = getSection(Section);
438 if (std::error_code EC = Sec.getError())
439 report_fatal_error(EC.message());
440 return getEntry<T>(*Sec, Entry);
441 }
442
443 template <class ELFT>
444 template <typename T>
getEntry(const Elf_Shdr * Section,uint32_t Entry)445 const T *ELFFile<ELFT>::getEntry(const Elf_Shdr *Section,
446 uint32_t Entry) const {
447 return reinterpret_cast<const T *>(base() + Section->sh_offset +
448 (Entry * Section->sh_entsize));
449 }
450
451 template <class ELFT>
452 ErrorOr<const typename ELFFile<ELFT>::Elf_Shdr *>
getSection(uint32_t Index)453 ELFFile<ELFT>::getSection(uint32_t Index) const {
454 assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
455 if (Index >= getNumSections())
456 return object_error::invalid_section_index;
457
458 return reinterpret_cast<const Elf_Shdr *>(
459 reinterpret_cast<const char *>(SectionHeaderTable) +
460 (Index * Header->e_shentsize));
461 }
462
463 template <class ELFT>
464 ErrorOr<StringRef>
getStringTable(const Elf_Shdr * Section)465 ELFFile<ELFT>::getStringTable(const Elf_Shdr *Section) const {
466 if (Section->sh_type != ELF::SHT_STRTAB)
467 return object_error::parse_failed;
468 uint64_t Offset = Section->sh_offset;
469 uint64_t Size = Section->sh_size;
470 if (Offset + Size > Buf.size())
471 return object_error::parse_failed;
472 StringRef Data((const char *)base() + Section->sh_offset, Size);
473 if (Data[Size - 1] != '\0')
474 return object_error::string_table_non_null_end;
475 return Data;
476 }
477
478 template <class ELFT>
479 ErrorOr<ArrayRef<typename ELFFile<ELFT>::Elf_Word>>
getSHNDXTable(const Elf_Shdr & Section)480 ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section) const {
481 assert(Section.sh_type == ELF::SHT_SYMTAB_SHNDX);
482 const Elf_Word *ShndxTableBegin =
483 reinterpret_cast<const Elf_Word *>(base() + Section.sh_offset);
484 uintX_t Size = Section.sh_size;
485 if (Size % sizeof(uint32_t))
486 return object_error::parse_failed;
487 uintX_t NumSymbols = Size / sizeof(uint32_t);
488 const Elf_Word *ShndxTableEnd = ShndxTableBegin + NumSymbols;
489 if (reinterpret_cast<const char *>(ShndxTableEnd) > Buf.end())
490 return object_error::parse_failed;
491 ErrorOr<const Elf_Shdr *> SymTableOrErr = getSection(Section.sh_link);
492 if (std::error_code EC = SymTableOrErr.getError())
493 return EC;
494 const Elf_Shdr &SymTable = **SymTableOrErr;
495 if (SymTable.sh_type != ELF::SHT_SYMTAB &&
496 SymTable.sh_type != ELF::SHT_DYNSYM)
497 return object_error::parse_failed;
498 if (NumSymbols != (SymTable.sh_size / sizeof(Elf_Sym)))
499 return object_error::parse_failed;
500 return makeArrayRef(ShndxTableBegin, ShndxTableEnd);
501 }
502
503 template <class ELFT>
504 ErrorOr<StringRef>
getStringTableForSymtab(const Elf_Shdr & Sec)505 ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
506 if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM)
507 return object_error::parse_failed;
508 ErrorOr<const Elf_Shdr *> SectionOrErr = getSection(Sec.sh_link);
509 if (std::error_code EC = SectionOrErr.getError())
510 return EC;
511 return getStringTable(*SectionOrErr);
512 }
513
514 template <class ELFT>
515 ErrorOr<StringRef>
getSectionName(const Elf_Shdr * Section)516 ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section) const {
517 uint32_t Offset = Section->sh_name;
518 if (Offset == 0)
519 return StringRef();
520 if (Offset >= DotShstrtab.size())
521 return object_error::parse_failed;
522 return StringRef(DotShstrtab.data() + Offset);
523 }
524
525 /// This function returns the hash value for a symbol in the .dynsym section
526 /// Name of the API remains consistent as specified in the libelf
527 /// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash
elf_hash(StringRef & symbolName)528 static inline unsigned elf_hash(StringRef &symbolName) {
529 unsigned h = 0, g;
530 for (unsigned i = 0, j = symbolName.size(); i < j; i++) {
531 h = (h << 4) + symbolName[i];
532 g = h & 0xf0000000L;
533 if (g != 0)
534 h ^= g >> 24;
535 h &= ~g;
536 }
537 return h;
538 }
539 } // end namespace object
540 } // end namespace llvm
541
542 #endif
543