1//===- ELF.h - ELF object file implementation -------------------*- C++ -*-===//
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// This file declares the ELFFile template class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_OBJECT_ELF_H
14#define LLVM_OBJECT_ELF_H
15
16#include "llvm/ADT/ArrayRef.h"
17#include "llvm/ADT/SmallVector.h"
18#include "llvm/ADT/StringRef.h"
19#include "llvm/BinaryFormat/ELF.h"
20#include "llvm/Object/ELFTypes.h"
21#include "llvm/Object/Error.h"
22#include "llvm/Support/Endian.h"
23#include "llvm/Support/Error.h"
24#include <cassert>
25#include <cstddef>
26#include <cstdint>
27#include <limits>
28#include <utility>
29
30namespace llvm {
31namespace object {
32
33struct VerdAux {
34 unsigned Offset;
35 std::string Name;
36};
37
38struct VerDef {
39 unsigned Offset;
40 unsigned Version;
41 unsigned Flags;
42 unsigned Ndx;
43 unsigned Cnt;
44 unsigned Hash;
45 std::string Name;
46 std::vector<VerdAux> AuxV;
47};
48
49struct VernAux {
50 unsigned Hash;
51 unsigned Flags;
52 unsigned Other;
53 unsigned Offset;
54 std::string Name;
55};
56
57struct VerNeed {
58 unsigned Version;
59 unsigned Cnt;
60 unsigned Offset;
61 std::string File;
62 std::vector<VernAux> AuxV;
63};
64
65struct VersionEntry {
66 std::string Name;
67 bool IsVerDef;
68};
69
70StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type);
71uint32_t getELFRelativeRelocationType(uint32_t Machine);
72StringRef getELFSectionTypeName(uint32_t Machine, uint32_t Type);
73
74// Subclasses of ELFFile may need this for template instantiation
75inline std::pair<unsigned char, unsigned char>
76getElfArchType(StringRef Object) {
77 if (Object.size() < ELF::EI_NIDENT)
78 return std::make_pair((uint8_t)ELF::ELFCLASSNONE,
79 (uint8_t)ELF::ELFDATANONE);
80 return std::make_pair((uint8_t)Object[ELF::EI_CLASS],
81 (uint8_t)Object[ELF::EI_DATA]);
82}
83
84static inline Error createError(const Twine &Err) {
85 return make_error<StringError>(Err, object_error::parse_failed);
86}
87
88enum PPCInstrMasks : uint64_t {
89 PADDI_R12_NO_DISP = 0x0610000039800000,
90 ADDIS_R12_TO_R2_NO_DISP = 0x3D820000,
91 ADDI_R12_TO_R2_NO_DISP = 0x39820000,
92 ADDI_R12_TO_R12_NO_DISP = 0x398C0000,
93 PLD_R12_NO_DISP = 0x04100000E5800000,
94 MTCTR_R12 = 0x7D8903A6,
95 BCTR = 0x4E800420,
96};
97
98template <class ELFT> class ELFFile;
99
100template <class T> struct DataRegion {
101 // This constructor is used when we know the start and the size of a data
102 // region. We assume that Arr does not go past the end of the file.
103 DataRegion(ArrayRef<T> Arr) : First(Arr.data()), Size(Arr.size()) {}
104
105 // Sometimes we only know the start of a data region. We still don't want to
106 // read past the end of the file, so we provide the end of a buffer.
107 DataRegion(const T *Data, const uint8_t *BufferEnd)
108 : First(Data), BufEnd(BufferEnd) {}
109
110 Expected<T> operator[](uint64_t N) {
111 assert(Size || BufEnd);
112 if (Size) {
113 if (N >= *Size)
114 return createError(
115 "the index is greater than or equal to the number of entries (" +
116 Twine(*Size) + ")");
117 } else {
118 const uint8_t *EntryStart = (const uint8_t *)First + N * sizeof(T);
119 if (EntryStart + sizeof(T) > BufEnd)
120 return createError("can't read past the end of the file");
121 }
122 return *(First + N);
123 }
124
125 const T *First;
126 Optional<uint64_t> Size = None;
127 const uint8_t *BufEnd = nullptr;
128};
129
130template <class ELFT>
131std::string getSecIndexForError(const ELFFile<ELFT> &Obj,
132 const typename ELFT::Shdr &Sec) {
133 auto TableOrErr = Obj.sections();
134 if (TableOrErr)
135 return "[index " + std::to_string(&Sec - &TableOrErr->front()) + "]";
136 // To make this helper be more convenient for error reporting purposes we
137 // drop the error. But really it should never be triggered. Before this point,
138 // our code should have called 'sections()' and reported a proper error on
139 // failure.
140 llvm::consumeError(TableOrErr.takeError());
141 return "[unknown index]";
142}
143
144template <class ELFT>
145static std::string describe(const ELFFile<ELFT> &Obj,
146 const typename ELFT::Shdr &Sec) {
147 unsigned SecNdx = &Sec - &cantFail(Obj.sections()).front();
148 return (object::getELFSectionTypeName(Obj.getHeader().e_machine,
149 Sec.sh_type) +
150 " section with index " + Twine(SecNdx))
151 .str();
152}
153
154template <class ELFT>
155std::string getPhdrIndexForError(const ELFFile<ELFT> &Obj,
156 const typename ELFT::Phdr &Phdr) {
157 auto Headers = Obj.program_headers();
158 if (Headers)
159 return ("[index " + Twine(&Phdr - &Headers->front()) + "]").str();
160 // See comment in the getSecIndexForError() above.
161 llvm::consumeError(Headers.takeError());
162 return "[unknown index]";
163}
164
165static inline Error defaultWarningHandler(const Twine &Msg) {
166 return createError(Msg);
167}
168
169template <class ELFT>
170class ELFFile {
171public:
172 LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
173
174 // This is a callback that can be passed to a number of functions.
175 // It can be used to ignore non-critical errors (warnings), which is
176 // useful for dumpers, like llvm-readobj.
177 // It accepts a warning message string and returns a success
178 // when the warning should be ignored or an error otherwise.
179 using WarningHandler = llvm::function_ref<Error(const Twine &Msg)>;
180
181 const uint8_t *base() const { return Buf.bytes_begin(); }
182 const uint8_t *end() const { return base() + getBufSize(); }
183
184 size_t getBufSize() const { return Buf.size(); }
185
186private:
187 StringRef Buf;
188
189 ELFFile(StringRef Object);
190
191public:
192 const Elf_Ehdr &getHeader() const {
193 return *reinterpret_cast<const Elf_Ehdr *>(base());
194 }
195
196 template <typename T>
197 Expected<const T *> getEntry(uint32_t Section, uint32_t Entry) const;
198 template <typename T>
199 Expected<const T *> getEntry(const Elf_Shdr &Section, uint32_t Entry) const;
200
201 Expected<std::vector<VerDef>>
202 getVersionDefinitions(const Elf_Shdr &Sec) const;
203 Expected<std::vector<VerNeed>> getVersionDependencies(
204 const Elf_Shdr &Sec,
205 WarningHandler WarnHandler = &defaultWarningHandler) const;
206 Expected<StringRef>
207 getSymbolVersionByIndex(uint32_t SymbolVersionIndex, bool &IsDefault,
208 SmallVector<Optional<VersionEntry>, 0> &VersionMap,
209 Optional<bool> IsSymHidden) const;
210
211 Expected<StringRef>
212 getStringTable(const Elf_Shdr &Section,
213 WarningHandler WarnHandler = &defaultWarningHandler) const;
214 Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const;
215 Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section,
216 Elf_Shdr_Range Sections) const;
217 Expected<StringRef> getLinkAsStrtab(const typename ELFT::Shdr &Sec) const;
218
219 Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section) const;
220 Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section,
221 Elf_Shdr_Range Sections) const;
222
223 Expected<uint64_t> getDynSymtabSize() const;
224
225 StringRef getRelocationTypeName(uint32_t Type) const;
226 void getRelocationTypeName(uint32_t Type,
227 SmallVectorImpl<char> &Result) const;
228 uint32_t getRelativeRelocationType() const;
229
230 std::string getDynamicTagAsString(unsigned Arch, uint64_t Type) const;
231 std::string getDynamicTagAsString(uint64_t Type) const;
232
233 /// Get the symbol for a given relocation.
234 Expected<const Elf_Sym *> getRelocationSymbol(const Elf_Rel &Rel,
235 const Elf_Shdr *SymTab) const;
236
237 Expected<SmallVector<Optional<VersionEntry>, 0>>
238 loadVersionMap(const Elf_Shdr *VerNeedSec, const Elf_Shdr *VerDefSec) const;
239
240 static Expected<ELFFile> create(StringRef Object);
241
242 bool isLE() const {
243 return getHeader().getDataEncoding() == ELF::ELFDATA2LSB;
244 }
245
246 bool isMipsELF64() const {
247 return getHeader().e_machine == ELF::EM_MIPS &&
248 getHeader().getFileClass() == ELF::ELFCLASS64;
249 }
250
251 bool isMips64EL() const { return isMipsELF64() && isLE(); }
252
253 Expected<Elf_Shdr_Range> sections() const;
254
255 Expected<Elf_Dyn_Range> dynamicEntries() const;
256
257 Expected<const uint8_t *>
258 toMappedAddr(uint64_t VAddr,
259 WarningHandler WarnHandler = &defaultWarningHandler) const;
260
261 Expected<Elf_Sym_Range> symbols(const Elf_Shdr *Sec) const {
262 if (!Sec)
263 return makeArrayRef<Elf_Sym>(nullptr, nullptr);
264 return getSectionContentsAsArray<Elf_Sym>(*Sec);
265 }
266
267 Expected<Elf_Rela_Range> relas(const Elf_Shdr &Sec) const {
268 return getSectionContentsAsArray<Elf_Rela>(Sec);
269 }
270
271 Expected<Elf_Rel_Range> rels(const Elf_Shdr &Sec) const {
272 return getSectionContentsAsArray<Elf_Rel>(Sec);
273 }
274
275 Expected<Elf_Relr_Range> relrs(const Elf_Shdr &Sec) const {
276 return getSectionContentsAsArray<Elf_Relr>(Sec);
277 }
278
279 std::vector<Elf_Rel> decode_relrs(Elf_Relr_Range relrs) const;
280
281 Expected<std::vector<Elf_Rela>> android_relas(const Elf_Shdr &Sec) const;
282
283 /// Iterate over program header table.
284 Expected<Elf_Phdr_Range> program_headers() const {
285 if (getHeader().e_phnum && getHeader().e_phentsize != sizeof(Elf_Phdr))
286 return createError("invalid e_phentsize: " +
287 Twine(getHeader().e_phentsize));
288
289 uint64_t HeadersSize =
290 (uint64_t)getHeader().e_phnum * getHeader().e_phentsize;
291 uint64_t PhOff = getHeader().e_phoff;
292 if (PhOff + HeadersSize < PhOff || PhOff + HeadersSize > getBufSize())
293 return createError("program headers are longer than binary of size " +
294 Twine(getBufSize()) + ": e_phoff = 0x" +
295 Twine::utohexstr(getHeader().e_phoff) +
296 ", e_phnum = " + Twine(getHeader().e_phnum) +
297 ", e_phentsize = " + Twine(getHeader().e_phentsize));
298
299 auto *Begin = reinterpret_cast<const Elf_Phdr *>(base() + PhOff);
300 return makeArrayRef(Begin, Begin + getHeader().e_phnum);
301 }
302
303 /// Get an iterator over notes in a program header.
304 ///
305 /// The program header must be of type \c PT_NOTE.
306 ///
307 /// \param Phdr the program header to iterate over.
308 /// \param Err [out] an error to support fallible iteration, which should
309 /// be checked after iteration ends.
310 Elf_Note_Iterator notes_begin(const Elf_Phdr &Phdr, Error &Err) const {
311 assert(Phdr.p_type == ELF::PT_NOTE && "Phdr is not of type PT_NOTE");
312 ErrorAsOutParameter ErrAsOutParam(&Err);
313 if (Phdr.p_offset + Phdr.p_filesz > getBufSize()) {
314 Err =
315 createError("invalid offset (0x" + Twine::utohexstr(Phdr.p_offset) +
316 ") or size (0x" + Twine::utohexstr(Phdr.p_filesz) + ")");
317 return Elf_Note_Iterator(Err);
318 }
319 return Elf_Note_Iterator(base() + Phdr.p_offset, Phdr.p_filesz, Err);
320 }
321
322 /// Get an iterator over notes in a section.
323 ///
324 /// The section must be of type \c SHT_NOTE.
325 ///
326 /// \param Shdr the section to iterate over.
327 /// \param Err [out] an error to support fallible iteration, which should
328 /// be checked after iteration ends.
329 Elf_Note_Iterator notes_begin(const Elf_Shdr &Shdr, Error &Err) const {
330 assert(Shdr.sh_type == ELF::SHT_NOTE && "Shdr is not of type SHT_NOTE");
331 ErrorAsOutParameter ErrAsOutParam(&Err);
332 if (Shdr.sh_offset + Shdr.sh_size > getBufSize()) {
333 Err =
334 createError("invalid offset (0x" + Twine::utohexstr(Shdr.sh_offset) +
335 ") or size (0x" + Twine::utohexstr(Shdr.sh_size) + ")");
336 return Elf_Note_Iterator(Err);
337 }
338 return Elf_Note_Iterator(base() + Shdr.sh_offset, Shdr.sh_size, Err);
339 }
340
341 /// Get the end iterator for notes.
342 Elf_Note_Iterator notes_end() const {
343 return Elf_Note_Iterator();
344 }
345
346 /// Get an iterator range over notes of a program header.
347 ///
348 /// The program header must be of type \c PT_NOTE.
349 ///
350 /// \param Phdr the program header to iterate over.
351 /// \param Err [out] an error to support fallible iteration, which should
352 /// be checked after iteration ends.
353 iterator_range<Elf_Note_Iterator> notes(const Elf_Phdr &Phdr,
354 Error &Err) const {
355 return make_range(notes_begin(Phdr, Err), notes_end());
356 }
357
358 /// Get an iterator range over notes of a section.
359 ///
360 /// The section must be of type \c SHT_NOTE.
361 ///
362 /// \param Shdr the section to iterate over.
363 /// \param Err [out] an error to support fallible iteration, which should
364 /// be checked after iteration ends.
365 iterator_range<Elf_Note_Iterator> notes(const Elf_Shdr &Shdr,
366 Error &Err) const {
367 return make_range(notes_begin(Shdr, Err), notes_end());
368 }
369
370 Expected<StringRef> getSectionStringTable(
371 Elf_Shdr_Range Sections,
372 WarningHandler WarnHandler = &defaultWarningHandler) const;
373 Expected<uint32_t> getSectionIndex(const Elf_Sym &Sym, Elf_Sym_Range Syms,
374 DataRegion<Elf_Word> ShndxTable) const;
375 Expected<const Elf_Shdr *> getSection(const Elf_Sym &Sym,
376 const Elf_Shdr *SymTab,
377 DataRegion<Elf_Word> ShndxTable) const;
378 Expected<const Elf_Shdr *> getSection(const Elf_Sym &Sym,
379 Elf_Sym_Range Symtab,
380 DataRegion<Elf_Word> ShndxTable) const;
381 Expected<const Elf_Shdr *> getSection(uint32_t Index) const;
382
383 Expected<const Elf_Sym *> getSymbol(const Elf_Shdr *Sec,
384 uint32_t Index) const;
385
386 Expected<StringRef>
387 getSectionName(const Elf_Shdr &Section,
388 WarningHandler WarnHandler = &defaultWarningHandler) const;
389 Expected<StringRef> getSectionName(const Elf_Shdr &Section,
390 StringRef DotShstrtab) const;
391 template <typename T>
392 Expected<ArrayRef<T>> getSectionContentsAsArray(const Elf_Shdr &Sec) const;
393 Expected<ArrayRef<uint8_t>> getSectionContents(const Elf_Shdr &Sec) const;
394 Expected<ArrayRef<uint8_t>> getSegmentContents(const Elf_Phdr &Phdr) const;
395 Expected<std::vector<Elf_BBAddrMap>>
396 decodeBBAddrMap(const Elf_Shdr &Sec) const;
397};
398
399using ELF32LEFile = ELFFile<ELF32LE>;
400using ELF64LEFile = ELFFile<ELF64LE>;
401using ELF32BEFile = ELFFile<ELF32BE>;
402using ELF64BEFile = ELFFile<ELF64BE>;
403
404template <class ELFT>
405inline Expected<const typename ELFT::Shdr *>
406getSection(typename ELFT::ShdrRange Sections, uint32_t Index) {
407 if (Index >= Sections.size())
408 return createError("invalid section index: " + Twine(Index));
409 return &Sections[Index];
410}
411
412template <class ELFT>
413inline Expected<uint32_t>
414getExtendedSymbolTableIndex(const typename ELFT::Sym &Sym, unsigned SymIndex,
415 DataRegion<typename ELFT::Word> ShndxTable) {
416 assert(Sym.st_shndx == ELF::SHN_XINDEX);
417 if (!ShndxTable.First)
418 return createError(
419 "found an extended symbol index (" + Twine(SymIndex) +
420 "), but unable to locate the extended symbol index table");
421
422 Expected<typename ELFT::Word> TableOrErr = ShndxTable[SymIndex];
423 if (!TableOrErr)
424 return createError("unable to read an extended symbol table at index " +
425 Twine(SymIndex) + ": " +
426 toString(TableOrErr.takeError()));
427 return *TableOrErr;
428}
429
430template <class ELFT>
431Expected<uint32_t>
432ELFFile<ELFT>::getSectionIndex(const Elf_Sym &Sym, Elf_Sym_Range Syms,
433 DataRegion<Elf_Word> ShndxTable) const {
434 uint32_t Index = Sym.st_shndx;
435 if (Index == ELF::SHN_XINDEX) {
436 Expected<uint32_t> ErrorOrIndex =
437 getExtendedSymbolTableIndex<ELFT>(Sym, &Sym - Syms.begin(), ShndxTable);
438 if (!ErrorOrIndex)
439 return ErrorOrIndex.takeError();
440 return *ErrorOrIndex;
441 }
442 if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
443 return 0;
444 return Index;
445}
446
447template <class ELFT>
448Expected<const typename ELFT::Shdr *>
449ELFFile<ELFT>::getSection(const Elf_Sym &Sym, const Elf_Shdr *SymTab,
450 DataRegion<Elf_Word> ShndxTable) const {
451 auto SymsOrErr = symbols(SymTab);
452 if (!SymsOrErr)
453 return SymsOrErr.takeError();
454 return getSection(Sym, *SymsOrErr, ShndxTable);
455}
456
457template <class ELFT>
458Expected<const typename ELFT::Shdr *>
459ELFFile<ELFT>::getSection(const Elf_Sym &Sym, Elf_Sym_Range Symbols,
460 DataRegion<Elf_Word> ShndxTable) const {
461 auto IndexOrErr = getSectionIndex(Sym, Symbols, ShndxTable);
462 if (!IndexOrErr)
463 return IndexOrErr.takeError();
464 uint32_t Index = *IndexOrErr;
465 if (Index == 0)
466 return nullptr;
467 return getSection(Index);
468}
469
470template <class ELFT>
471Expected<const typename ELFT::Sym *>
472ELFFile<ELFT>::getSymbol(const Elf_Shdr *Sec, uint32_t Index) const {
473 auto SymsOrErr = symbols(Sec);
474 if (!SymsOrErr)
475 return SymsOrErr.takeError();
476
477 Elf_Sym_Range Symbols = *SymsOrErr;
478 if (Index >= Symbols.size())
479 return createError("unable to get symbol from section " +
480 getSecIndexForError(*this, *Sec) +
481 ": invalid symbol index (" + Twine(Index) + ")");
482 return &Symbols[Index];
483}
484
485template <class ELFT>
486template <typename T>
487Expected<ArrayRef<T>>
488ELFFile<ELFT>::getSectionContentsAsArray(const Elf_Shdr &Sec) const {
489 if (Sec.sh_entsize != sizeof(T) && sizeof(T) != 1)
490 return createError("section " + getSecIndexForError(*this, Sec) +
491 " has invalid sh_entsize: expected " + Twine(sizeof(T)) +
492 ", but got " + Twine(Sec.sh_entsize));
493
494 uintX_t Offset = Sec.sh_offset;
495 uintX_t Size = Sec.sh_size;
496
497 if (Size % sizeof(T))
498 return createError("section " + getSecIndexForError(*this, Sec) +
499 " has an invalid sh_size (" + Twine(Size) +
500 ") which is not a multiple of its sh_entsize (" +
501 Twine(Sec.sh_entsize) + ")");
502 if (std::numeric_limits<uintX_t>::max() - Offset < Size)
503 return createError("section " + getSecIndexForError(*this, Sec) +
504 " has a sh_offset (0x" + Twine::utohexstr(Offset) +
505 ") + sh_size (0x" + Twine::utohexstr(Size) +
506 ") that cannot be represented");
507 if (Offset + Size > Buf.size())
508 return createError("section " + getSecIndexForError(*this, Sec) +
509 " has a sh_offset (0x" + Twine::utohexstr(Offset) +
510 ") + sh_size (0x" + Twine::utohexstr(Size) +
511 ") that is greater than the file size (0x" +
512 Twine::utohexstr(Buf.size()) + ")");
513
514 if (Offset % alignof(T))
515 // TODO: this error is untested.
516 return createError("unaligned data");
517
518 const T *Start = reinterpret_cast<const T *>(base() + Offset);
519 return makeArrayRef(Start, Size / sizeof(T));
520}
521
522template <class ELFT>
523Expected<ArrayRef<uint8_t>>
524ELFFile<ELFT>::getSegmentContents(const Elf_Phdr &Phdr) const {
525 uintX_t Offset = Phdr.p_offset;
526 uintX_t Size = Phdr.p_filesz;
527
528 if (std::numeric_limits<uintX_t>::max() - Offset < Size)
529 return createError("program header " + getPhdrIndexForError(*this, Phdr) +
530 " has a p_offset (0x" + Twine::utohexstr(Offset) +
531 ") + p_filesz (0x" + Twine::utohexstr(Size) +
532 ") that cannot be represented");
533 if (Offset + Size > Buf.size())
534 return createError("program header " + getPhdrIndexForError(*this, Phdr) +
535 " has a p_offset (0x" + Twine::utohexstr(Offset) +
536 ") + p_filesz (0x" + Twine::utohexstr(Size) +
537 ") that is greater than the file size (0x" +
538 Twine::utohexstr(Buf.size()) + ")");
539 return makeArrayRef(base() + Offset, Size);
540}
541
542template <class ELFT>
543Expected<ArrayRef<uint8_t>>
544ELFFile<ELFT>::getSectionContents(const Elf_Shdr &Sec) const {
545 return getSectionContentsAsArray<uint8_t>(Sec);
546}
547
548template <class ELFT>
549StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
550 return getELFRelocationTypeName(getHeader().e_machine, Type);
551}
552
553template <class ELFT>
554void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
555 SmallVectorImpl<char> &Result) const {
556 if (!isMipsELF64()) {
557 StringRef Name = getRelocationTypeName(Type);
558 Result.append(Name.begin(), Name.end());
559 } else {
560 // The Mips N64 ABI allows up to three operations to be specified per
561 // relocation record. Unfortunately there's no easy way to test for the
562 // presence of N64 ELFs as they have no special flag that identifies them
563 // as being N64. We can safely assume at the moment that all Mips
564 // ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
565 // information to disambiguate between old vs new ABIs.
566 uint8_t Type1 = (Type >> 0) & 0xFF;
567 uint8_t Type2 = (Type >> 8) & 0xFF;
568 uint8_t Type3 = (Type >> 16) & 0xFF;
569
570 // Concat all three relocation type names.
571 StringRef Name = getRelocationTypeName(Type1);
572 Result.append(Name.begin(), Name.end());
573
574 Name = getRelocationTypeName(Type2);
575 Result.append(1, '/');
576 Result.append(Name.begin(), Name.end());
577
578 Name = getRelocationTypeName(Type3);
579 Result.append(1, '/');
580 Result.append(Name.begin(), Name.end());
581 }
582}
583
584template <class ELFT>
585uint32_t ELFFile<ELFT>::getRelativeRelocationType() const {
586 return getELFRelativeRelocationType(getHeader().e_machine);
587}
588
589template <class ELFT>
590Expected<SmallVector<Optional<VersionEntry>, 0>>
591ELFFile<ELFT>::loadVersionMap(const Elf_Shdr *VerNeedSec,
592 const Elf_Shdr *VerDefSec) const {
593 SmallVector<Optional<VersionEntry>, 0> VersionMap;
594
595 // The first two version indexes are reserved.
596 // Index 0 is VER_NDX_LOCAL, index 1 is VER_NDX_GLOBAL.
597 VersionMap.push_back(VersionEntry());
598 VersionMap.push_back(VersionEntry());
599
600 auto InsertEntry = [&](unsigned N, StringRef Version, bool IsVerdef) {
601 if (N >= VersionMap.size())
602 VersionMap.resize(N + 1);
603 VersionMap[N] = {std::string(Version), IsVerdef};
604 };
605
606 if (VerDefSec) {
607 Expected<std::vector<VerDef>> Defs = getVersionDefinitions(*VerDefSec);
608 if (!Defs)
609 return Defs.takeError();
610 for (const VerDef &Def : *Defs)
611 InsertEntry(Def.Ndx & ELF::VERSYM_VERSION, Def.Name, true);
612 }
613
614 if (VerNeedSec) {
615 Expected<std::vector<VerNeed>> Deps = getVersionDependencies(*VerNeedSec);
616 if (!Deps)
617 return Deps.takeError();
618 for (const VerNeed &Dep : *Deps)
619 for (const VernAux &Aux : Dep.AuxV)
620 InsertEntry(Aux.Other & ELF::VERSYM_VERSION, Aux.Name, false);
621 }
622
623 return VersionMap;
624}
625
626template <class ELFT>
627Expected<const typename ELFT::Sym *>
628ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel &Rel,
629 const Elf_Shdr *SymTab) const {
630 uint32_t Index = Rel.getSymbol(isMips64EL());
631 if (Index == 0)
632 return nullptr;
633 return getEntry<Elf_Sym>(*SymTab, Index);
634}
635
636template <class ELFT>
637Expected<StringRef>
638ELFFile<ELFT>::getSectionStringTable(Elf_Shdr_Range Sections,
639 WarningHandler WarnHandler) const {
640 uint32_t Index = getHeader().e_shstrndx;
641 if (Index == ELF::SHN_XINDEX) {
642 // If the section name string table section index is greater than
643 // or equal to SHN_LORESERVE, then the actual index of the section name
644 // string table section is contained in the sh_link field of the section
645 // header at index 0.
646 if (Sections.empty())
647 return createError(
648 "e_shstrndx == SHN_XINDEX, but the section header table is empty");
649
650 Index = Sections[0].sh_link;
651 }
652
653 if (!Index) // no section string table.
654 return "";
655 if (Index >= Sections.size())
656 return createError("section header string table index " + Twine(Index) +
657 " does not exist");
658 return getStringTable(Sections[Index], WarnHandler);
659}
660
661/// This function finds the number of dynamic symbols using a GNU hash table.
662///
663/// @param Table The GNU hash table for .dynsym.
664template <class ELFT>
665static Expected<uint64_t>
666getDynSymtabSizeFromGnuHash(const typename ELFT::GnuHash &Table,
667 const void *BufEnd) {
668 using Elf_Word = typename ELFT::Word;
669 if (Table.nbuckets == 0)
670 return Table.symndx + 1;
671 uint64_t LastSymIdx = 0;
672 // Find the index of the first symbol in the last chain.
673 for (Elf_Word Val : Table.buckets())
674 LastSymIdx = std::max(LastSymIdx, (uint64_t)Val);
675 const Elf_Word *It =
676 reinterpret_cast<const Elf_Word *>(Table.values(LastSymIdx).end());
677 // Locate the end of the chain to find the last symbol index.
678 while (It < BufEnd && (*It & 1) == 0) {
679 ++LastSymIdx;
680 ++It;
681 }
682 if (It >= BufEnd) {
683 return createStringError(
684 object_error::parse_failed,
685 "no terminator found for GNU hash section before buffer end");
686 }
687 return LastSymIdx + 1;
688}
689
690/// This function determines the number of dynamic symbols. It reads section
691/// headers first. If section headers are not available, the number of
692/// symbols will be inferred by parsing dynamic hash tables.
693template <class ELFT>
694Expected<uint64_t> ELFFile<ELFT>::getDynSymtabSize() const {
695 // Read .dynsym section header first if available.
696 Expected<Elf_Shdr_Range> SectionsOrError = sections();
697 if (!SectionsOrError)
698 return SectionsOrError.takeError();
699 for (const Elf_Shdr &Sec : *SectionsOrError) {
700 if (Sec.sh_type == ELF::SHT_DYNSYM) {
701 if (Sec.sh_size % Sec.sh_entsize != 0) {
702 return createStringError(object_error::parse_failed,
703 "SHT_DYNSYM section has sh_size (" +
704 Twine(Sec.sh_size) + ") % sh_entsize (" +
705 Twine(Sec.sh_entsize) + ") that is not 0");
706 }
707 return Sec.sh_size / Sec.sh_entsize;
708 }
709 }
710
711 if (!SectionsOrError->empty()) {
712 // Section headers are available but .dynsym header is not found.
713 // Return 0 as .dynsym does not exist.
714 return 0;
715 }
716
717 // Section headers do not exist. Falling back to infer
718 // upper bound of .dynsym from .gnu.hash and .hash.
719 Expected<Elf_Dyn_Range> DynTable = dynamicEntries();
720 if (!DynTable)
721 return DynTable.takeError();
722 llvm::Optional<uint64_t> ElfHash;
723 llvm::Optional<uint64_t> ElfGnuHash;
724 for (const Elf_Dyn &Entry : *DynTable) {
725 switch (Entry.d_tag) {
726 case ELF::DT_HASH:
727 ElfHash = Entry.d_un.d_ptr;
728 break;
729 case ELF::DT_GNU_HASH:
730 ElfGnuHash = Entry.d_un.d_ptr;
731 break;
732 }
733 }
734 if (ElfGnuHash) {
735 Expected<const uint8_t *> TablePtr = toMappedAddr(*ElfGnuHash);
736 if (!TablePtr)
737 return TablePtr.takeError();
738 const Elf_GnuHash *Table =
739 reinterpret_cast<const Elf_GnuHash *>(TablePtr.get());
740 return getDynSymtabSizeFromGnuHash<ELFT>(*Table, this->Buf.bytes_end());
741 }
742
743 // Search SYSV hash table to try to find the upper bound of dynsym.
744 if (ElfHash) {
745 Expected<const uint8_t *> TablePtr = toMappedAddr(*ElfHash);
746 if (!TablePtr)
747 return TablePtr.takeError();
748 const Elf_Hash *Table = reinterpret_cast<const Elf_Hash *>(TablePtr.get());
749 return Table->nchain;
750 }
751 return 0;
752}
753
754template <class ELFT> ELFFile<ELFT>::ELFFile(StringRef Object) : Buf(Object) {}
755
756template <class ELFT>
757Expected<ELFFile<ELFT>> ELFFile<ELFT>::create(StringRef Object) {
758 if (sizeof(Elf_Ehdr) > Object.size())
759 return createError("invalid buffer: the size (" + Twine(Object.size()) +
760 ") is smaller than an ELF header (" +
761 Twine(sizeof(Elf_Ehdr)) + ")");
762 return ELFFile(Object);
763}
764
765template <class ELFT>
766Expected<typename ELFT::ShdrRange> ELFFile<ELFT>::sections() const {
767 const uintX_t SectionTableOffset = getHeader().e_shoff;
768 if (SectionTableOffset == 0)
769 return ArrayRef<Elf_Shdr>();
770
771 if (getHeader().e_shentsize != sizeof(Elf_Shdr))
772 return createError("invalid e_shentsize in ELF header: " +
773 Twine(getHeader().e_shentsize));
774
775 const uint64_t FileSize = Buf.size();
776 if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize ||
777 SectionTableOffset + (uintX_t)sizeof(Elf_Shdr) < SectionTableOffset)
778 return createError(
779 "section header table goes past the end of the file: e_shoff = 0x" +
780 Twine::utohexstr(SectionTableOffset));
781
782 // Invalid address alignment of section headers
783 if (SectionTableOffset & (alignof(Elf_Shdr) - 1))
784 // TODO: this error is untested.
785 return createError("invalid alignment of section headers");
786
787 const Elf_Shdr *First =
788 reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
789
790 uintX_t NumSections = getHeader().e_shnum;
791 if (NumSections == 0)
792 NumSections = First->sh_size;
793
794 if (NumSections > UINT64_MAX / sizeof(Elf_Shdr))
795 return createError("invalid number of sections specified in the NULL "
796 "section's sh_size field (" +
797 Twine(NumSections) + ")");
798
799 const uint64_t SectionTableSize = NumSections * sizeof(Elf_Shdr);
800 if (SectionTableOffset + SectionTableSize < SectionTableOffset)
801 return createError(
802 "invalid section header table offset (e_shoff = 0x" +
803 Twine::utohexstr(SectionTableOffset) +
804 ") or invalid number of sections specified in the first section "
805 "header's sh_size field (0x" +
806 Twine::utohexstr(NumSections) + ")");
807
808 // Section table goes past end of file!
809 if (SectionTableOffset + SectionTableSize > FileSize)
810 return createError("section table goes past the end of file");
811 return makeArrayRef(First, NumSections);
812}
813
814template <class ELFT>
815template <typename T>
816Expected<const T *> ELFFile<ELFT>::getEntry(uint32_t Section,
817 uint32_t Entry) const {
818 auto SecOrErr = getSection(Section);
819 if (!SecOrErr)
820 return SecOrErr.takeError();
821 return getEntry<T>(**SecOrErr, Entry);
822}
823
824template <class ELFT>
825template <typename T>
826Expected<const T *> ELFFile<ELFT>::getEntry(const Elf_Shdr &Section,
827 uint32_t Entry) const {
828 Expected<ArrayRef<T>> EntriesOrErr = getSectionContentsAsArray<T>(Section);
829 if (!EntriesOrErr)
830 return EntriesOrErr.takeError();
831
832 ArrayRef<T> Arr = *EntriesOrErr;
833 if (Entry >= Arr.size())
834 return createError(
835 "can't read an entry at 0x" +
836 Twine::utohexstr(Entry * static_cast<uint64_t>(sizeof(T))) +
837 ": it goes past the end of the section (0x" +
838 Twine::utohexstr(Section.sh_size) + ")");
839 return &Arr[Entry];
840}
841
842template <typename ELFT>
843Expected<StringRef> ELFFile<ELFT>::getSymbolVersionByIndex(
844 uint32_t SymbolVersionIndex, bool &IsDefault,
845 SmallVector<Optional<VersionEntry>, 0> &VersionMap,
846 Optional<bool> IsSymHidden) const {
847 size_t VersionIndex = SymbolVersionIndex & llvm::ELF::VERSYM_VERSION;
848
849 // Special markers for unversioned symbols.
850 if (VersionIndex == llvm::ELF::VER_NDX_LOCAL ||
851 VersionIndex == llvm::ELF::VER_NDX_GLOBAL) {
852 IsDefault = false;
853 return "";
854 }
855
856 // Lookup this symbol in the version table.
857 if (VersionIndex >= VersionMap.size() || !VersionMap[VersionIndex])
858 return createError("SHT_GNU_versym section refers to a version index " +
859 Twine(VersionIndex) + " which is missing");
860
861 const VersionEntry &Entry = *VersionMap[VersionIndex];
862 // A default version (@@) is only available for defined symbols.
863 if (!Entry.IsVerDef || IsSymHidden.getValueOr(false))
864 IsDefault = false;
865 else
866 IsDefault = !(SymbolVersionIndex & llvm::ELF::VERSYM_HIDDEN);
867 return Entry.Name.c_str();
868}
869
870template <class ELFT>
871Expected<std::vector<VerDef>>
872ELFFile<ELFT>::getVersionDefinitions(const Elf_Shdr &Sec) const {
873 Expected<StringRef> StrTabOrErr = getLinkAsStrtab(Sec);
874 if (!StrTabOrErr)
875 return StrTabOrErr.takeError();
876
877 Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
878 if (!ContentsOrErr)
879 return createError("cannot read content of " + describe(*this, Sec) + ": " +
880 toString(ContentsOrErr.takeError()));
881
882 const uint8_t *Start = ContentsOrErr->data();
883 const uint8_t *End = Start + ContentsOrErr->size();
884
885 auto ExtractNextAux = [&](const uint8_t *&VerdauxBuf,
886 unsigned VerDefNdx) -> Expected<VerdAux> {
887 if (VerdauxBuf + sizeof(Elf_Verdaux) > End)
888 return createError("invalid " + describe(*this, Sec) +
889 ": version definition " + Twine(VerDefNdx) +
890 " refers to an auxiliary entry that goes past the end "
891 "of the section");
892
893 auto *Verdaux = reinterpret_cast<const Elf_Verdaux *>(VerdauxBuf);
894 VerdauxBuf += Verdaux->vda_next;
895
896 VerdAux Aux;
897 Aux.Offset = VerdauxBuf - Start;
898 if (Verdaux->vda_name <= StrTabOrErr->size())
899 Aux.Name = std::string(StrTabOrErr->drop_front(Verdaux->vda_name));
900 else
901 Aux.Name = ("<invalid vda_name: " + Twine(Verdaux->vda_name) + ">").str();
902 return Aux;
903 };
904
905 std::vector<VerDef> Ret;
906 const uint8_t *VerdefBuf = Start;
907 for (unsigned I = 1; I <= /*VerDefsNum=*/Sec.sh_info; ++I) {
908 if (VerdefBuf + sizeof(Elf_Verdef) > End)
909 return createError("invalid " + describe(*this, Sec) +
910 ": version definition " + Twine(I) +
911 " goes past the end of the section");
912
913 if (reinterpret_cast<uintptr_t>(VerdefBuf) % sizeof(uint32_t) != 0)
914 return createError(
915 "invalid " + describe(*this, Sec) +
916 ": found a misaligned version definition entry at offset 0x" +
917 Twine::utohexstr(VerdefBuf - Start));
918
919 unsigned Version = *reinterpret_cast<const Elf_Half *>(VerdefBuf);
920 if (Version != 1)
921 return createError("unable to dump " + describe(*this, Sec) +
922 ": version " + Twine(Version) +
923 " is not yet supported");
924
925 const Elf_Verdef *D = reinterpret_cast<const Elf_Verdef *>(VerdefBuf);
926 VerDef &VD = *Ret.emplace(Ret.end());
927 VD.Offset = VerdefBuf - Start;
928 VD.Version = D->vd_version;
929 VD.Flags = D->vd_flags;
930 VD.Ndx = D->vd_ndx;
931 VD.Cnt = D->vd_cnt;
932 VD.Hash = D->vd_hash;
933
934 const uint8_t *VerdauxBuf = VerdefBuf + D->vd_aux;
935 for (unsigned J = 0; J < D->vd_cnt; ++J) {
936 if (reinterpret_cast<uintptr_t>(VerdauxBuf) % sizeof(uint32_t) != 0)
937 return createError("invalid " + describe(*this, Sec) +
938 ": found a misaligned auxiliary entry at offset 0x" +
939 Twine::utohexstr(VerdauxBuf - Start));
940
941 Expected<VerdAux> AuxOrErr = ExtractNextAux(VerdauxBuf, I);
942 if (!AuxOrErr)
943 return AuxOrErr.takeError();
944
945 if (J == 0)
946 VD.Name = AuxOrErr->Name;
947 else
948 VD.AuxV.push_back(*AuxOrErr);
949 }
950
951 VerdefBuf += D->vd_next;
952 }
953
954 return Ret;
955}
956
957template <class ELFT>
958Expected<std::vector<VerNeed>>
959ELFFile<ELFT>::getVersionDependencies(const Elf_Shdr &Sec,
960 WarningHandler WarnHandler) const {
961 StringRef StrTab;
962 Expected<StringRef> StrTabOrErr = getLinkAsStrtab(Sec);
963 if (!StrTabOrErr) {
964 if (Error E = WarnHandler(toString(StrTabOrErr.takeError())))
965 return std::move(E);
966 } else {
967 StrTab = *StrTabOrErr;
968 }
969
970 Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
971 if (!ContentsOrErr)
972 return createError("cannot read content of " + describe(*this, Sec) + ": " +
973 toString(ContentsOrErr.takeError()));
974
975 const uint8_t *Start = ContentsOrErr->data();
976 const uint8_t *End = Start + ContentsOrErr->size();
977 const uint8_t *VerneedBuf = Start;
978
979 std::vector<VerNeed> Ret;
980 for (unsigned I = 1; I <= /*VerneedNum=*/Sec.sh_info; ++I) {
981 if (VerneedBuf + sizeof(Elf_Verdef) > End)
982 return createError("invalid " + describe(*this, Sec) +
983 ": version dependency " + Twine(I) +
984 " goes past the end of the section");
985
986 if (reinterpret_cast<uintptr_t>(VerneedBuf) % sizeof(uint32_t) != 0)
987 return createError(
988 "invalid " + describe(*this, Sec) +
989 ": found a misaligned version dependency entry at offset 0x" +
990 Twine::utohexstr(VerneedBuf - Start));
991
992 unsigned Version = *reinterpret_cast<const Elf_Half *>(VerneedBuf);
993 if (Version != 1)
994 return createError("unable to dump " + describe(*this, Sec) +
995 ": version " + Twine(Version) +
996 " is not yet supported");
997
998 const Elf_Verneed *Verneed =
999 reinterpret_cast<const Elf_Verneed *>(VerneedBuf);
1000
1001 VerNeed &VN = *Ret.emplace(Ret.end());
1002 VN.Version = Verneed->vn_version;
1003 VN.Cnt = Verneed->vn_cnt;
1004 VN.Offset = VerneedBuf - Start;
1005
1006 if (Verneed->vn_file < StrTab.size())
1007 VN.File = std::string(StrTab.drop_front(Verneed->vn_file));
1008 else
1009 VN.File = ("<corrupt vn_file: " + Twine(Verneed->vn_file) + ">").str();
1010
1011 const uint8_t *VernauxBuf = VerneedBuf + Verneed->vn_aux;
1012 for (unsigned J = 0; J < Verneed->vn_cnt; ++J) {
1013 if (reinterpret_cast<uintptr_t>(VernauxBuf) % sizeof(uint32_t) != 0)
1014 return createError("invalid " + describe(*this, Sec) +
1015 ": found a misaligned auxiliary entry at offset 0x" +
1016 Twine::utohexstr(VernauxBuf - Start));
1017
1018 if (VernauxBuf + sizeof(Elf_Vernaux) > End)
1019 return createError(
1020 "invalid " + describe(*this, Sec) + ": version dependency " +
1021 Twine(I) +
1022 " refers to an auxiliary entry that goes past the end "
1023 "of the section");
1024
1025 const Elf_Vernaux *Vernaux =
1026 reinterpret_cast<const Elf_Vernaux *>(VernauxBuf);
1027
1028 VernAux &Aux = *VN.AuxV.emplace(VN.AuxV.end());
1029 Aux.Hash = Vernaux->vna_hash;
1030 Aux.Flags = Vernaux->vna_flags;
1031 Aux.Other = Vernaux->vna_other;
1032 Aux.Offset = VernauxBuf - Start;
1033 if (StrTab.size() <= Vernaux->vna_name)
1034 Aux.Name = "<corrupt>";
1035 else
1036 Aux.Name = std::string(StrTab.drop_front(Vernaux->vna_name));
1037
1038 VernauxBuf += Vernaux->vna_next;
1039 }
1040 VerneedBuf += Verneed->vn_next;
1041 }
1042 return Ret;
1043}
1044
1045template <class ELFT>
1046Expected<const typename ELFT::Shdr *>
1047ELFFile<ELFT>::getSection(uint32_t Index) const {
1048 auto TableOrErr = sections();
1049 if (!TableOrErr)
1050 return TableOrErr.takeError();
1051 return object::getSection<ELFT>(*TableOrErr, Index);
1052}
1053
1054template <class ELFT>
1055Expected<StringRef>
1056ELFFile<ELFT>::getStringTable(const Elf_Shdr &Section,
1057 WarningHandler WarnHandler) const {
1058 if (Section.sh_type != ELF::SHT_STRTAB)
1059 if (Error E = WarnHandler("invalid sh_type for string table section " +
1060 getSecIndexForError(*this, Section) +
1061 ": expected SHT_STRTAB, but got " +
1062 object::getELFSectionTypeName(
1063 getHeader().e_machine, Section.sh_type)))
1064 return std::move(E);
1065
1066 auto V = getSectionContentsAsArray<char>(Section);
1067 if (!V)
1068 return V.takeError();
1069 ArrayRef<char> Data = *V;
1070 if (Data.empty())
1071 return createError("SHT_STRTAB string table section " +
1072 getSecIndexForError(*this, Section) + " is empty");
1073 if (Data.back() != '\0')
1074 return createError("SHT_STRTAB string table section " +
1075 getSecIndexForError(*this, Section) +
1076 " is non-null terminated");
1077 return StringRef(Data.begin(), Data.size());
1078}
1079
1080template <class ELFT>
1081Expected<ArrayRef<typename ELFT::Word>>
1082ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section) const {
1083 auto SectionsOrErr = sections();
1084 if (!SectionsOrErr)
1085 return SectionsOrErr.takeError();
1086 return getSHNDXTable(Section, *SectionsOrErr);
1087}
1088
1089template <class ELFT>
1090Expected<ArrayRef<typename ELFT::Word>>
1091ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section,
1092 Elf_Shdr_Range Sections) const {
1093 assert(Section.sh_type == ELF::SHT_SYMTAB_SHNDX);
1094 auto VOrErr = getSectionContentsAsArray<Elf_Word>(Section);
1095 if (!VOrErr)
1096 return VOrErr.takeError();
1097 ArrayRef<Elf_Word> V = *VOrErr;
1098 auto SymTableOrErr = object::getSection<ELFT>(Sections, Section.sh_link);
1099 if (!SymTableOrErr)
1100 return SymTableOrErr.takeError();
1101 const Elf_Shdr &SymTable = **SymTableOrErr;
1102 if (SymTable.sh_type != ELF::SHT_SYMTAB &&
1103 SymTable.sh_type != ELF::SHT_DYNSYM)
1104 return createError(
1105 "SHT_SYMTAB_SHNDX section is linked with " +
1106 object::getELFSectionTypeName(getHeader().e_machine, SymTable.sh_type) +
1107 " section (expected SHT_SYMTAB/SHT_DYNSYM)");
1108
1109 uint64_t Syms = SymTable.sh_size / sizeof(Elf_Sym);
1110 if (V.size() != Syms)
1111 return createError("SHT_SYMTAB_SHNDX has " + Twine(V.size()) +
1112 " entries, but the symbol table associated has " +
1113 Twine(Syms));
1114
1115 return V;
1116}
1117
1118template <class ELFT>
1119Expected<StringRef>
1120ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
1121 auto SectionsOrErr = sections();
1122 if (!SectionsOrErr)
1123 return SectionsOrErr.takeError();
1124 return getStringTableForSymtab(Sec, *SectionsOrErr);
1125}
1126
1127template <class ELFT>
1128Expected<StringRef>
1129ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec,
1130 Elf_Shdr_Range Sections) const {
1131
1132 if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM)
1133 return createError(
1134 "invalid sh_type for symbol table, expected SHT_SYMTAB or SHT_DYNSYM");
1135 Expected<const Elf_Shdr *> SectionOrErr =
1136 object::getSection<ELFT>(Sections, Sec.sh_link);
1137 if (!SectionOrErr)
1138 return SectionOrErr.takeError();
1139 return getStringTable(**SectionOrErr);
1140}
1141
1142template <class ELFT>
1143Expected<StringRef>
1144ELFFile<ELFT>::getLinkAsStrtab(const typename ELFT::Shdr &Sec) const {
1145 Expected<const typename ELFT::Shdr *> StrTabSecOrErr =
1146 getSection(Sec.sh_link);
1147 if (!StrTabSecOrErr)
1148 return createError("invalid section linked to " + describe(*this, Sec) +
1149 ": " + toString(StrTabSecOrErr.takeError()));
1150
1151 Expected<StringRef> StrTabOrErr = getStringTable(**StrTabSecOrErr);
1152 if (!StrTabOrErr)
1153 return createError("invalid string table linked to " +
1154 describe(*this, Sec) + ": " +
1155 toString(StrTabOrErr.takeError()));
1156 return *StrTabOrErr;
1157}
1158
1159template <class ELFT>
1160Expected<StringRef>
1161ELFFile<ELFT>::getSectionName(const Elf_Shdr &Section,
1162 WarningHandler WarnHandler) const {
1163 auto SectionsOrErr = sections();
1164 if (!SectionsOrErr)
1165 return SectionsOrErr.takeError();
1166 auto Table = getSectionStringTable(*SectionsOrErr, WarnHandler);
1167 if (!Table)
1168 return Table.takeError();
1169 return getSectionName(Section, *Table);
1170}
1171
1172template <class ELFT>
1173Expected<StringRef> ELFFile<ELFT>::getSectionName(const Elf_Shdr &Section,
1174 StringRef DotShstrtab) const {
1175 uint32_t Offset = Section.sh_name;
1176 if (Offset == 0)
1177 return StringRef();
1178 if (Offset >= DotShstrtab.size())
1179 return createError("a section " + getSecIndexForError(*this, Section) +
1180 " has an invalid sh_name (0x" +
1181 Twine::utohexstr(Offset) +
1182 ") offset which goes past the end of the "
1183 "section name string table");
1184 return StringRef(DotShstrtab.data() + Offset);
1185}
1186
1187/// This function returns the hash value for a symbol in the .dynsym section
1188/// Name of the API remains consistent as specified in the libelf
1189/// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash
1190inline unsigned hashSysV(StringRef SymbolName) {
1191 unsigned h = 0, g;
1192 for (char C : SymbolName) {
1193 h = (h << 4) + C;
1194 g = h & 0xf0000000L;
1195 if (g != 0)
1196 h ^= g >> 24;
1197 h &= ~g;
1198 }
1199 return h;
1200}
1201
1202} // end namespace object
1203} // end namespace llvm
1204
1205#endif // LLVM_OBJECT_ELF_H
1206