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/ArrayRef.h"
18#include "llvm/ADT/DenseMap.h"
19#include "llvm/ADT/PointerIntPair.h"
20#include "llvm/ADT/SmallVector.h"
21#include "llvm/ADT/StringSwitch.h"
22#include "llvm/ADT/Triple.h"
23#include "llvm/Object/ELFTypes.h"
24#include "llvm/Object/Error.h"
25#include "llvm/Support/Casting.h"
26#include "llvm/Support/ELF.h"
27#include "llvm/Support/Endian.h"
28#include "llvm/Support/ErrorHandling.h"
29#include "llvm/Support/ErrorOr.h"
30#include "llvm/Support/MemoryBuffer.h"
31#include "llvm/Support/raw_ostream.h"
32#include <algorithm>
33#include <limits>
34#include <utility>
35
36namespace llvm {
37namespace object {
38
39StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type);
40
41// Subclasses of ELFFile may need this for template instantiation
42inline std::pair<unsigned char, unsigned char>
43getElfArchType(StringRef Object) {
44  if (Object.size() < ELF::EI_NIDENT)
45    return std::make_pair((uint8_t)ELF::ELFCLASSNONE,
46                          (uint8_t)ELF::ELFDATANONE);
47  return std::make_pair((uint8_t)Object[ELF::EI_CLASS],
48                        (uint8_t)Object[ELF::EI_DATA]);
49}
50
51template <class ELFT>
52class ELFFile {
53public:
54  LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
55  typedef typename std::conditional<ELFT::Is64Bits,
56                                    uint64_t, uint32_t>::type uintX_t;
57
58  /// \brief Iterate over constant sized entities.
59  template <class EntT>
60  class ELFEntityIterator {
61  public:
62    typedef ptrdiff_t difference_type;
63    typedef EntT value_type;
64    typedef std::forward_iterator_tag iterator_category;
65    typedef value_type &reference;
66    typedef value_type *pointer;
67
68    /// \brief Default construct iterator.
69    ELFEntityIterator() : EntitySize(0), Current(nullptr) {}
70    ELFEntityIterator(uintX_t EntSize, const char *Start)
71        : EntitySize(EntSize), Current(Start) {}
72
73    reference operator *() {
74      assert(Current && "Attempted to dereference an invalid iterator!");
75      return *reinterpret_cast<pointer>(Current);
76    }
77
78    pointer operator ->() {
79      assert(Current && "Attempted to dereference an invalid iterator!");
80      return reinterpret_cast<pointer>(Current);
81    }
82
83    bool operator ==(const ELFEntityIterator &Other) {
84      return Current == Other.Current;
85    }
86
87    bool operator !=(const ELFEntityIterator &Other) {
88      return !(*this == Other);
89    }
90
91    ELFEntityIterator &operator ++() {
92      assert(Current && "Attempted to increment an invalid iterator!");
93      Current += EntitySize;
94      return *this;
95    }
96
97    ELFEntityIterator operator ++(int) {
98      ELFEntityIterator Tmp = *this;
99      ++*this;
100      return Tmp;
101    }
102
103    ELFEntityIterator &operator =(const ELFEntityIterator &Other) {
104      EntitySize = Other.EntitySize;
105      Current = Other.Current;
106      return *this;
107    }
108
109    difference_type operator -(const ELFEntityIterator &Other) const {
110      assert(EntitySize == Other.EntitySize &&
111             "Subtracting iterators of different EntitySize!");
112      return (Current - Other.Current) / EntitySize;
113    }
114
115    const char *get() const { return Current; }
116
117    uintX_t getEntSize() const { return EntitySize; }
118
119  private:
120    uintX_t EntitySize;
121    const char *Current;
122  };
123
124  typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
125  typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
126  typedef Elf_Sym_Impl<ELFT> Elf_Sym;
127  typedef Elf_Dyn_Impl<ELFT> Elf_Dyn;
128  typedef Elf_Phdr_Impl<ELFT> Elf_Phdr;
129  typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
130  typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
131  typedef Elf_Verdef_Impl<ELFT> Elf_Verdef;
132  typedef Elf_Verdaux_Impl<ELFT> Elf_Verdaux;
133  typedef Elf_Verneed_Impl<ELFT> Elf_Verneed;
134  typedef Elf_Vernaux_Impl<ELFT> Elf_Vernaux;
135  typedef Elf_Versym_Impl<ELFT> Elf_Versym;
136  typedef ELFEntityIterator<const Elf_Dyn> Elf_Dyn_Iter;
137  typedef iterator_range<Elf_Dyn_Iter> Elf_Dyn_Range;
138  typedef ELFEntityIterator<const Elf_Rela> Elf_Rela_Iter;
139  typedef ELFEntityIterator<const Elf_Rel> Elf_Rel_Iter;
140  typedef ELFEntityIterator<const Elf_Shdr> Elf_Shdr_Iter;
141  typedef iterator_range<Elf_Shdr_Iter> Elf_Shdr_Range;
142
143  /// \brief Archive files are 2 byte aligned, so we need this for
144  ///     PointerIntPair to work.
145  template <typename T>
146  class ArchivePointerTypeTraits {
147  public:
148    static inline const void *getAsVoidPointer(T *P) { return P; }
149    static inline T *getFromVoidPointer(const void *P) {
150      return static_cast<T *>(P);
151    }
152    enum { NumLowBitsAvailable = 1 };
153  };
154
155  class Elf_Sym_Iter {
156  public:
157    typedef ptrdiff_t difference_type;
158    typedef const Elf_Sym value_type;
159    typedef std::random_access_iterator_tag iterator_category;
160    typedef value_type &reference;
161    typedef value_type *pointer;
162
163    /// \brief Default construct iterator.
164    Elf_Sym_Iter() : EntitySize(0), Current(0, false) {}
165    Elf_Sym_Iter(uintX_t EntSize, const char *Start, bool IsDynamic)
166        : EntitySize(EntSize), Current(Start, IsDynamic) {}
167
168    reference operator*() {
169      assert(Current.getPointer() &&
170             "Attempted to dereference an invalid iterator!");
171      return *reinterpret_cast<pointer>(Current.getPointer());
172    }
173
174    pointer operator->() {
175      assert(Current.getPointer() &&
176             "Attempted to dereference an invalid iterator!");
177      return reinterpret_cast<pointer>(Current.getPointer());
178    }
179
180    bool operator==(const Elf_Sym_Iter &Other) {
181      return Current == Other.Current;
182    }
183
184    bool operator!=(const Elf_Sym_Iter &Other) { return !(*this == Other); }
185
186    Elf_Sym_Iter &operator++() {
187      assert(Current.getPointer() &&
188             "Attempted to increment an invalid iterator!");
189      Current.setPointer(Current.getPointer() + EntitySize);
190      return *this;
191    }
192
193    Elf_Sym_Iter operator++(int) {
194      Elf_Sym_Iter Tmp = *this;
195      ++*this;
196      return Tmp;
197    }
198
199    Elf_Sym_Iter operator+(difference_type Dist) {
200      assert(Current.getPointer() &&
201             "Attempted to increment an invalid iterator!");
202      Current.setPointer(Current.getPointer() + EntitySize * Dist);
203      return *this;
204    }
205
206    Elf_Sym_Iter &operator=(const Elf_Sym_Iter &Other) {
207      EntitySize = Other.EntitySize;
208      Current = Other.Current;
209      return *this;
210    }
211
212    difference_type operator-(const Elf_Sym_Iter &Other) const {
213      assert(EntitySize == Other.EntitySize &&
214             "Subtracting iterators of different EntitySize!");
215      return (Current.getPointer() - Other.Current.getPointer()) / EntitySize;
216    }
217
218    const char *get() const { return Current.getPointer(); }
219
220    bool isDynamic() const { return Current.getInt(); }
221
222    uintX_t getEntSize() const { return EntitySize; }
223
224  private:
225    uintX_t EntitySize;
226    PointerIntPair<const char *, 1, bool,
227                   ArchivePointerTypeTraits<const char> > Current;
228  };
229
230private:
231  typedef SmallVector<const Elf_Shdr *, 2> Sections_t;
232  typedef DenseMap<unsigned, unsigned> IndexMap_t;
233
234  StringRef Buf;
235
236  const uint8_t *base() const {
237    return reinterpret_cast<const uint8_t *>(Buf.data());
238  }
239
240  const Elf_Ehdr *Header;
241  const Elf_Shdr *SectionHeaderTable;
242  const Elf_Shdr *dot_shstrtab_sec; // Section header string table.
243  const Elf_Shdr *dot_strtab_sec;   // Symbol header string table.
244  const Elf_Shdr *dot_symtab_sec;   // Symbol table section.
245
246  const Elf_Shdr *SymbolTableSectionHeaderIndex;
247  DenseMap<const Elf_Sym *, ELF::Elf64_Word> ExtendedSymbolTable;
248
249  const Elf_Shdr *dot_gnu_version_sec;   // .gnu.version
250  const Elf_Shdr *dot_gnu_version_r_sec; // .gnu.version_r
251  const Elf_Shdr *dot_gnu_version_d_sec; // .gnu.version_d
252
253  /// \brief Represents a region described by entries in the .dynamic table.
254  struct DynRegionInfo {
255    DynRegionInfo() : Addr(nullptr), Size(0), EntSize(0) {}
256    /// \brief Address in current address space.
257    const void *Addr;
258    /// \brief Size in bytes of the region.
259    uintX_t Size;
260    /// \brief Size of each entity in the region.
261    uintX_t EntSize;
262  };
263
264  DynRegionInfo DynamicRegion;
265  DynRegionInfo DynHashRegion;
266  DynRegionInfo DynStrRegion;
267  DynRegionInfo DynSymRegion;
268
269  // Pointer to SONAME entry in dynamic string table
270  // This is set the first time getLoadName is called.
271  mutable const char *dt_soname;
272
273  // Records for each version index the corresponding Verdef or Vernaux entry.
274  // This is filled the first time LoadVersionMap() is called.
275  class VersionMapEntry : public PointerIntPair<const void*, 1> {
276    public:
277    // If the integer is 0, this is an Elf_Verdef*.
278    // If the integer is 1, this is an Elf_Vernaux*.
279    VersionMapEntry() : PointerIntPair<const void*, 1>(nullptr, 0) { }
280    VersionMapEntry(const Elf_Verdef *verdef)
281        : PointerIntPair<const void*, 1>(verdef, 0) { }
282    VersionMapEntry(const Elf_Vernaux *vernaux)
283        : PointerIntPair<const void*, 1>(vernaux, 1) { }
284    bool isNull() const { return getPointer() == nullptr; }
285    bool isVerdef() const { return !isNull() && getInt() == 0; }
286    bool isVernaux() const { return !isNull() && getInt() == 1; }
287    const Elf_Verdef *getVerdef() const {
288      return isVerdef() ? (const Elf_Verdef*)getPointer() : nullptr;
289    }
290    const Elf_Vernaux *getVernaux() const {
291      return isVernaux() ? (const Elf_Vernaux*)getPointer() : nullptr;
292    }
293  };
294  mutable SmallVector<VersionMapEntry, 16> VersionMap;
295  void LoadVersionDefs(const Elf_Shdr *sec) const;
296  void LoadVersionNeeds(const Elf_Shdr *ec) const;
297  void LoadVersionMap() const;
298
299public:
300  template<typename T>
301  const T        *getEntry(uint32_t Section, uint32_t Entry) const;
302  template <typename T>
303  const T *getEntry(const Elf_Shdr *Section, uint32_t Entry) const;
304  const char     *getString(uint32_t section, uint32_t offset) const;
305  const char     *getString(const Elf_Shdr *section, uint32_t offset) const;
306  const char *getDynamicString(uintX_t Offset) const;
307  ErrorOr<StringRef> getSymbolVersion(const Elf_Shdr *section,
308                                      const Elf_Sym *Symb,
309                                      bool &IsDefault) const;
310  void VerifyStrTab(const Elf_Shdr *sh) const;
311
312  StringRef getRelocationTypeName(uint32_t Type) const;
313  void getRelocationTypeName(uint32_t Type,
314                             SmallVectorImpl<char> &Result) const;
315
316  /// \brief Get the symbol table section and symbol for a given relocation.
317  template <class RelT>
318  std::pair<const Elf_Shdr *, const Elf_Sym *>
319  getRelocationSymbol(const Elf_Shdr *RelSec, const RelT *Rel) const;
320
321  ELFFile(StringRef Object, std::error_code &ec);
322
323  bool isMipsELF64() const {
324    return Header->e_machine == ELF::EM_MIPS &&
325      Header->getFileClass() == ELF::ELFCLASS64;
326  }
327
328  bool isMips64EL() const {
329    return Header->e_machine == ELF::EM_MIPS &&
330      Header->getFileClass() == ELF::ELFCLASS64 &&
331      Header->getDataEncoding() == ELF::ELFDATA2LSB;
332  }
333
334  Elf_Shdr_Iter begin_sections() const;
335  Elf_Shdr_Iter end_sections() const;
336  Elf_Shdr_Range sections() const {
337    return make_range(begin_sections(), end_sections());
338  }
339
340  Elf_Sym_Iter begin_symbols() const;
341  Elf_Sym_Iter end_symbols() const;
342
343  Elf_Dyn_Iter begin_dynamic_table() const;
344  /// \param NULLEnd use one past the first DT_NULL entry as the end instead of
345  /// the section size.
346  Elf_Dyn_Iter end_dynamic_table(bool NULLEnd = false) const;
347  Elf_Dyn_Range dynamic_table(bool NULLEnd = false) const {
348    return make_range(begin_dynamic_table(), end_dynamic_table(NULLEnd));
349  }
350
351  Elf_Sym_Iter begin_dynamic_symbols() const {
352    if (DynSymRegion.Addr)
353      return Elf_Sym_Iter(DynSymRegion.EntSize, (const char *)DynSymRegion.Addr,
354                          true);
355    return Elf_Sym_Iter(0, nullptr, true);
356  }
357
358  Elf_Sym_Iter end_dynamic_symbols() const {
359    if (DynSymRegion.Addr)
360      return Elf_Sym_Iter(DynSymRegion.EntSize,
361                          (const char *)DynSymRegion.Addr + DynSymRegion.Size,
362                          true);
363    return Elf_Sym_Iter(0, nullptr, true);
364  }
365
366  Elf_Rela_Iter begin_rela(const Elf_Shdr *sec) const {
367    return Elf_Rela_Iter(sec->sh_entsize,
368                         (const char *)(base() + sec->sh_offset));
369  }
370
371  Elf_Rela_Iter end_rela(const Elf_Shdr *sec) const {
372    return Elf_Rela_Iter(
373        sec->sh_entsize,
374        (const char *)(base() + sec->sh_offset + sec->sh_size));
375  }
376
377  Elf_Rel_Iter begin_rel(const Elf_Shdr *sec) const {
378    return Elf_Rel_Iter(sec->sh_entsize,
379                        (const char *)(base() + sec->sh_offset));
380  }
381
382  Elf_Rel_Iter end_rel(const Elf_Shdr *sec) const {
383    return Elf_Rel_Iter(sec->sh_entsize,
384                        (const char *)(base() + sec->sh_offset + sec->sh_size));
385  }
386
387  /// \brief Iterate over program header table.
388  typedef ELFEntityIterator<const Elf_Phdr> Elf_Phdr_Iter;
389
390  Elf_Phdr_Iter begin_program_headers() const {
391    return Elf_Phdr_Iter(Header->e_phentsize,
392                         (const char*)base() + Header->e_phoff);
393  }
394
395  Elf_Phdr_Iter end_program_headers() const {
396    return Elf_Phdr_Iter(Header->e_phentsize,
397                         (const char*)base() +
398                           Header->e_phoff +
399                           (Header->e_phnum * Header->e_phentsize));
400  }
401
402  uint64_t getNumSections() const;
403  uintX_t getStringTableIndex() const;
404  ELF::Elf64_Word getSymbolTableIndex(const Elf_Sym *symb) const;
405  const Elf_Ehdr *getHeader() const { return Header; }
406  const Elf_Shdr *getSection(const Elf_Sym *symb) const;
407  const Elf_Shdr *getSection(uint32_t Index) const;
408  const Elf_Sym *getSymbol(uint32_t index) const;
409
410  ErrorOr<StringRef> getSymbolName(Elf_Sym_Iter Sym) const;
411
412  /// \brief Get the name of \p Symb.
413  /// \param SymTab The symbol table section \p Symb is contained in.
414  /// \param Symb The symbol to get the name of.
415  ///
416  /// \p SymTab is used to lookup the string table to use to get the symbol's
417  /// name.
418  ErrorOr<StringRef> getSymbolName(const Elf_Shdr *SymTab,
419                                   const Elf_Sym *Symb) const;
420  ErrorOr<StringRef> getSectionName(const Elf_Shdr *Section) const;
421  uint64_t getSymbolIndex(const Elf_Sym *sym) const;
422  ErrorOr<ArrayRef<uint8_t> > getSectionContents(const Elf_Shdr *Sec) const;
423  StringRef getLoadName() const;
424};
425
426// Use an alignment of 2 for the typedefs since that is the worst case for
427// ELF files in archives.
428typedef ELFFile<ELFType<support::little, 2, false> > ELF32LEFile;
429typedef ELFFile<ELFType<support::little, 2, true> > ELF64LEFile;
430typedef ELFFile<ELFType<support::big, 2, false> > ELF32BEFile;
431typedef ELFFile<ELFType<support::big, 2, true> > ELF64BEFile;
432
433// Iterate through the version definitions, and place each Elf_Verdef
434// in the VersionMap according to its index.
435template <class ELFT>
436void ELFFile<ELFT>::LoadVersionDefs(const Elf_Shdr *sec) const {
437  unsigned vd_size = sec->sh_size;  // Size of section in bytes
438  unsigned vd_count = sec->sh_info; // Number of Verdef entries
439  const char *sec_start = (const char*)base() + sec->sh_offset;
440  const char *sec_end = sec_start + vd_size;
441  // The first Verdef entry is at the start of the section.
442  const char *p = sec_start;
443  for (unsigned i = 0; i < vd_count; i++) {
444    if (p + sizeof(Elf_Verdef) > sec_end)
445      report_fatal_error("Section ended unexpectedly while scanning "
446                         "version definitions.");
447    const Elf_Verdef *vd = reinterpret_cast<const Elf_Verdef *>(p);
448    if (vd->vd_version != ELF::VER_DEF_CURRENT)
449      report_fatal_error("Unexpected verdef version");
450    size_t index = vd->vd_ndx & ELF::VERSYM_VERSION;
451    if (index >= VersionMap.size())
452      VersionMap.resize(index + 1);
453    VersionMap[index] = VersionMapEntry(vd);
454    p += vd->vd_next;
455  }
456}
457
458// Iterate through the versions needed section, and place each Elf_Vernaux
459// in the VersionMap according to its index.
460template <class ELFT>
461void ELFFile<ELFT>::LoadVersionNeeds(const Elf_Shdr *sec) const {
462  unsigned vn_size = sec->sh_size;  // Size of section in bytes
463  unsigned vn_count = sec->sh_info; // Number of Verneed entries
464  const char *sec_start = (const char *)base() + sec->sh_offset;
465  const char *sec_end = sec_start + vn_size;
466  // The first Verneed entry is at the start of the section.
467  const char *p = sec_start;
468  for (unsigned i = 0; i < vn_count; i++) {
469    if (p + sizeof(Elf_Verneed) > sec_end)
470      report_fatal_error("Section ended unexpectedly while scanning "
471                         "version needed records.");
472    const Elf_Verneed *vn = reinterpret_cast<const Elf_Verneed *>(p);
473    if (vn->vn_version != ELF::VER_NEED_CURRENT)
474      report_fatal_error("Unexpected verneed version");
475    // Iterate through the Vernaux entries
476    const char *paux = p + vn->vn_aux;
477    for (unsigned j = 0; j < vn->vn_cnt; j++) {
478      if (paux + sizeof(Elf_Vernaux) > sec_end)
479        report_fatal_error("Section ended unexpected while scanning auxiliary "
480                           "version needed records.");
481      const Elf_Vernaux *vna = reinterpret_cast<const Elf_Vernaux *>(paux);
482      size_t index = vna->vna_other & ELF::VERSYM_VERSION;
483      if (index >= VersionMap.size())
484        VersionMap.resize(index + 1);
485      VersionMap[index] = VersionMapEntry(vna);
486      paux += vna->vna_next;
487    }
488    p += vn->vn_next;
489  }
490}
491
492template <class ELFT>
493void ELFFile<ELFT>::LoadVersionMap() const {
494  // If there is no dynamic symtab or version table, there is nothing to do.
495  if (!DynSymRegion.Addr || !dot_gnu_version_sec)
496    return;
497
498  // Has the VersionMap already been loaded?
499  if (VersionMap.size() > 0)
500    return;
501
502  // The first two version indexes are reserved.
503  // Index 0 is LOCAL, index 1 is GLOBAL.
504  VersionMap.push_back(VersionMapEntry());
505  VersionMap.push_back(VersionMapEntry());
506
507  if (dot_gnu_version_d_sec)
508    LoadVersionDefs(dot_gnu_version_d_sec);
509
510  if (dot_gnu_version_r_sec)
511    LoadVersionNeeds(dot_gnu_version_r_sec);
512}
513
514template <class ELFT>
515ELF::Elf64_Word ELFFile<ELFT>::getSymbolTableIndex(const Elf_Sym *symb) const {
516  if (symb->st_shndx == ELF::SHN_XINDEX)
517    return ExtendedSymbolTable.lookup(symb);
518  return symb->st_shndx;
519}
520
521template <class ELFT>
522const typename ELFFile<ELFT>::Elf_Shdr *
523ELFFile<ELFT>::getSection(const Elf_Sym *symb) const {
524  if (symb->st_shndx == ELF::SHN_XINDEX)
525    return getSection(ExtendedSymbolTable.lookup(symb));
526  if (symb->st_shndx >= ELF::SHN_LORESERVE)
527    return nullptr;
528  return getSection(symb->st_shndx);
529}
530
531template <class ELFT>
532const typename ELFFile<ELFT>::Elf_Sym *
533ELFFile<ELFT>::getSymbol(uint32_t Index) const {
534  return &*(begin_symbols() + Index);
535}
536
537template <class ELFT>
538ErrorOr<ArrayRef<uint8_t> >
539ELFFile<ELFT>::getSectionContents(const Elf_Shdr *Sec) const {
540  if (Sec->sh_offset + Sec->sh_size > Buf.size())
541    return object_error::parse_failed;
542  const uint8_t *Start = base() + Sec->sh_offset;
543  return ArrayRef<uint8_t>(Start, Sec->sh_size);
544}
545
546template <class ELFT>
547StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
548  return getELFRelocationTypeName(Header->e_machine, Type);
549}
550
551template <class ELFT>
552void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
553                                          SmallVectorImpl<char> &Result) const {
554  if (!isMipsELF64()) {
555    StringRef Name = getRelocationTypeName(Type);
556    Result.append(Name.begin(), Name.end());
557  } else {
558    // The Mips N64 ABI allows up to three operations to be specified per
559    // relocation record. Unfortunately there's no easy way to test for the
560    // presence of N64 ELFs as they have no special flag that identifies them
561    // as being N64. We can safely assume at the moment that all Mips
562    // ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
563    // information to disambiguate between old vs new ABIs.
564    uint8_t Type1 = (Type >> 0) & 0xFF;
565    uint8_t Type2 = (Type >> 8) & 0xFF;
566    uint8_t Type3 = (Type >> 16) & 0xFF;
567
568    // Concat all three relocation type names.
569    StringRef Name = getRelocationTypeName(Type1);
570    Result.append(Name.begin(), Name.end());
571
572    Name = getRelocationTypeName(Type2);
573    Result.append(1, '/');
574    Result.append(Name.begin(), Name.end());
575
576    Name = getRelocationTypeName(Type3);
577    Result.append(1, '/');
578    Result.append(Name.begin(), Name.end());
579  }
580}
581
582template <class ELFT>
583template <class RelT>
584std::pair<const typename ELFFile<ELFT>::Elf_Shdr *,
585          const typename ELFFile<ELFT>::Elf_Sym *>
586ELFFile<ELFT>::getRelocationSymbol(const Elf_Shdr *Sec, const RelT *Rel) const {
587  if (!Sec->sh_link)
588    return std::make_pair(nullptr, nullptr);
589  const Elf_Shdr *SymTable = getSection(Sec->sh_link);
590  return std::make_pair(
591      SymTable, getEntry<Elf_Sym>(SymTable, Rel->getSymbol(isMips64EL())));
592}
593
594// Verify that the last byte in the string table in a null.
595template <class ELFT>
596void ELFFile<ELFT>::VerifyStrTab(const Elf_Shdr *sh) const {
597  const char *strtab = (const char *)base() + sh->sh_offset;
598  if (strtab[sh->sh_size - 1] != 0)
599    // FIXME: Proper error handling.
600    report_fatal_error("String table must end with a null terminator!");
601}
602
603template <class ELFT>
604uint64_t ELFFile<ELFT>::getNumSections() const {
605  assert(Header && "Header not initialized!");
606  if (Header->e_shnum == ELF::SHN_UNDEF && Header->e_shoff > 0) {
607    assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
608    return SectionHeaderTable->sh_size;
609  }
610  return Header->e_shnum;
611}
612
613template <class ELFT>
614typename ELFFile<ELFT>::uintX_t ELFFile<ELFT>::getStringTableIndex() const {
615  if (Header->e_shnum == ELF::SHN_UNDEF) {
616    if (Header->e_shstrndx == ELF::SHN_HIRESERVE)
617      return SectionHeaderTable->sh_link;
618    if (Header->e_shstrndx >= getNumSections())
619      return 0;
620  }
621  return Header->e_shstrndx;
622}
623
624template <class ELFT>
625ELFFile<ELFT>::ELFFile(StringRef Object, std::error_code &ec)
626    : Buf(Object), SectionHeaderTable(nullptr), dot_shstrtab_sec(nullptr),
627      dot_strtab_sec(nullptr), dot_symtab_sec(nullptr),
628      SymbolTableSectionHeaderIndex(nullptr), dot_gnu_version_sec(nullptr),
629      dot_gnu_version_r_sec(nullptr), dot_gnu_version_d_sec(nullptr),
630      dt_soname(nullptr) {
631  const uint64_t FileSize = Buf.size();
632
633  if (sizeof(Elf_Ehdr) > FileSize)
634    // FIXME: Proper error handling.
635    report_fatal_error("File too short!");
636
637  Header = reinterpret_cast<const Elf_Ehdr *>(base());
638
639  if (Header->e_shoff == 0)
640    return;
641
642  const uint64_t SectionTableOffset = Header->e_shoff;
643
644  if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize)
645    // FIXME: Proper error handling.
646    report_fatal_error("Section header table goes past end of file!");
647
648  // The getNumSections() call below depends on SectionHeaderTable being set.
649  SectionHeaderTable =
650    reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
651  const uint64_t SectionTableSize = getNumSections() * Header->e_shentsize;
652
653  if (SectionTableOffset + SectionTableSize > FileSize)
654    // FIXME: Proper error handling.
655    report_fatal_error("Section table goes past end of file!");
656
657  // Scan sections for special sections.
658
659  for (const Elf_Shdr &Sec : sections()) {
660    switch (Sec.sh_type) {
661    case ELF::SHT_SYMTAB_SHNDX:
662      if (SymbolTableSectionHeaderIndex)
663        // FIXME: Proper error handling.
664        report_fatal_error("More than one .symtab_shndx!");
665      SymbolTableSectionHeaderIndex = &Sec;
666      break;
667    case ELF::SHT_SYMTAB:
668      if (dot_symtab_sec)
669        // FIXME: Proper error handling.
670        report_fatal_error("More than one .symtab!");
671      dot_symtab_sec = &Sec;
672      dot_strtab_sec = getSection(Sec.sh_link);
673      break;
674    case ELF::SHT_DYNSYM: {
675      if (DynSymRegion.Addr)
676        // FIXME: Proper error handling.
677        report_fatal_error("More than one .dynsym!");
678      DynSymRegion.Addr = base() + Sec.sh_offset;
679      DynSymRegion.Size = Sec.sh_size;
680      DynSymRegion.EntSize = Sec.sh_entsize;
681      const Elf_Shdr *DynStr = getSection(Sec.sh_link);
682      DynStrRegion.Addr = base() + DynStr->sh_offset;
683      DynStrRegion.Size = DynStr->sh_size;
684      DynStrRegion.EntSize = DynStr->sh_entsize;
685      break;
686    }
687    case ELF::SHT_DYNAMIC:
688      if (DynamicRegion.Addr)
689        // FIXME: Proper error handling.
690        report_fatal_error("More than one .dynamic!");
691      DynamicRegion.Addr = base() + Sec.sh_offset;
692      DynamicRegion.Size = Sec.sh_size;
693      DynamicRegion.EntSize = Sec.sh_entsize;
694      break;
695    case ELF::SHT_GNU_versym:
696      if (dot_gnu_version_sec != nullptr)
697        // FIXME: Proper error handling.
698        report_fatal_error("More than one .gnu.version section!");
699      dot_gnu_version_sec = &Sec;
700      break;
701    case ELF::SHT_GNU_verdef:
702      if (dot_gnu_version_d_sec != nullptr)
703        // FIXME: Proper error handling.
704        report_fatal_error("More than one .gnu.version_d section!");
705      dot_gnu_version_d_sec = &Sec;
706      break;
707    case ELF::SHT_GNU_verneed:
708      if (dot_gnu_version_r_sec != nullptr)
709        // FIXME: Proper error handling.
710        report_fatal_error("More than one .gnu.version_r section!");
711      dot_gnu_version_r_sec = &Sec;
712      break;
713    }
714  }
715
716  // Get string table sections.
717  dot_shstrtab_sec = getSection(getStringTableIndex());
718  if (dot_shstrtab_sec) {
719    // Verify that the last byte in the string table in a null.
720    VerifyStrTab(dot_shstrtab_sec);
721  }
722
723  // Build symbol name side-mapping if there is one.
724  if (SymbolTableSectionHeaderIndex) {
725    const Elf_Word *ShndxTable = reinterpret_cast<const Elf_Word*>(base() +
726                                      SymbolTableSectionHeaderIndex->sh_offset);
727    for (Elf_Sym_Iter SI = begin_symbols(), SE = end_symbols(); SI != SE;
728         ++SI) {
729      if (*ShndxTable != ELF::SHN_UNDEF)
730        ExtendedSymbolTable[&*SI] = *ShndxTable;
731      ++ShndxTable;
732    }
733  }
734
735  // Scan program headers.
736  for (Elf_Phdr_Iter PhdrI = begin_program_headers(),
737                     PhdrE = end_program_headers();
738       PhdrI != PhdrE; ++PhdrI) {
739    if (PhdrI->p_type == ELF::PT_DYNAMIC) {
740      DynamicRegion.Addr = base() + PhdrI->p_offset;
741      DynamicRegion.Size = PhdrI->p_filesz;
742      DynamicRegion.EntSize = sizeof(Elf_Dyn);
743      break;
744    }
745  }
746
747  ec = std::error_code();
748}
749
750// Get the symbol table index in the symtab section given a symbol
751template <class ELFT>
752uint64_t ELFFile<ELFT>::getSymbolIndex(const Elf_Sym *Sym) const {
753  uintptr_t SymLoc = uintptr_t(Sym);
754  uintptr_t SymTabLoc = uintptr_t(base() + dot_symtab_sec->sh_offset);
755  assert(SymLoc > SymTabLoc && "Symbol not in symbol table!");
756  uint64_t SymOffset = SymLoc - SymTabLoc;
757  assert(SymOffset % dot_symtab_sec->sh_entsize == 0 &&
758         "Symbol not multiple of symbol size!");
759  return SymOffset / dot_symtab_sec->sh_entsize;
760}
761
762template <class ELFT>
763typename ELFFile<ELFT>::Elf_Shdr_Iter ELFFile<ELFT>::begin_sections() const {
764  return Elf_Shdr_Iter(Header->e_shentsize,
765                       (const char *)base() + Header->e_shoff);
766}
767
768template <class ELFT>
769typename ELFFile<ELFT>::Elf_Shdr_Iter ELFFile<ELFT>::end_sections() const {
770  return Elf_Shdr_Iter(Header->e_shentsize,
771                       (const char *)base() + Header->e_shoff +
772                           (getNumSections() * Header->e_shentsize));
773}
774
775template <class ELFT>
776typename ELFFile<ELFT>::Elf_Sym_Iter ELFFile<ELFT>::begin_symbols() const {
777  if (!dot_symtab_sec)
778    return Elf_Sym_Iter(0, nullptr, false);
779  return Elf_Sym_Iter(dot_symtab_sec->sh_entsize,
780                      (const char *)base() + dot_symtab_sec->sh_offset, false);
781}
782
783template <class ELFT>
784typename ELFFile<ELFT>::Elf_Sym_Iter ELFFile<ELFT>::end_symbols() const {
785  if (!dot_symtab_sec)
786    return Elf_Sym_Iter(0, nullptr, false);
787  return Elf_Sym_Iter(dot_symtab_sec->sh_entsize,
788                      (const char *)base() + dot_symtab_sec->sh_offset +
789                          dot_symtab_sec->sh_size,
790                      false);
791}
792
793template <class ELFT>
794typename ELFFile<ELFT>::Elf_Dyn_Iter
795ELFFile<ELFT>::begin_dynamic_table() const {
796  if (DynamicRegion.Addr)
797    return Elf_Dyn_Iter(DynamicRegion.EntSize,
798                        (const char *)DynamicRegion.Addr);
799  return Elf_Dyn_Iter(0, nullptr);
800}
801
802template <class ELFT>
803typename ELFFile<ELFT>::Elf_Dyn_Iter
804ELFFile<ELFT>::end_dynamic_table(bool NULLEnd) const {
805  if (!DynamicRegion.Addr)
806    return Elf_Dyn_Iter(0, nullptr);
807  Elf_Dyn_Iter Ret(DynamicRegion.EntSize,
808                    (const char *)DynamicRegion.Addr + DynamicRegion.Size);
809
810  if (NULLEnd) {
811    Elf_Dyn_Iter Start = begin_dynamic_table();
812    while (Start != Ret && Start->getTag() != ELF::DT_NULL)
813      ++Start;
814
815    // Include the DT_NULL.
816    if (Start != Ret)
817      ++Start;
818    Ret = Start;
819  }
820  return Ret;
821}
822
823template <class ELFT>
824StringRef ELFFile<ELFT>::getLoadName() const {
825  if (!dt_soname) {
826    dt_soname = "";
827    // Find the DT_SONAME entry
828    for (const auto &Entry : dynamic_table())
829      if (Entry.getTag() == ELF::DT_SONAME) {
830        dt_soname = getDynamicString(Entry.getVal());
831        break;
832      }
833  }
834  return dt_soname;
835}
836
837template <class ELFT>
838template <typename T>
839const T *ELFFile<ELFT>::getEntry(uint32_t Section, uint32_t Entry) const {
840  return getEntry<T>(getSection(Section), Entry);
841}
842
843template <class ELFT>
844template <typename T>
845const T *ELFFile<ELFT>::getEntry(const Elf_Shdr *Section,
846                                 uint32_t Entry) const {
847  return reinterpret_cast<const T *>(base() + Section->sh_offset +
848                                     (Entry * Section->sh_entsize));
849}
850
851template <class ELFT>
852const typename ELFFile<ELFT>::Elf_Shdr *
853ELFFile<ELFT>::getSection(uint32_t index) const {
854  if (index == 0)
855    return nullptr;
856  if (!SectionHeaderTable || index >= getNumSections())
857    // FIXME: Proper error handling.
858    report_fatal_error("Invalid section index!");
859
860  return reinterpret_cast<const Elf_Shdr *>(
861         reinterpret_cast<const char *>(SectionHeaderTable)
862         + (index * Header->e_shentsize));
863}
864
865template <class ELFT>
866const char *ELFFile<ELFT>::getString(uint32_t section,
867                                     ELF::Elf32_Word offset) const {
868  return getString(getSection(section), offset);
869}
870
871template <class ELFT>
872const char *ELFFile<ELFT>::getString(const Elf_Shdr *section,
873                                     ELF::Elf32_Word offset) const {
874  assert(section && section->sh_type == ELF::SHT_STRTAB && "Invalid section!");
875  if (offset >= section->sh_size)
876    // FIXME: Proper error handling.
877    report_fatal_error("Symbol name offset outside of string table!");
878  return (const char *)base() + section->sh_offset + offset;
879}
880
881template <class ELFT>
882const char *ELFFile<ELFT>::getDynamicString(uintX_t Offset) const {
883  if (!DynStrRegion.Addr || Offset >= DynStrRegion.Size)
884    return nullptr;
885  return (const char *)DynStrRegion.Addr + Offset;
886}
887
888template <class ELFT>
889ErrorOr<StringRef> ELFFile<ELFT>::getSymbolName(Elf_Sym_Iter Sym) const {
890  if (!Sym.isDynamic())
891    return getSymbolName(dot_symtab_sec, &*Sym);
892
893  if (!DynStrRegion.Addr || Sym->st_name >= DynStrRegion.Size)
894    return object_error::parse_failed;
895  return StringRef(getDynamicString(Sym->st_name));
896}
897
898template <class ELFT>
899ErrorOr<StringRef> ELFFile<ELFT>::getSymbolName(const Elf_Shdr *Section,
900                                                const Elf_Sym *Symb) const {
901  if (Symb->st_name == 0) {
902    const Elf_Shdr *ContainingSec = getSection(Symb);
903    if (ContainingSec)
904      return getSectionName(ContainingSec);
905  }
906
907  const Elf_Shdr *StrTab = getSection(Section->sh_link);
908  if (Symb->st_name >= StrTab->sh_size)
909    return object_error::parse_failed;
910  return StringRef(getString(StrTab, Symb->st_name));
911}
912
913template <class ELFT>
914ErrorOr<StringRef>
915ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section) const {
916  if (Section->sh_name >= dot_shstrtab_sec->sh_size)
917    return object_error::parse_failed;
918  return StringRef(getString(dot_shstrtab_sec, Section->sh_name));
919}
920
921template <class ELFT>
922ErrorOr<StringRef> ELFFile<ELFT>::getSymbolVersion(const Elf_Shdr *section,
923                                                   const Elf_Sym *symb,
924                                                   bool &IsDefault) const {
925  // Handle non-dynamic symbols.
926  if (section != DynSymRegion.Addr && section != nullptr) {
927    // Non-dynamic symbols can have versions in their names
928    // A name of the form 'foo@V1' indicates version 'V1', non-default.
929    // A name of the form 'foo@@V2' indicates version 'V2', default version.
930    ErrorOr<StringRef> SymName = getSymbolName(section, symb);
931    if (!SymName)
932      return SymName;
933    StringRef Name = *SymName;
934    size_t atpos = Name.find('@');
935    if (atpos == StringRef::npos) {
936      IsDefault = false;
937      return StringRef("");
938    }
939    ++atpos;
940    if (atpos < Name.size() && Name[atpos] == '@') {
941      IsDefault = true;
942      ++atpos;
943    } else {
944      IsDefault = false;
945    }
946    return Name.substr(atpos);
947  }
948
949  // This is a dynamic symbol. Look in the GNU symbol version table.
950  if (!dot_gnu_version_sec) {
951    // No version table.
952    IsDefault = false;
953    return StringRef("");
954  }
955
956  // Determine the position in the symbol table of this entry.
957  size_t entry_index = ((const char *)symb - (const char *)DynSymRegion.Addr) /
958                       DynSymRegion.EntSize;
959
960  // Get the corresponding version index entry
961  const Elf_Versym *vs = getEntry<Elf_Versym>(dot_gnu_version_sec, entry_index);
962  size_t version_index = vs->vs_index & ELF::VERSYM_VERSION;
963
964  // Special markers for unversioned symbols.
965  if (version_index == ELF::VER_NDX_LOCAL ||
966      version_index == ELF::VER_NDX_GLOBAL) {
967    IsDefault = false;
968    return StringRef("");
969  }
970
971  // Lookup this symbol in the version table
972  LoadVersionMap();
973  if (version_index >= VersionMap.size() || VersionMap[version_index].isNull())
974    return object_error::parse_failed;
975  const VersionMapEntry &entry = VersionMap[version_index];
976
977  // Get the version name string
978  size_t name_offset;
979  if (entry.isVerdef()) {
980    // The first Verdaux entry holds the name.
981    name_offset = entry.getVerdef()->getAux()->vda_name;
982  } else {
983    name_offset = entry.getVernaux()->vna_name;
984  }
985
986  // Set IsDefault
987  if (entry.isVerdef()) {
988    IsDefault = !(vs->vs_index & ELF::VERSYM_HIDDEN);
989  } else {
990    IsDefault = false;
991  }
992
993  if (name_offset >= DynStrRegion.Size)
994    return object_error::parse_failed;
995  return StringRef(getDynamicString(name_offset));
996}
997
998/// This function returns the hash value for a symbol in the .dynsym section
999/// Name of the API remains consistent as specified in the libelf
1000/// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash
1001static inline unsigned elf_hash(StringRef &symbolName) {
1002  unsigned h = 0, g;
1003  for (unsigned i = 0, j = symbolName.size(); i < j; i++) {
1004    h = (h << 4) + symbolName[i];
1005    g = h & 0xf0000000L;
1006    if (g != 0)
1007      h ^= g >> 24;
1008    h &= ~g;
1009  }
1010  return h;
1011}
1012} // end namespace object
1013} // end namespace llvm
1014
1015#endif
1016