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llvm-6502/include/llvm/Object/ELF.h
Alexey Samsonov 8ecf661ef1 Object, ELF: Use error code instead of calling report_fatal_error() 
Make createELFObjectFile() return object_error::parse_failed on
encountering invalid ELF file, instead of crashing the program.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238481 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-28 20:25:42 +00:00

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//===- ELF.h - ELF object file implementation -------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the ELFFile template class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_OBJECT_ELF_H
#define LLVM_OBJECT_ELF_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Object/ELFTypes.h"
#include "llvm/Object/Error.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <limits>
#include <utility>
namespace llvm {
namespace object {
StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type);
// Subclasses of ELFFile may need this for template instantiation
inline std::pair<unsigned char, unsigned char>
getElfArchType(StringRef Object) {
if (Object.size() < ELF::EI_NIDENT)
return std::make_pair((uint8_t)ELF::ELFCLASSNONE,
(uint8_t)ELF::ELFDATANONE);
return std::make_pair((uint8_t)Object[ELF::EI_CLASS],
(uint8_t)Object[ELF::EI_DATA]);
}
template <class ELFT>
class ELFFile {
public:
LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
typedef typename std::conditional<ELFT::Is64Bits,
uint64_t, uint32_t>::type uintX_t;
/// \brief Iterate over constant sized entities.
template <class EntT>
class ELFEntityIterator {
public:
typedef ptrdiff_t difference_type;
typedef EntT value_type;
typedef std::forward_iterator_tag iterator_category;
typedef value_type &reference;
typedef value_type *pointer;
/// \brief Default construct iterator.
ELFEntityIterator() : EntitySize(0), Current(nullptr) {}
ELFEntityIterator(uintX_t EntSize, const char *Start)
: EntitySize(EntSize), Current(Start) {}
reference operator *() {
assert(Current && "Attempted to dereference an invalid iterator!");
return *reinterpret_cast<pointer>(Current);
}
pointer operator ->() {
assert(Current && "Attempted to dereference an invalid iterator!");
return reinterpret_cast<pointer>(Current);
}
bool operator ==(const ELFEntityIterator &Other) {
return Current == Other.Current;
}
bool operator !=(const ELFEntityIterator &Other) {
return !(*this == Other);
}
ELFEntityIterator &operator ++() {
assert(Current && "Attempted to increment an invalid iterator!");
Current += EntitySize;
return *this;
}
ELFEntityIterator &operator+(difference_type n) {
assert(Current && "Attempted to increment an invalid iterator!");
Current += (n * EntitySize);
return *this;
}
ELFEntityIterator &operator-(difference_type n) {
assert(Current && "Attempted to subtract an invalid iterator!");
Current -= (n * EntitySize);
return *this;
}
ELFEntityIterator operator ++(int) {
ELFEntityIterator Tmp = *this;
++*this;
return Tmp;
}
difference_type operator -(const ELFEntityIterator &Other) const {
assert(EntitySize == Other.EntitySize &&
"Subtracting iterators of different EntitySize!");
return (Current - Other.Current) / EntitySize;
}
const char *get() const { return Current; }
uintX_t getEntSize() const { return EntitySize; }
private:
uintX_t EntitySize;
const char *Current;
};
typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
typedef Elf_Sym_Impl<ELFT> Elf_Sym;
typedef Elf_Dyn_Impl<ELFT> Elf_Dyn;
typedef Elf_Phdr_Impl<ELFT> Elf_Phdr;
typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
typedef Elf_Verdef_Impl<ELFT> Elf_Verdef;
typedef Elf_Verdaux_Impl<ELFT> Elf_Verdaux;
typedef Elf_Verneed_Impl<ELFT> Elf_Verneed;
typedef Elf_Vernaux_Impl<ELFT> Elf_Vernaux;
typedef Elf_Versym_Impl<ELFT> Elf_Versym;
typedef ELFEntityIterator<const Elf_Dyn> Elf_Dyn_Iter;
typedef iterator_range<Elf_Dyn_Iter> Elf_Dyn_Range;
typedef ELFEntityIterator<const Elf_Rela> Elf_Rela_Iter;
typedef ELFEntityIterator<const Elf_Rel> Elf_Rel_Iter;
typedef ELFEntityIterator<const Elf_Shdr> Elf_Shdr_Iter;
typedef iterator_range<Elf_Shdr_Iter> Elf_Shdr_Range;
/// \brief Archive files are 2 byte aligned, so we need this for
/// PointerIntPair to work.
template <typename T>
class ArchivePointerTypeTraits {
public:
static inline const void *getAsVoidPointer(T *P) { return P; }
static inline T *getFromVoidPointer(const void *P) {
return static_cast<T *>(P);
}
enum { NumLowBitsAvailable = 1 };
};
class Elf_Sym_Iter {
public:
typedef ptrdiff_t difference_type;
typedef const Elf_Sym value_type;
typedef std::random_access_iterator_tag iterator_category;
typedef value_type &reference;
typedef value_type *pointer;
/// \brief Default construct iterator.
Elf_Sym_Iter() : EntitySize(0), Current(0, false) {}
Elf_Sym_Iter(uintX_t EntSize, const char *Start, bool IsDynamic)
: EntitySize(EntSize), Current(Start, IsDynamic) {}
reference operator*() {
assert(Current.getPointer() &&
"Attempted to dereference an invalid iterator!");
return *reinterpret_cast<pointer>(Current.getPointer());
}
pointer operator->() {
assert(Current.getPointer() &&
"Attempted to dereference an invalid iterator!");
return reinterpret_cast<pointer>(Current.getPointer());
}
bool operator==(const Elf_Sym_Iter &Other) {
return Current == Other.Current;
}
bool operator!=(const Elf_Sym_Iter &Other) { return !(*this == Other); }
Elf_Sym_Iter &operator++() {
assert(Current.getPointer() &&
"Attempted to increment an invalid iterator!");
Current.setPointer(Current.getPointer() + EntitySize);
return *this;
}
Elf_Sym_Iter operator++(int) {
Elf_Sym_Iter Tmp = *this;
++*this;
return Tmp;
}
Elf_Sym_Iter operator+(difference_type Dist) {
assert(Current.getPointer() &&
"Attempted to increment an invalid iterator!");
Current.setPointer(Current.getPointer() + EntitySize * Dist);
return *this;
}
difference_type operator-(const Elf_Sym_Iter &Other) const {
assert(EntitySize == Other.EntitySize &&
"Subtracting iterators of different EntitySize!");
return (Current.getPointer() - Other.Current.getPointer()) / EntitySize;
}
const char *get() const { return Current.getPointer(); }
bool isDynamic() const { return Current.getInt(); }
uintX_t getEntSize() const { return EntitySize; }
private:
uintX_t EntitySize;
PointerIntPair<const char *, 1, bool,
ArchivePointerTypeTraits<const char> > Current;
};
private:
typedef SmallVector<const Elf_Shdr *, 2> Sections_t;
typedef DenseMap<unsigned, unsigned> IndexMap_t;
StringRef Buf;
const uint8_t *base() const {
return reinterpret_cast<const uint8_t *>(Buf.data());
}
const Elf_Ehdr *Header;
const Elf_Shdr *SectionHeaderTable;
const Elf_Shdr *dot_shstrtab_sec; // Section header string table.
const Elf_Shdr *dot_strtab_sec; // Symbol header string table.
const Elf_Shdr *dot_symtab_sec; // Symbol table section.
const Elf_Shdr *SymbolTableSectionHeaderIndex;
DenseMap<const Elf_Sym *, ELF::Elf64_Word> ExtendedSymbolTable;
const Elf_Shdr *dot_gnu_version_sec; // .gnu.version
const Elf_Shdr *dot_gnu_version_r_sec; // .gnu.version_r
const Elf_Shdr *dot_gnu_version_d_sec; // .gnu.version_d
/// \brief Represents a region described by entries in the .dynamic table.
struct DynRegionInfo {
DynRegionInfo() : Addr(nullptr), Size(0), EntSize(0) {}
/// \brief Address in current address space.
const void *Addr;
/// \brief Size in bytes of the region.
uintX_t Size;
/// \brief Size of each entity in the region.
uintX_t EntSize;
};
DynRegionInfo DynamicRegion;
DynRegionInfo DynHashRegion;
DynRegionInfo DynStrRegion;
DynRegionInfo DynSymRegion;
// Pointer to SONAME entry in dynamic string table
// This is set the first time getLoadName is called.
mutable const char *dt_soname;
// Records for each version index the corresponding Verdef or Vernaux entry.
// This is filled the first time LoadVersionMap() is called.
class VersionMapEntry : public PointerIntPair<const void*, 1> {
public:
// If the integer is 0, this is an Elf_Verdef*.
// If the integer is 1, this is an Elf_Vernaux*.
VersionMapEntry() : PointerIntPair<const void*, 1>(nullptr, 0) { }
VersionMapEntry(const Elf_Verdef *verdef)
: PointerIntPair<const void*, 1>(verdef, 0) { }
VersionMapEntry(const Elf_Vernaux *vernaux)
: PointerIntPair<const void*, 1>(vernaux, 1) { }
bool isNull() const { return getPointer() == nullptr; }
bool isVerdef() const { return !isNull() && getInt() == 0; }
bool isVernaux() const { return !isNull() && getInt() == 1; }
const Elf_Verdef *getVerdef() const {
return isVerdef() ? (const Elf_Verdef*)getPointer() : nullptr;
}
const Elf_Vernaux *getVernaux() const {
return isVernaux() ? (const Elf_Vernaux*)getPointer() : nullptr;
}
};
mutable SmallVector<VersionMapEntry, 16> VersionMap;
void LoadVersionDefs(const Elf_Shdr *sec) const;
void LoadVersionNeeds(const Elf_Shdr *ec) const;
void LoadVersionMap() const;
public:
template<typename T>
const T *getEntry(uint32_t Section, uint32_t Entry) const;
template <typename T>
const T *getEntry(const Elf_Shdr *Section, uint32_t Entry) const;
const char *getString(uint32_t section, uint32_t offset) const;
const char *getString(const Elf_Shdr *section, uint32_t offset) const;
const char *getDynamicString(uintX_t Offset) const;
ErrorOr<StringRef> getSymbolVersion(const Elf_Shdr *section,
const Elf_Sym *Symb,
bool &IsDefault) const;
void VerifyStrTab(const Elf_Shdr *sh) const;
StringRef getRelocationTypeName(uint32_t Type) const;
void getRelocationTypeName(uint32_t Type,
SmallVectorImpl<char> &Result) const;
/// \brief Get the symbol table section and symbol for a given relocation.
template <class RelT>
std::pair<const Elf_Shdr *, const Elf_Sym *>
getRelocationSymbol(const Elf_Shdr *RelSec, const RelT *Rel) const;
ELFFile(StringRef Object, std::error_code &EC);
bool isMipsELF64() const {
return Header->e_machine == ELF::EM_MIPS &&
Header->getFileClass() == ELF::ELFCLASS64;
}
bool isMips64EL() const {
return Header->e_machine == ELF::EM_MIPS &&
Header->getFileClass() == ELF::ELFCLASS64 &&
Header->getDataEncoding() == ELF::ELFDATA2LSB;
}
Elf_Shdr_Iter begin_sections() const;
Elf_Shdr_Iter end_sections() const;
Elf_Shdr_Range sections() const {
return make_range(begin_sections(), end_sections());
}
Elf_Sym_Iter begin_symbols() const;
Elf_Sym_Iter end_symbols() const;
Elf_Dyn_Iter begin_dynamic_table() const;
/// \param NULLEnd use one past the first DT_NULL entry as the end instead of
/// the section size.
Elf_Dyn_Iter end_dynamic_table(bool NULLEnd = false) const;
Elf_Dyn_Range dynamic_table(bool NULLEnd = false) const {
return make_range(begin_dynamic_table(), end_dynamic_table(NULLEnd));
}
Elf_Sym_Iter begin_dynamic_symbols() const {
if (DynSymRegion.Addr)
return Elf_Sym_Iter(DynSymRegion.EntSize, (const char *)DynSymRegion.Addr,
true);
return Elf_Sym_Iter(0, nullptr, true);
}
Elf_Sym_Iter end_dynamic_symbols() const {
if (DynSymRegion.Addr)
return Elf_Sym_Iter(DynSymRegion.EntSize,
(const char *)DynSymRegion.Addr + DynSymRegion.Size,
true);
return Elf_Sym_Iter(0, nullptr, true);
}
Elf_Rela_Iter begin_rela(const Elf_Shdr *sec) const {
return Elf_Rela_Iter(sec->sh_entsize,
(const char *)(base() + sec->sh_offset));
}
Elf_Rela_Iter end_rela(const Elf_Shdr *sec) const {
return Elf_Rela_Iter(
sec->sh_entsize,
(const char *)(base() + sec->sh_offset + sec->sh_size));
}
Elf_Rel_Iter begin_rel(const Elf_Shdr *sec) const {
return Elf_Rel_Iter(sec->sh_entsize,
(const char *)(base() + sec->sh_offset));
}
Elf_Rel_Iter end_rel(const Elf_Shdr *sec) const {
return Elf_Rel_Iter(sec->sh_entsize,
(const char *)(base() + sec->sh_offset + sec->sh_size));
}
/// \brief Iterate over program header table.
typedef ELFEntityIterator<const Elf_Phdr> Elf_Phdr_Iter;
Elf_Phdr_Iter begin_program_headers() const {
return Elf_Phdr_Iter(Header->e_phentsize,
(const char*)base() + Header->e_phoff);
}
Elf_Phdr_Iter end_program_headers() const {
return Elf_Phdr_Iter(Header->e_phentsize,
(const char*)base() +
Header->e_phoff +
(Header->e_phnum * Header->e_phentsize));
}
uint64_t getNumSections() const;
uintX_t getStringTableIndex() const;
ELF::Elf64_Word getSymbolTableIndex(const Elf_Sym *symb) const;
const Elf_Ehdr *getHeader() const { return Header; }
const Elf_Shdr *getSection(const Elf_Sym *symb) const;
const Elf_Shdr *getSection(uint32_t Index) const;
const Elf_Sym *getSymbol(uint32_t index) const;
ErrorOr<StringRef> getSymbolName(Elf_Sym_Iter Sym) const;
/// \brief Get the name of \p Symb.
/// \param SymTab The symbol table section \p Symb is contained in.
/// \param Symb The symbol to get the name of.
///
/// \p SymTab is used to lookup the string table to use to get the symbol's
/// name.
ErrorOr<StringRef> getSymbolName(const Elf_Shdr *SymTab,
const Elf_Sym *Symb) const;
ErrorOr<StringRef> getSectionName(const Elf_Shdr *Section) const;
uint64_t getSymbolIndex(const Elf_Sym *sym) const;
ErrorOr<ArrayRef<uint8_t> > getSectionContents(const Elf_Shdr *Sec) const;
StringRef getLoadName() const;
};
// Use an alignment of 2 for the typedefs since that is the worst case for
// ELF files in archives.
typedef ELFFile<ELFType<support::little, 2, false> > ELF32LEFile;
typedef ELFFile<ELFType<support::little, 2, true> > ELF64LEFile;
typedef ELFFile<ELFType<support::big, 2, false> > ELF32BEFile;
typedef ELFFile<ELFType<support::big, 2, true> > ELF64BEFile;
// Iterate through the version definitions, and place each Elf_Verdef
// in the VersionMap according to its index.
template <class ELFT>
void ELFFile<ELFT>::LoadVersionDefs(const Elf_Shdr *sec) const {
unsigned vd_size = sec->sh_size; // Size of section in bytes
unsigned vd_count = sec->sh_info; // Number of Verdef entries
const char *sec_start = (const char*)base() + sec->sh_offset;
const char *sec_end = sec_start + vd_size;
// The first Verdef entry is at the start of the section.
const char *p = sec_start;
for (unsigned i = 0; i < vd_count; i++) {
if (p + sizeof(Elf_Verdef) > sec_end)
report_fatal_error("Section ended unexpectedly while scanning "
"version definitions.");
const Elf_Verdef *vd = reinterpret_cast<const Elf_Verdef *>(p);
if (vd->vd_version != ELF::VER_DEF_CURRENT)
report_fatal_error("Unexpected verdef version");
size_t index = vd->vd_ndx & ELF::VERSYM_VERSION;
if (index >= VersionMap.size())
VersionMap.resize(index + 1);
VersionMap[index] = VersionMapEntry(vd);
p += vd->vd_next;
}
}
// Iterate through the versions needed section, and place each Elf_Vernaux
// in the VersionMap according to its index.
template <class ELFT>
void ELFFile<ELFT>::LoadVersionNeeds(const Elf_Shdr *sec) const {
unsigned vn_size = sec->sh_size; // Size of section in bytes
unsigned vn_count = sec->sh_info; // Number of Verneed entries
const char *sec_start = (const char *)base() + sec->sh_offset;
const char *sec_end = sec_start + vn_size;
// The first Verneed entry is at the start of the section.
const char *p = sec_start;
for (unsigned i = 0; i < vn_count; i++) {
if (p + sizeof(Elf_Verneed) > sec_end)
report_fatal_error("Section ended unexpectedly while scanning "
"version needed records.");
const Elf_Verneed *vn = reinterpret_cast<const Elf_Verneed *>(p);
if (vn->vn_version != ELF::VER_NEED_CURRENT)
report_fatal_error("Unexpected verneed version");
// Iterate through the Vernaux entries
const char *paux = p + vn->vn_aux;
for (unsigned j = 0; j < vn->vn_cnt; j++) {
if (paux + sizeof(Elf_Vernaux) > sec_end)
report_fatal_error("Section ended unexpected while scanning auxiliary "
"version needed records.");
const Elf_Vernaux *vna = reinterpret_cast<const Elf_Vernaux *>(paux);
size_t index = vna->vna_other & ELF::VERSYM_VERSION;
if (index >= VersionMap.size())
VersionMap.resize(index + 1);
VersionMap[index] = VersionMapEntry(vna);
paux += vna->vna_next;
}
p += vn->vn_next;
}
}
template <class ELFT>
void ELFFile<ELFT>::LoadVersionMap() const {
// If there is no dynamic symtab or version table, there is nothing to do.
if (!DynSymRegion.Addr || !dot_gnu_version_sec)
return;
// Has the VersionMap already been loaded?
if (VersionMap.size() > 0)
return;
// The first two version indexes are reserved.
// Index 0 is LOCAL, index 1 is GLOBAL.
VersionMap.push_back(VersionMapEntry());
VersionMap.push_back(VersionMapEntry());
if (dot_gnu_version_d_sec)
LoadVersionDefs(dot_gnu_version_d_sec);
if (dot_gnu_version_r_sec)
LoadVersionNeeds(dot_gnu_version_r_sec);
}
template <class ELFT>
ELF::Elf64_Word ELFFile<ELFT>::getSymbolTableIndex(const Elf_Sym *symb) const {
if (symb->st_shndx == ELF::SHN_XINDEX)
return ExtendedSymbolTable.lookup(symb);
return symb->st_shndx;
}
template <class ELFT>
const typename ELFFile<ELFT>::Elf_Shdr *
ELFFile<ELFT>::getSection(const Elf_Sym *symb) const {
if (symb->st_shndx == ELF::SHN_XINDEX)
return getSection(ExtendedSymbolTable.lookup(symb));
if (symb->st_shndx >= ELF::SHN_LORESERVE)
return nullptr;
return getSection(symb->st_shndx);
}
template <class ELFT>
const typename ELFFile<ELFT>::Elf_Sym *
ELFFile<ELFT>::getSymbol(uint32_t Index) const {
return &*(begin_symbols() + Index);
}
template <class ELFT>
ErrorOr<ArrayRef<uint8_t> >
ELFFile<ELFT>::getSectionContents(const Elf_Shdr *Sec) const {
if (Sec->sh_offset + Sec->sh_size > Buf.size())
return object_error::parse_failed;
const uint8_t *Start = base() + Sec->sh_offset;
return makeArrayRef(Start, Sec->sh_size);
}
template <class ELFT>
StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
return getELFRelocationTypeName(Header->e_machine, Type);
}
template <class ELFT>
void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
SmallVectorImpl<char> &Result) const {
if (!isMipsELF64()) {
StringRef Name = getRelocationTypeName(Type);
Result.append(Name.begin(), Name.end());
} else {
// The Mips N64 ABI allows up to three operations to be specified per
// relocation record. Unfortunately there's no easy way to test for the
// presence of N64 ELFs as they have no special flag that identifies them
// as being N64. We can safely assume at the moment that all Mips
// ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
// information to disambiguate between old vs new ABIs.
uint8_t Type1 = (Type >> 0) & 0xFF;
uint8_t Type2 = (Type >> 8) & 0xFF;
uint8_t Type3 = (Type >> 16) & 0xFF;
// Concat all three relocation type names.
StringRef Name = getRelocationTypeName(Type1);
Result.append(Name.begin(), Name.end());
Name = getRelocationTypeName(Type2);
Result.append(1, '/');
Result.append(Name.begin(), Name.end());
Name = getRelocationTypeName(Type3);
Result.append(1, '/');
Result.append(Name.begin(), Name.end());
}
}
template <class ELFT>
template <class RelT>
std::pair<const typename ELFFile<ELFT>::Elf_Shdr *,
const typename ELFFile<ELFT>::Elf_Sym *>
ELFFile<ELFT>::getRelocationSymbol(const Elf_Shdr *Sec, const RelT *Rel) const {
if (!Sec->sh_link)
return std::make_pair(nullptr, nullptr);
const Elf_Shdr *SymTable = getSection(Sec->sh_link);
return std::make_pair(
SymTable, getEntry<Elf_Sym>(SymTable, Rel->getSymbol(isMips64EL())));
}
// Verify that the last byte in the string table in a null.
template <class ELFT>
void ELFFile<ELFT>::VerifyStrTab(const Elf_Shdr *sh) const {
const char *strtab = (const char *)base() + sh->sh_offset;
if (strtab[sh->sh_size - 1] != 0)
// FIXME: Proper error handling.
report_fatal_error("String table must end with a null terminator!");
}
template <class ELFT>
uint64_t ELFFile<ELFT>::getNumSections() const {
assert(Header && "Header not initialized!");
if (Header->e_shnum == ELF::SHN_UNDEF && Header->e_shoff > 0) {
assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
return SectionHeaderTable->sh_size;
}
return Header->e_shnum;
}
template <class ELFT>
typename ELFFile<ELFT>::uintX_t ELFFile<ELFT>::getStringTableIndex() const {
if (Header->e_shnum == ELF::SHN_UNDEF) {
if (Header->e_shstrndx == ELF::SHN_HIRESERVE)
return SectionHeaderTable->sh_link;
if (Header->e_shstrndx >= getNumSections())
return 0;
}
return Header->e_shstrndx;
}
template <class ELFT>
ELFFile<ELFT>::ELFFile(StringRef Object, std::error_code &EC)
: Buf(Object), SectionHeaderTable(nullptr), dot_shstrtab_sec(nullptr),
dot_strtab_sec(nullptr), dot_symtab_sec(nullptr),
SymbolTableSectionHeaderIndex(nullptr), dot_gnu_version_sec(nullptr),
dot_gnu_version_r_sec(nullptr), dot_gnu_version_d_sec(nullptr),
dt_soname(nullptr) {
const uint64_t FileSize = Buf.size();
if (sizeof(Elf_Ehdr) > FileSize) {
// File too short!
EC = object_error::parse_failed;
return;
}
Header = reinterpret_cast<const Elf_Ehdr *>(base());
if (Header->e_shoff == 0)
return;
const uint64_t SectionTableOffset = Header->e_shoff;
if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize) {
// Section header table goes past end of file!
EC = object_error::parse_failed;
return;
}
// The getNumSections() call below depends on SectionHeaderTable being set.
SectionHeaderTable =
reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
const uint64_t SectionTableSize = getNumSections() * Header->e_shentsize;
if (SectionTableOffset + SectionTableSize > FileSize) {
// Section table goes past end of file!
EC = object_error::parse_failed;
return;
}
// Scan sections for special sections.
for (const Elf_Shdr &Sec : sections()) {
switch (Sec.sh_type) {
case ELF::SHT_SYMTAB_SHNDX:
if (SymbolTableSectionHeaderIndex) {
// More than one .symtab_shndx!
EC = object_error::parse_failed;
return;
}
SymbolTableSectionHeaderIndex = &Sec;
break;
case ELF::SHT_SYMTAB:
if (dot_symtab_sec) {
// More than one .symtab!
EC = object_error::parse_failed;
return;
}
dot_symtab_sec = &Sec;
dot_strtab_sec = getSection(Sec.sh_link);
break;
case ELF::SHT_DYNSYM: {
if (DynSymRegion.Addr) {
// More than one .dynsym!
EC = object_error::parse_failed;
return;
}
DynSymRegion.Addr = base() + Sec.sh_offset;
DynSymRegion.Size = Sec.sh_size;
DynSymRegion.EntSize = Sec.sh_entsize;
const Elf_Shdr *DynStr = getSection(Sec.sh_link);
DynStrRegion.Addr = base() + DynStr->sh_offset;
DynStrRegion.Size = DynStr->sh_size;
DynStrRegion.EntSize = DynStr->sh_entsize;
break;
}
case ELF::SHT_DYNAMIC:
if (DynamicRegion.Addr) {
// More than one .dynamic!
EC = object_error::parse_failed;
return;
}
DynamicRegion.Addr = base() + Sec.sh_offset;
DynamicRegion.Size = Sec.sh_size;
DynamicRegion.EntSize = Sec.sh_entsize;
break;
case ELF::SHT_GNU_versym:
if (dot_gnu_version_sec != nullptr) {
// More than one .gnu.version section!
EC = object_error::parse_failed;
return;
}
dot_gnu_version_sec = &Sec;
break;
case ELF::SHT_GNU_verdef:
if (dot_gnu_version_d_sec != nullptr) {
// More than one .gnu.version_d section!
EC = object_error::parse_failed;
return;
}
dot_gnu_version_d_sec = &Sec;
break;
case ELF::SHT_GNU_verneed:
if (dot_gnu_version_r_sec != nullptr) {
// More than one .gnu.version_r section!
EC = object_error::parse_failed;
return;
}
dot_gnu_version_r_sec = &Sec;
break;
}
}
// Get string table sections.
dot_shstrtab_sec = getSection(getStringTableIndex());
if (dot_shstrtab_sec) {
// Verify that the last byte in the string table in a null.
VerifyStrTab(dot_shstrtab_sec);
}
// Build symbol name side-mapping if there is one.
if (SymbolTableSectionHeaderIndex) {
const Elf_Word *ShndxTable = reinterpret_cast<const Elf_Word*>(base() +
SymbolTableSectionHeaderIndex->sh_offset);
for (Elf_Sym_Iter SI = begin_symbols(), SE = end_symbols(); SI != SE;
++SI) {
if (*ShndxTable != ELF::SHN_UNDEF)
ExtendedSymbolTable[&*SI] = *ShndxTable;
++ShndxTable;
}
}
// Scan program headers.
for (Elf_Phdr_Iter PhdrI = begin_program_headers(),
PhdrE = end_program_headers();
PhdrI != PhdrE; ++PhdrI) {
if (PhdrI->p_type == ELF::PT_DYNAMIC) {
DynamicRegion.Addr = base() + PhdrI->p_offset;
DynamicRegion.Size = PhdrI->p_filesz;
DynamicRegion.EntSize = sizeof(Elf_Dyn);
break;
}
}
EC = std::error_code();
}
// Get the symbol table index in the symtab section given a symbol
template <class ELFT>
uint64_t ELFFile<ELFT>::getSymbolIndex(const Elf_Sym *Sym) const {
uintptr_t SymLoc = uintptr_t(Sym);
uintptr_t SymTabLoc = uintptr_t(base() + dot_symtab_sec->sh_offset);
assert(SymLoc > SymTabLoc && "Symbol not in symbol table!");
uint64_t SymOffset = SymLoc - SymTabLoc;
assert(SymOffset % dot_symtab_sec->sh_entsize == 0 &&
"Symbol not multiple of symbol size!");
return SymOffset / dot_symtab_sec->sh_entsize;
}
template <class ELFT>
typename ELFFile<ELFT>::Elf_Shdr_Iter ELFFile<ELFT>::begin_sections() const {
return Elf_Shdr_Iter(Header->e_shentsize,
(const char *)base() + Header->e_shoff);
}
template <class ELFT>
typename ELFFile<ELFT>::Elf_Shdr_Iter ELFFile<ELFT>::end_sections() const {
return Elf_Shdr_Iter(Header->e_shentsize,
(const char *)base() + Header->e_shoff +
(getNumSections() * Header->e_shentsize));
}
template <class ELFT>
typename ELFFile<ELFT>::Elf_Sym_Iter ELFFile<ELFT>::begin_symbols() const {
if (!dot_symtab_sec)
return Elf_Sym_Iter(0, nullptr, false);
return Elf_Sym_Iter(dot_symtab_sec->sh_entsize,
(const char *)base() + dot_symtab_sec->sh_offset, false);
}
template <class ELFT>
typename ELFFile<ELFT>::Elf_Sym_Iter ELFFile<ELFT>::end_symbols() const {
if (!dot_symtab_sec)
return Elf_Sym_Iter(0, nullptr, false);
return Elf_Sym_Iter(dot_symtab_sec->sh_entsize,
(const char *)base() + dot_symtab_sec->sh_offset +
dot_symtab_sec->sh_size,
false);
}
template <class ELFT>
typename ELFFile<ELFT>::Elf_Dyn_Iter
ELFFile<ELFT>::begin_dynamic_table() const {
if (DynamicRegion.Addr)
return Elf_Dyn_Iter(DynamicRegion.EntSize,
(const char *)DynamicRegion.Addr);
return Elf_Dyn_Iter(0, nullptr);
}
template <class ELFT>
typename ELFFile<ELFT>::Elf_Dyn_Iter
ELFFile<ELFT>::end_dynamic_table(bool NULLEnd) const {
if (!DynamicRegion.Addr)
return Elf_Dyn_Iter(0, nullptr);
Elf_Dyn_Iter Ret(DynamicRegion.EntSize,
(const char *)DynamicRegion.Addr + DynamicRegion.Size);
if (NULLEnd) {
Elf_Dyn_Iter Start = begin_dynamic_table();
while (Start != Ret && Start->getTag() != ELF::DT_NULL)
++Start;
// Include the DT_NULL.
if (Start != Ret)
++Start;
Ret = Start;
}
return Ret;
}
template <class ELFT>
StringRef ELFFile<ELFT>::getLoadName() const {
if (!dt_soname) {
dt_soname = "";
// Find the DT_SONAME entry
for (const auto &Entry : dynamic_table())
if (Entry.getTag() == ELF::DT_SONAME) {
dt_soname = getDynamicString(Entry.getVal());
break;
}
}
return dt_soname;
}
template <class ELFT>
template <typename T>
const T *ELFFile<ELFT>::getEntry(uint32_t Section, uint32_t Entry) const {
return getEntry<T>(getSection(Section), Entry);
}
template <class ELFT>
template <typename T>
const T *ELFFile<ELFT>::getEntry(const Elf_Shdr *Section,
uint32_t Entry) const {
return reinterpret_cast<const T *>(base() + Section->sh_offset +
(Entry * Section->sh_entsize));
}
template <class ELFT>
const typename ELFFile<ELFT>::Elf_Shdr *
ELFFile<ELFT>::getSection(uint32_t index) const {
if (index == 0)
return nullptr;
if (!SectionHeaderTable || index >= getNumSections())
// FIXME: Proper error handling.
report_fatal_error("Invalid section index!");
return reinterpret_cast<const Elf_Shdr *>(
reinterpret_cast<const char *>(SectionHeaderTable)
+ (index * Header->e_shentsize));
}
template <class ELFT>
const char *ELFFile<ELFT>::getString(uint32_t section,
ELF::Elf32_Word offset) const {
return getString(getSection(section), offset);
}
template <class ELFT>
const char *ELFFile<ELFT>::getString(const Elf_Shdr *section,
ELF::Elf32_Word offset) const {
assert(section && section->sh_type == ELF::SHT_STRTAB && "Invalid section!");
if (offset >= section->sh_size)
// FIXME: Proper error handling.
report_fatal_error("Symbol name offset outside of string table!");
return (const char *)base() + section->sh_offset + offset;
}
template <class ELFT>
const char *ELFFile<ELFT>::getDynamicString(uintX_t Offset) const {
if (!DynStrRegion.Addr || Offset >= DynStrRegion.Size)
return nullptr;
return (const char *)DynStrRegion.Addr + Offset;
}
template <class ELFT>
ErrorOr<StringRef> ELFFile<ELFT>::getSymbolName(Elf_Sym_Iter Sym) const {
if (!Sym.isDynamic())
return getSymbolName(dot_symtab_sec, &*Sym);
if (!DynStrRegion.Addr || Sym->st_name >= DynStrRegion.Size)
return object_error::parse_failed;
return StringRef(getDynamicString(Sym->st_name));
}
template <class ELFT>
ErrorOr<StringRef> ELFFile<ELFT>::getSymbolName(const Elf_Shdr *Section,
const Elf_Sym *Symb) const {
if (Symb->st_name == 0) {
const Elf_Shdr *ContainingSec = getSection(Symb);
if (ContainingSec)
return getSectionName(ContainingSec);
}
const Elf_Shdr *StrTab = getSection(Section->sh_link);
if (Symb->st_name >= StrTab->sh_size)
return object_error::parse_failed;
return StringRef(getString(StrTab, Symb->st_name));
}
template <class ELFT>
ErrorOr<StringRef>
ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section) const {
if (Section->sh_name >= dot_shstrtab_sec->sh_size)
return object_error::parse_failed;
return StringRef(getString(dot_shstrtab_sec, Section->sh_name));
}
template <class ELFT>
ErrorOr<StringRef> ELFFile<ELFT>::getSymbolVersion(const Elf_Shdr *section,
const Elf_Sym *symb,
bool &IsDefault) const {
// Handle non-dynamic symbols.
if (section != DynSymRegion.Addr && section != nullptr) {
// Non-dynamic symbols can have versions in their names
// A name of the form 'foo@V1' indicates version 'V1', non-default.
// A name of the form 'foo@@V2' indicates version 'V2', default version.
ErrorOr<StringRef> SymName = getSymbolName(section, symb);
if (!SymName)
return SymName;
StringRef Name = *SymName;
size_t atpos = Name.find('@');
if (atpos == StringRef::npos) {
IsDefault = false;
return StringRef("");
}
++atpos;
if (atpos < Name.size() && Name[atpos] == '@') {
IsDefault = true;
++atpos;
} else {
IsDefault = false;
}
return Name.substr(atpos);
}
// This is a dynamic symbol. Look in the GNU symbol version table.
if (!dot_gnu_version_sec) {
// No version table.
IsDefault = false;
return StringRef("");
}
// Determine the position in the symbol table of this entry.
size_t entry_index = ((const char *)symb - (const char *)DynSymRegion.Addr) /
DynSymRegion.EntSize;
// Get the corresponding version index entry
const Elf_Versym *vs = getEntry<Elf_Versym>(dot_gnu_version_sec, entry_index);
size_t version_index = vs->vs_index & ELF::VERSYM_VERSION;
// Special markers for unversioned symbols.
if (version_index == ELF::VER_NDX_LOCAL ||
version_index == ELF::VER_NDX_GLOBAL) {
IsDefault = false;
return StringRef("");
}
// Lookup this symbol in the version table
LoadVersionMap();
if (version_index >= VersionMap.size() || VersionMap[version_index].isNull())
return object_error::parse_failed;
const VersionMapEntry &entry = VersionMap[version_index];
// Get the version name string
size_t name_offset;
if (entry.isVerdef()) {
// The first Verdaux entry holds the name.
name_offset = entry.getVerdef()->getAux()->vda_name;
} else {
name_offset = entry.getVernaux()->vna_name;
}
// Set IsDefault
if (entry.isVerdef()) {
IsDefault = !(vs->vs_index & ELF::VERSYM_HIDDEN);
} else {
IsDefault = false;
}
if (name_offset >= DynStrRegion.Size)
return object_error::parse_failed;
return StringRef(getDynamicString(name_offset));
}
/// This function returns the hash value for a symbol in the .dynsym section
/// Name of the API remains consistent as specified in the libelf
/// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash
static inline unsigned elf_hash(StringRef &symbolName) {
unsigned h = 0, g;
for (unsigned i = 0, j = symbolName.size(); i < j; i++) {
h = (h << 4) + symbolName[i];
g = h & 0xf0000000L;
if (g != 0)
h ^= g >> 24;
h &= ~g;
}
return h;
}
} // end namespace object
} // end namespace llvm
#endif
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