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llvm-for-llvmta/include/llvm/Object/ELF.h

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2022-04-25 10:02:23 +02:00
//===- ELF.h - ELF object file implementation -------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// 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/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/Object/ELFTypes.h"
#include "llvm/Object/Error.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Error.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <limits>
#include <utility>
namespace llvm {
namespace object {
struct VerdAux {
unsigned Offset;
std::string Name;
};
struct VerDef {
unsigned Offset;
unsigned Version;
unsigned Flags;
unsigned Ndx;
unsigned Cnt;
unsigned Hash;
std::string Name;
std::vector<VerdAux> AuxV;
};
struct VernAux {
unsigned Hash;
unsigned Flags;
unsigned Other;
unsigned Offset;
std::string Name;
};
struct VerNeed {
unsigned Version;
unsigned Cnt;
unsigned Offset;
std::string File;
std::vector<VernAux> AuxV;
};
struct VersionEntry {
std::string Name;
bool IsVerDef;
};
StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type);
uint32_t getELFRelativeRelocationType(uint32_t Machine);
StringRef getELFSectionTypeName(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]);
}
static inline Error createError(const Twine &Err) {
return make_error<StringError>(Err, object_error::parse_failed);
}
enum PPCInstrMasks : uint64_t {
PADDI_R12_NO_DISP = 0x0610000039800000,
PLD_R12_NO_DISP = 0x04100000E5800000,
MTCTR_R12 = 0x7D8903A6,
BCTR = 0x4E800420,
};
template <class ELFT> class ELFFile;
template <class T> struct DataRegion {
// This constructor is used when we know the start and the size of a data
// region. We assume that Arr does not go past the end of the file.
DataRegion(ArrayRef<T> Arr) : First(Arr.data()), Size(Arr.size()) {}
// Sometimes we only know the start of a data region. We still don't want to
// read past the end of the file, so we provide the end of a buffer.
DataRegion(const T *Data, const uint8_t *BufferEnd)
: First(Data), BufEnd(BufferEnd) {}
Expected<T> operator[](uint64_t N) {
assert(Size || BufEnd);
if (Size) {
if (N >= *Size)
return createError(
"the index is greater than or equal to the number of entries (" +
Twine(*Size) + ")");
} else {
const uint8_t *EntryStart = (const uint8_t *)First + N * sizeof(T);
if (EntryStart + sizeof(T) > BufEnd)
return createError("can't read past the end of the file");
}
return *(First + N);
}
const T *First;
Optional<uint64_t> Size = None;
const uint8_t *BufEnd = nullptr;
};
template <class ELFT>
std::string getSecIndexForError(const ELFFile<ELFT> &Obj,
const typename ELFT::Shdr &Sec) {
auto TableOrErr = Obj.sections();
if (TableOrErr)
return "[index " + std::to_string(&Sec - &TableOrErr->front()) + "]";
// To make this helper be more convenient for error reporting purposes we
// drop the error. But really it should never be triggered. Before this point,
// our code should have called 'sections()' and reported a proper error on
// failure.
llvm::consumeError(TableOrErr.takeError());
return "[unknown index]";
}
template <class ELFT>
static std::string describe(const ELFFile<ELFT> &Obj,
const typename ELFT::Shdr &Sec) {
unsigned SecNdx = &Sec - &cantFail(Obj.sections()).front();
return (object::getELFSectionTypeName(Obj.getHeader().e_machine,
Sec.sh_type) +
" section with index " + Twine(SecNdx))
.str();
}
template <class ELFT>
std::string getPhdrIndexForError(const ELFFile<ELFT> &Obj,
const typename ELFT::Phdr &Phdr) {
auto Headers = Obj.program_headers();
if (Headers)
return ("[index " + Twine(&Phdr - &Headers->front()) + "]").str();
// See comment in the getSecIndexForError() above.
llvm::consumeError(Headers.takeError());
return "[unknown index]";
}
static inline Error defaultWarningHandler(const Twine &Msg) {
return createError(Msg);
}
template <class ELFT>
class ELFFile {
public:
LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
// This is a callback that can be passed to a number of functions.
// It can be used to ignore non-critical errors (warnings), which is
// useful for dumpers, like llvm-readobj.
// It accepts a warning message string and returns a success
// when the warning should be ignored or an error otherwise.
using WarningHandler = llvm::function_ref<Error(const Twine &Msg)>;
const uint8_t *base() const { return Buf.bytes_begin(); }
const uint8_t *end() const { return base() + getBufSize(); }
size_t getBufSize() const { return Buf.size(); }
private:
StringRef Buf;
ELFFile(StringRef Object);
public:
const Elf_Ehdr &getHeader() const {
return *reinterpret_cast<const Elf_Ehdr *>(base());
}
template <typename T>
Expected<const T *> getEntry(uint32_t Section, uint32_t Entry) const;
template <typename T>
Expected<const T *> getEntry(const Elf_Shdr &Section, uint32_t Entry) const;
Expected<std::vector<VerDef>>
getVersionDefinitions(const Elf_Shdr &Sec) const;
Expected<std::vector<VerNeed>> getVersionDependencies(
const Elf_Shdr &Sec,
WarningHandler WarnHandler = &defaultWarningHandler) const;
Expected<StringRef>
getSymbolVersionByIndex(uint32_t SymbolVersionIndex, bool &IsDefault,
SmallVector<Optional<VersionEntry>, 0> &VersionMap,
Optional<bool> IsSymHidden) const;
Expected<StringRef>
getStringTable(const Elf_Shdr &Section,
WarningHandler WarnHandler = &defaultWarningHandler) const;
Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const;
Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section,
Elf_Shdr_Range Sections) const;
Expected<StringRef> getLinkAsStrtab(const typename ELFT::Shdr &Sec) const;
Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section) const;
Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section,
Elf_Shdr_Range Sections) const;
Expected<uint64_t> getDynSymtabSize() const;
StringRef getRelocationTypeName(uint32_t Type) const;
void getRelocationTypeName(uint32_t Type,
SmallVectorImpl<char> &Result) const;
uint32_t getRelativeRelocationType() const;
std::string getDynamicTagAsString(unsigned Arch, uint64_t Type) const;
std::string getDynamicTagAsString(uint64_t Type) const;
/// Get the symbol for a given relocation.
Expected<const Elf_Sym *> getRelocationSymbol(const Elf_Rel &Rel,
const Elf_Shdr *SymTab) const;
Expected<SmallVector<Optional<VersionEntry>, 0>>
loadVersionMap(const Elf_Shdr *VerNeedSec, const Elf_Shdr *VerDefSec) const;
static Expected<ELFFile> create(StringRef Object);
bool isLE() const {
return getHeader().getDataEncoding() == ELF::ELFDATA2LSB;
}
bool isMipsELF64() const {
return getHeader().e_machine == ELF::EM_MIPS &&
getHeader().getFileClass() == ELF::ELFCLASS64;
}
bool isMips64EL() const { return isMipsELF64() && isLE(); }
Expected<Elf_Shdr_Range> sections() const;
Expected<Elf_Dyn_Range> dynamicEntries() const;
Expected<const uint8_t *>
toMappedAddr(uint64_t VAddr,
WarningHandler WarnHandler = &defaultWarningHandler) const;
Expected<Elf_Sym_Range> symbols(const Elf_Shdr *Sec) const {
if (!Sec)
return makeArrayRef<Elf_Sym>(nullptr, nullptr);
return getSectionContentsAsArray<Elf_Sym>(*Sec);
}
Expected<Elf_Rela_Range> relas(const Elf_Shdr &Sec) const {
return getSectionContentsAsArray<Elf_Rela>(Sec);
}
Expected<Elf_Rel_Range> rels(const Elf_Shdr &Sec) const {
return getSectionContentsAsArray<Elf_Rel>(Sec);
}
Expected<Elf_Relr_Range> relrs(const Elf_Shdr &Sec) const {
return getSectionContentsAsArray<Elf_Relr>(Sec);
}
std::vector<Elf_Rel> decode_relrs(Elf_Relr_Range relrs) const;
Expected<std::vector<Elf_Rela>> android_relas(const Elf_Shdr &Sec) const;
/// Iterate over program header table.
Expected<Elf_Phdr_Range> program_headers() const {
if (getHeader().e_phnum && getHeader().e_phentsize != sizeof(Elf_Phdr))
return createError("invalid e_phentsize: " +
Twine(getHeader().e_phentsize));
uint64_t HeadersSize =
(uint64_t)getHeader().e_phnum * getHeader().e_phentsize;
uint64_t PhOff = getHeader().e_phoff;
if (PhOff + HeadersSize < PhOff || PhOff + HeadersSize > getBufSize())
return createError("program headers are longer than binary of size " +
Twine(getBufSize()) + ": e_phoff = 0x" +
Twine::utohexstr(getHeader().e_phoff) +
", e_phnum = " + Twine(getHeader().e_phnum) +
", e_phentsize = " + Twine(getHeader().e_phentsize));
auto *Begin = reinterpret_cast<const Elf_Phdr *>(base() + PhOff);
return makeArrayRef(Begin, Begin + getHeader().e_phnum);
}
/// Get an iterator over notes in a program header.
///
/// The program header must be of type \c PT_NOTE.
///
/// \param Phdr the program header to iterate over.
/// \param Err [out] an error to support fallible iteration, which should
/// be checked after iteration ends.
Elf_Note_Iterator notes_begin(const Elf_Phdr &Phdr, Error &Err) const {
assert(Phdr.p_type == ELF::PT_NOTE && "Phdr is not of type PT_NOTE");
ErrorAsOutParameter ErrAsOutParam(&Err);
if (Phdr.p_offset + Phdr.p_filesz > getBufSize()) {
Err =
createError("invalid offset (0x" + Twine::utohexstr(Phdr.p_offset) +
") or size (0x" + Twine::utohexstr(Phdr.p_filesz) + ")");
return Elf_Note_Iterator(Err);
}
return Elf_Note_Iterator(base() + Phdr.p_offset, Phdr.p_filesz, Err);
}
/// Get an iterator over notes in a section.
///
/// The section must be of type \c SHT_NOTE.
///
/// \param Shdr the section to iterate over.
/// \param Err [out] an error to support fallible iteration, which should
/// be checked after iteration ends.
Elf_Note_Iterator notes_begin(const Elf_Shdr &Shdr, Error &Err) const {
assert(Shdr.sh_type == ELF::SHT_NOTE && "Shdr is not of type SHT_NOTE");
ErrorAsOutParameter ErrAsOutParam(&Err);
if (Shdr.sh_offset + Shdr.sh_size > getBufSize()) {
Err =
createError("invalid offset (0x" + Twine::utohexstr(Shdr.sh_offset) +
") or size (0x" + Twine::utohexstr(Shdr.sh_size) + ")");
return Elf_Note_Iterator(Err);
}
return Elf_Note_Iterator(base() + Shdr.sh_offset, Shdr.sh_size, Err);
}
/// Get the end iterator for notes.
Elf_Note_Iterator notes_end() const {
return Elf_Note_Iterator();
}
/// Get an iterator range over notes of a program header.
///
/// The program header must be of type \c PT_NOTE.
///
/// \param Phdr the program header to iterate over.
/// \param Err [out] an error to support fallible iteration, which should
/// be checked after iteration ends.
iterator_range<Elf_Note_Iterator> notes(const Elf_Phdr &Phdr,
Error &Err) const {
return make_range(notes_begin(Phdr, Err), notes_end());
}
/// Get an iterator range over notes of a section.
///
/// The section must be of type \c SHT_NOTE.
///
/// \param Shdr the section to iterate over.
/// \param Err [out] an error to support fallible iteration, which should
/// be checked after iteration ends.
iterator_range<Elf_Note_Iterator> notes(const Elf_Shdr &Shdr,
Error &Err) const {
return make_range(notes_begin(Shdr, Err), notes_end());
}
Expected<StringRef> getSectionStringTable(
Elf_Shdr_Range Sections,
WarningHandler WarnHandler = &defaultWarningHandler) const;
Expected<uint32_t> getSectionIndex(const Elf_Sym &Sym, Elf_Sym_Range Syms,
DataRegion<Elf_Word> ShndxTable) const;
Expected<const Elf_Shdr *> getSection(const Elf_Sym &Sym,
const Elf_Shdr *SymTab,
DataRegion<Elf_Word> ShndxTable) const;
Expected<const Elf_Shdr *> getSection(const Elf_Sym &Sym,
Elf_Sym_Range Symtab,
DataRegion<Elf_Word> ShndxTable) const;
Expected<const Elf_Shdr *> getSection(uint32_t Index) const;
Expected<const Elf_Sym *> getSymbol(const Elf_Shdr *Sec,
uint32_t Index) const;
Expected<StringRef>
getSectionName(const Elf_Shdr &Section,
WarningHandler WarnHandler = &defaultWarningHandler) const;
Expected<StringRef> getSectionName(const Elf_Shdr &Section,
StringRef DotShstrtab) const;
template <typename T>
Expected<ArrayRef<T>> getSectionContentsAsArray(const Elf_Shdr &Sec) const;
Expected<ArrayRef<uint8_t>> getSectionContents(const Elf_Shdr &Sec) const;
Expected<ArrayRef<uint8_t>> getSegmentContents(const Elf_Phdr &Phdr) const;
};
using ELF32LEFile = ELFFile<ELF32LE>;
using ELF64LEFile = ELFFile<ELF64LE>;
using ELF32BEFile = ELFFile<ELF32BE>;
using ELF64BEFile = ELFFile<ELF64BE>;
template <class ELFT>
inline Expected<const typename ELFT::Shdr *>
getSection(typename ELFT::ShdrRange Sections, uint32_t Index) {
if (Index >= Sections.size())
return createError("invalid section index: " + Twine(Index));
return &Sections[Index];
}
template <class ELFT>
inline Expected<uint32_t>
getExtendedSymbolTableIndex(const typename ELFT::Sym &Sym, unsigned SymIndex,
DataRegion<typename ELFT::Word> ShndxTable) {
assert(Sym.st_shndx == ELF::SHN_XINDEX);
if (!ShndxTable.First)
return createError(
"found an extended symbol index (" + Twine(SymIndex) +
"), but unable to locate the extended symbol index table");
Expected<typename ELFT::Word> TableOrErr = ShndxTable[SymIndex];
if (!TableOrErr)
return createError("unable to read an extended symbol table at index " +
Twine(SymIndex) + ": " +
toString(TableOrErr.takeError()));
return *TableOrErr;
}
template <class ELFT>
Expected<uint32_t>
ELFFile<ELFT>::getSectionIndex(const Elf_Sym &Sym, Elf_Sym_Range Syms,
DataRegion<Elf_Word> ShndxTable) const {
uint32_t Index = Sym.st_shndx;
if (Index == ELF::SHN_XINDEX) {
Expected<uint32_t> ErrorOrIndex =
getExtendedSymbolTableIndex<ELFT>(Sym, &Sym - Syms.begin(), ShndxTable);
if (!ErrorOrIndex)
return ErrorOrIndex.takeError();
return *ErrorOrIndex;
}
if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
return 0;
return Index;
}
template <class ELFT>
Expected<const typename ELFT::Shdr *>
ELFFile<ELFT>::getSection(const Elf_Sym &Sym, const Elf_Shdr *SymTab,
DataRegion<Elf_Word> ShndxTable) const {
auto SymsOrErr = symbols(SymTab);
if (!SymsOrErr)
return SymsOrErr.takeError();
return getSection(Sym, *SymsOrErr, ShndxTable);
}
template <class ELFT>
Expected<const typename ELFT::Shdr *>
ELFFile<ELFT>::getSection(const Elf_Sym &Sym, Elf_Sym_Range Symbols,
DataRegion<Elf_Word> ShndxTable) const {
auto IndexOrErr = getSectionIndex(Sym, Symbols, ShndxTable);
if (!IndexOrErr)
return IndexOrErr.takeError();
uint32_t Index = *IndexOrErr;
if (Index == 0)
return nullptr;
return getSection(Index);
}
template <class ELFT>
Expected<const typename ELFT::Sym *>
ELFFile<ELFT>::getSymbol(const Elf_Shdr *Sec, uint32_t Index) const {
auto SymsOrErr = symbols(Sec);
if (!SymsOrErr)
return SymsOrErr.takeError();
Elf_Sym_Range Symbols = *SymsOrErr;
if (Index >= Symbols.size())
return createError("unable to get symbol from section " +
getSecIndexForError(*this, *Sec) +
": invalid symbol index (" + Twine(Index) + ")");
return &Symbols[Index];
}
template <class ELFT>
template <typename T>
Expected<ArrayRef<T>>
ELFFile<ELFT>::getSectionContentsAsArray(const Elf_Shdr &Sec) const {
if (Sec.sh_entsize != sizeof(T) && sizeof(T) != 1)
return createError("section " + getSecIndexForError(*this, Sec) +
" has invalid sh_entsize: expected " + Twine(sizeof(T)) +
", but got " + Twine(Sec.sh_entsize));
uintX_t Offset = Sec.sh_offset;
uintX_t Size = Sec.sh_size;
if (Size % sizeof(T))
return createError("section " + getSecIndexForError(*this, Sec) +
" has an invalid sh_size (" + Twine(Size) +
") which is not a multiple of its sh_entsize (" +
Twine(Sec.sh_entsize) + ")");
if (std::numeric_limits<uintX_t>::max() - Offset < Size)
return createError("section " + getSecIndexForError(*this, Sec) +
" has a sh_offset (0x" + Twine::utohexstr(Offset) +
") + sh_size (0x" + Twine::utohexstr(Size) +
") that cannot be represented");
if (Offset + Size > Buf.size())
return createError("section " + getSecIndexForError(*this, Sec) +
" has a sh_offset (0x" + Twine::utohexstr(Offset) +
") + sh_size (0x" + Twine::utohexstr(Size) +
") that is greater than the file size (0x" +
Twine::utohexstr(Buf.size()) + ")");
if (Offset % alignof(T))
// TODO: this error is untested.
return createError("unaligned data");
const T *Start = reinterpret_cast<const T *>(base() + Offset);
return makeArrayRef(Start, Size / sizeof(T));
}
template <class ELFT>
Expected<ArrayRef<uint8_t>>
ELFFile<ELFT>::getSegmentContents(const Elf_Phdr &Phdr) const {
uintX_t Offset = Phdr.p_offset;
uintX_t Size = Phdr.p_filesz;
if (std::numeric_limits<uintX_t>::max() - Offset < Size)
return createError("program header " + getPhdrIndexForError(*this, Phdr) +
" has a p_offset (0x" + Twine::utohexstr(Offset) +
") + p_filesz (0x" + Twine::utohexstr(Size) +
") that cannot be represented");
if (Offset + Size > Buf.size())
return createError("program header " + getPhdrIndexForError(*this, Phdr) +
" has a p_offset (0x" + Twine::utohexstr(Offset) +
") + p_filesz (0x" + Twine::utohexstr(Size) +
") that is greater than the file size (0x" +
Twine::utohexstr(Buf.size()) + ")");
return makeArrayRef(base() + Offset, Size);
}
template <class ELFT>
Expected<ArrayRef<uint8_t>>
ELFFile<ELFT>::getSectionContents(const Elf_Shdr &Sec) const {
return getSectionContentsAsArray<uint8_t>(Sec);
}
template <class ELFT>
StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
return getELFRelocationTypeName(getHeader().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>
uint32_t ELFFile<ELFT>::getRelativeRelocationType() const {
return getELFRelativeRelocationType(getHeader().e_machine);
}
template <class ELFT>
Expected<SmallVector<Optional<VersionEntry>, 0>>
ELFFile<ELFT>::loadVersionMap(const Elf_Shdr *VerNeedSec,
const Elf_Shdr *VerDefSec) const {
SmallVector<Optional<VersionEntry>, 0> VersionMap;
// The first two version indexes are reserved.
// Index 0 is VER_NDX_LOCAL, index 1 is VER_NDX_GLOBAL.
VersionMap.push_back(VersionEntry());
VersionMap.push_back(VersionEntry());
auto InsertEntry = [&](unsigned N, StringRef Version, bool IsVerdef) {
if (N >= VersionMap.size())
VersionMap.resize(N + 1);
VersionMap[N] = {std::string(Version), IsVerdef};
};
if (VerDefSec) {
Expected<std::vector<VerDef>> Defs = getVersionDefinitions(*VerDefSec);
if (!Defs)
return Defs.takeError();
for (const VerDef &Def : *Defs)
InsertEntry(Def.Ndx & ELF::VERSYM_VERSION, Def.Name, true);
}
if (VerNeedSec) {
Expected<std::vector<VerNeed>> Deps = getVersionDependencies(*VerNeedSec);
if (!Deps)
return Deps.takeError();
for (const VerNeed &Dep : *Deps)
for (const VernAux &Aux : Dep.AuxV)
InsertEntry(Aux.Other & ELF::VERSYM_VERSION, Aux.Name, false);
}
return VersionMap;
}
template <class ELFT>
Expected<const typename ELFT::Sym *>
ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel &Rel,
const Elf_Shdr *SymTab) const {
uint32_t Index = Rel.getSymbol(isMips64EL());
if (Index == 0)
return nullptr;
return getEntry<Elf_Sym>(*SymTab, Index);
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getSectionStringTable(Elf_Shdr_Range Sections,
WarningHandler WarnHandler) const {
uint32_t Index = getHeader().e_shstrndx;
if (Index == ELF::SHN_XINDEX) {
// If the section name string table section index is greater than
// or equal to SHN_LORESERVE, then the actual index of the section name
// string table section is contained in the sh_link field of the section
// header at index 0.
if (Sections.empty())
return createError(
"e_shstrndx == SHN_XINDEX, but the section header table is empty");
Index = Sections[0].sh_link;
}
if (!Index) // no section string table.
return "";
if (Index >= Sections.size())
return createError("section header string table index " + Twine(Index) +
" does not exist");
return getStringTable(Sections[Index], WarnHandler);
}
/// This function finds the number of dynamic symbols using a GNU hash table.
///
/// @param Table The GNU hash table for .dynsym.
template <class ELFT>
static Expected<uint64_t>
getDynSymtabSizeFromGnuHash(const typename ELFT::GnuHash &Table,
const void *BufEnd) {
using Elf_Word = typename ELFT::Word;
if (Table.nbuckets == 0)
return Table.symndx + 1;
uint64_t LastSymIdx = 0;
// Find the index of the first symbol in the last chain.
for (Elf_Word Val : Table.buckets())
LastSymIdx = std::max(LastSymIdx, (uint64_t)Val);
const Elf_Word *It =
reinterpret_cast<const Elf_Word *>(Table.values(LastSymIdx).end());
// Locate the end of the chain to find the last symbol index.
while (It < BufEnd && (*It & 1) == 0) {
++LastSymIdx;
++It;
}
if (It >= BufEnd) {
return createStringError(
object_error::parse_failed,
"no terminator found for GNU hash section before buffer end");
}
return LastSymIdx + 1;
}
/// This function determines the number of dynamic symbols. It reads section
/// headers first. If section headers are not available, the number of
/// symbols will be inferred by parsing dynamic hash tables.
template <class ELFT>
Expected<uint64_t> ELFFile<ELFT>::getDynSymtabSize() const {
// Read .dynsym section header first if available.
Expected<Elf_Shdr_Range> SectionsOrError = sections();
if (!SectionsOrError)
return SectionsOrError.takeError();
for (const Elf_Shdr &Sec : *SectionsOrError) {
if (Sec.sh_type == ELF::SHT_DYNSYM) {
if (Sec.sh_size % Sec.sh_entsize != 0) {
return createStringError(object_error::parse_failed,
"SHT_DYNSYM section has sh_size (" +
Twine(Sec.sh_size) + ") % sh_entsize (" +
Twine(Sec.sh_entsize) + ") that is not 0");
}
return Sec.sh_size / Sec.sh_entsize;
}
}
if (!SectionsOrError->empty()) {
// Section headers are available but .dynsym header is not found.
// Return 0 as .dynsym does not exist.
return 0;
}
// Section headers do not exist. Falling back to infer
// upper bound of .dynsym from .gnu.hash and .hash.
Expected<Elf_Dyn_Range> DynTable = dynamicEntries();
if (!DynTable)
return DynTable.takeError();
llvm::Optional<uint64_t> ElfHash;
llvm::Optional<uint64_t> ElfGnuHash;
for (const Elf_Dyn &Entry : *DynTable) {
switch (Entry.d_tag) {
case ELF::DT_HASH:
ElfHash = Entry.d_un.d_ptr;
break;
case ELF::DT_GNU_HASH:
ElfGnuHash = Entry.d_un.d_ptr;
break;
}
}
if (ElfGnuHash) {
Expected<const uint8_t *> TablePtr = toMappedAddr(*ElfGnuHash);
if (!TablePtr)
return TablePtr.takeError();
const Elf_GnuHash *Table =
reinterpret_cast<const Elf_GnuHash *>(TablePtr.get());
return getDynSymtabSizeFromGnuHash<ELFT>(*Table, this->Buf.bytes_end());
}
// Search SYSV hash table to try to find the upper bound of dynsym.
if (ElfHash) {
Expected<const uint8_t *> TablePtr = toMappedAddr(*ElfHash);
if (!TablePtr)
return TablePtr.takeError();
const Elf_Hash *Table = reinterpret_cast<const Elf_Hash *>(TablePtr.get());
return Table->nchain;
}
return 0;
}
template <class ELFT> ELFFile<ELFT>::ELFFile(StringRef Object) : Buf(Object) {}
template <class ELFT>
Expected<ELFFile<ELFT>> ELFFile<ELFT>::create(StringRef Object) {
if (sizeof(Elf_Ehdr) > Object.size())
return createError("invalid buffer: the size (" + Twine(Object.size()) +
") is smaller than an ELF header (" +
Twine(sizeof(Elf_Ehdr)) + ")");
return ELFFile(Object);
}
template <class ELFT>
Expected<typename ELFT::ShdrRange> ELFFile<ELFT>::sections() const {
const uintX_t SectionTableOffset = getHeader().e_shoff;
if (SectionTableOffset == 0)
return ArrayRef<Elf_Shdr>();
if (getHeader().e_shentsize != sizeof(Elf_Shdr))
return createError("invalid e_shentsize in ELF header: " +
Twine(getHeader().e_shentsize));
const uint64_t FileSize = Buf.size();
if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize ||
SectionTableOffset + (uintX_t)sizeof(Elf_Shdr) < SectionTableOffset)
return createError(
"section header table goes past the end of the file: e_shoff = 0x" +
Twine::utohexstr(SectionTableOffset));
// Invalid address alignment of section headers
if (SectionTableOffset & (alignof(Elf_Shdr) - 1))
// TODO: this error is untested.
return createError("invalid alignment of section headers");
const Elf_Shdr *First =
reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
uintX_t NumSections = getHeader().e_shnum;
if (NumSections == 0)
NumSections = First->sh_size;
if (NumSections > UINT64_MAX / sizeof(Elf_Shdr))
return createError("invalid number of sections specified in the NULL "
"section's sh_size field (" +
Twine(NumSections) + ")");
const uint64_t SectionTableSize = NumSections * sizeof(Elf_Shdr);
if (SectionTableOffset + SectionTableSize < SectionTableOffset)
return createError(
"invalid section header table offset (e_shoff = 0x" +
Twine::utohexstr(SectionTableOffset) +
") or invalid number of sections specified in the first section "
"header's sh_size field (0x" +
Twine::utohexstr(NumSections) + ")");
// Section table goes past end of file!
if (SectionTableOffset + SectionTableSize > FileSize)
return createError("section table goes past the end of file");
return makeArrayRef(First, NumSections);
}
template <class ELFT>
template <typename T>
Expected<const T *> ELFFile<ELFT>::getEntry(uint32_t Section,
uint32_t Entry) const {
auto SecOrErr = getSection(Section);
if (!SecOrErr)
return SecOrErr.takeError();
return getEntry<T>(**SecOrErr, Entry);
}
template <class ELFT>
template <typename T>
Expected<const T *> ELFFile<ELFT>::getEntry(const Elf_Shdr &Section,
uint32_t Entry) const {
Expected<ArrayRef<T>> EntriesOrErr = getSectionContentsAsArray<T>(Section);
if (!EntriesOrErr)
return EntriesOrErr.takeError();
ArrayRef<T> Arr = *EntriesOrErr;
if (Entry >= Arr.size())
return createError(
"can't read an entry at 0x" +
Twine::utohexstr(Entry * static_cast<uint64_t>(sizeof(T))) +
": it goes past the end of the section (0x" +
Twine::utohexstr(Section.sh_size) + ")");
return &Arr[Entry];
}
template <typename ELFT>
Expected<StringRef> ELFFile<ELFT>::getSymbolVersionByIndex(
uint32_t SymbolVersionIndex, bool &IsDefault,
SmallVector<Optional<VersionEntry>, 0> &VersionMap,
Optional<bool> IsSymHidden) const {
size_t VersionIndex = SymbolVersionIndex & llvm::ELF::VERSYM_VERSION;
// Special markers for unversioned symbols.
if (VersionIndex == llvm::ELF::VER_NDX_LOCAL ||
VersionIndex == llvm::ELF::VER_NDX_GLOBAL) {
IsDefault = false;
return "";
}
// Lookup this symbol in the version table.
if (VersionIndex >= VersionMap.size() || !VersionMap[VersionIndex])
return createError("SHT_GNU_versym section refers to a version index " +
Twine(VersionIndex) + " which is missing");
const VersionEntry &Entry = *VersionMap[VersionIndex];
// A default version (@@) is only available for defined symbols.
if (!Entry.IsVerDef || IsSymHidden.getValueOr(false))
IsDefault = false;
else
IsDefault = !(SymbolVersionIndex & llvm::ELF::VERSYM_HIDDEN);
return Entry.Name.c_str();
}
template <class ELFT>
Expected<std::vector<VerDef>>
ELFFile<ELFT>::getVersionDefinitions(const Elf_Shdr &Sec) const {
Expected<StringRef> StrTabOrErr = getLinkAsStrtab(Sec);
if (!StrTabOrErr)
return StrTabOrErr.takeError();
Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
if (!ContentsOrErr)
return createError("cannot read content of " + describe(*this, Sec) + ": " +
toString(ContentsOrErr.takeError()));
const uint8_t *Start = ContentsOrErr->data();
const uint8_t *End = Start + ContentsOrErr->size();
auto ExtractNextAux = [&](const uint8_t *&VerdauxBuf,
unsigned VerDefNdx) -> Expected<VerdAux> {
if (VerdauxBuf + sizeof(Elf_Verdaux) > End)
return createError("invalid " + describe(*this, Sec) +
": version definition " + Twine(VerDefNdx) +
" refers to an auxiliary entry that goes past the end "
"of the section");
auto *Verdaux = reinterpret_cast<const Elf_Verdaux *>(VerdauxBuf);
VerdauxBuf += Verdaux->vda_next;
VerdAux Aux;
Aux.Offset = VerdauxBuf - Start;
if (Verdaux->vda_name <= StrTabOrErr->size())
Aux.Name = std::string(StrTabOrErr->drop_front(Verdaux->vda_name));
else
Aux.Name = ("<invalid vda_name: " + Twine(Verdaux->vda_name) + ">").str();
return Aux;
};
std::vector<VerDef> Ret;
const uint8_t *VerdefBuf = Start;
for (unsigned I = 1; I <= /*VerDefsNum=*/Sec.sh_info; ++I) {
if (VerdefBuf + sizeof(Elf_Verdef) > End)
return createError("invalid " + describe(*this, Sec) +
": version definition " + Twine(I) +
" goes past the end of the section");
if (reinterpret_cast<uintptr_t>(VerdefBuf) % sizeof(uint32_t) != 0)
return createError(
"invalid " + describe(*this, Sec) +
": found a misaligned version definition entry at offset 0x" +
Twine::utohexstr(VerdefBuf - Start));
unsigned Version = *reinterpret_cast<const Elf_Half *>(VerdefBuf);
if (Version != 1)
return createError("unable to dump " + describe(*this, Sec) +
": version " + Twine(Version) +
" is not yet supported");
const Elf_Verdef *D = reinterpret_cast<const Elf_Verdef *>(VerdefBuf);
VerDef &VD = *Ret.emplace(Ret.end());
VD.Offset = VerdefBuf - Start;
VD.Version = D->vd_version;
VD.Flags = D->vd_flags;
VD.Ndx = D->vd_ndx;
VD.Cnt = D->vd_cnt;
VD.Hash = D->vd_hash;
const uint8_t *VerdauxBuf = VerdefBuf + D->vd_aux;
for (unsigned J = 0; J < D->vd_cnt; ++J) {
if (reinterpret_cast<uintptr_t>(VerdauxBuf) % sizeof(uint32_t) != 0)
return createError("invalid " + describe(*this, Sec) +
": found a misaligned auxiliary entry at offset 0x" +
Twine::utohexstr(VerdauxBuf - Start));
Expected<VerdAux> AuxOrErr = ExtractNextAux(VerdauxBuf, I);
if (!AuxOrErr)
return AuxOrErr.takeError();
if (J == 0)
VD.Name = AuxOrErr->Name;
else
VD.AuxV.push_back(*AuxOrErr);
}
VerdefBuf += D->vd_next;
}
return Ret;
}
template <class ELFT>
Expected<std::vector<VerNeed>>
ELFFile<ELFT>::getVersionDependencies(const Elf_Shdr &Sec,
WarningHandler WarnHandler) const {
StringRef StrTab;
Expected<StringRef> StrTabOrErr = getLinkAsStrtab(Sec);
if (!StrTabOrErr) {
if (Error E = WarnHandler(toString(StrTabOrErr.takeError())))
return std::move(E);
} else {
StrTab = *StrTabOrErr;
}
Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
if (!ContentsOrErr)
return createError("cannot read content of " + describe(*this, Sec) + ": " +
toString(ContentsOrErr.takeError()));
const uint8_t *Start = ContentsOrErr->data();
const uint8_t *End = Start + ContentsOrErr->size();
const uint8_t *VerneedBuf = Start;
std::vector<VerNeed> Ret;
for (unsigned I = 1; I <= /*VerneedNum=*/Sec.sh_info; ++I) {
if (VerneedBuf + sizeof(Elf_Verdef) > End)
return createError("invalid " + describe(*this, Sec) +
": version dependency " + Twine(I) +
" goes past the end of the section");
if (reinterpret_cast<uintptr_t>(VerneedBuf) % sizeof(uint32_t) != 0)
return createError(
"invalid " + describe(*this, Sec) +
": found a misaligned version dependency entry at offset 0x" +
Twine::utohexstr(VerneedBuf - Start));
unsigned Version = *reinterpret_cast<const Elf_Half *>(VerneedBuf);
if (Version != 1)
return createError("unable to dump " + describe(*this, Sec) +
": version " + Twine(Version) +
" is not yet supported");
const Elf_Verneed *Verneed =
reinterpret_cast<const Elf_Verneed *>(VerneedBuf);
VerNeed &VN = *Ret.emplace(Ret.end());
VN.Version = Verneed->vn_version;
VN.Cnt = Verneed->vn_cnt;
VN.Offset = VerneedBuf - Start;
if (Verneed->vn_file < StrTab.size())
VN.File = std::string(StrTab.drop_front(Verneed->vn_file));
else
VN.File = ("<corrupt vn_file: " + Twine(Verneed->vn_file) + ">").str();
const uint8_t *VernauxBuf = VerneedBuf + Verneed->vn_aux;
for (unsigned J = 0; J < Verneed->vn_cnt; ++J) {
if (reinterpret_cast<uintptr_t>(VernauxBuf) % sizeof(uint32_t) != 0)
return createError("invalid " + describe(*this, Sec) +
": found a misaligned auxiliary entry at offset 0x" +
Twine::utohexstr(VernauxBuf - Start));
if (VernauxBuf + sizeof(Elf_Vernaux) > End)
return createError(
"invalid " + describe(*this, Sec) + ": version dependency " +
Twine(I) +
" refers to an auxiliary entry that goes past the end "
"of the section");
const Elf_Vernaux *Vernaux =
reinterpret_cast<const Elf_Vernaux *>(VernauxBuf);
VernAux &Aux = *VN.AuxV.emplace(VN.AuxV.end());
Aux.Hash = Vernaux->vna_hash;
Aux.Flags = Vernaux->vna_flags;
Aux.Other = Vernaux->vna_other;
Aux.Offset = VernauxBuf - Start;
if (StrTab.size() <= Vernaux->vna_name)
Aux.Name = "<corrupt>";
else
Aux.Name = std::string(StrTab.drop_front(Vernaux->vna_name));
VernauxBuf += Vernaux->vna_next;
}
VerneedBuf += Verneed->vn_next;
}
return Ret;
}
template <class ELFT>
Expected<const typename ELFT::Shdr *>
ELFFile<ELFT>::getSection(uint32_t Index) const {
auto TableOrErr = sections();
if (!TableOrErr)
return TableOrErr.takeError();
return object::getSection<ELFT>(*TableOrErr, Index);
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getStringTable(const Elf_Shdr &Section,
WarningHandler WarnHandler) const {
if (Section.sh_type != ELF::SHT_STRTAB)
if (Error E = WarnHandler("invalid sh_type for string table section " +
getSecIndexForError(*this, Section) +
": expected SHT_STRTAB, but got " +
object::getELFSectionTypeName(
getHeader().e_machine, Section.sh_type)))
return std::move(E);
auto V = getSectionContentsAsArray<char>(Section);
if (!V)
return V.takeError();
ArrayRef<char> Data = *V;
if (Data.empty())
return createError("SHT_STRTAB string table section " +
getSecIndexForError(*this, Section) + " is empty");
if (Data.back() != '\0')
return createError("SHT_STRTAB string table section " +
getSecIndexForError(*this, Section) +
" is non-null terminated");
return StringRef(Data.begin(), Data.size());
}
template <class ELFT>
Expected<ArrayRef<typename ELFT::Word>>
ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section) const {
auto SectionsOrErr = sections();
if (!SectionsOrErr)
return SectionsOrErr.takeError();
return getSHNDXTable(Section, *SectionsOrErr);
}
template <class ELFT>
Expected<ArrayRef<typename ELFT::Word>>
ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section,
Elf_Shdr_Range Sections) const {
assert(Section.sh_type == ELF::SHT_SYMTAB_SHNDX);
auto VOrErr = getSectionContentsAsArray<Elf_Word>(Section);
if (!VOrErr)
return VOrErr.takeError();
ArrayRef<Elf_Word> V = *VOrErr;
auto SymTableOrErr = object::getSection<ELFT>(Sections, Section.sh_link);
if (!SymTableOrErr)
return SymTableOrErr.takeError();
const Elf_Shdr &SymTable = **SymTableOrErr;
if (SymTable.sh_type != ELF::SHT_SYMTAB &&
SymTable.sh_type != ELF::SHT_DYNSYM)
return createError(
"SHT_SYMTAB_SHNDX section is linked with " +
object::getELFSectionTypeName(getHeader().e_machine, SymTable.sh_type) +
" section (expected SHT_SYMTAB/SHT_DYNSYM)");
uint64_t Syms = SymTable.sh_size / sizeof(Elf_Sym);
if (V.size() != Syms)
return createError("SHT_SYMTAB_SHNDX has " + Twine(V.size()) +
" entries, but the symbol table associated has " +
Twine(Syms));
return V;
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
auto SectionsOrErr = sections();
if (!SectionsOrErr)
return SectionsOrErr.takeError();
return getStringTableForSymtab(Sec, *SectionsOrErr);
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec,
Elf_Shdr_Range Sections) const {
if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM)
return createError(
"invalid sh_type for symbol table, expected SHT_SYMTAB or SHT_DYNSYM");
Expected<const Elf_Shdr *> SectionOrErr =
object::getSection<ELFT>(Sections, Sec.sh_link);
if (!SectionOrErr)
return SectionOrErr.takeError();
return getStringTable(**SectionOrErr);
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getLinkAsStrtab(const typename ELFT::Shdr &Sec) const {
Expected<const typename ELFT::Shdr *> StrTabSecOrErr =
getSection(Sec.sh_link);
if (!StrTabSecOrErr)
return createError("invalid section linked to " + describe(*this, Sec) +
": " + toString(StrTabSecOrErr.takeError()));
Expected<StringRef> StrTabOrErr = getStringTable(**StrTabSecOrErr);
if (!StrTabOrErr)
return createError("invalid string table linked to " +
describe(*this, Sec) + ": " +
toString(StrTabOrErr.takeError()));
return *StrTabOrErr;
}
template <class ELFT>
Expected<StringRef>
ELFFile<ELFT>::getSectionName(const Elf_Shdr &Section,
WarningHandler WarnHandler) const {
auto SectionsOrErr = sections();
if (!SectionsOrErr)
return SectionsOrErr.takeError();
auto Table = getSectionStringTable(*SectionsOrErr, WarnHandler);
if (!Table)
return Table.takeError();
return getSectionName(Section, *Table);
}
template <class ELFT>
Expected<StringRef> ELFFile<ELFT>::getSectionName(const Elf_Shdr &Section,
StringRef DotShstrtab) const {
uint32_t Offset = Section.sh_name;
if (Offset == 0)
return StringRef();
if (Offset >= DotShstrtab.size())
return createError("a section " + getSecIndexForError(*this, Section) +
" has an invalid sh_name (0x" +
Twine::utohexstr(Offset) +
") offset which goes past the end of the "
"section name string table");
return StringRef(DotShstrtab.data() + 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
inline unsigned hashSysV(StringRef SymbolName) {
unsigned h = 0, g;
for (char C : SymbolName) {
h = (h << 4) + C;
g = h & 0xf0000000L;
if (g != 0)
h ^= g >> 24;
h &= ~g;
}
return h;
}
} // end namespace object
} // end namespace llvm
#endif // LLVM_OBJECT_ELF_H