llvm-project/lld/ELF/InputFiles.cpp

301 lines
8.9 KiB
C++
Raw Normal View History

//===- InputFiles.cpp -----------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "InputFiles.h"
#include "InputSection.h"
#include "Error.h"
#include "Symbols.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
using namespace llvm::ELF;
using namespace llvm::object;
using namespace llvm::sys::fs;
using namespace lld;
using namespace lld::elf2;
template <class ELFT> static uint16_t getEMachine(const ELFFileBase &B) {
bool IsShared = isa<SharedFileBase>(B);
if (IsShared)
return cast<SharedFile<ELFT>>(B).getEMachine();
return cast<ObjectFile<ELFT>>(B).getEMachine();
}
uint16_t ELFFileBase::getEMachine() const {
switch (EKind) {
case ELF32BEKind:
return ::getEMachine<ELF32BE>(*this);
case ELF32LEKind:
return ::getEMachine<ELF32LE>(*this);
case ELF64BEKind:
return ::getEMachine<ELF64BE>(*this);
case ELF64LEKind:
return ::getEMachine<ELF64LE>(*this);
default:
llvm_unreachable("Invalid kind");
}
}
namespace {
class ECRAII {
std::error_code EC;
public:
std::error_code &getEC() { return EC; }
~ECRAII() { error(EC); }
};
}
template <class ELFT>
ELFData<ELFT>::ELFData(MemoryBufferRef MB)
: ELFObj(MB.getBuffer(), ECRAII().getEC()) {}
template <class ELFT>
typename ELFData<ELFT>::Elf_Sym_Range
ELFData<ELFT>::getSymbolsHelper(bool Local) {
if (!Symtab)
return Elf_Sym_Range(nullptr, nullptr);
Elf_Sym_Range Syms = ELFObj.symbols(Symtab);
uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
uint32_t FirstNonLocal = Symtab->sh_info;
if (FirstNonLocal > NumSymbols)
error("Invalid sh_info in symbol table");
if (!Local)
return make_range(Syms.begin() + FirstNonLocal, Syms.end());
// +1 to skip over dummy symbol.
return make_range(Syms.begin() + 1, Syms.begin() + FirstNonLocal);
}
template <class ELFT> void ELFData<ELFT>::initStringTable() {
if (!Symtab)
return;
ErrorOr<StringRef> StringTableOrErr = ELFObj.getStringTableForSymtab(*Symtab);
error(StringTableOrErr.getError());
StringTable = *StringTableOrErr;
}
template <class ELFT>
typename ELFData<ELFT>::Elf_Sym_Range ELFData<ELFT>::getNonLocalSymbols() {
return getSymbolsHelper(false);
}
template <class ELFT>
ObjectFile<ELFT>::ObjectFile(MemoryBufferRef M)
: ObjectFileBase(getStaticELFKind<ELFT>(), M), ELFData<ELFT>(M) {}
template <class ELFT>
typename ObjectFile<ELFT>::Elf_Sym_Range ObjectFile<ELFT>::getLocalSymbols() {
return this->getSymbolsHelper(true);
}
template <class ELFT> void elf2::ObjectFile<ELFT>::parse() {
// Read section and symbol tables.
initializeSections();
initializeSymbols();
}
template <class ELFT> void elf2::ObjectFile<ELFT>::initializeSections() {
uint64_t Size = this->ELFObj.getNumSections();
Sections.resize(Size);
unsigned I = 0;
for (const Elf_Shdr &Sec : this->ELFObj.sections()) {
switch (Sec.sh_type) {
case SHT_SYMTAB:
this->Symtab = &Sec;
break;
case SHT_SYMTAB_SHNDX: {
ErrorOr<ArrayRef<Elf_Word>> ErrorOrTable =
this->ELFObj.getSHNDXTable(Sec);
error(ErrorOrTable);
SymtabSHNDX = *ErrorOrTable;
break;
}
case SHT_STRTAB:
case SHT_NULL:
break;
case SHT_RELA:
case SHT_REL: {
uint32_t RelocatedSectionIndex = Sec.sh_info;
if (RelocatedSectionIndex >= Size)
error("Invalid relocated section index");
InputSection<ELFT> *RelocatedSection = Sections[RelocatedSectionIndex];
if (!RelocatedSection)
error("Unsupported relocation reference");
RelocatedSection->RelocSections.push_back(&Sec);
break;
}
default:
Sections[I] = new (Alloc) InputSection<ELFT>(this, &Sec);
break;
}
++I;
}
}
template <class ELFT> void elf2::ObjectFile<ELFT>::initializeSymbols() {
this->initStringTable();
Elf_Sym_Range Syms = this->getNonLocalSymbols();
uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
SymbolBodies.reserve(NumSymbols);
for (const Elf_Sym &Sym : Syms)
SymbolBodies.push_back(createSymbolBody(this->StringTable, &Sym));
}
template <class ELFT>
SymbolBody *elf2::ObjectFile<ELFT>::createSymbolBody(StringRef StringTable,
const Elf_Sym *Sym) {
ErrorOr<StringRef> NameOrErr = Sym->getName(StringTable);
error(NameOrErr.getError());
StringRef Name = *NameOrErr;
uint32_t SecIndex = Sym->st_shndx;
switch (SecIndex) {
case SHN_ABS:
return new (Alloc) DefinedAbsolute<ELFT>(Name, *Sym);
case SHN_UNDEF:
return new (Alloc) Undefined<ELFT>(Name, *Sym);
case SHN_COMMON:
return new (Alloc) DefinedCommon<ELFT>(Name, *Sym);
case SHN_XINDEX:
SecIndex = this->ELFObj.getExtendedSymbolTableIndex(Sym, this->Symtab,
SymtabSHNDX);
break;
}
if (SecIndex >= Sections.size() || (SecIndex != 0 && !Sections[SecIndex]))
error("Invalid section index");
switch (Sym->getBinding()) {
default:
error("unexpected binding");
case STB_GLOBAL:
case STB_WEAK:
case STB_GNU_UNIQUE:
return new (Alloc) DefinedRegular<ELFT>(Name, *Sym, *Sections[SecIndex]);
}
}
static std::unique_ptr<Archive> openArchive(MemoryBufferRef MB) {
ErrorOr<std::unique_ptr<Archive>> ArchiveOrErr = Archive::create(MB);
error(ArchiveOrErr, "Failed to parse archive");
return std::move(*ArchiveOrErr);
}
void ArchiveFile::parse() {
File = openArchive(MB);
// Allocate a buffer for Lazy objects.
size_t NumSyms = File->getNumberOfSymbols();
LazySymbols.reserve(NumSyms);
// Read the symbol table to construct Lazy objects.
for (const Archive::Symbol &Sym : File->symbols())
LazySymbols.emplace_back(this, Sym);
}
// Returns a buffer pointing to a member file containing a given symbol.
MemoryBufferRef ArchiveFile::getMember(const Archive::Symbol *Sym) {
ErrorOr<Archive::child_iterator> ItOrErr = Sym->getMember();
error(ItOrErr,
Twine("Could not get the member for symbol ") + Sym->getName());
Archive::child_iterator It = *ItOrErr;
if (!Seen.insert(It->getChildOffset()).second)
return MemoryBufferRef();
ErrorOr<MemoryBufferRef> Ret = It->getMemoryBufferRef();
error(Ret, Twine("Could not get the buffer for the member defining symbol ") +
Sym->getName());
return *Ret;
}
std::vector<MemoryBufferRef> ArchiveFile::getMembers() {
File = openArchive(MB);
std::vector<MemoryBufferRef> Result;
for (const Archive::Child &Child : File->children()) {
ErrorOr<MemoryBufferRef> MbOrErr = Child.getMemoryBufferRef();
error(MbOrErr,
Twine("Could not get the buffer for a child of the archive ") +
File->getFileName());
Result.push_back(MbOrErr.get());
}
return Result;
}
template <class ELFT>
SharedFile<ELFT>::SharedFile(MemoryBufferRef M)
: SharedFileBase(getStaticELFKind<ELFT>(), M), ELFData<ELFT>(M) {}
template <class ELFT> void SharedFile<ELFT>::parseSoName() {
typedef typename ELFFile<ELFT>::Elf_Dyn Elf_Dyn;
typedef typename ELFFile<ELFT>::uintX_t uintX_t;
const Elf_Shdr *DynamicSec = nullptr;
const ELFFile<ELFT> Obj = this->ELFObj;
for (const Elf_Shdr &Sec : Obj.sections()) {
uint32_t Type = Sec.sh_type;
if (Type == SHT_DYNSYM)
this->Symtab = &Sec;
else if (Type == SHT_DYNAMIC)
DynamicSec = &Sec;
}
this->initStringTable();
SoName = getName();
if (DynamicSec) {
auto *Begin =
reinterpret_cast<const Elf_Dyn *>(Obj.base() + DynamicSec->sh_offset);
const Elf_Dyn *End = Begin + DynamicSec->sh_size / sizeof(Elf_Dyn);
for (const Elf_Dyn &Dyn : make_range(Begin, End)) {
if (Dyn.d_tag == DT_SONAME) {
uintX_t Val = Dyn.getVal();
if (Val >= this->StringTable.size())
error("Invalid DT_SONAME entry");
SoName = StringRef(this->StringTable.data() + Val);
break;
}
}
}
}
template <class ELFT> void SharedFile<ELFT>::parse() {
Elf_Sym_Range Syms = this->getNonLocalSymbols();
uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
SymbolBodies.reserve(NumSymbols);
for (const Elf_Sym &Sym : Syms) {
if (Sym.isUndefined())
continue;
ErrorOr<StringRef> NameOrErr = Sym.getName(this->StringTable);
error(NameOrErr.getError());
StringRef Name = *NameOrErr;
SymbolBodies.emplace_back(Name, Sym);
}
}
namespace lld {
namespace elf2 {
template class elf2::ObjectFile<llvm::object::ELF32LE>;
template class elf2::ObjectFile<llvm::object::ELF32BE>;
template class elf2::ObjectFile<llvm::object::ELF64LE>;
template class elf2::ObjectFile<llvm::object::ELF64BE>;
template class elf2::SharedFile<llvm::object::ELF32LE>;
template class elf2::SharedFile<llvm::object::ELF32BE>;
template class elf2::SharedFile<llvm::object::ELF64LE>;
template class elf2::SharedFile<llvm::object::ELF64BE>;
}
}