llvm-project/lld/COFF/InputFiles.cpp

308 lines
10 KiB
C++

//===- InputFiles.cpp -----------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "Chunks.h"
#include "Error.h"
#include "InputFiles.h"
#include "Writer.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/LTO/LTOModule.h"
#include "llvm/Object/COFF.h"
#include "llvm/Support/COFF.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm::object;
using namespace llvm::support::endian;
using llvm::COFF::ImportHeader;
using llvm::COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
using llvm::RoundUpToAlignment;
using llvm::sys::fs::identify_magic;
using llvm::sys::fs::file_magic;
namespace lld {
namespace coff {
// Returns the last element of a path, which is supposed to be a filename.
static StringRef getBasename(StringRef Path) {
size_t Pos = Path.find_last_of("\\/");
if (Pos == StringRef::npos)
return Path;
return Path.substr(Pos + 1);
}
// Returns a string in the format of "foo.obj" or "foo.obj(bar.lib)".
std::string InputFile::getShortName() {
if (ParentName == "")
return getName().lower();
std::string Res = (getBasename(ParentName) + "(" +
getBasename(getName()) + ")").str();
return StringRef(Res).lower();
}
std::error_code ArchiveFile::parse() {
// Parse a MemoryBufferRef as an archive file.
auto ArchiveOrErr = Archive::create(MB);
if (auto EC = ArchiveOrErr.getError())
return EC;
File = std::move(ArchiveOrErr.get());
// Allocate a buffer for Lazy objects.
size_t BufSize = File->getNumberOfSymbols() * sizeof(Lazy);
Lazy *Buf = (Lazy *)Alloc.Allocate(BufSize, llvm::alignOf<Lazy>());
// Read the symbol table to construct Lazy objects.
uint32_t I = 0;
for (const Archive::Symbol &Sym : File->symbols()) {
auto *B = new (&Buf[I++]) Lazy(this, Sym);
// Skip special symbol exists in import library files.
if (B->getName() != "__NULL_IMPORT_DESCRIPTOR")
SymbolBodies.push_back(B);
}
return std::error_code();
}
// Returns a buffer pointing to a member file containing a given symbol.
ErrorOr<MemoryBufferRef> ArchiveFile::getMember(const Archive::Symbol *Sym) {
auto ItOrErr = Sym->getMember();
if (auto EC = ItOrErr.getError())
return EC;
Archive::child_iterator It = ItOrErr.get();
// Return an empty buffer if we have already returned the same buffer.
const char *StartAddr = It->getBuffer().data();
auto Pair = Seen.insert(StartAddr);
if (!Pair.second)
return MemoryBufferRef();
return It->getMemoryBufferRef();
}
std::error_code ObjectFile::parse() {
// Parse a memory buffer as a COFF file.
auto BinOrErr = createBinary(MB);
if (auto EC = BinOrErr.getError())
return EC;
std::unique_ptr<Binary> Bin = std::move(BinOrErr.get());
if (auto *Obj = dyn_cast<COFFObjectFile>(Bin.get())) {
Bin.release();
COFFObj.reset(Obj);
} else {
llvm::errs() << getName() << " is not a COFF file.\n";
return make_error_code(LLDError::InvalidFile);
}
// Read section and symbol tables.
if (auto EC = initializeChunks())
return EC;
return initializeSymbols();
}
SymbolBody *ObjectFile::getSymbolBody(uint32_t SymbolIndex) {
return SparseSymbolBodies[SymbolIndex]->getReplacement();
}
std::error_code ObjectFile::initializeChunks() {
uint32_t NumSections = COFFObj->getNumberOfSections();
Chunks.reserve(NumSections);
SparseChunks.resize(NumSections + 1);
for (uint32_t I = 1; I < NumSections + 1; ++I) {
const coff_section *Sec;
StringRef Name;
if (auto EC = COFFObj->getSection(I, Sec)) {
llvm::errs() << "getSection failed: " << Name << ": "
<< EC.message() << "\n";
return make_error_code(LLDError::BrokenFile);
}
if (auto EC = COFFObj->getSectionName(Sec, Name)) {
llvm::errs() << "getSectionName failed: " << Name << ": "
<< EC.message() << "\n";
return make_error_code(LLDError::BrokenFile);
}
if (Name == ".drectve") {
ArrayRef<uint8_t> Data;
COFFObj->getSectionContents(Sec, Data);
Directives = std::string((const char *)Data.data(), Data.size());
continue;
}
if (Name.startswith(".debug"))
continue;
if (Sec->Characteristics & llvm::COFF::IMAGE_SCN_LNK_REMOVE)
continue;
auto *C = new (Alloc) SectionChunk(this, Sec, I);
Chunks.push_back(C);
SparseChunks[I] = C;
}
return std::error_code();
}
std::error_code ObjectFile::initializeSymbols() {
uint32_t NumSymbols = COFFObj->getNumberOfSymbols();
SymbolBodies.reserve(NumSymbols);
SparseSymbolBodies.resize(NumSymbols);
int32_t LastSectionNumber = 0;
for (uint32_t I = 0; I < NumSymbols; ++I) {
// Get a COFFSymbolRef object.
auto SymOrErr = COFFObj->getSymbol(I);
if (auto EC = SymOrErr.getError()) {
llvm::errs() << "broken object file: " << getName() << ": "
<< EC.message() << "\n";
return make_error_code(LLDError::BrokenFile);
}
COFFSymbolRef Sym = SymOrErr.get();
const void *AuxP = nullptr;
if (Sym.getNumberOfAuxSymbols())
AuxP = COFFObj->getSymbol(I + 1)->getRawPtr();
bool IsFirst = (LastSectionNumber != Sym.getSectionNumber());
SymbolBody *Body = createSymbolBody(Sym, AuxP, IsFirst);
if (Body) {
SymbolBodies.push_back(Body);
SparseSymbolBodies[I] = Body;
}
I += Sym.getNumberOfAuxSymbols();
LastSectionNumber = Sym.getSectionNumber();
}
return std::error_code();
}
SymbolBody *ObjectFile::createSymbolBody(COFFSymbolRef Sym, const void *AuxP,
bool IsFirst) {
StringRef Name;
if (Sym.isUndefined()) {
COFFObj->getSymbolName(Sym, Name);
return new (Alloc) Undefined(Name);
}
if (Sym.isCommon()) {
Chunk *C = new (Alloc) CommonChunk(Sym);
Chunks.push_back(C);
return new (Alloc) DefinedCommon(COFFObj.get(), Sym, C);
}
if (Sym.isAbsolute()) {
COFFObj->getSymbolName(Sym, Name);
// Skip special symbols.
if (Name == "@comp.id" || Name == "@feat.00")
return nullptr;
return new (Alloc) DefinedAbsolute(Name, Sym.getValue());
}
// TODO: Handle IMAGE_WEAK_EXTERN_SEARCH_ALIAS
if (Sym.isWeakExternal()) {
COFFObj->getSymbolName(Sym, Name);
auto *Aux = (const coff_aux_weak_external *)AuxP;
return new (Alloc) Undefined(Name, &SparseSymbolBodies[Aux->TagIndex]);
}
// Handle associative sections
if (IsFirst && AuxP) {
if (Chunk *C = SparseChunks[Sym.getSectionNumber()]) {
auto *Aux = reinterpret_cast<const coff_aux_section_definition *>(AuxP);
if (Aux->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
auto *Parent =
(SectionChunk *)(SparseChunks[Aux->getNumber(Sym.isBigObj())]);
if (Parent)
Parent->addAssociative((SectionChunk *)C);
}
}
}
if (Chunk *C = SparseChunks[Sym.getSectionNumber()]) {
if (C->isCOMDAT())
return new (Alloc) DefinedCOMDAT(COFFObj.get(), Sym, C);
return new (Alloc) DefinedRegular(COFFObj.get(), Sym, C);
}
return nullptr;
}
std::error_code ImportFile::parse() {
const char *Buf = MB.getBufferStart();
const char *End = MB.getBufferEnd();
const auto *Hdr = reinterpret_cast<const coff_import_header *>(Buf);
// Check if the total size is valid.
if ((size_t)(End - Buf) != (sizeof(*Hdr) + Hdr->SizeOfData)) {
llvm::errs() << "broken import library\n";
return make_error_code(LLDError::BrokenFile);
}
// Read names and create an __imp_ symbol.
StringRef Name = StringAlloc.save(StringRef(Buf + sizeof(*Hdr)));
StringRef ImpName = StringAlloc.save(Twine("__imp_") + Name);
StringRef DLLName(Buf + sizeof(coff_import_header) + Name.size() + 1);
StringRef ExternalName = Name;
if (Hdr->getNameType() == llvm::COFF::IMPORT_ORDINAL)
ExternalName = "";
auto *ImpSym = new (Alloc) DefinedImportData(DLLName, ImpName, ExternalName,
Hdr);
SymbolBodies.push_back(ImpSym);
// If type is function, we need to create a thunk which jump to an
// address pointed by the __imp_ symbol. (This allows you to call
// DLL functions just like regular non-DLL functions.)
if (Hdr->getType() == llvm::COFF::IMPORT_CODE)
SymbolBodies.push_back(new (Alloc) DefinedImportThunk(Name, ImpSym));
return std::error_code();
}
std::error_code BitcodeFile::parse() {
std::string Err;
M.reset(LTOModule::createFromBuffer(MB.getBufferStart(),
MB.getBufferSize(),
llvm::TargetOptions(), Err));
if (!Err.empty()) {
llvm::errs() << Err << '\n';
return make_error_code(LLDError::BrokenFile);
}
llvm::BumpPtrStringSaver Saver(Alloc);
for (unsigned I = 0, E = M->getSymbolCount(); I != E; ++I) {
lto_symbol_attributes Attrs = M->getSymbolAttributes(I);
if ((Attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
continue;
StringRef SymName = Saver.save(M->getSymbolName(I));
int SymbolDef = Attrs & LTO_SYMBOL_DEFINITION_MASK;
if (SymbolDef == LTO_SYMBOL_DEFINITION_UNDEFINED) {
SymbolBodies.push_back(new (Alloc) Undefined(SymName));
} else {
bool Replaceable = (SymbolDef == LTO_SYMBOL_DEFINITION_TENTATIVE ||
(Attrs & LTO_SYMBOL_COMDAT));
SymbolBodies.push_back(new (Alloc) DefinedBitcode(SymName, Replaceable));
const llvm::GlobalValue *GV = M->getSymbolGV(I);
if (GV && GV->hasDLLExportStorageClass()) {
Directives += " /export:";
Directives += SymName;
if (!GV->getValueType()->isFunctionTy())
Directives += ",data";
}
}
}
// Extract any linker directives from the bitcode file, which are represented
// as module flags with the key "Linker Options".
llvm::SmallVector<llvm::Module::ModuleFlagEntry, 8> Flags;
M->getModule().getModuleFlagsMetadata(Flags);
for (auto &&Flag : Flags) {
if (Flag.Key->getString() != "Linker Options")
continue;
for (llvm::Metadata *Op : cast<llvm::MDNode>(Flag.Val)->operands()) {
for (llvm::Metadata *InnerOp : cast<llvm::MDNode>(Op)->operands()) {
Directives += " ";
Directives += cast<llvm::MDString>(InnerOp)->getString();
}
}
}
return std::error_code();
}
} // namespace coff
} // namespace lld