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//===- lib/ReaderWriter/PECOFF/IdataPass.cpp ------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "IdataPass.h"
#include "Pass.h"
#include "lld/Core/File.h"
#include "lld/Core/Pass.h"
#include "lld/Core/Simple.h"
#include "llvm/Support/COFF.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Endian.h"
#include <algorithm>
#include <cstddef>
#include <cstring>
#include <map>
namespace lld {
namespace pecoff {
namespace idata {
IdataAtom::IdataAtom(Context &context, std::vector<uint8_t> data)
: COFFLinkerInternalAtom(context.dummyFile,
context.dummyFile.getNextOrdinal(), data) {
context.file.addAtom(*this);
}
HintNameAtom::HintNameAtom(Context &context, uint16_t hint,
StringRef importName)
: IdataAtom(context, assembleRawContent(hint, importName)),
_importName(importName) {}
std::vector<uint8_t> HintNameAtom::assembleRawContent(uint16_t hint,
StringRef importName) {
size_t size =
llvm::RoundUpToAlignment(sizeof(hint) + importName.size() + 1, 2);
std::vector<uint8_t> ret(size);
ret[importName.size()] = 0;
ret[importName.size() - 1] = 0;
*reinterpret_cast<llvm::support::ulittle16_t *>(&ret[0]) = hint;
std::memcpy(&ret[2], importName.data(), importName.size());
return ret;
}
std::vector<uint8_t>
ImportTableEntryAtom::assembleRawContent(uint32_t contents) {
std::vector<uint8_t> ret(4);
*reinterpret_cast<llvm::support::ulittle32_t *>(&ret[0]) = contents;
return ret;
}
// Creates atoms for an import lookup table. The import lookup table is an
// array of pointers to hint/name atoms. The array needs to be terminated with
// the NULL entry.
void ImportDirectoryAtom::addRelocations(
Context &context, StringRef loadName,
const std::vector<COFFSharedLibraryAtom *> &sharedAtoms) {
// Create parallel arrays. The contents of the two are initially the
// same. The PE/COFF loader overwrites the import address tables with the
// pointers to the referenced items after loading the executable into
// memory.
std::vector<ImportTableEntryAtom *> importLookupTables =
createImportTableAtoms(context, sharedAtoms, false, ".idata.t");
std::vector<ImportTableEntryAtom *> importAddressTables =
createImportTableAtoms(context, sharedAtoms, true, ".idata.a");
addDir32NBReloc(this, importLookupTables[0],
offsetof(ImportDirectoryTableEntry, ImportLookupTableRVA));
addDir32NBReloc(this, importAddressTables[0],
offsetof(ImportDirectoryTableEntry, ImportAddressTableRVA));
auto *atom = new (_alloc)
COFFStringAtom(context.dummyFile, context.dummyFile.getNextOrdinal(),
".idata", loadName);
context.file.addAtom(*atom);
addDir32NBReloc(this, atom, offsetof(ImportDirectoryTableEntry, NameRVA));
}
std::vector<ImportTableEntryAtom *> ImportDirectoryAtom::createImportTableAtoms(
Context &context, const std::vector<COFFSharedLibraryAtom *> &sharedAtoms,
bool shouldAddReference, StringRef sectionName) const {
std::vector<ImportTableEntryAtom *> ret;
for (COFFSharedLibraryAtom *atom : sharedAtoms) {
ImportTableEntryAtom *entry = nullptr;
if (atom->importName().empty()) {
// Import by ordinal
uint32_t hint = (1U << 31) | atom->hint();
entry = new (_alloc) ImportTableEntryAtom(context, hint, sectionName);
} else {
// Import by name
entry = new (_alloc) ImportTableEntryAtom(context, 0, sectionName);
HintNameAtom *hintName =
new (_alloc) HintNameAtom(context, atom->hint(), atom->importName());
addDir32NBReloc(entry, hintName);
}
ret.push_back(entry);
if (shouldAddReference)
atom->setImportTableEntry(entry);
}
// Add the NULL entry.
ret.push_back(new (_alloc) ImportTableEntryAtom(context, 0, sectionName));
return ret;
}
} // namespace idata
void IdataPass::perform(std::unique_ptr<MutableFile> &file) {
if (file->sharedLibrary().empty())
return;
idata::Context context(*file, _dummyFile);
std::map<StringRef, std::vector<COFFSharedLibraryAtom *> > sharedAtoms =
groupByLoadName(*file);
for (auto i : sharedAtoms) {
StringRef loadName = i.first;
std::vector<COFFSharedLibraryAtom *> &atoms = i.second;
new (_alloc) idata::ImportDirectoryAtom(context, loadName, atoms);
}
// All atoms, including those of tyep NullImportDirectoryAtom, are added to
// context.file in the IdataAtom's constructor.
new (_alloc) idata::NullImportDirectoryAtom(context);
replaceSharedLibraryAtoms(context);
}
std::map<StringRef, std::vector<COFFSharedLibraryAtom *> >
IdataPass::groupByLoadName(MutableFile &file) {
std::map<StringRef, COFFSharedLibraryAtom *> uniqueAtoms;
for (const SharedLibraryAtom *atom : file.sharedLibrary())
uniqueAtoms[atom->name()] = (COFFSharedLibraryAtom *)atom;
std::map<StringRef, std::vector<COFFSharedLibraryAtom *> > ret;
for (auto i : uniqueAtoms) {
COFFSharedLibraryAtom *atom = i.second;
ret[atom->loadName()].push_back(atom);
}
return ret;
}
/// Transforms a reference to a COFFSharedLibraryAtom to a real reference.
void IdataPass::replaceSharedLibraryAtoms(idata::Context &context) {
for (const DefinedAtom *atom : context.file.defined()) {
for (const Reference *ref : *atom) {
const Atom *target = ref->target();
auto *sharedAtom = dyn_cast<SharedLibraryAtom>(target);
if (!sharedAtom)
continue;
auto *coffSharedAtom = (COFFSharedLibraryAtom *)sharedAtom;
const DefinedAtom *entry = coffSharedAtom->getImportTableEntry();
const_cast<Reference *>(ref)->setTarget(entry);
}
}
}
} // namespace pecoff
} // namespace lld
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