forked from OSchip/llvm-project
495 lines
16 KiB
C++
495 lines
16 KiB
C++
//===- Librarian.cpp ------------------------------------------------------===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains functions for the Librarian. The librarian creates and
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// manages libraries of the Common Object File Format (COFF) object files. It
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// primarily is used for creating static libraries and import libraries.
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//
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//===----------------------------------------------------------------------===//
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#include "Config.h"
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#include "Driver.h"
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#include "Error.h"
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#include "Symbols.h"
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#include "llvm/Object/Archive.h"
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#include "llvm/Object/ArchiveWriter.h"
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#include "llvm/Object/COFF.h"
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#include "llvm/Support/Path.h"
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#include <vector>
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using namespace lld::coff;
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using namespace llvm::COFF;
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using namespace llvm::object;
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using namespace llvm;
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static bool is32bit() {
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switch (Config->Machine) {
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default:
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llvm_unreachable("unsupported machine");
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case IMAGE_FILE_MACHINE_AMD64:
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return false;
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case IMAGE_FILE_MACHINE_ARMNT:
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case IMAGE_FILE_MACHINE_I386:
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return true;
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}
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}
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static uint16_t getImgRelRelocation() {
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switch (Config->Machine) {
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default:
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llvm_unreachable("unsupported machine");
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case IMAGE_FILE_MACHINE_AMD64:
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return IMAGE_REL_AMD64_ADDR32NB;
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case IMAGE_FILE_MACHINE_ARMNT:
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return IMAGE_REL_ARM_ADDR32NB;
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case IMAGE_FILE_MACHINE_I386:
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return IMAGE_REL_I386_DIR32NB;
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}
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}
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template <class T> static void append(std::vector<uint8_t> &B, const T &Data) {
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size_t S = B.size();
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B.resize(S + sizeof(T));
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memcpy(&B[S], &Data, sizeof(T));
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}
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static void writeStringTable(std::vector<uint8_t> &B,
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ArrayRef<const std::string> Strings) {
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// The COFF string table consists of a 4-byte value which is the size of the
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// table, including the length field itself. This value is followed by the
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// string content itself, which is an array of null-terminated C-style
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// strings. The termination is important as they are referenced to by offset
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// by the symbol entity in the file format.
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std::vector<uint8_t>::size_type Pos = B.size();
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std::vector<uint8_t>::size_type Offset = B.size();
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// Skip over the length field, we will fill it in later as we will have
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// computed the length while emitting the string content itself.
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Pos += sizeof(uint32_t);
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for (const auto &S : Strings) {
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B.resize(Pos + S.length() + 1);
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strcpy(reinterpret_cast<char *>(&B[Pos]), S.c_str());
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Pos += S.length() + 1;
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}
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// Backfill the length of the table now that it has been computed.
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support::ulittle32_t Length(B.size() - Offset);
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memcpy(&B[Offset], &Length, sizeof(Length));
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}
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static std::string getImplibPath() {
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if (!Config->Implib.empty())
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return Config->Implib;
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SmallString<128> Out = StringRef(Config->OutputFile);
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sys::path::replace_extension(Out, ".lib");
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return Out.str();
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}
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static ImportNameType getNameType(StringRef Sym, StringRef ExtName) {
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if (Sym != ExtName)
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return IMPORT_NAME_UNDECORATE;
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if (Config->Machine == I386 && Sym.startswith("_"))
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return IMPORT_NAME_NOPREFIX;
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return IMPORT_NAME;
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}
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static std::string replace(StringRef S, StringRef From, StringRef To) {
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size_t Pos = S.find(From);
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assert(Pos != StringRef::npos);
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return (Twine(S.substr(0, Pos)) + To + S.substr(Pos + From.size())).str();
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}
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static const std::string NullImportDescriptorSymbolName =
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"__NULL_IMPORT_DESCRIPTOR";
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namespace {
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// This class constructs various small object files necessary to support linking
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// symbols imported from a DLL. The contents are pretty strictly defined and
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// nearly entirely static. The details of the structures files are defined in
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// WINNT.h and the PE/COFF specification.
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class ObjectFactory {
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using u16 = support::ulittle16_t;
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using u32 = support::ulittle32_t;
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BumpPtrAllocator Alloc;
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StringRef DLLName;
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StringRef Library;
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std::string ImportDescriptorSymbolName;
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std::string NullThunkSymbolName;
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public:
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ObjectFactory(StringRef S)
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: DLLName(S), Library(S.drop_back(4)),
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ImportDescriptorSymbolName(("__IMPORT_DESCRIPTOR_" + Library).str()),
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NullThunkSymbolName(("\x7f" + Library + "_NULL_THUNK_DATA").str()) {}
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// Creates an Import Descriptor. This is a small object file which contains a
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// reference to the terminators and contains the library name (entry) for the
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// import name table. It will force the linker to construct the necessary
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// structure to import symbols from the DLL.
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NewArchiveMember createImportDescriptor(std::vector<uint8_t> &Buffer);
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// Creates a NULL import descriptor. This is a small object file whcih
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// contains a NULL import descriptor. It is used to terminate the imports
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// from a specific DLL.
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NewArchiveMember createNullImportDescriptor(std::vector<uint8_t> &Buffer);
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// Create a NULL Thunk Entry. This is a small object file which contains a
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// NULL Import Address Table entry and a NULL Import Lookup Table Entry. It
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// is used to terminate the IAT and ILT.
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NewArchiveMember createNullThunk(std::vector<uint8_t> &Buffer);
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// Create a short import file which is described in PE/COFF spec 7. Import
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// Library Format.
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NewArchiveMember createShortImport(StringRef Sym, uint16_t Ordinal,
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ImportNameType NameType, bool isData);
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};
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}
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NewArchiveMember
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ObjectFactory::createImportDescriptor(std::vector<uint8_t> &Buffer) {
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static const uint32_t NumberOfSections = 2;
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static const uint32_t NumberOfSymbols = 7;
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static const uint32_t NumberOfRelocations = 3;
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// COFF Header
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coff_file_header Header{
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u16(Config->Machine), u16(NumberOfSections), u32(0),
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u32(sizeof(Header) + (NumberOfSections * sizeof(coff_section)) +
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// .idata$2
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sizeof(coff_import_directory_table_entry) +
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NumberOfRelocations * sizeof(coff_relocation) +
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// .idata$4
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(DLLName.size() + 1)),
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u32(NumberOfSymbols), u16(0),
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u16(is32bit() ? IMAGE_FILE_32BIT_MACHINE : 0),
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};
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append(Buffer, Header);
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// Section Header Table
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static const coff_section SectionTable[NumberOfSections] = {
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{{'.', 'i', 'd', 'a', 't', 'a', '$', '2'},
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u32(0),
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u32(0),
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u32(sizeof(coff_import_directory_table_entry)),
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u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section)),
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u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section) +
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sizeof(coff_import_directory_table_entry)),
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u32(0),
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u16(NumberOfRelocations),
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u16(0),
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u32(IMAGE_SCN_ALIGN_4BYTES | IMAGE_SCN_CNT_INITIALIZED_DATA |
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IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE)},
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{{'.', 'i', 'd', 'a', 't', 'a', '$', '6'},
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u32(0),
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u32(0),
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u32(DLLName.size() + 1),
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u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section) +
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sizeof(coff_import_directory_table_entry) +
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NumberOfRelocations * sizeof(coff_relocation)),
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u32(0),
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u32(0),
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u16(0),
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u16(0),
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u32(IMAGE_SCN_ALIGN_2BYTES | IMAGE_SCN_CNT_INITIALIZED_DATA |
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IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE)},
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};
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append(Buffer, SectionTable);
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// .idata$2
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static const coff_import_directory_table_entry ImportDescriptor{
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u32(0), u32(0), u32(0), u32(0), u32(0),
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};
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append(Buffer, ImportDescriptor);
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static const coff_relocation RelocationTable[NumberOfRelocations] = {
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{u32(offsetof(coff_import_directory_table_entry, NameRVA)), u32(2),
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u16(getImgRelRelocation())},
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{u32(offsetof(coff_import_directory_table_entry, ImportLookupTableRVA)),
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u32(3), u16(getImgRelRelocation())},
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{u32(offsetof(coff_import_directory_table_entry, ImportAddressTableRVA)),
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u32(4), u16(getImgRelRelocation())},
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};
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append(Buffer, RelocationTable);
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// .idata$6
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auto S = Buffer.size();
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Buffer.resize(S + DLLName.size() + 1);
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memcpy(&Buffer[S], DLLName.data(), DLLName.size());
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Buffer[S + DLLName.size()] = '\0';
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// Symbol Table
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coff_symbol16 SymbolTable[NumberOfSymbols] = {
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{{{0, 0, 0, 0, 0, 0, 0, 0}},
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u32(0),
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u16(1),
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u16(0),
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IMAGE_SYM_CLASS_EXTERNAL,
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0},
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{{{'.', 'i', 'd', 'a', 't', 'a', '$', '2'}},
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u32(0),
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u16(1),
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u16(0),
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IMAGE_SYM_CLASS_SECTION,
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0},
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{{{'.', 'i', 'd', 'a', 't', 'a', '$', '6'}},
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u32(0),
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u16(2),
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u16(0),
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IMAGE_SYM_CLASS_STATIC,
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0},
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{{{'.', 'i', 'd', 'a', 't', 'a', '$', '4'}},
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u32(0),
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u16(0),
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u16(0),
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IMAGE_SYM_CLASS_SECTION,
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0},
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{{{'.', 'i', 'd', 'a', 't', 'a', '$', '5'}},
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u32(0),
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u16(0),
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u16(0),
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IMAGE_SYM_CLASS_SECTION,
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0},
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{{{0, 0, 0, 0, 0, 0, 0, 0}},
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u32(0),
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u16(0),
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u16(0),
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IMAGE_SYM_CLASS_EXTERNAL,
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0},
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{{{0, 0, 0, 0, 0, 0, 0, 0}},
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u32(0),
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u16(0),
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u16(0),
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IMAGE_SYM_CLASS_EXTERNAL,
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0},
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};
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reinterpret_cast<StringTableOffset &>(SymbolTable[0].Name).Offset =
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sizeof(uint32_t);
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reinterpret_cast<StringTableOffset &>(SymbolTable[5].Name).Offset =
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sizeof(uint32_t) + ImportDescriptorSymbolName.length() + 1;
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reinterpret_cast<StringTableOffset &>(SymbolTable[6].Name).Offset =
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sizeof(uint32_t) + ImportDescriptorSymbolName.length() + 1 +
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NullImportDescriptorSymbolName.length() + 1;
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append(Buffer, SymbolTable);
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// String Table
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writeStringTable(Buffer,
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{ImportDescriptorSymbolName, NullImportDescriptorSymbolName,
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NullThunkSymbolName});
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StringRef F{reinterpret_cast<const char *>(Buffer.data()), Buffer.size()};
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return {MemoryBufferRef(F, DLLName)};
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}
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NewArchiveMember
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ObjectFactory::createNullImportDescriptor(std::vector<uint8_t> &Buffer) {
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static const uint32_t NumberOfSections = 1;
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static const uint32_t NumberOfSymbols = 1;
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// COFF Header
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coff_file_header Header{
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u16(Config->Machine), u16(NumberOfSections), u32(0),
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u32(sizeof(Header) + (NumberOfSections * sizeof(coff_section)) +
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// .idata$3
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sizeof(coff_import_directory_table_entry)),
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u32(NumberOfSymbols), u16(0),
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u16(is32bit() ? IMAGE_FILE_32BIT_MACHINE : 0),
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};
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append(Buffer, Header);
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// Section Header Table
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static const coff_section SectionTable[NumberOfSections] = {
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{{'.', 'i', 'd', 'a', 't', 'a', '$', '3'},
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u32(0),
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u32(0),
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u32(sizeof(coff_import_directory_table_entry)),
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u32(sizeof(coff_file_header) +
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(NumberOfSections * sizeof(coff_section))),
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u32(0),
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u32(0),
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u16(0),
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u16(0),
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u32(IMAGE_SCN_ALIGN_4BYTES | IMAGE_SCN_CNT_INITIALIZED_DATA |
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IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE)},
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};
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append(Buffer, SectionTable);
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// .idata$3
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static const coff_import_directory_table_entry ImportDescriptor{
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u32(0), u32(0), u32(0), u32(0), u32(0),
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};
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append(Buffer, ImportDescriptor);
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// Symbol Table
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coff_symbol16 SymbolTable[NumberOfSymbols] = {
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{{{0, 0, 0, 0, 0, 0, 0, 0}},
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u32(0),
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u16(1),
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u16(0),
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IMAGE_SYM_CLASS_EXTERNAL,
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0},
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};
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reinterpret_cast<StringTableOffset &>(SymbolTable[0].Name).Offset =
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sizeof(uint32_t);
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append(Buffer, SymbolTable);
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// String Table
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writeStringTable(Buffer, {NullImportDescriptorSymbolName});
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StringRef F{reinterpret_cast<const char *>(Buffer.data()), Buffer.size()};
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return {MemoryBufferRef(F, DLLName)};
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}
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NewArchiveMember ObjectFactory::createNullThunk(std::vector<uint8_t> &Buffer) {
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static const uint32_t NumberOfSections = 2;
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static const uint32_t NumberOfSymbols = 1;
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uint32_t VASize = is32bit() ? 4 : 8;
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// COFF Header
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coff_file_header Header{
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u16(Config->Machine), u16(NumberOfSections), u32(0),
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u32(sizeof(Header) + (NumberOfSections * sizeof(coff_section)) +
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// .idata$5
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VASize +
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// .idata$4
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VASize),
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u32(NumberOfSymbols), u16(0),
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u16(is32bit() ? IMAGE_FILE_32BIT_MACHINE : 0),
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};
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append(Buffer, Header);
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// Section Header Table
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static const coff_section SectionTable[NumberOfSections] = {
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{{'.', 'i', 'd', 'a', 't', 'a', '$', '5'},
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u32(0),
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u32(0),
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u32(VASize),
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u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section)),
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u32(0),
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u32(0),
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u16(0),
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u16(0),
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u32((is32bit() ? IMAGE_SCN_ALIGN_4BYTES : IMAGE_SCN_ALIGN_8BYTES) |
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IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ |
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IMAGE_SCN_MEM_WRITE)},
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{{'.', 'i', 'd', 'a', 't', 'a', '$', '4'},
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u32(0),
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u32(0),
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u32(VASize),
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u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section) +
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VASize),
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u32(0),
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u32(0),
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u16(0),
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u16(0),
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u32((is32bit() ? IMAGE_SCN_ALIGN_4BYTES : IMAGE_SCN_ALIGN_8BYTES) |
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IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ |
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IMAGE_SCN_MEM_WRITE)},
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};
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append(Buffer, SectionTable);
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// .idata$5, ILT
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append(Buffer, u32(0));
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if (!is32bit())
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append(Buffer, u32(0));
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// .idata$4, IAT
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append(Buffer, u32(0));
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if (!is32bit())
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append(Buffer, u32(0));
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// Symbol Table
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coff_symbol16 SymbolTable[NumberOfSymbols] = {
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{{{0, 0, 0, 0, 0, 0, 0, 0}},
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u32(0),
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u16(1),
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u16(0),
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IMAGE_SYM_CLASS_EXTERNAL,
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0},
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};
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reinterpret_cast<StringTableOffset &>(SymbolTable[0].Name).Offset =
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sizeof(uint32_t);
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append(Buffer, SymbolTable);
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// String Table
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writeStringTable(Buffer, {NullThunkSymbolName});
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StringRef F{reinterpret_cast<const char *>(Buffer.data()), Buffer.size()};
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return {MemoryBufferRef{F, DLLName}};
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}
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NewArchiveMember ObjectFactory::createShortImport(StringRef Sym,
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uint16_t Ordinal,
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ImportNameType NameType,
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bool isData) {
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size_t ImpSize = DLLName.size() + Sym.size() + 2; // +2 for NULs
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size_t Size = sizeof(coff_import_header) + ImpSize;
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char *Buf = Alloc.Allocate<char>(Size);
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memset(Buf, 0, Size);
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char *P = Buf;
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// Write short import library.
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auto *Imp = reinterpret_cast<coff_import_header *>(P);
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P += sizeof(*Imp);
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Imp->Sig2 = 0xFFFF;
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Imp->Machine = Config->Machine;
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Imp->SizeOfData = ImpSize;
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if (Ordinal > 0)
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Imp->OrdinalHint = Ordinal;
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Imp->TypeInfo = (isData ? IMPORT_DATA : IMPORT_CODE);
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Imp->TypeInfo |= NameType << 2;
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// Write symbol name and DLL name.
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memcpy(P, Sym.data(), Sym.size());
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P += Sym.size() + 1;
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memcpy(P, DLLName.data(), DLLName.size());
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return {MemoryBufferRef(StringRef(Buf, Size), DLLName)};
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}
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// Creates an import library for a DLL. In this function, we first
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// create an empty import library using lib.exe and then adds short
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// import files to that file.
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void lld::coff::writeImportLibrary() {
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std::vector<NewArchiveMember> Members;
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std::string Path = getImplibPath();
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std::string DLLName = sys::path::filename(Config->OutputFile);
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ObjectFactory OF(DLLName);
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std::vector<uint8_t> ImportDescriptor;
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Members.push_back(OF.createImportDescriptor(ImportDescriptor));
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std::vector<uint8_t> NullImportDescriptor;
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Members.push_back(OF.createNullImportDescriptor(NullImportDescriptor));
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std::vector<uint8_t> NullThunk;
|
|
Members.push_back(OF.createNullThunk(NullThunk));
|
|
|
|
for (Export &E : Config->Exports) {
|
|
if (E.Private)
|
|
continue;
|
|
|
|
ImportNameType Type = getNameType(E.SymbolName, E.Name);
|
|
std::string Name = E.ExtName.empty()
|
|
? std::string(E.SymbolName)
|
|
: replace(E.SymbolName, E.Name, E.ExtName);
|
|
Members.push_back(OF.createShortImport(Name, E.Ordinal, Type, E.Data));
|
|
}
|
|
|
|
std::pair<StringRef, std::error_code> Result =
|
|
writeArchive(Path, Members, /*WriteSymtab*/ true, object::Archive::K_GNU,
|
|
/*Deterministic*/ true, /*Thin*/ false);
|
|
if (auto EC = Result.second)
|
|
fatal(EC, "failed to write " + Path);
|
|
}
|