lib/Object/COFFImportFile.cpp

   1 //===- COFFImportFile.cpp - COFF short import file implementation ---------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines the writeImportLibrary function.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/Object/COFFImportFile.h"
  14 #include "llvm/ADT/ArrayRef.h"
  15 #include "llvm/Object/Archive.h"
  16 #include "llvm/Object/ArchiveWriter.h"
  17 #include "llvm/Object/COFF.h"
  18 #include "llvm/Support/Error.h"
  19 #include "llvm/Support/Path.h"
  20
  21 #include <cstdint>
  22 #include <string>
  23 #include <vector>
  24
  25 using namespace llvm::COFF;
  26 using namespace llvm::object;
  27 using namespace llvm;
  28
  29 namespace llvm {
  30 namespace object {
  31
  32 static bool is32bit(MachineTypes Machine) {
  33   switch (Machine) {
  34   default:
  35     llvm_unreachable("unsupported machine");
  36   case IMAGE_FILE_MACHINE_ARM64:
  37   case IMAGE_FILE_MACHINE_AMD64:
  38     return false;
  39   case IMAGE_FILE_MACHINE_ARMNT:
  40   case IMAGE_FILE_MACHINE_I386:
  41     return true;
  42   }
  43 }
  44
  45 static uint16_t getImgRelRelocation(MachineTypes Machine) {
  46   switch (Machine) {
  47   default:
  48     llvm_unreachable("unsupported machine");
  49   case IMAGE_FILE_MACHINE_AMD64:
  50     return IMAGE_REL_AMD64_ADDR32NB;
  51   case IMAGE_FILE_MACHINE_ARMNT:
  52     return IMAGE_REL_ARM_ADDR32NB;
  53   case IMAGE_FILE_MACHINE_ARM64:
  54     return IMAGE_REL_ARM64_ADDR32NB;
  55   case IMAGE_FILE_MACHINE_I386:
  56     return IMAGE_REL_I386_DIR32NB;
  57   }
  58 }
  59
  60 template <class T> static void append(std::vector<uint8_t> &B, const T &Data) {
  61   size_t S = B.size();
  62   B.resize(S + sizeof(T));
  63   memcpy(&B[S], &Data, sizeof(T));
  64 }
  65
  66 static void writeStringTable(std::vector<uint8_t> &B,
  67                              ArrayRef<const std::string> Strings) {
  68   // The COFF string table consists of a 4-byte value which is the size of the
  69   // table, including the length field itself.  This value is followed by the
  70   // string content itself, which is an array of null-terminated C-style
  71   // strings.  The termination is important as they are referenced to by offset
  72   // by the symbol entity in the file format.
  73
  74   size_t Pos = B.size();
  75   size_t Offset = B.size();
  76
  77   // Skip over the length field, we will fill it in later as we will have
  78   // computed the length while emitting the string content itself.
  79   Pos += sizeof(uint32_t);
  80
  81   for (const auto &S : Strings) {
  82     B.resize(Pos + S.length() + 1);
  83     strcpy(reinterpret_cast<char *>(&B[Pos]), S.c_str());
  84     Pos += S.length() + 1;
  85   }
  86
  87   // Backfill the length of the table now that it has been computed.
  88   support::ulittle32_t Length(B.size() - Offset);
  89   support::endian::write32le(&B[Offset], Length);
  90 }
  91
  92 static ImportNameType getNameType(StringRef Sym, StringRef ExtName,
  93                                   MachineTypes Machine, bool MinGW) {
  94   // A decorated stdcall function in MSVC is exported with the
  95   // type IMPORT_NAME, and the exported function name includes the
  96   // the leading underscore. In MinGW on the other hand, a decorated
  97   // stdcall function still omits the underscore (IMPORT_NAME_NOPREFIX).
  98   // See the comment in isDecorated in COFFModuleDefinition.cpp for more
  99   // details.
 100   if (ExtName.startswith("_") && ExtName.contains('@') && !MinGW)
 101     return IMPORT_NAME;
 102   if (Sym != ExtName)
 103     return IMPORT_NAME_UNDECORATE;
 104   if (Machine == IMAGE_FILE_MACHINE_I386 && Sym.startswith("_"))
 105     return IMPORT_NAME_NOPREFIX;
 106   return IMPORT_NAME;
 107 }
 108
 109 static Expected<std::string> replace(StringRef S, StringRef From,
 110                                      StringRef To) {
 111   size_t Pos = S.find(From);
 112
 113   // From and To may be mangled, but substrings in S may not.
 114   if (Pos == StringRef::npos && From.startswith("_") && To.startswith("_")) {
 115     From = From.substr(1);
 116     To = To.substr(1);
 117     Pos = S.find(From);
 118   }
 119
 120   if (Pos == StringRef::npos) {
 121     return make_error<StringError>(
 122       StringRef(Twine(S + ": replacing '" + From +
 123         "' with '" + To + "' failed").str()), object_error::parse_failed);
 124   }
 125
 126   return (Twine(S.substr(0, Pos)) + To + S.substr(Pos + From.size())).str();
 127 }
 128
 129 static const std::string NullImportDescriptorSymbolName =
 130     "__NULL_IMPORT_DESCRIPTOR";
 131
 132 namespace {
 133 // This class constructs various small object files necessary to support linking
 134 // symbols imported from a DLL.  The contents are pretty strictly defined and
 135 // nearly entirely static.  The details of the structures files are defined in
 136 // WINNT.h and the PE/COFF specification.
 137 class ObjectFactory {
 138   using u16 = support::ulittle16_t;
 139   using u32 = support::ulittle32_t;
 140   MachineTypes Machine;
 141   BumpPtrAllocator Alloc;
 142   StringRef ImportName;
 143   StringRef Library;
 144   std::string ImportDescriptorSymbolName;
 145   std::string NullThunkSymbolName;
 146
 147 public:
 148   ObjectFactory(StringRef S, MachineTypes M)
 149       : Machine(M), ImportName(S), Library(S.drop_back(4)),
 150         ImportDescriptorSymbolName(("__IMPORT_DESCRIPTOR_" + Library).str()),
 151         NullThunkSymbolName(("\x7f" + Library + "_NULL_THUNK_DATA").str()) {}
 152
 153   // Creates an Import Descriptor.  This is a small object file which contains a
 154   // reference to the terminators and contains the library name (entry) for the
 155   // import name table.  It will force the linker to construct the necessary
 156   // structure to import symbols from the DLL.
 157   NewArchiveMember createImportDescriptor(std::vector<uint8_t> &Buffer);
 158
 159   // Creates a NULL import descriptor.  This is a small object file whcih
 160   // contains a NULL import descriptor.  It is used to terminate the imports
 161   // from a specific DLL.
 162   NewArchiveMember createNullImportDescriptor(std::vector<uint8_t> &Buffer);
 163
 164   // Create a NULL Thunk Entry.  This is a small object file which contains a
 165   // NULL Import Address Table entry and a NULL Import Lookup Table Entry.  It
 166   // is used to terminate the IAT and ILT.
 167   NewArchiveMember createNullThunk(std::vector<uint8_t> &Buffer);
 168
 169   // Create a short import file which is described in PE/COFF spec 7. Import
 170   // Library Format.
 171   NewArchiveMember createShortImport(StringRef Sym, uint16_t Ordinal,
 172                                      ImportType Type, ImportNameType NameType);
 173
 174   // Create a weak external file which is described in PE/COFF Aux Format 3.
 175   NewArchiveMember createWeakExternal(StringRef Sym, StringRef Weak, bool Imp);
 176 };
 177 } // namespace
 178
 179 NewArchiveMember
 180 ObjectFactory::createImportDescriptor(std::vector<uint8_t> &Buffer) {
 181   const uint32_t NumberOfSections = 2;
 182   const uint32_t NumberOfSymbols = 7;
 183   const uint32_t NumberOfRelocations = 3;
 184
 185   // COFF Header
 186   coff_file_header Header{
 187       u16(Machine),
 188       u16(NumberOfSections),
 189       u32(0),
 190       u32(sizeof(Header) + (NumberOfSections * sizeof(coff_section)) +
 191           // .idata$2
 192           sizeof(coff_import_directory_table_entry) +
 193           NumberOfRelocations * sizeof(coff_relocation) +
 194           // .idata$4
 195           (ImportName.size() + 1)),
 196       u32(NumberOfSymbols),
 197       u16(0),
 198       u16(is32bit(Machine) ? IMAGE_FILE_32BIT_MACHINE : C_Invalid),
 199   };
 200   append(Buffer, Header);
 201
 202   // Section Header Table
 203   const coff_section SectionTable[NumberOfSections] = {
 204       {{'.', 'i', 'd', 'a', 't', 'a', '$', '2'},
 205        u32(0),
 206        u32(0),
 207        u32(sizeof(coff_import_directory_table_entry)),
 208        u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section)),
 209        u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section) +
 210            sizeof(coff_import_directory_table_entry)),
 211        u32(0),
 212        u16(NumberOfRelocations),
 213        u16(0),
 214        u32(IMAGE_SCN_ALIGN_4BYTES | IMAGE_SCN_CNT_INITIALIZED_DATA |
 215            IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE)},
 216       {{'.', 'i', 'd', 'a', 't', 'a', '$', '6'},
 217        u32(0),
 218        u32(0),
 219        u32(ImportName.size() + 1),
 220        u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section) +
 221            sizeof(coff_import_directory_table_entry) +
 222            NumberOfRelocations * sizeof(coff_relocation)),
 223        u32(0),
 224        u32(0),
 225        u16(0),
 226        u16(0),
 227        u32(IMAGE_SCN_ALIGN_2BYTES | IMAGE_SCN_CNT_INITIALIZED_DATA |
 228            IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE)},
 229   };
 230   append(Buffer, SectionTable);
 231
 232   // .idata$2
 233   const coff_import_directory_table_entry ImportDescriptor{
 234       u32(0), u32(0), u32(0), u32(0), u32(0),
 235   };
 236   append(Buffer, ImportDescriptor);
 237
 238   const coff_relocation RelocationTable[NumberOfRelocations] = {
 239       {u32(offsetof(coff_import_directory_table_entry, NameRVA)), u32(2),
 240        u16(getImgRelRelocation(Machine))},
 241       {u32(offsetof(coff_import_directory_table_entry, ImportLookupTableRVA)),
 242        u32(3), u16(getImgRelRelocation(Machine))},
 243       {u32(offsetof(coff_import_directory_table_entry, ImportAddressTableRVA)),
 244        u32(4), u16(getImgRelRelocation(Machine))},
 245   };
 246   append(Buffer, RelocationTable);
 247
 248   // .idata$6
 249   auto S = Buffer.size();
 250   Buffer.resize(S + ImportName.size() + 1);
 251   memcpy(&Buffer[S], ImportName.data(), ImportName.size());
 252   Buffer[S + ImportName.size()] = '\0';
 253
 254   // Symbol Table
 255   coff_symbol16 SymbolTable[NumberOfSymbols] = {
 256       {{{0, 0, 0, 0, 0, 0, 0, 0}},
 257        u32(0),
 258        u16(1),
 259        u16(0),
 260        IMAGE_SYM_CLASS_EXTERNAL,
 261        0},
 262       {{{'.', 'i', 'd', 'a', 't', 'a', '$', '2'}},
 263        u32(0),
 264        u16(1),
 265        u16(0),
 266        IMAGE_SYM_CLASS_SECTION,
 267        0},
 268       {{{'.', 'i', 'd', 'a', 't', 'a', '$', '6'}},
 269        u32(0),
 270        u16(2),
 271        u16(0),
 272        IMAGE_SYM_CLASS_STATIC,
 273        0},
 274       {{{'.', 'i', 'd', 'a', 't', 'a', '$', '4'}},
 275        u32(0),
 276        u16(0),
 277        u16(0),
 278        IMAGE_SYM_CLASS_SECTION,
 279        0},
 280       {{{'.', 'i', 'd', 'a', 't', 'a', '$', '5'}},
 281        u32(0),
 282        u16(0),
 283        u16(0),
 284        IMAGE_SYM_CLASS_SECTION,
 285        0},
 286       {{{0, 0, 0, 0, 0, 0, 0, 0}},
 287        u32(0),
 288        u16(0),
 289        u16(0),
 290        IMAGE_SYM_CLASS_EXTERNAL,
 291        0},
 292       {{{0, 0, 0, 0, 0, 0, 0, 0}},
 293        u32(0),
 294        u16(0),
 295        u16(0),
 296        IMAGE_SYM_CLASS_EXTERNAL,
 297        0},
 298   };
 299   // TODO: Name.Offset.Offset here and in the all similar places below
 300   // suggests a names refactoring. Maybe StringTableOffset.Value?
 301   SymbolTable[0].Name.Offset.Offset =
 302       sizeof(uint32_t);
 303   SymbolTable[5].Name.Offset.Offset =
 304       sizeof(uint32_t) + ImportDescriptorSymbolName.length() + 1;
 305   SymbolTable[6].Name.Offset.Offset =
 306       sizeof(uint32_t) + ImportDescriptorSymbolName.length() + 1 +
 307       NullImportDescriptorSymbolName.length() + 1;
 308   append(Buffer, SymbolTable);
 309
 310   // String Table
 311   writeStringTable(Buffer,
 312                    {ImportDescriptorSymbolName, NullImportDescriptorSymbolName,
 313                     NullThunkSymbolName});
 314
 315   StringRef F{reinterpret_cast<const char *>(Buffer.data()), Buffer.size()};
 316   return {MemoryBufferRef(F, ImportName)};
 317 }
 318
 319 NewArchiveMember
 320 ObjectFactory::createNullImportDescriptor(std::vector<uint8_t> &Buffer) {
 321   const uint32_t NumberOfSections = 1;
 322   const uint32_t NumberOfSymbols = 1;
 323
 324   // COFF Header
 325   coff_file_header Header{
 326       u16(Machine),
 327       u16(NumberOfSections),
 328       u32(0),
 329       u32(sizeof(Header) + (NumberOfSections * sizeof(coff_section)) +
 330           // .idata$3
 331           sizeof(coff_import_directory_table_entry)),
 332       u32(NumberOfSymbols),
 333       u16(0),
 334       u16(is32bit(Machine) ? IMAGE_FILE_32BIT_MACHINE : C_Invalid),
 335   };
 336   append(Buffer, Header);
 337
 338   // Section Header Table
 339   const coff_section SectionTable[NumberOfSections] = {
 340       {{'.', 'i', 'd', 'a', 't', 'a', '$', '3'},
 341        u32(0),
 342        u32(0),
 343        u32(sizeof(coff_import_directory_table_entry)),
 344        u32(sizeof(coff_file_header) +
 345            (NumberOfSections * sizeof(coff_section))),
 346        u32(0),
 347        u32(0),
 348        u16(0),
 349        u16(0),
 350        u32(IMAGE_SCN_ALIGN_4BYTES | IMAGE_SCN_CNT_INITIALIZED_DATA |
 351            IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE)},
 352   };
 353   append(Buffer, SectionTable);
 354
 355   // .idata$3
 356   const coff_import_directory_table_entry ImportDescriptor{
 357       u32(0), u32(0), u32(0), u32(0), u32(0),
 358   };
 359   append(Buffer, ImportDescriptor);
 360
 361   // Symbol Table
 362   coff_symbol16 SymbolTable[NumberOfSymbols] = {
 363       {{{0, 0, 0, 0, 0, 0, 0, 0}},
 364        u32(0),
 365        u16(1),
 366        u16(0),
 367        IMAGE_SYM_CLASS_EXTERNAL,
 368        0},
 369   };
 370   SymbolTable[0].Name.Offset.Offset = sizeof(uint32_t);
 371   append(Buffer, SymbolTable);
 372
 373   // String Table
 374   writeStringTable(Buffer, {NullImportDescriptorSymbolName});
 375
 376   StringRef F{reinterpret_cast<const char *>(Buffer.data()), Buffer.size()};
 377   return {MemoryBufferRef(F, ImportName)};
 378 }
 379
 380 NewArchiveMember ObjectFactory::createNullThunk(std::vector<uint8_t> &Buffer) {
 381   const uint32_t NumberOfSections = 2;
 382   const uint32_t NumberOfSymbols = 1;
 383   uint32_t VASize = is32bit(Machine) ? 4 : 8;
 384
 385   // COFF Header
 386   coff_file_header Header{
 387       u16(Machine),
 388       u16(NumberOfSections),
 389       u32(0),
 390       u32(sizeof(Header) + (NumberOfSections * sizeof(coff_section)) +
 391           // .idata$5
 392           VASize +
 393           // .idata$4
 394           VASize),
 395       u32(NumberOfSymbols),
 396       u16(0),
 397       u16(is32bit(Machine) ? IMAGE_FILE_32BIT_MACHINE : C_Invalid),
 398   };
 399   append(Buffer, Header);
 400
 401   // Section Header Table
 402   const coff_section SectionTable[NumberOfSections] = {
 403       {{'.', 'i', 'd', 'a', 't', 'a', '$', '5'},
 404        u32(0),
 405        u32(0),
 406        u32(VASize),
 407        u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section)),
 408        u32(0),
 409        u32(0),
 410        u16(0),
 411        u16(0),
 412        u32((is32bit(Machine) ? IMAGE_SCN_ALIGN_4BYTES
 413                              : IMAGE_SCN_ALIGN_8BYTES) |
 414            IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ |
 415            IMAGE_SCN_MEM_WRITE)},
 416       {{'.', 'i', 'd', 'a', 't', 'a', '$', '4'},
 417        u32(0),
 418        u32(0),
 419        u32(VASize),
 420        u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section) +
 421            VASize),
 422        u32(0),
 423        u32(0),
 424        u16(0),
 425        u16(0),
 426        u32((is32bit(Machine) ? IMAGE_SCN_ALIGN_4BYTES
 427                              : IMAGE_SCN_ALIGN_8BYTES) |
 428            IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ |
 429            IMAGE_SCN_MEM_WRITE)},
 430   };
 431   append(Buffer, SectionTable);
 432
 433   // .idata$5, ILT
 434   append(Buffer, u32(0));
 435   if (!is32bit(Machine))
 436     append(Buffer, u32(0));
 437
 438   // .idata$4, IAT
 439   append(Buffer, u32(0));
 440   if (!is32bit(Machine))
 441     append(Buffer, u32(0));
 442
 443   // Symbol Table
 444   coff_symbol16 SymbolTable[NumberOfSymbols] = {
 445       {{{0, 0, 0, 0, 0, 0, 0, 0}},
 446        u32(0),
 447        u16(1),
 448        u16(0),
 449        IMAGE_SYM_CLASS_EXTERNAL,
 450        0},
 451   };
 452   SymbolTable[0].Name.Offset.Offset = sizeof(uint32_t);
 453   append(Buffer, SymbolTable);
 454
 455   // String Table
 456   writeStringTable(Buffer, {NullThunkSymbolName});
 457
 458   StringRef F{reinterpret_cast<const char *>(Buffer.data()), Buffer.size()};
 459   return {MemoryBufferRef{F, ImportName}};
 460 }
 461
 462 NewArchiveMember ObjectFactory::createShortImport(StringRef Sym,
 463                                                   uint16_t Ordinal,
 464                                                   ImportType ImportType,
 465                                                   ImportNameType NameType) {
 466   size_t ImpSize = ImportName.size() + Sym.size() + 2; // +2 for NULs
 467   size_t Size = sizeof(coff_import_header) + ImpSize;
 468   char *Buf = Alloc.Allocate<char>(Size);
 469   memset(Buf, 0, Size);
 470   char *P = Buf;
 471
 472   // Write short import library.
 473   auto *Imp = reinterpret_cast<coff_import_header *>(P);
 474   P += sizeof(*Imp);
 475   Imp->Sig2 = 0xFFFF;
 476   Imp->Machine = Machine;
 477   Imp->SizeOfData = ImpSize;
 478   if (Ordinal > 0)
 479     Imp->OrdinalHint = Ordinal;
 480   Imp->TypeInfo = (NameType << 2) | ImportType;
 481
 482   // Write symbol name and DLL name.
 483   memcpy(P, Sym.data(), Sym.size());
 484   P += Sym.size() + 1;
 485   memcpy(P, ImportName.data(), ImportName.size());
 486
 487   return {MemoryBufferRef(StringRef(Buf, Size), ImportName)};
 488 }
 489
 490 NewArchiveMember ObjectFactory::createWeakExternal(StringRef Sym,
 491                                                    StringRef Weak, bool Imp) {
 492   std::vector<uint8_t> Buffer;
 493   const uint32_t NumberOfSections = 1;
 494   const uint32_t NumberOfSymbols = 5;
 495
 496   // COFF Header
 497   coff_file_header Header{
 498       u16(Machine),
 499       u16(NumberOfSections),
 500       u32(0),
 501       u32(sizeof(Header) + (NumberOfSections * sizeof(coff_section))),
 502       u32(NumberOfSymbols),
 503       u16(0),
 504       u16(0),
 505   };
 506   append(Buffer, Header);
 507
 508   // Section Header Table
 509   const coff_section SectionTable[NumberOfSections] = {
 510       {{'.', 'd', 'r', 'e', 'c', 't', 'v', 'e'},
 511        u32(0),
 512        u32(0),
 513        u32(0),
 514        u32(0),
 515        u32(0),
 516        u32(0),
 517        u16(0),
 518        u16(0),
 519        u32(IMAGE_SCN_LNK_INFO | IMAGE_SCN_LNK_REMOVE)}};
 520   append(Buffer, SectionTable);
 521
 522   // Symbol Table
 523   coff_symbol16 SymbolTable[NumberOfSymbols] = {
 524       {{{'@', 'c', 'o', 'm', 'p', '.', 'i', 'd'}},
 525        u32(0),
 526        u16(0xFFFF),
 527        u16(0),
 528        IMAGE_SYM_CLASS_STATIC,
 529        0},
 530       {{{'@', 'f', 'e', 'a', 't', '.', '0', '0'}},
 531        u32(0),
 532        u16(0xFFFF),
 533        u16(0),
 534        IMAGE_SYM_CLASS_STATIC,
 535        0},
 536       {{{0, 0, 0, 0, 0, 0, 0, 0}},
 537        u32(0),
 538        u16(0),
 539        u16(0),
 540        IMAGE_SYM_CLASS_EXTERNAL,
 541        0},
 542       {{{0, 0, 0, 0, 0, 0, 0, 0}},
 543        u32(0),
 544        u16(0),
 545        u16(0),
 546        IMAGE_SYM_CLASS_WEAK_EXTERNAL,
 547        1},
 548       {{{2, 0, 0, 0, IMAGE_WEAK_EXTERN_SEARCH_ALIAS, 0, 0, 0}},
 549        u32(0),
 550        u16(0),
 551        u16(0),
 552        IMAGE_SYM_CLASS_NULL,
 553        0},
 554   };
 555   SymbolTable[2].Name.Offset.Offset = sizeof(uint32_t);
 556
 557   //__imp_ String Table
 558   StringRef Prefix = Imp ? "__imp_" : "";
 559   SymbolTable[3].Name.Offset.Offset =
 560       sizeof(uint32_t) + Sym.size() + Prefix.size() + 1;
 561   append(Buffer, SymbolTable);
 562   writeStringTable(Buffer, {(Prefix + Sym).str(),
 563                             (Prefix + Weak).str()});
 564
 565   // Copied here so we can still use writeStringTable
 566   char *Buf = Alloc.Allocate<char>(Buffer.size());
 567   memcpy(Buf, Buffer.data(), Buffer.size());
 568   return {MemoryBufferRef(StringRef(Buf, Buffer.size()), ImportName)};
 569 }
 570
 571 Error writeImportLibrary(StringRef ImportName, StringRef Path,
 572                          ArrayRef<COFFShortExport> Exports,
 573                          MachineTypes Machine, bool MinGW) {
 574
 575   std::vector<NewArchiveMember> Members;
 576   ObjectFactory OF(llvm::sys::path::filename(ImportName), Machine);
 577
 578   std::vector<uint8_t> ImportDescriptor;
 579   Members.push_back(OF.createImportDescriptor(ImportDescriptor));
 580
 581   std::vector<uint8_t> NullImportDescriptor;
 582   Members.push_back(OF.createNullImportDescriptor(NullImportDescriptor));
 583
 584   std::vector<uint8_t> NullThunk;
 585   Members.push_back(OF.createNullThunk(NullThunk));
 586
 587   for (COFFShortExport E : Exports) {
 588     if (E.Private)
 589       continue;
 590
 591     ImportType ImportType = IMPORT_CODE;
 592     if (E.Data)
 593       ImportType = IMPORT_DATA;
 594     if (E.Constant)
 595       ImportType = IMPORT_CONST;
 596
 597     StringRef SymbolName = E.SymbolName.empty() ? E.Name : E.SymbolName;
 598     ImportNameType NameType = getNameType(SymbolName, E.Name, Machine, MinGW);
 599     Expected<std::string> Name = E.ExtName.empty()
 600                                      ? SymbolName
 601                                      : replace(SymbolName, E.Name, E.ExtName);
 602
 603     if (!Name)
 604       return Name.takeError();
 605
 606     if (!E.AliasTarget.empty() && *Name != E.AliasTarget) {
 607       Members.push_back(OF.createWeakExternal(E.AliasTarget, *Name, false));
 608       Members.push_back(OF.createWeakExternal(E.AliasTarget, *Name, true));
 609       continue;
 610     }
 611
 612     Members.push_back(
 613         OF.createShortImport(*Name, E.Ordinal, ImportType, NameType));
 614   }
 615
 616   return writeArchive(Path, Members, /*WriteSymtab*/ true,
 617                       object::Archive::K_GNU,
 618                       /*Deterministic*/ true, /*Thin*/ false);
 619 }
 620
 621 } // namespace object
 622 } // namespace llvm