ArchiveWriter.cpp revision 344779
1//===- ArchiveWriter.cpp - ar File Format implementation --------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines the writeArchive function. 11// 12//===----------------------------------------------------------------------===// 13 14#include "llvm/Object/ArchiveWriter.h" 15#include "llvm/ADT/ArrayRef.h" 16#include "llvm/ADT/StringRef.h" 17#include "llvm/BinaryFormat/Magic.h" 18#include "llvm/IR/LLVMContext.h" 19#include "llvm/Object/Archive.h" 20#include "llvm/Object/ObjectFile.h" 21#include "llvm/Object/SymbolicFile.h" 22#include "llvm/Support/EndianStream.h" 23#include "llvm/Support/Errc.h" 24#include "llvm/Support/ErrorHandling.h" 25#include "llvm/Support/Format.h" 26#include "llvm/Support/Path.h" 27#include "llvm/Support/ToolOutputFile.h" 28#include "llvm/Support/raw_ostream.h" 29 30#include <map> 31 32#if !defined(_MSC_VER) && !defined(__MINGW32__) 33#include <unistd.h> 34#else 35#include <io.h> 36#endif 37 38using namespace llvm; 39 40NewArchiveMember::NewArchiveMember(MemoryBufferRef BufRef) 41 : Buf(MemoryBuffer::getMemBuffer(BufRef, false)), 42 MemberName(BufRef.getBufferIdentifier()) {} 43 44Expected<NewArchiveMember> 45NewArchiveMember::getOldMember(const object::Archive::Child &OldMember, 46 bool Deterministic) { 47 Expected<llvm::MemoryBufferRef> BufOrErr = OldMember.getMemoryBufferRef(); 48 if (!BufOrErr) 49 return BufOrErr.takeError(); 50 51 NewArchiveMember M; 52 assert(M.IsNew == false); 53 M.Buf = MemoryBuffer::getMemBuffer(*BufOrErr, false); 54 M.MemberName = M.Buf->getBufferIdentifier(); 55 if (!Deterministic) { 56 auto ModTimeOrErr = OldMember.getLastModified(); 57 if (!ModTimeOrErr) 58 return ModTimeOrErr.takeError(); 59 M.ModTime = ModTimeOrErr.get(); 60 Expected<unsigned> UIDOrErr = OldMember.getUID(); 61 if (!UIDOrErr) 62 return UIDOrErr.takeError(); 63 M.UID = UIDOrErr.get(); 64 Expected<unsigned> GIDOrErr = OldMember.getGID(); 65 if (!GIDOrErr) 66 return GIDOrErr.takeError(); 67 M.GID = GIDOrErr.get(); 68 Expected<sys::fs::perms> AccessModeOrErr = OldMember.getAccessMode(); 69 if (!AccessModeOrErr) 70 return AccessModeOrErr.takeError(); 71 M.Perms = AccessModeOrErr.get(); 72 } 73 return std::move(M); 74} 75 76Expected<NewArchiveMember> NewArchiveMember::getFile(StringRef FileName, 77 bool Deterministic) { 78 sys::fs::file_status Status; 79 int FD; 80 if (auto EC = sys::fs::openFileForRead(FileName, FD)) 81 return errorCodeToError(EC); 82 assert(FD != -1); 83 84 if (auto EC = sys::fs::status(FD, Status)) 85 return errorCodeToError(EC); 86 87 // Opening a directory doesn't make sense. Let it fail. 88 // Linux cannot open directories with open(2), although 89 // cygwin and *bsd can. 90 if (Status.type() == sys::fs::file_type::directory_file) 91 return errorCodeToError(make_error_code(errc::is_a_directory)); 92 93 ErrorOr<std::unique_ptr<MemoryBuffer>> MemberBufferOrErr = 94 MemoryBuffer::getOpenFile(FD, FileName, Status.getSize(), false); 95 if (!MemberBufferOrErr) 96 return errorCodeToError(MemberBufferOrErr.getError()); 97 98 if (close(FD) != 0) 99 return errorCodeToError(std::error_code(errno, std::generic_category())); 100 101 NewArchiveMember M; 102 M.IsNew = true; 103 M.Buf = std::move(*MemberBufferOrErr); 104 M.MemberName = M.Buf->getBufferIdentifier(); 105 if (!Deterministic) { 106 M.ModTime = std::chrono::time_point_cast<std::chrono::seconds>( 107 Status.getLastModificationTime()); 108 M.UID = Status.getUser(); 109 M.GID = Status.getGroup(); 110 M.Perms = Status.permissions(); 111 } 112 return std::move(M); 113} 114 115template <typename T> 116static void printWithSpacePadding(raw_ostream &OS, T Data, unsigned Size) { 117 uint64_t OldPos = OS.tell(); 118 OS << Data; 119 unsigned SizeSoFar = OS.tell() - OldPos; 120 assert(SizeSoFar <= Size && "Data doesn't fit in Size"); 121 OS.indent(Size - SizeSoFar); 122} 123 124static bool isDarwin(object::Archive::Kind Kind) { 125 return Kind == object::Archive::K_DARWIN || 126 Kind == object::Archive::K_DARWIN64; 127} 128 129static bool isBSDLike(object::Archive::Kind Kind) { 130 switch (Kind) { 131 case object::Archive::K_GNU: 132 case object::Archive::K_GNU64: 133 return false; 134 case object::Archive::K_BSD: 135 case object::Archive::K_DARWIN: 136 case object::Archive::K_DARWIN64: 137 return true; 138 case object::Archive::K_COFF: 139 break; 140 } 141 llvm_unreachable("not supported for writting"); 142} 143 144template <class T> 145static void print(raw_ostream &Out, object::Archive::Kind Kind, T Val) { 146 support::endian::write(Out, Val, 147 isBSDLike(Kind) ? support::little : support::big); 148} 149 150static void printRestOfMemberHeader( 151 raw_ostream &Out, const sys::TimePoint<std::chrono::seconds> &ModTime, 152 unsigned UID, unsigned GID, unsigned Perms, unsigned Size) { 153 printWithSpacePadding(Out, sys::toTimeT(ModTime), 12); 154 155 // The format has only 6 chars for uid and gid. Truncate if the provided 156 // values don't fit. 157 printWithSpacePadding(Out, UID % 1000000, 6); 158 printWithSpacePadding(Out, GID % 1000000, 6); 159 160 printWithSpacePadding(Out, format("%o", Perms), 8); 161 printWithSpacePadding(Out, Size, 10); 162 Out << "`\n"; 163} 164 165static void 166printGNUSmallMemberHeader(raw_ostream &Out, StringRef Name, 167 const sys::TimePoint<std::chrono::seconds> &ModTime, 168 unsigned UID, unsigned GID, unsigned Perms, 169 unsigned Size) { 170 printWithSpacePadding(Out, Twine(Name) + "/", 16); 171 printRestOfMemberHeader(Out, ModTime, UID, GID, Perms, Size); 172} 173 174static void 175printBSDMemberHeader(raw_ostream &Out, uint64_t Pos, StringRef Name, 176 const sys::TimePoint<std::chrono::seconds> &ModTime, 177 unsigned UID, unsigned GID, unsigned Perms, 178 unsigned Size) { 179 uint64_t PosAfterHeader = Pos + 60 + Name.size(); 180 // Pad so that even 64 bit object files are aligned. 181 unsigned Pad = OffsetToAlignment(PosAfterHeader, 8); 182 unsigned NameWithPadding = Name.size() + Pad; 183 printWithSpacePadding(Out, Twine("#1/") + Twine(NameWithPadding), 16); 184 printRestOfMemberHeader(Out, ModTime, UID, GID, Perms, 185 NameWithPadding + Size); 186 Out << Name; 187 while (Pad--) 188 Out.write(uint8_t(0)); 189} 190 191static bool useStringTable(bool Thin, StringRef Name) { 192 return Thin || Name.size() >= 16 || Name.contains('/'); 193} 194 195// Compute the relative path from From to To. 196static std::string computeRelativePath(StringRef From, StringRef To) { 197 if (sys::path::is_absolute(From) || sys::path::is_absolute(To)) 198 return To; 199 200 StringRef DirFrom = sys::path::parent_path(From); 201 auto FromI = sys::path::begin(DirFrom); 202 auto ToI = sys::path::begin(To); 203 while (*FromI == *ToI) { 204 ++FromI; 205 ++ToI; 206 } 207 208 SmallString<128> Relative; 209 for (auto FromE = sys::path::end(DirFrom); FromI != FromE; ++FromI) 210 sys::path::append(Relative, ".."); 211 212 for (auto ToE = sys::path::end(To); ToI != ToE; ++ToI) 213 sys::path::append(Relative, *ToI); 214 215#ifdef _WIN32 216 // Replace backslashes with slashes so that the path is portable between *nix 217 // and Windows. 218 std::replace(Relative.begin(), Relative.end(), '\\', '/'); 219#endif 220 221 return Relative.str(); 222} 223 224static bool is64BitKind(object::Archive::Kind Kind) { 225 switch (Kind) { 226 case object::Archive::K_GNU: 227 case object::Archive::K_BSD: 228 case object::Archive::K_DARWIN: 229 case object::Archive::K_COFF: 230 return false; 231 case object::Archive::K_DARWIN64: 232 case object::Archive::K_GNU64: 233 return true; 234 } 235 llvm_unreachable("not supported for writting"); 236} 237 238static void addToStringTable(raw_ostream &Out, StringRef ArcName, 239 const NewArchiveMember &M, bool Thin) { 240 StringRef ID = M.Buf->getBufferIdentifier(); 241 if (Thin) { 242 if (M.IsNew) 243 Out << computeRelativePath(ArcName, ID); 244 else 245 Out << ID; 246 } else 247 Out << M.MemberName; 248 Out << "/\n"; 249} 250 251static void printMemberHeader(raw_ostream &Out, uint64_t Pos, 252 raw_ostream &StringTable, 253 StringMap<uint64_t> &MemberNames, 254 object::Archive::Kind Kind, bool Thin, 255 StringRef ArcName, const NewArchiveMember &M, 256 sys::TimePoint<std::chrono::seconds> ModTime, 257 unsigned Size) { 258 259 if (isBSDLike(Kind)) 260 return printBSDMemberHeader(Out, Pos, M.MemberName, ModTime, M.UID, M.GID, 261 M.Perms, Size); 262 if (!useStringTable(Thin, M.MemberName)) 263 return printGNUSmallMemberHeader(Out, M.MemberName, ModTime, M.UID, M.GID, 264 M.Perms, Size); 265 Out << '/'; 266 uint64_t NamePos; 267 if (Thin) { 268 NamePos = StringTable.tell(); 269 addToStringTable(StringTable, ArcName, M, Thin); 270 } else { 271 auto Insertion = MemberNames.insert({M.MemberName, uint64_t(0)}); 272 if (Insertion.second) { 273 Insertion.first->second = StringTable.tell(); 274 addToStringTable(StringTable, ArcName, M, Thin); 275 } 276 NamePos = Insertion.first->second; 277 } 278 printWithSpacePadding(Out, NamePos, 15); 279 printRestOfMemberHeader(Out, ModTime, M.UID, M.GID, M.Perms, Size); 280} 281 282namespace { 283struct MemberData { 284 std::vector<unsigned> Symbols; 285 std::string Header; 286 StringRef Data; 287 StringRef Padding; 288}; 289} // namespace 290 291static MemberData computeStringTable(StringRef Names) { 292 unsigned Size = Names.size(); 293 unsigned Pad = OffsetToAlignment(Size, 2); 294 std::string Header; 295 raw_string_ostream Out(Header); 296 printWithSpacePadding(Out, "//", 48); 297 printWithSpacePadding(Out, Size + Pad, 10); 298 Out << "`\n"; 299 Out.flush(); 300 return {{}, std::move(Header), Names, Pad ? "\n" : ""}; 301} 302 303static sys::TimePoint<std::chrono::seconds> now(bool Deterministic) { 304 using namespace std::chrono; 305 306 if (!Deterministic) 307 return time_point_cast<seconds>(system_clock::now()); 308 return sys::TimePoint<seconds>(); 309} 310 311static bool isArchiveSymbol(const object::BasicSymbolRef &S) { 312 uint32_t Symflags = S.getFlags(); 313 if (Symflags & object::SymbolRef::SF_FormatSpecific) 314 return false; 315 if (!(Symflags & object::SymbolRef::SF_Global)) 316 return false; 317 if (Symflags & object::SymbolRef::SF_Undefined) 318 return false; 319 return true; 320} 321 322static void printNBits(raw_ostream &Out, object::Archive::Kind Kind, 323 uint64_t Val) { 324 if (is64BitKind(Kind)) 325 print<uint64_t>(Out, Kind, Val); 326 else 327 print<uint32_t>(Out, Kind, Val); 328} 329 330static void writeSymbolTable(raw_ostream &Out, object::Archive::Kind Kind, 331 bool Deterministic, ArrayRef<MemberData> Members, 332 StringRef StringTable) { 333 // We don't write a symbol table on an archive with no members -- except on 334 // Darwin, where the linker will abort unless the archive has a symbol table. 335 if (StringTable.empty() && !isDarwin(Kind)) 336 return; 337 338 unsigned NumSyms = 0; 339 for (const MemberData &M : Members) 340 NumSyms += M.Symbols.size(); 341 342 unsigned Size = 0; 343 unsigned OffsetSize = is64BitKind(Kind) ? sizeof(uint64_t) : sizeof(uint32_t); 344 345 Size += OffsetSize; // Number of entries 346 if (isBSDLike(Kind)) 347 Size += NumSyms * OffsetSize * 2; // Table 348 else 349 Size += NumSyms * OffsetSize; // Table 350 if (isBSDLike(Kind)) 351 Size += OffsetSize; // byte count 352 Size += StringTable.size(); 353 // ld64 expects the members to be 8-byte aligned for 64-bit content and at 354 // least 4-byte aligned for 32-bit content. Opt for the larger encoding 355 // uniformly. 356 // We do this for all bsd formats because it simplifies aligning members. 357 unsigned Alignment = isBSDLike(Kind) ? 8 : 2; 358 unsigned Pad = OffsetToAlignment(Size, Alignment); 359 Size += Pad; 360 361 if (isBSDLike(Kind)) { 362 const char *Name = is64BitKind(Kind) ? "__.SYMDEF_64" : "__.SYMDEF"; 363 printBSDMemberHeader(Out, Out.tell(), Name, now(Deterministic), 0, 0, 0, 364 Size); 365 } else { 366 const char *Name = is64BitKind(Kind) ? "/SYM64" : ""; 367 printGNUSmallMemberHeader(Out, Name, now(Deterministic), 0, 0, 0, Size); 368 } 369 370 uint64_t Pos = Out.tell() + Size; 371 372 if (isBSDLike(Kind)) 373 printNBits(Out, Kind, NumSyms * 2 * OffsetSize); 374 else 375 printNBits(Out, Kind, NumSyms); 376 377 for (const MemberData &M : Members) { 378 for (unsigned StringOffset : M.Symbols) { 379 if (isBSDLike(Kind)) 380 printNBits(Out, Kind, StringOffset); 381 printNBits(Out, Kind, Pos); // member offset 382 } 383 Pos += M.Header.size() + M.Data.size() + M.Padding.size(); 384 } 385 386 if (isBSDLike(Kind)) 387 // byte count of the string table 388 printNBits(Out, Kind, StringTable.size()); 389 Out << StringTable; 390 391 while (Pad--) 392 Out.write(uint8_t(0)); 393} 394 395static Expected<std::vector<unsigned>> 396getSymbols(MemoryBufferRef Buf, raw_ostream &SymNames, bool &HasObject) { 397 std::vector<unsigned> Ret; 398 399 // In the scenario when LLVMContext is populated SymbolicFile will contain a 400 // reference to it, thus SymbolicFile should be destroyed first. 401 LLVMContext Context; 402 std::unique_ptr<object::SymbolicFile> Obj; 403 if (identify_magic(Buf.getBuffer()) == file_magic::bitcode) { 404 auto ObjOrErr = object::SymbolicFile::createSymbolicFile( 405 Buf, file_magic::bitcode, &Context); 406 if (!ObjOrErr) { 407 // FIXME: check only for "not an object file" errors. 408 consumeError(ObjOrErr.takeError()); 409 return Ret; 410 } 411 Obj = std::move(*ObjOrErr); 412 } else { 413 auto ObjOrErr = object::SymbolicFile::createSymbolicFile(Buf); 414 if (!ObjOrErr) { 415 // FIXME: check only for "not an object file" errors. 416 consumeError(ObjOrErr.takeError()); 417 return Ret; 418 } 419 Obj = std::move(*ObjOrErr); 420 } 421 422 HasObject = true; 423 for (const object::BasicSymbolRef &S : Obj->symbols()) { 424 if (!isArchiveSymbol(S)) 425 continue; 426 Ret.push_back(SymNames.tell()); 427 if (auto EC = S.printName(SymNames)) 428 return errorCodeToError(EC); 429 SymNames << '\0'; 430 } 431 return Ret; 432} 433 434static Expected<std::vector<MemberData>> 435computeMemberData(raw_ostream &StringTable, raw_ostream &SymNames, 436 object::Archive::Kind Kind, bool Thin, StringRef ArcName, 437 bool Deterministic, ArrayRef<NewArchiveMember> NewMembers) { 438 static char PaddingData[8] = {'\n', '\n', '\n', '\n', '\n', '\n', '\n', '\n'}; 439 440 // This ignores the symbol table, but we only need the value mod 8 and the 441 // symbol table is aligned to be a multiple of 8 bytes 442 uint64_t Pos = 0; 443 444 std::vector<MemberData> Ret; 445 bool HasObject = false; 446 447 // Deduplicate long member names in the string table and reuse earlier name 448 // offsets. This especially saves space for COFF Import libraries where all 449 // members have the same name. 450 StringMap<uint64_t> MemberNames; 451 452 // UniqueTimestamps is a special case to improve debugging on Darwin: 453 // 454 // The Darwin linker does not link debug info into the final 455 // binary. Instead, it emits entries of type N_OSO in in the output 456 // binary's symbol table, containing references to the linked-in 457 // object files. Using that reference, the debugger can read the 458 // debug data directly from the object files. Alternatively, an 459 // invocation of 'dsymutil' will link the debug data from the object 460 // files into a dSYM bundle, which can be loaded by the debugger, 461 // instead of the object files. 462 // 463 // For an object file, the N_OSO entries contain the absolute path 464 // path to the file, and the file's timestamp. For an object 465 // included in an archive, the path is formatted like 466 // "/absolute/path/to/archive.a(member.o)", and the timestamp is the 467 // archive member's timestamp, rather than the archive's timestamp. 468 // 469 // However, this doesn't always uniquely identify an object within 470 // an archive -- an archive file can have multiple entries with the 471 // same filename. (This will happen commonly if the original object 472 // files started in different directories.) The only way they get 473 // distinguished, then, is via the timestamp. But this process is 474 // unable to find the correct object file in the archive when there 475 // are two files of the same name and timestamp. 476 // 477 // Additionally, timestamp==0 is treated specially, and causes the 478 // timestamp to be ignored as a match criteria. 479 // 480 // That will "usually" work out okay when creating an archive not in 481 // deterministic timestamp mode, because the objects will probably 482 // have been created at different timestamps. 483 // 484 // To ameliorate this problem, in deterministic archive mode (which 485 // is the default), on Darwin we will emit a unique non-zero 486 // timestamp for each entry with a duplicated name. This is still 487 // deterministic: the only thing affecting that timestamp is the 488 // order of the files in the resultant archive. 489 // 490 // See also the functions that handle the lookup: 491 // in lldb: ObjectContainerBSDArchive::Archive::FindObject() 492 // in llvm/tools/dsymutil: BinaryHolder::GetArchiveMemberBuffers(). 493 bool UniqueTimestamps = Deterministic && isDarwin(Kind); 494 std::map<StringRef, unsigned> FilenameCount; 495 if (UniqueTimestamps) { 496 for (const NewArchiveMember &M : NewMembers) 497 FilenameCount[M.MemberName]++; 498 for (auto &Entry : FilenameCount) 499 Entry.second = Entry.second > 1 ? 1 : 0; 500 } 501 502 for (const NewArchiveMember &M : NewMembers) { 503 std::string Header; 504 raw_string_ostream Out(Header); 505 506 MemoryBufferRef Buf = M.Buf->getMemBufferRef(); 507 StringRef Data = Thin ? "" : Buf.getBuffer(); 508 509 // ld64 expects the members to be 8-byte aligned for 64-bit content and at 510 // least 4-byte aligned for 32-bit content. Opt for the larger encoding 511 // uniformly. This matches the behaviour with cctools and ensures that ld64 512 // is happy with archives that we generate. 513 unsigned MemberPadding = 514 isDarwin(Kind) ? OffsetToAlignment(Data.size(), 8) : 0; 515 unsigned TailPadding = OffsetToAlignment(Data.size() + MemberPadding, 2); 516 StringRef Padding = StringRef(PaddingData, MemberPadding + TailPadding); 517 518 sys::TimePoint<std::chrono::seconds> ModTime; 519 if (UniqueTimestamps) 520 // Increment timestamp for each file of a given name. 521 ModTime = sys::toTimePoint(FilenameCount[M.MemberName]++); 522 else 523 ModTime = M.ModTime; 524 printMemberHeader(Out, Pos, StringTable, MemberNames, Kind, Thin, ArcName, 525 M, ModTime, Buf.getBufferSize() + MemberPadding); 526 Out.flush(); 527 528 Expected<std::vector<unsigned>> Symbols = 529 getSymbols(Buf, SymNames, HasObject); 530 if (auto E = Symbols.takeError()) 531 return std::move(E); 532 533 Pos += Header.size() + Data.size() + Padding.size(); 534 Ret.push_back({std::move(*Symbols), std::move(Header), Data, Padding}); 535 } 536 // If there are no symbols, emit an empty symbol table, to satisfy Solaris 537 // tools, older versions of which expect a symbol table in a non-empty 538 // archive, regardless of whether there are any symbols in it. 539 if (HasObject && SymNames.tell() == 0) 540 SymNames << '\0' << '\0' << '\0'; 541 return Ret; 542} 543 544Error llvm::writeArchive(StringRef ArcName, 545 ArrayRef<NewArchiveMember> NewMembers, 546 bool WriteSymtab, object::Archive::Kind Kind, 547 bool Deterministic, bool Thin, 548 std::unique_ptr<MemoryBuffer> OldArchiveBuf) { 549 assert((!Thin || !isBSDLike(Kind)) && "Only the gnu format has a thin mode"); 550 551 SmallString<0> SymNamesBuf; 552 raw_svector_ostream SymNames(SymNamesBuf); 553 SmallString<0> StringTableBuf; 554 raw_svector_ostream StringTable(StringTableBuf); 555 556 Expected<std::vector<MemberData>> DataOrErr = computeMemberData( 557 StringTable, SymNames, Kind, Thin, ArcName, Deterministic, NewMembers); 558 if (Error E = DataOrErr.takeError()) 559 return E; 560 std::vector<MemberData> &Data = *DataOrErr; 561 562 if (!StringTableBuf.empty()) 563 Data.insert(Data.begin(), computeStringTable(StringTableBuf)); 564 565 // We would like to detect if we need to switch to a 64-bit symbol table. 566 if (WriteSymtab) { 567 uint64_t MaxOffset = 0; 568 uint64_t LastOffset = MaxOffset; 569 for (const auto &M : Data) { 570 // Record the start of the member's offset 571 LastOffset = MaxOffset; 572 // Account for the size of each part associated with the member. 573 MaxOffset += M.Header.size() + M.Data.size() + M.Padding.size(); 574 // We assume 32-bit symbols to see if 32-bit symbols are possible or not. 575 MaxOffset += M.Symbols.size() * 4; 576 } 577 578 // The SYM64 format is used when an archive's member offsets are larger than 579 // 32-bits can hold. The need for this shift in format is detected by 580 // writeArchive. To test this we need to generate a file with a member that 581 // has an offset larger than 32-bits but this demands a very slow test. To 582 // speed the test up we use this environment variable to pretend like the 583 // cutoff happens before 32-bits and instead happens at some much smaller 584 // value. 585 const char *Sym64Env = std::getenv("SYM64_THRESHOLD"); 586 int Sym64Threshold = 32; 587 if (Sym64Env) 588 StringRef(Sym64Env).getAsInteger(10, Sym64Threshold); 589 590 // If LastOffset isn't going to fit in a 32-bit varible we need to switch 591 // to 64-bit. Note that the file can be larger than 4GB as long as the last 592 // member starts before the 4GB offset. 593 if (LastOffset >= (1ULL << Sym64Threshold)) { 594 if (Kind == object::Archive::K_DARWIN) 595 Kind = object::Archive::K_DARWIN64; 596 else 597 Kind = object::Archive::K_GNU64; 598 } 599 } 600 601 Expected<sys::fs::TempFile> Temp = 602 sys::fs::TempFile::create(ArcName + ".temp-archive-%%%%%%%.a"); 603 if (!Temp) 604 return Temp.takeError(); 605 606 raw_fd_ostream Out(Temp->FD, false); 607 if (Thin) 608 Out << "!<thin>\n"; 609 else 610 Out << "!<arch>\n"; 611 612 if (WriteSymtab) 613 writeSymbolTable(Out, Kind, Deterministic, Data, SymNamesBuf); 614 615 for (const MemberData &M : Data) 616 Out << M.Header << M.Data << M.Padding; 617 618 Out.flush(); 619 620 // At this point, we no longer need whatever backing memory 621 // was used to generate the NewMembers. On Windows, this buffer 622 // could be a mapped view of the file we want to replace (if 623 // we're updating an existing archive, say). In that case, the 624 // rename would still succeed, but it would leave behind a 625 // temporary file (actually the original file renamed) because 626 // a file cannot be deleted while there's a handle open on it, 627 // only renamed. So by freeing this buffer, this ensures that 628 // the last open handle on the destination file, if any, is 629 // closed before we attempt to rename. 630 OldArchiveBuf.reset(); 631 632 return Temp->keep(ArcName); 633} 634