lib/Object/Archive.cpp

   1 //===- Archive.cpp - ar File Format 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 ArchiveObjectFile class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/Object/Archive.h"
  14 #include "llvm/ADT/Optional.h"
  15 #include "llvm/ADT/SmallString.h"
  16 #include "llvm/ADT/StringRef.h"
  17 #include "llvm/ADT/Twine.h"
  18 #include "llvm/Object/Binary.h"
  19 #include "llvm/Object/Error.h"
  20 #include "llvm/Support/Chrono.h"
  21 #include "llvm/Support/Endian.h"
  22 #include "llvm/Support/Error.h"
  23 #include "llvm/Support/ErrorOr.h"
  24 #include "llvm/Support/FileSystem.h"
  25 #include "llvm/Support/MemoryBuffer.h"
  26 #include "llvm/Support/Path.h"
  27 #include "llvm/Support/raw_ostream.h"
  28 #include <algorithm>
  29 #include <cassert>
  30 #include <cstddef>
  31 #include <cstdint>
  32 #include <cstring>
  33 #include <memory>
  34 #include <string>
  35 #include <system_error>
  36
  37 using namespace llvm;
  38 using namespace object;
  39 using namespace llvm::support::endian;
  40
  41 static const char *const Magic = "!<arch>\n";
  42 static const char *const ThinMagic = "!<thin>\n";
  43
  44 void Archive::anchor() {}
  45
  46 static Error
  47 malformedError(Twine Msg) {
  48   std::string StringMsg = "truncated or malformed archive (" + Msg.str() + ")";
  49   return make_error<GenericBinaryError>(std::move(StringMsg),
  50                                         object_error::parse_failed);
  51 }
  52
  53 ArchiveMemberHeader::ArchiveMemberHeader(const Archive *Parent,
  54                                          const char *RawHeaderPtr,
  55                                          uint64_t Size, Error *Err)
  56     : Parent(Parent),
  57       ArMemHdr(reinterpret_cast<const ArMemHdrType *>(RawHeaderPtr)) {
  58   if (RawHeaderPtr == nullptr)
  59     return;
  60   ErrorAsOutParameter ErrAsOutParam(Err);
  61
  62   if (Size < sizeof(ArMemHdrType)) {
  63     if (Err) {
  64       std::string Msg("remaining size of archive too small for next archive "
  65                       "member header ");
  66       Expected<StringRef> NameOrErr = getName(Size);
  67       if (!NameOrErr) {
  68         consumeError(NameOrErr.takeError());
  69         uint64_t Offset = RawHeaderPtr - Parent->getData().data();
  70         *Err = malformedError(Msg + "at offset " + Twine(Offset));
  71       } else
  72         *Err = malformedError(Msg + "for " + NameOrErr.get());
  73     }
  74     return;
  75   }
  76   if (ArMemHdr->Terminator[0] != '`' || ArMemHdr->Terminator[1] != '\n') {
  77     if (Err) {
  78       std::string Buf;
  79       raw_string_ostream OS(Buf);
  80       OS.write_escaped(StringRef(ArMemHdr->Terminator,
  81                                  sizeof(ArMemHdr->Terminator)));
  82       OS.flush();
  83       std::string Msg("terminator characters in archive member \"" + Buf +
  84                       "\" not the correct \"`\\n\" values for the archive "
  85                       "member header ");
  86       Expected<StringRef> NameOrErr = getName(Size);
  87       if (!NameOrErr) {
  88         consumeError(NameOrErr.takeError());
  89         uint64_t Offset = RawHeaderPtr - Parent->getData().data();
  90         *Err = malformedError(Msg + "at offset " + Twine(Offset));
  91       } else
  92         *Err = malformedError(Msg + "for " + NameOrErr.get());
  93     }
  94     return;
  95   }
  96 }
  97
  98 // This gets the raw name from the ArMemHdr->Name field and checks that it is
  99 // valid for the kind of archive.  If it is not valid it returns an Error.
 100 Expected<StringRef> ArchiveMemberHeader::getRawName() const {
 101   char EndCond;
 102   auto Kind = Parent->kind();
 103   if (Kind == Archive::K_BSD || Kind == Archive::K_DARWIN64) {
 104     if (ArMemHdr->Name[0] == ' ') {
 105       uint64_t Offset = reinterpret_cast<const char *>(ArMemHdr) -
 106                         Parent->getData().data();
 107       return malformedError("name contains a leading space for archive member "
 108                             "header at offset " + Twine(Offset));
 109     }
 110     EndCond = ' ';
 111   }
 112   else if (ArMemHdr->Name[0] == '/' || ArMemHdr->Name[0] == '#')
 113     EndCond = ' ';
 114   else
 115     EndCond = '/';
 116   StringRef::size_type end =
 117       StringRef(ArMemHdr->Name, sizeof(ArMemHdr->Name)).find(EndCond);
 118   if (end == StringRef::npos)
 119     end = sizeof(ArMemHdr->Name);
 120   assert(end <= sizeof(ArMemHdr->Name) && end > 0);
 121   // Don't include the EndCond if there is one.
 122   return StringRef(ArMemHdr->Name, end);
 123 }
 124
 125 // This gets the name looking up long names. Size is the size of the archive
 126 // member including the header, so the size of any name following the header
 127 // is checked to make sure it does not overflow.
 128 Expected<StringRef> ArchiveMemberHeader::getName(uint64_t Size) const {
 129
 130   // This can be called from the ArchiveMemberHeader constructor when the
 131   // archive header is truncated to produce an error message with the name.
 132   // Make sure the name field is not truncated.
 133   if (Size < offsetof(ArMemHdrType, Name) + sizeof(ArMemHdr->Name)) {
 134     uint64_t ArchiveOffset = reinterpret_cast<const char *>(ArMemHdr) -
 135                       Parent->getData().data();
 136     return malformedError("archive header truncated before the name field "
 137                           "for archive member header at offset " +
 138                           Twine(ArchiveOffset));
 139   }
 140
 141   // The raw name itself can be invalid.
 142   Expected<StringRef> NameOrErr = getRawName();
 143   if (!NameOrErr)
 144     return NameOrErr.takeError();
 145   StringRef Name = NameOrErr.get();
 146
 147   // Check if it's a special name.
 148   if (Name[0] == '/') {
 149     if (Name.size() == 1) // Linker member.
 150       return Name;
 151     if (Name.size() == 2 && Name[1] == '/') // String table.
 152       return Name;
 153     // It's a long name.
 154     // Get the string table offset.
 155     std::size_t StringOffset;
 156     if (Name.substr(1).rtrim(' ').getAsInteger(10, StringOffset)) {
 157       std::string Buf;
 158       raw_string_ostream OS(Buf);
 159       OS.write_escaped(Name.substr(1).rtrim(' '));
 160       OS.flush();
 161       uint64_t ArchiveOffset = reinterpret_cast<const char *>(ArMemHdr) -
 162                                Parent->getData().data();
 163       return malformedError("long name offset characters after the '/' are "
 164                             "not all decimal numbers: '" + Buf + "' for "
 165                             "archive member header at offset " +
 166                             Twine(ArchiveOffset));
 167     }
 168
 169     // Verify it.
 170     if (StringOffset >= Parent->getStringTable().size()) {
 171       uint64_t ArchiveOffset = reinterpret_cast<const char *>(ArMemHdr) -
 172                                Parent->getData().data();
 173       return malformedError("long name offset " + Twine(StringOffset) + " past "
 174                             "the end of the string table for archive member "
 175                             "header at offset " + Twine(ArchiveOffset));
 176     }
 177
 178     // GNU long file names end with a "/\n".
 179     if (Parent->kind() == Archive::K_GNU ||
 180         Parent->kind() == Archive::K_GNU64) {
 181       size_t End = Parent->getStringTable().find('\n', /*From=*/StringOffset);
 182       if (End == StringRef::npos || End < 1 ||
 183           Parent->getStringTable()[End - 1] != '/') {
 184         return malformedError("string table at long name offset " +
 185                               Twine(StringOffset) + "not terminated");
 186       }
 187       return Parent->getStringTable().slice(StringOffset, End - 1);
 188     }
 189     return Parent->getStringTable().begin() + StringOffset;
 190   }
 191
 192   if (Name.startswith("#1/")) {
 193     uint64_t NameLength;
 194     if (Name.substr(3).rtrim(' ').getAsInteger(10, NameLength)) {
 195       std::string Buf;
 196       raw_string_ostream OS(Buf);
 197       OS.write_escaped(Name.substr(3).rtrim(' '));
 198       OS.flush();
 199       uint64_t ArchiveOffset = reinterpret_cast<const char *>(ArMemHdr) -
 200                         Parent->getData().data();
 201       return malformedError("long name length characters after the #1/ are "
 202                             "not all decimal numbers: '" + Buf + "' for "
 203                             "archive member header at offset " +
 204                             Twine(ArchiveOffset));
 205     }
 206     if (getSizeOf() + NameLength > Size) {
 207       uint64_t ArchiveOffset = reinterpret_cast<const char *>(ArMemHdr) -
 208                         Parent->getData().data();
 209       return malformedError("long name length: " + Twine(NameLength) +
 210                             " extends past the end of the member or archive "
 211                             "for archive member header at offset " +
 212                             Twine(ArchiveOffset));
 213     }
 214     return StringRef(reinterpret_cast<const char *>(ArMemHdr) + getSizeOf(),
 215                      NameLength).rtrim('\0');
 216   }
 217
 218   // It is not a long name so trim the blanks at the end of the name.
 219   if (Name[Name.size() - 1] != '/')
 220     return Name.rtrim(' ');
 221
 222   // It's a simple name.
 223   return Name.drop_back(1);
 224 }
 225
 226 Expected<uint64_t> ArchiveMemberHeader::getSize() const {
 227   uint64_t Ret;
 228   if (StringRef(ArMemHdr->Size,
 229                 sizeof(ArMemHdr->Size)).rtrim(" ").getAsInteger(10, Ret)) {
 230     std::string Buf;
 231     raw_string_ostream OS(Buf);
 232     OS.write_escaped(StringRef(ArMemHdr->Size,
 233                                sizeof(ArMemHdr->Size)).rtrim(" "));
 234     OS.flush();
 235     uint64_t Offset = reinterpret_cast<const char *>(ArMemHdr) -
 236                       Parent->getData().data();
 237     return malformedError("characters in size field in archive header are not "
 238                           "all decimal numbers: '" + Buf + "' for archive "
 239                           "member header at offset " + Twine(Offset));
 240   }
 241   return Ret;
 242 }
 243
 244 Expected<sys::fs::perms> ArchiveMemberHeader::getAccessMode() const {
 245   unsigned Ret;
 246   if (StringRef(ArMemHdr->AccessMode,
 247                 sizeof(ArMemHdr->AccessMode)).rtrim(' ').getAsInteger(8, Ret)) {
 248     std::string Buf;
 249     raw_string_ostream OS(Buf);
 250     OS.write_escaped(StringRef(ArMemHdr->AccessMode,
 251                                sizeof(ArMemHdr->AccessMode)).rtrim(" "));
 252     OS.flush();
 253     uint64_t Offset = reinterpret_cast<const char *>(ArMemHdr) -
 254                       Parent->getData().data();
 255     return malformedError("characters in AccessMode field in archive header "
 256                           "are not all decimal numbers: '" + Buf + "' for the "
 257                           "archive member header at offset " + Twine(Offset));
 258   }
 259   return static_cast<sys::fs::perms>(Ret);
 260 }
 261
 262 Expected<sys::TimePoint<std::chrono::seconds>>
 263 ArchiveMemberHeader::getLastModified() const {
 264   unsigned Seconds;
 265   if (StringRef(ArMemHdr->LastModified,
 266                 sizeof(ArMemHdr->LastModified)).rtrim(' ')
 267           .getAsInteger(10, Seconds)) {
 268     std::string Buf;
 269     raw_string_ostream OS(Buf);
 270     OS.write_escaped(StringRef(ArMemHdr->LastModified,
 271                                sizeof(ArMemHdr->LastModified)).rtrim(" "));
 272     OS.flush();
 273     uint64_t Offset = reinterpret_cast<const char *>(ArMemHdr) -
 274                       Parent->getData().data();
 275     return malformedError("characters in LastModified field in archive header "
 276                           "are not all decimal numbers: '" + Buf + "' for the "
 277                           "archive member header at offset " + Twine(Offset));
 278   }
 279
 280   return sys::toTimePoint(Seconds);
 281 }
 282
 283 Expected<unsigned> ArchiveMemberHeader::getUID() const {
 284   unsigned Ret;
 285   StringRef User = StringRef(ArMemHdr->UID, sizeof(ArMemHdr->UID)).rtrim(' ');
 286   if (User.empty())
 287     return 0;
 288   if (User.getAsInteger(10, Ret)) {
 289     std::string Buf;
 290     raw_string_ostream OS(Buf);
 291     OS.write_escaped(User);
 292     OS.flush();
 293     uint64_t Offset = reinterpret_cast<const char *>(ArMemHdr) -
 294                       Parent->getData().data();
 295     return malformedError("characters in UID field in archive header "
 296                           "are not all decimal numbers: '" + Buf + "' for the "
 297                           "archive member header at offset " + Twine(Offset));
 298   }
 299   return Ret;
 300 }
 301
 302 Expected<unsigned> ArchiveMemberHeader::getGID() const {
 303   unsigned Ret;
 304   StringRef Group = StringRef(ArMemHdr->GID, sizeof(ArMemHdr->GID)).rtrim(' ');
 305   if (Group.empty())
 306     return 0;
 307   if (Group.getAsInteger(10, Ret)) {
 308     std::string Buf;
 309     raw_string_ostream OS(Buf);
 310     OS.write_escaped(Group);
 311     OS.flush();
 312     uint64_t Offset = reinterpret_cast<const char *>(ArMemHdr) -
 313                       Parent->getData().data();
 314     return malformedError("characters in GID field in archive header "
 315                           "are not all decimal numbers: '" + Buf + "' for the "
 316                           "archive member header at offset " + Twine(Offset));
 317   }
 318   return Ret;
 319 }
 320
 321 Archive::Child::Child(const Archive *Parent, StringRef Data,
 322                       uint16_t StartOfFile)
 323     : Parent(Parent), Header(Parent, Data.data(), Data.size(), nullptr),
 324       Data(Data), StartOfFile(StartOfFile) {
 325 }
 326
 327 Archive::Child::Child(const Archive *Parent, const char *Start, Error *Err)
 328     : Parent(Parent),
 329       Header(Parent, Start,
 330              Parent
 331                ? Parent->getData().size() - (Start - Parent->getData().data())
 332                : 0, Err) {
 333   if (!Start)
 334     return;
 335
 336   // If we are pointed to real data, Start is not a nullptr, then there must be
 337   // a non-null Err pointer available to report malformed data on.  Only in
 338   // the case sentinel value is being constructed is Err is permitted to be a
 339   // nullptr.
 340   assert(Err && "Err can't be nullptr if Start is not a nullptr");
 341
 342   ErrorAsOutParameter ErrAsOutParam(Err);
 343
 344   // If there was an error in the construction of the Header
 345   // then just return with the error now set.
 346   if (*Err)
 347     return;
 348
 349   uint64_t Size = Header.getSizeOf();
 350   Data = StringRef(Start, Size);
 351   Expected<bool> isThinOrErr = isThinMember();
 352   if (!isThinOrErr) {
 353     *Err = isThinOrErr.takeError();
 354     return;
 355   }
 356   bool isThin = isThinOrErr.get();
 357   if (!isThin) {
 358     Expected<uint64_t> MemberSize = getRawSize();
 359     if (!MemberSize) {
 360       *Err = MemberSize.takeError();
 361       return;
 362     }
 363     Size += MemberSize.get();
 364     Data = StringRef(Start, Size);
 365   }
 366
 367   // Setup StartOfFile and PaddingBytes.
 368   StartOfFile = Header.getSizeOf();
 369   // Don't include attached name.
 370   Expected<StringRef> NameOrErr = getRawName();
 371   if (!NameOrErr){
 372     *Err = NameOrErr.takeError();
 373     return;
 374   }
 375   StringRef Name = NameOrErr.get();
 376   if (Name.startswith("#1/")) {
 377     uint64_t NameSize;
 378     if (Name.substr(3).rtrim(' ').getAsInteger(10, NameSize)) {
 379       std::string Buf;
 380       raw_string_ostream OS(Buf);
 381       OS.write_escaped(Name.substr(3).rtrim(' '));
 382       OS.flush();
 383       uint64_t Offset = Start - Parent->getData().data();
 384       *Err = malformedError("long name length characters after the #1/ are "
 385                             "not all decimal numbers: '" + Buf + "' for "
 386                             "archive member header at offset " +
 387                             Twine(Offset));
 388       return;
 389     }
 390     StartOfFile += NameSize;
 391   }
 392 }
 393
 394 Expected<uint64_t> Archive::Child::getSize() const {
 395   if (Parent->IsThin) {
 396     Expected<uint32_t> Size = Header.getSize();
 397     if (!Size)
 398       return Size.takeError();
 399     return Size.get();
 400   }
 401   return Data.size() - StartOfFile;
 402 }
 403
 404 Expected<uint64_t> Archive::Child::getRawSize() const {
 405   return Header.getSize();
 406 }
 407
 408 Expected<bool> Archive::Child::isThinMember() const {
 409   Expected<StringRef> NameOrErr = Header.getRawName();
 410   if (!NameOrErr)
 411     return NameOrErr.takeError();
 412   StringRef Name = NameOrErr.get();
 413   return Parent->IsThin && Name != "/" && Name != "//";
 414 }
 415
 416 Expected<std::string> Archive::Child::getFullName() const {
 417   Expected<bool> isThin = isThinMember();
 418   if (!isThin)
 419     return isThin.takeError();
 420   assert(isThin.get());
 421   Expected<StringRef> NameOrErr = getName();
 422   if (!NameOrErr)
 423     return NameOrErr.takeError();
 424   StringRef Name = *NameOrErr;
 425   if (sys::path::is_absolute(Name))
 426     return Name;
 427
 428   SmallString<128> FullName = sys::path::parent_path(
 429       Parent->getMemoryBufferRef().getBufferIdentifier());
 430   sys::path::append(FullName, Name);
 431   return StringRef(FullName);
 432 }
 433
 434 Expected<StringRef> Archive::Child::getBuffer() const {
 435   Expected<bool> isThinOrErr = isThinMember();
 436   if (!isThinOrErr)
 437     return isThinOrErr.takeError();
 438   bool isThin = isThinOrErr.get();
 439   if (!isThin) {
 440     Expected<uint32_t> Size = getSize();
 441     if (!Size)
 442       return Size.takeError();
 443     return StringRef(Data.data() + StartOfFile, Size.get());
 444   }
 445   Expected<std::string> FullNameOrErr = getFullName();
 446   if (!FullNameOrErr)
 447     return FullNameOrErr.takeError();
 448   const std::string &FullName = *FullNameOrErr;
 449   ErrorOr<std::unique_ptr<MemoryBuffer>> Buf = MemoryBuffer::getFile(FullName);
 450   if (std::error_code EC = Buf.getError())
 451     return errorCodeToError(EC);
 452   Parent->ThinBuffers.push_back(std::move(*Buf));
 453   return Parent->ThinBuffers.back()->getBuffer();
 454 }
 455
 456 Expected<Archive::Child> Archive::Child::getNext() const {
 457   size_t SpaceToSkip = Data.size();
 458   // If it's odd, add 1 to make it even.
 459   if (SpaceToSkip & 1)
 460     ++SpaceToSkip;
 461
 462   const char *NextLoc = Data.data() + SpaceToSkip;
 463
 464   // Check to see if this is at the end of the archive.
 465   if (NextLoc == Parent->Data.getBufferEnd())
 466     return Child(nullptr, nullptr, nullptr);
 467
 468   // Check to see if this is past the end of the archive.
 469   if (NextLoc > Parent->Data.getBufferEnd()) {
 470     std::string Msg("offset to next archive member past the end of the archive "
 471                     "after member ");
 472     Expected<StringRef> NameOrErr = getName();
 473     if (!NameOrErr) {
 474       consumeError(NameOrErr.takeError());
 475       uint64_t Offset = Data.data() - Parent->getData().data();
 476       return malformedError(Msg + "at offset " + Twine(Offset));
 477     } else
 478       return malformedError(Msg + NameOrErr.get());
 479   }
 480
 481   Error Err = Error::success();
 482   Child Ret(Parent, NextLoc, &Err);
 483   if (Err)
 484     return std::move(Err);
 485   return Ret;
 486 }
 487
 488 uint64_t Archive::Child::getChildOffset() const {
 489   const char *a = Parent->Data.getBuffer().data();
 490   const char *c = Data.data();
 491   uint64_t offset = c - a;
 492   return offset;
 493 }
 494
 495 Expected<StringRef> Archive::Child::getName() const {
 496   Expected<uint64_t> RawSizeOrErr = getRawSize();
 497   if (!RawSizeOrErr)
 498     return RawSizeOrErr.takeError();
 499   uint64_t RawSize = RawSizeOrErr.get();
 500   Expected<StringRef> NameOrErr = Header.getName(Header.getSizeOf() + RawSize);
 501   if (!NameOrErr)
 502     return NameOrErr.takeError();
 503   StringRef Name = NameOrErr.get();
 504   return Name;
 505 }
 506
 507 Expected<MemoryBufferRef> Archive::Child::getMemoryBufferRef() const {
 508   Expected<StringRef> NameOrErr = getName();
 509   if (!NameOrErr)
 510     return NameOrErr.takeError();
 511   StringRef Name = NameOrErr.get();
 512   Expected<StringRef> Buf = getBuffer();
 513   if (!Buf)
 514     return createFileError(Name, Buf.takeError());
 515   return MemoryBufferRef(*Buf, Name);
 516 }
 517
 518 Expected<std::unique_ptr<Binary>>
 519 Archive::Child::getAsBinary(LLVMContext *Context) const {
 520   Expected<MemoryBufferRef> BuffOrErr = getMemoryBufferRef();
 521   if (!BuffOrErr)
 522     return BuffOrErr.takeError();
 523
 524   auto BinaryOrErr = createBinary(BuffOrErr.get(), Context);
 525   if (BinaryOrErr)
 526     return std::move(*BinaryOrErr);
 527   return BinaryOrErr.takeError();
 528 }
 529
 530 Expected<std::unique_ptr<Archive>> Archive::create(MemoryBufferRef Source) {
 531   Error Err = Error::success();
 532   std::unique_ptr<Archive> Ret(new Archive(Source, Err));
 533   if (Err)
 534     return std::move(Err);
 535   return std::move(Ret);
 536 }
 537
 538 void Archive::setFirstRegular(const Child &C) {
 539   FirstRegularData = C.Data;
 540   FirstRegularStartOfFile = C.StartOfFile;
 541 }
 542
 543 Archive::Archive(MemoryBufferRef Source, Error &Err)
 544     : Binary(Binary::ID_Archive, Source) {
 545   ErrorAsOutParameter ErrAsOutParam(&Err);
 546   StringRef Buffer = Data.getBuffer();
 547   // Check for sufficient magic.
 548   if (Buffer.startswith(ThinMagic)) {
 549     IsThin = true;
 550   } else if (Buffer.startswith(Magic)) {
 551     IsThin = false;
 552   } else {
 553     Err = make_error<GenericBinaryError>("File too small to be an archive",
 554                                          object_error::invalid_file_type);
 555     return;
 556   }
 557
 558   // Make sure Format is initialized before any call to
 559   // ArchiveMemberHeader::getName() is made.  This could be a valid empty
 560   // archive which is the same in all formats.  So claiming it to be gnu to is
 561   // fine if not totally correct before we look for a string table or table of
 562   // contents.
 563   Format = K_GNU;
 564
 565   // Get the special members.
 566   child_iterator I = child_begin(Err, false);
 567   if (Err)
 568     return;
 569   child_iterator E = child_end();
 570
 571   // See if this is a valid empty archive and if so return.
 572   if (I == E) {
 573     Err = Error::success();
 574     return;
 575   }
 576   const Child *C = &*I;
 577
 578   auto Increment = [&]() {
 579     ++I;
 580     if (Err)
 581       return true;
 582     C = &*I;
 583     return false;
 584   };
 585
 586   Expected<StringRef> NameOrErr = C->getRawName();
 587   if (!NameOrErr) {
 588     Err = NameOrErr.takeError();
 589     return;
 590   }
 591   StringRef Name = NameOrErr.get();
 592
 593   // Below is the pattern that is used to figure out the archive format
 594   // GNU archive format
 595   //  First member : / (may exist, if it exists, points to the symbol table )
 596   //  Second member : // (may exist, if it exists, points to the string table)
 597   //  Note : The string table is used if the filename exceeds 15 characters
 598   // BSD archive format
 599   //  First member : __.SYMDEF or "__.SYMDEF SORTED" (the symbol table)
 600   //  There is no string table, if the filename exceeds 15 characters or has a
 601   //  embedded space, the filename has #1/<size>, The size represents the size
 602   //  of the filename that needs to be read after the archive header
 603   // COFF archive format
 604   //  First member : /
 605   //  Second member : / (provides a directory of symbols)
 606   //  Third member : // (may exist, if it exists, contains the string table)
 607   //  Note: Microsoft PE/COFF Spec 8.3 says that the third member is present
 608   //  even if the string table is empty. However, lib.exe does not in fact
 609   //  seem to create the third member if there's no member whose filename
 610   //  exceeds 15 characters. So the third member is optional.
 611
 612   if (Name == "__.SYMDEF" || Name == "__.SYMDEF_64") {
 613     if (Name == "__.SYMDEF")
 614       Format = K_BSD;
 615     else // Name == "__.SYMDEF_64"
 616       Format = K_DARWIN64;
 617     // We know that the symbol table is not an external file, but we still must
 618     // check any Expected<> return value.
 619     Expected<StringRef> BufOrErr = C->getBuffer();
 620     if (!BufOrErr) {
 621       Err = BufOrErr.takeError();
 622       return;
 623     }
 624     SymbolTable = BufOrErr.get();
 625     if (Increment())
 626       return;
 627     setFirstRegular(*C);
 628
 629     Err = Error::success();
 630     return;
 631   }
 632
 633   if (Name.startswith("#1/")) {
 634     Format = K_BSD;
 635     // We know this is BSD, so getName will work since there is no string table.
 636     Expected<StringRef> NameOrErr = C->getName();
 637     if (!NameOrErr) {
 638       Err = NameOrErr.takeError();
 639       return;
 640     }
 641     Name = NameOrErr.get();
 642     if (Name == "__.SYMDEF SORTED" || Name == "__.SYMDEF") {
 643       // We know that the symbol table is not an external file, but we still
 644       // must check any Expected<> return value.
 645       Expected<StringRef> BufOrErr = C->getBuffer();
 646       if (!BufOrErr) {
 647         Err = BufOrErr.takeError();
 648         return;
 649       }
 650       SymbolTable = BufOrErr.get();
 651       if (Increment())
 652         return;
 653     }
 654     else if (Name == "__.SYMDEF_64 SORTED" || Name == "__.SYMDEF_64") {
 655       Format = K_DARWIN64;
 656       // We know that the symbol table is not an external file, but we still
 657       // must check any Expected<> return value.
 658       Expected<StringRef> BufOrErr = C->getBuffer();
 659       if (!BufOrErr) {
 660         Err = BufOrErr.takeError();
 661         return;
 662       }
 663       SymbolTable = BufOrErr.get();
 664       if (Increment())
 665         return;
 666     }
 667     setFirstRegular(*C);
 668     return;
 669   }
 670
 671   // MIPS 64-bit ELF archives use a special format of a symbol table.
 672   // This format is marked by `ar_name` field equals to "/SYM64/".
 673   // For detailed description see page 96 in the following document:
 674   // http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
 675
 676   bool has64SymTable = false;
 677   if (Name == "/" || Name == "/SYM64/") {
 678     // We know that the symbol table is not an external file, but we still
 679     // must check any Expected<> return value.
 680     Expected<StringRef> BufOrErr = C->getBuffer();
 681     if (!BufOrErr) {
 682       Err = BufOrErr.takeError();
 683       return;
 684     }
 685     SymbolTable = BufOrErr.get();
 686     if (Name == "/SYM64/")
 687       has64SymTable = true;
 688
 689     if (Increment())
 690       return;
 691     if (I == E) {
 692       Err = Error::success();
 693       return;
 694     }
 695     Expected<StringRef> NameOrErr = C->getRawName();
 696     if (!NameOrErr) {
 697       Err = NameOrErr.takeError();
 698       return;
 699     }
 700     Name = NameOrErr.get();
 701   }
 702
 703   if (Name == "//") {
 704     Format = has64SymTable ? K_GNU64 : K_GNU;
 705     // The string table is never an external member, but we still
 706     // must check any Expected<> return value.
 707     Expected<StringRef> BufOrErr = C->getBuffer();
 708     if (!BufOrErr) {
 709       Err = BufOrErr.takeError();
 710       return;
 711     }
 712     StringTable = BufOrErr.get();
 713     if (Increment())
 714       return;
 715     setFirstRegular(*C);
 716     Err = Error::success();
 717     return;
 718   }
 719
 720   if (Name[0] != '/') {
 721     Format = has64SymTable ? K_GNU64 : K_GNU;
 722     setFirstRegular(*C);
 723     Err = Error::success();
 724     return;
 725   }
 726
 727   if (Name != "/") {
 728     Err = errorCodeToError(object_error::parse_failed);
 729     return;
 730   }
 731
 732   Format = K_COFF;
 733   // We know that the symbol table is not an external file, but we still
 734   // must check any Expected<> return value.
 735   Expected<StringRef> BufOrErr = C->getBuffer();
 736   if (!BufOrErr) {
 737     Err = BufOrErr.takeError();
 738     return;
 739   }
 740   SymbolTable = BufOrErr.get();
 741
 742   if (Increment())
 743     return;
 744
 745   if (I == E) {
 746     setFirstRegular(*C);
 747     Err = Error::success();
 748     return;
 749   }
 750
 751   NameOrErr = C->getRawName();
 752   if (!NameOrErr) {
 753     Err = NameOrErr.takeError();
 754     return;
 755   }
 756   Name = NameOrErr.get();
 757
 758   if (Name == "//") {
 759     // The string table is never an external member, but we still
 760     // must check any Expected<> return value.
 761     Expected<StringRef> BufOrErr = C->getBuffer();
 762     if (!BufOrErr) {
 763       Err = BufOrErr.takeError();
 764       return;
 765     }
 766     StringTable = BufOrErr.get();
 767     if (Increment())
 768       return;
 769   }
 770
 771   setFirstRegular(*C);
 772   Err = Error::success();
 773 }
 774
 775 Archive::child_iterator Archive::child_begin(Error &Err,
 776                                              bool SkipInternal) const {
 777   if (isEmpty())
 778     return child_end();
 779
 780   if (SkipInternal)
 781     return child_iterator::itr(
 782         Child(this, FirstRegularData, FirstRegularStartOfFile), Err);
 783
 784   const char *Loc = Data.getBufferStart() + strlen(Magic);
 785   Child C(this, Loc, &Err);
 786   if (Err)
 787     return child_end();
 788   return child_iterator::itr(C, Err);
 789 }
 790
 791 Archive::child_iterator Archive::child_end() const {
 792   return child_iterator::end(Child(nullptr, nullptr, nullptr));
 793 }
 794
 795 StringRef Archive::Symbol::getName() const {
 796   return Parent->getSymbolTable().begin() + StringIndex;
 797 }
 798
 799 Expected<Archive::Child> Archive::Symbol::getMember() const {
 800   const char *Buf = Parent->getSymbolTable().begin();
 801   const char *Offsets = Buf;
 802   if (Parent->kind() == K_GNU64 || Parent->kind() == K_DARWIN64)
 803     Offsets += sizeof(uint64_t);
 804   else
 805     Offsets += sizeof(uint32_t);
 806   uint64_t Offset = 0;
 807   if (Parent->kind() == K_GNU) {
 808     Offset = read32be(Offsets + SymbolIndex * 4);
 809   } else if (Parent->kind() == K_GNU64) {
 810     Offset = read64be(Offsets + SymbolIndex * 8);
 811   } else if (Parent->kind() == K_BSD) {
 812     // The SymbolIndex is an index into the ranlib structs that start at
 813     // Offsets (the first uint32_t is the number of bytes of the ranlib
 814     // structs).  The ranlib structs are a pair of uint32_t's the first
 815     // being a string table offset and the second being the offset into
 816     // the archive of the member that defines the symbol.  Which is what
 817     // is needed here.
 818     Offset = read32le(Offsets + SymbolIndex * 8 + 4);
 819   } else if (Parent->kind() == K_DARWIN64) {
 820     // The SymbolIndex is an index into the ranlib_64 structs that start at
 821     // Offsets (the first uint64_t is the number of bytes of the ranlib_64
 822     // structs).  The ranlib_64 structs are a pair of uint64_t's the first
 823     // being a string table offset and the second being the offset into
 824     // the archive of the member that defines the symbol.  Which is what
 825     // is needed here.
 826     Offset = read64le(Offsets + SymbolIndex * 16 + 8);
 827   } else {
 828     // Skip offsets.
 829     uint32_t MemberCount = read32le(Buf);
 830     Buf += MemberCount * 4 + 4;
 831
 832     uint32_t SymbolCount = read32le(Buf);
 833     if (SymbolIndex >= SymbolCount)
 834       return errorCodeToError(object_error::parse_failed);
 835
 836     // Skip SymbolCount to get to the indices table.
 837     const char *Indices = Buf + 4;
 838
 839     // Get the index of the offset in the file member offset table for this
 840     // symbol.
 841     uint16_t OffsetIndex = read16le(Indices + SymbolIndex * 2);
 842     // Subtract 1 since OffsetIndex is 1 based.
 843     --OffsetIndex;
 844
 845     if (OffsetIndex >= MemberCount)
 846       return errorCodeToError(object_error::parse_failed);
 847
 848     Offset = read32le(Offsets + OffsetIndex * 4);
 849   }
 850
 851   const char *Loc = Parent->getData().begin() + Offset;
 852   Error Err = Error::success();
 853   Child C(Parent, Loc, &Err);
 854   if (Err)
 855     return std::move(Err);
 856   return C;
 857 }
 858
 859 Archive::Symbol Archive::Symbol::getNext() const {
 860   Symbol t(*this);
 861   if (Parent->kind() == K_BSD) {
 862     // t.StringIndex is an offset from the start of the __.SYMDEF or
 863     // "__.SYMDEF SORTED" member into the string table for the ranlib
 864     // struct indexed by t.SymbolIndex .  To change t.StringIndex to the
 865     // offset in the string table for t.SymbolIndex+1 we subtract the
 866     // its offset from the start of the string table for t.SymbolIndex
 867     // and add the offset of the string table for t.SymbolIndex+1.
 868
 869     // The __.SYMDEF or "__.SYMDEF SORTED" member starts with a uint32_t
 870     // which is the number of bytes of ranlib structs that follow.  The ranlib
 871     // structs are a pair of uint32_t's the first being a string table offset
 872     // and the second being the offset into the archive of the member that
 873     // define the symbol. After that the next uint32_t is the byte count of
 874     // the string table followed by the string table.
 875     const char *Buf = Parent->getSymbolTable().begin();
 876     uint32_t RanlibCount = 0;
 877     RanlibCount = read32le(Buf) / 8;
 878     // If t.SymbolIndex + 1 will be past the count of symbols (the RanlibCount)
 879     // don't change the t.StringIndex as we don't want to reference a ranlib
 880     // past RanlibCount.
 881     if (t.SymbolIndex + 1 < RanlibCount) {
 882       const char *Ranlibs = Buf + 4;
 883       uint32_t CurRanStrx = 0;
 884       uint32_t NextRanStrx = 0;
 885       CurRanStrx = read32le(Ranlibs + t.SymbolIndex * 8);
 886       NextRanStrx = read32le(Ranlibs + (t.SymbolIndex + 1) * 8);
 887       t.StringIndex -= CurRanStrx;
 888       t.StringIndex += NextRanStrx;
 889     }
 890   } else {
 891     // Go to one past next null.
 892     t.StringIndex = Parent->getSymbolTable().find('\0', t.StringIndex) + 1;
 893   }
 894   ++t.SymbolIndex;
 895   return t;
 896 }
 897
 898 Archive::symbol_iterator Archive::symbol_begin() const {
 899   if (!hasSymbolTable())
 900     return symbol_iterator(Symbol(this, 0, 0));
 901
 902   const char *buf = getSymbolTable().begin();
 903   if (kind() == K_GNU) {
 904     uint32_t symbol_count = 0;
 905     symbol_count = read32be(buf);
 906     buf += sizeof(uint32_t) + (symbol_count * (sizeof(uint32_t)));
 907   } else if (kind() == K_GNU64) {
 908     uint64_t symbol_count = read64be(buf);
 909     buf += sizeof(uint64_t) + (symbol_count * (sizeof(uint64_t)));
 910   } else if (kind() == K_BSD) {
 911     // The __.SYMDEF or "__.SYMDEF SORTED" member starts with a uint32_t
 912     // which is the number of bytes of ranlib structs that follow.  The ranlib
 913     // structs are a pair of uint32_t's the first being a string table offset
 914     // and the second being the offset into the archive of the member that
 915     // define the symbol. After that the next uint32_t is the byte count of
 916     // the string table followed by the string table.
 917     uint32_t ranlib_count = 0;
 918     ranlib_count = read32le(buf) / 8;
 919     const char *ranlibs = buf + 4;
 920     uint32_t ran_strx = 0;
 921     ran_strx = read32le(ranlibs);
 922     buf += sizeof(uint32_t) + (ranlib_count * (2 * (sizeof(uint32_t))));
 923     // Skip the byte count of the string table.
 924     buf += sizeof(uint32_t);
 925     buf += ran_strx;
 926   } else if (kind() == K_DARWIN64) {
 927     // The __.SYMDEF_64 or "__.SYMDEF_64 SORTED" member starts with a uint64_t
 928     // which is the number of bytes of ranlib_64 structs that follow.  The
 929     // ranlib_64 structs are a pair of uint64_t's the first being a string
 930     // table offset and the second being the offset into the archive of the
 931     // member that define the symbol. After that the next uint64_t is the byte
 932     // count of the string table followed by the string table.
 933     uint64_t ranlib_count = 0;
 934     ranlib_count = read64le(buf) / 16;
 935     const char *ranlibs = buf + 8;
 936     uint64_t ran_strx = 0;
 937     ran_strx = read64le(ranlibs);
 938     buf += sizeof(uint64_t) + (ranlib_count * (2 * (sizeof(uint64_t))));
 939     // Skip the byte count of the string table.
 940     buf += sizeof(uint64_t);
 941     buf += ran_strx;
 942   } else {
 943     uint32_t member_count = 0;
 944     uint32_t symbol_count = 0;
 945     member_count = read32le(buf);
 946     buf += 4 + (member_count * 4); // Skip offsets.
 947     symbol_count = read32le(buf);
 948     buf += 4 + (symbol_count * 2); // Skip indices.
 949   }
 950   uint32_t string_start_offset = buf - getSymbolTable().begin();
 951   return symbol_iterator(Symbol(this, 0, string_start_offset));
 952 }
 953
 954 Archive::symbol_iterator Archive::symbol_end() const {
 955   return symbol_iterator(Symbol(this, getNumberOfSymbols(), 0));
 956 }
 957
 958 uint32_t Archive::getNumberOfSymbols() const {
 959   if (!hasSymbolTable())
 960     return 0;
 961   const char *buf = getSymbolTable().begin();
 962   if (kind() == K_GNU)
 963     return read32be(buf);
 964   if (kind() == K_GNU64)
 965     return read64be(buf);
 966   if (kind() == K_BSD)
 967     return read32le(buf) / 8;
 968   if (kind() == K_DARWIN64)
 969     return read64le(buf) / 16;
 970   uint32_t member_count = 0;
 971   member_count = read32le(buf);
 972   buf += 4 + (member_count * 4); // Skip offsets.
 973   return read32le(buf);
 974 }
 975
 976 Expected<Optional<Archive::Child>> Archive::findSym(StringRef name) const {
 977   Archive::symbol_iterator bs = symbol_begin();
 978   Archive::symbol_iterator es = symbol_end();
 979
 980   for (; bs != es; ++bs) {
 981     StringRef SymName = bs->getName();
 982     if (SymName == name) {
 983       if (auto MemberOrErr = bs->getMember())
 984         return Child(*MemberOrErr);
 985       else
 986         return MemberOrErr.takeError();
 987     }
 988   }
 989   return Optional<Child>();
 990 }
 991
 992 // Returns true if archive file contains no member file.
 993 bool Archive::isEmpty() const { return Data.getBufferSize() == 8; }
 994
 995 bool Archive::hasSymbolTable() const { return !SymbolTable.empty(); }