C++ raw_fd_ostream::seek方法代码示例

static void writeStringTable(raw_fd_ostream &Out,
                             ArrayRef<NewArchiveIterator> Members,
                             std::vector<unsigned> &StringMapIndexes) {
  unsigned StartOffset = 0;
  for (ArrayRef<NewArchiveIterator>::iterator I = Members.begin(),
                                              E = Members.end();
       I != E; ++I) {
    StringRef Name = I->getName();
    if (Name.size() < 16)
      continue;
    if (StartOffset == 0) {
      printWithSpacePadding(Out, "//", 58);
      Out << "`\n";
      StartOffset = Out.tell();
    }
    StringMapIndexes.push_back(Out.tell() - StartOffset);
    Out << Name << "/\n";
  }
  if (StartOffset == 0)
    return;
  if (Out.tell() % 2)
    Out << '\n';
  int Pos = Out.tell();
  Out.seek(StartOffset - 12);
  printWithSpacePadding(Out, Pos - StartOffset, 10);
  Out.seek(Pos);
}

static void writeStringTable(raw_fd_ostream &Out, StringRef ArcName,
                             ArrayRef<NewArchiveMember> Members,
                             std::vector<unsigned> &StringMapIndexes,
                             bool Thin) {
  unsigned StartOffset = 0;
  for (const NewArchiveMember &M : Members) {
    StringRef Path = M.Buf->getBufferIdentifier();
    StringRef Name = sys::path::filename(Path);
    if (!useStringTable(Thin, Name))
      continue;
    if (StartOffset == 0) {
      printWithSpacePadding(Out, "//", 58);
      Out << "`\n";
      StartOffset = Out.tell();
    }
    StringMapIndexes.push_back(Out.tell() - StartOffset);

    if (Thin)
      Out << computeRelativePath(ArcName, Path);
    else
      Out << Name;

    Out << "/\n";
  }
  if (StartOffset == 0)
    return;
  if (Out.tell() % 2)
    Out << '\n';
  int Pos = Out.tell();
  Out.seek(StartOffset - 12);
  printWithSpacePadding(Out, Pos - StartOffset, 10);
  Out.seek(Pos);
}

static void
writeSymbolTable(raw_fd_ostream &Out, ArrayRef<NewArchiveIterator> Members,
                 MutableArrayRef<std::unique_ptr<MemoryBuffer>> Buffers,
                 std::vector<std::pair<unsigned, unsigned>> &MemberOffsetRefs) {
  unsigned StartOffset = 0;
  unsigned MemberNum = 0;
  std::string NameBuf;
  raw_string_ostream NameOS(NameBuf);
  unsigned NumSyms = 0;
  LLVMContext &Context = getGlobalContext();
  for (ArrayRef<NewArchiveIterator>::iterator I = Members.begin(),
                                              E = Members.end();
       I != E; ++I, ++MemberNum) {
    std::unique_ptr<MemoryBuffer> &MemberBuffer = Buffers[MemberNum];
    ErrorOr<std::unique_ptr<object::SymbolicFile>> ObjOrErr =
        object::SymbolicFile::createSymbolicFile(
            MemberBuffer, sys::fs::file_magic::unknown, &Context);
    if (!ObjOrErr)
      continue;  // FIXME: check only for "not an object file" errors.
    object::SymbolicFile &Obj = *ObjOrErr.get();

    if (!StartOffset) {
      printMemberHeader(Out, "", sys::TimeValue::now(), 0, 0, 0, 0);
      StartOffset = Out.tell();
      print32BE(Out, 0);
    }

    for (const object::BasicSymbolRef &S : Obj.symbols()) {
      uint32_t Symflags = S.getFlags();
      if (Symflags & object::SymbolRef::SF_FormatSpecific)
        continue;
      if (!(Symflags & object::SymbolRef::SF_Global))
        continue;
      if (Symflags & object::SymbolRef::SF_Undefined)
        continue;
      failIfError(S.printName(NameOS));
      NameOS << '\0';
      ++NumSyms;
      MemberOffsetRefs.push_back(std::make_pair(Out.tell(), MemberNum));
      print32BE(Out, 0);
    }
    MemberBuffer.reset(Obj.releaseBuffer());
  }
  Out << NameOS.str();

  if (StartOffset == 0)
    return;

  if (Out.tell() % 2)
    Out << '\0';

  unsigned Pos = Out.tell();
  Out.seek(StartOffset - 12);
  printWithSpacePadding(Out, Pos - StartOffset, 10);
  Out.seek(StartOffset);
  print32BE(Out, NumSyms);
  Out.seek(Pos);
}

void InstrProfWriter::write(raw_fd_ostream &OS) {
  // Write the hash table.
  auto TableStart = writeImpl(OS);

  // Go back and fill in the hash table start.
  using namespace support;
  OS.seek(TableStart.first);
  endian::Writer<little>(OS).write<uint64_t>(TableStart.second);
}

static void printWithSpacePadding(raw_fd_ostream &OS, T Data, unsigned Size,
                                  bool MayTruncate = false) {
  uint64_t OldPos = OS.tell();
  OS << Data;
  unsigned SizeSoFar = OS.tell() - OldPos;
  if (Size > SizeSoFar) {
    OS.indent(Size - SizeSoFar);
  } else if (Size < SizeSoFar) {
    assert(MayTruncate && "Data doesn't fit in Size");
    // Some of the data this is used for (like UID) can be larger than the
    // space available in the archive format. Truncate in that case.
    OS.seek(OldPos + Size);
  }
}

// Returns the offset of the first reference to a member offset.
static ErrorOr<unsigned>
writeSymbolTable(raw_fd_ostream &Out, object::Archive::Kind Kind,
                 ArrayRef<NewArchiveMember> Members,
                 std::vector<unsigned> &MemberOffsetRefs, bool Deterministic) {
  unsigned HeaderStartOffset = 0;
  unsigned BodyStartOffset = 0;
  SmallString<128> NameBuf;
  raw_svector_ostream NameOS(NameBuf);
  LLVMContext Context;
  for (unsigned MemberNum = 0, N = Members.size(); MemberNum < N; ++MemberNum) {
    MemoryBufferRef MemberBuffer = Members[MemberNum].Buf->getMemBufferRef();
    Expected<std::unique_ptr<object::SymbolicFile>> ObjOrErr =
        object::SymbolicFile::createSymbolicFile(
            MemberBuffer, sys::fs::file_magic::unknown, &Context);
    if (!ObjOrErr) {
      // FIXME: check only for "not an object file" errors.
      consumeError(ObjOrErr.takeError());
      continue;
    }
    object::SymbolicFile &Obj = *ObjOrErr.get();

    if (!HeaderStartOffset) {
      HeaderStartOffset = Out.tell();
      if (Kind == object::Archive::K_GNU)
        printGNUSmallMemberHeader(Out, "", now(Deterministic), 0, 0, 0, 0);
      else
        printBSDMemberHeader(Out, "__.SYMDEF", now(Deterministic), 0, 0, 0, 0);
      BodyStartOffset = Out.tell();
      print32(Out, Kind, 0); // number of entries or bytes
    }

    for (const object::BasicSymbolRef &S : Obj.symbols()) {
      uint32_t Symflags = S.getFlags();
      if (Symflags & object::SymbolRef::SF_FormatSpecific)
        continue;
      if (!(Symflags & object::SymbolRef::SF_Global))
        continue;
      if (Symflags & object::SymbolRef::SF_Undefined)
        continue;

      unsigned NameOffset = NameOS.tell();
      if (auto EC = S.printName(NameOS))
        return EC;
      NameOS << '\0';
      MemberOffsetRefs.push_back(MemberNum);
      if (Kind == object::Archive::K_BSD)
        print32(Out, Kind, NameOffset);
      print32(Out, Kind, 0); // member offset
    }
  }

  if (HeaderStartOffset == 0)
    return 0;

  StringRef StringTable = NameOS.str();
  if (Kind == object::Archive::K_BSD)
    print32(Out, Kind, StringTable.size()); // byte count of the string table
  Out << StringTable;

  // ld64 requires the next member header to start at an offset that is
  // 4 bytes aligned.
  unsigned Pad = OffsetToAlignment(Out.tell(), 4);
  while (Pad--)
    Out.write(uint8_t(0));

  // Patch up the size of the symbol table now that we know how big it is.
  unsigned Pos = Out.tell();
  const unsigned MemberHeaderSize = 60;
  Out.seek(HeaderStartOffset + 48); // offset of the size field.
  printWithSpacePadding(Out, Pos - MemberHeaderSize - HeaderStartOffset, 10);

  // Patch up the number of symbols.
  Out.seek(BodyStartOffset);
  unsigned NumSyms = MemberOffsetRefs.size();
  if (Kind == object::Archive::K_GNU)
    print32(Out, Kind, NumSyms);
  else
    print32(Out, Kind, NumSyms * 8);

  Out.seek(Pos);
  return BodyStartOffset + 4;
}

static void writeSymbolTable(
    raw_fd_ostream &Out, ArrayRef<NewArchiveIterator> Members,
    std::vector<std::pair<unsigned, unsigned> > &MemberOffsetRefs) {
  unsigned StartOffset = 0;
  unsigned MemberNum = 0;
  std::vector<StringRef> SymNames;
  std::vector<object::ObjectFile *> DeleteIt;
  for (ArrayRef<NewArchiveIterator>::iterator I = Members.begin(),
                                              E = Members.end();
       I != E; ++I, ++MemberNum) {
    object::ObjectFile *Obj;
    if (I->isNewMember()) {
      const char *Filename = I->getNew();
      Obj = object::ObjectFile::createObjectFile(Filename);
    } else {
      object::Archive::child_iterator OldMember = I->getOld();
      OwningPtr<object::Binary> Binary;
      error_code EC = OldMember->getAsBinary(Binary);
      if (EC) { // FIXME: check only for "not an object file" errors.
        Obj = NULL;
      } else {
        Obj = dyn_cast<object::ObjectFile>(Binary.get());
        if (Obj)
          Binary.take();
      }
    }
    if (!Obj)
      continue;
    DeleteIt.push_back(Obj);
    if (!StartOffset) {
      printMemberHeader(Out, "", sys::TimeValue::now(), 0, 0, 0, 0);
      StartOffset = Out.tell();
      print32BE(Out, 0);
    }

    error_code Err;
    for (object::symbol_iterator I = Obj->begin_symbols(),
                                 E = Obj->end_symbols();
         I != E; I.increment(Err), failIfError(Err)) {
      uint32_t Symflags;
      failIfError(I->getFlags(Symflags));
      if (Symflags & object::SymbolRef::SF_FormatSpecific)
        continue;
      if (!(Symflags & object::SymbolRef::SF_Global))
        continue;
      if (Symflags & object::SymbolRef::SF_Undefined)
        continue;
      StringRef Name;
      failIfError(I->getName(Name));
      SymNames.push_back(Name);
      MemberOffsetRefs.push_back(std::make_pair(Out.tell(), MemberNum));
      print32BE(Out, 0);
    }
  }
  for (std::vector<StringRef>::iterator I = SymNames.begin(),
                                        E = SymNames.end();
       I != E; ++I) {
    Out << *I;
    Out << '\0';
  }

  for (std::vector<object::ObjectFile *>::iterator I = DeleteIt.begin(),
                                                   E = DeleteIt.end();
       I != E; ++I) {
    object::ObjectFile *O = *I;
    delete O;
  }

  if (StartOffset == 0)
    return;

  if (Out.tell() % 2)
    Out << '\0';

  unsigned Pos = Out.tell();
  Out.seek(StartOffset - 12);
  printWithSpacePadding(Out, Pos - StartOffset, 10);
  Out.seek(StartOffset);
  print32BE(Out, SymNames.size());
  Out.seek(Pos);
}

static void writeSymbolTable(
    raw_fd_ostream &Out, ArrayRef<NewArchiveIterator> Members,
    ArrayRef<MemoryBuffer *> Buffers,
    std::vector<std::pair<unsigned, unsigned> > &MemberOffsetRefs) {
  unsigned StartOffset = 0;
  unsigned MemberNum = 0;
  std::string NameBuf;
  raw_string_ostream NameOS(NameBuf);
  unsigned NumSyms = 0;
  std::vector<object::SymbolicFile *> DeleteIt;
  LLVMContext &Context = getGlobalContext();
  for (ArrayRef<NewArchiveIterator>::iterator I = Members.begin(),
                                              E = Members.end();
       I != E; ++I, ++MemberNum) {
    MemoryBuffer *MemberBuffer = Buffers[MemberNum];
    ErrorOr<object::SymbolicFile *> ObjOrErr =
        object::SymbolicFile::createSymbolicFile(
            MemberBuffer, false, sys::fs::file_magic::unknown, &Context);
    if (!ObjOrErr)
      continue;  // FIXME: check only for "not an object file" errors.
    object::SymbolicFile *Obj = ObjOrErr.get();

    DeleteIt.push_back(Obj);
    if (!StartOffset) {
      printMemberHeader(Out, "", sys::TimeValue::now(), 0, 0, 0, 0);
      StartOffset = Out.tell();
      print32BE(Out, 0);
    }

    for (object::basic_symbol_iterator I = Obj->symbol_begin(),
                                       E = Obj->symbol_end();
         I != E; ++I) {
      uint32_t Symflags = I->getFlags();
      if (Symflags & object::SymbolRef::SF_FormatSpecific)
        continue;
      if (!(Symflags & object::SymbolRef::SF_Global))
        continue;
      if (Symflags & object::SymbolRef::SF_Undefined)
        continue;
      failIfError(I->printName(NameOS));
      NameOS << '\0';
      ++NumSyms;
      MemberOffsetRefs.push_back(std::make_pair(Out.tell(), MemberNum));
      print32BE(Out, 0);
    }
  }
  Out << NameOS.str();

  for (std::vector<object::SymbolicFile *>::iterator I = DeleteIt.begin(),
                                                     E = DeleteIt.end();
       I != E; ++I) {
    object::SymbolicFile *O = *I;
    delete O;
  }

  if (StartOffset == 0)
    return;

  if (Out.tell() % 2)
    Out << '\0';

  unsigned Pos = Out.tell();
  Out.seek(StartOffset - 12);
  printWithSpacePadding(Out, Pos - StartOffset, 10);
  Out.seek(StartOffset);
  print32BE(Out, NumSyms);
  Out.seek(Pos);
}

// Headers in tar files must be aligned to 512 byte boundaries.
// This function forwards the current file position to the next boundary.
static void pad(raw_fd_ostream &OS) {
  uint64_t Pos = OS.tell();
  OS.seek(alignTo(Pos, BlockSize));
}