C++ MemoryBufferRef::getBuffer方法代码示例

template <class ELFT> static ELFFile<ELFT> createELFObj(MemoryBufferRef MB) {
  std::error_code EC;
  ELFFile<ELFT> F(MB.getBuffer(), EC);
  if (EC)
    fatal(EC, "failed to read " + MB.getBufferIdentifier());
  return F;
}

bool llvm::parseAssemblyInto(MemoryBufferRef F, Module &M, SMDiagnostic &Err) {
  SourceMgr SM;
  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(F, false);
  SM.AddNewSourceBuffer(std::move(Buf), SMLoc());

  return LLParser(F.getBuffer(), SM, Err, &M).Run();
}

ErrorOr<std::unique_ptr<ObjectFile>>
ObjectFile::createELFObjectFile(MemoryBufferRef Obj) {
  std::pair<unsigned char, unsigned char> Ident =
      getElfArchType(Obj.getBuffer());
  std::size_t MaxAlignment =
      1ULL << countTrailingZeros(uintptr_t(Obj.getBufferStart()));

  if (MaxAlignment < 2)
    return object_error::parse_failed;

  std::error_code EC;
  std::unique_ptr<ObjectFile> R;
  if (Ident.first == ELF::ELFCLASS32) {
    if (Ident.second == ELF::ELFDATA2LSB)
      R.reset(new ELFObjectFile<ELFType<support::little, false>>(Obj, EC));
    else if (Ident.second == ELF::ELFDATA2MSB)
      R.reset(new ELFObjectFile<ELFType<support::big, false>>(Obj, EC));
    else
      return object_error::parse_failed;
  } else if (Ident.first == ELF::ELFCLASS64) {
    if (Ident.second == ELF::ELFDATA2LSB)
      R.reset(new ELFObjectFile<ELFType<support::little, true>>(Obj, EC));
    else if (Ident.second == ELF::ELFDATA2MSB)
      R.reset(new ELFObjectFile<ELFType<support::big, true>>(Obj, EC));
    else
      return object_error::parse_failed;
  } else {
    return object_error::parse_failed;
  }

  if (EC)
    return EC;
  return std::move(R);
}

void SymbolTable<ELFT>::addLazyArchive(ArchiveFile *F,
                                       const object::Archive::Symbol Sym) {
  Symbol *S;
  bool WasInserted;
  std::tie(S, WasInserted) = insert(Sym.getName());
  if (WasInserted) {
    replaceBody<LazyArchive>(S, *F, Sym, SymbolBody::UnknownType);
    return;
  }
  if (!S->body()->isUndefined())
    return;

  // Weak undefined symbols should not fetch members from archives. If we were
  // to keep old symbol we would not know that an archive member was available
  // if a strong undefined symbol shows up afterwards in the link. If a strong
  // undefined symbol never shows up, this lazy symbol will get to the end of
  // the link and must be treated as the weak undefined one. We already marked
  // this symbol as used when we added it to the symbol table, but we also need
  // to preserve its type. FIXME: Move the Type field to Symbol.
  if (S->isWeak()) {
    replaceBody<LazyArchive>(S, *F, Sym, S->body()->Type);
    return;
  }
  MemoryBufferRef MBRef = F->getMember(&Sym);
  if (!MBRef.getBuffer().empty())
    addFile(createObjectFile(MBRef, F->getName()));
}

bool llvm::parseAssemblyInto(MemoryBufferRef F, Module &M, SMDiagnostic &Err,
                             SlotMapping *Slots, bool UpgradeDebugInfo) {
  SourceMgr SM;
  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(F);
  SM.AddNewSourceBuffer(std::move(Buf), SMLoc());

  return LLParser(F.getBuffer(), SM, Err, &M, Slots, UpgradeDebugInfo).Run();
}

std::unique_ptr<InputFile> LazyArchive::getFile() {
  MemoryBufferRef MBRef = File->getMember(&Sym);

  // getMember returns an empty buffer if the member was already
  // read from the library.
  if (MBRef.getBuffer().empty())
    return std::unique_ptr<InputFile>(nullptr);
  return createObjectFile(MBRef, File->getName());
}

static ELFKind getELFKind(MemoryBufferRef MB) {
  unsigned char Size;
  unsigned char Endian;
  std::tie(Size, Endian) = getElfArchType(MB.getBuffer());

  if (Endian != ELFDATA2LSB && Endian != ELFDATA2MSB)
    fatal(MB.getBufferIdentifier() + ": invalid data encoding");
  if (Size != ELFCLASS32 && Size != ELFCLASS64)
    fatal(MB.getBufferIdentifier() + ": invalid file class");

  size_t BufSize = MB.getBuffer().size();
  if ((Size == ELFCLASS32 && BufSize < sizeof(Elf32_Ehdr)) ||
      (Size == ELFCLASS64 && BufSize < sizeof(Elf64_Ehdr)))
    fatal(MB.getBufferIdentifier() + ": file is too short");

  if (Size == ELFCLASS32)
    return (Endian == ELFDATA2LSB) ? ELF32LEKind : ELF32BEKind;
  return (Endian == ELFDATA2LSB) ? ELF64LEKind : ELF64BEKind;
}

static std::unique_ptr<InputFile> createFile(MemoryBufferRef MB) {
  // File type is detected by contents, not by file extension.
  file_magic Magic = identify_magic(MB.getBuffer());
  if (Magic == file_magic::archive)
    return std::unique_ptr<InputFile>(new ArchiveFile(MB));
  if (Magic == file_magic::bitcode)
    return std::unique_ptr<InputFile>(new BitcodeFile(MB));
  if (Config->OutputFile == "")
    Config->OutputFile = getOutputPath(MB.getBufferIdentifier());
  return std::unique_ptr<InputFile>(new ObjectFile<llvm::object::ELF64LE>(MB));
}

ErrorOr<std::unique_ptr<SymbolicFile>> SymbolicFile::createSymbolicFile(
    MemoryBufferRef Object, sys::fs::file_magic Type, LLVMContext *Context) {
  StringRef Data = Object.getBuffer();
  if (Type == sys::fs::file_magic::unknown)
    Type = sys::fs::identify_magic(Data);

  switch (Type) {
  case sys::fs::file_magic::bitcode:
    if (Context)
      return IRObjectFile::create(Object, *Context);
  // Fallthrough
  case sys::fs::file_magic::unknown:
  case sys::fs::file_magic::archive:
  case sys::fs::file_magic::macho_universal_binary:
  case sys::fs::file_magic::windows_resource:
    return object_error::invalid_file_type;
  case sys::fs::file_magic::elf:
  case sys::fs::file_magic::elf_executable:
  case sys::fs::file_magic::elf_shared_object:
  case sys::fs::file_magic::elf_core:
  case sys::fs::file_magic::macho_executable:
  case sys::fs::file_magic::macho_fixed_virtual_memory_shared_lib:
  case sys::fs::file_magic::macho_core:
  case sys::fs::file_magic::macho_preload_executable:
  case sys::fs::file_magic::macho_dynamically_linked_shared_lib:
  case sys::fs::file_magic::macho_dynamic_linker:
  case sys::fs::file_magic::macho_bundle:
  case sys::fs::file_magic::macho_dynamically_linked_shared_lib_stub:
  case sys::fs::file_magic::macho_dsym_companion:
  case sys::fs::file_magic::macho_kext_bundle:
  case sys::fs::file_magic::pecoff_executable:
    return ObjectFile::createObjectFile(Object, Type);
  case sys::fs::file_magic::coff_import_library:
    return std::unique_ptr<SymbolicFile>(new COFFImportFile(Object));
  case sys::fs::file_magic::elf_relocatable:
  case sys::fs::file_magic::macho_object:
  case sys::fs::file_magic::coff_object: {
    ErrorOr<std::unique_ptr<ObjectFile>> Obj =
        ObjectFile::createObjectFile(Object, Type);
    if (!Obj || !Context)
      return std::move(Obj);

    ErrorOr<MemoryBufferRef> BCData =
        IRObjectFile::findBitcodeInObject(*Obj->get());
    if (!BCData)
      return std::move(Obj);

    return IRObjectFile::create(
        MemoryBufferRef(BCData->getBuffer(), Object.getBufferIdentifier()),
        *Context);
  }
  }
  llvm_unreachable("Unexpected Binary File Type");
}

std::vector<StringRef> lld::args::getLines(MemoryBufferRef MB) {
  SmallVector<StringRef, 0> Arr;
  MB.getBuffer().split(Arr, '\n');

  std::vector<StringRef> Ret;
  for (StringRef S : Arr) {
    S = S.trim();
    if (!S.empty() && S[0] != '#')
      Ret.push_back(S);
  }
  return Ret;
}

std::unique_ptr<InputFile> Lazy::getMember() {
  MemoryBufferRef MBRef = File->getMember(&Sym);

  // getMember returns an empty buffer if the member was already
  // read from the library.
  if (MBRef.getBuffer().empty())
    return std::unique_ptr<InputFile>(nullptr);

  file_magic Magic = identify_magic(MBRef.getBuffer());
  if (Magic == file_magic::coff_import_library)
    return std::unique_ptr<InputFile>(new ImportFile(MBRef));

  std::unique_ptr<InputFile> Obj;
  if (Magic == file_magic::coff_object)
    Obj.reset(new ObjectFile(MBRef));
  else if (Magic == file_magic::bitcode)
    Obj.reset(new BitcodeFile(MBRef));
  else
    error(Twine(File->getName()) + ": unknown file type");

  Obj->setParentName(File->getName());
  return Obj;
}

Optional<MemoryBufferRef> elf::readFile(StringRef Path) {
  log(Path);
  auto MBOrErr = MemoryBuffer::getFile(Path);
  if (auto EC = MBOrErr.getError()) {
    error("cannot open " + Path + ": " + EC.message());
    return None;
  }

  std::unique_ptr<MemoryBuffer> &MB = *MBOrErr;
  MemoryBufferRef MBRef = MB->getMemBufferRef();
  make<std::unique_ptr<MemoryBuffer>>(std::move(MB)); // take MB ownership

  if (Tar)
    Tar->append(relativeToRoot(Path), MBRef.getBuffer());
  return MBRef;
}

// Split S into linker script tokens.
void ScriptParserBase::tokenize(MemoryBufferRef MB) {
  std::vector<StringRef> Vec;
  MBs.push_back(MB);
  StringRef S = MB.getBuffer();
  StringRef Begin = S;

  for (;;) {
    S = skipSpace(S);
    if (S.empty())
      break;

    // Quoted token. Note that double-quote characters are parts of a token
    // because, in a glob match context, only unquoted tokens are interpreted
    // as glob patterns. Double-quoted tokens are literal patterns in that
    // context.
    if (S.startswith("\"")) {
      size_t E = S.find("\"", 1);
      if (E == StringRef::npos) {
        StringRef Filename = MB.getBufferIdentifier();
        size_t Lineno = Begin.substr(0, S.data() - Begin.data()).count('\n');
        error(Filename + ":" + Twine(Lineno + 1) + ": unclosed quote");
        return;
      }

      Vec.push_back(S.take_front(E + 1));
      S = S.substr(E + 1);
      continue;
    }

    // Unquoted token. This is more relaxed than tokens in C-like language,
    // so that you can write "file-name.cpp" as one bare token, for example.
    size_t Pos = S.find_first_not_of(
        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
        "0123456789_.$/\\~=+[]*?-:!<>^");

    // A character that cannot start a word (which is usually a
    // punctuation) forms a single character token.
    if (Pos == 0)
      Pos = 1;
    Vec.push_back(S.substr(0, Pos));
    S = S.substr(Pos);
  }

  Tokens.insert(Tokens.begin() + Pos, Vec.begin(), Vec.end());
}

ErrorOr<MemoryBufferRef> IRObjectFile::findBitcodeInMemBuffer(MemoryBufferRef Object) {
  sys::fs::file_magic Type = sys::fs::identify_magic(Object.getBuffer());
  switch (Type) {
  case sys::fs::file_magic::bitcode:
    return Object;
  case sys::fs::file_magic::elf_relocatable:
  case sys::fs::file_magic::macho_object:
  case sys::fs::file_magic::coff_object: {
    ErrorOr<std::unique_ptr<ObjectFile>> ObjFile =
        ObjectFile::createObjectFile(Object, Type);
    if (!ObjFile)
      return ObjFile.getError();
    return findBitcodeInObject(*ObjFile->get());
  }
  default:
    return object_error::invalid_file_type;
  }
}

static std::unique_ptr<InputFile> createFile(MemoryBufferRef MB) {
  std::pair<unsigned char, unsigned char> Type =
      object::getElfArchType(MB.getBuffer());
  if (Type.second != ELF::ELFDATA2LSB && Type.second != ELF::ELFDATA2MSB)
    error("Invalid data encoding");

  if (Type.first == ELF::ELFCLASS32) {
    if (Type.second == ELF::ELFDATA2LSB)
      return make_unique<ObjectFile<object::ELF32LE>>(MB);
    return make_unique<ObjectFile<object::ELF32BE>>(MB);
  }
  if (Type.first == ELF::ELFCLASS64) {
    if (Type.second == ELF::ELFDATA2LSB)
      return make_unique<ObjectFile<object::ELF64LE>>(MB);
    return make_unique<ObjectFile<object::ELF64BE>>(MB);
  }
  error("Invalid file class");
}