C++ MemoryBufferRef::getBufferStart方法代码示例

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);
}

Error PDBFile::parseFileHeaders() {
  std::error_code EC;
  MemoryBufferRef BufferRef = *Context->Buffer;

  // Make sure the file is sufficiently large to hold a super block.
  // Do this before attempting to read the super block.
  if (BufferRef.getBufferSize() < sizeof(SuperBlock))
    return make_error<RawError>(raw_error_code::corrupt_file,
                                "Does not contain superblock");

  Context->SB =
      reinterpret_cast<const SuperBlock *>(BufferRef.getBufferStart());
  const SuperBlock *SB = Context->SB;
  // Check the magic bytes.
  if (memcmp(SB->MagicBytes, Magic, sizeof(Magic)) != 0)
    return make_error<RawError>(raw_error_code::corrupt_file,
                                "MSF magic header doesn't match");

  // We don't support blocksizes which aren't a multiple of four bytes.
  if (SB->BlockSize % sizeof(support::ulittle32_t) != 0)
    return make_error<RawError>(raw_error_code::corrupt_file,
                                "Block size is not multiple of 4.");

  switch (SB->BlockSize) {
  case 512: case 1024: case 2048: case 4096:
    break;
  default:
    // An invalid block size suggests a corrupt PDB file.
    return make_error<RawError>(raw_error_code::corrupt_file,
                                "Unsupported block size.");
  }

  if (BufferRef.getBufferSize() % SB->BlockSize != 0)
    return make_error<RawError>(raw_error_code::corrupt_file,
                                "File size is not a multiple of block size");

  // We don't support directories whose sizes aren't a multiple of four bytes.
  if (SB->NumDirectoryBytes % sizeof(support::ulittle32_t) != 0)
    return make_error<RawError>(raw_error_code::corrupt_file,
                                "Directory size is not multiple of 4.");

  // The number of blocks which comprise the directory is a simple function of
  // the number of bytes it contains.
  uint64_t NumDirectoryBlocks = getNumDirectoryBlocks();

  // The block map, as we understand it, is a block which consists of a list of
  // block numbers.
  // It is unclear what would happen if the number of blocks couldn't fit on a
  // single block.
  if (NumDirectoryBlocks > SB->BlockSize / sizeof(support::ulittle32_t))
    return make_error<RawError>(raw_error_code::corrupt_file,
                                "Too many directory blocks.");

  // Make sure the directory block array fits within the file.
  if (auto EC = checkOffset(BufferRef, getDirectoryBlockArray()))
    return EC;

  return Error::success();
}

static std::error_code checkOffset(MemoryBufferRef M, uintptr_t Addr,
                                   const uint64_t Size) {
  if (Addr + Size < Addr || Addr + Size < Size ||
      Addr + Size > uintptr_t(M.getBufferEnd()) ||
      Addr < uintptr_t(M.getBufferStart())) {
    return object_error::unexpected_eof;
  }
  return std::error_code();
}

static std::error_code checkOffset(MemoryBufferRef M, uintptr_t Addr,
                                   const uint64_t Size) {
  if (Addr + Size < Addr || Addr + Size < Size ||
      Addr + Size > uintptr_t(M.getBufferEnd()) ||
      Addr < uintptr_t(M.getBufferStart())) {
    return std::make_error_code(std::errc::bad_address);
  }
  return std::error_code();
}

static Error checkOffset(MemoryBufferRef M, uintptr_t Addr,
                         const uint64_t Size) {
  if (Addr + Size < Addr || Addr + Size < Size ||
      Addr + Size > uintptr_t(M.getBufferEnd()) ||
      Addr < uintptr_t(M.getBufferStart())) {
    return make_error<RawError>(raw_error_code::corrupt_file,
                                "Invalid buffer address");
  }
  return Error::success();
}

 void notifyObjectCompiled(const Module *M, MemoryBufferRef Obj) override {
   const std::string &ModuleID = M->getModuleIdentifier();
   std::string CacheName;
   if (!getCacheFilename(ModuleID, CacheName))
     return;
   if (!CacheDir.empty()) { // Create user-defined cache dir.
     SmallString<128> dir(sys::path::parent_path(CacheName));
     sys::fs::create_directories(Twine(dir));
   }
   std::error_code EC;
   raw_fd_ostream outfile(CacheName, EC, sys::fs::F_None);
   outfile.write(Obj.getBufferStart(), Obj.getBufferSize());
   outfile.close();
 }

std::unique_ptr<Module> llvm::parseIR(MemoryBufferRef Buffer, SMDiagnostic &Err,
                                      LLVMContext &Context) {
  NamedRegionTimer T(TimeIRParsingName, TimeIRParsingGroupName,
                     TimePassesIsEnabled);
  if (isBitcode((const unsigned char *)Buffer.getBufferStart(),
                (const unsigned char *)Buffer.getBufferEnd())) {
    ErrorOr<std::unique_ptr<Module>> ModuleOrErr =
        parseBitcodeFile(Buffer, Context);
    if (std::error_code EC = ModuleOrErr.getError()) {
      Err = SMDiagnostic(Buffer.getBufferIdentifier(), SourceMgr::DK_Error,
                         EC.message());
      return nullptr;
    }
    return std::move(ModuleOrErr.get());
  }

  return parseAssembly(Buffer, Err, Context);
}

std::error_code PDBFile::parseFileHeaders() {
  std::error_code EC;
  MemoryBufferRef BufferRef = *Context->Buffer;

  Context->SB =
      reinterpret_cast<const SuperBlock *>(BufferRef.getBufferStart());
  const SuperBlock *SB = Context->SB;

  // Make sure the file is sufficiently large to hold a super block.
  if (BufferRef.getBufferSize() < sizeof(SuperBlock))
    return std::make_error_code(std::errc::illegal_byte_sequence);

  // Check the magic bytes.
  if (memcmp(SB->MagicBytes, Magic, sizeof(Magic)) != 0)
    return std::make_error_code(std::errc::illegal_byte_sequence);

  // We don't support blocksizes which aren't a multiple of four bytes.
  if (SB->BlockSize == 0 || SB->BlockSize % sizeof(support::ulittle32_t) != 0)
    return std::make_error_code(std::errc::not_supported);

  // We don't support directories whose sizes aren't a multiple of four bytes.
  if (SB->NumDirectoryBytes % sizeof(support::ulittle32_t) != 0)
    return std::make_error_code(std::errc::not_supported);

  // The number of blocks which comprise the directory is a simple function of
  // the number of bytes it contains.
  uint64_t NumDirectoryBlocks = getNumDirectoryBlocks();

  // The block map, as we understand it, is a block which consists of a list of
  // block numbers.
  // It is unclear what would happen if the number of blocks couldn't fit on a
  // single block.
  if (NumDirectoryBlocks > SB->BlockSize / sizeof(support::ulittle32_t))
    return std::make_error_code(std::errc::illegal_byte_sequence);

  return std::error_code();
}

Error PDBFile::parseStreamData() {
  assert(Context && Context->SB);

  bool SeenNumStreams = false;
  uint32_t NumStreams = 0;
  uint32_t StreamIdx = 0;
  uint64_t DirectoryBytesRead = 0;

  MemoryBufferRef M = *Context->Buffer;
  const SuperBlock *SB = Context->SB;

  auto DirectoryBlocks = getDirectoryBlockArray();

  // The structure of the directory is as follows:
  //    struct PDBDirectory {
  //      uint32_t NumStreams;
  //      uint32_t StreamSizes[NumStreams];
  //      uint32_t StreamMap[NumStreams][];
  //    };
  //
  //  Empty streams don't consume entries in the StreamMap.
  for (uint32_t DirectoryBlockAddr : DirectoryBlocks) {
    uint64_t DirectoryBlockOffset =
        blockToOffset(DirectoryBlockAddr, SB->BlockSize);
    auto DirectoryBlock =
        makeArrayRef(reinterpret_cast<const support::ulittle32_t *>(
                         M.getBufferStart() + DirectoryBlockOffset),
                     SB->BlockSize / sizeof(support::ulittle32_t));
    if (auto EC = checkOffset(M, DirectoryBlock))
      return EC;

    // We read data out of the directory four bytes at a time.  Depending on
    // where we are in the directory, the contents may be: the number of streams
    // in the directory, a stream's size, or a block in the stream map.
    for (uint32_t Data : DirectoryBlock) {
      // Don't read beyond the end of the directory.
      if (DirectoryBytesRead == SB->NumDirectoryBytes)
        break;

      DirectoryBytesRead += sizeof(Data);

      // This data must be the number of streams if we haven't seen it yet.
      if (!SeenNumStreams) {
        NumStreams = Data;
        SeenNumStreams = true;
        continue;
      }
      // This data must be a stream size if we have not seen them all yet.
      if (Context->StreamSizes.size() < NumStreams) {
        // It seems like some streams have their set to -1 when their contents
        // are not present.  Treat them like empty streams for now.
        if (Data == UINT32_MAX)
          Context->StreamSizes.push_back(0);
        else
          Context->StreamSizes.push_back(Data);
        continue;
      }

      // This data must be a stream block number if we have seen all of the
      // stream sizes.
      std::vector<uint32_t> *StreamBlocks = nullptr;
      // Figure out which stream this block number belongs to.
      while (StreamIdx < NumStreams) {
        uint64_t NumExpectedStreamBlocks =
            bytesToBlocks(Context->StreamSizes[StreamIdx], SB->BlockSize);
        StreamBlocks = &Context->StreamMap[StreamIdx];
        if (NumExpectedStreamBlocks > StreamBlocks->size())
          break;
        ++StreamIdx;
      }
      // It seems this block doesn't belong to any stream?  The stream is either
      // corrupt or something more mysterious is going on.
      if (StreamIdx == NumStreams)
        return make_error<RawError>(raw_error_code::corrupt_file,
                                    "Orphaned block found?");

      StreamBlocks->push_back(Data);
    }
  }

  // We should have read exactly SB->NumDirectoryBytes bytes.
  assert(DirectoryBytesRead == SB->NumDirectoryBytes);
  return Error::success();
}

Reader::Reader(MemoryBufferRef InputBuffer)
    : InputBuffer(InputBuffer), Current(InputBuffer.getBufferStart()),
      End(InputBuffer.getBufferEnd()) {}