C++ DWARFDataExtractor::isValidOffsetForDataOfSize方法代码示例

llvm::Error DWARFDebugNames::Header::extract(const DWARFDataExtractor &AS,
                                             uint32_t *Offset) {
  // Check that we can read the fixed-size part.
  if (!AS.isValidOffset(*Offset + sizeof(HeaderPOD) - 1))
    return make_error<StringError>("Section too small: cannot read header.",
                                   inconvertibleErrorCode());

  UnitLength = AS.getU32(Offset);
  Version = AS.getU16(Offset);
  Padding = AS.getU16(Offset);
  CompUnitCount = AS.getU32(Offset);
  LocalTypeUnitCount = AS.getU32(Offset);
  ForeignTypeUnitCount = AS.getU32(Offset);
  BucketCount = AS.getU32(Offset);
  NameCount = AS.getU32(Offset);
  AbbrevTableSize = AS.getU32(Offset);
  AugmentationStringSize = AS.getU32(Offset);

  if (!AS.isValidOffsetForDataOfSize(*Offset, AugmentationStringSize))
    return make_error<StringError>(
        "Section too small: cannot read header augmentation.",
        inconvertibleErrorCode());
  AugmentationString.resize(AugmentationStringSize);
  AS.getU8(Offset, reinterpret_cast<uint8_t *>(AugmentationString.data()),
           AugmentationStringSize);
  *Offset = alignTo(*Offset, 4);
  return Error::success();
}

Optional<DWARFDebugLoc::LocationList>
DWARFDebugLoc::parseOneLocationList(DWARFDataExtractor Data, unsigned *Offset) {
  LocationList LL;
  LL.Offset = *Offset;

  // 2.6.2 Location Lists
  // A location list entry consists of:
  while (true) {
    Entry E;
    if (!Data.isValidOffsetForDataOfSize(*Offset, 2 * Data.getAddressSize())) {
      llvm::errs() << "Location list overflows the debug_loc section.\n";
      return None;
    }

    // 1. A beginning address offset. ...
    E.Begin = Data.getRelocatedAddress(Offset);

    // 2. An ending address offset. ...
    E.End = Data.getRelocatedAddress(Offset);

    // The end of any given location list is marked by an end of list entry,
    // which consists of a 0 for the beginning address offset and a 0 for the
    // ending address offset.
    if (E.Begin == 0 && E.End == 0)
      return LL;

    if (!Data.isValidOffsetForDataOfSize(*Offset, 2)) {
      llvm::errs() << "Location list overflows the debug_loc section.\n";
      return None;
    }

    unsigned Bytes = Data.getU16(Offset);
    if (!Data.isValidOffsetForDataOfSize(*Offset, Bytes)) {
      llvm::errs() << "Location list overflows the debug_loc section.\n";
      return None;
    }
    // A single location description describing the location of the object...
    StringRef str = Data.getData().substr(*Offset, Bytes);
    *Offset += Bytes;
    E.Loc.reserve(str.size());
    std::copy(str.begin(), str.end(), std::back_inserter(E.Loc));
    LL.Entries.push_back(std::move(E));
  }
}

Optional<StrOffsetsContributionDescriptor>
StrOffsetsContributionDescriptor::validateContributionSize(
    DWARFDataExtractor &DA) {
  uint8_t EntrySize = getDwarfOffsetByteSize();
  // In order to ensure that we don't read a partial record at the end of
  // the section we validate for a multiple of the entry size.
  uint64_t ValidationSize = alignTo(Size, EntrySize);
  // Guard against overflow.
  if (ValidationSize >= Size)
    if (DA.isValidOffsetForDataOfSize((uint32_t)Base, ValidationSize))
      return *this;
  return Optional<StrOffsetsContributionDescriptor>();
}

// Look for a DWARF32-formatted contribution to the string offsets table
// starting at a given offset and record it in a descriptor.
static Optional<StrOffsetsContributionDescriptor>
parseDWARF32StringOffsetsTableHeader(DWARFDataExtractor &DA, uint32_t Offset) {
  if (!DA.isValidOffsetForDataOfSize(Offset, 8))
    return None;
  uint32_t ContributionSize = DA.getU32(&Offset);
  if (ContributionSize >= 0xfffffff0)
    return None;
  uint8_t Version = DA.getU16(&Offset);
  (void)DA.getU16(&Offset); // padding
  // The encoded length includes the 2-byte version field and the 2-byte
  // padding, so we need to subtract them out when we populate the descriptor.
  return {{Offset, ContributionSize - 4, Version, DWARF32}};
}

// Look for a DWARF64-formatted contribution to the string offsets table
// starting at a given offset and record it in a descriptor.
static Optional<StrOffsetsContributionDescriptor>
parseDWARF64StringOffsetsTableHeader(DWARFDataExtractor &DA, uint32_t Offset) {
  if (!DA.isValidOffsetForDataOfSize(Offset, 16))
    return Optional<StrOffsetsContributionDescriptor>();

  if (DA.getU32(&Offset) != 0xffffffff)
    return Optional<StrOffsetsContributionDescriptor>();

  uint64_t Size = DA.getU64(&Offset);
  uint8_t Version = DA.getU16(&Offset);
  (void)DA.getU16(&Offset); // padding
  // The encoded length includes the 2-byte version field and the 2-byte
  // padding, so we need to subtract them out when we populate the descriptor.
  return StrOffsetsContributionDescriptor(Offset, Size - 4, Version, DWARF64);
  //return Optional<StrOffsetsContributionDescriptor>(Descriptor);
}