Add the DataExtractor utility class.

It is an endian-aware helper that can read data from a StringRef. It will
come in handy for DWARF parsing. This class is inspired by LLDB's
DataExtractor, but is stripped down to the bare minimum needed for DWARF.

Comes with unit tests!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139626 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/DataExtractor.h

@@ -0,0 +1,352 @@
+//===-- DataExtractor.h -----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_DATAEXTRACTOR_H
+#define LLVM_SUPPORT_DATAEXTRACTOR_H
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/DataTypes.h"
+
+namespace llvm {
+class DataExtractor {
+  StringRef Data;
+  uint8_t IsLittleEndian;
+  uint8_t PointerSize;
+public:
+  /// Construct with a buffer that is owned by the caller.
+  ///
+  /// This constructor allows us to use data that is owned by the
+  /// caller. The data must stay around as long as this object is
+  /// valid.
+  DataExtractor(StringRef Data, bool IsLittleEndian, uint8_t PointerSize)
+    : Data(Data), IsLittleEndian(IsLittleEndian), PointerSize(PointerSize) {}
+
+  /// getData - Get the data pointed to by this extractor.
+  StringRef getData() const { return Data; }
+  /// isLittleEndian - Get the endianess for this extractor.
+  bool isLittleEndian() const { return IsLittleEndian; }
+  /// getAddressSize - Get the address size for this extractor.
+  uint8_t getAddressSize() const { return PointerSize; }
+
+  /// Extract a C string from \a *offset_ptr.
+  ///
+  /// Returns a pointer to a C String from the data at the offset
+  /// pointed to by \a offset_ptr. A variable length NULL terminated C
+  /// string will be extracted and the \a offset_ptr will be
+  /// updated with the offset of the byte that follows the NULL
+  /// terminator byte.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @return
+  ///     A pointer to the C string value in the data. If the offset
+  ///     pointed to by \a offset_ptr is out of bounds, or if the
+  ///     offset plus the length of the C string is out of bounds,
+  ///     NULL will be returned.
+  const char *getCStr(uint32_t *offset_ptr) const;
+
+  /// Extract an unsigned integer of size \a byte_size from \a
+  /// *offset_ptr.
+  ///
+  /// Extract a single unsigned integer value and update the offset
+  /// pointed to by \a offset_ptr. The size of the extracted integer
+  /// is specified by the \a byte_size argument. \a byte_size should
+  /// have a value greater than or equal to one and less than or equal
+  /// to eight since the return value is 64 bits wide. Any
+  /// \a byte_size values less than 1 or greater than 8 will result in
+  /// nothing being extracted, and zero being returned.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @param[in] byte_size
+  ///     The size in byte of the integer to extract.
+  ///
+  /// @return
+  ///     The unsigned integer value that was extracted, or zero on
+  ///     failure.
+  uint64_t getUnsigned(uint32_t *offset_ptr, uint32_t byte_size) const;
+
+  /// Extract an signed integer of size \a byte_size from \a *offset_ptr.
+  ///
+  /// Extract a single signed integer value (sign extending if required)
+  /// and update the offset pointed to by \a offset_ptr. The size of
+  /// the extracted integer is specified by the \a byte_size argument.
+  /// \a byte_size should have a value greater than or equal to one
+  /// and less than or equal to eight since the return value is 64
+  /// bits wide. Any \a byte_size values less than 1 or greater than
+  /// 8 will result in nothing being extracted, and zero being returned.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @param[in] byte_size
+  ///     The size in byte of the integer to extract.
+  ///
+  /// @return
+  ///     The sign extended signed integer value that was extracted,
+  ///     or zero on failure.
+  int64_t getSigned(uint32_t *offset_ptr, uint32_t size) const;
+
+  //------------------------------------------------------------------
+  /// Extract an pointer from \a *offset_ptr.
+  ///
+  /// Extract a single pointer from the data and update the offset
+  /// pointed to by \a offset_ptr. The size of the extracted pointer
+  /// comes from the \a m_addr_size member variable and should be
+  /// set correctly prior to extracting any pointer values.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @return
+  ///     The extracted pointer value as a 64 integer.
+  uint64_t getAddress(uint32_t *offset_ptr) const {
+    return getUnsigned(offset_ptr, PointerSize);
+  }
+
+  /// Extract a uint8_t value from \a *offset_ptr.
+  ///
+  /// Extract a single uint8_t from the binary data at the offset
+  /// pointed to by \a offset_ptr, and advance the offset on success.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @return
+  ///     The extracted uint8_t value.
+  uint8_t getU8(uint32_t *offset_ptr) const;
+
+  /// Extract \a count uint8_t values from \a *offset_ptr.
+  ///
+  /// Extract \a count uint8_t values from the binary data at the
+  /// offset pointed to by \a offset_ptr, and advance the offset on
+  /// success. The extracted values are copied into \a dst.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @param[out] dst
+  ///     A buffer to copy \a count uint8_t values into. \a dst must
+  ///     be large enough to hold all requested data.
+  ///
+  /// @param[in] count
+  ///     The number of uint8_t values to extract.
+  ///
+  /// @return
+  ///     \a dst if all values were properly extracted and copied,
+  ///     NULL otherise.
+  uint8_t *getU8(uint32_t *offset_ptr, uint8_t *dst, uint32_t count) const;
+
+  //------------------------------------------------------------------
+  /// Extract a uint16_t value from \a *offset_ptr.
+  ///
+  /// Extract a single uint16_t from the binary data at the offset
+  /// pointed to by \a offset_ptr, and update the offset on success.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @return
+  ///     The extracted uint16_t value.
+  //------------------------------------------------------------------
+  uint16_t getU16(uint32_t *offset_ptr) const;
+
+  /// Extract \a count uint16_t values from \a *offset_ptr.
+  ///
+  /// Extract \a count uint16_t values from the binary data at the
+  /// offset pointed to by \a offset_ptr, and advance the offset on
+  /// success. The extracted values are copied into \a dst.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @param[out] dst
+  ///     A buffer to copy \a count uint16_t values into. \a dst must
+  ///     be large enough to hold all requested data.
+  ///
+  /// @param[in] count
+  ///     The number of uint16_t values to extract.
+  ///
+  /// @return
+  ///     \a dst if all values were properly extracted and copied,
+  ///     NULL otherise.
+  uint16_t *getU16(uint32_t *offset_ptr, uint16_t *dst, uint32_t count) const;
+
+  /// Extract a uint32_t value from \a *offset_ptr.
+  ///
+  /// Extract a single uint32_t from the binary data at the offset
+  /// pointed to by \a offset_ptr, and update the offset on success.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @return
+  ///     The extracted uint32_t value.
+  uint32_t getU32(uint32_t *offset_ptr) const;
+
+  /// Extract \a count uint32_t values from \a *offset_ptr.
+  ///
+  /// Extract \a count uint32_t values from the binary data at the
+  /// offset pointed to by \a offset_ptr, and advance the offset on
+  /// success. The extracted values are copied into \a dst.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @param[out] dst
+  ///     A buffer to copy \a count uint32_t values into. \a dst must
+  ///     be large enough to hold all requested data.
+  ///
+  /// @param[in] count
+  ///     The number of uint32_t values to extract.
+  ///
+  /// @return
+  ///     \a dst if all values were properly extracted and copied,
+  ///     NULL otherise.
+  uint32_t *getU32(uint32_t *offset_ptr, uint32_t *dst, uint32_t count) const;
+
+  /// Extract a uint64_t value from \a *offset_ptr.
+  ///
+  /// Extract a single uint64_t from the binary data at the offset
+  /// pointed to by \a offset_ptr, and update the offset on success.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @return
+  ///     The extracted uint64_t value.
+  uint64_t getU64(uint32_t *offset_ptr) const;
+
+  /// Extract \a count uint64_t values from \a *offset_ptr.
+  ///
+  /// Extract \a count uint64_t values from the binary data at the
+  /// offset pointed to by \a offset_ptr, and advance the offset on
+  /// success. The extracted values are copied into \a dst.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @param[out] dst
+  ///     A buffer to copy \a count uint64_t values into. \a dst must
+  ///     be large enough to hold all requested data.
+  ///
+  /// @param[in] count
+  ///     The number of uint64_t values to extract.
+  ///
+  /// @return
+  ///     \a dst if all values were properly extracted and copied,
+  ///     NULL otherise.
+  uint64_t *getU64(uint32_t *offset_ptr, uint64_t *dst, uint32_t count) const;
+
+  /// Extract a signed LEB128 value from \a *offset_ptr.
+  ///
+  /// Extracts an signed LEB128 number from this object's data
+  /// starting at the offset pointed to by \a offset_ptr. The offset
+  /// pointed to by \a offset_ptr will be updated with the offset of
+  /// the byte following the last extracted byte.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @return
+  ///     The extracted signed integer value.
+  int64_t getSLEB128(uint32_t *offset_ptr) const;
+
+  /// Extract a unsigned LEB128 value from \a *offset_ptr.
+  ///
+  /// Extracts an unsigned LEB128 number from this object's data
+  /// starting at the offset pointed to by \a offset_ptr. The offset
+  /// pointed to by \a offset_ptr will be updated with the offset of
+  /// the byte following the last extracted byte.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// @return
+  ///     The extracted unsigned integer value.
+  uint64_t getULEB128(uint32_t *offset_ptr) const;
+
+  /// Test the validity of \a offset.
+  ///
+  /// @return
+  ///     \b true if \a offset is a valid offset into the data in this
+  ///     object, \b false otherwise.
+  bool isValidOffset(uint32_t offset) const { return Data.size() > offset; }
+
+  /// Test the availability of \a length bytes of data from \a offset.
+  ///
+  /// @return
+  ///     \b true if \a offset is a valid offset and there are \a
+  ///     length bytes available at that offset, \b false otherwise.
+  bool isValidOffsetForDataOfSize(uint32_t offset, uint32_t length) const {
+    return offset + length >= offset && isValidOffset(offset + length - 1);
+  }
+};
+
+} // namespace llvm
+
+#endif

lib/Support/CMakeLists.txt

@@ -15,6 +15,7 @@ add_llvm_library(LLVMSupport
   CommandLine.cpp
   ConstantRange.cpp
   CrashRecoveryContext.cpp
+  DataExtractor.cpp
   Debug.cpp
   DeltaAlgorithm.cpp
   DAGDeltaAlgorithm.cpp

lib/Support/DataExtractor.cpp

@@ -0,0 +1,175 @@
+//===-- DataExtractor.cpp -------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/DataExtractor.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/SwapByteOrder.h"
+using namespace llvm;
+
+template <typename T>
+static T getU(uint32_t *offset_ptr, const DataExtractor *de,
+              bool isLittleEndian, const char *Data) {
+  T val = 0;
+  uint32_t offset = *offset_ptr;
+  if (de->isValidOffsetForDataOfSize(offset, sizeof(val))) {
+    std::memcpy(&val, &Data[offset], sizeof(val));
+    if (sys::isLittleEndianHost() != isLittleEndian)
+      val = sys::SwapByteOrder(val);
+
+    // Advance the offset
+    *offset_ptr += sizeof(val);
+  }
+  return val;
+}
+
+template <typename T>
+static T *getUs(uint32_t *offset_ptr, T *dst, uint32_t count,
+                const DataExtractor *de, bool isLittleEndian, const char *Data){
+  uint32_t offset = *offset_ptr;
+
+  if (count > 0 && de->isValidOffsetForDataOfSize(offset, sizeof(*dst)*count)) {
+    for (T *value_ptr = dst, *end = dst + count; value_ptr != end;
+        ++value_ptr, offset += sizeof(*dst))
+      *value_ptr = getU<T>(offset_ptr, de, isLittleEndian, Data);
+    // Advance the offset
+    *offset_ptr = offset;
+    // Return a non-NULL pointer to the converted data as an indicator of
+    // success
+    return dst;
+  }
+  return NULL;
+}
+
+uint8_t DataExtractor::getU8(uint32_t *offset_ptr) const {
+  return getU<uint8_t>(offset_ptr, this, IsLittleEndian, Data.data());
+}
+
+uint8_t *
+DataExtractor::getU8(uint32_t *offset_ptr, uint8_t *dst, uint32_t count) const {
+  return getUs<uint8_t>(offset_ptr, dst, count, this, IsLittleEndian,
+                       Data.data());
+}
+
+
+uint16_t DataExtractor::getU16(uint32_t *offset_ptr) const {
+  return getU<uint16_t>(offset_ptr, this, IsLittleEndian, Data.data());
+}
+
+uint16_t *DataExtractor::getU16(uint32_t *offset_ptr, uint16_t *dst,
+                                uint32_t count) const {
+  return getUs<uint16_t>(offset_ptr, dst, count, this, IsLittleEndian,
+                        Data.data());
+}
+
+uint32_t DataExtractor::getU32(uint32_t *offset_ptr) const {
+  return getU<uint32_t>(offset_ptr, this, IsLittleEndian, Data.data());
+}
+
+uint32_t *DataExtractor::getU32(uint32_t *offset_ptr, uint32_t *dst,
+                                uint32_t count) const {
+  return getUs<uint32_t>(offset_ptr, dst, count, this, IsLittleEndian,
+                        Data.data());;
+}
+
+uint64_t DataExtractor::getU64(uint32_t *offset_ptr) const {
+  return getU<uint64_t>(offset_ptr, this, IsLittleEndian, Data.data());
+}
+
+uint64_t *DataExtractor::getU64(uint32_t *offset_ptr, uint64_t *dst,
+                                uint32_t count) const {
+  return getUs<uint64_t>(offset_ptr, dst, count, this, IsLittleEndian,
+                        Data.data());
+}
+
+uint64_t
+DataExtractor::getUnsigned(uint32_t *offset_ptr, uint32_t byte_size) const {
+  switch (byte_size) {
+  case 1:
+    return getU8(offset_ptr);
+  case 2:
+    return getU16(offset_ptr);
+  case 4:
+    return getU32(offset_ptr);
+  case 8:
+    return getU64(offset_ptr);
+  }
+  llvm_unreachable("getUnsigned unhandled case!");
+}
+
+int64_t
+DataExtractor::getSigned(uint32_t *offset_ptr, uint32_t byte_size) const {
+  switch (byte_size) {
+  case 1:
+    return (int8_t)getU8(offset_ptr);
+  case 2:
+    return (int16_t)getU16(offset_ptr);
+  case 4:
+    return (int32_t)getU32(offset_ptr);
+  case 8:
+    return (int64_t)getU64(offset_ptr);
+  }
+  llvm_unreachable("getSigned unhandled case!");
+}
+
+const char *DataExtractor::getCStr(uint32_t *offset_ptr) const {
+  uint32_t offset = *offset_ptr;
+  StringRef::size_type pos = Data.find('\0', offset);
+  if (pos != StringRef::npos) {
+    *offset_ptr = pos + 1;
+    return Data.data() + offset;
+  }
+  return NULL;
+}
+
+uint64_t DataExtractor::getULEB128(uint32_t *offset_ptr) const {
+  uint64_t result = 0;
+  if (Data.empty())
+    return 0;
+
+  unsigned shift = 0;
+  uint32_t offset = *offset_ptr;
+  uint8_t byte = 0;
+
+  while (isValidOffset(offset)) {
+    byte = Data[offset++];
+    result |= (byte & 0x7f) << shift;
+    shift += 7;
+    if ((byte & 0x80) == 0)
+      break;
+  }
+
+  *offset_ptr = offset;
+  return result;
+}
+
+int64_t DataExtractor::getSLEB128(uint32_t *offset_ptr) const {
+  int64_t result = 0;
+  if (Data.empty())
+    return 0;
+
+  unsigned shift = 0;
+  uint32_t offset = *offset_ptr;
+  uint8_t byte = 0;
+
+  while (isValidOffset(offset)) {
+    byte = Data[offset++];
+    result |= (byte & 0x7f) << shift;
+    shift += 7;
+    if ((byte & 0x80) == 0)
+      break;
+  }
+
+  // Sign bit of byte is 2nd high order bit (0x40)
+  if (shift < 64 && (byte & 0x40))
+    result |= -(1 << shift);
+
+  *offset_ptr = offset;
+  return result;
+}

unittests/Support/DataExtractorTest.cpp

@@ -0,0 +1,111 @@
+//===- llvm/unittest/Support/DataExtractorTest.cpp - DataExtractor tests --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+#include "llvm/Support/DataExtractor.h"
+using namespace llvm;
+
+namespace {
+
+const char numberData[] = "\x80\x90\xFF\xFF\x80\x00\x00\x00";
+const char stringData[] = "hellohello\0hello";
+const char leb128data[] = "\xA6\x49";
+
+TEST(DataExtractorTest, OffsetOverflow) {
+  DataExtractor DE(StringRef(numberData, sizeof(numberData)-1), false, 8);
+  EXPECT_FALSE(DE.isValidOffsetForDataOfSize(-2U, 5));
+}
+
+TEST(DataExtractorTest, UnsignedNumbers) {
+  DataExtractor DE(StringRef(numberData, sizeof(numberData)-1), false, 8);
+  uint32_t offset = 0;
+
+  EXPECT_EQ(0x80U, DE.getU8(&offset));
+  EXPECT_EQ(1U, offset);
+  offset = 0;
+  EXPECT_EQ(0x8090U, DE.getU16(&offset));
+  EXPECT_EQ(2U, offset);
+  offset = 0;
+  EXPECT_EQ(0x8090FFFFU, DE.getU32(&offset));
+  EXPECT_EQ(4U, offset);
+  offset = 0;
+  EXPECT_EQ(0x8090FFFF80000000U, DE.getU64(&offset));
+  EXPECT_EQ(8U, offset);
+  offset = 0;
+  EXPECT_EQ(0x8090FFFF80000000U, DE.getAddress(&offset));
+  EXPECT_EQ(8U, offset);
+  offset = 0;
+
+  uint32_t data[2];
+  EXPECT_EQ(data, DE.getU32(&offset, data, 2));
+  EXPECT_EQ(0x8090FFFFU, data[0]);
+  EXPECT_EQ(0x80000000U, data[1]);
+  EXPECT_EQ(8U, offset);
+  offset = 0;
+
+  // Now for little endian.
+  DE = DataExtractor(StringRef(numberData, sizeof(numberData)-1), true, 4);
+  EXPECT_EQ(0x9080U, DE.getU16(&offset));
+  EXPECT_EQ(2U, offset);
+  offset = 0;
+  EXPECT_EQ(0xFFFF9080U, DE.getU32(&offset));
+  EXPECT_EQ(4U, offset);
+  offset = 0;
+  EXPECT_EQ(0x80FFFF9080U, DE.getU64(&offset));
+  EXPECT_EQ(8U, offset);
+  offset = 0;
+  EXPECT_EQ(0xFFFF9080U, DE.getAddress(&offset));
+  EXPECT_EQ(4U, offset);
+  offset = 0;
+
+  EXPECT_EQ(data, DE.getU32(&offset, data, 2));
+  EXPECT_EQ(0xFFFF9080U, data[0]);
+  EXPECT_EQ(0x80U, data[1]);
+  EXPECT_EQ(8U, offset);
+}
+
+TEST(DataExtractorTest, SignedNumbers) {
+  DataExtractor DE(StringRef(numberData, sizeof(numberData)-1), false, 8);
+  uint32_t offset = 0;
+
+  EXPECT_EQ(-128, DE.getSigned(&offset, 1));
+  EXPECT_EQ(1U, offset);
+  offset = 0;
+  EXPECT_EQ(-32624, DE.getSigned(&offset, 2));
+  EXPECT_EQ(2U, offset);
+  offset = 0;
+  EXPECT_EQ(-2137980929, DE.getSigned(&offset, 4));
+  EXPECT_EQ(4U, offset);
+  offset = 0;
+  EXPECT_EQ(-9182558167379214336LL, DE.getSigned(&offset, 8));
+  EXPECT_EQ(8U, offset);
+}
+
+TEST(DataExtractorTest, Strings) {
+  DataExtractor DE(StringRef(stringData, sizeof(stringData)-1), false, 8);
+  uint32_t offset = 0;
+
+  EXPECT_EQ(stringData, DE.getCStr(&offset));
+  EXPECT_EQ(11U, offset);
+  EXPECT_EQ(NULL, DE.getCStr(&offset));
+  EXPECT_EQ(11U, offset);
+}
+
+TEST(DataExtractorTest, LEB128) {
+  DataExtractor DE(StringRef(leb128data, sizeof(leb128data)-1), false, 8);
+  uint32_t offset = 0;
+
+  EXPECT_EQ(9382ULL, DE.getULEB128(&offset));
+  EXPECT_EQ(2U, offset);
+  offset = 0;
+  EXPECT_EQ(-7002LL, DE.getSLEB128(&offset));
+  EXPECT_EQ(2U, offset);
+}
+
+}