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Add the DataExtractor utility class.

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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
This commit is contained in:
Benjamin Kramer 2011-09-13 19:42:16 +00:00
parent df24e1fb08
commit 8c74f7f299
4 changed files with 639 additions and 0 deletions
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352
include/llvm/Support/DataExtractor.h Normal file
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//===-- 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

1
lib/Support/CMakeLists.txt
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@ -15,6 +15,7 @@ add_llvm_library(LLVMSupport
CommandLine.cpp
ConstantRange.cpp
CrashRecoveryContext.cpp
DataExtractor.cpp
Debug.cpp
DeltaAlgorithm.cpp
DAGDeltaAlgorithm.cpp

175
lib/Support/DataExtractor.cpp Normal file
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//===-- 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;
}

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unittests/Support/DataExtractorTest.cpp Normal file
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//===- 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);
}
}