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// -*- mode: C++ -*-
// Copyright (c) 2010 Google Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef COMMON_DWARF_BYTEREADER_H__
#define COMMON_DWARF_BYTEREADER_H__
#include <string>
#include "common/dwarf/types.h"
namespace dwarf2reader {
// We can't use the obvious name of LITTLE_ENDIAN and BIG_ENDIAN
// because it conflicts with a macro
enum Endianness {
ENDIANNESS_BIG,
ENDIANNESS_LITTLE
};
// Class that knows how to read both big endian and little endian
// numbers, for use in DWARF2/3 reader.
// Takes an endianness argument.
// To read addresses and offsets, SetAddressSize and SetOffsetSize
// must be called first.
class ByteReader {
public:
explicit ByteReader(enum Endianness endian);
virtual ~ByteReader();
// Set the address size to SIZE, which sets up the ReadAddress member
// so that it works.
void SetAddressSize(uint8 size);
// Set the offset size to SIZE, which sets up the ReadOffset member
// so that it works.
void SetOffsetSize(uint8 size);
// Return the current offset size
uint8 OffsetSize() const { return offset_size_; }
// Return the current address size
uint8 AddressSize() const { return address_size_; }
// Read a single byte from BUFFER and return it as an unsigned 8 bit
// number.
uint8 ReadOneByte(const char* buffer) const;
// Read two bytes from BUFFER and return it as an unsigned 16 bit
// number.
uint16 ReadTwoBytes(const char* buffer) const;
// Read four bytes from BUFFER and return it as an unsigned 32 bit
// number. This function returns a uint64 so that it is compatible
// with ReadAddress and ReadOffset. The number it returns will
// never be outside the range of an unsigned 32 bit integer.
uint64 ReadFourBytes(const char* buffer) const;
// Read eight bytes from BUFFER and return it as an unsigned 64 bit
// number
uint64 ReadEightBytes(const char* buffer) const;
// Read an unsigned LEB128 (Little Endian Base 128) number from
// BUFFER and return it as an unsigned 64 bit integer. LEN is set
// to the length read. Everybody seems to reinvent LEB128 as a
// variable size integer encoding, DWARF has had it for a long time.
uint64 ReadUnsignedLEB128(const char* buffer, size_t* len) const;
// Read a signed LEB128 number from BUFFER and return it as an
// signed 64 bit integer. LEN is set to the length read.
int64 ReadSignedLEB128(const char* buffer, size_t* len) const;
// Read an offset from BUFFER and return it as an unsigned 64 bit
// integer. DWARF2/3 define offsets as either 4 or 8 bytes,
// generally depending on the amount of DWARF2/3 info present.
uint64 ReadOffset(const char* buffer) const;
// Read an address from BUFFER and return it as an unsigned 64 bit
// integer. DWARF2/3 allow addresses to be any size from 0-255
// bytes currently. Internally we support 4 and 8 byte addresses,
// and will CHECK on anything else.
uint64 ReadAddress(const char* buffer) const;
// Read a DWARF2/3 initial length field from START, and report the
// length of the length field in LEN. Return the value of the length
// field. Set this reader's offset size as indicated by the length
// field's encoding.
uint64 ReadInitialLength(const char* start, size_t* len);
private:
// Function pointer type for our address and offset readers.
typedef uint64 (ByteReader::*AddressReader)(const char*) const;
// Read an offset from BUFFER and return it as an unsigned 64 bit
// integer. DWARF2/3 define offsets as either 4 or 8 bytes,
// generally depending on the amount of DWARF2/3 info present.
// This function pointer gets set by SetOffsetSize.
AddressReader offset_reader_;
// Read an address from BUFFER and return it as an unsigned 64 bit
// integer. DWARF2/3 allow addresses to be any size from 0-255
// bytes currently. Internally we support 4 and 8 byte addresses,
// and will CHECK on anything else.
// This function pointer gets set by SetAddressSize.
AddressReader address_reader_;
Endianness endian_;
uint8 address_size_;
uint8 offset_size_;
};
} // namespace dwarf2reader
#endif // COMMON_DWARF_BYTEREADER_H__
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