First round of dead file removal

obsolete/breakpad/common/dwarf/bytereader.h

-// -*- 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,
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-// 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"
-#include "common/dwarf/dwarf2enums.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
-};
-
-// A ByteReader knows how to read single- and multi-byte values of
-// various endiannesses, sizes, and encodings, as used in DWARF
-// debugging information and Linux C++ exception handling data.
-class ByteReader {
- public:
-  // Construct a ByteReader capable of reading one-, two-, four-, and
-  // eight-byte values according to ENDIANNESS, absolute machine-sized
-  // addresses, DWARF-style "initial length" values, signed and
-  // unsigned LEB128 numbers, and Linux C++ exception handling data's
-  // encoded pointers.
-  explicit ByteReader(enum Endianness endianness);
-  virtual ~ByteReader();
-
-  // 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 them as an unsigned 16 bit
-  // number, using this ByteReader's endianness.
-  uint16 ReadTwoBytes(const char* buffer) const;
-
-  // Read four bytes from BUFFER and return them as an unsigned 32 bit
-  // number, using this ByteReader's endianness. 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 them as an unsigned 64
-  // bit number, using this ByteReader's endianness.
-  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. Set LEN to
-  // the number of bytes read.
-  //
-  // The unsigned LEB128 representation of an integer N is a variable
-  // number of bytes:
-  //
-  // - If N is between 0 and 0x7f, then its unsigned LEB128
-  //   representation is a single byte whose value is N.
-  // 
-  // - Otherwise, its unsigned LEB128 representation is (N & 0x7f) |
-  //   0x80, followed by the unsigned LEB128 representation of N /
-  //   128, rounded towards negative infinity.
-  //
-  // In other words, we break VALUE into groups of seven bits, put
-  // them in little-endian order, and then write them as eight-bit
-  // bytes with the high bit on all but the last.
-  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. Set LEN to the number of bytes read.
-  //
-  // The signed LEB128 representation of an integer N is a variable
-  // number of bytes:
-  //
-  // - If N is between -0x40 and 0x3f, then its signed LEB128
-  //   representation is a single byte whose value is N in two's
-  //   complement.
-  // 
-  // - Otherwise, its signed LEB128 representation is (N & 0x7f) |
-  //   0x80, followed by the signed LEB128 representation of N / 128,
-  //   rounded towards negative infinity.
-  //
-  // In other words, we break VALUE into groups of seven bits, put
-  // them in little-endian order, and then write them as eight-bit
-  // bytes with the high bit on all but the last.
-  int64 ReadSignedLEB128(const char* buffer, size_t* len) const;
-
-  // Indicate that addresses on this architecture are SIZE bytes long. SIZE
-  // must be either 4 or 8. (DWARF allows addresses to be any number of
-  // bytes in length from 1 to 255, but we only support 32- and 64-bit
-  // addresses at the moment.) You must call this before using the
-  // ReadAddress member function.
-  //
-  // For data in a .debug_info section, or something that .debug_info
-  // refers to like line number or macro data, the compilation unit
-  // header's address_size field indicates the address size to use. Call
-  // frame information doesn't indicate its address size (a shortcoming of
-  // the spec); you must supply the appropriate size based on the
-  // architecture of the target machine.
-  void SetAddressSize(uint8 size);
-
-  // Return the current address size, in bytes. This is either 4,
-  // indicating 32-bit addresses, or 8, indicating 64-bit addresses.
-  uint8 AddressSize() const { return address_size_; }
-
-  // Read an address from BUFFER and return it as an unsigned 64 bit
-  // integer, respecting this ByteReader's endianness and address size. You
-  // must call SetAddressSize before calling this function.
-  uint64 ReadAddress(const char* buffer) const;
-
-  // DWARF actually defines two slightly different formats: 32-bit DWARF
-  // and 64-bit DWARF. This is *not* related to the size of registers or
-  // addresses on the target machine; it refers only to the size of section
-  // offsets and data lengths appearing in the DWARF data. One only needs
-  // 64-bit DWARF when the debugging data itself is larger than 4GiB.
-  // 32-bit DWARF can handle x86_64 or PPC64 code just fine, unless the
-  // debugging data itself is very large.
-  //
-  // DWARF information identifies itself as 32-bit or 64-bit DWARF: each
-  // compilation unit and call frame information entry begins with an
-  // "initial length" field, which, in addition to giving the length of the
-  // data, also indicates the size of section offsets and lengths appearing
-  // in that data. The ReadInitialLength member function, below, reads an
-  // initial length and sets the ByteReader's offset size as a side effect.
-  // Thus, in the normal process of reading DWARF data, the appropriate
-  // offset size is set automatically. So, you should only need to call
-  // SetOffsetSize if you are using the same ByteReader to jump from the
-  // midst of one block of DWARF data into another.
-
-  // Read a DWARF "initial length" field from START, and return it as
-  // an unsigned 64 bit integer, respecting this ByteReader's
-  // endianness. Set *LEN to the length of the initial length in
-  // bytes, either four or twelve. As a side effect, set this
-  // ByteReader's offset size to either 4 (if we see a 32-bit DWARF
-  // initial length) or 8 (if we see a 64-bit DWARF initial length).
-  //
-  // A DWARF initial length is either:
-  //
-  // - a byte count stored as an unsigned 32-bit value less than
-  //   0xffffff00, indicating that the data whose length is being
-  //   measured uses the 32-bit DWARF format, or
-  //
-  // - The 32-bit value 0xffffffff, followed by a 64-bit byte count,
-  //   indicating that the data whose length is being measured uses
-  //   the 64-bit DWARF format.
-  uint64 ReadInitialLength(const char* start, size_t* len);
-
-  // Read an offset from BUFFER and return it as an unsigned 64 bit
-  // integer, respecting the ByteReader's endianness. In 32-bit DWARF, the
-  // offset is 4 bytes long; in 64-bit DWARF, the offset is eight bytes
-  // long. You must call ReadInitialLength or SetOffsetSize before calling
-  // this function; see the comments above for details.
-  uint64 ReadOffset(const char* buffer) const;
-
-  // Return the current offset size, in bytes.
-  // A return value of 4 indicates that we are reading 32-bit DWARF.
-  // A return value of 8 indicates that we are reading 64-bit DWARF.
-  uint8 OffsetSize() const { return offset_size_; }
-
-  // Indicate that section offsets and lengths are SIZE bytes long. SIZE
-  // must be either 4 (meaning 32-bit DWARF) or 8 (meaning 64-bit DWARF).
-  // Usually, you should not call this function yourself; instead, let a
-  // call to ReadInitialLength establish the data's offset size
-  // automatically.
-  void SetOffsetSize(uint8 size);
-
-  // The Linux C++ ABI uses a variant of DWARF call frame information
-  // for exception handling. This data is included in the program's
-  // address space as the ".eh_frame" section, and intepreted at
-  // runtime to walk the stack, find exception handlers, and run
-  // cleanup code. The format is mostly the same as DWARF CFI, with
-  // some adjustments made to provide the additional
-  // exception-handling data, and to make the data easier to work with
-  // in memory --- for example, to allow it to be placed in read-only
-  // memory even when describing position-independent code.
-  //
-  // In particular, exception handling data can select a number of
-  // different encodings for pointers that appear in the data, as
-  // described by the DwarfPointerEncoding enum. There are actually
-  // four axes(!) to the encoding:
-  //
-  // - The pointer size: pointers can be 2, 4, or 8 bytes long, or use
-  //   the DWARF LEB128 encoding.
-  //
-  // - The pointer's signedness: pointers can be signed or unsigned.
-  //
-  // - The pointer's base address: the data stored in the exception
-  //   handling data can be the actual address (that is, an absolute
-  //   pointer), or relative to one of a number of different base
-  //   addreses --- including that of the encoded pointer itself, for
-  //   a form of "pc-relative" addressing.
-  //
-  // - The pointer may be indirect: it may be the address where the
-  //   true pointer is stored. (This is used to refer to things via
-  //   global offset table entries, program linkage table entries, or
-  //   other tricks used in position-independent code.)
-  //
-  // There are also two options that fall outside that matrix
-  // altogether: the pointer may be omitted, or it may have padding to
-  // align it on an appropriate address boundary. (That last option
-  // may seem like it should be just another axis, but it is not.)
-
-  // Indicate that the exception handling data is loaded starting at
-  // SECTION_BASE, and that the start of its buffer in our own memory
-  // is BUFFER_BASE. This allows us to find the address that a given
-  // byte in our buffer would have when loaded into the program the
-  // data describes. We need this to resolve DW_EH_PE_pcrel pointers.
-  void SetCFIDataBase(uint64 section_base, const char *buffer_base);
-
-  // Indicate that the base address of the program's ".text" section
-  // is TEXT_BASE. We need this to resolve DW_EH_PE_textrel pointers.
-  void SetTextBase(uint64 text_base);
-
-  // Indicate that the base address for DW_EH_PE_datarel pointers is
-  // DATA_BASE. The proper value depends on the ABI; it is usually the
-  // address of the global offset table, held in a designated register in
-  // position-independent code. You will need to look at the startup code
-  // for the target system to be sure. I tried; my eyes bled.
-  void SetDataBase(uint64 data_base);
-
-  // Indicate that the base address for the FDE we are processing is
-  // FUNCTION_BASE. This is the start address of DW_EH_PE_funcrel
-  // pointers. (This encoding does not seem to be used by the GNU
-  // toolchain.)
-  void SetFunctionBase(uint64 function_base);
-
-  // Indicate that we are no longer processing any FDE, so any use of
-  // a DW_EH_PE_funcrel encoding is an error.
-  void ClearFunctionBase();
-
-  // Return true if ENCODING is a valid pointer encoding.
-  bool ValidEncoding(DwarfPointerEncoding encoding) const;
-
-  // Return true if we have all the information we need to read a
-  // pointer that uses ENCODING. This checks that the appropriate
-  // SetFooBase function for ENCODING has been called.
-  bool UsableEncoding(DwarfPointerEncoding encoding) const;
-
-  // Read an encoded pointer from BUFFER using ENCODING; return the
-  // absolute address it represents, and set *LEN to the pointer's
-  // length in bytes, including any padding for aligned pointers.
-  //
-  // This function calls 'abort' if ENCODING is invalid or refers to a
-  // base address this reader hasn't been given, so you should check
-  // with ValidEncoding and UsableEncoding first if you would rather
-  // die in a more helpful way.
-  uint64 ReadEncodedPointer(const char *buffer, DwarfPointerEncoding encoding,
-                            size_t *len) const;
-
- 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_;
-
-  // Base addresses for Linux C++ exception handling data's encoded pointers.
-  bool have_section_base_, have_text_base_, have_data_base_;
-  bool have_function_base_;
-  uint64 section_base_, text_base_, data_base_, function_base_;
-  const char *buffer_base_;
-};
-
-}  // namespace dwarf2reader
-
-#include "common\dwarf\bytereader-inl.h"
-
-#endif  // COMMON_DWARF_BYTEREADER_H__