The Tor Browser: toolkit/crashreporter/google-breakpad/src/common/dwarf/bytereader.h@129ffea94266 (annotated)

toolkit/crashreporter/google-breakpad/src/common/dwarf/bytereader.h@129ffea94266 (annotated)

toolkit/crashreporter/google-breakpad/src/common/dwarf/bytereader.h

Sat, 03 Jan 2015 20:18:00 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Sat, 03 Jan 2015 20:18:00 +0100
branch: TOR_BUG_3246
changeset 7: 129ffea94266
permissions: -rw-r--r--

Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.

 // -*- 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"
 #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
 #endif  // COMMON_DWARF_BYTEREADER_H__

The Tor Browser / annotate

toolkit/crashreporter/google-breakpad/src/common/dwarf/bytereader.h@129ffea94266 (annotated)

toolkit/crashreporter/google-breakpad/src/common/dwarf/bytereader.h