The Tor Browser: other-licenses/snappy/src/snappy-stubs-internal.h@97036ab72558 (annotated)

other-licenses/snappy/src/snappy-stubs-internal.h@97036ab72558 (annotated)

other-licenses/snappy/src/snappy-stubs-internal.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 // Copyright 2011 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.
 //
 // Various stubs for the open-source version of Snappy.
 #ifndef UTIL_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_
 #define UTIL_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
 #include <iostream>
 #include <string>
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 #ifdef HAVE_SYS_MMAN_H
 #include <sys/mman.h>
 #endif
 #include "snappy-stubs-public.h"
 #if defined(__x86_64__)
 // Enable 64-bit optimized versions of some routines.
 #define ARCH_K8 1
 #endif
 // Needed by OS X, among others.
 #ifndef MAP_ANONYMOUS
 #define MAP_ANONYMOUS MAP_ANON
 #endif
 // Pull in std::min, std::ostream, and the likes. This is safe because this
 // header file is never used from any public header files.
 using namespace std;
 // The size of an array, if known at compile-time.
 // Will give unexpected results if used on a pointer.
 // We undefine it first, since some compilers already have a definition.
 #ifdef ARRAYSIZE
 #undef ARRAYSIZE
 #endif
 #define ARRAYSIZE(a) (sizeof(a) / sizeof(*(a)))
 // Static prediction hints.
 #ifdef HAVE_BUILTIN_EXPECT
 #define PREDICT_FALSE(x) (__builtin_expect(x, 0))
 #define PREDICT_TRUE(x) (__builtin_expect(!!(x), 1))
 #else
 #define PREDICT_FALSE(x) x
 #define PREDICT_TRUE(x) x
 #endif
 // This is only used for recomputing the tag byte table used during
 // decompression; for simplicity we just remove it from the open-source
 // version (anyone who wants to regenerate it can just do the call
 // themselves within main()).
 #define DEFINE_bool(flag_name, default_value, description) \
   bool FLAGS_ ## flag_name = default_value
 #define DECLARE_bool(flag_name) \
   extern bool FLAGS_ ## flag_name
 namespace snappy {
 static const uint32 kuint32max = static_cast<uint32>(0xFFFFFFFF);
 static const int64 kint64max = static_cast<int64>(0x7FFFFFFFFFFFFFFFLL);
 // Logging.
 #define LOG(level) LogMessage()
 #define VLOG(level) true ? (void)0 : \
     snappy::LogMessageVoidify() & snappy::LogMessage()
 class LogMessage {
  public:
   LogMessage() { }
   ~LogMessage() {
     cerr << endl;
   }
   LogMessage& operator<<(const std::string& msg) {
     cerr << msg;
     return *this;
   }
   LogMessage& operator<<(int x) {
     cerr << x;
     return *this;
   }
 };
 // Asserts, both versions activated in debug mode only,
 // and ones that are always active.
 #define CRASH_UNLESS(condition) \
     PREDICT_TRUE(condition) ? (void)0 : \
     snappy::LogMessageVoidify() & snappy::LogMessageCrash()
 class LogMessageCrash : public LogMessage {
  public:
   LogMessageCrash() { }
   ~LogMessageCrash() {
     cerr << endl;
     abort();
   }
 };
 // This class is used to explicitly ignore values in the conditional
 // logging macros.  This avoids compiler warnings like "value computed
 // is not used" and "statement has no effect".
 class LogMessageVoidify {
  public:
   LogMessageVoidify() { }
   // This has to be an operator with a precedence lower than << but
   // higher than ?:
   void operator&(const LogMessage&) { }
 };
 #define CHECK(cond) CRASH_UNLESS(cond)
 #define CHECK_LE(a, b) CRASH_UNLESS((a) <= (b))
 #define CHECK_GE(a, b) CRASH_UNLESS((a) >= (b))
 #define CHECK_EQ(a, b) CRASH_UNLESS((a) == (b))
 #define CHECK_NE(a, b) CRASH_UNLESS((a) != (b))
 #define CHECK_LT(a, b) CRASH_UNLESS((a) < (b))
 #define CHECK_GT(a, b) CRASH_UNLESS((a) > (b))
 #ifdef NDEBUG
 #define DCHECK(cond) CRASH_UNLESS(true)
 #define DCHECK_LE(a, b) CRASH_UNLESS(true)
 #define DCHECK_GE(a, b) CRASH_UNLESS(true)
 #define DCHECK_EQ(a, b) CRASH_UNLESS(true)
 #define DCHECK_NE(a, b) CRASH_UNLESS(true)
 #define DCHECK_LT(a, b) CRASH_UNLESS(true)
 #define DCHECK_GT(a, b) CRASH_UNLESS(true)
 #else
 #define DCHECK(cond) CHECK(cond)
 #define DCHECK_LE(a, b) CHECK_LE(a, b)
 #define DCHECK_GE(a, b) CHECK_GE(a, b)
 #define DCHECK_EQ(a, b) CHECK_EQ(a, b)
 #define DCHECK_NE(a, b) CHECK_NE(a, b)
 #define DCHECK_LT(a, b) CHECK_LT(a, b)
 #define DCHECK_GT(a, b) CHECK_GT(a, b)
 #endif
 // Potentially unaligned loads and stores.
 #if defined(__i386__) || defined(__x86_64__) || defined(__powerpc__)
 #define UNALIGNED_LOAD16(_p) (*reinterpret_cast<const uint16 *>(_p))
 #define UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32 *>(_p))
 #define UNALIGNED_LOAD64(_p) (*reinterpret_cast<const uint64 *>(_p))
 #define UNALIGNED_STORE16(_p, _val) (*reinterpret_cast<uint16 *>(_p) = (_val))
 #define UNALIGNED_STORE32(_p, _val) (*reinterpret_cast<uint32 *>(_p) = (_val))
 #define UNALIGNED_STORE64(_p, _val) (*reinterpret_cast<uint64 *>(_p) = (_val))
 #else
 // These functions are provided for architectures that don't support
 // unaligned loads and stores.
 inline uint16 UNALIGNED_LOAD16(const void *p) {
   uint16 t;
   memcpy(&t, p, sizeof t);
   return t;
 }
 inline uint32 UNALIGNED_LOAD32(const void *p) {
   uint32 t;
   memcpy(&t, p, sizeof t);
   return t;
 }
 inline uint64 UNALIGNED_LOAD64(const void *p) {
   uint64 t;
   memcpy(&t, p, sizeof t);
   return t;
 }
 inline void UNALIGNED_STORE16(void *p, uint16 v) {
   memcpy(p, &v, sizeof v);
 }
 inline void UNALIGNED_STORE32(void *p, uint32 v) {
   memcpy(p, &v, sizeof v);
 }
 inline void UNALIGNED_STORE64(void *p, uint64 v) {
   memcpy(p, &v, sizeof v);
 }
 #endif
 // The following guarantees declaration of the byte swap functions.
 #ifdef WORDS_BIGENDIAN
 #ifdef HAVE_SYS_BYTEORDER_H
 #include <sys/byteorder.h>
 #endif
 #ifdef HAVE_SYS_ENDIAN_H
 #include <sys/endian.h>
 #endif
 #ifdef _MSC_VER
 #include <stdlib.h>
 #define bswap_16(x) _byteswap_ushort(x)
 #define bswap_32(x) _byteswap_ulong(x)
 #define bswap_64(x) _byteswap_uint64(x)
 #elif defined(__APPLE__)
 // Mac OS X / Darwin features
 #include <libkern/OSByteOrder.h>
 #define bswap_16(x) OSSwapInt16(x)
 #define bswap_32(x) OSSwapInt32(x)
 #define bswap_64(x) OSSwapInt64(x)
 #elif defined(HAVE_BYTESWAP_H)
 #include <byteswap.h>
 #elif defined(bswap32)
 // FreeBSD defines bswap{16,32,64} in <sys/endian.h> (already #included).
 #define bswap_16(x) bswap16(x)
 #define bswap_32(x) bswap32(x)
 #define bswap_64(x) bswap64(x)
 #elif defined(BSWAP_64)
 // Solaris 10 defines BSWAP_{16,32,64} in <sys/byteorder.h> (already #included).
 #define bswap_16(x) BSWAP_16(x)
 #define bswap_32(x) BSWAP_32(x)
 #define bswap_64(x) BSWAP_64(x)
 #else
 inline uint16 bswap_16(uint16 x) {
   return (x << 8) | (x >> 8);
 }
 inline uint32 bswap_32(uint32 x) {
   x = ((x & 0xff00ff00UL) >> 8) | ((x & 0x00ff00ffUL) << 8);
   return (x >> 16) | (x << 16);
 }
 inline uint64 bswap_64(uint64 x) {
   x = ((x & 0xff00ff00ff00ff00ULL) >> 8) | ((x & 0x00ff00ff00ff00ffULL) << 8);
   x = ((x & 0xffff0000ffff0000ULL) >> 16) | ((x & 0x0000ffff0000ffffULL) << 16);
   return (x >> 32) | (x << 32);
 }
 #endif
 #endif  // WORDS_BIGENDIAN
 // Convert to little-endian storage, opposite of network format.
 // Convert x from host to little endian: x = LittleEndian.FromHost(x);
 // convert x from little endian to host: x = LittleEndian.ToHost(x);
 //
 //  Store values into unaligned memory converting to little endian order:
 //    LittleEndian.Store16(p, x);
 //
 //  Load unaligned values stored in little endian converting to host order:
 //    x = LittleEndian.Load16(p);
 class LittleEndian {
  public:
   // Conversion functions.
 #ifdef WORDS_BIGENDIAN
   static uint16 FromHost16(uint16 x) { return bswap_16(x); }
   static uint16 ToHost16(uint16 x) { return bswap_16(x); }
   static uint32 FromHost32(uint32 x) { return bswap_32(x); }
   static uint32 ToHost32(uint32 x) { return bswap_32(x); }
   static bool IsLittleEndian() { return false; }
 #else  // !defined(WORDS_BIGENDIAN)
   static uint16 FromHost16(uint16 x) { return x; }
   static uint16 ToHost16(uint16 x) { return x; }
   static uint32 FromHost32(uint32 x) { return x; }
   static uint32 ToHost32(uint32 x) { return x; }
   static bool IsLittleEndian() { return true; }
 #endif  // !defined(WORDS_BIGENDIAN)
   // Functions to do unaligned loads and stores in little-endian order.
   static uint16 Load16(const void *p) {
     return ToHost16(UNALIGNED_LOAD16(p));
   }
   static void Store16(void *p, uint16 v) {
     UNALIGNED_STORE16(p, FromHost16(v));
   }
   static uint32 Load32(const void *p) {
     return ToHost32(UNALIGNED_LOAD32(p));
   }
   static void Store32(void *p, uint32 v) {
     UNALIGNED_STORE32(p, FromHost32(v));
   }
 };
 // Some bit-manipulation functions.
 class Bits {
  public:
   // Return floor(log2(n)) for positive integer n.  Returns -1 iff n == 0.
   static int Log2Floor(uint32 n);
   // Return the first set least / most significant bit, 0-indexed.  Returns an
   // undefined value if n == 0.  FindLSBSetNonZero() is similar to ffs() except
   // that it's 0-indexed.
   static int FindLSBSetNonZero(uint32 n);
   static int FindLSBSetNonZero64(uint64 n);
  private:
   DISALLOW_COPY_AND_ASSIGN(Bits);
 };
 #ifdef HAVE_BUILTIN_CTZ
 inline int Bits::Log2Floor(uint32 n) {
   return n == 0 ? -1 : 31 ^ __builtin_clz(n);
 }
 inline int Bits::FindLSBSetNonZero(uint32 n) {
   return __builtin_ctz(n);
 }
 inline int Bits::FindLSBSetNonZero64(uint64 n) {
   return __builtin_ctzll(n);
 }
 #else  // Portable versions.
 inline int Bits::Log2Floor(uint32 n) {
   if (n == 0)
     return -1;
   int log = 0;
   uint32 value = n;
   for (int i = 4; i >= 0; --i) {
     int shift = (1 << i);
     uint32 x = value >> shift;
     if (x != 0) {
       value = x;
       log += shift;
     }
   }
   assert(value == 1);
   return log;
 }
 inline int Bits::FindLSBSetNonZero(uint32 n) {
   int rc = 31;
   for (int i = 4, shift = 1 << 4; i >= 0; --i) {
     const uint32 x = n << shift;
     if (x != 0) {
       n = x;
       rc -= shift;
     }
     shift >>= 1;
   }
   return rc;
 }
 // FindLSBSetNonZero64() is defined in terms of FindLSBSetNonZero().
 inline int Bits::FindLSBSetNonZero64(uint64 n) {
   const uint32 bottombits = static_cast<uint32>(n);
   if (bottombits == 0) {
     // Bottom bits are zero, so scan in top bits
     return 32 + FindLSBSetNonZero(static_cast<uint32>(n >> 32));
   } else {
     return FindLSBSetNonZero(bottombits);
   }
 }
 #endif  // End portable versions.
 // Variable-length integer encoding.
 class Varint {
  public:
   // Maximum lengths of varint encoding of uint32.
   static const int kMax32 = 5;
   // Attempts to parse a varint32 from a prefix of the bytes in [ptr,limit-1].
   // Never reads a character at or beyond limit.  If a valid/terminated varint32
   // was found in the range, stores it in *OUTPUT and returns a pointer just
   // past the last byte of the varint32. Else returns NULL.  On success,
   // "result <= limit".
   static const char* Parse32WithLimit(const char* ptr, const char* limit,
                                       uint32* OUTPUT);
   // REQUIRES   "ptr" points to a buffer of length sufficient to hold "v".
   // EFFECTS    Encodes "v" into "ptr" and returns a pointer to the
   //            byte just past the last encoded byte.
   static char* Encode32(char* ptr, uint32 v);
   // EFFECTS    Appends the varint representation of "value" to "*s".
   static void Append32(string* s, uint32 value);
 };
 inline const char* Varint::Parse32WithLimit(const char* p,
                                             const char* l,
                                             uint32* OUTPUT) {
   const unsigned char* ptr = reinterpret_cast<const unsigned char*>(p);
   const unsigned char* limit = reinterpret_cast<const unsigned char*>(l);
   uint32 b, result;
   if (ptr >= limit) return NULL;
   b = *(ptr++); result = b & 127;          if (b < 128) goto done;
   if (ptr >= limit) return NULL;
   b = *(ptr++); result |= (b & 127) <<  7; if (b < 128) goto done;
   if (ptr >= limit) return NULL;
   b = *(ptr++); result |= (b & 127) << 14; if (b < 128) goto done;
   if (ptr >= limit) return NULL;
   b = *(ptr++); result |= (b & 127) << 21; if (b < 128) goto done;
   if (ptr >= limit) return NULL;
   b = *(ptr++); result |= (b & 127) << 28; if (b < 16) goto done;
   return NULL;       // Value is too long to be a varint32
  done:
   *OUTPUT = result;
   return reinterpret_cast<const char*>(ptr);
 }
 inline char* Varint::Encode32(char* sptr, uint32 v) {
   // Operate on characters as unsigneds
   unsigned char* ptr = reinterpret_cast<unsigned char*>(sptr);
   static const int B = 128;
   if (v < (1<<7)) {
     *(ptr++) = v;
   } else if (v < (1<<14)) {
     *(ptr++) = v | B;
     *(ptr++) = v>>7;
   } else if (v < (1<<21)) {
     *(ptr++) = v | B;
     *(ptr++) = (v>>7) | B;
     *(ptr++) = v>>14;
   } else if (v < (1<<28)) {
     *(ptr++) = v | B;
     *(ptr++) = (v>>7) | B;
     *(ptr++) = (v>>14) | B;
     *(ptr++) = v>>21;
   } else {
     *(ptr++) = v | B;
     *(ptr++) = (v>>7) | B;
     *(ptr++) = (v>>14) | B;
     *(ptr++) = (v>>21) | B;
     *(ptr++) = v>>28;
   }
   return reinterpret_cast<char*>(ptr);
 }
 // If you know the internal layout of the std::string in use, you can
 // replace this function with one that resizes the string without
 // filling the new space with zeros (if applicable) --
 // it will be non-portable but faster.
 inline void STLStringResizeUninitialized(string* s, size_t new_size) {
   s->resize(new_size);
 }
 // Return a mutable char* pointing to a string's internal buffer,
 // which may not be null-terminated. Writing through this pointer will
 // modify the string.
 //
 // string_as_array(&str)[i] is valid for 0 <= i < str.size() until the
 // next call to a string method that invalidates iterators.
 //
 // As of 2006-04, there is no standard-blessed way of getting a
 // mutable reference to a string's internal buffer. However, issue 530
 // (http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-defects.html#530)
 // proposes this as the method. It will officially be part of the standard
 // for C++0x. This should already work on all current implementations.
 inline char* string_as_array(string* str) {
   return str->empty() ? NULL : &*str->begin();
 }
 }  // namespace snappy
 #endif  // UTIL_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_

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