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

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

other-licenses/snappy/src/snappy.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 2005 and onwards Google Inc.
 //
 // 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.
 //
 // A light-weight compression algorithm.  It is designed for speed of
 // compression and decompression, rather than for the utmost in space
 // savings.
 //
 // For getting better compression ratios when you are compressing data
 // with long repeated sequences or compressing data that is similar to
 // other data, while still compressing fast, you might look at first
 // using BMDiff and then compressing the output of BMDiff with
 // Snappy.
 #ifndef UTIL_SNAPPY_SNAPPY_H__
 #define UTIL_SNAPPY_SNAPPY_H__
 #include <stddef.h>
 #include <string>
 #include "snappy-stubs-public.h"
 namespace snappy {
   class Source;
   class Sink;
   // ------------------------------------------------------------------------
   // Generic compression/decompression routines.
   // ------------------------------------------------------------------------
   // Compress the bytes read from "*source" and append to "*sink". Return the
   // number of bytes written.
   size_t Compress(Source* source, Sink* sink);
   bool GetUncompressedLength(Source* source, uint32* result);
   // ------------------------------------------------------------------------
   // Higher-level string based routines (should be sufficient for most users)
   // ------------------------------------------------------------------------
   // Sets "*output" to the compressed version of "input[0,input_length-1]".
   // Original contents of *output are lost.
   //
   // REQUIRES: "input[]" is not an alias of "*output".
   size_t Compress(const char* input, size_t input_length, string* output);
   // Decompresses "compressed[0,compressed_length-1]" to "*uncompressed".
   // Original contents of "*uncompressed" are lost.
   //
   // REQUIRES: "compressed[]" is not an alias of "*uncompressed".
   //
   // returns false if the message is corrupted and could not be decompressed
   bool Uncompress(const char* compressed, size_t compressed_length,
                   string* uncompressed);
   // ------------------------------------------------------------------------
   // Lower-level character array based routines.  May be useful for
   // efficiency reasons in certain circumstances.
   // ------------------------------------------------------------------------
   // REQUIRES: "compressed" must point to an area of memory that is at
   // least "MaxCompressedLength(input_length)" bytes in length.
   //
   // Takes the data stored in "input[0..input_length]" and stores
   // it in the array pointed to by "compressed".
   //
   // "*compressed_length" is set to the length of the compressed output.
   //
   // Example:
   //    char* output = new char[snappy::MaxCompressedLength(input_length)];
   //    size_t output_length;
   //    RawCompress(input, input_length, output, &output_length);
   //    ... Process(output, output_length) ...
   //    delete [] output;
   void RawCompress(const char* input,
                    size_t input_length,
                    char* compressed,
                    size_t* compressed_length);
   // Given data in "compressed[0..compressed_length-1]" generated by
   // calling the Snappy::Compress routine, this routine
   // stores the uncompressed data to
   //    uncompressed[0..GetUncompressedLength(compressed)-1]
   // returns false if the message is corrupted and could not be decrypted
   bool RawUncompress(const char* compressed, size_t compressed_length,
                      char* uncompressed);
   // Given data from the byte source 'compressed' generated by calling
   // the Snappy::Compress routine, this routine stores the uncompressed
   // data to
   //    uncompressed[0..GetUncompressedLength(compressed,compressed_length)-1]
   // returns false if the message is corrupted and could not be decrypted
   bool RawUncompress(Source* compressed, char* uncompressed);
   // Returns the maximal size of the compressed representation of
   // input data that is "source_bytes" bytes in length;
   size_t MaxCompressedLength(size_t source_bytes);
   // REQUIRES: "compressed[]" was produced by RawCompress() or Compress()
   // Returns true and stores the length of the uncompressed data in
   // *result normally.  Returns false on parsing error.
   // This operation takes O(1) time.
   bool GetUncompressedLength(const char* compressed, size_t compressed_length,
                              size_t* result);
   // Returns true iff the contents of "compressed[]" can be uncompressed
   // successfully.  Does not return the uncompressed data.  Takes
   // time proportional to compressed_length, but is usually at least
   // a factor of four faster than actual decompression.
   bool IsValidCompressedBuffer(const char* compressed,
                                size_t compressed_length);
   // *** DO NOT CHANGE THE VALUE OF kBlockSize ***
   //
   // New Compression code chops up the input into blocks of at most
   // the following size.  This ensures that back-references in the
   // output never cross kBlockSize block boundaries.  This can be
   // helpful in implementing blocked decompression.  However the
   // decompression code should not rely on this guarantee since older
   // compression code may not obey it.
   static const int kBlockLog = 15;
   static const size_t kBlockSize = 1 << kBlockLog;
   static const int kMaxHashTableBits = 14;
   static const size_t kMaxHashTableSize = 1 << kMaxHashTableBits;
 }  // end namespace snappy
 #endif  // UTIL_SNAPPY_SNAPPY_H__

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