/work/obj-fuzz/dist/include/mozilla/Compression.h

Source (jump to first uncovered line)
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* Various simple compression/decompression functions. */

#ifndef mozilla_Compression_h_
#define mozilla_Compression_h_

#include "mozilla/Assertions.h"
#include "mozilla/Types.h"

namespace mozilla {
namespace Compression {

/**
 * LZ4 is a very fast byte-wise compression algorithm.
 *
 * Compared to Google's Snappy it is faster to compress and decompress and
 * generally produces output of about the same size.
 *
 * Compared to zlib it compresses at about 10x the speed, decompresses at about
 * 4x the speed and produces output of about 1.5x the size.
 */

class LZ4
{
public:
  /**
   * Compresses |aInputSize| bytes from |aSource| into |aDest|. Destination
   * buffer must be already allocated, and must be sized to handle worst cases
   * situations (input data not compressible). Worst case size evaluation is
   * provided by function maxCompressedSize()
   *
   * @param aInputSize is the input size. Max supported value is ~1.9GB
   * @return the number of bytes written in buffer |aDest|
   */
  static MFBT_API size_t
  compress(const char* aSource, size_t aInputSize, char* aDest);

  /**
   * Compress |aInputSize| bytes from |aSource| into an output buffer
   * |aDest| of maximum size |aMaxOutputSize|.  If it cannot achieve it,
   * compression will stop, and result of the function will be zero,
   * |aDest| will still be written to, but since the number of input
   * bytes consumed is not returned the result is not usable.
   *
   * This function never writes outside of provided output buffer.
   *
   * @param aInputSize is the input size. Max supported value is ~1.9GB
   * @param aMaxOutputSize is the size of the destination buffer (which must
   *   be already allocated)
   * @return the number of bytes written in buffer |aDest| or 0 if the
   *   compression fails
   */
  static MFBT_API size_t
  compressLimitedOutput(const char* aSource, size_t aInputSize, char* aDest,
                        size_t aMaxOutputSize);

  /**
   * If the source stream is malformed, the function will stop decoding
   * and return false.
   *
   * This function never writes outside of provided buffers, and never
   * modifies input buffer.
   *
   * Note: destination buffer must be already allocated, and its size must be a
   *       minimum of |aOutputSize| bytes.
   *
   * @param aOutputSize is the output size, therefore the original size
   * @return true on success, false on failure
   */
  static MFBT_API MOZ_MUST_USE bool
  decompress(const char* aSource, char* aDest, size_t aOutputSize);

  /**
   * If the source stream is malformed, the function will stop decoding
   * and return false.
   *
   * This function never writes beyond aDest + aMaxOutputSize, and is
   * therefore protected against malicious data packets.
   *
   * Note: Destination buffer must be already allocated.  This version is
   *       slightly slower than the decompress without the aMaxOutputSize.
   *
   * @param aInputSize is the length of the input compressed data
   * @param aMaxOutputSize is the size of the destination buffer (which must be
   *   already allocated)
   * @param aOutputSize the actual number of bytes decoded in the destination
   *   buffer (necessarily <= aMaxOutputSize)
   * @return true on success, false on failure
   */
  static MFBT_API MOZ_MUST_USE bool
  decompress(const char* aSource, size_t aInputSize, char* aDest,
             size_t aMaxOutputSize, size_t* aOutputSize);

  /**
   * If the source stream is malformed, the function will stop decoding
   * and return false.
   *
   * This function never writes beyond aDest + aMaxOutputSize, and is
   * therefore protected against malicious data packets. It also ignores
   * unconsumed input upon reaching aMaxOutputSize and can therefore be used
   * for partial decompression.
   *
   * Note: Destination buffer must be already allocated.  This version is
   *       slightly slower than the decompress without the aMaxOutputSize.
   *
   * @param aInputSize is the length of the input compressed data
   * @param aMaxOutputSize is the size of the destination buffer (which must be
   *   already allocated)
   * @param aOutputSize the actual number of bytes decoded in the destination
   *   buffer (necessarily <= aMaxOutputSize)
   * @return true on success, false on failure
   */
  static MFBT_API MOZ_MUST_USE bool
  decompressPartial(const char* aSource, size_t aInputSize, char* aDest,
                    size_t aMaxOutputSize, size_t* aOutputSize);

  /*
   * Provides the maximum size that LZ4 may output in a "worst case"
   * scenario (input data not compressible) primarily useful for memory
   * allocation of output buffer.
   * note : this function is limited by "int" range (2^31-1)
   *
   * @param aInputSize is the input size. Max supported value is ~1.9GB
   * @return maximum output size in a "worst case" scenario
   */
  static inline size_t maxCompressedSize(size_t aInputSize)
  {
    size_t max = (aInputSize + (aInputSize / 255) + 16);
    MOZ_ASSERT(max > aInputSize);
    return max;
  }
};

} /* namespace Compression */
} /* namespace mozilla */

#endif /* mozilla_Compression_h_ */

Line	Count	Source (jump to first uncovered line)
1		/* -- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -- */
2		/* vim: set ts=8 sts=2 et sw=2 tw=80: */
3		/* This Source Code Form is subject to the terms of the Mozilla Public
4		* License, v. 2.0. If a copy of the MPL was not distributed with this
5		* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6
7		/* Various simple compression/decompression functions. */
8
9		#ifndef mozilla_Compression_h_
10		#define mozilla_Compression_h_
11
12		#include "mozilla/Assertions.h"
13		#include "mozilla/Types.h"
14
15		namespace mozilla {
16		namespace Compression {
17
18		/**
19		* LZ4 is a very fast byte-wise compression algorithm.
20		*
21		* Compared to Google's Snappy it is faster to compress and decompress and
22		* generally produces output of about the same size.
23		*
24		* Compared to zlib it compresses at about 10x the speed, decompresses at about
25		* 4x the speed and produces output of about 1.5x the size.
26		*/
27
28		class LZ4
29		{
30		public:
31		/**
32		* Compresses \|aInputSize\| bytes from \|aSource\| into \|aDest\|. Destination
33		* buffer must be already allocated, and must be sized to handle worst cases
34		* situations (input data not compressible). Worst case size evaluation is
35		* provided by function maxCompressedSize()
36		*
37		* @param aInputSize is the input size. Max supported value is ~1.9GB
38		* @return the number of bytes written in buffer \|aDest\|
39		*/
40		static MFBT_API size_t
41		compress(const char* aSource, size_t aInputSize, char* aDest);
42
43		/**
44		* Compress \|aInputSize\| bytes from \|aSource\| into an output buffer
45		* \|aDest\| of maximum size \|aMaxOutputSize\|. If it cannot achieve it,
46		* compression will stop, and result of the function will be zero,
47		* \|aDest\| will still be written to, but since the number of input
48		* bytes consumed is not returned the result is not usable.
49		*
50		* This function never writes outside of provided output buffer.
51		*
52		* @param aInputSize is the input size. Max supported value is ~1.9GB
53		* @param aMaxOutputSize is the size of the destination buffer (which must
54		* be already allocated)
55		* @return the number of bytes written in buffer \|aDest\| or 0 if the
56		* compression fails
57		*/
58		static MFBT_API size_t
59		compressLimitedOutput(const char* aSource, size_t aInputSize, char* aDest,
60		size_t aMaxOutputSize);
61
62		/**
63		* If the source stream is malformed, the function will stop decoding
64		* and return false.
65		*
66		* This function never writes outside of provided buffers, and never
67		* modifies input buffer.
68		*
69		* Note: destination buffer must be already allocated, and its size must be a
70		* minimum of \|aOutputSize\| bytes.
71		*
72		* @param aOutputSize is the output size, therefore the original size
73		* @return true on success, false on failure
74		*/
75		static MFBT_API MOZ_MUST_USE bool
76		decompress(const char* aSource, char* aDest, size_t aOutputSize);
77
78		/**
79		* If the source stream is malformed, the function will stop decoding
80		* and return false.
81		*
82		* This function never writes beyond aDest + aMaxOutputSize, and is
83		* therefore protected against malicious data packets.
84		*
85		* Note: Destination buffer must be already allocated. This version is
86		* slightly slower than the decompress without the aMaxOutputSize.
87		*
88		* @param aInputSize is the length of the input compressed data
89		* @param aMaxOutputSize is the size of the destination buffer (which must be
90		* already allocated)
91		* @param aOutputSize the actual number of bytes decoded in the destination
92		* buffer (necessarily <= aMaxOutputSize)
93		* @return true on success, false on failure
94		*/
95		static MFBT_API MOZ_MUST_USE bool
96		decompress(const char* aSource, size_t aInputSize, char* aDest,
97		size_t aMaxOutputSize, size_t* aOutputSize);
98
99		/**
100		* If the source stream is malformed, the function will stop decoding
101		* and return false.
102		*
103		* This function never writes beyond aDest + aMaxOutputSize, and is
104		* therefore protected against malicious data packets. It also ignores
105		* unconsumed input upon reaching aMaxOutputSize and can therefore be used
106		* for partial decompression.
107		*
108		* Note: Destination buffer must be already allocated. This version is
109		* slightly slower than the decompress without the aMaxOutputSize.
110		*
111		* @param aInputSize is the length of the input compressed data
112		* @param aMaxOutputSize is the size of the destination buffer (which must be
113		* already allocated)
114		* @param aOutputSize the actual number of bytes decoded in the destination
115		* buffer (necessarily <= aMaxOutputSize)
116		* @return true on success, false on failure
117		*/
118		static MFBT_API MOZ_MUST_USE bool
119		decompressPartial(const char* aSource, size_t aInputSize, char* aDest,
120		size_t aMaxOutputSize, size_t* aOutputSize);
121
122		/*
123		* Provides the maximum size that LZ4 may output in a "worst case"
124		* scenario (input data not compressible) primarily useful for memory
125		* allocation of output buffer.
126		* note : this function is limited by "int" range (2^31-1)
127		*
128		* @param aInputSize is the input size. Max supported value is ~1.9GB
129		* @return maximum output size in a "worst case" scenario
130		*/
131		static inline size_t maxCompressedSize(size_t aInputSize)
132	0	{
133	0	size_t max = (aInputSize + (aInputSize / 255) + 16);
134	0	MOZ_ASSERT(max > aInputSize);
135	0	return max;
136	0	} Unexecuted instantiation: mozilla::Compression::LZ4::maxCompressedSize(unsigned long) Unexecuted instantiation: mozilla::Compression::LZ4::maxCompressedSize(unsigned long)
137		};
138
139		} /* namespace Compression */
140		} /* namespace mozilla */
141
142		#endif /* mozilla_Compression_h_ */

Coverage Report

Created: 2018-09-25 14:53