Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 218 insertions, 0 deletions

diff --git a/mfbt/Compression.h b/mfbt/Compression.h
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+++ b/mfbt/Compression.h
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+/* -*- 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"
+#include "mozilla/ResultVariant.h"
+#include "mozilla/Span.h"
+#include "mozilla/UniquePtr.h"
+
+struct LZ4F_cctx_s;  // compression context
+struct LZ4F_dctx_s;  // decompression context
+
+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 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
+   */
+  [[nodiscard]] static MFBT_API 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
+   */
+  [[nodiscard]] static MFBT_API 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;
+  }
+};
+
+/**
+ * Context for LZ4 Frame-based streaming compression. Use this if you
+ * want to incrementally compress something or if you want to compress
+ * something such that another application can read it.
+ */
+class LZ4FrameCompressionContext final {
+ public:
+  MFBT_API LZ4FrameCompressionContext(int aCompressionLevel, size_t aMaxSrcSize,
+                                      bool aChecksum, bool aStableSrc = false);
+
+  MFBT_API ~LZ4FrameCompressionContext();
+
+  size_t GetRequiredWriteBufferLength() { return mWriteBufLen; }
+
+  /**
+   * Begin streaming frame-based compression.
+   *
+   * @return a Result with a Span containing the frame header, or an lz4 error
+   * code (size_t).
+   */
+  MFBT_API Result<Span<const char>, size_t> BeginCompressing(
+      Span<char> aWriteBuffer);
+
+  /**
+   * Continue streaming frame-based compression with the provided input.
+   *
+   * @param aInput input buffer to be compressed.
+   * @return a Result with a Span containing compressed output, or an lz4 error
+   * code (size_t).
+   */
+  MFBT_API Result<Span<const char>, size_t> ContinueCompressing(
+      Span<const char> aInput);
+
+  /**
+   * Finalize streaming frame-based compression with the provided input.
+   *
+   * @return a Result with a Span containing compressed output and the frame
+   * footer, or an lz4 error code (size_t).
+   */
+  MFBT_API Result<Span<const char>, size_t> EndCompressing();
+
+ private:
+  LZ4F_cctx_s* mContext;
+  int mCompressionLevel;
+  bool mGenerateChecksum;
+  bool mStableSrc;
+  size_t mMaxSrcSize;
+  size_t mWriteBufLen;
+  Span<char> mWriteBuffer;
+};
+
+struct LZ4FrameDecompressionResult {
+  size_t mSizeRead;
+  size_t mSizeWritten;
+  bool mFinished;
+};
+
+/**
+ * Context for LZ4 Frame-based streaming decompression. Use this if you
+ * want to decompress something compressed by LZ4FrameCompressionContext
+ * or by another application.
+ */
+class LZ4FrameDecompressionContext final {
+ public:
+  explicit MFBT_API LZ4FrameDecompressionContext(bool aStableDest = false);
+  MFBT_API ~LZ4FrameDecompressionContext();
+
+  /**
+   * Decompress a buffer/part of a buffer compressed with
+   * LZ4FrameCompressionContext or another application.
+   *
+   * @param aOutput output buffer to be write results into.
+   * @param aInput input buffer to be decompressed.
+   * @return a Result with information on bytes read/written and whether we
+   * completely decompressed the input into the output, or an lz4 error code
+   * (size_t).
+   */
+  MFBT_API Result<LZ4FrameDecompressionResult, size_t> Decompress(
+      Span<char> aOutput, Span<const char> aInput);
+
+ private:
+  LZ4F_dctx_s* mContext;
+  bool mStableDest;
+};
+
+} /* namespace Compression */
+} /* namespace mozilla */
+
+#endif /* mozilla_Compression_h_ */