1 files changed, 80 insertions, 0 deletions
diff --git a/xpcom/io/SnappyFrameUtils.h b/xpcom/io/SnappyFrameUtils.h
new file mode 100644
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--- /dev/null
+++ b/xpcom/io/SnappyFrameUtils.h
@@ -0,0 +1,80 @@
+/* -*- 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/. */
+
+#ifndef mozilla_SnappyFrameUtils_h__
+#define mozilla_SnappyFrameUtils_h__
+
+#include <cstddef>
+
+#include "mozilla/Attributes.h"
+#include "nsError.h"
+
+namespace mozilla {
+namespace detail {
+
+//
+// Utility class providing primitives necessary to build streams based
+// on the snappy compressor.  This essentially abstracts the framing format
+// defined in:
+//
+//  other-licences/snappy/src/framing_format.txt
+//
+// NOTE: Currently only the StreamIdentifier and CompressedData chunks are
+//       supported.
+//
+class SnappyFrameUtils {
+ public:
+  enum ChunkType {
+    Unknown,
+    StreamIdentifier,
+    CompressedData,
+    UncompressedData,
+    Padding,
+    Reserved,
+    ChunkTypeCount
+  };
+
+  static const size_t kChunkTypeLength = 1;
+  static const size_t kChunkLengthLength = 3;
+  static const size_t kHeaderLength = kChunkTypeLength + kChunkLengthLength;
+  static const size_t kStreamIdentifierDataLength = 6;
+  static const size_t kCRCLength = 4;
+
+  static nsresult WriteStreamIdentifier(char* aDest, size_t aDestLength,
+                                        size_t* aBytesWrittenOut);
+
+  static nsresult WriteCompressedData(char* aDest, size_t aDestLength,
+                                      const char* aData, size_t aDataLength,
+                                      size_t* aBytesWrittenOut);
+
+  static nsresult ParseHeader(const char* aSource, size_t aSourceLength,
+                              ChunkType* aTypeOut, size_t* aDataLengthOut);
+
+  static nsresult ParseData(char* aDest, size_t aDestLength, ChunkType aType,
+                            const char* aData, size_t aDataLength,
+                            size_t* aBytesWrittenOut, size_t* aBytesReadOut);
+
+  static nsresult ParseStreamIdentifier(char* aDest, size_t aDestLength,
+                                        const char* aData, size_t aDataLength,
+                                        size_t* aBytesWrittenOut,
+                                        size_t* aBytesReadOut);
+
+  static nsresult ParseCompressedData(char* aDest, size_t aDestLength,
+                                      const char* aData, size_t aDataLength,
+                                      size_t* aBytesWrittenOut,
+                                      size_t* aBytesReadOut);
+
+  static size_t MaxCompressedBufferLength(size_t aSourceLength);
+
+ protected:
+  SnappyFrameUtils() = default;
+  virtual ~SnappyFrameUtils() = default;
+};
+
+}  // namespace detail
+}  // namespace mozilla
+
+#endif  // mozilla_SnappyFrameUtils_h__