1 files changed, 85 insertions, 0 deletions
diff --git a/xpcom/io/SnappyFrameUtils.h b/xpcom/io/SnappyFrameUtils.h
new file mode 100644
index 0000000000..41479b14d6
--- /dev/null
+++ b/xpcom/io/SnappyFrameUtils.h
@@ -0,0 +1,85 @@
+/* -*- 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 "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() { }
+  virtual ~SnappyFrameUtils() { }
+};
+
+} // namespace detail
+} // namespace mozilla
+
+#endif // mozilla_SnappyFrameUtils_h__