Initial commit - WPinternals 2.6

DiscUtils/Ntfs/DataRun.cs

@@ -0,0 +1,173 @@
+//
+// Copyright (c) 2008-2011, Kenneth Bell
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+//
+
+namespace DiscUtils.Ntfs
+{
+    using System.Globalization;
+    using System.IO;
+
+    internal class DataRun
+    {
+        private long _runLength;
+        private long _runOffset;
+        private bool _isSparse;
+
+        public DataRun()
+        {
+        }
+
+        public DataRun(long offset, long length, bool isSparse)
+        {
+            _runOffset = offset;
+            _runLength = length;
+            _isSparse = isSparse;
+        }
+
+        public long RunLength
+        {
+            get { return _runLength; }
+            set { _runLength = value; }
+        }
+
+        public long RunOffset
+        {
+            get { return _runOffset; }
+            set { _runOffset = value; }
+        }
+
+        public bool IsSparse
+        {
+            get { return _isSparse; }
+        }
+
+        internal int Size
+        {
+            get
+            {
+                int runLengthSize = VarLongSize(_runLength);
+                int runOffsetSize = VarLongSize(_runOffset);
+                return 1 + runLengthSize + runOffsetSize;
+            }
+        }
+
+        public int Read(byte[] buffer, int offset)
+        {
+            int runOffsetSize = (buffer[offset] >> 4) & 0x0F;
+            int runLengthSize = buffer[offset] & 0x0F;
+
+            _runLength = ReadVarLong(buffer, offset + 1, runLengthSize);
+            _runOffset = ReadVarLong(buffer, offset + 1 + runLengthSize, runOffsetSize);
+            _isSparse = runOffsetSize == 0;
+
+            return 1 + runLengthSize + runOffsetSize;
+        }
+
+        public override string ToString()
+        {
+            return string.Format(CultureInfo.InvariantCulture, "{0:+##;-##;0}[+{1}]", _runOffset, _runLength);
+        }
+
+        internal int Write(byte[] buffer, int offset)
+        {
+            int runLengthSize = WriteVarLong(buffer, offset + 1, _runLength);
+            int runOffsetSize = _isSparse ? 0 : WriteVarLong(buffer, offset + 1 + runLengthSize, _runOffset);
+
+            buffer[offset] = (byte)((runLengthSize & 0x0F) | ((runOffsetSize << 4) & 0xF0));
+
+            return 1 + runLengthSize + runOffsetSize;
+        }
+
+        private static long ReadVarLong(byte[] buffer, int offset, int size)
+        {
+            ulong val = 0;
+            bool signExtend = false;
+
+            for (int i = 0; i < size; ++i)
+            {
+                byte b = buffer[offset + i];
+                val = val | (((ulong)b) << (i * 8));
+                signExtend = (b & 0x80) != 0;
+            }
+
+            if (signExtend)
+            {
+                for (int i = size; i < 8; ++i)
+                {
+                    val = val | (((ulong)0xFF) << (i * 8));
+                }
+            }
+
+            return (long)val;
+        }
+
+        private static int WriteVarLong(byte[] buffer, int offset, long val)
+        {
+            bool isPositive = val >= 0;
+
+            int pos = 0;
+            do
+            {
+                buffer[offset + pos] = (byte)(val & 0xFF);
+                val >>= 8;
+                pos++;
+            }
+            while (val != 0 && val != -1);
+
+            // Avoid appearing to have a negative number that is actually positive,
+            // record an extra empty byte if needed.
+            if (isPositive && (buffer[offset + pos - 1] & 0x80) != 0)
+            {
+                buffer[offset + pos] = 0;
+                pos++;
+            }
+            else if (!isPositive && (buffer[offset + pos - 1] & 0x80) != 0x80)
+            {
+                buffer[offset + pos] = 0xFF;
+                pos++;
+            }
+
+            return pos;
+        }
+
+        private static int VarLongSize(long val)
+        {
+            bool isPositive = val >= 0;
+            bool lastByteHighBitSet = false;
+
+            int len = 0;
+            do
+            {
+                lastByteHighBitSet = (val & 0x80) != 0;
+                val >>= 8;
+                len++;
+            }
+            while (val != 0 && val != -1);
+
+            if ((isPositive && lastByteHighBitSet) || (!isPositive && !lastByteHighBitSet))
+            {
+                len++;
+            }
+
+            return len;
+        }
+    }
+}