Merge pull request #69 from pnewman8/master

Skip entry stream on dispose

SharpCompress/Archive/SevenZip/SevenZipArchive.cs

@@ -236,7 +236,7 @@ namespace SharpCompress.Archive.SevenZip
 
             protected override EntryStream GetEntryStream()
             {
-                return new EntryStream(new ReadOnlySubStream(currentStream, currentItem.Size));
+                return CreateEntryStream(new ReadOnlySubStream(currentStream, currentItem.Size));
             }
         }
     }

SharpCompress/Common/EntryStream.cs

@@ -1,16 +1,19 @@
 using System;
 using System.IO;
+using SharpCompress.Reader;
 
 namespace SharpCompress.Common
 {
     public class EntryStream : Stream
     {
+        public IReader Reader { get; private set; }
         private Stream stream;
         private bool completed;
         private bool isDisposed;
 
-        internal EntryStream(Stream stream)
+        internal EntryStream(IReader reader, Stream stream)
         {
+            this.Reader = reader;
             this.stream = stream;
         }
 
@@ -28,10 +31,9 @@ namespace SharpCompress.Common
 
         protected override void Dispose(bool disposing)
         {
-            if (!completed)
+            if (!(completed || Reader.Cancelled))
             {
-                throw new InvalidOperationException(
-                    "EntryStream has not been fully consumed.  Read the entire stream or use SkipEntry.");
+                SkipEntry();
             }
             if (isDisposed)
             {

SharpCompress/Reader/AbstractReader.cs

@@ -67,12 +67,32 @@ namespace SharpCompress.Reader
 
         #endregion
 
+
+        public bool Cancelled { get; private set; }
+
+        /// <summary>
+        /// Indicates that the remaining entries are not required.
+        /// On dispose of an EntryStream, the stream will not skip to the end of the entry.
+        /// An attempt to move to the next entry will throw an exception, as the compressed stream is not positioned at an entry boundary.
+        /// </summary>
+        public void Cancel()
+        {
+          if (!completed)
+          {
+            Cancelled = true;
+          }
+        }
+
         public bool MoveToNextEntry()
         {
             if (completed)
             {
                 return false;
             }
+            if (Cancelled)
+            {
+                throw new InvalidOperationException("Reader has been cancelled.");
+            }
             if (entriesForCurrentReadStream == null)
             {
                 return LoadStreamForReading(RequestInitialStream());
@@ -197,9 +217,17 @@ namespace SharpCompress.Reader
             return stream;
         }
 
+        /// <summary>
+        /// Retains a reference to the entry stream, so we can check whether it completed later.
+        /// </summary>
+        protected EntryStream CreateEntryStream(Stream decompressed)
+        {
+          return new EntryStream(this, decompressed);
+        }
+
         protected virtual EntryStream GetEntryStream()
         {
-            return new EntryStream(Entry.Parts.First().GetCompressedStream());
+          return CreateEntryStream(Entry.Parts.First().GetCompressedStream());
         }
 
         #endregion

SharpCompress/Reader/IReader.cs

@@ -22,6 +22,9 @@ namespace SharpCompress.Reader
         /// <param name="writableStream"></param>
         void WriteEntryTo(Stream writableStream);
 
+        bool Cancelled { get; }
+        void Cancel();
+
         /// <summary>
         /// Moves to the next entry by reading more data from the underlying stream.  This skips if data has not been read.
         /// </summary>

SharpCompress/Reader/Rar/RarReader.cs

@@ -73,7 +73,7 @@ namespace SharpCompress.Reader.Rar
 
         protected override EntryStream GetEntryStream()
         {
-            return new EntryStream(new RarStream(pack, Entry.FileHeader,
+            return CreateEntryStream(new RarStream(pack, Entry.FileHeader,
                                                  new MultiVolumeReadOnlyStream(
                                                      CreateFilePartEnumerableForCurrentEntry().Cast<RarFilePart>(), this)));
         }