patch-sharpziplib-ca-63358-TarInputStream.diff

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#     following disclaimer.
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--- src/Tar/TarInputStream.cs	2011-06-17 23:09:32.000000000 +0100
+++ ../SharpZipLib-0.85.4.403/src/Tar/TarInputStream.cs	2011-08-01 22:47:08.000000000 +0100
@@ -215,81 +215,22 @@
 		public override int Read(byte[] buffer, int offset, int count)
 		{
 			if ( buffer == null ) 
-			{
 				throw new ArgumentNullException("buffer");
-			}
 
-			int totalRead = 0;
-			
-			if (this.entryOffset >= this.entrySize) 
-			{
-				return 0;
-			}
-			
-			long numToRead = count;
-			
-			if ((numToRead + this.entryOffset) > this.entrySize) 
-			{
-				numToRead = this.entrySize - this.entryOffset;
-			}
-			
-			if (this.readBuffer != null) 
-			{
-				int sz = (numToRead > this.readBuffer.Length) ? this.readBuffer.Length : (int)numToRead;
-				
-				Array.Copy(this.readBuffer, 0, buffer, offset, sz);
-				
-				if (sz >= this.readBuffer.Length) 
-				{
-					this.readBuffer = null;
-				} 
-				else 
-				{
-					int newLen = this.readBuffer.Length - sz;
-					byte[] newBuf = new byte[newLen];
-					Array.Copy(this.readBuffer, sz, newBuf, 0, newLen);
-					this.readBuffer = newBuf;
-				}
-				
-				totalRead += sz;
-				numToRead -= sz;
-				offset += sz;
-			}
-			
-			while (numToRead > 0) 
-			{
-				byte[] rec = this.buffer.ReadBlock();
-				if (rec == null) 
-				{
-					// Unexpected EOF!
-					throw new TarException("unexpected EOF with " + numToRead + " bytes unread");
-				}
-				
-				int sz     = (int)numToRead;
-				int recLen = rec.Length;
-				
-				if (recLen > sz) 
-				{
-					Array.Copy(rec, 0, buffer, offset, sz);
-					this.readBuffer = new byte[recLen - sz];
-					Array.Copy(rec, sz, this.readBuffer, 0, recLen - sz);
-				} 
-				else 
-				{
-					sz = recLen;
-					Array.Copy(rec, 0, buffer, offset, recLen);
-				}
-				
-				totalRead += sz;
-				numToRead -= sz;
-				offset += sz;
-			}
-			
-			this.entryOffset += totalRead;
-			
-			return totalRead;
+            if ((this.entryOffset + count) > this.entrySize)
+                count = (int)(this.entrySize - this.entryOffset);
+
+            if (count <= 0)
+                return 0;
+
+            int bytesRead = inputStream.Read(buffer, offset, count);
+
+            this.entryOffset += bytesRead;
+
+            return bytesRead;
 		}
-		
+        
+
 		/// <summary>
 		/// Closes this stream. Calls the TarBuffer's close() method.
 		/// The underlying stream is closed by the TarBuffer.
@@ -345,36 +286,8 @@
 				return this.entrySize - this.entryOffset;
 			}
 		}
-		
-		/// <summary>
-		/// Skip bytes in the input buffer. This skips bytes in the
-		/// current entry's data, not the entire archive, and will
-		/// stop at the end of the current entry's data if the number
-		/// to skip extends beyond that point.
-		/// </summary>
-		/// <param name="skipCount">
-		/// The number of bytes to skip.
-		/// </param>
-		public void Skip(long skipCount)
-		{
-			// TODO: REVIEW efficiency of TarInputStream.Skip
-			// This is horribly inefficient, but it ensures that we
-			// properly skip over bytes via the TarBuffer...
-			//
-			byte[] skipBuf = new byte[8 * 1024];
-			
-			for (long num = skipCount; num > 0;) {
-				int toRead = num > skipBuf.Length ? skipBuf.Length : (int)num;
-				int numRead = this.Read(skipBuf, 0, toRead);
-				
-				if (numRead == -1) {
-					break;
-				}
-				
-				num -= numRead;
-			}
-		}
-		
+
+
 		/// <summary>
 		/// Return a value of true if marking is supported; false otherwise.
 		/// </summary>
@@ -384,8 +297,17 @@
 				return false;
 			}
 		}
-		
-		/// <summary>
+
+
+        /// <summary>
+        /// Get the position within the current entry.
+        /// </summary>
+        public long EntryPosition 
+        { 
+            get { return this.entryOffset; }
+        }
+
+        /// <summary>
 		/// Since we do not support marking just yet, we do nothing.
 		/// </summary>
 		/// <param name ="markLimit">
@@ -401,6 +323,29 @@
 		public void Reset()
 		{
 		}
+
+        /// <summary>
+        /// Read a tar entry header.
+        /// </summary>
+        protected byte[] ReadHeader()
+        {
+            byte[] headerBuffer = new byte[TarBuffer.BlockSize];
+
+            Array.Clear(headerBuffer, 0, headerBuffer.Length);
+
+            int bytesRead = inputStream.Read(headerBuffer, 0, headerBuffer.Length);
+
+            // Account for an improper archive that does not include terminating records 
+            // such as those from Virtual Box.
+            // Fabricate a terminating record.
+            if (bytesRead == 0)
+                return headerBuffer;
+
+            if (bytesRead != headerBuffer.Length)
+                throw new TarException("Header is incomplete.");
+
+            return headerBuffer;
+        }
 		
 		/// <summary>
 		/// Get the next entry in this tar archive. This will skip
@@ -425,7 +370,7 @@
 				SkipToNextEntry();
 			}
 			
-			byte[] headerBuf = this.buffer.ReadBlock();
+			byte[] headerBuf = ReadHeader();
 			
 			if (headerBuf == null) {
 				this.hasHitEOF = true;
@@ -467,25 +412,25 @@
 						}
 						
 						SkipToNextEntry();
-						headerBuf = this.buffer.ReadBlock();
+                        headerBuf = ReadHeader();
 					} else if (header.TypeFlag == TarHeader.LF_GHDR) {  // POSIX global extended header 
 						// Ignore things we dont understand completely for now
 						SkipToNextEntry();
-						headerBuf = this.buffer.ReadBlock();
+                        headerBuf = ReadHeader();
 					} else if (header.TypeFlag == TarHeader.LF_XHDR) {  // POSIX extended header
 						// Ignore things we dont understand completely for now
 						SkipToNextEntry();
-						headerBuf = this.buffer.ReadBlock();
+                        headerBuf = ReadHeader();
 					} else if (header.TypeFlag == TarHeader.LF_GNU_VOLHDR) {
 						// TODO: could show volume name when verbose
 						SkipToNextEntry();
-						headerBuf = this.buffer.ReadBlock();
+                        headerBuf = ReadHeader();
 					} else if (header.TypeFlag != TarHeader.LF_NORMAL && 
 							   header.TypeFlag != TarHeader.LF_OLDNORM &&
 							   header.TypeFlag != TarHeader.LF_DIR) {
 						// Ignore things we dont understand completely for now
 						SkipToNextEntry();
-						headerBuf = this.buffer.ReadBlock();
+                        headerBuf = ReadHeader();
 					}
 					
 					if (this.entryFactory == null) {
@@ -538,15 +483,39 @@
 
 		void SkipToNextEntry()
 		{
-			long numToSkip = this.entrySize - this.entryOffset;
-			
-			if (numToSkip > 0) 
-			{
-				this.Skip(numToSkip);
-			}
-			
-			this.readBuffer = null;
-		}
+            // Skip the rest of the content.
+            long bytesToSkip = this.entrySize - this.entryOffset;
+
+            // Account for the pad out to a block.
+            long bytesInLastBlock = this.entrySize % TarBuffer.BlockSize;
+
+            if (bytesInLastBlock > 0)
+            {
+                bytesToSkip += TarBuffer.BlockSize - bytesInLastBlock;
+            }
+
+            // Skip by seeking if at all possible.
+            if (inputStream.CanSeek)
+            {
+                inputStream.Seek(bytesToSkip, SeekOrigin.Current);
+                return;
+            }
+
+            // Last resort is to skip by reading.
+            byte[] skipBuf = new byte[8 * 1024];
+
+            while (bytesToSkip > 0)
+            {
+                int bytesToRead = (bytesToSkip > skipBuf.Length) ? skipBuf.Length : (int)bytesToSkip;
+
+                int bytesRead = inputStream.Read(skipBuf, 0, bytesToRead);
+
+                if (bytesRead <= 0)
+                    return;
+
+                bytesToSkip -= bytesRead;
+            }
+        }
 		
 		/// <summary>
 		/// This interface is provided, along with the method <see cref="SetEntryFactory"/>, to allow
@@ -638,11 +607,6 @@
 		/// Number of bytes read for this entry so far
 		/// </summary>
 		protected long entryOffset;
-
-		/// <summary>
-		/// Buffer used with calls to <code>Read()</code>
-		/// </summary>		
-		protected byte[] readBuffer;
 		
 		/// <summary>
 		/// Working buffer