HADOOP-10653. Add a new constructor for CryptoInputStream that receives current position of wrapped stream. Contributed by Yi Liu

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/fs-encryption@1599228 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES-fs-encryption.txt

@@ -21,6 +21,9 @@ fs-encryption (Unreleased)
 
     HADOOP-10635. Add a method to CryptoCodec to generate SRNs for IV. (Yi Liu)
 
+    HADOOP-10653. Add a new constructor for CryptoInputStream that 
+    receives current position of wrapped stream. (Yi Liu)
+
   OPTIMIZATIONS
 
   BUG FIXES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/crypto/CryptoInputStream.java

@@ -102,18 +102,22 @@ public class CryptoInputStream extends FilterInputStream implements
   
   public CryptoInputStream(InputStream in, CryptoCodec codec, 
       int bufferSize, byte[] key, byte[] iv) throws IOException {
+    this(in, codec, bufferSize, key, iv, 
+        CryptoStreamUtils.getInputStreamOffset(in));
+  }
+  
+  public CryptoInputStream(InputStream in, CryptoCodec codec,
+      int bufferSize, byte[] key, byte[] iv, long streamOffset) throws IOException {
     super(in);
     this.bufferSize = CryptoStreamUtils.checkBufferSize(codec, bufferSize);
     this.codec = codec;
     this.key = key.clone();
     this.initIV = iv.clone();
     this.iv = iv.clone();
+    this.streamOffset = streamOffset;
     inBuffer = ByteBuffer.allocateDirect(this.bufferSize);
     outBuffer = ByteBuffer.allocateDirect(this.bufferSize);
     decryptor = getDecryptor();
-    if (in instanceof Seekable) {
-      streamOffset = ((Seekable) in).getPos();
-    }
     resetStreamOffset(streamOffset);
   }
   

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/crypto/CryptoStreamUtils.java

@@ -20,10 +20,13 @@ package org.apache.hadoop.crypto;
 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.HADOOP_SECURITY_CRYPTO_BUFFER_SIZE_DEFAULT;
 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.HADOOP_SECURITY_CRYPTO_BUFFER_SIZE_KEY;
 
+import java.io.IOException;
+import java.io.InputStream;
 import java.nio.ByteBuffer;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Seekable;
 
 import com.google.common.base.Preconditions;
 
@@ -52,4 +55,15 @@ public class CryptoStreamUtils {
         "Minimum value of buffer size is " + MIN_BUFFER_SIZE + ".");
     return bufferSize - bufferSize % codec.getAlgorithmBlockSize();
   }
+  
+  /**
+   * If input stream is {@link org.apache.hadoop.fs.Seekable}, return it's
+   * current position, otherwise return 0;
+   */
+  public static long getInputStreamOffset(InputStream in) throws IOException {
+    if (in instanceof Seekable) {
+      return ((Seekable) in).getPos();
+    }
+    return 0;
+  }
 }