OutputStream that computes hash while writing.

Author: tlipkis

src/org/lockss/util/HashedOutputStream.java

@@ -0,0 +1,73 @@
+/*
+ * $Id$
+ */
+
+/*
+
+Copyright (c) 2016 Board of Trustees of Leland Stanford Jr. University,
+all rights reserved.
+
+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
+STANFORD UNIVERSITY 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.
+
+Except as contained in this notice, the name of Stanford University shall not
+be used in advertising or otherwise to promote the sale, use or other dealings
+in this Software without prior written authorization from Stanford University.
+
+*/
+
+package org.lockss.util;
+import java.io.*;
+import java.security.MessageDigest;
+
+/**
+ * An OutputStream wrapper that feeds all the bytes written to a MessageDigest.
+ */
+public class HashedOutputStream extends FilterOutputStream {
+  private MessageDigest md;
+
+  /**
+   * @param os the underlying OutputStream.
+   * @param md the MessageDigest to which to feed the bytes written.
+   */
+  public HashedOutputStream(OutputStream os, MessageDigest md) {
+    super(os);
+    if (os == null) {
+      throw new IllegalArgumentException("null OutputStream");
+    }
+    if (md == null) {
+      throw new IllegalArgumentException("null MessageDigest");
+    }
+    this.md = md;
+  }
+
+  public void write(int b) throws IOException {
+    byte[] buf = new byte[1];
+    buf[0] = (byte)b;
+    write(buf);
+  }
+
+  public void write(byte[] buf) throws IOException {
+    write(buf, 0, buf.length);
+  }
+
+  public void write(byte[] buf, int off, int len) throws IOException {
+    out.write(buf, off, len);
+    md.update(buf, off, len);
+  }
+
+}

test/src/org/lockss/util/TestHashedOutputStream.java

@@ -0,0 +1,75 @@
+/*
+ * $Id$
+ */
+
+/*
+
+Copyright (c) 2000-2016 Board of Trustees of Leland Stanford Jr. University,
+all rights reserved.
+
+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
+STANFORD UNIVERSITY 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.
+
+Except as contained in this notice, the name of Stanford University shall not
+be used in advertising or otherwise to promote the sale, use or other dealings
+in this Software without prior written authorization from Stanford University.
+
+*/
+
+package org.lockss.util;
+import java.io.*;
+import java.security.*;
+import org.lockss.test.*;
+
+public class TestHashedOutputStream extends LockssTestCase {
+
+  private MockMessageDigest makeMessageDigest() {
+    return new MockMessageDigest();
+  }
+
+  public void testNullArgumentsToConstructor() {
+    MessageDigest md = makeMessageDigest();
+    OutputStream out = new ByteArrayOutputStream();
+    try {
+      new HashedOutputStream(null, md);
+      fail("Calling the constructor with null OutputStream should throw");
+    } catch (IllegalArgumentException e) {
+    }
+    try {
+      new HashedOutputStream(out, null);
+      fail("Calling the constructor with null MessageDigest should throw");
+    } catch (IllegalArgumentException e) {
+    }
+  }
+
+  byte[] getBytes(String s) throws UnsupportedEncodingException {
+    return s.getBytes(Constants.DEFAULT_ENCODING);
+  }
+
+  public void testWrite() throws IOException {
+    ByteArrayOutputStream out = new ByteArrayOutputStream();
+    MockMessageDigest md = makeMessageDigest();
+    HashedOutputStream hos = new HashedOutputStream(out, md);
+    hos.write('a');
+    assertEquals(getBytes("a"), md.getUpdatedBytes());
+    hos.write(getBytes("bcdefghijk"));
+    hos.write(getBytes("1234567890"), 3, 4);
+    assertEquals(getBytes("bcdefghijk4567"), md.getUpdatedBytes());
+    assertEquals("abcdefghijk4567", out.toString());
+  }
+
+}