svn commit: r1487402 - /manifoldcf/trunk/framework/core/src/main/java/org/apache/manifoldcf/core/common/DeflateInputStream.java

[kw...@apache.org]

Author: kwright
Date: Wed May 29 08:35:28 2013
New Revision: 1487402

URL: http://svn.apache.org/r1487402
Log:
Add DeflateInputStream, to support compression content types in some connectors.

Added:
    manifoldcf/trunk/framework/core/src/main/java/org/apache/manifoldcf/core/common/DeflateInputStream.java   (with props)

Added: manifoldcf/trunk/framework/core/src/main/java/org/apache/manifoldcf/core/common/DeflateInputStream.java
URL: http://svn.apache.org/viewvc/manifoldcf/trunk/framework/core/src/main/java/org/apache/manifoldcf/core/common/DeflateInputStream.java?rev=1487402&view=auto
==============================================================================
--- manifoldcf/trunk/framework/core/src/main/java/org/apache/manifoldcf/core/common/DeflateInputStream.java (added)
+++ manifoldcf/trunk/framework/core/src/main/java/org/apache/manifoldcf/core/common/DeflateInputStream.java Wed May 29 08:35:28 2013
@@ -0,0 +1,222 @@
+/* $Id$ */
+
+/**
+* Licensed to the Apache Software Foundation (ASF) under one or more
+* contributor license agreements. See the NOTICE file distributed with
+* this work for additional information regarding copyright ownership.
+* The ASF licenses this file to You under the Apache License, Version 2.0
+* (the "License"); you may not use this file except in compliance with
+* the License. You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+package org.apache.manifoldcf.core.common;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.PushbackInputStream;
+import java.util.zip.DataFormatException;
+import java.util.zip.Inflater;
+import java.util.zip.InflaterInputStream;
+
+/** Deflate input stream.  This class takes logic from HttpComponents HttpClient 4.2.x that
+* really should have been exposed as an independent input stream wrapper, and does it the right
+* way.  I will also open an HttpClient ticket so that this code can be pushed upstream eventually.
+*/
+public class DeflateInputStream extends InputStream
+{
+  private InputStream sourceStream;
+
+  public DeflateInputStream(final InputStream wrapped)
+    throws IOException
+  {
+    /*
+      * A zlib stream will have a header.
+      *
+      * CMF | FLG [| DICTID ] | ...compressed data | ADLER32 |
+      *
+      * * CMF is one byte.
+      *
+      * * FLG is one byte.
+      *
+      * * DICTID is four bytes, and only present if FLG.FDICT is set.
+      *
+      * Sniff the content. Does it look like a zlib stream, with a CMF, etc? c.f. RFC1950,
+      * section 2.2. http://tools.ietf.org/html/rfc1950#page-4
+      *
+      * We need to see if it looks like a proper zlib stream, or whether it is just a deflate
+      * stream. RFC2616 calls zlib streams deflate. Confusing, isn't it? That's why some servers
+      * implement deflate Content-Encoding using deflate streams, rather than zlib streams.
+      *
+      * We could start looking at the bytes, but to be honest, someone else has already read
+      * the RFCs and implemented that for us. So we'll just use the JDK libraries and exception
+      * handling to do this. If that proves slow, then we could potentially change this to check
+      * the first byte - does it look like a CMF? What about the second byte - does it look like
+      * a FLG, etc.
+      */
+
+    /* We read a small buffer to sniff the content. */
+    final byte[] peeked = new byte[6];
+
+    final PushbackInputStream pushback = new PushbackInputStream(wrapped, peeked.length);
+
+    final int headerLength = pushback.read(peeked);
+
+    if (headerLength == -1) {
+      throw new IOException("Unable to read the response");
+    }
+
+    /* We try to read the first uncompressed byte. */
+    final byte[] dummy = new byte[1];
+
+    final Inflater inf = new Inflater();
+
+    try {
+      int n;
+      while ((n = inf.inflate(dummy)) == 0) {
+        if (inf.finished()) {
+
+          /* Not expecting this, so fail loudly. */
+          throw new IOException("Unable to read the response");
+        }
+
+        if (inf.needsDictionary()) {
+
+          /* Need dictionary - then it must be zlib stream with DICTID part? */
+          break;
+        }
+
+        if (inf.needsInput()) {
+          inf.setInput(peeked);
+        }
+      }
+
+      if (n == -1) {
+        throw new IOException("Unable to read the response");
+      }
+
+      /*
+        * We read something without a problem, so it's a valid zlib stream. Just need to reset
+        * and return an unused InputStream now.
+        */
+      pushback.unread(peeked, 0, headerLength);
+      sourceStream = new DeflateStream(pushback, new Inflater());
+    } catch (final DataFormatException e) {
+
+      /* Presume that it's an RFC1951 deflate stream rather than RFC1950 zlib stream and try
+        * again. */
+      pushback.unread(peeked, 0, headerLength);
+      sourceStream = new DeflateStream(pushback, new Inflater(true));
+    } finally {
+      inf.end();
+    }
+
+  }
+
+  /** Read a byte.
+  */
+  @Override
+  public int read()
+    throws IOException
+  {
+    return sourceStream.read();
+  }
+    
+  /** Read lots of bytes.
+  */
+  @Override
+  public int read(byte[] b)
+    throws IOException
+  {
+    return sourceStream.read(b);
+  }
+
+  /** Read lots of specific bytes.
+  */
+  @Override
+  public int read(byte[] b, int off, int len)
+    throws IOException
+  {
+    return sourceStream.read(b,off,len);
+  }
+  
+  /** Skip
+  */
+  @Override
+  public long skip(long n)
+    throws IOException
+  {
+    return sourceStream.skip(n);
+  }
+
+  /** Get available.
+  */
+  @Override
+  public int available()
+    throws IOException
+  {
+    return sourceStream.available();
+  }
+
+  /** Mark.
+  */
+  @Override
+  public void mark(int readLimit)
+  {
+    sourceStream.mark(readLimit);
+  }
+
+  /** Reset.
+  */
+  @Override
+  public void reset()
+    throws IOException
+  {
+    sourceStream.reset();
+  }
+
+  /** Check if mark is supported.
+  */
+  @Override
+  public boolean markSupported()
+  {
+    return sourceStream.markSupported();
+  }
+
+  /** Close.
+  */
+  @Override
+  public void close()
+    throws IOException
+  {
+    sourceStream.close();
+  }
+
+  static class DeflateStream extends InflaterInputStream {
+
+    private boolean closed = false;
+
+    public DeflateStream(final InputStream in, final Inflater inflater) {
+      super(in, inflater);
+    }
+
+    @Override
+    public void close() throws IOException {
+      if (closed) {
+        return;
+      }
+      closed = true;
+      inf.end();
+      super.close();
+    }
+
+  }
+
+}
+

Propchange: manifoldcf/trunk/framework/core/src/main/java/org/apache/manifoldcf/core/common/DeflateInputStream.java
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