* Adding ChecksumFile component to aide in common checksum creation and validation routines.

* Adding .getFilenameExtension() to digesters (by popular demand)

Author: joakime

src/main/java/org/codehaus/plexus/digest/ChecksumFile.java

@@ -0,0 +1,128 @@
+package org.codehaus.plexus.digest;
+
+/*
+ * Copyright 2001-2007 The Codehaus.
+ *
+ * Licensed 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.
+ */
+
+import org.codehaus.plexus.util.FileUtils;
+import org.codehaus.plexus.util.StringUtils;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+/**
+ * ChecksumFile 
+ *
+ * @author <a href="mailto:[email protected]">Joakim Erdfelt</a>
+ * @version $Id$
+ * 
+ * @plexus.component role="org.codehaus.plexus.digest.ChecksumFile"
+ */
+public class ChecksumFile
+{
+    /**
+     * @plexus.requirement role-hint="sha1"
+     */
+    private Digester digestSha1;
+
+    /**
+     * @plexus.requirement role-hint="md5";
+     */
+    private Digester digestMd5;
+
+    /**
+     * <p>
+     * Given a checksum file, check to see if the file it represents is valid according to the checksum.
+     * </p>
+     * 
+     * <dl>
+     *   <lh>Terminology:</lh>
+     *   <dt>Checksum File</dt>
+     *   <dd>The file that contains the previously calculated checksum value for the reference file.
+     *       This is a text file with the extension ".sha1" or ".md5", and contains a single entry
+     *       consisting of an optional reference filename, and a checksum string.
+     *   </dd>
+     *   <dt>Reference File</dt>
+     *   <dd>The file that is being referenced in the checksum file.</dd>
+     * </dl>
+     * 
+     * <p>
+     * NOTE: Only supports single file checksums of type MD5 or SHA1.
+     * </p>
+     * 
+     * @param checksumFile the checksum file (must end in ".sha1" or ".md5")
+     * @return true if the checksum is valid for the file it represents.
+     * @throws DigesterException if there is a digester problem during the check of the reference file. 
+     * @throws FileNotFoundException if the checksumFile itself or the file it refers to is not found.
+     * @throws IOException if the reading of the checksumFile or the file it refers to fails.
+     */
+    public boolean isValidChecksum( File checksumFile ) throws DigesterException, FileNotFoundException, IOException
+    {
+        if ( !checksumFile.exists() )
+        {
+            throw new FileNotFoundException( "Unable to find checksum file " + checksumFile.getAbsolutePath() );
+        }
+
+        if ( !checksumFile.isFile() )
+        {
+            throw new IOException( "Unable to load checksum from non-file " + checksumFile.getAbsolutePath() );
+        }
+
+        String path = checksumFile.getAbsolutePath();
+        Digester digester = null;
+
+        if ( path.endsWith( digestMd5.getFilenameExtension() ) )
+        {
+            digester = digestMd5;
+        }
+        else if ( path.endsWith( digestSha1.getFilenameExtension() ) )
+        {
+            digester = digestSha1;
+        }
+        // TODO: Add more digester implementations here.
+
+        if ( digester == null )
+        {
+            throw new DigesterException( "Unable to determine digester type from filename " + path );
+        }
+
+        File referenceFile = new File( path.substring( 0, path.length() - digester.getFilenameExtension().length() ) );
+
+        String rawChecksum = FileUtils.fileRead( checksumFile );
+        String expectedChecksum = DigestUtils.cleanChecksum( rawChecksum, digester, referenceFile.getName() );
+
+        String actualChecksum = digester.calc( referenceFile );
+
+        return StringUtils.equalsIgnoreCase( expectedChecksum, actualChecksum );
+    }
+
+    /**
+     * Creates a checksum file of the provided referenceFile.
+     * 
+     * @param referenceFile the file to checksum.
+     * @param digester the digester to use.
+     * @return the checksum File that was created.
+     * @throws DigesterException if there was a problem calculating the checksum of the referenceFile. 
+     * @throws IOException if there was a problem either reading the referenceFile, or writing the checksum file.
+     */
+    public File createChecksum( File referenceFile, Digester digester ) throws DigesterException, IOException
+    {
+        File checksumFile = new File( referenceFile.getAbsolutePath() + digester.getFilenameExtension() );
+        String checksum = digester.calc( checksumFile );
+        FileUtils.fileWrite( checksumFile.getAbsolutePath(), checksum + "  " + referenceFile.getName() );
+        return checksumFile;
+    }
+}

src/main/java/org/codehaus/plexus/digest/DigestUtils.java

@@ -30,6 +30,20 @@ private DigestUtils()
     {
         // don't create this class
     }
+    
+    /**
+     * Take a raw checksum string and verify that it matches the expectedFilename and digester, then
+     * return the trimmed checksum string.
+     * 
+     * @param rawChecksum the raw checksum string that may include the filename.
+     * @param digester the expected digester for this checksum string.
+     * @return the trimmed checksum string (no filename portion)
+     * @throws DigesterException if there was a problem verifying the checksum string.
+     */
+    public static String cleanChecksum( String rawChecksum, Digester digester, String expectedFilename ) throws DigesterException
+    {
+        return cleanChecksum( rawChecksum, digester.getAlgorithm(), expectedFilename );
+    }
 
     public static String cleanChecksum( String checksum, String algorithm, String path )
         throws DigesterException

src/main/java/org/codehaus/plexus/digest/Digester.java

@@ -33,6 +33,13 @@ public interface Digester
      * @return the algorithm
      */
     String getAlgorithm();
+    
+    /**
+     * The filename extension for this digester.
+     * 
+     * @return the filename extension.
+     */
+    String getFilenameExtension();
 
     /**
      * Calculate a checksum for a file.

src/main/java/org/codehaus/plexus/digest/Md5Digester.java

@@ -24,6 +24,11 @@
 public class Md5Digester
     extends AbstractDigester
 {
+    public String getFilenameExtension()
+    {
+        return ".md5";
+    }
+    
     public Md5Digester()
     {
         super( new StreamingMd5Digester() );

src/main/java/org/codehaus/plexus/digest/Sha1Digester.java

@@ -24,6 +24,11 @@
 public class Sha1Digester
     extends AbstractDigester
 {
+    public String getFilenameExtension()
+    {
+        return ".sha1";
+    }
+    
     public Sha1Digester()
     {
         super( new StreamingSha1Digester() );

src/test/examples/redback-authz-open.jar

@@ -0,0 +1 @@
+f42047fe2e177ac04d0df7aa44d408be  redback-authz-open.jar

src/test/examples/redback-authz-open.jar.md5

@@ -0,0 +1 @@
+2bb14b388973351b0a4dfe11d171965f59cc61a1  redback-authz-open.jar

src/test/examples/redback-authz-open.jar.sha1

@@ -0,0 +1,49 @@
+package org.codehaus.plexus.digest;
+
+/*
+ * Copyright 2001-2007 The Codehaus.
+ *
+ * Licensed 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.
+ */
+
+import org.codehaus.plexus.PlexusTestCase;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+/**
+ * ChecksumFileTest 
+ *
+ * @author <a href="mailto:[email protected]">Joakim Erdfelt</a>
+ * @version $Id$
+ */
+public class ChecksumFileTest extends PlexusTestCase
+{
+    private ChecksumFile checksum;
+
+    protected void setUp() throws Exception
+    {
+        super.setUp();
+
+        checksum = (ChecksumFile) lookup( ChecksumFile.class.getName() );
+    }
+
+    public void testChecksum() throws FileNotFoundException, DigesterException, IOException
+    {
+        File exampleDir = new File( getBasedir(), "src/test/examples" );
+
+        assertTrue( checksum.isValidChecksum( new File( exampleDir, "redback-authz-open.jar.md5" ) ) );
+        assertTrue( checksum.isValidChecksum( new File( exampleDir, "redback-authz-open.jar.sha1" ) ) );
+    }
+}