Extractor.java

// Copyright (c) 2003-2008 by Leif Frenzel - see http://leiffrenzel.de
// This code is made available under the terms of the Eclipse Public License,
// version 1.0 (EPL). See http://www.eclipse.org/legal/epl-v10.html
package net.sf.eclipsefp.haskell.ui.internal.wizards;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.GZIPInputStream;
import net.sf.eclipsefp.haskell.core.util.ResourceUtil;
import net.sf.eclipsefp.haskell.ui.HaskellUIPlugin;
import org.apache.tools.tar.TarEntry;
import org.apache.tools.tar.TarInputStream;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.core.runtime.Path;
import org.eclipse.core.runtime.Status;

/** <p>extract contents of a tar.gz archive to a workspace project.</p>
  *
  * @author Leif Frenzel
  */
class Extractor {

  private static final int BUFFER = 2048;

  static void extract( final File source,
                       final IProject dest ) throws CoreException {
    try {
      extract( new FileInputStream( source ), dest );
    } catch( final IOException ioex ) {
      String pluginId = HaskellUIPlugin.getPluginId();
      String msg = ioex.getMessage() == null ? "No message" : ioex.getMessage();
      IStatus status = new Status( IStatus.ERROR, pluginId, 0, msg, ioex );
      throw new CoreException( status );
    }
  }


  // helping functions
  ////////////////////

  private static void extract( final InputStream stream,
                               final IProject dest )
                                             throws IOException, CoreException {
    try (TarInputStream tis = new TarInputStream( new GZIPInputStream( stream ) )) {
      TarEntry entry = tis.getNextEntry();
      while( entry != null ) {
        if( !entry.isDirectory() ) {
          IPath entryPath = new Path( entry.getName() );
          if( entryPath.segmentCount() > 0 ) {
            // strip the first segment, it's the package name
            entryPath = entryPath.removeFirstSegments( 1 );
          }
          write( entryPath, dest, readPartially( tis ) );
        }
        entry = tis.getNextEntry();
      }
    }
  }

  private static void write( final IPath path,
                             final IProject project,
                             final InputStream is ) throws CoreException {
    if( path.segmentCount() > 1 ) {
      ResourceUtil.mkdirs( path.removeLastSegments( 1 ), project );
    }
    IFile file = project.getFile( path );
    if( file.exists() ) {
      file.setContents( is, true, false, new NullProgressMonitor() );
    } else {
      file.create( is, true, new NullProgressMonitor() );
    }
  }

  public static InputStream readPartially( final InputStream is )
                                                            throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    byte[] data = new byte[ BUFFER ];
    int currentByte = is.read( data, 0, BUFFER );
    while( currentByte != -1 ) {
      baos.write( data, 0, currentByte );
      currentByte = is.read( data, 0, BUFFER );
    }
    return new ByteArrayInputStream( baos.toByteArray() );
  }
}