apache-poi/src/java/org/apache/poi/hpsf/VariantSupport.java

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   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
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       http://www.apache.org/licenses/LICENSE-2.0

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package org.apache.poi.hpsf;

import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;

import org.apache.poi.util.CodePageUtil;
import org.apache.poi.util.POILogFactory;
import org.apache.poi.util.POILogger;

/**
 * <p>Supports reading and writing of variant data.</p>
 *
 * <p><strong>FIXME (3):</strong> Reading and writing should be made more
 * uniform than it is now. The following items should be resolved:
 *
 * <ul>
 *
 * <li><p>Reading requires a length parameter that is 4 byte greater than the
 * actual data, because the variant type field is included. </p></li>
 *
 * <li><p>Reading reads from a byte array while writing writes to an byte array
 * output stream.</p></li>
 *
 * </ul>
 *
 * @author Rainer Klute <a
 * href="mailto:klute@rainer-klute.de">&lt;klute@rainer-klute.de&gt;</a>
 */
public class VariantSupport extends Variant
{
	private static POILogger logger = POILogFactory.getLogger(VariantSupport.class);
    private static boolean logUnsupportedTypes = false;

    /**
     * <p>Specifies whether warnings about unsupported variant types are to be
     * written to <code>System.err</code> or not.</p>
     *
     * @param logUnsupportedTypes If <code>true</code> warnings will be written,
     * if <code>false</code> they won't.
     */
    public static void setLogUnsupportedTypes(final boolean logUnsupportedTypes)
    {
        VariantSupport.logUnsupportedTypes = logUnsupportedTypes;
    }

    /**
     * <p>Checks whether logging of unsupported variant types warning is turned
     * on or off.</p>
     *
     * @return <code>true</code> if logging is turned on, else
     * <code>false</code>.
     */
    public static boolean isLogUnsupportedTypes()
    {
        return logUnsupportedTypes;
    }



    /**
     * <p>Keeps a list of the variant types an "unsupported" message has already
     * been issued for.</p>
     */
    protected static List<Long> unsupportedMessage;

    /**
     * <p>Writes a warning to <code>System.err</code> that a variant type is
     * unsupported by HPSF. Such a warning is written only once for each variant
     * type. Log messages can be turned on or off by </p>
     *
     * @param ex The exception to log
     */
    protected static void writeUnsupportedTypeMessage
        (final UnsupportedVariantTypeException ex)
    {
        if (isLogUnsupportedTypes())
        {
            if (unsupportedMessage == null)
                unsupportedMessage = new LinkedList<Long>();
            Long vt = Long.valueOf(ex.getVariantType());
            if (!unsupportedMessage.contains(vt))
            {
            	logger.log( POILogger.ERROR, ex.getMessage());
                unsupportedMessage.add(vt);
            }
        }
    }


    /**
     * <p>HPSF is able to read these {@link Variant} types.</p>
     */
    final static public int[] SUPPORTED_TYPES = { Variant.VT_EMPTY,
            Variant.VT_I2, Variant.VT_I4, Variant.VT_I8, Variant.VT_R8,
            Variant.VT_FILETIME, Variant.VT_LPSTR, Variant.VT_LPWSTR,
            Variant.VT_CF, Variant.VT_BOOL };



    /**
     * <p>Checks whether HPSF supports the specified variant type. Unsupported
     * types should be implemented included in the {@link #SUPPORTED_TYPES}
     * array.</p>
     *
     * @see Variant
     * @param variantType the variant type to check
     * @return <code>true</code> if HPFS supports this type, else
     *         <code>false</code>
     */
    public boolean isSupportedType(final int variantType)
    {
        for (int i = 0; i < SUPPORTED_TYPES.length; i++)
            if (variantType == SUPPORTED_TYPES[i])
                return true;
        return false;
    }



    /**
     * <p>Reads a variant type from a byte array.</p>
     *
     * @param src The byte array
     * @param offset The offset in the byte array where the variant starts
     * @param length The length of the variant including the variant type field
     * @param type The variant type to read
     * @param codepage The codepage to use for non-wide strings
     * @return A Java object that corresponds best to the variant field. For
     *         example, a VT_I4 is returned as a {@link Long}, a VT_LPSTR as a
     *         {@link String}.
     * @exception ReadingNotSupportedException if a property is to be written
     *            who's variant type HPSF does not yet support
     * @exception UnsupportedEncodingException if the specified codepage is not
     *            supported.
     * @see Variant
     */
    public static Object read( final byte[] src, final int offset,
            final int length, final long type, final int codepage )
            throws ReadingNotSupportedException, UnsupportedEncodingException
    {
        TypedPropertyValue typedPropertyValue = new TypedPropertyValue(
                (int) type, null );
        int unpadded;
        try
        {
            unpadded = typedPropertyValue.readValue( src, offset );
        }
        catch ( UnsupportedOperationException exc )
        {
            int propLength = Math.min( length, src.length - offset );
            final byte[] v = new byte[propLength];
            System.arraycopy( src, offset, v, 0, propLength );
            throw new ReadingNotSupportedException( type, v );
        }

        switch ( (int) type )
        {
        case Variant.VT_EMPTY:
        case Variant.VT_I4:
        case Variant.VT_I8:
        case Variant.VT_R8:
            /*
             * we have more property types that can be converted into Java
             * objects, but current API need to be preserved, and it returns
             * other types as byte arrays. In future major versions it shall be
             * changed -- sergey
             */
            return typedPropertyValue.getValue();

        case Variant.VT_I2:
        {
            /*
             * also for backward-compatibility with prev. versions of POI
             * --sergey
             */
            return Integer.valueOf( ( (Short) typedPropertyValue.getValue() )
                    .intValue() );
        }
        case Variant.VT_FILETIME:
        {
            Filetime filetime = (Filetime) typedPropertyValue.getValue();
            return Util.filetimeToDate( (int) filetime.getHigh(),
                    (int) filetime.getLow() );
        }
        case Variant.VT_LPSTR:
        {
            CodePageString string = (CodePageString) typedPropertyValue
                    .getValue();
            return string.getJavaValue( codepage );
        }
        case Variant.VT_LPWSTR:
        {
            UnicodeString string = (UnicodeString) typedPropertyValue
                    .getValue();
            return string.toJavaString();
        }
        case Variant.VT_CF:
        {
            // if(l1 < 0) {
            /**
             * YK: reading the ClipboardData packet (VT_CF) is not quite
             * correct. The size of the data is determined by the first four
             * bytes of the packet while the current implementation calculates
             * it in the Section constructor. Test files in Bugzilla 42726 and
             * 45583 clearly show that this approach does not always work. The
             * workaround below attempts to gracefully handle such cases instead
             * of throwing exceptions.
             * 
             * August 20, 2009
             */
            // l1 = LittleEndian.getInt(src, o1); o1 += LittleEndian.INT_SIZE;
            // }
            // final byte[] v = new byte[l1];
            // System.arraycopy(src, o1, v, 0, v.length);
            // value = v;
            // break;
            ClipboardData clipboardData = (ClipboardData) typedPropertyValue
                    .getValue();
            return clipboardData.toByteArray();
        }

        case Variant.VT_BOOL:
        {
            VariantBool bool = (VariantBool) typedPropertyValue.getValue();
            return Boolean.valueOf( bool.getValue() );
        }

        default:
        {
            /*
             * it is not very good, but what can do without breaking current
             * API? --sergey
             */
            final byte[] v = new byte[unpadded];
            System.arraycopy( src, offset, v, 0, unpadded );
            throw new ReadingNotSupportedException( type, v );
        }
        }
    }

    /**
     * <p>Turns a codepage number into the equivalent character encoding's
     * name.</p>
     *
     * @param codepage The codepage number
     *
     * @return The character encoding's name. If the codepage number is 65001,
     * the encoding name is "UTF-8". All other positive numbers are mapped to
     * "cp" followed by the number, e.g. if the codepage number is 1252 the
     * returned character encoding name will be "cp1252".
     *
     * @exception UnsupportedEncodingException if the specified codepage is
     * less than zero.
     */
    public static String codepageToEncoding(final int codepage)
    throws UnsupportedEncodingException
    {
        return CodePageUtil.codepageToEncoding(codepage);
    }


    /**
     * <p>Writes a variant value to an output stream. This method ensures that
     * always a multiple of 4 bytes is written.</p>
     *
     * <p>If the codepage is UTF-16, which is encouraged, strings
     * <strong>must</strong> always be written as {@link Variant#VT_LPWSTR}
     * strings, not as {@link Variant#VT_LPSTR} strings. This method ensure this
     * by converting strings appropriately, if needed.</p>
     *
     * @param out The stream to write the value to.
     * @param type The variant's type.
     * @param value The variant's value.
     * @param codepage The codepage to use to write non-wide strings
     * @return The number of entities that have been written. In many cases an
     * "entity" is a byte but this is not always the case.
     * @exception IOException if an I/O exceptions occurs
     * @exception WritingNotSupportedException if a property is to be written
     * who's variant type HPSF does not yet support
     */
    public static int write(final OutputStream out, final long type,
                            final Object value, final int codepage)
        throws IOException, WritingNotSupportedException
    {
        int length = 0;
        switch ((int) type)
        {
            case Variant.VT_BOOL:
            {
                if ( ( (Boolean) value ).booleanValue() )
                {
                    out.write( 0xff );
                    out.write( 0xff );
                }
                else
                {
                    out.write( 0x00 );
                    out.write( 0x00 );
                }
                length += 2;
                break;
            }
            case Variant.VT_LPSTR:
            {
                CodePageString codePageString = new CodePageString( (String) value,
                        codepage );
                length += codePageString.write( out );
                break;
            }
            case Variant.VT_LPWSTR:
            {
                final int nrOfChars = ( (String) value ).length() + 1;
                length += TypeWriter.writeUIntToStream( out, nrOfChars );
                char[] s = ( (String) value ).toCharArray();
                for ( int i = 0; i < s.length; i++ )
                {
                    final int high = ( ( s[i] & 0x0000ff00 ) >> 8 );
                    final int low = ( s[i] & 0x000000ff );
                    final byte highb = (byte) high;
                    final byte lowb = (byte) low;
                    out.write( lowb );
                    out.write( highb );
                    length += 2;
                }
                // NullTerminator
                out.write( 0x00 );
                out.write( 0x00 );
                length += 2;
                break;
            }
            case Variant.VT_CF:
            {
                final byte[] b = (byte[]) value;
                out.write(b);
                length = b.length;
                break;
            }
            case Variant.VT_EMPTY:
            {
                length += TypeWriter.writeUIntToStream( out, Variant.VT_EMPTY );
                break;
            }
            case Variant.VT_I2:
            {
                length += TypeWriter.writeToStream( out,
                        ( (Integer) value ).shortValue() );
                break;
            }
            case Variant.VT_I4:
            {
                if (!(value instanceof Integer))
                {
                    throw new ClassCastException("Could not cast an object to "
                            + Integer.class.toString() + ": "
                            + value.getClass().toString() + ", "
                            + value.toString());
                }
                length += TypeWriter.writeToStream(out,
                          ((Integer) value).intValue());
                break;
            }
            case Variant.VT_I8:
            {
                length += TypeWriter.writeToStream(out, ((Long) value).longValue());
                break;
            }
            case Variant.VT_R8:
            {
                length += TypeWriter.writeToStream(out,
                          ((Double) value).doubleValue());
                break;
            }
            case Variant.VT_FILETIME:
            {
                long filetime = Util.dateToFileTime((Date) value);
                int high = (int) ((filetime >> 32) & 0x00000000FFFFFFFFL);
                int low = (int) (filetime & 0x00000000FFFFFFFFL);
                Filetime filetimeValue = new Filetime( low, high);
                length += filetimeValue.write( out );
                break;
            }
            default:
            {
                /* The variant type is not supported yet. However, if the value
                 * is a byte array we can write it nevertheless. */
                if (value instanceof byte[])
                {
                    final byte[] b = (byte[]) value;
                    out.write(b);
                    length = b.length;
                    writeUnsupportedTypeMessage
                        (new WritingNotSupportedException(type, value));
                }
                else
                    throw new WritingNotSupportedException(type, value);
                break;
            }
        }

        /* pad values to 4-bytes */
        while ( ( length & 0x3 ) != 0 )
        {
            out.write( 0x00 );
            length++;
        }

        return length;
    }
}