org.apache.poi.hslf.record.PersistPtrHolder Maven / Gradle / Ivy

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   this work for additional information regarding copyright ownership.
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       http://www.apache.org/licenses/LICENSE-2.0

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package org.apache.poi.hslf.record;

import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.function.Supplier;

import org.apache.poi.hslf.exceptions.CorruptPowerPointFileException;
import org.apache.poi.util.BitField;
import org.apache.poi.util.BitFieldFactory;
import org.apache.poi.util.GenericRecordUtil;
import org.apache.poi.util.IOUtils;
import org.apache.poi.util.LittleEndian;
import org.apache.poi.util.LittleEndianConsts;

/**
 * General holder for PersistPtrFullBlock and PersistPtrIncrementalBlock
 *  records. We need to handle them specially, since we have to go around
 *  updating UserEditAtoms if they shuffle about on disk
 * These hold references to where slides "live". If the position of a slide
 *  moves, then we have update all of these. If we come up with a new version
 *  of a slide, then we have to add one of these to the end of the chain
 *  (via CurrentUserAtom and UserEditAtom) pointing to the new slide location
 */

public final class PersistPtrHolder extends PositionDependentRecordAtom {

    private final byte[] _header;
    private byte[] _ptrData; // Will need to update this once we allow updates to _slideLocations
    private final long _type;

    /**
     * Holds the lookup for slides to their position on disk.
     * You always need to check the most recent PersistPtrHolder
     *  that knows about a given slide to find the right location
     */
    private final Map _slideLocations;

    private static final BitField persistIdFld = BitFieldFactory.getInstance(0X000FFFFF);
    private static final BitField cntPersistFld  = BitFieldFactory.getInstance(0XFFF00000);

    /**
     * Return the value we were given at creation, be it 6001 or 6002
     */
    @Override
    public long getRecordType() { return _type; }

    /**
     * Get the list of slides that this PersistPtrHolder knows about.
     * (They will be the keys in the map for looking up the positions
     *  of these slides)
     */
    public int[] getKnownSlideIDs() {
        int[] ids = new int[_slideLocations.size()];
        int i = 0;
        for (Integer slideId : _slideLocations.keySet()) {
            ids[i++] = slideId;
        }
        return ids;
    }

    /**
     * Get the lookup from slide numbers to byte offsets, for the slides
     *  known about by this PersistPtrHolder.
     */
    public Map getSlideLocationsLookup() {
        return Collections.unmodifiableMap(_slideLocations);
    }

    /**
     * Create a new holder for a PersistPtr record
     */
    protected PersistPtrHolder(byte[] source, int start, int len) {
        // Sanity Checking - including whole header, so treat
        //  length as based of 0, not 8 (including header size based)
        if(len < 8) { len = 8; }

        // Treat as an atom, grab and hold everything
        _header = Arrays.copyOfRange(source, start, start+8);
        _type = LittleEndian.getUShort(_header,2);

        // Try to make sense of the data part:
        // Data part is made up of a number of these sets:
        //   32 bit info value
        //      12 bits count of # of entries
        //      base number for these entries
        //   count * 32 bit offsets
        // Repeat as many times as you have data
        _slideLocations = new HashMap<>();
        _ptrData = IOUtils.safelyClone(source, start+8, len-8, RecordAtom.getMaxRecordLength());

        int pos = 0;
        while(pos < _ptrData.length) {
            // Grab the info field
            int info = LittleEndian.getInt(_ptrData,pos);

            // First 20 bits = offset number
            // Remaining 12 bits = offset count
            int offset_no = persistIdFld.getValue(info);
            int offset_count = cntPersistFld.getValue(info);

            // Wind on by the 4 byte info header
            pos += 4;

            // Grab the offsets for each of the sheets
            for(int i=0; i oldToNewReferencesLookup) {
        // Loop over all the slides we know about
        // Find where they used to live, and where they now live
        for (Entry me : _slideLocations.entrySet()) {
            Integer oldPos = me.getValue();
            Integer newPos = oldToNewReferencesLookup.get(oldPos);

            if (newPos == null) {
                Integer id = me.getKey();
                LOG.atWarn().log("Couldn't find the new location of the \"slide\" with id {} that used to " +
                        "be at {}. Not updating the position of it, you probably won't be able to find it any more " +
                        "(if you ever could!)", id, oldPos);
            } else {
                me.setValue(newPos);
            }
        }
    }

    private void normalizePersistDirectory() {
        // Building the info block
        // First 20 bits = offset number = slide ID (persistIdFld, i.e. first slide ID of a continuous group)
        // Remaining 12 bits = offset count = 1 (cntPersistFld, i.e. continuous entries in a group)
        //
        // the info block is then followed by the slide offset (32 bits)

        int[] infoBlocks = new int[_slideLocations.size()*2];
        int lastSlideId = -1;
        int lastPersistIdx = 0;
        int lastIdx = -1;
        int entryCnt = 0;
        int baseSlideId = -1;

        Iterable> iter = _slideLocations.entrySet().stream()
            .sorted(Comparator.comparingInt(Entry::getKey))::iterator;
        for (Entry me : iter) {
            int nextSlideId = me.getKey();
            if (lastSlideId + 1 < nextSlideId) {
                // start new PersistDirectoryEntry
                lastPersistIdx = ++lastIdx;
                entryCnt = 0;
                baseSlideId = nextSlideId;
            }

            int infoBlock = persistIdFld.setValue(0, baseSlideId);
            infoBlock = cntPersistFld.setValue(infoBlock, ++entryCnt);
            infoBlocks[lastPersistIdx] = infoBlock;
            // add the offset
            infoBlocks[++lastIdx] = me.getValue();

            lastSlideId = nextSlideId;
        }

        // Save the new ptr data
        _ptrData = new byte[(lastIdx+1)*LittleEndianConsts.INT_SIZE];
        for (int idx = 0; idx<=lastIdx; idx++) {
            LittleEndian.putInt(_ptrData, idx*LittleEndianConsts.INT_SIZE, infoBlocks[idx]);
        }

        // Update the atom header
        LittleEndian.putInt(_header, 4, _ptrData.length);
    }

    /**
     * Write the contents of the record back, so it can be written
     *  to disk
     */
    @Override
    public void writeOut(OutputStream out) throws IOException {
        normalizePersistDirectory();
        out.write(_header);
        out.write(_ptrData);
    }

    @Override
    public Map> getGenericProperties() {
        return GenericRecordUtil.getGenericProperties(
            "slideLocations", this::getSlideLocationsLookup
        );
    }
}