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Rework EscherRecordHolder parsing 

Modify the parsing done by EscherRecordHolder to be more deterministic. The format of the OfficeArtContent structure, which the EscherRecordHolder represents, is well defined in the MS-DOC spec. A clear class structure makes it easier to reason about the availability of data.

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1887008 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Marius Volkhart 2021-02-28 18:49:42 +00:00
parent fab0ec3e08
commit 9c88bb2201
1 changed files with 87 additions and 107 deletions
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194
src/scratchpad/src/org/apache/poi/hwpf/model/EscherRecordHolder.java
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@ -18,15 +18,18 @@
package org.apache.poi.hwpf.model;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.apache.logging.log4j.LogManager;
import org.apache.poi.ddf.DefaultEscherRecordFactory;
import org.apache.poi.ddf.EscherContainerRecord;
import org.apache.poi.ddf.EscherRecord;
import org.apache.poi.ddf.EscherRecordFactory;
import org.apache.poi.ddf.EscherRecordTypes;
import org.apache.poi.util.Internal;
import static org.apache.logging.log4j.util.Unbox.box;
/**
* Based on AbstractEscherRecordHolder from HSSF.
*
@ -34,7 +37,27 @@ import org.apache.poi.util.Internal;
*/
@Internal
public final class EscherRecordHolder {
private final ArrayList<EscherRecord> escherRecords = new ArrayList<>();
/**
* {@link EscherRecordTypes#DGG_CONTAINER} containing drawing group information for the document.
*/
private final EscherContainerRecord drawingGroupData = new EscherContainerRecord();
/**
* {@link EscherRecordTypes#DG_CONTAINER} for drawings in the Main Document.
* <p>
* {@code null} to indicate that the document does not have a {@link EscherRecordTypes#DG_CONTAINER} for the Main
* Document.
*/
private EscherContainerRecord mainDocumentDgContainer;
/**
* {@link EscherRecordTypes#DG_CONTAINER} for drawings in the Header Document.
* <p>
* {@code null} to indicate that the document does not have a {@link EscherRecordTypes#DG_CONTAINER} for the Header
* Document.
*/
private EscherContainerRecord headerDocumentDgContainer;
public EscherRecordHolder(byte[] data, int offset, int size) {
fillEscherRecords(data, offset, size);
@ -47,129 +70,77 @@ public final class EscherRecordHolder {
*
* @see FileInformationBlock#getLcbDggInfo()
*/
private void fillEscherRecords(byte[] data, int offset, int size)
{
private void fillEscherRecords(byte[] data, int offset, int size) {
if (size == 0) return;
EscherRecordFactory recordFactory = new DefaultEscherRecordFactory();
int pos = offset;
while ( pos < offset + size)
{
EscherRecord r = recordFactory.createRecord(data, pos);
escherRecords.add(r);
int bytesRead = r.fillFields(data, pos, recordFactory);
pos += bytesRead + 1; // There is an empty byte between each top-level record in a Word doc
pos += drawingGroupData.fillFields(data, pos, recordFactory);
assert drawingGroupData.getRecordId() == EscherRecordTypes.DGG_CONTAINER.typeID;
/*
* After the drawingGroupData there is an array (2 slots max) that has data about drawings. According to the
* spec, the first slot is for the Main Document, the second for the Header Document. Additionally, the
* OfficeArtWordDrawing structure has a byte (dgglbl) that indicates whether the structure is for the Main or
* Header Document. In practice we've seen documents such as 61911.doc where the order of array entries does not
* match the dgglbl byte. As the byte is more likely to be reliable, we base the parsing off of that rather than
* array order.
*/
// This should loop at most twice
while (pos < offset + size) {
// Named this way to match section 2.9.172 of [MS-DOC] - v20191119.
byte dgglbl = data[pos];
assert dgglbl == 0x00 || dgglbl == 0x01;
pos++;
EscherContainerRecord dgContainer = new EscherContainerRecord();
pos+= dgContainer.fillFields(data, pos, recordFactory);
assert dgContainer.getRecordId() == EscherRecordTypes.DG_CONTAINER.typeID;
switch (dgglbl) {
case 0x00:
mainDocumentDgContainer = dgContainer;
break;
case 0x01:
headerDocumentDgContainer = dgContainer;
break;
default:
LogManager.getLogger(EscherRecordHolder.class).atWarn()
.log("dgglbl {} for OfficeArtWordDrawing is out of bounds [0, 1]", box(dgglbl));
}
}
assert pos == offset + size;
}
public List<EscherRecord> getEscherRecords() {
return escherRecords;
return drawingGroupData.getChildRecords();
}
@Override
public String toString() {
StringBuilder buffer = new StringBuilder();
if (escherRecords.size() == 0) {
buffer.append("No Escher Records Decoded").append("\n");
}
Iterator<EscherRecord> iterator = escherRecords.iterator();
while (iterator.hasNext()) {
EscherRecord r = iterator.next();
buffer.append(r);
}
return buffer.toString();
}
/**
* If we have a EscherContainerRecord as one of our
* children (and most top level escher holders do),
* then return that.
*/
public EscherContainerRecord getEscherContainer() {
for(Iterator<EscherRecord> it = escherRecords.iterator(); it.hasNext();) {
Object er = it.next();
if(er instanceof EscherContainerRecord) {
return (EscherContainerRecord)er;
}
}
return null;
}
/**
* Descends into all our children, returning the
* first EscherRecord with the given id, or null
* if none found
*/
public EscherRecord findFirstWithId(short id) {
return findFirstWithId(id, getEscherRecords());
}
private static EscherRecord findFirstWithId(short id, List<EscherRecord> records) {
// Check at our level
for(Iterator<EscherRecord> it = records.iterator(); it.hasNext();) {
EscherRecord r = it.next();
if(r.getRecordId() == id) {
return r;
}
}
// Then check our children in turn
for(Iterator<EscherRecord> it = records.iterator(); it.hasNext();) {
EscherRecord r = it.next();
if(r.isContainerRecord()) {
EscherRecord found = findFirstWithId(id, r.getChildRecords());
if(found != null) {
return found;
}
}
}
// Not found in this lot
return null;
}
public List<? extends EscherContainerRecord> getDgContainers()
{
List<EscherContainerRecord> dgContainers = new ArrayList<>(
1);
for ( EscherRecord escherRecord : getEscherRecords() )
{
if ( escherRecord.getRecordId() == (short) 0xF002 )
{
dgContainers.add( (EscherContainerRecord) escherRecord );
}
public List<? extends EscherContainerRecord> getDgContainers() {
List<EscherContainerRecord> dgContainers = new ArrayList<>(2);
if (mainDocumentDgContainer != null) {
dgContainers.add(mainDocumentDgContainer);
}
if (headerDocumentDgContainer != null) {
dgContainers.add(headerDocumentDgContainer);
}
return dgContainers;
}
public List<? extends EscherContainerRecord> getDggContainers()
{
List<EscherContainerRecord> dggContainers = new ArrayList<>(
1);
for ( EscherRecord escherRecord : getEscherRecords() )
{
if ( escherRecord.getRecordId() == (short) 0xF000 )
{
dggContainers.add( (EscherContainerRecord) escherRecord );
}
}
return dggContainers;
}
public List<? extends EscherContainerRecord> getBStoreContainers()
{
List<EscherContainerRecord> bStoreContainers = new ArrayList<>(
1);
for ( EscherContainerRecord dggContainer : getDggContainers() )
{
for ( EscherRecord escherRecord : dggContainer.getChildRecords() )
{
if ( escherRecord.getRecordId() == (short) 0xF001 )
{
bStoreContainers.add( (EscherContainerRecord) escherRecord );
}
}
}
for ( EscherRecord escherRecord : drawingGroupData.getChildRecords() )
{
if ( escherRecord.getRecordId() == (short) 0xF001 )
{
bStoreContainers.add( (EscherContainerRecord) escherRecord );
}
}
return bStoreContainers;
}
@ -206,4 +177,13 @@ public final class EscherRecordHolder {
}
return spContainers;
}
@Override
public String toString() {
return "EscherRecordHolder{" +
"drawingGroupData=" + drawingGroupData +
", mainDocumentDgContainer=" + mainDocumentDgContainer +
", headerDocumentDgContainer=" + headerDocumentDgContainer +
'}';
}
}