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PDFBOX-5283: ignore dublicate object keys when correcting xRefs #129

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PDFBOX-5283: ignore dublicate object keys when correcting xRefs #129

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8604732
PDFBOX-5283: irgnore wrong object number in lenient mode
Schmidor Sep 23, 2021
ea0a6e0
only replace xRef with corrected entries, if the original entry was n…
Schmidor Oct 5, 2021
cd2c0ac
HashSet instead of HashMap for valid keys
Schmidor Oct 6, 2021
5ea0492
read pointers before replacing
Schmidor Mar 10, 2022
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48 changes: 32 additions & 16 deletions pdfbox/src/main/java/org/apache/pdfbox/pdfparser/COSParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1159,6 +1159,7 @@ private boolean validateXrefOffsets(Map<COSObjectKey, Long> xrefOffset) throws I
return true;
}
Map<COSObjectKey, COSObjectKey> correctedKeys = new HashMap<>();
HashSet<COSObjectKey> validKeys = new HashSet<>();
for (Entry<COSObjectKey, Long> objectEntry : xrefOffset.entrySet())
{
COSObjectKey objectKey = objectEntry.getKey();
Expand All @@ -1178,13 +1179,24 @@ else if (foundObjectKey != objectKey)
{
// Generation was fixed - need to update map later, after iteration
correctedKeys.put(objectKey, foundObjectKey);
} else {
validKeys.add(objectKey);
}
}
}
for (Entry<COSObjectKey, COSObjectKey> correctedKeyEntry : correctedKeys.entrySet())
{
xrefOffset.put(correctedKeyEntry.getValue(),
xrefOffset.remove(correctedKeyEntry.getKey()));
Map<COSObjectKey, Long> correctedPointers = new HashMap<COSObjectKey, Long>();
for (Entry<COSObjectKey, COSObjectKey> correctedKeyEntry : correctedKeys.entrySet()) {
if (!validKeys.contains(correctedKeyEntry.getValue())) {
// Only replace entries, if the original entry does not point to a valid object
correctedPointers.put(correctedKeyEntry.getValue(), xrefOffset.get(correctedKeyEntry.getKey()));
}
}
for (Entry<COSObjectKey, COSObjectKey> correctedKeyEntry : correctedKeys.entrySet()) {
// remove old invalid, as some might not be replaced
xrefOffset.remove(correctedKeyEntry.getKey());
}
for (Entry<COSObjectKey, Long> pointer : correctedPointers.entrySet()) {
xrefOffset.put(pointer.getKey(), pointer.getValue());
}
return true;
}
Expand Down Expand Up @@ -1235,19 +1247,23 @@ private COSObjectKey findObjectKey(COSObjectKey objectKey, long offset) throws I
{
source.seek(offset);
// try to read the given object/generation number
if (objectKey.getNumber() == readObjectNumber())
long foundObjectNumber = readObjectNumber();
if(objectKey.getNumber() != foundObjectNumber){
LOG.warn("found wrong object number. expected [" + objectKey.getNumber() +"] found ["+ foundObjectNumber + "]");
if(!isLenient) return null;
else objectKey = new COSObjectKey(foundObjectNumber, objectKey.getGeneration());
}

int genNumber = readGenerationNumber();
// finally try to read the object marker
readExpectedString(OBJ_MARKER, true);
if (genNumber == objectKey.getGeneration())
{
int genNumber = readGenerationNumber();
// finally try to read the object marker
readExpectedString(OBJ_MARKER, true);
if (genNumber == objectKey.getGeneration())
{
return objectKey;
}
else if (isLenient && genNumber > objectKey.getGeneration())
{
return new COSObjectKey(objectKey.getNumber(), genNumber);
}
return objectKey;
}
else if (isLenient && genNumber > objectKey.getGeneration())
{
return new COSObjectKey(objectKey.getNumber(), genNumber);
}
}
catch (IOException exception)
Expand Down