Hello again, I created a simple patch for this issue. The ref parameter is copied into a local refCpy variable, which is later used instead of the invalidated ref parameter for deleting the annotation and pdf object. Tested the patch against a sample pdf, the annotations are now correctly removed, nothing is left behind.
Greetings,
F.E.
Am Fr., 29. März 2019 um 13:30 Uhr schrieb F. E. <exler7...@gmail.com>:
> Hello dear podofo users,
>
> I stumbled upon an issue with the deletion of annotations today:
>
> PdfPage.cpp:409ff
>
>> void PdfPage::DeleteAnnotation( int index )
>> {
>> PdfObject* pObj = this->GetAnnotationsArray( false );
>> PdfObject* pItem;
>> [..]
>> pItem = &(pObj->GetArray()[index]);
>> if( pItem->IsDictionary() )
>> {
>> [..]
>> }
>> else
>> {
>> this->DeleteAnnotation( pItem->GetReference() );
>> }
>> }
>>
>
> When calling DeleteAnnotation with an index, the requested Annotation is
> stored into pItem. In my case it is not a dictionary, so DeleteAnnotation
> with a Reference is called:
>
> PdfPage.cpp:446ff
>
>> void PdfPage::DeleteAnnotation( const PdfReference & ref )
>> {
>> [..]
>>
> while( it != pObj->GetArray().end() )
>> {
>> if( (*it).IsReference() && (*it).GetReference() == ref )
>> {
>> pObj->GetArray().erase( it );
>> bFound = true;
>> break;
>> }
>> ++it;
>> }
>> [..]
>> delete this->GetObject()->GetOwner()->RemoveObject( ref );
>> }
>>
>
> Here, the reference is removed from the array and the corresponding object
> is deleted at the end.
> *The problem is, the erase operation on the array destroys the reference
> ref! *I can see with the debugger that Ref's object number changes after
> the erase, so the subsequent RemoveObject call is in error! It either tries
> to remove a non-existing object (best-case) or some other unrelated object
> (worst-case), depending on what values are stored at the location now.
> When checking the resulting PDF, I can see that the annotation objects are
> still there, but it was removed from the page's annotation list.
>
> I guess the fix might be quite easy:
> Either pass the PdfReference by value instead of by reference, or copy it
> into a local before removing it from the array, so a valid PdfReference
> object can be used for subsequent removal.
> I didn't have time to test this myself today, though.
>
> Could someone confirm my findings, please?
> Greetings
> F.E.
>
> p.s.: Sorry for the first, uncomplete mail, didn't know gmail sends the
> mail right away when pressing CTRL+Enter
>
pdfpage_delete_annotation_fix.patch
Description: Binary data
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