Hello dear podofo users,
I was having some issues with an unloadable pdf file. Analysing the file, I
found out that Podofo does not allow a zero for the /Prev key inside the
trailer dictionary:
xref
1 5
0000790024 00000 n
0000000208 00000 n
0000789878 00000 n
0000000012 00000 n
0000790084 00000 n
trailer
<< */Prev 0* /Root 5 0 R /Size 6 >>
startxref
790136
%%EOF
When removing or renaming the "/Prev 0" key, podofo can load the file just fine.
But then the file will no longer be loadable by Adobe Viewer. Why that
happens, I don't know,
especailly since Adobe can load other pdf files without any prev key
without issue.
So to resolve this whole issue, I created a patch that ignores the
/Prev key if its value is zero.
See attached patch.
Greetings
F.E.
--- src/podofo/base/PdfParser.cpp
+++ src/podofo/base/PdfParser.cpp
@@ -586,12 +586,17 @@
if( trailer.GetDictionary().HasKey( "Prev" ) )
{
- // Whenever we read a Prev key,
- // we know that the file was updated.
- m_nIncrementalUpdates++;
-
try {
pdf_long lOffset =
static_cast<pdf_long>(trailer.GetDictionary().GetKeyAsLong( "Prev", 0 ));
+ if( 0 == lOffset )
+ {
+ PdfError::LogMessage( eLogSeverity_Warning, "XRef contents
at offset %" PDF_FORMAT_INT64 " is invalid, skipping the read\n",
static_cast<pdf_int64>( lOffset ));
+ return;
+ }
+
+ // Whenever we read a Prev key (!= 0),
+ // we know that the file was updated.
+ m_nIncrementalUpdates++;
if( m_visitedXRefOffsets.find( lOffset ) ==
m_visitedXRefOffsets.end() )
ReadXRefContents( lOffset );
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