Detect loops in /Pages structure

Pushing inherited objects to pages and getting all pages were both
prone to stack overflow infinite loops if there were loops in the
Pages dictionary. There is a general weakness in the code in that any
part of the code that traverses the Pages structure would be prone to
this and would have to implement its own loop detection. A more robust
fix may provide some general method for handling the Pages structure,
but it's probably not worth doing.

Note: addition of *Internal2 private functions was done rather than
changing signatures of existing methods to avoid breaking
compatibility.

1 files changed, 9 insertions, 0 deletions

diff --git a/include/qpdf/QPDF.hh b/include/qpdf/QPDF.hh
index dfce40c1..71ff7e27 100644
--- a/include/qpdf/QPDF.hh
+++ b/include/qpdf/QPDF.hh
@@ -668,6 +668,9 @@ class QPDF
 
     void getAllPagesInternal(QPDFObjectHandle cur_pages,
 			     std::vector<QPDFObjectHandle>& result);
+    void getAllPagesInternal2(QPDFObjectHandle cur_pages,
+                              std::vector<QPDFObjectHandle>& result,
+                              std::set<QPDFObjGen>& visited);
     void insertPage(QPDFObjectHandle newpage, int pos);
     int findPage(QPDFObjGen const& og);
     int findPage(QPDFObjectHandle& page);
@@ -1023,6 +1026,12 @@ class QPDF
 	std::map<std::string, std::vector<QPDFObjectHandle> >&,
 	std::vector<QPDFObjectHandle>& all_pages,
 	bool allow_changes, bool warn_skipped_keys);
+    void pushInheritedAttributesToPageInternal2(
+	QPDFObjectHandle,
+	std::map<std::string, std::vector<QPDFObjectHandle> >&,
+	std::vector<QPDFObjectHandle>& all_pages,
+	bool allow_changes, bool warn_skipped_keys,
+        std::set<QPDFObjGen>& visited);
     void updateObjectMaps(ObjUser const& ou, QPDFObjectHandle oh);
     void updateObjectMapsInternal(ObjUser const& ou, QPDFObjectHandle oh,
 				  std::set<QPDFObjGen>& visited, bool top);