Explicitly check root dictionary type

Very badly corrupted files may not have a retrievable root dictionary. Handle that as a special case so that a more helpful error message can be provided.

Explicitly check root dictionary type
Very badly corrupted files may not have a retrievable root dictionary. Handle that as a special case so that a more helpful error message can be provided.
Jay Berkenbilt
1 parent ede1255a
Showing 7 changed files with 14 additions and 7 deletions
libqpdf/QPDF.cc
qpdf/qtest/qpdf/bad35-recover.out
qpdf/qtest/qpdf/bad35.out
qpdf/qtest/qpdf/issue-100.out
qpdf/qtest/qpdf/issue-118.out
qpdf/qtest/qpdf/issue-99.out
qpdf/qtest/qpdf/issue-99b.out
@@ -2028,7 +2028,14 @@ QPDF::getTrailer()
 QPDFObjectHandle
 QPDF::getRoot()
 {
-    return this->trailer.getKey("/Root");
+    QPDFObjectHandle root = this->trailer.getKey("/Root");
+    if (! root.isDictionary())
+    {
+        throw QPDFExc(qpdf_e_damaged_pdf, file->getName(),
+                      "", file->getLastOffset(),
+                      "unable to find /Root dictionary");
+    }
+    return root;
 }
 void
 WARNING: bad35.pdf (object 1 0, file position 521): supposed object stream 1 has wrong type
-operation for Dictionary object attempted on object of wrong type
+bad35.pdf (file position 521): unable to find /Root dictionary
 WARNING: bad35.pdf (object 1 0, file position 521): supposed object stream 1 has wrong type
-operation for Dictionary object attempted on object of wrong type
+bad35.pdf (file position 521): unable to find /Root dictionary
@@ -12,4 +12,4 @@ WARNING: issue-100.pdf (object 5 0, file position 418): /Length key in stream di
 WARNING: issue-100.pdf (object 5 0, file position 489): attempting to recover stream length
 WARNING: issue-100.pdf (trailer, file position 953): expected dictionary key but found non-name object; inserting key /QPDFFake1
 WARNING: issue-100.pdf (trailer, file position 953): dictionary ended prematurely; using null as value for last key
-operation for Dictionary object attempted on object of wrong type
+issue-100.pdf (file position 1138): unable to find /Root dictionary
 WARNING: issue-118.pdf (file position 732): loop detected resolving object 2 0
 WARNING: issue-118.pdf (xref stream: object 8 0, file position 732): supposed object stream 2 is not a stream
-operation for Dictionary object attempted on object of wrong type
+issue-118.pdf (file position 732): unable to find /Root dictionary
 WARNING: issue-99.pdf: file is damaged
 WARNING: issue-99.pdf (file position 3526): xref not found
 WARNING: issue-99.pdf: Attempting to reconstruct cross-reference table
-operation for Dictionary object attempted on object of wrong type
+issue-99.pdf (file position 4793): unable to find /Root dictionary
@@ -2,4 +2,4 @@ WARNING: issue-99b.pdf: file is damaged
 WARNING: issue-99b.pdf (object 1 0, file position 9): object with ID 0
 WARNING: issue-99b.pdf: Attempting to reconstruct cross-reference table
 WARNING: issue-99b.pdf: object 1 0 not found in file after regenerating cross reference table
-operation for Dictionary object attempted on object of wrong type
+issue-99b.pdf (file position 757): unable to find /Root dictionary