pdfviewer: when q start, and an operator is called, it should not be able to see operands before q.…

experimental/PdfViewer/pdfparser/native/SkPdfNativeDoc.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPdfNativeDoc.h"
 #include "SkPdfNativeTokenizer.h"
 #include "SkPdfNativeObject.h"
@@ skipping 340 matching lines @@
 
 void SkPdfNativeDoc::addCrossSectionInfo(int id, int generation, int offset, bool isFreed) {
     // TODO(edisonn): security here
     while (fObjects.count() < id + 1) {
         reset(fObjects.append());
     }
 
     fObjects[id].fOffset = offset;
     fObjects[id].fObj = NULL;
     fObjects[id].fResolvedReference = NULL;
+    fObjects[id].fIsReferenceResolved = false;
 }
 
 SkPdfNativeObject* SkPdfNativeDoc::readObject(int id/*, int expectedGeneration*/) {
     long startOffset = fObjects[id].fOffset;
     //long endOffset = fObjects[id].fOffsetEnd;
     // TODO(edisonn): use hinted endOffset
     // TODO(edisonn): current implementation will result in a lot of memory usage
     // to decrease memory usage, we wither need to be smart and know where objects end, and we will
     // alocate only the chancks needed, or the tokenizer will not make copies, but then it needs to
     // cache the results so it does not go twice on the same buffer
@@ skipping 168 matching lines @@
         int id = ref->referenceId();
         // TODO(edisonn): generation/updates not supported now
         //int gen = ref->referenceGeneration();
 
         // TODO(edisonn): verify id and gen expected
         if (id < 0 || id >= fObjects.count()) {
             // TODO(edisonn): report error/warning
             return NULL;
         }
 
-        if (fObjects[id].fResolvedReference != NULL) {
+        if (fObjects[id].fIsReferenceResolved) {
 
 #ifdef PDF_TRACE
             printf("\nresolve(%s) = %s\n", ref->toString(0).c_str(), fObjects[id].fResolvedReference->toString(0, ref->toString().size() + 13).c_str());
 #endif
 
+            // TODO(edisonn): for known good documents, assert here THAT THE REFERENCE IS NOT null
             return fObjects[id].fResolvedReference;
         }
 
+        // TODO(edisonn): there are pdfs in the crashing suite that cause a stack overflow here unless we check for resolved reference on next line
+        // determine if the pdf is corrupted, or we have a bug here
+
+        // avoids recursive calls
+        fObjects[id].fIsReferenceResolved = true;
+
         if (fObjects[id].fObj == NULL) {
             fObjects[id].fObj = readObject(id);
         }
 
         if (fObjects[id].fResolvedReference == NULL) {
             if (!fObjects[id].fObj->isReference()) {
                 fObjects[id].fResolvedReference = fObjects[id].fObj;
             } else {
                 fObjects[id].fResolvedReference = resolveReference(fObjects[id].fObj);
             }
         }
 
 #ifdef PDF_TRACE
         printf("\nresolve(%s) = %s\n", ref->toString(0).c_str(), fObjects[id].fResolvedReference->toString(0, ref->toString().size() + 13).c_str());
 #endif
         return fObjects[id].fResolvedReference;
     }
 
     // TODO(edisonn): fix the mess with const, probably we need to remove it pretty much everywhere
     return (SkPdfNativeObject*)ref;
 }
 
 size_t SkPdfNativeDoc::bytesUsed() const {
     return fAllocator->bytesUsed() +
            fContentLength +
            fObjects.count() * sizeof(PublicObjectEntry) +
            fPages.count() * sizeof(SkPdfPageObjectDictionary*) +
            sizeof(*this);
 }