Fix foreign stream copying bug (fixes #478)

This reverts an incorrect fix to #449 and codes it properly. The real problem was that we were looking at the local dictionaries rather than the foreign dictionaries when saving the foreign stream data. In the case of direct objects, these happened to be the same, but in the case of indirect objects, the object references could be pointing anywhere since object numbers don't match up between the old and new files.

Fix foreign stream copying bug (fixes #478)
This reverts an incorrect fix to #449 and codes it properly. The real problem was that we were looking at the local dictionaries rather than the foreign dictionaries when saving the foreign stream data. In the case of direct objects, these happened to be the same, but in the case of indirect objects, the object references could be pointing anywhere since object numbers don't match up between the old and new files.
Jay Berkenbilt
1 parent f1ae55a4
Showing 4 changed files with 17 additions and 16 deletions
ChangeLog
libqpdf/QPDF.cc
qpdf/qtest/qpdf/indirect-filter-out-0.pdf
qpdf/qtest/qpdf/indirect-filter-out-1.pdf
+2020-10-31  Jay Berkenbilt  <ejb@ql.org>
+
+	* My previous fix to #449 (handling foreign streams with indirect
+	objects in /Filter and/or /DecodeParms) was incorrect and caused
+	other problems. There is a now a correct fix to the original
+	problem. Fixes #478.
+
 2020-10-27  Jay Berkenbilt  <ejb@ql.org>
 	* 10.0.2: release
@@ -2317,8 +2317,7 @@ QPDF::reserveObjects(QPDFObjectHandle foreign, ObjCopier&amp; obj_copier,
     if (foreign.isReserved())
     {
         throw std::logic_error(
-            "QPDF: attempting to copy a foreign reserved object: " +
-            QUtil::int_to_string(foreign.getObjectID()));
+            "QPDF: attempting to copy a foreign reserved object");
     }
     if (foreign.isPagesObject())
@@ -2491,16 +2490,6 @@ QPDF::replaceForeignIndirectObjects(
         }
         PointerHolder<Buffer> stream_buffer =
             stream->getStreamDataBuffer();
-        // Note: at this stage, dictionary keys may still be reserved.
-        // We have to handle that explicitly if we access anything.
-        auto get_as_direct = [&old_dict] (std::string const& key) {
-            QPDFObjectHandle obj = old_dict.getKey(key);
-            obj.makeDirect();
-            return obj;
-        };
-
-        QPDFObjectHandle filter = get_as_direct("/Filter");
-        QPDFObjectHandle decode_parms = get_as_direct("/DecodeParms");
         if ((foreign_stream_qpdf->m->immediate_copy_from) &&
             (stream_buffer.getPointer() == 0))
         {
@@ -2510,7 +2499,8 @@ QPDF::replaceForeignIndirectObjects(
             // have to keep duplicating the memory.
             QTC::TC("qpdf", "QPDF immediate copy stream data");
             foreign.replaceStreamData(foreign.getRawStreamData(),
-                                      filter, decode_parms);
+                                      old_dict.getKey("/Filter"),
+                                      old_dict.getKey("/DecodeParms"));
             stream_buffer = stream->getStreamDataBuffer();
         }
         PointerHolder<QPDFObjectHandle::StreamDataProvider> stream_provider =
@@ -2518,7 +2508,9 @@ QPDF::replaceForeignIndirectObjects(
         if (stream_buffer.getPointer())
         {
             QTC::TC("qpdf", "QPDF copy foreign stream with buffer");
-            result.replaceStreamData(stream_buffer, filter, decode_parms);
+            result.replaceStreamData(stream_buffer,
+                                     dict.getKey("/Filter"),
+                                     dict.getKey("/DecodeParms"));
         }
         else if (stream_provider.getPointer())
         {
@@ -2527,7 +2519,8 @@ QPDF::replaceForeignIndirectObjects(
             this->m->copied_stream_data_provider->registerForeignStream(
                 local_og, foreign);
             result.replaceStreamData(this->m->copied_streams,
-                                     filter, decode_parms);
+                                     dict.getKey("/Filter"),
+                                     dict.getKey("/DecodeParms"));
         }
         else
         {
@@ -2545,7 +2538,8 @@ QPDF::replaceForeignIndirectObjects(
             this->m->copied_stream_data_provider->registerForeignStream(
                 local_og, foreign_stream_data);
             result.replaceStreamData(this->m->copied_streams,
-                                     filter, decode_parms);
+                                     dict.getKey("/Filter"),
+                                     dict.getKey("/DecodeParms"));
         }
     }
     else