Add precheck streams capability

When requested, QPDFWriter will do more aggress prechecking of streams
to make sure it can actually succeed in decoding them before
attempting to do so. This will allow preservation of raw data even
when the raw data is corrupted relative to the specified filters.

1 files changed, 19 insertions, 9 deletions

diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index 32c8cdf9..b5c1212c 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -2134,12 +2134,14 @@ QPDF::getCompressibleObjGens()
     return result;
 }
 
-void
+bool
 QPDF::pipeStreamData(int objid, int generation,
 		     qpdf_offset_t offset, size_t length,
 		     QPDFObjectHandle stream_dict,
-		     Pipeline* pipeline)
+		     Pipeline* pipeline,
+                     bool suppress_warnings)
 {
+    bool success = false;
     std::vector<PointerHolder<Pipeline> > to_delete;
     if (this->encrypted)
     {
@@ -2165,21 +2167,29 @@ QPDF::pipeStreamData(int objid, int generation,
 	    length -= len;
 	    pipeline->write(QUtil::unsigned_char_pointer(buf), len);
 	}
+        success = true;
     }
     catch (QPDFExc& e)
     {
-	warn(e);
+        if (! suppress_warnings)
+        {
+            warn(e);
+        }
     }
     catch (std::runtime_error& e)
     {
-	QTC::TC("qpdf", "QPDF decoding error warning");
-	warn(QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
-		     "", this->file->getLastOffset(),
-		     "error decoding stream data for object " +
-		     QUtil::int_to_string(objid) + " " +
-		     QUtil::int_to_string(generation) + ": " + e.what()));
+        if (! suppress_warnings)
+        {
+            QTC::TC("qpdf", "QPDF decoding error warning");
+            warn(QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
+                         "", this->file->getLastOffset(),
+                         "error decoding stream data for object " +
+                         QUtil::int_to_string(objid) + " " +
+                         QUtil::int_to_string(generation) + ": " + e.what()));
+        }
     }
     pipeline->finish();
+    return success;
 }
 
 void