Improve message for stream decoding error

Tweak the message so that we inform the user that we are mitigating
data loss.

5 files changed, 27 insertions, 8 deletions

diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index bea83c98..1ec0d6b6 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -2382,7 +2382,8 @@ QPDF::pipeStreamData(int objid, int generation,
 		     qpdf_offset_t offset, size_t length,
 		     QPDFObjectHandle stream_dict,
 		     Pipeline* pipeline,
-                     bool suppress_warnings)
+                     bool suppress_warnings,
+                     bool will_retry)
 {
     bool success = false;
     std::vector<PointerHolder<Pipeline> > to_delete;
@@ -2430,6 +2431,13 @@ QPDF::pipeStreamData(int objid, int generation,
                          "error decoding stream data for object " +
                          QUtil::int_to_string(objid) + " " +
                          QUtil::int_to_string(generation) + ": " + e.what()));
+            if (will_retry)
+            {
+                warn(QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
+                             "", this->m->file->getLastOffset(),
+                             "stream will be re-processed without"
+                             " filtering to avoid data loss"));
+            }
         }
     }
     if (! success)
diff --git a/libqpdf/QPDFObjectHandle.cc b/libqpdf/QPDFObjectHandle.cc
index 888d9a3a..247b3b38 100644
--- a/libqpdf/QPDFObjectHandle.cc
+++ b/libqpdf/QPDFObjectHandle.cc
@@ -501,9 +501,19 @@ QPDFObjectHandle::pipeStreamData(Pipeline* p,
                                  qpdf_stream_decode_level_e decode_level,
                                  bool suppress_warnings)
 {
+    return pipeStreamData(
+        p, encode_flags, decode_level, suppress_warnings, false);
+}
+
+bool
+QPDFObjectHandle::pipeStreamData(Pipeline* p,
+                                 unsigned long encode_flags,
+                                 qpdf_stream_decode_level_e decode_level,
+                                 bool suppress_warnings, bool will_retry)
+{
     assertStream();
     return dynamic_cast<QPDF_Stream*>(obj.getPointer())->pipeStreamData(
-	p, encode_flags, decode_level, suppress_warnings);
+	p, encode_flags, decode_level, suppress_warnings, will_retry);
 }
 
 bool
diff --git a/libqpdf/QPDFWriter.cc b/libqpdf/QPDFWriter.cc
index 1ce4bfb6..d4e13310 100644
--- a/libqpdf/QPDFWriter.cc
+++ b/libqpdf/QPDFWriter.cc
@@ -1623,7 +1623,7 @@ QPDFWriter::unparseObject(QPDFObjectHandle object, int level,
                      ((filter && compress) ? qpdf_ef_compress : 0)),
                     (filter
                      ? (uncompress ? qpdf_dl_all : this->m->stream_decode_level)
-                     : qpdf_dl_none));
+                     : qpdf_dl_none), false, (attempt == 1));
             popPipelineStack(&stream_data);
             if (filter && (! filtered))
             {
diff --git a/libqpdf/QPDF_Stream.cc b/libqpdf/QPDF_Stream.cc
index 27c6b477..cf26f001 100644
--- a/libqpdf/QPDF_Stream.cc
+++ b/libqpdf/QPDF_Stream.cc
@@ -94,7 +94,7 @@ PointerHolder<Buffer>
 QPDF_Stream::getStreamData(qpdf_stream_decode_level_e decode_level)
 {
     Pl_Buffer buf("stream data buffer");
-    if (! pipeStreamData(&buf, 0, decode_level, false))
+    if (! pipeStreamData(&buf, 0, decode_level, false, false))
     {
 	throw std::logic_error("getStreamData called on unfilterable stream");
     }
@@ -106,7 +106,7 @@ PointerHolder<Buffer>
 QPDF_Stream::getRawStreamData()
 {
     Pl_Buffer buf("stream data buffer");
-    pipeStreamData(&buf, 0, qpdf_dl_none, false);
+    pipeStreamData(&buf, 0, qpdf_dl_none, false, false);
     QTC::TC("qpdf", "QPDF_Stream getRawStreamData");
     return buf.getBuffer();
 }
@@ -373,7 +373,7 @@ bool
 QPDF_Stream::pipeStreamData(Pipeline* pipeline,
                             unsigned long encode_flags,
                             qpdf_stream_decode_level_e decode_level,
-                            bool suppress_warnings)
+                            bool suppress_warnings, bool will_retry)
 {
     std::vector<std::string> filters;
     int predictor = 1;
@@ -540,7 +540,8 @@ QPDF_Stream::pipeStreamData(Pipeline* pipeline,
 	if (! QPDF::Pipe::pipeStreamData(this->qpdf, this->objid, this->generation,
                                          this->offset, this->length,
                                          this->stream_dict, pipeline,
-                                         suppress_warnings))
+                                         suppress_warnings,
+                                         will_retry))
         {
             filter = false;
         }
diff --git a/libqpdf/qpdf/QPDF_Stream.hh b/libqpdf/qpdf/QPDF_Stream.hh
index a2bd5d61..50771627 100644
--- a/libqpdf/qpdf/QPDF_Stream.hh
+++ b/libqpdf/qpdf/QPDF_Stream.hh
@@ -25,7 +25,7 @@ class QPDF_Stream: public QPDFObject
     bool pipeStreamData(Pipeline*,
                         unsigned long encode_flags,
                         qpdf_stream_decode_level_e decode_level,
-                        bool suppress_warnings);
+                        bool suppress_warnings, bool will_retry);
     PointerHolder<Buffer> getStreamData(qpdf_stream_decode_level_e);
     PointerHolder<Buffer> getRawStreamData();
     void replaceStreamData(PointerHolder<Buffer> data,