Don't require stream data provider to know length in advance

Breaking API change: length parameter has disappeared from the
StreamDataProvider version of QPDFObjectHandle::replaceStreamData
since it is no longer necessary to compute it in advance.  This
breaking change is justified by the fact that removing the length
parameter provides the caller an opportunity to simplify the calling
code.

3 files changed, 42 insertions, 28 deletions

diff --git a/libqpdf/QPDFObjectHandle.cc b/libqpdf/QPDFObjectHandle.cc
index 4d6c5f79..c8b67416 100644
--- a/libqpdf/QPDFObjectHandle.cc
+++ b/libqpdf/QPDFObjectHandle.cc
@@ -414,12 +414,11 @@ QPDFObjectHandle::replaceStreamData(PointerHolder<Buffer> data,
 void
 QPDFObjectHandle::replaceStreamData(PointerHolder<StreamDataProvider> provider,
 				    QPDFObjectHandle const& filter,
-				    QPDFObjectHandle const& decode_parms,
-				    size_t length)
+				    QPDFObjectHandle const& decode_parms)
 {
     assertType("Stream", isStream());
     dynamic_cast<QPDF_Stream*>(obj.getPointer())->replaceStreamData(
-	provider, filter, decode_parms, length);
+	provider, filter, decode_parms);
 }
 
 int
diff --git a/libqpdf/QPDF_Stream.cc b/libqpdf/QPDF_Stream.cc
index ed5fb5be..c089bcc1 100644
--- a/libqpdf/QPDF_Stream.cc
+++ b/libqpdf/QPDF_Stream.cc
@@ -380,24 +380,33 @@ QPDF_Stream::pipeStreamData(Pipeline* pipeline, bool filter,
 	this->stream_provider->provideStreamData(
 	    this->objid, this->generation, &count);
 	qpdf_offset_t actual_length = count.getCount();
-	qpdf_offset_t desired_length =
-	    this->stream_dict.getKey("/Length").getIntValue();
-	if (actual_length == desired_length)
-	{
-	    QTC::TC("qpdf", "QPDF_Stream pipe use stream provider");
-	}
-	else
-	{
-	    QTC::TC("qpdf", "QPDF_Stream provider length mismatch");
-	    throw std::logic_error(
-		"stream data provider for " +
-		QUtil::int_to_string(this->objid) + " " +
-		QUtil::int_to_string(this->generation) +
-		" provided " +
-		QUtil::int_to_string(actual_length) +
-		" bytes instead of expected " +
-		QUtil::int_to_string(desired_length) + " bytes");
-	}
+	qpdf_offset_t desired_length = 0;
+        if (this->stream_dict.hasKey("/Length"))
+        {
+	    desired_length = this->stream_dict.getKey("/Length").getIntValue();
+            if (actual_length == desired_length)
+            {
+                QTC::TC("qpdf", "QPDF_Stream pipe use stream provider");
+            }
+            else
+            {
+                QTC::TC("qpdf", "QPDF_Stream provider length mismatch");
+                throw std::logic_error(
+                    "stream data provider for " +
+                    QUtil::int_to_string(this->objid) + " " +
+                    QUtil::int_to_string(this->generation) +
+                    " provided " +
+                    QUtil::int_to_string(actual_length) +
+                    " bytes instead of expected " +
+                    QUtil::int_to_string(desired_length) + " bytes");
+            }
+        }
+        else
+        {
+            QTC::TC("qpdf", "QPDF_Stream provider length not provided");
+            this->stream_dict.replaceKey(
+                "/Length", QPDFObjectHandle::newInteger(actual_length));
+        }
     }
     else if (this->offset == 0)
     {
@@ -430,12 +439,11 @@ void
 QPDF_Stream::replaceStreamData(
     PointerHolder<QPDFObjectHandle::StreamDataProvider> provider,
     QPDFObjectHandle const& filter,
-    QPDFObjectHandle const& decode_parms,
-    size_t length)
+    QPDFObjectHandle const& decode_parms)
 {
     this->stream_provider = provider;
     this->stream_data = 0;
-    replaceFilterData(filter, decode_parms, length);
+    replaceFilterData(filter, decode_parms, 0);
 }
 
 void
@@ -445,6 +453,14 @@ QPDF_Stream::replaceFilterData(QPDFObjectHandle const& filter,
 {
     this->stream_dict.replaceOrRemoveKey("/Filter", filter);
     this->stream_dict.replaceOrRemoveKey("/DecodeParms", decode_parms);
-    this->stream_dict.replaceKey("/Length",
-				 QPDFObjectHandle::newInteger((int)length));
+    if (length == 0)
+    {
+        QTC::TC("qpdf", "QPDF_Stream unknown stream length");
+        this->stream_dict.removeKey("/Length");
+    }
+    else
+    {
+        this->stream_dict.replaceKey(
+            "/Length", QPDFObjectHandle::newInteger((int)length));
+    }
 }
diff --git a/libqpdf/qpdf/QPDF_Stream.hh b/libqpdf/qpdf/QPDF_Stream.hh
index e74ae201..ce46d994 100644
--- a/libqpdf/qpdf/QPDF_Stream.hh
+++ b/libqpdf/qpdf/QPDF_Stream.hh
@@ -30,8 +30,7 @@ class QPDF_Stream: public QPDFObject
     void replaceStreamData(
 	PointerHolder<QPDFObjectHandle::StreamDataProvider> provider,
 	QPDFObjectHandle const& filter,
-	QPDFObjectHandle const& decode_parms,
-	size_t length);
+	QPDFObjectHandle const& decode_parms);
 
     // Replace object ID and generation.  This may only be called if
     // object ID and generation are 0.  It is used by QPDFObjectHandle