Enhancements to ParserCallbacks

ChangeLog

@@ -1,5 +1,9 @@
 2021-03-01  Jay Berkenbilt  <ejb@ql.org>
 
+	* QPDFObjectHandle::ParserCallbacks: add virtual handleWarning
+	method, and provide default (empty) implementation of it and
+	handleEOF().
+
 	* Add QPDF::numWarnings() -- useful to tell whether any warnings
 	were issued by a specific bit of code.
 

include/qpdf/QPDFObjectHandle.hh

@@ -224,7 +224,16 @@ class QPDFObjectHandle
         virtual void handleObject(
             QPDFObjectHandle, size_t offset, size_t length);
 
-        virtual void handleEOF() = 0;
+        // handleWarning is called if a warning was issued during the
+        // parsing of the most recent object. There's no good way to
+        // get information about the warning, but implementors can use
+        // this to become aware that there was some problem while
+        // parsing this content stream.
+        QPDF_DLL
+        virtual void handleWarning();
+
+        QPDF_DLL
+        virtual void handleEOF();
 
         // Override this if you want to know the full size of the
         // contents, possibly after concatenation of multiple streams.

libqpdf/QPDFObjectHandle.cc

@@ -151,6 +151,16 @@ QPDFObjectHandle::ParserCallbacks::handleObject(
     handleObject(oh);
 }
 
+void
+QPDFObjectHandle::ParserCallbacks::handleWarning()
+{
+}
+
+void
+QPDFObjectHandle::ParserCallbacks::handleEOF()
+{
+}
+
 void
 QPDFObjectHandle::ParserCallbacks::contentSize(size_t)
 {
@@ -1847,10 +1857,15 @@ QPDFObjectHandle::parseContentStream_internal(
     pipeContentStreams(&buf, description, all_description);
     PointerHolder<Buffer> stream_data = buf.getBuffer();
     callbacks->contentSize(stream_data->getSize());
+    QPDF* context = getOwningQPDF();
+    if ((! context) && isArray() && (getArrayNItems() > 0))
+    {
+        context = getArrayItem(0).getOwningQPDF();
+    }
     try
     {
         parseContentStream_data(stream_data, all_description,
-                                callbacks, getOwningQPDF());
+                                callbacks, context);
     }
     catch (TerminateParsing&)
     {
@@ -1881,9 +1896,15 @@ QPDFObjectHandle::parseContentStream_data(
         tokenizer.readToken(input, "content", true);
         qpdf_offset_t offset = input->getLastOffset();
         input->seek(offset, SEEK_SET);
+        size_t before_nwarnings = (context ? context->numWarnings() : 0);
         QPDFObjectHandle obj =
             parseInternal(input, "content", tokenizer,
                           empty, 0, context, true);
+        size_t after_nwarnings = (context ? context->numWarnings() : 0);
+        if (after_nwarnings > before_nwarnings)
+        {
+            callbacks->handleWarning();
+        }
         if (! obj.isInitialized())
         {
             // EOF
@@ -1910,6 +1931,7 @@ QPDFObjectHandle::parseContentStream_data(
                      QPDFExc(qpdf_e_damaged_pdf, input->getName(),
                              "stream data", input->tell(),
                              "EOF found while reading inline image"));
+                callbacks->handleWarning();
             }
             else
             {