Fixed a crash when loading/restoring a VST3's plug-in state in Cubase 9

modules/juce_audio_plugin_client/VST3/juce_VST3_Wrapper.cpp

@@ -1365,19 +1365,35 @@ public:
 
     bool readFromMemoryStream (IBStream* state)
     {
-        FUnknownPtr<MemoryStream> s (state);
+        FUnknownPtr<ISizeableStream> s (state);
+        Steinberg::int64 size = 0;
 
         if (s != nullptr
-             && s->getData() != nullptr
-             && s->getSize() > 0
-             && s->getSize() < 1024 * 1024 * 100) // (some hosts seem to return junk for the size)
+             && s->getStreamSize (size) == kResultOk
+             && size > 0
+             && size < 1024 * 1024 * 100) // (some hosts seem to return junk for the size)
         {
+            MemoryBlock block (static_cast<size_t> (size));
+
+            // turns out that Cubase 9 might give you the incorrect stream size :-(
+            Steinberg::int32 bytesRead = 1;
+            int len;
+
+            for (len = 0; bytesRead > 0 && len < static_cast<int> (block.getSize()); len += bytesRead)
+                if (state->read (block.getData(), static_cast<int32> (block.getSize()), &bytesRead) != kResultOk)
+                    break;
+
+            if (len == 0)
+                return false;
+
+            block.setSize (static_cast<size_t> (len));
+
             // Adobe Audition CS6 hack to avoid trying to use corrupted streams:
             if (getHostType().isAdobeAudition())
-                if (s->getSize() >= 5 && memcmp (s->getData(), "VC2!E", 5) == 0)
+                if (block.getSize() >= 5 && memcmp (block.getData(), "VC2!E", 5) == 0)
                     return false;
 
-            return loadStateData (s->getData(), (int) s->getSize());
+            return loadStateData (block.getData(), (int) block.getSize());
         }
 
         return false;