fix copying to not overwrite before offset

capnproto · Oct 22, 2024 · 08009f3 · 08009f3
1 parent c9e4512
commit 08009f3
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/runtime/src/main/java/org/capnproto/WireHelpers.java b/runtime/src/main/java/org/capnproto/WireHelpers.java
@@ -850,7 +850,14 @@ static Data.Builder setDataPointer(int refOffset,
                                        SegmentBuilder segment,
                                        Data.Reader value) {
         Data.Builder builder = initDataPointer(refOffset, segment, value.size);
+        int originalSrcPosition = value.buffer.position();
+        int originalDstPosition = builder.buffer.position();
+        builder.buffer.position(builder.offset);
+        //# copy from src offset until src end
         builder.buffer.put(value.buffer);
+        //# restore original positions
+        builder.buffer.position(originalDstPosition);
+        value.buffer.position(originalSrcPosition);
         return builder;
     }