Fix issue FasterXML#54

protobuf/src/main/java/com/fasterxml/jackson/dataformat/protobuf/ByteAccumulator.java

@@ -29,20 +29,22 @@ public class ByteAccumulator
     protected Segment _firstSegment, _lastSegment;
 
     protected int _segmentBytes;
+
+    // used to cache start pointer for nested message's parent
+    protected int _parentStart = 0;
 
     public ByteAccumulator(ByteAccumulator p, int typedTag,
-            byte[] prefixBuffer, int prefixOffset)
+            byte[] prefixBuffer, int prefixOffset, int parentStart)
     {
-        _parent = p;
-        _typedTag = typedTag;
-        _prefixBuffer = prefixBuffer;
-        _prefixOffset = prefixOffset;
+    	this(p, typedTag, prefixBuffer, prefixOffset);
+    	this._parentStart = parentStart;
     }
 
-    public ByteAccumulator(ByteAccumulator p,
-            byte[] prefixBuffer, int prefixOffset) {
+    public ByteAccumulator(ByteAccumulator p, int typedTag,
+            byte[] prefixBuffer, int prefixOffset)
+    {
         _parent = p;
-        _typedTag = -1;
+        _typedTag = typedTag;
         _prefixBuffer = prefixBuffer;
         _prefixOffset = prefixOffset;
     }

protobuf/src/main/java/com/fasterxml/jackson/dataformat/protobuf/ProtobufGenerator.java

@@ -1709,8 +1709,8 @@ private final void _startBuffering(int typedTag) throws IOException
                 _output.write(_currBuffer, start, len);
             }
         }
+        _buffered = new ByteAccumulator(_buffered, typedTag, _currBuffer, ptr, _currStart);
         _currStart = _currPtr = ptr + 10;
-        _buffered = new ByteAccumulator(_buffered, typedTag, _currBuffer, ptr);
     }
 
     /**
@@ -1735,8 +1735,8 @@ private final void _startBuffering() throws IOException
             }
         }
 
+        _buffered = new ByteAccumulator(_buffered, -1, _currBuffer, ptr, _currStart);
         _currStart = _currPtr = ptr + 5;
-        _buffered = new ByteAccumulator(_buffered, _currBuffer, ptr);
     }
 
     private final void _finishBuffering() throws IOException
@@ -1745,13 +1745,17 @@ private final void _finishBuffering() throws IOException
         final int currLen = _currPtr - start;
 
         ByteAccumulator acc = _buffered;
+        final ByteAccumulator child = _buffered;
         acc = acc.finish(_output, _currBuffer, start, currLen);
         _buffered = acc;
         if (acc == null) {
             _currStart = 0;
             _currPtr = 0;
         } else {
-            _currStart = _currPtr;
+            _currStart = child._parentStart;
+            _currPtr = child._prefixOffset;
+            // need to reallocate buffer, otherwise will overwrite
+            _ensureMore();
         }
     }
 

protobuf/src/test/java/com/fasterxml/jackson/dataformat/protobuf/NestedMessages.java

@@ -0,0 +1,131 @@
+package com.fasterxml.jackson.dataformat.protobuf;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.fasterxml.jackson.databind.ObjectReader;
+import com.fasterxml.jackson.databind.ObjectWriter;
+import com.fasterxml.jackson.dataformat.protobuf.ProtobufMapper;
+import com.fasterxml.jackson.dataformat.protobuf.schema.ProtobufSchema;
+import com.fasterxml.jackson.dataformat.protobuf.schema.ProtobufSchemaLoader;
+
+public class NestedMessages {
+
+	private static final String PROTO = //
+			"message TestObject {\n" + //
+					"optional string a = 1;\n" + //
+					"optional TestSub b = 2;\n" + //
+					"}\n" + //
+					"message TestSub {;\n" + //
+					"optional string c = 2;\n" + //
+					"optional string b = 3;\n" + //
+					"optional TestSubSub d = 4;\n" + //
+					"}\n" + //
+					"message TestSubSub {;\n" + //
+					"optional string a = 1;\n" + //
+					"}\n"; //
+
+	public static class TestObject {
+		String a;
+		TestSub b;
+
+		public String getA() {
+			return a;
+		}
+
+		public void setA(String a) {
+			this.a = a;
+		}
+
+		public TestSub getB() {
+			return b;
+		}
+
+		public void setB(TestSub b) {
+			this.b = b;
+		}
+
+		// The following annotation to force "d" as first field is needed before
+		// the fix
+		// @JsonPropertyOrder(value={"d", "b", "c"})
+		public static class TestSub {
+			String b;
+			String c;
+			TestSubSub d;
+
+			public String getB() {
+				return b;
+			}
+
+			public void setB(String b) {
+				this.b = b;
+			}
+
+			public String getC() {
+				return c;
+			}
+
+			public void setC(String c) {
+				this.c = c;
+			}
+
+			public TestSubSub getD() {
+				return d;
+			}
+
+			public void setD(TestSubSub d) {
+				this.d = d;
+			}
+
+			public static class TestSubSub {
+				String a;
+
+				public String getA() {
+					return a;
+				}
+
+				public void setA(String a) {
+					this.a = a;
+				}
+			}
+		}
+	}
+
+	@Test
+	public void testProto() throws IOException {
+
+		TestObject testClass = new TestObject();
+		ProtobufMapper om = new ProtobufMapper();
+		ProtobufSchema s = ProtobufSchemaLoader.std.load(new ByteArrayInputStream(PROTO.getBytes()));
+		ObjectReader r = om.readerFor(TestObject.class).with(s);
+		ObjectWriter w = om.writer(s);
+		ByteArrayOutputStream out = new ByteArrayOutputStream() {
+			@Override
+			public synchronized void write(byte[] b, int off, int len) {
+				super.write(b, off, len);
+				System.out.println("Off " + off + " len " + len);
+			}
+		};
+		testClass.a = "value";
+		testClass.b = new TestObject.TestSub();
+		testClass.b.b = "value-b";
+		testClass.b.c = "valc";
+		// if this following row is commented out, test succeeds with old code
+		testClass.b.d = new TestObject.TestSub.TestSubSub();
+		testClass.b.d.a = "a-value!";
+
+		w.writeValue(out, testClass);
+		System.out.println("Size: " + out.size());
+
+		TestObject res = r.readValue(out.toByteArray());
+
+		Assert.assertEquals("value", res.a);
+		Assert.assertEquals("valc", res.b.c);
+		Assert.assertEquals("value-b", res.b.b);
+	}
+
+}