Throw OutOfSpaceException instead of IllegalArgumentException.

When a MessageNano containing a String is serialized into a buffer that
is too small to contain it, and the buffer's boundary happens to be
where the string field's length delimiting varint is serialized,
and the string's length and 3*length have the same length when
encoded as a varint, an IllegalArgumentException is thrown rather than
an OutOfSpaceException.

Github issue: https://github.com/google/protobuf/issues/292

Change-Id: If478d68cf15bfd0662252d008e42b2bf1ff1c75e

javanano/src/main/java/com/google/protobuf/nano/CodedOutputByteBufferNano.java

@@ -300,6 +300,12 @@ public final class CodedOutputByteBufferNano {
       final int maxLengthVarIntSize = computeRawVarint32Size(value.length() * MAX_UTF8_EXPANSION);
       if (minLengthVarIntSize == maxLengthVarIntSize) {
         int oldPosition = buffer.position();
+        // Buffer.position, when passed a position that is past its limit, throws
+        // IllegalArgumentException, and this class is documented to throw
+        // OutOfSpaceException instead.
+        if (buffer.remaining() < minLengthVarIntSize) {
+          throw new OutOfSpaceException(oldPosition + minLengthVarIntSize, buffer.limit());
+        }
         buffer.position(oldPosition + minLengthVarIntSize);
         encode(value, buffer);
         int newPosition = buffer.position();
@@ -311,7 +317,10 @@ public final class CodedOutputByteBufferNano {
         encode(value, buffer);
       }
     } catch (BufferOverflowException e) {
-      throw new OutOfSpaceException(buffer.position(), buffer.limit());
+      final OutOfSpaceException outOfSpaceException = new OutOfSpaceException(buffer.position(),
+          buffer.limit());
+      outOfSpaceException.initCause(e);
+      throw outOfSpaceException;
     }
   }
 

javanano/src/test/java/com/google/protobuf/nano/NanoTest.java

@@ -31,6 +31,7 @@
 package com.google.protobuf.nano;
 
 import com.google.protobuf.nano.MapTestProto.TestMap;
+import com.google.protobuf.nano.CodedOutputByteBufferNano;
 import com.google.protobuf.nano.MapTestProto.TestMap.MessageValue;
 import com.google.protobuf.nano.NanoAccessorsOuterClass.TestNanoAccessors;
 import com.google.protobuf.nano.NanoHasOuterClass.TestAllTypesNanoHas;
@@ -2322,6 +2323,23 @@ public class NanoTest extends TestCase {
     }
   }
 
+  /** Regression test for https://github.com/google/protobuf/issues/292 */
+  public void testCorrectExceptionThrowWhenEncodingStringsWithoutEnoughSpace() throws Exception {
+    String testCase = "Foooooooo";
+    assertEquals(CodedOutputByteBufferNano.computeRawVarint32Size(testCase.length()),
+            CodedOutputByteBufferNano.computeRawVarint32Size(testCase.length() * 3));
+    assertEquals(11, CodedOutputByteBufferNano.computeStringSize(1, testCase));
+    // Tag is one byte, varint describing string length is 1 byte, string length is 9 bytes.
+    // An array of size 1 will cause a failure when trying to write the varint.
+    for (int i = 0; i < 11; i++) {
+      CodedOutputByteBufferNano bufferNano = CodedOutputByteBufferNano.newInstance(new byte[i]);
+      try {
+        bufferNano.writeString(1, testCase);
+        fail("Should have thrown an out of space exception");
+      } catch (CodedOutputByteBufferNano.OutOfSpaceException expected) {}
+    }
+  }
+
   private void testEncodingOfString(char c, int length) throws InvalidProtocolBufferNanoException {
     TestAllTypesNano testAllTypesNano = new TestAllTypesNano();
     final String fullString = fullString(c, length);