Bug fix: CDataStream::GetAndClear() when nReadPos > 0

Changed CDataStream::GetAndClear() to use the most obvious
get get and clear instead of a tricky swap().

Added a unit test for CDataStream insert/erase/GetAndClear.

Note: GetAndClear() is not performance critical, it is used only
by the send-a-message-to-the-network code. Bug was not noticed
before now because the send-a-message code never erased from the
stream.

src/serialize.h

@@ -1104,8 +1104,8 @@ class CDataStream
     }
 
     void GetAndClear(CSerializeData &data) {
-        vch.swap(data);
-        CSerializeData().swap(vch);
+        data.insert(data.end(), begin(), end());
+        clear();
     }
 };
 

src/test/serialize_tests.cpp

@@ -102,4 +102,52 @@ BOOST_AUTO_TEST_CASE(noncanonical)
     BOOST_CHECK_EXCEPTION(ReadCompactSize(ss), std::ios_base::failure, isCanonicalException);
 }
 
+BOOST_AUTO_TEST_CASE(insert_delete)
+{
+    // Test inserting/deleting bytes.
+    CDataStream ss(SER_DISK, 0);
+    BOOST_CHECK_EQUAL(ss.size(), 0);
+
+    ss.write("\x00\x01\x02\xff", 4);
+    BOOST_CHECK_EQUAL(ss.size(), 4);
+
+    char c = (char)11;
+
+    // Inserting at beginning/end/middle:
+    ss.insert(ss.begin(), c);
+    BOOST_CHECK_EQUAL(ss.size(), 5);
+    BOOST_CHECK_EQUAL(ss[0], c);
+    BOOST_CHECK_EQUAL(ss[1], 0);
+
+    ss.insert(ss.end(), c);
+    BOOST_CHECK_EQUAL(ss.size(), 6);
+    BOOST_CHECK_EQUAL(ss[4], (char)0xff);
+    BOOST_CHECK_EQUAL(ss[5], c);
+
+    ss.insert(ss.begin()+2, c);
+    BOOST_CHECK_EQUAL(ss.size(), 7);
+    BOOST_CHECK_EQUAL(ss[2], c);
+
+    // Delete at beginning/end/middle
+    ss.erase(ss.begin());
+    BOOST_CHECK_EQUAL(ss.size(), 6);
+    BOOST_CHECK_EQUAL(ss[0], 0);
+
+    ss.erase(ss.begin()+ss.size()-1);
+    BOOST_CHECK_EQUAL(ss.size(), 5);
+    BOOST_CHECK_EQUAL(ss[4], (char)0xff);
+
+    ss.erase(ss.begin()+1);
+    BOOST_CHECK_EQUAL(ss.size(), 4);
+    BOOST_CHECK_EQUAL(ss[0], 0);
+    BOOST_CHECK_EQUAL(ss[1], 1);
+    BOOST_CHECK_EQUAL(ss[2], 2);
+    BOOST_CHECK_EQUAL(ss[3], (char)0xff);
+
+    // Make sure GetAndClear does the right thing:
+    CSerializeData d;
+    ss.GetAndClear(d);
+    BOOST_CHECK_EQUAL(ss.size(), 0);
+}
+
 BOOST_AUTO_TEST_SUITE_END()