WT-3333 Fixes for zero length strings packed/unpacked in a 'u' format via Python. (#3432)

3 files changed, 50 insertions, 1 deletions

diff --git a/lang/python/wiredtiger/packing.py b/lang/python/wiredtiger/packing.py
index 0506f2afda9..fb674538b76 100644
--- a/lang/python/wiredtiger/packing.py
+++ b/lang/python/wiredtiger/packing.py
@@ -94,6 +94,9 @@ def unpack(fmt, s):
                 elif f == 'S':
                     size = s.find('\0')
                 elif f == 'u' and offset == len(fmt) - 1:
+                    # A WT_ITEM with a NULL data field will be appear as None.
+                    if s == None:
+                        s = ''
                     size = len(s)
                 else:
                     # Note: 'U' is used internally, and may be exposed to us.
@@ -169,7 +172,7 @@ def pack(fmt, *values):
                 result += val[:l]
             if f == 'S' and not havesize:
                 result += '\0'
-            elif size > l:
+            elif size > l and havesize:
                 result += '\0' * (size - l)
         elif f in 't':
             # bit type, size is number of bits
diff --git a/test/java/com/wiredtiger/test/PackTest.java b/test/java/com/wiredtiger/test/PackTest.java
index a162fdfd0f0..302313169cd 100644
--- a/test/java/com/wiredtiger/test/PackTest.java
+++ b/test/java/com/wiredtiger/test/PackTest.java
@@ -184,6 +184,47 @@ public class PackTest {
     }
 
     @Test
+    public void pack08()
+    throws WiredTigerPackingException {
+        String format = "u";
+        PackOutputStream packer = new PackOutputStream(format);
+        PackInputStream unpacker;
+        byte[] b0 = {};
+        byte[] b1 = { 0x00 };
+        byte[] packed;
+
+        packer.addByteArray(b0);
+        packed = packer.getValue();
+        unpacker = new PackInputStream(format, packed);
+        Assert.assertTrue(java.util.Arrays.equals(
+                              unpacker.getByteArray(), b0));
+
+        packer = new PackOutputStream(format);
+        packer.addByteArray(b1);
+        packed = packer.getValue();
+        unpacker = new PackInputStream(format, packed);
+        Assert.assertTrue(java.util.Arrays.equals(
+                              unpacker.getByteArray(), b1));
+
+        format = "uu";
+        for (int i = 0; i < 2; i++) {
+            byte[] arg0 = (i == 0 ? b0 : b1);
+            for (int j = 0; j < 2; j++) {
+                byte[] arg1 = (j == 0 ? b0 : b1);
+                packer = new PackOutputStream(format);
+                packer.addByteArray(arg0);
+                packer.addByteArray(arg1);
+                packed = packer.getValue();
+                unpacker = new PackInputStream(format, packed);
+                Assert.assertTrue(java.util.Arrays.equals(
+                                      unpacker.getByteArray(), arg0));
+                Assert.assertTrue(java.util.Arrays.equals(
+                                      unpacker.getByteArray(), arg1));
+            }
+        }
+    }
+
+    @Test
     public void packUnpackNumber01()
     throws WiredTigerPackingException {
         // Verify that we can pack and unpack single signed longs.
diff --git a/test/suite/test_pack.py b/test/suite/test_pack.py
index 951c0b0da20..a24ef4fdfe1 100644
--- a/test/suite/test_pack.py
+++ b/test/suite/test_pack.py
@@ -95,6 +95,11 @@ class test_pack(wttest.WiredTigerTestCase):
         self.check('3u', r"\x4")
         self.check('3uu', r"\x4", r"\x42" * 10)
         self.check('u3u', r"\x42" * 10, r"\x4")
+        self.check('u', '\x00')
+        self.check('u', '')
+        self.check('uu', '', '\x00')
+        self.check('uu', '\x00', '')
+        self.check('uu', '', '')
 
         self.check('s', "4")
         self.check("1s", "4")