msi: Don't crash if record has no fields.

dlls/msi/format.c

@@ -626,8 +626,8 @@ UINT MSI_FormatRecordW( MSIPACKAGE* package, MSIRECORD* record, LPWSTR buffer,
 
     TRACE("(%s)\n",debugstr_w(rec));
 
-    len = deformat_string_internal(package,rec,&deformated,strlenW(rec),
-                                   record, NULL);
+    len = deformat_string_internal(package,rec,&deformated,
+                                   rec ? strlenW(rec) : 0, record, NULL);
 
     if (buffer)
     {

dlls/msi/tests/format.c

@@ -388,6 +388,17 @@ static void test_formatrecord(void)
     r = MsiFormatRecord(0, 0, NULL, NULL );
     ok( r == ERROR_INVALID_HANDLE, "wrong error\n");
 
+    hrec = MsiCreateRecord(0);
+    ok( hrec, "failed to create record\n");
+
+    /* format an empty record on a record with no parameters */
+    sz = sizeof(buffer);
+    r = MsiFormatRecordA(0, hrec, buffer, &sz );
+    ok( r == ERROR_SUCCESS, "format failed\n");
+    ok( sz == 0, "size wrong\n");
+
+    MsiCloseHandle( hrec );
+
     hrec = MsiCreateRecord(4);
     ok( hrec, "failed to create record\n");