diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index 2889877..c3e420e 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -15,8 +15,6 @@
 from ordereddict import OrderedDict
 from qapi import *
 import re
-import os
-import errno
 
 def generate_command_decl(name, args, ret_type):
     arglist=""
@@ -311,51 +309,18 @@ qapi_init(qmp_init_marshal);
                 registry=registry.rstrip())
     return ret
 
-def gen_command_decl_prologue(header, guard, prefix=""):
+def gen_command_decl_prologue(prefix=""):
     ret = mcgen('''
-/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
-
-/*
- * schema-defined QAPI function prototypes
- *
- * Copyright IBM, Corp. 2011
- *
- * Authors:
- *  Anthony Liguori   <aliguori@us.ibm.com>
- *
- * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
- * See the COPYING.LIB file in the top-level directory.
- *
- */
-
-#ifndef %(guard)s
-#define %(guard)s
-
 #include "%(prefix)sqapi-types.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/error.h"
 
 ''',
-                 header=basename(header), guard=guardname(header), prefix=prefix)
+                 prefix=prefix)
     return ret
 
 def gen_command_def_prologue(prefix="", proxy=False):
     ret = mcgen('''
-/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
-
-/*
- * schema-defined QMP->QAPI command dispatch
- *
- * Copyright IBM, Corp. 2011
- *
- * Authors:
- *  Anthony Liguori   <aliguori@us.ibm.com>
- *
- * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
- * See the COPYING.LIB file in the top-level directory.
- *
- */
-
 #include "qemu-common.h"
 #include "qemu/module.h"
 #include "qapi/qmp/qerror.h"
@@ -374,8 +339,6 @@ def gen_command_def_prologue(prefix="", proxy=False):
         ret += '#include "%sqmp-commands.h"' % prefix
     return ret + "\n\n"
 
-c_file = 'qmp-marshal.c'
-h_file = 'qmp-commands.h'
 middle_mode = False
 
 (input_file, output_dir, do_c, do_h, prefix, opts) = \
@@ -385,29 +348,44 @@ for o, a in opts:
     if o in ("-m", "--middle"):
         middle_mode = True
 
-c_file = output_dir + prefix + c_file
-h_file = output_dir + prefix + h_file
-
-def maybe_open(really, name, opt):
-    if really:
-        return open(name, opt)
-    else:
-        import StringIO
-        return StringIO.StringIO()
-
-try:
-    os.makedirs(output_dir)
-except os.error, e:
-    if e.errno != errno.EEXIST:
-        raise
-
 exprs = parse_schema(input_file)
 commands = filter(lambda expr: expr.has_key('command'), exprs)
 commands = filter(lambda expr: not expr.has_key('gen'), commands)
 
-fdecl = maybe_open(do_h, h_file, 'w')
-fdef = maybe_open(do_c, c_file, 'w')
-ret = gen_command_decl_prologue(header=basename(h_file), guard=guardname(h_file), prefix=prefix)
+c_comment = '''
+/*
+ * schema-defined QMP->QAPI command dispatch
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+'''
+h_comment = '''
+/*
+ * schema-defined QAPI function prototypes
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+'''
+
+(fdef, fdecl) = open_output(output_dir, do_c, do_h, prefix,
+                            'qmp-marshal.c', 'qmp-commands.h',
+                            c_comment, h_comment)
+
+ret = gen_command_decl_prologue(prefix=prefix)
 fdecl.write(ret)
 ret = gen_command_def_prologue(prefix=prefix)
 fdef.write(ret)
@@ -431,13 +409,8 @@ for cmd in commands:
     ret = gen_marshal_input(cmd['command'], arglist, ret_type, middle_mode) + "\n"
     fdef.write(ret)
 
-fdecl.write("\n#endif\n");
-
 if not middle_mode:
     ret = gen_registry(commands)
     fdef.write(ret)
 
-fdef.flush()
-fdef.close()
-fdecl.flush()
-fdecl.close()
+close_output(fdef, fdecl)
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index bc5ca4a..56bc602 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -11,8 +11,6 @@
 
 from ordereddict import OrderedDict
 from qapi import *
-import os
-import errno
 
 def _generate_event_api_name(event_name, params):
     api_name = "void qapi_event_send_%s(" % c_name(event_name).lower();
@@ -214,36 +212,9 @@ const char *%(event_enum_name)s_lookup[] = {
 ''')
     return ret
 
-
-# Start the real job
-
-c_file = 'qapi-event.c'
-h_file = 'qapi-event.h'
-
 (input_file, output_dir, do_c, do_h, prefix, dummy) = parse_command_line()
 
-c_file = output_dir + prefix + c_file
-h_file = output_dir + prefix + h_file
-
-try:
-    os.makedirs(output_dir)
-except os.error, e:
-    if e.errno != errno.EEXIST:
-        raise
-
-def maybe_open(really, name, opt):
-    if really:
-        return open(name, opt)
-    else:
-        import StringIO
-        return StringIO.StringIO()
-
-fdef = maybe_open(do_c, c_file, 'w')
-fdecl = maybe_open(do_h, h_file, 'w')
-
-fdef.write(mcgen('''
-/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
-
+c_comment = '''
 /*
  * schema-defined QAPI event functions
  *
@@ -256,41 +227,43 @@ fdef.write(mcgen('''
  * See the COPYING.LIB file in the top-level directory.
  *
  */
+'''
+h_comment = '''
+/*
+ * schema-defined QAPI event functions
+ *
+ * Copyright (c) 2014 Wenchao Xia
+ *
+ * Authors:
+ *  Wenchao Xia  <wenchaoqemu@gmail.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+'''
 
+(fdef, fdecl) = open_output(output_dir, do_c, do_h, prefix,
+                            'qapi-event.c', 'qapi-event.h',
+                            c_comment, h_comment)
+
+fdef.write(mcgen('''
 #include "qemu-common.h"
-#include "%(header)s"
+#include "%(prefix)sqapi-event.h"
 #include "%(prefix)sqapi-visit.h"
 #include "qapi/qmp-output-visitor.h"
 #include "qapi/qmp-event.h"
 
 ''',
-                 prefix=prefix, header=basename(h_file)))
+                 prefix=prefix))
 
 fdecl.write(mcgen('''
-/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
-
-/*
- * schema-defined QAPI event functions
- *
- * Copyright (c) 2014 Wenchao Xia
- *
- * Authors:
- *  Wenchao Xia  <wenchaoqemu@gmail.com>
- *
- * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
- * See the COPYING.LIB file in the top-level directory.
- *
- */
-
-#ifndef %(guard)s
-#define %(guard)s
-
 #include "qapi/error.h"
 #include "qapi/qmp/qdict.h"
 #include "%(prefix)sqapi-types.h"
 
 ''',
-                  prefix=prefix, guard=guardname(h_file)))
+                  prefix=prefix))
 
 exprs = parse_schema(input_file)
 
@@ -323,12 +296,4 @@ fdecl.write(ret)
 ret = generate_event_enum_lookup(event_enum_name, event_enum_strings)
 fdef.write(ret)
 
-fdecl.write('''
-#endif
-''')
-
-fdecl.flush()
-fdecl.close()
-
-fdef.flush()
-fdef.close()
+close_output(fdef, fdecl)
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index 62044c1..6bd0b13 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -11,8 +11,6 @@
 
 from ordereddict import OrderedDict
 from qapi import *
-import os
-import errno
 
 def generate_fwd_struct(name, members, builtin_type=False):
     if builtin_type:
@@ -273,8 +271,6 @@ void qapi_free_%(name)s(%(c_type)s obj)
                 c_type=c_type(name), name=c_name(name))
     return ret
 
-c_file = 'qapi-types.c'
-h_file = 'qapi-types.h'
 do_builtins = False
 
 (input_file, output_dir, do_c, do_h, prefix, opts) = \
@@ -284,28 +280,7 @@ for o, a in opts:
     if o in ("-b", "--builtins"):
         do_builtins = True
 
-c_file = output_dir + prefix + c_file
-h_file = output_dir + prefix + h_file
-
-try:
-    os.makedirs(output_dir)
-except os.error, e:
-    if e.errno != errno.EEXIST:
-        raise
-
-def maybe_open(really, name, opt):
-    if really:
-        return open(name, opt)
-    else:
-        import StringIO
-        return StringIO.StringIO()
-
-fdef = maybe_open(do_c, c_file, 'w')
-fdecl = maybe_open(do_h, h_file, 'w')
-
-fdef.write(mcgen('''
-/* AUTOMATICALLY GENERATED, DO NOT MODIFY */
-
+c_comment = '''
 /*
  * deallocation functions for schema-defined QAPI types
  *
@@ -319,37 +294,39 @@ fdef.write(mcgen('''
  * See the COPYING.LIB file in the top-level directory.
  *
  */
+'''
+h_comment = '''
+/*
+ * schema-defined QAPI types
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+'''
 
+(fdef, fdecl) = open_output(output_dir, do_c, do_h, prefix,
+                            'qapi-types.c', 'qapi-types.h',
+                            c_comment, h_comment)
+
+fdef.write(mcgen('''
 #include "qapi/dealloc-visitor.h"
 #include "%(prefix)sqapi-types.h"
 #include "%(prefix)sqapi-visit.h"
 
-''',             prefix=prefix))
+''',
+                 prefix=prefix))
 
 fdecl.write(mcgen('''
-/* AUTOMATICALLY GENERATED, DO NOT MODIFY */
-
-/*
- * schema-defined QAPI types
- *
- * Copyright IBM, Corp. 2011
- *
- * Authors:
- *  Anthony Liguori   <aliguori@us.ibm.com>
- *
- * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
- * See the COPYING.LIB file in the top-level directory.
- *
- */
-
-#ifndef %(guard)s
-#define %(guard)s
-
 #include <stdbool.h>
 #include <stdint.h>
 
-''',
-                  guard=guardname(h_file)))
+'''))
 
 exprs = parse_schema(input_file)
 exprs = filter(lambda expr: not expr.has_key('gen'), exprs)
@@ -427,12 +404,4 @@ for expr in exprs:
         continue
     fdecl.write(ret)
 
-fdecl.write('''
-#endif
-''')
-
-fdecl.flush()
-fdecl.close()
-
-fdef.flush()
-fdef.close()
+close_output(fdef, fdecl)
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index f3e31cc..ba4be8d 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -15,8 +15,6 @@
 from ordereddict import OrderedDict
 from qapi import *
 import re
-import os
-import errno
 
 implicit_structs = []
 
@@ -375,8 +373,6 @@ void visit_type_%(name)s(Visitor *m, %(name)s *obj, const char *name, Error **er
 ''',
                  name=c_name(name))
 
-c_file = 'qapi-visit.c'
-h_file = 'qapi-visit.h'
 do_builtins = False
 
 (input_file, output_dir, do_c, do_h, prefix, opts) = \
@@ -386,70 +382,51 @@ for o, a in opts:
     if o in ("-b", "--builtins"):
         do_builtins = True
 
-c_file = output_dir + prefix + c_file
-h_file = output_dir + prefix + h_file
+c_comment = '''
+/*
+ * schema-defined QAPI visitor functions
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+'''
+h_comment = '''
+/*
+ * schema-defined QAPI visitor functions
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+'''
 
-try:
-    os.makedirs(output_dir)
-except os.error, e:
-    if e.errno != errno.EEXIST:
-        raise
-
-def maybe_open(really, name, opt):
-    if really:
-        return open(name, opt)
-    else:
-        import StringIO
-        return StringIO.StringIO()
-
-fdef = maybe_open(do_c, c_file, 'w')
-fdecl = maybe_open(do_h, h_file, 'w')
+(fdef, fdecl) = open_output(output_dir, do_c, do_h, prefix,
+                            'qapi-visit.c', 'qapi-visit.h',
+                            c_comment, h_comment)
 
 fdef.write(mcgen('''
-/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
-
-/*
- * schema-defined QAPI visitor functions
- *
- * Copyright IBM, Corp. 2011
- *
- * Authors:
- *  Anthony Liguori   <aliguori@us.ibm.com>
- *
- * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
- * See the COPYING.LIB file in the top-level directory.
- *
- */
-
 #include "qemu-common.h"
-#include "%(header)s"
+#include "%(prefix)sqapi-visit.h"
 ''',
-                 header=basename(h_file)))
+                 prefix = prefix))
 
 fdecl.write(mcgen('''
-/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
-
-/*
- * schema-defined QAPI visitor functions
- *
- * Copyright IBM, Corp. 2011
- *
- * Authors:
- *  Anthony Liguori   <aliguori@us.ibm.com>
- *
- * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
- * See the COPYING.LIB file in the top-level directory.
- *
- */
-
-#ifndef %(guard)s
-#define %(guard)s
-
 #include "qapi/visitor.h"
 #include "%(prefix)sqapi-types.h"
 
 ''',
-                  prefix=prefix, guard=guardname(h_file)))
+                  prefix=prefix))
 
 exprs = parse_schema(input_file)
 
@@ -505,12 +482,4 @@ for expr in exprs:
         ret += generate_enum_declaration(expr['enum'], expr['data'])
         fdecl.write(ret)
 
-fdecl.write('''
-#endif
-''')
-
-fdecl.flush()
-fdecl.close()
-
-fdef.flush()
-fdef.close()
+close_output(fdef, fdecl)
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 79d1e52..1f68fa9 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -13,6 +13,7 @@
 
 import re
 from ordereddict import OrderedDict
+import errno
 import getopt
 import os
 import sys
@@ -1002,3 +1003,52 @@ def parse_command_line(extra_options = "", extra_long_options = []):
     input_file = args[0]
 
     return (input_file, output_dir, do_c, do_h, prefix, extra_opts)
+
+def open_output(output_dir, do_c, do_h, prefix, c_file, h_file,
+                c_comment, h_comment):
+    c_file = output_dir + prefix + c_file
+    h_file = output_dir + prefix + h_file
+
+    try:
+        os.makedirs(output_dir)
+    except os.error, e:
+        if e.errno != errno.EEXIST:
+            raise
+
+    def maybe_open(really, name, opt):
+        if really:
+            return open(name, opt)
+        else:
+            import StringIO
+            return StringIO.StringIO()
+
+    fdef = maybe_open(do_c, c_file, 'w')
+    fdecl = maybe_open(do_h, h_file, 'w')
+
+    fdef.write(mcgen('''
+/* AUTOMATICALLY GENERATED, DO NOT MODIFY */
+%(comment)s
+''',
+                     comment = c_comment))
+
+    fdecl.write(mcgen('''
+/* AUTOMATICALLY GENERATED, DO NOT MODIFY */
+%(comment)s
+#ifndef %(guard)s
+#define %(guard)s
+
+''',
+                      comment = h_comment, guard = guardname(h_file)))
+
+    return (fdef, fdecl)
+
+def close_output(fdef, fdecl):
+    fdecl.write('''
+#endif
+''')
+
+    fdecl.flush()
+    fdecl.close()
+
+    fdef.flush()
+    fdef.close()
