qapi: Share gen_err_check()

qapi-commands has a nice helper gen_err_check(), but did not
use it everywhere. In fact, using it in more places makes it
easier to reduce the lines of code used for generating error
checks.  This in turn will make it easier for later patches
to consolidate another common pattern among the generators.

The generated code has fewer blank lines in qapi-event.c functions,
but has no semantic difference.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1443565276-4535-16-git-send-email-eblake@redhat.com>
[Drop another blank line for symmetry]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

4 files changed, 20 insertions, 33 deletions

diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index 267991ed8b..4e99c1de8b 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -25,17 +25,6 @@ def gen_command_decl(name, arg_type, ret_type):
                  params=gen_params(arg_type, 'Error **errp'))
 
 
-def gen_err_check(err):
-    if not err:
-        return ''
-    return mcgen('''
-    if (%(err)s) {
-        goto out;
-    }
-''',
-                 err=err)
-
-
 def gen_call(name, arg_type, ret_type):
     ret = ''
 
@@ -56,7 +45,7 @@ def gen_call(name, arg_type, ret_type):
 ''',
                 c_name=c_name(name), args=argstr, lhs=lhs)
     if ret_type:
-        ret += gen_err_check('err')
+        ret += gen_err_check()
         ret += mcgen('''
 
     qmp_marshal_output_%(c_name)s(retval, ret, &err);
@@ -133,7 +122,7 @@ def gen_marshal_input_visit(arg_type, dealloc=False):
 ''',
                          c_name=c_name(memb.name), name=memb.name,
                          errp=errparg)
-            ret += gen_err_check(errarg)
+            ret += gen_err_check(err=errarg)
             ret += mcgen('''
     if (has_%(c_name)s) {
 ''',
@@ -144,7 +133,7 @@ def gen_marshal_input_visit(arg_type, dealloc=False):
 ''',
                      c_name=c_name(memb.name), name=memb.name,
                      c_type=memb.type.c_name(), errp=errparg)
-        ret += gen_err_check(errarg)
+        ret += gen_err_check(err=errarg)
         if memb.optional:
             pop_indent()
             ret += mcgen('''
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index b5a9d4f364..eaaac05154 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -68,12 +68,9 @@ def gen_event_send(name, arg_type):
 
     /* Fake visit, as if all members are under a structure */
     visit_start_struct(v, NULL, "", "%(name)s", 0, &err);
-    if (err) {
-        goto out;
-    }
-
 ''',
                      name=name)
+        ret += gen_err_check()
 
         for memb in arg_type.members:
             if memb.optional:
@@ -91,14 +88,12 @@ def gen_event_send(name, arg_type):
 
             ret += mcgen('''
     visit_type_%(c_type)s(v, %(cast)s&%(c_name)s, "%(name)s", &err);
-    if (err) {
-        goto out;
-    }
 ''',
                          cast=cast,
                          c_name=c_name(memb.name),
                          c_type=memb.type.c_name(),
                          name=memb.name)
+            ret += gen_err_check()
 
             if memb.optional:
                 pop_indent()
@@ -107,7 +102,6 @@ def gen_event_send(name, arg_type):
 ''')
 
         ret += mcgen('''
-
     visit_end_struct(v, &err);
     if (err) {
         goto out;
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 78ad5560d0..bc6911f8fe 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -81,11 +81,9 @@ static void visit_type_%(c_name)s_fields(Visitor *v, %(c_name)s **obj, Error **e
     if base:
         ret += mcgen('''
     visit_type_implicit_%(c_type)s(v, &(*obj)->%(c_name)s, &err);
-    if (err) {
-        goto out;
-    }
 ''',
                      c_type=base.c_name(), c_name=c_name('base'))
+        ret += gen_err_check()
 
     for memb in members:
         if memb.optional:
@@ -107,11 +105,7 @@ static void visit_type_%(c_name)s_fields(Visitor *v, %(c_name)s **obj, Error **e
             ret += mcgen('''
     }
 ''')
-        ret += mcgen('''
-    if (err) {
-        goto out;
-    }
-''')
+        ret += gen_err_check()
 
     if re.search('^ *goto out;', ret, re.MULTILINE):
         ret += mcgen('''
@@ -271,11 +265,9 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error
     if base:
         ret += mcgen('''
     visit_type_%(c_name)s_fields(v, obj, &err);
-    if (err) {
-        goto out_obj;
-    }
 ''',
                      c_name=c_name(name))
+        ret += gen_err_check(label='out_obj')
 
     tag_key = variants.tag_member.name
     if not variants.tag_name:
diff --git a/scripts/qapi.py b/scripts/qapi.py
index c0728d73e1..62a415ccd9 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1536,6 +1536,18 @@ def gen_params(arg_type, extra):
         ret += sep + extra
     return ret
 
+
+def gen_err_check(err='err', label='out'):
+    if not err:
+        return ''
+    return mcgen('''
+    if (%(err)s) {
+        goto %(label)s;
+    }
+''',
+                 err=err, label=label)
+
+
 #
 # Common command line parsing
 #