[Qemu-devel] [RFC PATCH v7 18/18] qapi: Use gen_err_check() in more places

[Eric Blake]

Controversial: find all remaining patterns that generate a
goto statement due to 'err', and convert them to use
gen_err_check().  The bulk of these replacements actually
lead to code duplication (extra mcgen() calls with common
parameterization), so I will probably drop this patch.

Signed-off-by: Eric Blake <address@hidden>

---
v7: split off of 15/16, for discussion purposes
v6: new, split off of 10/46, add label parameter, and catch more
instances that could use it
---
 scripts/qapi-commands.py | 12 ++++++-----
 scripts/qapi-event.py    |  6 +++---
 scripts/qapi-visit.py    | 55 +++++++++++++++++++++++++++---------------------
 3 files changed, 41 insertions(+), 32 deletions(-)

diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index 43a893b..6994329 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -121,7 +121,7 @@ def gen_marshal_input_visit(arg_type, dealloc=False):


 def gen_marshal_output(ret_type):
-    return mcgen('''
+    ret = mcgen('''

 static void qmp_marshal_output_%(c_name)s(%(c_type)s ret_in, QObject 
**ret_out, Error **errp)
 {
@@ -132,9 +132,10 @@ static void qmp_marshal_output_%(c_name)s(%(c_type)s 
ret_in, QObject **ret_out,

     v = qmp_output_get_visitor(qov);
     visit_type_%(c_name)s(v, &ret_in, "unused", &err);
-    if (err) {
-        goto out;
-    }
+''',
+                c_type=ret_type.c_type(), c_name=ret_type.c_name())
+    ret += gen_err_check()
+    ret += mcgen('''
     *ret_out = qmp_output_get_qobject(qov);

 out:
@@ -146,7 +147,8 @@ out:
     qapi_dealloc_visitor_cleanup(qdv);
 }
 ''',
-                 c_type=ret_type.c_type(), c_name=ret_type.c_name())
+                 c_name=ret_type.c_name())
+    return ret


 def gen_marshal_proto(name):
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index b5e4d59..8eb353e 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -75,9 +75,9 @@ def gen_event_send(name, arg_type):
         ret += mcgen('''

     visit_end_struct(v, &err);
-    if (err) {
-        goto out;
-    }
+''')
+        ret += gen_err_check()
+        ret += mcgen('''

     obj = qmp_output_get_qobject(qov);
     g_assert(obj != NULL);
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 4f97781..46c4d56 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -128,7 +128,7 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, 
const char *name, Error


 def gen_visit_list(name, element_type):
-    return mcgen('''
+    ret = mcgen('''

 void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, 
Error **errp)
 {
@@ -136,9 +136,10 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, 
const char *name, Error
     GenericList *i, **prev;

     visit_start_list(v, name, &err);
-    if (err) {
-        goto out;
-    }
+''',
+                c_name=c_name(name), c_elt_type=element_type.c_name())
+    ret += gen_err_check()
+    ret += mcgen('''

     for (prev = (GenericList **)obj;
          !err && (i = visit_next_list(v, prev, &err)) != NULL;
@@ -155,6 +156,7 @@ out:
 }
 ''',
                  c_name=c_name(name), c_elt_type=element_type.c_name())
+    return ret


 def gen_visit_enum(name):
@@ -176,16 +178,17 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, 
const char *name, Error
     Error *err = NULL;

     visit_start_implicit_struct(v, (void**) obj, sizeof(%(c_name)s), &err);
-    if (err) {
-        goto out;
-    }
+''',
+                c_name=c_name(name))
+    ret += gen_err_check()
+    ret += mcgen('''
     visit_get_next_type(v, (int*) &(*obj)->kind, %(c_name)s_qtypes, name, 
&err);
-    if (err) {
-        goto out_obj;
-    }
+''',
+                 c_name=c_name(name))
+    ret += gen_err_check(label='out_obj')
+    ret += mcgen('''
     switch ((*obj)->kind) {
-''',
-                c_name=c_name(name))
+''')

     for var in variants.variants:
         ret += mcgen('''
@@ -233,14 +236,14 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, 
const char *name, Error
     Error *err = NULL;

     visit_start_struct(v, (void **)obj, "%(name)s", name, sizeof(%(c_name)s), 
&err);
-    if (err) {
-        goto out;
-    }
+''',
+                 c_name=c_name(name), name=name)
+    ret += gen_err_check()
+    ret += mcgen('''
     if (!*obj) {
         goto out_obj;
     }
-''',
-                 c_name=c_name(name), name=name)
+''')

     if base:
         ret += mcgen('''
@@ -255,13 +258,6 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, 
const char *name, Error
         tag_key = 'type'
     ret += mcgen('''
     visit_type_%(c_type)s(v, &(*obj)->%(c_name)s, "%(name)s", &err);
-    if (err) {
-        goto out_obj;
-    }
-    if (!visit_start_union(v, !!(*obj)->data, &err) || err) {
-        goto out_obj;
-    }
-    switch ((*obj)->%(c_name)s) {
 ''',
                  c_type=variants.tag_member.type.c_name(),
                  # TODO ugly special case for simple union
@@ -269,6 +265,17 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, 
const char *name, Error
                  # it, then: c_name=c_name(variants.tag_member.name)
                  c_name=c_name(variants.tag_name or 'kind'),
                  name=tag_key)
+    ret += gen_err_check(label='out_obj')
+    ret += mcgen('''
+    if (!visit_start_union(v, !!(*obj)->data, &err) || err) {
+        goto out_obj;
+    }
+    switch ((*obj)->%(c_name)s) {
+''',
+                 # TODO ugly special case for simple union
+                 # Use same tag name in C as on the wire to get rid of
+                 # it, then: c_name=c_name(variants.tag_member.name)
+                 c_name=c_name(variants.tag_name or 'kind'))

     for var in variants.variants:
         # TODO ugly special case for simple union
-- 
2.4.3