This patch adds a struct type in Go that will handle return values
for QAPI's command types.
The return value of a Command is, encouraged to be, QAPI's complex
types or an Array of those.
Every Command has a underlying CommandResult. The EmptyCommandReturn
is for those that don't expect any data e.g: `{ "return": {} }`.
All CommandReturn types implement the CommandResult interface.
Example:
qapi:
| { 'command': 'query-sev', 'returns': 'SevInfo',
| 'if': 'TARGET_I386' }
go:
| type QuerySevCommandReturn struct {
| CommandId string `json:"id,omitempty"`
| Result *SevInfo `json:"return"`
| Error *QapiError `json:"error,omitempty"`
| }
usage:
| // One can use QuerySevCommandReturn directly or
| // command's interface GetReturnType() instead.
|
| input := `{ "return": { "enabled": true, "api-major" : 0,` +
| `"api-minor" : 0, "build-id" : 0,` +
| `"policy" : 0, "state" : "running",` +
| `"handle" : 1 } } `
|
| ret := QuerySevCommandReturn{}
| err := json.Unmarshal([]byte(input), &ret)
| if ret.Error != nil {
| // Handle command failure {"error": { ...}}
| } else if ret.Result != nil {
| // ret.Result.Enable == true
| }
Signed-off-by: Victor Toso <victort...@redhat.com>
---
scripts/qapi/golang.py | 72 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 70 insertions(+), 2 deletions(-)
diff --git a/scripts/qapi/golang.py b/scripts/qapi/golang.py
index 52a9124641..48ca0deab0 100644
--- a/scripts/qapi/golang.py
+++ b/scripts/qapi/golang.py
@@ -40,6 +40,15 @@
'''
TEMPLATE_HELPER = '''
+type QapiError struct {
+ Class string `json:"class"`
+ Description string `json:"desc"`
+}
+
+func (err *QapiError) Error() string {
+ return fmt.Sprintf("%s: %s", err.Class, err.Description)
+}
+
// Creates a decoder that errors on unknown Fields
// Returns nil if successfully decoded @from payload to @into type
// Returns error if failed to decode @from payload to @into type
@@ -254,12 +263,17 @@
func (s *{type_name}) GetId() string {{
return s.MessageId
}}
+
+func (s *{type_name}) GetReturnType() CommandReturn {{
+ return &{cmd_ret_name}{{}}
+}}
'''
TEMPLATE_COMMAND = '''
type Command interface {{
GetId() string
GetName() string
+ GetReturnType() CommandReturn
}}
func MarshalCommand(c Command) ([]byte, error) {{
@@ -292,6 +306,45 @@
}}
'''
+TEMPLATE_COMMAND_RETURN = '''
+type CommandReturn interface {
+ GetId() string
+ GetCommandName() string
+ GetError() error
+}
+'''
+
+TEMPLATE_COMMAND_RETURN_METHODS = '''
+type {cmd_ret_name} struct {{
+ MessageId string `json:"id,omitempty"`
+ Error *QapiError `json:"error,omitempty"`
+{result}
+}}
+
+func (r *{cmd_ret_name}) GetCommandName() string {{
+ return "{name}"
+}}
+
+func (r *{cmd_ret_name}) GetId() string {{
+ return r.MessageId
+}}
+
+func (r *{cmd_ret_name}) GetError() error {{
+ return r.Error
+}}
+
+{marshal_empty}
+'''
+
+TEMPLATE_COMMAND_RETURN_MARSHAL_EMPTY = '''
+func (r {cmd_ret_name}) MarshalJSON() ([]byte, error) {{
+ if r.Error != nil {{
+ type Alias {cmd_ret_name}
+ return json.Marshal(Alias(r))
+ }}
+ return []byte(`{{"return":{{}}}}`), nil
+}}'''
+
def gen_golang(schema: QAPISchema,
output_dir: str,
prefix: str) -> None:
@@ -327,7 +380,7 @@ def qapi_to_go_type_name(name: str,
name += ''.join(word.title() for word in words[1:])
- types = ["event", "command"]
+ types = ["event", "command", "command return"]
if meta in types:
name = name[:-3] if name.endswith("Arg") else name
name += meta.title().replace(" ", "")
@@ -783,6 +836,7 @@ def generate_template_command(commands: dict[str, str]) ->
str:
return &command.Args, nil
'''
content = TEMPLATE_COMMAND.format(cases=cases)
+ content += TEMPLATE_COMMAND_RETURN
return content
@@ -926,6 +980,15 @@ def visit_command(self,
type_name = qapi_to_go_type_name(name, info.defn_meta)
self.commands[name] = type_name
+ cmd_ret_name = qapi_to_go_type_name(name, "command return")
+ marshal_empty =
TEMPLATE_COMMAND_RETURN_MARSHAL_EMPTY.format(cmd_ret_name=cmd_ret_name)
+ result = ""
+ if ret_type:
+ marshal_empty = ""
+ ret_type_name = qapi_schema_type_to_go_type(ret_type.name)
+ isptr = "*" if ret_type_name[0] not in "*[" else ""
+ result = f'''Result {isptr}{ret_type_name} `json:"return"`'''
+
content = ""
if boxed or not arg_type or not qapi_name_is_object(arg_type.name):
args = "" if not arg_type else "\n" + arg_type.name
@@ -943,7 +1006,12 @@ def visit_command(self,
arg_type.variants)
content += TEMPLATE_COMMAND_METHODS.format(name=name,
- type_name=type_name)
+ type_name=type_name,
+ cmd_ret_name=cmd_ret_name)
+ content += TEMPLATE_COMMAND_RETURN_METHODS.format(name=name,
+
cmd_ret_name=cmd_ret_name,
+ result=result,
+
marshal_empty=marshal_empty)
self.target["command"] += content
def visit_event(self, name, info, ifcond, features, arg_type, boxed):
--
2.41.0
