Re: [PATCH v2 4/5] qapi: Implement deprecated-input={reject,crash} for enum values

[Markus Armbruster]

Eric Blake <eblake@redhat.com> writes:

> On Sat, Oct 09, 2021 at 02:09:43PM +0200, Markus Armbruster wrote:
>> This copies the code implementing the policy from qapi/qmp-dispatch.c
>> to qapi/qobject-input-visitor.c.  Tolerable, but if we acquire more
>> copes, we should look into factoring them out.
>
> copies

Fixing, thanks!

>> 
>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>> ---
>>  docs/devel/qapi-code-gen.rst |  6 ++++--
>>  qapi/compat.json             |  3 ++-
>>  include/qapi/util.h          |  6 +++++-
>>  qapi/qapi-visit-core.c       | 18 +++++++++++++++---
>>  scripts/qapi/types.py        | 17 ++++++++++++++++-
>>  5 files changed, 42 insertions(+), 8 deletions(-)
>> 
>> diff --git a/docs/devel/qapi-code-gen.rst b/docs/devel/qapi-code-gen.rst
>> index 00334e9fb8..006a6f4a9a 100644
>> --- a/docs/devel/qapi-code-gen.rst
>> +++ b/docs/devel/qapi-code-gen.rst
>> @@ -708,8 +708,10 @@ QEMU shows a certain behaviour.
>>  Special features
>>  ~~~~~~~~~~~~~~~~
>>  
>> -Feature "deprecated" marks a command, event, or struct member as
>> -deprecated.  It is not supported elsewhere so far.
>> +Feature "deprecated" marks a command, event, struct or enum member as
>
> Do we want the comma before the conjunction?  (I've seen style guides
> that recommend it, and style guides that discourage it; while I tend
> to write by the former style, I usually don't care about the latter.
> Rather, switching styles mid-patch caught my attention).

With a comma there, we claim structs can be marked, which is actually
wrong.  Correct is "command, event, struct member, or enum member".

I'll rephrase to "marks a command, event, enum value, or struct member
deprecated."

>> +deprecated.  It is not supported elsewhere so far.  Interfaces so
>> +marked may be withdrawn in future releases in accordance with QEMU's
>> +deprecation policy.
>>  
>>  
>> +++ b/qapi/qapi-visit-core.c
>> @@ -393,7 +393,7 @@ static bool input_type_enum(Visitor *v, const char 
>> *name, int *obj,
>>                              const QEnumLookup *lookup, Error **errp)
>>  {
>>      int64_t value;
>> -    char *enum_str;
>> +    g_autofree char *enum_str = NULL;
>
> Nice change while touching the code.  Is it worth mentioning in the
> commit message?

I figure it would be more distracting than useful.

>>  
>>      if (!visit_type_str(v, name, &enum_str, errp)) {
>>          return false;
>> @@ -402,11 +402,23 @@ static bool input_type_enum(Visitor *v, const char 
>> *name, int *obj,
>>      value = qapi_enum_parse(lookup, enum_str, -1, NULL);
>>      if (value < 0) {
>>          error_setg(errp, QERR_INVALID_PARAMETER, enum_str);
>> -        g_free(enum_str);
>>          return false;
>>      }
>>  
>> -    g_free(enum_str);
>> +    if (lookup->flags && (lookup->flags[value] & QAPI_ENUM_DEPRECATED)) {
>> +        switch (v->compat_policy.deprecated_input) {
>> +        case COMPAT_POLICY_INPUT_ACCEPT:
>> +            break;
>> +        case COMPAT_POLICY_INPUT_REJECT:
>> +            error_setg(errp, "Deprecated value '%s' disabled by policy",
>> +                       enum_str);
>> +            return false;
>> +        case COMPAT_POLICY_INPUT_CRASH:
>> +        default:
>> +            abort();
>> +        }
>> +    }
>> +
>>      *obj = value;
>>      return true;
>>  }
>
> Grammar fixes are minor, so:
>
> Reviewed-by: Eric Blake <eblake@redhat.com>

Thanks!