[Libguestfs] [PATCH 7/9] qapi: Generalize enum member policy checking

[John Snow]

On Tue, Oct 26, 2021 at 5:43 AM Markus Armbruster <armbru at redhat.com> wrote:

> John Snow <jsnow at redhat.com> writes:
>
> > On Mon, Oct 25, 2021 at 1:26 AM Markus Armbruster <armbru at redhat.com>
> wrote:
> >
> >> The code to check enumeration value policy can see special feature
> >> flag 'deprecated' in QEnumLookup member flags[value].  I want to make
> >> feature flag 'unstable' visible there as well, so I can add policy for
> >> it.
> >>
> >> Instead of extending flags[], replace it by @special_features (a
> >> bitset of QapiSpecialFeature), because that's how special features get
> >> passed around elsewhere.
> >>
> >> Signed-off-by: Markus Armbruster <armbru at redhat.com>
> >> ---
> >>  include/qapi/util.h    |  5 +----
> >>  qapi/qapi-visit-core.c |  3 ++-
> >>  scripts/qapi/types.py  | 22 ++++++++++++----------
> >>  3 files changed, 15 insertions(+), 15 deletions(-)
> >>
> >> diff --git a/include/qapi/util.h b/include/qapi/util.h
> >> index 7a8d5c7d72..0cc98db9f9 100644
> >> --- a/include/qapi/util.h
> >> +++ b/include/qapi/util.h
> >> @@ -15,12 +15,9 @@ typedef enum {
> >>      QAPI_DEPRECATED,
> >>  } QapiSpecialFeature;
> >>
> >> -/* QEnumLookup flags */
> >> -#define QAPI_ENUM_DEPRECATED 1
> >> -
> >>  typedef struct QEnumLookup {
> >>      const char *const *array;
> >> -    const unsigned char *const flags;
> >> +    const unsigned char *const special_features;
> >>      const int size;
> >>  } QEnumLookup;
> >>
> >> diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
> >> index b4a81f1757..5572d90efb 100644
> >> --- a/qapi/qapi-visit-core.c
> >> +++ b/qapi/qapi-visit-core.c
> >> @@ -407,7 +407,8 @@ static bool input_type_enum(Visitor *v, const char
> >> *name, int *obj,
> >>          return false;
> >>      }
> >>
> >> -    if (lookup->flags && (lookup->flags[value] &
> QAPI_ENUM_DEPRECATED)) {
> >> +    if (lookup->special_features
> >> +        && (lookup->special_features[value] & QAPI_DEPRECATED)) {
> >>          switch (v->compat_policy.deprecated_input) {
> >>          case COMPAT_POLICY_INPUT_ACCEPT:
> >>              break;
> >> diff --git a/scripts/qapi/types.py b/scripts/qapi/types.py
> >> index ab2441adc9..3013329c24 100644
> >> --- a/scripts/qapi/types.py
> >> +++ b/scripts/qapi/types.py
> >> @@ -16,7 +16,7 @@
> >>  from typing import List, Optional
> >>
> >>  from .common import c_enum_const, c_name, mcgen
> >> -from .gen import QAPISchemaModularCVisitor, ifcontext
> >> +from .gen import QAPISchemaModularCVisitor, gen_special_features,
> >> ifcontext
> >>  from .schema import (
> >>      QAPISchema,
> >>      QAPISchemaEnumMember,
> >> @@ -39,7 +39,7 @@ def gen_enum_lookup(name: str,
> >>                      members: List[QAPISchemaEnumMember],
> >>                      prefix: Optional[str] = None) -> str:
> >>      max_index = c_enum_const(name, '_MAX', prefix)
> >> -    flags = ''
> >> +    feats = ''
> >>      ret = mcgen('''
> >>
> >>  const QEnumLookup %(c_name)s_lookup = {
> >> @@ -54,19 +54,21 @@ def gen_enum_lookup(name: str,
> >>  ''',
> >>                       index=index, name=memb.name)
> >>          ret += memb.ifcond.gen_endif()
> >> -        if 'deprecated' in (f.name for f in memb.features):
> >> -            flags += mcgen('''
> >> -        [%(index)s] = QAPI_ENUM_DEPRECATED,
> >> -''',
> >> -                           index=index)
> >>
> >> -    if flags:
> >> +        special_features = gen_special_features(memb.features)
> >> +        if special_features != '0':
> >>
> >
> > Though, I have to admit the common reoccurrence of this pattern suggests
> to
> > me that gen_special_features really ought to be returning something
> false-y
> > in these cases. Something about testing for the empty case with something
> > that represents, but isn't empty, gives me a brief pause.
> >
> > Not willing to wage war over it.
>
> I habitually start stupid, and when stupid confuses or annoys me later,
> I smarten it up some.
>
> Let's see how this instance of "stupid" ages, okay?
>
>
"I see what you're saying, but mehhhhh" is a relatable feeling ;)

>
> >> +            feats += mcgen('''
> >> +        [%(index)s] = %(special_features)s,
> >> +''',
> >> +                           index=index,
> special_features=special_features)
> >> +
> >> +    if feats:
> >>          ret += mcgen('''
> >>      },
> >> -    .flags = (const unsigned char[%(max_index)s]) {
> >> +    .special_features = (const unsigned char[%(max_index)s]) {
> >>  ''',
> >>                       max_index=max_index)
> >> -        ret += flags
> >> +        ret += feats
> >>
> >>      ret += mcgen('''
> >>      },
> >> --
> >> 2.31.1
> >>
> >>
> > Python bits: Acked-by: John Snow <jsnow at redhat.com>
>
> Thanks!
>
>
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