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Re: [Qemu-block] [Qemu-devel] [PATCH 12/18] block-qdict: Clean up qdict_
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH 12/18] block-qdict: Clean up qdict_crumple() a bit |
Date: |
Thu, 14 Jun 2018 13:52:11 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Kevin Wolf <address@hidden> writes:
> Am 13.06.2018 um 17:23 hat Markus Armbruster geschrieben:
>> Kevin Wolf <address@hidden> writes:
>>
>> > Am 12.06.2018 um 14:58 hat Markus Armbruster geschrieben:
>> >> When you mix scalar and non-scalar keys, whether you get an "already
>> >> set as scalar" or an "already set as dict" error depends on qdict
>> >> iteration order. Neither message makes much sense. Replace by
>> >> ""Cannot mix scalar and non-scalar keys". This is similar to the
>> >> message we get for mixing list and non-list keys.
>> >>
>> >> I find qdict_crumple()'s first loop hard to understand. Rearrange it
>> >> and add a comment.
>> >>
>> >> Signed-off-by: Markus Armbruster <address@hidden>
>> >
>> > To be honest, I found the old version of the loop more obvious.
>> >
>> >> qobject/block-qdict.c | 42 +++++++++++++++++++++---------------------
>> >> 1 file changed, 21 insertions(+), 21 deletions(-)
>> >>
>> >> diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c
>> >> index a4e1c8d08f..35e9052816 100644
>> >> --- a/qobject/block-qdict.c
>> >> +++ b/qobject/block-qdict.c
>> >> @@ -403,7 +403,7 @@ static int qdict_is_list(QDict *maybe_list, Error
>> >> **errp)
>> >> QObject *qdict_crumple(const QDict *src, Error **errp)
>> >> {
>> >> const QDictEntry *ent;
>> >> - QDict *two_level, *multi_level = NULL;
>> >> + QDict *two_level, *multi_level = NULL, *child_dict;
>> >> QObject *dst = NULL, *child;
>> >> size_t i;
>> >> char *prefix = NULL;
>> >> @@ -422,29 +422,29 @@ QObject *qdict_crumple(const QDict *src, Error
>> >> **errp)
>> >> }
>> >>
>> >> qdict_split_flat_key(ent->key, &prefix, &suffix);
>> >> -
>> >> child = qdict_get(two_level, prefix);
>> >> + child_dict = qobject_to(QDict, child);
>> >> +
>> >> + if (child) {
>> >> + /*
>> >> + * An existing child must be a dict and @ent must be a
>> >> + * dict member (i.e. suffix not null), or else @ent
>> >> + * clashes.
>> >> + */
>> >> + if (!child_dict || !suffix) {
>> >> + error_setg(errp,
>> >> + "Cannot mix scalar and non-scalar keys");
>> >> + goto error;
>> >> + }
>> >> + } else if (suffix) {
>> >> + child_dict = qdict_new();
>> >> + qdict_put(two_level, prefix, child_dict);
>> >> + } else {
>> >> + qdict_put_obj(two_level, prefix, qobject_ref(ent->value));
>> >> + }
>> >
>> > At least, can you please move the else branch to the if below so that
>> > the addition of the new entry is symmetrical for both scalars and dicts?
>> > As the code is, it mixes the conflict check, creation of the child dict
>> > and addition of scalars (but not to the child dict) in a weird way in a
>> > single if block.
>> >
>> > Or maybe organise it like this:
>> >
>> > if (child && !(child_dict && suffix)) {
>> > error
>> > }
>> >
>> > if (suffix) {
>> > if (!child_dict) {
>> > create it
>> > add it to two_level
>> > }
>> > add entry to child_dict
>> > } else {
>> > add entry to two_level
>> > }
>>
>> Fleshing out...
>>
>> if (child && !child_dict) {
>> /*
>> * @prefix already exists and it's a non-dictionary,
>> * i.e. we've seen a scalar with key @prefix. The same
>> * key can't occur twice, therefore suffix must be
>> * non-null.
>> */
>> assert(suffix);
>> /*
>> * @ent has key @address@hidden, but we've already seen
>> * key @prefix: clash.
>> */
>> error_setg(errp, "Cannot mix scalar and non-scalar keys");
>> goto error;
>> }
>
> This catches "foo.bar" after "foo", but not "foo" after "foo.bar".
>
>> if (suffix) {
>> if (!child_dict) {
>> child_dict = qdict_new();
>> qdict_put(two_level, prefix, child_dict);
>> }
>> qdict_put_obj(child_dict, suffix, qobject_ref(ent->value));
>> } else {
>> assert(!child);
>
> So "foo" after "foo.bar" would fail this assertion.
>
>> qdict_put_obj(two_level, prefix, qobject_ref(ent->value));
>> }
>>
>> Okay?
>
> Kevin
I feel dumb. Next try:
if (child) {
/*
* If @child_dict, then all previous keys with this prefix
* had a suffix. If @suffix, this one has one as well,
* and we're good, else there's a clash.
*/
if (!child_dict || !suffix) {
error_setg(errp, "Cannot mix scalar and non-scalar keys");
goto error;
}
}
if (suffix) {
if (!child_dict) {
child_dict = qdict_new();
qdict_put(two_level, prefix, child_dict);
}
qdict_put_obj(child_dict, suffix, qobject_ref(ent->value));
} else {
qdict_put_obj(two_level, prefix, qobject_ref(ent->value));
}
- [Qemu-block] [PATCH 13/18] block-qdict: Simplify qdict_is_list() some, (continued)
- [Qemu-block] [PATCH 13/18] block-qdict: Simplify qdict_is_list() some, Markus Armbruster, 2018/06/12
- [Qemu-block] [PATCH 15/18] check-block-qdict: Cover flattening of empty lists and dictionaries, Markus Armbruster, 2018/06/12
- [Qemu-block] [PATCH 17/18] rbd: New parameter auth-client-required, Markus Armbruster, 2018/06/12
- [Qemu-block] [PATCH 07/18] block: Clean up a misuse of qobject_to() in .bdrv_co_create_opts(), Markus Armbruster, 2018/06/12
- [Qemu-block] [PATCH 12/18] block-qdict: Clean up qdict_crumple() a bit, Markus Armbruster, 2018/06/12
[Qemu-block] [PATCH 10/18] block-qdict: Simplify qdict_flatten_qdict(), Markus Armbruster, 2018/06/12
[Qemu-block] [PATCH 03/18] block: Add block-specific QDict header, Markus Armbruster, 2018/06/12
[Qemu-block] [PATCH 18/18] rbd: New parameter key-secret, Markus Armbruster, 2018/06/12
[Qemu-block] [PATCH 08/18] block: Factor out qobject_input_visitor_new_flat_confused(), Markus Armbruster, 2018/06/12
[Qemu-block] [PATCH 05/18] block: Fix -blockdev for certain non-string scalars, Markus Armbruster, 2018/06/12