Re: [PATCH] qemu-config: use qemu_opts_from_qdict

[Markus Armbruster <armbru@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> Using qemu_opts_absorb_qdict, and then checking for any leftover options,
> is redundant because there is already a function that does the same,
> qemu_opts_from_qdict.  qemu_opts_from_qdict consumes the whole dictionary
> and therefore can just return an error message if an option fails to validate.

I missed this when I reviewed the series...

> This also fixes a bug, because the "id" entry was retrieved in
> qemu_config_do_parse and then left there by qemu_opts_absorb_qdict.
> As a result, it was reported as an unrecognized option.
>
> Reported-by: Markus Armbruster <armbru@redhat.com>
> Fixes: 3770141139 ("qemu-config: parse configuration files to a QDict")
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  util/qemu-config.c | 17 +----------------
>  1 file changed, 1 insertion(+), 16 deletions(-)
>
> diff --git a/util/qemu-config.c b/util/qemu-config.c
> index 374f3bc460..84ee6dc4ea 100644
> --- a/util/qemu-config.c
> +++ b/util/qemu-config.c
> @@ -429,29 +429,14 @@ out:
>  void qemu_config_do_parse(const char *group, QDict *qdict, void *opaque, Error **errp)
>  {
>      QemuOptsList **lists = opaque;
> -    const char *id = qdict_get_try_str(qdict, "id");
>      QemuOptsList *list;
> -    QemuOpts *opts;
> -    const QDictEntry *unrecognized;
>  
>      list = find_list(lists, group, errp);
>      if (!list) {
>          return;
>      }
>  
> -    opts = qemu_opts_create(list, id, 1, errp);
> -    if (!opts) {
> -        return;
> -    }
> -    if (!qemu_opts_absorb_qdict(opts, qdict, errp)) {
> -        qemu_opts_del(opts);
> -        return;
> -    }
> -    unrecognized = qdict_first(qdict);
> -    if (unrecognized) {
> -        error_setg(errp, QERR_INVALID_PARAMETER, unrecognized->key);
> -        qemu_opts_del(opts);
> -    }
> +    qemu_opts_from_qdict(list, qdict, errp);
>  }
>  
>  int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char *fname, Error **errp)

Creation of @opts is now in qemu_opts_from_qdict().  Works the same as
before.  Good.  Let's compare the remainder.

Before the patch:

    qemu_opts_absorb_qdict() absorbs entries with keys the QemuOpts accepts.
    It either accepts a (non-empty) list of keys, or any key.

    It fails when any of the absorbed entries fails
    qemu_opts_from_qdict_entry().

    qemu_config_do_parse() additionally fails when unabsorbed keys remain.

After the patch:

    qemu_opts_from_qdict() feeds all entries to
    qemu_opts_from_qdict_entry().  Which silently ignores entry "id",
    and fails for keys the QemuOpts doesn't accept.

Good.  The part 'ignores entry "id"' fixes the bug.

Reviewed-by: Markus Armbruster <armbru@redhat.com>

Tangent: we silently ignore entries whose value is a QTYPE_QNULL,
QTYPE_QDICT, or QTYPE_QLIST, because qemu_opts_from_qdict_entry() does.
Not changed by this patch, I believe.