Re: [PATCH v2 1/3] qemu-config: parse configuration files to a QDict

[Kevin Wolf]

Am 20.05.2021 um 11:26 hat Paolo Bonzini geschrieben:
> Change the parser to put the values into a QDict and pass them
> to a callback.  qemu_config_parse's QemuOpts creation is
> itself turned into a callback function.
> 
> This is useful for -readconfig to support keyval-based options;
> getting a QDict from the parser removes a roundtrip from
> QDict to QemuOpts and then back to QDict.
> 
> Unfortunately there is a disadvantage in that semantic errors will
> point to the last line of the group, because the entries of the QDict
> do not have a location attached.
> 
> Cc: Kevin Wolf <kwolf@redhat.com>
> Cc: Markus Armbruster <armbru@redhat.com>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

> -int qemu_read_config_file(const char *filename, Error **errp)
> +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 (id) {
> +        qdict_del(qdict, "id");
> +    }
> +    qemu_opts_absorb_qdict(opts, qdict, errp);
> +    unrecognized = qdict_first(qdict);
> +    if (unrecognized) {
> +        error_setg(errp, QERR_INVALID_PARAMETER, unrecognized->key);

This demonstrates why in the v1 review I suggested always checking for
errors explicitly and returning immediately in the error case.

errp can now be set twice, which will cause an assertion failure.

> +        qemu_opts_del(opts);
> +    }
> +}

Kevin