Re: [Qemu-devel] [PATCH 09/13] QMP: New argument checker (second part)

[Markus Armbruster]

Luiz Capitulino <address@hidden> writes:

> This commit introduces the second (and last) part of QMP's new
> argument checker.
>
> The job is done by check_client_args_type(), it iterates over
> the client's argument qdict and for for each argument it checks
> if it exists and if its type is valid.
>
> It's important to observe the following changes from the existing
> argument checker:
>
>   - If the handler accepts an O-type argument, unknown arguments
>     are passed down to it. It's up to O-type handlers to validate
>     their arguments
>
>   - Boolean types (eg. 'b' and '-') don't accept integers anymore,
>     only json-bool
>
>   - Argument types '/' and '.' are currently unsupported under QMP,
>     thus they're not handled
>
> Signed-off-by: Luiz Capitulino <address@hidden>
> ---
>  monitor.c |  100 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 99 insertions(+), 1 deletions(-)
>
> diff --git a/monitor.c b/monitor.c
> index b4fe5ba..8d074c2 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -4139,6 +4139,101 @@ static int invalid_qmp_mode(const Monitor *mon, const 
> char *cmd_name)
>  }
>  
>  /*
> + * Argument validation rules:
> + *
> + * 1. The argument must exist in cmd_args qdict
> + * 2. The argument type must be the expected one
> + *
> + * Special case: If the argument doesn't exist in cmd_args and
> + *               the QMP_CHECKER_OTYPE flag is set, then the
> + *               argument is considered an O-type one and the
> + *               checking is skipped for it.
> + */
> +static int check_client_args_type(const QDict *client_args,
> +                                  const QDict *cmd_args, int flags)
> +{
> +    const QDictEntry *ent;
> +
> +    for (ent = qdict_first(client_args); ent;ent = 
> qdict_next(client_args,ent)){
> +        QObject *obj;
> +        QString *arg_type;
> +        const QObject *client_arg = qdict_entry_value(ent);
> +        const char *client_arg_name = qdict_entry_key(ent);
> +
> +        obj = qdict_get(cmd_args, client_arg_name);
> +        if (!obj) {
> +            if (flags & QMP_CHECKER_OTYPE) {
> +                /*
> +                 * This handler accepts O-type arguments, it's up to it to
> +                 * check for unknowns and validate its type.
> +                 */
> +                continue;
> +            }
> +            /* client arg doesn't exist */
> +            qerror_report(QERR_INVALID_PARAMETER, client_arg_name);
> +            return -1;
> +        }
> +
> +        arg_type = qobject_to_qstring(obj);
> +        assert(arg_type != NULL);
> +
> +        /* check if argument's type is correct */
> +        switch (qstring_get_str(arg_type)[0]) {
> +        case 'F':
> +        case 'B':
> +        case 's':
> +            if (qobject_type(client_arg) != QTYPE_QSTRING) {
> +                qerror_report(QERR_INVALID_PARAMETER_TYPE, client_arg_name,
> +                              "string");
> +                return -1;
> +            }
> +        break;
> +        case 'i':
> +        case 'l':
> +        case 'M':
> +            if (qobject_type(client_arg) != QTYPE_QINT) {
> +                qerror_report(QERR_INVALID_PARAMETER_TYPE, client_arg_name,
> +                              "int");
> +                return -1; 
> +            }
> +            break;
> +        case 'f':
> +        case 'T':
> +            if (qobject_type(client_arg) != QTYPE_QINT &&
> +                qobject_type(client_arg) != QTYPE_QFLOAT) {
> +                qerror_report(QERR_INVALID_PARAMETER_TYPE, client_arg_name,
> +                              "number");
> +               return -1; 
> +            }
> +            break;
> +        case 'b':
> +        case '-':
> +            if (qobject_type(client_arg) != QTYPE_QBOOL) {
> +                qerror_report(QERR_INVALID_PARAMETER_TYPE, client_arg_name,
> +                              "bool");
> +               return -1; 
> +            }
> +            break;
> +        case 'O':
> +            /* XXX: this argument has the same name of the O-type defined in
> +                    in qemu-monitor.hx. This is not allowed, right? */


No, it's actually fine.

Consider device_add.  Its args_type is "device:O".  Nevertheless, it's
pefectly okay for a qdev to have a property named "device".

> +            qerror_report(QERR_INVALID_PARAMETER, client_arg_name);
> +            return -1;

Instead:

               assert(flags & QMP_CHECKER_OTYPE);
               continue;

Not sure I like the name QMP_CHECKER_OTYPE.  The way it's used, it means
"in addition to checking declared arguments, accept undeclared arguments
without checking them (somebody else will check)".  'O-type' is merely
something that triggers that flag.  Happens to be the only way right
now.

QMP_CHECKER_ACCEPT_MORE_ARGS?

> +        case '/':
> +        case '.':
> +            /*
> +             * These types are not supported by QMP and thus are not
> +             * handled here. Fall through.
> +             */
> +        default:
> +            abort();
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +/*
>   * - Check if the client has passed all mandatory args
>   * - Set special flags for argument validation
>   */
> @@ -4215,6 +4310,9 @@ out:
>   * Client argument checking rules:
>   *
>   * 1. Client must provide all mandatory arguments
> + * 2. Each argument provided by the client must be expected
> + * 3. Each argument provided by the client must have the type expected
> + *    by the command
>   */
>  static int qmp_check_client_args(const mon_cmd_t *cmd, QDict *client_args)
>  {
> @@ -4229,7 +4327,7 @@ static int qmp_check_client_args(const mon_cmd_t *cmd, 
> QDict *client_args)
>          goto out;
>      }
>  
> -    /* TODO: Check client args type */
> +    err = check_client_args_type(client_args, cmd_args, flags);
>  
>  out:
>      QDECREF(cmd_args);