Re: [Qemu-devel] [PATCH 4/9] QMP: Second half of the new argument checking code

[Luiz Capitulino]

On Wed, 02 Jun 2010 09:31:24 +0200
Markus Armbruster <address@hidden> wrote:

> Luiz Capitulino <address@hidden> writes:
> 
> > This commit introduces check_client_args_type(), which is
> > called by qmp_check_client_args() and complements the
> > previous commit.
> >
> > Now the new client's argument checker code is capable of
> > doing type checking and detecting unknown arguments.
> >
> > It works this way: we iterate over the client's arguments
> > qdict and for each argument we check if it exists and if
> > its type is correct.
> >
> > Signed-off-by: Luiz Capitulino <address@hidden>
> > ---
> >  monitor.c |   77 
> > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> >  1 files changed, 76 insertions(+), 1 deletions(-)
> >
> > diff --git a/monitor.c b/monitor.c
> > index 47a0da8..14790e6 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -4266,6 +4266,75 @@ typedef struct QMPArgCheckRes {
> >  } QMPArgCheckRes;
> >  
> >  /*
> > + * Check if client's argument exists and type is correct
> > + */
> > +static void check_client_args_type(const char *client_arg_name,
> > +                                   QObject *client_arg, void *opaque)
> > +{
> > +    QObject *obj;
> > +    QString *arg_type;
> > +    QMPArgCheckRes *res = opaque;
> > +
> > +    if (res->result < 0) {
> > +        /* report only the first error */
> > +        return;
> > +    }
> > +
> > +    obj = qdict_get(res->qdict, client_arg_name);
> > +    if (!obj) {
> > +        /* client arg doesn't exist */
> > +        res->result = -1;
> > +        qerror_report(QERR_INVALID_PARAMETER, client_arg_name);
> > +        return;
> > +    }
> > +
> > +    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");
> > +            res->result = -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");
> > +            res->result = -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");
> > +            res->result = -1;
> > +        }
> > +        break;
> > +    case 'b':
> > +    case '-':
> > +        if (qobject_type(client_arg) != QTYPE_QBOOL) {
> > +            qerror_report(QERR_INVALID_PARAMETER_TYPE, client_arg_name, 
> > "bool");
> > +            res->result = -1;
> > +        }
> > +        break;
> > +    case 'O':
> > +        /* Not checked here */
> > +        break;
> 
> What about case '/'?  I guess it doesn't make much sense for QMP, but
> the old checker handles it.  If we drop it from QMP, we should document
> the restriction in the source.

 Yes, there're two args_type we don't handle in QMP because we don't have
any of those handlers converted: '/' and '.'.

 I think it's unlikely to get them converted in this form, so the current
implementation contains dead-code. I explained this in one commit log, but
maybe it's the wrong place.

> 
> > +    default:
> > +        abort();
> > +    }
> > +}
> > +
> > +/*
> >   * Check if client passed all mandatory args
> >   */
> >  static void check_mandatory_args(const char *cmd_arg_name,
> > @@ -4344,6 +4413,9 @@ out:
> >   * Client argument checking rules:
> >   *
> >   * 1. Client must provide all mandatory arguments
> > + * 2. Each argument provided by the client must be valid
> > + * 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)
> >  {
> > @@ -4355,7 +4427,10 @@ static int qmp_check_client_args(const mon_cmd_t 
> > *cmd, QDict *client_args)
> >      res.qdict = client_args;
> >      qdict_iter(cmd_args, check_mandatory_args, &res);
> >  
> > -    /* TODO: Check client args type */
> > +    if (!res.result && !res.skip) {
> > +        res.qdict = cmd_args;
> > +        qdict_iter(client_args, check_client_args_type, &res);
> > +    }
> 
> What if we have both an O-type argument and other arguments?  Then the
> 'O' makes check_client_args_type() set res.skip, and we duly skip
> checking the other arguments here.

 Oh, good catch. I thought that that was what the current code does,
but looks like I misread it.

> Again, the iterator makes for tortuous code.
> 
> >  
> >      QDECREF(cmd_args);
> >      return res.result;
>