Re: [Qemu-devel] [PATCH 5/6] add visitor for parsing hz[KMG] input string

[mdroth <mdroth@linux.vnet.ibm.com>]

On Tue, Dec 04, 2012 at 05:34:42PM -0200, Eduardo Habkost wrote:
> From: Igor Mammedov <imammedo@redhat.com>
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> Acked-by: Andreas Färber <afaerber@suse.de>
> ---
>  qapi/qapi-visit-core.c      | 11 +++++++++++
>  qapi/qapi-visit-core.h      |  2 ++
>  qapi/string-input-visitor.c | 22 ++++++++++++++++++++++
>  3 files changed, 35 insertions(+)
> 
> diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
> index 7a82b63..5c8705e 100644
> --- a/qapi/qapi-visit-core.c
> +++ b/qapi/qapi-visit-core.c
> @@ -311,3 +311,14 @@ void input_type_enum(Visitor *v, int *obj, const char *strings[],
>      g_free(enum_str);
>      *obj = value;
>  }
> +
> +void visit_type_freq(Visitor *v, int64_t *obj, const char *name, Error **errp)
> +{
> +    if (!error_is_set(errp)) {
> +        if (v->type_freq) {
> +            v->type_freq(v, obj, name, errp);
> +        } else {
> +            v->type_int(v, obj, name, errp);
> +        }
> +    }
> +}
> diff --git a/qapi/qapi-visit-core.h b/qapi/qapi-visit-core.h
> index 60aceda..e5e7dd7 100644
> --- a/qapi/qapi-visit-core.h
> +++ b/qapi/qapi-visit-core.h
> @@ -62,6 +62,7 @@ struct Visitor
>      void (*type_int64)(Visitor *v, int64_t *obj, const char *name, Error **errp);
>      /* visit_type_size() falls back to (*type_uint64)() if type_size is unset */
>      void (*type_size)(Visitor *v, uint64_t *obj, const char *name, Error **errp);
> +    void (*type_freq)(Visitor *v, int64_t *obj, const char *name, Error **errp);
>  };
>  
>  void visit_start_handle(Visitor *v, void **obj, const char *kind,
> @@ -91,5 +92,6 @@ void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp);
>  void visit_type_bool(Visitor *v, bool *obj, const char *name, Error **errp);
>  void visit_type_str(Visitor *v, char **obj, const char *name, Error **errp);
>  void visit_type_number(Visitor *v, double *obj, const char *name, Error **errp);
> +void visit_type_freq(Visitor *v, int64_t *obj, const char *name, Error **errp);
>  
>  #endif
> diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
> index 497eb9a..74fe395 100644
> --- a/qapi/string-input-visitor.c
> +++ b/qapi/string-input-visitor.c
> @@ -110,6 +110,27 @@ static void parse_start_optional(Visitor *v, bool *present,
>      *present = true;
>  }
>  
> +static void parse_type_freq(Visitor *v, int64_t *obj, const char *name,
> +                            Error **errp)
> +{
> +    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
> +    char *endp = (char *) siv->string;
> +    long long val = 0;
> +
> +    errno = 0;

If this is for strtosz_suffix_unit(), it looks like this is already
handled internally and can be dropped. Relic from a previous version
that called strtod() directly maybe?

If that's not the case, I think it should be fixed in the called function[s]
rather than for each caller.

> +    if (siv->string) {
> +        val = strtosz_suffix_unit(siv->string, &endp,
> +                             STRTOSZ_DEFSUFFIX_B, 1000);

Specifying 1000 as the unit size will make "1M" == 1000^2 as opposed to
1024^2. Is this intentional?

> +    }
> +    if (!siv->string || val == -1 || *endp) {
> +        error_set(errp, QERR_INVALID_PARAMETER_VALUE, name,
> +              "a value representable as a non-negative int64");
> +        return;
> +    }
> +
> +    *obj = val;
> +}
> +
>  Visitor *string_input_get_visitor(StringInputVisitor *v)
>  {
>      return &v->visitor;
> @@ -132,6 +153,7 @@ StringInputVisitor *string_input_visitor_new(const char *str)
>      v->visitor.type_str = parse_type_str;
>      v->visitor.type_number = parse_type_number;
>      v->visitor.start_optional = parse_start_optional;
> +    v->visitor.type_freq = parse_type_freq;

This seems applicable for stuff like -m 1G and potentionally some other
properties. We can make it generic later, but if we do end up re-spinning
consider something like ->type_unit_suffixed_int(). But I'm not against
leaving as is for now since I can't think of a better name for it atm :)

Whatever we call it, based on a recent discussion here:

http://lists.gnu.org/archive/html/qemu-devel/2012-11/msg02872.html

we should have a corresponding implementation in qapi-dealloc-visitor.c.
In this case You can just do:

v->visitor.type_freq = qapi_dealloc_type_int;

There aren't any problems in the current code, we just want to avoid relying on
fallbacks for the dealloc case in general because in some situations the
underlying sizes of the C types don't match and this can cause problems down
the road for the dealloc visitor even though it's okay for other visitor
implementations.

>  
>      v->string = str;
>      return v;
> -- 
> 1.7.11.7
> 
>