Re: [Qemu-devel] [PATCH 13/22] add visitor for parsing hz[KMG] input string

[Don Slutz <don.slutz@gmail.com>]

Don Slutz wrote:
> On 09/07/12 18:47, Igor Mammedov wrote:
>> On Fri, 7 Sep 2012 18:12:00 -0400
>> Don Slutz <Don@cloudswitch.com> wrote:
>>
>>> On 09/07/12 16:55, Igor Mammedov wrote:
>>>> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
>>>> Acked-by: Andreas Färber <afaerber@suse.de>
>>>> -- 
>>>> v2:
>>>>     * replaced _hz suffix for frequency visitor by _freq suffix
>>>>       suggested-by: Andreas Färber
>>>>     * fixed typo & extra space spotted-by: Andreas Färber
>>>> ---
>>>>    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..47d2a84 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;
>>> I get:
>>>
>>> cc1: warnings being treated as errors
>>> qapi/string-input-visitor.c: In function 'parse_type_freq':
>>> qapi/string-input-visitor.c:118: error: 'val' may be used uninitialized
>>> in this function
>>> make: *** [qapi/string-input-visitor.o] Error 1
>>> make: *** Waiting for unfinished jobs....
>> FC17 with default configure settings doesn't complain.
>> And I really do not see how it could be.
>>
>>> Which the change:
>>>
>>>
>>> diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
>>> index 47d2a84..74fe395 100644
>>> --- a/qapi/string-input-visitor.c
>>> +++ b/qapi/string-input-visitor.c
>>> @@ -115,7 +115,7 @@ static void parse_type_freq(Visitor *v, int64_t
>>> *obj, const char *name,
>>>    {
>>>        StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, 
>>> visitor, v);
>>>        char *endp = (char *) siv->string;
>>> -    long long val;
>>> +    long long val = 0;
>>>        errno = 0;
>>>        if (siv->string) {
>>>
>>> Fixes it for me.
>>>
>>>> +
>>>> +    errno = 0;
>>>> +    if (siv->string) {
>>>> +        val = strtosz_suffix_unit(siv->string, &endp,
>>>> +                             STRTOSZ_DEFSUFFIX_B, 1000);
>>>> +    }
>>>> +    if (!siv->string || val == -1 || *endp) {
> I am using CentOS 6.3 so a different compiler.  This is the line that 
> has the issue.
>
> If !siv->string is true the 1st if does not set val. val is then 
> checked for -1.
Opps, This is not correct.   I was going too fast.  After more thought, 
I will agree that C says that val will not be used un-initialized.  So 
it looks to me like a compiler bug.  Since the warning says "val' may be 
used uninitialized.." gcc is "not" reporting a real coding error.

This all said, I think the extra init of val (to 0 or -1) is better then 
requiring a compiler upgrade.
>
>>>> +        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;
>>>>           v->string = str;
>>>>        return v;
>>>     -Don Slutz
>>
>   -Don Slutz
>
  -Don Slutz