Re: [PATCH v3] tools lib traceevent: Take care of return value of asprintf

[Arnaldo Carvalho de Melo <acme@redhat.com>]

Em Wed, Mar 25, 2020 at 09:05:46PM +0800, He Zhe escreveu:
> Can this be considered for the moment?

Rostedt, have you looked at this?

- Arnaldo
 
> Thanks,
> Zhe
> 
> On 2/20/20 9:58 AM, zhe.he@windriver.com wrote:
> > From: He Zhe <zhe.he@windriver.com>
> >
> > According to the API, if memory allocation wasn't possible, or some other
> > error occurs, asprintf will return -1, and the contents of strp below are
> > undefined.
> >
> > int asprintf(char **strp, const char *fmt, ...);
> >
> > This patch takes care of return value of asprintf to make it less error
> > prone and prevent the following build warning.
> >
> > ignoring return value of ‘asprintf’, declared with attribute warn_unused_result [-Wunused-result]
> >
> > Signed-off-by: He Zhe <zhe.he@windriver.com>
> > ---
> > v2: directly check the return value without saving to a variable
> > v3: as asked, not remove those that already save the return value
> >
> >  tools/lib/traceevent/parse-filter.c | 29 +++++++++++++++++++----------
> >  1 file changed, 19 insertions(+), 10 deletions(-)
> >
> > diff --git a/tools/lib/traceevent/parse-filter.c b/tools/lib/traceevent/parse-filter.c
> > index 20eed71..c271aee 100644
> > --- a/tools/lib/traceevent/parse-filter.c
> > +++ b/tools/lib/traceevent/parse-filter.c
> > @@ -1958,7 +1958,8 @@ static char *op_to_str(struct tep_event_filter *filter, struct tep_filter_arg *a
> >  				default:
> >  					break;
> >  				}
> > -				asprintf(&str, val ? "TRUE" : "FALSE");
> > +				if (asprintf(&str, val ? "TRUE" : "FALSE") < 0)
> > +					str = NULL;
> >  				break;
> >  			}
> >  		}
> > @@ -1976,7 +1977,8 @@ static char *op_to_str(struct tep_event_filter *filter, struct tep_filter_arg *a
> >  			break;
> >  		}
> >  
> > -		asprintf(&str, "(%s) %s (%s)", left, op, right);
> > +		if (asprintf(&str, "(%s) %s (%s)", left, op, right) < 0)
> > +			str = NULL;
> >  		break;
> >  
> >  	case TEP_FILTER_OP_NOT:
> > @@ -1992,10 +1994,12 @@ static char *op_to_str(struct tep_event_filter *filter, struct tep_filter_arg *a
> >  			right_val = 0;
> >  		if (right_val >= 0) {
> >  			/* just return the opposite */
> > -			asprintf(&str, right_val ? "FALSE" : "TRUE");
> > +			if (asprintf(&str, right_val ? "FALSE" : "TRUE") < 0)
> > +				str = NULL;
> >  			break;
> >  		}
> > -		asprintf(&str, "%s(%s)", op, right);
> > +		if (asprintf(&str, "%s(%s)", op, right) < 0)
> > +			str = NULL;
> >  		break;
> >  
> >  	default:
> > @@ -2011,7 +2015,8 @@ static char *val_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
> >  {
> >  	char *str = NULL;
> >  
> > -	asprintf(&str, "%lld", arg->value.val);
> > +	if (asprintf(&str, "%lld", arg->value.val) < 0)
> > +		str = NULL;
> >  
> >  	return str;
> >  }
> > @@ -2069,7 +2074,8 @@ static char *exp_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
> >  		break;
> >  	}
> >  
> > -	asprintf(&str, "%s %s %s", lstr, op, rstr);
> > +	if (asprintf(&str, "%s %s %s", lstr, op, rstr) < 0)
> > +		str = NULL;
> >  out:
> >  	free(lstr);
> >  	free(rstr);
> > @@ -2113,7 +2119,8 @@ static char *num_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
> >  		if (!op)
> >  			op = "<=";
> >  
> > -		asprintf(&str, "%s %s %s", lstr, op, rstr);
> > +		if (asprintf(&str, "%s %s %s", lstr, op, rstr) < 0)
> > +			str = NULL;
> >  		break;
> >  
> >  	default:
> > @@ -2148,8 +2155,9 @@ static char *str_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
> >  		if (!op)
> >  			op = "!~";
> >  
> > -		asprintf(&str, "%s %s \"%s\"",
> > -			 arg->str.field->name, op, arg->str.val);
> > +		if (asprintf(&str, "%s %s \"%s\"",
> > +			 arg->str.field->name, op, arg->str.val) < 0)
> > +			str = NULL;
> >  		break;
> >  
> >  	default:
> > @@ -2165,7 +2173,8 @@ static char *arg_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
> >  
> >  	switch (arg->type) {
> >  	case TEP_FILTER_ARG_BOOLEAN:
> > -		asprintf(&str, arg->boolean.value ? "TRUE" : "FALSE");
> > +		if (asprintf(&str, arg->boolean.value ? "TRUE" : "FALSE") < 0)
> > +			str = NULL;
> >  		return str;
> >  
> >  	case TEP_FILTER_ARG_OP: