Re: [PATCH bpf-next v5 1/2] selftests/bpf: implement setting global variables in veristat

[Eduard Zingerman <eddyz87@gmail.com>]

On Tue, 2025-02-25 at 16:31 +0000, Mykyta Yatsenko wrote:

New warning for trying to set non-enums from enumerators works fine.
This still can be abused if numeric value outside of the supported
range is specified, but that's fine, I think.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

[...]

> @@ -1292,6 +1320,268 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf
>  	return 0;
>  };
>  
> +static int append_var_preset(struct var_preset **presets, int *cnt, const char *expr)
> +{
> +	void *tmp;
> +	struct var_preset *cur;
> +	char var[256], val[256];
> +	long long value;
> +	int r, n, val_len;
> +
> +	tmp = realloc(*presets, (*cnt + 1) * sizeof(**presets));
> +	if (!tmp)
> +		return -ENOMEM;
> +	*presets = tmp;
> +	cur = &(*presets)[*cnt];
> +	cur->applied = false;
> +
> +	if (sscanf(expr, "%s = %s\n", var, val) != 2) {
> +		fprintf(stderr, "Could not parse expression %s\n", expr);
> +		return -EINVAL;
> +	}
> +
> +	val_len = strlen(val);
> +	errno = 0;
> +	r = sscanf(val, "%lli %n", &value, &n);
> +	if (r == 1 && n == val_len) {
> +		if (errno == ERANGE) {
> +			/* Try parsing as unsigned */
> +			errno = 0;
> +			r = sscanf(val, "%llu %n", &value, &n);
> +			/* Try hex if not all chars consumed */
> +			if (n != val_len) {
> +				errno = 0;
> +				r = sscanf(val, "%llx %n", &value, &n);

The discrepancy between %lli accepting 0x but %llu not accepting 0x is
annoying unfortunate. Does not look simpler then before, but let's
merge this already.

> +			}
> +		}
> +		if (errno || r != 1 || n != val_len) {
> +			fprintf(stderr, "Could not parse value %s\n", val);
> +			return -EINVAL;
> +		}
> +		cur->ivalue = value;
> +		cur->type = INTEGRAL;
> +	} else {
> +		/* If not a number, consider it enum value */
> +		cur->svalue = strdup(val);
> +		if (!cur->svalue)
> +			return -ENOMEM;
> +
> +		cur->type = ENUMERATOR;
> +	}
> +
> +	cur->name = strdup(var);
> +	if (!cur->name)
> +		return -ENOMEM;
> +
> +	(*cnt)++;
> +	return 0;
> +}

[...]