Re: [PATCH 1/7] ndctl: cxl: add helper function to parse trace event to json object

[Alison Schofield <alison.schofield@intel.com>]

On Wed, Sep 14, 2022 at 01:47:55PM -0700, Dave Jiang wrote:
> Add the helper function that parses a trace event captured by
> libtraceevent in a tep handle. All the parsed fields are added to a json
> object. The json object is added to the provided list in the input parameter.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Hi Dave,

I've been using these parsing patches, and it all works for the purpose 
of parsing the cxl device poison list.

Tested-by: Alison Schofield <alison.schofield@intel.com>

One comment below...

-snip-

> ---
> +
> +	for (i = 0; fields[i]; i++) {
> +		struct tep_format_field *f = fields[i];
> +		int len;
> +		char *tmp;
> +
> +		tmp = strcasestr(f->type, "char[]");
> +		if (tmp) { /* event field is a string */
> +			char *str;
> +
> +			str = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
> +			if (!str)
> +				continue;
> +
> +			jobj = json_object_new_string(str);
> +			if (!jobj) {
> +				rc = -ENOMEM;
> +				goto err;
> +			}
> +
> +			json_object_object_add(jevent, f->name, jobj);
> +		} else if (f->arraylen) { /* data array */
> +			unsigned char *data;
> +			int chunks;
> +
> +			data = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
> +			if (!data)
> +				continue;
> +
> +			/* check to see if we have a UUID */
> +			tmp = strcasestr(f->name, "uuid");
> +			if (tmp && f->arraylen == 16) {
> +				char uuid[SYSFS_ATTR_SIZE];
> +
> +				uuid_unparse(data, uuid);
> +				jobj = json_object_new_string(uuid);
> +				if (!jobj) {
> +					rc = -ENOMEM;
> +					goto err;
> +				}
> +
> +				json_object_object_add(jevent, f->name, jobj);
> +				continue;
> +			}

Insted of comparing the field name, is it possible to check for
f->type of 'uuid_t'?


> +
> +			jarray = json_object_new_array();
> +			if (!jarray) {
> +				rc = -ENOMEM;
> +				goto err;
> +			}
> +
> +			chunks = f->size / f->elementsize;
> +			for (j = 0; j < chunks; j++) {
> +				jobj = num_to_json(data, f->elementsize);
> +				if (!jobj) {
> +					json_object_put(jarray);
> +					return -ENOMEM;
> +				}
> +				json_object_array_add(jarray, jobj);
> +				data += f->elementsize;
> +			}
> +
> +			json_object_object_add(jevent, f->name, jarray);
> +		} else { /* single number */
> +			char *data;
> +
> +			data = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
> +			if (!data)
> +				continue;
> +
> +			jobj = num_to_json(data, f->elementsize);
> +			if (!jobj) {
> +				rc = -ENOMEM;
> +				goto err;
> +			}
> +
> +			json_object_object_add(jevent, f->name, jobj);
> +		}
> +	}
> +
> +	list_add_tail(jlist_head, &jnode->list);
> +	return 0;
> +
> +err:
> +	json_object_put(jevent);
> +err_jevent:
> +	free(jnode);
> +	return rc;
> +}

snip