[lttng-dev] [LTTNG-TOOLS 2.4 RFC PATCH] Kernel consumer generate indexes

[Mathieu Desnoyers]

* Mathieu Desnoyers (mathieu.desnoyers at efficios.com) wrote:
> * Julien Desfossez (jdesfossez at efficios.com) wrote:
[...]
> > +static int create_index_file(struct lttng_consumer_stream *stream)
> > +{
> > +	char *index_name;
> > +	struct lttng_packet_index_file_hdr hdr;
> > +	int ret;
> > +
> > +	ret = asprintf(&index_name, "%s.idx", stream->name);
> > +	if (ret < 0) {
> > +		PERROR("Allocating index name");
> > +		goto error;
> > +	}
> > +	ret = utils_create_stream_file(stream->chan->pathname,
> > +			index_name, 0, 0, stream->uid,
> > +			stream->gid);
> > +	free(index_name);
> > +	if (ret < 0) {
> > +		goto error;
> > +	}
> > +
> > +	stream->index_fd = ret;
> > +	strncpy(hdr.magic, INDEX_MAGIC, sizeof(hdr.magic));
> 
> If you use strncpy, it's because you don't trust that INDEX_MAGIC will
> always fit within hdr.magic. If it is the case, then you should always
> do:
> 
> hdr.magic[sizeof(hdr.magic) - 1] = '\0';
> 
> after the strncpy.

In this case, you'll want to use a memcpy, since you clearly copy from a
fixed-sized to a fixed-sized area, which need to have both the same
size.

  memcpy(hdr.magic, INDEX_MAGIC, sizeof(hdr.magic));

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com