commands: only set ringbuffer datalen when needed

If we do it unconditionally a request to only clear the ringbuffer and not read
or write anything will fail.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/commands.c b/src/lxc/commands.c
index c158672ede6f0dd518f0f713d5c5e44511db66e3..759346b8b43e19afbf80873ec710caa4615e3c6c 100644 (file)
--- a/src/lxc/commands.c
+++ b/src/lxc/commands.c
@@ -1037,7 +1037,9 @@ static int lxc_cmd_console_log_callback(int fd, struct lxc_cmd_req *req,
        if (buffer_size <= 0)
                goto out;
 
-       rsp.datalen = lxc_ringbuf_used(buf);
+       if (log->read || log->write_logfile)
+               rsp.datalen = lxc_ringbuf_used(buf);
+
        if (log->read)
                rsp.data = lxc_ringbuf_get_read_addr(buf);