g_assert(group->len > 0);
tf = &g_array_index (group, LttTracefile, 0);
header = (struct ltt_block_start_header*)tf->buffer.head;
g_assert(group->len > 0);
tf = &g_array_index (group, LttTracefile, 0);
header = (struct ltt_block_start_header*)tf->buffer.head;