The plan is that names in littlefs now include a directory-id prefixed
as a single leb128.
01 66 69 6c 65 2e 74 78 74 .file.txt
^ '----------+----------'
'------------|------------ leb128 directory-id
'------------ ascii/utf8 name
Unfortunately, while this is easy for read/compare operations to implement,
it creates a bit of a problem for writes. We can't allocate a new buffer
for each name, so we need some sort of extra mechanism.
The solution here is to just add a did member to lfsr_data_t that is
written when non-negative. This works, though it does introduce some
complexity.
Fortunately, did in lfsr_data_t is somewhat free when
sizeof(void*) == sizeof(lfs_size_t), due to the union with disk
references.
It doesn't make sense to test more complex logic, such as t2_btree.toml,
when the logic it is built on, t1_rbyd.toml, does not past testing. The
test runner already guarantees a consistent lexicographic order, so all
we need to do is renamed these from test_* -> tn_*.
Note, if we every have more than 10 tests, we will need to bump up the
number of digits for all tests, so t1_rbyd.toml -> t01_rbyd.toml. This
is the main downside of lexicographic ordering. But we'll cross that
bridge when we get to it.