This provides mp_vfs_XXX functions (eg mount, open, listdir) which are
agnostic to the underlying filesystem type, and just require an object with
the relevant filesystem-like methods (eg .mount, .open, .listidr) which can
then be mounted.
These mp_vfs_XXX functions would typically be used by a port to implement
the "uos" module, and mp_vfs_open would be the builtin open function.
This feature is controlled by MICROPY_VFS, disabled by default.
If MICROPY_VFS_FAT is enabled by a port then the port must switch to using
MICROPY_FATFS_OO. Otherwise a port can continue to use the FatFs code
without any changes.
Previous to this patch the qemu-arm tests were compiled with is_relp=true
meaning that the __repl_print__ function was called for all lines of code
in the outer scope. This is not the right behaviour for scripts that are
executed as though they were a file (eg tests).
With this fix the micropython/heapalloc_str.py test now works so it is
removed from the test blacklist.
In this, don't allocate copy, just return non-empty string. This helps
with a standard pattern of buffering data in case of short reads:
buf = b""
while ...:
s = f.read(...)
buf += s
...
For a typical case when single read returns all data needed, there won't
be extra allocation. This optimization helps uasyncio.
They are one-line functions and having them inline in mp_init/mp_deinit
eliminates the overhead of a function call, and matches how other state
is initialised in mp_init.