Commit Graph

5 Commits

Author SHA1 Message Date
Jeff Epler 238e121236 protocols: Allow them to be (optionally) type-safe
Protocols are nice, but there is no way for C code to verify whether
a type's "protocol" structure actually implements some particular
protocol.  As a result, you can pass an object that implements the
"vfs" protocol to one that expects the "stream" protocol, and the
opposite of awesomeness ensues.

This patch adds an OPTIONAL (but enabled by default) protocol identifier
as the first member of any protocol structure.  This identifier is
simply a unique QSTR chosen by the protocol designer and used by each
protocol implementer.  When checking for protocol support, instead of
just checking whether the object's type has a non-NULL protocol field,
use `mp_proto_get` which implements the protocol check when possible.

The existing protocols are now named:
    protocol_framebuf
    protocol_i2c
    protocol_pin
    protocol_stream
    protocol_spi
    protocol_vfs
(most of these are unused in CP and are just inherited from MP; vfs and
stream are definitely used though)

I did not find any crashing examples, but here's one to give a flavor of what
is improved, using `micropython_coverage`.  Before the change,
the vfs "ioctl" protocol is invoked, and the result is not intelligible
as json (but it could have resulted in a hard fault, potentially):

    >>> import uos, ujson
    >>> u = uos.VfsPosix('/tmp')
    >>> ujson.load(u)
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    ValueError: syntax error in JSON

After the change, the vfs object is correctly detected as not supporting
the stream protocol:
    >>> ujson.load(p)
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    OSError: stream operation not supported
2019-12-04 09:29:57 -06:00
Scott Shawcroft b569e8bab0
More make_new updates 2019-01-18 17:09:56 -08:00
Scott Shawcroft 96534e598e
Fix unix coverage and update translations. 2018-08-16 17:41:53 -07:00
Dan Halbert 0d27f4d9a6 continued WIP: almost compiling 2018-07-12 14:13:51 -04:00
Damien George 8d82b0edbd extmod: Add VfsPosix filesystem component.
This VFS component allows to mount a host POSIX filesystem within the uPy
VFS sub-system.  All traditional POSIX file access then goes through the
VFS, allowing to sandbox a uPy process to a certain sub-dir of the host
system, as well as mount other filesystem types alongside the host
filesystem.
2018-06-06 14:28:23 +10:00