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 58a2009cc1
Fix unix build 2019-01-18 12:52:27 -08:00
Damien George b02be234e1 extmod/machine_pinbase: Put PinBase singleton in ROM.
This patch also removes the empty type "pinbase_type" (which crashes if
accessed) and uses "machine_pinbase_type" instead as the type of the
PinBase singleton.
2017-09-12 16:00:21 +10:00
Paul Sokolovsky efee577318 extmod/machine_pinbase: Fix nanbox build.
MP_ROM_PTR() is only for data structures initialization, code should use
MP_OBJ_FROM_PTR().
2016-06-19 00:26:57 +03:00
Paul Sokolovsky 3fecbb2462 extmod/machine_pinbase: Implementation of PinBase class.
Allows to translate C-level pin API to Python-level pin API. In other
words, allows to implement a pin class and Python which will be usable
for efficient C-coded algorithms, like bitbanging SPI/I2C, time_pulse,
etc.
2016-06-18 23:40:28 +03:00