MicroPython code may rely on the return value of sys.stdout.buffer.write()
to reflect the number of bytes actually written. While in most scenarios a
write() operation is successful, there are cases where it fails, leading to
data loss. This problem arises because, currently, write() merely returns
the number of bytes it was supposed to write, without indication of
failure.
One scenario where write() might fail, is where USB is used and the
receiving end doesn't read quickly enough to empty the receive buffer. In
that case, write() on the MicroPython side can timeout, resulting in the
loss of data without any indication, a behavior observed notably in
communication between a Pi Pico as a client and a Linux host using the ACM
driver.
A complex issue arises with mp_hal_stdout_tx_strn() when it involves
multiple outputs, such as USB, dupterm and hardware UART. The challenge is
in handling cases where writing to one output is successful, but another
fails, either fully or partially. This patch implements the following
solution:
mp_hal_stdout_tx_strn() attempts to write len bytes to all of the possible
destinations for that data, and returns the minimum successful write
length.
The implementation of this is complicated by several factors:
- multiple outputs may be enabled or disabled at compiled time
- multiple outputs may be enabled or disabled at runtime
- mp_os_dupterm_tx_strn() is one such output, optionally containing
multiple additional outputs
- each of these outputs may or may not be able to report success
- each of these outputs may or may not be able to report partial writes
As a result, there's no single strategy that fits all ports, necessitating
unique logic for each instance of mp_hal_stdout_tx_strn().
Note that addressing sys.stdout.write() is more complex due to its data
modification process ("cooked" output), and it remains unchanged in this
patch. Developers who are concerned about accurate return values from
write operations should use sys.stdout.buffer.write().
This patch might disrupt some existing code, but it's also expected to
resolve issues, considering that the peculiar return value behavior of
sys.stdout.buffer.write() is not well-documented and likely not widely
known. Therefore, it's improbable that much existing code relies on the
previous behavior.
Signed-off-by: Maarten van der Schrieck <maarten@thingsconnected.nl>
There are enough places that implement __exit__ by forwarding directly to
mp_stream_close that this saves code size.
For the cases where __exit__ is a no-op, additionally make their
MP_STREAM_CLOSE ioctl handled as a no-op.
This work was funded through GitHub Sponsors.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Instead of being an explicit field, it's now a slot like all the other
methods.
This is a marginal code size improvement because most types have a make_new
(100/138 on PYBV11), however it improves consistency in how types are
declared, removing the special case for make_new.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
The goal here is to remove a slot (making way to turn make_new into a slot)
as well as reduce code size by the ~40 references to mp_identity_getiter
and mp_stream_unbuffered_iter.
This introduces two new type flags:
- MP_TYPE_FLAG_ITER_IS_ITERNEXT: This means that the "iter" slot in the
type is "iternext", and should use the identity getiter.
- MP_TYPE_FLAG_ITER_IS_CUSTOM: This means that the "iter" slot is a pointer
to a mp_getiter_iternext_custom_t instance, which then defines both
getiter and iternext.
And a third flag that is the OR of both, MP_TYPE_FLAG_ITER_IS_STREAM: This
means that the type should use the identity getiter, and
mp_stream_unbuffered_iter as iternext.
Finally, MP_TYPE_FLAG_ITER_IS_GETITER is defined as a no-op flag to give
the default case where "iter" is "getiter".
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
stdio_obj_print is private to this file so can be made static. The __del__
method does nothing so can be removed (it's only called by the GC if it
exists, so if it doesn't exist it won't be called). And FileIO doesn't
support a constructor in MicroPython at this stage.
Signed-off-by: Damien George <damien@micropython.org>
This commit moves all first-party code developed for this project from lib/
to shared/, so that lib/ now only contains third-party code.
The following directories are moved as-is from lib to shared:
lib/libc -> shared/libc
lib/memzip -> shared/memzip
lib/netutils -> shared/netutils
lib/timeutils -> shared/timeutils
lib/upytesthelper -> shared/upytesthelper
All files in lib/embed/ have been moved to shared/libc/.
lib/mp-readline has been moved to shared/readline.
lib/utils has been moved to shared/runtime, with the exception of
lib/utils/printf.c which has been moved to shared/libc/printf.c.
Signed-off-by: Damien George <damien@micropython.org>
Maarten van der Schrieck
Jim Mussared
Damien George