If the _IRQ_L2CAP_RECV handler does the actual consumption of the incoming
data (i.e. via l2cap_recvinto), rather than setting a flag for
non-scheduler-context to handle it later, then two things can happen:
- It can starve the VM (i.e. the scheduled task never terminates). This is
because calling l2cap_recvinto will empty the rx buffer, which will grant
more credits to the channel (an HCI command), meaning more data can
arrive. This means that the loop in hal_uart.c that keeps reading HCI
data from the uart and executing NimBLE events as they are created will
not terminate, preventing other VM code from running.
- There's no flow control (i.e. data will arrive too quickly). The channel
shouldn't be given credits until after we return from scheduler context.
It's preferable that no work is done in scheduler/IRQ context. But to
prevent this being a problem this commit changes l2cap_recvinto so that if
it is called in IRQ context, and the Python handler empties the rx buffer,
then don't grant credits until the Python handler is complete.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
These args are already bounds checked and clipped, and using unsigned ints
can be more efficient. It also eliminates possible issues and compiler
warnings with shifting of signed integers.
Signed-off-by: Damien George <damien@micropython.org>
The superblock for littlefs is in block 0 and 1, but block 0 may be erased
or partially written, so block 1 must be checked if block 0 does not have a
valid littlefs superblock in it.
Prior to this commit, the mount of a block device which auto-detected the
filysystem type would fail for littlefs if block 0 did not contain a valid
superblock. That is now fixed.
Signed-off-by: Damien George <damien@micropython.org>
This allows sending arbitrary HCI commands and getting the response. The
return value of the function is the status of the command.
This is intended for debugging and not to be a part of the public API, and
must be enabled via mpconfigboard.h. It's currently only implemented for
NimBLE bindings.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This commit prevents uos.mount() from raising an AttributeError.
vfs_autodetect() is supposed to return an object that has a "mount" method,
so if no filesystem is found it should raise an OSError(ENODEV) and not
return the bdev itself which has no "mount" method.
Since CPython 3.8 the optional "sep" argument to hexlify is officially
supported, so update comments in the code and the docs to reflect this.
Signed-off-by: Damien George <damien@micropython.org>
Rather than dealing with the different int types, just pass them all as a
single array of mp_int_t with n_unsigned (before addr) and n_signed (after
addr).
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This adds `_IRQ_GET_SECRET` and `_IRQ_SET_SECRET` events to allow the BT
stack to request the Python code retrive/store/delete secret key data. The
actual keys and values are opaque to Python and stack-specific.
Only NimBLE is implemented (pending moving btstack to sync events). The
secret store is designed to be compatible with BlueKitchen's TLV store API.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This allows the application to be notified if any of encrypted,
authenticated and bonded state change, as well as the encryption key size.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Enable it on STM32/Unix NimBLE only (pairing/bonding requires synchronous
events and full bindings).
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Instead of returning None/bool from the IRQ, return None/int (where a zero
value means success). This mirrors how the L2CAP_ACCEPT return value
works.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This widens the characteristic/descriptor flags to 16-bit, to allow setting
encryption/authentication requirements.
Sets the required flags for NimBLE and btstack implementations.
The BLE.FLAG_* constants will eventually be deprecated in favour of copy
and paste Python constants (like the IRQs).
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This allows the application to be notified of changes to the connection
interval, connection latency and supervision timeout.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This commit switches the roles of the helper task from a cancellation task
to a runner task, to get the correct semantics for cancellation of
wait_for.
Some uasyncio tests are now disabled for the native emitter due to issues
with native code generation of generators and yield-from.
Fixes#5797.
Signed-off-by: Damien George <damien@micropython.org>
This is added because task.coro==None is no longer the way to detect if a
task is finished. Providing a (CPython compatible) function for this
allows the implementation to be abstracted away.
Signed-off-by: Damien George <damien@micropython.org>
When a tasks raises an exception which is uncaught, and no other task
await's on that task, then an error message is printed (or a user function
called) via a call to Loop.call_exception_handler. In CPython this call is
made when the Task object is freed (eg via reference counting) because it's
at that point that it is known that the exception that was raised will
never be handled.
MicroPython does not have reference counting and the current behaviour is
to deal with uncaught exceptions as early as possible, ie as soon as they
terminate the task. But this can be undesirable because in certain cases
a task can start and raise an exception immediately (before any await is
executed in that task's coro) and before any other task gets a chance to
await on it to catch the exception.
This commit changes the behaviour so that tasks which end due to an
uncaught exception are scheduled one more time for execution, and if they
are not await'ed on by the next scheduling loop, then the exception handler
is called (eg the exception is printed out).
Signed-off-by: Damien George <damien@micropython.org>
Disable certain classes of diagnostic when building ulab. We should
submit patches upstream to (A) fix these errors and (B) upgrade their
CI so that the problems are caught before we want to integrate with
CircuitPython, but not right now.
Also known as L2CAP "connection oriented channels". This provides a
socket-like data transfer mechanism for BLE.
Currently only implemented for NimBLE on STM32 / Unix.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Hardware I2C implementations must provide a .init() protocol method if they
want to support reconfiguration. Otherwise the default is that i2c.init()
raises an OSError (currently the case for all ports).
mp_machine_soft_i2c_locals_dict is renamed to mp_machine_i2c_locals_dict to
match the generic SPI bindings.
Fixes issue #6623 (where calling .init() on a HW I2C would crash).
Signed-off-by: Damien George <damien@micropython.org>
This changes stm32 from using PENDSV to run NimBLE to use the MicroPython
scheduler instead. This allows Python BLE callbacks to be invoked directly
(and therefore synchronously) rather than via the ringbuffer.
The NimBLE UART HCI and event processing now happens in a scheduled task
every 128ms. When RX IRQ idle events arrive, it will also schedule this
task to improve latency.
There is a similar change for the unix port where the background thread now
queues the scheduled task.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This requires that the event handlers are called from non-interrupt context
(i.e. the MicroPython scheduler).
This will allow the BLE stack (e.g. NimBLE) to run from the scheduler
rather than an IRQ like PENDSV, and therefore be able to invoke Python
callbacks directly/synchronously. This allows writing Python BLE handlers
for events that require immediate response such as _IRQ_READ_REQUEST (which
was previous a hard IRQ) and future events relating to pairing/bonding.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Using a semaphore (the previous approach) will only run the UART, whereas
for startup we need to also run the event queue.
This change makes it run the full scheduler hook.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Instead of having the stack indicate a "start", "data"..., "end", pass
through the data in one callback as an array of chunks of data.
This is because the upcoming non-ringbuffer modbluetooth implementation
cannot buffer the data in the ringbuffer and requires instead a single
callback with all the data, to pass to the Python callback.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Prior to this change machine.mem32['foo'] (or using any other non-integer
subscript) could result in a fault due to 'foo' being interpreted as an
integer. And when writing code it's hard to tell if the fault is due to a
bad subscript type, or an integer subscript that specifies an invalid
memory address.
The type of the object used in the subscript is now tested to be an
integer by using mp_obj_get_int_truncated instead of
mp_obj_int_get_truncated. The performance hit of this change is minimal,
and machine.memX objects are more for convenience than performance (there
are many other ways to read/write memory in a faster way),
Fixes issue #6588.
If a port provides MICROPY_PY_URANDOM_SEED_INIT_FUNC as a source of
randomness then this will be used when urandom.seed() is called without
an argument (or with None as the argument) to seed the pRNG.
Other related changes in this commit:
- mod_urandom___init__ is changed to call seed() without arguments, instead
of explicitly passing in the result of MICROPY_PY_URANDOM_SEED_INIT_FUNC.
- mod_urandom___init__ will only ever seed the pRNG once (before it could
seed it again if imported by, eg, random and then urandom).
- The Yasmarang state is moved to the BSS for builds where the state is
guaranteed to be initialised on import of the (u)random module.
Signed-off-by: Damien George <damien@micropython.org>
.. pull in various doc build fixes that prevented the previous commit from building. This is still "0.54.5", the tag was updated in micropython-ulab (since no functional difference was introduced, only doc and CI differences, I imagine)
Newer GCC versions are able to warn about switch cases that fall
through. This is usually a sign of a forgotten break statement, but in
the few cases where a fall through is intended we annotate it with this
macro to avoid the warning.
When compiling with -Wextra which includes -Wmissing-field-initializers
GCC will warn that the defval field of mp_arg_val_t is not initialized.
This is just a warning as it is defined to be zero initialized, but since
it is a union it makes sense to be explicit about which member we're
going to use, so add the explicit initializers and get rid of the
warning.
This unifies the flash config to the settings used by the Boot ROM.
This makes the config unique per board which allows for changing
quad enable and status bit differences per flash device. It also
allows for timing differences due to the board layout.
This change also tweaks linker layout to leave more ram space for
the CircuitPython heap.
It requires mp_hal_time_ns() to be provided by a port. This function
allows very accurate absolute timestamps.
Enabled on unix, windows, stm32, esp8266 and esp32.
Signed-off-by: Damien George <damien@micropython.org>
With a warning that this way of constructing software I2C/SPI is
deprecated. The check and warning will be removed in a future release.
This should help existing code to migrate to the new SoftI2C/SoftSPI types.
Signed-off-by: Damien George <damien@micropython.org>
The SoftSPI constructor is now used soley to create SoftSPI instances, it
can no longer delegate to create a hardware-based SPI instance.
Signed-off-by: Damien George <damien@micropython.org>
The SoftI2C constructor is now used soley to create SoftI2C instances, it
can no longer delegate to create a hardware-based I2C instance.
Signed-off-by: Damien George <damien@micropython.org>
Also rename machine_i2c_type to mp_machine_soft_i2c_type. These changes
make it clear that it's a soft-I2C implementation, and match SoftSPI.
Signed-off-by: Damien George <damien@micropython.org>
A read-only memoryview object is a better representation of the data, which
is owned by the ubluetooth module and may change between calls to the
user's irq callback function.
Signed-off-by: Damien George <damien@micropython.org>
Prior to this commit, uos.chdir('/') followed by uos.stat('noexist') would
succeed that stat even though the entry did not exist (some other functions
like listdir would have similar issues). This is because, if the current
directory was the root and the path was relative, mp_vfs_lookup_path would
return success for bad paths.
Signed-off-by: Damien George <damien@micropython.org>
For time-based functions that work with absolute time there is the need for
an Epoch, to set the zero-point at which the absolute time starts counting.
Such functions include time.time() and filesystem stat return values. And
different ports may use a different Epoch.
To make it clearer what functions use the Epoch (whatever it may be), and
make the ports more consistent with their use of the Epoch, this commit
renames all Epoch related functions to include the word "epoch" in their
name (and remove references to "2000").
Along with this rename, the following things have changed:
- mp_hal_time_ns() is now specified to return the number of nanoseconds
since the Epoch, rather than since 1970 (but since this is an internal
function it doesn't change anything for the user).
- littlefs timestamps on the esp8266 have been fixed (they were previously
off by 30 years in nanoseconds).
Otherwise, there is no functional change made by this commit.
Signed-off-by: Damien George <damien@micropython.org>
For the following 3 functions, previously the code relied on whether the
arg was passed at all, to make it optional. Now it allows them to be
explicitly `None` to indicate they are not used:
- gatts_notify(..., [data])
- gattc_discover_services(..., [uuid])
- gattc_discover_characteristics(..., [uuid])
Also ensure that the uuid arguments are actually instances of the uuid
type, and fix handling of the 5th arg in gattc_discover_characteristics().
This allows `ble.active(1)` to fail correctly if the HCI controller is
unavailable.
It also avoids an infine loop in the NimBLE event handler where NimBLE
doesn't correctly detect that the HCI controller is unavailable and keeps
trying to reset.
Furthermore, it fixes an issue where GATT service registrations were left
allocated, which led to a bad realloc if the stack was activated multiple
times.
Generally a controller should either have its own public address hardcoded,
or loaded by the driver (e.g. cywbt43).
However, for a controller that has no public address where you still want a
long-term stable address, this allows you to use a static address generated
by the port. Typically on STM32 this will be an LAA, but a board might
override this.
This commit adds support for using Bluetooth on the unix port via a H4
serial interface (distinct from a USB dongle), with both BTstack and NimBLE
Bluetooth stacks.
Note that MICROPY_PY_BLUETOOTH is now disabled for the coverage variant.
Prior to this commit Bluetooth was anyway not being built on Travis because
libusb was not detected. But now that bluetooth works in H4 mode it will
be built, and will lead to a large decrease in coverage because Bluetooth
tests cannot be run on Travis.
Previously the interaction between the different layers of the Bluetooth
stack was different on each port and each stack. This commit defines
common interfaces between them and implements them for cyw43, btstack,
nimble, stm32, unix.
This is consistent with the other 'micro' modules and allows implementing
additional features in Python via e.g. micropython-lib's sys.
Note this is a breaking change (not backwards compatible) for ports which
do not enable weak links, as "import sys" must now be replaced with
"import usys".
By setting MICROPY_EPOCH_IS_1970 a port can opt to use 1970/1/1 as the
Epoch for timestamps returned by stat(). And this setting is enabled on
the unix and windows ports because that's what they use.
Signed-off-by: Damien George <damien@micropython.org>
On ports like unix where the Epoch is 1970/1/1 and atime/mtime/ctime are in
seconds since the Epoch, this value will overflow a small-int on 32-bit
systems. So far this is only an issue on 32-bit unix builds that use the
VFS layer (eg dev and coverage unix variants) but the fix (using
mp_obj_new_int_from_uint instead of MP_OBJ_NEW_SMALL_INT) is there for all
ports so as to not complicate the code, and because they will need the
range one day.
Also apply a similar fix to other fields in VfsPosix.stat because they may
also be large.
Signed-off-by: Damien George <damien@micropython.org>
This commit fixes the cases when a TCP socket is in STATE_NEW,
STATE_LISTENING or STATE_CONNECTING and recv() is called on it. It now
raises ENOTCONN instead of a random error code due to it previously
indexing beyond the start of error_lookup_table[].
Signed-off-by: Damien George <damien@micropython.org>
Updating to Black v20.8b1 there are two changes that affect the code in
this repository:
- If there is a trailing comma in a list (eg [], () or function call) then
that list is now written out with one line per element. So remove such
trailing commas where the list should stay on one line.
- Spaces at the start of """ doc strings are removed.
Signed-off-by: Damien George <damien@micropython.org>
The memory operation functions read_mem() and write_mem() create a
temporary buffer on the local C stack for the address bytes with the size
of 4 bytes. This buffer is filled in a loop from the user supplied address
and address length. If the user supplied 'addrsize' is bigger than 32, the
local buffer is overrun.
Fix this by raising an exception for invalid 'addrsize' values.
Signed-off-by: Michael Buesch <m@bues.ch>
This adds an additional optional parameter to gap_scan() to select active
scanning, where scan responses are returned as well as normal scan results.
This parameter is False by default which retains the existing behaviour.
The READ_REQUEST callback is handled as a hard interrupt (because the BLE
stack needs an immediate response from it so it can continue) and so calls
to Python require extra protection:
- the caller-owned tuple passed into the callback must be separate from the
tuple used by other callback events (which are soft interrupts);
- the GC and scheduler must be locked during callback execution.
This commit adds support for modification time of files on littlefs v2
filesystems, using file attributes. For some background see issue #6114.
Features/properties of this implementation:
- Only supported on littlefs2 (not littlefs1).
- Uses littlefs2's general file attributes to store the timestamp.
- The timestamp is 64-bits and stores nanoseconds since 1970/1/1 (if the
range to the year 2554 is not enough then additional bits can be added to
this timestamp by adding another file attribute).
- mtime is enabled by default but can be disabled in the constructor, eg:
uos.mount(uos.VfsLfs2(bdev, mtime=False), '/flash')
- It's fully backwards compatible, existing littlefs2 filesystems will work
without reformatting and timestamps will be added transparently to
existing files (once they are opened for writing).
- Files without timestamps will open correctly, and stat will just return 0
for their timestamp.
- mtime can be disabled or enabled each mount time and timestamps will only
be updated if mtime is enabled (otherwise they will be untouched).
Signed-off-by: Damien George <damien@micropython.org>
Otherwise a task that continuously awaits on a large negative sleep can
monopolise the scheduler (because its wake time is always less than
everything else in the pairing heap).
Signed-off-by: Damien George <damien@micropython.org>
mp_reader_new_file() is used to read in files for importing, either .py or
.mpy files, for the lexer and persistent code loader respectively. In both
cases the file should be opened in raw bytes mode: the lexer handles
unicode characters itself, and .mpy files contain 8-bit bytes by nature.
Before this commit importing was working correctly because, although the
file was opened in text mode, all native filesystem implementations (POSIX,
FAT, LFS) would access the file in raw bytes mode via mp_stream_rw()
calling mp_stream_p_t.read(). So it was only an issue for non-native
filesystems, such as those implemented in Python. For Python-based
filesystem implementations, a call to mp_stream_rw() would go via IOBase
and then to readinto() at the Python level, and readinto() is only defined
on files opened in raw bytes mode.
Signed-off-by: Damien George <damien@micropython.org>
This version
* moves source files to reflect module structure
* adds inline documentation suitable for extract_pyi
* incompatibly moves spectrogram to fft
* incompatibly removes "extras"
There are some remaining markup errors in the specific revision of
extmod/ulab but they do not prevent the doc building process from
completing.
It raises on EOFError instead of an IncompleteReadError (which is what
CPython does). But the latter is derived from EOFError so code compatible
with MicroPython and CPython can be written by catching EOFError (eg see
included test).
Fixes issue #6156.
Signed-off-by: Damien George <damien@micropython.org>
This commit adds human readable error messages when mbedtls or axtls raise
an exception. Currently often just an EIO error is raised so the user is
lost and can't tell whether it's a cert error, buffer overrun, connecting
to a non-ssl port, etc. The axtls and mbedtls error raising in the ussl
module is modified to raise:
OSError(-err_num, "error string")
For axtls a small error table of strings is added and used for the second
argument of the OSErrer. For mbedtls the code uses mbedtls' built-in
strerror function, and if there is an out of memory condition it just
produces OSError(-err_num). Producing the error string for mbedtls is
conditional on them being included in the mbedtls build, via
MBEDTLS_ERROR_C.
This commit adds the IRQ_GATTS_INDICATE_DONE BLE event which will be raised
with the status of gatts_indicate (unlike notify, indications require
acknowledgement).
An example of its use is added to ble_temperature.py, and to the multitests
in ble_characteristic.py.
Implemented for btstack and nimble bindings, tested in both directions
between unix/btstack and pybd/nimble.
The goal of this commit is to allow using ble.gatts_notify() at any time,
even if the stack is not ready to send the notification right now. It also
addresses the same issue for ble.gatts_indicate() and ble.gattc_write()
(without response). In addition this commit fixes the case where the
buffer passed to write-with-response wasn't copied, meaning it could be
modified by the caller, affecting the in-progress write.
The changes are:
- gatts_notify/indicate will now run in the background if the ACL buffer is
currently full, meaning that notify/indicate can be called at any time.
- gattc_write(mode=0) (no response) will now allow for one outstanding
write.
- gattc_write(mode=1) (with response) will now copy the buffer so that it
can't be modified by the caller while the write is in progress.
All four paths also now track the buffer while the operation is in
progress, which prevents the GC free'ing the buffer while it's still
needed.
With only `sp_func_proto_paren = remove` set there are some cases where
uncrustify misses removing a space between the function name and the
opening '('. This sets all of the related options to `force` as well.
The ring buffer previously used a single unsigned byte field to save the
length, meaning that it would overflow for large characteristic value
responses.
With this commit it now use a 16-bit length instead and has code to
explicitly truncate at UINT16_MAX (although this should be impossible to
achieve in practice).
This commit makes sure that all discovery complete and read/write status
events set the status to zero on success.
The status value will be implementation-dependent on non-success cases.
On btstack there's no status associated with the read result, it comes
through as a separate event. This allows you to detect read failures or
timeouts.
There doesn't appear to be any use for only triggering on specific events,
so it's just easier to number them sequentially. This makes them smaller
values so they take up only 1 byte in the ringbuf, only 1 byte for the
opcode in the bytecode, and makes room for more events.
Also add a couple of new event types that need to be implemented (to avoid
re-numbering later).
And rename _COMPLETE and _STATUS to _DONE for consistency.
In the future the "trigger" keyword argument can be reinstated by requiring
the user to compute the bitmask, eg:
ble.irq(handler, 1 << _IRQ_SCAN_RESULT | 1 << _IRQ_SCAN_DONE)
Before this change, any NimBLE error that does not appear in the
ble_hs_err_to_errno_table maps to return code 0, meaning success. If we
miss adding an error code to the table we end up returning success in case
of failure.
Instead, handle the zero case explicitly and default to MP_EIO. This
allows removing the now-redundant MP_EIO entries from the mapping.
This commit allows the user to set/get the GAP device name used by service
0x1800, characteristic 0x2a00. The usage is:
BLE.config(gap_name="myname")
print(BLE.config("gap_name"))
As part of this change the compile-time setting
MICROPY_PY_BLUETOOTH_DEFAULT_NAME is renamed to
MICROPY_PY_BLUETOOTH_DEFAULT_GAP_NAME to emphasise its link to GAP and this
new "gap_name" config value. And the default value of this for the NimBLE
bindings is changed from "PYBD" to "MPY NIMBLE" to be more generic.
Ujson should only worry about whitespace before JSON. This becomes apparent when you are using MP stream protocol to read directly from input buffers.
When you attempt to read(1) on a UART (and possibly other protocols) you have to wait for either the byte or the timeout.
Fixes:
- Waiting for a timeout after you have completed reading a correct and complete JSON off the input.
- Raising an OSError after reading a correct and complete JSON off the input.
- Eating more data than semantically owned off the input buffer.
- Blocking to start parsing JSON until the entire JSON body has been loaded into a potentially large, contiguous Python object.
Code you would write before:
```
line = board_busio_uart_port.read_line()
json_dict = json.loads(line)
```
or reaching for fixed buffers and swapping them around in Python.
Code that did not work before that does now:
```
json_dict = json.load(board_busio_uart_port)
```
- This removes the need for intermediate copies of data when reading JSON from micropython stream protocol inputs.
- It also increases total application speed by parsing JSON concurrently with receiving on boards that read from UART via DMA.
- It simplifies code that users write while improving their apps.
If the new name start with '/', cur_dir is not prepened any more, so that
the current working directory is respected. And extend the test cases for
rename to cover this functionality.
This change scans for '.', '..' and multiple '/' and normalizes the new
path name. If the resulting path does not exist, an error is raised.
Non-existing interim path elements are ignored if they are removed during
normalization.
This fixes the bug, that stat(filename) would not consider the current
working directory. So if e.g. the cwd is "lib", then stat("main.py") would
return the info for "/main.py" instead of "/lib/main.py".
For ports that have a system malloc which is not garbage collected (eg
unix, esp32), the stream object for the DB must be retained separately to
prevent it from being reclaimed by the MicroPython GC (because the
berkeley-db library uses malloc to allocate the DB structure which stores
the only reference to the stream).
Although in some cases the user code will explicitly retain a reference to
the underlying stream because it needs to call close() on it, this is not
always the case, eg in cases where the DB is intended to live forever.
Fixes issue #5940.
But only when bluetooth is enabled, i.e. if building the dev or coverage
variants, and we have libusb available.
Update travis to match, i.e. specify the variant when doing
`make submodules`.
This commit adds full support to the unix port for Bluetooth using the
common extmod/modbluetooth Python bindings. This uses the libusb HCI
transport, which supports many common USB BT adaptors.
This change is made for two reasons:
1. A 3rd-party library (eg berkeley-db-1.xx, axtls) may use the system
provided errno for certain errors, and yet MicroPython stream objects
that it calls will be using the internal mp_stream_errno. So if the
library returns an error it is not known whether the corresponding errno
code is stored in the system errno or mp_stream_errno. Using the system
errno in all cases (eg in the mp_stream_posix_XXX wrappers) fixes this
ambiguity.
2. For systems that have threading the system-provided errno should always
be used because the errno value is thread-local.
For systems that do not have an errno, the new lib/embed/__errno.c file is
provided.
