function instead of the getentropy() function. The getentropy() function is
blocking to generate very good quality entropy, os.urandom() doesn't need such
high-quality entropy.
On Windows, the tv_sec field of the timeval structure has the type C long,
whereas it has the type C time_t on all other platforms. A C long has a size of
32 bits (signed inter, 1 bit for the sign, 31 bits for the value) which is not
enough to store an Epoch timestamp after the year 2038.
Add the _PyTime_AsTimevalTime_t() function written for datetime.datetime.now():
convert a _PyTime_t timestamp to a (secs, us) tuple where secs type is time_t.
It allows to support dates after the year 2038 on Windows.
Enhance also _PyTime_AsTimeval_impl() to detect overflow on the number of
seconds when rounding the number of microseconds.
Issue #24891: Fix a race condition at Python startup if the file descriptor
of stdin (0), stdout (1) or stderr (2) is closed while Python is creating
sys.stdin, sys.stdout and sys.stderr objects. These attributes are now set
to None if the creation of the object failed, instead of raising an OSError
exception. Initial patch written by Marco Paolini.
Don't check anymore at runtime that the monotonic clock doesn't go backward.
Yes, it happens. It occurs sometimes each month on a Debian buildbot slave
running in a VM.
The problem is that Python cannot do anything useful if a monotonic clock goes
backward. It was decided in the PEP 418 to not fix the system, but only expose
the clock provided by the OS.
See the latest version of getrandom() manual page:
http://man7.org/linux/man-pages/man2/getrandom.2.html#NOTES
The behavior when a call to getrandom() that is blocked while reading from
/dev/urandom is interrupted by a signal handler depends on the
initialization state of the entropy buffer and on the request size, buflen.
If the entropy is not yet initialized, then the call will fail with the
EINTR error. If the entropy pool has been initialized and the request size
is large (buflen > 256), the call either succeeds, returning a partially
filled buffer, or fails with the error EINTR. If the entropy pool has been
initialized and the request size is small (buflen <= 256), then getrandom()
will not fail with EINTR. Instead, it will return all of the bytes that
have been requested.
Note: py_getrandom() calls getrandom() with flags=0.
