The code_state.old_globals variable is there to save the globals state so
should be used for this purpose, to avoid the need for additional local
variables on the C stack.
This patch allows to use lwIP as the implementation of the usocket module,
instead of the existing socket-multiplexer that delegates the entire TCP/IP
layer to the NIC itself.
This is disabled by default, and enabled by defining MICROPY_PY_LWIP to 1.
When enabled, the lwIP TCP/IP stack will be included in the build with
default settings for memory usage and performance (see
lwip_inc/lwipopts.h). It is then up to a particular NIC to register itself
with lwIP using the standard lwIP netif API.
Without this, if GC threshold is hit and there is not enough memory left to
satisfy the request, gc_collect() will run a second time and the search for
memory will happen again and will fail again.
Thanks to @adritium for pointing out this issue, see #3786.
Under ubsan, when evaluating hash(-0.) the following diagnostic occurs:
../../py/objfloat.c:102:15: runtime error: negation of
-9223372036854775808 cannot be represented in type 'mp_int_t' (aka
'long'); cast to an unsigned type to negate this value to itself
So do just that, to tell the compiler that we want to perform this
operation using modulo arithmetic rules.
Before this, ubsan would detect a problem when executing
hash(006699999999999999999999999999999999999999999999999999999999999999999999)
../../py/mpz.c:1539:20: runtime error: left shift of 1067371580458 by
32 places cannot be represented in type 'mp_int_t' (aka 'long')
When the overflow does occur it now happens as defined by the rules of
unsigned arithmetic.
When computing e.g. hash(0.4e3) with ubsan enabled, a diagnostic like the
following would occur:
../../py/objfloat.c:91:30: runtime error: shift exponent 44 is too
large for 32-bit type 'int'
By casting constant "1" to the right type the intended value is preserved.
Fuzz testing combined with the undefined behavior sanitizer found that
parsing unreasonable float literals like 1e+9999999999999 resulted in
undefined behavior due to overflow in signed integer arithmetic, and a
wrong result being returned.
Damien George
Jan Klusacek
Daniel Shaulov
Jeff Epler