GeezerVison

"""Check that ctypes callbacks can be executed (gh-152433, Windows UWP).

Before the fix, the closure trampoline lives in PAGE_READWRITE memory, so
the first call into it raises:
    OSError: exception: access violation executing 0x...
After the fix, every check prints OK.
"""
import ctypes
import gc
import sys

INTFUNC = ctypes.CFUNCTYPE(ctypes.c_int, ctypes.c_int)
CMPFUNC = ctypes.CFUNCTYPE(ctypes.c_int,
                           ctypes.POINTER(ctypes.c_int),
                           ctypes.POINTER(ctypes.c_int))


def check(name, func):
    try:
        func()
    except Exception as exc:
        print(f"FAIL {name}: {type(exc).__name__}: {exc}")
        return False
    print(f"OK   {name}")
    return True


def call_through_pointer():
    # Calling the callback via its raw address forces execution of the
    # generated trampoline; no external DLL is needed.
    cb = INTFUNC(lambda x: x * 2)
    func = ctypes.cast(cb, INTFUNC)
    assert func(21) == 42, func(21)


def many_callbacks():
    # Allocate and free many closures to exercise the allocator.
    for i in range(1000):
        cb = INTFUNC(lambda x, i=i: x + i)
        assert ctypes.cast(cb, INTFUNC)(1) == i + 1
    gc.collect()


def qsort_from_crt():
    # C code calling back into Python.
    try:
        crt = ctypes.CDLL("ucrtbase")
    except OSError as exc:
        print(f"SKIP qsort (cannot load ucrtbase: {exc})")
        return
    values = (ctypes.c_int * 5)(5, 1, 4, 2, 3)
    cmp = CMPFUNC(lambda a, b: a[0] - b[0])
    crt.qsort(values, len(values), ctypes.sizeof(ctypes.c_int), cmp)
    assert list(values) == [1, 2, 3, 4, 5], list(values)


results = [
    check("call callback through pointer", call_through_pointer),
    check("create/free 1000 callbacks", many_callbacks),
    check("qsort with Python comparator", qsort_from_crt),
]

print("PASSED" if all(results) else "FAILED")