[OpenBSD] Process num_fds() and open_files() may raise NSP for PID 0

[giampaolo]

This is weird, because of all the sudden the tests below started failing. This is despite PID 0 exists. The syscall failing with ESRCH is kinfo_getfile:

psutil/psutil/arch/openbsd/proc.c

Line 57 in f8b929b

kinfo_getfile(pid_t pid, int* cnt) {

We therefore return "null" fallback values instead of raising NoSuchProcess.

=================================== FAILURES ===================================
___________________________ TestProcess.test_as_dict ___________________________
psutil/_psbsd.py:604: in wrapper
    return fun(self, *args, **kwargs)
psutil/_psbsd.py:914: in open_files
    rawlist = cext.proc_open_files(self.pid)
E   ProcessLookupError: [Errno 3] No such process (originated from sysctl(kinfo_file) (1/2))

During handling of the above exception, another exception occurred:
psutil/tests/test_process.py:1309: in test_as_dict
    d = p.as_dict()
psutil/__init__.py:558: in as_dict
    ret = meth()
psutil/__init__.py:1199: in open_files
    return self._proc.open_files()
psutil/_psbsd.py:609: in wrapper
    raise NoSuchProcess(self.pid, self._name)
E   psutil.NoSuchProcess: process no longer exists (pid=0)
____________________________ TestProcess.test_pid_0 ____________________________
psutil/_psbsd.py:604: in wrapper
    return fun(self, *args, **kwargs)
psutil/_psbsd.py:914: in open_files
    rawlist = cext.proc_open_files(self.pid)
E   ProcessLookupError: [Errno 3] No such process (originated from sysctl(kinfo_file) (1/2))

During handling of the above exception, another exception occurred:
psutil/tests/test_process.py:1513: in test_pid_0
    ret = fun()
psutil/__init__.py:1199: in open_files
    return self._proc.open_files()
psutil/_psbsd.py:609: in wrapper
    raise NoSuchProcess(self.pid, self._name)
E   psutil.NoSuchProcess: process no longer exists (pid=0)
________________________ TestFetchAllProcesses.test_all ________________________
psutil/_psbsd.py:604: in wrapper
    return fun(self, *args, **kwargs)
psutil/_psbsd.py:914: in open_files
    rawlist = cext.proc_open_files(self.pid)
E   ProcessLookupError: [Errno 3] No such process (originated from sysctl(kinfo_file) (1/2))

During handling of the above exception, another exception occurred:
psutil/tests/test_process_all.py:93: in proc_info
    info[fun_name] = fun()
psutil/__init__.py:1199: in open_files
    return self._proc.open_files()
psutil/_psbsd.py:609: in wrapper
    raise NoSuchProcess(self.pid, self._name)
E   psutil.NoSuchProcess: process no longer exists (pid=0, name='swapper')

During handling of the above exception, another exception occurred:
psutil/tests/test_process_all.py:135: in test_all
    for info in self.iter_proc_info():
psutil/tests/test_process_all.py:130: in iter_proc_info
    ls.append(proc_info(pid))
psutil/tests/test_process_all.py:95: in proc_info
    check_exception(exc, proc, name, ppid)
psutil/tests/test_process_all.py:65: in check_exception
    tcase.assertProcessGone(proc)
psutil/tests/__init__.py:1069: in assertProcessGone
    self.assertPidGone(proc.pid)
psutil/tests/__init__.py:1057: in assertPidGone
    with pytest.raises(psutil.NoSuchProcess) as cm:
E   Failed: DID NOT RAISE <class 'psutil.NoSuchProcess'>