# Copyright (c) 2009, Giampaolo Rodola'. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""FreeBSD, OpenBSD and NetBSD platforms implementation."""

import contextlib
import errno
import functools
import os
import xml.etree.ElementTree as ET
from collections import defaultdict
from collections import namedtuple

from . import _common
from . import _psposix
from . import _psutil_bsd as cext
from . import _psutil_posix as cext_posix
from ._common import FREEBSD
from ._common import NETBSD
from ._common import OPENBSD
from ._common import AccessDenied
from ._common import NoSuchProcess
from ._common import ZombieProcess
from ._common import conn_tmap
from ._common import conn_to_ntuple
from ._common import memoize
from ._common import memoize_when_activated
from ._common import usage_percent
from ._compat import FileNotFoundError
from ._compat import PermissionError
from ._compat import ProcessLookupError
from ._compat import which


__extra__all__ = []


# =====================================================================
# --- globals
# =====================================================================


if FREEBSD:
    PROC_STATUSES = {
        cext.SIDL: _common.STATUS_IDLE,
        cext.SRUN: _common.STATUS_RUNNING,
        cext.SSLEEP: _common.STATUS_SLEEPING,
        cext.SSTOP: _common.STATUS_STOPPED,
        cext.SZOMB: _common.STATUS_ZOMBIE,
        cext.SWAIT: _common.STATUS_WAITING,
        cext.SLOCK: _common.STATUS_LOCKED,
    }
elif OPENBSD:
    PROC_STATUSES = {
        cext.SIDL: _common.STATUS_IDLE,
        cext.SSLEEP: _common.STATUS_SLEEPING,
        cext.SSTOP: _common.STATUS_STOPPED,
        # According to /usr/include/sys/proc.h SZOMB is unused.
        # test_zombie_process() shows that SDEAD is the right
        # equivalent. Also it appears there's no equivalent of
        # psutil.STATUS_DEAD. SDEAD really means STATUS_ZOMBIE.
        # cext.SZOMB: _common.STATUS_ZOMBIE,
        cext.SDEAD: _common.STATUS_ZOMBIE,
        cext.SZOMB: _common.STATUS_ZOMBIE,
        # From http://www.eecs.harvard.edu/~margo/cs161/videos/proc.h.txt
        # OpenBSD has SRUN and SONPROC: SRUN indicates that a process
        # is runnable but *not* yet running, i.e. is on a run queue.
        # SONPROC indicates that the process is actually executing on
        # a CPU, i.e. it is no longer on a run queue.
        # As such we'll map SRUN to STATUS_WAKING and SONPROC to
        # STATUS_RUNNING
        cext.SRUN: _common.STATUS_WAKING,
        cext.SONPROC: _common.STATUS_RUNNING,
    }
elif NETBSD:
    PROC_STATUSES = {
        cext.SIDL: _common.STATUS_IDLE,
        cext.SSLEEP: _common.STATUS_SLEEPING,
        cext.SSTOP: _common.STATUS_STOPPED,
        cext.SZOMB: _common.STATUS_ZOMBIE,
        cext.SRUN: _common.STATUS_WAKING,
        cext.SONPROC: _common.STATUS_RUNNING,
    }

TCP_STATUSES = {
    cext.TCPS_ESTABLISHED: _common.CONN_ESTABLISHED,
    cext.TCPS_SYN_SENT: _common.CONN_SYN_SENT,
    cext.TCPS_SYN_RECEIVED: _common.CONN_SYN_RECV,
    cext.TCPS_FIN_WAIT_1: _common.CONN_FIN_WAIT1,
    cext.TCPS_FIN_WAIT_2: _common.CONN_FIN_WAIT2,
    cext.TCPS_TIME_WAIT: _common.CONN_TIME_WAIT,
    cext.TCPS_CLOSED: _common.CONN_CLOSE,
    cext.TCPS_CLOSE_WAIT: _common.CONN_CLOSE_WAIT,
    cext.TCPS_LAST_ACK: _common.CONN_LAST_ACK,
    cext.TCPS_LISTEN: _common.CONN_LISTEN,
    cext.TCPS_CLOSING: _common.CONN_CLOSING,
    cext.PSUTIL_CONN_NONE: _common.CONN_NONE,
}

PAGESIZE = cext_posix.getpagesize()
AF_LINK = cext_posix.AF_LINK

HAS_PER_CPU_TIMES = hasattr(cext, "per_cpu_times")
HAS_PROC_NUM_THREADS = hasattr(cext, "proc_num_threads")
HAS_PROC_OPEN_FILES = hasattr(cext, 'proc_open_files')
HAS_PROC_NUM_FDS = hasattr(cext, 'proc_num_fds')

kinfo_proc_map = dict(
    ppid=0,
    status=1,
    real_uid=2,
    effective_uid=3,
    saved_uid=4,
    real_gid=5,
    effective_gid=6,
    saved_gid=7,
    ttynr=8,
    create_time=9,
    ctx_switches_vol=10,
    ctx_switches_unvol=11,
    read_io_count=12,
    write_io_count=13,
    user_time=14,
    sys_time=15,
    ch_user_time=16,
    ch_sys_time=17,
    rss=18,
    vms=19,
    memtext=20,
    memdata=21,
    memstack=22,
    cpunum=23,
    name=24,
)


# =====================================================================
# --- named tuples
# =====================================================================


# psutil.virtual_memory()
svmem = namedtuple(
    'svmem', ['total', 'available', 'percent', 'used', 'free',
              'active', 'inactive', 'buffers', 'cached', 'shared', 'wired'])
# psutil.cpu_times()
scputimes = namedtuple(
    'scputimes', ['user', 'nice', 'system', 'idle', 'irq'])
# psutil.Process.memory_info()
pmem = namedtuple('pmem', ['rss', 'vms', 'text', 'data', 'stack'])
# psutil.Process.memory_full_info()
pfullmem = pmem
# psutil.Process.cpu_times()
pcputimes = namedtuple('pcputimes',
                       ['user', 'system', 'children_user', 'children_system'])
# psutil.Process.memory_maps(grouped=True)
pmmap_grouped = namedtuple(
    'pmmap_grouped', 'path rss, private, ref_count, shadow_count')
# psutil.Process.memory_maps(grouped=False)
pmmap_ext = namedtuple(
    'pmmap_ext', 'addr, perms path rss, private, ref_count, shadow_count')
# psutil.disk_io_counters()
if FREEBSD:
    sdiskio = namedtuple('sdiskio', ['read_count', 'write_count',
                                     'read_bytes', 'write_bytes',
                                     'read_time', 'write_time',
                                     'busy_time'])
else:
    sdiskio = namedtuple('sdiskio', ['read_count', 'write_count',
                                     'read_bytes', 'write_bytes'])


# =====================================================================
# --- memory
# =====================================================================


def virtual_memory():
    mem = cext.virtual_mem()
    if NETBSD:
        total, free, active, inactive, wired, cached = mem
        # On NetBSD buffers and shared mem is determined via /proc.
        # The C ext set them to 0.
        with open('/proc/meminfo', 'rb') as f:
            for line in f:
                if line.startswith(b'Buffers:'):
                    buffers = int(line.split()[1]) * 1024
                elif line.startswith(b'MemShared:'):
                    shared = int(line.split()[1]) * 1024
        # Before avail was calculated as (inactive + cached + free),
        # same as zabbix, but it turned out it could exceed total (see
        # #2233), so zabbix seems to be wrong. Htop calculates it
        # differently, and the used value seem more realistic, so let's
        # match htop.
        # https://github.com/htop-dev/htop/blob/e7f447b/netbsd/NetBSDProcessList.c#L162  # noqa
        # https://github.com/zabbix/zabbix/blob/af5e0f8/src/libs/zbxsysinfo/netbsd/memory.c#L135  # noqa
        used = active + wired
        avail = total - used
    else:
        total, free, active, inactive, wired, cached, buffers, shared = mem
        # matches freebsd-memory CLI:
        # * https://people.freebsd.org/~rse/dist/freebsd-memory
        # * https://www.cyberciti.biz/files/scripts/freebsd-memory.pl.txt
        # matches zabbix:
        # * https://github.com/zabbix/zabbix/blob/af5e0f8/src/libs/zbxsysinfo/freebsd/memory.c#L143  # noqa
        avail = inactive + cached + free
        used = active + wired + cached

    percent = usage_percent((total - avail), total, round_=1)
    return svmem(total, avail, percent, used, free,
                 active, inactive, buffers, cached, shared, wired)


def swap_memory():
    """System swap memory as (total, used, free, sin, sout) namedtuple."""
    total, used, free, sin, sout = cext.swap_mem()
    percent = usage_percent(used, total, round_=1)
    return _common.sswap(total, used, free, percent, sin, sout)


# =====================================================================
# --- CPU
# =====================================================================


def cpu_times():
    """Return system per-CPU times as a namedtuple"""
    user, nice, system, idle, irq = cext.cpu_times()
    return scputimes(user, nice, system, idle, irq)


if HAS_PER_CPU_TIMES:
    def per_cpu_times():
        """Return system CPU times as a namedtuple"""
        ret = []
        for cpu_t in cext.per_cpu_times():
            user, nice, system, idle, irq = cpu_t
            item = scputimes(user, nice, system, idle, irq)
            ret.append(item)
        return ret
else:
    # XXX
    # Ok, this is very dirty.
    # On FreeBSD < 8 we cannot gather per-cpu information, see:
    # https://github.com/giampaolo/psutil/issues/226
    # If num cpus > 1, on first call we return single cpu times to avoid a
    # crash at psutil import time.
    # Next calls will fail with NotImplementedError
    def per_cpu_times():
        """Return system CPU times as a namedtuple"""
        if cpu_count_logical() == 1:
            return [cpu_times()]
        if per_cpu_times.__called__:
            raise NotImplementedError("supported only starting from FreeBSD 8")
        per_cpu_times.__called__ = True
        return [cpu_times()]

    per_cpu_times.__called__ = False


def cpu_count_logical():
    """Return the number of logical CPUs in the system."""
    return cext.cpu_count_logical()


if OPENBSD or NETBSD:
    def cpu_count_cores():
        # OpenBSD and NetBSD do not implement this.
        return 1 if cpu_count_logical() == 1 else None
else:
    def cpu_count_cores():
        """Return the number of CPU cores in the system."""
        # From the C module we'll get an XML string similar to this:
        # http://manpages.ubuntu.com/manpages/precise/man4/smp.4freebsd.html
        # We may get None in case "sysctl kern.sched.topology_spec"
        # is not supported on this BSD version, in which case we'll mimic
        # os.cpu_count() and return None.
        ret = None
        s = cext.cpu_topology()
        if s is not None:
            # get rid of padding chars appended at the end of the string
            index = s.rfind("</groups>")
            if index != -1:
                s = s[:index + 9]
                root = ET.fromstring(s)
                try:
                    ret = len(root.findall('group/children/group/cpu')) or None
                finally:
                    # needed otherwise it will memleak
                    root.clear()
        if not ret:
            # If logical CPUs == 1 it's obvious we' have only 1 core.
            if cpu_count_logical() == 1:
                return 1
        return ret


def cpu_stats():
    """Return various CPU stats as a named tuple."""
    if FREEBSD:
        # Note: the C ext is returning some metrics we are not exposing:
        # traps.
        ctxsw, intrs, soft_intrs, syscalls, traps = cext.cpu_stats()
    elif NETBSD:
        # XXX
        # Note about intrs: the C extension returns 0. intrs
        # can be determined via /proc/stat; it has the same value as
        # soft_intrs thought so the kernel is faking it (?).
        #
        # Note about syscalls: the C extension always sets it to 0 (?).
        #
        # Note: the C ext is returning some metrics we are not exposing:
        # traps, faults and forks.
        ctxsw, intrs, soft_intrs, syscalls, traps, faults, forks = \
            cext.cpu_stats()
        with open('/proc/stat', 'rb') as f:
            for line in f:
                if line.startswith(b'intr'):
                    intrs = int(line.split()[1])
    elif OPENBSD:
        # Note: the C ext is returning some metrics we are not exposing:
        # traps, faults and forks.
        ctxsw, intrs, soft_intrs, syscalls, traps, faults, forks = \
            cext.cpu_stats()
    return _common.scpustats(ctxsw, intrs, soft_intrs, syscalls)


if FREEBSD:
    def cpu_freq():
        """Return frequency metrics for CPUs. As of Dec 2018 only
        CPU 0 appears to be supported by FreeBSD and all other cores
        match the frequency of CPU 0.
        """
        ret = []
        num_cpus = cpu_count_logical()
        for cpu in range(num_cpus):
            try:
                current, available_freq = cext.cpu_freq(cpu)
            except NotImplementedError:
                continue
            if available_freq:
                try:
                    min_freq = int(available_freq.split(" ")[-1].split("/")[0])
                except (IndexError, ValueError):
                    min_freq = None
                try:
                    max_freq = int(available_freq.split(" ")[0].split("/")[0])
                except (IndexError, ValueError):
                    max_freq = None
            ret.append(_common.scpufreq(current, min_freq, max_freq))
        return ret
elif OPENBSD:
    def cpu_freq():
        curr = float(cext.cpu_freq())
        return [_common.scpufreq(curr, 0.0, 0.0)]


# =====================================================================
# --- disks
# =====================================================================


def disk_partitions(all=False):
    """Return mounted disk partitions as a list of namedtuples.
    'all' argument is ignored, see:
    https://github.com/giampaolo/psutil/issues/906
    """
    retlist = []
    partitions = cext.disk_partitions()
    for partition in partitions:
        device, mountpoint, fstype, opts = partition
        maxfile = maxpath = None  # set later
        ntuple = _common.sdiskpart(device, mountpoint, fstype, opts,
                                   maxfile, maxpath)
        retlist.append(ntuple)
    return retlist


disk_usage = _psposix.disk_usage
disk_io_counters = cext.disk_io_counters


# =====================================================================
# --- network
# =====================================================================


net_io_counters = cext.net_io_counters
net_if_addrs = cext_posix.net_if_addrs


def net_if_stats():
    """Get NIC stats (isup, duplex, speed, mtu)."""
    names = net_io_counters().keys()
    ret = {}
    for name in names:
        try:
            mtu = cext_posix.net_if_mtu(name)
            flags = cext_posix.net_if_flags(name)
            duplex, speed = cext_posix.net_if_duplex_speed(name)
        except OSError as err:
            # https://github.com/giampaolo/psutil/issues/1279
            if err.errno != errno.ENODEV:
                raise
        else:
            if hasattr(_common, 'NicDuplex'):
                duplex = _common.NicDuplex(duplex)
            output_flags = ','.join(flags)
            isup = 'running' in flags
            ret[name] = _common.snicstats(isup, duplex, speed, mtu,
                                          output_flags)
    return ret


def net_connections(kind):
    """System-wide network connections."""
    if kind not in _common.conn_tmap:
        raise ValueError("invalid %r kind argument; choose between %s"
                         % (kind, ', '.join([repr(x) for x in conn_tmap])))
    families, types = conn_tmap[kind]
    ret = set()

    if OPENBSD:
        rawlist = cext.net_connections(-1, families, types)
    elif NETBSD:
        rawlist = cext.net_connections(-1)
    else:  # FreeBSD
        rawlist = cext.net_connections()

    for item in rawlist:
        fd, fam, type, laddr, raddr, status, pid = item
        if NETBSD or FREEBSD:
            # OpenBSD implements filtering in C
            if (fam not in families) or (type not in types):
                continue
        nt = conn_to_ntuple(fd, fam, type, laddr, raddr,
                            status, TCP_STATUSES, pid)
        ret.add(nt)
    return list(ret)


# =====================================================================
#  --- sensors
# =====================================================================


if FREEBSD:

    def sensors_battery():
        """Return battery info."""
        try:
            percent, minsleft, power_plugged = cext.sensors_battery()
        except NotImplementedError:
            # See: https://github.com/giampaolo/psutil/issues/1074
            return None
        power_plugged = power_plugged == 1
        if power_plugged:
            secsleft = _common.POWER_TIME_UNLIMITED
        elif minsleft == -1:
            secsleft = _common.POWER_TIME_UNKNOWN
        else:
            secsleft = minsleft * 60
        return _common.sbattery(percent, secsleft, power_plugged)

    def sensors_temperatures():
        """Return CPU cores temperatures if available, else an empty dict."""
        ret = defaultdict(list)
        num_cpus = cpu_count_logical()
        for cpu in range(num_cpus):
            try:
                current, high = cext.sensors_cpu_temperature(cpu)
                if high <= 0:
                    high = None
                name = "Core %s" % cpu
                ret["coretemp"].append(
                    _common.shwtemp(name, current, high, high))
            except NotImplementedError:
                pass

        return ret


# =====================================================================
#  --- other system functions
# =====================================================================


def boot_time():
    """The system boot time expressed in seconds since the epoch."""
    return cext.boot_time()


def users():
    """Return currently connected users as a list of namedtuples."""
    retlist = []
    rawlist = cext.users()
    for item in rawlist:
        user, tty, hostname, tstamp, pid = item
        if pid == -1:
            assert OPENBSD
            pid = None
        if tty == '~':
            continue  # reboot or shutdown
        nt = _common.suser(user, tty or None, hostname, tstamp, pid)
        retlist.append(nt)
    return retlist


# =====================================================================
# --- processes
# =====================================================================


@memoize
def _pid_0_exists():
    try:
        Process(0).name()
    except NoSuchProcess:
        return False
    except AccessDenied:
        return True
    else:
        return True


def pids():
    """Returns a list of PIDs currently running on the system."""
    ret = cext.pids()
    if OPENBSD and (0 not in ret) and _pid_0_exists():
        # On OpenBSD the kernel does not return PID 0 (neither does
        # ps) but it's actually querable (Process(0) will succeed).
        ret.insert(0, 0)
    return ret


if OPENBSD or NETBSD:
    def pid_exists(pid):
        """Return True if pid exists."""
        exists = _psposix.pid_exists(pid)
        if not exists:
            # We do this because _psposix.pid_exists() lies in case of
            # zombie processes.
            return pid in pids()
        else:
            return True
else:
    pid_exists = _psposix.pid_exists


def is_zombie(pid):
    try:
        st = cext.proc_oneshot_info(pid)[kinfo_proc_map['status']]
        return PROC_STATUSES.get(st) == _common.STATUS_ZOMBIE
    except Exception:
        return False


def wrap_exceptions(fun):
    """Decorator which translates bare OSError exceptions into
    NoSuchProcess and AccessDenied.
    """
    @functools.wraps(fun)
    def wrapper(self, *args, **kwargs):
        try:
            return fun(self, *args, **kwargs)
        except ProcessLookupError:
            if is_zombie(self.pid):
                raise ZombieProcess(self.pid, self._name, self._ppid)
            else:
                raise NoSuchProcess(self.pid, self._name)
        except PermissionError:
            raise AccessDenied(self.pid, self._name)
        except OSError:
            if self.pid == 0:
                if 0 in pids():
                    raise AccessDenied(self.pid, self._name)
                else:
                    raise
            raise
    return wrapper


@contextlib.contextmanager
def wrap_exceptions_procfs(inst):
    """Same as above, for routines relying on reading /proc fs."""
    try:
        yield
    except (ProcessLookupError, FileNotFoundError):
        # ENOENT (no such file or directory) gets raised on open().
        # ESRCH (no such process) can get raised on read() if
        # process is gone in meantime.
        if is_zombie(inst.pid):
            raise ZombieProcess(inst.pid, inst._name, inst._ppid)
        else:
            raise NoSuchProcess(inst.pid, inst._name)
    except PermissionError:
        raise AccessDenied(inst.pid, inst._name)


class Process(object):
    """Wrapper class around underlying C implementation."""

    __slots__ = ["pid", "_name", "_ppid", "_cache"]

    def __init__(self, pid):
        self.pid = pid
        self._name = None
        self._ppid = None

    def _assert_alive(self):
        """Raise NSP if the process disappeared on us."""
        # For those C function who do not raise NSP, possibly returning
        # incorrect or incomplete result.
        cext.proc_name(self.pid)

    @wrap_exceptions
    @memoize_when_activated
    def oneshot(self):
        """Retrieves multiple process info in one shot as a raw tuple."""
        ret = cext.proc_oneshot_info(self.pid)
        assert len(ret) == len(kinfo_proc_map)
        return ret

    def oneshot_enter(self):
        self.oneshot.cache_activate(self)

    def oneshot_exit(self):
        self.oneshot.cache_deactivate(self)

    @wrap_exceptions
    def name(self):
        name = self.oneshot()[kinfo_proc_map['name']]
        return name if name is not None else cext.proc_name(self.pid)

    @wrap_exceptions
    def exe(self):
        if FREEBSD:
            if self.pid == 0:
                return ''  # else NSP
            return cext.proc_exe(self.pid)
        elif NETBSD:
            if self.pid == 0:
                # /proc/0 dir exists but /proc/0/exe doesn't
                return ""
            with wrap_exceptions_procfs(self):
                return os.readlink("/proc/%s/exe" % self.pid)
        else:
            # OpenBSD: exe cannot be determined; references:
            # https://chromium.googlesource.com/chromium/src/base/+/
            #     master/base_paths_posix.cc
            # We try our best guess by using which against the first
            # cmdline arg (may return None).
            cmdline = self.cmdline()
            if cmdline:
                return which(cmdline[0]) or ""
            else:
                return ""

    @wrap_exceptions
    def cmdline(self):
        if OPENBSD and self.pid == 0:
            return []  # ...else it crashes
        elif NETBSD:
            # XXX - most of the times the underlying sysctl() call on Net
            # and Open BSD returns a truncated string.
            # Also /proc/pid/cmdline behaves the same so it looks
            # like this is a kernel bug.
            try:
                return cext.proc_cmdline(self.pid)
            except OSError as err:
                if err.errno == errno.EINVAL:
                    if is_zombie(self.pid):
                        raise ZombieProcess(self.pid, self._name, self._ppid)
                    elif not pid_exists(self.pid):
                        raise NoSuchProcess(self.pid, self._name, self._ppid)
                    else:
                        # XXX: this happens with unicode tests. It means the C
                        # routine is unable to decode invalid unicode chars.
                        return []
                else:
                    raise
        else:
            return cext.proc_cmdline(self.pid)

    @wrap_exceptions
    def environ(self):
        return cext.proc_environ(self.pid)

    @wrap_exceptions
    def terminal(self):
        tty_nr = self.oneshot()[kinfo_proc_map['ttynr']]
        tmap = _psposix.get_terminal_map()
        try:
            return tmap[tty_nr]
        except KeyError:
            return None

    @wrap_exceptions
    def ppid(self):
        self._ppid = self.oneshot()[kinfo_proc_map['ppid']]
        return self._ppid

    @wrap_exceptions
    def uids(self):
        rawtuple = self.oneshot()
        return _common.puids(
            rawtuple[kinfo_proc_map['real_uid']],
            rawtuple[kinfo_proc_map['effective_uid']],
            rawtuple[kinfo_proc_map['saved_uid']])

    @wrap_exceptions
    def gids(self):
        rawtuple = self.oneshot()
        return _common.pgids(
            rawtuple[kinfo_proc_map['real_gid']],
            rawtuple[kinfo_proc_map['effective_gid']],
            rawtuple[kinfo_proc_map['saved_gid']])

    @wrap_exceptions
    def cpu_times(self):
        rawtuple = self.oneshot()
        return _common.pcputimes(
            rawtuple[kinfo_proc_map['user_time']],
            rawtuple[kinfo_proc_map['sys_time']],
            rawtuple[kinfo_proc_map['ch_user_time']],
            rawtuple[kinfo_proc_map['ch_sys_time']])

    if FREEBSD:
        @wrap_exceptions
        def cpu_num(self):
            return self.oneshot()[kinfo_proc_map['cpunum']]

    @wrap_exceptions
    def memory_info(self):
        rawtuple = self.oneshot()
        return pmem(
            rawtuple[kinfo_proc_map['rss']],
            rawtuple[kinfo_proc_map['vms']],
            rawtuple[kinfo_proc_map['memtext']],
            rawtuple[kinfo_proc_map['memdata']],
            rawtuple[kinfo_proc_map['memstack']])

    memory_full_info = memory_info

    @wrap_exceptions
    def create_time(self):
        return self.oneshot()[kinfo_proc_map['create_time']]

    @wrap_exceptions
    def num_threads(self):
        if HAS_PROC_NUM_THREADS:
            # FreeBSD
            return cext.proc_num_threads(self.pid)
        else:
            return len(self.threads())

    @wrap_exceptions
    def num_ctx_switches(self):
        rawtuple = self.oneshot()
        return _common.pctxsw(
            rawtuple[kinfo_proc_map['ctx_switches_vol']],
            rawtuple[kinfo_proc_map['ctx_switches_unvol']])

    @wrap_exceptions
    def threads(self):
        # Note: on OpenSBD this (/dev/mem) requires root access.
        rawlist = cext.proc_threads(self.pid)
        retlist = []
        for thread_id, utime, stime in rawlist:
            ntuple = _common.pthread(thread_id, utime, stime)
            retlist.append(ntuple)
        if OPENBSD:
            self._assert_alive()
        return retlist

    @wrap_exceptions
    def connections(self, kind='inet'):
        if kind not in conn_tmap:
            raise ValueError("invalid %r kind argument; choose between %s"
                             % (kind, ', '.join([repr(x) for x in conn_tmap])))
        families, types = conn_tmap[kind]
        ret = []

        if NETBSD:
            rawlist = cext.net_connections(self.pid)
        elif OPENBSD:
            rawlist = cext.net_connections(self.pid, families, types)
        else:  # FreeBSD
            rawlist = cext.proc_connections(self.pid, families, types)

        for item in rawlist:
            fd, fam, type, laddr, raddr, status = item[:6]
            if NETBSD:
                # FreeBSD and OpenBSD implement filtering in C
                if (fam not in families) or (type not in types):
                    continue
            nt = conn_to_ntuple(fd, fam, type, laddr, raddr, status,
                                TCP_STATUSES)
            ret.append(nt)

        self._assert_alive()
        return ret

    @wrap_exceptions
    def wait(self, timeout=None):
        return _psposix.wait_pid(self.pid, timeout, self._name)

    @wrap_exceptions
    def nice_get(self):
        return cext_posix.getpriority(self.pid)

    @wrap_exceptions
    def nice_set(self, value):
        return cext_posix.setpriority(self.pid, value)

    @wrap_exceptions
    def status(self):
        code = self.oneshot()[kinfo_proc_map['status']]
        # XXX is '?' legit? (we're not supposed to return it anyway)
        return PROC_STATUSES.get(code, '?')

    @wrap_exceptions
    def io_counters(self):
        rawtuple = self.oneshot()
        return _common.pio(
            rawtuple[kinfo_proc_map['read_io_count']],
            rawtuple[kinfo_proc_map['write_io_count']],
            -1,
            -1)

    @wrap_exceptions
    def cwd(self):
        """Return process current working directory."""
        # sometimes we get an empty string, in which case we turn
        # it into None
        if OPENBSD and self.pid == 0:
            return ""  # ...else it would raise EINVAL
        elif NETBSD or HAS_PROC_OPEN_FILES:
            # FreeBSD < 8 does not support functions based on
            # kinfo_getfile() and kinfo_getvmmap()
            return cext.proc_cwd(self.pid)
        else:
            raise NotImplementedError(
                "supported only starting from FreeBSD 8" if
                FREEBSD else "")

    nt_mmap_grouped = namedtuple(
        'mmap', 'path rss, private, ref_count, shadow_count')
    nt_mmap_ext = namedtuple(
        'mmap', 'addr, perms path rss, private, ref_count, shadow_count')

    def _not_implemented(self):
        raise NotImplementedError

    # FreeBSD < 8 does not support functions based on kinfo_getfile()
    # and kinfo_getvmmap()
    if HAS_PROC_OPEN_FILES:
        @wrap_exceptions
        def open_files(self):
            """Return files opened by process as a list of namedtuples."""
            rawlist = cext.proc_open_files(self.pid)
            return [_common.popenfile(path, fd) for path, fd in rawlist]
    else:
        open_files = _not_implemented

    # FreeBSD < 8 does not support functions based on kinfo_getfile()
    # and kinfo_getvmmap()
    if HAS_PROC_NUM_FDS:
        @wrap_exceptions
        def num_fds(self):
            """Return the number of file descriptors opened by this process."""
            ret = cext.proc_num_fds(self.pid)
            if NETBSD:
                self._assert_alive()
            return ret
    else:
        num_fds = _not_implemented

    # --- FreeBSD only APIs

    if FREEBSD:

        @wrap_exceptions
        def cpu_affinity_get(self):
            return cext.proc_cpu_affinity_get(self.pid)

        @wrap_exceptions
        def cpu_affinity_set(self, cpus):
            # Pre-emptively check if CPUs are valid because the C
            # function has a weird behavior in case of invalid CPUs,
            # see: https://github.com/giampaolo/psutil/issues/586
            allcpus = tuple(range(len(per_cpu_times())))
            for cpu in cpus:
                if cpu not in allcpus:
                    raise ValueError("invalid CPU #%i (choose between %s)"
                                     % (cpu, allcpus))
            try:
                cext.proc_cpu_affinity_set(self.pid, cpus)
            except OSError as err:
                # 'man cpuset_setaffinity' about EDEADLK:
                # <<the call would leave a thread without a valid CPU to run
                # on because the set does not overlap with the thread's
                # anonymous mask>>
                if err.errno in (errno.EINVAL, errno.EDEADLK):
                    for cpu in cpus:
                        if cpu not in allcpus:
                            raise ValueError(
                                "invalid CPU #%i (choose between %s)" % (
                                    cpu, allcpus))
                raise

        @wrap_exceptions
        def memory_maps(self):
            return cext.proc_memory_maps(self.pid)

        @wrap_exceptions
        def rlimit(self, resource, limits=None):
            if limits is None:
                return cext.proc_getrlimit(self.pid, resource)
            else:
                if len(limits) != 2:
                    raise ValueError(
                        "second argument must be a (soft, hard) tuple, "
                        "got %s" % repr(limits))
                soft, hard = limits
                return cext.proc_setrlimit(self.pid, resource, soft, hard)
