def swap_memory():
    sin, sout = cext.swap_mem()
    # XXX
    # we are supposed to get total/free by doing so:
    # http://cvs.opensolaris.org/source/xref/onnv/onnv-gate/
    #     usr/src/cmd/swap/swap.c
    # ...nevertheless I can't manage to obtain the same numbers as 'swap'
    # cmdline utility, so let's parse its output (sigh!)
    p = subprocess.Popen(['swap', '-l', '-k'], stdout=subprocess.PIPE)
    stdout, stderr = p.communicate()
    if PY3:
        stdout = stdout.decode(sys.stdout.encoding)
    if p.returncode != 0:
        raise RuntimeError("'swap -l -k' failed (retcode=%s)" % p.returncode)

    lines = stdout.strip().split('\n')[1:]
    if not lines:
        raise RuntimeError('no swap device(s) configured')
    total = free = 0
    for line in lines:
        line = line.split()
        t, f = line[-2:]
        t = t.replace('K', '')
        f = f.replace('K', '')
        total += int(int(t) * 1024)
        free += int(int(f) * 1024)
    used = total - free
    percent = usage_percent(used, total, _round=1)
    return _common.sswap(total, used, free, percent,
                       sin * PAGE_SIZE, sout * PAGE_SIZE)

def disk_usage(path):
    """Return disk usage associated with path."""
    try:
        st = os.statvfs(path)
    except UnicodeEncodeError:
        if not PY3 and isinstance(path, unicode):
            # this is a bug with os.statvfs() and unicode on
            # Python 2, see:
            # - https://github.com/giampaolo/psutil/issues/416
            # - http://bugs.python.org/issue18695
            try:
                path = path.encode(sys.getfilesystemencoding())
            except UnicodeEncodeError:
                pass
            st = os.statvfs(path)
        else:
            raise
    free = (st.f_bavail * st.f_frsize)
    total = (st.f_blocks * st.f_frsize)
    used = (st.f_blocks - st.f_bfree) * st.f_frsize
    percent = usage_percent(used, total, _round=1)
    # NB: the percentage is -5% than what shown by df due to
    # reserved blocks that we are currently not considering:
    # http://goo.gl/sWGbH
    return sdiskusage(total, used, free, percent)

def swap_memory():
    _, _, _, _, total, free = cext.linux_sysinfo()
    used = total - free
    percent = usage_percent(used, total, _round=1)
    # get pgin/pgouts
    f = open("/proc/vmstat", "rb")
    SIN, SOUT = b('pswpin'), b('pswpout')
    sin = sout = None
    try:
        for line in f:
            # values are expressed in 4 kilo bytes, we want bytes instead
            if line.startswith(SIN):
                sin = int(line.split(b(' '))[1]) * 4 * 1024
            elif line.startswith(SOUT):
                sout = int(line.split(b(' '))[1]) * 4 * 1024
            if sin is not None and sout is not None:
                break
        else:
            # we might get here when dealing with exotic Linux flavors, see:
            # http://code.google.com/p/psutil/issues/detail?id=313
            msg = "'sin' and 'sout' swap memory stats couldn't " \
                  "be determined and were set to 0"
            warnings.warn(msg, RuntimeWarning)
            sin = sout = 0
    finally:
        f.close()
    return _common.sswap(total, used, free, percent, sin, sout)

def virtual_memory():
    total, free, buffers, shared, _, _ = cext.linux_sysinfo()
    cached = active = inactive = None
    with open('/proc/meminfo', 'rb') as f:
        for line in f:
            if line.startswith(b"Cached:"):
                cached = int(line.split()[1]) * 1024
            elif line.startswith(b"Active:"):
                active = int(line.split()[1]) * 1024
            elif line.startswith(b"Inactive:"):
                inactive = int(line.split()[1]) * 1024
            if (cached is not None
                    and active is not None
                    and inactive is not None):
                break
        else:
            # we might get here when dealing with exotic Linux flavors, see:
            # https://github.com/giampaolo/psutil/issues/313
            msg = "'cached', 'active' and 'inactive' memory stats couldn't " \
                  "be determined and were set to 0"
            warnings.warn(msg, RuntimeWarning)
            cached = active = inactive = 0
    avail = free + buffers + cached
    used = total - free
    percent = usage_percent((total - avail), total, _round=1)
    return svmem(total, avail, percent, used, free,
                 active, inactive, buffers, cached)

def virtual_memory():
    total, free, buffers, shared, _, _ = cext.linux_sysinfo()
    cached = active = inactive = None
    f = open('/proc/meminfo', 'rb')
    CACHED, ACTIVE, INACTIVE = b("Cached:"), b("Active:"), b("Inactive:")
    try:
        for line in f:
            if line.startswith(CACHED):
                cached = int(line.split()[1]) * 1024
            elif line.startswith(ACTIVE):
                active = int(line.split()[1]) * 1024
            elif line.startswith(INACTIVE):
                inactive = int(line.split()[1]) * 1024
            if (cached is not None
                    and active is not None
                    and inactive is not None):
                break
        else:
            # we might get here when dealing with exotic Linux flavors, see:
            # http://code.google.com/p/psutil/issues/detail?id=313
            msg = "'cached', 'active' and 'inactive' memory stats couldn't " \
                  "be determined and were set to 0"
            warnings.warn(msg, RuntimeWarning)
            cached = active = inactive = 0
    finally:
        f.close()
    avail = free + buffers + cached
    used = total - free
    percent = usage_percent((total - avail), total, _round=1)
    return svmem(total, avail, percent, used, free,
                 active, inactive, buffers, cached)

def virtual_memory():
    # we could have done this with kstat, but imho this is good enough
    total = os.sysconf('SC_PHYS_PAGES') * PAGE_SIZE
    # note: there's no difference on Solaris
    free = avail = os.sysconf('SC_AVPHYS_PAGES') * PAGE_SIZE
    used = total - free
    percent = usage_percent(used, total, _round=1)
    return svmem(total, avail, percent, used, free)

def swap_memory():
    """Swap system memory as a (total, used, free, sin, sout) tuple."""
    mem = cext.virtual_mem()
    total = mem[2]
    free = mem[3]
    used = total - free
    percent = usage_percent(used, total, _round=1)
    return _common.sswap(total, used, free, percent, 0, 0)

def virtual_memory():
    """System virtual memory as a namedtuple."""
    total, active, inactive, wired, free = cext.virtual_mem()
    avail = inactive + free
    used = active + inactive + wired
    percent = usage_percent((total - avail), total, _round=1)
    return svmem(total, avail, percent, used, free,
                 active, inactive, wired)

def virtual_memory():
    """System virtual memory as a namedtuple."""
    mem = cext.virtual_mem()
    total, free, active, inactive, wired, cached, buffers, shared = mem
    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 virtual_memory():
    """System virtual memory as a namedtuple."""
    mem = cext.virtual_mem()
    totphys, availphys, totpagef, availpagef, totvirt, freevirt = mem
    #
    total = totphys
    avail = availphys
    free = availphys
    used = total - avail
    percent = usage_percent((total - avail), total, _round=1)
    return svmem(total, avail, percent, used, free)

def get_disk_usage(path):
    """Return disk usage associated with path."""
    st = os.statvfs(path)
    free = (st.f_bavail * st.f_frsize)
    total = (st.f_blocks * st.f_frsize)
    used = (st.f_blocks - st.f_bfree) * st.f_frsize
    percent = usage_percent(used, total, _round=1)
    # NB: the percentage is -5% than what shown by df due to
    # reserved blocks that we are currently not considering:
    # http://goo.gl/sWGbH
    return ntuple_diskinfo(total, used, free, percent)

def disk_usage(path):
    """Return disk usage associated with path."""
    try:
        total, free = cext.disk_usage(path)
    except WindowsError:
        if not os.path.exists(path):
            msg = "No such file or directory: '%s'" % path
            raise OSError(errno.ENOENT, msg)
        raise
    used = total - free
    percent = usage_percent(used, total, _round=1)
    return _common.sdiskusage(total, used, free, percent)

def swap_memory():
    _, _, _, _, total, free = cext.linux_sysinfo()
    used = total - free
    percent = usage_percent(used, total, _round=1)
    # get pgin/pgouts
    with open("/proc/vmstat", "rb") as f:
        sin = sout = None
        for line in f:
            # values are expressed in 4 kilo bytes, we want bytes instead
            if line.startswith(b'pswpin'):
                sin = int(line.split(b' ')[1]) * 4 * 1024
            elif line.startswith(b'pswpout'):
                sout = int(line.split(b' ')[1]) * 4 * 1024
            if sin is not None and sout is not None:
                break
        else:
            # we might get here when dealing with exotic Linux flavors, see:
            # https://github.com/giampaolo/psutil/issues/313
            msg = "'sin' and 'sout' swap memory stats couldn't " \
                  "be determined and were set to 0"
            warnings.warn(msg, RuntimeWarning)
            sin = sout = 0
    return _common.sswap(total, used, free, percent, sin, sout)

def swap_memory():
    """System swap memory as (total, used, free, sin, sout) namedtuple."""
    total, used, free, sin, sout = [x * PAGESIZE for x in cext.swap_mem()]
    percent = usage_percent(used, total, _round=1)
    return _common.sswap(total, used, free, percent, sin, sout)

def swap_memory():
    """Swap system memory as a (total, used, free, sin, sout) tuple."""
    total, used, free, sin, sout = cext.swap_mem()
    percent = usage_percent(used, total, _round=1)
    return _common.sswap(total, used, free, percent, sin, sout)