Synnefo

from os.path import expanduser, exists

from os import getenv, fsync, unlink

from errno import ENOENT

from shutil import move

stripchars = '"\' '

_pvpath_default = getenv('PVDATA_PATH')

if not _pvpath_default:

    _pvpath_default = expanduser('~/.pvdata')

_pvpath = None

_pvdict = None

_pvdata_counter = 0

_pvdirty = 0

def _pvopen(pvpath=_pvpath_default):

    global _pvdict

    if _pvdict is not None:

        return _pvdict

    try:

        with open(pvpath) as f:

            pvdata = f.read()

    except IOError, e:

        if e.errno != ENOENT:

            m = "Cannot open pvdata file '%s'" % (pvpath,)

            raise ValueError(m, e)

        with open(pvpath, "w") as f:

            pass

        pvdata = ''

    global _pvpath

    _pvpath = pvpath

    pvdict = {}

    for line in pvdata.splitlines():

        key, sep, val = line.partition('=')

        if not key or key[0] == '#':

            continue

        key = key.strip()

        val = val.strip()

        if len(key) > 1 and key[0] == "'" and key[-1] == "'":

            key = key[1:-1]

        if len(val) > 1 and val[0] == "'" and val[-1] == "'":

            val = val[1:-1]

        pvdict[key] = val

    _pvdict = pvdict

    return pvdict

def pvsave(pvpath=None, force=0):

    if _pvdict is None or not (force or _pvdirty):

        return

    if pvpath is None:

        pvpath = _pvpath

    pvdata_list = []

    append = pvdata_list.append

    for key, val in _pvdict.items():

        if not key or '\n' in key or '\n' in val:

            continue

        if key[0] == ' ' or key[-1] == ' ':

            key = "'%s'" % (key,)

        if val[0] == ' ' or val[-1] == ' ':

            val = "'%s'" % (val,)

        append("%s = %s" % (key, val))

    pvdata = '\n'.join(pvdata_list) + '\n'

    global _pvdata_counter

    while 1:

        pvpath_old = '%s.old.%d' % (pvpath, _pvdata_counter)

        if not exists(pvpath_old):

            break

        _pvdata_counter += 1

        continue

    move(pvpath, pvpath_old)

    try:

        with open(pvpath, "w") as f:

            f.write(pvdata)

            f.flush()

            fsync(f.fileno())

    except IOError, e:

        m = "Cannot open pvdata file '%s'" % (pvpath,)

        raise ValueError(m, e)

    unlink(pvpath_old)

def getpv(key):

    pvdict = _pvopen()

    return pvdict[key] if key in pvdict else ''

def setpv(key, val):

    pvdict = _pvopen()

    global _pvdirty

    _pvdirty = 1

    pvdict[key] = val

def delpv(key):

    pvdict = _pvopen()

    del pvdict[key]

def savepv(key, val):

    setpv(key, val)

    pvsave()