Synnefo

#!/usr/bin/env python

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()

    if key in pvdict:

        del pvdict[key]

def savepv(key, val):

    setpv(key, val)

    pvsave()

def listpv():

    pvdict = _pvopen()

    return pvdict.keys()

def showpv():

    pvdict = _pvopen()

    return pvdict.items()

def main(argv):

    argc = len(argv)

    if argc < 2:

        usage = """

./pvdata <command> [<args...>]

  Manipulate a simplistic private value store.

Commands:

  list                      --  lists available keys

  values                    --  lists keys with values

  get  <key>...             --  retrieve key values

  set  <key=value>...       --  set key values

  del  <key>...             --  delete keys

Environment Variable Options:

  PVDATA_PATH=<filepath>    --  use file at <filepath>

                                default: ~/.pvdata

"""

        print(usage)

        raise SystemExit

    cmd = argv[1]

    args = argv[2:]

    if cmd == 'list':

        for x in listpv():      

            print(x)

    elif cmd == 'values':

        for k, v in showpv():

            print("%s=%s" % (k, v))

    elif cmd == 'get':

        for k in args:

            print(getpv[k])

    elif cmd == 'set':

        for kv in args:

            k, sep, v = kv.partition('=')

            if not k or not v:

                continue

            setpv(k, v)

        pvsave()

    elif cmd == 'del':

        for k in args:

            delpv(k)

        pvsave()

if __name__ == '__main__':

    from sys import argv

    main(argv)