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from ctypes import Structure, c_char_p, c_int, c_void_p, CDLL, POINTER, c_char
import ctypes.util
import os, sys
class error(Exception):
def __init__(self, msg):
self.msg = msg
def __str__(self):
return self.msg
class datum(Structure):
_fields_ = [
('dptr', POINTER(c_char)),
('dsize', c_int),
]
def __init__(self, text):
if not isinstance(text, str):
raise TypeError("datum: expected string, not %s" % type(text))
Structure.__init__(self, text, len(text))
class dbm(object):
def __init__(self, dbmobj):
self._aobj = dbmobj
def close(self):
if not self._aobj:
raise error('DBM object has already been closed')
getattr(lib, funcs['close'])(self._aobj)
self._aobj = None
def __del__(self):
if self._aobj:
self.close()
def keys(self):
if not self._aobj:
raise error('DBM object has already been closed')
allkeys = []
k = getattr(lib, funcs['firstkey'])(self._aobj)
while k.dptr:
allkeys.append(k.dptr[:k.dsize])
k = getattr(lib, funcs['nextkey'])(self._aobj)
return allkeys
def get(self, key, default=None):
if not self._aobj:
raise error('DBM object has already been closed')
dat = datum(key)
k = getattr(lib, funcs['fetch'])(self._aobj, dat)
if k.dptr:
return k.dptr[:k.dsize]
if getattr(lib, funcs['error'])(self._aobj):
getattr(lib, funcs['clearerr'])(self._aobj)
raise error("")
return default
def __len__(self):
return len(self.keys())
def __getitem__(self, key):
value = self.get(key)
if value is None:
raise KeyError(key)
return value
def __setitem__(self, key, value):
if not self._aobj:
raise error('DBM object has already been closed')
dat = datum(key)
data = datum(value)
status = getattr(lib, funcs['store'])(self._aobj, dat, data, lib.DBM_REPLACE)
if getattr(lib, funcs['error'])(self._aobj):
getattr(lib, funcs['clearerr'])(self._aobj)
raise error("")
return status
def setdefault(self, key, default=''):
if not self._aobj:
raise error('DBM object has already been closed')
dat = datum(key)
k = getattr(lib, funcs['fetch'])(self._aobj, dat)
if k.dptr:
return k.dptr[:k.dsize]
data = datum(default)
status = getattr(lib, funcs['store'])(self._aobj, dat, data, lib.DBM_INSERT)
if status < 0:
getattr(lib, funcs['clearerr'])(self._aobj)
raise error("cannot add item to database")
return default
def __contains__(self, key):
if not self._aobj:
raise error('DBM object has already been closed')
dat = datum(key)
k = getattr(lib, funcs['fetch'])(self._aobj, dat)
if k.dptr:
return True
return False
has_key = __contains__
def __delitem__(self, key):
if not self._aobj:
raise error('DBM object has already been closed')
dat = datum(key)
status = getattr(lib, funcs['delete'])(self._aobj, dat)
if status < 0:
raise KeyError(key)
### initialization: Berkeley DB versus normal DB
def _init_func(name, argtypes=None, restype=None):
try:
func = getattr(lib, '__db_ndbm_' + name)
funcs[name] = '__db_ndbm_' + name
except AttributeError:
func = getattr(lib, 'dbm_' + name)
funcs[name] = 'dbm_' + name
if argtypes is not None:
func.argtypes = argtypes
if restype is not None:
func.restype = restype
if sys.platform != 'darwin':
libpath = ctypes.util.find_library('db')
if not libpath:
# XXX this is hopeless...
for c in ['5.3', '5.2', '5.1', '5.0', '4.9', '4.8', '4.7', '4.6', '4.5']:
libpath = ctypes.util.find_library('db-%s' % c)
if libpath:
break
else:
raise ImportError("Cannot find dbm library")
lib = CDLL(libpath) # Linux
_platform = 'bdb'
else:
lib = CDLL("/usr/lib/libdbm.dylib") # OS X
_platform = 'osx'
library = "GNU gdbm"
funcs = {}
_init_func('open', (c_char_p, c_int, c_int), restype=c_void_p)
_init_func('close', (c_void_p,), restype=c_void_p)
_init_func('firstkey', (c_void_p,), restype=datum)
_init_func('nextkey', (c_void_p,), restype=datum)
_init_func('fetch', (c_void_p, datum), restype=datum)
_init_func('store', (c_void_p, datum, datum, c_int), restype=c_int)
_init_func('error', (c_void_p,), restype=c_int)
_init_func('delete', (c_void_p, datum), restype=c_int)
_init_func('clearerr', (c_void_p,), restype=c_int)
lib.DBM_INSERT = 0
lib.DBM_REPLACE = 1
def open(filename, flag='r', mode=0666):
"open a DBM database"
if not isinstance(filename, str):
if sys.version_info < (3,) and isinstance(filename, unicode):
# unlike CPython we'll encode 'filename' with filesystemencoding
# instead of defaultencoding, because that seems like a far
# better idea. But I'm also open for saying that we should
# rather go for bug-to-bug compatibility instead.
filename = filename.encode(sys.getfilesystemencoding())
else:
raise TypeError("expected string")
openflag = 0
try:
openflag = {
'r': os.O_RDONLY,
'rw': os.O_RDWR,
'w': os.O_RDWR | os.O_CREAT,
'c': os.O_RDWR | os.O_CREAT,
'n': os.O_RDWR | os.O_CREAT | os.O_TRUNC,
}[flag]
except KeyError:
raise error("arg 2 to open should be 'r', 'w', 'c', or 'n'")
a_db = getattr(lib, funcs['open'])(filename, openflag, mode)
if a_db == 0:
raise error("Could not open file %s.db" % filename)
return dbm(a_db)
__all__ = ('datum', 'dbm', 'error', 'funcs', 'open', 'library')
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