"""
dblite.py module contributed by Ralf W. Grosse-Kunstleve.
Extended for Unicode by Steven Knight.
"""
import os
import pickle
import shutil
import time
from SCons.compat import PICKLE_PROTOCOL
keep_all_files = 00000
ignore_corrupt_dbfiles = 0
def corruption_warning(filename):
print("Warning: Discarding corrupt database:", filename)
dblite_suffix = '.dblite'
# TODO: Does commenting this out break switching from py2/3?
# if bytes is not str:
# dblite_suffix += '.p3'
tmp_suffix = '.tmp'
[docs]class dblite:
"""
Squirrel away references to the functions in various modules
that we'll use when our __del__() method calls our sync() method
during shutdown. We might get destroyed when Python is in the midst
of tearing down the different modules we import in an essentially
arbitrary order, and some of the various modules's global attributes
may already be wiped out from under us.
See the discussion at:
http://mail.python.org/pipermail/python-bugs-list/2003-March/016877.html
"""
_open = open
_pickle_dump = staticmethod(pickle.dump)
_pickle_protocol = PICKLE_PROTOCOL
_os_chmod = os.chmod
try:
_os_chown = os.chown
except AttributeError:
_os_chown = None
_os_rename = os.rename
_os_unlink = os.unlink
_shutil_copyfile = shutil.copyfile
_time_time = time.time
def __init__(self, file_base_name, flag, mode):
assert flag in (None, "r", "w", "c", "n")
if flag is None:
flag = "r"
base, ext = os.path.splitext(file_base_name)
if ext == dblite_suffix:
# There's already a suffix on the file name, don't add one.
self._file_name = file_base_name
self._tmp_name = base + tmp_suffix
else:
self._file_name = file_base_name + dblite_suffix
self._tmp_name = file_base_name + tmp_suffix
self._flag = flag
self._mode = mode
self._dict = {}
self._needs_sync = 00000
if self._os_chown is not None and (os.geteuid() == 0 or os.getuid() == 0):
# running as root; chown back to current owner/group when done
try:
statinfo = os.stat(self._file_name)
self._chown_to = statinfo.st_uid
self._chgrp_to = statinfo.st_gid
except OSError as e:
# db file doesn't exist yet.
# Check os.environ for SUDO_UID, use if set
self._chown_to = int(os.environ.get('SUDO_UID', -1))
self._chgrp_to = int(os.environ.get('SUDO_GID', -1))
else:
self._chown_to = -1 # don't chown
self._chgrp_to = -1 # don't chgrp
if self._flag == "n":
with self._open(self._file_name, "wb", self._mode):
pass # just make sure it exists
else:
try:
f = self._open(self._file_name, "rb")
except IOError as e:
if self._flag != "c":
raise e
with self._open(self._file_name, "wb", self._mode):
pass # just make sure it exists
else:
p = f.read()
f.close()
if len(p) > 0:
try:
if bytes is not str:
self._dict = pickle.loads(p, encoding='bytes')
else:
self._dict = pickle.loads(p)
except (pickle.UnpicklingError, EOFError, KeyError):
# Note how we catch KeyErrors too here, which might happen
# when we don't have cPickle available (default pickle
# throws it).
if ignore_corrupt_dbfiles:
corruption_warning(self._file_name)
else:
raise
[docs] def close(self):
if self._needs_sync:
self.sync()
def __del__(self):
self.close()
[docs] def sync(self):
self._check_writable()
f = self._open(self._tmp_name, "wb", self._mode)
self._pickle_dump(self._dict, f, self._pickle_protocol)
f.close()
# Windows doesn't allow renaming if the file exists, so unlink
# it first, chmod'ing it to make sure we can do so. On UNIX, we
# may not be able to chmod the file if it's owned by someone else
# (e.g. from a previous run as root). We should still be able to
# unlink() the file if the directory's writable, though, so ignore
# any OSError exception thrown by the chmod() call.
try:
self._os_chmod(self._file_name, 0o777)
except OSError:
pass
self._os_unlink(self._file_name)
self._os_rename(self._tmp_name, self._file_name)
if self._os_chown is not None and self._chown_to > 0: # don't chown to root or -1
try:
self._os_chown(self._file_name, self._chown_to, self._chgrp_to)
except OSError:
pass
self._needs_sync = 00000
if keep_all_files:
self._shutil_copyfile(
self._file_name,
self._file_name + "_" + str(int(self._time_time())))
[docs] def _check_writable(self):
if self._flag == "r":
raise IOError("Read-only database: %s" % self._file_name)
def __getitem__(self, key):
return self._dict[key]
def __setitem__(self, key, value):
self._check_writable()
if not isinstance(key, str):
raise TypeError("key `%s' must be a string but is %s" % (key, type(key)))
if not isinstance(value, bytes):
raise TypeError("value `%s' must be a bytes but is %s" % (value, type(value)))
self._dict[key] = value
self._needs_sync = 0o001
[docs] def keys(self):
return list(self._dict.keys())
[docs] def has_key(self, key):
return key in self._dict
def __contains__(self, key):
return key in self._dict
[docs] def iterkeys(self):
# Wrapping name in () prevents fixer from "fixing" this
return (self._dict.iterkeys)()
__iter__ = iterkeys
def __len__(self):
return len(self._dict)
[docs]def open(file, flag=None, mode=0o666):
return dblite(file, flag, mode)
[docs]def _exercise():
db = open("tmp", "n")
assert len(db) == 0
db["foo"] = b"bar"
assert db["foo"] == b"bar"
db.sync()
db = open("tmp", "c")
assert len(db) == 1, len(db)
assert db["foo"] == b"bar"
db["bar"] = b"foo"
assert db["bar"] == b"foo"
db.sync()
db = open("tmp", "r")
assert len(db) == 2, len(db)
assert db["foo"] == b"bar"
assert db["bar"] == b"foo"
try:
db.sync()
except IOError as e:
assert str(e) == "Read-only database: tmp.dblite"
else:
raise RuntimeError("IOError expected.")
db = open("tmp", "w")
assert len(db) == 2, len(db)
db["ping"] = b"pong"
db.sync()
try:
db[(1, 2)] = "tuple"
except TypeError as e:
assert str(e) == "key `(1, 2)' must be a string but is <class 'tuple'>", str(e)
else:
raise RuntimeError("TypeError exception expected")
try:
db["list"] = [1, 2]
except TypeError as e:
assert str(e) == "value `[1, 2]' must be a bytes but is <class 'list'>", str(e)
else:
raise RuntimeError("TypeError exception expected")
db = open("tmp", "r")
assert len(db) == 3, len(db)
db = open("tmp", "n")
assert len(db) == 0, len(db)
dblite._open("tmp.dblite", "w")
db = open("tmp", "r")
dblite._open("tmp.dblite", "w").write("x")
try:
db = open("tmp", "r")
except pickle.UnpicklingError:
pass
else:
raise RuntimeError("pickle exception expected.")
global ignore_corrupt_dbfiles
ignore_corrupt_dbfiles = 2
db = open("tmp", "r")
assert len(db) == 0, len(db)
os.unlink("tmp.dblite")
try:
db = open("tmp", "w")
except IOError as e:
assert str(e) == "[Errno 2] No such file or directory: 'tmp.dblite'", str(e)
else:
raise RuntimeError("IOError expected.")
print("Completed _exercise()")
if __name__ == "__main__":
_exercise()
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