Source code for SCons.dblite

"""
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() # Local Variables: # tab-width:4 # indent-tabs-mode:nil # End: # vim: set expandtab tabstop=4 shiftwidth=4: