From: Zooko O'Whielacronx zooko@zooko.com Date: Sat, 14 Apr 2007 17:54:02 +0000 (+0530) Subject: pyfec: import a copy of fileutil.py from the pyutil library X-Git-Url: https://git.rkrishnan.org/frontends/sub?a=commitdiff_plain;h=bf79dfb5d306588bce3d1388f8f47b610b01e9a4;p=tahoe-lafs%2Fzfec.git pyfec: import a copy of fileutil.py from the pyutil library darcs-hash:7cd00a70c4cc7417f1d40dae42f3f464364b236c --- diff --git a/pyfec/fec/util/fileutil.py b/pyfec/fec/util/fileutil.py new file mode 100644 index 0000000..ef75cc6 --- /dev/null +++ b/pyfec/fec/util/fileutil.py @@ -0,0 +1,186 @@ +# Copyright (c) 2000 Autonomous Zone Industries +# Copyright (c) 2002-2007 Bryce "Zooko" Wilcox-O'Hearn +# This file is licensed under the +# GNU Lesser General Public License v2.1. +# See the file COPYING or visit http://www.gnu.org/ for details. +# Portions snarfed out of the Python standard library. +# The du part is due to Jim McCoy. + +""" +Futz with files like a pro. +""" + +import exceptions, os, stat, tempfile, time + +try: + from twisted.python import log +except ImportError: + class DummyLog: + def msg(self, *args, **kwargs): + pass + log = DummyLog() + +def rename(src, dst, tries=4, basedelay=0.1): + """ Here is a superkludge to workaround the fact that occasionally on + Windows some other process (e.g. an anti-virus scanner, a local search + engine, etc.) is looking at your file when you want to delete or move it, + and hence you can't. The horrible workaround is to sit and spin, trying + to delete it, for a short time and then give up. + + With the default values of tries and basedelay this can block for less + than a second. + + @param tries: number of tries -- each time after the first we wait twice + as long as the previous wait + @param basedelay: how long to wait before the second try + """ + for i in range(tries-1): + try: + return os.rename(src, dst) + except EnvironmentError, le: + # XXX Tighten this to check if this is a permission denied error (possibly due to another Windows process having the file open and execute the superkludge only in this case. + log.msg("XXX KLUDGE Attempting to move file %s => %s; got %s; sleeping %s seconds" % (src, dst, le, basedelay,)) + time.sleep(basedelay) + basedelay *= 2 + return os.rename(src, dst) # The last try. + +def remove(f, tries=4, basedelay=0.1): + """ Here is a superkludge to workaround the fact that occasionally on + Windows some other process (e.g. an anti-virus scanner, a local search + engine, etc.) is looking at your file when you want to delete or move it, + and hence you can't. The horrible workaround is to sit and spin, trying + to delete it, for a short time and then give up. + + With the default values of tries and basedelay this can block for less + than a second. + + @param tries: number of tries -- each time after the first we wait twice + as long as the previous wait + @param basedelay: how long to wait before the second try + """ + try: + os.chmod(f, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD) + except: + pass + for i in range(tries-1): + try: + return os.remove(f) + except EnvironmentError, le: + # XXX Tighten this to check if this is a permission denied error (possibly due to another Windows process having the file open and execute the superkludge only in this case. + if not os.path.exists(f): + return + log.msg("XXX KLUDGE Attempting to remove file %s; got %s; sleeping %s seconds" % (f, le, basedelay,)) + time.sleep(basedelay) + basedelay *= 2 + return os.remove(f) # The last try. + +class NamedTemporaryDirectory: + """ + This calls tempfile.mkdtemp(), stores the name of the dir in + self.name, and rmrf's the dir when it gets garbage collected or + "shutdown()". + """ + def __init__(self, cleanup=True, *args, **kwargs): + """ If cleanup, then the directory will be rmrf'ed when the object is shutdown. """ + self.cleanup = cleanup + self.name = tempfile.mkdtemp(*args, **kwargs) + + def __repr__(self): + return "<%s instance at %x %s>" % (self.__class__.__name__, id(self), self.name) + + def __str__(self): + return self.__repr__() + + def __del__(self): + try: + self.shutdown() + except: + import traceback + traceback.print_exc() + + def shutdown(self): + if self.cleanup and hasattr(self, 'name'): + rm_dir(self.name) + +def make_dirs(dirname, mode=0777, strictmode=False): + """ + A threadsafe and idempotent version of os.makedirs(). If the dir already + exists, do nothing and return without raising an exception. If this call + creates the dir, return without raising an exception. If there is an + error that prevents creation or if the directory gets deleted after + make_dirs() creates it and before make_dirs() checks that it exists, raise + an exception. + + @param strictmode if true, then make_dirs() will raise an exception if the + directory doesn't have the desired mode. For example, if the + directory already exists, and has a different mode than the one + specified by the mode parameter, then if strictmode is true, + make_dirs() will raise an exception, else it will ignore the + discrepancy. + """ + tx = None + try: + os.makedirs(dirname, mode) + except OSError, x: + tx = x + + if not os.path.isdir(dirname): + if tx: + raise tx + raise exceptions.IOError, "unknown error prevented creation of directory, or deleted the directory immediately after creation: %s" % dirname # careful not to construct an IOError with a 2-tuple, as that has a special meaning... + + tx = None + if hasattr(os, 'chmod'): + try: + os.chmod(dirname, mode) + except OSError, x: + tx = x + + if strictmode and hasattr(os, 'stat'): + s = os.stat(dirname) + resmode = stat.S_IMODE(s.st_mode) + if resmode != mode: + if tx: + raise tx + raise exceptions.IOError, "unknown error prevented setting correct mode of directory, or changed mode of the directory immediately after creation. dirname: %s, mode: %04o, resmode: %04o" % (dirname, mode, resmode,) # careful not to construct an IOError with a 2-tuple, as that has a special meaning... + +def rm_dir(dirname): + """ + A threadsafe and idempotent version of shutil.rmtree(). If the dir is + already gone, do nothing and return without raising an exception. If this + call removes the dir, return without raising an exception. If there is an + error that prevents deletion or if the directory gets created again after + rm_dir() deletes it and before rm_dir() checks that it is gone, raise an + exception. + """ + excs = [] + try: + os.chmod(dirname, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD) + for f in os.listdir(dirname): + fullname = os.path.join(dirname, f) + if os.path.isdir(fullname): + rm_dir(fullname) + else: + remove(fullname) + os.rmdir(dirname) + except Exception, le: + # Ignore "No such file or directory" + if (not isinstance(le, OSError)) or le.args[0] != 2: + excs.append(le) + + # Okay, now we've recursively removed everything, ignoring any "No + # such file or directory" errors, and collecting any other errors. + + if os.path.exists(dirname): + if len(excs) == 1: + raise excs[0] + if len(excs) == 0: + raise OSError, "Failed to remove dir for unknown reason." + raise OSError, excs + + +def remove_if_possible(f): + try: + remove(f) + except: + pass