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Keep mbox files open, so we don't break our locks 

When committing a changed mbox, don't use os.rename(), and don't open/close
the mbox file to truncate it to zero length.  Locking was pretty much broken
before -- at least in theory a quite severe bug.
This commit is contained in:
Nikolaus Schulz 2008-08-05 18:02:56 +02:00
parent ba8928d279
commit a78af4c0ff
1 changed files with 17 additions and 34 deletions
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51
archivemail.py
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@ -471,15 +471,9 @@ class Mbox(mailbox.UnixMailbox):
_stale.procmail_lock = None
def leave_empty(self):
"""Replace the 'mbox' mailbox with a zero-length file.
This should be the same as 'cp /dev/null mailbox'.
This will leave a zero-length mailbox file so that mail
reading programs don't get upset that the mailbox has been
completely deleted."""
assert(os.path.isfile(self.mbox_file_name))
"""Truncate the 'mbox' mailbox to zero-length."""
vprint("turning '%s' into a zero-length file" % self.mbox_file_name)
blank_file = open(self.mbox_file_name, "w")
blank_file.close()
self.mbox_file.truncate(0)
def get_size(self):
"""Return the current size of the mbox file"""
@ -493,42 +487,32 @@ class RetainMbox(Mbox):
overwrite the original mailbox if everything is OK.
"""
__final_name = None
def __init__(self, final_name):
def __init__(self, final_mbox_file):
"""Constructor - create a temporary file for the mailbox.
Arguments:
final_name -- the name of the original mailbox that this mailbox
final_mbox_file -- file object of the original mailbox that this mailbox
will replace when we call finalise()
"""
assert(final_name)
assert(final_mbox_file)
temp_name = tempfile.mkstemp("retain")[1]
self.mbox_file = open(temp_name, "w")
self.mbox_file = open(temp_name, "w+")
self.mbox_file_name = temp_name
_stale.retain = temp_name
vprint("opened temporary retain file '%s'" % self.mbox_file_name)
self.__final_name = final_name
self.__final_mbox_file = final_mbox_file
def finalise(self):
"""Overwrite the original mailbox with this temporary mailbox."""
assert(self.__final_name)
self.close()
# make sure that the retained mailbox has the same
# permission as the original mailbox
mode = os.stat(self.__final_name)[stat.ST_MODE]
os.chmod(self.mbox_file_name, mode)
vprint("renaming '%s' to '%s'" % (self.mbox_file_name, self.__final_name))
try:
os.rename(self.mbox_file_name, self.__final_name)
except OSError:
# file might be on a different filesystem -- move it manually
shutil.copy(self.mbox_file_name, self.__final_name)
os.remove(self.mbox_file_name)
_stale.retain = None
assert(self.__final_mbox_file)
vprint("writing back '%s' to '%s'" % (self.mbox_file_name, self.__final_mbox_file.name))
self.mbox_file.seek(0)
self.__final_mbox_file.seek(0)
shutil.copyfileobj(self.mbox_file, self.__final_mbox_file)
self.__final_mbox_file.truncate()
self.remove()
def remove(self):
"""Delete this temporary mailbox. Overrides Mbox.remove()"""
@ -1185,17 +1169,14 @@ def _archive_mbox(mailbox_name, final_archive_name):
vprint("decision: retain message")
if not options.dry_run and not options.copy_old_mail:
if (not retain):
retain = RetainMbox(mailbox_name)
retain = RetainMbox(original.mbox_file)
retain.write(msg)
msg = original.next()
vprint("finished reading messages")
original.exclusive_unlock()
original.close()
if original.starting_size != original.get_size():
unexpected_error("the mailbox '%s' changed size during reading!" % \
mailbox_name)
if not options.dry_run:
if retain: retain.close()
if archive: archive.close()
if options.delete_old_mail:
# we will never have an archive file
@ -1217,6 +1198,8 @@ def _archive_mbox(mailbox_name, final_archive_name):
if retain:
# retain will be the same as original mailbox
retain.remove()
original.exclusive_unlock()
original.close()
original.reset_timestamps()
original.procmail_unlock()
if not options.quiet: