Veracity of "attributes modified" date
Veracity of "attributes modified" date
- Subject: Veracity of "attributes modified" date
- From: James Bucanek <email@hidden>
- Date: Wed, 19 Sep 2012 18:30:40 -0700
Greetings again,
Question: What filesystem object metadata changes will cause the
'attribute change time' (ATTR_CMN_CHGTIME) property to be updated?
The reason I'm asking:
I've been working to build a better directory scanner that looks
for modified files (this is for a backup solution).
In the past, I've obtained almost all of the available metadata
for every item and compared that with what's been backed up.
This includes:
creation date
modified date
attributes modified date
owner ID
group ID
access flags
file flags
name encoding hint
ACLs
extended attributes
link count
logical data fork length (files only)
logical resource fork length (files only)
I'd like to update my code to use NSURL/CFURL but some of this
metadata doesn't appear to be available through that API. (At
least I can't find keys for things like the UID, GID, access
flags, file flags, and so on.) This means I have to use
secondary calls for every item to obtain the other metadata,
which *really* slows the process down.
It occurred to me, however, that I might not have to get and
compare every morsel of metadata if I can depend on the
ATTR_CMN_CHGTIME to be updated whenever the object's metadata
changes. For example, it would be great to just compare the
CHGTIME of two items instead of manually comparing their
ownership, file flags, ACLs, and extended attributes.
Naturally, this is a shortcut and there's the obvious
possibility the a filesystem object could have its "attribute
changed" time set so that it appears not to have changed when it
has. That's something I can deal with.
Thanks in advance,
James
--
James Bucanek
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