On 05/24/2016 06:42 AM, Hrubák, András wrote: > Dear Coreutils Dev Team, > > I made a patch for chmod. > It introduces an option `--cheap' to avoid real chmod (fchmodat) call > if the new mode seems equivalent to the old one. > It not only saves IO time, but also leaves ctime unchanged. While > ctime often plays role in updating/backuping/cleaning mechanisms, I > needed such a feature. > Please see it here: https://github.com/coreutils/coreutils/pull/6
Please post patches to this list, rather than making us chase pull requests. That said, it is unlikely that your patch will be applied, as it is fundamentally a TOCTTOU race - there is no race-free way to determine a file's current mode to know that the changed mode will not be different, because a concurrent operation can occur between your check and the (potentially-skipped) chmod; so we prefer to always do the chmod. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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