Re: [PATCH] Implement fchmodat4 system call

[CC += linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org]

Hello William,

Since this is a kernel-user-space API change, please CC linux-api@.
The kernel source file Documentation/SubmitChecklist notes that all
Linux kernel patches that change userspace interfaces should be CCed
to linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, so that the various parties who are
interested in API changes are informed. For further information, see
https://www.kernel.org/doc/man-pages/linux-api-ml.html

Aside from that, I've added a few other people/lists to CC that seem
likely to be relevant. Some additional comments below.

On Mon, May 11, 2015 at 4:07 AM, William Orr [off-list ref] wrote:

Hey,

Currently, Linux's fchmodat(2) doesn't honor the flags argument. To bring it
more in-line with POSIX and other implementations, this patch adds fchmodat4,
which honors the flags argument, and implements the same flags as fchownat(2).

This makes it possible to chmod a file without following symlinks, without
having to call open(2) on a file with O_NOFOLLOW. This is heavily based off
of Andrew Ayer's work in 2012, and is sent with his permission. Let me know
if this can be applied.

Please CC me, since I'm not subscribed to this list.

This seems an obviously sensible addition, and it was an obvious
mistake not to have a 'flags' argument in the original system call
(https://lwn.net/Articles/585415/). As well as getting us a proper
POSIX compliant API (and one that is consistent with other
implementations, such as FreeBSD), it allows for future behavior
expansion via the 'flags' argument.

Cheers,

Michael

-- 
Michael Kerrisk Linux man-pages maintainer;
http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface", http://blog.man7.org/