[RFC][glibc PATCH] fcntl-linux.h: add new definitions and manual updates for open file description locks
Michael Kerrisk (man-pages)
mtk.manpages at gmail.com
Wed Apr 23 13:13:03 MDT 2014
On Wed, Apr 23, 2014 at 9:00 PM, Alfred M. Szmidt <ams at gnu.org> wrote:
> > Likewise. You infact write that it does get the lock information
> > later in the document wrt. F_OFD_GETLK.
> Sorry, I disagree here...GETLK is really a misnomer, IMO. TESTLK
> would have been a better name.
I'm inclined to agree.
> GETLK are used is to "get the first lock".
> It's a way to test whether a particular lock can be applied, and to
> return information about a conflicting lock if it can't. If, for
> instance there is no conflicting lock, then you don't "get" any
> lock information back (l_type just gets reset to F_UNLCK).
> While I kinda see your point, it isn't what GETLK does; it really does
> get you information about the first lock -- you're not testing
> anything. It is also the terminology used in the POSIX standard.
The POSIX wording is a little confused. For example, what does "first"
mean in this context? F_GETLK returns information about one
(arbitrarily selected) lock that blocks a lock you would like to
place. So, I'm inclined to agree with Jeff -- this really is a "test"
(or "can I lock it") operation.
Of course, the operation has no reliable use: by the time it returns
the information might already be out of date. I suspect that it was
designed to solve the problem: "My F_GETLK operation failed. Who's
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