Re: flock(2): locking against itself?

[David Holland <dholland-tech%netbsd.org@localhost>]

On Sun, Mar 19, 2023 at 01:49:54PM +0700, Robert Elz wrote:
 >   | Except they aren't.  They're on open file table entries, something
 >   | remarkably difficult to describe in a way that doesn't just refer to
 >   | the kernel-internal mechanism behind it
 > 
 > Yes.  The terminology in this area really sucks, but that's why
 > I mentioned 'kernel file*' in my message.   POSIX distinguishes
 > file descriptors and file descriptions, but you have to be reading
 > very carefully to even notice the difference - ok for a standards
 > doc perhaps, not for a man page or e-mail message.
 > 
 > Given the lack of well understood terminology, it is not easy to
 > do better.  That, I assume, is what led to that paragraph in the
 > NOTES section - an attempt to explain better just where the locks
 > fit, without getting into kernel internals (the access model the
 > kernel provides, that is, fd, file*, vnode, data, really needs to
 > be understood in order to do any non-trivial file related
 > operations).

"They're per-open"

...which is not actually difficult to understand since it's the same
as the seek pointer behavior; that is, seek pointers are per-open too.

-- 
David A. Holland
dholland%netbsd.org@localhost