Re: [9fans] 9fs/9auth for FreeBSD

[Alexander Viro <viro@math.psu.edu>]

On Wed, 28 Mar 2001, Lyndon Nerenberg wrote:

> >>>>> "Alexander" == Alexander Viro <viro@math.psu.edu> writes:
> 
>     Alexander> PS: POSIX says nothing, since append-only is BSDism and
>     Alexander> POSIX is a codification of Missed'em'V bugs, so
>     Alexander> append-only is out of scope.
> 
> Let's make sure we're talking about the same thing here. The chflags()
> behaviour is 4.4BSD-specific. The O_APPEND behaviour has been around
> since the dawn of time (or at least SVR1). My copy of POSIX is at
> home, however SuS V2 states explicitly (both open(2) and write(2))
> that O_APPEND causes all writes to set the file pointer to the end of
> the file prior to performing the write I/O, and that the combination
> of the implicit seek and the associated write are atomic.

Wait a second. The question being: what happens if you open append-only
file with fd = open("foo", O_RDWR), then lseek(fd, 0, SEEK_SET), then
write(fd, buf, len)?
	Plan9: append to EOF.
	Linux: -EPERM on open()
	FreeBSD: -EPERM on write() (open() succeeds).