truncate and open(O_TRUNC) times.

[Chris Johns]

Bruce Evans wrote:
>
> I just checked some details for another bug involving [f]truncate() and
> the file size limit. They are specified to act the same (SIGFXSZ with
> no change in the file) above the limit, but for most file systems including
> ffs, neither checks. So the flag isn't needed to fix this bug. It is
> write() that acts differently. It is specified to write up to the limit
> and then return a short write with no SIGXFXSZ if the file pointer is
> initially before the limit; otherwise SIGFXSZ with no change to the file
> (or file times?). But for most file systems including ffs, write() fails
> with SIGFXSZ and no change in the file if the result of a full successful
> write would be above the limit. This is mostly a bug in POSIX. It makes
> short write()s possible for any write(), where users can easily arrange
> for foot shooting using their soft rlimit, but almost no applications
> understand short writes.

Applications running on RTEMS with its limited resources need to know 
this and we have a test to make sure this is handled correctly by all 
file systems.

Chris