Date: Sat, 29 Oct 2011 23:40:58 +0200 From: Jilles Tjoelker <jilles@stack.nl> To: John Baldwin <jhb@freebsd.org> Cc: arch@freebsd.org Subject: Re: [PATCH] fadvise(2) system call Message-ID: <20111029214057.GB90408@stack.nl> In-Reply-To: <201110281426.00013.jhb@freebsd.org> References: <201110281426.00013.jhb@freebsd.org>
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On Fri, Oct 28, 2011 at 02:25:59PM -0400, John Baldwin wrote:
> I have been working for the last week or so on a patch to add an
> fadvise(2) system call. It is somewhat similar to madvise(2) except
> that it operates on a file descriptor instead of a memory region. It
> also only really makes sense for regular files and does not apply to
> other file descriptor types.
Cool.
Various other posix_* functions such as posix_spawn() and posix_openpt()
are implemented directly, not as a wrapper around s/posix_//. I think
posix_madvise() is only implemented as a wrapper because madvise()
already existed. Therefore, I don't see a reason why a function named
fadvise would be useful on its own (except if there are existing
applications that use that name).
If the advice is FADV_SEQUENTIAL, FADV_RANDOM or FADV_NOREUSE and the
file descriptor is invalid (fget() fails), the struct fadvise_info is
leaked.
The comparisons
+ (fa->fa_start != 0 && fa->fa_start == end + 1) ||
+ (uap->offset != 0 && fa->fa_end + 1 == uap->offset))) {
should instead be something like
+ (end != OFF_MAX && fa->fa_start == end + 1) ||
+ (fa->fa_end != OFF_MAX && fa->fa_end + 1 == uap->offset))) {
to avoid integer overflow.
--
Jilles Tjoelker
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