Open with O_APPEND fails

[Mel]

On Saturday 27 December 2008 21:06:58 Jonathan Chen wrote:
> On Sun, Dec 28, 2008 at 05:46:39AM +0100, Mitar wrote:
> > Hi!
> >
> > On Sun, Dec 28, 2008 at 5:10 AM, Mel
> >
> > <fbsd.questions at rachie.is-a-geek.net> wrote:
> > > open(2) will succeed but write(2) will fail with EBADF as documented
> > > (and I verified this behavior). Still no EACCES as you and the
> > > bugreporter are seeing.
> >
> > Where is documented that write would fail if file is opened only with
> > O_APPEND?

Implicitly in write(2) manpage:
     The write(), writev(), pwrite() and pwritev() system calls will fail and
     the file pointer will remain unchanged if:

     [EBADF]            The d argument is not a valid descriptor open for
                        writing.

> > Just O_APPEND should also open file for writing as appending 
> > is also writing. It cannot be used without "write" semantics so file
> > has to be open also for writing.
>
> If I recall correctly, this behaviour has been standard on UNIX-like
> OS's for a *very* long time now. If you are seeing a write allowed
> with just O_APPEND on Linux, it would very likely be a Linux only
> "feature".

Yup. Append is a bad english choice for the constant as it implies writes like 
you say, but really should be O_ATEND, because that's all that it does: seek 
to EOF.

-- 
Mel

Problem with today's modular software: they start with the modules
    and never get to the software part.