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SubjectRe: Bug in open() function (?)
Date
> > On Fri, 11 Jul 2003 22:23:00 PDT, Andrew Morton said:

> >

> > > We've lived with it for this long.

> >

> > Well... you have a point there..

> >

> > > Given that the behaviour is undefined, the behaviour which we should

> > > implement is clearly "whatever 2.4 is doing". So let's leave it
alone.

> >

> > I suppose I could live with that *IF* somebody fixes 'man 2 open' to

> > reflect reality.

>

> Corrections and additions to manpages are always welcome.

> Mail to aeb@cwi.nl .

>

>

> (Concerning the topic under discussion, the man page says

>

> O_TRUNC

> If the file already exists and is a regular file

> and the open mode allows writing (i.e., is O_RDWR

> or O_WRONLY) it will be truncated to length 0. If

> the file is a FIFO or terminal device file, the

> O_TRUNC flag is ignored. Otherwise the effect of

> O_TRUNC is unspecified.

>

> which is precisely right. It continues

>

> (On many Linux versions it

> will be ignored; on other versions it will return

> an error.)

>

> where someone may read this as if this is an exhaustive list of

> possibilities. So adding ", or actually do the truncate" will

> clarify.)

>

>

> Concerning the desired behaviour: if I recall things correctly

> doing the truncate was old SunOS behaviour, not doing it,

> that is, honouring the O_RDONLY, is new Solaris behaviour.

> Maybe someone with access to such machines can check.

>

> Software exists that does O_RDONLY | O_TRUNC.



A late addition to this thread, but all of these systems DO truncate with

O_RDONLY | O_TRUNC:



Solaris 8

Tru64 5.1B

HP-UX 11.22

FreeBSD 4.7



Although this flag combination is left unspecified by SUSv3, I don't

know of an implementation that DOESN'T truncate in these circumstances.



Cheers



Michael

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