Re: [PATCH] 9pfs: fix dead code in qemu_open_flags_tostr()

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

On Monday, February 10, 2025 4:32:08 PM CET Philippe Mathieu-Daudé wrote:
> On 10/2/25 15:33, Christian Schoenebeck wrote:
> > Coverity scan complained about expression "|LARGEFILE" to be non reachable
> > and the detailed Coverity report claims O_LARGEFILE was zero. I can't
> > reproduce this here, but I assume that means there are at least some
> > system(s) which define O_LARGEFILE as zero.
> 
> Is O_LARGEFILE a Linux-ism?

Ah right, O_LARGEFILE is indeed Linux-specific, not POSIX.

> Commit 67b915a5dd5 ("win32 port (initial patch by kazu)") started to
> define it to 0 on 32-bit Windows. It isn't defined on my 64-bit Darwin,
> and apparently nor on other BSDs.

Yeah, that explains why O_LARGEFILE was defined as zero. I'll adjust the 
commit log message at least on my end. The code change itself is appropriate.

Thanks!

/Christian

> > This is not really an issue, but to silence this Coverity warning, add a
> > preprocessor wrapper that checks for O_LARGEFILE being non-zero for this
> > overall expression. The 'defined(O_LARGEFILE)' check is not necessary,
> > but it makes it more clear that we really want to check for the value of
> > O_LARGEFILE, not just whether the macro was defined.
> > 
> > Fixes: 9a0dd4b3
> > Resolves: Coverity CID 1591178
> > Reported-by: Coverity Scan
> > Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
> > ---
> >   hw/9pfs/9p-util-generic.c | 2 ++
> >   1 file changed, 2 insertions(+)
> > 
> > diff --git a/hw/9pfs/9p-util-generic.c b/hw/9pfs/9p-util-generic.c
> > index 4c1e9c887d..02e359f17b 100644
> > --- a/hw/9pfs/9p-util-generic.c
> > +++ b/hw/9pfs/9p-util-generic.c
> > @@ -19,7 +19,9 @@ char *qemu_open_flags_tostr(int flags)
> >           #ifdef O_DIRECT
> >           (flags & O_DIRECT) ? "|DIRECT" : "",
> >           #endif
> > +        #if defined(O_LARGEFILE) && O_LARGEFILE != 0
> >           (flags & O_LARGEFILE) ? "|LARGEFILE" : "",
> > +        #endif
> >           (flags & O_DIRECTORY) ? "|DIRECTORY" : "",
> >           (flags & O_NOFOLLOW) ? "|NOFOLLOW" : "",
> >           #ifdef O_NOATIME
> 
> 
>