Re: [PATCH][BZ 21340] add support for POSIX_SPAWN_SETSID

[Florian Weimer <fweimer at redhat dot com>]

On 04/03/2017 09:35 PM, Adhemerval Zanella wrote:
> On 03/04/2017 16:12, Florian Weimer wrote:
> > On 04/01/2017 04:29 PM, daurnimator wrote:
> > > diff --git a/posix/spawn.h b/posix/spawn.h
> > > index 36e3867e17..8d2ace1b87 100644
> > > --- a/posix/spawn.h
> > > +++ b/posix/spawn.h
> > > @@ -60,6 +60,7 @@ typedef struct
> > >  #ifdef __USE_GNU
> > >  # define POSIX_SPAWN_USEVFORK        0x40
> > >  #endif
> > > +#define POSIX_SPAWN_SETSID        0x80
> >
> > Doesn't this add the flag to past POSIX versions?
>
> I do not think this is an issue since afaik POSIX does not state any
> constraint regarding the flags values [1].  For instance, the example
> library implementation uses spawn as example and just use constant
> different than glibc [2].

Sorry, this is not what I meant.  I was wondering if it was acceptable, 
from a namespace point of view, to define the constant unconditionally, 
or if we have to use a feature test macro here.

> > I wonder if we should add a new symbol version for posix_spawnattr_setflags, so that applications which do not perform error checking for the function call fail in a predictable manner.
>
> I do not follow, which semantic difference are you proposing for
> posix_spawnattr_setflags that are not covered currently?

I'm worried about applications which ignore the error return value from 
posix_spawnattr_setflags, use POSIX_SPAWN_SETSID, and accidentally spawn 
processes with the wrong flags.

Thanks,
Florian