Re: [PATCH 1/2] Add pthread_getname_np and pthread_setname_np

[Jon Turney <jon dot turney at dronecode dot org dot uk>]

On 28/07/2016 20:21, Corinna Vinschen wrote:
> Hi Jon,
>
> On Jul 28 12:43, Jon Turney wrote:
> > This patch adds pthread_getname_np and pthread_setname_np.
> >
> > These were added to glibc in 2.12[1] and are also present in some form on
> > NetBSD and several UNIXes.
> >
> > The code is based on NetBSD's implementation with changes to better match
> > Linux behaviour.
> >
> > Implementation quirks:
> >
> > * pthread_setname_np with a NULL pointer segfaults (as linux)
> >
> > * pthread_setname_np accepts names longer than 16 characters (linux returns
> > ERANGE)
>
> Given the behaviour of pthread_getname_np we should do the same, I think.

Ok.

> > * pthread_getname_np with a NULL pointer returns EFAULT (as linux)
> >
> > * pthread_getname_np with a buffer length of less than 16 returns ERANGE (as
> > linux)
> >
> > * pthread_getname_np truncates the thread name to fit the buffer length.
> > This guarantees success even when the default thread name is longer than 16
> > characters, but means there is no way to discover the actual length of the
> > thread name. (Linux always truncates the thread name to 16 characters)
> >
> > * Changing program_invocation_short_name changes the default thread name.
> >
> > I'll leave it up to you to decide any of these matter.
> >
> > This is implemented via class pthread_attr to make it easier to add
> > pthread_attr_[gs]etname_np (present in NetBSD and some UNIXes) should it
> > ever be added to Linux (or we decide we want it anyway).
>
> Good thinking.

Yaakov's idea, not mine :)