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Date: Thu, 15 Sep 2016 00:17:16 -0400
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: [PATCH RFC] add pthread_setname_np
On Wed, Sep 14, 2016 at 11:43:51PM -0400, Felix Janda wrote:
> Rich Felker wrote:
>
> Thanks for the review!
>
> > On Wed, Sep 14, 2016 at 11:02:16PM -0400, Felix Janda wrote:
> > > gdb's "info threads" displays the thread name.
> > > ---
> > > Should this function care about interrupted syscalls?
> >
> > Unless it's specified not to return EINTR I'm fine with it returning
> > EINTR.
>
> ok. Is it possible that write() is interrupted with partial data
> written (so that it won't return -1)?
That won't happen with these proc pseudo-files because the write is
required by the kernel to be atomic. If it's broken up into multiple
parts, the kernel only uses the last one.
> > > include/pthread.h | 1 +
> > > src/thread/pthread_setname_np.c | 21 +++++++++++++++++++++
> > > 2 files changed, 22 insertions(+)
> > > create mode 100644 src/thread/pthread_setname_np.c
> > >
> > > diff --git a/include/pthread.h b/include/pthread.h
> > > index 3d2e0c4..94ef919 100644
> > > --- a/include/pthread.h
> > > +++ b/include/pthread.h
> > > @@ -214,6 +214,7 @@ struct cpu_set_t;
> > > int pthread_getaffinity_np(pthread_t, size_t, struct cpu_set_t *);
> > > int pthread_setaffinity_np(pthread_t, size_t, const struct cpu_set_t *);
> > > int pthread_getattr_np(pthread_t, pthread_attr_t *);
> > > +int pthread_setname_np(pthread_t, const char *);
> > > int pthread_tryjoin_np(pthread_t, void **);
> > > int pthread_timedjoin_np(pthread_t, void **, const struct timespec *);
> > > #endif
> > > diff --git a/src/thread/pthread_setname_np.c b/src/thread/pthread_setname_np.c
> > > new file mode 100644
> > > index 0000000..b7f7a4b
> > > --- /dev/null
> > > +++ b/src/thread/pthread_setname_np.c
> > > @@ -0,0 +1,21 @@
> > > +#include <fcntl.h>
> > > +#include <string.h>
> > > +#include <unistd.h>
> > > +
> > > +#include "pthread_impl.h"
> > > +
> > > +int pthread_setname_np(pthread_t thread, const char *name)
> > > +{
> > > + int fd, status = 0;
> > > + char f[sizeof "/proc/self/task//comm" + 7];
> >
> > Where does 7 come from? I don't think it's correct. 3*sizeof(int) is
> > the normal lazy bound we use for %d's.
>
> man 5 proc
>
> says that the maximum value for a pid is about 4 million. I'm fine with
> to changing it to the usual lazy bound, though.
Ah. That may be true for all current versions of Linux, but I don't
think it counts as part of the API/ABI. The ABI limit on pids is 512M
IIRC (because high bits have special meaning in robust/PI futex ABI).
Rich
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