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Message-ID: <20160915032731.GE15995@brightrain.aerifal.cx>
Date: Wed, 14 Sep 2016 23:27:31 -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 11:02:16PM -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.
> ---
> 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.
> + ssize_t len;
> +
> + if ((len = strlen(name)) > 15) return ERANGE;
Storing the result of strlen in a ssize_t is odd. It works because no
object can be larger than SIZE_MAX/2, but it's ugly. Also using
strnlen would be preferable if there's a limit (so as not to read
unboundedly long strings only to reject them).
> +
> + snprintf(f, sizeof f, "/proc/self/task/%d/comm", thread->tid);
> + if ((fd = open(f, O_WRONLY)) < 0) return errno;
> + if (write(fd, name, len) < 0) status = errno;
> +
> + close(fd);
This needs blocking of the cancellation points, I think.
Rich
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