/* pthread_setname_np -- Set  thread name.  Linux version

   Copyright (C) 2010-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public License as

   published by the Free Software Foundation; either version 2.1 of the

   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; see the file COPYING.LIB.  If

   not, see <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#include <fcntl.h>

#include <pthreadP.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include <sys/prctl.h>

#include <not-cancel.h>

int

pthread_setname_np (pthread_t th, const char *name)

{

  const struct pthread *pd = (const struct pthread *) th;

  /* Unfortunately the kernel headers do not export the TASK_COMM_LEN

     macro.  So we have to define it here.  */

#define TASK_COMM_LEN 16

  size_t name_len = strlen (name);

  if (name_len >= TASK_COMM_LEN)

    return ERANGE;

  if (pd == THREAD_SELF)

    return prctl (PR_SET_NAME, name) ? errno : 0;

#define FMT "/proc/self/task/%u/comm"

  char fname[sizeof (FMT) + 8];

  sprintf (fname, FMT, (unsigned int) pd->tid);

  int fd = __open64_nocancel (fname, O_RDWR);

  if (fd == -1)

    return errno;

  int res = 0;

  ssize_t n = TEMP_FAILURE_RETRY (__write_nocancel (fd, name, name_len));

  if (n < 0)

    res = errno;

  else if (n != name_len)

    res = EIO;

  __close_nocancel_nostatus (fd);

  return res;

}