sysdeps/unix/sysv/linux/pthread_setname.c

   1 /* pthread_setname_np -- Set  thread name.  Linux version
   2    Copyright (C) 2010-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <pthreadP.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <sys/prctl.h>
  26
  27 #include <not-cancel.h>
  28
  29
  30 int
  31 pthread_setname_np (pthread_t th, const char *name)
  32 {
  33   const struct pthread *pd = (const struct pthread *) th;
  34
  35   /* Unfortunately the kernel headers do not export the TASK_COMM_LEN
  36      macro.  So we have to define it here.  */
  37 #define TASK_COMM_LEN 16
  38   size_t name_len = strlen (name);
  39   if (name_len >= TASK_COMM_LEN)
  40     return ERANGE;
  41
  42   if (pd == THREAD_SELF)
  43     return prctl (PR_SET_NAME, name) ? errno : 0;
  44
  45 #define FMT "/proc/self/task/%u/comm"
  46   char fname[sizeof (FMT) + 8];
  47   sprintf (fname, FMT, (unsigned int) pd->tid);
  48
  49   int fd = __open_nocancel (fname, O_RDWR);
  50   if (fd == -1)
  51     return errno;
  52
  53   int res = 0;
  54   ssize_t n = TEMP_FAILURE_RETRY (write_not_cancel (fd, name, name_len));
  55   if (n < 0)
  56     res = errno;
  57   else if (n != name_len)
  58     res = EIO;
  59
  60   close_not_cancel_no_status (fd);
  61
  62   return res;
  63 }