nptl/pthread_getname.c

   1 /* pthread_getname_np -- Get  thread name.  Linux version
   2    Copyright (C) 2010-2022 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 <https://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 #include <not-cancel.h>
  27 #include <shlib-compat.h>
  28
  29 int
  30 __pthread_getname_np (pthread_t th, char *buf, size_t len)
  31 {
  32   const struct pthread *pd = (const struct pthread *) th;
  33
  34   /* Unfortunately the kernel headers do not export the TASK_COMM_LEN
  35      macro.  So we have to define it here.  */
  36 #define TASK_COMM_LEN 16
  37   if (len < TASK_COMM_LEN)
  38     return ERANGE;
  39
  40   if (pd == THREAD_SELF)
  41     return __prctl (PR_GET_NAME, buf) ? errno : 0;
  42
  43 #define FMT "/proc/self/task/%u/comm"
  44   char fname[sizeof (FMT) + 8];
  45   sprintf (fname, FMT, (unsigned int) pd->tid);
  46
  47   int fd = __open64_nocancel (fname, O_RDONLY);
  48   if (fd == -1)
  49     return errno;
  50
  51   int res = 0;
  52   ssize_t n = TEMP_FAILURE_RETRY (__read_nocancel (fd, buf, len));
  53   if (n < 0)
  54     res = errno;
  55   else
  56     {
  57       if (buf[n - 1] == '\n')
  58         buf[n - 1] = '\0';
  59       else if (n == len)
  60         res = ERANGE;
  61       else
  62         buf[n] = '\0';
  63     }
  64
  65   __close_nocancel_nostatus (fd);
  66
  67   return res;
  68 }
  69 versioned_symbol (libc, __pthread_getname_np, pthread_getname_np,
  70                   GLIBC_2_34);
  71
  72 #if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_12, GLIBC_2_34)
  73 compat_symbol (libpthread, __pthread_getname_np, pthread_getname_np,
  74                GLIBC_2_12);
  75 #endif