sysdeps/unix/sysv/linux/getpriority.c

   1 /* getpriority for Linux.
   2    Copyright (C) 1996,98,2000,02,03 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
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <sys/resource.h>
  22
  23 #include <sysdep.h>
  24 #include <sys/syscall.h>
  25
  26 /* The return value of getpriority syscall is biased by this value
  27    to avoid returning negative values.  */
  28 #define PZERO 20
  29
  30 /* Return the highest priority of any process specified by WHICH and WHO
  31    (see above); if WHO is zero, the current process, process group, or user
  32    (as specified by WHO) is used.  A lower priority number means higher
  33    priority.  Priorities range from PRIO_MIN to PRIO_MAX.  */
  34
  35 int
  36 getpriority (enum __priority_which which, id_t who)
  37 {
  38   int res;
  39
  40   res = INLINE_SYSCALL (getpriority, 2, (int) which, who);
  41   if (res >= 0)
  42     res = PZERO - res;
  43   return res;
  44 }
  45 libc_hidden_def (getpriority)