glibc/sysdeps/unix/sysv/linux/getpriority.c

45 lines
1.5 KiB
C

/* getpriority for Linux.
Copyright (C) 1996-2014 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; if not, see
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <sys/resource.h>
#include <sysdep.h>
#include <sys/syscall.h>
/* The return value of getpriority syscall is biased by this value
to avoid returning negative values. */
#define PZERO 20
/* Return the highest priority of any process specified by WHICH and WHO
(see above); if WHO is zero, the current process, process group, or user
(as specified by WHO) is used. A lower priority number means higher
priority. Priorities range from PRIO_MIN to PRIO_MAX. */
int
getpriority (enum __priority_which which, id_t who)
{
int res;
res = INLINE_SYSCALL (getpriority, 2, (int) which, who);
if (res >= 0)
res = PZERO - res;
return res;
}
libc_hidden_def (getpriority)