glibc/sysdeps/posix/nice.c

52 lines
1.5 KiB
C

/* Copyright (C) 1992-2016 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 <unistd.h>
#include <sys/resource.h>
/* Increment the scheduling priority of the calling process by INCR.
The superuser may use a negative INCR to decrement the priority. */
int
nice (int incr)
{
int save;
int prio;
int result;
/* -1 is a valid priority, so we use errno to check for an error. */
save = errno;
__set_errno (0);
prio = __getpriority (PRIO_PROCESS, 0);
if (prio == -1)
{
if (errno != 0)
return -1;
}
result = __setpriority (PRIO_PROCESS, 0, prio + incr);
if (result == -1)
{
if (errno == EACCES)
__set_errno (EPERM);
return -1;
}
__set_errno (save);
return __getpriority (PRIO_PROCESS, 0);
}