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[glibc.git] / sysdeps / unix / nice.c
blob700305c0e9b18754972c764c1bc709822b8ca5c1
1 /* Copyright (C) 1992, 1996, 1997, 2001, 2002 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, write to the Free
16 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
17 02111-1307 USA. */
19 #include <errno.h>
20 #include <unistd.h>
21 #include <sys/resource.h>
23 /* Increment the scheduling priority of the calling process by INCR.
24 The superuser may use a negative INCR to decrement the priority. */
25 int
26 nice (int incr)
28 int save;
29 int prio;
30 int result;
32 /* -1 is a valid priority, so we use errno to check for an error. */
33 save = errno;
34 __set_errno (0);
35 prio = getpriority (PRIO_PROCESS, 0);
36 if (prio == -1)
38 if (errno != 0)
39 return -1;
40 else
41 __set_errno (save);
44 result = setpriority (PRIO_PROCESS, 0, prio + incr);
45 if (result != -1)
46 return getpriority (PRIO_PROCESS, 0);
47 else
48 return -1;