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[glibc.git] / sysdeps / unix / nice.c
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1 /* Copyright (C) 1992, 1996 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 Library General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 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 Library General Public License for more details.
14 You should have received a copy of the GNU Library General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If
16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
17 Cambridge, MA 02139, 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 (incr)
27 int incr;
29 int save;
30 int prio;
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 return setpriority (PRIO_PROCESS, 0, prio + incr);