This is a maintenance fork
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program 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 │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/safemacros.h"
#include "libc/calls/calls.h"
#include "libc/fmt/conv.h"
#include "libc/sysv/consts/prio.h"
static int clamp(int p) {
return max(-NZERO, min(NZERO - 1, p));
}
/**
* Changes process priority.
*
* @param delta is added to current priority w/ clamping
* @return new priority, or -1 w/ errno
* @see Linux claims ioprio_set() is tuned automatically by this
*/
int nice(int delta) {
int p;
if (abs(delta) >= NZERO * 2) {
p = delta;
} else {
delta = clamp(delta);
if ((p = getpriority(PRIO_PROCESS, 0)) == -1) return -1;
p += delta;
}
p = clamp(p);
if (setpriority(PRIO_PROCESS, 0, p) == -1) return -1;
return p;
}