sbase/renice.c

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/* See LICENSE file for copyright and license details. */
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#include <sys/resource.h>
#include <errno.h>
#include <limits.h>
#include <pwd.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "util.h"
static int strtop(const char *);
static bool renice(int, int, long);
static void eusage(void);
int
main(int argc, char **argv)
{
const char *adj = NULL;
long val;
int i, which = PRIO_PROCESS, status = 0;
ARGBEGIN {
case 'n':
adj = EARGF(eusage());
break;
case 'g':
which = PRIO_PGRP;
break;
case 'p':
which = PRIO_PROCESS;
break;
case 'u':
which = PRIO_USER;
break;
default:
eusage();
break;
} ARGEND;
if(argc == 0 || !adj)
eusage();
val = estrtol(adj, 10);
for(i = 0; i < argc; i++) {
int who = -1;
if(which == PRIO_USER) {
const struct passwd *pwd;
errno = 0;
do pwd = getpwnam(argv[i]); while(errno == EINTR);
if(pwd)
who = pwd->pw_uid;
else if(errno != 0) {
perror("can't read passwd");
status = 1;
continue;
}
}
if(who < 0)
who = strtop(argv[i]);
if(who < 0 || !renice(which, who, val))
status = 1;
}
return status;
}
static int
strtop(const char *s)
{
char *end;
long n;
errno = 0;
n = strtol(s, &end, 10);
if(*end != '\0') {
fprintf(stderr, "%s: not an integer\n", s);
return -1;
}
if(errno != 0 || n <= 0 || n > INT_MAX) {
fprintf(stderr, "%s: invalid value\n", s);
return -1;
}
return (int)n;
}
static bool
renice(int which, int who, long adj)
{
errno = 0;
adj += getpriority(which, who);
if(errno != 0) {
fprintf(stderr, "can't get %d nice level: %s\n",
who, strerror(errno));
return false;
}
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/* PRIO_{MIN,MAX} does not exist in musl libc */
adj = MAX(-20, MIN(adj, 20));
if(setpriority(which, who, (int)adj) == -1) {
fprintf(stderr, "can't set %d nice level: %s\n",
who, strerror(errno));
return false;
}
return true;
}
static void
eusage(void)
{
eprintf("renice -n inc [-g | -p | -u] ID ...\n");
}