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/* vi: set sw=4 ts=4: */
/*
* nice implementation for busybox
*
* Copyright (C) 2005 Manuel Novoa III <mjn3@codepoet.org>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include <unistd.h>
#include <sys/resource.h>
#include "busybox.h"
static inline int int_add_no_wrap(int a, int b)
{
int s = a + b;
if (b < 0) {
if (s > a) s = INT_MIN;
} else {
if (s < a) s = INT_MAX;
}
return s;
}
int nice_main(int argc, char **argv)
{
static const char Xetpriority_msg[] = "cannot %cet priority";
int old_priority, adjustment;
errno = 0; /* Needed for getpriority error detection. */
old_priority = getpriority(PRIO_PROCESS, 0);
if (errno) {
bb_perror_msg_and_die(Xetpriority_msg, 'g');
}
if (!*++argv) { /* No args, so (GNU) output current nice value. */
bb_printf("%d\n", old_priority);
bb_fflush_stdout_and_exit(EXIT_SUCCESS);
}
adjustment = 10; /* Set default adjustment. */
if ((argv[0][0] == '-') && (argv[0][1] == 'n') && !argv[0][2]) { /* "-n" */
if (argc < 4) { /* Missing priority and/or utility! */
bb_show_usage();
}
adjustment = xatoi(argv[1]);
argv += 2;
}
{ /* Set our priority. Handle integer wrapping for old + adjust. */
int new_priority = int_add_no_wrap(old_priority, adjustment);
if (setpriority(PRIO_PROCESS, 0, new_priority) < 0) {
bb_perror_msg_and_die(Xetpriority_msg, 's');
}
}
execvp(*argv, argv); /* Now exec the desired program. */
/* The exec failed... */
xfunc_error_retval = (errno == ENOENT) ? 127 : 126; /* SUSv3 */
bb_perror_msg_and_die("%s", *argv);
}
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