busybox/coreutils/nice.c

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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 source tree.
*/
//config:config NICE
//config: bool "nice (1.8 kb)"
//config: default y
//config: help
//config: nice runs a program with modified scheduling priority.
//applet:IF_NICE(APPLET_NOEXEC(nice, nice, BB_DIR_BIN, BB_SUID_DROP, nice))
//kbuild:lib-$(CONFIG_NICE) += nice.o
//usage:#define nice_trivial_usage
//usage: "[-n ADJUST] [PROG ARGS]"
//usage:#define nice_full_usage "\n\n"
//usage: "Change scheduling priority, run PROG\n"
//usage: "\n -n ADJUST Adjust priority by ADJUST"
#include "libbb.h"
int nice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int nice_main(int argc UNUSED_PARAM, char **argv)
{
int old_priority, adjustment;
old_priority = getpriority(PRIO_PROCESS, 0);
if (!*++argv) { /* No args, so (GNU) output current nice value. */
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printf("%d\n", old_priority);
fflush_stdout_and_exit(EXIT_SUCCESS);
}
adjustment = 10; /* Set default adjustment. */
if (argv[0][0] == '-') {
char *nnn = argv[0] + 1;
if (nnn[0] == 'n') { /* -n */
nnn += 1;
if (!nnn[0]) { /* "-n NNN" */
nnn = *++argv;
}
/* else: "-nNNN" (w/o space) */
}
/* else: "-NNN" (NNN may be negative) - same as "-n NNN" */
if (!nnn || !argv[1]) { /* Missing priority or PROG! */
bb_show_usage();
}
adjustment = xatoi_range(nnn, INT_MIN/2, INT_MAX/2);
argv++;
}
{ /* Set our priority. */
int prio = old_priority + adjustment;
if (setpriority(PRIO_PROCESS, 0, prio) < 0) {
bb_perror_msg_and_die("setpriority(%d)", prio);
}
}
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BB_EXECVP_or_die(argv);
}