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