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 tarball for details.
*/
#include <sys/resource.h>
#include "libbb.h"
int nice_main(int argc, char **argv);
int nice_main(int argc, 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] == '-') {
if (argv[0][1] == 'n') { /* -n */
if (argv[0][2]) { /* -nNNNN (w/o space) */
argv[0] += 2; argv--; argc++;
}
} else { /* -NNN (NNN may be negative) == -n NNN */
argv[0] += 1; argv--; argc++;
}
if (argc < 4) { /* Missing priority and/or utility! */
bb_show_usage();
}
adjustment = xatoi_range(argv[1], INT_MIN/2, INT_MAX/2);
argv += 2;
}
{ /* 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(*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);
}