source: MondoRescue/branches/2.2.9/mindi-busybox/miscutils/chrt.c@ 2725

/* vi: set sw=4 ts=4: */
/*
 * chrt - manipulate real-time attributes of a process
 * Copyright (c) 2006-2007 Bernhard Reutner-Fischer
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
#include <sched.h>
#include "libbb.h"
#ifndef _POSIX_PRIORITY_SCHEDULING
#warning your system may be foobared
#endif

static const struct {
    int policy;
    char name[sizeof("SCHED_OTHER")];
} policies[] = {
    {SCHED_OTHER, "SCHED_OTHER"},
    {SCHED_FIFO, "SCHED_FIFO"},
    {SCHED_RR, "SCHED_RR"}
};

//TODO: add
// -b, SCHED_BATCH
// -i, SCHED_IDLE

static void show_min_max(int pol)
{
    const char *fmt = "%s min/max priority\t: %u/%u\n";
    int max, min;

    max = sched_get_priority_max(pol);
    min = sched_get_priority_min(pol);
    if ((max|min) < 0)
        fmt = "%s not supported\n";
    printf(fmt, policies[pol].name, min, max);
}

#define OPT_m (1<<0)
#define OPT_p (1<<1)
#define OPT_r (1<<2)
#define OPT_f (1<<3)
#define OPT_o (1<<4)

int chrt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int chrt_main(int argc UNUSED_PARAM, char **argv)
{
    pid_t pid = 0;
    unsigned opt;
    struct sched_param sp;
    char *pid_str;
    char *priority = priority; /* for compiler */
    const char *current_new;
    int policy = SCHED_RR;

    /* at least 1 arg; only one policy accepted */
    opt_complementary = "-1:r--fo:f--ro:r--fo";
    opt = getopt32(argv, "+mprfo");
    if (opt & OPT_r)
        policy = SCHED_RR;
    if (opt & OPT_f)
        policy = SCHED_FIFO;
    if (opt & OPT_o)
        policy = SCHED_OTHER;
    if (opt & OPT_m) { /* print min/max */
        show_min_max(SCHED_FIFO);
        show_min_max(SCHED_RR);
        show_min_max(SCHED_OTHER);
        fflush_stdout_and_exit(EXIT_SUCCESS);
    }

    argv += optind;
    if (opt & OPT_p) {
        pid_str = *argv++;
        if (*argv) { /* "-p <priority> <pid> [...]" */
            priority = pid_str;
            pid_str = *argv;
        }
        /* else "-p <pid>", and *argv == NULL */
        pid = xatoul_range(pid_str, 1, ((unsigned)(pid_t)ULONG_MAX) >> 1);
    } else {
        priority = *argv++;
        if (!*argv)
            bb_show_usage();
    }

    current_new = "current\0new";
    if (opt & OPT_p) {
        int pol;
 print_rt_info:
        pol = sched_getscheduler(pid);
        if (pol < 0)
            bb_perror_msg_and_die("can't %cet pid %d's policy", 'g', pid);
        printf("pid %d's %s scheduling policy: %s\n",
                pid, current_new, policies[pol].name);
        if (sched_getparam(pid, &sp))
            bb_perror_msg_and_die("can't get pid %d's attributes", pid);
        printf("pid %d's %s scheduling priority: %d\n",
                pid, current_new, sp.sched_priority);
        if (!*argv) {
            /* Either it was just "-p <pid>",
             * or it was "-p <priority> <pid>" and we came here
             * for the second time (see goto below) */
            return EXIT_SUCCESS;
        }
        *argv = NULL;
        current_new += 8;
    }

    /* from the manpage of sched_getscheduler:
    [...] sched_priority can have a value in the range 0 to 99.
    [...] SCHED_OTHER or SCHED_BATCH must be assigned static priority 0.
    [...] SCHED_FIFO or SCHED_RR can have static priority in 1..99 range.
    */
    sp.sched_priority = xstrtou_range(priority, 0, policy != SCHED_OTHER ? 1 : 0, 99);

    if (sched_setscheduler(pid, policy, &sp) < 0)
        bb_perror_msg_and_die("can't %cet pid %d's policy", 's', pid);

    if (!argv[0]) /* "-p <priority> <pid> [...]" */
        goto print_rt_info;

    BB_EXECVP_or_die(argv);
}