source: MondoRescue/branches/3.3/mindi-busybox/miscutils/ionice.c@ 3647

/* vi: set sw=4 ts=4: */
/*
 * ionice implementation for busybox based on linux-utils-ng 2.14
 *
 * Copyright (C) 2008 by  <u173034@informatik.uni-oldenburg.de>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

//usage:#define ionice_trivial_usage
//usage:    "[-c 1-3] [-n 0-7] [-p PID] [PROG]"
//usage:#define ionice_full_usage "\n\n"
//usage:       "Change I/O priority and class\n"
//usage:     "\n    -c  Class. 1:realtime 2:best-effort 3:idle"
//usage:     "\n    -n  Priority"

#include <sys/syscall.h>
#include <asm/unistd.h>
#include "libbb.h"

static int ioprio_set(int which, int who, int ioprio)
{
    return syscall(SYS_ioprio_set, which, who, ioprio);
}

static int ioprio_get(int which, int who)
{
    return syscall(SYS_ioprio_get, which, who);
}

enum {
    IOPRIO_WHO_PROCESS = 1,
    IOPRIO_WHO_PGRP,
    IOPRIO_WHO_USER
};

enum {
    IOPRIO_CLASS_NONE,
    IOPRIO_CLASS_RT,
    IOPRIO_CLASS_BE,
    IOPRIO_CLASS_IDLE
};

static const char to_prio[] ALIGN1 = "none\0realtime\0best-effort\0idle";

#define IOPRIO_CLASS_SHIFT      13

int ionice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int ionice_main(int argc UNUSED_PARAM, char **argv)
{
    /* Defaults */
    int ioclass = 0;
    int pri = 0;
    int pid = 0; /* affect own porcess */
    int opt;
    enum {
        OPT_n = 1,
        OPT_c = 2,
        OPT_p = 4,
    };

    /* Numeric params */
    opt_complementary = "n+:c+:p+";
    /* '+': stop at first non-option */
    opt = getopt32(argv, "+n:c:p:", &pri, &ioclass, &pid);
    argv += optind;

    if (opt & OPT_c) {
        if (ioclass > 3)
            bb_error_msg_and_die("bad class %d", ioclass);
// Do we need this (compat?)?
//      if (ioclass == IOPRIO_CLASS_NONE)
//          ioclass = IOPRIO_CLASS_BE;
//      if (ioclass == IOPRIO_CLASS_IDLE) {
//          //if (opt & OPT_n)
//          //  bb_error_msg("ignoring priority for idle class");
//          pri = 7;
//      }
    }

    if (!(opt & (OPT_n|OPT_c))) {
        if (!(opt & OPT_p) && *argv)
            pid = xatoi_positive(*argv);

        pri = ioprio_get(IOPRIO_WHO_PROCESS, pid);
        if (pri == -1)
            bb_perror_msg_and_die("ioprio_%cet", 'g');

        ioclass = (pri >> IOPRIO_CLASS_SHIFT) & 0x3;
        pri &= 0xff;
        printf((ioclass == IOPRIO_CLASS_IDLE) ? "%s\n" : "%s: prio %d\n",
                nth_string(to_prio, ioclass), pri);
    } else {
//printf("pri=%d class=%d val=%x\n",
//pri, ioclass, pri | (ioclass << IOPRIO_CLASS_SHIFT));
        pri |= (ioclass << IOPRIO_CLASS_SHIFT);
        if (ioprio_set(IOPRIO_WHO_PROCESS, pid, pri) == -1)
            bb_perror_msg_and_die("ioprio_%cet", 's');
        if (argv[0]) {
            BB_EXECVP_or_die(argv);
        }
    }

    return EXIT_SUCCESS;
}