LXR busybox/miscutils/ionice.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * ionice implementation for busybox based on linux-utils-ng 2.14
   4 *
   5 * Copyright (C) 2008 by  <u173034@informatik.uni-oldenburg.de>
   6 *
   7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8 */
   9
  10//usage:#define ionice_trivial_usage
  11//usage:        "[-c 1-3] [-n 0-7] [-p PID] [PROG]"
  12//usage:#define ionice_full_usage "\n\n"
  13//usage:       "Change I/O priority and class\n"
  14//usage:     "\n        -c      Class. 1:realtime 2:best-effort 3:idle"
  15//usage:     "\n        -n      Priority"
  16
  17#include <sys/syscall.h>
  18#include <asm/unistd.h>
  19#include "libbb.h"
  20
  21static int ioprio_set(int which, int who, int ioprio)
  22{
  23        return syscall(SYS_ioprio_set, which, who, ioprio);
  24}
  25
  26static int ioprio_get(int which, int who)
  27{
  28        return syscall(SYS_ioprio_get, which, who);
  29}
  30
  31enum {
  32        IOPRIO_WHO_PROCESS = 1,
  33        IOPRIO_WHO_PGRP,
  34        IOPRIO_WHO_USER
  35};
  36
  37enum {
  38        IOPRIO_CLASS_NONE,
  39        IOPRIO_CLASS_RT,
  40        IOPRIO_CLASS_BE,
  41        IOPRIO_CLASS_IDLE
  42};
  43
  44static const char to_prio[] = "none\0realtime\0best-effort\0idle";
  45
  46#define IOPRIO_CLASS_SHIFT      13
  47
  48int ionice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  49int ionice_main(int argc UNUSED_PARAM, char **argv)
  50{
  51        /* Defaults */
  52        int ioclass = 0;
  53        int pri = 0;
  54        int pid = 0; /* affect own porcess */
  55        int opt;
  56        enum {
  57                OPT_n = 1,
  58                OPT_c = 2,
  59                OPT_p = 4,
  60        };
  61
  62        /* Numeric params */
  63        opt_complementary = "n+:c+:p+";
  64        /* '+': stop at first non-option */
  65        opt = getopt32(argv, "+n:c:p:", &pri, &ioclass, &pid);
  66        argv += optind;
  67
  68        if (opt & OPT_c) {
  69                if (ioclass > 3)
  70                        bb_error_msg_and_die("bad class %d", ioclass);
  71// Do we need this (compat?)?
  72//              if (ioclass == IOPRIO_CLASS_NONE)
  73//                      ioclass = IOPRIO_CLASS_BE;
  74//              if (ioclass == IOPRIO_CLASS_IDLE) {
  75//                      //if (opt & OPT_n)
  76//                      //      bb_error_msg("ignoring priority for idle class");
  77//                      pri = 7;
  78//              }
  79        }
  80
  81        if (!(opt & (OPT_n|OPT_c))) {
  82                if (!(opt & OPT_p) && *argv)
  83                        pid = xatoi_positive(*argv);
  84
  85                pri = ioprio_get(IOPRIO_WHO_PROCESS, pid);
  86                if (pri == -1)
  87                        bb_perror_msg_and_die("ioprio_%cet", 'g');
  88
  89                ioclass = (pri >> IOPRIO_CLASS_SHIFT) & 0x3;
  90                pri &= 0xff;
  91                printf((ioclass == IOPRIO_CLASS_IDLE) ? "%s\n" : "%s: prio %d\n",
  92                                nth_string(to_prio, ioclass), pri);
  93        } else {
  94//printf("pri=%d class=%d val=%x\n",
  95//pri, ioclass, pri | (ioclass << IOPRIO_CLASS_SHIFT));
  96                pri |= (ioclass << IOPRIO_CLASS_SHIFT);
  97                if (ioprio_set(IOPRIO_WHO_PROCESS, pid, pri) == -1)
  98                        bb_perror_msg_and_die("ioprio_%cet", 's');
  99                if (argv[0]) {
 100                        BB_EXECVP_or_die(argv);
 101                }
 102        }
 103
 104        return EXIT_SUCCESS;
 105}
 106