LXR busybox/procps/renice.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * renice implementation for busybox
   4 *
   5 * Copyright (C) 2005  Manuel Novoa III  <mjn3@codepoet.org>
   6 *
   7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8 */
   9
  10/* Notes:
  11 *   Setting an absolute priority was obsoleted in SUSv2 and removed
  12 *   in SUSv3.  However, the common linux version of renice does
  13 *   absolute and not relative.  So we'll continue supporting absolute,
  14 *   although the stdout logging has been removed since both SUSv2 and
  15 *   SUSv3 specify that stdout isn't used.
  16 *
  17 *   This version is lenient in that it doesn't require any IDs.  The
  18 *   options -p, -g, and -u are treated as mode switches for the
  19 *   following IDs (if any).  Multiple switches are allowed.
  20 */
  21//config:config RENICE
  22//config:       bool "renice"
  23//config:       default y
  24//config:       help
  25//config:         Renice alters the scheduling priority of one or more running
  26//config:         processes.
  27
  28//applet:IF_RENICE(APPLET(renice, BB_DIR_USR_BIN, BB_SUID_DROP))
  29
  30//kbuild:lib-$(CONFIG_RENICE) += renice.o
  31
  32//usage:#define renice_trivial_usage
  33//usage:       "[-n] PRIORITY [[-p | -g | -u] ID...]..."
  34//usage:#define renice_full_usage "\n\n"
  35//usage:       "Change scheduling priority of a running process\n"
  36//usage:     "\n        -n      Add PRIORITY to current nice value"
  37//usage:     "\n                Without -n, nice value is set to PRIORITY"
  38//usage:     "\n        -p      Process ids (default)"
  39//usage:     "\n        -g      Process group ids"
  40//usage:     "\n        -u      Process user names"
  41
  42#include "libbb.h"
  43#include <sys/resource.h>
  44
  45void BUG_bad_PRIO_PROCESS(void);
  46void BUG_bad_PRIO_PGRP(void);
  47void BUG_bad_PRIO_USER(void);
  48
  49int renice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  50int renice_main(int argc UNUSED_PARAM, char **argv)
  51{
  52        static const char Xetpriority_msg[] ALIGN1 = "%cetpriority";
  53
  54        int retval = EXIT_SUCCESS;
  55        int which = PRIO_PROCESS;  /* Default 'which' value. */
  56        int use_relative = 0;
  57        int adjustment, new_priority;
  58        unsigned who;
  59        char *arg;
  60
  61        /* Yes, they are not #defines in glibc 2.4! #if won't work */
  62        if (PRIO_PROCESS < CHAR_MIN || PRIO_PROCESS > CHAR_MAX)
  63                BUG_bad_PRIO_PROCESS();
  64        if (PRIO_PGRP < CHAR_MIN || PRIO_PGRP > CHAR_MAX)
  65                BUG_bad_PRIO_PGRP();
  66        if (PRIO_USER < CHAR_MIN || PRIO_USER > CHAR_MAX)
  67                BUG_bad_PRIO_USER();
  68
  69        arg = *++argv;
  70
  71        /* Check if we are using a relative adjustment. */
  72        if (arg && arg[0] == '-' && arg[1] == 'n') {
  73                use_relative = 1;
  74                if (!arg[2])
  75                        arg = *++argv;
  76                else
  77                        arg += 2;
  78        }
  79
  80        if (!arg) {  /* No args?  Then show usage. */
  81                bb_show_usage();
  82        }
  83
  84        /* Get the priority adjustment (absolute or relative). */
  85        adjustment = xatoi_range(arg, INT_MIN/2, INT_MAX/2);
  86
  87        while ((arg = *++argv) != NULL) {
  88                /* Check for a mode switch. */
  89                if (arg[0] == '-' && arg[1]) {
  90                        static const char opts[] ALIGN1 = {
  91                                'p', 'g', 'u', 0, PRIO_PROCESS, PRIO_PGRP, PRIO_USER
  92                        };
  93                        const char *p = strchr(opts, arg[1]);
  94                        if (p) {
  95                                which = p[4];
  96                                if (!arg[2])
  97                                        continue;
  98                                arg += 2;
  99                        }
 100                }
 101
 102                /* Process an ID arg. */
 103                if (which == PRIO_USER) {
 104                        struct passwd *p;
 105                        p = getpwnam(arg);
 106                        if (!p) {
 107                                bb_error_msg("unknown user %s", arg);
 108                                goto HAD_ERROR;
 109                        }
 110                        who = p->pw_uid;
 111                } else {
 112                        who = bb_strtou(arg, NULL, 10);
 113                        if (errno) {
 114                                bb_error_msg("invalid number '%s'", arg);
 115                                goto HAD_ERROR;
 116                        }
 117                }
 118
 119                /* Get priority to use, and set it. */
 120                if (use_relative) {
 121                        int old_priority;
 122
 123                        errno = 0;  /* Needed for getpriority error detection. */
 124                        old_priority = getpriority(which, who);
 125                        if (errno) {
 126                                bb_perror_msg(Xetpriority_msg, 'g');
 127                                goto HAD_ERROR;
 128                        }
 129
 130                        new_priority = old_priority + adjustment;
 131                } else {
 132                        new_priority = adjustment;
 133                }
 134
 135                if (setpriority(which, who, new_priority) == 0) {
 136                        continue;
 137                }
 138
 139                bb_perror_msg(Xetpriority_msg, 's');
 140 HAD_ERROR:
 141                retval = EXIT_FAILURE;
 142        }
 143
 144        /* No need to check for errors outputing to stderr since, if it
 145         * was used, the HAD_ERROR label was reached and retval was set. */
 146
 147        return retval;
 148}
 149