LXR busybox/util-linux/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/* Notes:
  10 *   Setting an absolute priority was obsoleted in SUSv2 and removed
  11 *   in SUSv3.  However, the common linux version of renice does
  12 *   absolute and not relative.  So we'll continue supporting absolute,
  13 *   although the stdout logging has been removed since both SUSv2 and
  14 *   SUSv3 specify that stdout isn't used.
  15 *
  16 *   This version is lenient in that it doesn't require any IDs.  The
  17 *   options -p, -g, and -u are treated as mode switches for the
  18 *   following IDs (if any).  Multiple switches are allowed.
  19 */
  20//config:config RENICE
  21//config:       bool "renice (4.2 kb)"
  22//config:       default y
  23//config:       help
  24//config:       Renice alters the scheduling priority of one or more running
  25//config:       processes.
  26
  27//applet:IF_RENICE(APPLET_NOEXEC(renice, renice, BB_DIR_USR_BIN, BB_SUID_DROP, renice))
  28
  29//kbuild:lib-$(CONFIG_RENICE) += renice.o
  30
  31//usage:#define renice_trivial_usage
  32//usage:       "[-n] PRIORITY [[-p|g|u] ID...]..."
  33//usage:#define renice_full_usage "\n\n"
  34//usage:       "Change scheduling priority of a running process\n"
  35//usage:     "\n        -n      Add PRIORITY to current nice value"
  36//usage:     "\n                Without -n, nice value is set to PRIORITY"
  37//usage:     "\n        -p      Process ids (default)"
  38//usage:     "\n        -g      Process group ids"
  39//usage:     "\n        -u      Process user names"
  40
  41#include "libbb.h"
  42
  43int renice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  44int renice_main(int argc UNUSED_PARAM, char **argv)
  45{
  46        static const char Xetpriority_msg[] ALIGN1 = "%cetpriority";
  47
  48        int retval = EXIT_SUCCESS;
  49        int which = PRIO_PROCESS;  /* Default 'which' value. */
  50        int use_relative = 0;
  51        int adjustment, new_priority;
  52        unsigned who;
  53        char *arg;
  54
  55        /* Yes, they are not #defines in glibc 2.4! #if won't work */
  56        BUILD_BUG_ON(PRIO_PROCESS < CHAR_MIN || PRIO_PROCESS > CHAR_MAX);
  57        BUILD_BUG_ON(PRIO_PGRP < CHAR_MIN || PRIO_PGRP > CHAR_MAX);
  58        BUILD_BUG_ON(PRIO_USER < CHAR_MIN || PRIO_USER > CHAR_MAX);
  59
  60        arg = *++argv;
  61
  62        /* Check if we are using a relative adjustment. */
  63        if (arg && arg[0] == '-' && arg[1] == 'n') {
  64                use_relative = 1;
  65                if (!arg[2])
  66                        arg = *++argv;
  67                else
  68                        arg += 2;
  69        }
  70
  71        if (!arg) {  /* No args?  Then show usage. */
  72                bb_show_usage();
  73        }
  74
  75        /* Get the priority adjustment (absolute or relative). */
  76        adjustment = xatoi_range(arg, INT_MIN/2, INT_MAX/2);
  77
  78        while ((arg = *++argv) != NULL) {
  79                /* Check for a mode switch. */
  80                if (arg[0] == '-' && arg[1]) {
  81                        static const char opts[] ALIGN1 = {
  82                                'p', 'g', 'u', 0, PRIO_PROCESS, PRIO_PGRP, PRIO_USER
  83                        };
  84                        const char *p = strchr(opts, arg[1]);
  85                        if (p) {
  86                                which = p[4];
  87                                if (!arg[2])
  88                                        continue;
  89                                arg += 2;
  90                        }
  91                }
  92
  93                /* Process an ID arg. */
  94                if (which == PRIO_USER) {
  95                        struct passwd *p;
  96                        /* NB: use of getpwnam makes it risky to be NOFORK, switch to getpwnam_r? */
  97                        p = getpwnam(arg);
  98                        if (!p) {
  99                                bb_error_msg("unknown user %s", arg);
 100                                goto HAD_ERROR;
 101                        }
 102                        who = p->pw_uid;
 103                } else {
 104                        who = bb_strtou(arg, NULL, 10);
 105                        if (errno) {
 106                                bb_error_msg("invalid number '%s'", arg);
 107                                goto HAD_ERROR;
 108                        }
 109                }
 110
 111                /* Get priority to use, and set it. */
 112                if (use_relative) {
 113                        int old_priority;
 114
 115                        errno = 0;  /* Needed for getpriority error detection. */
 116                        old_priority = getpriority(which, who);
 117                        if (errno) {
 118                                bb_perror_msg(Xetpriority_msg, 'g');
 119                                goto HAD_ERROR;
 120                        }
 121
 122                        new_priority = old_priority + adjustment;
 123                } else {
 124                        new_priority = adjustment;
 125                }
 126
 127                if (setpriority(which, who, new_priority) == 0) {
 128                        continue;
 129                }
 130
 131                bb_perror_msg(Xetpriority_msg, 's');
 132 HAD_ERROR:
 133                retval = EXIT_FAILURE;
 134        }
 135
 136        /* No need to check for errors outputting to stderr since, if it
 137         * was used, the HAD_ERROR label was reached and retval was set. */
 138
 139        return retval;
 140}
 141