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 the GPL v2 or later, see the file LICENSE in this tarball.
   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
  22#include "libbb.h"
  23#include <sys/resource.h>
  24
  25void BUG_bad_PRIO_PROCESS(void);
  26void BUG_bad_PRIO_PGRP(void);
  27void BUG_bad_PRIO_USER(void);
  28
  29int renice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  30int renice_main(int argc UNUSED_PARAM, char **argv)
  31{
  32        static const char Xetpriority_msg[] ALIGN1 = "%cetpriority";
  33
  34        int retval = EXIT_SUCCESS;
  35        int which = PRIO_PROCESS;       /* Default 'which' value. */
  36        int use_relative = 0;
  37        int adjustment, new_priority;
  38        unsigned who;
  39        char *arg;
  40
  41        /* Yes, they are not #defines in glibc 2.4! #if won't work */
  42        if (PRIO_PROCESS < CHAR_MIN || PRIO_PROCESS > CHAR_MAX)
  43                BUG_bad_PRIO_PROCESS();
  44        if (PRIO_PGRP < CHAR_MIN || PRIO_PGRP > CHAR_MAX)
  45                BUG_bad_PRIO_PGRP();
  46        if (PRIO_USER < CHAR_MIN || PRIO_USER > CHAR_MAX)
  47                BUG_bad_PRIO_USER();
  48
  49        arg = *++argv;
  50
  51        /* Check if we are using a relative adjustment. */
  52        if (arg && arg[0] == '-' && arg[1] == 'n') {
  53                use_relative = 1;
  54                if (!arg[2])
  55                        arg = *++argv;
  56                else
  57                        arg += 2;
  58        }
  59
  60        if (!arg) {                             /* No args?  Then show usage. */
  61                bb_show_usage();
  62        }
  63
  64        /* Get the priority adjustment (absolute or relative). */
  65        adjustment = xatoi_range(arg, INT_MIN/2, INT_MAX/2);
  66
  67        while ((arg = *++argv) != NULL) {
  68                /* Check for a mode switch. */
  69                if (arg[0] == '-' && arg[1]) {
  70                        static const char opts[] ALIGN1 = {
  71                                'p', 'g', 'u', 0, PRIO_PROCESS, PRIO_PGRP, PRIO_USER
  72                        };
  73                        const char *p = strchr(opts, arg[1]);
  74                        if (p) {
  75                                which = p[4];
  76                                if (!arg[2])
  77                                        continue;
  78                                arg += 2;
  79                        }
  80                }
  81
  82                /* Process an ID arg. */
  83                if (which == PRIO_USER) {
  84                        struct passwd *p;
  85                        p = getpwnam(arg);
  86                        if (!p) {
  87                                bb_error_msg("unknown user %s", arg);
  88                                goto HAD_ERROR;
  89                        }
  90                        who = p->pw_uid;
  91                } else {
  92                        who = bb_strtou(arg, NULL, 10);
  93                        if (errno) {
  94                                bb_error_msg("bad value: %s", arg);
  95                                goto HAD_ERROR;
  96                        }
  97                }
  98
  99                /* Get priority to use, and set it. */
 100                if (use_relative) {
 101                        int old_priority;
 102
 103                        errno = 0;       /* Needed for getpriority error detection. */
 104                        old_priority = getpriority(which, who);
 105                        if (errno) {
 106                                bb_perror_msg(Xetpriority_msg, 'g');
 107                                goto HAD_ERROR;
 108                        }
 109
 110                        new_priority = old_priority + adjustment;
 111                } else {
 112                        new_priority = adjustment;
 113                }
 114
 115                if (setpriority(which, who, new_priority) == 0) {
 116                        continue;
 117                }
 118
 119                bb_perror_msg(Xetpriority_msg, 's');
 120 HAD_ERROR:
 121                retval = EXIT_FAILURE;
 122        }
 123
 124        /* No need to check for errors outputing to stderr since, if it
 125         * was used, the HAD_ERROR label was reached and retval was set. */
 126
 127        return retval;
 128}
 129