release/src/router/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
  22 //usage:#define renice_trivial_usage
  23 //usage:       "{{-n INCREMENT} | PRIORITY} [[-p | -g | -u] ID...]"
  24 //usage:#define renice_full_usage "\n\n"
  25 //usage:       "Change scheduling priority for a running process\n"
  26 //usage:     "\n        -n      Adjust current nice value (smaller is faster)"
  27 //usage:     "\n        -p      Process id(s) (default)"
  28 //usage:     "\n        -g      Process group id(s)"
  29 //usage:     "\n        -u      Process user name(s) and/or id(s)"
  30
  31 #include "libbb.h"
  32 #include <sys/resource.h>
  33
  34 void BUG_bad_PRIO_PROCESS(void);
  35 void BUG_bad_PRIO_PGRP(void);
  36 void BUG_bad_PRIO_USER(void);
  37
  38 int renice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  39 int renice_main(int argc UNUSED_PARAM, char **argv)
  40 {
  41         static const char Xetpriority_msg[] ALIGN1 = "%cetpriority";
  42
  43         int retval = EXIT_SUCCESS;
  44         int which = PRIO_PROCESS;  /* Default 'which' value. */
  45         int use_relative = 0;
  46         int adjustment, new_priority;
  47         unsigned who;
  48         char *arg;
  49
  50         /* Yes, they are not #defines in glibc 2.4! #if won't work */
  51         if (PRIO_PROCESS < CHAR_MIN || PRIO_PROCESS > CHAR_MAX)
  52                 BUG_bad_PRIO_PROCESS();
  53         if (PRIO_PGRP < CHAR_MIN || PRIO_PGRP > CHAR_MAX)
  54                 BUG_bad_PRIO_PGRP();
  55         if (PRIO_USER < CHAR_MIN || PRIO_USER > CHAR_MAX)
  56                 BUG_bad_PRIO_USER();
  57
  58         arg = *++argv;
  59
  60         /* Check if we are using a relative adjustment. */
  61         if (arg && arg[0] == '-' && arg[1] == 'n') {
  62                 use_relative = 1;
  63                 if (!arg[2])
  64                         arg = *++argv;
  65                 else
  66                         arg += 2;
  67         }
  68
  69         if (!arg) {  /* No args?  Then show usage. */
  70                 bb_show_usage();
  71         }
  72
  73         /* Get the priority adjustment (absolute or relative). */
  74         adjustment = xatoi_range(arg, INT_MIN/2, INT_MAX/2);
  75
  76         while ((arg = *++argv) != NULL) {
  77                 /* Check for a mode switch. */
  78                 if (arg[0] == '-' && arg[1]) {
  79                         static const char opts[] ALIGN1 = {
  80                                 'p', 'g', 'u', 0, PRIO_PROCESS, PRIO_PGRP, PRIO_USER
  81                         };
  82                         const char *p = strchr(opts, arg[1]);
  83                         if (p) {
  84                                 which = p[4];
  85                                 if (!arg[2])
  86                                         continue;
  87                                 arg += 2;
  88                         }
  89                 }
  90
  91                 /* Process an ID arg. */
  92                 if (which == PRIO_USER) {
  93                         struct passwd *p;
  94                         p = getpwnam(arg);
  95                         if (!p) {
  96                                 bb_error_msg("unknown user %s", arg);
  97                                 goto HAD_ERROR;
  98                         }
  99                         who = p->pw_uid;
 100                 } else {
 101                         who = bb_strtou(arg, NULL, 10);
 102                         if (errno) {
 103                                 bb_error_msg("invalid number '%s'", arg);
 104                                 goto HAD_ERROR;
 105                         }
 106                 }
 107
 108                 /* Get priority to use, and set it. */
 109                 if (use_relative) {
 110                         int old_priority;
 111
 112                         errno = 0;  /* Needed for getpriority error detection. */
 113                         old_priority = getpriority(which, who);
 114                         if (errno) {
 115                                 bb_perror_msg(Xetpriority_msg, 'g');
 116                                 goto HAD_ERROR;
 117                         }
 118
 119                         new_priority = old_priority + adjustment;
 120                 } else {
 121                         new_priority = adjustment;
 122                 }
 123
 124                 if (setpriority(which, who, new_priority) == 0) {
 125                         continue;
 126                 }
 127
 128                 bb_perror_msg(Xetpriority_msg, 's');
 129  HAD_ERROR:
 130                 retval = EXIT_FAILURE;
 131         }
 132
 133         /* No need to check for errors outputing to stderr since, if it
 134          * was used, the HAD_ERROR label was reached and retval was set. */
 135
 136         return retval;
 137 }