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] PRIORITY [[-p | -g | -u] ID...]..."
  24 //usage:#define renice_full_usage "\n\n"
  25 //usage:       "Change scheduling priority of a running process\n"
  26 //usage:     "\n        -n      Add PRIORITY to current nice value"
  27 //usage:     "\n                Without -n, nice value is set to PRIORITY"
  28 //usage:     "\n        -p      Process ids (default)"
  29 //usage:     "\n        -g      Process group ids"
  30 //usage:     "\n        -u      Process user names"
  31
  32 #include "libbb.h"
  33 #include <sys/resource.h>
  34
  35 void BUG_bad_PRIO_PROCESS(void);
  36 void BUG_bad_PRIO_PGRP(void);
  37 void BUG_bad_PRIO_USER(void);
  38
  39 int renice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  40 int renice_main(int argc UNUSED_PARAM, char **argv)
  41 {
  42         static const char Xetpriority_msg[] ALIGN1 = "%cetpriority";
  43
  44         int retval = EXIT_SUCCESS;
  45         int which = PRIO_PROCESS;  /* Default 'which' value. */
  46         int use_relative = 0;
  47         int adjustment, new_priority;
  48         unsigned who;
  49         char *arg;
  50
  51         /* Yes, they are not #defines in glibc 2.4! #if won't work */
  52         if (PRIO_PROCESS < CHAR_MIN || PRIO_PROCESS > CHAR_MAX)
  53                 BUG_bad_PRIO_PROCESS();
  54         if (PRIO_PGRP < CHAR_MIN || PRIO_PGRP > CHAR_MAX)
  55                 BUG_bad_PRIO_PGRP();
  56         if (PRIO_USER < CHAR_MIN || PRIO_USER > CHAR_MAX)
  57                 BUG_bad_PRIO_USER();
  58
  59         arg = *++argv;
  60
  61         /* Check if we are using a relative adjustment. */
  62         if (arg && arg[0] == '-' && arg[1] == 'n') {
  63                 use_relative = 1;
  64                 if (!arg[2])
  65                         arg = *++argv;
  66                 else
  67                         arg += 2;
  68         }
  69
  70         if (!arg) {  /* No args?  Then show usage. */
  71                 bb_show_usage();
  72         }
  73
  74         /* Get the priority adjustment (absolute or relative). */
  75         adjustment = xatoi_range(arg, INT_MIN/2, INT_MAX/2);
  76
  77         while ((arg = *++argv) != NULL) {
  78                 /* Check for a mode switch. */
  79                 if (arg[0] == '-' && arg[1]) {
  80                         static const char opts[] ALIGN1 = {
  81                                 'p', 'g', 'u', 0, PRIO_PROCESS, PRIO_PGRP, PRIO_USER
  82                         };
  83                         const char *p = strchr(opts, arg[1]);
  84                         if (p) {
  85                                 which = p[4];
  86                                 if (!arg[2])
  87                                         continue;
  88                                 arg += 2;
  89                         }
  90                 }
  91
  92                 /* Process an ID arg. */
  93                 if (which == PRIO_USER) {
  94                         struct passwd *p;
  95                         p = getpwnam(arg);
  96                         if (!p) {
  97                                 bb_error_msg("unknown user %s", arg);
  98                                 goto HAD_ERROR;
  99                         }
 100                         who = p->pw_uid;
 101                 } else {
 102                         who = bb_strtou(arg, NULL, 10);
 103                         if (errno) {
 104                                 bb_error_msg("invalid number '%s'", arg);
 105                                 goto HAD_ERROR;
 106                         }
 107                 }
 108
 109                 /* Get priority to use, and set it. */
 110                 if (use_relative) {
 111                         int old_priority;
 112
 113                         errno = 0;  /* Needed for getpriority error detection. */
 114                         old_priority = getpriority(which, who);
 115                         if (errno) {
 116                                 bb_perror_msg(Xetpriority_msg, 'g');
 117                                 goto HAD_ERROR;
 118                         }
 119
 120                         new_priority = old_priority + adjustment;
 121                 } else {
 122                         new_priority = adjustment;
 123                 }
 124
 125                 if (setpriority(which, who, new_priority) == 0) {
 126                         continue;
 127                 }
 128
 129                 bb_perror_msg(Xetpriority_msg, 's');
 130  HAD_ERROR:
 131                 retval = EXIT_FAILURE;
 132         }
 133
 134         /* No need to check for errors outputing to stderr since, if it
 135          * was used, the HAD_ERROR label was reached and retval was set. */
 136
 137         return retval;
 138 }