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
  25 void BUG_bad_PRIO_PROCESS(void);
  26 void BUG_bad_PRIO_PGRP(void);
  27 void BUG_bad_PRIO_USER(void);
  28
  29 int renice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  30 int renice_main(int argc, 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 }