src/nice.c

   1 /* nice -- run a program with modified niceness
   2    Copyright (C) 1990-2005, 2007-2011 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* David MacKenzie <djm@gnu.ai.mit.edu> */
  18
  19 #include <config.h>
  20 #include <stdio.h>
  21 #include <getopt.h>
  22 #include <sys/types.h>
  23
  24 #include "system.h"
  25
  26 #if ! HAVE_NICE
  27 /* Include this after "system.h" so we're sure to have definitions
  28    (from time.h or sys/time.h) required for e.g. the ru_utime member.  */
  29 # include <sys/resource.h>
  30 #endif
  31
  32 #include "error.h"
  33 #include "quote.h"
  34 #include "xstrtol.h"
  35
  36 /* The official name of this program (e.g., no `g' prefix).  */
  37 #define PROGRAM_NAME "nice"
  38
  39 #define AUTHORS proper_name ("David MacKenzie")
  40
  41 #if HAVE_NICE
  42 # define GET_NICENESS() nice (0)
  43 #else
  44 # define GET_NICENESS() getpriority (PRIO_PROCESS, 0)
  45 #endif
  46
  47 #ifndef NZERO
  48 # define NZERO 20
  49 #endif
  50
  51 /* This is required for Darwin Kernel Version 7.7.0.  */
  52 #if NZERO == 0
  53 # undef  NZERO
  54 # define NZERO 20
  55 #endif
  56
  57 static struct option const longopts[] =
  58 {
  59   {"adjustment", required_argument, NULL, 'n'},
  60   {GETOPT_HELP_OPTION_DECL},
  61   {GETOPT_VERSION_OPTION_DECL},
  62   {NULL, 0, NULL, 0}
  63 };
  64
  65 void
  66 usage (int status)
  67 {
  68   if (status != EXIT_SUCCESS)
  69     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  70              program_name);
  71   else
  72     {
  73       printf (_("Usage: %s [OPTION] [COMMAND [ARG]...]\n"), program_name);
  74       printf (_("\
  75 Run COMMAND with an adjusted niceness, which affects process scheduling.\n\
  76 With no COMMAND, print the current niceness.  Nicenesses range from\n\
  77 %d (most favorable scheduling) to %d (least favorable).\n\
  78 \n\
  79   -n, --adjustment=N   add integer N to the niceness (default 10)\n\
  80 "),
  81               - NZERO, NZERO - 1);
  82       fputs (HELP_OPTION_DESCRIPTION, stdout);
  83       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  84       printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME);
  85       emit_ancillary_info ();
  86     }
  87   exit (status);
  88 }
  89
  90 static bool
  91 perm_related_errno (int err)
  92 {
  93   return err == EACCES || err == EPERM;
  94 }
  95
  96 int
  97 main (int argc, char **argv)
  98 {
  99   int current_niceness;
 100   int adjustment = 10;
 101   char const *adjustment_given = NULL;
 102   bool ok;
 103   int i;
 104
 105   initialize_main (&argc, &argv);
 106   set_program_name (argv[0]);
 107   setlocale (LC_ALL, "");
 108   bindtextdomain (PACKAGE, LOCALEDIR);
 109   textdomain (PACKAGE);
 110
 111   initialize_exit_failure (EXIT_CANCELED);
 112   atexit (close_stdout);
 113
 114   for (i = 1; i < argc; /* empty */)
 115     {
 116       char const *s = argv[i];
 117
 118       if (s[0] == '-' && ISDIGIT (s[1 + (s[1] == '-' || s[1] == '+')]))
 119         {
 120           adjustment_given = s + 1;
 121           ++i;
 122         }
 123       else
 124         {
 125           int c;
 126           int fake_argc = argc - (i - 1);
 127           char **fake_argv = argv + (i - 1);
 128
 129           /* Ensure that any getopt diagnostics use the right name.  */
 130           fake_argv[0] = argv[0];
 131
 132           /* Initialize getopt_long's internal state.  */
 133           optind = 0;
 134
 135           c = getopt_long (fake_argc, fake_argv, "+n:", longopts, NULL);
 136           i += optind - 1;
 137
 138           switch (c)
 139             {
 140             case 'n':
 141               adjustment_given = optarg;
 142               break;
 143
 144             case -1:
 145               break;
 146
 147             case_GETOPT_HELP_CHAR;
 148
 149             case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 150
 151             default:
 152               usage (EXIT_CANCELED);
 153               break;
 154             }
 155
 156           if (c == -1)
 157             break;
 158         }
 159     }
 160
 161   if (adjustment_given)
 162     {
 163       /* If the requested adjustment is outside the valid range,
 164          silently bring it to just within range; this mimics what
 165          "setpriority" and "nice" do.  */
 166       enum { MIN_ADJUSTMENT = 1 - 2 * NZERO, MAX_ADJUSTMENT = 2 * NZERO - 1 };
 167       long int tmp;
 168       if (LONGINT_OVERFLOW < xstrtol (adjustment_given, NULL, 10, &tmp, ""))
 169         error (EXIT_CANCELED, 0, _("invalid adjustment %s"),
 170                quote (adjustment_given));
 171       adjustment = MAX (MIN_ADJUSTMENT, MIN (tmp, MAX_ADJUSTMENT));
 172     }
 173
 174   if (i == argc)
 175     {
 176       if (adjustment_given)
 177         {
 178           error (0, 0, _("a command must be given with an adjustment"));
 179           usage (EXIT_CANCELED);
 180         }
 181       /* No command given; print the niceness.  */
 182       errno = 0;
 183       current_niceness = GET_NICENESS ();
 184       if (current_niceness == -1 && errno != 0)
 185         error (EXIT_CANCELED, errno, _("cannot get niceness"));
 186       printf ("%d\n", current_niceness);
 187       exit (EXIT_SUCCESS);
 188     }
 189
 190   errno = 0;
 191 #if HAVE_NICE
 192   ok = (nice (adjustment) != -1 || errno == 0);
 193 #else
 194   current_niceness = GET_NICENESS ();
 195   if (current_niceness == -1 && errno != 0)
 196     error (EXIT_CANCELED, errno, _("cannot get niceness"));
 197   ok = (setpriority (PRIO_PROCESS, 0, current_niceness + adjustment) == 0);
 198 #endif
 199   if (!ok)
 200     {
 201       error (perm_related_errno (errno) ? 0
 202              : EXIT_CANCELED, errno, _("cannot set niceness"));
 203       /* error() flushes stderr, but does not check for write failure.
 204          Normally, we would catch this via our atexit() hook of
 205          close_stdout, but execvp() gets in the way.  If stderr
 206          encountered a write failure, there is no need to try calling
 207          error() again.  */
 208       if (ferror (stderr))
 209         exit (EXIT_CANCELED);
 210     }
 211
 212   execvp (argv[i], &argv[i]);
 213
 214   {
 215     int exit_status = (errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
 216     error (0, errno, "%s", argv[i]);
 217     exit (exit_status);
 218   }
 219 }