src/nice.c

   1 /* nice -- run a program with modified niceness
   2    Copyright (C) 1990-2017 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 "die.h"
  33 #include "error.h"
  34 #include "quote.h"
  35 #include "xstrtol.h"
  36
  37 /* The official name of this program (e.g., no 'g' prefix).  */
  38 #define PROGRAM_NAME "nice"
  39
  40 #define AUTHORS proper_name ("David MacKenzie")
  41
  42 #if HAVE_NICE
  43 # define GET_NICENESS() nice (0)
  44 #else
  45 # define GET_NICENESS() getpriority (PRIO_PROCESS, 0)
  46 #endif
  47
  48 #ifndef NZERO
  49 # define NZERO 20
  50 #endif
  51
  52 /* This is required for Darwin Kernel Version 7.7.0.  */
  53 #if NZERO == 0
  54 # undef  NZERO
  55 # define NZERO 20
  56 #endif
  57
  58 static struct option const longopts[] =
  59 {
  60   {"adjustment", required_argument, NULL, 'n'},
  61   {GETOPT_HELP_OPTION_DECL},
  62   {GETOPT_VERSION_OPTION_DECL},
  63   {NULL, 0, NULL, 0}
  64 };
  65
  66 void
  67 usage (int status)
  68 {
  69   if (status != EXIT_SUCCESS)
  70     emit_try_help ();
  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.  Niceness values range from\n\
  77 %d (most favorable to the process) to %d (least favorable to the process).\n\
  78 "),
  79               - NZERO, NZERO - 1);
  80
  81       emit_mandatory_arg_note ();
  82
  83       fputs (_("\
  84   -n, --adjustment=N   add integer N to the niceness (default 10)\n\
  85 "), stdout);
  86       fputs (HELP_OPTION_DESCRIPTION, stdout);
  87       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  88       printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME);
  89       emit_ancillary_info (PROGRAM_NAME);
  90     }
  91   exit (status);
  92 }
  93
  94 static bool
  95 perm_related_errno (int err)
  96 {
  97   return err == EACCES || err == EPERM;
  98 }
  99
 100 int
 101 main (int argc, char **argv)
 102 {
 103   int current_niceness;
 104   int adjustment = 10;
 105   char const *adjustment_given = NULL;
 106   bool ok;
 107   int i;
 108
 109   initialize_main (&argc, &argv);
 110   set_program_name (argv[0]);
 111   setlocale (LC_ALL, "");
 112   bindtextdomain (PACKAGE, LOCALEDIR);
 113   textdomain (PACKAGE);
 114
 115   initialize_exit_failure (EXIT_CANCELED);
 116   atexit (close_stdout);
 117
 118   for (i = 1; i < argc; /* empty */)
 119     {
 120       char const *s = argv[i];
 121
 122       if (s[0] == '-' && ISDIGIT (s[1 + (s[1] == '-' || s[1] == '+')]))
 123         {
 124           adjustment_given = s + 1;
 125           ++i;
 126         }
 127       else
 128         {
 129           int c;
 130           int fake_argc = argc - (i - 1);
 131           char **fake_argv = argv + (i - 1);
 132
 133           /* Ensure that any getopt diagnostics use the right name.  */
 134           fake_argv[0] = argv[0];
 135
 136           /* Initialize getopt_long's internal state.  */
 137           optind = 0;
 138
 139           c = getopt_long (fake_argc, fake_argv, "+n:", longopts, NULL);
 140           i += optind - 1;
 141
 142           switch (c)
 143             {
 144             case 'n':
 145               adjustment_given = optarg;
 146               break;
 147
 148             case -1:
 149               break;
 150
 151             case_GETOPT_HELP_CHAR;
 152
 153             case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 154
 155             default:
 156               usage (EXIT_CANCELED);
 157               break;
 158             }
 159
 160           if (c == -1)
 161             break;
 162         }
 163     }
 164
 165   if (adjustment_given)
 166     {
 167       /* If the requested adjustment is outside the valid range,
 168          silently bring it to just within range; this mimics what
 169          "setpriority" and "nice" do.  */
 170       enum { MIN_ADJUSTMENT = 1 - 2 * NZERO, MAX_ADJUSTMENT = 2 * NZERO - 1 };
 171       long int tmp;
 172       if (LONGINT_OVERFLOW < xstrtol (adjustment_given, NULL, 10, &tmp, ""))
 173         die (EXIT_CANCELED, 0, _("invalid adjustment %s"),
 174              quote (adjustment_given));
 175       adjustment = MAX (MIN_ADJUSTMENT, MIN (tmp, MAX_ADJUSTMENT));
 176     }
 177
 178   if (i == argc)
 179     {
 180       if (adjustment_given)
 181         {
 182           error (0, 0, _("a command must be given with an adjustment"));
 183           usage (EXIT_CANCELED);
 184         }
 185       /* No command given; print the niceness.  */
 186       errno = 0;
 187       current_niceness = GET_NICENESS ();
 188       if (current_niceness == -1 && errno != 0)
 189         die (EXIT_CANCELED, errno, _("cannot get niceness"));
 190       printf ("%d\n", current_niceness);
 191       return EXIT_SUCCESS;
 192     }
 193
 194   errno = 0;
 195 #if HAVE_NICE
 196   ok = (nice (adjustment) != -1 || errno == 0);
 197 #else
 198   current_niceness = GET_NICENESS ();
 199   if (current_niceness == -1 && errno != 0)
 200     die (EXIT_CANCELED, errno, _("cannot get niceness"));
 201   ok = (setpriority (PRIO_PROCESS, 0, current_niceness + adjustment) == 0);
 202 #endif
 203   if (!ok)
 204     {
 205       error (perm_related_errno (errno) ? 0
 206              : EXIT_CANCELED, errno, _("cannot set niceness"));
 207       /* error() flushes stderr, but does not check for write failure.
 208          Normally, we would catch this via our atexit() hook of
 209          close_stdout, but execvp() gets in the way.  If stderr
 210          encountered a write failure, there is no need to try calling
 211          error() again.  */
 212       if (ferror (stderr))
 213         return EXIT_CANCELED;
 214     }
 215
 216   execvp (argv[i], &argv[i]);
 217
 218   int exit_status = errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE;
 219   error (0, errno, "%s", quote (argv[i]));
 220   return exit_status;
 221 }