src/nice.c

   1 /* nice -- run a program with modified niceness
   2    Copyright (C) 1990-2024 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 <https://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 "quote.h"
  33 #include "xstrtol.h"
  34
  35 /* The official name of this program (e.g., no 'g' prefix).  */
  36 #define PROGRAM_NAME "nice"
  37
  38 #define AUTHORS proper_name ("David MacKenzie")
  39
  40 #if HAVE_NICE
  41 # define GET_NICENESS() nice (0)
  42 #else
  43 # define GET_NICENESS() getpriority (PRIO_PROCESS, 0)
  44 #endif
  45
  46 #ifndef NZERO
  47 # define NZERO 20
  48 #endif
  49
  50 /* This is required for Darwin Kernel Version 7.7.0.  */
  51 #if NZERO == 0
  52 # undef  NZERO
  53 # define NZERO 20
  54 #endif
  55
  56 static struct option const longopts[] =
  57 {
  58   {"adjustment", required_argument, nullptr, 'n'},
  59   {GETOPT_HELP_OPTION_DECL},
  60   {GETOPT_VERSION_OPTION_DECL},
  61   {nullptr, 0, nullptr, 0}
  62 };
  63
  64 void
  65 usage (int status)
  66 {
  67   if (status != EXIT_SUCCESS)
  68     emit_try_help ();
  69   else
  70     {
  71       printf (_("Usage: %s [OPTION] [COMMAND [ARG]...]\n"), program_name);
  72       printf (_("\
  73 Run COMMAND with an adjusted niceness, which affects process scheduling.\n\
  74 With no COMMAND, print the current niceness.  Niceness values range from\n\
  75 %d (most favorable to the process) to %d (least favorable to the process).\n\
  76 "),
  77               - NZERO, NZERO - 1);
  78
  79       emit_mandatory_arg_note ();
  80
  81       fputs (_("\
  82   -n, --adjustment=N   add integer N to the niceness (default 10)\n\
  83 "), stdout);
  84       fputs (HELP_OPTION_DESCRIPTION, stdout);
  85       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  86       printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME);
  87       emit_exec_status (PROGRAM_NAME);
  88       emit_ancillary_info (PROGRAM_NAME);
  89     }
  90   exit (status);
  91 }
  92
  93 static bool
  94 perm_related_errno (int err)
  95 {
  96   return err == EACCES || err == EPERM;
  97 }
  98
  99 int
 100 main (int argc, char **argv)
 101 {
 102   int current_niceness;
 103   int adjustment = 10;
 104   char const *adjustment_given = nullptr;
 105   bool ok;
 106   int i;
 107
 108   initialize_main (&argc, &argv);
 109   set_program_name (argv[0]);
 110   setlocale (LC_ALL, "");
 111   bindtextdomain (PACKAGE, LOCALEDIR);
 112   textdomain (PACKAGE);
 113
 114   initialize_exit_failure (EXIT_CANCELED);
 115   atexit (close_stdout);
 116
 117   for (i = 1; i < argc; /* empty */)
 118     {
 119       char const *s = argv[i];
 120
 121       if (s[0] == '-' && ISDIGIT (s[1 + (s[1] == '-' || s[1] == '+')]))
 122         {
 123           adjustment_given = s + 1;
 124           ++i;
 125         }
 126       else
 127         {
 128           int c;
 129           int fake_argc = argc - (i - 1);
 130           char **fake_argv = argv + (i - 1);
 131
 132           /* Ensure that any getopt diagnostics use the right name.  */
 133           fake_argv[0] = argv[0];
 134
 135           /* Initialize getopt_long's internal state.  */
 136           optind = 0;
 137
 138           c = getopt_long (fake_argc, fake_argv, "+n:", longopts, nullptr);
 139           i += optind - 1;
 140
 141           switch (c)
 142             {
 143             case 'n':
 144               adjustment_given = optarg;
 145               break;
 146
 147             case -1:
 148               break;
 149
 150             case_GETOPT_HELP_CHAR;
 151
 152             case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 153
 154             default:
 155               usage (EXIT_CANCELED);
 156               break;
 157             }
 158
 159           if (c == -1)
 160             break;
 161         }
 162     }
 163
 164   if (adjustment_given)
 165     {
 166       /* If the requested adjustment is outside the valid range,
 167          silently bring it to just within range; this mimics what
 168          "setpriority" and "nice" do.  */
 169       enum { MIN_ADJUSTMENT = 1 - 2 * NZERO, MAX_ADJUSTMENT = 2 * NZERO - 1 };
 170       long int tmp;
 171       if (LONGINT_OVERFLOW < xstrtol (adjustment_given, nullptr, 10, &tmp, ""))
 172         error (EXIT_CANCELED, 0, _("invalid adjustment %s"),
 173                quote (adjustment_given));
 174       adjustment = MAX (MIN_ADJUSTMENT, MIN (tmp, MAX_ADJUSTMENT));
 175     }
 176
 177   if (i == argc)
 178     {
 179       if (adjustment_given)
 180         {
 181           error (0, 0, _("a command must be given with an adjustment"));
 182           usage (EXIT_CANCELED);
 183         }
 184       /* No command given; print the niceness.  */
 185       errno = 0;
 186       current_niceness = GET_NICENESS ();
 187       if (current_niceness == -1 && errno != 0)
 188         error (EXIT_CANCELED, errno, _("cannot get niceness"));
 189       printf ("%d\n", current_niceness);
 190       return EXIT_SUCCESS;
 191     }
 192
 193   errno = 0;
 194 #if HAVE_NICE
 195   ok = (nice (adjustment) != -1 || errno == 0);
 196 #else
 197   current_niceness = GET_NICENESS ();
 198   if (current_niceness == -1 && errno != 0)
 199     error (EXIT_CANCELED, errno, _("cannot get niceness"));
 200   ok = (setpriority (PRIO_PROCESS, 0, current_niceness + adjustment) == 0);
 201 #endif
 202   if (!ok)
 203     {
 204       error (perm_related_errno (errno) ? 0
 205              : EXIT_CANCELED, errno, _("cannot set niceness"));
 206       /* error() flushes stderr, but does not check for write failure.
 207          Normally, we would catch this via our atexit() hook of
 208          close_stdout, but execvp() gets in the way.  If stderr
 209          encountered a write failure, there is no need to try calling
 210          error() again.  */
 211       if (ferror (stderr))
 212         return EXIT_CANCELED;
 213     }
 214
 215   execvp (argv[i], &argv[i]);
 216
 217   int exit_status = errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE;
 218   error (0, errno, "%s", quote (argv[i]));
 219   return exit_status;
 220 }