posix/tst-nice.c

   1 /* Copyright (C) 2003-2015 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library 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 GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <stdio.h>
  20 #include <unistd.h>
  21
  22
  23 /* Test that nice() does not incorrectly return 0.  */
  24 static int
  25 do_test (void)
  26 {
  27   int ret;
  28   const int incr = 10;
  29   int old;
  30
  31   /* Discover current nice value.  */
  32   errno = 0;
  33   old = nice (0);
  34   if (old == -1 && errno != 0)
  35     {
  36       printf ("break: nice(%d) return: %d, %m\n", 0, old);
  37       return 1;
  38     }
  39
  40   /* Nice ourselves up.  */
  41   errno = 0;
  42   ret = nice (incr);
  43   if (ret == -1 && errno != 0)
  44     {
  45       printf ("break: nice(%d) return: %d, %m\n", incr, ret);
  46       return 1;
  47     }
  48
  49   /* Check for return value being zero when it shouldn't.  Cannot simply
  50      check for expected value since nice values are capped at 2^n-1.
  51      But we assume that we didn't start at the cap and so should have
  52      increased some.  */
  53   if (ret <= old)
  54     {
  55       printf ("FAIL: retval (%d) of nice(%d) != %d\n", ret, incr, old + incr);
  56       return 1;
  57     }
  58
  59   printf ("PASS: nice(%d) from %d return: %d\n", incr, old, ret);
  60
  61   return 0;
  62 }
  63
  64 #define TEST_FUNCTION do_test ()
  65 #include "../test-skeleton.c"