stdlib/tst-setcontext.c

   1 /* Copyright (C) 2001 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <ucontext.h>
  23
  24 static ucontext_t ctx[3];
  25
  26 static int was_in_f1;
  27 static int was_in_f2;
  28
  29 static char st2[8192];
  30
  31 static void
  32 f1 (long a0, long a1, long a2, long a3)
  33 {
  34   printf ("start f1(a0=%lx,a1=%lx,a2=%lx,a3=%lx)\n", a0, a1, a2, a3);
  35
  36   if (a0 != 1 || a1 != 2 || a2 != 3 || a3 != -4)
  37     {
  38       puts ("arg mismatch");
  39       exit (-1);
  40     }
  41
  42   if (swapcontext (&ctx[1], &ctx[2]) != 0)
  43     {
  44       printf ("%s: swapcontext: %m\n", __FUNCTION__);
  45       exit (1);
  46     }
  47   puts ("finish f1");
  48   was_in_f1 = 1;
  49 }
  50
  51 static void
  52 f2 (void)
  53 {
  54   char on_stack[1];
  55
  56   puts ("start f2");
  57
  58   printf ("&on_stack=%p\n", on_stack);
  59   if (on_stack < st2 || on_stack >= st2 + sizeof (st2))
  60     {
  61       printf ("%s: memory stack is not where it belongs!", __FUNCTION__);
  62       exit (1);
  63     }
  64
  65   if (swapcontext (&ctx[2], &ctx[1]) != 0)
  66     {
  67       printf ("%s: swapcontext: %m\n", __FUNCTION__);
  68       exit (1);
  69     }
  70   puts ("finish f2");
  71   was_in_f2 = 1;
  72 }
  73
  74 volatile int global;
  75
  76 int
  77 main (void)
  78 {
  79   char st1[8192];
  80
  81   puts ("making contexts");
  82   if (getcontext (&ctx[1]) != 0)
  83     {
  84       if (errno == ENOSYS)
  85         exit (0);
  86
  87       printf ("%s: getcontext: %m\n", __FUNCTION__);
  88       exit (1);
  89     }
  90
  91   /* Play some tricks with this context.  */
  92   if (++global == 1)
  93     if (setcontext (&ctx[1]) != 0)
  94       {
  95         printf ("%s: setcontext: %m\n", __FUNCTION__);
  96         exit (1);
  97       }
  98   if (global != 2)
  99     {
 100       printf ("%s: 'global' not incremented twice\n", __FUNCTION__);
 101       exit (1);
 102     }
 103
 104   ctx[1].uc_stack.ss_sp = st1;
 105   ctx[1].uc_stack.ss_size = sizeof st1;
 106   ctx[1].uc_link = &ctx[0];
 107   makecontext (&ctx[1], (void (*) (void)) f1, 4, 1, 2, 3, -4);
 108
 109   if (getcontext (&ctx[2]) != 0)
 110     {
 111       printf ("%s: second getcontext: %m\n", __FUNCTION__);
 112       exit (1);
 113     }
 114   ctx[2].uc_stack.ss_sp = st2;
 115   ctx[2].uc_stack.ss_size = sizeof st2;
 116   ctx[2].uc_link = &ctx[1];
 117   makecontext (&ctx[2], f2, 0);
 118
 119   puts ("swapping contexts");
 120   if (swapcontext (&ctx[0], &ctx[2]) != 0)
 121     {
 122       printf ("%s: swapcontext: %m\n", __FUNCTION__);
 123       exit (1);
 124     }
 125   puts ("back at main program");
 126
 127   if (was_in_f1 == 0)
 128     {
 129       puts ("didn't reach f1");
 130       exit (1);
 131     }
 132   if (was_in_f2 == 0)
 133     {
 134       puts ("didn't reach f2");
 135       exit (1);
 136     }
 137
 138   puts ("test succeeded");
 139   return 0;
 140 }