stdlib/tst-setcontext.c

   1 /* Copyright (C) 2001,02 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 <string.h>
  23 #include <ucontext.h>
  24
  25 static ucontext_t ctx[3];
  26
  27 static int was_in_f1;
  28 static int was_in_f2;
  29
  30 static char st2[8192];
  31
  32 static void
  33 f1 (long a0, long a1, long a2, long a3)
  34 {
  35   printf ("start f1(a0=%lx,a1=%lx,a2=%lx,a3=%lx)\n", a0, a1, a2, a3);
  36
  37   if (a0 != 1 || a1 != 2 || a2 != 3 || a3 != -4)
  38     {
  39       puts ("arg mismatch");
  40       exit (-1);
  41     }
  42
  43   if (swapcontext (&ctx[1], &ctx[2]) != 0)
  44     {
  45       printf ("%s: swapcontext: %m\n", __FUNCTION__);
  46       exit (1);
  47     }
  48   puts ("finish f1");
  49   was_in_f1 = 1;
  50 }
  51
  52 static void
  53 f2 (void)
  54 {
  55   char on_stack[1];
  56
  57   puts ("start f2");
  58
  59   printf ("&on_stack=%p\n", on_stack);
  60   if (on_stack < st2 || on_stack >= st2 + sizeof (st2))
  61     {
  62       printf ("%s: memory stack is not where it belongs!", __FUNCTION__);
  63       exit (1);
  64     }
  65
  66   if (swapcontext (&ctx[2], &ctx[1]) != 0)
  67     {
  68       printf ("%s: swapcontext: %m\n", __FUNCTION__);
  69       exit (1);
  70     }
  71   puts ("finish f2");
  72   was_in_f2 = 1;
  73 }
  74
  75 volatile int global;
  76
  77 int
  78 main (void)
  79 {
  80   char st1[8192];
  81
  82   puts ("making contexts");
  83   if (getcontext (&ctx[1]) != 0)
  84     {
  85       if (errno == ENOSYS)
  86         exit (0);
  87
  88       printf ("%s: getcontext: %m\n", __FUNCTION__);
  89       exit (1);
  90     }
  91
  92   /* Play some tricks with this context.  */
  93   if (++global == 1)
  94     if (setcontext (&ctx[1]) != 0)
  95       {
  96         printf ("%s: setcontext: %m\n", __FUNCTION__);
  97         exit (1);
  98       }
  99   if (global != 2)
 100     {
 101       printf ("%s: 'global' not incremented twice\n", __FUNCTION__);
 102       exit (1);
 103     }
 104
 105   ctx[1].uc_stack.ss_sp = st1;
 106   ctx[1].uc_stack.ss_size = sizeof st1;
 107   ctx[1].uc_link = &ctx[0];
 108   {
 109     ucontext_t tempctx = ctx[1];
 110     makecontext (&ctx[1], (void (*) (void)) f1, 4, 1, 2, 3, -4);
 111
 112     /* Without this check, a stub makecontext can make us spin forever.  */
 113     if (memcmp (&tempctx, &ctx[1], sizeof ctx[1]) == 0)
 114       {
 115         puts ("makecontext was a no-op, presuming not implemented");
 116         return 0;
 117       }
 118   }
 119
 120   if (getcontext (&ctx[2]) != 0)
 121     {
 122       printf ("%s: second getcontext: %m\n", __FUNCTION__);
 123       exit (1);
 124     }
 125   ctx[2].uc_stack.ss_sp = st2;
 126   ctx[2].uc_stack.ss_size = sizeof st2;
 127   ctx[2].uc_link = &ctx[1];
 128   makecontext (&ctx[2], f2, 0);
 129
 130   puts ("swapping contexts");
 131   if (swapcontext (&ctx[0], &ctx[2]) != 0)
 132     {
 133       printf ("%s: swapcontext: %m\n", __FUNCTION__);
 134       exit (1);
 135     }
 136   puts ("back at main program");
 137
 138   if (was_in_f1 == 0)
 139     {
 140       puts ("didn't reach f1");
 141       exit (1);
 142     }
 143   if (was_in_f2 == 0)
 144     {
 145       puts ("didn't reach f2");
 146       exit (1);
 147     }
 148
 149   puts ("test succeeded");
 150   return 0;
 151 }