stdlib/tst-setcontext.c

   1 /* Copyright (C) 2001-2014 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 <stdlib.h>
  21 #include <string.h>
  22 #include <ucontext.h>
  23 #include <unistd.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[32768];
  31
  32 static void
  33 f1 (int a0, int a1, int a2, int a3)
  34 {
  35   printf ("start f1(a0=%x,a1=%x,a2=%x,a3=%x)\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 void
  76 test_stack(volatile int a, volatile int b,
  77            volatile int c, volatile int d)
  78 {
  79   volatile int e = 5;
  80   volatile int f = 6;
  81   ucontext_t uc;
  82
  83   /* Test for cases where getcontext is clobbering the callers
  84      stack, including parameters.  */
  85   getcontext(&uc);
  86
  87   if (a != 1)
  88     {
  89       printf ("%s: getcontext clobbers parm a\n", __FUNCTION__);
  90       exit (1);
  91     }
  92
  93   if (b != 2)
  94     {
  95       printf ("%s: getcontext clobbers parm b\n", __FUNCTION__);
  96       exit (1);
  97     }
  98
  99   if (c != 3)
 100     {
 101       printf ("%s: getcontext clobbers parm c\n", __FUNCTION__);
 102       exit (1);
 103     }
 104
 105   if (d != 4)
 106     {
 107       printf ("%s: getcontext clobbers parm d\n", __FUNCTION__);
 108       exit (1);
 109     }
 110
 111   if (e != 5)
 112     {
 113       printf ("%s: getcontext clobbers varible e\n", __FUNCTION__);
 114       exit (1);
 115     }
 116
 117   if (f != 6)
 118     {
 119       printf ("%s: getcontext clobbers variable f\n", __FUNCTION__);
 120       exit (1);
 121     }
 122 }
 123
 124 volatile int global;
 125
 126
 127 static int back_in_main;
 128
 129
 130 static void
 131 check_called (void)
 132 {
 133   if (back_in_main == 0)
 134     {
 135       puts ("program did not reach main again");
 136       _exit (1);
 137     }
 138 }
 139
 140
 141 int
 142 main (void)
 143 {
 144   atexit (check_called);
 145
 146   char st1[32768];
 147
 148   puts ("making contexts");
 149   if (getcontext (&ctx[1]) != 0)
 150     {
 151       if (errno == ENOSYS)
 152         {
 153           back_in_main = 1;
 154           exit (0);
 155         }
 156
 157       printf ("%s: getcontext: %m\n", __FUNCTION__);
 158       exit (1);
 159     }
 160
 161   test_stack (1, 2, 3, 4);
 162
 163   /* Play some tricks with this context.  */
 164   if (++global == 1)
 165     if (setcontext (&ctx[1]) != 0)
 166       {
 167         printf ("%s: setcontext: %m\n", __FUNCTION__);
 168         exit (1);
 169       }
 170   if (global != 2)
 171     {
 172       printf ("%s: 'global' not incremented twice\n", __FUNCTION__);
 173       exit (1);
 174     }
 175
 176   ctx[1].uc_stack.ss_sp = st1;
 177   ctx[1].uc_stack.ss_size = sizeof st1;
 178   ctx[1].uc_link = &ctx[0];
 179   {
 180     ucontext_t tempctx = ctx[1];
 181     makecontext (&ctx[1], (void (*) (void)) f1, 4, 1, 2, 3, -4);
 182
 183     /* Without this check, a stub makecontext can make us spin forever.  */
 184     if (memcmp (&tempctx, &ctx[1], sizeof ctx[1]) == 0)
 185       {
 186         puts ("makecontext was a no-op, presuming not implemented");
 187         return 0;
 188       }
 189   }
 190
 191   if (getcontext (&ctx[2]) != 0)
 192     {
 193       printf ("%s: second getcontext: %m\n", __FUNCTION__);
 194       exit (1);
 195     }
 196   ctx[2].uc_stack.ss_sp = st2;
 197   ctx[2].uc_stack.ss_size = sizeof st2;
 198   ctx[2].uc_link = &ctx[1];
 199   makecontext (&ctx[2], f2, 0);
 200
 201   puts ("swapping contexts");
 202   if (swapcontext (&ctx[0], &ctx[2]) != 0)
 203     {
 204       printf ("%s: swapcontext: %m\n", __FUNCTION__);
 205       exit (1);
 206     }
 207   puts ("back at main program");
 208   back_in_main = 1;
 209
 210   if (was_in_f1 == 0)
 211     {
 212       puts ("didn't reach f1");
 213       exit (1);
 214     }
 215   if (was_in_f2 == 0)
 216     {
 217       puts ("didn't reach f2");
 218       exit (1);
 219     }
 220
 221   puts ("test succeeded");
 222   return 0;
 223 }