stdlib/tst-setcontext.c

   1 /* Copyright (C) 2001-2022 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    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <signal.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <ucontext.h>
  24 #include <unistd.h>
  25
  26 static ucontext_t ctx[3];
  27
  28 static int was_in_f1;
  29 static int was_in_f2;
  30
  31 static char st2[32768];
  32
  33 static void
  34 f1 (int a0, int a1, int a2, int a3)
  35 {
  36   printf ("start f1(a0=%x,a1=%x,a2=%x,a3=%x)\n", a0, a1, a2, a3);
  37
  38   if (a0 != 1 || a1 != 2 || a2 != 3 || a3 != -4)
  39     {
  40       puts ("arg mismatch");
  41       exit (-1);
  42     }
  43
  44   if (swapcontext (&ctx[1], &ctx[2]) != 0)
  45     {
  46       printf ("%s: swapcontext: %m\n", __FUNCTION__);
  47       exit (1);
  48     }
  49   puts ("finish f1");
  50   was_in_f1 = 1;
  51 }
  52
  53 static void
  54 f2 (void)
  55 {
  56   char on_stack[1];
  57
  58   puts ("start f2");
  59
  60   printf ("&on_stack=%p\n", on_stack);
  61   if (&on_stack[0] < &st2[0] || &on_stack[0] >= st2 + sizeof (st2))
  62     {
  63       printf ("%s: memory stack is not where it belongs!", __FUNCTION__);
  64       exit (1);
  65     }
  66
  67   if (swapcontext (&ctx[2], &ctx[1]) != 0)
  68     {
  69       printf ("%s: swapcontext: %m\n", __FUNCTION__);
  70       exit (1);
  71     }
  72   puts ("finish f2");
  73   was_in_f2 = 1;
  74 }
  75
  76 void
  77 test_stack (volatile int a, volatile int b,
  78             volatile int c, volatile int d)
  79 {
  80   volatile int e = 5;
  81   volatile int f = 6;
  82   ucontext_t uc;
  83
  84   /* Test for cases where getcontext is clobbering the callers
  85      stack, including parameters.  */
  86   getcontext (&uc);
  87
  88   if (a != 1)
  89     {
  90       printf ("%s: getcontext clobbers parm a\n", __FUNCTION__);
  91       exit (1);
  92     }
  93
  94   if (b != 2)
  95     {
  96       printf ("%s: getcontext clobbers parm b\n", __FUNCTION__);
  97       exit (1);
  98     }
  99
 100   if (c != 3)
 101     {
 102       printf ("%s: getcontext clobbers parm c\n", __FUNCTION__);
 103       exit (1);
 104     }
 105
 106   if (d != 4)
 107     {
 108       printf ("%s: getcontext clobbers parm d\n", __FUNCTION__);
 109       exit (1);
 110     }
 111
 112   if (e != 5)
 113     {
 114       printf ("%s: getcontext clobbers varible e\n", __FUNCTION__);
 115       exit (1);
 116     }
 117
 118   if (f != 6)
 119     {
 120       printf ("%s: getcontext clobbers variable f\n", __FUNCTION__);
 121       exit (1);
 122     }
 123 }
 124
 125 volatile int global;
 126
 127
 128 static int back_in_main;
 129
 130
 131 static void
 132 check_called (void)
 133 {
 134   if (back_in_main == 0)
 135     {
 136       puts ("program did not reach main again");
 137       _exit (1);
 138     }
 139 }
 140
 141
 142 int
 143 main (void)
 144 {
 145   atexit (check_called);
 146
 147   char st1[32768];
 148   stack_t stack_before, stack_after;
 149
 150   sigaltstack (NULL, &stack_before);
 151
 152   puts ("making contexts");
 153   if (getcontext (&ctx[1]) != 0)
 154     {
 155       if (errno == ENOSYS)
 156         {
 157           back_in_main = 1;
 158           exit (0);
 159         }
 160
 161       printf ("%s: getcontext: %m\n", __FUNCTION__);
 162       exit (1);
 163     }
 164
 165   test_stack (1, 2, 3, 4);
 166
 167   /* Play some tricks with this context.  */
 168   if (++global == 1)
 169     if (setcontext (&ctx[1]) != 0)
 170       {
 171         printf ("%s: setcontext: %m\n", __FUNCTION__);
 172         exit (1);
 173       }
 174   if (global != 2)
 175     {
 176       printf ("%s: 'global' not incremented twice\n", __FUNCTION__);
 177       exit (1);
 178     }
 179
 180   ctx[1].uc_stack.ss_sp = st1;
 181   ctx[1].uc_stack.ss_size = sizeof st1;
 182   ctx[1].uc_link = &ctx[0];
 183   {
 184     ucontext_t tempctx = ctx[1];
 185     makecontext (&ctx[1], (void (*) (void)) f1, 4, 1, 2, 3, -4);
 186
 187     /* Without this check, a stub makecontext can make us spin forever.  */
 188     if (memcmp (&tempctx, &ctx[1], sizeof ctx[1]) == 0)
 189       {
 190         puts ("makecontext was a no-op, presuming not implemented");
 191         return 0;
 192       }
 193   }
 194
 195   if (getcontext (&ctx[2]) != 0)
 196     {
 197       printf ("%s: second getcontext: %m\n", __FUNCTION__);
 198       exit (1);
 199     }
 200   ctx[2].uc_stack.ss_sp = st2;
 201   ctx[2].uc_stack.ss_size = sizeof st2;
 202   ctx[2].uc_link = &ctx[1];
 203   makecontext (&ctx[2], f2, 0);
 204
 205   puts ("swapping contexts");
 206   if (swapcontext (&ctx[0], &ctx[2]) != 0)
 207     {
 208       printf ("%s: swapcontext: %m\n", __FUNCTION__);
 209       exit (1);
 210     }
 211   puts ("back at main program");
 212   back_in_main = 1;
 213
 214   sigaltstack (NULL, &stack_after);
 215
 216   if (was_in_f1 == 0)
 217     {
 218       puts ("didn't reach f1");
 219       exit (1);
 220     }
 221   if (was_in_f2 == 0)
 222     {
 223       puts ("didn't reach f2");
 224       exit (1);
 225     }
 226
 227   /* Check sigaltstack state is not clobbered as in BZ #16629.  */
 228   if (stack_before.ss_sp != stack_after.ss_sp)
 229     {
 230       printf ("stack ss_sp mismatch: %p %p\n",
 231               stack_before.ss_sp, stack_after.ss_sp);
 232       exit (1);
 233     }
 234
 235   if (stack_before.ss_size != stack_after.ss_size)
 236     {
 237       printf ("stack ss_size mismatch: %zd %zd\n",
 238               stack_before.ss_size, stack_after.ss_size);
 239       exit (1);
 240     }
 241
 242   puts ("test succeeded");
 243   return 0;
 244 }