summaryrefslogtreecommitdiff
path: root/stdlib/tst-setcontext.c
blob: 66b2416118852291d7f71e017f4879b19c117a11 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
/* Copyright (C) 2001-2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ucontext.h>
#include <unistd.h>

static ucontext_t ctx[3];

static int was_in_f1;
static int was_in_f2;

static char st2[32768];

static void
f1 (int a0, int a1, int a2, int a3)
{
  printf ("start f1(a0=%x,a1=%x,a2=%x,a3=%x)\n", a0, a1, a2, a3);

  if (a0 != 1 || a1 != 2 || a2 != 3 || a3 != -4)
    {
      puts ("arg mismatch");
      exit (-1);
    }

  if (swapcontext (&ctx[1], &ctx[2]) != 0)
    {
      printf ("%s: swapcontext: %m\n", __FUNCTION__);
      exit (1);
    }
  puts ("finish f1");
  was_in_f1 = 1;
}

static void
f2 (void)
{
  char on_stack[1];

  puts ("start f2");

  printf ("&on_stack=%p\n", on_stack);
  if (on_stack < st2 || on_stack >= st2 + sizeof (st2))
    {
      printf ("%s: memory stack is not where it belongs!", __FUNCTION__);
      exit (1);
    }

  if (swapcontext (&ctx[2], &ctx[1]) != 0)
    {
      printf ("%s: swapcontext: %m\n", __FUNCTION__);
      exit (1);
    }
  puts ("finish f2");
  was_in_f2 = 1;
}

void
test_stack (volatile int a, volatile int b,
	    volatile int c, volatile int d)
{
  volatile int e = 5;
  volatile int f = 6;
  ucontext_t uc;

  /* Test for cases where getcontext is clobbering the callers
     stack, including parameters.  */
  getcontext (&uc);

  if (a != 1)
    {
      printf ("%s: getcontext clobbers parm a\n", __FUNCTION__);
      exit (1);
    }

  if (b != 2)
    {
      printf ("%s: getcontext clobbers parm b\n", __FUNCTION__);
      exit (1);
    }

  if (c != 3)
    {
      printf ("%s: getcontext clobbers parm c\n", __FUNCTION__);
      exit (1);
    }

  if (d != 4)
    {
      printf ("%s: getcontext clobbers parm d\n", __FUNCTION__);
      exit (1);
    }

  if (e != 5)
    {
      printf ("%s: getcontext clobbers varible e\n", __FUNCTION__);
      exit (1);
    }

  if (f != 6)
    {
      printf ("%s: getcontext clobbers variable f\n", __FUNCTION__);
      exit (1);
    }
}

volatile int global;


static int back_in_main;


static void
check_called (void)
{
  if (back_in_main == 0)
    {
      puts ("program did not reach main again");
      _exit (1);
    }
}


int
main (void)
{
  atexit (check_called);

  char st1[32768];
  stack_t stack_before, stack_after;

  sigaltstack (NULL, &stack_before);

  puts ("making contexts");
  if (getcontext (&ctx[1]) != 0)
    {
      if (errno == ENOSYS)
	{
	  back_in_main = 1;
	  exit (0);
	}

      printf ("%s: getcontext: %m\n", __FUNCTION__);
      exit (1);
    }

  test_stack (1, 2, 3, 4);

  /* Play some tricks with this context.  */
  if (++global == 1)
    if (setcontext (&ctx[1]) != 0)
      {
	printf ("%s: setcontext: %m\n", __FUNCTION__);
	exit (1);
      }
  if (global != 2)
    {
      printf ("%s: 'global' not incremented twice\n", __FUNCTION__);
      exit (1);
    }

  ctx[1].uc_stack.ss_sp = st1;
  ctx[1].uc_stack.ss_size = sizeof st1;
  ctx[1].uc_link = &ctx[0];
  {
    ucontext_t tempctx = ctx[1];
    makecontext (&ctx[1], (void (*) (void)) f1, 4, 1, 2, 3, -4);

    /* Without this check, a stub makecontext can make us spin forever.  */
    if (memcmp (&tempctx, &ctx[1], sizeof ctx[1]) == 0)
      {
	puts ("makecontext was a no-op, presuming not implemented");
	return 0;
      }
  }

  if (getcontext (&ctx[2]) != 0)
    {
      printf ("%s: second getcontext: %m\n", __FUNCTION__);
      exit (1);
    }
  ctx[2].uc_stack.ss_sp = st2;
  ctx[2].uc_stack.ss_size = sizeof st2;
  ctx[2].uc_link = &ctx[1];
  makecontext (&ctx[2], f2, 0);

  puts ("swapping contexts");
  if (swapcontext (&ctx[0], &ctx[2]) != 0)
    {
      printf ("%s: swapcontext: %m\n", __FUNCTION__);
      exit (1);
    }
  puts ("back at main program");
  back_in_main = 1;

  sigaltstack (NULL, &stack_after);

  if (was_in_f1 == 0)
    {
      puts ("didn't reach f1");
      exit (1);
    }
  if (was_in_f2 == 0)
    {
      puts ("didn't reach f2");
      exit (1);
    }

  /* Check sigaltstack state is not clobbered as in BZ #16629.  */
  if (stack_before.ss_sp != stack_after.ss_sp)
    {
      printf ("stack ss_sp mismatch: %p %p\n",
	      stack_before.ss_sp, stack_after.ss_sp);
      exit (1);
    }

  if (stack_before.ss_size != stack_after.ss_size)
    {
      printf ("stack ss_size mismatch: %zd %zd\n",
	      stack_before.ss_size, stack_after.ss_size);
      exit (1);
    }

  puts ("test succeeded");
  return 0;
}