1 /* Copyright (C) 2001-2023 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 variable 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 }