xref: /freebsd/lib/libc/tests/sys/swapcontext_test.c (revision b5daf675efc746611c7cfcd1fa474b8905064c4b)
1 /*-
2  * Copyright (c) 2025 Raptor Computing Systems, LLC
3  *
4  * SPDX-License-Identifier: BSD-2-Clause
5  */
6 
7 #include <stdio.h>
8 #include <stdlib.h>
9 #include <ucontext.h>
10 #include <errno.h>
11 
12 #include <atf-c.h>
13 
14 #define STACK_SIZE	(64ull << 10)
15 
16 static volatile int callback_reached = 0;
17 
18 static ucontext_t uctx_save, uctx_switch;
19 
20 static void swapcontext_callback()
21 {
22 	// Increment callback reached variable
23 	// If this is called multiple times, we will fail the test
24 	// If this is not called at all, we will fail the test
25 	callback_reached++;
26 }
27 
28 ATF_TC(swapcontext_basic);
29 ATF_TC_HEAD(swapcontext_basic, tc)
30 {
31 	atf_tc_set_md_var(tc, "descr",
32 		"Verify basic functionality of swapcontext");
33 }
34 
35 ATF_TC_BODY(swapcontext_basic, tc)
36 {
37 	char *stack;
38         int res;
39 
40 	stack = malloc(STACK_SIZE);
41 	ATF_REQUIRE_MSG(stack != NULL, "malloc failed: %s", strerror(errno));
42 	res = getcontext(&uctx_switch);
43 	ATF_REQUIRE_MSG(res == 0, "getcontext failed: %s", strerror(errno));
44 
45 	uctx_switch.uc_stack.ss_sp = stack;
46 	uctx_switch.uc_stack.ss_size = STACK_SIZE;
47 	uctx_switch.uc_link = &uctx_save;
48 	makecontext(&uctx_switch, swapcontext_callback, 0);
49 
50 	res = swapcontext(&uctx_save, &uctx_switch);
51 
52         ATF_REQUIRE_MSG(res == 0, "swapcontext failed: %s", strerror(errno));
53         ATF_REQUIRE_MSG(callback_reached == 1,
54 		"callback failed, reached %d times", callback_reached);
55 }
56 
57 ATF_TP_ADD_TCS(tp)
58 {
59 	ATF_TP_ADD_TC(tp, swapcontext_basic);
60 
61 	return (atf_no_error());
62 }
63 
64