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
|
// Copyright © Tavian Barnes <tavianator@tavianator.com>
// SPDX-License-Identifier: 0BSD
#include "prelude.h"
#include "tests.h"
#include "sighook.h"
#include "atomic.h"
#include "thread.h"
#include <pthread.h>
#include <signal.h>
#include <sys/time.h>
static atomic size_t count = 0;
/** SIGALRM handler. */
static void alrm_hook(int sig, siginfo_t *info, void *arg) {
fetch_add(&count, 1, relaxed);
}
/** Swap out an old hook for a new hook. */
static int swap_hooks(struct sighook **hook) {
struct sighook *next = sighook(SIGALRM, alrm_hook, NULL, SH_CONTINUE);
if (!bfs_pcheck(next, "sighook(SIGALRM)")) {
return -1;
}
sigunhook(*hook);
*hook = next;
return 0;
}
/** Background thread that rapidly (un)registers signal hooks. */
static void *hook_thread(void *ptr) {
struct sighook *hook = sighook(SIGALRM, alrm_hook, NULL, SH_CONTINUE);
if (!bfs_pcheck(hook, "sighook(SIGALRM)")) {
return NULL;
}
while (load(&count, relaxed) < 1000) {
if (swap_hooks(&hook) != 0) {
sigunhook(hook);
return NULL;
}
}
sigunhook(hook);
return &count;
}
bool check_sighook(void) {
bool ret = true;
struct sighook *hook = sighook(SIGALRM, alrm_hook, NULL, SH_CONTINUE);
ret &= bfs_pcheck(hook, "sighook(SIGALRM)");
if (!ret) {
goto done;
}
struct itimerval ival = {
.it_value = {
.tv_usec = 100,
},
.it_interval = {
.tv_usec = 100,
},
};
ret &= bfs_pcheck(setitimer(ITIMER_REAL, &ival, NULL) == 0);
if (!ret) {
goto unhook;
}
pthread_t thread;
ret &= bfs_pcheck(thread_create(&thread, NULL, hook_thread, NULL) == 0);
if (!ret) {
goto untime;
}
while (ret && load(&count, relaxed) < 1000) {
ret &= swap_hooks(&hook) == 0;
}
void *ptr;
thread_join(thread, &ptr);
ret &= bfs_check(ptr);
untime:
ival.it_value.tv_usec = 0;
ret &= bfs_pcheck(setitimer(ITIMER_REAL, &ival, NULL) == 0);
if (!ret) {
goto unhook;
}
unhook:
sigunhook(hook);
done:
return ret;
}
|
