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// Copyright © Tavian Barnes <tavianator@tavianator.com>
// SPDX-License-Identifier: 0BSD
#include "tests.h"
#include "atomic.h"
#include "bfstd.h"
#include "sighook.h"
#include "thread.h"
#include "xtime.h"
#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <stddef.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>
/** Counts SIGALRM deliveries. */
static atomic size_t count = 0;
/** Keeps the background thread alive. */
static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
static bool done = false;
/** SIGALRM handler. */
static void alrm_hook(int sig, siginfo_t *info, void *arg) {
fetch_add(&count, 1, relaxed);
}
/** SH_ONESHOT counter. */
static atomic size_t shots = 0;
/** SH_ONESHOT hook. */
static void alrm_oneshot(int sig, siginfo_t *info, void *arg) {
fetch_add(&shots, 1, relaxed);
}
/** Background thread that receives signals. */
static void *hook_thread(void *ptr) {
mutex_lock(&mutex);
while (!done) {
cond_wait(&cond, &mutex);
}
mutex_unlock(&mutex);
return NULL;
}
/** Block a signal in this thread. */
static int block_signal(int sig, sigset_t *old) {
sigset_t set;
if (sigemptyset(&set) != 0) {
return -1;
}
if (sigaddset(&set, sig) != 0) {
return -1;
}
errno = pthread_sigmask(SIG_BLOCK, &set, old);
if (errno != 0) {
return -1;
}
return 0;
}
/** Tests for sighook(). */
static void check_hooks(void) {
struct sighook *hook = sighook(SIGALRM, alrm_hook, NULL, SH_CONTINUE);
if (!bfs_echeck(hook, "sighook(SIGALRM)")) {
return;
}
// Check that we can unregister and re-register a hook
sigunhook(hook);
hook = sighook(SIGALRM, alrm_hook, NULL, SH_CONTINUE);
if (!bfs_echeck(hook, "sighook(SIGALRM)")) {
return;
}
// Test SH_ONESHOT
struct sighook *oneshot_hook = sighook(SIGALRM, alrm_oneshot, NULL, SH_ONESHOT);
if (!bfs_echeck(oneshot_hook, "sighook(SH_ONESHOT)")) {
goto unhook;
}
// Create a timer that sends SIGALRM every 100 microseconds
struct timespec ival = { .tv_nsec = 100 * 1000 };
struct timer *timer = xtimer_start(&ival);
if (!bfs_echeck(timer)) {
goto unhook;
}
// Create a background thread to receive signals
pthread_t thread;
if (!bfs_echeck(thread_create(&thread, NULL, hook_thread, NULL) == 0)) {
goto untime;
}
// Block SIGALRM in this thread so the handler runs concurrently with
// sighook()/sigunhook()
sigset_t mask;
if (!bfs_echeck(block_signal(SIGALRM, &mask) == 0)) {
goto untime;
}
// Rapidly register/unregister SIGALRM hooks
size_t alarms;
while (alarms = load(&count, relaxed), alarms < 1000) {
size_t nshots = load(&shots, relaxed);
bfs_echeck(nshots <= 1);
if (alarms > 1) {
bfs_echeck(nshots == 1);
}
if (alarms >= 500) {
sigunhook(oneshot_hook);
oneshot_hook = NULL;
}
struct sighook *next = sighook(SIGALRM, alrm_hook, NULL, SH_CONTINUE);
if (!bfs_echeck(next, "sighook(SIGALRM)")) {
break;
}
sigunhook(hook);
hook = next;
}
// Quit the background thread
mutex_lock(&mutex);
done = true;
mutex_unlock(&mutex);
cond_signal(&cond);
thread_join(thread, NULL);
// Restore the old signal mask
errno = pthread_sigmask(SIG_SETMASK, &mask, NULL);
bfs_echeck(errno == 0, "pthread_sigmask()");
untime:
// Stop the timer
xtimer_stop(timer);
unhook:
// Unregister the SIGALRM hooks
sigunhook(oneshot_hook);
sigunhook(hook);
}
/** atsigexit() hook. */
static void exit_hook(int sig, siginfo_t *info, void *arg) {
// Write the signal that's killing us to the pipe
int *pipes = arg;
if (xwrite(pipes[1], &sig, sizeof(sig)) != sizeof(sig)) {
abort();
}
}
/** Tests for atsigexit(). */
static void check_sigexit(int sig) {
// To wait for the child to call atsigexit()
int ready[2];
bfs_everify(pipe(ready) == 0);
// Written in the atsigexit() handler
int killed[2];
bfs_everify(pipe(killed) == 0);
pid_t pid;
bfs_everify((pid = fork()) >= 0);
if (pid > 0) {
// Parent
xclose(ready[1]);
xclose(killed[1]);
// Wait for the child to call atsigexit()
char c;
bfs_everify(xread(ready[0], &c, 1) == 1);
// Kill the child with the signal
bfs_everify(kill(pid, sig) == 0);
// Check that the child died to the right signal
int wstatus;
if (bfs_echeck(xwaitpid(pid, &wstatus, 0) == pid)) {
bfs_check(WIFSIGNALED(wstatus) && WTERMSIG(wstatus) == sig);
}
// Check that the signal hook wrote the signal number to the pipe
int hsig;
if (bfs_echeck(xread(killed[0], &hsig, sizeof(hsig)) == sizeof(hsig))) {
bfs_check(hsig == sig);
}
} else {
// Child
xclose(ready[0]);
xclose(killed[0]);
// exit_hook() will write to killed[1]
bfs_everify(atsigexit(exit_hook, killed) != NULL);
// Tell the parent we're ready
bfs_everify(xwrite(ready[1], "A", 1) == 1);
// Wait until we're killed
while (true) {
pause();
}
}
}
void check_sighook(void) {
check_hooks();
check_sigexit(SIGINT);
check_sigexit(SIGQUIT);
check_sigexit(SIGPIPE);
// macOS cannot distinguish between sync and async SIG{BUS,ILL,SEGV}
#if !__APPLE__
check_sigexit(SIGSEGV);
#endif
}
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