我正在 UNIX 和 C++ 中处理信号,遇到了这个问题。我正在尝试编写一个计数到 10 的程序,每秒一个数字,当用户尝试使用 SIGINT(如 CTRL+C(中断它时,它会打印一条消息,告诉它无论如何它都会继续计数。
到目前为止,我得到了这个:
#include <iostream>
#include <signal.h>
#include <zconf.h>
using namespace std;
sig_atomic_t they_want_to_interrupt = 0;
void sigint_handler(int signum) {
assert(signum == SIGINT);
they_want_to_interrupt = 1;
}
void register_handler() {
struct sigaction sa;
sigemptyset(&sa.sa_mask);
sigaddset(&sa.sa_mask, SIGINT);
sa.sa_handler = sigint_handler;
sigaction(SIGINT, &sa, 0);
}
int main() {
register_handler();
cout << "Hi! We'll count to a hundred no matter what" << endl;
for (int i = 1; i <= 100; i++) {
if (they_want_to_interrupt == 1) {
cout << endl << "DON'T INTERRUPT ME WHILE I'M COUNTING! I'll count ALL THE WAY THROUGH!!!" << endl;
they_want_to_interrupt = 0;
}
cout << i << " " << flush;
sleep(1);
}
cout << "Done!" << endl;
return 0;
}
现在,我第一次发送中断信号时,它工作正常:
Hi! We'll count to a hundred no matter what
1 2 ^C
DON'T INTERRUPT ME WHILE I'M COUNTING! I'll count ALL THE WAY THROUGH!!!
3 4
但是如果我发送第二个中断信号,该过程就会停止。
为什么会这样?我尝试阅读有关"sigaction"的手册,以尝试查看是否有某些东西可以使我创建的处理程序在捕获信号时不会被弹出并回滚到SIG_DFL,但无法解决。
谢谢
您可以在每次发送信号时重置信号处理程序。 我已经看到这用于处理SIGUSR,当信号可能重复预期时。
#include <iostream>
#include <cassert>
#include <signal.h>
#include <zconf.h>
using namespace std;
void register_handler();
sig_atomic_t they_want_to_interrupt = 0;
void sigint_handler(int signum) {
assert(signum == SIGINT);
they_want_to_interrupt = 1;
register_handler();
}
void register_handler() {
struct sigaction sa;
sigemptyset(&sa.sa_mask);
sigaddset(&sa.sa_mask, SIGINT);
sa.sa_handler = sigint_handler;
sigaction(SIGINT, &sa, 0);
}
int main() {
register_handler();
cout << "Hi! We'll count to a hundred no matter what" << endl;
for (int i = 1; i <= 100; i++) {
if (they_want_to_interrupt == 1) {
cout << endl << "DON'T INTERRUPT ME WHILE I'M COUNTING! I'll count ALL THE WAY THROUGH!!!" << endl;
they_want_to_interrupt = 0;
}
cout << i << " " << flush;
sleep(1);
}
cout << "Done!" << endl;
return 0;
}
在此代码中:
struct sigaction sa;
sigemptyset(&sa.sa_mask);
sigaddset(&sa.sa_mask, SIGINT);
sa.sa_handler = sigint_handler;
sigaction(SIGINT, &sa, 0);
sa.sa_flags
字段(和其他字段(未初始化,这可能会导致意外结果。最好在开始时对结构进行零初始化,例如:
struct sigaction sa = { 0 };
此外,应将sig_atomic_t
标志声明为volatile
,以防止优化程序引入意外行为。