#include <iostream>
#include <string>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>

using namespace std;

void Usage(string proc)
{
    cout << "Usage:\n\t" << proc << " signum pid\n\n";
}

int main(int argc, char *argv[])
{
    
     if(argc != 3)
     {
         Usage(argv[0]);
         exit(1);
     }
     int signum = stoi(argv[1]);
     pid_t pid = stoi(argv[2]);

     int n = kill(pid, signum);
     if(n == -1)
     {
         perror("kill");
         exit(2);
     }

    return 0;
}

#include <iostream>
#include <string>
#include <cstdlib>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>

using namespace std;

void Usage(string proc)
{
    cout << "Usage:\n\t" << proc << " signum pid\n\n";
}

// mykill signum pid
int main(int argc, char *argv[])
{
    // signal(2, myhandler);
    int cnt = 0;
    while (true)
    {
        cout << "I am a process, pid: " << getpid() << endl;
        sleep(1);
        cnt++;
        if(cnt % 2 == 0) 
        {
            //kill(getpid(), 2);
            raise(2);      
        }
    }
    return 0；
}

#include <iostream>
#include <string>
#include <cstdlib>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>

using namespace std;

void Usage(string proc)
{
    cout << "Usage:\n\t" << proc << " signum pid\n\n";
}

void myhandler(int signo)
{
    cout << "process get a signal: " << signo <<endl;
    // exit(1);
}

// mykill signum pid
int main(int argc, char *argv[])
{
    // signal(2, myhandler);
    
    signal(SIGABRT, myhandler);
    int cnt = 0;
    while (true)
    {
        cout << "I am a process, pid: " << getpid() << endl;
        sleep(1);
        cnt++;
        if(cnt % 2 == 0) 
        {
            //kill(getpid(), 2);
            //raise(2);   
            abort();   
        }
    }
    return 0；
}

#include <iostream>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>

using namespace std;

void handler(int signo)
{
    cout << "...get a sig, number: " << signo <<endl; //我什么都沒(méi)干，我只是打印了消息
}

int main()
{
    signal(SIG_FPE, handler);
    cout<<"div before"<<endl;
    sleep(1);
    int a = 10;
    int b = 0;

    a /= b;
    cout<<"div after"<<endl;
    sleep(1);
    return 0;

}

#include <iostream>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>

using namespace std;

void handler(int signo)
{
    cout << "...get a sig, number: " << signo <<endl; //我什么都沒(méi)干，我只是打印了消息
}

int main()
{
    signal(SIGSEGV, handler);
    cout<<"point error before"<<endl;
    sleep(1);
    int *p = nullptr;
    *p = 100;

    cout<<"point error after"<<endl;
    sleep(1);
    return 0;

}

#include <iostream>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>

using namespace std;

int main()
{
    // signal(2, SIG_IGN);
    signal(2, SIG_DFL);



    pid_t id = fork();
    if(id == 0)
    {
        //child
        int cnt = 500;
        while(cnt)
        {
            cout << "i am a child process, pid: " << getpid() << "cnt: " << cnt << endl;
            sleep(1);
            cnt--;
        }

        exit(0);
    }

    // father
    int status = 0;
    pid_t rid = waitpid(id, &status, 0);
    if(rid == id)
    {
        cout << "child quit info, rid: " << rid << " exit code: " << 
            ((status>>8)&0xFF) << " exit signal: " << (status&0x7F) <<
                " core dump: " << ((status>>7)&1) << endl; // ? & (0000 0000 ... 0001)
    }
    return 0;
}

#include <iostream>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>

using namespace std;

int main()
{
    // signal(2, SIG_IGN);
    signal(2, SIG_DFL);

    while (1)
    {
        cout << "hello signal" << endl;
        sleep(1);
    }

    int a = 10;
    int b = 0;

    a /= b;

    cout << " a = " << a << endl;
    return 0;
}

#include <iostream>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>

using namespace std;

using namespace std;
void work()
{
    cout << "print log..." << endl;
}

// 信號(hào)為什么會(huì)一直被觸發(fā)？？
void handler(int signo)
{
    // work();
    cout << "...get a sig, number: " << signo <<endl; //我什么都沒(méi)干，我只是打印了消息
    // exit(1);
    int n = alarm(5);
    cout << "剩余時(shí)間：" << n << endl;
}

int main()
{
    signal(SIGALRM, handler);
    int n = alarm(50);

    while(1)
    {
        cout << "proc is running..., pid: " << getpid() << endl;
        sleep(1);
    }

    sleep(1);

    return 0;
}

#include <iostream>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>

using namespace std;

int main()
{
    // signal(2, SIG_IGN);
    signal(2, SIG_DFL);

    while(1)
    {
        cout << "hello signal" << endl;
        sleep(1);
    }
    return 0;
}

#include <signal.h>
int sigemptyset(sigset_t *set);
int sigfillset(sigset_t *set);
int sigaddset (sigset_t *set, int signo);
int sigdelset(sigset_t *set, int signo);
int sigismember（const sigset_t *set, int signo);

#include <signal.h>
int sigprocmask(int how, const sigset_t *set, sigset_t *oset); 
返回值:若成功則為0,若出錯(cuò)則為-1

#include <iostream>
#include <unistd.h>
#include <signal.h>

using namespace std;

void PrintPending(sigset_t &pending)
{
    for (int signo = 31; signo >= 1; signo--)
    {
        if (sigismember(&pending, signo))
        {
            cout << "1";
        }
        else
        {
            cout << "0";
        }
    }
    cout << "\n\n";
}

void handler(int signo)
{
    cout << "catch a signo: " << signo << endl;
}

int main()
{
    // 0. 對(duì)2號(hào)信號(hào)進(jìn)行自定義捕捉
    signal(2, handler);

    // 1. 先對(duì)2號(hào)信號(hào)進(jìn)行屏蔽 --- 數(shù)據(jù)預(yù)備
    sigset_t bset, oset; // 在哪里開(kāi)辟的空間？？？用戶棧上的，屬于用戶區(qū)
    sigemptyset(&bset);
    sigemptyset(&oset);
    sigaddset(&bset, 2); // 我們已經(jīng)把2好信號(hào)屏蔽了嗎？并沒(méi)有設(shè)置進(jìn)入到你的進(jìn)程的task_struct
    // 1.2 調(diào)用系統(tǒng)調(diào)用，將數(shù)據(jù)設(shè)置進(jìn)內(nèi)核
    sigprocmask(SIG_SETMASK, &bset, &oset); // 我們已經(jīng)把2好信號(hào)屏蔽了嗎？ok

    // 2. 重復(fù)打印當(dāng)前進(jìn)程的pending 0000000000000000000000000
    sigset_t pending;
    int cnt = 0;
    while (true)
    {
        // 2.1 獲取
        int n = sigpending(&pending);
        if (n < 0)
            continue;
        // 2.2 打印
        PrintPending(pending);

        sleep(1);
        cnt++;
        // 2.3 解除阻塞
        if(cnt == 20)
        {
            cout << "unblock 2 signo" << endl;
            sigprocmask(SIG_SETMASK, &oset, nullptr); // 我們已經(jīng)把2好信號(hào)屏蔽了嗎？ok
        }
    }
    // 3 發(fā)送2號(hào) 0000000000000000000000010

    return 0;
}

#include <iostream>
#include <unistd.h>
#include <signal.h>

using namespace std;

void PrintPending(sigset_t &pending)
{
    for (int signo = 31; signo >= 1; signo--)
    {
        if (sigismember(&pending, signo))
        {
            cout << "1";
        }
        else
        {
            cout << "0";
        }
    }
    cout << "\n\n";
}

void handler(int signo)
{
    cout << "catch a signo: " << signo << endl;
}

int main()
{
    // 4. 我可以將所有的信號(hào)都進(jìn)行屏蔽，信號(hào)不就不會(huì)被處理了嗎？ 肯定的！9
    sigset_t bset, oset;
    sigemptyset(&bset);
    sigemptyset(&oset);
    for (int i = 1; i <= 31; i++)
    {
        sigaddset(&bset, i); // 屏蔽了所有信號(hào)嗎？？？
    }
    sigprocmask(SIG_SETMASK, &bset, &oset);

    sigset_t pending;
    while (true)
    {
        // 2.1 獲取
        int n = sigpending(&pending);
        if (n < 0)
            continue;
        // 2.2 打印
        PrintPending(pending);
        sleep(1);
    }
    return 0;
}

#include <iostream>
#include <cstring>
#include <unistd.h>
#include <signal.h>

using namespace std;

void handler(int signo)
{
    cout<< "catch a signal, signal number : " << signo << endl;
}

int main()
{
    struct sigaction act, oact;
    memset(&act, 0, sizeof(act));
    memset(&oact, 0, sizeof(oact));
    
    act.sa_handler = handler;

    sigaction(2,&act,&oact);

    while (true)
    {
        cout << "I am a process: " << getpid() << endl;
        sleep(1);
    }

    return 0;
}

#include <iostream>
#include <cstring>
#include <unistd.h>
#include <signal.h>

using namespace std;

void PrintPending()
{
    sigset_t set;
    sigpending(&set);

    for (int signo = 1; signo <= 31; signo++)
    {
        if (sigismember(&set, signo))
            cout << "1";
        else
            cout << "0";
    }
    cout << "\n";
}

void handler(int signo)
{
    PrintPending();
    sleep(1);
}

int main()
{
    struct sigaction act, oact;
    memset(&act, 0, sizeof(act));
    memset(&oact, 0, sizeof(oact));
    
    act.sa_handler = handler;

    sigaction(2,&act,&oact);

    while (true)
    {
        cout << "I am a process: " << getpid() << endl;
        sleep(1);
    }

    return 0;
}

#include <iostream>
#include <cstring>
#include <unistd.h>
#include <signal.h>

using namespace std;

void PrintPending()
{
    sigset_t set;
    sigpending(&set);

    for (int signo = 1; signo <= 31; signo++)
    {
        if (sigismember(&set, signo))
            cout << "1";
        else
            cout << "0";
    }
    cout << "\n";
}

void handler(int signo)
{
    cout << "catch a signal, signal number : " << signo << endl;
    while (true)
    {
        PrintPending();
        sleep(1);
    }
}

int main()
{
    struct sigaction act, oact;
    memset(&act, 0, sizeof(act));
    memset(&oact, 0, sizeof(oact));
    
    act.__sigaction_handler = handler;

    sigaction(2,&act,&oact);

    while (true)
    {
        cout << "I am a process: " << getpid() << endl;
        sleep(1);
    }

    return 0;
}

#include <iostream>
#include <cstring>
#include <unistd.h>
#include <signal.h>

using namespace std;

void PrintPending()
{
    sigset_t set;
    sigpending(&set);

    for (int signo = 1; signo <= 31; signo++)
    {
        if (sigismember(&set, signo))
            cout << "1";
        else
            cout << "0";
    }
    cout << "\n";
}

void handler(int signo)
{
    cout << "catch a signal, signal number : " << signo << endl;
    while (true)
    {
        PrintPending();
        sleep(1);
    }
}

int main()
{
    struct sigaction act, oact;
    memset(&act, 0, sizeof(act));
    memset(&oact, 0, sizeof(oact));
    
    sigemptyset(&act.sa_mask);
    sigaddset(&act.sa_mask, 1);
    sigaddset(&act.sa_mask, 3);
    sigaddset(&act.sa_mask, 4);

    act.__sigaction_handler = handler;

    sigaction(2, &act, &oact);

    while (true)
    {
        cout << "I am a process: " << getpid() << endl;
        sleep(1);
    }

    return 0;
}

mysignal:mysignal.cc
	g++ -o $@ $^ -O3 -g -std=c++11
.PHONY:clean
clean:
	rm -f mysignal

#include <iostream>
#include <cstring>
#include <unistd.h>
#include <signal.h>

using namespace std;

volatile int flag = 0;

void handler(int signo)
{
    cout << "catch a signal: " << signo << endl;
    flag = 1;
}

int main()
{
    signal(2, handler);
    // 在優(yōu)化條件下， flag變量可能被直接優(yōu)化到CPU內(nèi)的寄存器中
    while(!flag); // flag 0, !falg 真

    cout << "process quit normal" << endl;
    return 0;
}

#include <iostream>
#include <cstdlib>
#include <signal.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>
 
void handler(int signo)
{
     void handler(int signo)
 {
     sleep(5);
     pid_t rid;
     while ((rid = waitpid(-1, nullptr, WNOHANG)) > 0)
     {
         cout << "I am proccess: " << getpid() << " catch a signo: " << signo << "child             
          process quit: " << rid << endl;
     }
 }
}
 
// 驗(yàn)證子進(jìn)程退出，給父進(jìn)程發(fā)送SIGCHLD
int main()
{
    signal(SIGCHLD, handler);
    // 問(wèn)題1: 1個(gè)子進(jìn)程，10個(gè)呢？
    // 問(wèn)題2: 10個(gè)子進(jìn)程，6個(gè)退出了！
    for (int i = 0; i < 10; i++)
    {
        if (fork() == 0)
        {
            sleep(5);
            std::cout << "子進(jìn)程退出" << std::endl;
            // 子進(jìn)程
            exit(0);
        }
    }
 
    while (true)
    {
        sleep(1);
    }
    return 0;
}

int main()
{
    signal(SIGCHLD, handler);
    // 問(wèn)題1: 1個(gè)子進(jìn)程，10個(gè)呢？
    // 問(wèn)題2: 10個(gè)子進(jìn)程，6個(gè)退出了！
    for (int i = 0; i < 10; i++)
    {
        if (fork() == 0)
        {
            sleep(5);
            std::cout << "子進(jìn)程退出" << std::endl;
            // 子進(jìn)程
            exit(0);
        }
    }
 
    while (true)
    {
        sleep(1);
    }
    return 0;
}