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udp
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6 files changed

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‎LinuxCodes/signal_block.c‎

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/*
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#include<stdio.h>
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#include<signal.h>
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#include<unistd.h>
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int flag_sigusr1 = 0;
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int flag_sigusr2 = 0;
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void sig_usr1(int signo)
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{
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fprintf(stdout, "caught SIGUSR1\n");
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flag_sigusr1 = 1;
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return;
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}
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void sig_usr2(int signo)
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{
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fprintf(stdout, "caught SIGUSR2\n");
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flag_sigusr2 = 1;
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return;
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}
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int main(void){
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sigset_t newmask, oldmask;
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signal(SIGUSR1, sig_usr1);
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signal(SIGUSR2, sig_usr2);
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fprintf(stdout, "catch sigusr1 can break\n");
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while(1)
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{
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if(flag_sigusr1)
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{
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fprintf(stdout, "break\n");
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break;
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}
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sleep(5);
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}
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fprintf(stdout, "first while was broken\n");
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//重新设置为0
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flag_sigusr1 = 0;
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flag_sigusr2 = 0;
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// block SIGUSR1
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sigemptyset(&newmask);
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sigaddset(&newmask, SIGUSR1);
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if(sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)
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{
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perror("sigprocmask error");
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}
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fprintf(stdout, "only catch sigusr2 can break, because sigusr1 has been blocked\n");
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while(1)
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{
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if(flag_sigusr1 || flag_sigusr2)
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{
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fprintf(stdout, "break\n");
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break;
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}
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sleep(5);
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}
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fprintf(stdout, "second while was broken\n");
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fprintf(stdout, "after second while was broken, flag_sigusr1=%d, flag_sigusr2=%d\n", flag_sigusr1, flag_sigusr2);
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return 0;
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}
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*/
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#include<stdio.h>
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#include<signal.h>
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#include<unistd.h>
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#include<pthread.h>
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int flag_sigusr1 = 0;
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int flag_sigusr2 = 0;
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int flag_sighup = 0;
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void sig_usr1(int signo)
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{
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fprintf(stdout, "sig|caught SIGUSR1\n");
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flag_sigusr1 = 1;
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return;
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}
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void sig_usr2(int signo)
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{
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fprintf(stdout, "sig|caught SIGUSR2\n");
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flag_sigusr2 = 1;
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return;
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}
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void sig_hup(int signo)
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{
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fprintf(stdout, "sig|caught SIGHUP\n");
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flag_sighup = 1;
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return;
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}
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void *thread_control_signal(void *arg)
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{
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sigset_t newmask, oldmask;
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sigemptyset(&newmask);
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//thread block sighup
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sigemptyset(&newmask);
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sigaddset(&newmask, SIGHUP);
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if(pthread_sigmask(SIG_BLOCK, &newmask, &oldmask) < 0)
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{
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perror("sigprocmask error");
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}
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fprintf(stdout, "thread|first while. catch sigusr1 or sigusr2 can break\n");
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while(1)
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{
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if(flag_sigusr1 || flag_sigusr2)
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{
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fprintf(stdout, "thread|break\n");
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break;
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}
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sleep(5);
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}
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flag_sigusr1 = 0;
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//thread block SIGUSR1
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sigaddset(&newmask, SIGUSR1);
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if(pthread_sigmask(SIG_BLOCK, &newmask, &oldmask) < 0)
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{
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perror("sigprocmask error");
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}
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fprintf(stdout, "thread|first while. catch sigusr2 can break\n");
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while(1)
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{
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if(flag_sigusr1 || flag_sigusr2)
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{
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fprintf(stdout, "break\n");
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break;
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}
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sleep(10);
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}
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fprintf(stdout, "thread|thread exit\n");
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return (void *)0;
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}
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int main()
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{
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sigset_t newmask;
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pthread_t tid;
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int signo;
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//signal action
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signal(SIGUSR1, sig_usr1);
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signal(SIGUSR2, sig_usr2);
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signal(SIGHUP , sig_hup);
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if(pthread_create(&tid, NULL, thread_control_signal, NULL) < 0)
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{
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perror("create pthread failed");
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return -1;
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}
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//main thread block sigusr1
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sigemptyset(&newmask);
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sigaddset(&newmask, SIGUSR1);
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if(pthread_sigmask(SIG_BLOCK, &newmask, NULL) < 0)
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{
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perror("sigprocmask error");
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}
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//main thread wait sighup
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sigemptyset(&newmask);
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sigaddset(&newmask, SIGHUP);
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if(sigwait(&newmask, &signo) < 0)
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{
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perror("sigwait failed");
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return -1;
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}
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fprintf(stdout, "main|get SIGHUP\n");
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pthread_kill(tid, SIGUSR2);
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pthread_kill(tid, SIGUSR2);
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pthread_join(tid, NULL);
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fprintf(stdout, "main|exit\n");
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return 0;
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}
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‎LinuxCodes/signal_siguser1.c‎

Lines changed: 114 additions & 0 deletions
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/*
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#include <stdio.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <unistd.h>
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#include <sys/wait.h>
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void handler(int signo)
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{
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switch(signo) {
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case SIGUSR1: //处理信号 SIGUSR1
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printf("Parent : catch SIGUSR1\n");
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break;
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case SIGUSR2: //处理信号 SIGUSR2
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printf("Child : catch SIGUSR2\n");
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break;
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default: //本例不支持
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printf("Should not be here\n");
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break;
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}
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}
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int main(void)
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{
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pid_t ppid, cpid;
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//为两个信号设置信号处理函数
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if(signal(SIGUSR1, handler) == SIG_ERR)
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{ //设置出错
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perror("Can't set handler for SIGUSR1\n");
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exit(1);
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}
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if(signal(SIGUSR2, handler) == SIG_ERR)
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{ //设置出错
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perror("Can't set handler for SIGUSR2\n");
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exit(1);
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}
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ppid = getpid();//得到父进程ID
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if((cpid = fork()) < 0)
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{
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perror("fail to fork\n");
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exit(1);
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}
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else if(cpid == 0)
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{
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// 子进程内向父进程发送信号SIGUSER1
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if(kill(ppid, SIGUSR1) == -1)
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{
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perror("fail to send signal\n");
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exit(1);
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}
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while(1);//死循环，等待父进程的信号
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}
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else
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{
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sleep(1);//休眠，保证子进程先运行，并且发送SIGUSR1信号
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// 父进程向自己发送SIGUSER2信号
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if(kill(cpid, SIGUSR2) == -1)
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{
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perror("fail to send signal\n");
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exit(1);
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}
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// 必须sleep一下，否则子进程捕获不到SIGUSER2信号
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sleep(1);
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printf("will kill child\n");//输出提示
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if(kill(cpid, SIGKILL) == -1)
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{ //发送SIGKILL信号，杀死子进程
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perror("fail to send signal\n");
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exit(1);
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}
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if(wait(NULL) ==-1)
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{ //回收子进程状态，避免僵尸进程
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perror("fail to wait\n");
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exit(1);
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}
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printf("child has been killed.\n");
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}
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return;
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}
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*/
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#include <stdio.h>
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#include <signal.h>
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#include <unistd.h>
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static void sig_usr(int);
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int main(void)
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{
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if(signal(SIGUSR1, sig_usr) == SIG_ERR)
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printf("can not catch SIGUSR1\n");
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if(signal(SIGUSR2, sig_usr) == SIG_ERR)
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printf("can not catch SIGUSR2\n");
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for(;;)
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pause();
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}
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static void sig_usr(int signo)
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{
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if(signo == SIGUSR1)
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printf("received SIGUSR1\n");
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else if(signo == SIGUSR2)
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printf("received SIGUSR2\n");
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else
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printf("received signal %d\n", signo);
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}
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‎LinuxCodes/udp_client.cpp‎

Lines changed: 49 additions & 0 deletions
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#include<iostream>
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#include<stdlib.h>
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#include<stdio.h>
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#include<string.h>
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#include<unistd.h>
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#include<sys/socket.h>
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#include<netinet/in.h>
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#include<arpa/inet.h>
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#include<sys/select.h>
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using namespace std;
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#define BUFSZ 1024
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#define PORT 8888
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#define SERVER_IP "127.0.0.1"
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int main(int argc, char *argv[])
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{
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struct sockaddr_in svr_addr;
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int ret;
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int sock;
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socklen_t addrlen = sizeof(struct sockaddr_in);
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char buf[BUFSZ] = {};
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if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
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{
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perror("socket");
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exit(EXIT_FAILURE);
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}
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//sendto()函数需要指定目的端口/地址
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svr_addr.sin_family = AF_INET;
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svr_addr.sin_port = htons(PORT);
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svr_addr.sin_addr.s_addr = inet_addr(SERVER_IP);
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while (1)
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{
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memset(buf, 0, BUFSZ);
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printf("please input: ");
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fgets(buf, BUFSZ, stdin);
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sendto(sock, buf, BUFSZ, 0, (struct sockaddr* )&svr_addr, addrlen);
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ret = recvfrom(sock, buf, BUFSZ, 0, (struct sockaddr* )&svr_addr, &addrlen);
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printf("client: IPAddr = %s, Port = %d, recvfrom-buf = %s\n", inet_ntoa(svr_addr.sin_addr), ntohs(svr_addr.sin_port), buf);
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}
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close(sock);
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return 0;
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}
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