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1. 測試代碼：
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#include<stdio.h>
#include<stdlib.h>
#include<signal.h>
#include<errno.h>
#include<unistd.h>void catch_sigalrm(int signo)
{;
}unsigned int mysleep(unsigned int seconds)
{struct sigaction newact, oldact;sigset_t newmask, oldmask, suspmask;unsigned int unmask;//1. 為SIGALRM設置捕捉函數，一個空函數newact.sa_handler = sig_alrm;sigemptyset(&newact.sa_mask);newact.sa_flags = 0;sigaction(SIGALRM, &newact, &oldact);// 2. 設置阻塞信號集，阻塞SIGLARM信號sigemptyset(&newmask);sigaddset(*newact.sa_mask， SIGALRM);sigpromask(SIG_BLOCK, &newact, &oldact); //信號屏蔽字// 3、定時h秒，到時可以產生SIGALRM信號alarm(nsecs);/* 4. 構造一個調用sigsuspend臨時有效的阻塞信號集，* 臨時阻塞信號集里面解除SIGALRM的阻塞*/suspmask = oldmask;sigdelset(&suspmask, SIGALRM);/* 5. sigsuspend調用期間，采用臨時阻塞信號集suspmask替換原有阻塞信號集* 這個信號集中不包含SIGALRM信號，同時掛起等待* 當sigsuspend被信號喚醒返回時，恢復原有的阻塞信號集*/sigsuspend(&suspmask);unslept = alarm(0);//6. 恢復SIGALRM原有的處理動作，呼應前面注釋1sigaction(SIGLARM, &oldact, NULL);//7. 解除對SIGALRM的阻塞，呼應前面注釋2 sigprocmask(SIG_SETMASK, &oldmask, NULL);return (unslept);
}int main()
{while (1) {mysleep(3);printf("----------------------------\n");}return 0;
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2. 測試代碼：
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>int n = 0, flag = 0;void sys_err(char *str)
{perror(str);exit(1);
}void do_sig_child(int num)
{printf("I am child %d\t%d\n", getpid(), n);n += 2;flag = 1;sleep(1);
}void do_sig_parent(int num)
{printf("I am parent %d\t%d\n", getpid(), n);n += 2;flag = 1; //數數完成 sleep(1);
}int main(void)
{pid_t pid;struct sigaction act;if ((pid = fork()) < 0)sys_err("fork");else if (pid > 0) {n = 1;sleep(1);act.sa_handler = do_sig_parent;sigemptyset(&act.sa_mask);act.sa_flags = 0;sigaction(SIGUSR2, &act, NULL); //祖冊自己的信號捕捉函數 父用SIGUSR2信號 do_sig_parent(0);while (1) {/* wait for signal*/if (flag == 1) {kill(pid, SIGUSR1); //父進程數數完成flag = 0; //標志已經給子進程發送信號完信號 }}}else if (pid == 0) {n = 2;act.sa_handler = do_sig_child;sigemptyset(&act.sa_mask);act.sa_flags = 0;sigaction(SIGUSR1, &act, NULL);while (1) {/* wait for signal*/if (flag == 1) {kill(getppid(), SIGUSR2);flag = 0; //標志已經給父進程發送信號了 }}}return 0;
}測試代碼：
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>int n = 0, flag = 0;void sys_err(char *str)
{perror(str);exit(1);
}void do_sig_child(int num)
{printf("I am child %d\t%d\n", getpid(), n);n += 2;flag = 1;// sleep(1);
}void do_sig_parent(int num)
{printf("I am parent %d\t%d\n", getpid(), n);n += 2;flag = 1; //數數完成 //sleep(1);
}int main(void)
{pid_t pid;struct sigaction act;if ((pid = fork()) < 0)sys_err("fork");else if (pid > 0) {n = 1;sleep(1);act.sa_handler = do_sig_parent;sigemptyset(&act.sa_mask);act.sa_flags = 0;sigaction(SIGUSR2, &act, NULL); //祖冊自己的信號捕捉函數 父用SIGUSR2信號 do_sig_parent(0);while (1) {/* wait for signal*/if (flag == 1) {kill(pid, SIGUSR1); //父進程數數完成flag = 0; //標志已經給子進程發送信號完信號 }}}else if (pid == 0) {n = 2;act.sa_handler = do_sig_child;sigemptyset(&act.sa_mask);act.sa_flags = 0;sigaction(SIGUSR1, &act, NULL);while (1) {/* wait for signal*/if (flag == 1) {kill(getppid(), SIGUSR2);flag = 0; //標志已經給父進程發送信號了 }}}return 0;
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