linux 信号屏蔽

<span style="font-size:18px;">#include <sys/types.h>#include <unistd.h>#include <signal.h>#include <stdio.h>#include <stdlib.h>#include <errno.h>/*sigemptyset(&newmask);//获取空屏蔽信号集sigfillset(&newmask);//获取屏蔽了所有信号的屏蔽信号集，除了那两个SIGKILL SIGSTOPsigpending(&pendmask);//获取进程中当前的屏蔽信号集sigaddset(&newmask, SIGQUIT);//往空屏蔽信号集加入SIGQUIT(sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)//并集(sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)//设置会原来的屏蔽信号集(sigismember(&fillmask, SIGQUIT))//判断SIGQUIT是否在当前的屏蔽信号集中*/static voidsig_quit(int);intmain(void){sigset_tnewmask, oldmask, pendmask,fillmask;if (signal(SIGQUIT, sig_quit) == SIG_ERR)//设置信号处理函数perror("can't catch SIGQUIT");/* * Block SIGQUIT and save current signal mask. */sigemptyset(&newmask);//获取空屏蔽信号集sigaddset(&newmask, SIGQUIT);//往空屏蔽信号集加入SIGQUITif (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)//并集perror("SIG_BLOCK error");sleep(5);/* SIGQUIT here will remain pending */    //睡眠期间按下多次 ctrl+\   未决信号集中之保留一次if (sigpending(&pendmask) < 0)//获取进程中当前的屏蔽信号集perror("sigpending error");if (sigismember(&pendmask, SIGQUIT))//判断SIGQUIT是否在当前的屏蔽信号集中printf("\nSIGQUIT pending\n");/* * Restore signal mask which unblocks SIGQUIT. */if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)//设置会原来的屏蔽信号集，由于SIGQUIT保留着一个未决信号，所以这里触发了信号处理函数，SIGQUIT变回默认处理perror("SIG_SETMASK error");printf("SIGQUIT unblocked\n");sleep(5);/* SIGQUIT here will terminate with core file */ //在此期间按下  ctrl+\ 执行信号处理函数 ，调用默认处理。game over！printf("fillmask test\n");if (sigfillset(&fillmask) < 0)//获取屏蔽了所有信号的屏蔽信号集，除了那两个SIGKILL SIGSTOPperror("sigfillset error\n");if (sigismember(&fillmask, SIGQUIT))//判断SIGQUIT是否在当前的屏蔽信号集中printf("\nSIGQUIT pending\n");//在if (sigprocmask(SIG_SETMASK,&fillmask , &oldmask) < 0)//设置屏蔽所有perror("fillmask error\n");sleep(5);if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)//如果在fillmask测试期间有按下ctrl+\，则下面不会睡眠5秒了，执行了SIGQUIT的默认处理函数perror("SIG_SETMASK error\n");sleep(5);exit(0);}static voidsig_quit(int signo){printf("caught SIGQUIT\n");//if (signal(SIGQUIT, SIG_DFL) == SIG_ERR)//perror("can't reset SIGQUIT");}</span>