sigsuspend牛刀小试

sigsuspend的整个原子操作过程为：
(1) 设置新的mask阻塞当前进程；
(2) 收到信号，恢复原先mask；
(3) 调用该进程设置的信号处理函数；
(4) 待信号处理函数返回后，sigsuspend返回。

/***********************************************************************************************************************FILE NAME: tell_wait.cpp *CREATE DATE: 2011/06/25 *MODULE: view *AUTHOR: zengqh *---------------------------------------------------------------------------------------------------------------------**MEMO: **********************************************************************************************************************/#include <stdlib.h>#include <stdio.h>#include <unistd.h>#include "apue.h"#include <signal.h>#include <errno.h>/********************************************************************************************************************** *Macros and Structs **********************************************************************************************************************/#define SUCCESS(0)#define FAILURE(-1)/********************************************************************************************************************** *Global Variables Definition Section **********************************************************************************************************************/static volatile sig_atomic_t sig_flag = 0;static sigset_t newmask, oldmask, zeromask;/********************************************************************************************************************** *Functions **********************************************************************************************************************/static voidsig_usr(int signo){sig_flag = 1;}int tell_wait(){if(SIG_ERR == signal(SIGUSR1, sig_usr)){printf("signal failed: SIGUSR1./n");return FAILURE;}if(SIG_ERR == signal(SIGUSR2, sig_usr)){printf("signal failed: SIGUSR2./n");return FAILURE;}sigemptyset(&zeromask);sigemptyset(&newmask);sigaddset(&newmask, SIGUSR1);sigaddset(&newmask, SIGUSR2);if(sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0){printf("sigprocmask failed./n");return FAILURE;}return SUCCESS;}int tell_parent(pid_t pid){kill(pid, SIGUSR2);return SUCCESS;}int wait_parent(){while(0 == sig_flag){sigsuspend(&zeromask);}if(sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0){printf("sigprocmask failed./n");return FAILURE;}return SUCCESS;}int tell_child(pid_t pid){kill(pid, SIGUSR1);return SUCCESS;}int wait_child(){while(0 == sig_flag){sigsuspend(&zeromask);}if(sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0){printf("sigprocmask failed./n");return FAILURE;}return SUCCESS;}int main(){pid_tchild_pid;tell_wait();if((child_pid = fork()) < 0){printf("fork child failed./n");return FAILURE;}if(0 == child_pid){sleep(5);tell_parent(getppid());}else if(child_pid > 0){printf("begin to wait child./n");wait_child();printf("end to wait child./n");}return 0;}/********************************************************************************************************************** *Class **********************************************************************************************************************//********************************************************************************************************************** *Class Members **********************************************************************************************************************//*****************************************************EOF*************************************************************/