UNIX环境高级编程学习之第十章信号-用信号实现父子进程同步

UNIX环境高级编程学习之第十章信号-用信号实现父子进程同步

/* FileName:ParentAndChildProcessSynchronous.c
   Date:    20100309
   Description: 用信号实现父子进程同步。
*/
#include 
#include 
#include 
#include 
#include 
static volatile sig_atomic_t sigflag;
static sigset_t newmask, oldmask, zeromask;
static void sig_usr(int signo)
{
        sigflag = 1;
}
void TELL_WAIT(void)
{
        if (signal(SIGUSR1, sig_usr) == SIG_ERR)
        {
                printf("signal(SIGUSR1) ERROR /n");
                exit(-1);
        }
        if (signal(SIGUSR2, sig_usr) == SIG_ERR)
        {
                printf("signal(SIGUSR2) ERROR /n");
                exit(-1);
        }
        sigemptyset(&zeromask);
        sigemptyset(&newmask);
        sigaddset(&newmask, SIGUSR1);
        sigaddset(&newmask, SIGUSR2);
        if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)
        {
                printf("SIB_BLOCK ERROR /n");
                exit(-1);
        }
} 
void TELL_PARENT(pid_t pid)
{
        kill(pid, SIGUSR2);
}
void WAIT_PARENT(void)
{
        while (sigflag == 0)
        {
                sigsuspend(&zeromask);
        }
        sigflag = 0;
        if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
        {
                printf("SIG_SETMASK ERROR/n");
                exit(-1);
        }
}
void TELL_CHILD(pid_t pid)
{
        kill(pid, SIGUSR1);
}
void WAIT_CHILD(void)
{
        while (sigflag == 0)
        {
                sigsuspend(&zeromask);
        }
        sigflag = 0;
        if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
        {
                printf("SIG_SETMASK ERROR/n");
                exit(-1);
        }
}
static void charatatime(char* );
int main(int argc, char* argv[])
{
        pid_t pid;
        TELL_WAIT();
        if ((pid = fork()) < 0)
        {
                printf("fork error/n");
                exit(-1);
        }else if (pid == 0){
                WAIT_PARENT();
                charatatime("output from child/n");
        }else{
                charatatime("output from parent/n");
                TELL_CHILD(pid);
        }
        return 0;
}
static void charatatime(char* str)
{
        char* ptr;
        int c;
        setbuf(stdout, NULL);
        for (ptr = str; (c = *ptr++) != 0;) // 无缓冲的标准输出
        {
                putc(c, stdout);
        }
}


/* FileName:ParentAndChildProcessSynchronous.c
   Date:    20100309
   Description: 用信号实现父子进程同步。
*/
#include 
#include 
#include 
#include 
#include 
static volatile sig_atomic_t sigflag;
static sigset_t newmask, oldmask, zeromask;
static void sig_usr(int signo)
{
        sigflag = 1;
}
void TELL_WAIT(void)
{
        if (signal(SIGUSR1, sig_usr) == SIG_ERR)
        {
                printf("signal(SIGUSR1) ERROR /n");
                exit(-1);
        }
        if (signal(SIGUSR2, sig_usr) == SIG_ERR)
        {
                printf("signal(SIGUSR2) ERROR /n");
                exit(-1);
        }
        sigemptyset(&zeromask);
        sigemptyset(&newmask);
        sigaddset(&newmask, SIGUSR1);
        sigaddset(&newmask, SIGUSR2);
        if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)
        {
                printf("SIB_BLOCK ERROR /n");
                exit(-1);
        }
} 
void TELL_PARENT(pid_t pid)
{
        kill(pid, SIGUSR2);
}
void WAIT_PARENT(void)
{
        while (sigflag == 0)
        {
                sigsuspend(&zeromask);
        }
        sigflag = 0;
        if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
        {
                printf("SIG_SETMASK ERROR/n");
                exit(-1);
        }
}
void TELL_CHILD(pid_t pid)
{
        kill(pid, SIGUSR1);
}
void WAIT_CHILD(void)
{
        while (sigflag == 0)
        {
                sigsuspend(&zeromask);
        }
        sigflag = 0;
        if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
        {
                printf("SIG_SETMASK ERROR/n");
                exit(-1);
        }
}
static void charatatime(char* );
int main(int argc, char* argv[])
{
        pid_t pid;
        TELL_WAIT();
        if ((pid = fork()) < 0)
        {
                printf("fork error/n");
                exit(-1);
        }else if (pid == 0){
                WAIT_PARENT();
                charatatime("output from child/n");
        }else{
                charatatime("output from parent/n");
                TELL_CHILD(pid);
        }
        return 0;
}
static void charatatime(char* str)
{
        char* ptr;
        int c;
        setbuf(stdout, NULL);
        for (ptr = str; (c = *ptr++) != 0;) // 无缓冲的标准输出
        {
                putc(c, stdout);
        }
}