int main(int argc, char ** argv) {
//初始化两个信号集，一个只有usr1，一个只有usr2
sigemptyset(&t_sigset_usr);
sigemptyset(&t_sigset_old);
sigemptyset(&t_sigset_zero);
sigaddset(&t_sigset_usr, SIGUSR1);
sigaddset(&t_sigset_usr, SIGUSR2);
//注册信号处理程序，
signal(SIGUSR1, do_sig_usr);
signal(SIGUSR2, do_sig_usr);
//父进程阻塞usr信号
sigprocmask(SIG_SETMASK, &t_sigset_usr, NULL );
pid_t child_pid;
//父进程fork一个子进程出来
child_pid = fork();
if (child_pid == 0) {
//子进程,从2开始写
num = 2;
//注册信号处理程序，
signal(SIGUSR1, do_sig_usr);
signal(SIGUSR2, do_sig_usr);
//子进程阻塞usr信号
sigprocmask(SIG_SETMASK, &t_sigset_usr, NULL );
//子进程准备完毕，通知父进程去写
tell_parent();
while (1) {
//始终等待父进程唤醒
wait_parent();
write_num_to_file();
tell_parent();
}
} else {
//父进程
while (1) {
//始终等待子进程唤醒
wait_child();
write_num_to_file();
tell_child(child_pid);
}
}
//子进程写入数据，并且告知父进程，然后投入睡眠，等待父进程唤醒
//父进程等待子进程
exit(0);
}
int gpio_export(int pin)
{
if (write_num_to_file("/sys/class/gpio/export", pin))
{
CATERR("Failed to open GPIO export for writing\n");
return -1;
}
return 0;
}
int gpio_write(int pin, int val)
{
char path[256];
snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin);
if (write_num_to_file(path, val))
{
CATERR("Failed to open GPIO export for writing\n");
return -1;
}
return 0;
}
