[완료] getchar() 함수에서 대기중일 때 키보드 입력 말고 해제하는 방법이 있을까요?

#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <termios.h>
#include <fcntl.h>
#include <unistd.h>
#include <pthread.h>
 
static int poll_getch[2] = {-1, -1};
 
void cancel_getch(void)
{
        int fd = poll_getch[0];
        if (fd >= 0)
                write(poll_getch[1], &fd, 1);
}
 
int getch(void)
{
        int fd_cancel = poll_getch[0];
        int fd_stdin = fileno(stdin);
        int ch = -1;
 
        struct termios org_term, new_term;
        tcgetattr(fd_stdin, &org_term);
        new_term = org_term;
        new_term.c_lflag &= ~(ICANON | ECHO);
        new_term.c_cc[VTIME] = 0;
        new_term.c_cc[VMIN] = 1;
        tcsetattr(fd_stdin, TCSANOW, &new_term);
 
        fd_set rdfds;
        FD_ZERO(&rdfds);
        FD_SET(fd_stdin, &rdfds);
        FD_SET(fd_cancel, &rdfds);
 
        int max_fd = fd_stdin > fd_cancel ? fd_stdin : fd_cancel;
        int r = select(max_fd + 1, &rdfds, NULL, NULL, NULL);
        if (r > 0 && FD_ISSET(fd_stdin, &rdfds))
                ch = getchar();
 
        tcsetattr(fd_stdin, TCSANOW, &org_term);
 
        return ch;
}
 
void *test_timer(void *arg)
{
        sleep(5);
        cancel_getch();
        return NULL;
}
 
int main(int argc, char **argv)
{
        if (pipe(poll_getch) < 0) {
                perror("pipe");
                return 1;
        }
 
        pthread_t test;
        pthread_create(&test, NULL, test_timer, NULL);
 
        while (1) {
                int ch = getch();
                if (ch < 0) {
                        printf("canceled\n");
                        break;
                }
                printf("ch:%x\n", ch);
        }
 
        return 0;
}