/* * asynctest.c: use async notification to read stdin * * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet * Copyright (C) 2001 O'Reilly & Associates * * The source code in this file can be freely used, adapted, * and redistributed in source or binary form, so long as an * acknowledgment appears in derived source files.  The citation * should list that the code comes from the book "Linux Device * Drivers" by Alessandro Rubini and Jonathan Corbet, published * by O'Reilly & Associates.   No warranty is attached; * we cannot take responsibility for errors or fitness for use. */#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <signal.h>#include <fcntl.h>int gotdata=0;void sighandler(int signo){    if (signo==SIGIO)        gotdata++;    return;}char buffer[4096];int main(int argc, char **argv){    int count;    struct sigaction action;    memset(&action, 0, sizeof(action));    action.sa_handler = sighandler;    action.sa_flags = 0;    sigaction(SIGIO, &action, NULL);    fcntl(STDIN_FILENO, F_SETOWN, getpid());    fcntl(STDIN_FILENO, F_SETFL, fcntl(STDIN_FILENO, F_GETFL) | FASYNC);    while(1) {        /* this only returns if a signal arrives */        sleep(86400); /* one day */        if (!gotdata)            continue;        count=read(0, buffer, 4096);        /* buggy: if avail data is more than 4kbytes... */        write(1,buffer,count);        gotdata=0;    }}