/* * nbtest.c: read and write in non-blocking mode * This should run with any Unix * * 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 <unistd.h>#include <fcntl.h>#include <stdlib.h>#include <errno.h>char buffer[4096];int main(int argc, char **argv){	int delay = 1, n, m = 0;	if (argc > 1)		delay=atoi(argv[1]);	fcntl(0, F_SETFL, fcntl(0,F_GETFL) | O_NONBLOCK); /* stdin */	fcntl(1, F_SETFL, fcntl(1,F_GETFL) | O_NONBLOCK); /* stdout */	while (1) {		n = read(0, buffer, 4096);		if (n >= 0)			m = write(1, buffer, n);		if ((n < 0 || m < 0) && (errno != EAGAIN))			break;		sleep(delay);	}	perror(n < 0 ? "stdin" : "stdout");	exit(1);}