nbtest.c

本源码是将述嵌入式LINUX驱动程序例程

/*
 * 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);
}