linux_module_learn/examples/misc-progs/nbtest.c

45 lines
1.2 KiB
C

/*
* 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);
}