Re: bug in kernel

[linux-os]

On Mon, 14 Mar 2005, Evgeniy wrote:

> Here is a simple program.
>
> #include <stdio.h>
> #include <errno.h>
> main(){
>  int err;
>  err=read(0,NULL,6);
>  printf("%d %d\n",err,errno);
> }
>
> I think that it should be an error : Null pointer assignment, like in windows.
> But in practise it is not so.

It is an error. It will wait <forever> until you enter the [Enter]
key (it's reading from STDIN_FILENO). Then it will return -1 which
means there was an error, the error code in errno is 14 (EFAULT)
or "bad address".

You can configure user-mode code to "seg-fault" upon receiving
such an error. It can print a nasty message and leave a worthless
core file in your directory.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.11 on an i686 machine (5537.79 BogoMips).
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