Re: 64 Bits from Larry McVoy

Oleg Kibirev (snowcat@netgate.net)
Mon, 04 Nov 1996 19:43:34 -0800

Jim Nance wrote:
> Well Larry,
> I was almost sure you were wrong, so I wrote the following test program.
> Unfortunatly, I did manage to tickle enough linux bugs so that you can
> claim you are right :-) So instead of claiming victory, I will submit
> a bug report :-( For those intrested in reproducing this, I am running
> Redhat 4.0 with redhats kernel, and the partition I am working contains an
> 800MB ext2 file system. Here is the program. It tries to make a large
> sparse file:
>
>
> int main()
> {
> off_t offset;
> int fd = open("bigfile", O_CREAT|O_TRUNC|O_WRONLY);
>

An open with O_CREAT should have a mode (for example 0666) as the 3rd
argument. If it's omitted, the call with usually pick up some garbage
from the stack and use it as file's permissions.

So, unlike the printk, this is program's rather than system bug.

> The first thing to notice is that I have divided GB by 2. If I don't do
> this the program fails after making a 1G file, and I get a nice printk()
> from the ext2fs. So I divided by two and reran. Now I can make a very
> large file, but something is still wrong:
>
> total 76
> -rwxrwxrwx 1 jlnance users 14378 Nov 4 07:39 a.out*
> -rw-rw-rw- 1 jlnance users 544 Nov 4 07:38 big.c
> -r-xrwS--T 1 jlnance users 10200547329 Nov 4 07:43 bigfile*
> 

-- 
 _.    	        _       .  
(_ ,_  _ ,  .  / ` _ _L	 | Email: Oleg Kibirev <snowcat@netgate.net>
._)| U(_)\/\/  \_,(_L/L  | Visit
http://math.math.CSUFresno.EDU/~oleg/math.html
------------------------'  to get my programs + PGP public key