Re: Compatible fstat()

[Parag Warudkar <kernel-stuff@comcast.net>]

On Nov 8, 2005, at 2:39 PM, Bob Copeland wrote:

> Isn't this just because the device size is > 2**32?  What if you  
> use fseeko(3)
> and #define _FILE_OFFSET_BITS 64?

Yep. I got it to return the correct hard disk size (17Gb) using  
lseek64 and
#define _LARGEFILE64_SOURCE
#define _FILE_OFFSET_BITS 64

Here is what I did
-------------------------------------------------
#define _LARGEFILE64_SOURCE
#define _FILE_OFFSET_BITS 64
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>

int main()
{
        int f;
        off64_t off=0;
        f = open("/dev/hda", O_RDONLY );
        if(f <= 0){
                perror("open");
                exit(0);
        }
        off = lseek64(f, 0, SEEK_SET);
        off = lseek64(f, 0, SEEK_END);
        perror("llseek");
        printf ("Size %lld\n", off);
        close(f);
        return 0;
}



> Okay, still not portable and there is probably a better way that  
> doesn't rely
> on such nonsense.  For example, since you have a minimum size in mind,
> just seek that much and see if it works - you don't really need to  
> know the
> whole disk size for that.  Or figure out the best way on all of  
> your platforms
> and abstract it.

Now this gives me a clue what Ted was referring to as binary search  
in e2fsprogs.
If nothing works this should work portably I guess.

Thanks
Parag 
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