Some read-errors on floppys not reported on 2.4.22

Some read-errors on floppys not reported on 2.4.22

[Richard B. Johnson]

Given the following program:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
int main()
{
    int fd;
    char buf[0x1000];
    if((fd = open("/dev/fd0", O_RDONLY)) < 0)
    {
        perror("open");
        exit(EXIT_FAILURE);
    }
    while(read(fd, buf, sizeof(buf)) > 0)
        ;
    perror("read");
    close(fd);
    return 0;
}

This program will return:

Script started on Fri Aug 29 12:05:32 2003
# ./xxx
read: Success
# exit
exit

Script done on Fri Aug 29 12:05:51 2003

Success, even where there are lots of CRC errors that
prematurely terminate the read:

end_request: I/O error, dev 02:00 (floppy), sector 101
floppy0: data CRC error: track 2, head 1, sector 12, size 2
floppy0: data CRC error: track 2, head 1, sector 12, size 2
end_request: I/O error, dev 02:00 (floppy), sector 101
floppy0: data CRC error: track 3, head 1, sector 3, size 2
floppy0: data CRC error: track 3, head 1, sector 3, size 2
end_request: I/O error, dev 02:00 (floppy), sector 128
floppy0: data CRC error: track 2, head 1, sector 12, size 2
floppy0: data CRC error: track 2, head 1, sector 12, size 2
end_request: I/O error, dev 02:00 (floppy), sector 101


This is NotGood(tm); A program may think it got all the
data, from a floppy when, in fact it wasn't able to read
more than a few sectors.


Cheers,
Dick Johnson
Penguin : Linux version 2.4.22 on an i686 machine (794.73 BogoMips).
            Note 96.31% of all statistics are fiction.

Re: Some read-errors on floppys not reported on 2.4.22

[Pavel Machek]

Hi!

> Success, even where there are lots of CRC errors that
> prematurely terminate the read:

Can you find out if it works in 2.4.21?
-- 
				Pavel
Written on sharp zaurus, because my Velo1 broke. If you have Velo you don't need...

Re: Some read-errors on floppys not reported on 2.4.22

[Richard B. Johnson]

On Thu, 4 Sep 2003, Pavel Machek wrote:

> Hi!
>
> > Success, even where there are lots of CRC errors that
> > prematurely terminate the read:
>
> Can you find out if it works in 2.4.21?
> --
> 				Pavel
> Written on sharp zaurus, because my Velo1 broke. If you have Velo you don't need...
>

I will try and get back to you. I was not able to even boot
2.4.21 on my system because there were problems with aic7xxx
SCSI disk controller so I gave up. I will mix/match and see
what I can find.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.22 on an i686 machine (794.73 BogoMips).
            Note 96.31% of all statistics are fiction.

Re: Some read-errors on floppys not reported on 2.4.22

[Richard B. Johnson]

On Thu, 4 Sep 2003, Pavel Machek wrote:

> Hi!
>
> > Success, even where there are lots of CRC errors that
> > prematurely terminate the read:
>
> Can you find out if it works in 2.4.21?
> --
> 				Pavel

Okay. It works on 2.4.21, the code is identical to 2.4.20 which also
works. On 2.4.22, bad CRC errors which terminate the read, don't
always result in a bad return code. Some just return 0, which
is treated like EOF in user-mode code. Application software
has to add a call to fstat() to see if the bytes read were equal
to the file size as a work-around. This step should not be required.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.22 on an i686 machine (794.73 BogoMips).
            Note 96.31% of all statistics are fiction.