Most (not all) JPG, video and MP3 files on a friend's disk appear to be
corrupted, containing only FF characters.

ImageMagick says:

identify: Not a JPEG file: starts with 0xff 0xff `image.jpg' @
error/jpeg.c/JPEGErrorHandler/347.

They were on an external disk. They all seem to have the correct file size.

It's as though the space were reserved for them in a copy operation, but the
actual data didn't make it across, but I don't actually know what happened.

Daniele

On 24 Feb 2022 at 19:27:16 GMT, "D.M. Procida"
<daniele-at-vurt-dot-org@invalid.com> wrote:

> Most (not all) JPG, video and MP3 files on a friend's disk appear to be
> corrupted, containing only FF characters.
>
> ImageMagick says:
>
> identify: Not a JPEG file: starts with 0xff 0xff `image.jpg' @
> error/jpeg.c/JPEGErrorHandler/347.
>
> They were on an external disk. They all seem to have the correct file size.
>
> It's as though the space were reserved for them in a copy operation, but the
> actual data didn't make it across, but I don't actually know what happened.
>
> Daniele

That's ugly.

Given how write operations, er, operate, there's no mechanism for
all-FF's to be written at all. A new file just takes previously-disowned
blocks and then overwrites them with its own data. So unless the whole
disk had been FF beforehand... which I guess is vaguely possible if it
was secure-cleared by something that left FF on there.

What media type? What filesystem? What OS failed to write to it?

Not that knowing is going to help anyone, except to limit those who feel
at risk of the same.

Cheers - Jaimie
--
"It's a very sobering feeling to be up in space and realize
that one's safety factor was determined by the lowest bidder
on a government contract." -- Alan Shepard

On 24 Feb 2022 at 21:13:42 CET, "Jaimie Vandenbergh"
<jaimie@usually.sessile.org> wrote:

> On 24 Feb 2022 at 19:27:16 GMT, "D.M. Procida"
> <daniele-at-vurt-dot-org@invalid.com> wrote:
>
>> Most (not all) JPG, video and MP3 files on a friend's disk appear to be
>> corrupted, containing only FF characters.
>>
>> ImageMagick says:
>>
>> identify: Not a JPEG file: starts with 0xff 0xff `image.jpg' @
>> error/jpeg.c/JPEGErrorHandler/347.
>>
>> They were on an external disk. They all seem to have the correct file size.
>>
>> It's as though the space were reserved for them in a copy operation, but the
>> actual data didn't make it across, but I don't actually know what happened.
>>
>> Daniele
>
> That's ugly.
>
> Given how write operations, er, operate, there's no mechanism for
> all-FF's to be written at all. A new file just takes previously-disowned
> blocks and then overwrites them with its own data. So unless the whole
> disk had been FF beforehand... which I guess is vaguely possible if it
> was secure-cleared by something that left FF on there.
>
> What media type? What filesystem? What OS failed to write to it?

As far as I know - I am several thousand km away from this kit - it's all
Macintosh hardware/format.

> Not that knowing is going to help anyone, except to limit those who feel
> at risk of the same.

It's a teenager's computer, so you can imagine how vague the information is
that I'm getting.

Daniele

D.M. Procida wrote:
> On 24 Feb 2022 at 21:13:42 CET, "Jaimie Vandenbergh"

> It's a teenager's computer, so you can imagine how vague the information is
> that I'm getting.

With any luck, said teenager will learn to keep a proper backup.

--
Graham J

On 24/02/2022 20:13, Jaimie Vandenbergh wrote:
> On 24 Feb 2022 at 19:27:16 GMT, "D.M. Procida"
> <daniele-at-vurt-dot-org@invalid.com> wrote:
>
>> Most (not all) JPG, video and MP3 files on a friend's disk appear to be
>> corrupted, containing only FF characters.
>>
>> ImageMagick says:
>>
>> identify: Not a JPEG file: starts with 0xff 0xff `image.jpg' @
>> error/jpeg.c/JPEGErrorHandler/347.
>>
>> They were on an external disk. They all seem to have the correct file size.
>>
>> It's as though the space were reserved for them in a copy operation, but the
>> actual data didn't make it across, but I don't actually know what happened.
>>
>> Daniele
>
> That's ugly.
>
> Given how write operations, er, operate, there's no mechanism for
> all-FF's to be written at all. A new file just takes previously-disowned
> blocks and then overwrites them with its own data. So unless the whole
> disk had been FF beforehand... which I guess is vaguely possible if it
> was secure-cleared by something that left FF on there.

More likely a head failure or controller failure that's returning all 1s
regardless of what's actually stored.

If the data's really important then a chunky sum of money to a recovery
specialist might get new heads fitted and a reasonable chance of reading
it off.

> What media type? What filesystem? What OS failed to write to it?
>
> Not that knowing is going to help anyone, except to limit those who feel
> at risk of the same.
>
> Cheers - Jaimie

--
Bruce Horrocks
Surrey, England

On 24 Feb 2022 at 21:16:16 GMT, "D.M. Procida"
<daniele-at-vurt-dot-org@invalid.com> wrote:

> On 24 Feb 2022 at 21:13:42 CET, "Jaimie Vandenbergh"
> <jaimie@usually.sessile.org> wrote:
>
>> On 24 Feb 2022 at 19:27:16 GMT, "D.M. Procida"
>> <daniele-at-vurt-dot-org@invalid.com> wrote:
>>
>>> Most (not all) JPG, video and MP3 files on a friend's disk appear to be
>>> corrupted, containing only FF characters.
>>>
>>> ImageMagick says:
>>>
>>> identify: Not a JPEG file: starts with 0xff 0xff `image.jpg' @
>>> error/jpeg.c/JPEGErrorHandler/347.
>>>
>>> They were on an external disk. They all seem to have the correct file size.
>>>
>>> It's as though the space were reserved for them in a copy operation, but the
>>> actual data didn't make it across, but I don't actually know what happened.
>>>
>>> Daniele
>>
>> That's ugly.
>>
>> Given how write operations, er, operate, there's no mechanism for
>> all-FF's to be written at all. A new file just takes previously-disowned
>> blocks and then overwrites them with its own data. So unless the whole
>> disk had been FF beforehand... which I guess is vaguely possible if it
>> was secure-cleared by something that left FF on there.
>>
>> What media type? What filesystem? What OS failed to write to it?
>
> As far as I know - I am several thousand km away from this kit - it's all
> Macintosh hardware/format.
>
>> Not that knowing is going to help anyone, except to limit those who feel
>> at risk of the same.
>
> It's a teenager's computer, so you can imagine how vague the information is
> that I'm getting.

Mmm, yeah.

Probably a write off, but if I was there I'd strip the drive out and try
it in a different USB caddy. I would not hold out much hope since if it
was fake-returning FF's you wouldn't get a directory listing in the
first place. I think the file data almost certainly is trash.

Cheers - Jaimie
--
[Chlorine trifluoride] is also hypergolic with such things as
cloth, wood, and test engineers, not to mention asbestos,
sand, and water -- with which it reacts explosively.
- "Ignition! An Informal History of Liquid Rocket Propellants", J D Clarke