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Apple Photos app corrupts images

(tenderlovemaking.com)
1119 points pattyj | 3 comments | 17 Sep 25 11:07 UTC | HN request time: 0.082s | source
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billyjobob ◴[17 Sep 25 11:42 UTC] No.45274565[source]▶
He says the checksums are different but he doesn’t provide a diff to show how different. It could just be a single flipped bit or something. And that could happen in his own RAM/disk/CPU/router so seems premature to immediately blame Apple.
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tenderlove ◴[17 Sep 25 12:03 UTC] No.45274786[source]▶
Here you go!

  https://gist.github.com/tenderlove/25853f50ab46a58738ff2cc22d682f2b
I ran both files through xxd then diffed them. I've literally changed every piece of hardware (at no small cost). "premature to immediately blame Apple" seems a bit off.
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1. jjcob ◴[17 Sep 25 12:57 UTC] No.45275294{3}[source]▶
I tried running the file segments through a binary diff with Hex Fiend

As far as I can tell:

- 0x7800 bytes were replaced at file offset 0x00aa0000

- 0x2200 bytes were replaced at file offset 0x00aa8000

I can't tell if the replacement data came from a different part of the file, or somewhere totally different. Race condition somewhere sounds plausible.

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2. nickcw ◴[17 Sep 25 15:17 UTC] No.45276881[source]▶
gcd(0x2200,0x7800) = 512

So some part of the chain with 512 byte buffer size corrupted the data.

It doesn't look like a memory corruption but if this were my computer I'd run the equivalent of memtest86 on it.

It looks like a filing system corruption to me. Running `diskutil info` on the main harddisk and the sd card might be interesting to see if the block sizes match.

Running a disk tester on the sd card and the main disk might be a good idea too. Here is one I wrote: https://github.com/ncw/stressdisk

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3. borisgolovnev ◴[18 Sep 25 08:02 UTC] No.45286874[source]▶
It's a shame APFS does nothing to ensure file integrity.