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exFAT file modification times wrong for files created on Mac OS

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Started by Newbie lutz8471 , 520 Seed Feb 12, 2019 19:35 Replies : 3 View : 733 Likes : 1
(Trying to report a bug, and hoping this is an appropriate forum)

The modification times of files created by Mac OS on exFAT drives are interpreted incorrectly by Android on Samsung devices.

Specifically, a file written to an exFAT drive on Mac OS reports its times correctly on Mac OS, Windows, and Linux, but is skewed 16 hours in the future on Samsung Android devices alone.  Files times are correct for files created by Samsung Android on exFAT devices and used elsewhere, but files created by Mac OS (only) have incorrect times on Samsung Android (only).  This hampers interoperability of exFAT drives on these mobile devices for Mac OS users, and impacts tools like incremental-backup programs.

For more details on this bug, including related screenshots and test details, please see this page:

This bug was verified to exist in Android Nougat and Oreo, and on Samsung J7, S8+, and Note 9 devices.  It occurs only for files written by Mac OS (El Capitan through High Sierra).  Files written to exFAT drives on Windows (7 through 10) have correct times on Samsung Android, and files written by Mac OS have correct times outside Android. 

To recreate the bug: save a file to an exFAT USB drive on Mac OS, and inspect its modification time on Android; it will be incorrect on the latter.
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r.liechty_SDP , Feb 13, 2019 18:10 Post #1 1
I don't think anyone from Engineering will see this post. 

However, maybe another developer will notice this and be able to take advantage of your knowledge.

Samsung Developer Program
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Newbie lutz8471 , 520 Seed Feb 15, 2019 19:58 Post #2 0
Thanks.  Could anyone on this forum suggest a Samsung bug-reporting site to which this could/should be forwarded?  The usual searches are coming up empty, and my parallel post on Android's site has already been rejected as "won't fix, OEM specific" without any forwarding.

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Newbie lutz8471 , 520 Seed Feb 27, 2019 23:41 Post #3 0
An update for anyone stumbling onto this post in the future: this bug was also reported on the Samsung+ app (the US equivalent of Samsung Members).  It was also later discovered that Samsung Android devices sometimes _write_ files to exFAT drives with incorrect modification times that show up as -16 hours off on both Mac OS and Windows.

I.e., it's not just reads, and not just Mac OS content. This bug may stem from the fact that Android timestamps were broken in general until Oreo, but really should be fixed today. See the link in the original post above for more details.

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