Re: [Freemint-discuss] Mint handling of file timestamps

[Thorsten O. <ad...@th...>]

On Samstag, 11. November 2017 11:02:54 CET Thorsten Otto wrote:
> I think i have to find out what really gets written to the disk there

Ok, did that now. Created a plain FAT image (with mkdosfs), and mounted that 
with -t msdos to /mnt. Result:

$ touch -d "2017-07-15 13:00:00" /mnt/bla
$ ls -l --full-time /mnt/bla
-rwxr-xr-x 1 root root 0 2017-07-15 13:00:00.000000000 +0200 /mnt/bla

$ touch -d "2017-11-05 13:00:00" /mnt/bla 
$ ls -l --full-time /mnt/bla
-rwxr-xr-x 1 root root 0 2017-11-05 13:00:00.000000000 +0100 /mnt/bla

(+0200 was the daylight saving time in effect in July here, +0100 is the
 current timezone offset).

On disk, i get:

00005800: 42 4C 41 20  20 20 20 20  20 20 20 20  00 00 00 00   "BLA 
        ...." 
00005810: 00 00 00 00  00 00 00 60  EF 4A 00 00  00 00 00 00 
  ".......`.J......"

for the first, which is 2017-07-15 12:00:00 when i convert the stamp without 
applying any offset, and

00005800: 42 4C 41 20  20 20 20 20  20 20 20 20  00 00 00 00   "BLA 
        ...." 
00005810: 00 00 00 00  00 00 00 68  65 4B 00 00  00 00 00 00 
  ".......heK......"


for the 2nd, which is 2017-11-05 13:00:00. So it seems linux has the same 
problems, the stamp for the first file (on disk) is off by 1 hour. What 
happens is that:

- touch converts the time i specified to an UTC time, subtracting the offset 
of +0200 that was in effect at that time.
- the kernel adds the current time offset before writing the stamp, because 
for FAT a local time should be stored.

Not very pleasing. That means, if i wait half a year, and daylight savings 
time is in effect again, ls -l will suddenly report a different time.