Manually Update Time Zone Data on Android 10

One of the updates that stops when your carrier decides you have to buy a new phone to keep their profits up is the time zone data, which means as regions decide they will or won’t continue using standard time and will switch permanently to lazy people time (or not), time zone calculations start to fail, which can be awfully annoying when it causes you to miss flights or meetings. It is probably something you’ll want to keep up to date. Unfortunately, this requires root access to your phone because… profits depend on the velocity by which first world money is converted to e-waste to poison third world children. Yay.

Root requires reflashing your device, which means wiping all your data and apps and reinstalling them, so easier to do on a new phone than backing up and restoring and re-configuring all your apps. Sooner or later your vendor will stop supporting your device in an attempt to get you to throw it away and buy a new one and you’ll have to root it to keep it up to date and secure so you might as well do it now, void their stupid warranty, and take control of your device.

You should also take a moment to write your elected representatives and demand that they take civil action against this crap. Lets take a short rant break, shall we?

Planned obsolescence, death by security flaws, and vendor locks should be prosecuted, not just as illegal profiteering but as environmental crimes for needlessly flooding the world with e-waste. If you own a device you have the right to use it as you like and any entity that by omission or obfuscation of reasonable information needed to keep that device operational is depriving legitimate owners of rightful value. Willfully obstructing security updates, knowing full well the risks implied, is coercive if not extortion. Actively blocking the provision of third party services intended to mitigate these harms through barratry and legal extortion should be prosecuted aggressively. Everyone who has purchased a phone that has been intentionally and unfairly life-limited by non-replaceable batteries, intimidation of repair services, manipulation of the spare parts market, or restrictions or obfuscation of security updates is due refund of the value thus denied plus penalties.

Ah, that feels better, no?

Assuming you have a rooted phone, adb installed on your computer, and your TZ data is out of date, lets get it fixed, shall we? The problem is that TZ data comes from IANA, from here actually, and is versioned in a form like 2023c, the current as of now. That’s lovely but the format they provide is not compatible with android and needs to be transformed. Google seems to have some tools for this in the FOSS branch of Android, but it seems a little useless without a virtual environment, a PITA. But the good folks at LineageOS (yay, FOSS!!!) maintain their version of the tool with the thus created output data in their git, which we can use for all android devices (it seems). The files we need are in this directory: note that these are 2023a, but 2023c is identical to 2023a, reverting some changes made in 2023b because, I don’t know, the whole mess about getting up an hour earlier or later being some traumatic experience when it happens twice a year is catastrophic for people’s sense of well being, but when they get up at different times on days off than on work days, that doesn’t count or something. OMG. so drama. people. sometimes it hurts to be associated with them as a species. Not that I care, but stop messing around and just pick one. So many rant triggers in this whole mess.

Anyway, proceeding with the assumption your device is rooted and you have adb installed on your computer, the files needed are:

tzdata        a binary file that if you view with a text editor should start with: tzdata2023a
tzlookup.xml  an xml file that should (nearly) start with: 
tz_version    a simple text file that should have one line: 003.001|2023a|001

Download the compressed .tgz archive of the output_data directory from here by clicking on the [tgz] text at the top right

get the latest IANA time zone data

You should get a .tgz archive, from which you want to extract:

• tzlookup.xml from the android folder
• tzdata from the iana folder
• tz_version from the version folder

Here’s the tricky bit, you gotta get these files to the right places. So I mounted my android on my computer and created a folder TZData in Downloads and copied the files there, this resolved to /data/media/0/Download/TZdata/ on my device. While you’re there, make a folder like oldTZ in the same place for backup. Everything else is done by command line via adb.

(comments are demarked with "#", the prompt is assumed)
# get shell on your device
adb shell
# get root, if this fails, you don't have root, bummer, you don't really own your device.
su root
# verify your tz data is where mine was, if so copypasta should be safe.
find / -name tzdata 2>/dev/null
#output for me looks like some are symlinks
/apex/com.android.tzdata/etc/tz/tzdata
/apex/com.android.tzdata@290000000/etc/tz/tzdata
/apex/com.android.runtime/etc/tz/tzdata
/apex/com.android.runtime@1/etc/tz/tzdata
/system/apex/com.android.runtime.release/etc/tz/tzdata
/system/apex/com.android.tzdata/etc/tz/tzdata
/system/usr/share/zoneinfo/tzdata
# did ya get the same or close enough to figure out what to do next? good.
# Backup your old stuff
cp /system/apex/com.android.tzdata/etc/tz/* /data/media/0/Download/oldTZ
# your directories are read only, so you need to fix that, scary but reversible
mount -o rw,remount /
mount -o rw,remount /apex/com.android.tzdata
mount -o rw,remount /apex/com.android.runtime
# copy the new files over the old files, the last location is legacy and doesn't
# seem to have a copy of tzlookup.xml, so we don't put a new one there, but check
ls /system/usr/share/zoneinfo
# only tzdata and tz_version?  Good.
cp /data/media/0/Download/TZdata/* /apex/com.android.tzdata/etc/tz
cp /data/media/0/Download/TZdata/* /apex/com.android.runtime/etc/tz
cp /data/media/0/Download/TZdata/* /system/apex/com.android.tzdata/etc/tz
cp /data/media/0/Download/TZdata/tz_version /system/usr/share/zoneinfo
cp /data/media/0/Download/TZdata/tzdata /system/usr/share/zoneinfo
# all done, now we just gotta read-only those directories again
mount -o ro,remount /
mount -o ro,remount /apex/com.android.tzdata
mount -o ro,remount /apex/com.android.runtime
# and why not reboot from the command line?
reboot

That was fairly painless once you know what to do and have root, no? it worked for me, my phone rebooted and the time zone database appears to be updated. YMMV, hopefully not the reboot successfully part but bricking a phone is a risk because, you know, profits. After that tz file surgery I created a new event in a US time zone that recently changed their daylight savings to pacify the crazies and it seemed to work as expected.

Time zones correctly set