[OpenWrt-Devel] musl libc and timezone

[Gianluca Anzolin]

Hi,

I'm experimenting with the musl libc build, and I'm quite satisfied.

One thing that still bothers me is that the timezone is not working.

Currently the boot scripts in OpenWRT parse /etc/config/system and save the
timezone in /tmp/TZ.

The code in uClibc looks for a TZ variable in the environment and if it doesn't
find it, it tries to read /etc/TZ, a symlink that points to /tmp/TZ and
everything works.

Musl libc however doesn't work this way: it doesn't try to load /etc/TZ.
It looks for a TZ env variable and if it doesn't find it, it resorts to
canonical zoneinfo files. The timezone in /tmp/TZ is ignored.

I cooked up a patch to make musl libc read the /etc/TZ file, however I don't
think this is an efficient solution since it resorts to read data from the
filesystem. A simpler getenv("TZ") wouldn't need to access the fs at all.

So in my opinion the "better" fix would be to populate the TZ environment
variable.

With the current setup I simply added the following line to /etc/profile:

[ -f /tmp/TZ ] && export TZ=$(cat /tmp/TZ)

and now date returns the correct time and timezone.

I however suspect that this fix doesn't work with processes started by procd,
actually I haven't had the time to check.

If that is the case, would there be a way to populate the TZ env variable also
for those processes?

Thank you,

Gianluca
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