[TUHS] 2.11BSD cross compiling update

[random832@fastmail.com (Random832)]

On Fri, Jan 13, 2017, at 12:57, Nick Downing wrote:
> I then ended up doing a fair bit of re-engineering, how this came
> about was that I had to port the timezone compiler (zic) to run on the
> Linux cross compilation host, since the goal is eventually to build a
> SIMH-bootable disk (filesystem) with everything on it. This was a bit
> involved, it crashed initially and it turned out it was doing
> localtime() on really small and large values to try to figure out the
> range of years the system could handle. On the Linux system this
> returns NULL for unreasonable time_t values which POSIX allows it to
> do. Hence the crash. It wasn't too obvious how to port this code. (But
> whatever I did, it had to produce the exact same timezone files as a
> native build).

You know that the timezone file format that it uses is still in use
today, right? There's extra data at the end in modern ones for 64-bit
data, but the format itself is cross-platform, with defined field widths
and big-endian byte order.

What do you get when you compare the native built timezone files with
one from your linux host's own zic? It *should* only differ by the
version number in the header [first five bytes "TZif2" vs "TZif"] and
the 64-bit section, if you're giving it the same input files. And I bet
you could take the current version of the code from IANA and, if it
matters to you, remove the parts that output the 64-bit data. If nothing
else, looking at the modern code and the version in 2.11BSD side-by-side
will let you backport bug fixes.

(Note: Technically, the version present in most Linux systems is a fork
maintained with glibc rather than the main version of the code from
IANA)