Bug 10181

Summary:	tzset mishandles version 3 tzdb format
Product:	uClibc	Reporter:	Paul Eggert <eggert>
Component:	Other	Assignee:	unassigned
Status:	NEW ---
Severity:	normal	CC:	uclibc-cvs
Priority:	P5
Version:	unspecified
Target Milestone:	---
Hardware:	All
OS:	All
Host:		Target:
Build:
Attachments:	untested patch to support tzdb version 3 files Patch revised to handle >2 digit hours

Description Paul Eggert 2017-08-07 16:26:16 UTC

Created attachment 7171 [details]
untested patch to support tzdb version 3 files

This bug report responds to the following thread on the tz mailing list:

http://mm.icann.org/pipermail/tz/2017-August/025205.html

The issue is that tzdb version 3 format extends version 2 slightly, in that the POSIX-style TZ strings at the binary-file's end are allowed to have start times that range from -167:59:59 to 167:59:59, instead of the POSIX-specified 00:00:00 through 24:59:59. This is needed to support the predicted future time zone settings for Israel and Western Greenland, which have the following TZ string values in current tzdb:

Asia/Jerusalem 'IST-2IDT,M3.4.4/26,M10.5.0'
America/Godthab '<-03>3<-02>,M3.5.0/-2,M10.5.0/-1'

Although POSIX currently does not require support for these strings, they are widely supported by other C libraries including glibc, and it should be easy to fix uClibc-ng to support them too. Proposed patch attached. I don't use uClibc so I have not tested it.

Comment 1 Paul Eggert 2017-08-07 19:14:43 UTC

Created attachment 7176 [details]
Patch revised to handle >2 digit hours

In rereading that patch I noticed that it allows hour counts only to 99, whereas it should be up to at least 167. While we're at it, let's just increase it to 254; that's just as easy. Revised (and still untested) patch attached.