[Bug 1587128] [NEW] zdump returns incorrect transitions for Africa/Casablanca and Africa/El_Aaiun

Philip Ross phil.ross at gmail.com
Mon May 30 16:09:12 UTC 2016 

Public bug reported:

Ubuntu 16.04 LTS amd64
libc-bin 2.23-0ubuntu3
tzdata 2016d-0ubuntu0.16.04

The Africa/Casablanca and Africa/El_Aaiun time zones in the 2016d-
0ubuntu0.16.04 tzdata package have transitions from daylight savings to
standard time at 02:00 UTC on 2037-10-04 (see
https://github.com/eggert/tz/blob/2016d/africa#L892).

The time zone files (/usr/share/zoneinfo/Africa/Casablanca and
/usr/share/zoneinfo/Africa/El_Aaiun) both contain the correct transition
time (Unix timestamp 0x7f72de20) in the 32-bit and 64-bit sections:

$ hd -s 0x1b8 -n 4 /usr/share/zoneinfo/Africa/Casablanca
000001b8  7f 72 de 20                                       |.r. |
000001bc

$ hd -s 0x59d -n 8 /usr/share/zoneinfo/Africa/Casablanca
0000059d  00 00 00 00 7f 72 de 20                           |.....r. |
000005a5

$ hd -s 0x18c -n 4 /usr/share/zoneinfo/Africa/El_Aaiun
0000018c  7f 72 de 20                                       |.r. |
00000190

$ hd -s 0x506 -n 8 /usr/share/zoneinfo/Africa/El_Aaiun
00000506  00 00 00 00 7f 72 de 20                           |.....r. |
0000050e

However zdump (from libc-bin 2.23-0ubuntu3) incorrectly shows that the
transitions for both time zones occur on 2037-10-25 instead of
2037-10-04:

$ zdump -v -c 2037,2038 /usr/share/zoneinfo/Africa/Casablanca | grep Oct
/usr/share/zoneinfo/Africa/Casablanca  Sun Oct 25 01:59:59 2037 UT = Sun Oct 25 02:59:59 2037 WEST isdst=1 gmtoff=3600
/usr/share/zoneinfo/Africa/Casablanca  Sun Oct 25 02:00:00 2037 UT = Sun Oct 25 02:00:00 2037 WET isdst=0 gmtoff=0

$ zdump -v -c 2037,2038 /usr/share/zoneinfo/Africa/El_Aaiun | grep Oct
/usr/share/zoneinfo/Africa/El_Aaiun  Sun Oct 25 01:59:59 2037 UT = Sun Oct 25 02:59:59 2037 WEST isdst=1 gmtoff=3600
/usr/share/zoneinfo/Africa/El_Aaiun  Sun Oct 25 02:00:00 2037 UT = Sun Oct 25 02:00:00 2037 WET isdst=0 gmtoff=0

The copy of zdump.c released with glibc 2.23 is identical to zdump.c in
the tzcode2015g release from the IANA Timezone Database
(https://www.iana.org/time-
zones/repository/releases/tzcode2015g.tar.gz).

I have compiled the IANA Timezone Database 2015g version of zdump with
the default options and it produces the correct results for the Ubuntu-
distributed Africa/Casablanca and Africa/El_Aaiun time zone files:

$ ~/tz/2015g/zdump --version
zdump (tzcode) 2015g

$ ~/tz/2015g/zdump -v -c 2037,2038 /usr/share/zoneinfo/Africa/Casablanca | grep Oct
/usr/share/zoneinfo/Africa/Casablanca  Sun Oct  4 01:59:59 2037 UT = Sun Oct  4 02:59:59 2037 WEST isdst=1 gmtoff=3600
/usr/share/zoneinfo/Africa/Casablanca  Sun Oct  4 02:00:00 2037 UT = Sun Oct  4 02:00:00 2037 WET isdst=0 gmtoff=0

$ ~/tz/2015g/zdump -v -c 2037,2038 /usr/share/zoneinfo/Africa/El_Aaiun | grep Oct
/usr/share/zoneinfo/Africa/El_Aaiun  Sun Oct  4 01:59:59 2037 UT = Sun Oct  4 02:59:59 2037 WEST isdst=1 gmtoff=3600
/usr/share/zoneinfo/Africa/El_Aaiun  Sun Oct  4 02:00:00 2037 UT = Sun Oct  4 02:00:00 2037 WET isdst=0 gmtoff=0

** Affects: glibc (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1587128

Title:
  zdump returns incorrect transitions for Africa/Casablanca and
  Africa/El_Aaiun

Status in glibc package in Ubuntu:
  New

Bug description:
  Ubuntu 16.04 LTS amd64
  libc-bin 2.23-0ubuntu3
  tzdata 2016d-0ubuntu0.16.04

  The Africa/Casablanca and Africa/El_Aaiun time zones in the 2016d-
  0ubuntu0.16.04 tzdata package have transitions from daylight savings
  to standard time at 02:00 UTC on 2037-10-04 (see
  https://github.com/eggert/tz/blob/2016d/africa#L892).

  The time zone files (/usr/share/zoneinfo/Africa/Casablanca and
  /usr/share/zoneinfo/Africa/El_Aaiun) both contain the correct
  transition time (Unix timestamp 0x7f72de20) in the 32-bit and 64-bit
  sections:

  $ hd -s 0x1b8 -n 4 /usr/share/zoneinfo/Africa/Casablanca
  000001b8  7f 72 de 20                                       |.r. |
  000001bc

  $ hd -s 0x59d -n 8 /usr/share/zoneinfo/Africa/Casablanca
  0000059d  00 00 00 00 7f 72 de 20                           |.....r. |
  000005a5

  $ hd -s 0x18c -n 4 /usr/share/zoneinfo/Africa/El_Aaiun
  0000018c  7f 72 de 20                                       |.r. |
  00000190

  $ hd -s 0x506 -n 8 /usr/share/zoneinfo/Africa/El_Aaiun
  00000506  00 00 00 00 7f 72 de 20                           |.....r. |
  0000050e

  However zdump (from libc-bin 2.23-0ubuntu3) incorrectly shows that the
  transitions for both time zones occur on 2037-10-25 instead of
  2037-10-04:

  $ zdump -v -c 2037,2038 /usr/share/zoneinfo/Africa/Casablanca | grep Oct
  /usr/share/zoneinfo/Africa/Casablanca  Sun Oct 25 01:59:59 2037 UT = Sun Oct 25 02:59:59 2037 WEST isdst=1 gmtoff=3600
  /usr/share/zoneinfo/Africa/Casablanca  Sun Oct 25 02:00:00 2037 UT = Sun Oct 25 02:00:00 2037 WET isdst=0 gmtoff=0

  $ zdump -v -c 2037,2038 /usr/share/zoneinfo/Africa/El_Aaiun | grep Oct
  /usr/share/zoneinfo/Africa/El_Aaiun  Sun Oct 25 01:59:59 2037 UT = Sun Oct 25 02:59:59 2037 WEST isdst=1 gmtoff=3600
  /usr/share/zoneinfo/Africa/El_Aaiun  Sun Oct 25 02:00:00 2037 UT = Sun Oct 25 02:00:00 2037 WET isdst=0 gmtoff=0

  The copy of zdump.c released with glibc 2.23 is identical to zdump.c
  in the tzcode2015g release from the IANA Timezone Database
  (https://www.iana.org/time-
  zones/repository/releases/tzcode2015g.tar.gz).

  I have compiled the IANA Timezone Database 2015g version of zdump with
  the default options and it produces the correct results for the
  Ubuntu-distributed Africa/Casablanca and Africa/El_Aaiun time zone
  files:

  $ ~/tz/2015g/zdump --version
  zdump (tzcode) 2015g

  $ ~/tz/2015g/zdump -v -c 2037,2038 /usr/share/zoneinfo/Africa/Casablanca | grep Oct
  /usr/share/zoneinfo/Africa/Casablanca  Sun Oct  4 01:59:59 2037 UT = Sun Oct  4 02:59:59 2037 WEST isdst=1 gmtoff=3600
  /usr/share/zoneinfo/Africa/Casablanca  Sun Oct  4 02:00:00 2037 UT = Sun Oct  4 02:00:00 2037 WET isdst=0 gmtoff=0

  $ ~/tz/2015g/zdump -v -c 2037,2038 /usr/share/zoneinfo/Africa/El_Aaiun | grep Oct
  /usr/share/zoneinfo/Africa/El_Aaiun  Sun Oct  4 01:59:59 2037 UT = Sun Oct  4 02:59:59 2037 WEST isdst=1 gmtoff=3600
  /usr/share/zoneinfo/Africa/El_Aaiun  Sun Oct  4 02:00:00 2037 UT = Sun Oct  4 02:00:00 2037 WET isdst=0 gmtoff=0

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