[Bug 1437534] [NEW] unstable mktime result

[Filipe Dias]

Public bug reported:

Hi all,

Mktime has different results when using dates that coincide with times
that "didn't" exist due to a change of the reference for the specific
timezone. In the examples I've run, when it's first called, it returns a
past (IMHO invalid) value. After it's called for another date, calling
it again for the first date, returns the expected result.

I found this happens on 1912-01-01 for Europe/Lisbon timezone and
1910-10-01 for Europe/Istanbul and it may be happening on other cases. I
also found a similar case where it doesn't happen, 1940-05-15 for
Europe/Amsterdam.

The tests I made are available here:
https://gist.github.com/fmfdias/5c7c36726ff3cce12ead

Running them:
gcc  test_europe_lisbon_glibc.c -o  test_europe_lisbon_glibc
TZ='Europe/Lisbon' ./test_europe_lisbon_glibc

gcc  test_europe_istanbul_glibc.c -o  test_europe_istanbul_glibc
TZ='Europe/Istanbul' ./test_europe_istanbul_glibc

gcc  test_europe_amsterdam_glibc.c -o  test_europe_amsterdam_glibc
TZ='Europe/Amsterdam' ./test_europe_amsterdam_glibc

Although I run these tests on Ubuntu 14.10, I saw this also happening on
a Ubuntu 12.04 machine.

lsb_release -rd
Description:	Ubuntu 14.10
Release:	14.10

sudo apt-cache policy libc6
libc6:
  Installed: 2.19-10ubuntu2.3
  Candidate: 2.19-10ubuntu2.3
  Version table:
 *** 2.19-10ubuntu2.3 0
        500 http://archive.ubuntu.com/ubuntu/ utopic-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ utopic-security/main amd64 Packages
        100 /var/lib/dpkg/status
     2.19-10ubuntu2 0
        500 http://archive.ubuntu.com/ubuntu/ utopic/main amd64 Packages

Thank you!

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

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https://bugs.launchpad.net/bugs/1437534

Title:
  unstable mktime result

Status in glibc package in Ubuntu:
  New

Bug description:
  Hi all,

  Mktime has different results when using dates that coincide with times
  that "didn't" exist due to a change of the reference for the specific
  timezone. In the examples I've run, when it's first called, it returns
  a past (IMHO invalid) value. After it's called for another date,
  calling it again for the first date, returns the expected result.

  I found this happens on 1912-01-01 for Europe/Lisbon timezone and
  1910-10-01 for Europe/Istanbul and it may be happening on other cases.
  I also found a similar case where it doesn't happen, 1940-05-15 for
  Europe/Amsterdam.

  The tests I made are available here:
  https://gist.github.com/fmfdias/5c7c36726ff3cce12ead

  Running them:
  gcc  test_europe_lisbon_glibc.c -o  test_europe_lisbon_glibc
  TZ='Europe/Lisbon' ./test_europe_lisbon_glibc

  gcc  test_europe_istanbul_glibc.c -o  test_europe_istanbul_glibc
  TZ='Europe/Istanbul' ./test_europe_istanbul_glibc

  gcc  test_europe_amsterdam_glibc.c -o  test_europe_amsterdam_glibc
  TZ='Europe/Amsterdam' ./test_europe_amsterdam_glibc

  Although I run these tests on Ubuntu 14.10, I saw this also happening
  on a Ubuntu 12.04 machine.

  lsb_release -rd
  Description:	Ubuntu 14.10
  Release:	14.10

  sudo apt-cache policy libc6
  libc6:
    Installed: 2.19-10ubuntu2.3
    Candidate: 2.19-10ubuntu2.3
    Version table:
   *** 2.19-10ubuntu2.3 0
          500 http://archive.ubuntu.com/ubuntu/ utopic-updates/main amd64 Packages
          500 http://security.ubuntu.com/ubuntu/ utopic-security/main amd64 Packages
          100 /var/lib/dpkg/status
       2.19-10ubuntu2 0
          500 http://archive.ubuntu.com/ubuntu/ utopic/main amd64 Packages

  Thank you!

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