[Bug 1437534] Re: unstable mktime result

[Andor Rozsnyai]

I had the I think the same problem with mktime().
(Ubuntu EGLIBC 2.19-0ubuntu6.8) 2.19

With input data:
struct tm   testtime = {0};
    testtime.tm_year=10;
    testtime.tm_mon=0;
    testtime.tm_mday=1;
    testtime.tm_hour=0;
    testtime.tm_min=0;
    testtime.tm_sec=0;

mktime(t)	int	-1893459600	for "Europe/Budapest"
mktime(t)	int	-1893456000	for "Europe/London"
mktime(t)	int	-1893462264 ???	for "Europe/Bucharest"  

for 
struct tm   testtime = {0};
    testtime.tm_year=50;
    testtime.tm_mon=0;
    testtime.tm_mday=1;
    testtime.tm_hour=0;
    testtime.tm_min=0;
    testtime.tm_sec=0;

mktime(t)	int	-631155600	for "Europe/Budapest"
mktime(t)	int	-631152000	for "Europe/London"
mktime(t)	int	-631159200	for "Europe/Bucharest"
mktime(t)	int	-631134000	for "America/Nipigon"

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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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