[Bug libc/5186] New: localtime does not handle changed /etc/localtime

[Bug libc/5186] New: localtime does not handle changed /etc/localtime

[adi at hexapodia dot org]

Running "2.3.6.ds1-8" from Debian unstable on x86_64, libc does not seem to
correctly update its idea of localtime when /etc/localtime changes.

adi@xxxxx:~/tmp$ cat localtime-relink.c
#include <time.h>
#include <stdio.h>
#include <stdlib.h>

int main(void)
{
    char b1[40], b2[40];
    time_t t;
    struct tm tm1, tm2;

    system("ln -snf /usr/share/zoneinfo/PST8PDT /etc/localtime");
    system("ls -l /etc/localtime");

    t = 1192516347;
    strftime(b1, sizeof(b1), "%F %T %Z", localtime_r(&t, &tm1));

    system("ln -snf /usr/share/zoneinfo/EST5EDT /etc/localtime");
    system("ls -l /etc/localtime");

    t = 1192516347;
    strftime(b2, sizeof(b2), "%F %T %Z", localtime_r(&t, &tm2));

    printf("b1 = %s\n", b1);
    printf("b2 = %s\n", b2);

    return 0;
}
adi@xxxxx:~/tmp$ cc -Wall -g localtime-relink.c
adi@xxxxx:~/tmp$ sudo ./a.out
lrwxrwxrwx 1 root root 27 2007-10-15 23:56 /etc/localtime ->
/usr/share/zoneinfo/PST8PDT
lrwxrwxrwx 1 root root 27 2007-10-16 02:56 /etc/localtime ->
/usr/share/zoneinfo/EST5EDT
b1 = 2007-10-15 23:32:27 PDT
b2 = 2007-10-15 23:32:27 PDT

Note that the ls output does have the proper timezone offset, but the two calls
to localtime_r return the same 'struct tm' values.  Inspecting with gdb shows
that all fields are the same.

-- 
           Summary: localtime does not handle changed /etc/localtime
           Product: glibc
           Version: 2.3.6
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: adi at hexapodia dot org
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=5186

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[Bug libc/5186] localtime does not handle changed /etc/localtime

[adi at hexapodia dot org]

------- Additional Comments From adi at hexapodia dot org  2007-10-16 08:01 -------
(In reply to comment #0)
> Running "2.3.6.ds1-8" from Debian unstable on x86_64, libc does not seem to
> correctly update its idea of localtime when /etc/localtime changes.

Note that this is reproducable even with an empty environment.

adi@xxxxx:~/tmp$ sudo env -i env
adi@xxxxx:~/tmp$ sudo env -i ./a.out
lrwxrwxrwx 1 root root 27 Oct 16 01:00 /etc/localtime -> /usr/share/zoneinfo/PST8PDT
lrwxrwxrwx 1 root root 27 Oct 16 04:00 /etc/localtime -> /usr/share/zoneinfo/EST5EDT
b1 = 2007-10-15 23:32:27 PDT
b2 = 2007-10-15 23:32:27 PDT


-- 


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[Bug libc/5186] localtime does not handle changed /etc/localtime

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2007-10-17 20:23 -------
Your test case is wrong since localtime_r does not have to (nor should)
implicitly call tzset.  That's necessary to enable parallelism.

But there was a problem with using localtime after a file change.  This is now
fixed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://sourceware.org/bugzilla/show_bug.cgi?id=5186

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[Bug libc/5186] localtime does not handle changed /etc/localtime

[dhinakaran dot k at lntemsys dot com]

------- Additional Comments From dhinakaran dot k at lntemsys dot com  2007-12-14 09:09 -------
Drepper,
(In reply to comment #2)
> Your test case is wrong since localtime_r does not have to (nor should)
> implicitly call tzset.  That's necessary to enable parallelism.
> But there was a problem with using localtime after a file change.  This is 
now
> fixed.

  Looks like, its a problem with localtime() even. 

Can I know, from which version on, localtime() can handle change 
in /etc/localtime. 

Thanks
dhina

-- 


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