DST problem on Win32 not fully resolved in perl 5.34 #20061

blues1875 · 2022-08-07T18:15:38Z

Description
b277e76 was introduced to fix a long-standing problem with Daylight Savings Time on Win32 (#6080). The fix was successful in some combinations of time and time zone, but introduced problems in others. These symptoms are seen in the time zones shown with perl 5.32.0 and 5.34.0 on Windows 10:

Steps to Reproduce
The following code in three files:
stat_test.pl

my $mtime = 0;
utime $mtime, $mtime, 'stat_test.pl';
printf "%s\n", scalar gmtime ((stat 'stat_test.pl')[9]);

stat_test.bat

@echo off
tzutil /s "UTC"
echo (UTC) Co-ordinated Universal Time
call sub.bat

tzutil /s "Greenland Standard Time"
echo (UTC-03:00) Greenland
call sub.bat

tzutil /s "E. South America Standard Time"
echo (UTC-03:00) Brasilia
call sub.bat

tzutil /s "Turkey Standard Time"
echo  (UTC+03:00) Istanbul
call sub.bat

tzutil /s "E. Australia Standard Time"
echo  (UTC+10:00) Brisbane
call sub.bat

sub.bat

@echo off
echo | set /p="5.32: "
5.32\perl-5.32.0\perl stat_test.pl
echo | set /p="5.34: "
5.34\perl-5.34.0\perl stat_test.pl
echo --------------------------------

Observed behavior

(UTC) Co-ordinated Universal Time
5.32: Thu Jan  1 00:00:00 1970
5.34: Thu Jan  1 00:00:00 1970
--------------------------------
(UTC-03:00) Greenland
5.32: Wed Dec 31 23:59:59 1969
5.34: Thu Jan  1 00:00:00 1970
--------------------------------
(UTC-03:00) Brasilia
5.32: Wed Dec 31 23:59:59 1969
5.34: Thu Jan  1 01:00:00 1970
--------------------------------
 (UTC+03:00) Istanbul
5.32: Thu Jan  1 00:00:00 1970
5.34: Wed Dec 31 23:59:59 1969
--------------------------------
 (UTC+10:00) Brisbane
5.32: Thu Jan  1 00:00:00 1970
5.34: Thu Jan  1 00:00:00 1970
--------------------------------

When the variable $mtime is changed like this:

my $mtime = 10957 * 24 * 60 * 60;

the observed output is:

(UTC) Co-ordinated Universal Time
5.32: Sat Jan  1 00:00:00 2000
5.34: Sat Jan  1 00:00:00 2000
--------------------------------
(UTC-03:00) Greenland
5.32: Sat Jan  1 00:00:00 2000
5.34: Sat Jan  1 00:00:00 2000
--------------------------------
(UTC-03:00) Brasilia
5.32: Sat Jan  1 00:00:00 2000
5.34: Sat Jan  1 01:00:00 2000
--------------------------------
 (UTC+03:00) Istanbul
5.32: Sat Jan  1 00:00:00 2000
5.34: Fri Dec 31 23:00:00 1999
--------------------------------
 (UTC+10:00) Brisbane
5.32: Sat Jan  1 00:00:00 2000
5.34: Sat Jan  1 00:00:00 2000
--------------------------------

Expected behavior

5.32: Thu Jan  1 00:00:00 1970
5.34: Thu Jan  1 00:00:00 1970

and

5.32: Sat Jan  1 00:00:00 2000
5.34: Sat Jan  1 00:00:00 2000

Perl configuration

Summary of my perl5 (revision 5 version 36 subversion 0) configuration:

  Platform:
    osname=MSWin32
    osvers=10.0.19044.1826
    archname=MSWin32-x64-multi-thread
    uname=''
    config_args='undef'
    hint=recommended
    useposix=true
    d_sigaction=undef
    useithreads=define
    usemultiplicity=define
    use64bitint=define
    use64bitall=undef
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
  Compiler:
    cc='gcc'
    ccflags =' -DWIN32 -DWIN64  -DPERL_TEXTMODE_SCRIPTS -DMULTIPLICITY -DPERL_IMPLICIT_SYS -DUSE_PERLIO -D__USE_MINGW_ANSI_STDIO -fwrapv -fno-strict-aliasing -mms-bitfields'
    optimize='-O2'
    cppflags='-DWIN32'
    ccversion=''
    gccversion='8.3.0'
    gccosandvers=''
    intsize=4
    longsize=4
    ptrsize=8
    doublesize=8
    byteorder=12345678
    doublekind=3
    d_longlong=define
    longlongsize=8
    d_longdbl=define
    longdblsize=16
    longdblkind=3
    ivtype='long long'
    ivsize=8
    nvtype='double'
    nvsize=8
    Off_t='long long'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='g++'
    ldflags ='-s -L"C:\Users\Glenn\Apps\Strawberry\perl\lib\CORE" -L"C:\Users\Glenn\Apps\Strawberry\c\lib" -L"C:\Users\Glenn\Apps\Strawberry\c\x86_64-w64-mingw32\lib" -L"C:\Users\Glenn\Apps\Strawberry\c\lib\gcc\x86_64-w64-mingw32\8.3.0"'
    libpth=C:\Users\Glenn\Apps\Strawberry\c\lib C:\Users\Glenn\Apps\Strawberry\c\x86_64-w64-mingw32\lib C:\Users\Glenn\Apps\Strawberry\c\lib\gcc\x86_64-w64-mingw32\8.3.0
    libs= -lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    perllibs= -lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    libc=
    so=dll
    useshrplib=true
    libperl=libperl536.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs
    dlext=dll
    d_dlsymun=undef
    ccdlflags=' '
    cccdlflags=' '
    lddlflags='-shared -s -L"C:\Users\Glenn\Apps\Strawberry\perl\lib\CORE" -L"C:\Users\Glenn\Apps\Strawberry\c\lib" -L"C:\Users\Glenn\Apps\Strawberry\c\x86_64-w64-mingw32\lib" -L"C:\Users\Glenn\Apps\Strawberry\c\lib\gcc\x86_64-w64-mingw32\8.3.0"'


Characteristics of this binary (from libperl):
  Compile-time options:
    HAS_TIMES
    HAVE_INTERP_INTERN
    MULTIPLICITY
    PERLIO_LAYERS
    PERL_COPY_ON_WRITE
    PERL_DONT_CREATE_GVSV
    PERL_IMPLICIT_SYS
    PERL_MALLOC_WRAP
    PERL_OP_PARENT
    PERL_PRESERVE_IVUV
    USE_64_BIT_INT
    USE_ITHREADS
    USE_LARGE_FILES
    USE_LOCALE
    USE_LOCALE_COLLATE
    USE_LOCALE_CTYPE
    USE_LOCALE_NUMERIC
    USE_LOCALE_TIME
    USE_PERLIO
    USE_PERL_ATOF
  Built under MSWin32
  Compiled at Jul 17 2022 15:30:54

The text was updated successfully, but these errors were encountered:

Conversion to local time seems unnecessary and it apparently causes issues with DST. Fixes Perl#20018, Perl#20061

xenu · 2022-08-07T23:00:35Z

This PR should fix it: #20064

blues1875 · 2022-08-08T18:44:13Z

Excellent, @xenu! That fixed it for me. Applying your fix to blead gave me a clean build in my timezone. For my little test setup I now get this:

(UTC) Co-ordinated Universal Time
5.32:  Thu Jan  1 00:00:00 1970
5.34:  Thu Jan  1 00:00:00 1970
blead: Thu Jan  1 00:00:00 1970
--------------------------------
(UTC-03:00) Greenland
5.32:  Wed Dec 31 23:59:59 1969
5.34:  Thu Jan  1 00:00:00 1970
blead: Thu Jan  1 00:00:00 1970
--------------------------------
(UTC-03:00) Brasilia
5.32:  Wed Dec 31 23:59:59 1969
5.34:  Thu Jan  1 01:00:00 1970
blead: Thu Jan  1 00:00:00 1970
--------------------------------
 (UTC+03:00) Istanbul
5.32:  Thu Jan  1 00:00:00 1970
5.34:  Wed Dec 31 23:59:59 1969
blead: Thu Jan  1 00:00:00 1970
--------------------------------
 (UTC+10:00) Brisbane
5.32:  Thu Jan  1 00:00:00 1970
5.34:  Thu Jan  1 00:00:00 1970
blead: Thu Jan  1 00:00:00 1970
--------------------------------

Conversion to local time seems unnecessary and it apparently causes issues with DST. Fixes #20018, #20061

Conversion to local time seems unnecessary and it apparently causes issues with DST. Fixes Perl#20018, Perl#20061

blues1875 added the Needs Triage label Aug 7, 2022

xenu added a commit to xenu/perl5 that referenced this issue Aug 7, 2022

win32.c: use _mkgmtime() instead of mktime() in stat()

13c51f8

Conversion to local time seems unnecessary and it apparently causes issues with DST. Fixes Perl#20018, Perl#20061

xenu mentioned this issue Aug 7, 2022

win32.c: use _mkgmtime() instead of mktime() in stat() #20064

Merged

xenu mentioned this issue Aug 7, 2022

Failed test 'mtime preserved by copy() while testing cross-partition' #20018

Closed

jkeenan added distro-mswin32 and removed Needs Triage labels Aug 7, 2022

blues1875 closed this as completed Aug 8, 2022

xenu added a commit that referenced this issue Aug 9, 2022

win32.c: use _mkgmtime() instead of mktime() in stat()

f7e7b4d

Conversion to local time seems unnecessary and it apparently causes issues with DST. Fixes #20018, #20061

scottchiefbaker pushed a commit to scottchiefbaker/perl5 that referenced this issue Nov 3, 2022

win32.c: use _mkgmtime() instead of mktime() in stat()

4239459

Conversion to local time seems unnecessary and it apparently causes issues with DST. Fixes Perl#20018, Perl#20061

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Uh oh!

DST problem on Win32 not fully resolved in perl 5.34 #20061

DST problem on Win32 not fully resolved in perl 5.34 #20061

blues1875 commented Aug 7, 2022

xenu commented Aug 7, 2022

Uh oh!

blues1875 commented Aug 8, 2022

Uh oh!

DST problem on Win32 not fully resolved in perl 5.34 #20061

DST problem on Win32 not fully resolved in perl 5.34 #20061

Comments

blues1875 commented Aug 7, 2022

xenu commented Aug 7, 2022

Uh oh!

blues1875 commented Aug 8, 2022

Uh oh!