[perl #119425] strftime outputs wrong with format '%p' under certain locales

# New Ticket Created by  Felipe Sologuren 
# Please include the string:  [perl #119425]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=119425 >


This is a bug report for perl from fsologuren@newtenberg.com,
generated with the help of perlbug 1.39 running under perl 5.14.2.


-----------------------------------------------------------------
strftime function returns a wrong output when I used locale 'es_CL' for
LC_TIME variable and the format string '%p'.
In contrast with command `date`, that returns an empty string with that
locale environment variable, strftime returns '%p' itself:
--------------------------------8<---------------------------------
$ perl -MPOSIX -e "POSIX::setlocale( LC_TIME, 'es_CL' ); my @t =
CORE::localtime();print \"'\".POSIX::strftime(\"%p\",@t).\"'\n\";"
'%p'
--------------------------------8<---------------------------------

But if the format contains an aditional character that implies non-empty
string output, the response is correct:
--------------------------------8<---------------------------------
$ perl -MPOSIX -e "POSIX::setlocale( LC_TIME, 'es_CL' ); my @t =
CORE::localtime();print \"'\".POSIX::strftime(\" %p\",@t).\"'\n\";"
' '
--------------------------------8<---------------------------------

Alternatively, with the C locale, the behaviour is as espected, probably
because the output is non-empty:
--------------------------------8<---------------------------------
$ perl -MPOSIX -e "POSIX::setlocale( LC_TIME, 'C' ); my @t =
CORE::localtime();print \"'\".POSIX::strftime(\" %p\",@t).\"'\n\";"
' '
--------------------------------8<---------------------------------

I tested strftime with the C code provided by `man 3 strftime` and the
output of the input format '%p' is '', as espected, So I believe that the
problem is pure perl.

I tested with perl 5.10.1 from debian stable and the problem is the same.
I tested with perl 5.19.3 (perlbrew over debian) and the problem persist.
I tested with perl 5.6.2 (perlbrew over debian) and the behaviour was
correct; strftime returns empty string with LC_TIME=es_CL.

I couldn't figured out where is the root of the problem because the fact
that the output string equals the format string is strange, but I suspect
about the wrapper Perl_my_strftime because it didn't manage well this case
where the returned value of C strftime is zero length, but the format
string is non-empty. On the other hand, the actual asignment to ST(0)
changed in commit b3c85772f7a16b79e679c78c9638a7afa4856432 when the wrapper
was moved from POSIX.xs to util.c and I didn't understand low level perl
code very well.

Thank you for your great work.
Perl rules.

-----------------------------------------------------------------
---
Flags:
    category=library
    severity=low
    module=POSIX
---
Site configuration information for perl 5.14.2:

Configured by Debian Project at Wed Apr 10 16:58:16 UTC 2013.

Summary of my perl5 (revision 5 version 14 subversion 2) configuration:

  Platform:
    osname=linux, osvers=3.2.0-4-amd64,
archname=x86_64-linux-gnu-thread-multi
    uname='linux madeleine 3.2.0-4-amd64 #1 smp debian 3.2.39-2 x86_64
gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector --param=ssp-buffer-size=4
-Wformat -Werror=format-security -Dldflags= -Wl,-z,relro
-Dlddlflags=-shared -Wl,-z,relro -Dcccdlflags=-fPIC
-Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.14
-Darchlib=/usr/lib/perl/5.14 -Dvendorprefix=/usr
-Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5
-Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.14.2
-Dsitearch=/usr/local/lib/perl/5.14.2 -Dman1dir=/usr/share/man/man1
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
-Dsiteman3dir=/usr/local/man/man3 -Duse64bitint -Dman1ext=1 -Dman3ext=3perl
-Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm
-Ui_libutil -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib
-Dlibperl=libperl.so.5.14.2 -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN
-fstack-protector -fno-strict-aliasing -pipe -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fstack-protector
-fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='4.7.2', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib/x86_64-linux-gnu /lib/../lib
/usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /usr/lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=, so=so, useshrplib=true, libperl=libperl.so.5.14.2
    gnulibc_version='2.13'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib
-fstack-protector'

Locally applied patches:


---
@INC for perl 5.14.2:
    /etc/perl
    /usr/local/lib/perl/5.14.2
    /usr/local/share/perl/5.14.2
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.14
    /usr/share/perl/5.14
    /usr/local/lib/site_perl
    .

---
Environment for perl 5.14.2:
    HOME=/home/felipe
    LANG=es_CL.UTF-8
    LANGUAGE=es_CL.UTF-8
    LC_ALL=es_CL.UTF-8
    LC_CTYPE=es_CL.UTF-8
    LC_MESSAGES=es_CL.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)

PATH=/usr/lib/x86_64-linux-gnu/qt4/bin:/home/felipe/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/usr/local/sbin:/usr/sbin:/sbin:~/xpn/xmark/bin:/usr/local/sbin:/usr/sbin:/sbin:~/xpn/xmark/bin
    PERL_BADLANG (unset)
    SHELL=/bin/bash

• [perl #119425] strftime outputs wrong with format '%p' under certain locales by Tony Cook via RT
• [perl #119425] strftime outputs wrong with format '%p' under certain locales by Felipe Sologuren