Copy setlocale() return value in case it gets clobbered by later calls

[ntyni]

Flagged by AddressSanitizer in [perl #134182]

Quoting IEEE Std 1003.1, 2004 Edition

https://pubs.opengroup.org/onlinepubs/009695399/functions/setlocale.html

The string returned by setlocale() is such that a subsequent call with
that string and its associated category shall restore that part of the
program's locale. The application shall not modify the string returned
which may be overwritten by a subsequent call to setlocale().

Bug: https://rt.perl.org/Public/Bug/Display.html?id=134182

[tonycoz]

There's a more complete fix in https://rt.perl.org/Ticket/Display.html?id=134212

[Ark74]

Hello, just stumbled on this and tested it out.
Using this patch still fails on ext/POSIX/t/mb :(

ext/POSIX/t/mb ................................................. # Failed test 2 - MB_CUR_MAX is at least 4 in a UTF-8 locale at ../../t/test.pl line 1074
#      got 'perl: warning: Setting locale failed.\nperl: warning: Please check that your locale settings:\n\tLANGUAGE = (unset),\n\tLC_ALL = (unset),\n\tLC_CTYPE = \"C.UTF-8\",\n\tLANG = \"es_MX.UTF-8\"\n    are supported and installed on your system.\nperl: warning: Falling back to the standard locale (\"C\").\n1'
# expected /(?^:[4-6])/
# PROG: 
# use POSIX; print &POSIX::MB_CUR_MAX
# STATUS: 0
# Failed test 3 - mblen() recognizes invalid multibyte characters at ../../t/test.pl line 1062
#      got "perl: warning: Setting locale failed.\nperl: warning: Please check that your locale settings:\n\tLANGUAGE = (unset),\n\tLC_ALL = (unset),\n\tLC_CTYPE = \"C.UTF-8\",\n\tLANG = \"es_MX.UTF-8\"\n    are supported and installed on your system.\nperl: warning: Falling back to the standard locale (\"C\").\n-1"
# expected "-1"
# PROG: 
# use POSIX; print &POSIX::mblen("�(", 2)
# STATUS: 0
# Failed test 4 - mblen() works on UTF-8 characters at ../../t/test.pl line 1062
#      got "perl: warning: Setting locale failed.\nperl: warning: Please check that your locale settings:\n\tLANGUAGE = (unset),\n\tLC_ALL = (unset),\n\tLC_CTYPE = \"C.UTF-8\",\n\tLANG = \"es_MX.UTF-8\"\n    are supported and installed on your system.\nperl: warning: Falling back to the standard locale (\"C\").\n-1"
# expected "2"
# PROG: 
# use POSIX; print &POSIX::mblen("\N{GREEK SMALL LETTER SIGMA}", 2)
# STATUS: 0
FAILED at test 2

[...]

Failed 1 test out of 2537, 99.96% okay.
	../ext/POSIX/t/mb.t

Env:

• bionic - amd64
• perl - 5.30.0-9
• gdbm - 1.18.1-5
• dist - 3.5-236-0.1build1
• sbuild - 0.75.0-1ubuntu1

[Ark74]

Weird enough after applying this along with Perl/perl5@69b89a0

The build process passed 👍

What am I missing here? 😕

[Leont]

I've applied Tony's version of this patch