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[perl #127953] stat.t build tests failing on some Cygwin

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Joel Maslak
April 22, 2016 11:09
[perl #127953] stat.t build tests failing on some Cygwin
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# New Ticket Created by  Joel Maslak 
# Please include the string:  [perl #127953]
# in the subject line of all future correspondence about this issue. 
# <URL: >

This is a bug report for perl from,
generated with the help of perlbug 1.40 running under perl 5.22.1.

On at least Perl 5.22.1 and Perl 5.24.0-RC0, Cygwin builds under
perlbrew as a standard Windows 10 user fails.  User is a member
of the Administrators group on the local machine, but Cygwin
and Perl.exe are not running with any special privileges.

t/op/stat.t fails on this environment:

ok 88 - unlink tmp file
ok 89 - can create temp file
ok 90 - -T _ doesn't break the statbuffer
not ok 91 - -T _ doesn't break lstat for unreadable file
# Failed test 91 - -T _ doesn't break lstat for unreadable file at
# t/op/stat.t line 552

The problem is that Perl is essentually doing (line numbers are from

534  ok(open(F, ">", $tmpfile), 'can create temp file');
535     close F;
536     chmod 0077, $tmpfile;
537     my @a = stat($tmpfile);
538     my $s1 = -s _;
539     -T _;
540     my $s2 = -s _;
541     is($s1, $s2, q(-T _ doesn't break the statbuffer));
542     SKIP: {
543 ⇥       my $root_uid = $Is_Cygwin ? 18 : 0;
544 ⇥       skip "No lstat", 1 unless $Config{d_lstat};
545 ⇥       skip "uid=0", 1 if $< == $root_uid or $> == $root_uid;
546 ⇥       skip "Can't check if admin user in miniperl", 1
547 ⇥         if $^O =~ /^(cygwin|MSWin32|msys)$/ && is_miniperl();
548 ⇥       skip "Readable by group/other means readable by me on $^O", 1 if $^O eq 'VMS'
549           or ($^O =~ /^(cygwin|MSWin32|msys)$/ and Win32::IsAdminUser());
550 ⇥       lstat($tmpfile);
551 ⇥       -T _;
552 ⇥       ok(eval { lstat _ },
553 ⇥          q(-T _ doesn't break lstat for unreadable file));
554     }

Line 536 on Cygwin Windows 10 doesn't operate as would be expected.  Here's
an example from the command line (tests were done from inside the build
directory, on an NTFS partition):

# I'm an admin, but Win32::IsAdminUser() doesn't detect that because I'm
# not running in an elevated privilege context.  So I don't have admin
# rights in this session

$ id
uid=181623(jmasl) gid=181623(jmasl) groups=197609(jmasl),401408(Medium Mandatory Level),545(Users),4(INTERACTIVE),66049(CONSOLE LOGON),11(Authenticated Users),15(This Organization),68413(,113(Local account),66048(LOCAL),262180(Cloud Account Authentication)
$ PERL5LIB=lib ./perl.exe -MWin32 -e 'print Win32::IsAdminUser(), "\n"'

# When I create a file and set it's mode to 077, the mode instead ends
# up being 777, which I can read:

$ echo test >test.txt
$ ls -l test.txt
-rw-r--r-- 1 jmasl jmasl 5 Apr 21 21:04 test.txt
$ chmod 077 test.txt
$ ls -l test.txt
-rwxrwxrwx 1 jmasl jmasl 5 Apr 21 21:04 test.txt
$ cat test.txt

# If I set the mode to 000, I can't.

$ chmod 000 test.txt
joel-win10:perl-5.22.1$ ls -l test.txt
---------- 1 jmasl jmasl 5 Apr 21 21:04 test.txt
joel-win10:perl-5.22.1$ cat test.txt
cat: test.txt: Permission denied

As you can see, chmod 077, at least on my Win 10 machine does let you
read the file still, thus the -T can successfully read the file.  That
means the lstat _ in the eval at 552 succeeds.  If the file was not
readable, it would error with "The stat preceding lstat() wasn't an lstat"
and thus the test passes.

I think the best way to fix this in the test is probably to skip this
test period if the user is running in Cygwin. Alternatively, use a
mode of 0000 instead of 0077 in the chmod() statement.  The build fails
as a normal user today, but passes as an admin because we skip the test
if an admin (with elevated privileges) does the build.

The Perl I used for perlbug is not the Perl that is causing issues -
the issue is on Cygwin on newer Windows with Perls up to 5.24.0-RC1.

[Please do not change anything below this line]
Site configuration information for perl 5.22.1:

Configured by jmaslak at Wed Dec 30 17:06:04 MST 2015.

Summary of my perl5 (revision 5 version 22 subversion 1) configuration:
    osname=linux, osvers=3.19.0-30-generic, archname=x86_64-linux
    uname='linux red 3.19.0-30-generic #34-ubuntu smp fri oct 2 22:08:41 utc 2015 x86_64 x86_64 x86_64 gnulinux '
    config_args='-de -Dprefix=/home/jmaslak/perl5/perlbrew/perls/perl-5.22.1 -Aeval:scriptdir=/home/jmaslak/perl5/perlbrew/perls/perl-5.22.1/bin'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
    cc='cc', ccflags ='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    cppflags='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion='', gccversion='4.9.2', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678, doublekind=3
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16, longdblkind=3
    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-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/4.9/include-fixed /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib
    libs=-lpthread -lnsl -ldb -ldl -lm -lcrypt -lutil -lc
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'

Locally applied patches:
    Devel::PatchPerl 1.38

@INC for perl 5.22.1:

Environment for perl 5.22.1:
    LANGUAGE (unset)
    LOGDIR (unset)
    PERL_BADLANG (unset)

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