File Coverage

blib/lib/Parse/PMFile.pm

Criterion	Covered	Total	%
statement	330	494	66.8
branch	154	254	60.6
condition	54	143	37.7
subroutine	32	41	78.0
pod	2	2	100.0
total	572	934	61.2

package Parse::PMFile;

sub __clean_eval { eval $_[0] } # needs to be here (RT#101273)

use strict;
use warnings;
use Safe;
use JSON::PP ();
use Dumpvalue;
use version ();
use File::Spec ();

our $VERSION = '0.48';
our $VERBOSE = 0;
our $ALLOW_DEV_VERSION = 0;
our $FORK = 0;
our $UNSAFE = $] < 5.010000 ? 1 : 0;

sub new {
    my ($class, $meta, $opts) = @_;
    bless {%{ $opts || {} }, META_CONTENT => $meta}, $class;
}

# from PAUSE::pmfile::examine_fio
sub parse {
    my ($self, $pmfile) = @_;

    $pmfile =~ s|\\|/|g;

    my($filemtime) = (stat $pmfile)[9];
    $self->{MTIME} = $filemtime;
    $self->{PMFILE} = $pmfile;

    unless ($self->_version_from_meta_ok) {
        my $version;
        unless (eval { $version = $self->_parse_version; 1 }) {
          $self->_verbose(1, "error with version in $pmfile: $@");
          return;
        }

        $self->{VERSION} = $version;
        if ($self->{VERSION} =~ /^\{.*\}$/) {
            # JSON error message
        } elsif ($self->{VERSION} =~ /[_\s]/ && !$self->{ALLOW_DEV_VERSION} && !$ALLOW_DEV_VERSION){   # ignore developer releases and "You suck!"
            return;
        }
    }

    my($ppp) = $self->_packages_per_pmfile;
    my @keys_ppp = $self->_filter_ppps(sort keys %$ppp);
    $self->_verbose(1,"Will check keys_ppp[@keys_ppp]\n");

    #
    # Immediately after each package (pmfile) examined contact
    # the database
    #

    my ($package, %errors);
    my %checked_in;
  DBPACK: foreach $package (@keys_ppp) {
        # this part is taken from PAUSE::package::examine_pkg
        # and PAUSE::package::_pkg_name_insane
        if ($package !~ /^\w[\w\:\']*\w?\z/
         || $package !~ /\w\z/
         || $package =~ /:/ && $package !~ /::/
         || $package =~ /\w:\w/
         || $package =~ /:::/
        ){
            $self->_verbose(1,"Package[$package] did not pass the ultimate sanity check");
            delete $ppp->{$package};
            next;
        }

        if ($self->{USERID} && $self->{PERMISSIONS} && !$self->_perm_check($package)) {
            delete $ppp->{$package};
            next;
        }

        # Check that package name matches case of file name
        {
          my (undef, $module) = split m{/lib/}, $self->{PMFILE}, 2;
          if ($module) {
            $module =~ s{\.pm\z}{};
            $module =~ s{/}{::}g;

            if (lc $module eq lc $package && $module ne $package) {
              # warn "/// $self->{PMFILE} vs. $module vs. $package\n";
              $errors{$package} = {
                indexing_warning => "Capitalization of package ($package) does not match filename!",
                infile => $self->{PMFILE},
              };
            }
          }
        }

        my $pp = $ppp->{$package};
        if ($pp->{version} && $pp->{version} =~ /^\{.*\}$/) { # JSON parser error
            my $err = JSON::PP::decode_json($pp->{version});
            if ($err->{x_normalize}) {
                $errors{$package} = {
                    normalize => $err->{version},
                    infile => $pp->{infile},
                };
                $pp->{version} = "undef";
            } elsif ($err->{openerr}) {
                $pp->{version} = "undef";
                $self->_verbose(1,
                              qq{Parse::PMFile was not able to
        read the file. It issued the following error: C< $err->{r} >},
                              );
                $errors{$package} = {
                    open => $err->{r},
                    infile => $pp->{infile},
                };
            } else {
                $pp->{version} = "undef";
                $self->_verbose(1,
                              qq{Parse::PMFile was not able to
        parse the following line in that file: C< $err->{line} >

        Note: the indexer is running in a Safe compartement and cannot
        provide the full functionality of perl in the VERSION line. It
        is trying hard, but sometime it fails. As a workaround, please
        consider writing a META.yml that contains a 'provides'
        attribute or contact the CPAN admins to investigate (yet
        another) workaround against "Safe" limitations.)},

                              );
                $errors{$package} = {
                    parse_version => $err->{line},
                    infile => $err->{file},
                };
            }
        }

        # Sanity checks

        for (
            $package,
            $pp->{version},
        ) {
            if (!defined || /^\s*$/ || /\s/){  # for whatever reason I come here
                delete $ppp->{$package};
                next;            # don't screw up 02packages
            }
        }
        unless ($self->_version_ok($pp)) {
            $errors{$package} = {
                long_version => qq{Version string exceeds maximum allowed length of 16b: "$pp->{version}"},
                infile => $pp->{infile},
            };
            next;
        }
        $checked_in{$package} = $ppp->{$package};
    }                       # end foreach package

    return (wantarray && %errors) ? (\%checked_in, \%errors) : \%checked_in;
}

sub _version_ok {
    my ($self, $pp) = @_;
    return if length($pp->{version} || 0) > 16;
    return 1
}

sub _perm_check {
    my ($self, $package) = @_;
    my $userid = $self->{USERID};
    my $module = $self->{PERMISSIONS}->module_permissions($package);
    return 1 if !$module; # not listed yet
    return 1 if defined $module->m && $module->m eq $userid;
    return 1 if defined $module->f && $module->f eq $userid;
    return 1 if defined $module->c && grep {$_ eq $userid} @{$module->c};
    return;
}

# from PAUSE::pmfile;
sub _parse_version {
    my $self = shift;

    use strict;

    my $pmfile = $self->{PMFILE};
    my $tmpfile = File::Spec->catfile(File::Spec->tmpdir, "ParsePMFile$$" . rand(1000));

    my $pmcp = $pmfile;
    for ($pmcp) {
        s/([^\\](\\\\)*)@/$1\\@/g; # thanks to Raphael Manfredi for the
        # solution to escape @s and \
    }
    my($v);
    {

        package main; # seems necessary

        # XXX: do we need to fork as PAUSE does?
        # or, is alarm() just fine?
        my $pid;
        if ($self->{FORK} || $FORK) {
            $pid = fork();
            die "Can't fork: $!" unless defined $pid;
        }
        if ($pid) {
            waitpid($pid, 0);
            if (open my $fh, '<', $tmpfile) {
                $v = <$fh>;
            }
        } else {
            # XXX Limit Resources too

            my $comp;
            my $eval = qq{
                local(\$^W) = 0;
                Parse::PMFile::_parse_version_safely("$pmcp");
            };
            unless ($self->{UNSAFE} || $UNSAFE) {
                $comp = Safe->new;
                $comp->permit("entereval"); # for MBARBON/Module-Info-0.30.tar.gz
                $comp->share("*Parse::PMFile::_parse_version_safely");
                $comp->share("*version::new");
                $comp->share("*version::numify");
                $comp->share_from('main', ['*version::',
                                            '*charstar::',
                                            '*Exporter::',
                                            '*DynaLoader::']);
                $comp->share_from('version', ['&qv']);
                $comp->permit(":base_math"); # atan2 (Acme-Pi)
                # $comp->permit("require"); # no strict!
                $comp->deny(qw/enteriter iter unstack goto/); # minimum protection against Acme::BadExample
            }

            version->import('qv') if $self->{UNSAFE} || $UNSAFE;
            {
                no strict;
                $v = $comp ? $comp->reval($eval) : eval $eval;
            }
            if ($@){ # still in the child process, out of Safe::reval
                my $err = $@;
                # warn ">>>>>>>err[$err]<<<<<<<<";
                if (ref $err) {
                    if ($err->{line} =~ /([\$*])([\w\:\']*)\bVERSION\b.*?\=(.*)/) {
                        local($^W) = 0;
                        my ($sigil, $vstr) = ($1, $3);
                        $self->_restore_overloaded_stuff(1) if $err->{line} =~ /use\s+version\b|version\->|qv\(/;
                        $v = $comp ? $comp->reval($vstr) : eval $vstr;
                        $v = $$v if $sigil eq '*' && ref $v;
                    }
                    if ($@ or !$v) {
                        $self->_verbose(1, sprintf("reval failed: err[%s] for eval[%s]",
                                      JSON::PP::encode_json($err),
                                      $eval,
                                    ));
                        $v = JSON::PP::encode_json($err);
                    }
                } else {
                    $v = JSON::PP::encode_json({ openerr => $err });
                }
            }
            if (defined $v) {
                no warnings;
                $v = $v->numify if ref($v) =~ /^version(::vpp)?$/;
            } else {
                $v = "";
            }
            if ($self->{FORK} || $FORK) {
                open my $fh, '>:utf8', $tmpfile;
                print $fh $v;
                exit 0;
            } else {
                utf8::encode($v);
                # undefine empty $v as if read from the tmpfile
                $v = undef if defined $v && !length $v;
                $comp->erase if ($comp);
                $self->_restore_overloaded_stuff;
            }
        }
    }
    unlink $tmpfile if ($self->{FORK} || $FORK) && -e $tmpfile;

    return $self->_normalize_version($v);
}

sub _restore_overloaded_stuff {
    my ($self, $used_version_in_safe) = @_;
    return if $self->{UNSAFE} || $UNSAFE;

    no strict 'refs';
    no warnings 'redefine';

    # version XS in CPAN
    my $restored;
    if ($INC{'version/vxs.pm'}) {
        *{'version::(""'} = \&version::vxs::stringify;
        *{'version::(0+'} = \&version::vxs::numify;
        *{'version::(cmp'} = \&version::vxs::VCMP;
        *{'version::(<=>'} = \&version::vxs::VCMP;
        *{'version::(bool'} = \&version::vxs::boolean;
        $restored = 1;
    }
    # version PP in CPAN
    if ($INC{'version/vpp.pm'}) {
        {
            package # hide from PAUSE
                charstar;
            overload->import;
        }
        if (!$used_version_in_safe) {
            package # hide from PAUSE
                version::vpp;
            overload->import;
        }
        unless ($restored) {
            *{'version::(""'} = \&version::vpp::stringify;
            *{'version::(0+'} = \&version::vpp::numify;
            *{'version::(cmp'} = \&version::vpp::vcmp;
            *{'version::(<=>'} = \&version::vpp::vcmp;
            *{'version::(bool'} = \&version::vpp::vbool;
        }
        *{'version::vpp::(""'} = \&version::vpp::stringify;
        *{'version::vpp::(0+'} = \&version::vpp::numify;
        *{'version::vpp::(cmp'} = \&version::vpp::vcmp;
        *{'version::vpp::(<=>'} = \&version::vpp::vcmp;
        *{'version::vpp::(bool'} = \&version::vpp::vbool;
        *{'charstar::(""'} = \&charstar::thischar;
        *{'charstar::(0+'} = \&charstar::thischar;
        *{'charstar::(++'} = \&charstar::increment;
        *{'charstar::(--'} = \&charstar::decrement;
        *{'charstar::(+'} = \&charstar::plus;
        *{'charstar::(-'} = \&charstar::minus;
        *{'charstar::(*'} = \&charstar::multiply;
        *{'charstar::(cmp'} = \&charstar::cmp;
        *{'charstar::(<=>'} = \&charstar::spaceship;
        *{'charstar::(bool'} = \&charstar::thischar;
        *{'charstar::(='} = \&charstar::clone;
        $restored = 1;
    }
    # version in core
    if (!$restored) {
        *{'version::(""'} = \&version::stringify;
        *{'version::(0+'} = \&version::numify;
        *{'version::(cmp'} = \&version::vcmp;
        *{'version::(<=>'} = \&version::vcmp;
        *{'version::(bool'} = \&version::boolean;
    }
}

# from PAUSE::pmfile;
sub _packages_per_pmfile {
    my $self = shift;

    my $ppp = {};
    my $pmfile = $self->{PMFILE};
    my $filemtime = $self->{MTIME};
    my $version = $self->{VERSION};

    open my $fh, "<", "$pmfile" or return $ppp;

    local $/ = "\n";
    my $inpod = 0;

    my $package_or_class = 'package';
    my $checked_bom;
  PLINE: while (<$fh>) {
        chomp;
        my($pline) = $_;
        $pline =~ s/\A(?:\x00\x00\xfe\xff|\xff\xfe\x00\x00|\xfe\xff|\xff\xfe|\xef\xbb\xbf)// unless $checked_bom;
        $checked_bom = 1;
        $inpod = $pline =~ /^=(?!cut)/ ? 1 :
            $pline =~ /^=cut/ ? 0 : $inpod;
        next if $inpod;
        next if substr($pline,0,4) eq "=cut";

        $pline =~ s/\#.*//;
        next if $pline =~ /^\s*$/;
        if ($pline =~ /^__(?:END|DATA)__\b/
            and $pmfile !~ /\.PL$/   # PL files may well have code after __DATA__
            ){
            last PLINE;
        }

=pod
        # hide in the pod block until 'class' is added to a version bundle
        if ($pline =~ /^[\s\{;]*use\s(+v?5\.[0-9]+)/) {
            my $version = $1;
            my $version_bundle_for_class = version->parse("v5.xx.xx");
            if (eval { version->parse($version) >= $version_bundle_for_class) {
                $package_or_class = 'package|class|role';
            }
            next PLINE;
        }
=cut

        # use feature 'class'; enabels class (and role, though not implemented yet)
        if ($pline =~ /^[\s\{;]*use\s+(?:feature|experimental)\s+[^;]+\b(?:class|all)[^;]*;/) {
            $package_or_class = 'package|class';
        }

        # some modules also enables class and role
        if ($pline =~ /^[\s\{;]*use\s+(?:Feature::Compat::Class)[^;]*;/) {
            $package_or_class = 'package|class';
        }
        if ($pline =~ /^[\s\{;]*use\s+(?:Object::Pad)[^;]*;/) {
            $package_or_class = 'package|class|role';
        }

        my $pkg;
        my $strict_version;

        if (
            # If you change *anything* here, it needs changing in '_parse_version_safely' too
            $pline =~ m{
                      # (.*) # takes too much time if $pline is long
                      #(?
                      ^[\s\{;]*
                      \b(?:$package_or_class)\s+
                      ([\w\:\']+)
                      \s*
                      (?: $ | [\}\;\:] | \{ | \s+($version::STRICT) )
                    }x) {
            $pkg = $1;
            $strict_version = $2;
            if ($pkg eq "DB"){
                # XXX if pumpkin and perl make him comaintainer! I
                # think I always made the pumpkins comaint on DB
                # without further ado (?)
                next PLINE;
            }
        }

        if ($pkg) {
            # Found something

            # from package
            $pkg =~ s/\'/::/g;
            next PLINE unless $pkg =~ /^[A-Za-z]/;
            next PLINE unless $pkg =~ /\w$/;
            next PLINE if $pkg eq "main";
            # Perl::Critic::Policy::TestingAndDebugging::ProhibitShebangWarningsArg
            # database for modid in mods, package in packages, package in perms
            # alter table mods modify modid varchar(128) binary NOT NULL default '';
            # alter table packages modify package varchar(128) binary NOT NULL default '';
            next PLINE if length($pkg) > 128;
            #restriction
            $ppp->{$pkg}{parsed}++;
            $ppp->{$pkg}{infile} = $pmfile;
            if ($self->_simile($pmfile,$pkg)) {
                $ppp->{$pkg}{simile} = $pmfile;
                if ($self->_version_from_meta_ok) {
                    my $provides = $self->{META_CONTENT}{provides};
                    if (exists $provides->{$pkg}) {
                        if (defined $provides->{$pkg}{version}) {
                            my $v = $provides->{$pkg}{version};
                            if ($v =~ /[_\s]/ && !$self->{ALLOW_DEV_VERSION} && !$ALLOW_DEV_VERSION){   # ignore developer releases and "You suck!"
                                next PLINE;
                            }

                            unless (eval { $version = $self->_normalize_version($v); 1 }) {
                              $self->_verbose(1, "error with version in $pmfile: $@");
                              next;

                            }
                            $ppp->{$pkg}{version} = $version;
                        } else {
                            $ppp->{$pkg}{version} = "undef";
                        }
                    }
                } else {
                    if (defined $strict_version){
                        $ppp->{$pkg}{version} = $strict_version ;
                    } else {
                        $ppp->{$pkg}{version} = defined $version ? $version : "";
                    }
                    no warnings;
                    if ($version eq 'undef') {
                        $ppp->{$pkg}{version} = $version unless defined $ppp->{$pkg}{version};
                    } else {
                        $ppp->{$pkg}{version} =
                            $version
                                if $version
                                    > $ppp->{$pkg}{version} ||
                                        $version
                                            gt $ppp->{$pkg}{version};
                    }
                }
            } else {        # not simile
                #### it comes later, it would be nonsense
                #### to set to "undef". MM_Unix gives us
                #### the best we can reasonably consider
                $ppp->{$pkg}{version} =
                    $version
                        unless defined $ppp->{$pkg}{version} &&
                            length($ppp->{$pkg}{version});
            }
            $ppp->{$pkg}{filemtime} = $filemtime;
            $ppp->{$pkg}{version} .= "";    # make sure to stringify version
        } else {
            # $self->_verbose(2,"no pkg found");
        }
    }

    close $fh;
    $ppp;
}

# from PAUSE::pmfile;
{
    no strict;
    sub _parse_version_safely {
        my($parsefile) = @_;
        my $result;
        local *FH;
        local $/ = "\n";
        open(FH,$parsefile) or die "Could not open '$parsefile': $!";
        my $inpod = 0;
        my $package_or_class = 'package';
        while () {
            $inpod = /^=(?!cut)/ ? 1 : /^=cut/ ? 0 : $inpod;
            next if $inpod || /^\s*#/;
            last if /^__(?:END|DATA)__\b/; # fails on quoted __END__ but this is rare -> __END__ in the middle of a line is rarer
            chop;

            # use feature 'class'; enabels class (and role, though not implemented yet)
            if (/^[\s\{;]*use\s+(?:feature|experimental)\s+[^;]+\b(?:class|all)[^;]*;/) {
                $package_or_class = 'package|class';
            }

            # some modules also enables class and role
            # XXX: what to do with MooseX::Declare and a few minor experiments)
            if (/^[\s\{;]*use\s+(?:Feature::Compat::Class)[^;]*;/) {
                $package_or_class = 'package|class';
            }
            if (/^[\s\{;]*use\s+(?:Object::Pad)[^;]*;/) {
                $package_or_class = 'package|class|role';
            }

            # If you change *anything* here, it needs changing in '_packages_per_pmfile' too
            if (my ($ver) = /$package_or_class \s+ \S+ \s+ (\S+) \s* [:;{]/x) {
              # XXX: should handle this better if version is bogus -- rjbs,
              # 2014-03-16
              return $ver if version::is_lax($ver);
            }

            # next unless /\$(([\w\:\']*)\bVERSION)\b.*\=/;
            next unless /(?<=])\=(?![=>])/;
            my $current_parsed_line = $_;
            my $eval = qq{
                package #
                    ExtUtils::MakeMaker::_version;

                local $1$2;
                \$$2=undef; do {
                    $_
                }; \$$2
            };
            local $^W = 0;
            local $SIG{__WARN__} = sub {};
            $result = __clean_eval($eval);
            # warn "current_parsed_line[$current_parsed_line]\$\@[$@]";
            if ($@ or !defined $result){
                die +{
                      eval => $eval,
                      line => $current_parsed_line,
                      file => $parsefile,
                      err => $@,
                      };
            }
            last;
        } #;
        close FH;

        $result = "undef" unless defined $result;
        if ((ref $result) =~ /^version(?:::vpp)?\b/) {
            no warnings;
            $result = $result->numify;
        }
        return $result;
    }
}

# from PAUSE::pmfile;
sub _filter_ppps {
    my($self,@ppps) = @_;
    my @res;

    # very similar code is in PAUSE::dist::filter_pms
  MANI: for my $ppp ( @ppps ) {
        if ($self->{META_CONTENT}){
            my $no_index = $self->{META_CONTENT}{no_index}
                            || $self->{META_CONTENT}{private}; # backward compat
            if (ref($no_index) eq 'HASH') {
                my %map = (
                            package => qr{\z},
                            namespace => qr{::},
                          );
                for my $k (qw(package namespace)) {
                    next unless my $v = $no_index->{$k};
                    my $rest = $map{$k};
                    if (ref $v eq "ARRAY") {
                        for my $ve (@$v) {
                            $ve =~ s|::$||;
                            if ($ppp =~ /^$ve$rest/){
                                $self->_verbose(1,"Skipping ppp[$ppp] due to ve[$ve]");
                                next MANI;
                            } else {
                                $self->_verbose(1,"NOT skipping ppp[$ppp] due to ve[$ve]");
                            }
                        }
                    } else {
                        $v =~ s|::$||;
                        if ($ppp =~ /^$v$rest/){
                            $self->_verbose(1,"Skipping ppp[$ppp] due to v[$v]");
                            next MANI;
                        } else {
                            $self->_verbose(1,"NOT skipping ppp[$ppp] due to v[$v]");
                        }
                    }
                }
            } else {
                $self->_verbose(1,"No keyword 'no_index' or 'private' in META_CONTENT");
            }
        } else {
            # $self->_verbose(1,"no META_CONTENT"); # too noisy
        }
        push @res, $ppp;
    }
    $self->_verbose(1,"Result of filter_ppps: res[@res]");
    @res;
}

# from PAUSE::pmfile;
sub _simile {
    my($self,$file,$package) = @_;
    # MakeMaker gives them the chance to have the file Simple.pm in
    # this directory but have the package HTML::Simple in it.
    # Afaik, they wouldn't be able to do so with deeper nested packages
    $file =~ s|.*/||;
    $file =~ s|\.pm(?:\.PL)?||;
    my $ret = $package =~ m/\b\Q$file\E$/;
    $ret ||= 0;
    unless ($ret) {
        # Apache::mod_perl_guide stuffs it into Version.pm
        $ret = 1 if lc $file eq 'version';
    }
    $self->_verbose(1,"Result of simile(): file[$file] package[$package] ret[$ret]\n");
    $ret;
}

# from PAUSE::pmfile
sub _normalize_version {
    my($self,$v) = @_;
    $v = "undef" unless defined $v;
    my $dv = Dumpvalue->new;
    my $sdv = $dv->stringify($v,1); # second argument prevents ticks
    $self->_verbose(1,"Result of normalize_version: sdv[$sdv]\n");

    return $v if $v eq "undef";
    return $v if $v =~ /^\{.*\}$/; # JSON object
    $v =~ s/^\s+//;
    $v =~ s/\s+\z//;
    if ($v =~ /_/) {
        # XXX should pass something like EDEVELOPERRELEASE up e.g.
        # SIXTEASE/XML-Entities-0.0306.tar.gz had nothing but one
        # such modules and the mesage was not helpful that "nothing
        # was found".
        return $v ;
    }
    if (!version::is_lax($v)) {
        return JSON::PP::encode_json({ x_normalize => 'version::is_lax failed', version => $v });
    }
    # may warn "Integer overflow"
    my $vv = eval { no warnings; version->new($v)->numify };
    if ($@) {
        # warn "$v: $@";
        return JSON::PP::encode_json({ x_normalize => $@, version => $v });
        # return "undef";
    }
    if ($vv eq $v) {
        # the boring 3.14
    } else {
        my $forced = $self->_force_numeric($v);
        if ($forced eq $vv) {
        } elsif ($forced =~ /^v(.+)/) {
            # rare case where a v1.0.23 slipped in (JANL/w3mir-1.0.10.tar.gz)
            no warnings;
            $vv = version->new($1)->numify;
        } else {
            # warn "Unequal forced[$forced] and vv[$vv]";
            if ($forced == $vv) {
                # the trailing zeroes would cause unnecessary havoc
                $vv = $forced;
            }
        }
    }
    return $vv;
}

# from PAUSE::pmfile;
sub _force_numeric {
    my($self,$v) = @_;
    $v = $self->_readable($v);

    if (
        $v =~
        /^(\+?)(\d*)(\.(\d*))?/ &&
        # "$2$4" ne ''
        (
          defined $2 && length $2
          ||
          defined $4 && length $4
        )
        ) {
        my $two = defined $2 ? $2 : "";
        my $three = defined $3 ? $3 : "";
        $v = "$two$three";
    }
    # no else branch! We simply say, everything else is a string.
    $v;
}

# from PAUSE::dist
sub _version_from_meta_ok {
  my($self) = @_;
  return $self->{VERSION_FROM_META_OK} if exists $self->{VERSION_FROM_META_OK};
  my $c = $self->{META_CONTENT};

  # If there's no provides hash, we can't get our module versions from the
  # provides hash! -- rjbs, 2012-03-31
  return($self->{VERSION_FROM_META_OK} = 0) unless $c->{provides};

  # Some versions of Module::Build geneated an empty provides hash.  If we're
  # *not* looking at a Module::Build-generated metafile, then it's okay.
  my ($mb_v) = (defined $c->{generated_by} ? $c->{generated_by} : '') =~ /Module::Build version ([\d\.]+)/;
  return($self->{VERSION_FROM_META_OK} = 1) unless $mb_v;

  # ??? I don't know why this is here.
  return($self->{VERSION_FROM_META_OK} = 1) if $mb_v eq '0.250.0';

  if ($mb_v >= 0.19 && $mb_v < 0.26 && ! keys %{$c->{provides}}) {
      # RSAVAGE/Javascript-SHA1-1.01.tgz had an empty provides hash. Ron
      # did not find the reason why this happened, but let's not go
      # overboard, 0.26 seems a good threshold from the statistics: there
      # are not many empty provides hashes from 0.26 up.
      return($self->{VERSION_FROM_META_OK} = 0);
  }

  # We're not in the suspect range of M::B versions.  It's good to go.
  return($self->{VERSION_FROM_META_OK} = 1);
}

sub _verbose {
    my($self,$level,@what) = @_;
    warn @what if $level <= ((ref $self && $self->{VERBOSE}) || $VERBOSE);
}

# all of the following methods are stripped from CPAN::Version
# (as of version 5.5001, bundled in CPAN 2.03), and slightly
# modified (ie. made private, as well as CPAN->debug(...) are
# replaced with $self->_verbose(9, ...).)

# CPAN::Version::vcmp courtesy Jost Krieger
sub _vcmp {
    my($self,$l,$r) = @_;
    local($^W) = 0;
    $self->_verbose(9, "l[$l] r[$r]");

    return 0 if $l eq $r; # short circuit for quicker success

    for ($l,$r) {
        s/_//g;
    }
    $self->_verbose(9, "l[$l] r[$r]");
    for ($l,$r) {
        next unless tr/.// > 1 || /^v/;
        s/^v?/v/;
        1 while s/\.0+(\d)/.$1/; # remove leading zeroes per group
    }
    $self->_verbose(9, "l[$l] r[$r]");
    if ($l=~/^v/ <=> $r=~/^v/) {
        for ($l,$r) {
            next if /^v/;
            $_ = $self->_float2vv($_);
        }
    }
    $self->_verbose(9, "l[$l] r[$r]");
    my $lvstring = "v0";
    my $rvstring = "v0";
    if ($] >= 5.006
     && $l =~ /^v/
     && $r =~ /^v/) {
        $lvstring = $self->_vstring($l);
        $rvstring = $self->_vstring($r);
        $self->_verbose(9, sprintf "lv[%vd] rv[%vd]", $lvstring, $rvstring);
    }

    return (
            ($l ne "undef") <=> ($r ne "undef")
            ||
            $lvstring cmp $rvstring
            ||
            $l <=> $r
            ||
            $l cmp $r
    );
}

sub _vgt {
    my($self,$l,$r) = @_;
    $self->_vcmp($l,$r) > 0;
}

sub _vlt {
    my($self,$l,$r) = @_;
    $self->_vcmp($l,$r) < 0;
}

sub _vge {
    my($self,$l,$r) = @_;
    $self->_vcmp($l,$r) >= 0;
}

sub _vle {
    my($self,$l,$r) = @_;
    $self->_vcmp($l,$r) <= 0;
}

sub _vstring {
    my($self,$n) = @_;
    $n =~ s/^v// or die "Parse::PMFile::_vstring() called with invalid arg [$n]";
    pack "U*", split /\./, $n;
}

# vv => visible vstring
sub _float2vv {
    my($self,$n) = @_;
    my($rev) = int($n);
    $rev ||= 0;
    my($mantissa) = $n =~ /\.(\d{1,12})/; # limit to 12 digits to limit
                                          # architecture influence
    $mantissa ||= 0;
    $mantissa .= "0" while length($mantissa)%3;
    my $ret = "v" . $rev;
    while ($mantissa) {
        $mantissa =~ s/(\d{1,3})// or
            die "Panic: length>0 but not a digit? mantissa[$mantissa]";
        $ret .= ".".int($1);
    }
    # warn "n[$n]ret[$ret]";
    $ret =~ s/(\.0)+/.0/; # v1.0.0 => v1.0
    $ret;
}

sub _readable {
    my($self,$n) = @_;
    $n =~ /^([\w\-\+\.]+)/;

    return $1 if defined $1 && length($1)>0;
    # if the first user reaches version v43, he will be treated as "+".
    # We'll have to decide about a new rule here then, depending on what
    # will be the prevailing versioning behavior then.

    if ($] < 5.006) { # or whenever v-strings were introduced
        # we get them wrong anyway, whatever we do, because 5.005 will
        # have already interpreted 0.2.4 to be "0.24". So even if he
        # indexer sends us something like "v0.2.4" we compare wrongly.

        # And if they say v1.2, then the old perl takes it as "v12"

        $self->_verbose(9, "Suspicious version string seen [$n]\n");
        return $n;
    }
    my $better = sprintf "v%vd", $n;
    $self->_verbose(9, "n[$n] better[$better]");
    return $better;
}

1;

__END__