Current File : //proc/16466/root/usr/share/perl5/XSLoader.pm
# Generated from XSLoader.pm.PL (resolved %Config::Config value)
package XSLoader;
$VERSION = "0.16";
#use strict;
package DynaLoader;
# No prizes for guessing why we don't say 'bootstrap DynaLoader;' here.
# NOTE: All dl_*.xs (including dl_none.xs) define a dl_error() XSUB
boot_DynaLoader('DynaLoader') if defined(&boot_DynaLoader) &&
!defined(&dl_error);
package XSLoader;
sub load {
package DynaLoader;
my ($module, $modlibname) = caller();
if (@_) {
$module = $_[0];
} else {
$_[0] = $module;
}
# work with static linking too
my $boots = "$module\::bootstrap";
goto &$boots if defined &$boots;
goto \&XSLoader::bootstrap_inherit unless $module and defined &dl_load_file;
my @modparts = split(/::/,$module);
my $modfname = $modparts[-1];
my $modpname = join('/',@modparts);
my $c = @modparts;
$modlibname =~ s,[\\/][^\\/]+$,, while $c--; # Q&D basename
my $file = "$modlibname/auto/$modpname/$modfname.so";
# print STDERR "XSLoader::load for $module ($file)\n" if $dl_debug;
my $bs = $file;
$bs =~ s/(\.\w+)?(;\d*)?$/\.bs/; # look for .bs 'beside' the library
if (-s $bs) { # only read file if it's not empty
# print STDERR "BS: $bs ($^O, $dlsrc)\n" if $dl_debug;
eval { do $bs; };
warn "$bs: $@\n" if $@;
}
goto \&XSLoader::bootstrap_inherit if not -f $file or -s $bs;
my $bootname = "boot_$module";
$bootname =~ s/\W/_/g;
@DynaLoader::dl_require_symbols = ($bootname);
my $boot_symbol_ref;
# Many dynamic extension loading problems will appear to come from
# this section of code: XYZ failed at line 123 of DynaLoader.pm.
# Often these errors are actually occurring in the initialisation
# C code of the extension XS file. Perl reports the error as being
# in this perl code simply because this was the last perl code
# it executed.
my $libref = dl_load_file($file, 0) or do {
require Carp;
Carp::croak("Can't load '$file' for module $module: " . dl_error());
};
push(@DynaLoader::dl_librefs,$libref); # record loaded object
my @unresolved = dl_undef_symbols();
if (@unresolved) {
require Carp;
Carp::carp("Undefined symbols present after loading $file: @unresolved\n");
}
$boot_symbol_ref = dl_find_symbol($libref, $bootname) or do {
require Carp;
Carp::croak("Can't find '$bootname' symbol in $file\n");
};
push(@DynaLoader::dl_modules, $module); # record loaded module
boot:
my $xs = dl_install_xsub($boots, $boot_symbol_ref, $file);
# See comment block above
push(@DynaLoader::dl_shared_objects, $file); # record files loaded
return &$xs(@_);
}
sub bootstrap_inherit {
require DynaLoader;
goto \&DynaLoader::bootstrap_inherit;
}
1;
__END__
=head1 NAME
XSLoader - Dynamically load C libraries into Perl code
=head1 VERSION
Version 0.15
=head1 SYNOPSIS
package YourPackage;
require XSLoader;
XSLoader::load();
=head1 DESCRIPTION
This module defines a standard I<simplified> interface to the dynamic
linking mechanisms available on many platforms. Its primary purpose is
to implement cheap automatic dynamic loading of Perl modules.
For a more complicated interface, see L<DynaLoader>. Many (most)
features of C<DynaLoader> are not implemented in C<XSLoader>, like for
example the C<dl_load_flags>, not honored by C<XSLoader>.
=head2 Migration from C<DynaLoader>
A typical module using L<DynaLoader|DynaLoader> starts like this:
package YourPackage;
require DynaLoader;
our @ISA = qw( OnePackage OtherPackage DynaLoader );
our $VERSION = '0.01';
bootstrap YourPackage $VERSION;
Change this to
package YourPackage;
use XSLoader;
our @ISA = qw( OnePackage OtherPackage );
our $VERSION = '0.01';
XSLoader::load 'YourPackage', $VERSION;
In other words: replace C<require DynaLoader> by C<use XSLoader>, remove
C<DynaLoader> from C<@ISA>, change C<bootstrap> by C<XSLoader::load>. Do not
forget to quote the name of your package on the C<XSLoader::load> line,
and add comma (C<,>) before the arguments (C<$VERSION> above).
Of course, if C<@ISA> contained only C<DynaLoader>, there is no need to have
the C<@ISA> assignment at all; moreover, if instead of C<our> one uses the
more backward-compatible
use vars qw($VERSION @ISA);
one can remove this reference to C<@ISA> together with the C<@ISA> assignment.
If no C<$VERSION> was specified on the C<bootstrap> line, the last line becomes
XSLoader::load 'YourPackage';
If the call to C<load> is from the YourPackage, then that can be further
simplified to
XSLoader::load();
as C<load> will use C<caller> to determine the package.
=head2 Backward compatible boilerplate
If you want to have your cake and eat it too, you need a more complicated
boilerplate.
package YourPackage;
use vars qw($VERSION @ISA);
@ISA = qw( OnePackage OtherPackage );
$VERSION = '0.01';
eval {
require XSLoader;
XSLoader::load('YourPackage', $VERSION);
1;
} or do {
require DynaLoader;
push @ISA, 'DynaLoader';
bootstrap YourPackage $VERSION;
};
The parentheses about C<XSLoader::load()> arguments are needed since we replaced
C<use XSLoader> by C<require>, so the compiler does not know that a function
C<XSLoader::load()> is present.
This boilerplate uses the low-overhead C<XSLoader> if present; if used with
an antic Perl which has no C<XSLoader>, it falls back to using C<DynaLoader>.
=head1 Order of initialization: early load()
I<Skip this section if the XSUB functions are supposed to be called from other
modules only; read it only if you call your XSUBs from the code in your module,
or have a C<BOOT:> section in your XS file (see L<perlxs/"The BOOT: Keyword">).
What is described here is equally applicable to the L<DynaLoader|DynaLoader>
interface.>
A sufficiently complicated module using XS would have both Perl code (defined
in F<YourPackage.pm>) and XS code (defined in F<YourPackage.xs>). If this
Perl code makes calls into this XS code, and/or this XS code makes calls to
the Perl code, one should be careful with the order of initialization.
The call to C<XSLoader::load()> (or C<bootstrap()>) calls the module's
bootstrap code. For modules build by F<xsubpp> (nearly all modules) this
has three side effects:
=over
=item *
A sanity check is done to ensure that the versions of the F<.pm> and the
(compiled) F<.xs> parts are compatible. If C<$VERSION> was specified, this
is used for the check. If not specified, it defaults to
C<$XS_VERSION // $VERSION> (in the module's namespace)
=item *
the XSUBs are made accessible from Perl
=item *
if a C<BOOT:> section was present in the F<.xs> file, the code there is called.
=back
Consequently, if the code in the F<.pm> file makes calls to these XSUBs, it is
convenient to have XSUBs installed before the Perl code is defined; for
example, this makes prototypes for XSUBs visible to this Perl code.
Alternatively, if the C<BOOT:> section makes calls to Perl functions (or
uses Perl variables) defined in the F<.pm> file, they must be defined prior to
the call to C<XSLoader::load()> (or C<bootstrap()>).
The first situation being much more frequent, it makes sense to rewrite the
boilerplate as
package YourPackage;
use XSLoader;
use vars qw($VERSION @ISA);
BEGIN {
@ISA = qw( OnePackage OtherPackage );
$VERSION = '0.01';
# Put Perl code used in the BOOT: section here
XSLoader::load 'YourPackage', $VERSION;
}
# Put Perl code making calls into XSUBs here
=head2 The most hairy case
If the interdependence of your C<BOOT:> section and Perl code is
more complicated than this (e.g., the C<BOOT:> section makes calls to Perl
functions which make calls to XSUBs with prototypes), get rid of the C<BOOT:>
section altogether. Replace it with a function C<onBOOT()>, and call it like
this:
package YourPackage;
use XSLoader;
use vars qw($VERSION @ISA);
BEGIN {
@ISA = qw( OnePackage OtherPackage );
$VERSION = '0.01';
XSLoader::load 'YourPackage', $VERSION;
}
# Put Perl code used in onBOOT() function here; calls to XSUBs are
# prototype-checked.
onBOOT;
# Put Perl initialization code assuming that XS is initialized here
=head1 DIAGNOSTICS
=over
=item C<Can't find '%s' symbol in %s>
B<(F)> The bootstrap symbol could not be found in the extension module.
=item C<Can't load '%s' for module %s: %s>
B<(F)> The loading or initialisation of the extension module failed.
The detailed error follows.
=item C<Undefined symbols present after loading %s: %s>
B<(W)> As the message says, some symbols stay undefined although the
extension module was correctly loaded and initialised. The list of undefined
symbols follows.
=back
=head1 LIMITATIONS
To reduce the overhead as much as possible, only one possible location
is checked to find the extension DLL (this location is where C<make install>
would put the DLL). If not found, the search for the DLL is transparently
delegated to C<DynaLoader>, which looks for the DLL along the C<@INC> list.
In particular, this is applicable to the structure of C<@INC> used for testing
not-yet-installed extensions. This means that running uninstalled extensions
may have much more overhead than running the same extensions after
C<make install>.
=head1 KNOWN BUGS
The new simpler way to call C<XSLoader::load()> with no arguments at all
does not work on Perl 5.8.4 and 5.8.5.
=head1 BUGS
Please report any bugs or feature requests via the perlbug(1) utility.
=head1 SEE ALSO
L<DynaLoader>
=head1 AUTHORS
Ilya Zakharevich originally extracted C<XSLoader> from C<DynaLoader>.
CPAN version is currently maintained by SE<eacute>bastien Aperghis-Tramoni
E<lt>sebastien@aperghis.netE<gt>.
Previous maintainer was Michael G Schwern <schwern@pobox.com>.
=head1 COPYRIGHT & LICENSE
Copyright (C) 1990-2011 by Larry Wall and others.
This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
=cut
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