# Generated from XSLoader_pm.PL (resolved %Config::Config value) # This file is unique for every OS package XSLoader; $VERSION = "0.30"; # remember to update version in POD! #use strict; package DynaLoader; # No prizes for guessing why we don't say 'bootstrap DynaLoader;' here. # NOTE: All dl_*.xs (including dl_none.xs) define a dl_error() XSUB boot_DynaLoader('DynaLoader') if defined(&boot_DynaLoader) && !defined(&dl_error); package XSLoader; sub load { package DynaLoader; my ($caller, $modlibname) = caller(); my $module = $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 $modfname_orig = $modfname; # For .bs file search my $modpname = join('/',@modparts); my $c = () = split(/::/,$caller,-1); $modlibname =~ s,[\\/][^\\/]+$,, while $c--; # Q&D basename # Does this look like a relative path? if ($modlibname !~ m{^/}) { # Someone may have a #line directive that changes the file name, or # may be calling XSLoader::load from inside a string eval. We cer- # tainly do not want to go loading some code that is not in @INC, # as it could be untrusted. # # We could just fall back to DynaLoader here, but then the rest of # this function would go untested in the perl core, since all @INC # paths are relative during testing. That would be a time bomb # waiting to happen, since bugs could be introduced into the code. # # So look through @INC to see if $modlibname is in it. A rela- # tive $modlibname is not a common occurrence, so this block is # not hot code. FOUND: { for (@INC) { if ($_ eq $modlibname) { last FOUND; } } # Not found. Fall back to DynaLoader. goto \&XSLoader::bootstrap_inherit; } } my $file = "$modlibname/auto/$modpname/$modfname.so"; # print STDERR "XSLoader::load for $module ($file)\n" if $dl_debug; # N.B. The .bs file does not following the naming convention used # by mod2fname, so use the unedited version of the name. my $bs = "$modlibname/auto/$modpname/$modfname_orig.bs"; # This calls DynaLoader::bootstrap, which will load the .bs file if present 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 $boot_symbol_ref = dl_find_symbol($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 0.30 =head1 SYNOPSIS package YourPackage; require XSLoader; XSLoader::load(__PACKAGE__, $VERSION); =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 $VERSION = '0.01'; __PACKAGE__->bootstrap($VERSION); Change this to package YourPackage; use XSLoader; our @ISA = qw( OnePackage OtherPackage ); our $VERSION = '0.01'; XSLoader::load(__PACKAGE__, $VERSION); In other words: replace C<require DynaLoader> by C<use XSLoader>, remove C<DynaLoader> from C<@ISA>, change C<bootstrap> by C<XSLoader::load>. Do not forget to quote the name of your package on the C<XSLoader::load> line, and add comma (C<,>) before the arguments (C<$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(__PACKAGE__); in which case it 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; our @ISA = qw( OnePackage OtherPackage ); our $VERSION = '0.01'; eval { require XSLoader; XSLoader::load(__PACKAGE__, $VERSION); 1; } or do { require DynaLoader; push @ISA, 'DynaLoader'; __PACKAGE__->bootstrap($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 antique 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 // $VERSION> (in the module's namespace) =item * the XSUBs are made accessible from Perl =item * if a C<BOOT:> section was present in the F<.xs> file, the code there is called. =back Consequently, if the code in the F<.pm> file makes calls to these XSUBs, it is convenient to have XSUBs installed before the Perl code is defined; for example, this makes prototypes for XSUBs visible to this Perl code. Alternatively, if the C<BOOT:> section makes calls to Perl functions (or uses Perl variables) defined in the F<.pm> file, they must be defined prior to the call to C<XSLoader::load()> (or C<bootstrap()>). The first situation being much more frequent, it makes sense to rewrite the boilerplate as package YourPackage; use XSLoader; our ($VERSION, @ISA); BEGIN { @ISA = qw( OnePackage OtherPackage ); $VERSION = '0.01'; # Put Perl code used in the BOOT: section here XSLoader::load(__PACKAGE__, $VERSION); } # Put Perl code making calls into XSUBs here =head2 The most hairy case If the interdependence of your C<BOOT:> section and Perl code is more complicated than this (e.g., the C<BOOT:> section makes calls to Perl functions which make calls to XSUBs with prototypes), get rid of the C<BOOT:> section altogether. Replace it with a function C<onBOOT()>, and call it like this: package YourPackage; use XSLoader; our ($VERSION, @ISA); BEGIN { @ISA = qw( OnePackage OtherPackage ); $VERSION = '0.01'; XSLoader::load(__PACKAGE__, $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