373 lines
11 KiB
Perl
373 lines
11 KiB
Perl
# Generated from XSLoader_pm.PL (resolved %Config::Config value)
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# This file is unique for every OS
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package XSLoader;
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$VERSION = "0.30"; # remember to update version in POD!
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#use strict;
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package DynaLoader;
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# No prizes for guessing why we don't say 'bootstrap DynaLoader;' here.
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# NOTE: All dl_*.xs (including dl_none.xs) define a dl_error() XSUB
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boot_DynaLoader('DynaLoader') if defined(&boot_DynaLoader) &&
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!defined(&dl_error);
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package XSLoader;
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sub load {
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package DynaLoader;
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my ($caller, $modlibname) = caller();
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my $module = $caller;
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if (@_) {
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$module = $_[0];
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} else {
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$_[0] = $module;
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}
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# work with static linking too
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my $boots = "$module\::bootstrap";
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goto &$boots if defined &$boots;
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goto \&XSLoader::bootstrap_inherit unless $module and defined &dl_load_file;
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my @modparts = split(/::/,$module);
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my $modfname = $modparts[-1];
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my $modfname_orig = $modfname; # For .bs file search
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my $modpname = join('/',@modparts);
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my $c = () = split(/::/,$caller,-1);
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$modlibname =~ s,[\\/][^\\/]+$,, while $c--; # Q&D basename
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# Does this look like a relative path?
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if ($modlibname !~ m{^(?:[A-Za-z]:)?[\\/]}) {
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# Someone may have a #line directive that changes the file name, or
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# may be calling XSLoader::load from inside a string eval. We cer-
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# tainly do not want to go loading some code that is not in @INC,
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# as it could be untrusted.
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#
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# We could just fall back to DynaLoader here, but then the rest of
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# this function would go untested in the perl core, since all @INC
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# paths are relative during testing. That would be a time bomb
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# waiting to happen, since bugs could be introduced into the code.
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#
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# So look through @INC to see if $modlibname is in it. A rela-
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# tive $modlibname is not a common occurrence, so this block is
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# not hot code.
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FOUND: {
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for (@INC) {
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if ($_ eq $modlibname) {
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last FOUND;
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}
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}
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# Not found. Fall back to DynaLoader.
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goto \&XSLoader::bootstrap_inherit;
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}
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}
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my $file = "$modlibname/auto/$modpname/$modfname.xs\.dll";
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# print STDERR "XSLoader::load for $module ($file)\n" if $dl_debug;
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# N.B. The .bs file does not following the naming convention used
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# by mod2fname, so use the unedited version of the name.
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my $bs = "$modlibname/auto/$modpname/$modfname_orig.bs";
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# This calls DynaLoader::bootstrap, which will load the .bs file if present
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goto \&XSLoader::bootstrap_inherit if not -f $file or -s $bs;
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my $bootname = "boot_$module";
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$bootname =~ s/\W/_/g;
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@DynaLoader::dl_require_symbols = ($bootname);
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my $boot_symbol_ref;
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# Many dynamic extension loading problems will appear to come from
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# this section of code: XYZ failed at line 123 of DynaLoader.pm.
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# Often these errors are actually occurring in the initialisation
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# C code of the extension XS file. Perl reports the error as being
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# in this perl code simply because this was the last perl code
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# it executed.
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my $libref = dl_load_file($file, 0) or do {
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require Carp;
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Carp::croak("Can't load '$file' for module $module: " . dl_error());
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};
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push(@DynaLoader::dl_librefs,$libref); # record loaded object
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$boot_symbol_ref = dl_find_symbol($libref, $bootname) or do {
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require Carp;
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Carp::croak("Can't find '$bootname' symbol in $file\n");
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};
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push(@DynaLoader::dl_modules, $module); # record loaded module
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boot:
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my $xs = dl_install_xsub($boots, $boot_symbol_ref, $file);
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# See comment block above
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push(@DynaLoader::dl_shared_objects, $file); # record files loaded
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return &$xs(@_);
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}
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sub bootstrap_inherit {
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require DynaLoader;
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goto \&DynaLoader::bootstrap_inherit;
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}
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1;
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__END__
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=head1 NAME
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XSLoader - Dynamically load C libraries into Perl code
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=head1 VERSION
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Version 0.30
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=head1 SYNOPSIS
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package YourPackage;
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require XSLoader;
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XSLoader::load(__PACKAGE__, $VERSION);
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=head1 DESCRIPTION
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This module defines a standard I<simplified> interface to the dynamic
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linking mechanisms available on many platforms. Its primary purpose is
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to implement cheap automatic dynamic loading of Perl modules.
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For a more complicated interface, see L<DynaLoader>. Many (most)
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features of C<DynaLoader> are not implemented in C<XSLoader>, like for
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example the C<dl_load_flags>, not honored by C<XSLoader>.
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=head2 Migration from C<DynaLoader>
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A typical module using L<DynaLoader|DynaLoader> starts like this:
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package YourPackage;
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require DynaLoader;
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our @ISA = qw( OnePackage OtherPackage DynaLoader );
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our $VERSION = '0.01';
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__PACKAGE__->bootstrap($VERSION);
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Change this to
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package YourPackage;
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use XSLoader;
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our @ISA = qw( OnePackage OtherPackage );
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our $VERSION = '0.01';
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XSLoader::load(__PACKAGE__, $VERSION);
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In other words: replace C<require DynaLoader> by C<use XSLoader>, remove
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C<DynaLoader> from C<@ISA>, change C<bootstrap> by C<XSLoader::load>. Do not
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forget to quote the name of your package on the C<XSLoader::load> line,
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and add comma (C<,>) before the arguments (C<$VERSION> above).
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Of course, if C<@ISA> contained only C<DynaLoader>, there is no need to have
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the C<@ISA> assignment at all; moreover, if instead of C<our> one uses the
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more backward-compatible
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use vars qw($VERSION @ISA);
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one can remove this reference to C<@ISA> together with the C<@ISA> assignment.
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If no C<$VERSION> was specified on the C<bootstrap> line, the last line becomes
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XSLoader::load(__PACKAGE__);
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in which case it can be further simplified to
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XSLoader::load();
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as C<load> will use C<caller> to determine the package.
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=head2 Backward compatible boilerplate
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If you want to have your cake and eat it too, you need a more complicated
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boilerplate.
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package YourPackage;
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our @ISA = qw( OnePackage OtherPackage );
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our $VERSION = '0.01';
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eval {
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require XSLoader;
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XSLoader::load(__PACKAGE__, $VERSION);
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1;
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} or do {
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require DynaLoader;
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push @ISA, 'DynaLoader';
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__PACKAGE__->bootstrap($VERSION);
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};
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The parentheses about C<XSLoader::load()> arguments are needed since we replaced
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C<use XSLoader> by C<require>, so the compiler does not know that a function
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C<XSLoader::load()> is present.
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This boilerplate uses the low-overhead C<XSLoader> if present; if used with
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an antique Perl which has no C<XSLoader>, it falls back to using C<DynaLoader>.
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=head1 Order of initialization: early load()
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I<Skip this section if the XSUB functions are supposed to be called from other
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modules only; read it only if you call your XSUBs from the code in your module,
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or have a C<BOOT:> section in your XS file (see L<perlxs/"The BOOT: Keyword">).
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What is described here is equally applicable to the L<DynaLoader|DynaLoader>
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interface.>
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A sufficiently complicated module using XS would have both Perl code (defined
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in F<YourPackage.pm>) and XS code (defined in F<YourPackage.xs>). If this
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Perl code makes calls into this XS code, and/or this XS code makes calls to
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the Perl code, one should be careful with the order of initialization.
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The call to C<XSLoader::load()> (or C<bootstrap()>) calls the module's
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bootstrap code. For modules build by F<xsubpp> (nearly all modules) this
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has three side effects:
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=over
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=item *
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A sanity check is done to ensure that the versions of the F<.pm> and the
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(compiled) F<.xs> parts are compatible. If C<$VERSION> was specified, this
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is used for the check. If not specified, it defaults to
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C<$XS_VERSION // $VERSION> (in the module's namespace)
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=item *
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the XSUBs are made accessible from Perl
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=item *
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if a C<BOOT:> section was present in the F<.xs> file, the code there is called.
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=back
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Consequently, if the code in the F<.pm> file makes calls to these XSUBs, it is
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convenient to have XSUBs installed before the Perl code is defined; for
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example, this makes prototypes for XSUBs visible to this Perl code.
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Alternatively, if the C<BOOT:> section makes calls to Perl functions (or
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uses Perl variables) defined in the F<.pm> file, they must be defined prior to
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the call to C<XSLoader::load()> (or C<bootstrap()>).
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The first situation being much more frequent, it makes sense to rewrite the
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boilerplate as
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package YourPackage;
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use XSLoader;
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our ($VERSION, @ISA);
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BEGIN {
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@ISA = qw( OnePackage OtherPackage );
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$VERSION = '0.01';
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# Put Perl code used in the BOOT: section here
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XSLoader::load(__PACKAGE__, $VERSION);
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}
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# Put Perl code making calls into XSUBs here
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=head2 The most hairy case
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If the interdependence of your C<BOOT:> section and Perl code is
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more complicated than this (e.g., the C<BOOT:> section makes calls to Perl
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functions which make calls to XSUBs with prototypes), get rid of the C<BOOT:>
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section altogether. Replace it with a function C<onBOOT()>, and call it like
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this:
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package YourPackage;
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use XSLoader;
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our ($VERSION, @ISA);
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BEGIN {
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@ISA = qw( OnePackage OtherPackage );
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$VERSION = '0.01';
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XSLoader::load(__PACKAGE__, $VERSION);
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}
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# Put Perl code used in onBOOT() function here; calls to XSUBs are
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# prototype-checked.
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onBOOT;
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# Put Perl initialization code assuming that XS is initialized here
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=head1 DIAGNOSTICS
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=over
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=item C<Can't find '%s' symbol in %s>
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B<(F)> The bootstrap symbol could not be found in the extension module.
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=item C<Can't load '%s' for module %s: %s>
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B<(F)> The loading or initialisation of the extension module failed.
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The detailed error follows.
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=item C<Undefined symbols present after loading %s: %s>
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B<(W)> As the message says, some symbols stay undefined although the
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extension module was correctly loaded and initialised. The list of undefined
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symbols follows.
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=back
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=head1 LIMITATIONS
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To reduce the overhead as much as possible, only one possible location
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is checked to find the extension DLL (this location is where C<make install>
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would put the DLL). If not found, the search for the DLL is transparently
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delegated to C<DynaLoader>, which looks for the DLL along the C<@INC> list.
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In particular, this is applicable to the structure of C<@INC> used for testing
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not-yet-installed extensions. This means that running uninstalled extensions
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may have much more overhead than running the same extensions after
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C<make install>.
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=head1 KNOWN BUGS
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The new simpler way to call C<XSLoader::load()> with no arguments at all
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does not work on Perl 5.8.4 and 5.8.5.
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=head1 BUGS
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Please report any bugs or feature requests via the perlbug(1) utility.
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=head1 SEE ALSO
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L<DynaLoader>
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=head1 AUTHORS
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Ilya Zakharevich originally extracted C<XSLoader> from C<DynaLoader>.
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CPAN version is currently maintained by SE<eacute>bastien Aperghis-Tramoni
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E<lt>sebastien@aperghis.netE<gt>.
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Previous maintainer was Michael G Schwern <schwern@pobox.com>.
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=head1 COPYRIGHT & LICENSE
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Copyright (C) 1990-2011 by Larry Wall and others.
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This program is free software; you can redistribute it and/or modify
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it under the same terms as Perl itself.
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=cut
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