11 # subroutine expand_os_specific expands $^O-specific preprocessing information
12 # so that it will not be re-calculated at runtime in Dynaloader.pm
14 # Syntax of preprocessor should be kept extremely simple:
15 # - directives are in double angle brackets <<...>>
16 # - <<=string>> will be just evaluated
17 # - for $^O-specific there are two forms:
20 # this directive should be closed with respectively
23 # construct <<|$^O-ne-osname>> means #else
24 # nested <<$^O...>>-constructs are allowed but nested values must be for
27 # -- added by VKON, 03-10-2004 to separate $^O-specific between OSes
28 # (so that Win32 never checks for $^O eq 'VMS' for example)
30 # The $^O tests test both for $^O and for $Config{osname}.
31 # The latter is better for some for cross-compilation setups.
33 sub expand_os_specific {
37 s/<<\$\^O-(eq|ne)-(\w+)>>(.*?)<<\/\$\^O-\1-\2>>/
38 my ($op, $os, $expr) = ($1,$2,$3);
39 if ($op ne 'eq' and $op ne 'ne') {die "wrong eq-ne arg in $&"};
40 if ($expr =~ m[^(.*?)<<\|\$\^O-$op-$os>>(.*?)$]s) {
42 my ($if,$el) = ($1,$2);
43 if (($op eq 'eq' and ($^O eq $os || $Config{osname} eq $os)) || ($op eq 'ne' and ($^O ne $os || $Config{osname} ne $os))) {
52 if (($op eq 'eq' and ($^O eq $os || $Config{osname} eq $os)) || ($op eq 'ne' and ($^O ne $os || $Config{osname} ne $os))) {
60 if (/<<(=|\$\^O-)/) {die "bad <<\$^O-eq/ne-osname>> expression.".
61 " Unclosed brackets?";
67 unlink "DynaLoader.pm" if -f "DynaLoader.pm";
68 open OUT, ">DynaLoader.pm" or die $!;
71 # Generated from DynaLoader_pm.PL
75 # And Gandalf said: 'Many folk like to know beforehand what is to
76 # be set on the table; but those who have laboured to prepare the
77 # feast like to keep their secret; for wonder makes the words of
80 # (Quote from Tolkien suggested by Anno Siegel.)
82 # See pod text at end of file for documentation.
83 # See also ext/DynaLoader/README in source tree for other information.
85 # Tim.Bunce@ig.co.uk, August 1994
92 *AUTOLOAD = \&AutoLoader::AUTOLOAD;
96 # enable debug/trace messages from DynaLoader perl code
97 $dl_debug = $ENV{PERL_DL_DEBUG} || 0 unless defined $dl_debug;
100 # Flags to alter dl_load_file behaviour. Assigned bits:
101 # 0x01 make symbols available for linking later dl_load_file's.
102 # (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL))
103 # (ignored under VMS; effect is built-in to image linking)
105 # This is called as a class method $module->dl_load_flags. The
106 # definition here will be inherited and result on "default" loading
107 # behaviour unless a sub-class of DynaLoader defines its own version.
110 sub dl_load_flags { 0x00 }
112 # ($dl_dlext, $dlsrc)
113 # = @Config::Config{'dlext', 'dlsrc'};
116 $dl_dlext = $Config::Config{'dlext'};
117 $dl_so = $Config::Config{'so'};
118 print OUT " (\$dl_dlext, \$dlsrc) = ('$dl_dlext', ",
119 to_string($Config::Config{'dlsrc'}), ")\n;";
121 print OUT expand_os_specific(<<'EOT');
124 # Some systems need special handling to expand file specifications
125 # (VMS support by Charles Bailey <bailey@HMIVAX.HUMGEN.UPENN.EDU>)
126 # See dl_expandspec() for more details. Should be harmless but
127 # inefficient to define on systems that don't need it.
128 $Is_VMS = $^O eq 'VMS';
130 $do_expand = <<$^O-eq-VMS>>1<<|$^O-eq-VMS>>0<</$^O-eq-VMS>>;
134 $Mac_FS = eval { require Mac::FileSpec::Unixish };
137 @dl_require_symbols = (); # names of symbols we need
138 @dl_resolve_using = (); # names of files to link with
139 @dl_library_path = (); # path to look for files
141 #XSLoader.pm may have added elements before we were required
142 #@dl_shared_objects = (); # shared objects for symbols we have
143 #@dl_librefs = (); # things we have loaded
144 #@dl_modules = (); # Modules we have loaded
146 # This is a fix to support DLD's unfortunate desire to relink -lc
147 @dl_resolve_using = dl_findfile('-lc') if $dlsrc eq "dl_dld.xs";
151 my $cfg_dl_library_path = <<'EOT';
152 push(@dl_library_path, split(' ', $Config::Config{libpth}));
155 sub dquoted_comma_list {
156 join(", ", map {'"'.quotemeta($_).'"'} @_);
159 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS}) {
160 eval $cfg_dl_library_path;
161 if (!$ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
162 my $dl_library_path = dquoted_comma_list(@dl_library_path);
164 # The below \@dl_library_path has been expanded (%Config) in Perl build time.
166 \@dl_library_path = ($dl_library_path);
173 # Initialise \@dl_library_path with the 'standard' library path
174 # for this platform as determined by Configure.
182 my $ldlibpthname_defined;
185 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS}) {
186 $ldlibpthname = to_string($Config::Config{ldlibpthname});
187 $ldlibpthname_defined = to_string(defined $Config::Config{ldlibpthname} ? 1 : 0);
188 $pthsep = to_string($Config::Config{path_sep});
191 $ldlibpthname = q($Config::Config{ldlibpthname});
192 $ldlibpthname_defined = q(defined $Config::Config{ldlibpthname});
193 $pthsep = q($Config::Config{path_sep});
196 my \$ldlibpthname = $ldlibpthname;
197 my \$ldlibpthname_defined = $ldlibpthname_defined;
198 my \$pthsep = $pthsep;
202 my $env_dl_library_path = <<'EOT';
203 if ($ldlibpthname_defined &&
204 exists $ENV{$ldlibpthname}) {
205 push(@dl_library_path, split(/$pthsep/, $ENV{$ldlibpthname}));
208 # E.g. HP-UX supports both its native SHLIB_PATH *and* LD_LIBRARY_PATH.
210 if ($ldlibpthname_defined &&
211 $ldlibpthname ne 'LD_LIBRARY_PATH' &&
212 exists $ENV{LD_LIBRARY_PATH}) {
213 push(@dl_library_path, split(/$pthsep/, $ENV{LD_LIBRARY_PATH}));
217 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS} && $ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
218 eval $env_dl_library_path;
222 # Add to \@dl_library_path any extra directories we can gather from environment
230 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS} && $ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
231 my $dl_library_path = dquoted_comma_list(@dl_library_path);
233 # The below \@dl_library_path has been expanded (%Config, %ENV)
234 # in Perl build time.
236 \@dl_library_path = ($dl_library_path);
242 # following long string contains $^O-specific stuff, which is factored out
243 print OUT expand_os_specific(<<'EOT');
244 # No prizes for guessing why we don't say 'bootstrap DynaLoader;' here.
245 # NOTE: All dl_*.xs (including dl_none.xs) define a dl_error() XSUB
246 boot_DynaLoader('DynaLoader') if defined(&boot_DynaLoader) &&
250 print STDERR "DynaLoader.pm loaded (@INC, @dl_library_path)\n";
251 print STDERR "DynaLoader not linked into this perl\n"
252 unless defined(&boot_DynaLoader);
255 1; # End of main code
258 sub croak { require Carp; Carp::croak(@_) }
260 sub bootstrap_inherit {
262 local *isa = *{"$module\::ISA"};
263 local @isa = (@isa, 'DynaLoader');
264 # Cannot goto due to delocalization. Will report errors on a wrong line?
268 # The bootstrap function cannot be autoloaded (without complications)
269 # so we define it here:
272 # use local vars to enable $module.bs script to edit values
274 local($module) = $args[0];
279 Carp::confess("Usage: DynaLoader::bootstrap(module)");
282 # A common error on platforms which don't support dynamic loading.
283 # Since it's fatal and potentially confusing we give a detailed message.
284 croak("Can't load module $module, dynamic loading not available in this perl.\n".
285 " (You may need to build a new perl executable which either supports\n".
286 " dynamic loading or has the $module module statically linked into it.)\n")
287 unless defined(&dl_load_file);
291 # Can dynaload, but cannot dynaload Perl modules...
292 die 'Dynaloaded Perl modules are not available in this build of Perl' if $OS2::is_static;
295 my @modparts = split(/::/,$module);
296 my $modfname = $modparts[-1];
298 # Some systems have restrictions on files names for DLL's etc.
299 # mod2fname returns appropriate file base name (typically truncated)
300 # It may also edit @modparts if required.
301 $modfname = &mod2fname(\@modparts) if defined &mod2fname;
304 # Truncate the module name to 8.3 format for NetWare
305 if ((length($modfname) > 8)) {
306 $modfname = substr($modfname, 0, 8);
310 my $modpname = join(<<$^O-eq-MacOS>>':'<<|$^O-eq-MacOS>>'/'<</$^O-eq-MacOS>>,@modparts);
312 print STDERR "DynaLoader::bootstrap for $module ",
313 <<$^O-eq-MacOS>> "(:auto:$modpname:$modfname.<<=$dl_dlext>>)\n"
314 <<|$^O-eq-MacOS>>"(auto/$modpname/$modfname.<<=$dl_dlext>>)\n"<</$^O-eq-MacOS>>
318 <<$^O-eq-VMS>>chop($_ = VMS::Filespec::unixpath($_));<</$^O-eq-VMS>>
321 if ($Mac_FS && ! -d $path) {
322 $path = Mac::FileSpec::Unixish::nativize($path);
324 $path .= ":" unless /:$/;
325 my $dir = "${path}auto:$modpname";
327 my $dir = "$_/auto/$modpname";
330 next unless -d $dir; # skip over uninteresting directories
332 # check for common cases to avoid autoload of dl_findfile
333 my $try = <<$^O-eq-MacOS>> "$dir:$modfname.<<=$dl_dlext>>" <<|$^O-eq-MacOS>> "$dir/$modfname.<<=$dl_dlext>>"<</$^O-eq-MacOS>>;
334 last if $file = <<$^O-eq-VMS>>($do_expand) ? dl_expandspec($try) : ((-f $try) && $try);
335 <<|$^O-eq-VMS>>(-f $try) && $try;
338 # no luck here, save dir for possible later dl_findfile search
341 # last resort, let dl_findfile have a go in all known locations
342 $file = dl_findfile(map("-L$_",@dirs,@INC), $modfname) unless $file;
344 croak("Can't locate loadable object for module $module in \@INC (\@INC contains: @INC)")
345 unless $file; # wording similar to error from 'require'
347 <<$^O-eq-VMS>>$file = uc($file) if $Config::Config{d_vms_case_sensitive_symbols};<</$^O-eq-VMS>>
348 my $bootname = "boot_$module";
349 $bootname =~ s/\W/_/g;
350 @dl_require_symbols = ($bootname);
352 # Execute optional '.bootstrap' perl script for this module.
353 # The .bs file can be used to configure @dl_resolve_using etc to
354 # match the needs of the individual module on this architecture.
356 $bs =~ s/(\.\w+)?(;\d*)?$/\.bs/; # look for .bs 'beside' the library
357 if (-s $bs) { # only read file if it's not empty
358 print STDERR "BS: $bs ($^O, $dlsrc)\n" if $dl_debug;
360 warn "$bs: $@\n" if $@;
366 if ($boot_symbol_ref = dl_find_symbol(0, $bootname)) {
367 goto boot; #extension library has already been loaded, e.g. darwin
371 # Many dynamic extension loading problems will appear to come from
372 # this section of code: XYZ failed at line 123 of DynaLoader.pm.
373 # Often these errors are actually occurring in the initialisation
374 # C code of the extension XS file. Perl reports the error as being
375 # in this perl code simply because this was the last perl code
378 my $libref = dl_load_file($file, $module->dl_load_flags) or
379 croak("Can't load '$file' for module $module: ".dl_error());
381 push(@dl_librefs,$libref); # record loaded object
383 my @unresolved = dl_undef_symbols();
386 Carp::carp("Undefined symbols present after loading $file: @unresolved\n");
389 $boot_symbol_ref = dl_find_symbol($libref, $bootname) or
390 croak("Can't find '$bootname' symbol in $file\n");
392 push(@dl_modules, $module); # record loaded module
395 my $xs = dl_install_xsub("${module}::bootstrap", $boot_symbol_ref, $file);
397 # See comment block above
399 push(@dl_shared_objects, $file); # record files loaded
405 #sub _check_file { # private utility to handle dl_expandspec vs -f tests
407 # return $file if (!$do_expand && -f $file); # the common case
408 # return $file if ( $do_expand && ($file=dl_expandspec($file)));
413 # Let autosplit and the autoloader deal with these functions:
418 # Read ext/DynaLoader/DynaLoader.doc for detailed information.
419 # This function does not automatically consider the architecture
420 # or the perl library auto directories.
422 my (@dirs, $dir); # which directories to search
423 my (@found); # full paths to real files we have found
424 #my $dl_ext= <<=to_string($Config::Config{'dlext'})>>; # $Config::Config{'dlext'} suffix for perl extensions
425 #my $dl_so = <<=to_string($Config::Config{'so'})>>; # $Config::Config{'so'} suffix for shared libraries
427 print STDERR "dl_findfile(@args)\n" if $dl_debug;
429 # accumulate directories but process files as they appear
430 arg: foreach(@args) {
431 # Special fast case: full filepath requires no search
433 if (m%[:>/\]]% && -f $_) {
434 push(@found,dl_expandspec(VMS::Filespec::vmsify($_)));
435 last arg unless wantarray;
442 last arg unless wantarray;
448 last arg unless wantarray;
453 # Deal with directories first:
454 # Using a -L prefix is the preferred option (faster and more robust)
455 if (m:^-L:) { s/^-L//; push(@dirs, $_); next; }
458 # Otherwise we try to try to spot directories by a heuristic
459 # (this is a more complicated issue than it first appears)
460 if (m/:/ && -d $_) { push(@dirs, $_); next; }
461 # Only files should get this far...
462 my(@names, $name); # what filenames to look for
465 foreach $dir (@dirs, @dl_library_path) {
467 $dir =~ s/^([^:]+)$/:$1/;
469 foreach $name (@names) {
470 my($file) = "$dir:$name";
471 print STDERR " checking in $dir for $name\n" if $dl_debug;
474 next arg; # no need to look any further
481 # Otherwise we try to try to spot directories by a heuristic
482 # (this is a more complicated issue than it first appears)
483 if (m:/: && -d $_) { push(@dirs, $_); next; }
486 # VMS: we may be using native VMS directory syntax instead of
487 # Unix emulation, so check this as well
488 if (/[:>\]]/ && -d $_) { push(@dirs, $_); next; }
491 # Only files should get this far...
492 my(@names, $name); # what filenames to look for
493 if (m:-l: ) { # convert -lname to appropriate library name
495 push(@names,"lib$_.<<=$dl_so>>");
496 push(@names,"lib$_.a");
497 } else { # Umm, a bare name. Try various alternatives:
498 # these should be ordered with the most likely first
499 push(@names,"$_.<<=$dl_dlext>>") unless m/\.<<=$dl_dlext>>$/o;
500 push(@names,"$_.<<=$dl_so>>") unless m/\.<<=$dl_so>>$/o;
501 push(@names,"lib$_.<<=$dl_so>>") unless m:/:;
502 push(@names,"$_.a") if !m/\.a$/ and $dlsrc eq "dl_dld.xs";
508 if ($0 =~ /^([a-z]):/i) {
510 @dirs = map { "$drive:$_" } @dirs;
511 @dl_library_path = map { "$drive:$_" } @dl_library_path;
514 foreach $dir (@dirs, @dl_library_path) {
517 chop($dir = VMS::Filespec::unixpath($dir));
519 foreach $name (@names) {
520 my($file) = "$dir$dirsep$name";
521 print STDERR " checking in $dir for $name\n" if $dl_debug;
522 $file = ($do_expand) ? dl_expandspec($file) : (-f $file && $file);
523 #$file = _check_file($file);
526 next arg; # no need to look any further
533 print STDERR " dl_findfile ignored non-existent directory: $_\n" unless -d $_;
535 print STDERR "dl_findfile found: @found\n";
537 return $found[0] unless wantarray;
544 # Optional function invoked if DynaLoader.pm sets $do_expand.
545 # Most systems do not require or use this function.
546 # Some systems may implement it in the dl_*.xs file in which case
547 # this autoload version will not be called but is harmless.
549 # This function is designed to deal with systems which treat some
550 # 'filenames' in a special way. For example VMS 'Logical Names'
551 # (something like unix environment variables - but different).
552 # This function should recognise such names and expand them into
554 # Must return undef if $spec is invalid or file does not exist.
556 my $file = $spec; # default output to input
559 # dl_expandspec should be defined in dl_vms.xs
561 Carp::croak("dl_expandspec: should be defined in XS file!\n");
563 return undef unless -f $file;
565 print STDERR "dl_expandspec($spec) => $file\n" if $dl_debug;
569 sub dl_find_symbol_anywhere
573 foreach $libref (@dl_librefs) {
574 my $symref = dl_find_symbol($libref,$sym);
575 return $symref if $symref;
582 DynaLoader - Dynamically load C libraries into Perl code
588 @ISA = qw(... DynaLoader ...);
589 bootstrap YourPackage;
591 # optional method for 'global' loading
592 sub dl_load_flags { 0x01 }
597 This document defines a standard generic interface to the dynamic
598 linking mechanisms available on many platforms. Its primary purpose is
599 to implement automatic dynamic loading of Perl modules.
601 This document serves as both a specification for anyone wishing to
602 implement the DynaLoader for a new platform and as a guide for
603 anyone wishing to use the DynaLoader directly in an application.
605 The DynaLoader is designed to be a very simple high-level
606 interface that is sufficiently general to cover the requirements
607 of SunOS, HP-UX, NeXT, Linux, VMS and other platforms.
609 It is also hoped that the interface will cover the needs of OS/2, NT
610 etc and also allow pseudo-dynamic linking (using C<ld -A> at runtime).
612 It must be stressed that the DynaLoader, by itself, is practically
613 useless for accessing non-Perl libraries because it provides almost no
614 Perl-to-C 'glue'. There is, for example, no mechanism for calling a C
615 library function or supplying arguments. A C::DynaLib module
616 is available from CPAN sites which performs that function for some
617 common system types. And since the year 2000, there's also Inline::C,
618 a module that allows you to write Perl subroutines in C. Also available
619 from your local CPAN site.
621 DynaLoader Interface Summary
631 bootstrap($modulename) Perl
632 @filepaths = dl_findfile(@names) Perl
633 $flags = $modulename->dl_load_flags Perl
634 $symref = dl_find_symbol_anywhere($symbol) Perl
636 $libref = dl_load_file($filename, $flags) C
637 $status = dl_unload_file($libref) C
638 $symref = dl_find_symbol($libref, $symbol) C
639 @symbols = dl_undef_symbols() C
640 dl_install_xsub($name, $symref [, $filename]) C
641 $message = dl_error C
645 =item @dl_library_path
647 The standard/default list of directories in which dl_findfile() will
648 search for libraries etc. Directories are searched in order:
649 $dl_library_path[0], [1], ... etc
651 @dl_library_path is initialised to hold the list of 'normal' directories
652 (F</usr/lib>, etc) determined by B<Configure> (C<$Config{'libpth'}>). This should
653 ensure portability across a wide range of platforms.
655 @dl_library_path should also be initialised with any other directories
656 that can be determined from the environment at runtime (such as
657 LD_LIBRARY_PATH for SunOS).
659 After initialisation @dl_library_path can be manipulated by an
660 application using push and unshift before calling dl_findfile().
661 Unshift can be used to add directories to the front of the search order
662 either to save search time or to override libraries with the same name
663 in the 'normal' directories.
665 The load function that dl_load_file() calls may require an absolute
666 pathname. The dl_findfile() function and @dl_library_path can be
667 used to search for and return the absolute pathname for the
668 library/object that you wish to load.
670 =item @dl_resolve_using
672 A list of additional libraries or other shared objects which can be
673 used to resolve any undefined symbols that might be generated by a
674 later call to load_file().
676 This is only required on some platforms which do not handle dependent
677 libraries automatically. For example the Socket Perl extension
678 library (F<auto/Socket/Socket.so>) contains references to many socket
679 functions which need to be resolved when it's loaded. Most platforms
680 will automatically know where to find the 'dependent' library (e.g.,
681 F</usr/lib/libsocket.so>). A few platforms need to be told the
682 location of the dependent library explicitly. Use @dl_resolve_using
687 @dl_resolve_using = dl_findfile('-lsocket');
689 =item @dl_require_symbols
691 A list of one or more symbol names that are in the library/object file
692 to be dynamically loaded. This is only required on some platforms.
696 An array of the handles returned by successful calls to dl_load_file(),
697 made by bootstrap, in the order in which they were loaded.
698 Can be used with dl_find_symbol() to look for a symbol in any of
703 An array of module (package) names that have been bootstrap'ed.
705 =item @dl_shared_objects
707 An array of file names for the shared objects that were loaded.
713 $message = dl_error();
715 Error message text from the last failed DynaLoader function. Note
716 that, similar to errno in unix, a successful function call does not
719 Implementations should detect the error as soon as it occurs in any of
720 the other functions and save the corresponding message for later
721 retrieval. This will avoid problems on some platforms (such as SunOS)
722 where the error message is very temporary (e.g., dlerror()).
726 Internal debugging messages are enabled when $dl_debug is set true.
727 Currently setting $dl_debug only affects the Perl side of the
728 DynaLoader. These messages should help an application developer to
729 resolve any DynaLoader usage problems.
731 $dl_debug is set to C<$ENV{'PERL_DL_DEBUG'}> if defined.
733 For the DynaLoader developer/porter there is a similar debugging
734 variable added to the C code (see dlutils.c) and enabled if Perl was
735 built with the B<-DDEBUGGING> flag. This can also be set via the
736 PERL_DL_DEBUG environment variable. Set to 1 for minimal information or
743 @filepaths = dl_findfile(@names)
745 Determine the full paths (including file suffix) of one or more
746 loadable files given their generic names and optionally one or more
747 directories. Searches directories in @dl_library_path by default and
748 returns an empty list if no files were found.
750 Names can be specified in a variety of platform independent forms. Any
751 names in the form B<-lname> are converted into F<libname.*>, where F<.*> is
752 an appropriate suffix for the platform.
754 If a name does not already have a suitable prefix and/or suffix then
755 the corresponding file will be searched for by trying combinations of
756 prefix and suffix appropriate to the platform: "$name.o", "lib$name.*"
759 If any directories are included in @names they are searched before
760 @dl_library_path. Directories may be specified as B<-Ldir>. Any other
761 names are treated as filenames to be searched for.
763 Using arguments of the form C<-Ldir> and C<-lname> is recommended.
767 @dl_resolve_using = dl_findfile(qw(-L/usr/5lib -lposix));
770 =item dl_expandspec()
774 $filepath = dl_expandspec($spec)
776 Some unusual systems, such as VMS, require special filename handling in
777 order to deal with symbolic names for files (i.e., VMS's Logical Names).
779 To support these systems a dl_expandspec() function can be implemented
780 either in the F<dl_*.xs> file or code can be added to the autoloadable
781 dl_expandspec() function in F<DynaLoader.pm>. See F<DynaLoader.pm> for
788 $libref = dl_load_file($filename, $flags)
790 Dynamically load $filename, which must be the path to a shared object
791 or library. An opaque 'library reference' is returned as a handle for
792 the loaded object. Returns undef on error.
794 The $flags argument to alters dl_load_file behaviour.
797 0x01 make symbols available for linking later dl_load_file's.
798 (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL))
799 (ignored under VMS; this is a normal part of image linking)
801 (On systems that provide a handle for the loaded object such as SunOS
802 and HPUX, $libref will be that handle. On other systems $libref will
803 typically be $filename or a pointer to a buffer containing $filename.
804 The application should not examine or alter $libref in any way.)
806 This is the function that does the real work. It should use the
807 current values of @dl_require_symbols and @dl_resolve_using if required.
809 SunOS: dlopen($filename)
810 HP-UX: shl_load($filename)
811 Linux: dld_create_reference(@dl_require_symbols); dld_link($filename)
812 NeXT: rld_load($filename, @dl_resolve_using)
813 VMS: lib$find_image_symbol($filename,$dl_require_symbols[0])
815 (The dlopen() function is also used by Solaris and some versions of
816 Linux, and is a common choice when providing a "wrapper" on other
817 mechanisms as is done in the OS/2 port.)
819 =item dl_unload_file()
823 $status = dl_unload_file($libref)
825 Dynamically unload $libref, which must be an opaque 'library reference' as
826 returned from dl_load_file. Returns one on success and zero on failure.
828 This function is optional and may not necessarily be provided on all platforms.
829 If it is defined, it is called automatically when the interpreter exits for
830 every shared object or library loaded by DynaLoader::bootstrap. All such
831 library references are stored in @dl_librefs by DynaLoader::Bootstrap as it
832 loads the libraries. The files are unloaded in last-in, first-out order.
834 This unloading is usually necessary when embedding a shared-object perl (e.g.
835 one configured with -Duseshrplib) within a larger application, and the perl
836 interpreter is created and destroyed several times within the lifetime of the
837 application. In this case it is possible that the system dynamic linker will
838 unload and then subsequently reload the shared libperl without relocating any
839 references to it from any files DynaLoaded by the previous incarnation of the
840 interpreter. As a result, any shared objects opened by DynaLoader may point to
841 a now invalid 'ghost' of the libperl shared object, causing apparently random
842 memory corruption and crashes. This behaviour is most commonly seen when using
843 Apache and mod_perl built with the APXS mechanism.
845 SunOS: dlclose($libref)
851 (The dlclose() function is also used by Solaris and some versions of
852 Linux, and is a common choice when providing a "wrapper" on other
853 mechanisms as is done in the OS/2 port.)
855 =item dl_load_flags()
859 $flags = dl_load_flags $modulename;
861 Designed to be a method call, and to be overridden by a derived class
862 (i.e. a class which has DynaLoader in its @ISA). The definition in
863 DynaLoader itself returns 0, which produces standard behavior from
866 =item dl_find_symbol()
870 $symref = dl_find_symbol($libref, $symbol)
872 Return the address of the symbol $symbol or C<undef> if not found. If the
873 target system has separate functions to search for symbols of different
874 types then dl_find_symbol() should search for function symbols first and
877 The exact manner in which the address is returned in $symref is not
878 currently defined. The only initial requirement is that $symref can
879 be passed to, and understood by, dl_install_xsub().
881 SunOS: dlsym($libref, $symbol)
882 HP-UX: shl_findsym($libref, $symbol)
883 Linux: dld_get_func($symbol) and/or dld_get_symbol($symbol)
884 NeXT: rld_lookup("_$symbol")
885 VMS: lib$find_image_symbol($libref,$symbol)
888 =item dl_find_symbol_anywhere()
892 $symref = dl_find_symbol_anywhere($symbol)
894 Applies dl_find_symbol() to the members of @dl_librefs and returns
895 the first match found.
897 =item dl_undef_symbols()
901 @symbols = dl_undef_symbols()
903 Return a list of symbol names which remain undefined after load_file().
904 Returns C<()> if not known. Don't worry if your platform does not provide
905 a mechanism for this. Most do not need it and hence do not provide it,
906 they just return an empty list.
909 =item dl_install_xsub()
913 dl_install_xsub($perl_name, $symref [, $filename])
915 Create a new Perl external subroutine named $perl_name using $symref as
916 a pointer to the function which implements the routine. This is simply
917 a direct call to newXSUB(). Returns a reference to the installed
920 The $filename parameter is used by Perl to identify the source file for
921 the function if required by die(), caller() or the debugger. If
922 $filename is not defined then "DynaLoader" will be used.
931 This is the normal entry point for automatic dynamic loading in Perl.
933 It performs the following actions:
939 locates an auto/$module directory by searching @INC
943 uses dl_findfile() to determine the filename to load
947 sets @dl_require_symbols to C<("boot_$module")>
951 executes an F<auto/$module/$module.bs> file if it exists
952 (typically used to add to @dl_resolve_using any files which
953 are required to load the module on the current platform)
957 calls dl_load_flags() to determine how to load the file.
961 calls dl_load_file() to load the file
965 calls dl_undef_symbols() and warns if any symbols are undefined
969 calls dl_find_symbol() for "boot_$module"
973 calls dl_install_xsub() to install it as "${module}::bootstrap"
977 calls &{"${module}::bootstrap"} to bootstrap the module (actually
978 it uses the function reference returned by dl_install_xsub for speed)
987 Tim Bunce, 11 August 1994.
989 This interface is based on the work and comments of (in no particular
990 order): Larry Wall, Robert Sanders, Dean Roehrich, Jeff Okamoto, Anno
991 Siegel, Thomas Neumann, Paul Marquess, Charles Bailey, myself and others.
993 Larry Wall designed the elegant inherited bootstrap mechanism and
994 implemented the first Perl 5 dynamic loader using it.
996 Solaris global loading added by Nick Ing-Simmons with design/coding
997 assistance from Tim Bunce, January 1996.
1002 close OUT or die $!;