10 unlink "DynaLoader.pm" if -f "DynaLoader.pm";
11 open OUT, ">DynaLoader.pm" or die $!;
14 # Generated from DynaLoader.pm.PL
18 # And Gandalf said: 'Many folk like to know beforehand what is to
19 # be set on the table; but those who have laboured to prepare the
20 # feast like to keep their secret; for wonder makes the words of
23 # (Quote from Tolkien suggested by Anno Siegel.)
25 # See pod text at end of file for documentation.
26 # See also ext/DynaLoader/README in source tree for other information.
28 # Tim.Bunce@ig.co.uk, August 1994
30 use vars qw($VERSION *AUTOLOAD);
32 $VERSION = '1.04'; # avoid typo warning
35 *AUTOLOAD = \&AutoLoader::AUTOLOAD;
39 # The following require can't be removed during maintenance
40 # releases, sadly, because of the risk of buggy code that does
41 # require Carp; Carp::croak "..."; without brackets dying
42 # if Carp hasn't been loaded in earlier compile time. :-(
43 # We'll let those bugs get found on the development track.
44 require Carp if $] < 5.00450;
46 # enable debug/trace messages from DynaLoader perl code
47 $dl_debug = $ENV{PERL_DL_DEBUG} || 0 unless defined $dl_debug;
50 # Flags to alter dl_load_file behaviour. Assigned bits:
51 # 0x01 make symbols available for linking later dl_load_file's.
52 # (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL))
53 # (ignored under VMS; effect is built-in to image linking)
55 # This is called as a class method $module->dl_load_flags. The
56 # definition here will be inherited and result on "default" loading
57 # behaviour unless a sub-class of DynaLoader defines its own version.
60 sub dl_load_flags { 0x00 }
63 # = @Config::Config{'dlext', 'dlsrc'};
66 print OUT " (\$dl_dlext, \$dlsrc) = (",
67 to_string($Config::Config{'dlext'}), ",",
68 to_string($Config::Config{'dlsrc'}), ")\n;" ;
72 # Some systems need special handling to expand file specifications
73 # (VMS support by Charles Bailey <bailey@HMIVAX.HUMGEN.UPENN.EDU>)
74 # See dl_expandspec() for more details. Should be harmless but
75 # inefficient to define on systems that don't need it.
76 $Is_VMS = $^O eq 'VMS';
78 $Is_MacOS = $^O eq 'MacOS';
81 $Mac_FS = eval { require Mac::FileSpec::Unixish } if $Is_MacOS;
83 @dl_require_symbols = (); # names of symbols we need
84 @dl_resolve_using = (); # names of files to link with
85 @dl_library_path = (); # path to look for files
87 #XSLoader.pm may have added elements before we were required
88 #@dl_librefs = (); # things we have loaded
89 #@dl_modules = (); # Modules we have loaded
91 # This is a fix to support DLD's unfortunate desire to relink -lc
92 @dl_resolve_using = dl_findfile('-lc') if $dlsrc eq "dl_dld.xs";
96 my $cfg_dl_library_path = <<'EOT';
97 push(@dl_library_path, split(' ', $Config::Config{libpth}));
100 sub dquoted_comma_list {
101 join(", ", map {qq("$_")} @_);
104 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS}) {
105 eval $cfg_dl_library_path;
106 if (!$ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
107 my $dl_library_path = dquoted_comma_list(@dl_library_path);
109 # The below \@dl_library_path has been expanded (%Config) in Perl build time.
111 \@dl_library_path = ($dl_library_path);
118 # Initialise \@dl_library_path with the 'standard' library path
119 # for this platform as determined by Configure.
127 my $ldlibpthname_defined;
130 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS}) {
131 $ldlibpthname = $Config::Config{ldlibpthname};
132 $ldlibpthname_defined = defined $Config::Config{ldlibpthname} ? 1 : 0;
133 $pthsep = $Config::Config{path_sep};
136 $ldlibpthname = q($Config::Config{ldlibpthname});
137 $ldlibpthname_defined = q(defined $Config::Config{ldlibpthname});
138 $pthsep = q($Config::Config{path_sep});
140 my \$ldlibpthname = $ldlibpthname;
141 my \$ldlibpthname_defined = $ldlibpthname_defined;
142 my \$pthsep = $pthsep;
147 my $env_dl_library_path = <<'EOT';
148 if ($ldlibpthname_defined &&
149 exists $ENV{$ldlibpthname}) {
150 push(@dl_library_path, split(/$pthsep/, $ENV{$ldlibpthname}));
153 # E.g. HP-UX supports both its native SHLIB_PATH *and* LD_LIBRARY_PATH.
155 if ($ldlibpthname_defined &&
156 $ldlibpthname ne 'LD_LIBRARY_PATH' &&
157 exists $ENV{LD_LIBRARY_PATH}) {
158 push(@dl_library_path, split(/$pthsep/, $ENV{LD_LIBRARY_PATH}));
162 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS} && $ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
163 eval $env_dl_library_path;
167 # Add to \@dl_library_path any extra directories we can gather from environment
175 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS} && $ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
176 my $dl_library_path = dquoted_comma_list(@dl_library_path);
178 # The below \@dl_library_path has been expanded (%Config, %ENV)
179 # in Perl build time.
181 \@dl_library_path = ($dl_library_path);
187 # No prizes for guessing why we don't say 'bootstrap DynaLoader;' here.
188 # NOTE: All dl_*.xs (including dl_none.xs) define a dl_error() XSUB
189 boot_DynaLoader('DynaLoader') if defined(&boot_DynaLoader) &&
193 print STDERR "DynaLoader.pm loaded (@INC, @dl_library_path)\n";
194 print STDERR "DynaLoader not linked into this perl\n"
195 unless defined(&boot_DynaLoader);
198 1; # End of main code
201 sub croak { require Carp; Carp::croak(@_) }
203 sub bootstrap_inherit {
205 local *isa = *{"$module\::ISA"};
206 local @isa = (@isa, 'DynaLoader');
207 # Cannot goto due to delocalization. Will report errors on a wrong line?
211 # The bootstrap function cannot be autoloaded (without complications)
212 # so we define it here:
215 # use local vars to enable $module.bs script to edit values
217 local($module) = $args[0];
222 Carp::confess("Usage: DynaLoader::bootstrap(module)");
225 # A common error on platforms which don't support dynamic loading.
226 # Since it's fatal and potentially confusing we give a detailed message.
227 croak("Can't load module $module, dynamic loading not available in this perl.\n".
228 " (You may need to build a new perl executable which either supports\n".
229 " dynamic loading or has the $module module statically linked into it.)\n")
230 unless defined(&dl_load_file);
234 print OUT <<'EOT' if $^O eq 'os2';
235 # Can dynaload, but cannot dynaload Perl modules...
236 die 'Dynaloaded Perl modules are not available in this build of Perl' if $OS2::is_static;
241 my @modparts = split(/::/,$module);
242 my $modfname = $modparts[-1];
244 # Some systems have restrictions on files names for DLL's etc.
245 # mod2fname returns appropriate file base name (typically truncated)
246 # It may also edit @modparts if required.
247 $modfname = &mod2fname(\@modparts) if defined &mod2fname;
249 # Truncate the module name to 8.3 format for NetWare
250 if (($^O eq 'NetWare') && (length($modfname) > 8)) {
251 $modfname = substr($modfname, 0, 8);
254 my $modpname = join(($Is_MacOS ? ':' : '/'),@modparts);
256 print STDERR "DynaLoader::bootstrap for $module ",
258 ? "(:auto:$modpname:$modfname.$dl_dlext)\n" :
259 "(auto/$modpname/$modfname.$dl_dlext)\n")
263 chop($_ = VMS::Filespec::unixpath($_)) if $Is_VMS;
267 if ($Mac_FS && ! -d $path) {
268 $path = Mac::FileSpec::Unixish::nativize($path);
270 $path .= ":" unless /:$/;
271 $dir = "${path}auto:$modpname";
273 $dir = "$_/auto/$modpname";
276 next unless -d $dir; # skip over uninteresting directories
278 # check for common cases to avoid autoload of dl_findfile
279 my $try = $Is_MacOS ? "$dir:$modfname.$dl_dlext" : "$dir/$modfname.$dl_dlext";
280 last if $file = ($do_expand) ? dl_expandspec($try) : ((-f $try) && $try);
282 # no luck here, save dir for possible later dl_findfile search
285 # last resort, let dl_findfile have a go in all known locations
286 $file = dl_findfile(map("-L$_",@dirs,@INC), $modfname) unless $file;
288 croak("Can't locate loadable object for module $module in \@INC (\@INC contains: @INC)")
289 unless $file; # wording similar to error from 'require'
291 $file = uc($file) if $Is_VMS && $Config::Config{d_vms_case_sensitive_symbols};
292 my $bootname = "boot_$module";
293 $bootname =~ s/\W/_/g;
294 @dl_require_symbols = ($bootname);
296 # Execute optional '.bootstrap' perl script for this module.
297 # The .bs file can be used to configure @dl_resolve_using etc to
298 # match the needs of the individual module on this architecture.
300 $bs =~ s/(\.\w+)?(;\d*)?$/\.bs/; # look for .bs 'beside' the library
301 if (-s $bs) { # only read file if it's not empty
302 print STDERR "BS: $bs ($^O, $dlsrc)\n" if $dl_debug;
304 warn "$bs: $@\n" if $@;
309 if ($^O eq 'darwin') {
310 if ($boot_symbol_ref = dl_find_symbol(0, $bootname)) {
311 goto boot; #extension library has already been loaded, e.g. darwin
315 # Many dynamic extension loading problems will appear to come from
316 # this section of code: XYZ failed at line 123 of DynaLoader.pm.
317 # Often these errors are actually occurring in the initialisation
318 # C code of the extension XS file. Perl reports the error as being
319 # in this perl code simply because this was the last perl code
322 my $libref = dl_load_file($file, $module->dl_load_flags) or
323 croak("Can't load '$file' for module $module: ".dl_error());
325 push(@dl_librefs,$libref); # record loaded object
327 my @unresolved = dl_undef_symbols();
330 Carp::carp("Undefined symbols present after loading $file: @unresolved\n");
333 $boot_symbol_ref = dl_find_symbol($libref, $bootname) or
334 croak("Can't find '$bootname' symbol in $file\n");
336 push(@dl_modules, $module); # record loaded module
339 my $xs = dl_install_xsub("${module}::bootstrap", $boot_symbol_ref, $file);
341 # See comment block above
346 #sub _check_file { # private utility to handle dl_expandspec vs -f tests
348 # return $file if (!$do_expand && -f $file); # the common case
349 # return $file if ( $do_expand && ($file=dl_expandspec($file)));
354 # Let autosplit and the autoloader deal with these functions:
359 # Read ext/DynaLoader/DynaLoader.doc for detailed information.
360 # This function does not automatically consider the architecture
361 # or the perl library auto directories.
363 my (@dirs, $dir); # which directories to search
364 my (@found); # full paths to real files we have found
367 print OUT ' my $dl_ext= ' . to_string($Config::Config{'dlext'}) .
368 "; # \$Config::Config{'dlext'} suffix for perl extensions\n";
369 print OUT ' my $dl_so = ' . to_string($Config::Config{'so'}) .
370 "; # \$Config::Config{'so'} suffix for shared libraries\n";
374 print STDERR "dl_findfile(@args)\n" if $dl_debug;
376 # accumulate directories but process files as they appear
377 arg: foreach(@args) {
378 # Special fast case: full filepath requires no search
379 if ($Is_VMS && m%[:>/\]]% && -f $_) {
380 push(@found,dl_expandspec(VMS::Filespec::vmsify($_)));
381 last arg unless wantarray;
387 last arg unless wantarray;
390 elsif (m:/: && -f $_ && !$do_expand) {
392 last arg unless wantarray;
396 # Deal with directories first:
397 # Using a -L prefix is the preferred option (faster and more robust)
398 if (m:^-L:) { s/^-L//; push(@dirs, $_); next; }
401 # Otherwise we try to try to spot directories by a heuristic
402 # (this is a more complicated issue than it first appears)
403 if (m/:/ && -d $_) { push(@dirs, $_); next; }
404 # Only files should get this far...
405 my(@names, $name); # what filenames to look for
408 foreach $dir (@dirs, @dl_library_path) {
410 $dir =~ s/^([^:]+)$/:$1/;
412 foreach $name (@names) {
413 my($file) = "$dir:$name";
414 print STDERR " checking in $dir for $name\n" if $dl_debug;
417 next arg; # no need to look any further
424 # Otherwise we try to try to spot directories by a heuristic
425 # (this is a more complicated issue than it first appears)
426 if (m:/: && -d $_) { push(@dirs, $_); next; }
428 # VMS: we may be using native VMS directory syntax instead of
429 # Unix emulation, so check this as well
430 if ($Is_VMS && /[:>\]]/ && -d $_) { push(@dirs, $_); next; }
432 # Only files should get this far...
433 my(@names, $name); # what filenames to look for
434 if (m:-l: ) { # convert -lname to appropriate library name
436 push(@names,"lib$_.$dl_so");
437 push(@names,"lib$_.a");
438 } else { # Umm, a bare name. Try various alternatives:
439 # these should be ordered with the most likely first
440 push(@names,"$_.$dl_ext") unless m/\.$dl_ext$/o;
441 push(@names,"$_.$dl_so") unless m/\.$dl_so$/o;
442 push(@names,"lib$_.$dl_so") unless m:/:;
443 push(@names,"$_.a") if !m/\.a$/ and $dlsrc eq "dl_dld.xs";
446 foreach $dir (@dirs, @dl_library_path) {
448 chop($dir = VMS::Filespec::unixpath($dir)) if $Is_VMS;
449 foreach $name (@names) {
450 my($file) = "$dir/$name";
451 print STDERR " checking in $dir for $name\n" if $dl_debug;
452 $file = ($do_expand) ? dl_expandspec($file) : (-f $file && $file);
453 #$file = _check_file($file);
456 next arg; # no need to look any further
463 print STDERR " dl_findfile ignored non-existent directory: $_\n" unless -d $_;
465 print STDERR "dl_findfile found: @found\n";
467 return $found[0] unless wantarray;
474 # Optional function invoked if DynaLoader.pm sets $do_expand.
475 # Most systems do not require or use this function.
476 # Some systems may implement it in the dl_*.xs file in which case
477 # this autoload version will not be called but is harmless.
479 # This function is designed to deal with systems which treat some
480 # 'filenames' in a special way. For example VMS 'Logical Names'
481 # (something like unix environment variables - but different).
482 # This function should recognise such names and expand them into
484 # Must return undef if $spec is invalid or file does not exist.
486 my $file = $spec; # default output to input
488 if ($Is_VMS) { # dl_expandspec should be defined in dl_vms.xs
490 Carp::croak("dl_expandspec: should be defined in XS file!\n");
492 return undef unless -f $file;
494 print STDERR "dl_expandspec($spec) => $file\n" if $dl_debug;
498 sub dl_find_symbol_anywhere
502 foreach $libref (@dl_librefs) {
503 my $symref = dl_find_symbol($libref,$sym);
504 return $symref if $symref;
511 DynaLoader - Dynamically load C libraries into Perl code
513 dl_error(), dl_findfile(), dl_expandspec(), dl_load_file(), dl_unload_file(), dl_find_symbol(), dl_find_symbol_anywhere(), dl_undef_symbols(), dl_install_xsub(), dl_load_flags(), bootstrap() - routines used by DynaLoader modules
519 @ISA = qw(... DynaLoader ...);
520 bootstrap YourPackage;
522 # optional method for 'global' loading
523 sub dl_load_flags { 0x01 }
528 This document defines a standard generic interface to the dynamic
529 linking mechanisms available on many platforms. Its primary purpose is
530 to implement automatic dynamic loading of Perl modules.
532 This document serves as both a specification for anyone wishing to
533 implement the DynaLoader for a new platform and as a guide for
534 anyone wishing to use the DynaLoader directly in an application.
536 The DynaLoader is designed to be a very simple high-level
537 interface that is sufficiently general to cover the requirements
538 of SunOS, HP-UX, NeXT, Linux, VMS and other platforms.
540 It is also hoped that the interface will cover the needs of OS/2, NT
541 etc and also allow pseudo-dynamic linking (using C<ld -A> at runtime).
543 It must be stressed that the DynaLoader, by itself, is practically
544 useless for accessing non-Perl libraries because it provides almost no
545 Perl-to-C 'glue'. There is, for example, no mechanism for calling a C
546 library function or supplying arguments. A C::DynaLib module
547 is available from CPAN sites which performs that function for some
548 common system types. And since the year 2000, there's also Inline::C,
549 a module that allows you to write Perl subroutines in C. Also available
550 from your local CPAN site.
552 DynaLoader Interface Summary
561 bootstrap($modulename) Perl
562 @filepaths = dl_findfile(@names) Perl
563 $flags = $modulename->dl_load_flags Perl
564 $symref = dl_find_symbol_anywhere($symbol) Perl
566 $libref = dl_load_file($filename, $flags) C
567 $status = dl_unload_file($libref) C
568 $symref = dl_find_symbol($libref, $symbol) C
569 @symbols = dl_undef_symbols() C
570 dl_install_xsub($name, $symref [, $filename]) C
571 $message = dl_error C
575 =item @dl_library_path
577 The standard/default list of directories in which dl_findfile() will
578 search for libraries etc. Directories are searched in order:
579 $dl_library_path[0], [1], ... etc
581 @dl_library_path is initialised to hold the list of 'normal' directories
582 (F</usr/lib>, etc) determined by B<Configure> (C<$Config{'libpth'}>). This should
583 ensure portability across a wide range of platforms.
585 @dl_library_path should also be initialised with any other directories
586 that can be determined from the environment at runtime (such as
587 LD_LIBRARY_PATH for SunOS).
589 After initialisation @dl_library_path can be manipulated by an
590 application using push and unshift before calling dl_findfile().
591 Unshift can be used to add directories to the front of the search order
592 either to save search time or to override libraries with the same name
593 in the 'normal' directories.
595 The load function that dl_load_file() calls may require an absolute
596 pathname. The dl_findfile() function and @dl_library_path can be
597 used to search for and return the absolute pathname for the
598 library/object that you wish to load.
600 =item @dl_resolve_using
602 A list of additional libraries or other shared objects which can be
603 used to resolve any undefined symbols that might be generated by a
604 later call to load_file().
606 This is only required on some platforms which do not handle dependent
607 libraries automatically. For example the Socket Perl extension
608 library (F<auto/Socket/Socket.so>) contains references to many socket
609 functions which need to be resolved when it's loaded. Most platforms
610 will automatically know where to find the 'dependent' library (e.g.,
611 F</usr/lib/libsocket.so>). A few platforms need to be told the
612 location of the dependent library explicitly. Use @dl_resolve_using
617 @dl_resolve_using = dl_findfile('-lsocket');
619 =item @dl_require_symbols
621 A list of one or more symbol names that are in the library/object file
622 to be dynamically loaded. This is only required on some platforms.
626 An array of the handles returned by successful calls to dl_load_file(),
627 made by bootstrap, in the order in which they were loaded.
628 Can be used with dl_find_symbol() to look for a symbol in any of
633 An array of module (package) names that have been bootstrap'ed.
639 $message = dl_error();
641 Error message text from the last failed DynaLoader function. Note
642 that, similar to errno in unix, a successful function call does not
645 Implementations should detect the error as soon as it occurs in any of
646 the other functions and save the corresponding message for later
647 retrieval. This will avoid problems on some platforms (such as SunOS)
648 where the error message is very temporary (e.g., dlerror()).
652 Internal debugging messages are enabled when $dl_debug is set true.
653 Currently setting $dl_debug only affects the Perl side of the
654 DynaLoader. These messages should help an application developer to
655 resolve any DynaLoader usage problems.
657 $dl_debug is set to C<$ENV{'PERL_DL_DEBUG'}> if defined.
659 For the DynaLoader developer/porter there is a similar debugging
660 variable added to the C code (see dlutils.c) and enabled if Perl was
661 built with the B<-DDEBUGGING> flag. This can also be set via the
662 PERL_DL_DEBUG environment variable. Set to 1 for minimal information or
669 @filepaths = dl_findfile(@names)
671 Determine the full paths (including file suffix) of one or more
672 loadable files given their generic names and optionally one or more
673 directories. Searches directories in @dl_library_path by default and
674 returns an empty list if no files were found.
676 Names can be specified in a variety of platform independent forms. Any
677 names in the form B<-lname> are converted into F<libname.*>, where F<.*> is
678 an appropriate suffix for the platform.
680 If a name does not already have a suitable prefix and/or suffix then
681 the corresponding file will be searched for by trying combinations of
682 prefix and suffix appropriate to the platform: "$name.o", "lib$name.*"
685 If any directories are included in @names they are searched before
686 @dl_library_path. Directories may be specified as B<-Ldir>. Any other
687 names are treated as filenames to be searched for.
689 Using arguments of the form C<-Ldir> and C<-lname> is recommended.
693 @dl_resolve_using = dl_findfile(qw(-L/usr/5lib -lposix));
696 =item dl_expandspec()
700 $filepath = dl_expandspec($spec)
702 Some unusual systems, such as VMS, require special filename handling in
703 order to deal with symbolic names for files (i.e., VMS's Logical Names).
705 To support these systems a dl_expandspec() function can be implemented
706 either in the F<dl_*.xs> file or code can be added to the autoloadable
707 dl_expandspec() function in F<DynaLoader.pm>. See F<DynaLoader.pm> for
714 $libref = dl_load_file($filename, $flags)
716 Dynamically load $filename, which must be the path to a shared object
717 or library. An opaque 'library reference' is returned as a handle for
718 the loaded object. Returns undef on error.
720 The $flags argument to alters dl_load_file behaviour.
723 0x01 make symbols available for linking later dl_load_file's.
724 (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL))
725 (ignored under VMS; this is a normal part of image linking)
727 (On systems that provide a handle for the loaded object such as SunOS
728 and HPUX, $libref will be that handle. On other systems $libref will
729 typically be $filename or a pointer to a buffer containing $filename.
730 The application should not examine or alter $libref in any way.)
732 This is the function that does the real work. It should use the
733 current values of @dl_require_symbols and @dl_resolve_using if required.
735 SunOS: dlopen($filename)
736 HP-UX: shl_load($filename)
737 Linux: dld_create_reference(@dl_require_symbols); dld_link($filename)
738 NeXT: rld_load($filename, @dl_resolve_using)
739 VMS: lib$find_image_symbol($filename,$dl_require_symbols[0])
741 (The dlopen() function is also used by Solaris and some versions of
742 Linux, and is a common choice when providing a "wrapper" on other
743 mechanisms as is done in the OS/2 port.)
745 =item dl_unload_file()
749 $status = dl_unload_file($libref)
751 Dynamically unload $libref, which must be an opaque 'library reference' as
752 returned from dl_load_file. Returns one on success and zero on failure.
754 This function is optional and may not necessarily be provided on all platforms.
755 If it is defined, it is called automatically when the interpreter exits for
756 every shared object or library loaded by DynaLoader::bootstrap. All such
757 library references are stored in @dl_librefs by DynaLoader::Bootstrap as it
758 loads the libraries. The files are unloaded in last-in, first-out order.
760 This unloading is usually necessary when embedding a shared-object perl (e.g.
761 one configured with -Duseshrplib) within a larger application, and the perl
762 interpreter is created and destroyed several times within the lifetime of the
763 application. In this case it is possible that the system dynamic linker will
764 unload and then subsequently reload the shared libperl without relocating any
765 references to it from any files DynaLoaded by the previous incarnation of the
766 interpreter. As a result, any shared objects opened by DynaLoader may point to
767 a now invalid 'ghost' of the libperl shared object, causing apparently random
768 memory corruption and crashes. This behaviour is most commonly seen when using
769 Apache and mod_perl built with the APXS mechanism.
771 SunOS: dlclose($libref)
777 (The dlclose() function is also used by Solaris and some versions of
778 Linux, and is a common choice when providing a "wrapper" on other
779 mechanisms as is done in the OS/2 port.)
781 =item dl_load_flags()
785 $flags = dl_load_flags $modulename;
787 Designed to be a method call, and to be overridden by a derived class
788 (i.e. a class which has DynaLoader in its @ISA). The definition in
789 DynaLoader itself returns 0, which produces standard behavior from
792 =item dl_find_symbol()
796 $symref = dl_find_symbol($libref, $symbol)
798 Return the address of the symbol $symbol or C<undef> if not found. If the
799 target system has separate functions to search for symbols of different
800 types then dl_find_symbol() should search for function symbols first and
803 The exact manner in which the address is returned in $symref is not
804 currently defined. The only initial requirement is that $symref can
805 be passed to, and understood by, dl_install_xsub().
807 SunOS: dlsym($libref, $symbol)
808 HP-UX: shl_findsym($libref, $symbol)
809 Linux: dld_get_func($symbol) and/or dld_get_symbol($symbol)
810 NeXT: rld_lookup("_$symbol")
811 VMS: lib$find_image_symbol($libref,$symbol)
814 =item dl_find_symbol_anywhere()
818 $symref = dl_find_symbol_anywhere($symbol)
820 Applies dl_find_symbol() to the members of @dl_librefs and returns
821 the first match found.
823 =item dl_undef_symbols()
827 @symbols = dl_undef_symbols()
829 Return a list of symbol names which remain undefined after load_file().
830 Returns C<()> if not known. Don't worry if your platform does not provide
831 a mechanism for this. Most do not need it and hence do not provide it,
832 they just return an empty list.
835 =item dl_install_xsub()
839 dl_install_xsub($perl_name, $symref [, $filename])
841 Create a new Perl external subroutine named $perl_name using $symref as
842 a pointer to the function which implements the routine. This is simply
843 a direct call to newXSUB(). Returns a reference to the installed
846 The $filename parameter is used by Perl to identify the source file for
847 the function if required by die(), caller() or the debugger. If
848 $filename is not defined then "DynaLoader" will be used.
857 This is the normal entry point for automatic dynamic loading in Perl.
859 It performs the following actions:
865 locates an auto/$module directory by searching @INC
869 uses dl_findfile() to determine the filename to load
873 sets @dl_require_symbols to C<("boot_$module")>
877 executes an F<auto/$module/$module.bs> file if it exists
878 (typically used to add to @dl_resolve_using any files which
879 are required to load the module on the current platform)
883 calls dl_load_flags() to determine how to load the file.
887 calls dl_load_file() to load the file
891 calls dl_undef_symbols() and warns if any symbols are undefined
895 calls dl_find_symbol() for "boot_$module"
899 calls dl_install_xsub() to install it as "${module}::bootstrap"
903 calls &{"${module}::bootstrap"} to bootstrap the module (actually
904 it uses the function reference returned by dl_install_xsub for speed)
913 Tim Bunce, 11 August 1994.
915 This interface is based on the work and comments of (in no particular
916 order): Larry Wall, Robert Sanders, Dean Roehrich, Jeff Okamoto, Anno
917 Siegel, Thomas Neumann, Paul Marquess, Charles Bailey, myself and others.
919 Larry Wall designed the elegant inherited bootstrap mechanism and
920 implemented the first Perl 5 dynamic loader using it.
922 Solaris global loading added by Nick Ing-Simmons with design/coding
923 assistance from Tim Bunce, January 1996.