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
90 *AUTOLOAD = \&AutoLoader::AUTOLOAD;
94 # enable debug/trace messages from DynaLoader perl code
95 $dl_debug = $ENV{PERL_DL_DEBUG} || 0 unless defined $dl_debug;
98 # Flags to alter dl_load_file behaviour. Assigned bits:
99 # 0x01 make symbols available for linking later dl_load_file's.
100 # (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL))
101 # (ignored under VMS; effect is built-in to image linking)
103 # This is called as a class method $module->dl_load_flags. The
104 # definition here will be inherited and result on "default" loading
105 # behaviour unless a sub-class of DynaLoader defines its own version.
108 sub dl_load_flags { 0x00 }
110 # ($dl_dlext, $dlsrc)
111 # = @Config::Config{'dlext', 'dlsrc'};
114 $dl_dlext = $Config::Config{'dlext'};
115 $dl_so = $Config::Config{'so'};
116 print OUT " (\$dl_dlext, \$dlsrc) = ('$dl_dlext', ",
117 to_string($Config::Config{'dlsrc'}), ")\n;";
119 print OUT expand_os_specific(<<'EOT');
122 # Some systems need special handling to expand file specifications
123 # (VMS support by Charles Bailey <bailey@HMIVAX.HUMGEN.UPENN.EDU>)
124 # See dl_expandspec() for more details. Should be harmless but
125 # inefficient to define on systems that don't need it.
126 $Is_VMS = $^O eq 'VMS';
128 $do_expand = <<$^O-eq-VMS>>1<<|$^O-eq-VMS>>0<</$^O-eq-VMS>>;
132 $Mac_FS = eval { require Mac::FileSpec::Unixish };
135 @dl_require_symbols = (); # names of symbols we need
136 @dl_resolve_using = (); # names of files to link with
137 @dl_library_path = (); # path to look for files
139 #XSLoader.pm may have added elements before we were required
140 #@dl_shared_objects = (); # shared objects for symbols we have
141 #@dl_librefs = (); # things we have loaded
142 #@dl_modules = (); # Modules we have loaded
144 # This is a fix to support DLD's unfortunate desire to relink -lc
145 @dl_resolve_using = dl_findfile('-lc') if $dlsrc eq "dl_dld.xs";
149 my $cfg_dl_library_path = <<'EOT';
150 push(@dl_library_path, split(' ', $Config::Config{libpth}));
153 sub dquoted_comma_list {
154 join(", ", map {'"'.quotemeta($_).'"'} @_);
157 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS}) {
158 eval $cfg_dl_library_path;
159 if (!$ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
160 my $dl_library_path = dquoted_comma_list(@dl_library_path);
162 # The below \@dl_library_path has been expanded (%Config) in Perl build time.
164 \@dl_library_path = ($dl_library_path);
171 # Initialise \@dl_library_path with the 'standard' library path
172 # for this platform as determined by Configure.
180 my $ldlibpthname_defined;
183 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS}) {
184 $ldlibpthname = to_string($Config::Config{ldlibpthname});
185 $ldlibpthname_defined = to_string(defined $Config::Config{ldlibpthname} ? 1 : 0);
186 $pthsep = to_string($Config::Config{path_sep});
189 $ldlibpthname = q($Config::Config{ldlibpthname});
190 $ldlibpthname_defined = q(defined $Config::Config{ldlibpthname});
191 $pthsep = q($Config::Config{path_sep});
194 my \$ldlibpthname = $ldlibpthname;
195 my \$ldlibpthname_defined = $ldlibpthname_defined;
196 my \$pthsep = $pthsep;
200 my $env_dl_library_path = <<'EOT';
201 if ($ldlibpthname_defined &&
202 exists $ENV{$ldlibpthname}) {
203 push(@dl_library_path, split(/$pthsep/, $ENV{$ldlibpthname}));
206 # E.g. HP-UX supports both its native SHLIB_PATH *and* LD_LIBRARY_PATH.
208 if ($ldlibpthname_defined &&
209 $ldlibpthname ne 'LD_LIBRARY_PATH' &&
210 exists $ENV{LD_LIBRARY_PATH}) {
211 push(@dl_library_path, split(/$pthsep/, $ENV{LD_LIBRARY_PATH}));
215 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS} && $ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
216 eval $env_dl_library_path;
220 # Add to \@dl_library_path any extra directories we can gather from environment
228 if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS} && $ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
229 my $dl_library_path = dquoted_comma_list(@dl_library_path);
231 # The below \@dl_library_path has been expanded (%Config, %ENV)
232 # in Perl build time.
234 \@dl_library_path = ($dl_library_path);
240 # following long string contains $^O-specific stuff, which is factored out
241 print OUT expand_os_specific(<<'EOT');
242 # No prizes for guessing why we don't say 'bootstrap DynaLoader;' here.
243 # NOTE: All dl_*.xs (including dl_none.xs) define a dl_error() XSUB
244 boot_DynaLoader('DynaLoader') if defined(&boot_DynaLoader) &&
248 print STDERR "DynaLoader.pm loaded (@INC, @dl_library_path)\n";
249 print STDERR "DynaLoader not linked into this perl\n"
250 unless defined(&boot_DynaLoader);
253 1; # End of main code
256 sub croak { require Carp; Carp::croak(@_) }
258 sub bootstrap_inherit {
260 local *isa = *{"$module\::ISA"};
261 local @isa = (@isa, 'DynaLoader');
262 # Cannot goto due to delocalization. Will report errors on a wrong line?
266 # The bootstrap function cannot be autoloaded (without complications)
267 # so we define it here:
270 # use local vars to enable $module.bs script to edit values
272 local($module) = $args[0];
277 Carp::confess("Usage: DynaLoader::bootstrap(module)");
280 # A common error on platforms which don't support dynamic loading.
281 # Since it's fatal and potentially confusing we give a detailed message.
282 croak("Can't load module $module, dynamic loading not available in this perl.\n".
283 " (You may need to build a new perl executable which either supports\n".
284 " dynamic loading or has the $module module statically linked into it.)\n")
285 unless defined(&dl_load_file);
289 # Can dynaload, but cannot dynaload Perl modules...
290 die 'Dynaloaded Perl modules are not available in this build of Perl' if $OS2::is_static;
293 my @modparts = split(/::/,$module);
294 my $modfname = $modparts[-1];
296 # Some systems have restrictions on files names for DLL's etc.
297 # mod2fname returns appropriate file base name (typically truncated)
298 # It may also edit @modparts if required.
299 $modfname = &mod2fname(\@modparts) if defined &mod2fname;
302 # Truncate the module name to 8.3 format for NetWare
303 if ((length($modfname) > 8)) {
304 $modfname = substr($modfname, 0, 8);
308 my $modpname = join(<<$^O-eq-MacOS>>':'<<|$^O-eq-MacOS>>'/'<</$^O-eq-MacOS>>,@modparts);
310 print STDERR "DynaLoader::bootstrap for $module ",
311 <<$^O-eq-MacOS>> "(:auto:$modpname:$modfname.<<=$dl_dlext>>)\n"
312 <<|$^O-eq-MacOS>>"(auto/$modpname/$modfname.<<=$dl_dlext>>)\n"<</$^O-eq-MacOS>>
316 <<$^O-eq-VMS>>chop($_ = VMS::Filespec::unixpath($_));<</$^O-eq-VMS>>
319 if ($Mac_FS && ! -d $path) {
320 $path = Mac::FileSpec::Unixish::nativize($path);
322 $path .= ":" unless /:$/;
323 my $dir = "${path}auto:$modpname";
325 my $dir = "$_/auto/$modpname";
328 next unless -d $dir; # skip over uninteresting directories
330 # check for common cases to avoid autoload of dl_findfile
331 my $try = <<$^O-eq-MacOS>> "$dir:$modfname.<<=$dl_dlext>>" <<|$^O-eq-MacOS>> "$dir/$modfname.<<=$dl_dlext>>"<</$^O-eq-MacOS>>;
332 last if $file = <<$^O-eq-VMS>>($do_expand) ? dl_expandspec($try) : ((-f $try) && $try);
333 <<|$^O-eq-VMS>>(-f $try) && $try;
336 # no luck here, save dir for possible later dl_findfile search
339 # last resort, let dl_findfile have a go in all known locations
340 $file = dl_findfile(map("-L$_",@dirs,@INC), $modfname) unless $file;
342 croak("Can't locate loadable object for module $module in \@INC (\@INC contains: @INC)")
343 unless $file; # wording similar to error from 'require'
345 <<$^O-eq-VMS>>$file = uc($file) if $Config::Config{d_vms_case_sensitive_symbols};<</$^O-eq-VMS>>
346 my $bootname = "boot_$module";
347 $bootname =~ s/\W/_/g;
348 @dl_require_symbols = ($bootname);
350 # Execute optional '.bootstrap' perl script for this module.
351 # The .bs file can be used to configure @dl_resolve_using etc to
352 # match the needs of the individual module on this architecture.
354 $bs =~ s/(\.\w+)?(;\d*)?$/\.bs/; # look for .bs 'beside' the library
355 if (-s $bs) { # only read file if it's not empty
356 print STDERR "BS: $bs ($^O, $dlsrc)\n" if $dl_debug;
358 warn "$bs: $@\n" if $@;
364 if ($boot_symbol_ref = dl_find_symbol(0, $bootname)) {
365 goto boot; #extension library has already been loaded, e.g. darwin
369 # Many dynamic extension loading problems will appear to come from
370 # this section of code: XYZ failed at line 123 of DynaLoader.pm.
371 # Often these errors are actually occurring in the initialisation
372 # C code of the extension XS file. Perl reports the error as being
373 # in this perl code simply because this was the last perl code
376 my $libref = dl_load_file($file, $module->dl_load_flags) or
377 croak("Can't load '$file' for module $module: ".dl_error());
379 push(@dl_librefs,$libref); # record loaded object
381 my @unresolved = dl_undef_symbols();
384 Carp::carp("Undefined symbols present after loading $file: @unresolved\n");
387 $boot_symbol_ref = dl_find_symbol($libref, $bootname) or
388 croak("Can't find '$bootname' symbol in $file\n");
390 push(@dl_modules, $module); # record loaded module
393 my $xs = dl_install_xsub("${module}::bootstrap", $boot_symbol_ref, $file);
395 # See comment block above
397 push(@dl_shared_objects, $file); # record files loaded
403 #sub _check_file { # private utility to handle dl_expandspec vs -f tests
405 # return $file if (!$do_expand && -f $file); # the common case
406 # return $file if ( $do_expand && ($file=dl_expandspec($file)));
411 # Let autosplit and the autoloader deal with these functions:
416 # Read ext/DynaLoader/DynaLoader.doc for detailed information.
417 # This function does not automatically consider the architecture
418 # or the perl library auto directories.
420 my (@dirs, $dir); # which directories to search
421 my (@found); # full paths to real files we have found
422 #my $dl_ext= <<=to_string($Config::Config{'dlext'})>>; # $Config::Config{'dlext'} suffix for perl extensions
423 #my $dl_so = <<=to_string($Config::Config{'so'})>>; # $Config::Config{'so'} suffix for shared libraries
425 print STDERR "dl_findfile(@args)\n" if $dl_debug;
427 # accumulate directories but process files as they appear
428 arg: foreach(@args) {
429 # Special fast case: full filepath requires no search
431 if (m%[:>/\]]% && -f $_) {
432 push(@found,dl_expandspec(VMS::Filespec::vmsify($_)));
433 last arg unless wantarray;
440 last arg unless wantarray;
446 last arg unless wantarray;
451 # Deal with directories first:
452 # Using a -L prefix is the preferred option (faster and more robust)
453 if (m:^-L:) { s/^-L//; push(@dirs, $_); next; }
456 # Otherwise we try to try to spot directories by a heuristic
457 # (this is a more complicated issue than it first appears)
458 if (m/:/ && -d $_) { push(@dirs, $_); next; }
459 # Only files should get this far...
460 my(@names, $name); # what filenames to look for
463 foreach $dir (@dirs, @dl_library_path) {
465 $dir =~ s/^([^:]+)$/:$1/;
467 foreach $name (@names) {
468 my($file) = "$dir:$name";
469 print STDERR " checking in $dir for $name\n" if $dl_debug;
472 next arg; # no need to look any further
479 # Otherwise we try to try to spot directories by a heuristic
480 # (this is a more complicated issue than it first appears)
481 if (m:/: && -d $_) { push(@dirs, $_); next; }
484 # VMS: we may be using native VMS directory syntax instead of
485 # Unix emulation, so check this as well
486 if (/[:>\]]/ && -d $_) { push(@dirs, $_); next; }
489 # Only files should get this far...
490 my(@names, $name); # what filenames to look for
491 if (m:-l: ) { # convert -lname to appropriate library name
493 push(@names,"lib$_.<<=to_string($Config::Config{'so'})>>");
494 push(@names,"lib$_.a");
495 } else { # Umm, a bare name. Try various alternatives:
496 # these should be ordered with the most likely first
497 push(@names,"$_.<<=$dl_dlext>>") unless m/\.<<=$dl_dlext>>$/o;
498 push(@names,"$_.<<=$dl_so>>") unless m/\.<<=$dl_so>>$/o;
499 push(@names,"lib$_.<<=$dl_so>>") unless m:/:;
500 push(@names,"$_.a") if !m/\.a$/ and $dlsrc eq "dl_dld.xs";
506 if ($0 =~ /^([a-z]):/i) {
508 @dirs = map { "$drive:$_" } @dirs;
509 @dl_library_path = map { "$drive:$_" } @dl_library_path;
512 foreach $dir (@dirs, @dl_library_path) {
515 chop($dir = VMS::Filespec::unixpath($dir));
517 foreach $name (@names) {
518 my($file) = "$dir$dirsep$name";
519 print STDERR " checking in $dir for $name\n" if $dl_debug;
520 $file = ($do_expand) ? dl_expandspec($file) : (-f $file && $file);
521 #$file = _check_file($file);
524 next arg; # no need to look any further
531 print STDERR " dl_findfile ignored non-existent directory: $_\n" unless -d $_;
533 print STDERR "dl_findfile found: @found\n";
535 return $found[0] unless wantarray;
542 # Optional function invoked if DynaLoader.pm sets $do_expand.
543 # Most systems do not require or use this function.
544 # Some systems may implement it in the dl_*.xs file in which case
545 # this autoload version will not be called but is harmless.
547 # This function is designed to deal with systems which treat some
548 # 'filenames' in a special way. For example VMS 'Logical Names'
549 # (something like unix environment variables - but different).
550 # This function should recognise such names and expand them into
552 # Must return undef if $spec is invalid or file does not exist.
554 my $file = $spec; # default output to input
557 # dl_expandspec should be defined in dl_vms.xs
559 Carp::croak("dl_expandspec: should be defined in XS file!\n");
561 return undef unless -f $file;
563 print STDERR "dl_expandspec($spec) => $file\n" if $dl_debug;
567 sub dl_find_symbol_anywhere
571 foreach $libref (@dl_librefs) {
572 my $symref = dl_find_symbol($libref,$sym);
573 return $symref if $symref;
580 DynaLoader - Dynamically load C libraries into Perl code
586 @ISA = qw(... DynaLoader ...);
587 bootstrap YourPackage;
589 # optional method for 'global' loading
590 sub dl_load_flags { 0x01 }
595 This document defines a standard generic interface to the dynamic
596 linking mechanisms available on many platforms. Its primary purpose is
597 to implement automatic dynamic loading of Perl modules.
599 This document serves as both a specification for anyone wishing to
600 implement the DynaLoader for a new platform and as a guide for
601 anyone wishing to use the DynaLoader directly in an application.
603 The DynaLoader is designed to be a very simple high-level
604 interface that is sufficiently general to cover the requirements
605 of SunOS, HP-UX, NeXT, Linux, VMS and other platforms.
607 It is also hoped that the interface will cover the needs of OS/2, NT
608 etc and also allow pseudo-dynamic linking (using C<ld -A> at runtime).
610 It must be stressed that the DynaLoader, by itself, is practically
611 useless for accessing non-Perl libraries because it provides almost no
612 Perl-to-C 'glue'. There is, for example, no mechanism for calling a C
613 library function or supplying arguments. A C::DynaLib module
614 is available from CPAN sites which performs that function for some
615 common system types. And since the year 2000, there's also Inline::C,
616 a module that allows you to write Perl subroutines in C. Also available
617 from your local CPAN site.
619 DynaLoader Interface Summary
629 bootstrap($modulename) Perl
630 @filepaths = dl_findfile(@names) Perl
631 $flags = $modulename->dl_load_flags Perl
632 $symref = dl_find_symbol_anywhere($symbol) Perl
634 $libref = dl_load_file($filename, $flags) C
635 $status = dl_unload_file($libref) C
636 $symref = dl_find_symbol($libref, $symbol) C
637 @symbols = dl_undef_symbols() C
638 dl_install_xsub($name, $symref [, $filename]) C
639 $message = dl_error C
643 =item @dl_library_path
645 The standard/default list of directories in which dl_findfile() will
646 search for libraries etc. Directories are searched in order:
647 $dl_library_path[0], [1], ... etc
649 @dl_library_path is initialised to hold the list of 'normal' directories
650 (F</usr/lib>, etc) determined by B<Configure> (C<$Config{'libpth'}>). This should
651 ensure portability across a wide range of platforms.
653 @dl_library_path should also be initialised with any other directories
654 that can be determined from the environment at runtime (such as
655 LD_LIBRARY_PATH for SunOS).
657 After initialisation @dl_library_path can be manipulated by an
658 application using push and unshift before calling dl_findfile().
659 Unshift can be used to add directories to the front of the search order
660 either to save search time or to override libraries with the same name
661 in the 'normal' directories.
663 The load function that dl_load_file() calls may require an absolute
664 pathname. The dl_findfile() function and @dl_library_path can be
665 used to search for and return the absolute pathname for the
666 library/object that you wish to load.
668 =item @dl_resolve_using
670 A list of additional libraries or other shared objects which can be
671 used to resolve any undefined symbols that might be generated by a
672 later call to load_file().
674 This is only required on some platforms which do not handle dependent
675 libraries automatically. For example the Socket Perl extension
676 library (F<auto/Socket/Socket.so>) contains references to many socket
677 functions which need to be resolved when it's loaded. Most platforms
678 will automatically know where to find the 'dependent' library (e.g.,
679 F</usr/lib/libsocket.so>). A few platforms need to be told the
680 location of the dependent library explicitly. Use @dl_resolve_using
685 @dl_resolve_using = dl_findfile('-lsocket');
687 =item @dl_require_symbols
689 A list of one or more symbol names that are in the library/object file
690 to be dynamically loaded. This is only required on some platforms.
694 An array of the handles returned by successful calls to dl_load_file(),
695 made by bootstrap, in the order in which they were loaded.
696 Can be used with dl_find_symbol() to look for a symbol in any of
701 An array of module (package) names that have been bootstrap'ed.
703 =item @dl_shared_objects
705 An array of file names for the shared objects that were loaded.
711 $message = dl_error();
713 Error message text from the last failed DynaLoader function. Note
714 that, similar to errno in unix, a successful function call does not
717 Implementations should detect the error as soon as it occurs in any of
718 the other functions and save the corresponding message for later
719 retrieval. This will avoid problems on some platforms (such as SunOS)
720 where the error message is very temporary (e.g., dlerror()).
724 Internal debugging messages are enabled when $dl_debug is set true.
725 Currently setting $dl_debug only affects the Perl side of the
726 DynaLoader. These messages should help an application developer to
727 resolve any DynaLoader usage problems.
729 $dl_debug is set to C<$ENV{'PERL_DL_DEBUG'}> if defined.
731 For the DynaLoader developer/porter there is a similar debugging
732 variable added to the C code (see dlutils.c) and enabled if Perl was
733 built with the B<-DDEBUGGING> flag. This can also be set via the
734 PERL_DL_DEBUG environment variable. Set to 1 for minimal information or
741 @filepaths = dl_findfile(@names)
743 Determine the full paths (including file suffix) of one or more
744 loadable files given their generic names and optionally one or more
745 directories. Searches directories in @dl_library_path by default and
746 returns an empty list if no files were found.
748 Names can be specified in a variety of platform independent forms. Any
749 names in the form B<-lname> are converted into F<libname.*>, where F<.*> is
750 an appropriate suffix for the platform.
752 If a name does not already have a suitable prefix and/or suffix then
753 the corresponding file will be searched for by trying combinations of
754 prefix and suffix appropriate to the platform: "$name.o", "lib$name.*"
757 If any directories are included in @names they are searched before
758 @dl_library_path. Directories may be specified as B<-Ldir>. Any other
759 names are treated as filenames to be searched for.
761 Using arguments of the form C<-Ldir> and C<-lname> is recommended.
765 @dl_resolve_using = dl_findfile(qw(-L/usr/5lib -lposix));
768 =item dl_expandspec()
772 $filepath = dl_expandspec($spec)
774 Some unusual systems, such as VMS, require special filename handling in
775 order to deal with symbolic names for files (i.e., VMS's Logical Names).
777 To support these systems a dl_expandspec() function can be implemented
778 either in the F<dl_*.xs> file or code can be added to the autoloadable
779 dl_expandspec() function in F<DynaLoader.pm>. See F<DynaLoader.pm> for
786 $libref = dl_load_file($filename, $flags)
788 Dynamically load $filename, which must be the path to a shared object
789 or library. An opaque 'library reference' is returned as a handle for
790 the loaded object. Returns undef on error.
792 The $flags argument to alters dl_load_file behaviour.
795 0x01 make symbols available for linking later dl_load_file's.
796 (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL))
797 (ignored under VMS; this is a normal part of image linking)
799 (On systems that provide a handle for the loaded object such as SunOS
800 and HPUX, $libref will be that handle. On other systems $libref will
801 typically be $filename or a pointer to a buffer containing $filename.
802 The application should not examine or alter $libref in any way.)
804 This is the function that does the real work. It should use the
805 current values of @dl_require_symbols and @dl_resolve_using if required.
807 SunOS: dlopen($filename)
808 HP-UX: shl_load($filename)
809 Linux: dld_create_reference(@dl_require_symbols); dld_link($filename)
810 NeXT: rld_load($filename, @dl_resolve_using)
811 VMS: lib$find_image_symbol($filename,$dl_require_symbols[0])
813 (The dlopen() function is also used by Solaris and some versions of
814 Linux, and is a common choice when providing a "wrapper" on other
815 mechanisms as is done in the OS/2 port.)
817 =item dl_unload_file()
821 $status = dl_unload_file($libref)
823 Dynamically unload $libref, which must be an opaque 'library reference' as
824 returned from dl_load_file. Returns one on success and zero on failure.
826 This function is optional and may not necessarily be provided on all platforms.
827 If it is defined, it is called automatically when the interpreter exits for
828 every shared object or library loaded by DynaLoader::bootstrap. All such
829 library references are stored in @dl_librefs by DynaLoader::Bootstrap as it
830 loads the libraries. The files are unloaded in last-in, first-out order.
832 This unloading is usually necessary when embedding a shared-object perl (e.g.
833 one configured with -Duseshrplib) within a larger application, and the perl
834 interpreter is created and destroyed several times within the lifetime of the
835 application. In this case it is possible that the system dynamic linker will
836 unload and then subsequently reload the shared libperl without relocating any
837 references to it from any files DynaLoaded by the previous incarnation of the
838 interpreter. As a result, any shared objects opened by DynaLoader may point to
839 a now invalid 'ghost' of the libperl shared object, causing apparently random
840 memory corruption and crashes. This behaviour is most commonly seen when using
841 Apache and mod_perl built with the APXS mechanism.
843 SunOS: dlclose($libref)
849 (The dlclose() function is also used by Solaris and some versions of
850 Linux, and is a common choice when providing a "wrapper" on other
851 mechanisms as is done in the OS/2 port.)
853 =item dl_load_flags()
857 $flags = dl_load_flags $modulename;
859 Designed to be a method call, and to be overridden by a derived class
860 (i.e. a class which has DynaLoader in its @ISA). The definition in
861 DynaLoader itself returns 0, which produces standard behavior from
864 =item dl_find_symbol()
868 $symref = dl_find_symbol($libref, $symbol)
870 Return the address of the symbol $symbol or C<undef> if not found. If the
871 target system has separate functions to search for symbols of different
872 types then dl_find_symbol() should search for function symbols first and
875 The exact manner in which the address is returned in $symref is not
876 currently defined. The only initial requirement is that $symref can
877 be passed to, and understood by, dl_install_xsub().
879 SunOS: dlsym($libref, $symbol)
880 HP-UX: shl_findsym($libref, $symbol)
881 Linux: dld_get_func($symbol) and/or dld_get_symbol($symbol)
882 NeXT: rld_lookup("_$symbol")
883 VMS: lib$find_image_symbol($libref,$symbol)
886 =item dl_find_symbol_anywhere()
890 $symref = dl_find_symbol_anywhere($symbol)
892 Applies dl_find_symbol() to the members of @dl_librefs and returns
893 the first match found.
895 =item dl_undef_symbols()
899 @symbols = dl_undef_symbols()
901 Return a list of symbol names which remain undefined after load_file().
902 Returns C<()> if not known. Don't worry if your platform does not provide
903 a mechanism for this. Most do not need it and hence do not provide it,
904 they just return an empty list.
907 =item dl_install_xsub()
911 dl_install_xsub($perl_name, $symref [, $filename])
913 Create a new Perl external subroutine named $perl_name using $symref as
914 a pointer to the function which implements the routine. This is simply
915 a direct call to newXSUB(). Returns a reference to the installed
918 The $filename parameter is used by Perl to identify the source file for
919 the function if required by die(), caller() or the debugger. If
920 $filename is not defined then "DynaLoader" will be used.
929 This is the normal entry point for automatic dynamic loading in Perl.
931 It performs the following actions:
937 locates an auto/$module directory by searching @INC
941 uses dl_findfile() to determine the filename to load
945 sets @dl_require_symbols to C<("boot_$module")>
949 executes an F<auto/$module/$module.bs> file if it exists
950 (typically used to add to @dl_resolve_using any files which
951 are required to load the module on the current platform)
955 calls dl_load_flags() to determine how to load the file.
959 calls dl_load_file() to load the file
963 calls dl_undef_symbols() and warns if any symbols are undefined
967 calls dl_find_symbol() for "boot_$module"
971 calls dl_install_xsub() to install it as "${module}::bootstrap"
975 calls &{"${module}::bootstrap"} to bootstrap the module (actually
976 it uses the function reference returned by dl_install_xsub for speed)
985 Tim Bunce, 11 August 1994.
987 This interface is based on the work and comments of (in no particular
988 order): Larry Wall, Robert Sanders, Dean Roehrich, Jeff Okamoto, Anno
989 Siegel, Thomas Neumann, Paul Marquess, Charles Bailey, myself and others.
991 Larry Wall designed the elegant inherited bootstrap mechanism and
992 implemented the first Perl 5 dynamic loader using it.
994 Solaris global loading added by Nick Ing-Simmons with design/coding
995 assistance from Tim Bunce, January 1996.
1000 close OUT or die $!;