This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
Bunch of doc patches from Stas; plus regen.
[perl5.git] / ext / DynaLoader / DynaLoader_pm.PL
CommitLineData
03c9e98c
GS
1use Config;
2
3sub to_string {
4 my ($value) = @_;
146174a9 5 $value =~ s/\\/\\\\/g;
03c9e98c
GS
6 $value =~ s/'/\\'/g;
7 return "'$value'";
8}
9
10unlink "DynaLoader.pm" if -f "DynaLoader.pm";
11open OUT, ">DynaLoader.pm" or die $!;
12print OUT <<'EOT';
13
d0a5ed9f 14# Generated from DynaLoader.pm.PL
03c9e98c 15
a0d0e21e
LW
16package DynaLoader;
17
8e07c86e
AD
18# And Gandalf said: 'Many folk like to know beforehand what is to
19# be set on the table; but those who have laboured to prepare the
20# feast like to keep their secret; for wonder makes the words of
21# praise louder.'
22
6662521e 23# (Quote from Tolkien suggested by Anno Siegel.)
8e07c86e
AD
24#
25# See pod text at end of file for documentation.
26# See also ext/DynaLoader/README in source tree for other information.
27#
28# Tim.Bunce@ig.co.uk, August 1994
29
632a9a7f
A
30use vars qw($VERSION *AUTOLOAD);
31
32$VERSION = 1.04; # avoid typo warning
dc848c6f 33
dc848c6f
PP
34require AutoLoader;
35*AUTOLOAD = \&AutoLoader::AUTOLOAD;
8e07c86e 36
7e9f3af8
JH
37use Config;
38
fb73857a
PP
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.
44require Carp if $] < 5.00450;
45
8e07c86e
AD
46# enable debug/trace messages from DynaLoader perl code
47$dl_debug = $ENV{PERL_DL_DEBUG} || 0 unless defined $dl_debug;
48
ff7f3c60
NIS
49#
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))
f86702cc 53# (ignored under VMS; effect is built-in to image linking)
ff7f3c60
NIS
54#
55# This is called as a class method $module->dl_load_flags. The
56# definition here will be inherited and result on "default" loading
57# behaviour unless a sub-class of DynaLoader defines its own version.
58#
59
60sub dl_load_flags { 0x00 }
61
03c9e98c
GS
62# ($dl_dlext, $dlsrc)
63# = @Config::Config{'dlext', 'dlsrc'};
64EOT
65
66print OUT " (\$dl_dlext, \$dlsrc) = (",
67 to_string($Config::Config{'dlext'}), ",",
68 to_string($Config::Config{'dlsrc'}), ")\n;" ;
ff7f3c60 69
03c9e98c 70print OUT <<'EOT';
8e07c86e
AD
71
72# Some systems need special handling to expand file specifications
73# (VMS support by Charles Bailey <bailey@HMIVAX.HUMGEN.UPENN.EDU>)
74# See dl_expandspec() for more details. Should be harmless but
75# inefficient to define on systems that don't need it.
632a9a7f
A
76$Is_VMS = $^O eq 'VMS';
77$do_expand = $Is_VMS;
78$Is_MacOS = $^O eq 'MacOS';
8e07c86e 79
d5201bd2
JH
80my $Mac_FS;
81$Mac_FS = eval { require Mac::FileSpec::Unixish } if $Is_MacOS;
82
8e07c86e
AD
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
bff25830
DM
86
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
8e07c86e
AD
90
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";
93
d0a5ed9f 94EOT
03c9e98c 95
d0a5ed9f 96my $cfg_dl_library_path = <<'EOT';
632a9a7f 97push(@dl_library_path, split(' ', $Config::Config{libpth}));
03c9e98c
GS
98EOT
99
d0a5ed9f
JH
100sub dquoted_comma_list {
101 join(", ", map {qq("$_")} @_);
102}
03c9e98c 103
d0a5ed9f
JH
104if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS}) {
105 eval $cfg_dl_library_path;
106 if (!$ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
107 my $dl_library_path = dquoted_comma_list(@dl_library_path);
108 print OUT <<EOT;
7e9f3af8 109# The below \@dl_library_path has been expanded (%Config) in Perl build time.
d0a5ed9f
JH
110
111\@dl_library_path = ($dl_library_path);
112
113EOT
114 }
115}
116else {
117 print OUT <<EOT;
118# Initialise \@dl_library_path with the 'standard' library path
119# for this platform as determined by Configure.
120
121$cfg_dl_library_path
122
123EOT
124}
8e07c86e 125
8225e35f 126my $ldlibpthname;
7e9f3af8 127my $ldlibpthname_defined;
8225e35f
JH
128my $pthsep;
129
130if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS}) {
7e9f3af8
JH
131 $ldlibpthname = $Config::Config{ldlibpthname};
132 $ldlibpthname_defined = defined $Config::Config{ldlibpthname} ? 1 : 0;
133 $pthsep = $Config::Config{path_sep};
8225e35f
JH
134}
135else {
7e9f3af8
JH
136 $ldlibpthname = q($Config::Config{ldlibpthname});
137 $ldlibpthname_defined = q(defined $Config::Config{ldlibpthname});
138 $pthsep = q($Config::Config{path_sep});
8225e35f 139 print OUT <<EOT;
7e9f3af8
JH
140my \$ldlibpthname = $ldlibpthname;
141my \$ldlibpthname_defined = $ldlibpthname_defined;
142my \$pthsep = $pthsep;
8225e35f
JH
143
144EOT
145}
146
7e9f3af8
JH
147my $env_dl_library_path = <<'EOT';
148if ($ldlibpthname_defined &&
149 exists $ENV{$ldlibpthname}) {
150 push(@dl_library_path, split(/$pthsep/, $ENV{$ldlibpthname}));
8225e35f
JH
151}
152
5cf1d1f1 153# E.g. HP-UX supports both its native SHLIB_PATH *and* LD_LIBRARY_PATH.
8225e35f 154
7e9f3af8
JH
155if ($ldlibpthname_defined &&
156 $ldlibpthname ne 'LD_LIBRARY_PATH' &&
157 exists $ENV{LD_LIBRARY_PATH}) {
158 push(@dl_library_path, split(/$pthsep/, $ENV{LD_LIBRARY_PATH}));
d0a5ed9f 159}
e6197cab
NC
160EOT
161
d0a5ed9f
JH
162if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS} && $ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
163 eval $env_dl_library_path;
e6197cab 164}
d0a5ed9f
JH
165else {
166 print OUT <<EOT;
167# Add to \@dl_library_path any extra directories we can gather from environment
168# during runtime.
e6197cab 169
d0a5ed9f
JH
170$env_dl_library_path
171
172EOT
e6197cab
NC
173}
174
d0a5ed9f
JH
175if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS} && $ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
176 my $dl_library_path = dquoted_comma_list(@dl_library_path);
177 print OUT <<EOT;
7e9f3af8
JH
178# The below \@dl_library_path has been expanded (%Config, %ENV)
179# in Perl build time.
d0a5ed9f
JH
180
181\@dl_library_path = ($dl_library_path);
182
183EOT
146174a9 184}
8e07c86e 185
d0a5ed9f 186print OUT <<'EOT';
8e07c86e 187# No prizes for guessing why we don't say 'bootstrap DynaLoader;' here.
b4cea227 188# NOTE: All dl_*.xs (including dl_none.xs) define a dl_error() XSUB
bb3913c7 189boot_DynaLoader('DynaLoader') if defined(&boot_DynaLoader) &&
b4cea227 190 !defined(&dl_error);
8e07c86e
AD
191
192if ($dl_debug) {
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);
196}
197
1981; # End of main code
199
200
fb73857a
PP
201sub croak { require Carp; Carp::croak(@_) }
202
146174a9
CB
203sub bootstrap_inherit {
204 my $module = $_[0];
205 local *isa = *{"$module\::ISA"};
206 local @isa = (@isa, 'DynaLoader');
207 # Cannot goto due to delocalization. Will report errors on a wrong line?
208 bootstrap(@_);
209}
210
8e07c86e
AD
211# The bootstrap function cannot be autoloaded (without complications)
212# so we define it here:
213
214sub bootstrap {
215 # use local vars to enable $module.bs script to edit values
216 local(@args) = @_;
217 local($module) = $args[0];
218 local(@dirs, $file);
219
fb73857a
PP
220 unless ($module) {
221 require Carp;
222 Carp::confess("Usage: DynaLoader::bootstrap(module)");
223 }
8e07c86e
AD
224
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.
fb73857a 227 croak("Can't load module $module, dynamic loading not available in this perl.\n".
8e07c86e
AD
228 " (You may need to build a new perl executable which either supports\n".
229 " dynamic loading or has the $module module statically linked into it.)\n")
230 unless defined(&dl_load_file);
231
232 my @modparts = split(/::/,$module);
233 my $modfname = $modparts[-1];
234
235 # Some systems have restrictions on files names for DLL's etc.
236 # mod2fname returns appropriate file base name (typically truncated)
237 # It may also edit @modparts if required.
238 $modfname = &mod2fname(\@modparts) if defined &mod2fname;
239
1a95e36d 240 # Truncate the module name to 8.3 format for NetWare
f355267c
JH
241 if (($^O eq 'NetWare') && (length($modfname) > 8)) {
242 $modfname = substr($modfname, 0, 8);
243 }
244
146174a9 245 my $modpname = join(($Is_MacOS ? ':' : '/'),@modparts);
8e07c86e
AD
246
247 print STDERR "DynaLoader::bootstrap for $module ",
146174a9 248 ($Is_MacOS
6662521e
GS
249 ? "(:auto:$modpname:$modfname.$dl_dlext)\n" :
250 "(auto/$modpname/$modfname.$dl_dlext)\n")
146174a9 251 if $dl_debug;
8e07c86e
AD
252
253 foreach (@INC) {
54d6a3b3 254 chop($_ = VMS::Filespec::unixpath($_)) if $Is_VMS;
146174a9
CB
255 my $dir;
256 if ($Is_MacOS) {
e69a2255 257 my $path = $_;
5b865721 258 if ($Mac_FS && ! -d $path) {
d5201bd2
JH
259 $path = Mac::FileSpec::Unixish::nativize($path);
260 }
e69a2255
JH
261 $path .= ":" unless /:$/;
262 $dir = "${path}auto:$modpname";
146174a9
CB
263 } else {
264 $dir = "$_/auto/$modpname";
265 }
1a95e36d
JH
266
267 next unless -d $dir; # skip over uninteresting directories
268
8e07c86e 269 # check for common cases to avoid autoload of dl_findfile
146174a9 270 my $try = $Is_MacOS ? "$dir:$modfname.$dl_dlext" : "$dir/$modfname.$dl_dlext";
1a95e36d
JH
271 last if $file = ($do_expand) ? dl_expandspec($try) : ((-f $try) && $try);
272
8e07c86e 273 # no luck here, save dir for possible later dl_findfile search
fb73857a 274 push @dirs, $dir;
8e07c86e
AD
275 }
276 # last resort, let dl_findfile have a go in all known locations
fb73857a 277 $file = dl_findfile(map("-L$_",@dirs,@INC), $modfname) unless $file;
8e07c86e 278
fb73857a
PP
279 croak("Can't locate loadable object for module $module in \@INC (\@INC contains: @INC)")
280 unless $file; # wording similar to error from 'require'
8e07c86e 281
7e9f3af8 282 $file = uc($file) if $Is_VMS && $Config::Config{d_vms_case_sensitive_symbols};
8e07c86e
AD
283 my $bootname = "boot_$module";
284 $bootname =~ s/\W/_/g;
285 @dl_require_symbols = ($bootname);
286
287 # Execute optional '.bootstrap' perl script for this module.
288 # The .bs file can be used to configure @dl_resolve_using etc to
289 # match the needs of the individual module on this architecture.
290 my $bs = $file;
3f45a6dd 291 $bs =~ s/(\.\w+)?(;\d*)?$/\.bs/; # look for .bs 'beside' the library
8e07c86e 292 if (-s $bs) { # only read file if it's not empty
d404d5bf 293 print STDERR "BS: $bs ($^O, $dlsrc)\n" if $dl_debug;
8e07c86e
AD
294 eval { do $bs; };
295 warn "$bs: $@\n" if $@;
296 }
297
588cafc8
DM
298 my $boot_symbol_ref;
299
300 if ($^O eq 'darwin') {
301 if ($boot_symbol_ref = dl_find_symbol(0, $bootname)) {
302 goto boot; #extension library has already been loaded, e.g. darwin
303 }
304 }
305
8e07c86e
AD
306 # Many dynamic extension loading problems will appear to come from
307 # this section of code: XYZ failed at line 123 of DynaLoader.pm.
308 # Often these errors are actually occurring in the initialisation
309 # C code of the extension XS file. Perl reports the error as being
310 # in this perl code simply because this was the last perl code
311 # it executed.
312
ff7f3c60 313 my $libref = dl_load_file($file, $module->dl_load_flags) or
549a6b10 314 croak("Can't load '$file' for module $module: ".dl_error());
8e07c86e 315
ff7f3c60
NIS
316 push(@dl_librefs,$libref); # record loaded object
317
8e07c86e 318 my @unresolved = dl_undef_symbols();
fb73857a
PP
319 if (@unresolved) {
320 require Carp;
321 Carp::carp("Undefined symbols present after loading $file: @unresolved\n");
322 }
8e07c86e 323
588cafc8 324 $boot_symbol_ref = dl_find_symbol($libref, $bootname) or
fb73857a 325 croak("Can't find '$bootname' symbol in $file\n");
8e07c86e 326
ff7f3c60
NIS
327 push(@dl_modules, $module); # record loaded module
328
588cafc8
DM
329 boot:
330 my $xs = dl_install_xsub("${module}::bootstrap", $boot_symbol_ref, $file);
331
8e07c86e
AD
332 # See comment block above
333 &$xs(@args);
334}
335
336
fb73857a
PP
337#sub _check_file { # private utility to handle dl_expandspec vs -f tests
338# my($file) = @_;
339# return $file if (!$do_expand && -f $file); # the common case
340# return $file if ( $do_expand && ($file=dl_expandspec($file)));
341# return undef;
342#}
8e07c86e
AD
343
344
345# Let autosplit and the autoloader deal with these functions:
346__END__
347
348
349sub dl_findfile {
350 # Read ext/DynaLoader/DynaLoader.doc for detailed information.
351 # This function does not automatically consider the architecture
352 # or the perl library auto directories.
353 my (@args) = @_;
354 my (@dirs, $dir); # which directories to search
355 my (@found); # full paths to real files we have found
03c9e98c
GS
356EOT
357
358print OUT ' my $dl_ext= ' . to_string($Config::Config{'dlext'}) .
359 "; # \$Config::Config{'dlext'} suffix for perl extensions\n";
360print OUT ' my $dl_so = ' . to_string($Config::Config{'so'}) .
361 "; # \$Config::Config{'so'} suffix for shared libraries\n";
362
363print OUT <<'EOT';
8e07c86e
AD
364
365 print STDERR "dl_findfile(@args)\n" if $dl_debug;
366
367 # accumulate directories but process files as they appear
368 arg: foreach(@args) {
369 # Special fast case: full filepath requires no search
54d6a3b3
PP
370 if ($Is_VMS && m%[:>/\]]% && -f $_) {
371 push(@found,dl_expandspec(VMS::Filespec::vmsify($_)));
372 last arg unless wantarray;
373 next;
374 }
146174a9
CB
375 elsif ($Is_MacOS) {
376 if (m/:/ && -f $_) {
377 push(@found,$_);
378 last arg unless wantarray;
379 }
380 }
54d6a3b3 381 elsif (m:/: && -f $_ && !$do_expand) {
8e07c86e
AD
382 push(@found,$_);
383 last arg unless wantarray;
384 next;
385 }
386
387 # Deal with directories first:
388 # Using a -L prefix is the preferred option (faster and more robust)
389 if (m:^-L:) { s/^-L//; push(@dirs, $_); next; }
390
146174a9
CB
391 if ($Is_MacOS) {
392 # Otherwise we try to try to spot directories by a heuristic
393 # (this is a more complicated issue than it first appears)
394 if (m/:/ && -d $_) { push(@dirs, $_); next; }
395 # Only files should get this far...
396 my(@names, $name); # what filenames to look for
397 s/^-l//;
398 push(@names, $_);
399 foreach $dir (@dirs, @dl_library_path) {
400 next unless -d $dir;
401 $dir =~ s/^([^:]+)$/:$1/;
402 $dir =~ s/:$//;
403 foreach $name (@names) {
404 my($file) = "$dir:$name";
405 print STDERR " checking in $dir for $name\n" if $dl_debug;
406 if (-f $file) {
407 push(@found, $file);
408 next arg; # no need to look any further
409 }
410 }
411 }
412 next;
413 }
414
8e07c86e
AD
415 # Otherwise we try to try to spot directories by a heuristic
416 # (this is a more complicated issue than it first appears)
417 if (m:/: && -d $_) { push(@dirs, $_); next; }
418
7e9f3af8 419 # VMS: we may be using native VMS directory syntax instead of
8e07c86e 420 # Unix emulation, so check this as well
54d6a3b3 421 if ($Is_VMS && /[:>\]]/ && -d $_) { push(@dirs, $_); next; }
8e07c86e
AD
422
423 # Only files should get this far...
424 my(@names, $name); # what filenames to look for
425 if (m:-l: ) { # convert -lname to appropriate library name
426 s/-l//;
427 push(@names,"lib$_.$dl_so");
428 push(@names,"lib$_.a");
429 } else { # Umm, a bare name. Try various alternatives:
430 # these should be ordered with the most likely first
d404d5bf 431 push(@names,"$_.$dl_ext") unless m/\.$dl_ext$/o;
8e07c86e
AD
432 push(@names,"$_.$dl_so") unless m/\.$dl_so$/o;
433 push(@names,"lib$_.$dl_so") unless m:/:;
8e07c86e
AD
434 push(@names,"$_.a") if !m/\.a$/ and $dlsrc eq "dl_dld.xs";
435 push(@names, $_);
436 }
437 foreach $dir (@dirs, @dl_library_path) {
438 next unless -d $dir;
54d6a3b3 439 chop($dir = VMS::Filespec::unixpath($dir)) if $Is_VMS;
8e07c86e
AD
440 foreach $name (@names) {
441 my($file) = "$dir/$name";
442 print STDERR " checking in $dir for $name\n" if $dl_debug;
fb73857a
PP
443 $file = ($do_expand) ? dl_expandspec($file) : (-f $file && $file);
444 #$file = _check_file($file);
8e07c86e
AD
445 if ($file) {
446 push(@found, $file);
447 next arg; # no need to look any further
448 }
449 }
450 }
451 }
452 if ($dl_debug) {
453 foreach(@dirs) {
454 print STDERR " dl_findfile ignored non-existent directory: $_\n" unless -d $_;
455 }
456 print STDERR "dl_findfile found: @found\n";
457 }
458 return $found[0] unless wantarray;
459 @found;
460}
461
462
463sub dl_expandspec {
464 my($spec) = @_;
465 # Optional function invoked if DynaLoader.pm sets $do_expand.
466 # Most systems do not require or use this function.
467 # Some systems may implement it in the dl_*.xs file in which case
468 # this autoload version will not be called but is harmless.
469
470 # This function is designed to deal with systems which treat some
471 # 'filenames' in a special way. For example VMS 'Logical Names'
472 # (something like unix environment variables - but different).
473 # This function should recognise such names and expand them into
474 # full file paths.
475 # Must return undef if $spec is invalid or file does not exist.
476
477 my $file = $spec; # default output to input
478
d404d5bf 479 if ($Is_VMS) { # dl_expandspec should be defined in dl_vms.xs
fb73857a 480 require Carp;
4633a7c4 481 Carp::croak("dl_expandspec: should be defined in XS file!\n");
8e07c86e
AD
482 } else {
483 return undef unless -f $file;
484 }
485 print STDERR "dl_expandspec($spec) => $file\n" if $dl_debug;
486 $file;
487}
488
ff7f3c60
NIS
489sub dl_find_symbol_anywhere
490{
491 my $sym = shift;
492 my $libref;
493 foreach $libref (@dl_librefs) {
494 my $symref = dl_find_symbol($libref,$sym);
495 return $symref if $symref;
496 }
497 return undef;
498}
8e07c86e 499
3b35bae3
AD
500=head1 NAME
501
502DynaLoader - Dynamically load C libraries into Perl code
503
abb9e9dc 504dl_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
3b35bae3
AD
505
506=head1 SYNOPSIS
507
8e07c86e 508 package YourPackage;
3b35bae3 509 require DynaLoader;
c2960299 510 @ISA = qw(... DynaLoader ...);
8e07c86e 511 bootstrap YourPackage;
3b35bae3 512
ff7f3c60
NIS
513 # optional method for 'global' loading
514 sub dl_load_flags { 0x01 }
515
3b35bae3
AD
516
517=head1 DESCRIPTION
518
c2960299 519This document defines a standard generic interface to the dynamic
3b35bae3
AD
520linking mechanisms available on many platforms. Its primary purpose is
521to implement automatic dynamic loading of Perl modules.
522
c2960299
AD
523This document serves as both a specification for anyone wishing to
524implement the DynaLoader for a new platform and as a guide for
525anyone wishing to use the DynaLoader directly in an application.
526
3b35bae3
AD
527The DynaLoader is designed to be a very simple high-level
528interface that is sufficiently general to cover the requirements
529of SunOS, HP-UX, NeXT, Linux, VMS and other platforms.
530
c2960299
AD
531It is also hoped that the interface will cover the needs of OS/2, NT
532etc and also allow pseudo-dynamic linking (using C<ld -A> at runtime).
3b35bae3
AD
533
534It must be stressed that the DynaLoader, by itself, is practically
535useless for accessing non-Perl libraries because it provides almost no
536Perl-to-C 'glue'. There is, for example, no mechanism for calling a C
03c9e98c 537library function or supplying arguments. A C::DynaLib module
90248788 538is available from CPAN sites which performs that function for some
1f98619c
EM
539common system types. And since the year 2000, there's also Inline::C,
540a module that allows you to write Perl subroutines in C. Also available
541from your local CPAN site.
3b35bae3
AD
542
543DynaLoader Interface Summary
544
545 @dl_library_path
546 @dl_resolve_using
547 @dl_require_symbols
548 $dl_debug
ff7f3c60
NIS
549 @dl_librefs
550 @dl_modules
3b35bae3
AD
551 Implemented in:
552 bootstrap($modulename) Perl
553 @filepaths = dl_findfile(@names) Perl
ff7f3c60
NIS
554 $flags = $modulename->dl_load_flags Perl
555 $symref = dl_find_symbol_anywhere($symbol) Perl
3b35bae3 556
ff7f3c60 557 $libref = dl_load_file($filename, $flags) C
abb9e9dc 558 $status = dl_unload_file($libref) C
3b35bae3
AD
559 $symref = dl_find_symbol($libref, $symbol) C
560 @symbols = dl_undef_symbols() C
561 dl_install_xsub($name, $symref [, $filename]) C
562 $message = dl_error C
563
564=over 4
565
566=item @dl_library_path
567
568The standard/default list of directories in which dl_findfile() will
569search for libraries etc. Directories are searched in order:
570$dl_library_path[0], [1], ... etc
571
572@dl_library_path is initialised to hold the list of 'normal' directories
573(F</usr/lib>, etc) determined by B<Configure> (C<$Config{'libpth'}>). This should
574ensure portability across a wide range of platforms.
575
576@dl_library_path should also be initialised with any other directories
577that can be determined from the environment at runtime (such as
578LD_LIBRARY_PATH for SunOS).
579
580After initialisation @dl_library_path can be manipulated by an
581application using push and unshift before calling dl_findfile().
582Unshift can be used to add directories to the front of the search order
583either to save search time or to override libraries with the same name
584in the 'normal' directories.
585
586The load function that dl_load_file() calls may require an absolute
587pathname. The dl_findfile() function and @dl_library_path can be
588used to search for and return the absolute pathname for the
589library/object that you wish to load.
590
591=item @dl_resolve_using
592
593A list of additional libraries or other shared objects which can be
594used to resolve any undefined symbols that might be generated by a
595later call to load_file().
596
597This is only required on some platforms which do not handle dependent
7a2e2cd6
PP
598libraries automatically. For example the Socket Perl extension
599library (F<auto/Socket/Socket.so>) contains references to many socket
600functions which need to be resolved when it's loaded. Most platforms
601will automatically know where to find the 'dependent' library (e.g.,
602F</usr/lib/libsocket.so>). A few platforms need to be told the
603location of the dependent library explicitly. Use @dl_resolve_using
604for this.
3b35bae3
AD
605
606Example usage:
607
608 @dl_resolve_using = dl_findfile('-lsocket');
609
610=item @dl_require_symbols
611
612A list of one or more symbol names that are in the library/object file
613to be dynamically loaded. This is only required on some platforms.
614
ff7f3c60
NIS
615=item @dl_librefs
616
617An array of the handles returned by successful calls to dl_load_file(),
618made by bootstrap, in the order in which they were loaded.
619Can be used with dl_find_symbol() to look for a symbol in any of
620the loaded files.
621
622=item @dl_modules
623
624An array of module (package) names that have been bootstrap'ed.
625
3b35bae3
AD
626=item dl_error()
627
628Syntax:
629
630 $message = dl_error();
631
632Error message text from the last failed DynaLoader function. Note
633that, similar to errno in unix, a successful function call does not
634reset this message.
635
636Implementations should detect the error as soon as it occurs in any of
637the other functions and save the corresponding message for later
638retrieval. This will avoid problems on some platforms (such as SunOS)
639where the error message is very temporary (e.g., dlerror()).
640
641=item $dl_debug
642
643Internal debugging messages are enabled when $dl_debug is set true.
644Currently setting $dl_debug only affects the Perl side of the
645DynaLoader. These messages should help an application developer to
646resolve any DynaLoader usage problems.
647
648$dl_debug is set to C<$ENV{'PERL_DL_DEBUG'}> if defined.
649
650For the DynaLoader developer/porter there is a similar debugging
651variable added to the C code (see dlutils.c) and enabled if Perl was
652built with the B<-DDEBUGGING> flag. This can also be set via the
653PERL_DL_DEBUG environment variable. Set to 1 for minimal information or
654higher for more.
655
656=item dl_findfile()
657
658Syntax:
659
660 @filepaths = dl_findfile(@names)
661
662Determine the full paths (including file suffix) of one or more
663loadable files given their generic names and optionally one or more
664directories. Searches directories in @dl_library_path by default and
665returns an empty list if no files were found.
666
667Names can be specified in a variety of platform independent forms. Any
668names in the form B<-lname> are converted into F<libname.*>, where F<.*> is
669an appropriate suffix for the platform.
670
671If a name does not already have a suitable prefix and/or suffix then
672the corresponding file will be searched for by trying combinations of
673prefix and suffix appropriate to the platform: "$name.o", "lib$name.*"
674and "$name".
675
676If any directories are included in @names they are searched before
c2960299
AD
677@dl_library_path. Directories may be specified as B<-Ldir>. Any other
678names are treated as filenames to be searched for.
3b35bae3
AD
679
680Using arguments of the form C<-Ldir> and C<-lname> is recommended.
681
682Example:
683
684 @dl_resolve_using = dl_findfile(qw(-L/usr/5lib -lposix));
685
686
687=item dl_expandspec()
688
689Syntax:
690
691 $filepath = dl_expandspec($spec)
692
693Some unusual systems, such as VMS, require special filename handling in
694order to deal with symbolic names for files (i.e., VMS's Logical Names).
695
696To support these systems a dl_expandspec() function can be implemented
697either in the F<dl_*.xs> file or code can be added to the autoloadable
c2960299
AD
698dl_expandspec() function in F<DynaLoader.pm>. See F<DynaLoader.pm> for
699more information.
3b35bae3
AD
700
701=item dl_load_file()
702
703Syntax:
704
ff7f3c60 705 $libref = dl_load_file($filename, $flags)
3b35bae3
AD
706
707Dynamically load $filename, which must be the path to a shared object
708or library. An opaque 'library reference' is returned as a handle for
709the loaded object. Returns undef on error.
710
ff7f3c60
NIS
711The $flags argument to alters dl_load_file behaviour.
712Assigned bits:
713
714 0x01 make symbols available for linking later dl_load_file's.
715 (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL))
f86702cc 716 (ignored under VMS; this is a normal part of image linking)
ff7f3c60 717
3b35bae3
AD
718(On systems that provide a handle for the loaded object such as SunOS
719and HPUX, $libref will be that handle. On other systems $libref will
720typically be $filename or a pointer to a buffer containing $filename.
721The application should not examine or alter $libref in any way.)
722
ff7f3c60
NIS
723This is the function that does the real work. It should use the
724current values of @dl_require_symbols and @dl_resolve_using if required.
3b35bae3
AD
725
726 SunOS: dlopen($filename)
727 HP-UX: shl_load($filename)
728 Linux: dld_create_reference(@dl_require_symbols); dld_link($filename)
729 NeXT: rld_load($filename, @dl_resolve_using)
730 VMS: lib$find_image_symbol($filename,$dl_require_symbols[0])
731
ff7f3c60
NIS
732(The dlopen() function is also used by Solaris and some versions of
733Linux, and is a common choice when providing a "wrapper" on other
734mechanisms as is done in the OS/2 port.)
735
abb9e9dc
GS
736=item dl_unload_file()
737
738Syntax:
739
740 $status = dl_unload_file($libref)
741
742Dynamically unload $libref, which must be an opaque 'library reference' as
743returned from dl_load_file. Returns one on success and zero on failure.
744
745This function is optional and may not necessarily be provided on all platforms.
746If it is defined, it is called automatically when the interpreter exits for
747every shared object or library loaded by DynaLoader::bootstrap. All such
748library references are stored in @dl_librefs by DynaLoader::Bootstrap as it
22851543 749loads the libraries. The files are unloaded in last-in, first-out order.
abb9e9dc
GS
750
751This unloading is usually necessary when embedding a shared-object perl (e.g.
752one configured with -Duseshrplib) within a larger application, and the perl
753interpreter is created and destroyed several times within the lifetime of the
754application. In this case it is possible that the system dynamic linker will
755unload and then subsequently reload the shared libperl without relocating any
756references to it from any files DynaLoaded by the previous incarnation of the
757interpreter. As a result, any shared objects opened by DynaLoader may point to
758a now invalid 'ghost' of the libperl shared object, causing apparently random
759memory corruption and crashes. This behaviour is most commonly seen when using
760Apache and mod_perl built with the APXS mechanism.
761
762 SunOS: dlclose($libref)
763 HP-UX: ???
764 Linux: ???
765 NeXT: ???
766 VMS: ???
767
768(The dlclose() function is also used by Solaris and some versions of
769Linux, and is a common choice when providing a "wrapper" on other
770mechanisms as is done in the OS/2 port.)
771
2307c6d0 772=item dl_load_flags()
ff7f3c60
NIS
773
774Syntax:
775
2307c6d0 776 $flags = dl_load_flags $modulename;
ff7f3c60
NIS
777
778Designed to be a method call, and to be overridden by a derived class
779(i.e. a class which has DynaLoader in its @ISA). The definition in
780DynaLoader itself returns 0, which produces standard behavior from
781dl_load_file().
3b35bae3
AD
782
783=item dl_find_symbol()
784
785Syntax:
786
787 $symref = dl_find_symbol($libref, $symbol)
788
789Return the address of the symbol $symbol or C<undef> if not found. If the
790target system has separate functions to search for symbols of different
791types then dl_find_symbol() should search for function symbols first and
792then other types.
793
794The exact manner in which the address is returned in $symref is not
795currently defined. The only initial requirement is that $symref can
796be passed to, and understood by, dl_install_xsub().
797
798 SunOS: dlsym($libref, $symbol)
799 HP-UX: shl_findsym($libref, $symbol)
800 Linux: dld_get_func($symbol) and/or dld_get_symbol($symbol)
801 NeXT: rld_lookup("_$symbol")
802 VMS: lib$find_image_symbol($libref,$symbol)
803
804
ff7f3c60
NIS
805=item dl_find_symbol_anywhere()
806
807Syntax:
808
809 $symref = dl_find_symbol_anywhere($symbol)
810
811Applies dl_find_symbol() to the members of @dl_librefs and returns
812the first match found.
813
3b35bae3
AD
814=item dl_undef_symbols()
815
816Example
817
818 @symbols = dl_undef_symbols()
819
820Return a list of symbol names which remain undefined after load_file().
821Returns C<()> if not known. Don't worry if your platform does not provide
c2960299
AD
822a mechanism for this. Most do not need it and hence do not provide it,
823they just return an empty list.
3b35bae3
AD
824
825
826=item dl_install_xsub()
827
828Syntax:
829
830 dl_install_xsub($perl_name, $symref [, $filename])
831
832Create a new Perl external subroutine named $perl_name using $symref as
833a pointer to the function which implements the routine. This is simply
834a direct call to newXSUB(). Returns a reference to the installed
835function.
836
837The $filename parameter is used by Perl to identify the source file for
838the function if required by die(), caller() or the debugger. If
839$filename is not defined then "DynaLoader" will be used.
840
841
1fef88e7 842=item bootstrap()
3b35bae3
AD
843
844Syntax:
845
846bootstrap($module)
847
848This is the normal entry point for automatic dynamic loading in Perl.
849
850It performs the following actions:
851
852=over 8
853
854=item *
855
856locates an auto/$module directory by searching @INC
857
858=item *
859
860uses dl_findfile() to determine the filename to load
861
862=item *
863
864sets @dl_require_symbols to C<("boot_$module")>
865
866=item *
867
868executes an F<auto/$module/$module.bs> file if it exists
869(typically used to add to @dl_resolve_using any files which
870are required to load the module on the current platform)
871
872=item *
873
ff7f3c60
NIS
874calls dl_load_flags() to determine how to load the file.
875
876=item *
877
3b35bae3
AD
878calls dl_load_file() to load the file
879
880=item *
881
882calls dl_undef_symbols() and warns if any symbols are undefined
883
884=item *
885
886calls dl_find_symbol() for "boot_$module"
887
888=item *
889
890calls dl_install_xsub() to install it as "${module}::bootstrap"
891
892=item *
893
8e07c86e
AD
894calls &{"${module}::bootstrap"} to bootstrap the module (actually
895it uses the function reference returned by dl_install_xsub for speed)
3b35bae3
AD
896
897=back
898
899=back
900
901
902=head1 AUTHOR
903
c2960299
AD
904Tim Bunce, 11 August 1994.
905
3b35bae3
AD
906This interface is based on the work and comments of (in no particular
907order): Larry Wall, Robert Sanders, Dean Roehrich, Jeff Okamoto, Anno
c2960299 908Siegel, Thomas Neumann, Paul Marquess, Charles Bailey, myself and others.
3b35bae3
AD
909
910Larry Wall designed the elegant inherited bootstrap mechanism and
911implemented the first Perl 5 dynamic loader using it.
912
ff7f3c60
NIS
913Solaris global loading added by Nick Ing-Simmons with design/coding
914assistance from Tim Bunce, January 1996.
915
3b35bae3 916=cut
03c9e98c
GS
917EOT
918
919close OUT or die $!;
920