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1 | |
2 | # Generated from DynaLoader.pm.PL | |
3 | ||
4 | package DynaLoader; | |
5 | ||
6 | # And Gandalf said: 'Many folk like to know beforehand what is to | |
7 | # be set on the table; but those who have laboured to prepare the | |
8 | # feast like to keep their secret; for wonder makes the words of | |
9 | # praise louder.' | |
10 | ||
11 | # (Quote from Tolkien suggested by Anno Siegel.) | |
12 | # | |
13 | # See pod text at end of file for documentation. | |
14 | # See also ext/DynaLoader/README in source tree for other information. | |
15 | # | |
16 | # Tim.Bunce@ig.co.uk, August 1994 | |
17 | ||
18 | use vars qw($VERSION *AUTOLOAD); | |
19 | ||
20 | $VERSION = 1.04; # avoid typo warning | |
21 | ||
22 | require AutoLoader; | |
23 | *AUTOLOAD = \&AutoLoader::AUTOLOAD; | |
24 | ||
25 | use Config; | |
26 | ||
27 | # The following require can't be removed during maintenance | |
28 | # releases, sadly, because of the risk of buggy code that does | |
29 | # require Carp; Carp::croak "..."; without brackets dying | |
30 | # if Carp hasn't been loaded in earlier compile time. :-( | |
31 | # We'll let those bugs get found on the development track. | |
32 | require Carp if $] < 5.00450; | |
33 | ||
34 | # enable debug/trace messages from DynaLoader perl code | |
35 | $dl_debug = $ENV{PERL_DL_DEBUG} || 0 unless defined $dl_debug; | |
36 | ||
37 | # | |
38 | # Flags to alter dl_load_file behaviour. Assigned bits: | |
39 | # 0x01 make symbols available for linking later dl_load_file's. | |
40 | # (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL)) | |
41 | # (ignored under VMS; effect is built-in to image linking) | |
42 | # | |
43 | # This is called as a class method $module->dl_load_flags. The | |
44 | # definition here will be inherited and result on "default" loading | |
45 | # behaviour unless a sub-class of DynaLoader defines its own version. | |
46 | # | |
47 | ||
48 | sub dl_load_flags { 0x00 } | |
49 | ||
50 | # ($dl_dlext, $dlsrc) | |
51 | # = @Config::Config{'dlext', 'dlsrc'}; | |
52 | ($dl_dlext, $dlsrc) = ('so','dl_dlopen.xs') | |
53 | ; | |
54 | # Some systems need special handling to expand file specifications | |
55 | # (VMS support by Charles Bailey <bailey@HMIVAX.HUMGEN.UPENN.EDU>) | |
56 | # See dl_expandspec() for more details. Should be harmless but | |
57 | # inefficient to define on systems that don't need it. | |
58 | $Is_VMS = $^O eq 'VMS'; | |
59 | $do_expand = $Is_VMS; | |
60 | $Is_MacOS = $^O eq 'MacOS'; | |
61 | ||
62 | my $Mac_FS; | |
63 | $Mac_FS = eval { require Mac::FileSpec::Unixish } if $Is_MacOS; | |
64 | ||
65 | @dl_require_symbols = (); # names of symbols we need | |
66 | @dl_resolve_using = (); # names of files to link with | |
67 | @dl_library_path = (); # path to look for files | |
68 | ||
69 | #XSLoader.pm may have added elements before we were required | |
70 | #@dl_librefs = (); # things we have loaded | |
71 | #@dl_modules = (); # Modules we have loaded | |
72 | ||
73 | # This is a fix to support DLD's unfortunate desire to relink -lc | |
74 | @dl_resolve_using = dl_findfile('-lc') if $dlsrc eq "dl_dld.xs"; | |
75 | ||
76 | # Initialise @dl_library_path with the 'standard' library path | |
77 | # for this platform as determined by Configure. | |
78 | ||
79 | push(@dl_library_path, split(' ', $Config::Config{libpth})); | |
80 | ||
81 | ||
82 | my $ldlibpthname = $Config::Config{ldlibpthname}; | |
83 | my $ldlibpthname_defined = defined $Config::Config{ldlibpthname}; | |
84 | my $pthsep = $Config::Config{path_sep}; | |
85 | ||
86 | # Add to @dl_library_path any extra directories we can gather from environment | |
87 | # during runtime. | |
88 | ||
89 | if ($ldlibpthname_defined && | |
90 | exists $ENV{$ldlibpthname}) { | |
91 | push(@dl_library_path, split(/$pthsep/, $ENV{$ldlibpthname})); | |
92 | } | |
93 | ||
94 | # E.g. HP-UX supports both its native SHLIB_PATH *and* LD_LIBRARY_PATH. | |
95 | ||
96 | if ($ldlibpthname_defined && | |
97 | $ldlibpthname ne 'LD_LIBRARY_PATH' && | |
98 | exists $ENV{LD_LIBRARY_PATH}) { | |
99 | push(@dl_library_path, split(/$pthsep/, $ENV{LD_LIBRARY_PATH})); | |
100 | } | |
101 | ||
102 | ||
103 | # No prizes for guessing why we don't say 'bootstrap DynaLoader;' here. | |
104 | # NOTE: All dl_*.xs (including dl_none.xs) define a dl_error() XSUB | |
105 | boot_DynaLoader('DynaLoader') if defined(&boot_DynaLoader) && | |
106 | !defined(&dl_error); | |
107 | ||
108 | if ($dl_debug) { | |
109 | print STDERR "DynaLoader.pm loaded (@INC, @dl_library_path)\n"; | |
110 | print STDERR "DynaLoader not linked into this perl\n" | |
111 | unless defined(&boot_DynaLoader); | |
112 | } | |
113 | ||
114 | 1; # End of main code | |
115 | ||
116 | ||
117 | sub croak { require Carp; Carp::croak(@_) } | |
118 | ||
119 | sub bootstrap_inherit { | |
120 | my $module = $_[0]; | |
121 | local *isa = *{"$module\::ISA"}; | |
122 | local @isa = (@isa, 'DynaLoader'); | |
123 | # Cannot goto due to delocalization. Will report errors on a wrong line? | |
124 | bootstrap(@_); | |
125 | } | |
126 | ||
127 | # The bootstrap function cannot be autoloaded (without complications) | |
128 | # so we define it here: | |
129 | ||
130 | sub bootstrap { | |
131 | # use local vars to enable $module.bs script to edit values | |
132 | local(@args) = @_; | |
133 | local($module) = $args[0]; | |
134 | local(@dirs, $file); | |
135 | ||
136 | unless ($module) { | |
137 | require Carp; | |
138 | Carp::confess("Usage: DynaLoader::bootstrap(module)"); | |
139 | } | |
140 | ||
141 | # A common error on platforms which don't support dynamic loading. | |
142 | # Since it's fatal and potentially confusing we give a detailed message. | |
143 | croak("Can't load module $module, dynamic loading not available in this perl.\n". | |
144 | " (You may need to build a new perl executable which either supports\n". | |
145 | " dynamic loading or has the $module module statically linked into it.)\n") | |
146 | unless defined(&dl_load_file); | |
147 | ||
148 | my @modparts = split(/::/,$module); | |
149 | my $modfname = $modparts[-1]; | |
150 | ||
151 | # Some systems have restrictions on files names for DLL's etc. | |
152 | # mod2fname returns appropriate file base name (typically truncated) | |
153 | # It may also edit @modparts if required. | |
154 | $modfname = &mod2fname(\@modparts) if defined &mod2fname; | |
155 | ||
156 | # Truncate the module name to 8.3 format for NetWare | |
157 | if (($^O eq 'NetWare') && (length($modfname) > 8)) { | |
158 | $modfname = substr($modfname, 0, 8); | |
159 | } | |
160 | ||
161 | my $modpname = join(($Is_MacOS ? ':' : '/'),@modparts); | |
162 | ||
163 | print STDERR "DynaLoader::bootstrap for $module ", | |
164 | ($Is_MacOS | |
165 | ? "(:auto:$modpname:$modfname.$dl_dlext)\n" : | |
166 | "(auto/$modpname/$modfname.$dl_dlext)\n") | |
167 | if $dl_debug; | |
168 | ||
169 | foreach (@INC) { | |
170 | chop($_ = VMS::Filespec::unixpath($_)) if $Is_VMS; | |
171 | my $dir; | |
172 | if ($Is_MacOS) { | |
173 | my $path = $_; | |
174 | if ($Mac_FS && ! -d $path) { | |
175 | $path = Mac::FileSpec::Unixish::nativize($path); | |
176 | } | |
177 | $path .= ":" unless /:$/; | |
178 | $dir = "${path}auto:$modpname"; | |
179 | } else { | |
180 | $dir = "$_/auto/$modpname"; | |
181 | } | |
182 | ||
183 | next unless -d $dir; # skip over uninteresting directories | |
184 | ||
185 | # check for common cases to avoid autoload of dl_findfile | |
186 | my $try = $Is_MacOS ? "$dir:$modfname.$dl_dlext" : "$dir/$modfname.$dl_dlext"; | |
187 | last if $file = ($do_expand) ? dl_expandspec($try) : ((-f $try) && $try); | |
188 | ||
189 | # no luck here, save dir for possible later dl_findfile search | |
190 | push @dirs, $dir; | |
191 | } | |
192 | # last resort, let dl_findfile have a go in all known locations | |
193 | $file = dl_findfile(map("-L$_",@dirs,@INC), $modfname) unless $file; | |
194 | ||
195 | croak("Can't locate loadable object for module $module in \@INC (\@INC contains: @INC)") | |
196 | unless $file; # wording similar to error from 'require' | |
197 | ||
198 | $file = uc($file) if $Is_VMS && $Config::Config{d_vms_case_sensitive_symbols}; | |
199 | my $bootname = "boot_$module"; | |
200 | $bootname =~ s/\W/_/g; | |
201 | @dl_require_symbols = ($bootname); | |
202 | ||
203 | # Execute optional '.bootstrap' perl script for this module. | |
204 | # The .bs file can be used to configure @dl_resolve_using etc to | |
205 | # match the needs of the individual module on this architecture. | |
206 | my $bs = $file; | |
207 | $bs =~ s/(\.\w+)?(;\d*)?$/\.bs/; # look for .bs 'beside' the library | |
208 | if (-s $bs) { # only read file if it's not empty | |
209 | print STDERR "BS: $bs ($^O, $dlsrc)\n" if $dl_debug; | |
210 | eval { do $bs; }; | |
211 | warn "$bs: $@\n" if $@; | |
212 | } | |
213 | ||
214 | my $boot_symbol_ref; | |
215 | ||
216 | if ($^O eq 'darwin') { | |
217 | if ($boot_symbol_ref = dl_find_symbol(0, $bootname)) { | |
218 | goto boot; #extension library has already been loaded, e.g. darwin | |
219 | } | |
220 | } | |
221 | ||
222 | # Many dynamic extension loading problems will appear to come from | |
223 | # this section of code: XYZ failed at line 123 of DynaLoader.pm. | |
224 | # Often these errors are actually occurring in the initialisation | |
225 | # C code of the extension XS file. Perl reports the error as being | |
226 | # in this perl code simply because this was the last perl code | |
227 | # it executed. | |
228 | ||
229 | my $libref = dl_load_file($file, $module->dl_load_flags) or | |
230 | croak("Can't load '$file' for module $module: ".dl_error()); | |
231 | ||
232 | push(@dl_librefs,$libref); # record loaded object | |
233 | ||
234 | my @unresolved = dl_undef_symbols(); | |
235 | if (@unresolved) { | |
236 | require Carp; | |
237 | Carp::carp("Undefined symbols present after loading $file: @unresolved\n"); | |
238 | } | |
239 | ||
240 | $boot_symbol_ref = dl_find_symbol($libref, $bootname) or | |
241 | croak("Can't find '$bootname' symbol in $file\n"); | |
242 | ||
243 | push(@dl_modules, $module); # record loaded module | |
244 | ||
245 | boot: | |
246 | my $xs = dl_install_xsub("${module}::bootstrap", $boot_symbol_ref, $file); | |
247 | ||
248 | # See comment block above | |
249 | &$xs(@args); | |
250 | } | |
251 | ||
252 | ||
253 | #sub _check_file { # private utility to handle dl_expandspec vs -f tests | |
254 | # my($file) = @_; | |
255 | # return $file if (!$do_expand && -f $file); # the common case | |
256 | # return $file if ( $do_expand && ($file=dl_expandspec($file))); | |
257 | # return undef; | |
258 | #} | |
259 | ||
260 | ||
261 | # Let autosplit and the autoloader deal with these functions: | |
262 | __END__ | |
263 | ||
264 | ||
265 | sub dl_findfile { | |
266 | # Read ext/DynaLoader/DynaLoader.doc for detailed information. | |
267 | # This function does not automatically consider the architecture | |
268 | # or the perl library auto directories. | |
269 | my (@args) = @_; | |
270 | my (@dirs, $dir); # which directories to search | |
271 | my (@found); # full paths to real files we have found | |
272 | my $dl_ext= 'so'; # $Config::Config{'dlext'} suffix for perl extensions | |
273 | my $dl_so = 'so'; # $Config::Config{'so'} suffix for shared libraries | |
274 | ||
275 | print STDERR "dl_findfile(@args)\n" if $dl_debug; | |
276 | ||
277 | # accumulate directories but process files as they appear | |
278 | arg: foreach(@args) { | |
279 | # Special fast case: full filepath requires no search | |
280 | if ($Is_VMS && m%[:>/\]]% && -f $_) { | |
281 | push(@found,dl_expandspec(VMS::Filespec::vmsify($_))); | |
282 | last arg unless wantarray; | |
283 | next; | |
284 | } | |
285 | elsif ($Is_MacOS) { | |
286 | if (m/:/ && -f $_) { | |
287 | push(@found,$_); | |
288 | last arg unless wantarray; | |
289 | } | |
290 | } | |
291 | elsif (m:/: && -f $_ && !$do_expand) { | |
292 | push(@found,$_); | |
293 | last arg unless wantarray; | |
294 | next; | |
295 | } | |
296 | ||
297 | # Deal with directories first: | |
298 | # Using a -L prefix is the preferred option (faster and more robust) | |
299 | if (m:^-L:) { s/^-L//; push(@dirs, $_); next; } | |
300 | ||
301 | if ($Is_MacOS) { | |
302 | # Otherwise we try to try to spot directories by a heuristic | |
303 | # (this is a more complicated issue than it first appears) | |
304 | if (m/:/ && -d $_) { push(@dirs, $_); next; } | |
305 | # Only files should get this far... | |
306 | my(@names, $name); # what filenames to look for | |
307 | s/^-l//; | |
308 | push(@names, $_); | |
309 | foreach $dir (@dirs, @dl_library_path) { | |
310 | next unless -d $dir; | |
311 | $dir =~ s/^([^:]+)$/:$1/; | |
312 | $dir =~ s/:$//; | |
313 | foreach $name (@names) { | |
314 | my($file) = "$dir:$name"; | |
315 | print STDERR " checking in $dir for $name\n" if $dl_debug; | |
316 | if (-f $file) { | |
317 | push(@found, $file); | |
318 | next arg; # no need to look any further | |
319 | } | |
320 | } | |
321 | } | |
322 | next; | |
323 | } | |
324 | ||
325 | # Otherwise we try to try to spot directories by a heuristic | |
326 | # (this is a more complicated issue than it first appears) | |
327 | if (m:/: && -d $_) { push(@dirs, $_); next; } | |
328 | ||
329 | # VMS: we may be using native VMS directory syntax instead of | |
330 | # Unix emulation, so check this as well | |
331 | if ($Is_VMS && /[:>\]]/ && -d $_) { push(@dirs, $_); next; } | |
332 | ||
333 | # Only files should get this far... | |
334 | my(@names, $name); # what filenames to look for | |
335 | if (m:-l: ) { # convert -lname to appropriate library name | |
336 | s/-l//; | |
337 | push(@names,"lib$_.$dl_so"); | |
338 | push(@names,"lib$_.a"); | |
339 | } else { # Umm, a bare name. Try various alternatives: | |
340 | # these should be ordered with the most likely first | |
341 | push(@names,"$_.$dl_ext") unless m/\.$dl_ext$/o; | |
342 | push(@names,"$_.$dl_so") unless m/\.$dl_so$/o; | |
343 | push(@names,"lib$_.$dl_so") unless m:/:; | |
344 | push(@names,"$_.a") if !m/\.a$/ and $dlsrc eq "dl_dld.xs"; | |
345 | push(@names, $_); | |
346 | } | |
347 | foreach $dir (@dirs, @dl_library_path) { | |
348 | next unless -d $dir; | |
349 | chop($dir = VMS::Filespec::unixpath($dir)) if $Is_VMS; | |
350 | foreach $name (@names) { | |
351 | my($file) = "$dir/$name"; | |
352 | print STDERR " checking in $dir for $name\n" if $dl_debug; | |
353 | $file = ($do_expand) ? dl_expandspec($file) : (-f $file && $file); | |
354 | #$file = _check_file($file); | |
355 | if ($file) { | |
356 | push(@found, $file); | |
357 | next arg; # no need to look any further | |
358 | } | |
359 | } | |
360 | } | |
361 | } | |
362 | if ($dl_debug) { | |
363 | foreach(@dirs) { | |
364 | print STDERR " dl_findfile ignored non-existent directory: $_\n" unless -d $_; | |
365 | } | |
366 | print STDERR "dl_findfile found: @found\n"; | |
367 | } | |
368 | return $found[0] unless wantarray; | |
369 | @found; | |
370 | } | |
371 | ||
372 | ||
373 | sub dl_expandspec { | |
374 | my($spec) = @_; | |
375 | # Optional function invoked if DynaLoader.pm sets $do_expand. | |
376 | # Most systems do not require or use this function. | |
377 | # Some systems may implement it in the dl_*.xs file in which case | |
378 | # this autoload version will not be called but is harmless. | |
379 | ||
380 | # This function is designed to deal with systems which treat some | |
381 | # 'filenames' in a special way. For example VMS 'Logical Names' | |
382 | # (something like unix environment variables - but different). | |
383 | # This function should recognise such names and expand them into | |
384 | # full file paths. | |
385 | # Must return undef if $spec is invalid or file does not exist. | |
386 | ||
387 | my $file = $spec; # default output to input | |
388 | ||
389 | if ($Is_VMS) { # dl_expandspec should be defined in dl_vms.xs | |
390 | require Carp; | |
391 | Carp::croak("dl_expandspec: should be defined in XS file!\n"); | |
392 | } else { | |
393 | return undef unless -f $file; | |
394 | } | |
395 | print STDERR "dl_expandspec($spec) => $file\n" if $dl_debug; | |
396 | $file; | |
397 | } | |
398 | ||
399 | sub dl_find_symbol_anywhere | |
400 | { | |
401 | my $sym = shift; | |
402 | my $libref; | |
403 | foreach $libref (@dl_librefs) { | |
404 | my $symref = dl_find_symbol($libref,$sym); | |
405 | return $symref if $symref; | |
406 | } | |
407 | return undef; | |
408 | } | |
409 | ||
410 | =head1 NAME | |
411 | ||
412 | DynaLoader - Dynamically load C libraries into Perl code | |
413 | ||
414 | 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 | |
415 | ||
416 | =head1 SYNOPSIS | |
417 | ||
418 | package YourPackage; | |
419 | require DynaLoader; | |
420 | @ISA = qw(... DynaLoader ...); | |
421 | bootstrap YourPackage; | |
422 | ||
423 | # optional method for 'global' loading | |
424 | sub dl_load_flags { 0x01 } | |
425 | ||
426 | ||
427 | =head1 DESCRIPTION | |
428 | ||
429 | This document defines a standard generic interface to the dynamic | |
430 | linking mechanisms available on many platforms. Its primary purpose is | |
431 | to implement automatic dynamic loading of Perl modules. | |
432 | ||
433 | This document serves as both a specification for anyone wishing to | |
434 | implement the DynaLoader for a new platform and as a guide for | |
435 | anyone wishing to use the DynaLoader directly in an application. | |
436 | ||
437 | The DynaLoader is designed to be a very simple high-level | |
438 | interface that is sufficiently general to cover the requirements | |
439 | of SunOS, HP-UX, NeXT, Linux, VMS and other platforms. | |
440 | ||
441 | It is also hoped that the interface will cover the needs of OS/2, NT | |
442 | etc and also allow pseudo-dynamic linking (using C<ld -A> at runtime). | |
443 | ||
444 | It must be stressed that the DynaLoader, by itself, is practically | |
445 | useless for accessing non-Perl libraries because it provides almost no | |
446 | Perl-to-C 'glue'. There is, for example, no mechanism for calling a C | |
447 | library function or supplying arguments. A C::DynaLib module | |
448 | is available from CPAN sites which performs that function for some | |
449 | common system types. And since the year 2000, there's also Inline::C, | |
450 | a module that allows you to write Perl subroutines in C. Also available | |
451 | from your local CPAN site. | |
452 | ||
453 | DynaLoader Interface Summary | |
454 | ||
455 | @dl_library_path | |
456 | @dl_resolve_using | |
457 | @dl_require_symbols | |
458 | $dl_debug | |
459 | @dl_librefs | |
460 | @dl_modules | |
461 | Implemented in: | |
462 | bootstrap($modulename) Perl | |
463 | @filepaths = dl_findfile(@names) Perl | |
464 | $flags = $modulename->dl_load_flags Perl | |
465 | $symref = dl_find_symbol_anywhere($symbol) Perl | |
466 | ||
467 | $libref = dl_load_file($filename, $flags) C | |
468 | $status = dl_unload_file($libref) C | |
469 | $symref = dl_find_symbol($libref, $symbol) C | |
470 | @symbols = dl_undef_symbols() C | |
471 | dl_install_xsub($name, $symref [, $filename]) C | |
472 | $message = dl_error C | |
473 | ||
474 | =over 4 | |
475 | ||
476 | =item @dl_library_path | |
477 | ||
478 | The standard/default list of directories in which dl_findfile() will | |
479 | search for libraries etc. Directories are searched in order: | |
480 | $dl_library_path[0], [1], ... etc | |
481 | ||
482 | @dl_library_path is initialised to hold the list of 'normal' directories | |
483 | (F</usr/lib>, etc) determined by B<Configure> (C<$Config{'libpth'}>). This should | |
484 | ensure portability across a wide range of platforms. | |
485 | ||
486 | @dl_library_path should also be initialised with any other directories | |
487 | that can be determined from the environment at runtime (such as | |
488 | LD_LIBRARY_PATH for SunOS). | |
489 | ||
490 | After initialisation @dl_library_path can be manipulated by an | |
491 | application using push and unshift before calling dl_findfile(). | |
492 | Unshift can be used to add directories to the front of the search order | |
493 | either to save search time or to override libraries with the same name | |
494 | in the 'normal' directories. | |
495 | ||
496 | The load function that dl_load_file() calls may require an absolute | |
497 | pathname. The dl_findfile() function and @dl_library_path can be | |
498 | used to search for and return the absolute pathname for the | |
499 | library/object that you wish to load. | |
500 | ||
501 | =item @dl_resolve_using | |
502 | ||
503 | A list of additional libraries or other shared objects which can be | |
504 | used to resolve any undefined symbols that might be generated by a | |
505 | later call to load_file(). | |
506 | ||
507 | This is only required on some platforms which do not handle dependent | |
508 | libraries automatically. For example the Socket Perl extension | |
509 | library (F<auto/Socket/Socket.so>) contains references to many socket | |
510 | functions which need to be resolved when it's loaded. Most platforms | |
511 | will automatically know where to find the 'dependent' library (e.g., | |
512 | F</usr/lib/libsocket.so>). A few platforms need to be told the | |
513 | location of the dependent library explicitly. Use @dl_resolve_using | |
514 | for this. | |
515 | ||
516 | Example usage: | |
517 | ||
518 | @dl_resolve_using = dl_findfile('-lsocket'); | |
519 | ||
520 | =item @dl_require_symbols | |
521 | ||
522 | A list of one or more symbol names that are in the library/object file | |
523 | to be dynamically loaded. This is only required on some platforms. | |
524 | ||
525 | =item @dl_librefs | |
526 | ||
527 | An array of the handles returned by successful calls to dl_load_file(), | |
528 | made by bootstrap, in the order in which they were loaded. | |
529 | Can be used with dl_find_symbol() to look for a symbol in any of | |
530 | the loaded files. | |
531 | ||
532 | =item @dl_modules | |
533 | ||
534 | An array of module (package) names that have been bootstrap'ed. | |
535 | ||
536 | =item dl_error() | |
537 | ||
538 | Syntax: | |
539 | ||
540 | $message = dl_error(); | |
541 | ||
542 | Error message text from the last failed DynaLoader function. Note | |
543 | that, similar to errno in unix, a successful function call does not | |
544 | reset this message. | |
545 | ||
546 | Implementations should detect the error as soon as it occurs in any of | |
547 | the other functions and save the corresponding message for later | |
548 | retrieval. This will avoid problems on some platforms (such as SunOS) | |
549 | where the error message is very temporary (e.g., dlerror()). | |
550 | ||
551 | =item $dl_debug | |
552 | ||
553 | Internal debugging messages are enabled when $dl_debug is set true. | |
554 | Currently setting $dl_debug only affects the Perl side of the | |
555 | DynaLoader. These messages should help an application developer to | |
556 | resolve any DynaLoader usage problems. | |
557 | ||
558 | $dl_debug is set to C<$ENV{'PERL_DL_DEBUG'}> if defined. | |
559 | ||
560 | For the DynaLoader developer/porter there is a similar debugging | |
561 | variable added to the C code (see dlutils.c) and enabled if Perl was | |
562 | built with the B<-DDEBUGGING> flag. This can also be set via the | |
563 | PERL_DL_DEBUG environment variable. Set to 1 for minimal information or | |
564 | higher for more. | |
565 | ||
566 | =item dl_findfile() | |
567 | ||
568 | Syntax: | |
569 | ||
570 | @filepaths = dl_findfile(@names) | |
571 | ||
572 | Determine the full paths (including file suffix) of one or more | |
573 | loadable files given their generic names and optionally one or more | |
574 | directories. Searches directories in @dl_library_path by default and | |
575 | returns an empty list if no files were found. | |
576 | ||
577 | Names can be specified in a variety of platform independent forms. Any | |
578 | names in the form B<-lname> are converted into F<libname.*>, where F<.*> is | |
579 | an appropriate suffix for the platform. | |
580 | ||
581 | If a name does not already have a suitable prefix and/or suffix then | |
582 | the corresponding file will be searched for by trying combinations of | |
583 | prefix and suffix appropriate to the platform: "$name.o", "lib$name.*" | |
584 | and "$name". | |
585 | ||
586 | If any directories are included in @names they are searched before | |
587 | @dl_library_path. Directories may be specified as B<-Ldir>. Any other | |
588 | names are treated as filenames to be searched for. | |
589 | ||
590 | Using arguments of the form C<-Ldir> and C<-lname> is recommended. | |
591 | ||
592 | Example: | |
593 | ||
594 | @dl_resolve_using = dl_findfile(qw(-L/usr/5lib -lposix)); | |
595 | ||
596 | ||
597 | =item dl_expandspec() | |
598 | ||
599 | Syntax: | |
600 | ||
601 | $filepath = dl_expandspec($spec) | |
602 | ||
603 | Some unusual systems, such as VMS, require special filename handling in | |
604 | order to deal with symbolic names for files (i.e., VMS's Logical Names). | |
605 | ||
606 | To support these systems a dl_expandspec() function can be implemented | |
607 | either in the F<dl_*.xs> file or code can be added to the autoloadable | |
608 | dl_expandspec() function in F<DynaLoader.pm>. See F<DynaLoader.pm> for | |
609 | more information. | |
610 | ||
611 | =item dl_load_file() | |
612 | ||
613 | Syntax: | |
614 | ||
615 | $libref = dl_load_file($filename, $flags) | |
616 | ||
617 | Dynamically load $filename, which must be the path to a shared object | |
618 | or library. An opaque 'library reference' is returned as a handle for | |
619 | the loaded object. Returns undef on error. | |
620 | ||
621 | The $flags argument to alters dl_load_file behaviour. | |
622 | Assigned bits: | |
623 | ||
624 | 0x01 make symbols available for linking later dl_load_file's. | |
625 | (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL)) | |
626 | (ignored under VMS; this is a normal part of image linking) | |
627 | ||
628 | (On systems that provide a handle for the loaded object such as SunOS | |
629 | and HPUX, $libref will be that handle. On other systems $libref will | |
630 | typically be $filename or a pointer to a buffer containing $filename. | |
631 | The application should not examine or alter $libref in any way.) | |
632 | ||
633 | This is the function that does the real work. It should use the | |
634 | current values of @dl_require_symbols and @dl_resolve_using if required. | |
635 | ||
636 | SunOS: dlopen($filename) | |
637 | HP-UX: shl_load($filename) | |
638 | Linux: dld_create_reference(@dl_require_symbols); dld_link($filename) | |
639 | NeXT: rld_load($filename, @dl_resolve_using) | |
640 | VMS: lib$find_image_symbol($filename,$dl_require_symbols[0]) | |
641 | ||
642 | (The dlopen() function is also used by Solaris and some versions of | |
643 | Linux, and is a common choice when providing a "wrapper" on other | |
644 | mechanisms as is done in the OS/2 port.) | |
645 | ||
646 | =item dl_unload_file() | |
647 | ||
648 | Syntax: | |
649 | ||
650 | $status = dl_unload_file($libref) | |
651 | ||
652 | Dynamically unload $libref, which must be an opaque 'library reference' as | |
653 | returned from dl_load_file. Returns one on success and zero on failure. | |
654 | ||
655 | This function is optional and may not necessarily be provided on all platforms. | |
656 | If it is defined, it is called automatically when the interpreter exits for | |
657 | every shared object or library loaded by DynaLoader::bootstrap. All such | |
658 | library references are stored in @dl_librefs by DynaLoader::Bootstrap as it | |
659 | loads the libraries. The files are unloaded in last-in, first-out order. | |
660 | ||
661 | This unloading is usually necessary when embedding a shared-object perl (e.g. | |
662 | one configured with -Duseshrplib) within a larger application, and the perl | |
663 | interpreter is created and destroyed several times within the lifetime of the | |
664 | application. In this case it is possible that the system dynamic linker will | |
665 | unload and then subsequently reload the shared libperl without relocating any | |
666 | references to it from any files DynaLoaded by the previous incarnation of the | |
667 | interpreter. As a result, any shared objects opened by DynaLoader may point to | |
668 | a now invalid 'ghost' of the libperl shared object, causing apparently random | |
669 | memory corruption and crashes. This behaviour is most commonly seen when using | |
670 | Apache and mod_perl built with the APXS mechanism. | |
671 | ||
672 | SunOS: dlclose($libref) | |
673 | HP-UX: ??? | |
674 | Linux: ??? | |
675 | NeXT: ??? | |
676 | VMS: ??? | |
677 | ||
678 | (The dlclose() function is also used by Solaris and some versions of | |
679 | Linux, and is a common choice when providing a "wrapper" on other | |
680 | mechanisms as is done in the OS/2 port.) | |
681 | ||
682 | =item dl_loadflags() | |
683 | ||
684 | Syntax: | |
685 | ||
686 | $flags = dl_loadflags $modulename; | |
687 | ||
688 | Designed to be a method call, and to be overridden by a derived class | |
689 | (i.e. a class which has DynaLoader in its @ISA). The definition in | |
690 | DynaLoader itself returns 0, which produces standard behavior from | |
691 | dl_load_file(). | |
692 | ||
693 | =item dl_find_symbol() | |
694 | ||
695 | Syntax: | |
696 | ||
697 | $symref = dl_find_symbol($libref, $symbol) | |
698 | ||
699 | Return the address of the symbol $symbol or C<undef> if not found. If the | |
700 | target system has separate functions to search for symbols of different | |
701 | types then dl_find_symbol() should search for function symbols first and | |
702 | then other types. | |
703 | ||
704 | The exact manner in which the address is returned in $symref is not | |
705 | currently defined. The only initial requirement is that $symref can | |
706 | be passed to, and understood by, dl_install_xsub(). | |
707 | ||
708 | SunOS: dlsym($libref, $symbol) | |
709 | HP-UX: shl_findsym($libref, $symbol) | |
710 | Linux: dld_get_func($symbol) and/or dld_get_symbol($symbol) | |
711 | NeXT: rld_lookup("_$symbol") | |
712 | VMS: lib$find_image_symbol($libref,$symbol) | |
713 | ||
714 | ||
715 | =item dl_find_symbol_anywhere() | |
716 | ||
717 | Syntax: | |
718 | ||
719 | $symref = dl_find_symbol_anywhere($symbol) | |
720 | ||
721 | Applies dl_find_symbol() to the members of @dl_librefs and returns | |
722 | the first match found. | |
723 | ||
724 | =item dl_undef_symbols() | |
725 | ||
726 | Example | |
727 | ||
728 | @symbols = dl_undef_symbols() | |
729 | ||
730 | Return a list of symbol names which remain undefined after load_file(). | |
731 | Returns C<()> if not known. Don't worry if your platform does not provide | |
732 | a mechanism for this. Most do not need it and hence do not provide it, | |
733 | they just return an empty list. | |
734 | ||
735 | ||
736 | =item dl_install_xsub() | |
737 | ||
738 | Syntax: | |
739 | ||
740 | dl_install_xsub($perl_name, $symref [, $filename]) | |
741 | ||
742 | Create a new Perl external subroutine named $perl_name using $symref as | |
743 | a pointer to the function which implements the routine. This is simply | |
744 | a direct call to newXSUB(). Returns a reference to the installed | |
745 | function. | |
746 | ||
747 | The $filename parameter is used by Perl to identify the source file for | |
748 | the function if required by die(), caller() or the debugger. If | |
749 | $filename is not defined then "DynaLoader" will be used. | |
750 | ||
751 | ||
752 | =item bootstrap() | |
753 | ||
754 | Syntax: | |
755 | ||
756 | bootstrap($module) | |
757 | ||
758 | This is the normal entry point for automatic dynamic loading in Perl. | |
759 | ||
760 | It performs the following actions: | |
761 | ||
762 | =over 8 | |
763 | ||
764 | =item * | |
765 | ||
766 | locates an auto/$module directory by searching @INC | |
767 | ||
768 | =item * | |
769 | ||
770 | uses dl_findfile() to determine the filename to load | |
771 | ||
772 | =item * | |
773 | ||
774 | sets @dl_require_symbols to C<("boot_$module")> | |
775 | ||
776 | =item * | |
777 | ||
778 | executes an F<auto/$module/$module.bs> file if it exists | |
779 | (typically used to add to @dl_resolve_using any files which | |
780 | are required to load the module on the current platform) | |
781 | ||
782 | =item * | |
783 | ||
784 | calls dl_load_flags() to determine how to load the file. | |
785 | ||
786 | =item * | |
787 | ||
788 | calls dl_load_file() to load the file | |
789 | ||
790 | =item * | |
791 | ||
792 | calls dl_undef_symbols() and warns if any symbols are undefined | |
793 | ||
794 | =item * | |
795 | ||
796 | calls dl_find_symbol() for "boot_$module" | |
797 | ||
798 | =item * | |
799 | ||
800 | calls dl_install_xsub() to install it as "${module}::bootstrap" | |
801 | ||
802 | =item * | |
803 | ||
804 | calls &{"${module}::bootstrap"} to bootstrap the module (actually | |
805 | it uses the function reference returned by dl_install_xsub for speed) | |
806 | ||
807 | =back | |
808 | ||
809 | =back | |
810 | ||
811 | ||
812 | =head1 AUTHOR | |
813 | ||
814 | Tim Bunce, 11 August 1994. | |
815 | ||
816 | This interface is based on the work and comments of (in no particular | |
817 | order): Larry Wall, Robert Sanders, Dean Roehrich, Jeff Okamoto, Anno | |
818 | Siegel, Thomas Neumann, Paul Marquess, Charles Bailey, myself and others. | |
819 | ||
820 | Larry Wall designed the elegant inherited bootstrap mechanism and | |
821 | implemented the first Perl 5 dynamic loader using it. | |
822 | ||
823 | Solaris global loading added by Nick Ing-Simmons with design/coding | |
824 | assistance from Tim Bunce, January 1996. | |
825 | ||
826 | =cut |