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1 | package DynaLoader; |
2 | |
8e07c86e |
3 | # And Gandalf said: 'Many folk like to know beforehand what is to |
4 | # be set on the table; but those who have laboured to prepare the |
5 | # feast like to keep their secret; for wonder makes the words of |
6 | # praise louder.' |
7 | |
8 | # (Quote from Tolkien sugested by Anno Siegel.) |
9 | # |
10 | # See pod text at end of file for documentation. |
11 | # See also ext/DynaLoader/README in source tree for other information. |
12 | # |
13 | # Tim.Bunce@ig.co.uk, August 1994 |
14 | |
fb73857a |
15 | $VERSION = $VERSION = "1.03"; # avoid typo warning |
dc848c6f |
16 | |
8e07c86e |
17 | require Config; |
8e07c86e |
18 | |
dc848c6f |
19 | require AutoLoader; |
20 | *AUTOLOAD = \&AutoLoader::AUTOLOAD; |
8e07c86e |
21 | |
fb73857a |
22 | # The following require can't be removed during maintenance |
23 | # releases, sadly, because of the risk of buggy code that does |
24 | # require Carp; Carp::croak "..."; without brackets dying |
25 | # if Carp hasn't been loaded in earlier compile time. :-( |
26 | # We'll let those bugs get found on the development track. |
27 | require Carp if $] < 5.00450; |
28 | |
29 | |
8e07c86e |
30 | # enable debug/trace messages from DynaLoader perl code |
31 | $dl_debug = $ENV{PERL_DL_DEBUG} || 0 unless defined $dl_debug; |
32 | |
ff7f3c60 |
33 | # |
34 | # Flags to alter dl_load_file behaviour. Assigned bits: |
35 | # 0x01 make symbols available for linking later dl_load_file's. |
36 | # (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL)) |
f86702cc |
37 | # (ignored under VMS; effect is built-in to image linking) |
ff7f3c60 |
38 | # |
39 | # This is called as a class method $module->dl_load_flags. The |
40 | # definition here will be inherited and result on "default" loading |
41 | # behaviour unless a sub-class of DynaLoader defines its own version. |
42 | # |
43 | |
44 | sub dl_load_flags { 0x00 } |
45 | |
46 | # |
47 | |
d404d5bf |
48 | ($dl_dlext, $dlsrc) |
49 | = @Config::Config{'dlext', 'dlsrc'}; |
8e07c86e |
50 | |
51 | # Some systems need special handling to expand file specifications |
52 | # (VMS support by Charles Bailey <bailey@HMIVAX.HUMGEN.UPENN.EDU>) |
53 | # See dl_expandspec() for more details. Should be harmless but |
54 | # inefficient to define on systems that don't need it. |
d404d5bf |
55 | $do_expand = $Is_VMS = $^O eq 'VMS'; |
8e07c86e |
56 | |
57 | @dl_require_symbols = (); # names of symbols we need |
58 | @dl_resolve_using = (); # names of files to link with |
59 | @dl_library_path = (); # path to look for files |
ff7f3c60 |
60 | @dl_librefs = (); # things we have loaded |
61 | @dl_modules = (); # Modules we have loaded |
8e07c86e |
62 | |
63 | # This is a fix to support DLD's unfortunate desire to relink -lc |
64 | @dl_resolve_using = dl_findfile('-lc') if $dlsrc eq "dl_dld.xs"; |
65 | |
66 | # Initialise @dl_library_path with the 'standard' library path |
67 | # for this platform as determined by Configure |
68 | push(@dl_library_path, split(' ',$Config::Config{'libpth'})); |
69 | |
70 | # Add to @dl_library_path any extra directories we can gather from |
71 | # environment variables. So far LD_LIBRARY_PATH is the only known |
72 | # variable used for this purpose. Others may be added later. |
73 | push(@dl_library_path, split(/:/, $ENV{LD_LIBRARY_PATH})) |
74 | if $ENV{LD_LIBRARY_PATH}; |
75 | |
76 | |
77 | # No prizes for guessing why we don't say 'bootstrap DynaLoader;' here. |
54d6a3b3 |
78 | boot_DynaLoader('DynaLoader') if defined(&boot_DynaLoader); |
8e07c86e |
79 | |
80 | |
81 | if ($dl_debug) { |
82 | print STDERR "DynaLoader.pm loaded (@INC, @dl_library_path)\n"; |
83 | print STDERR "DynaLoader not linked into this perl\n" |
84 | unless defined(&boot_DynaLoader); |
85 | } |
86 | |
87 | 1; # End of main code |
88 | |
89 | |
fb73857a |
90 | sub croak { require Carp; Carp::croak(@_) } |
91 | |
8e07c86e |
92 | # The bootstrap function cannot be autoloaded (without complications) |
93 | # so we define it here: |
94 | |
95 | sub bootstrap { |
96 | # use local vars to enable $module.bs script to edit values |
97 | local(@args) = @_; |
98 | local($module) = $args[0]; |
99 | local(@dirs, $file); |
100 | |
fb73857a |
101 | unless ($module) { |
102 | require Carp; |
103 | Carp::confess("Usage: DynaLoader::bootstrap(module)"); |
104 | } |
8e07c86e |
105 | |
106 | # A common error on platforms which don't support dynamic loading. |
107 | # Since it's fatal and potentially confusing we give a detailed message. |
fb73857a |
108 | croak("Can't load module $module, dynamic loading not available in this perl.\n". |
8e07c86e |
109 | " (You may need to build a new perl executable which either supports\n". |
110 | " dynamic loading or has the $module module statically linked into it.)\n") |
111 | unless defined(&dl_load_file); |
112 | |
113 | my @modparts = split(/::/,$module); |
114 | my $modfname = $modparts[-1]; |
115 | |
116 | # Some systems have restrictions on files names for DLL's etc. |
117 | # mod2fname returns appropriate file base name (typically truncated) |
118 | # It may also edit @modparts if required. |
119 | $modfname = &mod2fname(\@modparts) if defined &mod2fname; |
120 | |
121 | my $modpname = join('/',@modparts); |
122 | |
123 | print STDERR "DynaLoader::bootstrap for $module ", |
124 | "(auto/$modpname/$modfname.$dl_dlext)\n" if $dl_debug; |
125 | |
126 | foreach (@INC) { |
54d6a3b3 |
127 | chop($_ = VMS::Filespec::unixpath($_)) if $Is_VMS; |
8e07c86e |
128 | my $dir = "$_/auto/$modpname"; |
129 | next unless -d $dir; # skip over uninteresting directories |
130 | |
131 | # check for common cases to avoid autoload of dl_findfile |
fb73857a |
132 | my $try = "$dir/$modfname.$dl_dlext"; |
133 | last if $file = ($do_expand) ? dl_expandspec($try) : (-f $try && $try); |
8e07c86e |
134 | |
135 | # no luck here, save dir for possible later dl_findfile search |
fb73857a |
136 | push @dirs, $dir; |
8e07c86e |
137 | } |
138 | # last resort, let dl_findfile have a go in all known locations |
fb73857a |
139 | $file = dl_findfile(map("-L$_",@dirs,@INC), $modfname) unless $file; |
8e07c86e |
140 | |
fb73857a |
141 | croak("Can't locate loadable object for module $module in \@INC (\@INC contains: @INC)") |
142 | unless $file; # wording similar to error from 'require' |
8e07c86e |
143 | |
144 | my $bootname = "boot_$module"; |
145 | $bootname =~ s/\W/_/g; |
146 | @dl_require_symbols = ($bootname); |
147 | |
148 | # Execute optional '.bootstrap' perl script for this module. |
149 | # The .bs file can be used to configure @dl_resolve_using etc to |
150 | # match the needs of the individual module on this architecture. |
151 | my $bs = $file; |
152 | $bs =~ s/(\.\w+)?$/\.bs/; # look for .bs 'beside' the library |
153 | if (-s $bs) { # only read file if it's not empty |
d404d5bf |
154 | print STDERR "BS: $bs ($^O, $dlsrc)\n" if $dl_debug; |
8e07c86e |
155 | eval { do $bs; }; |
156 | warn "$bs: $@\n" if $@; |
157 | } |
158 | |
159 | # Many dynamic extension loading problems will appear to come from |
160 | # this section of code: XYZ failed at line 123 of DynaLoader.pm. |
161 | # Often these errors are actually occurring in the initialisation |
162 | # C code of the extension XS file. Perl reports the error as being |
163 | # in this perl code simply because this was the last perl code |
164 | # it executed. |
165 | |
ff7f3c60 |
166 | my $libref = dl_load_file($file, $module->dl_load_flags) or |
fb73857a |
167 | croak("Can't load '$file' for module $module: ".dl_error()."\n"); |
8e07c86e |
168 | |
ff7f3c60 |
169 | push(@dl_librefs,$libref); # record loaded object |
170 | |
8e07c86e |
171 | my @unresolved = dl_undef_symbols(); |
fb73857a |
172 | if (@unresolved) { |
173 | require Carp; |
174 | Carp::carp("Undefined symbols present after loading $file: @unresolved\n"); |
175 | } |
8e07c86e |
176 | |
177 | my $boot_symbol_ref = dl_find_symbol($libref, $bootname) or |
fb73857a |
178 | croak("Can't find '$bootname' symbol in $file\n"); |
8e07c86e |
179 | |
180 | my $xs = dl_install_xsub("${module}::bootstrap", $boot_symbol_ref, $file); |
181 | |
ff7f3c60 |
182 | push(@dl_modules, $module); # record loaded module |
183 | |
8e07c86e |
184 | # See comment block above |
185 | &$xs(@args); |
186 | } |
187 | |
188 | |
fb73857a |
189 | #sub _check_file { # private utility to handle dl_expandspec vs -f tests |
190 | # my($file) = @_; |
191 | # return $file if (!$do_expand && -f $file); # the common case |
192 | # return $file if ( $do_expand && ($file=dl_expandspec($file))); |
193 | # return undef; |
194 | #} |
8e07c86e |
195 | |
196 | |
197 | # Let autosplit and the autoloader deal with these functions: |
198 | __END__ |
199 | |
200 | |
201 | sub dl_findfile { |
202 | # Read ext/DynaLoader/DynaLoader.doc for detailed information. |
203 | # This function does not automatically consider the architecture |
204 | # or the perl library auto directories. |
205 | my (@args) = @_; |
206 | my (@dirs, $dir); # which directories to search |
207 | my (@found); # full paths to real files we have found |
d404d5bf |
208 | my $dl_ext= $Config::Config{'dlext'}; # suffix for perl extensions |
8e07c86e |
209 | my $dl_so = $Config::Config{'so'}; # suffix for shared libraries |
210 | |
211 | print STDERR "dl_findfile(@args)\n" if $dl_debug; |
212 | |
213 | # accumulate directories but process files as they appear |
214 | arg: foreach(@args) { |
215 | # Special fast case: full filepath requires no search |
54d6a3b3 |
216 | if ($Is_VMS && m%[:>/\]]% && -f $_) { |
217 | push(@found,dl_expandspec(VMS::Filespec::vmsify($_))); |
218 | last arg unless wantarray; |
219 | next; |
220 | } |
221 | elsif (m:/: && -f $_ && !$do_expand) { |
8e07c86e |
222 | push(@found,$_); |
223 | last arg unless wantarray; |
224 | next; |
225 | } |
226 | |
227 | # Deal with directories first: |
228 | # Using a -L prefix is the preferred option (faster and more robust) |
229 | if (m:^-L:) { s/^-L//; push(@dirs, $_); next; } |
230 | |
231 | # Otherwise we try to try to spot directories by a heuristic |
232 | # (this is a more complicated issue than it first appears) |
233 | if (m:/: && -d $_) { push(@dirs, $_); next; } |
234 | |
235 | # VMS: we may be using native VMS directry syntax instead of |
236 | # Unix emulation, so check this as well |
54d6a3b3 |
237 | if ($Is_VMS && /[:>\]]/ && -d $_) { push(@dirs, $_); next; } |
8e07c86e |
238 | |
239 | # Only files should get this far... |
240 | my(@names, $name); # what filenames to look for |
241 | if (m:-l: ) { # convert -lname to appropriate library name |
242 | s/-l//; |
243 | push(@names,"lib$_.$dl_so"); |
244 | push(@names,"lib$_.a"); |
245 | } else { # Umm, a bare name. Try various alternatives: |
246 | # these should be ordered with the most likely first |
d404d5bf |
247 | push(@names,"$_.$dl_ext") unless m/\.$dl_ext$/o; |
8e07c86e |
248 | push(@names,"$_.$dl_so") unless m/\.$dl_so$/o; |
249 | push(@names,"lib$_.$dl_so") unless m:/:; |
8e07c86e |
250 | push(@names,"$_.a") if !m/\.a$/ and $dlsrc eq "dl_dld.xs"; |
251 | push(@names, $_); |
252 | } |
253 | foreach $dir (@dirs, @dl_library_path) { |
254 | next unless -d $dir; |
54d6a3b3 |
255 | chop($dir = VMS::Filespec::unixpath($dir)) if $Is_VMS; |
8e07c86e |
256 | foreach $name (@names) { |
257 | my($file) = "$dir/$name"; |
258 | print STDERR " checking in $dir for $name\n" if $dl_debug; |
fb73857a |
259 | $file = ($do_expand) ? dl_expandspec($file) : (-f $file && $file); |
260 | #$file = _check_file($file); |
8e07c86e |
261 | if ($file) { |
262 | push(@found, $file); |
263 | next arg; # no need to look any further |
264 | } |
265 | } |
266 | } |
267 | } |
268 | if ($dl_debug) { |
269 | foreach(@dirs) { |
270 | print STDERR " dl_findfile ignored non-existent directory: $_\n" unless -d $_; |
271 | } |
272 | print STDERR "dl_findfile found: @found\n"; |
273 | } |
274 | return $found[0] unless wantarray; |
275 | @found; |
276 | } |
277 | |
278 | |
279 | sub dl_expandspec { |
280 | my($spec) = @_; |
281 | # Optional function invoked if DynaLoader.pm sets $do_expand. |
282 | # Most systems do not require or use this function. |
283 | # Some systems may implement it in the dl_*.xs file in which case |
284 | # this autoload version will not be called but is harmless. |
285 | |
286 | # This function is designed to deal with systems which treat some |
287 | # 'filenames' in a special way. For example VMS 'Logical Names' |
288 | # (something like unix environment variables - but different). |
289 | # This function should recognise such names and expand them into |
290 | # full file paths. |
291 | # Must return undef if $spec is invalid or file does not exist. |
292 | |
293 | my $file = $spec; # default output to input |
294 | |
d404d5bf |
295 | if ($Is_VMS) { # dl_expandspec should be defined in dl_vms.xs |
fb73857a |
296 | require Carp; |
4633a7c4 |
297 | Carp::croak("dl_expandspec: should be defined in XS file!\n"); |
8e07c86e |
298 | } else { |
299 | return undef unless -f $file; |
300 | } |
301 | print STDERR "dl_expandspec($spec) => $file\n" if $dl_debug; |
302 | $file; |
303 | } |
304 | |
ff7f3c60 |
305 | sub dl_find_symbol_anywhere |
306 | { |
307 | my $sym = shift; |
308 | my $libref; |
309 | foreach $libref (@dl_librefs) { |
310 | my $symref = dl_find_symbol($libref,$sym); |
311 | return $symref if $symref; |
312 | } |
313 | return undef; |
314 | } |
8e07c86e |
315 | |
3b35bae3 |
316 | =head1 NAME |
317 | |
318 | DynaLoader - Dynamically load C libraries into Perl code |
319 | |
ff7f3c60 |
320 | dl_error(), dl_findfile(), dl_expandspec(), dl_load_file(), dl_find_symbol(), dl_find_symbol_anywhere(), dl_undef_symbols(), dl_install_xsub(), dl_load_flags(), bootstrap() - routines used by DynaLoader modules |
3b35bae3 |
321 | |
322 | =head1 SYNOPSIS |
323 | |
8e07c86e |
324 | package YourPackage; |
3b35bae3 |
325 | require DynaLoader; |
c2960299 |
326 | @ISA = qw(... DynaLoader ...); |
8e07c86e |
327 | bootstrap YourPackage; |
3b35bae3 |
328 | |
ff7f3c60 |
329 | # optional method for 'global' loading |
330 | sub dl_load_flags { 0x01 } |
331 | |
3b35bae3 |
332 | |
333 | =head1 DESCRIPTION |
334 | |
c2960299 |
335 | This document defines a standard generic interface to the dynamic |
3b35bae3 |
336 | linking mechanisms available on many platforms. Its primary purpose is |
337 | to implement automatic dynamic loading of Perl modules. |
338 | |
c2960299 |
339 | This document serves as both a specification for anyone wishing to |
340 | implement the DynaLoader for a new platform and as a guide for |
341 | anyone wishing to use the DynaLoader directly in an application. |
342 | |
3b35bae3 |
343 | The DynaLoader is designed to be a very simple high-level |
344 | interface that is sufficiently general to cover the requirements |
345 | of SunOS, HP-UX, NeXT, Linux, VMS and other platforms. |
346 | |
c2960299 |
347 | It is also hoped that the interface will cover the needs of OS/2, NT |
348 | etc and also allow pseudo-dynamic linking (using C<ld -A> at runtime). |
3b35bae3 |
349 | |
350 | It must be stressed that the DynaLoader, by itself, is practically |
351 | useless for accessing non-Perl libraries because it provides almost no |
352 | Perl-to-C 'glue'. There is, for example, no mechanism for calling a C |
90248788 |
353 | library function or supplying arguments. A ExtUtils::DynaLib module |
354 | is available from CPAN sites which performs that function for some |
355 | common system types. |
3b35bae3 |
356 | |
357 | DynaLoader Interface Summary |
358 | |
359 | @dl_library_path |
360 | @dl_resolve_using |
361 | @dl_require_symbols |
362 | $dl_debug |
ff7f3c60 |
363 | @dl_librefs |
364 | @dl_modules |
3b35bae3 |
365 | Implemented in: |
366 | bootstrap($modulename) Perl |
367 | @filepaths = dl_findfile(@names) Perl |
ff7f3c60 |
368 | $flags = $modulename->dl_load_flags Perl |
369 | $symref = dl_find_symbol_anywhere($symbol) Perl |
3b35bae3 |
370 | |
ff7f3c60 |
371 | $libref = dl_load_file($filename, $flags) C |
3b35bae3 |
372 | $symref = dl_find_symbol($libref, $symbol) C |
373 | @symbols = dl_undef_symbols() C |
374 | dl_install_xsub($name, $symref [, $filename]) C |
375 | $message = dl_error C |
376 | |
377 | =over 4 |
378 | |
379 | =item @dl_library_path |
380 | |
381 | The standard/default list of directories in which dl_findfile() will |
382 | search for libraries etc. Directories are searched in order: |
383 | $dl_library_path[0], [1], ... etc |
384 | |
385 | @dl_library_path is initialised to hold the list of 'normal' directories |
386 | (F</usr/lib>, etc) determined by B<Configure> (C<$Config{'libpth'}>). This should |
387 | ensure portability across a wide range of platforms. |
388 | |
389 | @dl_library_path should also be initialised with any other directories |
390 | that can be determined from the environment at runtime (such as |
391 | LD_LIBRARY_PATH for SunOS). |
392 | |
393 | After initialisation @dl_library_path can be manipulated by an |
394 | application using push and unshift before calling dl_findfile(). |
395 | Unshift can be used to add directories to the front of the search order |
396 | either to save search time or to override libraries with the same name |
397 | in the 'normal' directories. |
398 | |
399 | The load function that dl_load_file() calls may require an absolute |
400 | pathname. The dl_findfile() function and @dl_library_path can be |
401 | used to search for and return the absolute pathname for the |
402 | library/object that you wish to load. |
403 | |
404 | =item @dl_resolve_using |
405 | |
406 | A list of additional libraries or other shared objects which can be |
407 | used to resolve any undefined symbols that might be generated by a |
408 | later call to load_file(). |
409 | |
410 | This is only required on some platforms which do not handle dependent |
7a2e2cd6 |
411 | libraries automatically. For example the Socket Perl extension |
412 | library (F<auto/Socket/Socket.so>) contains references to many socket |
413 | functions which need to be resolved when it's loaded. Most platforms |
414 | will automatically know where to find the 'dependent' library (e.g., |
415 | F</usr/lib/libsocket.so>). A few platforms need to be told the |
416 | location of the dependent library explicitly. Use @dl_resolve_using |
417 | for this. |
3b35bae3 |
418 | |
419 | Example usage: |
420 | |
421 | @dl_resolve_using = dl_findfile('-lsocket'); |
422 | |
423 | =item @dl_require_symbols |
424 | |
425 | A list of one or more symbol names that are in the library/object file |
426 | to be dynamically loaded. This is only required on some platforms. |
427 | |
ff7f3c60 |
428 | =item @dl_librefs |
429 | |
430 | An array of the handles returned by successful calls to dl_load_file(), |
431 | made by bootstrap, in the order in which they were loaded. |
432 | Can be used with dl_find_symbol() to look for a symbol in any of |
433 | the loaded files. |
434 | |
435 | =item @dl_modules |
436 | |
437 | An array of module (package) names that have been bootstrap'ed. |
438 | |
3b35bae3 |
439 | =item dl_error() |
440 | |
441 | Syntax: |
442 | |
443 | $message = dl_error(); |
444 | |
445 | Error message text from the last failed DynaLoader function. Note |
446 | that, similar to errno in unix, a successful function call does not |
447 | reset this message. |
448 | |
449 | Implementations should detect the error as soon as it occurs in any of |
450 | the other functions and save the corresponding message for later |
451 | retrieval. This will avoid problems on some platforms (such as SunOS) |
452 | where the error message is very temporary (e.g., dlerror()). |
453 | |
454 | =item $dl_debug |
455 | |
456 | Internal debugging messages are enabled when $dl_debug is set true. |
457 | Currently setting $dl_debug only affects the Perl side of the |
458 | DynaLoader. These messages should help an application developer to |
459 | resolve any DynaLoader usage problems. |
460 | |
461 | $dl_debug is set to C<$ENV{'PERL_DL_DEBUG'}> if defined. |
462 | |
463 | For the DynaLoader developer/porter there is a similar debugging |
464 | variable added to the C code (see dlutils.c) and enabled if Perl was |
465 | built with the B<-DDEBUGGING> flag. This can also be set via the |
466 | PERL_DL_DEBUG environment variable. Set to 1 for minimal information or |
467 | higher for more. |
468 | |
469 | =item dl_findfile() |
470 | |
471 | Syntax: |
472 | |
473 | @filepaths = dl_findfile(@names) |
474 | |
475 | Determine the full paths (including file suffix) of one or more |
476 | loadable files given their generic names and optionally one or more |
477 | directories. Searches directories in @dl_library_path by default and |
478 | returns an empty list if no files were found. |
479 | |
480 | Names can be specified in a variety of platform independent forms. Any |
481 | names in the form B<-lname> are converted into F<libname.*>, where F<.*> is |
482 | an appropriate suffix for the platform. |
483 | |
484 | If a name does not already have a suitable prefix and/or suffix then |
485 | the corresponding file will be searched for by trying combinations of |
486 | prefix and suffix appropriate to the platform: "$name.o", "lib$name.*" |
487 | and "$name". |
488 | |
489 | If any directories are included in @names they are searched before |
c2960299 |
490 | @dl_library_path. Directories may be specified as B<-Ldir>. Any other |
491 | names are treated as filenames to be searched for. |
3b35bae3 |
492 | |
493 | Using arguments of the form C<-Ldir> and C<-lname> is recommended. |
494 | |
495 | Example: |
496 | |
497 | @dl_resolve_using = dl_findfile(qw(-L/usr/5lib -lposix)); |
498 | |
499 | |
500 | =item dl_expandspec() |
501 | |
502 | Syntax: |
503 | |
504 | $filepath = dl_expandspec($spec) |
505 | |
506 | Some unusual systems, such as VMS, require special filename handling in |
507 | order to deal with symbolic names for files (i.e., VMS's Logical Names). |
508 | |
509 | To support these systems a dl_expandspec() function can be implemented |
510 | either in the F<dl_*.xs> file or code can be added to the autoloadable |
c2960299 |
511 | dl_expandspec() function in F<DynaLoader.pm>. See F<DynaLoader.pm> for |
512 | more information. |
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513 | |
514 | =item dl_load_file() |
515 | |
516 | Syntax: |
517 | |
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518 | $libref = dl_load_file($filename, $flags) |
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519 | |
520 | Dynamically load $filename, which must be the path to a shared object |
521 | or library. An opaque 'library reference' is returned as a handle for |
522 | the loaded object. Returns undef on error. |
523 | |
ff7f3c60 |
524 | The $flags argument to alters dl_load_file behaviour. |
525 | Assigned bits: |
526 | |
527 | 0x01 make symbols available for linking later dl_load_file's. |
528 | (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL)) |
f86702cc |
529 | (ignored under VMS; this is a normal part of image linking) |
ff7f3c60 |
530 | |
3b35bae3 |
531 | (On systems that provide a handle for the loaded object such as SunOS |
532 | and HPUX, $libref will be that handle. On other systems $libref will |
533 | typically be $filename or a pointer to a buffer containing $filename. |
534 | The application should not examine or alter $libref in any way.) |
535 | |
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536 | This is the function that does the real work. It should use the |
537 | current values of @dl_require_symbols and @dl_resolve_using if required. |
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538 | |
539 | SunOS: dlopen($filename) |
540 | HP-UX: shl_load($filename) |
541 | Linux: dld_create_reference(@dl_require_symbols); dld_link($filename) |
542 | NeXT: rld_load($filename, @dl_resolve_using) |
543 | VMS: lib$find_image_symbol($filename,$dl_require_symbols[0]) |
544 | |
ff7f3c60 |
545 | (The dlopen() function is also used by Solaris and some versions of |
546 | Linux, and is a common choice when providing a "wrapper" on other |
547 | mechanisms as is done in the OS/2 port.) |
548 | |
549 | =item dl_loadflags() |
550 | |
551 | Syntax: |
552 | |
553 | $flags = dl_loadflags $modulename; |
554 | |
555 | Designed to be a method call, and to be overridden by a derived class |
556 | (i.e. a class which has DynaLoader in its @ISA). The definition in |
557 | DynaLoader itself returns 0, which produces standard behavior from |
558 | dl_load_file(). |
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559 | |
560 | =item dl_find_symbol() |
561 | |
562 | Syntax: |
563 | |
564 | $symref = dl_find_symbol($libref, $symbol) |
565 | |
566 | Return the address of the symbol $symbol or C<undef> if not found. If the |
567 | target system has separate functions to search for symbols of different |
568 | types then dl_find_symbol() should search for function symbols first and |
569 | then other types. |
570 | |
571 | The exact manner in which the address is returned in $symref is not |
572 | currently defined. The only initial requirement is that $symref can |
573 | be passed to, and understood by, dl_install_xsub(). |
574 | |
575 | SunOS: dlsym($libref, $symbol) |
576 | HP-UX: shl_findsym($libref, $symbol) |
577 | Linux: dld_get_func($symbol) and/or dld_get_symbol($symbol) |
578 | NeXT: rld_lookup("_$symbol") |
579 | VMS: lib$find_image_symbol($libref,$symbol) |
580 | |
581 | |
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582 | =item dl_find_symbol_anywhere() |
583 | |
584 | Syntax: |
585 | |
586 | $symref = dl_find_symbol_anywhere($symbol) |
587 | |
588 | Applies dl_find_symbol() to the members of @dl_librefs and returns |
589 | the first match found. |
590 | |
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591 | =item dl_undef_symbols() |
592 | |
593 | Example |
594 | |
595 | @symbols = dl_undef_symbols() |
596 | |
597 | Return a list of symbol names which remain undefined after load_file(). |
598 | Returns C<()> if not known. Don't worry if your platform does not provide |
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599 | a mechanism for this. Most do not need it and hence do not provide it, |
600 | they just return an empty list. |
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601 | |
602 | |
603 | =item dl_install_xsub() |
604 | |
605 | Syntax: |
606 | |
607 | dl_install_xsub($perl_name, $symref [, $filename]) |
608 | |
609 | Create a new Perl external subroutine named $perl_name using $symref as |
610 | a pointer to the function which implements the routine. This is simply |
611 | a direct call to newXSUB(). Returns a reference to the installed |
612 | function. |
613 | |
614 | The $filename parameter is used by Perl to identify the source file for |
615 | the function if required by die(), caller() or the debugger. If |
616 | $filename is not defined then "DynaLoader" will be used. |
617 | |
618 | |
1fef88e7 |
619 | =item bootstrap() |
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620 | |
621 | Syntax: |
622 | |
623 | bootstrap($module) |
624 | |
625 | This is the normal entry point for automatic dynamic loading in Perl. |
626 | |
627 | It performs the following actions: |
628 | |
629 | =over 8 |
630 | |
631 | =item * |
632 | |
633 | locates an auto/$module directory by searching @INC |
634 | |
635 | =item * |
636 | |
637 | uses dl_findfile() to determine the filename to load |
638 | |
639 | =item * |
640 | |
641 | sets @dl_require_symbols to C<("boot_$module")> |
642 | |
643 | =item * |
644 | |
645 | executes an F<auto/$module/$module.bs> file if it exists |
646 | (typically used to add to @dl_resolve_using any files which |
647 | are required to load the module on the current platform) |
648 | |
649 | =item * |
650 | |
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651 | calls dl_load_flags() to determine how to load the file. |
652 | |
653 | =item * |
654 | |
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655 | calls dl_load_file() to load the file |
656 | |
657 | =item * |
658 | |
659 | calls dl_undef_symbols() and warns if any symbols are undefined |
660 | |
661 | =item * |
662 | |
663 | calls dl_find_symbol() for "boot_$module" |
664 | |
665 | =item * |
666 | |
667 | calls dl_install_xsub() to install it as "${module}::bootstrap" |
668 | |
669 | =item * |
670 | |
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671 | calls &{"${module}::bootstrap"} to bootstrap the module (actually |
672 | it uses the function reference returned by dl_install_xsub for speed) |
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673 | |
674 | =back |
675 | |
676 | =back |
677 | |
678 | |
679 | =head1 AUTHOR |
680 | |
c2960299 |
681 | Tim Bunce, 11 August 1994. |
682 | |
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683 | This interface is based on the work and comments of (in no particular |
684 | order): Larry Wall, Robert Sanders, Dean Roehrich, Jeff Okamoto, Anno |
c2960299 |
685 | Siegel, Thomas Neumann, Paul Marquess, Charles Bailey, myself and others. |
3b35bae3 |
686 | |
687 | Larry Wall designed the elegant inherited bootstrap mechanism and |
688 | implemented the first Perl 5 dynamic loader using it. |
689 | |
ff7f3c60 |
690 | Solaris global loading added by Nick Ing-Simmons with design/coding |
691 | assistance from Tim Bunce, January 1996. |
692 | |
3b35bae3 |
693 | =cut |