| 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 = '1.05'; # 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_shared_objects = (); # shared objects for symbols we have |
| 71 | #@dl_librefs = (); # things we have loaded |
| 72 | #@dl_modules = (); # Modules we have loaded |
| 73 | |
| 74 | # This is a fix to support DLD's unfortunate desire to relink -lc |
| 75 | @dl_resolve_using = dl_findfile('-lc') if $dlsrc eq "dl_dld.xs"; |
| 76 | |
| 77 | # Initialise @dl_library_path with the 'standard' library path |
| 78 | # for this platform as determined by Configure. |
| 79 | |
| 80 | push(@dl_library_path, split(' ', $Config::Config{libpth})); |
| 81 | |
| 82 | |
| 83 | my $ldlibpthname = $Config::Config{ldlibpthname}; |
| 84 | my $ldlibpthname_defined = defined $Config::Config{ldlibpthname}; |
| 85 | my $pthsep = $Config::Config{path_sep}; |
| 86 | |
| 87 | # Add to @dl_library_path any extra directories we can gather from environment |
| 88 | # during runtime. |
| 89 | |
| 90 | if ($ldlibpthname_defined && |
| 91 | exists $ENV{$ldlibpthname}) { |
| 92 | push(@dl_library_path, split(/$pthsep/, $ENV{$ldlibpthname})); |
| 93 | } |
| 94 | |
| 95 | # E.g. HP-UX supports both its native SHLIB_PATH *and* LD_LIBRARY_PATH. |
| 96 | |
| 97 | if ($ldlibpthname_defined && |
| 98 | $ldlibpthname ne 'LD_LIBRARY_PATH' && |
| 99 | exists $ENV{LD_LIBRARY_PATH}) { |
| 100 | push(@dl_library_path, split(/$pthsep/, $ENV{LD_LIBRARY_PATH})); |
| 101 | } |
| 102 | |
| 103 | |
| 104 | # No prizes for guessing why we don't say 'bootstrap DynaLoader;' here. |
| 105 | # NOTE: All dl_*.xs (including dl_none.xs) define a dl_error() XSUB |
| 106 | boot_DynaLoader('DynaLoader') if defined(&boot_DynaLoader) && |
| 107 | !defined(&dl_error); |
| 108 | |
| 109 | if ($dl_debug) { |
| 110 | print STDERR "DynaLoader.pm loaded (@INC, @dl_library_path)\n"; |
| 111 | print STDERR "DynaLoader not linked into this perl\n" |
| 112 | unless defined(&boot_DynaLoader); |
| 113 | } |
| 114 | |
| 115 | 1; # End of main code |
| 116 | |
| 117 | |
| 118 | sub croak { require Carp; Carp::croak(@_) } |
| 119 | |
| 120 | sub bootstrap_inherit { |
| 121 | my $module = $_[0]; |
| 122 | local *isa = *{"$module\::ISA"}; |
| 123 | local @isa = (@isa, 'DynaLoader'); |
| 124 | # Cannot goto due to delocalization. Will report errors on a wrong line? |
| 125 | bootstrap(@_); |
| 126 | } |
| 127 | |
| 128 | # The bootstrap function cannot be autoloaded (without complications) |
| 129 | # so we define it here: |
| 130 | |
| 131 | sub bootstrap { |
| 132 | # use local vars to enable $module.bs script to edit values |
| 133 | local(@args) = @_; |
| 134 | local($module) = $args[0]; |
| 135 | local(@dirs, $file); |
| 136 | |
| 137 | unless ($module) { |
| 138 | require Carp; |
| 139 | Carp::confess("Usage: DynaLoader::bootstrap(module)"); |
| 140 | } |
| 141 | |
| 142 | # A common error on platforms which don't support dynamic loading. |
| 143 | # Since it's fatal and potentially confusing we give a detailed message. |
| 144 | croak("Can't load module $module, dynamic loading not available in this perl.\n". |
| 145 | " (You may need to build a new perl executable which either supports\n". |
| 146 | " dynamic loading or has the $module module statically linked into it.)\n") |
| 147 | unless defined(&dl_load_file); |
| 148 | |
| 149 | my @modparts = split(/::/,$module); |
| 150 | my $modfname = $modparts[-1]; |
| 151 | |
| 152 | # Some systems have restrictions on files names for DLL's etc. |
| 153 | # mod2fname returns appropriate file base name (typically truncated) |
| 154 | # It may also edit @modparts if required. |
| 155 | $modfname = &mod2fname(\@modparts) if defined &mod2fname; |
| 156 | |
| 157 | # Truncate the module name to 8.3 format for NetWare |
| 158 | if (($^O eq 'NetWare') && (length($modfname) > 8)) { |
| 159 | $modfname = substr($modfname, 0, 8); |
| 160 | } |
| 161 | |
| 162 | my $modpname = join(($Is_MacOS ? ':' : '/'),@modparts); |
| 163 | |
| 164 | print STDERR "DynaLoader::bootstrap for $module ", |
| 165 | ($Is_MacOS |
| 166 | ? "(:auto:$modpname:$modfname.$dl_dlext)\n" : |
| 167 | "(auto/$modpname/$modfname.$dl_dlext)\n") |
| 168 | if $dl_debug; |
| 169 | |
| 170 | foreach (@INC) { |
| 171 | chop($_ = VMS::Filespec::unixpath($_)) if $Is_VMS; |
| 172 | my $dir; |
| 173 | if ($Is_MacOS) { |
| 174 | my $path = $_; |
| 175 | if ($Mac_FS && ! -d $path) { |
| 176 | $path = Mac::FileSpec::Unixish::nativize($path); |
| 177 | } |
| 178 | $path .= ":" unless /:$/; |
| 179 | $dir = "${path}auto:$modpname"; |
| 180 | } else { |
| 181 | $dir = "$_/auto/$modpname"; |
| 182 | } |
| 183 | |
| 184 | next unless -d $dir; # skip over uninteresting directories |
| 185 | |
| 186 | # check for common cases to avoid autoload of dl_findfile |
| 187 | my $try = $Is_MacOS ? "$dir:$modfname.$dl_dlext" : "$dir/$modfname.$dl_dlext"; |
| 188 | last if $file = ($do_expand) ? dl_expandspec($try) : ((-f $try) && $try); |
| 189 | |
| 190 | # no luck here, save dir for possible later dl_findfile search |
| 191 | push @dirs, $dir; |
| 192 | } |
| 193 | # last resort, let dl_findfile have a go in all known locations |
| 194 | $file = dl_findfile(map("-L$_",@dirs,@INC), $modfname) unless $file; |
| 195 | |
| 196 | croak("Can't locate loadable object for module $module in \@INC (\@INC contains: @INC)") |
| 197 | unless $file; # wording similar to error from 'require' |
| 198 | |
| 199 | $file = uc($file) if $Is_VMS && $Config::Config{d_vms_case_sensitive_symbols}; |
| 200 | my $bootname = "boot_$module"; |
| 201 | $bootname =~ s/\W/_/g; |
| 202 | @dl_require_symbols = ($bootname); |
| 203 | |
| 204 | # Execute optional '.bootstrap' perl script for this module. |
| 205 | # The .bs file can be used to configure @dl_resolve_using etc to |
| 206 | # match the needs of the individual module on this architecture. |
| 207 | my $bs = $file; |
| 208 | $bs =~ s/(\.\w+)?(;\d*)?$/\.bs/; # look for .bs 'beside' the library |
| 209 | if (-s $bs) { # only read file if it's not empty |
| 210 | print STDERR "BS: $bs ($^O, $dlsrc)\n" if $dl_debug; |
| 211 | eval { do $bs; }; |
| 212 | warn "$bs: $@\n" if $@; |
| 213 | } |
| 214 | |
| 215 | my $boot_symbol_ref; |
| 216 | |
| 217 | if ($^O eq 'darwin') { |
| 218 | if ($boot_symbol_ref = dl_find_symbol(0, $bootname)) { |
| 219 | goto boot; #extension library has already been loaded, e.g. darwin |
| 220 | } |
| 221 | } |
| 222 | |
| 223 | # Many dynamic extension loading problems will appear to come from |
| 224 | # this section of code: XYZ failed at line 123 of DynaLoader.pm. |
| 225 | # Often these errors are actually occurring in the initialisation |
| 226 | # C code of the extension XS file. Perl reports the error as being |
| 227 | # in this perl code simply because this was the last perl code |
| 228 | # it executed. |
| 229 | |
| 230 | my $libref = dl_load_file($file, $module->dl_load_flags) or |
| 231 | croak("Can't load '$file' for module $module: ".dl_error()); |
| 232 | |
| 233 | push(@dl_librefs,$libref); # record loaded object |
| 234 | |
| 235 | my @unresolved = dl_undef_symbols(); |
| 236 | if (@unresolved) { |
| 237 | require Carp; |
| 238 | Carp::carp("Undefined symbols present after loading $file: @unresolved\n"); |
| 239 | } |
| 240 | |
| 241 | $boot_symbol_ref = dl_find_symbol($libref, $bootname) or |
| 242 | croak("Can't find '$bootname' symbol in $file\n"); |
| 243 | |
| 244 | push(@dl_modules, $module); # record loaded module |
| 245 | |
| 246 | boot: |
| 247 | my $xs = dl_install_xsub("${module}::bootstrap", $boot_symbol_ref, $file); |
| 248 | |
| 249 | # See comment block above |
| 250 | |
| 251 | push(@dl_shared_objects, $file); # record files loaded |
| 252 | |
| 253 | &$xs(@args); |
| 254 | } |
| 255 | |
| 256 | |
| 257 | #sub _check_file { # private utility to handle dl_expandspec vs -f tests |
| 258 | # my($file) = @_; |
| 259 | # return $file if (!$do_expand && -f $file); # the common case |
| 260 | # return $file if ( $do_expand && ($file=dl_expandspec($file))); |
| 261 | # return undef; |
| 262 | #} |
| 263 | |
| 264 | |
| 265 | # Let autosplit and the autoloader deal with these functions: |
| 266 | __END__ |
| 267 | |
| 268 | |
| 269 | sub dl_findfile { |
| 270 | # Read ext/DynaLoader/DynaLoader.doc for detailed information. |
| 271 | # This function does not automatically consider the architecture |
| 272 | # or the perl library auto directories. |
| 273 | my (@args) = @_; |
| 274 | my (@dirs, $dir); # which directories to search |
| 275 | my (@found); # full paths to real files we have found |
| 276 | my $dl_ext= 'so'; # $Config::Config{'dlext'} suffix for perl extensions |
| 277 | my $dl_so = 'so'; # $Config::Config{'so'} suffix for shared libraries |
| 278 | |
| 279 | print STDERR "dl_findfile(@args)\n" if $dl_debug; |
| 280 | |
| 281 | # accumulate directories but process files as they appear |
| 282 | arg: foreach(@args) { |
| 283 | # Special fast case: full filepath requires no search |
| 284 | if ($Is_VMS && m%[:>/\]]% && -f $_) { |
| 285 | push(@found,dl_expandspec(VMS::Filespec::vmsify($_))); |
| 286 | last arg unless wantarray; |
| 287 | next; |
| 288 | } |
| 289 | elsif ($Is_MacOS) { |
| 290 | if (m/:/ && -f $_) { |
| 291 | push(@found,$_); |
| 292 | last arg unless wantarray; |
| 293 | } |
| 294 | } |
| 295 | elsif (m:/: && -f $_ && !$do_expand) { |
| 296 | push(@found,$_); |
| 297 | last arg unless wantarray; |
| 298 | next; |
| 299 | } |
| 300 | |
| 301 | # Deal with directories first: |
| 302 | # Using a -L prefix is the preferred option (faster and more robust) |
| 303 | if (m:^-L:) { s/^-L//; push(@dirs, $_); next; } |
| 304 | |
| 305 | if ($Is_MacOS) { |
| 306 | # Otherwise we try to try to spot directories by a heuristic |
| 307 | # (this is a more complicated issue than it first appears) |
| 308 | if (m/:/ && -d $_) { push(@dirs, $_); next; } |
| 309 | # Only files should get this far... |
| 310 | my(@names, $name); # what filenames to look for |
| 311 | s/^-l//; |
| 312 | push(@names, $_); |
| 313 | foreach $dir (@dirs, @dl_library_path) { |
| 314 | next unless -d $dir; |
| 315 | $dir =~ s/^([^:]+)$/:$1/; |
| 316 | $dir =~ s/:$//; |
| 317 | foreach $name (@names) { |
| 318 | my($file) = "$dir:$name"; |
| 319 | print STDERR " checking in $dir for $name\n" if $dl_debug; |
| 320 | if (-f $file) { |
| 321 | push(@found, $file); |
| 322 | next arg; # no need to look any further |
| 323 | } |
| 324 | } |
| 325 | } |
| 326 | next; |
| 327 | } |
| 328 | |
| 329 | # Otherwise we try to try to spot directories by a heuristic |
| 330 | # (this is a more complicated issue than it first appears) |
| 331 | if (m:/: && -d $_) { push(@dirs, $_); next; } |
| 332 | |
| 333 | # VMS: we may be using native VMS directory syntax instead of |
| 334 | # Unix emulation, so check this as well |
| 335 | if ($Is_VMS && /[:>\]]/ && -d $_) { push(@dirs, $_); next; } |
| 336 | |
| 337 | # Only files should get this far... |
| 338 | my(@names, $name); # what filenames to look for |
| 339 | if (m:-l: ) { # convert -lname to appropriate library name |
| 340 | s/-l//; |
| 341 | push(@names,"lib$_.$dl_so"); |
| 342 | push(@names,"lib$_.a"); |
| 343 | } else { # Umm, a bare name. Try various alternatives: |
| 344 | # these should be ordered with the most likely first |
| 345 | push(@names,"$_.$dl_ext") unless m/\.$dl_ext$/o; |
| 346 | push(@names,"$_.$dl_so") unless m/\.$dl_so$/o; |
| 347 | push(@names,"lib$_.$dl_so") unless m:/:; |
| 348 | push(@names,"$_.a") if !m/\.a$/ and $dlsrc eq "dl_dld.xs"; |
| 349 | push(@names, $_); |
| 350 | } |
| 351 | foreach $dir (@dirs, @dl_library_path) { |
| 352 | next unless -d $dir; |
| 353 | chop($dir = VMS::Filespec::unixpath($dir)) if $Is_VMS; |
| 354 | foreach $name (@names) { |
| 355 | my($file) = "$dir/$name"; |
| 356 | print STDERR " checking in $dir for $name\n" if $dl_debug; |
| 357 | $file = ($do_expand) ? dl_expandspec($file) : (-f $file && $file); |
| 358 | #$file = _check_file($file); |
| 359 | if ($file) { |
| 360 | push(@found, $file); |
| 361 | next arg; # no need to look any further |
| 362 | } |
| 363 | } |
| 364 | } |
| 365 | } |
| 366 | if ($dl_debug) { |
| 367 | foreach(@dirs) { |
| 368 | print STDERR " dl_findfile ignored non-existent directory: $_\n" unless -d $_; |
| 369 | } |
| 370 | print STDERR "dl_findfile found: @found\n"; |
| 371 | } |
| 372 | return $found[0] unless wantarray; |
| 373 | @found; |
| 374 | } |
| 375 | |
| 376 | |
| 377 | sub dl_expandspec { |
| 378 | my($spec) = @_; |
| 379 | # Optional function invoked if DynaLoader.pm sets $do_expand. |
| 380 | # Most systems do not require or use this function. |
| 381 | # Some systems may implement it in the dl_*.xs file in which case |
| 382 | # this autoload version will not be called but is harmless. |
| 383 | |
| 384 | # This function is designed to deal with systems which treat some |
| 385 | # 'filenames' in a special way. For example VMS 'Logical Names' |
| 386 | # (something like unix environment variables - but different). |
| 387 | # This function should recognise such names and expand them into |
| 388 | # full file paths. |
| 389 | # Must return undef if $spec is invalid or file does not exist. |
| 390 | |
| 391 | my $file = $spec; # default output to input |
| 392 | |
| 393 | if ($Is_VMS) { # dl_expandspec should be defined in dl_vms.xs |
| 394 | require Carp; |
| 395 | Carp::croak("dl_expandspec: should be defined in XS file!\n"); |
| 396 | } else { |
| 397 | return undef unless -f $file; |
| 398 | } |
| 399 | print STDERR "dl_expandspec($spec) => $file\n" if $dl_debug; |
| 400 | $file; |
| 401 | } |
| 402 | |
| 403 | sub dl_find_symbol_anywhere |
| 404 | { |
| 405 | my $sym = shift; |
| 406 | my $libref; |
| 407 | foreach $libref (@dl_librefs) { |
| 408 | my $symref = dl_find_symbol($libref,$sym); |
| 409 | return $symref if $symref; |
| 410 | } |
| 411 | return undef; |
| 412 | } |
| 413 | |
| 414 | =head1 NAME |
| 415 | |
| 416 | DynaLoader - Dynamically load C libraries into Perl code |
| 417 | |
| 418 | =head1 SYNOPSIS |
| 419 | |
| 420 | package YourPackage; |
| 421 | require DynaLoader; |
| 422 | @ISA = qw(... DynaLoader ...); |
| 423 | bootstrap YourPackage; |
| 424 | |
| 425 | # optional method for 'global' loading |
| 426 | sub dl_load_flags { 0x01 } |
| 427 | |
| 428 | |
| 429 | =head1 DESCRIPTION |
| 430 | |
| 431 | This document defines a standard generic interface to the dynamic |
| 432 | linking mechanisms available on many platforms. Its primary purpose is |
| 433 | to implement automatic dynamic loading of Perl modules. |
| 434 | |
| 435 | This document serves as both a specification for anyone wishing to |
| 436 | implement the DynaLoader for a new platform and as a guide for |
| 437 | anyone wishing to use the DynaLoader directly in an application. |
| 438 | |
| 439 | The DynaLoader is designed to be a very simple high-level |
| 440 | interface that is sufficiently general to cover the requirements |
| 441 | of SunOS, HP-UX, NeXT, Linux, VMS and other platforms. |
| 442 | |
| 443 | It is also hoped that the interface will cover the needs of OS/2, NT |
| 444 | etc and also allow pseudo-dynamic linking (using C<ld -A> at runtime). |
| 445 | |
| 446 | It must be stressed that the DynaLoader, by itself, is practically |
| 447 | useless for accessing non-Perl libraries because it provides almost no |
| 448 | Perl-to-C 'glue'. There is, for example, no mechanism for calling a C |
| 449 | library function or supplying arguments. A C::DynaLib module |
| 450 | is available from CPAN sites which performs that function for some |
| 451 | common system types. And since the year 2000, there's also Inline::C, |
| 452 | a module that allows you to write Perl subroutines in C. Also available |
| 453 | from your local CPAN site. |
| 454 | |
| 455 | DynaLoader Interface Summary |
| 456 | |
| 457 | @dl_library_path |
| 458 | @dl_resolve_using |
| 459 | @dl_require_symbols |
| 460 | $dl_debug |
| 461 | @dl_librefs |
| 462 | @dl_modules |
| 463 | @dl_shared_objects |
| 464 | Implemented in: |
| 465 | bootstrap($modulename) Perl |
| 466 | @filepaths = dl_findfile(@names) Perl |
| 467 | $flags = $modulename->dl_load_flags Perl |
| 468 | $symref = dl_find_symbol_anywhere($symbol) Perl |
| 469 | |
| 470 | $libref = dl_load_file($filename, $flags) C |
| 471 | $status = dl_unload_file($libref) C |
| 472 | $symref = dl_find_symbol($libref, $symbol) C |
| 473 | @symbols = dl_undef_symbols() C |
| 474 | dl_install_xsub($name, $symref [, $filename]) C |
| 475 | $message = dl_error C |
| 476 | |
| 477 | =over 4 |
| 478 | |
| 479 | =item @dl_library_path |
| 480 | |
| 481 | The standard/default list of directories in which dl_findfile() will |
| 482 | search for libraries etc. Directories are searched in order: |
| 483 | $dl_library_path[0], [1], ... etc |
| 484 | |
| 485 | @dl_library_path is initialised to hold the list of 'normal' directories |
| 486 | (F</usr/lib>, etc) determined by B<Configure> (C<$Config{'libpth'}>). This should |
| 487 | ensure portability across a wide range of platforms. |
| 488 | |
| 489 | @dl_library_path should also be initialised with any other directories |
| 490 | that can be determined from the environment at runtime (such as |
| 491 | LD_LIBRARY_PATH for SunOS). |
| 492 | |
| 493 | After initialisation @dl_library_path can be manipulated by an |
| 494 | application using push and unshift before calling dl_findfile(). |
| 495 | Unshift can be used to add directories to the front of the search order |
| 496 | either to save search time or to override libraries with the same name |
| 497 | in the 'normal' directories. |
| 498 | |
| 499 | The load function that dl_load_file() calls may require an absolute |
| 500 | pathname. The dl_findfile() function and @dl_library_path can be |
| 501 | used to search for and return the absolute pathname for the |
| 502 | library/object that you wish to load. |
| 503 | |
| 504 | =item @dl_resolve_using |
| 505 | |
| 506 | A list of additional libraries or other shared objects which can be |
| 507 | used to resolve any undefined symbols that might be generated by a |
| 508 | later call to load_file(). |
| 509 | |
| 510 | This is only required on some platforms which do not handle dependent |
| 511 | libraries automatically. For example the Socket Perl extension |
| 512 | library (F<auto/Socket/Socket.so>) contains references to many socket |
| 513 | functions which need to be resolved when it's loaded. Most platforms |
| 514 | will automatically know where to find the 'dependent' library (e.g., |
| 515 | F</usr/lib/libsocket.so>). A few platforms need to be told the |
| 516 | location of the dependent library explicitly. Use @dl_resolve_using |
| 517 | for this. |
| 518 | |
| 519 | Example usage: |
| 520 | |
| 521 | @dl_resolve_using = dl_findfile('-lsocket'); |
| 522 | |
| 523 | =item @dl_require_symbols |
| 524 | |
| 525 | A list of one or more symbol names that are in the library/object file |
| 526 | to be dynamically loaded. This is only required on some platforms. |
| 527 | |
| 528 | =item @dl_librefs |
| 529 | |
| 530 | An array of the handles returned by successful calls to dl_load_file(), |
| 531 | made by bootstrap, in the order in which they were loaded. |
| 532 | Can be used with dl_find_symbol() to look for a symbol in any of |
| 533 | the loaded files. |
| 534 | |
| 535 | =item @dl_modules |
| 536 | |
| 537 | An array of module (package) names that have been bootstrap'ed. |
| 538 | |
| 539 | =item @dl_shared_objects |
| 540 | |
| 541 | An array of file names for the shared objects that were loaded. |
| 542 | |
| 543 | =item dl_error() |
| 544 | |
| 545 | Syntax: |
| 546 | |
| 547 | $message = dl_error(); |
| 548 | |
| 549 | Error message text from the last failed DynaLoader function. Note |
| 550 | that, similar to errno in unix, a successful function call does not |
| 551 | reset this message. |
| 552 | |
| 553 | Implementations should detect the error as soon as it occurs in any of |
| 554 | the other functions and save the corresponding message for later |
| 555 | retrieval. This will avoid problems on some platforms (such as SunOS) |
| 556 | where the error message is very temporary (e.g., dlerror()). |
| 557 | |
| 558 | =item $dl_debug |
| 559 | |
| 560 | Internal debugging messages are enabled when $dl_debug is set true. |
| 561 | Currently setting $dl_debug only affects the Perl side of the |
| 562 | DynaLoader. These messages should help an application developer to |
| 563 | resolve any DynaLoader usage problems. |
| 564 | |
| 565 | $dl_debug is set to C<$ENV{'PERL_DL_DEBUG'}> if defined. |
| 566 | |
| 567 | For the DynaLoader developer/porter there is a similar debugging |
| 568 | variable added to the C code (see dlutils.c) and enabled if Perl was |
| 569 | built with the B<-DDEBUGGING> flag. This can also be set via the |
| 570 | PERL_DL_DEBUG environment variable. Set to 1 for minimal information or |
| 571 | higher for more. |
| 572 | |
| 573 | =item dl_findfile() |
| 574 | |
| 575 | Syntax: |
| 576 | |
| 577 | @filepaths = dl_findfile(@names) |
| 578 | |
| 579 | Determine the full paths (including file suffix) of one or more |
| 580 | loadable files given their generic names and optionally one or more |
| 581 | directories. Searches directories in @dl_library_path by default and |
| 582 | returns an empty list if no files were found. |
| 583 | |
| 584 | Names can be specified in a variety of platform independent forms. Any |
| 585 | names in the form B<-lname> are converted into F<libname.*>, where F<.*> is |
| 586 | an appropriate suffix for the platform. |
| 587 | |
| 588 | If a name does not already have a suitable prefix and/or suffix then |
| 589 | the corresponding file will be searched for by trying combinations of |
| 590 | prefix and suffix appropriate to the platform: "$name.o", "lib$name.*" |
| 591 | and "$name". |
| 592 | |
| 593 | If any directories are included in @names they are searched before |
| 594 | @dl_library_path. Directories may be specified as B<-Ldir>. Any other |
| 595 | names are treated as filenames to be searched for. |
| 596 | |
| 597 | Using arguments of the form C<-Ldir> and C<-lname> is recommended. |
| 598 | |
| 599 | Example: |
| 600 | |
| 601 | @dl_resolve_using = dl_findfile(qw(-L/usr/5lib -lposix)); |
| 602 | |
| 603 | |
| 604 | =item dl_expandspec() |
| 605 | |
| 606 | Syntax: |
| 607 | |
| 608 | $filepath = dl_expandspec($spec) |
| 609 | |
| 610 | Some unusual systems, such as VMS, require special filename handling in |
| 611 | order to deal with symbolic names for files (i.e., VMS's Logical Names). |
| 612 | |
| 613 | To support these systems a dl_expandspec() function can be implemented |
| 614 | either in the F<dl_*.xs> file or code can be added to the autoloadable |
| 615 | dl_expandspec() function in F<DynaLoader.pm>. See F<DynaLoader.pm> for |
| 616 | more information. |
| 617 | |
| 618 | =item dl_load_file() |
| 619 | |
| 620 | Syntax: |
| 621 | |
| 622 | $libref = dl_load_file($filename, $flags) |
| 623 | |
| 624 | Dynamically load $filename, which must be the path to a shared object |
| 625 | or library. An opaque 'library reference' is returned as a handle for |
| 626 | the loaded object. Returns undef on error. |
| 627 | |
| 628 | The $flags argument to alters dl_load_file behaviour. |
| 629 | Assigned bits: |
| 630 | |
| 631 | 0x01 make symbols available for linking later dl_load_file's. |
| 632 | (only known to work on Solaris 2 using dlopen(RTLD_GLOBAL)) |
| 633 | (ignored under VMS; this is a normal part of image linking) |
| 634 | |
| 635 | (On systems that provide a handle for the loaded object such as SunOS |
| 636 | and HPUX, $libref will be that handle. On other systems $libref will |
| 637 | typically be $filename or a pointer to a buffer containing $filename. |
| 638 | The application should not examine or alter $libref in any way.) |
| 639 | |
| 640 | This is the function that does the real work. It should use the |
| 641 | current values of @dl_require_symbols and @dl_resolve_using if required. |
| 642 | |
| 643 | SunOS: dlopen($filename) |
| 644 | HP-UX: shl_load($filename) |
| 645 | Linux: dld_create_reference(@dl_require_symbols); dld_link($filename) |
| 646 | NeXT: rld_load($filename, @dl_resolve_using) |
| 647 | VMS: lib$find_image_symbol($filename,$dl_require_symbols[0]) |
| 648 | |
| 649 | (The dlopen() function is also used by Solaris and some versions of |
| 650 | Linux, and is a common choice when providing a "wrapper" on other |
| 651 | mechanisms as is done in the OS/2 port.) |
| 652 | |
| 653 | =item dl_unload_file() |
| 654 | |
| 655 | Syntax: |
| 656 | |
| 657 | $status = dl_unload_file($libref) |
| 658 | |
| 659 | Dynamically unload $libref, which must be an opaque 'library reference' as |
| 660 | returned from dl_load_file. Returns one on success and zero on failure. |
| 661 | |
| 662 | This function is optional and may not necessarily be provided on all platforms. |
| 663 | If it is defined, it is called automatically when the interpreter exits for |
| 664 | every shared object or library loaded by DynaLoader::bootstrap. All such |
| 665 | library references are stored in @dl_librefs by DynaLoader::Bootstrap as it |
| 666 | loads the libraries. The files are unloaded in last-in, first-out order. |
| 667 | |
| 668 | This unloading is usually necessary when embedding a shared-object perl (e.g. |
| 669 | one configured with -Duseshrplib) within a larger application, and the perl |
| 670 | interpreter is created and destroyed several times within the lifetime of the |
| 671 | application. In this case it is possible that the system dynamic linker will |
| 672 | unload and then subsequently reload the shared libperl without relocating any |
| 673 | references to it from any files DynaLoaded by the previous incarnation of the |
| 674 | interpreter. As a result, any shared objects opened by DynaLoader may point to |
| 675 | a now invalid 'ghost' of the libperl shared object, causing apparently random |
| 676 | memory corruption and crashes. This behaviour is most commonly seen when using |
| 677 | Apache and mod_perl built with the APXS mechanism. |
| 678 | |
| 679 | SunOS: dlclose($libref) |
| 680 | HP-UX: ??? |
| 681 | Linux: ??? |
| 682 | NeXT: ??? |
| 683 | VMS: ??? |
| 684 | |
| 685 | (The dlclose() function is also used by Solaris and some versions of |
| 686 | Linux, and is a common choice when providing a "wrapper" on other |
| 687 | mechanisms as is done in the OS/2 port.) |
| 688 | |
| 689 | =item dl_load_flags() |
| 690 | |
| 691 | Syntax: |
| 692 | |
| 693 | $flags = dl_load_flags $modulename; |
| 694 | |
| 695 | Designed to be a method call, and to be overridden by a derived class |
| 696 | (i.e. a class which has DynaLoader in its @ISA). The definition in |
| 697 | DynaLoader itself returns 0, which produces standard behavior from |
| 698 | dl_load_file(). |
| 699 | |
| 700 | =item dl_find_symbol() |
| 701 | |
| 702 | Syntax: |
| 703 | |
| 704 | $symref = dl_find_symbol($libref, $symbol) |
| 705 | |
| 706 | Return the address of the symbol $symbol or C<undef> if not found. If the |
| 707 | target system has separate functions to search for symbols of different |
| 708 | types then dl_find_symbol() should search for function symbols first and |
| 709 | then other types. |
| 710 | |
| 711 | The exact manner in which the address is returned in $symref is not |
| 712 | currently defined. The only initial requirement is that $symref can |
| 713 | be passed to, and understood by, dl_install_xsub(). |
| 714 | |
| 715 | SunOS: dlsym($libref, $symbol) |
| 716 | HP-UX: shl_findsym($libref, $symbol) |
| 717 | Linux: dld_get_func($symbol) and/or dld_get_symbol($symbol) |
| 718 | NeXT: rld_lookup("_$symbol") |
| 719 | VMS: lib$find_image_symbol($libref,$symbol) |
| 720 | |
| 721 | |
| 722 | =item dl_find_symbol_anywhere() |
| 723 | |
| 724 | Syntax: |
| 725 | |
| 726 | $symref = dl_find_symbol_anywhere($symbol) |
| 727 | |
| 728 | Applies dl_find_symbol() to the members of @dl_librefs and returns |
| 729 | the first match found. |
| 730 | |
| 731 | =item dl_undef_symbols() |
| 732 | |
| 733 | Example |
| 734 | |
| 735 | @symbols = dl_undef_symbols() |
| 736 | |
| 737 | Return a list of symbol names which remain undefined after load_file(). |
| 738 | Returns C<()> if not known. Don't worry if your platform does not provide |
| 739 | a mechanism for this. Most do not need it and hence do not provide it, |
| 740 | they just return an empty list. |
| 741 | |
| 742 | |
| 743 | =item dl_install_xsub() |
| 744 | |
| 745 | Syntax: |
| 746 | |
| 747 | dl_install_xsub($perl_name, $symref [, $filename]) |
| 748 | |
| 749 | Create a new Perl external subroutine named $perl_name using $symref as |
| 750 | a pointer to the function which implements the routine. This is simply |
| 751 | a direct call to newXSUB(). Returns a reference to the installed |
| 752 | function. |
| 753 | |
| 754 | The $filename parameter is used by Perl to identify the source file for |
| 755 | the function if required by die(), caller() or the debugger. If |
| 756 | $filename is not defined then "DynaLoader" will be used. |
| 757 | |
| 758 | |
| 759 | =item bootstrap() |
| 760 | |
| 761 | Syntax: |
| 762 | |
| 763 | bootstrap($module) |
| 764 | |
| 765 | This is the normal entry point for automatic dynamic loading in Perl. |
| 766 | |
| 767 | It performs the following actions: |
| 768 | |
| 769 | =over 8 |
| 770 | |
| 771 | =item * |
| 772 | |
| 773 | locates an auto/$module directory by searching @INC |
| 774 | |
| 775 | =item * |
| 776 | |
| 777 | uses dl_findfile() to determine the filename to load |
| 778 | |
| 779 | =item * |
| 780 | |
| 781 | sets @dl_require_symbols to C<("boot_$module")> |
| 782 | |
| 783 | =item * |
| 784 | |
| 785 | executes an F<auto/$module/$module.bs> file if it exists |
| 786 | (typically used to add to @dl_resolve_using any files which |
| 787 | are required to load the module on the current platform) |
| 788 | |
| 789 | =item * |
| 790 | |
| 791 | calls dl_load_flags() to determine how to load the file. |
| 792 | |
| 793 | =item * |
| 794 | |
| 795 | calls dl_load_file() to load the file |
| 796 | |
| 797 | =item * |
| 798 | |
| 799 | calls dl_undef_symbols() and warns if any symbols are undefined |
| 800 | |
| 801 | =item * |
| 802 | |
| 803 | calls dl_find_symbol() for "boot_$module" |
| 804 | |
| 805 | =item * |
| 806 | |
| 807 | calls dl_install_xsub() to install it as "${module}::bootstrap" |
| 808 | |
| 809 | =item * |
| 810 | |
| 811 | calls &{"${module}::bootstrap"} to bootstrap the module (actually |
| 812 | it uses the function reference returned by dl_install_xsub for speed) |
| 813 | |
| 814 | =back |
| 815 | |
| 816 | =back |
| 817 | |
| 818 | |
| 819 | =head1 AUTHOR |
| 820 | |
| 821 | Tim Bunce, 11 August 1994. |
| 822 | |
| 823 | This interface is based on the work and comments of (in no particular |
| 824 | order): Larry Wall, Robert Sanders, Dean Roehrich, Jeff Okamoto, Anno |
| 825 | Siegel, Thomas Neumann, Paul Marquess, Charles Bailey, myself and others. |
| 826 | |
| 827 | Larry Wall designed the elegant inherited bootstrap mechanism and |
| 828 | implemented the first Perl 5 dynamic loader using it. |
| 829 | |
| 830 | Solaris global loading added by Nick Ing-Simmons with design/coding |
| 831 | assistance from Tim Bunce, January 1996. |
| 832 | |
| 833 | =cut |