v1/chuck_dl.cpp

   1 /*----------------------------------------------------------------------------
   2     ChucK Concurrent, On-the-fly Audio Programming Language
   3       Compiler and Virtual Machine
   4
   5     Copyright (c) 2004 Ge Wang and Perry R. Cook.  All rights reserved.
   6       http://chuck.cs.princeton.edu/
   7       http://soundlab.cs.princeton.edu/
   8
   9     This program is free software; you can redistribute it and/or modify
  10     it under the terms of the GNU General Public License as published by
  11     the Free Software Foundation; either version 2 of the License, or
  12     (at your option) any later version.
  13
  14     This program is distributed in the hope that it will be useful,
  15     but WITHOUT ANY WARRANTY; without even the implied warranty of
  16     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17     GNU General Public License for more details.
  18
  19     You should have received a copy of the GNU General Public License
  20     along with this program; if not, write to the Free Software
  21     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  22     U.S.A.
  23 -----------------------------------------------------------------------------*/
  24
  25 //-----------------------------------------------------------------------------
  26 // name: chuck_dl.cpp
  27 // desc: chuck dynamic linking
  28 //
  29 // authors: Ge Wang (gewang@cs.princeton.edu)
  30 //          Perry R. Cook (prc@cs.princeton.edu)
  31 // mac code from apple
  32 //
  33 // date: spring 2004
  34 //-----------------------------------------------------------------------------
  35 #include "chuck_dl.h"
  36 #ifndef __CKDL_NO_BBQ__
  37 #include "chuck_bbq.h"
  38 #endif
  39 using namespace std;
  40
  41
  42
  43 //-----------------------------------------------------------------------------
  44 // name: load()
  45 // desc: load dynamic link library
  46 //-----------------------------------------------------------------------------
  47 t_CKBOOL Chuck_DLL::load( const char * filename, const char * func, t_CKBOOL lazy )
  48 {
  49     // open
  50     m_handle = dlopen( filename, lazy ? RTLD_LAZY : RTLD_NOW );
  51
  52     // still not there
  53     if( !m_handle )
  54     {
  55         m_last_error = dlerror();
  56         return FALSE;
  57     }
  58
  59     // save the filename
  60     m_filename = filename;
  61     m_done_query = FALSE;
  62     m_func = func;
  63
  64     // if not lazy, do it
  65     if( !lazy && !this->query() )
  66         return FALSE;
  67
  68     return TRUE;
  69 }
  70
  71
  72
  73
  74 //-----------------------------------------------------------------------------
  75 // name: load()
  76 // desc: load dynamic link library
  77 //-----------------------------------------------------------------------------
  78 t_CKBOOL Chuck_DLL::load( f_ck_query query_func, t_CKBOOL lazy )
  79 {
  80     m_query_func = query_func;
  81     m_done_query = FALSE;
  82     m_func = "ck_query";
  83
  84     // if not lazy, do it
  85     if( !lazy && !this->query() )
  86         return FALSE;
  87
  88     return TRUE;
  89 }
  90
  91
  92
  93
  94 //-----------------------------------------------------------------------------
  95 // name: good()
  96 // desc: ...
  97 //-----------------------------------------------------------------------------
  98 t_CKBOOL Chuck_DLL::good() const
  99 {
 100     return ( m_handle != NULL || m_query_func != NULL );
 101 }
 102
 103
 104
 105
 106 //-----------------------------------------------------------------------------
 107 // name: query()
 108 // desc: ...
 109 //-----------------------------------------------------------------------------
 110 const Chuck_DL_Query * Chuck_DLL::query( )
 111 {
 112     if( !m_handle && !m_query_func )
 113     {
 114         m_last_error = "dynamic link library not loaded for query...";
 115         return NULL;
 116     }
 117
 118     // return if there already
 119     if( m_done_query )
 120         return &m_query;
 121
 122     // get the address of the query function from the DLL
 123     if( !m_query_func )
 124         m_query_func = (f_ck_query)this->get_addr( m_func.c_str() );
 125     if( !m_query_func )
 126         m_query_func = (f_ck_query)this->get_addr( (string("_")+m_func).c_str() );
 127     if( !m_query_func )
 128     {
 129         m_last_error = string("no query function found in dll '")
 130                        + m_filename + string("'");
 131         return NULL;
 132     }
 133
 134     // get the address of the attach function from the DLL
 135     if( !m_attach_func )
 136         m_attach_func = (f_ck_attach)this->get_addr( "ck_attach" );
 137     if( !m_attach_func )
 138         m_attach_func = (f_ck_attach)this->get_addr( "_ck_attach" );
 139
 140     // get the address of the detach function from the DLL
 141     if( !m_detach_func )
 142         m_detach_func = (f_ck_detach)this->get_addr( "ck_detach" );
 143     if( !m_detach_func )
 144         m_detach_func = (f_ck_detach)this->get_addr( "_ck_detach" );
 145
 146     // do the query
 147     m_query.clear();
 148     if( !m_query_func( &m_query ) )
 149     {
 150         m_last_error = string("unsuccessful query in dll '") + m_filename
 151                        + string("'");
 152         return NULL;
 153     }
 154
 155     // load the proto table
 156     Chuck_DL_Proto * proto;
 157     m_name2proto.clear();
 158     for( t_CKUINT i = 0; i < m_query.dll_exports.size(); i++ )
 159     {
 160         proto = &m_query.dll_exports[i];
 161         if( m_name2proto[proto->name] )
 162         {
 163             m_last_error = string("duplicate export name '") + proto->name
 164                            + string("'");
 165             return NULL;
 166         }
 167
 168         // get the addr
 169         if( !proto->addr )
 170             proto->addr = (f_ck_func)this->get_addr( (char *)proto->name.c_str() );
 171         if( !proto->addr )
 172         {
 173             m_last_error = string("no addr associated with export '") +
 174                            proto->name + string("'");
 175             return NULL;
 176         }
 177
 178         // put in the lookup table
 179         m_name2proto[proto->name] = proto;
 180     }
 181
 182     // load the proto table
 183     Chuck_UGen_Info * info;
 184     m_name2ugen.clear();
 185     for( t_CKUINT j = 0; j < m_query.ugen_exports.size(); j++ )
 186     {
 187         info = &m_query.ugen_exports[j];
 188         if( m_name2ugen[info->name] )
 189         {
 190             m_last_error = string("duplicate export ugen name '") + info->name
 191                            + string("'");
 192             return NULL;
 193         }
 194
 195         // put in the lookup table
 196         m_name2ugen[info->name] = info;
 197     }
 198
 199     m_done_query = TRUE;
 200
 201     // call attach
 202     if( m_attach_func ) m_attach_func( 0, NULL );
 203
 204     return &m_query;
 205 }
 206
 207
 208
 209
 210 //-----------------------------------------------------------------------------
 211 // name: unload()
 212 // desc: ...
 213 //-----------------------------------------------------------------------------
 214 t_CKBOOL Chuck_DLL::unload()
 215 {
 216     if( !m_handle && !m_query_func )
 217     {
 218         m_last_error = "cannot unload dynamic library - nothing open...";
 219         return FALSE;
 220     }
 221
 222     if( m_detach_func ) m_detach_func( 0, NULL );
 223
 224     if( m_handle )
 225     {
 226         dlclose( m_handle );
 227         m_handle = NULL;
 228     }
 229     else
 230         m_query_func = NULL;
 231
 232     return TRUE;
 233 }
 234
 235
 236
 237
 238 //-----------------------------------------------------------------------------
 239 // name: get_addr()
 240 // desc: ...
 241 //-----------------------------------------------------------------------------
 242 void * Chuck_DLL::get_addr( const char * symbol )
 243 {
 244     if( !m_handle )
 245     {
 246         m_last_error = "cannot find addr from dynamic library - nothing open...";
 247         return FALSE;
 248     }
 249
 250     return dlsym( m_handle, symbol );
 251 }
 252
 253
 254
 255
 256 //-----------------------------------------------------------------------------
 257 // name: proto()
 258 // desc: ...
 259 //-----------------------------------------------------------------------------
 260 const Chuck_DL_Proto * Chuck_DLL::proto( const char * symbol )
 261 {
 262     if( !m_handle && !m_query_func )
 263     {
 264         m_last_error = "cannot find proto from dynamic library - nothing open...";
 265         return NULL;
 266     }
 267
 268     // get the proto from the hash
 269     Chuck_DL_Proto * proto = m_name2proto[symbol];
 270     if( !proto )
 271     {
 272         m_last_error = string("no prototype function '") + string(symbol)
 273                        + string("' found");
 274         return NULL;
 275     }
 276
 277     return proto;
 278 }
 279
 280
 281
 282
 283 //-----------------------------------------------------------------------------
 284 // name: last_error()
 285 // desc: ...
 286 //-----------------------------------------------------------------------------
 287 const char * Chuck_DLL::last_error() const
 288 {
 289     return m_last_error.c_str();
 290 }
 291
 292
 293
 294
 295 //-----------------------------------------------------------------------------
 296 // name: Chuck_DL_Query
 297 // desc: ...
 298 //-----------------------------------------------------------------------------
 299 Chuck_DL_Query::Chuck_DL_Query( )
 300 { add_export = __ck_addexport; add_param = __ck_addparam;
 301   ugen_add = __ck_ugen_add; ugen_func = __ck_ugen_func;
 302   ugen_ctrl = __ck_ugen_ctrl; set_name = __ck_setname;
 303   ugen_extends = __ck_ugen_extends;  // XXX - pld
 304   dll_name = "[noname]"; reserved = NULL;
 305
 306 #ifndef __CKDL_NO_BBQ__
 307   srate = Digitalio::sampling_rate() ; bufsize = Digitalio::buffer_size();
 308 #else
 309   srate = 0; bufsize = 0;
 310 #endif
 311
 312   ugen_exports.resize( 128 );
 313   linepos = 0;
 314 }
 315
 316
 317
 318
 319 // add proto
 320 extern "C" void CK_DLL_CALL __ck_addexport( Chuck_DL_Query * query,
 321            const char * type, const char * name, f_ck_func addr,
 322            t_CKBOOL is_func )
 323 { query->dll_exports.push_back( Chuck_DL_Proto( type, name, (void *)addr, is_func ) ); }
 324
 325 // add param
 326 extern "C" void CK_DLL_CALL __ck_addparam( Chuck_DL_Query * query,
 327            const char * type, const char * name )
 328 { if( query->dll_exports.size() )
 329     query->dll_exports[query->dll_exports.size()-1].add_param( type, name ); }
 330
 331 // add ugen
 332 extern "C" void CK_DLL_CALL __ck_ugen_add( Chuck_DL_Query * query,
 333            const char * name, void * reserved )
 334 { query->ugen_exports.push_back( Chuck_UGen_Info( name ) );
 335   query->reserved = reserved; }
 336
 337 // set funcs
 338 extern "C" void CK_DLL_CALL __ck_ugen_func( Chuck_DL_Query * query,
 339            f_ctor c, f_dtor d, f_tick t, f_pmsg p )
 340 { if( query->ugen_exports.size() )
 341     query->ugen_exports[query->ugen_exports.size()-1].set( c, d, t, p ); }
 342
 343 // add ctrl
 344 extern "C" void CK_DLL_CALL __ck_ugen_ctrl( Chuck_DL_Query * query,
 345            f_ctrl c, f_cget g, const char * t, const char * n )
 346 { if( query->ugen_exports.size() )
 347     query->ugen_exports[query->ugen_exports.size()-1].add( c, g, t, n ); }
 348
 349 //XXX - pld  inherit functions from 'parent' ugen
 350 extern "C" void CK_DLL_CALL __ck_ugen_extends( Chuck_DL_Query * query,
 351            const char * parent )
 352 {
 353     if( query->ugen_exports.size() > 1 )
 354         for( int i= 0 ; i < query->ugen_exports.size() - 1 ; i++ )
 355             if( strcmp ( parent, query->ugen_exports[i].name.c_str() ) == 0 )
 356             {
 357                 query->ugen_exports[query->ugen_exports.size()-1].inherit(
 358                     &(query->ugen_exports[i]) );
 359                 return;
 360             }
 361 }
 362
 363
 364 // set name
 365 extern "C" void CK_DLL_CALL __ck_setname( Chuck_DL_Query * query,
 366            const char * name )
 367 { query->dll_name = name; }
 368
 369 // windows
 370 #if defined(__WINDOWS_DS__)
 371 extern "C"
 372 {
 373 #include <windows.h>
 374
 375 void *dlopen( const char *path, int mode)
 376 {
 377     return (void *)LoadLibrary(path);
 378 }
 379
 380 int dlclose( void *handle)
 381 {
 382     FreeLibrary((HMODULE)handle);
 383     return 1;
 384 }
 385
 386 void *dlsym( void * handle, const char *symbol )
 387 {
 388     return (void *)GetProcAddress((HMODULE)handle, symbol);
 389 }
 390
 391 const char * dlerror( void )
 392 {
 393     int error = GetLastError();
 394     if( error == 0 ) return NULL;
 395     sprintf( dlerror_buffer, "%i", error );
 396     return dlerror_buffer;
 397 }
 398 }
 399 #endif
 400
 401 // mac os x
 402 #if defined(__MACOSX_CORE__) && MAC_OS_X_VERSION_MAX_ALLOWED <= 1030
 403
 404 extern "C"
 405 {
 406
 407 #include <stdio.h>
 408 #include <stdlib.h>
 409 #include <string.h>
 410 #include <errno.h>
 411 #include <sys/types.h>
 412 #include <sys/stat.h>
 413 #include <limits.h>
 414 #include "mach-o/dyld.h"
 415
 416 /*
 417  * debugging macros
 418  */
 419 #if DEBUG > 0
 420 #define DEBUG_PRINT(format) fprintf(stderr,(format));fflush(stderr)
 421 #define DEBUG_PRINT1(format,arg1) fprintf(stderr,(format),(arg1));\
 422   fflush(stderr)
 423 #define DEBUG_PRINT2(format,arg1,arg2) fprintf(stderr,(format),\
 424   (arg1),(arg2));fflush(stderr)
 425 #define DEBUG_PRINT3(format,arg1,arg2,arg3) fprintf(stderr,(format),\
 426   (arg1),(arg2),(arg3));fflush(stderr)
 427 #else
 428 #define DEBUG_PRINT(format) /**/
 429 #define DEBUG_PRINT1(format,arg1) /**/
 430 #define DEBUG_PRINT2(format,arg1,arg2) /**/
 431 #define DEBUG_PRINT3(format,arg1,arg2,arg3) /**/
 432 #undef DEBUG
 433 #endif
 434
 435 /*
 436  * The structure of a dlopen() handle.
 437  */
 438 struct dlopen_handle {
 439     dev_t dev;          /* the path's device and inode number from stat(2) */
 440     ino_t ino;
 441     int dlopen_mode;    /* current dlopen mode for this handle */
 442     int dlopen_count;   /* number of times dlopen() called on this handle */
 443     NSModule module;    /* the NSModule returned by NSLinkModule() */
 444     struct dlopen_handle *prev;
 445     struct dlopen_handle *next;
 446 };
 447 static struct dlopen_handle *dlopen_handles = NULL;
 448 static const struct dlopen_handle main_program_handle = {NULL};
 449 static char *dlerror_pointer = NULL;
 450
 451 /*
 452  * NSMakePrivateModulePublic() is not part of the public dyld API so we define
 453  * it here.  The internal dyld function pointer for
 454  * __dyld_NSMakePrivateModulePublic is returned so thats all that maters to get
 455  * the functionality need to implement the dlopen() interfaces.
 456  */
 457 static
 458 int
 459 NSMakePrivateModulePublic(
 460 NSModule module)
 461 {
 462     static int (*p)(NSModule module) = NULL;
 463
 464         if(p == NULL)
 465             _dyld_func_lookup("__dyld_NSMakePrivateModulePublic",
 466                               (unsigned long *)&p);
 467         if(p == NULL){
 468 #ifdef DEBUG
 469             printf("_dyld_func_lookup of __dyld_NSMakePrivateModulePublic "
 470                    "failed\n");
 471 #endif
 472             return(FALSE);
 473         }
 474         return(p(module));
 475 }
 476
 477 /*
 478  * helper routine: search for a named module in various locations
 479  */
 480 static
 481 int
 482 _dl_search_paths(
 483 const char *filename,
 484 char *pathbuf,
 485 struct stat *stat_buf)
 486 {
 487     const char *pathspec;
 488     const char *element;
 489     const char *p;
 490     char *q;
 491     char *pathbuf_end;
 492     const char *envvars[] = {
 493         "$DYLD_LIBRARY_PATH",
 494         "$LD_LIBRARY_PATH",
 495         "/usr/lib:/lib",
 496         NULL };
 497     int envvar_index;
 498
 499         pathbuf_end = pathbuf + PATH_MAX - 8;
 500
 501         for(envvar_index = 0; envvars[envvar_index]; envvar_index++){
 502             if(envvars[envvar_index][0] == '$'){
 503                 pathspec = getenv(envvars[envvar_index]+1);
 504             }
 505             else {
 506                 pathspec = envvars[envvar_index];
 507             }
 508
 509             if(pathspec != NULL){
 510                 element = pathspec;
 511                 while(*element){
 512                     /* extract path list element */
 513                     p = element;
 514                     q = pathbuf;
 515                     while(*p && *p != ':' && q < pathbuf_end) *q++ = *p++;
 516                     if(q == pathbuf){  /* empty element */
 517                         if(*p){
 518                             element = p+1;
 519                             continue;
 520                         }
 521                         break;
 522                     }
 523                     if (*p){
 524                         element = p+1;
 525                     }
 526                     else{
 527                         element = p;  /* this terminates the loop */
 528                     }
 529
 530                     /* add slash if neccessary */
 531                     if(*(q-1) != '/' && q < pathbuf_end){
 532                         *q++ = '/';
 533                     }
 534
 535                     /* append module name */
 536                     p = filename;
 537                     while(*p && q < pathbuf_end) *q++ = *p++;
 538                     *q++ = 0;
 539
 540                     if(q >= pathbuf_end){
 541                         /* maybe add an error message here */
 542                         break;
 543                     }
 544
 545                     if(stat(pathbuf, stat_buf) == 0){
 546                         return 0;
 547                     }
 548                 }
 549             }
 550         }
 551
 552         /* we have searched everywhere, now we give up */
 553         return -1;
 554 }
 555
 556 /*
 557  * dlopen() the MacOS X version of the FreeBSD dlopen() interface.
 558  */
 559 void *
 560 dlopen(
 561 const char *path,
 562 int mode)
 563 {
 564     const char *module_path;
 565     void *retval;
 566     struct stat stat_buf;
 567     NSObjectFileImage objectFileImage;
 568     NSObjectFileImageReturnCode ofile_result_code;
 569     NSModule module;
 570     struct dlopen_handle *p;
 571     unsigned long options;
 572     NSSymbol NSSymbol;
 573     void (*init)(void);
 574     char pathbuf[PATH_MAX];
 575
 576         DEBUG_PRINT2("libdl: dlopen(%s,0x%x) -> ", path, (unsigned int)mode);
 577
 578         dlerror_pointer = NULL;
 579         /*
 580          * A NULL path is to indicate the caller wants a handle for the
 581          * main program.
 582          */
 583         if(path == NULL){
 584             retval = (void *)&main_program_handle;
 585             DEBUG_PRINT1("main / %p\n", retval);
 586             return(retval);
 587         }
 588
 589         /* see if the path exists and if so get the device and inode number */
 590         if(stat(path, &stat_buf) == -1){
 591             dlerror_pointer = strerror(errno);
 592
 593             if(path[0] == '/'){
 594                 DEBUG_PRINT1("ERROR (stat): %s\n", dlerror_pointer);
 595                 return(NULL);
 596             }
 597
 598             /* search for the module in various places */
 599             if(_dl_search_paths(path, pathbuf, &stat_buf)){
 600                 /* dlerror_pointer is unmodified */
 601                 DEBUG_PRINT1("ERROR (stat): %s\n", dlerror_pointer);
 602                 return(NULL);
 603             }
 604             DEBUG_PRINT1("found %s -> ", pathbuf);
 605             module_path = pathbuf;
 606             dlerror_pointer = NULL;
 607         }
 608         else{
 609             module_path = path;
 610         }
 611
 612         /*
 613          * If we don't want an unshared handle see if we already have a handle
 614          * for this path.
 615          */
 616         if((mode & RTLD_UNSHARED) != RTLD_UNSHARED){
 617             p = dlopen_handles;
 618             while(p != NULL){
 619                 if(p->dev == stat_buf.st_dev && p->ino == stat_buf.st_ino){
 620                     /* skip unshared handles */
 621                     if((p->dlopen_mode & RTLD_UNSHARED) == RTLD_UNSHARED)
 622                         continue;
 623                     /*
 624                      * We have already created a handle for this path.  The
 625                      * caller might be trying to promote an RTLD_LOCAL handle
 626                      * to a RTLD_GLOBAL.  Or just looking it up with
 627                      * RTLD_NOLOAD.
 628                      */
 629                     if((p->dlopen_mode & RTLD_LOCAL) == RTLD_LOCAL &&
 630                        (mode & RTLD_GLOBAL) == RTLD_GLOBAL){
 631                         /* promote the handle */
 632                         if(NSMakePrivateModulePublic(p->module) == TRUE){
 633                             p->dlopen_mode &= ~RTLD_LOCAL;
 634                             p->dlopen_mode |= RTLD_GLOBAL;
 635                             p->dlopen_count++;
 636                             DEBUG_PRINT1("%p\n", p);
 637                             return(p);
 638                         }
 639                         else{
 640                             dlerror_pointer = "can't promote handle from "
 641                                               "RTLD_LOCAL to RTLD_GLOBAL";
 642                             DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 643                             return(NULL);
 644                         }
 645                     }
 646                     p->dlopen_count++;
 647                     DEBUG_PRINT1("%p\n", p);
 648                     return(p);
 649                 }
 650                 p = p->next;
 651             }
 652         }
 653
 654         /*
 655          * We do not have a handle for this path if we were just trying to
 656          * look it up return NULL to indicate we don't have it.
 657          */
 658         if((mode & RTLD_NOLOAD) == RTLD_NOLOAD){
 659             dlerror_pointer = "no existing handle for path RTLD_NOLOAD test";
 660             DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 661             return(NULL);
 662         }
 663
 664         /* try to create an object file image from this path */
 665         ofile_result_code = NSCreateObjectFileImageFromFile(module_path,
 666                                                             &objectFileImage);
 667         if(ofile_result_code != NSObjectFileImageSuccess){
 668             switch(ofile_result_code){
 669             case NSObjectFileImageFailure:
 670                 dlerror_pointer = "object file setup failure";
 671                 DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 672                 return(NULL);
 673             case NSObjectFileImageInappropriateFile:
 674                 dlerror_pointer = "not a Mach-O MH_BUNDLE file type";
 675                 DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 676                 return(NULL);
 677             case NSObjectFileImageArch:
 678                 dlerror_pointer = "no object for this architecture";
 679                 DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 680                 return(NULL);
 681             case NSObjectFileImageFormat:
 682                 dlerror_pointer = "bad object file format";
 683                 DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 684                 return(NULL);
 685             case NSObjectFileImageAccess:
 686                 dlerror_pointer = "can't read object file";
 687                 DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 688                 return(NULL);
 689             default:
 690                 dlerror_pointer = "unknown error from "
 691                                   "NSCreateObjectFileImageFromFile()";
 692                 DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 693                 return(NULL);
 694             }
 695         }
 696
 697         /* try to link in this object file image */
 698         options = NSLINKMODULE_OPTION_PRIVATE;
 699         if((mode & RTLD_NOW) == RTLD_NOW)
 700             options |= NSLINKMODULE_OPTION_BINDNOW;
 701         module = NSLinkModule(objectFileImage, module_path, options);
 702         NSDestroyObjectFileImage(objectFileImage) ;
 703         if(module == NULL){
 704             dlerror_pointer = "NSLinkModule() failed for dlopen()";
 705             DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 706             return(NULL);
 707         }
 708
 709         /*
 710          * If the handle is to be global promote the handle.  It is done this
 711          * way to avoid multiply defined symbols.
 712          */
 713         if((mode & RTLD_GLOBAL) == RTLD_GLOBAL){
 714             if(NSMakePrivateModulePublic(module) == FALSE){
 715                 dlerror_pointer = "can't promote handle from RTLD_LOCAL to "
 716                                   "RTLD_GLOBAL";
 717                 DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 718                 return(NULL);
 719             }
 720         }
 721
 722         p = (dlopen_handle *)malloc(sizeof(struct dlopen_handle));
 723         if(p == NULL){
 724             dlerror_pointer = "can't allocate memory for the dlopen handle";
 725             DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 726             return(NULL);
 727         }
 728
 729         /* fill in the handle */
 730         p->dev = stat_buf.st_dev;
 731         p->ino = stat_buf.st_ino;
 732         if(mode & RTLD_GLOBAL)
 733             p->dlopen_mode = RTLD_GLOBAL;
 734         else
 735             p->dlopen_mode = RTLD_LOCAL;
 736         p->dlopen_mode |= (mode & RTLD_UNSHARED) |
 737                           (mode & RTLD_NODELETE) |
 738                           (mode & RTLD_LAZY_UNDEF);
 739         p->dlopen_count = 1;
 740         p->module = module;
 741         p->prev = NULL;
 742         p->next = dlopen_handles;
 743         if(dlopen_handles != NULL)
 744             dlopen_handles->prev = p;
 745         dlopen_handles = p;
 746
 747         /* call the init function if one exists */
 748         NSSymbol = NSLookupSymbolInModule(p->module, "__init");
 749         if(NSSymbol != NULL){
 750             init = ( void(*)() )NSAddressOfSymbol(NSSymbol);
 751             init();
 752         }
 753
 754         DEBUG_PRINT1("%p\n", p);
 755         return(p);
 756 }
 757
 758 /*
 759  * dlsym() the MacOS X version of the FreeBSD dlopen() interface.
 760  */
 761 void *
 762 dlsym(
 763 void * handle,
 764 const char *symbol)
 765 {
 766     struct dlopen_handle *dlopen_handle, *p;
 767     NSSymbol NSSymbol;
 768     void *address;
 769
 770         DEBUG_PRINT2("libdl: dlsym(%p,%s) -> ", handle, symbol);
 771
 772         dlopen_handle = (struct dlopen_handle *)handle;
 773
 774         /*
 775          * If this is the handle for the main program do a global lookup.
 776          */
 777         if(dlopen_handle == (struct dlopen_handle *)&main_program_handle){
 778             if(NSIsSymbolNameDefined(symbol) == TRUE){
 779                 NSSymbol = NSLookupAndBindSymbol(symbol);
 780                 address = NSAddressOfSymbol(NSSymbol);
 781                 dlerror_pointer = NULL;
 782                 DEBUG_PRINT1("%p\n", address);
 783                 return(address);
 784             }
 785             else{
 786                 dlerror_pointer = "symbol not found";
 787                 DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 788                 return(NULL);
 789             }
 790         }
 791
 792         /*
 793          * Find this handle and do a lookup in just this module.
 794          */
 795         p = dlopen_handles;
 796         while(p != NULL){
 797             if(dlopen_handle == p){
 798                 NSSymbol = NSLookupSymbolInModule(p->module, symbol);
 799                 if(NSSymbol != NULL){
 800                     address = NSAddressOfSymbol(NSSymbol);
 801                     dlerror_pointer = NULL;
 802                     DEBUG_PRINT1("%p\n", address);
 803                     return(address);
 804                 }
 805                 else{
 806                     dlerror_pointer = "symbol not found";
 807                     DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 808                     return(NULL);
 809                 }
 810             }
 811             p = p->next;
 812         }
 813
 814         dlerror_pointer = "bad handle passed to dlsym()";
 815         DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 816         return(NULL);
 817 }
 818
 819 /*
 820  * dlerror() the MacOS X version of the FreeBSD dlopen() interface.
 821  */
 822 const char *
 823 dlerror(
 824 void)
 825 {
 826     const char *p;
 827
 828         p = (const char *)dlerror_pointer;
 829         dlerror_pointer = NULL;
 830         return(p);
 831 }
 832
 833 /*
 834  * dlclose() the MacOS X version of the FreeBSD dlopen() interface.
 835  */
 836 int
 837 dlclose(
 838 void * handle)
 839 {
 840     struct dlopen_handle *p, *q;
 841     unsigned long options;
 842     NSSymbol NSSymbol;
 843     void (*fini)(void);
 844
 845         DEBUG_PRINT1("libdl: dlclose(%p) -> ", handle);
 846
 847         dlerror_pointer = NULL;
 848         q = (struct dlopen_handle *)handle;
 849         p = dlopen_handles;
 850         while(p != NULL){
 851             if(p == q){
 852                 /* if the dlopen() count is not zero we are done */
 853                 p->dlopen_count--;
 854                 if(p->dlopen_count != 0){
 855                     DEBUG_PRINT("OK");
 856                     return(0);
 857                 }
 858
 859                 /* call the fini function if one exists */
 860                 NSSymbol = NSLookupSymbolInModule(p->module, "__fini");
 861                 if(NSSymbol != NULL){
 862                     fini = ( void(*)() )NSAddressOfSymbol(NSSymbol);
 863                     fini();
 864                 }
 865
 866                 /* unlink the module for this handle */
 867                 options = 0;
 868                 if(p->dlopen_mode & RTLD_NODELETE)
 869                     options |= NSUNLINKMODULE_OPTION_KEEP_MEMORY_MAPPED;
 870                 if(p->dlopen_mode & RTLD_LAZY_UNDEF)
 871                     options |= NSUNLINKMODULE_OPTION_RESET_LAZY_REFERENCES;
 872                 if(NSUnLinkModule(p->module, options) == FALSE){
 873                     dlerror_pointer = "NSUnLinkModule() failed for dlclose()";
 874                     DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 875                     return(-1);
 876                 }
 877                 if(p->prev != NULL)
 878                     p->prev->next = p->next;
 879                 if(p->next != NULL)
 880                     p->next->prev = p->prev;
 881                 if(dlopen_handles == p)
 882                     dlopen_handles = p->next;
 883                 free(p);
 884                 DEBUG_PRINT("OK");
 885                 return(0);
 886             }
 887             p = p->next;
 888         }
 889         dlerror_pointer = "invalid handle passed to dlclose()";
 890         DEBUG_PRINT1("ERROR: %s\n", dlerror_pointer);
 891         return(-1);
 892 }
 893
 894 }
 895
 896 #else
 897
 898 // do nothing, it's all in dlfcn
 899
 900 #endif