boehm-gc/win32_threads.c

   1 #if defined(GC_WIN32_THREADS)
   2
   3 #include "private/gc_priv.h"
   4
   5 #if 0
   6 #define STRICT
   7 #include <windows.h>
   8 #endif
   9
  10 #define MAX_THREADS 64
  11
  12 struct thread_entry {
  13   LONG in_use;
  14   DWORD id;
  15   HANDLE handle;
  16   void *stack;          /* The cold end of the stack.   */
  17                         /* 0 ==> entry not valid.       */
  18                         /* !in_use ==> stack == 0       */
  19   CONTEXT context;
  20   GC_bool suspended;
  21 };
  22
  23 volatile GC_bool GC_please_stop = FALSE;
  24
  25 volatile struct thread_entry thread_table[MAX_THREADS];
  26
  27 void GC_push_thread_structures GC_PROTO((void))
  28 {
  29     /* Unlike the other threads implementations, the thread table here  */
  30     /* contains no pointers to the collectable heap.  Thus we have      */
  31     /* no private structures we need to preserve.                       */
  32 }
  33
  34 void GC_stop_world()
  35 {
  36   DWORD thread_id = GetCurrentThreadId();
  37   int i;
  38
  39   GC_please_stop = TRUE;
  40   for (i = 0; i < MAX_THREADS; i++)
  41     if (thread_table[i].stack != 0
  42         && thread_table[i].id != thread_id) {
  43 #     ifdef MSWINCE
  44         /* SuspendThread will fail if thread is running kernel code */
  45         while (SuspendThread(thread_table[i].handle) == (DWORD)-1)
  46           Sleep(10);
  47 #     else
  48         /* Apparently the Windows 95 GetOpenFileName call creates       */
  49         /* a thread that does not properly get cleaned up, and          */
  50         /* SuspendThread on its descriptor may provoke a crash.         */
  51         /* This reduces the probability of that event, though it still  */
  52         /* appears there's a race here.                                 */
  53         DWORD exitCode;
  54         if (GetExitCodeThread(thread_table[i].handle,&exitCode) &&
  55             exitCode != STILL_ACTIVE) {
  56             thread_table[i].stack = 0;
  57             thread_table[i].in_use = FALSE;
  58             CloseHandle(thread_table[i].handle);
  59             BZERO((void *)(&thread_table[i].context), sizeof(CONTEXT));
  60             continue;
  61         }
  62         if (SuspendThread(thread_table[i].handle) == (DWORD)-1)
  63           ABORT("SuspendThread failed");
  64 #     endif
  65       thread_table[i].suspended = TRUE;
  66     }
  67 }
  68
  69 void GC_start_world()
  70 {
  71   DWORD thread_id = GetCurrentThreadId();
  72   int i;
  73   for (i = 0; i < MAX_THREADS; i++)
  74     if (thread_table[i].stack != 0 && thread_table[i].suspended
  75         && thread_table[i].id != thread_id) {
  76       if (ResumeThread(thread_table[i].handle) == (DWORD)-1)
  77         ABORT("ResumeThread failed");
  78       thread_table[i].suspended = FALSE;
  79     }
  80   GC_please_stop = FALSE;
  81 }
  82
  83 # ifdef _MSC_VER
  84 #   pragma warning(disable:4715)
  85 # endif
  86 ptr_t GC_current_stackbottom()
  87 {
  88   DWORD thread_id = GetCurrentThreadId();
  89   int i;
  90   for (i = 0; i < MAX_THREADS; i++)
  91     if (thread_table[i].stack && thread_table[i].id == thread_id)
  92       return thread_table[i].stack;
  93   ABORT("no thread table entry for current thread");
  94 }
  95 # ifdef _MSC_VER
  96 #   pragma warning(default:4715)
  97 # endif
  98
  99 # ifdef MSWINCE
 100     /* The VirtualQuery calls below won't work properly on WinCE, but   */
 101     /* since each stack is restricted to an aligned 64K region of       */
 102     /* virtual memory we can just take the next lowest multiple of 64K. */
 103 #   define GC_get_lo_stack_addr(s) \
 104         ((ptr_t)(((DWORD)(s) - 1) & 0xFFFF0000))
 105 # else
 106     static ptr_t GC_get_lo_stack_addr(ptr_t s)
 107     {
 108         ptr_t bottom;
 109         MEMORY_BASIC_INFORMATION info;
 110         VirtualQuery(s, &info, sizeof(info));
 111         do {
 112             bottom = info.BaseAddress;
 113             VirtualQuery(bottom - 1, &info, sizeof(info));
 114         } while ((info.Protect & PAGE_READWRITE)
 115                  && !(info.Protect & PAGE_GUARD));
 116         return(bottom);
 117     }
 118 # endif
 119
 120 void GC_push_all_stacks()
 121 {
 122   DWORD thread_id = GetCurrentThreadId();
 123   int i;
 124   for (i = 0; i < MAX_THREADS; i++)
 125     if (thread_table[i].stack) {
 126       ptr_t bottom = GC_get_lo_stack_addr(thread_table[i].stack);
 127       if (thread_table[i].id == thread_id)
 128         GC_push_all_stack((ptr_t)&i, thread_table[i].stack);
 129       else {
 130         thread_table[i].context.ContextFlags
 131                         = (CONTEXT_INTEGER|CONTEXT_CONTROL);
 132         if (!GetThreadContext(thread_table[i].handle,
 133                                 /* cast away volatile qualifier */
 134                                 (LPCONTEXT)&thread_table[i].context))
 135           ABORT("GetThreadContext failed");
 136 #       ifdef I386
 137           if (thread_table[i].context.Esp >= (DWORD)thread_table[i].stack
 138               || thread_table[i].context.Esp < (DWORD)bottom)
 139               ABORT("Thread stack pointer out of range");
 140           GC_push_one ((word) thread_table[i].context.Edi);
 141           GC_push_one ((word) thread_table[i].context.Esi);
 142           GC_push_one ((word) thread_table[i].context.Ebp);
 143           GC_push_one ((word) thread_table[i].context.Ebx);
 144           GC_push_one ((word) thread_table[i].context.Edx);
 145           GC_push_one ((word) thread_table[i].context.Ecx);
 146           GC_push_one ((word) thread_table[i].context.Eax);
 147           GC_push_all_stack((char *) thread_table[i].context.Esp,
 148                             thread_table[i].stack);
 149 #       else
 150 #       ifdef ARM32
 151           if (thread_table[i].context.Sp >= (DWORD)thread_table[i].stack
 152               || thread_table[i].context.Sp < (DWORD)bottom)
 153               ABORT("Thread stack pointer out of range");
 154           GC_push_one ((word) thread_table[i].context.R0);
 155           GC_push_one ((word) thread_table[i].context.R1);
 156           GC_push_one ((word) thread_table[i].context.R2);
 157           GC_push_one ((word) thread_table[i].context.R3);
 158           GC_push_one ((word) thread_table[i].context.R4);
 159           GC_push_one ((word) thread_table[i].context.R5);
 160           GC_push_one ((word) thread_table[i].context.R6);
 161           GC_push_one ((word) thread_table[i].context.R7);
 162           GC_push_one ((word) thread_table[i].context.R8);
 163           GC_push_one ((word) thread_table[i].context.R9);
 164           GC_push_one ((word) thread_table[i].context.R10);
 165           GC_push_one ((word) thread_table[i].context.R11);
 166           GC_push_one ((word) thread_table[i].context.R12);
 167           GC_push_all_stack((char *) thread_table[i].context.Sp,
 168                             thread_table[i].stack);
 169 #       else
 170 #       ifdef SHx
 171           if (thread_table[i].context.R15 >= (DWORD)thread_table[i].stack
 172               || thread_table[i].context.R15 < (DWORD)bottom)
 173               ABORT("Thread stack pointer out of range");
 174           GC_push_one ((word) thread_table[i].context.R0);
 175           GC_push_one ((word) thread_table[i].context.R1);
 176           GC_push_one ((word) thread_table[i].context.R2);
 177           GC_push_one ((word) thread_table[i].context.R3);
 178           GC_push_one ((word) thread_table[i].context.R4);
 179           GC_push_one ((word) thread_table[i].context.R5);
 180           GC_push_one ((word) thread_table[i].context.R6);
 181           GC_push_one ((word) thread_table[i].context.R7);
 182           GC_push_one ((word) thread_table[i].context.R8);
 183           GC_push_one ((word) thread_table[i].context.R9);
 184           GC_push_one ((word) thread_table[i].context.R10);
 185           GC_push_one ((word) thread_table[i].context.R11);
 186           GC_push_one ((word) thread_table[i].context.R12);
 187           GC_push_one ((word) thread_table[i].context.R13);
 188           GC_push_one ((word) thread_table[i].context.R14);
 189           GC_push_all_stack((char *) thread_table[i].context.R15,
 190                             thread_table[i].stack);
 191 #       else
 192 #       ifdef MIPS
 193           if (thread_table[i].context.IntSp >= (DWORD)thread_table[i].stack
 194               || thread_table[i].context.IntSp < (DWORD)bottom)
 195               ABORT("Thread stack pointer out of range");
 196           GC_push_one ((word) thread_table[i].context.IntAt);
 197           GC_push_one ((word) thread_table[i].context.IntV0);
 198           GC_push_one ((word) thread_table[i].context.IntV1);
 199           GC_push_one ((word) thread_table[i].context.IntA0);
 200           GC_push_one ((word) thread_table[i].context.IntA1);
 201           GC_push_one ((word) thread_table[i].context.IntA2);
 202           GC_push_one ((word) thread_table[i].context.IntA3);
 203           GC_push_one ((word) thread_table[i].context.IntT0);
 204           GC_push_one ((word) thread_table[i].context.IntT1);
 205           GC_push_one ((word) thread_table[i].context.IntT2);
 206           GC_push_one ((word) thread_table[i].context.IntT3);
 207           GC_push_one ((word) thread_table[i].context.IntT4);
 208           GC_push_one ((word) thread_table[i].context.IntT5);
 209           GC_push_one ((word) thread_table[i].context.IntT6);
 210           GC_push_one ((word) thread_table[i].context.IntT7);
 211           GC_push_one ((word) thread_table[i].context.IntS0);
 212           GC_push_one ((word) thread_table[i].context.IntS1);
 213           GC_push_one ((word) thread_table[i].context.IntS2);
 214           GC_push_one ((word) thread_table[i].context.IntS3);
 215           GC_push_one ((word) thread_table[i].context.IntS4);
 216           GC_push_one ((word) thread_table[i].context.IntS5);
 217           GC_push_one ((word) thread_table[i].context.IntS6);
 218           GC_push_one ((word) thread_table[i].context.IntS7);
 219           GC_push_one ((word) thread_table[i].context.IntT8);
 220           GC_push_one ((word) thread_table[i].context.IntT9);
 221           GC_push_one ((word) thread_table[i].context.IntK0);
 222           GC_push_one ((word) thread_table[i].context.IntK1);
 223           GC_push_one ((word) thread_table[i].context.IntS8);
 224           GC_push_all_stack((char *) thread_table[i].context.IntSp,
 225                             thread_table[i].stack);
 226 #       else
 227 #       ifdef PPC
 228           if (thread_table[i].context.Gpr1 >= (DWORD)thread_table[i].stack
 229               || thread_table[i].context.Gpr1 < (DWORD)bottom)
 230               ABORT("Thread stack pointer out of range");
 231           GC_push_one ((word) thread_table[i].context.Gpr0);
 232           /* Gpr1 is stack pointer */
 233           /* Gpr2 is global pointer */
 234           GC_push_one ((word) thread_table[i].context.Gpr3);
 235           GC_push_one ((word) thread_table[i].context.Gpr4);
 236           GC_push_one ((word) thread_table[i].context.Gpr5);
 237           GC_push_one ((word) thread_table[i].context.Gpr6);
 238           GC_push_one ((word) thread_table[i].context.Gpr7);
 239           GC_push_one ((word) thread_table[i].context.Gpr8);
 240           GC_push_one ((word) thread_table[i].context.Gpr9);
 241           GC_push_one ((word) thread_table[i].context.Gpr10);
 242           GC_push_one ((word) thread_table[i].context.Gpr11);
 243           GC_push_one ((word) thread_table[i].context.Gpr12);
 244           /* Gpr13 is reserved for the kernel */
 245           GC_push_one ((word) thread_table[i].context.Gpr14);
 246           GC_push_one ((word) thread_table[i].context.Gpr15);
 247           GC_push_one ((word) thread_table[i].context.Gpr16);
 248           GC_push_one ((word) thread_table[i].context.Gpr17);
 249           GC_push_one ((word) thread_table[i].context.Gpr18);
 250           GC_push_one ((word) thread_table[i].context.Gpr19);
 251           GC_push_one ((word) thread_table[i].context.Gpr20);
 252           GC_push_one ((word) thread_table[i].context.Gpr21);
 253           GC_push_one ((word) thread_table[i].context.Gpr22);
 254           GC_push_one ((word) thread_table[i].context.Gpr23);
 255           GC_push_one ((word) thread_table[i].context.Gpr24);
 256           GC_push_one ((word) thread_table[i].context.Gpr25);
 257           GC_push_one ((word) thread_table[i].context.Gpr26);
 258           GC_push_one ((word) thread_table[i].context.Gpr27);
 259           GC_push_one ((word) thread_table[i].context.Gpr28);
 260           GC_push_one ((word) thread_table[i].context.Gpr29);
 261           GC_push_one ((word) thread_table[i].context.Gpr30);
 262           GC_push_one ((word) thread_table[i].context.Gpr31);
 263           GC_push_all_stack((char *) thread_table[i].context.Gpr1,
 264                             thread_table[i].stack);
 265 #       else
 266 #       ifdef ALPHA
 267           if (thread_table[i].context.IntSp >= (DWORD)thread_table[i].stack
 268               || thread_table[i].context.IntSp < (DWORD)bottom)
 269               ABORT("Thread stack pointer out of range");
 270           GC_push_one ((word) thread_table[i].context.IntV0);
 271           GC_push_one ((word) thread_table[i].context.IntT0);
 272           GC_push_one ((word) thread_table[i].context.IntT1);
 273           GC_push_one ((word) thread_table[i].context.IntT2);
 274           GC_push_one ((word) thread_table[i].context.IntT3);
 275           GC_push_one ((word) thread_table[i].context.IntT4);
 276           GC_push_one ((word) thread_table[i].context.IntT5);
 277           GC_push_one ((word) thread_table[i].context.IntT6);
 278           GC_push_one ((word) thread_table[i].context.IntT7);
 279           GC_push_one ((word) thread_table[i].context.IntS0);
 280           GC_push_one ((word) thread_table[i].context.IntS1);
 281           GC_push_one ((word) thread_table[i].context.IntS2);
 282           GC_push_one ((word) thread_table[i].context.IntS3);
 283           GC_push_one ((word) thread_table[i].context.IntS4);
 284           GC_push_one ((word) thread_table[i].context.IntS5);
 285           GC_push_one ((word) thread_table[i].context.IntFp);
 286           GC_push_one ((word) thread_table[i].context.IntA0);
 287           GC_push_one ((word) thread_table[i].context.IntA1);
 288           GC_push_one ((word) thread_table[i].context.IntA2);
 289           GC_push_one ((word) thread_table[i].context.IntA3);
 290           GC_push_one ((word) thread_table[i].context.IntA4);
 291           GC_push_one ((word) thread_table[i].context.IntA5);
 292           GC_push_one ((word) thread_table[i].context.IntT8);
 293           GC_push_one ((word) thread_table[i].context.IntT9);
 294           GC_push_one ((word) thread_table[i].context.IntT10);
 295           GC_push_one ((word) thread_table[i].context.IntT11);
 296           GC_push_one ((word) thread_table[i].context.IntT12);
 297           GC_push_one ((word) thread_table[i].context.IntAt);
 298           GC_push_all_stack((char *) thread_table[i].context.IntSp,
 299                             thread_table[i].stack);
 300 #       else
 301               --> architecture not supported
 302 #       endif /* !ALPHA */
 303 #       endif /* !PPC */
 304 #       endif /* !MIPS */
 305 #       endif /* !SHx */
 306 #       endif /* !ARM32 */
 307 #       endif /* !I386 */
 308       }
 309     }
 310 }
 311
 312 void GC_get_next_stack(char *start, char **lo, char **hi)
 313 {
 314     int i;
 315 #   define ADDR_LIMIT (char *)(-1L)
 316     char * current_min = ADDR_LIMIT;
 317
 318     for (i = 0; i < MAX_THREADS; i++) {
 319         char * s = (char *)thread_table[i].stack;
 320
 321         if (0 != s && s > start && s < current_min) {
 322             current_min = s;
 323         }
 324     }
 325     *hi = current_min;
 326     if (current_min == ADDR_LIMIT) {
 327         *lo = ADDR_LIMIT;
 328         return;
 329     }
 330     *lo = GC_get_lo_stack_addr(current_min);
 331     if (*lo < start) *lo = start;
 332 }
 333
 334 #if !defined(MSWINCE) && !(defined(__MINGW32__) && !defined(_DLL))
 335
 336 HANDLE WINAPI GC_CreateThread(
 337     LPSECURITY_ATTRIBUTES lpThreadAttributes,
 338     DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
 339     LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
 340 {
 341     return CreateThread(lpThreadAttributes, dwStackSize, lpStartAddress,
 342                         lpParameter, dwCreationFlags, lpThreadId);
 343 }
 344
 345 #else /* !defined(MSWINCE) && !(defined(__MINGW32__) && !defined(_DLL)) */
 346
 347 typedef struct {
 348     HANDLE child_ready_h, parent_ready_h;
 349     volatile struct thread_entry * entry;
 350     LPTHREAD_START_ROUTINE start;
 351     LPVOID param;
 352 } thread_args;
 353
 354 DWORD WINAPI thread_start(LPVOID arg);
 355
 356 HANDLE WINAPI GC_CreateThread(
 357     LPSECURITY_ATTRIBUTES lpThreadAttributes,
 358     DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
 359     LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
 360 {
 361     HANDLE thread_h = NULL;
 362     HANDLE child_ready_h, parent_ready_h;
 363
 364     int i;
 365     thread_args args;
 366
 367     /* allocate thread slot */
 368     LOCK();
 369     for (i = 0; i != MAX_THREADS && thread_table[i].in_use; i++)
 370         ;
 371     if (i != MAX_THREADS) {
 372         thread_table[i].in_use = TRUE;
 373     }
 374     UNLOCK();
 375
 376     if (i != MAX_THREADS) {
 377
 378         /* create unnamed unsignalled events */
 379         if (child_ready_h = CreateEvent(NULL, FALSE, FALSE, NULL)) {
 380             if (parent_ready_h = CreateEvent(NULL, FALSE, FALSE, NULL)) {
 381
 382                 /* set up thread arguments */
 383                 args.child_ready_h = child_ready_h;
 384                 args.parent_ready_h = parent_ready_h;
 385                 args.entry = &thread_table[i];
 386                 args.start = lpStartAddress;
 387                 args.param = lpParameter;
 388
 389                 thread_h = CreateThread(lpThreadAttributes,
 390                                         dwStackSize, thread_start,
 391                                         &args,
 392                                         dwCreationFlags & ~CREATE_SUSPENDED,
 393                                         lpThreadId);
 394
 395                 if (thread_h) {
 396
 397                     /* fill in ID and handle; tell child this is done */
 398                     thread_table[i].id = *lpThreadId;
 399                     thread_table[i].handle = thread_h;
 400                     SetEvent (parent_ready_h);
 401
 402                     /* wait for child to fill in stack and copy args */
 403                     WaitForSingleObject (child_ready_h, INFINITE);
 404
 405                     /* suspend the child if requested */
 406                     if (dwCreationFlags & CREATE_SUSPENDED)
 407                         SuspendThread (thread_h);
 408
 409                     /* let child call given function now (or when resumed) */
 410                     SetEvent (parent_ready_h);
 411
 412                 } else {
 413                     CloseHandle (parent_ready_h);
 414                 }
 415             }
 416         }
 417
 418         CloseHandle (child_ready_h);
 419
 420         if (thread_h == NULL)
 421             thread_table[i].in_use = FALSE;
 422
 423     } else { /* no thread slot found */
 424         SetLastError (ERROR_TOO_MANY_TCBS);
 425     }
 426
 427     return thread_h;
 428 }
 429
 430 static DWORD WINAPI thread_start(LPVOID arg)
 431 {
 432     DWORD ret = 0;
 433     thread_args args = *(thread_args *)arg;
 434
 435     /* wait for parent to fill in ID and handle */
 436     WaitForSingleObject (args.parent_ready_h, INFINITE);
 437     ResetEvent (args.parent_ready_h);
 438
 439     /* fill in stack; tell parent this is done */
 440     args.entry->stack = GC_get_stack_base();
 441     SetEvent (args.child_ready_h);
 442
 443     /* wait for parent to tell us to go (in case it needs to suspend us) */
 444     WaitForSingleObject (args.parent_ready_h, INFINITE);
 445     CloseHandle (args.parent_ready_h);
 446
 447     /* Clear the thread entry even if we exit with an exception.        */
 448     /* This is probably pointless, since an uncaught exception is       */
 449     /* supposed to result in the process being killed.                  */
 450     __try {
 451         ret = args.start (args.param);
 452     } __finally {
 453         LOCK();
 454         args.entry->stack = 0;
 455         args.entry->in_use = FALSE;
 456               /* cast away volatile qualifier */
 457         BZERO((void *) &args.entry->context, sizeof(CONTEXT));
 458         UNLOCK();
 459     }
 460
 461     return ret;
 462 }
 463 #endif /* !defined(MSWINCE) && !(defined(__MINGW32__) && !defined(_DLL)) */
 464
 465 #ifdef MSWINCE
 466
 467 typedef struct {
 468     HINSTANCE hInstance;
 469     HINSTANCE hPrevInstance;
 470     LPWSTR lpCmdLine;
 471     int nShowCmd;
 472 } main_thread_args;
 473
 474 DWORD WINAPI main_thread_start(LPVOID arg);
 475
 476 int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 477                    LPWSTR lpCmdLine, int nShowCmd)
 478 {
 479     DWORD exit_code = 1;
 480
 481     main_thread_args args = {
 482         hInstance, hPrevInstance, lpCmdLine, nShowCmd
 483     };
 484     HANDLE thread_h;
 485     DWORD thread_id;
 486
 487     /* initialize everything */
 488     InitializeCriticalSection(&GC_allocate_ml);
 489     GC_init();
 490
 491     /* start the main thread */
 492     thread_h = GC_CreateThread(
 493         NULL, 0, main_thread_start, &args, 0, &thread_id);
 494
 495     if (thread_h != NULL)
 496     {
 497         WaitForSingleObject (thread_h, INFINITE);
 498         GetExitCodeThread (thread_h, &exit_code);
 499         CloseHandle (thread_h);
 500     }
 501
 502     GC_deinit();
 503     DeleteCriticalSection(&GC_allocate_ml);
 504
 505     return (int) exit_code;
 506 }
 507
 508 DWORD WINAPI main_thread_start(LPVOID arg)
 509 {
 510     main_thread_args * args = (main_thread_args *) arg;
 511
 512     return (DWORD) GC_WinMain (args->hInstance, args->hPrevInstance,
 513                                args->lpCmdLine, args->nShowCmd);
 514 }
 515
 516 # else /* !MSWINCE */
 517
 518 LONG WINAPI GC_write_fault_handler(struct _EXCEPTION_POINTERS *exc_info);
 519
 520 /*
 521  * This isn't generally safe, since DllMain is not premptible.
 522  * If another thread holds the lock while this runs we're in trouble.
 523  * Pontus Rydin suggests wrapping the thread start routine instead.
 524  */
 525 BOOL WINAPI DllMain(HINSTANCE inst, ULONG reason, LPVOID reserved)
 526 {
 527   switch (reason) {
 528   case DLL_PROCESS_ATTACH:
 529     InitializeCriticalSection(&GC_allocate_ml);
 530     GC_init();  /* Force initialization before thread attach.   */
 531     /* fall through */
 532   case DLL_THREAD_ATTACH:
 533     {
 534       int i;
 535       /* It appears to be unsafe to acquire a lock here, since this     */
 536       /* code is apparently not preeemptible on some systems.           */
 537       /* (This is based on complaints, not on Microsoft's official      */
 538       /* documentation, which says this should perform "only simple     */
 539       /* inititalization tasks".)                                       */
 540       /* Hence we make do with nonblocking synchronization.             */
 541
 542       /* The following should be a noop according to the win32  */
 543       /* documentation.  There is empirical evidence that it    */
 544       /* isn't.         - HB                                    */
 545 #     ifdef MPROTECT_VDB
 546        if (GC_incremental) SetUnhandledExceptionFilter(GC_write_fault_handler);
 547 #     endif
 548
 549       for (i = 0;
 550                                /* cast away volatile qualifier */
 551            InterlockedExchange((LPLONG) &thread_table[i].in_use, 1) != 0;
 552            i++) {
 553         /* Compare-and-swap would make this cleaner, but that's not     */
 554         /* supported before Windows 98 and NT 4.0.  In Windows 2000,    */
 555         /* InterlockedExchange is supposed to be replaced by            */
 556         /* InterlockedExchangePointer, but that's not really what I     */
 557         /* want here.                                                   */
 558         if (i == MAX_THREADS - 1)
 559           ABORT("too many threads");
 560       }
 561       thread_table[i].id = GetCurrentThreadId();
 562       if (!DuplicateHandle(GetCurrentProcess(),
 563                            GetCurrentThread(),
 564                            GetCurrentProcess(),
 565                            /* cast away volatile qualifier */
 566                            (HANDLE *) &thread_table[i].handle,
 567                            0,
 568                            0,
 569                            DUPLICATE_SAME_ACCESS)) {
 570         DWORD last_error = GetLastError();
 571         GC_printf1("Last error code: %lx\n", last_error);
 572         ABORT("DuplicateHandle failed");
 573       }
 574       thread_table[i].stack = GC_get_stack_base();
 575       /* If this thread is being created while we are trying to stop    */
 576       /* the world, wait here.  Hopefully this can't happen on any      */
 577       /* systems that don't allow us to block here.                     */
 578       while (GC_please_stop) Sleep(20);
 579     }
 580     break;
 581   case DLL_THREAD_DETACH:
 582     {
 583       int i;
 584       DWORD thread_id = GetCurrentThreadId();
 585       LOCK();
 586       for (i = 0;
 587            i < MAX_THREADS &&
 588            (thread_table[i].stack == 0 || thread_table[i].id != thread_id);
 589            i++) {}
 590       if (i >= MAX_THREADS) {
 591           WARN("thread %ld not found on detach", (GC_word)thread_id);
 592       } else {
 593           thread_table[i].stack = 0;
 594           thread_table[i].in_use = FALSE;
 595           CloseHandle(thread_table[i].handle);
 596             /* cast away volatile qualifier */
 597           BZERO((void *) &thread_table[i].context, sizeof(CONTEXT));
 598       }
 599       UNLOCK();
 600     }
 601     break;
 602   case DLL_PROCESS_DETACH:
 603     {
 604       int i;
 605
 606       LOCK();
 607       for (i = 0; i < MAX_THREADS; ++i)
 608       {
 609           if (thread_table[i].in_use)
 610           {
 611               thread_table[i].stack = 0;
 612               thread_table[i].in_use = FALSE;
 613               CloseHandle(thread_table[i].handle);
 614               BZERO((void *) &thread_table[i].context, sizeof(CONTEXT));
 615           }
 616       }
 617       UNLOCK();
 618
 619       GC_deinit();
 620       DeleteCriticalSection(&GC_allocate_ml);
 621     }
 622     break;
 623
 624   }
 625   return TRUE;
 626 }
 627
 628 # endif /* !MSWINCE */
 629
 630 #endif /* GC_WIN32_THREADS */