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
 335 # ifdef MSWINCE
 336
 337 typedef struct {
 338     HANDLE child_ready_h, parent_ready_h;
 339     volatile struct thread_entry * entry;
 340     LPTHREAD_START_ROUTINE start;
 341     LPVOID param;
 342 } thread_args;
 343
 344 DWORD WINAPI thread_start(LPVOID arg);
 345
 346 HANDLE WINAPI GC_CreateThread(
 347     LPSECURITY_ATTRIBUTES lpThreadAttributes,
 348     DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
 349     LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
 350 {
 351     HANDLE thread_h = NULL;
 352     HANDLE child_ready_h, parent_ready_h;
 353
 354     int i;
 355     thread_args args;
 356
 357     /* allocate thread slot */
 358     LOCK();
 359     for (i = 0; i != MAX_THREADS && thread_table[i].in_use; i++)
 360         ;
 361     if (i != MAX_THREADS) {
 362         thread_table[i].in_use = TRUE;
 363     }
 364     UNLOCK();
 365
 366     if (i != MAX_THREADS) {
 367
 368         /* create unnamed unsignalled events */
 369         if (child_ready_h = CreateEvent(NULL, FALSE, FALSE, NULL)) {
 370             if (parent_ready_h = CreateEvent(NULL, FALSE, FALSE, NULL)) {
 371
 372                 /* set up thread arguments */
 373                 args.child_ready_h = child_ready_h;
 374                 args.parent_ready_h = parent_ready_h;
 375                 args.entry = &thread_table[i];
 376                 args.start = lpStartAddress;
 377                 args.param = lpParameter;
 378
 379                 thread_h = CreateThread(lpThreadAttributes,
 380                                         dwStackSize, thread_start,
 381                                         &args,
 382                                         dwCreationFlags & ~CREATE_SUSPENDED,
 383                                         lpThreadId);
 384
 385                 if (thread_h) {
 386
 387                     /* fill in ID and handle; tell child this is done */
 388                     thread_table[i].id = *lpThreadId;
 389                     thread_table[i].handle = thread_h;
 390                     SetEvent (parent_ready_h);
 391
 392                     /* wait for child to fill in stack and copy args */
 393                     WaitForSingleObject (child_ready_h, INFINITE);
 394
 395                     /* suspend the child if requested */
 396                     if (dwCreationFlags & CREATE_SUSPENDED)
 397                         SuspendThread (thread_h);
 398
 399                     /* let child call given function now (or when resumed) */
 400                     SetEvent (parent_ready_h);
 401
 402                 } else {
 403                     CloseHandle (parent_ready_h);
 404                 }
 405             }
 406         }
 407
 408         CloseHandle (child_ready_h);
 409
 410         if (thread_h == NULL)
 411             thread_table[i].in_use = FALSE;
 412
 413     } else { /* no thread slot found */
 414         SetLastError (ERROR_TOO_MANY_TCBS);
 415     }
 416
 417     return thread_h;
 418 }
 419
 420 static DWORD WINAPI thread_start(LPVOID arg)
 421 {
 422     DWORD ret = 0;
 423     thread_args args = *(thread_args *)arg;
 424
 425     /* wait for parent to fill in ID and handle */
 426     WaitForSingleObject (args.parent_ready_h, INFINITE);
 427     ResetEvent (args.parent_ready_h);
 428
 429     /* fill in stack; tell parent this is done */
 430     args.entry->stack = GC_get_stack_base();
 431     SetEvent (args.child_ready_h);
 432
 433     /* wait for parent to tell us to go (in case it needs to suspend us) */
 434     WaitForSingleObject (args.parent_ready_h, INFINITE);
 435     CloseHandle (args.parent_ready_h);
 436
 437     /* Clear the thread entry even if we exit with an exception.        */
 438     /* This is probably pointless, since an uncaught exception is       */
 439     /* supposed to result in the process being killed.                  */
 440     __try {
 441         ret = args.start (args.param);
 442     } __finally {
 443         LOCK();
 444         args.entry->stack = 0;
 445         args.entry->in_use = FALSE;
 446               /* cast away volatile qualifier */
 447         BZERO((void *) &args.entry->context, sizeof(CONTEXT));
 448         UNLOCK();
 449     }
 450
 451     return ret;
 452 }
 453
 454 typedef struct {
 455     HINSTANCE hInstance;
 456     HINSTANCE hPrevInstance;
 457     LPWSTR lpCmdLine;
 458     int nShowCmd;
 459 } main_thread_args;
 460
 461 DWORD WINAPI main_thread_start(LPVOID arg);
 462
 463 int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 464                    LPWSTR lpCmdLine, int nShowCmd)
 465 {
 466     DWORD exit_code = 1;
 467
 468     main_thread_args args = {
 469         hInstance, hPrevInstance, lpCmdLine, nShowCmd
 470     };
 471     HANDLE thread_h;
 472     DWORD thread_id;
 473
 474     /* initialize everything */
 475     InitializeCriticalSection(&GC_allocate_ml);
 476     GC_init();
 477
 478     /* start the main thread */
 479     thread_h = GC_CreateThread(
 480         NULL, 0, main_thread_start, &args, 0, &thread_id);
 481
 482     if (thread_h != NULL)
 483     {
 484         WaitForSingleObject (thread_h, INFINITE);
 485         GetExitCodeThread (thread_h, &exit_code);
 486         CloseHandle (thread_h);
 487     }
 488
 489     GC_deinit();
 490     DeleteCriticalSection(&GC_allocate_ml);
 491
 492     return (int) exit_code;
 493 }
 494
 495 DWORD WINAPI main_thread_start(LPVOID arg)
 496 {
 497     main_thread_args * args = (main_thread_args *) arg;
 498
 499     return (DWORD) GC_WinMain (args->hInstance, args->hPrevInstance,
 500                                args->lpCmdLine, args->nShowCmd);
 501 }
 502
 503 # else /* !MSWINCE */
 504
 505 LONG WINAPI GC_write_fault_handler(struct _EXCEPTION_POINTERS *exc_info);
 506
 507 /*
 508  * This isn't generally safe, since DllMain is not premptible.
 509  * If another thread holds the lock while this runs we're in trouble.
 510  * Pontus Rydin suggests wrapping the thread start routine instead.
 511  */
 512 BOOL WINAPI DllMain(HINSTANCE inst, ULONG reason, LPVOID reserved)
 513 {
 514   switch (reason) {
 515   case DLL_PROCESS_ATTACH:
 516     InitializeCriticalSection(&GC_allocate_ml);
 517     GC_init();  /* Force initialization before thread attach.   */
 518     /* fall through */
 519   case DLL_THREAD_ATTACH:
 520     {
 521       int i;
 522       /* It appears to be unsafe to acquire a lock here, since this     */
 523       /* code is apparently not preeemptible on some systems.           */
 524       /* (This is based on complaints, not on Microsoft's official      */
 525       /* documentation, which says this should perform "only simple     */
 526       /* inititalization tasks".)                                       */
 527       /* Hence we make do with nonblocking synchronization.             */
 528
 529       /* The following should be a noop according to the win32  */
 530       /* documentation.  There is empirical evidence that it    */
 531       /* isn't.         - HB                                    */
 532 #     ifdef MPROTECT_VDB
 533        if (GC_incremental) SetUnhandledExceptionFilter(GC_write_fault_handler);
 534 #     endif
 535
 536       for (i = 0;
 537                                /* cast away volatile qualifier */
 538            InterlockedExchange((LPLONG) &thread_table[i].in_use, 1) != 0;
 539            i++) {
 540         /* Compare-and-swap would make this cleaner, but that's not     */
 541         /* supported before Windows 98 and NT 4.0.  In Windows 2000,    */
 542         /* InterlockedExchange is supposed to be replaced by            */
 543         /* InterlockedExchangePointer, but that's not really what I     */
 544         /* want here.                                                   */
 545         if (i == MAX_THREADS - 1)
 546           ABORT("too many threads");
 547       }
 548       thread_table[i].id = GetCurrentThreadId();
 549       if (!DuplicateHandle(GetCurrentProcess(),
 550                            GetCurrentThread(),
 551                            GetCurrentProcess(),
 552                            /* cast away volatile qualifier */
 553                            (HANDLE *) &thread_table[i].handle,
 554                            0,
 555                            0,
 556                            DUPLICATE_SAME_ACCESS)) {
 557         DWORD last_error = GetLastError();
 558         GC_printf1("Last error code: %lx\n", last_error);
 559         ABORT("DuplicateHandle failed");
 560       }
 561       thread_table[i].stack = GC_get_stack_base();
 562       /* If this thread is being created while we are trying to stop    */
 563       /* the world, wait here.  Hopefully this can't happen on any      */
 564       /* systems that don't allow us to block here.                     */
 565       while (GC_please_stop) Sleep(20);
 566     }
 567     break;
 568   case DLL_THREAD_DETACH:
 569     {
 570       int i;
 571       DWORD thread_id = GetCurrentThreadId();
 572       LOCK();
 573       for (i = 0;
 574            i < MAX_THREADS &&
 575            (thread_table[i].stack == 0 || thread_table[i].id != thread_id);
 576            i++) {}
 577       if (i >= MAX_THREADS) {
 578           WARN("thread %ld not found on detach", (GC_word)thread_id);
 579       } else {
 580           thread_table[i].stack = 0;
 581           thread_table[i].in_use = FALSE;
 582           CloseHandle(thread_table[i].handle);
 583             /* cast away volatile qualifier */
 584           BZERO((void *) &thread_table[i].context, sizeof(CONTEXT));
 585       }
 586       UNLOCK();
 587     }
 588     break;
 589   case DLL_PROCESS_DETACH:
 590     {
 591       int i;
 592
 593       LOCK();
 594       for (i = 0; i < MAX_THREADS; ++i)
 595       {
 596           if (thread_table[i].in_use)
 597           {
 598               thread_table[i].stack = 0;
 599               thread_table[i].in_use = FALSE;
 600               CloseHandle(thread_table[i].handle);
 601               BZERO((void *) &thread_table[i].context, sizeof(CONTEXT));
 602           }
 603       }
 604       UNLOCK();
 605
 606       GC_deinit();
 607       DeleteCriticalSection(&GC_allocate_ml);
 608     }
 609     break;
 610
 611   }
 612   return TRUE;
 613 }
 614
 615 # endif /* !MSWINCE */
 616
 617 #endif /* GC_WIN32_THREADS */