libgc/win32_threads.c

   1 #include "private/gc_priv.h"
   2
   3 #if defined(GC_WIN32_THREADS)
   4
   5 #include <windows.h>
   6
   7 #ifdef CYGWIN32
   8 # include <errno.h>
   9
  10  /* Cygwin-specific forward decls */
  11 # undef pthread_create
  12 # undef pthread_sigmask
  13 # undef pthread_join
  14 # undef pthread_detach
  15 # undef dlopen
  16
  17 # define DEBUG_CYGWIN_THREADS 0
  18
  19   void * GC_start_routine(void * arg);
  20   void GC_thread_exit_proc(void *arg);
  21
  22 #endif
  23
  24 /* The type of the first argument to InterlockedExchange.       */
  25 /* Documented to be LONG volatile *, but at least gcc likes     */
  26 /* this better.                                                 */
  27 typedef LONG * IE_t;
  28
  29 #ifndef MAX_THREADS
  30 # define MAX_THREADS 256
  31     /* FIXME:                                                   */
  32     /* Things may get quite slow for large numbers of threads,  */
  33     /* since we look them up with sequential search.            */
  34 #endif
  35
  36 GC_bool GC_thr_initialized = FALSE;
  37
  38 DWORD GC_main_thread = 0;
  39
  40 struct GC_thread_Rep {
  41   LONG in_use; /* Updated without lock. */
  42                         /* We assert that unused        */
  43                         /* entries have invalid ids of  */
  44                         /* zero and zero stack fields.  */
  45   DWORD id;
  46   HANDLE handle;
  47   ptr_t stack_base;     /* The cold end of the stack.   */
  48                         /* 0 ==> entry not valid.       */
  49                         /* !in_use ==> stack_base == 0  */
  50   GC_bool suspended;
  51
  52 # ifdef CYGWIN32
  53     void *status; /* hold exit value until join in case it's a pointer */
  54     pthread_t pthread_id;
  55     short flags;                /* Protected by GC lock.        */
  56 #       define FINISHED 1       /* Thread has exited.   */
  57 #       define DETACHED 2       /* Thread is intended to be detached.   */
  58 # endif
  59 };
  60
  61 typedef volatile struct GC_thread_Rep * GC_thread;
  62
  63 /*
  64  * We generally assume that volatile ==> memory ordering, at least among
  65  * volatiles.
  66  */
  67
  68 volatile GC_bool GC_please_stop = FALSE;
  69
  70 volatile struct GC_thread_Rep thread_table[MAX_THREADS];
  71
  72 volatile LONG GC_max_thread_index = 0; /* Largest index in thread_table */
  73                                        /* that was ever used.           */
  74
  75 extern LONG WINAPI GC_write_fault_handler(struct _EXCEPTION_POINTERS *exc_info);
  76
  77 int GC_thread_is_registered (void)
  78 {
  79 #if defined(GC_DLL) || defined(GC_INSIDE_DLL)
  80         /* Registered by DllMain */
  81         return 1;
  82 #else
  83         /* FIXME: */
  84         return 0;
  85 #endif
  86 }
  87
  88 void GC_allow_register_threads (void)
  89 {
  90     /* No-op for GC pre-v7. */
  91 }
  92
  93 int GC_register_my_thread (struct GC_stack_base *sb)
  94 {
  95 #   if defined(GC_DLL) || defined(GC_INSIDE_DLL)
  96         /* Registered by DllMain. */
  97         return GC_DUPLICATE;
  98 #   else
  99         /* TODO: Implement. */
 100         return GC_UNIMPLEMENTED;
 101 #   endif
 102 }
 103
 104 void GC_register_altstack (void *stack, int stack_size, void *altstack, int altstack_size)
 105 {
 106 }
 107
 108 /*
 109  * This may be called from DllMain, and hence operates under unusual
 110  * constraints.
 111  */
 112 static GC_thread GC_new_thread(void) {
 113   int i;
 114   /* It appears to be unsafe to acquire a lock here, since this */
 115   /* code is apparently not preeemptible on some systems.       */
 116   /* (This is based on complaints, not on Microsoft's official  */
 117   /* documentation, which says this should perform "only simple */
 118   /* initialization tasks".)                                    */
 119   /* Hence we make do with nonblocking synchronization.         */
 120
 121   /* The following should be a noop according to the win32      */
 122   /* documentation.  There is empirical evidence that it        */
 123   /* isn't.             - HB                                    */
 124 # if defined(MPROTECT_VDB)
 125    if (GC_incremental) SetUnhandledExceptionFilter(GC_write_fault_handler);
 126 # endif
 127                 /* cast away volatile qualifier */
 128   for (i = 0; InterlockedExchange((IE_t)&thread_table[i].in_use,1) != 0; i++) {
 129     /* Compare-and-swap would make this cleaner, but that's not         */
 130     /* supported before Windows 98 and NT 4.0.  In Windows 2000,        */
 131     /* InterlockedExchange is supposed to be replaced by                */
 132     /* InterlockedExchangePointer, but that's not really what I         */
 133     /* want here.                                                       */
 134     if (i == MAX_THREADS - 1)
 135       ABORT("too many threads");
 136   }
 137   /* Update GC_max_thread_index if necessary.  The following is safe,   */
 138   /* and unlike CompareExchange-based solutions seems to work on all    */
 139   /* Windows95 and later platforms.                                     */
 140   /* Unfortunately, GC_max_thread_index may be temporarily out of       */
 141   /* bounds, so readers have to compensate.                             */
 142   while (i > GC_max_thread_index) {
 143     InterlockedIncrement((IE_t)&GC_max_thread_index);
 144   }
 145   if (GC_max_thread_index >= MAX_THREADS) {
 146     /* We overshot due to simultaneous increments.      */
 147     /* Setting it to MAX_THREADS-1 is always safe.      */
 148     GC_max_thread_index = MAX_THREADS - 1;
 149   }
 150
 151 # ifdef CYGWIN32
 152     thread_table[i].pthread_id = pthread_self();
 153 # endif
 154   if (!DuplicateHandle(GetCurrentProcess(),
 155                        GetCurrentThread(),
 156                        GetCurrentProcess(),
 157                        (HANDLE*)&thread_table[i].handle,
 158                        0,
 159                        0,
 160                        DUPLICATE_SAME_ACCESS)) {
 161         DWORD last_error = GetLastError();
 162         GC_printf1("Last error code: %lx\n", last_error);
 163         ABORT("DuplicateHandle failed");
 164   }
 165   thread_table[i].stack_base = GC_get_stack_base();
 166   /* Up until this point, GC_push_all_stacks considers this thread      */
 167   /* invalid.                                                           */
 168   if (thread_table[i].stack_base == NULL)
 169     ABORT("Failed to find stack base in GC_new_thread");
 170   /* Up until this point, this entry is viewed as reserved but invalid  */
 171   /* by GC_delete_thread.                                               */
 172   thread_table[i].id = GetCurrentThreadId();
 173   /* If this thread is being created while we are trying to stop        */
 174   /* the world, wait here.  Hopefully this can't happen on any  */
 175   /* systems that don't allow us to block here.                 */
 176   while (GC_please_stop) Sleep(20);
 177   return thread_table + i;
 178 }
 179
 180 /*
 181  * GC_max_thread_index may temporarily be larger than MAX_THREADS.
 182  * To avoid subscript errors, we check on access.
 183  */
 184 #ifdef __GNUC__
 185 __inline__
 186 #endif
 187 static LONG GC_get_max_thread_index()
 188 {
 189   LONG my_max = GC_max_thread_index;
 190
 191   if (my_max >= MAX_THREADS) return MAX_THREADS-1;
 192   return my_max;
 193 }
 194
 195 /* This is intended to be lock-free, though that                        */
 196 /* assumes that the CloseHandle becomes visible before the              */
 197 /* in_use assignment.                                                   */
 198 static void GC_delete_gc_thread(GC_thread thr)
 199 {
 200     CloseHandle(thr->handle);
 201       /* cast away volatile qualifier */
 202     thr->stack_base = 0;
 203     thr->id = 0;
 204 #   ifdef CYGWIN32
 205       thr->pthread_id = 0;
 206 #   endif /* CYGWIN32 */
 207     thr->in_use = FALSE;
 208 }
 209
 210 static void GC_delete_thread(DWORD thread_id) {
 211   int i;
 212   LONG my_max = GC_get_max_thread_index();
 213
 214   for (i = 0;
 215        i <= my_max &&
 216        (!thread_table[i].in_use || thread_table[i].id != thread_id);
 217        /* Must still be in_use, since nobody else can store our thread_id. */
 218        i++) {}
 219   if (i > my_max) {
 220     WARN("Removing nonexistent thread %ld\n", (GC_word)thread_id);
 221   } else {
 222     GC_delete_gc_thread(thread_table+i);
 223   }
 224 }
 225
 226
 227 #ifdef CYGWIN32
 228
 229 /* Return a GC_thread corresponding to a given pthread_t.       */
 230 /* Returns 0 if it's not there.                                 */
 231 /* We assume that this is only called for pthread ids that      */
 232 /* have not yet terminated or are still joinable.               */
 233 static GC_thread GC_lookup_thread(pthread_t id)
 234 {
 235   int i;
 236   LONG my_max = GC_get_max_thread_index();
 237
 238   for (i = 0;
 239        i <= my_max &&
 240        (!thread_table[i].in_use || thread_table[i].pthread_id != id
 241         || !thread_table[i].in_use);
 242        /* Must still be in_use, since nobody else can store our thread_id. */
 243        i++);
 244   if (i > my_max) return 0;
 245   return thread_table + i;
 246 }
 247
 248 #endif /* CYGWIN32 */
 249
 250 void GC_push_thread_structures GC_PROTO((void))
 251 {
 252     /* Unlike the other threads implementations, the thread table here  */
 253     /* contains no pointers to the collectable heap.  Thus we have      */
 254     /* no private structures we need to preserve.                       */
 255 # ifdef CYGWIN32
 256   { int i; /* pthreads may keep a pointer in the thread exit value */
 257     LONG my_max = GC_get_max_thread_index();
 258
 259     for (i = 0; i <= my_max; i++)
 260       if (thread_table[i].in_use)
 261         GC_push_all((ptr_t)&(thread_table[i].status),
 262                     (ptr_t)(&(thread_table[i].status)+1));
 263   }
 264 # endif
 265 }
 266
 267 /* Defined in misc.c */
 268 extern CRITICAL_SECTION GC_write_cs;
 269
 270 void GC_stop_world()
 271 {
 272   DWORD thread_id = GetCurrentThreadId();
 273   int i;
 274
 275   if (!GC_thr_initialized) ABORT("GC_stop_world() called before GC_thr_init()");
 276
 277   GC_please_stop = TRUE;
 278 # ifndef CYGWIN32
 279     EnterCriticalSection(&GC_write_cs);
 280 # endif /* !CYGWIN32 */
 281   for (i = 0; i <= GC_get_max_thread_index(); i++)
 282     if (thread_table[i].stack_base != 0
 283         && thread_table[i].id != thread_id) {
 284 #     ifdef MSWINCE
 285         /* SuspendThread will fail if thread is running kernel code */
 286         while (SuspendThread(thread_table[i].handle) == (DWORD)-1)
 287           Sleep(10);
 288 #     else
 289         /* Apparently the Windows 95 GetOpenFileName call creates       */
 290         /* a thread that does not properly get cleaned up, and          */
 291         /* SuspendThread on its descriptor may provoke a crash.         */
 292         /* This reduces the probability of that event, though it still  */
 293         /* appears there's a race here.                                 */
 294         DWORD exitCode;
 295         if (GetExitCodeThread(thread_table[i].handle,&exitCode) &&
 296             exitCode != STILL_ACTIVE) {
 297           thread_table[i].stack_base = 0; /* prevent stack from being pushed */
 298 #         ifndef CYGWIN32
 299             /* this breaks pthread_join on Cygwin, which is guaranteed to  */
 300             /* only see user pthreads                                      */
 301             thread_table[i].in_use = FALSE;
 302             CloseHandle(thread_table[i].handle);
 303 #         endif
 304           continue;
 305         }
 306         if (SuspendThread(thread_table[i].handle) == (DWORD)-1) {
 307           thread_table[i].stack_base = 0; /* prevent stack from being pushed */
 308 #         ifndef CYGWIN32
 309             /* this breaks pthread_join on Cygwin, which is guaranteed to  */
 310             /* only see user pthreads                                      */
 311             thread_table[i].in_use = FALSE;
 312             CloseHandle(thread_table[i].handle);
 313 #         endif
 314         }
 315 #     endif
 316       thread_table[i].suspended = TRUE;
 317     }
 318 # ifndef CYGWIN32
 319     LeaveCriticalSection(&GC_write_cs);
 320 # endif /* !CYGWIN32 */
 321 }
 322
 323 void GC_start_world()
 324 {
 325   DWORD thread_id = GetCurrentThreadId();
 326   int i;
 327   LONG my_max = GC_get_max_thread_index();
 328
 329   for (i = 0; i <= my_max; i++)
 330     if (thread_table[i].stack_base != 0 && thread_table[i].suspended
 331         && thread_table[i].id != thread_id) {
 332       if (ResumeThread(thread_table[i].handle) == (DWORD)-1)
 333         ABORT("ResumeThread failed");
 334       thread_table[i].suspended = FALSE;
 335     }
 336   GC_please_stop = FALSE;
 337 }
 338
 339 # ifdef _MSC_VER
 340 #   pragma warning(disable:4715)
 341 # endif
 342 ptr_t GC_current_stackbottom()
 343 {
 344   DWORD thread_id = GetCurrentThreadId();
 345   int i;
 346   LONG my_max = GC_get_max_thread_index();
 347
 348   for (i = 0; i <= my_max; i++)
 349     if (thread_table[i].stack_base && thread_table[i].id == thread_id)
 350       return thread_table[i].stack_base;
 351   ABORT("no thread table entry for current thread");
 352 }
 353 # ifdef _MSC_VER
 354 #   pragma warning(default:4715)
 355 # endif
 356
 357 # ifdef MSWINCE
 358     /* The VirtualQuery calls below won't work properly on WinCE, but   */
 359     /* since each stack is restricted to an aligned 64K region of       */
 360     /* virtual memory we can just take the next lowest multiple of 64K. */
 361 #   define GC_get_stack_min(s) \
 362         ((ptr_t)(((DWORD)(s) - 1) & 0xFFFF0000))
 363 # else
 364     static ptr_t GC_get_stack_min(ptr_t s)
 365     {
 366         ptr_t bottom;
 367         MEMORY_BASIC_INFORMATION info;
 368         VirtualQuery(s, &info, sizeof(info));
 369         do {
 370             bottom = info.BaseAddress;
 371             VirtualQuery(bottom - 1, &info, sizeof(info));
 372         } while ((info.Protect & PAGE_READWRITE)
 373                  && !(info.Protect & PAGE_GUARD));
 374         return(bottom);
 375     }
 376 # endif
 377
 378 void GC_push_all_stacks()
 379 {
 380   DWORD thread_id = GetCurrentThreadId();
 381   GC_bool found_me = FALSE;
 382   int i;
 383   int dummy;
 384   ptr_t sp, stack_min;
 385   GC_thread thread;
 386   LONG my_max = GC_get_max_thread_index();
 387
 388   for (i = 0; i <= my_max; i++) {
 389     thread = thread_table + i;
 390     if (thread -> in_use && thread -> stack_base) {
 391       if (thread -> id == thread_id) {
 392         sp = (ptr_t) &dummy;
 393         found_me = TRUE;
 394       } else {
 395         CONTEXT context;
 396         context.ContextFlags = CONTEXT_INTEGER|CONTEXT_CONTROL;
 397         if (!GetThreadContext(thread_table[i].handle, &context))
 398           ABORT("GetThreadContext failed");
 399
 400         /* Push all registers that might point into the heap.  Frame    */
 401         /* pointer registers are included in case client code was       */
 402         /* compiled with the 'omit frame pointer' optimisation.         */
 403 #       define PUSH1(reg) GC_push_one((word)context.reg)
 404 #       define PUSH2(r1,r2) PUSH1(r1), PUSH1(r2)
 405 #       define PUSH4(r1,r2,r3,r4) PUSH2(r1,r2), PUSH2(r3,r4)
 406 #       if defined(I386)
 407           PUSH4(Edi,Esi,Ebx,Edx), PUSH2(Ecx,Eax), PUSH1(Ebp);
 408           sp = (ptr_t)context.Esp;
 409 #       elif defined(X86_64)
 410           PUSH4(Rax,Rcx,Rdx,Rbx); PUSH2(Rbp, Rsi); PUSH1(Rdi);
 411           PUSH4(R8, R9, R10, R11); PUSH4(R12, R13, R14, R15);
 412           sp = (ptr_t)context.Rsp;
 413 #       elif defined(ARM32)
 414           PUSH4(R0,R1,R2,R3),PUSH4(R4,R5,R6,R7),PUSH4(R8,R9,R10,R11),PUSH1(R12);
 415           sp = (ptr_t)context.Sp;
 416 #       elif defined(SHx)
 417           PUSH4(R0,R1,R2,R3), PUSH4(R4,R5,R6,R7), PUSH4(R8,R9,R10,R11);
 418           PUSH2(R12,R13), PUSH1(R14);
 419           sp = (ptr_t)context.R15;
 420 #       elif defined(MIPS)
 421           PUSH4(IntAt,IntV0,IntV1,IntA0), PUSH4(IntA1,IntA2,IntA3,IntT0);
 422           PUSH4(IntT1,IntT2,IntT3,IntT4), PUSH4(IntT5,IntT6,IntT7,IntS0);
 423           PUSH4(IntS1,IntS2,IntS3,IntS4), PUSH4(IntS5,IntS6,IntS7,IntT8);
 424           PUSH4(IntT9,IntK0,IntK1,IntS8);
 425           sp = (ptr_t)context.IntSp;
 426 #       elif defined(PPC)
 427           PUSH4(Gpr0, Gpr3, Gpr4, Gpr5),  PUSH4(Gpr6, Gpr7, Gpr8, Gpr9);
 428           PUSH4(Gpr10,Gpr11,Gpr12,Gpr14), PUSH4(Gpr15,Gpr16,Gpr17,Gpr18);
 429           PUSH4(Gpr19,Gpr20,Gpr21,Gpr22), PUSH4(Gpr23,Gpr24,Gpr25,Gpr26);
 430           PUSH4(Gpr27,Gpr28,Gpr29,Gpr30), PUSH1(Gpr31);
 431           sp = (ptr_t)context.Gpr1;
 432 #       elif defined(ALPHA)
 433           PUSH4(IntV0,IntT0,IntT1,IntT2), PUSH4(IntT3,IntT4,IntT5,IntT6);
 434           PUSH4(IntT7,IntS0,IntS1,IntS2), PUSH4(IntS3,IntS4,IntS5,IntFp);
 435           PUSH4(IntA0,IntA1,IntA2,IntA3), PUSH4(IntA4,IntA5,IntT8,IntT9);
 436           PUSH4(IntT10,IntT11,IntT12,IntAt);
 437           sp = (ptr_t)context.IntSp;
 438 #       else
 439 #         error "architecture is not supported"
 440 #       endif
 441       }
 442
 443       stack_min = GC_get_stack_min(thread->stack_base);
 444
 445       if (sp >= stack_min && sp < thread->stack_base)
 446         GC_push_all_stack(sp, thread->stack_base);
 447       else {
 448         WARN("Thread stack pointer 0x%lx out of range, pushing everything\n",
 449              (unsigned long)sp);
 450         GC_push_all_stack(stack_min, thread->stack_base);
 451       }
 452     }
 453   }
 454   if (!found_me) ABORT("Collecting from unknown thread.");
 455 }
 456
 457 void GC_get_next_stack(char *start, char **lo, char **hi)
 458 {
 459     int i;
 460 #   define ADDR_LIMIT (char *)(-1L)
 461     char * current_min = ADDR_LIMIT;
 462     LONG my_max = GC_get_max_thread_index();
 463
 464     for (i = 0; i <= my_max; i++) {
 465         char * s = (char *)thread_table[i].stack_base;
 466
 467         if (0 != s && s > start && s < current_min) {
 468             current_min = s;
 469         }
 470     }
 471     *hi = current_min;
 472     if (current_min == ADDR_LIMIT) {
 473         *lo = ADDR_LIMIT;
 474         return;
 475     }
 476     *lo = GC_get_stack_min(current_min);
 477     if (*lo < start) *lo = start;
 478 }
 479
 480 #if !defined(CYGWIN32)
 481
 482 #if !defined(MSWINCE) && defined(GC_DLL)
 483
 484 /* We register threads from DllMain */
 485
 486 GC_API HANDLE WINAPI GC_CreateThread(
 487     LPSECURITY_ATTRIBUTES lpThreadAttributes,
 488     DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
 489     LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
 490 {
 491     return CreateThread(lpThreadAttributes, dwStackSize, lpStartAddress,
 492                         lpParameter, dwCreationFlags, lpThreadId);
 493 }
 494
 495 #else /* defined(MSWINCE) || !defined(GC_DLL))  */
 496
 497 /* We have no DllMain to take care of new threads.  Thus we     */
 498 /* must properly intercept thread creation.                     */
 499
 500 typedef struct {
 501     LPTHREAD_START_ROUTINE start;
 502     LPVOID param;
 503 } thread_args;
 504
 505 static DWORD WINAPI thread_start(LPVOID arg);
 506
 507 GC_API HANDLE WINAPI GC_CreateThread(
 508     LPSECURITY_ATTRIBUTES lpThreadAttributes,
 509     DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
 510     LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
 511 {
 512     HANDLE thread_h = NULL;
 513
 514     thread_args *args;
 515
 516     if (!GC_is_initialized) GC_init();
 517                 /* make sure GC is initialized (i.e. main thread is attached) */
 518
 519     args = GC_malloc_uncollectable(sizeof(thread_args));
 520         /* Handed off to and deallocated by child thread.       */
 521     if (0 == args) {
 522         SetLastError(ERROR_NOT_ENOUGH_MEMORY);
 523         return NULL;
 524     }
 525
 526     /* set up thread arguments */
 527         args -> start = lpStartAddress;
 528         args -> param = lpParameter;
 529
 530     thread_h = CreateThread(lpThreadAttributes,
 531                             dwStackSize, thread_start,
 532                             args, dwCreationFlags,
 533                             lpThreadId);
 534
 535     return thread_h;
 536 }
 537
 538 static DWORD WINAPI thread_start(LPVOID arg)
 539 {
 540     DWORD ret = 0;
 541     thread_args *args = (thread_args *)arg;
 542
 543     GC_new_thread();
 544
 545     /* Clear the thread entry even if we exit with an exception.        */
 546     /* This is probably pointless, since an uncaught exception is       */
 547     /* supposed to result in the process being killed.                  */
 548 #ifndef __GNUC__
 549     __try {
 550 #endif /* __GNUC__ */
 551         ret = args->start (args->param);
 552 #ifndef __GNUC__
 553     } __finally {
 554 #endif /* __GNUC__ */
 555         GC_free(args);
 556         GC_delete_thread(GetCurrentThreadId());
 557 #ifndef __GNUC__
 558     }
 559 #endif /* __GNUC__ */
 560
 561     return ret;
 562 }
 563 #endif /* !defined(MSWINCE) && !(defined(__MINGW32__) && !defined(_DLL))  */
 564
 565 #endif /* !CYGWIN32 */
 566
 567 #ifdef MSWINCE
 568
 569 typedef struct {
 570     HINSTANCE hInstance;
 571     HINSTANCE hPrevInstance;
 572     LPWSTR lpCmdLine;
 573     int nShowCmd;
 574 } main_thread_args;
 575
 576 DWORD WINAPI main_thread_start(LPVOID arg);
 577
 578 int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 579                    LPWSTR lpCmdLine, int nShowCmd)
 580 {
 581     DWORD exit_code = 1;
 582
 583     main_thread_args args = {
 584         hInstance, hPrevInstance, lpCmdLine, nShowCmd
 585     };
 586     HANDLE thread_h;
 587     DWORD thread_id;
 588
 589     /* initialize everything */
 590     GC_init();
 591
 592     /* start the main thread */
 593     thread_h = GC_CreateThread(
 594         NULL, 0, main_thread_start, &args, 0, &thread_id);
 595
 596     if (thread_h != NULL)
 597     {
 598         WaitForSingleObject (thread_h, INFINITE);
 599         GetExitCodeThread (thread_h, &exit_code);
 600         CloseHandle (thread_h);
 601     }
 602
 603     GC_deinit();
 604     DeleteCriticalSection(&GC_allocate_ml);
 605
 606     return (int) exit_code;
 607 }
 608
 609 DWORD WINAPI main_thread_start(LPVOID arg)
 610 {
 611     main_thread_args * args = (main_thread_args *) arg;
 612
 613     return (DWORD) GC_WinMain (args->hInstance, args->hPrevInstance,
 614                                args->lpCmdLine, args->nShowCmd);
 615 }
 616
 617 # else /* !MSWINCE */
 618
 619 /* Called by GC_init() - we hold the allocation lock.   */
 620 void GC_thr_init() {
 621     if (GC_thr_initialized) return;
 622     GC_main_thread = GetCurrentThreadId();
 623     GC_thr_initialized = TRUE;
 624
 625     /* Add the initial thread, so we can stop it.       */
 626     GC_new_thread();
 627 }
 628
 629 #ifdef CYGWIN32
 630
 631 struct start_info {
 632     void *(*start_routine)(void *);
 633     void *arg;
 634     GC_bool detached;
 635 };
 636
 637 int GC_pthread_join(pthread_t pthread_id, void **retval) {
 638     int result;
 639     int i;
 640     GC_thread me;
 641
 642 #   if DEBUG_CYGWIN_THREADS
 643       GC_printf3("thread 0x%x(0x%x) is joining thread 0x%x.\n",
 644                  (int)pthread_self(), GetCurrentThreadId(), (int)pthread_id);
 645 #   endif
 646
 647     /* Thread being joined might not have registered itself yet. */
 648     /* After the join,thread id may have been recycled.          */
 649     /* FIXME: It would be better if this worked more like        */
 650     /* pthread_support.c.                                        */
 651
 652     while ((me = GC_lookup_thread(pthread_id)) == 0) Sleep(10);
 653
 654     result = pthread_join(pthread_id, retval);
 655
 656     GC_delete_gc_thread(me);
 657
 658 #   if DEBUG_CYGWIN_THREADS
 659       GC_printf3("thread 0x%x(0x%x) completed join with thread 0x%x.\n",
 660                  (int)pthread_self(), GetCurrentThreadId(), (int)pthread_id);
 661 #   endif
 662
 663     return result;
 664 }
 665
 666 /* Cygwin-pthreads calls CreateThread internally, but it's not
 667  * easily interceptible by us..
 668  *   so intercept pthread_create instead
 669  */
 670 int
 671 GC_pthread_create(pthread_t *new_thread,
 672                   const pthread_attr_t *attr,
 673                   void *(*start_routine)(void *), void *arg) {
 674     int result;
 675     struct start_info * si;
 676
 677     if (!GC_is_initialized) GC_init();
 678                 /* make sure GC is initialized (i.e. main thread is attached) */
 679
 680     /* This is otherwise saved only in an area mmapped by the thread */
 681     /* library, which isn't visible to the collector.            */
 682     si = GC_malloc_uncollectable(sizeof(struct start_info));
 683     if (0 == si) return(EAGAIN);
 684
 685     si -> start_routine = start_routine;
 686     si -> arg = arg;
 687     if (attr != 0 &&
 688         pthread_attr_getdetachstate(attr, &si->detached)
 689         == PTHREAD_CREATE_DETACHED) {
 690       si->detached = TRUE;
 691     }
 692
 693 #   if DEBUG_CYGWIN_THREADS
 694       GC_printf2("About to create a thread from 0x%x(0x%x)\n",
 695                  (int)pthread_self(), GetCurrentThreadId);
 696 #   endif
 697     result = pthread_create(new_thread, attr, GC_start_routine, si);
 698
 699     if (result) { /* failure */
 700         GC_free(si);
 701     }
 702
 703     return(result);
 704 }
 705
 706 void * GC_start_routine(void * arg)
 707 {
 708     struct start_info * si = arg;
 709     void * result;
 710     void *(*start)(void *);
 711     void *start_arg;
 712     pthread_t pthread_id;
 713     GC_thread me;
 714     GC_bool detached;
 715     int i;
 716
 717 #   if DEBUG_CYGWIN_THREADS
 718       GC_printf2("thread 0x%x(0x%x) starting...\n",(int)pthread_self(),
 719                                                    GetCurrentThreadId());
 720 #   endif
 721
 722     /* If a GC occurs before the thread is registered, that GC will     */
 723     /* ignore this thread.  That's fine, since it will block trying to  */
 724     /* acquire the allocation lock, and won't yet hold interesting      */
 725     /* pointers.                                                        */
 726     LOCK();
 727     /* We register the thread here instead of in the parent, so that    */
 728     /* we don't need to hold the allocation lock during pthread_create. */
 729     me = GC_new_thread();
 730     UNLOCK();
 731
 732     start = si -> start_routine;
 733     start_arg = si -> arg;
 734     if (si-> detached) me -> flags |= DETACHED;
 735     me -> pthread_id = pthread_id = pthread_self();
 736
 737     GC_free(si); /* was allocated uncollectable */
 738
 739     pthread_cleanup_push(GC_thread_exit_proc, (void *)me);
 740     result = (*start)(start_arg);
 741     me -> status = result;
 742     pthread_cleanup_pop(0);
 743
 744 #   if DEBUG_CYGWIN_THREADS
 745       GC_printf2("thread 0x%x(0x%x) returned from start routine.\n",
 746                  (int)pthread_self(),GetCurrentThreadId());
 747 #   endif
 748
 749     return(result);
 750 }
 751
 752 void GC_thread_exit_proc(void *arg)
 753 {
 754     GC_thread me = (GC_thread)arg;
 755     int i;
 756
 757 #   if DEBUG_CYGWIN_THREADS
 758       GC_printf2("thread 0x%x(0x%x) called pthread_exit().\n",
 759                  (int)pthread_self(),GetCurrentThreadId());
 760 #   endif
 761
 762     LOCK();
 763     if (me -> flags & DETACHED) {
 764       GC_delete_thread(GetCurrentThreadId());
 765     } else {
 766       /* deallocate it as part of join */
 767       me -> flags |= FINISHED;
 768     }
 769     UNLOCK();
 770 }
 771
 772 /* nothing required here... */
 773 int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) {
 774   return pthread_sigmask(how, set, oset);
 775 }
 776
 777 int GC_pthread_detach(pthread_t thread)
 778 {
 779     int result;
 780     GC_thread thread_gc_id;
 781
 782     LOCK();
 783     thread_gc_id = GC_lookup_thread(thread);
 784     UNLOCK();
 785     result = pthread_detach(thread);
 786     if (result == 0) {
 787       LOCK();
 788       thread_gc_id -> flags |= DETACHED;
 789       /* Here the pthread thread id may have been recycled. */
 790       if (thread_gc_id -> flags & FINISHED) {
 791         GC_delete_gc_thread(thread_gc_id);
 792       }
 793       UNLOCK();
 794     }
 795     return result;
 796 }
 797
 798 #else /* !CYGWIN32 */
 799
 800 /*
 801  * We avoid acquiring locks here, since this doesn't seem to be preemptable.
 802  * Pontus Rydin suggests wrapping the thread start routine instead.
 803  */
 804 #if defined(GC_DLL) || defined(GC_INSIDE_DLL)
 805 BOOL WINAPI GC_DllMain(HINSTANCE inst, ULONG reason, LPVOID reserved)
 806 {
 807   switch (reason) {
 808   case DLL_PROCESS_ATTACH:
 809     GC_init();  /* Force initialization before thread attach.   */
 810     /* fall through */
 811   case DLL_THREAD_ATTACH:
 812     GC_ASSERT(GC_thr_initialized);
 813     if (GC_main_thread != GetCurrentThreadId()) {
 814         GC_new_thread();
 815     } /* o.w. we already did it during GC_thr_init(), called by GC_init() */
 816     break;
 817
 818   case DLL_THREAD_DETACH:
 819     GC_delete_thread(GetCurrentThreadId());
 820     break;
 821
 822   case DLL_PROCESS_DETACH:
 823     {
 824       int i;
 825
 826       LOCK();
 827       for (i = 0; i <= GC_get_max_thread_index(); ++i)
 828       {
 829           if (thread_table[i].in_use)
 830             GC_delete_gc_thread(thread_table + i);
 831       }
 832       UNLOCK();
 833
 834       GC_deinit();
 835       DeleteCriticalSection(&GC_allocate_ml);
 836     }
 837     break;
 838
 839   }
 840   return TRUE;
 841 }
 842 #endif /* GC_DLL */
 843 #endif /* !CYGWIN32 */
 844
 845 # endif /* !MSWINCE */
 846
 847 #endif /* GC_WIN32_THREADS */