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