libkern/c++/OSSymbol.cpp

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /* IOSymbol.cpp created by gvdl on Fri 1998-11-17 */
  26
  27 #include <string.h>
  28 #include <sys/cdefs.h>
  29
  30 __BEGIN_DECLS
  31 #include <kern/lock.h>
  32 __END_DECLS
  33
  34 #include <libkern/c++/OSSymbol.h>
  35 #include <libkern/c++/OSLib.h>
  36 #include <string.h>
  37
  38 #define super OSString
  39
  40 typedef struct { int i, j; } OSSymbolPoolState;
  41
  42 #if OSALLOCDEBUG
  43 extern "C" {
  44     extern int debug_container_malloc_size;
  45 };
  46 #define ACCUMSIZE(s) do { debug_container_malloc_size += (s); } while(0)
  47 #else
  48 #define ACCUMSIZE(s)
  49 #endif
  50
  51 class OSSymbolPool
  52 {
  53 private:
  54     static const unsigned int kInitBucketCount = 16;
  55
  56     typedef struct { unsigned int count; OSSymbol **symbolP; } Bucket;
  57
  58     Bucket *buckets;
  59     unsigned int nBuckets;
  60     unsigned int count;
  61     mutex_t *poolGate;
  62
  63     static inline void hashSymbol(const char *s,
  64                                   unsigned int *hashP,
  65                                   unsigned int *lenP)
  66     {
  67         unsigned int hash = 0;
  68         unsigned int len = 0;
  69
  70         /* Unroll the loop. */
  71         for (;;) {
  72             if (!*s) break; len++; hash ^= *s++;
  73             if (!*s) break; len++; hash ^= *s++ <<  8;
  74             if (!*s) break; len++; hash ^= *s++ << 16;
  75             if (!*s) break; len++; hash ^= *s++ << 24;
  76         }
  77         *lenP = len;
  78         *hashP = hash;
  79     }
  80
  81     static unsigned long log2(unsigned int x);
  82     static unsigned long exp2ml(unsigned int x);
  83
  84     void reconstructSymbols();
  85
  86 public:
  87     static void *operator new(size_t size);
  88     static void operator delete(void *mem, size_t size);
  89
  90     OSSymbolPool() { };
  91     OSSymbolPool(const OSSymbolPool *old);
  92     virtual ~OSSymbolPool();
  93
  94     bool init();
  95
  96     inline void closeGate() { mutex_lock(poolGate); };
  97     inline void openGate()  { mutex_unlock(poolGate); };
  98
  99     OSSymbol *findSymbol(const char *cString, OSSymbol ***replace) const;
 100     OSSymbol *insertSymbol(OSSymbol *sym);
 101     void removeSymbol(OSSymbol *sym);
 102
 103     OSSymbolPoolState initHashState();
 104     OSSymbol *nextHashState(OSSymbolPoolState *stateP);
 105 };
 106
 107 void * OSSymbolPool::operator new(size_t size)
 108 {
 109     void *mem = (void *)kalloc(size);
 110     ACCUMSIZE(size);
 111     assert(mem);
 112     bzero(mem, size);
 113
 114     return mem;
 115 }
 116
 117 void OSSymbolPool::operator delete(void *mem, size_t size)
 118 {
 119     kfree((vm_offset_t)mem, size);
 120     ACCUMSIZE(-size);
 121 }
 122
 123 bool OSSymbolPool::init()
 124 {
 125     count = 0;
 126     nBuckets = exp2ml(1 + log2(kInitBucketCount));
 127     buckets = (Bucket *) kalloc(nBuckets * sizeof(Bucket));
 128     ACCUMSIZE(nBuckets * sizeof(Bucket));
 129     if (!buckets)
 130         return false;
 131
 132     bzero(buckets, nBuckets * sizeof(Bucket));
 133
 134     poolGate = mutex_alloc(0);
 135
 136     return poolGate != 0;
 137 }
 138
 139 OSSymbolPool::OSSymbolPool(const OSSymbolPool *old)
 140 {
 141     count = old->count;
 142     nBuckets = old->nBuckets;
 143     buckets = old->buckets;
 144
 145     poolGate = 0;       // Do not duplicate the poolGate
 146 }
 147
 148 OSSymbolPool::~OSSymbolPool()
 149 {
 150     if (buckets) {
 151         kfree((vm_offset_t)buckets, nBuckets * sizeof(Bucket));
 152         ACCUMSIZE(-(nBuckets * sizeof(Bucket)));
 153     }
 154
 155     if (poolGate)
 156         kfree((vm_offset_t) poolGate, 36 * 4);
 157 }
 158
 159 unsigned long OSSymbolPool::log2(unsigned int x)
 160 {
 161     unsigned long i;
 162
 163     for (i = 0; x > 1 ; i++)
 164         x >>= 1;
 165     return i;
 166 }
 167
 168 unsigned long OSSymbolPool::exp2ml(unsigned int x)
 169 {
 170     return (1 << x) - 1;
 171 }
 172
 173 OSSymbolPoolState OSSymbolPool::initHashState()
 174 {
 175     OSSymbolPoolState newState = { nBuckets, 0 };
 176     return newState;
 177 }
 178
 179 OSSymbol *OSSymbolPool::nextHashState(OSSymbolPoolState *stateP)
 180 {
 181     Bucket *thisBucket = &buckets[stateP->i];
 182
 183     while (!stateP->j) {
 184         if (!stateP->i)
 185             return 0;
 186         stateP->i--;
 187         thisBucket--;
 188         stateP->j = thisBucket->count;
 189     }
 190
 191     stateP->j--;
 192     if (thisBucket->count == 1)
 193         return (OSSymbol *) thisBucket->symbolP;
 194     else
 195         return thisBucket->symbolP[stateP->j];
 196 }
 197
 198 void OSSymbolPool::reconstructSymbols()
 199 {
 200     OSSymbolPool old(this);
 201     OSSymbol *insert;
 202     OSSymbolPoolState state;
 203
 204     nBuckets += nBuckets + 1;
 205     count = 0;
 206     buckets = (Bucket *) kalloc(nBuckets * sizeof(Bucket));
 207     ACCUMSIZE(nBuckets * sizeof(Bucket));
 208     /* @@@ gvdl: Zero test and panic if can't set up pool */
 209     bzero(buckets, nBuckets * sizeof(Bucket));
 210
 211     state = old.initHashState();
 212     while ( (insert = old.nextHashState(&state)) )
 213         insertSymbol(insert);
 214 }
 215
 216 OSSymbol *OSSymbolPool::findSymbol(const char *cString, OSSymbol ***replace) const
 217 {
 218     Bucket *thisBucket;
 219     unsigned int j, inLen, hash;
 220     OSSymbol *probeSymbol, **list;
 221
 222     hashSymbol(cString, &hash, &inLen); inLen++;
 223     thisBucket = &buckets[hash % nBuckets];
 224     j = thisBucket->count;
 225
 226     *replace = NULL;
 227
 228     if (!j)
 229         return 0;
 230
 231     if (j == 1) {
 232         probeSymbol = (OSSymbol *) thisBucket->symbolP;
 233
 234         if (inLen == probeSymbol->length
 235         &&  (strcmp(probeSymbol->string, cString) == 0)) {
 236             probeSymbol->retain();
 237             if (probeSymbol->getRetainCount() != 0xffff)
 238                 return probeSymbol;
 239             else
 240                 // replace this one
 241                 *replace = (OSSymbol **) &thisBucket->symbolP;
 242         }
 243         return 0;
 244     }
 245
 246     for (list = thisBucket->symbolP; j--; list++) {
 247         probeSymbol = *list;
 248         if (inLen == probeSymbol->length
 249         &&  (strcmp(probeSymbol->string, cString) == 0)) {
 250             probeSymbol->retain();
 251             if (probeSymbol->getRetainCount() != 0xffff)
 252                 return probeSymbol;
 253             else
 254                 // replace this one
 255                 *replace = list;
 256         }
 257     }
 258
 259     return 0;
 260 }
 261
 262 OSSymbol *OSSymbolPool::insertSymbol(OSSymbol *sym)
 263 {
 264     const char *cString = sym->string;
 265     Bucket *thisBucket;
 266     unsigned int j, inLen, hash;
 267     OSSymbol *probeSymbol, **list;
 268
 269     hashSymbol(cString, &hash, &inLen); inLen++;
 270     thisBucket = &buckets[hash % nBuckets];
 271     j = thisBucket->count;
 272
 273     if (!j) {
 274         thisBucket->symbolP = (OSSymbol **) sym;
 275         thisBucket->count++;
 276         count++;
 277         return 0;
 278     }
 279
 280     if (j == 1) {
 281         probeSymbol = (OSSymbol *) thisBucket->symbolP;
 282
 283         if (inLen == probeSymbol->length
 284         &&  strcmp(probeSymbol->string, cString) == 0)
 285             return probeSymbol;
 286
 287         list = (OSSymbol **) kalloc(2 * sizeof(OSSymbol *));
 288         ACCUMSIZE(2 * sizeof(OSSymbol *));
 289         /* @@@ gvdl: Zero test and panic if can't set up pool */
 290         list[0] = sym;
 291         list[1] = probeSymbol;
 292         thisBucket->symbolP = list;
 293         thisBucket->count++;
 294         count++;
 295         if (count > nBuckets)
 296             reconstructSymbols();
 297
 298         return 0;
 299     }
 300
 301     for (list = thisBucket->symbolP; j--; list++) {
 302         probeSymbol = *list;
 303         if (inLen == probeSymbol->length
 304         &&  strcmp(probeSymbol->string, cString) == 0)
 305             return probeSymbol;
 306     }
 307
 308     j = thisBucket->count++;
 309     count++;
 310     list = (OSSymbol **) kalloc(thisBucket->count * sizeof(OSSymbol *));
 311     ACCUMSIZE(thisBucket->count * sizeof(OSSymbol *));
 312     /* @@@ gvdl: Zero test and panic if can't set up pool */
 313     list[0] = sym;
 314     bcopy(thisBucket->symbolP, list + 1, j * sizeof(OSSymbol *));
 315     kfree((vm_offset_t)thisBucket->symbolP, j * sizeof(OSSymbol *));
 316     ACCUMSIZE(-(j * sizeof(OSSymbol *)));
 317     thisBucket->symbolP = list;
 318     if (count > nBuckets)
 319         reconstructSymbols();
 320
 321     return 0;
 322 }
 323
 324 void OSSymbolPool::removeSymbol(OSSymbol *sym)
 325 {
 326     Bucket *thisBucket;
 327     unsigned int j, inLen, hash;
 328     OSSymbol *probeSymbol, **list;
 329
 330     hashSymbol(sym->string, &hash, &inLen); inLen++;
 331     thisBucket = &buckets[hash % nBuckets];
 332     j = thisBucket->count;
 333     list = thisBucket->symbolP;
 334
 335     if (!j)
 336         return;
 337
 338     if (j == 1) {
 339         probeSymbol = (OSSymbol *) list;
 340
 341         if (probeSymbol == sym) {
 342             thisBucket->symbolP = 0;
 343             count--;
 344             thisBucket->count--;
 345             return;
 346         }
 347         return;
 348     }
 349
 350     if (j == 2) {
 351         probeSymbol = list[0];
 352         if (probeSymbol == sym) {
 353             thisBucket->symbolP = (OSSymbol **) list[1];
 354             kfree((vm_offset_t)list, 2 * sizeof(OSSymbol *));
 355             ACCUMSIZE(-(2 * sizeof(OSSymbol *)));
 356             count--;
 357             thisBucket->count--;
 358             return;
 359         }
 360
 361         probeSymbol = list[1];
 362         if (probeSymbol == sym) {
 363             thisBucket->symbolP = (OSSymbol **) list[0];
 364             kfree((vm_offset_t)list, 2 * sizeof(OSSymbol *));
 365             ACCUMSIZE(-(2 * sizeof(OSSymbol *)));
 366             count--;
 367             thisBucket->count--;
 368             return;
 369         }
 370         return;
 371     }
 372
 373     for (; j--; list++) {
 374         probeSymbol = *list;
 375         if (probeSymbol == sym) {
 376
 377             list = (OSSymbol **)
 378                 kalloc((thisBucket->count-1) * sizeof(OSSymbol *));
 379             ACCUMSIZE((thisBucket->count-1) * sizeof(OSSymbol *));
 380             if (thisBucket->count-1 != j)
 381                 bcopy(thisBucket->symbolP, list,
 382                       (thisBucket->count-1-j) * sizeof(OSSymbol *));
 383             if (j)
 384                 bcopy(thisBucket->symbolP + thisBucket->count-j,
 385                       list + thisBucket->count-1-j,
 386                       j * sizeof(OSSymbol *));
 387             kfree((vm_offset_t)thisBucket->symbolP, thisBucket->count * sizeof(OSSymbol *));
 388             ACCUMSIZE(-(thisBucket->count * sizeof(OSSymbol *)));
 389             thisBucket->symbolP = list;
 390             count--;
 391             thisBucket->count--;
 392             return;
 393         }
 394     }
 395 }
 396
 397 /*
 398  *********************************************************************
 399  * From here on we are actually implementing the OSSymbol class
 400  *********************************************************************
 401  */
 402 OSDefineMetaClassAndStructorsWithInit(OSSymbol, OSString,
 403                                       OSSymbol::initialize())
 404 OSMetaClassDefineReservedUnused(OSSymbol, 0);
 405 OSMetaClassDefineReservedUnused(OSSymbol, 1);
 406 OSMetaClassDefineReservedUnused(OSSymbol, 2);
 407 OSMetaClassDefineReservedUnused(OSSymbol, 3);
 408 OSMetaClassDefineReservedUnused(OSSymbol, 4);
 409 OSMetaClassDefineReservedUnused(OSSymbol, 5);
 410 OSMetaClassDefineReservedUnused(OSSymbol, 6);
 411 OSMetaClassDefineReservedUnused(OSSymbol, 7);
 412
 413 static OSSymbolPool *pool;
 414
 415 void OSSymbol::initialize()
 416 {
 417     pool = new OSSymbolPool;
 418     assert(pool);
 419
 420     if (!pool->init()) {
 421         delete pool;
 422         assert(false);
 423     };
 424 }
 425
 426 bool OSSymbol::initWithCStringNoCopy(const char *) { return false; }
 427 bool OSSymbol::initWithCString(const char *) { return false; }
 428 bool OSSymbol::initWithString(const OSString *) { return false; }
 429
 430 const OSSymbol *OSSymbol::withString(const OSString *aString)
 431 {
 432     // This string may be a OSSymbol already, cheap check.
 433     if (OSDynamicCast(OSSymbol, aString)) {
 434         aString->retain();
 435         return (const OSSymbol *) aString;
 436     }
 437     else if (((const OSSymbol *) aString)->flags & kOSStringNoCopy)
 438         return OSSymbol::withCStringNoCopy(aString->getCStringNoCopy());
 439     else
 440         return OSSymbol::withCString(aString->getCStringNoCopy());
 441 }
 442
 443 const OSSymbol *OSSymbol::withCString(const char *cString)
 444 {
 445     OSSymbol **replace;
 446
 447     pool->closeGate();
 448
 449     OSSymbol *newSymb = pool->findSymbol(cString, &replace);
 450     if (!newSymb && (newSymb = new OSSymbol) ) {
 451         if (newSymb->OSString::initWithCString(cString)) {
 452             if (replace)
 453                 *replace = newSymb;
 454             else
 455                 pool->insertSymbol(newSymb);
 456         } else {
 457             newSymb->OSString::free();
 458             newSymb = 0;
 459         }
 460     }
 461     pool->openGate();
 462
 463     return newSymb;
 464 }
 465
 466 const OSSymbol *OSSymbol::withCStringNoCopy(const char *cString)
 467 {
 468     OSSymbol **replace;
 469
 470     pool->closeGate();
 471
 472     OSSymbol *newSymb = pool->findSymbol(cString, &replace);
 473     if (!newSymb && (newSymb = new OSSymbol) ) {
 474         if (newSymb->OSString::initWithCStringNoCopy(cString)) {
 475             if (replace)
 476                 *replace = newSymb;
 477             else
 478                 pool->insertSymbol(newSymb);
 479         } else {
 480             newSymb->OSString::free();
 481             newSymb = 0;
 482         }
 483     }
 484     pool->openGate();
 485
 486     return newSymb;
 487 }
 488
 489 void OSSymbol::checkForPageUnload(void *startAddr, void *endAddr)
 490 {
 491     OSSymbol *probeSymbol;
 492     OSSymbolPoolState state;
 493
 494     pool->closeGate();
 495     state = pool->initHashState();
 496     while ( (probeSymbol = pool->nextHashState(&state)) ) {
 497         if (probeSymbol->string >= startAddr && probeSymbol->string < endAddr) {
 498             const char *oldString = probeSymbol->string;
 499
 500             probeSymbol->string = (char *) kalloc(probeSymbol->length);
 501             ACCUMSIZE(probeSymbol->length);
 502             bcopy(oldString, probeSymbol->string, probeSymbol->length);
 503             probeSymbol->flags &= ~kOSStringNoCopy;
 504         }
 505     }
 506     pool->openGate();
 507 }
 508
 509 void OSSymbol::free()
 510 {
 511     pool->closeGate();
 512     pool->removeSymbol(this);
 513     pool->openGate();
 514
 515     super::free();
 516 }
 517
 518 bool OSSymbol::isEqualTo(const char *aCString) const
 519 {
 520     return super::isEqualTo(aCString);
 521 }
 522
 523 bool OSSymbol::isEqualTo(const OSSymbol *aSymbol) const
 524 {
 525     return aSymbol == this;
 526 }
 527
 528 bool OSSymbol::isEqualTo(const OSMetaClassBase *obj) const
 529 {
 530     OSSymbol *  sym;
 531     OSString *  str;
 532
 533     if ((sym = OSDynamicCast(OSSymbol, obj)))
 534         return isEqualTo(sym);
 535     else if ((str = OSDynamicCast(OSString, obj)))
 536         return super::isEqualTo(str);
 537     else
 538         return false;
 539 }