src/mem2.c

   1 /*
   2 ** 2007 August 15
   3 **
   4 ** The author disclaims copyright to this source code.  In place of
   5 ** a legal notice, here is a blessing:
   6 **
   7 **    May you do good and not evil.
   8 **    May you find forgiveness for yourself and forgive others.
   9 **    May you share freely, never taking more than you give.
  10 **
  11 *************************************************************************
  12 **
  13 ** This file contains low-level memory allocation drivers for when
  14 ** SQLite will use the standard C-library malloc/realloc/free interface
  15 ** to obtain the memory it needs while adding lots of additional debugging
  16 ** information to each allocation in order to help detect and fix memory
  17 ** leaks and memory usage errors.
  18 **
  19 ** This file contains implementations of the low-level memory allocation
  20 ** routines specified in the sqlite3_mem_methods object.
  21 */
  22 #include "sqliteInt.h"
  23
  24 /*
  25 ** This version of the memory allocator is used only if the
  26 ** SQLITE_MEMDEBUG macro is defined
  27 */
  28 #ifdef SQLITE_MEMDEBUG
  29
  30 /*
  31 ** The backtrace functionality is only available with GLIBC
  32 */
  33 #ifdef __GLIBC__
  34   extern int backtrace(void**,int);
  35   extern void backtrace_symbols_fd(void*const*,int,int);
  36 #else
  37 # define backtrace(A,B) 1
  38 # define backtrace_symbols_fd(A,B,C)
  39 #endif
  40 #include <stdio.h>
  41
  42 /*
  43 ** Each memory allocation looks like this:
  44 **
  45 **  ------------------------------------------------------------------------
  46 **  | Title |  backtrace pointers |  MemBlockHdr |  allocation |  EndGuard |
  47 **  ------------------------------------------------------------------------
  48 **
  49 ** The application code sees only a pointer to the allocation.  We have
  50 ** to back up from the allocation pointer to find the MemBlockHdr.  The
  51 ** MemBlockHdr tells us the size of the allocation and the number of
  52 ** backtrace pointers.  There is also a guard word at the end of the
  53 ** MemBlockHdr.
  54 */
  55 struct MemBlockHdr {
  56   i64 iSize;                          /* Size of this allocation */
  57   struct MemBlockHdr *pNext, *pPrev;  /* Linked list of all unfreed memory */
  58   char nBacktrace;                    /* Number of backtraces on this alloc */
  59   char nBacktraceSlots;               /* Available backtrace slots */
  60   u8 nTitle;                          /* Bytes of title; includes '\0' */
  61   u8 eType;                           /* Allocation type code */
  62   int iForeGuard;                     /* Guard word for sanity */
  63 };
  64
  65 /*
  66 ** Guard words
  67 */
  68 #define FOREGUARD 0x80F5E153
  69 #define REARGUARD 0xE4676B53
  70
  71 /*
  72 ** Number of malloc size increments to track.
  73 */
  74 #define NCSIZE  1000
  75
  76 /*
  77 ** All of the static variables used by this module are collected
  78 ** into a single structure named "mem".  This is to keep the
  79 ** static variables organized and to reduce namespace pollution
  80 ** when this module is combined with other in the amalgamation.
  81 */
  82 static struct {
  83
  84   /*
  85   ** Mutex to control access to the memory allocation subsystem.
  86   */
  87   sqlite3_mutex *mutex;
  88
  89   /*
  90   ** Head and tail of a linked list of all outstanding allocations
  91   */
  92   struct MemBlockHdr *pFirst;
  93   struct MemBlockHdr *pLast;
  94
  95   /*
  96   ** The number of levels of backtrace to save in new allocations.
  97   */
  98   int nBacktrace;
  99   void (*xBacktrace)(int, int, void **);
 100
 101   /*
 102   ** Title text to insert in front of each block
 103   */
 104   int nTitle;        /* Bytes of zTitle to save.  Includes '\0' and padding */
 105   char zTitle[100];  /* The title text */
 106
 107   /*
 108   ** sqlite3MallocDisallow() increments the following counter.
 109   ** sqlite3MallocAllow() decrements it.
 110   */
 111   int disallow; /* Do not allow memory allocation */
 112
 113   /*
 114   ** Gather statistics on the sizes of memory allocations.
 115   ** nAlloc[i] is the number of allocation attempts of i*8
 116   ** bytes.  i==NCSIZE is the number of allocation attempts for
 117   ** sizes more than NCSIZE*8 bytes.
 118   */
 119   int nAlloc[NCSIZE];      /* Total number of allocations */
 120   int nCurrent[NCSIZE];    /* Current number of allocations */
 121   int mxCurrent[NCSIZE];   /* Highwater mark for nCurrent */
 122
 123 } mem;
 124
 125
 126 /*
 127 ** Adjust memory usage statistics
 128 */
 129 static void adjustStats(int iSize, int increment){
 130   int i = ROUND8(iSize)/8;
 131   if( i>NCSIZE-1 ){
 132     i = NCSIZE - 1;
 133   }
 134   if( increment>0 ){
 135     mem.nAlloc[i]++;
 136     mem.nCurrent[i]++;
 137     if( mem.nCurrent[i]>mem.mxCurrent[i] ){
 138       mem.mxCurrent[i] = mem.nCurrent[i];
 139     }
 140   }else{
 141     mem.nCurrent[i]--;
 142     assert( mem.nCurrent[i]>=0 );
 143   }
 144 }
 145
 146 /*
 147 ** Given an allocation, find the MemBlockHdr for that allocation.
 148 **
 149 ** This routine checks the guards at either end of the allocation and
 150 ** if they are incorrect it asserts.
 151 */
 152 static struct MemBlockHdr *sqlite3MemsysGetHeader(void *pAllocation){
 153   struct MemBlockHdr *p;
 154   int *pInt;
 155   u8 *pU8;
 156   int nReserve;
 157
 158   p = (struct MemBlockHdr*)pAllocation;
 159   p--;
 160   assert( p->iForeGuard==(int)FOREGUARD );
 161   nReserve = ROUND8(p->iSize);
 162   pInt = (int*)pAllocation;
 163   pU8 = (u8*)pAllocation;
 164   assert( pInt[nReserve/sizeof(int)]==(int)REARGUARD );
 165   /* This checks any of the "extra" bytes allocated due
 166   ** to rounding up to an 8 byte boundary to ensure
 167   ** they haven't been overwritten.
 168   */
 169   while( nReserve-- > p->iSize ) assert( pU8[nReserve]==0x65 );
 170   return p;
 171 }
 172
 173 /*
 174 ** Return the number of bytes currently allocated at address p.
 175 */
 176 static int sqlite3MemSize(void *p){
 177   struct MemBlockHdr *pHdr;
 178   if( !p ){
 179     return 0;
 180   }
 181   pHdr = sqlite3MemsysGetHeader(p);
 182   return (int)pHdr->iSize;
 183 }
 184
 185 /*
 186 ** Initialize the memory allocation subsystem.
 187 */
 188 static int sqlite3MemInit(void *NotUsed){
 189   UNUSED_PARAMETER(NotUsed);
 190   assert( (sizeof(struct MemBlockHdr)&7) == 0 );
 191   if( !sqlite3GlobalConfig.bMemstat ){
 192     /* If memory status is enabled, then the malloc.c wrapper will already
 193     ** hold the STATIC_MEM mutex when the routines here are invoked. */
 194     mem.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
 195   }
 196   return SQLITE_OK;
 197 }
 198
 199 /*
 200 ** Deinitialize the memory allocation subsystem.
 201 */
 202 static void sqlite3MemShutdown(void *NotUsed){
 203   UNUSED_PARAMETER(NotUsed);
 204   mem.mutex = 0;
 205 }
 206
 207 /*
 208 ** Round up a request size to the next valid allocation size.
 209 */
 210 static int sqlite3MemRoundup(int n){
 211   return ROUND8(n);
 212 }
 213
 214 /*
 215 ** Fill a buffer with pseudo-random bytes.  This is used to preset
 216 ** the content of a new memory allocation to unpredictable values and
 217 ** to clear the content of a freed allocation to unpredictable values.
 218 */
 219 static void randomFill(char *pBuf, int nByte){
 220   unsigned int x, y, r;
 221   x = SQLITE_PTR_TO_INT(pBuf);
 222   y = nByte | 1;
 223   while( nByte >= 4 ){
 224     x = (x>>1) ^ (-(int)(x&1) & 0xd0000001);
 225     y = y*1103515245 + 12345;
 226     r = x ^ y;
 227     *(int*)pBuf = r;
 228     pBuf += 4;
 229     nByte -= 4;
 230   }
 231   while( nByte-- > 0 ){
 232     x = (x>>1) ^ (-(int)(x&1) & 0xd0000001);
 233     y = y*1103515245 + 12345;
 234     r = x ^ y;
 235     *(pBuf++) = r & 0xff;
 236   }
 237 }
 238
 239 /*
 240 ** Allocate nByte bytes of memory.
 241 */
 242 static void *sqlite3MemMalloc(int nByte){
 243   struct MemBlockHdr *pHdr;
 244   void **pBt;
 245   char *z;
 246   int *pInt;
 247   void *p = 0;
 248   int totalSize;
 249   int nReserve;
 250   sqlite3_mutex_enter(mem.mutex);
 251   assert( mem.disallow==0 );
 252   nReserve = ROUND8(nByte);
 253   totalSize = nReserve + sizeof(*pHdr) + sizeof(int) +
 254                mem.nBacktrace*sizeof(void*) + mem.nTitle;
 255   p = malloc(totalSize);
 256   if( p ){
 257     z = p;
 258     pBt = (void**)&z[mem.nTitle];
 259     pHdr = (struct MemBlockHdr*)&pBt[mem.nBacktrace];
 260     pHdr->pNext = 0;
 261     pHdr->pPrev = mem.pLast;
 262     if( mem.pLast ){
 263       mem.pLast->pNext = pHdr;
 264     }else{
 265       mem.pFirst = pHdr;
 266     }
 267     mem.pLast = pHdr;
 268     pHdr->iForeGuard = FOREGUARD;
 269     pHdr->eType = MEMTYPE_HEAP;
 270     pHdr->nBacktraceSlots = mem.nBacktrace;
 271     pHdr->nTitle = mem.nTitle;
 272     if( mem.nBacktrace ){
 273       void *aAddr[40];
 274       pHdr->nBacktrace = backtrace(aAddr, mem.nBacktrace+1)-1;
 275       memcpy(pBt, &aAddr[1], pHdr->nBacktrace*sizeof(void*));
 276       assert(pBt[0]);
 277       if( mem.xBacktrace ){
 278         mem.xBacktrace(nByte, pHdr->nBacktrace-1, &aAddr[1]);
 279       }
 280     }else{
 281       pHdr->nBacktrace = 0;
 282     }
 283     if( mem.nTitle ){
 284       memcpy(z, mem.zTitle, mem.nTitle);
 285     }
 286     pHdr->iSize = nByte;
 287     adjustStats(nByte, +1);
 288     pInt = (int*)&pHdr[1];
 289     pInt[nReserve/sizeof(int)] = REARGUARD;
 290     randomFill((char*)pInt, nByte);
 291     memset(((char*)pInt)+nByte, 0x65, nReserve-nByte);
 292     p = (void*)pInt;
 293   }
 294   sqlite3_mutex_leave(mem.mutex);
 295   return p;
 296 }
 297
 298 /*
 299 ** Free memory.
 300 */
 301 static void sqlite3MemFree(void *pPrior){
 302   struct MemBlockHdr *pHdr;
 303   void **pBt;
 304   char *z;
 305   assert( sqlite3GlobalConfig.bMemstat || sqlite3GlobalConfig.bCoreMutex==0
 306        || mem.mutex!=0 );
 307   pHdr = sqlite3MemsysGetHeader(pPrior);
 308   pBt = (void**)pHdr;
 309   pBt -= pHdr->nBacktraceSlots;
 310   sqlite3_mutex_enter(mem.mutex);
 311   if( pHdr->pPrev ){
 312     assert( pHdr->pPrev->pNext==pHdr );
 313     pHdr->pPrev->pNext = pHdr->pNext;
 314   }else{
 315     assert( mem.pFirst==pHdr );
 316     mem.pFirst = pHdr->pNext;
 317   }
 318   if( pHdr->pNext ){
 319     assert( pHdr->pNext->pPrev==pHdr );
 320     pHdr->pNext->pPrev = pHdr->pPrev;
 321   }else{
 322     assert( mem.pLast==pHdr );
 323     mem.pLast = pHdr->pPrev;
 324   }
 325   z = (char*)pBt;
 326   z -= pHdr->nTitle;
 327   adjustStats((int)pHdr->iSize, -1);
 328   randomFill(z, sizeof(void*)*pHdr->nBacktraceSlots + sizeof(*pHdr) +
 329                 (int)pHdr->iSize + sizeof(int) + pHdr->nTitle);
 330   free(z);
 331   sqlite3_mutex_leave(mem.mutex);
 332 }
 333
 334 /*
 335 ** Change the size of an existing memory allocation.
 336 **
 337 ** For this debugging implementation, we *always* make a copy of the
 338 ** allocation into a new place in memory.  In this way, if the
 339 ** higher level code is using pointer to the old allocation, it is
 340 ** much more likely to break and we are much more liking to find
 341 ** the error.
 342 */
 343 static void *sqlite3MemRealloc(void *pPrior, int nByte){
 344   struct MemBlockHdr *pOldHdr;
 345   void *pNew;
 346   assert( mem.disallow==0 );
 347   assert( (nByte & 7)==0 );     /* EV: R-46199-30249 */
 348   pOldHdr = sqlite3MemsysGetHeader(pPrior);
 349   pNew = sqlite3MemMalloc(nByte);
 350   if( pNew ){
 351     memcpy(pNew, pPrior, (int)(nByte<pOldHdr->iSize ? nByte : pOldHdr->iSize));
 352     if( nByte>pOldHdr->iSize ){
 353       randomFill(&((char*)pNew)[pOldHdr->iSize], nByte - (int)pOldHdr->iSize);
 354     }
 355     sqlite3MemFree(pPrior);
 356   }
 357   return pNew;
 358 }
 359
 360 /*
 361 ** Populate the low-level memory allocation function pointers in
 362 ** sqlite3GlobalConfig.m with pointers to the routines in this file.
 363 */
 364 void sqlite3MemSetDefault(void){
 365   static const sqlite3_mem_methods defaultMethods = {
 366      sqlite3MemMalloc,
 367      sqlite3MemFree,
 368      sqlite3MemRealloc,
 369      sqlite3MemSize,
 370      sqlite3MemRoundup,
 371      sqlite3MemInit,
 372      sqlite3MemShutdown,
 373      0
 374   };
 375   sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
 376 }
 377
 378 /*
 379 ** Set the "type" of an allocation.
 380 */
 381 void sqlite3MemdebugSetType(void *p, u8 eType){
 382   if( p && sqlite3GlobalConfig.m.xFree==sqlite3MemFree ){
 383     struct MemBlockHdr *pHdr;
 384     pHdr = sqlite3MemsysGetHeader(p);
 385     assert( pHdr->iForeGuard==FOREGUARD );
 386     pHdr->eType = eType;
 387   }
 388 }
 389
 390 /*
 391 ** Return TRUE if the mask of type in eType matches the type of the
 392 ** allocation p.  Also return true if p==NULL.
 393 **
 394 ** This routine is designed for use within an assert() statement, to
 395 ** verify the type of an allocation.  For example:
 396 **
 397 **     assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
 398 */
 399 int sqlite3MemdebugHasType(void *p, u8 eType){
 400   int rc = 1;
 401   if( p && sqlite3GlobalConfig.m.xFree==sqlite3MemFree ){
 402     struct MemBlockHdr *pHdr;
 403     pHdr = sqlite3MemsysGetHeader(p);
 404     assert( pHdr->iForeGuard==FOREGUARD );         /* Allocation is valid */
 405     if( (pHdr->eType&eType)==0 ){
 406       rc = 0;
 407     }
 408   }
 409   return rc;
 410 }
 411
 412 /*
 413 ** Return TRUE if the mask of type in eType matches no bits of the type of the
 414 ** allocation p.  Also return true if p==NULL.
 415 **
 416 ** This routine is designed for use within an assert() statement, to
 417 ** verify the type of an allocation.  For example:
 418 **
 419 **     assert( sqlite3MemdebugNoType(p, MEMTYPE_LOOKASIDE) );
 420 */
 421 int sqlite3MemdebugNoType(void *p, u8 eType){
 422   int rc = 1;
 423   if( p && sqlite3GlobalConfig.m.xFree==sqlite3MemFree ){
 424     struct MemBlockHdr *pHdr;
 425     pHdr = sqlite3MemsysGetHeader(p);
 426     assert( pHdr->iForeGuard==FOREGUARD );         /* Allocation is valid */
 427     if( (pHdr->eType&eType)!=0 ){
 428       rc = 0;
 429     }
 430   }
 431   return rc;
 432 }
 433
 434 /*
 435 ** Set the number of backtrace levels kept for each allocation.
 436 ** A value of zero turns off backtracing.  The number is always rounded
 437 ** up to a multiple of 2.
 438 */
 439 void sqlite3MemdebugBacktrace(int depth){
 440   if( depth<0 ){ depth = 0; }
 441   if( depth>20 ){ depth = 20; }
 442   depth = (depth+1)&0xfe;
 443   mem.nBacktrace = depth;
 444 }
 445
 446 void sqlite3MemdebugBacktraceCallback(void (*xBacktrace)(int, int, void **)){
 447   mem.xBacktrace = xBacktrace;
 448 }
 449
 450 /*
 451 ** Set the title string for subsequent allocations.
 452 */
 453 void sqlite3MemdebugSettitle(const char *zTitle){
 454   unsigned int n = sqlite3Strlen30(zTitle) + 1;
 455   sqlite3_mutex_enter(mem.mutex);
 456   if( n>=sizeof(mem.zTitle) ) n = sizeof(mem.zTitle)-1;
 457   memcpy(mem.zTitle, zTitle, n);
 458   mem.zTitle[n] = 0;
 459   mem.nTitle = ROUND8(n);
 460   sqlite3_mutex_leave(mem.mutex);
 461 }
 462
 463 void sqlite3MemdebugSync(){
 464   struct MemBlockHdr *pHdr;
 465   for(pHdr=mem.pFirst; pHdr; pHdr=pHdr->pNext){
 466     void **pBt = (void**)pHdr;
 467     pBt -= pHdr->nBacktraceSlots;
 468     mem.xBacktrace((int)pHdr->iSize, pHdr->nBacktrace-1, &pBt[1]);
 469   }
 470 }
 471
 472 /*
 473 ** Open the file indicated and write a log of all unfreed memory
 474 ** allocations into that log.
 475 */
 476 void sqlite3MemdebugDump(const char *zFilename){
 477   FILE *out;
 478   struct MemBlockHdr *pHdr;
 479   void **pBt;
 480   int i;
 481   out = fopen(zFilename, "w");
 482   if( out==0 ){
 483     fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
 484                     zFilename);
 485     return;
 486   }
 487   for(pHdr=mem.pFirst; pHdr; pHdr=pHdr->pNext){
 488     char *z = (char*)pHdr;
 489     z -= pHdr->nBacktraceSlots*sizeof(void*) + pHdr->nTitle;
 490     fprintf(out, "**** %lld bytes at %p from %s ****\n",
 491             pHdr->iSize, &pHdr[1], pHdr->nTitle ? z : "???");
 492     if( pHdr->nBacktrace ){
 493       fflush(out);
 494       pBt = (void**)pHdr;
 495       pBt -= pHdr->nBacktraceSlots;
 496       backtrace_symbols_fd(pBt, pHdr->nBacktrace, fileno(out));
 497       fprintf(out, "\n");
 498     }
 499   }
 500   fprintf(out, "COUNTS:\n");
 501   for(i=0; i<NCSIZE-1; i++){
 502     if( mem.nAlloc[i] ){
 503       fprintf(out, "   %5d: %10d %10d %10d\n",
 504             i*8, mem.nAlloc[i], mem.nCurrent[i], mem.mxCurrent[i]);
 505     }
 506   }
 507   if( mem.nAlloc[NCSIZE-1] ){
 508     fprintf(out, "   %5d: %10d %10d %10d\n",
 509              NCSIZE*8-8, mem.nAlloc[NCSIZE-1],
 510              mem.nCurrent[NCSIZE-1], mem.mxCurrent[NCSIZE-1]);
 511   }
 512   fclose(out);
 513 }
 514
 515 /*
 516 ** Return the number of times sqlite3MemMalloc() has been called.
 517 */
 518 int sqlite3MemdebugMallocCount(){
 519   int i;
 520   int nTotal = 0;
 521   for(i=0; i<NCSIZE; i++){
 522     nTotal += mem.nAlloc[i];
 523   }
 524   return nTotal;
 525 }
 526
 527
 528 #endif /* SQLITE_MEMDEBUG */