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 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) ^ (-(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) ^ (-(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(pHdr->iSize, -1);
328: randomFill(z, sizeof(void*)*pHdr->nBacktraceSlots + sizeof(*pHdr) +
329: 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, nByte<pOldHdr->iSize ? nByte : pOldHdr->iSize);
352: if( nByte>pOldHdr->iSize ){
353: randomFill(&((char*)pNew)[pOldHdr->iSize], nByte - 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.xMalloc==sqlite3MemMalloc ){
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_DB) );
398: */
399: int sqlite3MemdebugHasType(void *p, u8 eType){
400: int rc = 1;
401: if( p && sqlite3GlobalConfig.m.xMalloc==sqlite3MemMalloc ){
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_DB) );
420: */
421: int sqlite3MemdebugNoType(void *p, u8 eType){
422: int rc = 1;
423: if( p && sqlite3GlobalConfig.m.xMalloc==sqlite3MemMalloc ){
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(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 */
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