SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite.  
**
** $Id: mem2.c,v 1.26 2008/04/10 14:57:25 drh Exp $
*/
#include "sqliteInt.h"

/*
** This version of the memory allocator is used only if the
** SQLITE_MEMDEBUG macro is defined
*/

** The application code sees only a pointer to the allocation.  We have
** to back up from the allocation pointer to find the MemBlockHdr.  The
** MemBlockHdr tells us the size of the allocation and the number of
** backtrace pointers.  There is also a guard word at the end of the
** MemBlockHdr.
*/
struct MemBlockHdr {
  i64 iSize;                          /* Size of this allocation */
  struct MemBlockHdr *pNext, *pPrev;  /* Linked list of all unfreed memory */

  char nBacktrace;                    /* Number of backtraces on this alloc */
  char nBacktraceSlots;               /* Available backtrace slots */
  short nTitle;                       /* Bytes of title; includes '\0' */
  int iForeGuard;                     /* Guard word for sanity */
};

/*

  int *pInt;
  u8 *pU8;
  int nReserve;

  p = (struct MemBlockHdr*)pAllocation;
  p--;
  assert( p->iForeGuard==FOREGUARD );
  nReserve = (p->iSize+7)&~7;
  pInt = (int*)pAllocation;
  pU8 = (u8*)pAllocation;
  assert( pInt[nReserve/sizeof(int)]==REARGUARD );
  assert( (nReserve-0)<=p->iSize || pU8[nReserve-1]==0x65 );
  assert( (nReserve-1)<=p->iSize || pU8[nReserve-2]==0x65 );
  assert( (nReserve-2)<=p->iSize || pU8[nReserve-3]==0x65 );
  return p;

  if( nByte>0 ){
    int nReserve;
    enterMem();
    assert( mem.disallow==0 );
    if( mem.alarmCallback!=0 && mem.nowUsed+nByte>=mem.alarmThreshold ){
      sqlite3MemsysAlarm(nByte);
    }
    nReserve = (nByte+7)&~7;
    if( nReserve/8>NCSIZE-1 ){
      mem.sizeCnt[NCSIZE-1]++;
    }else{
      mem.sizeCnt[nReserve/8]++;
    }
    totalSize = nReserve + sizeof(*pHdr) + sizeof(int) +
                 mem.nBacktrace*sizeof(void*) + mem.nTitle;

*/
void sqlite3MemdebugSettitle(const char *zTitle){
  int n = strlen(zTitle) + 1;
  enterMem();
  if( n>=sizeof(mem.zTitle) ) n = sizeof(mem.zTitle)-1;
  memcpy(mem.zTitle, zTitle, n);
  mem.zTitle[n] = 0;
  mem.nTitle = (n+7)&~7;
  sqlite3_mutex_leave(mem.mutex);
}

void sqlite3MemdebugSync(){
  struct MemBlockHdr *pHdr;
  for(pHdr=mem.pFirst; pHdr; pHdr=pHdr->pNext){
    void **pBt = (void**)pHdr;

    fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
                    zFilename);
    return;
  }
  for(pHdr=mem.pFirst; pHdr; pHdr=pHdr->pNext){
    char *z = (char*)pHdr;
    z -= pHdr->nBacktraceSlots*sizeof(void*) + pHdr->nTitle;
    fprintf(out, "**** %lld bytes at %p from %s ****\n", 
            pHdr->iSize, &pHdr[1], pHdr->nTitle ? z : "???");
    if( pHdr->nBacktrace ){
      fflush(out);
      pBt = (void**)pHdr;
      pBt -= pHdr->nBacktraceSlots;
      backtrace_symbols_fd(pBt, pHdr->nBacktrace, fileno(out));
      fprintf(out, "\n");

** and store the result in pMem.  Return the number of bytes read.
*/ 
int sqlite3VdbeSerialGet(
  const unsigned char *buf,     /* Buffer to deserialize from */
  u32 serial_type,              /* Serial type to deserialize */
  Mem *pMem                     /* Memory cell to write value into */
){
#ifndef SQLITE_MEMORY_SIZE
  assert( (7&(int)pMem)==0 );   /* Verify 8-byte alignment.  Ticket #3040 */
#endif
  switch( serial_type ){
    case 10:   /* Reserved for future use */
    case 11:   /* Reserved for future use */
    case 0: {  /* NULL */
      pMem->flags = MEM_Null;
      break;
    }

  const unsigned char *aKey = (const unsigned char *)pKey;
  UnpackedRecord *p;
  int nByte;
  int i, idx, d;
  u32 szHdr;
  Mem *pMem;
  
  assert( sizeof(Mem)>sizeof(*p) );
  nByte = sizeof(Mem)*(pKeyInfo->nField+2);
  if( nByte>szSpace ){
    p = sqlite3DbMallocRaw(pKeyInfo->db, nByte);
    if( p==0 ) return 0;
    p->needFree = 1;
  }else{
    p = pSpace;
    p->needFree = 0;
  }
  p->pKeyInfo = pKeyInfo;
  p->nField = pKeyInfo->nField + 1;
  p->needDestroy = 1;
  p->aMem = pMem = &((Mem*)p)[1];
  idx = GetVarint(aKey, szHdr);
  d = szHdr;
  i = 0;
  while( idx<szHdr && i<p->nField ){
    u32 serial_type;

    idx += GetVarint( aKey+idx, serial_type);