SQLite

**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.182 2006/01/23 15:39:59 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <stdarg.h>
#include <ctype.h>

/*

** Size reserved for storing the user string. Each time a Malloc() or Realloc()
** call succeeds, up to TESTALLOC_USERSIZE bytes of the string pointed to by
** sqlite3_malloc_id are stored along with the other test system metadata.
*/
#define TESTALLOC_USERSIZE 64
const char *sqlite3_malloc_id = 0;








/*
** Blocks used by the test layer have the following format:
**
**        <sizeof(void *) pNext pointer>
**        <sizeof(void *) pPrev pointer>
**        <TESTALLOC_NGUARD 32-bit guard words>
**            <The application level allocation>

#if defined(TCLSH) && defined(SQLITE_DEBUG) && SQLITE_MEMDEBUG>1
#include <tcl.h>
int sqlite3OutstandingMallocs(Tcl_Interp *interp){
  void *p;
  Tcl_Obj *pRes = Tcl_NewObj();
  Tcl_IncrRefCount(pRes);


  for(p=sqlite3_pFirst; p; p=((void **)p)[1]){
    Tcl_Obj *pEntry = Tcl_NewObj();
    Tcl_Obj *pStack = Tcl_NewObj();
    char *z;
    u32 iLine;
    int nBytes = sqlite3OsAllocationSize(p) - TESTALLOC_OVERHEAD;
    char *zAlloc = (char *)p;

*/
static void * OSMALLOC(int n){
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  sqlite3_nMaxAlloc = 
      MAX(sqlite3_nMaxAlloc, sqlite3ThreadDataReadOnly()->nAlloc);
#endif
  assert( !sqlite3_mallocDisallowed );

  if( !sqlite3TestMallocFail() ){
    u32 *p;
    p = (u32 *)sqlite3OsMalloc(n + TESTALLOC_OVERHEAD);
    assert(p);
    sqlite3_nMalloc++;
    applyGuards(p);
    linkAlloc(p);

** This is the test layer's wrapper around sqlite3OsRealloc().
*/
static void * OSREALLOC(void *pRealloc, int n){
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  sqlite3_nMaxAlloc = 
      MAX(sqlite3_nMaxAlloc, sqlite3ThreadDataReadOnly()->nAlloc);
#endif

  assert( !sqlite3_mallocDisallowed );
  if( !sqlite3TestMallocFail() ){


    u32 *p = (u32 *)getOsPointer(pRealloc);
    checkGuards(p);

    p = sqlite3OsRealloc(p, n + TESTALLOC_OVERHEAD);
    applyGuards(p);
    relinkAlloc(p);
    return (void *)(&p[TESTALLOC_NGUARD + 2*sizeof(void *)/sizeof(u32)]);
  }
  return 0;
}

/*
** Allocate and return N bytes of uninitialised memory by calling
** sqlite3OsMalloc(). If the Malloc() call fails, attempt to free memory 
** by calling sqlite3_release_memory().
*/
void *sqlite3MallocRaw(int n){
  void *p = 0;
  if( n>0 && !sqlite3MallocFailed() && !handleSoftLimit(n) ){
    while( (p = OSMALLOC(n))==0 && sqlite3_release_memory(n) );
    if( !p ){
      /* If the allocation failed, call handleSoftLimit() again, this time
      ** with the additive inverse of the argument passed to 
      ** handleSoftLimit() above. This is so the ThreadData.nAlloc variable is
      ** still correct after a malloc() failure. 
      */
      (void)handleSoftLimit(n * -1);

      sqlite3FailedMalloc();
      OSMALLOC_FAILED();
    }
  }
  return p;
}

/*
** Resize the allocation at p to n bytes by calling sqlite3OsRealloc(). The
** pointer to the new allocation is returned.  If the Realloc() call fails,
** attempt to free memory by calling sqlite3_release_memory().
*/
void *sqlite3Realloc(void *p, int n){

  if( sqlite3MallocFailed() ){
    return 0;
  }

  if( !p ){
    return sqlite3Malloc(n);
  }else{
    void *np = 0;
    if( !handleSoftLimit(n - OSSIZEOF(p)) ){

      while( (np = OSREALLOC(p, n))==0 && sqlite3_release_memory(n) );
      if( !np ){
        /* If the allocation failed, call handleSoftLimit() again, this time
        ** with the additive inverse of the argument passed to 
        ** handleSoftLimit() above. This is so the ThreadData.nAlloc variable is
        ** still correct after a malloc() failure. 
        */
        (void)handleSoftLimit(OSSIZEOF(p) - n);

        sqlite3FailedMalloc();
        OSMALLOC_FAILED();
      }
    }
    return np;
  }
}

/*
** Free the memory pointed to by p. p must be either a NULL pointer or a 
** value returned by a previous call to sqlite3Malloc() or sqlite3Realloc().
*/
void sqlite3FreeX(void *p){