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/*
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** 2007 August 14
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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*************************************************************************
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**
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** This file contains low-level memory allocation drivers for when
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** SQLite will use the standard C-library malloc/realloc/free interface
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** to obtain the memory it needs.
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**
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** This file contains implementations of the low-level memory allocation
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** routines specified in the sqlite3_mem_methods object.
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**
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** $Id: mem1.c,v 1.25 2008/07/25 08:49:00 danielk1977 Exp $
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*/
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#include "sqliteInt.h"
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/*
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** This version of the memory allocator is the default. It is
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** used when no other memory allocator is specified using compile-time
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** macros.
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*/
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#ifdef SQLITE_SYSTEM_MALLOC
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/*
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** Like malloc(), but remember the size of the allocation
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** so that we can find it later using sqlite3MemSize().
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**
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** For this low-level routine, we are guaranteed that nByte>0 because
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** cases of nByte<=0 will be intercepted and dealt with by higher level
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** routines.
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*/
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static void *sqlite3MemMalloc(int nByte){
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sqlite3_int64 *p;
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assert( nByte>0 );
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nByte = (nByte+7)&~7;
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p = malloc( nByte+8 );
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if( p ){
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p[0] = nByte;
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p++;
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}
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return (void *)p;
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}
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/*
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** Like free() but works for allocations obtained from sqlite3MemMalloc()
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** or sqlite3MemRealloc().
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**
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** For this low-level routine, we already know that pPrior!=0 since
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** cases where pPrior==0 will have been intecepted and dealt with
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** by higher-level routines.
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*/
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static void sqlite3MemFree(void *pPrior){
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sqlite3_int64 *p = (sqlite3_int64*)pPrior;
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assert( pPrior!=0 );
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p--;
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free(p);
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}
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/*
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** Like realloc(). Resize an allocation previously obtained from
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** sqlite3MemMalloc().
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**
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** For this low-level interface, we know that pPrior!=0. Cases where
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** pPrior==0 while have been intercepted by higher-level routine and
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** redirected to xMalloc. Similarly, we know that nByte>0 becauses
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** cases where nByte<=0 will have been intercepted by higher-level
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** routines and redirected to xFree.
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*/
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static void *sqlite3MemRealloc(void *pPrior, int nByte){
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sqlite3_int64 *p = (sqlite3_int64*)pPrior;
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assert( pPrior!=0 && nByte>0 );
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nByte = (nByte+7)&~7;
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p = (sqlite3_int64*)pPrior;
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p--;
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p = realloc(p, nByte+8 );
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if( p ){
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p[0] = nByte;
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p++;
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}
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return (void*)p;
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}
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/*
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** Report the allocated size of a prior return from xMalloc()
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** or xRealloc().
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*/
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static int sqlite3MemSize(void *pPrior){
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sqlite3_int64 *p;
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if( pPrior==0 ) return 0;
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p = (sqlite3_int64*)pPrior;
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p--;
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return p[0];
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}
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/*
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** Round up a request size to the next valid allocation size.
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*/
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static int sqlite3MemRoundup(int n){
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return (n+7) & ~7;
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}
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/*
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** Initialize this module.
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*/
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static int sqlite3MemInit(void *NotUsed){
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return SQLITE_OK;
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}
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/*
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** Deinitialize this module.
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*/
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static void sqlite3MemShutdown(void *NotUsed){
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return;
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}
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const sqlite3_mem_methods *sqlite3MemGetDefault(void){
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static const sqlite3_mem_methods defaultMethods = {
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sqlite3MemMalloc,
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sqlite3MemFree,
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sqlite3MemRealloc,
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sqlite3MemSize,
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sqlite3MemRoundup,
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sqlite3MemInit,
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sqlite3MemShutdown,
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0
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};
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return &defaultMethods;
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}
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/*
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** This routine is the only routine in this file with external linkage.
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**
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** Populate the low-level memory allocation function pointers in
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** sqlite3Config.m with pointers to the routines in this file.
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*/
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void sqlite3MemSetDefault(void){
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sqlite3_config(SQLITE_CONFIG_MALLOC, sqlite3MemGetDefault());
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}
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#endif /* SQLITE_SYSTEM_MALLOC */
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