Change the definition of SQLITE_CONFIG_PAGECACHE and

SQLITE_CONFIG_SCRATCH to omit the magic "+4" in the buffer size
calculation. (CVS 5512)

FossilOrigin-Name: e7ed0fe640a39053009eac52a7f055b121750e57

1 files changed, 8 insertions, 2 deletions

diff --git a/src/malloc.c b/src/malloc.c
index c7b2e650f..a68378a0f 100644
--- a/src/malloc.c
+++ b/src/malloc.c
@@ -12,7 +12,7 @@
 **
 ** Memory allocation functions used throughout sqlite.
 **
-** $Id: malloc.c,v 1.31 2008/07/29 14:29:07 drh Exp $
+** $Id: malloc.c,v 1.32 2008/07/31 17:16:05 drh Exp $
 */
 #include "sqliteInt.h"
 #include <stdarg.h>
@@ -115,6 +115,7 @@ int sqlite3MallocInit(void){
   if( sqlite3Config.pScratch && sqlite3Config.szScratch>=3000
       && sqlite3Config.nScratch>0 ){
     int i;
+    sqlite3Config.szScratch -= 4;
     mem0.aScratchFree = (u32*)&((char*)sqlite3Config.pScratch)
                   [sqlite3Config.szScratch*sqlite3Config.nScratch];
     for(i=0; i<sqlite3Config.nScratch; i++){ mem0.aScratchFree[i] = i; }
@@ -124,8 +125,13 @@ int sqlite3MallocInit(void){
     sqlite3Config.szScratch = 0;
   }
   if( sqlite3Config.pPage && sqlite3Config.szPage>=512
-      && sqlite3Config.nPage>0 ){
+      && sqlite3Config.nPage>1 ){
     int i;
+    int overhead;
+    int sz = sqlite3Config.szPage;
+    int n = sqlite3Config.nPage;
+    overhead = (4*n + sz - 1)/sz;
+    sqlite3Config.nPage -= overhead;
     mem0.aPageFree = (u32*)&((char*)sqlite3Config.pPage)
                   [sqlite3Config.szPage*sqlite3Config.nPage];
     for(i=0; i<sqlite3Config.nPage; i++){ mem0.aPageFree[i] = i; }