SQLite

/*
** 2004 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.286 2006/01/09 05:36:27 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.

  int maxLeaf;          /* Maximum local payload in a LEAFDATA table */
  int minLeaf;          /* Minimum local payload in a LEAFDATA table */
  BusyHandler *pBusyHandler;   /* Callback for when there is lock contention */
  u8 inTransaction;     /* Transaction state */
  BtShared *pNext;      /* Next in SqliteTsd.pBtree linked list */
  int nRef;             /* Number of references to this structure */
  int nTransaction;     /* Number of open transactions (read + write) */

  void *pSchema;        /* Pointer to space allocated by sqlite3BtreeSchema() */
  void (*xFreeSchema)(void*);  /* Destructor for BtShared.pSchema */
#ifndef SQLITE_OMIT_SHARED_CACHE
  BtLock *pLock;        /* List of locks held on this shared-btree struct */
#endif
};

/*
** An instance of the following structure is used to hold information
** about a cell.  The parseCellPtr() function fills in this structure
** based on information extract from the raw disk page.
*/

** Move the cursor to the root page
*/
static int moveToRoot(BtCursor *pCur){
  MemPage *pRoot;
  int rc;
  BtShared *pBt = pCur->pBtree->pBt;

  if( 
    SQLITE_OK!=(rc = restoreCursorPosition(pCur, 0)) ||
    SQLITE_OK!=(rc = getAndInitPage(pBt, pCur->pgnoRoot, &pRoot, 0))
  ){
    pCur->eState = CURSOR_INVALID;
    return rc;
  }
  releasePage(pCur->pPage);
  pageIntegrity(pRoot);
  pCur->pPage = pRoot;
  pCur->idx = 0;

    return SQLITE_PERM;   /* Cursor not open for writing */
  }
  if( checkReadLocks(pBt, pCur->pgnoRoot, pCur) ){
    return SQLITE_LOCKED; /* The table pCur points to has a read lock */
  }

  /* Save the positions of any other cursors open on this table */
  if( 
    SQLITE_OK!=(rc = restoreCursorPosition(pCur, 0)) ||
    SQLITE_OK!=(rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur)) ||
    SQLITE_OK!=(rc = sqlite3BtreeMoveto(pCur, pKey, nKey, &loc))
  ){
    return rc;
  }



  pPage = pCur->pPage;
  assert( pPage->intKey || nKey>=0 );
  assert( pPage->leaf || !pPage->leafData );
  TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
          pCur->pgnoRoot, nKey, nData, pPage->pgno,
          loc==0 ? "overwrite" : "new entry"));
  assert( pPage->isInit );

** handle holds an exclusive lock on the sqlite_master table.
*/
int sqlite3BtreeSchemaLocked(Btree *p){
  return (queryTableLock(p, MASTER_ROOT, READ_LOCK)!=SQLITE_OK);
}

int sqlite3BtreeLockTable(Btree *p, int iTab, u8 isWriteLock){
  int rc = SQLITE_OK;
#ifndef SQLITE_OMIT_SHARED_CACHE
  u8 lockType = (isWriteLock?WRITE_LOCK:READ_LOCK);
  rc = queryTableLock(p, iTab, lockType);
  if( rc==SQLITE_OK ){
    rc = lockTable(p, iTab, lockType);
  }
#endif
  return rc;
}

#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Enable the shared pager and schema features.
*/

**     CREATE INDEX
**     DROP INDEX
**     creating ID lists
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**
** $Id: build.c,v 1.370 2006/01/09 05:36:27 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Initialize the pParse structure as needed.

    /* The cookie mask contains one bit for each database file open.
    ** (Bit 0 is for main, bit 1 is for temp, and so forth.)  Bits are
    ** set for each database that is used.  Generate code to start a
    ** transaction on each used database and to verify the schema cookie
    ** on each used database.
    */

    if( pParse->cookieGoto>0 ){
      u32 mask;
      int iDb;
      sqlite3VdbeJumpHere(v, pParse->cookieGoto-1);
      for(iDb=0, mask=1; iDb<db->nDb; mask<<=1, iDb++){
        if( (mask & pParse->cookieMask)==0 ) continue;
        sqlite3VdbeAddOp(v, OP_Transaction, iDb, (mask & pParse->writeMask)!=0);