SQLite

/*
** 2001 September 15
**
** 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 1.62 2002/06/06 23:16:05 drh 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.

*/
struct Btree {
  Pager *pPager;        /* The page cache */
  BtCursor *pCursor;    /* A list of all open cursors */
  PageOne *page1;       /* First page of the database */
  u8 inTrans;           /* True if a transaction is in progress */
  u8 inCkpt;            /* True if there is a checkpoint on the transaction */
  u8 readOnly;          /* True if the underlying file is readonly */
  Hash locks;           /* Key: root page number.  Data: lock count */
};
typedef Btree Bt;

/*
** A cursor is a pointer to a particular entry in the BTree.
** The entry is identified by its MemPage and the index in

    sqliteFree(pBt);
    *ppBtree = 0;
    return rc;
  }
  sqlitepager_set_destructor(pBt->pPager, pageDestructor);
  pBt->pCursor = 0;
  pBt->page1 = 0;
  pBt->readOnly = sqlitepager_isreadonly(pBt->pPager);
  sqliteHashInit(&pBt->locks, SQLITE_HASH_INT, 0);
  *ppBtree = pBt;
  return SQLITE_OK;
}

/*
** Close an open database and invalidate all cursors.

  if( pBt->inTrans ) return SQLITE_ERROR;
  if( pBt->page1==0 ){
    rc = lockBtree(pBt);
    if( rc!=SQLITE_OK ){
      return rc;
    }
  }
  if( pBt->readOnly ){
    rc = SQLITE_OK;
  }else{
    rc = sqlitepager_begin(pBt->page1);
    if( rc==SQLITE_OK ){
      rc = newDatabase(pBt);
    }
  }
  if( rc==SQLITE_OK ){
    pBt->inTrans = 1;
    pBt->inCkpt = 0;
  }else{
    unlockBtreeIfUnused(pBt);
  }
  return rc;
}

/*
** Commit the transaction currently in progress.
**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
int sqliteBtreeCommit(Btree *pBt){
  int rc;
  if( pBt->inTrans==0 ) return SQLITE_ERROR;
  rc = pBt->readOnly ? SQLITE_OK : sqlitepager_commit(pBt->pPager);
  pBt->inTrans = 0;
  pBt->inCkpt = 0;
  unlockBtreeIfUnused(pBt);
  return rc;
}

/*

  pBt->inCkpt = 0;
  for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
    if( pCur->pPage ){
      sqlitepager_unref(pCur->pPage);
      pCur->pPage = 0;
    }
  }
  rc = pBt->readOnly ? SQLITE_OK : sqlitepager_rollback(pBt->pPager);
  unlockBtreeIfUnused(pBt);
  return rc;
}

/*
** Set the checkpoint for the current transaction.  The checkpoint serves
** as a sub-transaction that can be rolled back independently of the
** main transaction.  You must start a transaction before starting a
** checkpoint.  The checkpoint is ended automatically if the transaction
** commits or rolls back.
**
** Only one checkpoint may be active at a time.  It is an error to try
** to start a new checkpoint if another checkpoint is already active.
*/
int sqliteBtreeBeginCkpt(Btree *pBt){
  int rc;
  if( !pBt->inTrans || pBt->inCkpt ){
    return SQLITE_ERROR;
  }
  rc = pBt->readOnly ? SQLITE_OK : sqlitepager_ckpt_begin(pBt->pPager);
  pBt->inCkpt = 1;
  return rc;
}


/*
** Commit a checkpoint to transaction currently in progress.  If no
** checkpoint is active, this is a no-op.
*/
int sqliteBtreeCommitCkpt(Btree *pBt){
  int rc;
  if( pBt->inCkpt && !pBt->readOnly ){
    rc = sqlitepager_ckpt_commit(pBt->pPager);
  }else{
    rc = SQLITE_OK;
  }
  pBt->inCkpt = 0;
  return rc;
}

/*
** Rollback the checkpoint to the current transaction.  If there
** is no active checkpoint or transaction, this routine is a no-op.
**
** All cursors will be invalided by this operation.  Any attempt
** to use a cursor that was open at the beginning of this operation
** will result in an error.
*/
int sqliteBtreeRollbackCkpt(Btree *pBt){
  int rc;
  BtCursor *pCur;
  if( pBt->inCkpt==0 || pBt->readOnly ) return SQLITE_OK;
  for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
    if( pCur->pPage ){
      sqlitepager_unref(pCur->pPage);
      pCur->pPage = 0;
    }
  }
  rc = sqlitepager_ckpt_rollback(pBt->pPager);

  if( pBt->page1==0 ){
    rc = lockBtree(pBt);
    if( rc!=SQLITE_OK ){
      *ppCur = 0;
      return rc;
    }
  }
  if( wrFlag && pBt->readOnly ){
    *ppCur = 0;
    return SQLITE_READONLY;
  }
  pCur = sqliteMalloc( sizeof(*pCur) );
  if( pCur==0 ){
    rc = SQLITE_NOMEM;
    goto create_cursor_exception;
  }
  pCur->pgnoRoot = (Pgno)iTable;

int sqliteBtreeCreateTable(Btree *pBt, int *piTable){
  MemPage *pRoot;
  Pgno pgnoRoot;
  int rc;
  if( !pBt->inTrans ){
    return SQLITE_ERROR;  /* Must start a transaction first */
  }
  if( pBt->readOnly ){
    return SQLITE_READONLY;
  }
  rc = allocatePage(pBt, &pRoot, &pgnoRoot);
  if( rc ) return rc;
  assert( sqlitepager_iswriteable(pRoot) );
  zeroPage(pRoot);
  sqlitepager_unref(pRoot);
  *piTable = (int)pgnoRoot;
  return SQLITE_OK;
}

/*
** Create a new BTree index.  Write into *piTable the page
** number for the root page of the new index.
**
** In the current implementation, BTree tables and BTree indices are the 
** the same.  But in the future, we may change this so that BTree tables
** are restricted to having a 4-byte integer key and arbitrary data and
** BTree indices are restricted to having an arbitrary key and no data.
*/
int sqliteBtreeCreateIndex(Btree *pBt, int *piIndex){












  return sqliteBtreeCreateTable(pBt, piIndex);
}

/*
** Erase the given database page and all its children.  Return
** the page to the freelist.
*/
static int clearDatabasePage(Btree *pBt, Pgno pgno, int freePageFlag){

*/
int sqliteBtreeClearTable(Btree *pBt, int iTable){
  int rc;
  ptr nLock;
  if( !pBt->inTrans ){
    return SQLITE_ERROR;  /* Must start a transaction first */
  }
  if( pBt->readOnly ){
    return SQLITE_READONLY;
  }
  nLock = (ptr)sqliteHashFind(&pBt->locks, 0, iTable);
  if( nLock ){
    return SQLITE_LOCKED;
  }
  rc = clearDatabasePage(pBt, (Pgno)iTable, 0);
  if( rc ){
    sqliteBtreeRollback(pBt);

*/
int sqliteBtreeDropTable(Btree *pBt, int iTable){
  int rc;
  MemPage *pPage;
  if( !pBt->inTrans ){
    return SQLITE_ERROR;  /* Must start a transaction first */
  }
  if( pBt->readOnly ){
    return SQLITE_READONLY;
  }
  rc = sqlitepager_get(pBt->pPager, (Pgno)iTable, (void**)&pPage);
  if( rc ) return rc;
  rc = sqliteBtreeClearTable(pBt, iTable);
  if( rc ) return rc;
  if( iTable>2 ){
    rc = freePage(pBt, pPage, iTable);
  }else{

*/
int sqliteBtreeUpdateMeta(Btree *pBt, int *aMeta){
  PageOne *pP1;
  int rc;
  if( !pBt->inTrans ){
    return SQLITE_ERROR;  /* Must start a transaction first */
  }
  if( pBt->readOnly ){
    return SQLITE_READONLY;
  }
  pP1 = pBt->page1;
  rc = sqlitepager_write(pP1);
  if( rc ) return rc;   
  memcpy(pP1->aMeta, &aMeta[1], sizeof(pP1->aMeta));
  return SQLITE_OK;
}

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.153 2002/06/06 23:16:06 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The following global variable is incremented every time a cursor
** moves, either by the OP_MoveTo or the OP_Next opcode.  The test

          break;
        }
        /* Fall through to ROLLBACK */
      }
      case OE_Rollback: {
        sqliteBtreeRollback(pBt);
        if( db->pBeTemp ) sqliteBtreeRollback(db->pBeTemp);

        db->flags &= ~SQLITE_InTrans;
        db->onError = OE_Default;
        break;
      }
      default: {
        if( undoTransOnError ){
          sqliteBtreeCommit(pBt);
          if( db->pBeTemp ) sqliteBtreeCommit(db->pBeTemp);

          db->flags &= ~SQLITE_InTrans;
          db->onError = OE_Default;
        }
        break;
      }
    }
    sqliteRollbackInternalChanges(db);
  }
  sqliteBtreeCommitCkpt(pBt);
  if( db->pBeTemp ) sqliteBtreeCommitCkpt(db->pBeTemp);
  assert( p->tos<pc );
  return rc;

  /* Jump to here if a malloc() fails.  It's hard to get a malloc()

#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests for temporary tables and indices.
#
# $Id: temptable.test,v 1.6 2002/06/06 23:16:06 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Create an alternative connection to the database
#
do_test temptable-1.0 {

do_test temptable-5.9 {
  execsql {
    SELECT y FROM t2 WHERE x=3
  }
} {4}

db2 close

# Test for correct operation of read-only databases
#
do_test temptable-6.1 {
  execsql {
    CREATE TABLE t8(x);
    INSERT INTO t8 VALUES('xyzzy');
    SELECT * FROM t8;
  }
} {xyzzy}
do_test temptable-6.2 {
  db close
  catch {file attributes test.db -permissions 0444}
  catch {file attributes test.db -readonly 1}
  sqlite db test.db
  execsql {
    SELECT * FROM t8;
  }
} {xyzzy}
do_test temptable-6.3 {
  catchsql {
    CREATE TABLE t9(x,y);
  }
} {1 {attempt to write a readonly database}}
do_test temptable-6.4 {
  catchsql {
    CREATE TEMP TABLE t9(x,y);
  }
} {0 {}}
do_test temptable-6.5 {
  catchsql {
    INSERT INTO t9 VALUES(1,2);
    SELECT * FROM t9;
  }
} {0 {1 2}}
do_test temptable-6.6 {
  catchsql {
    INSERT INTO t8 VALUES('hello');
    SELECT * FROM t8;
  }
} {1 {attempt to write a readonly database}}
do_test temptable-6.7 {
  catchsql {
    SELECT * FROM t8,t9;
  }
} {0 {xyzzy 1 2}}
do_test temptable-6.8 {
  db close
  sqlite db test.db
  catchsql {
    SELECT * FROM t8,t9;
  }
} {1 {no such table: t9}}

finish_test