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 1.356 2007/04/19 00:24:34 drh Exp $
** $Id: btree.c,v 1.357 2007/04/24 17:27:51 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.

  */
  rc = SQLITE_NOTADB;
  if( sqlite3PagerPagecount(pBt->pPager)>0 ){
    u8 *page1 = pPage1->aData;
    if( memcmp(page1, zMagicHeader, 16)!=0 ){
      goto page1_init_failed;
    }
    if( page1[18]>1 || page1[19]>1 ){
    if( page1[18]>1 ){
      pBt->readOnly = 1;
    }
    if( page1[19]>1 ){
      goto page1_init_failed;
    }
    pageSize = get2byte(&page1[16]);
    if( ((pageSize-1)&pageSize)!=0 || pageSize<512 ){
      goto page1_init_failed;
    }
    assert( (pageSize & 7)==0 );

    return SQLITE_BUSY;
  }

  do {
    if( pBt->pPage1==0 ){
      rc = lockBtree(pBt);
    }
  

    if( rc==SQLITE_OK && wrflag ){
      if( pBt->readOnly ){
        rc = SQLITE_READONLY;
      }else{
      rc = sqlite3PagerBegin(pBt->pPage1->pDbPage, wrflag>1);
      if( rc==SQLITE_OK ){
        rc = newDatabase(pBt);
        rc = sqlite3PagerBegin(pBt->pPage1->pDbPage, wrflag>1);
        if( rc==SQLITE_OK ){
          rc = newDatabase(pBt);
        }
      }
    }
  
    if( rc==SQLITE_OK ){
      if( wrflag ) pBt->inStmt = 0;
    }else{
      unlockBtreeIfUnused(pBt);

# 2007 April 24
#
# 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.
#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests to make sure SQLite treats a database
# as readonly if its write version is set to  high.
#
# $Id: rdonly.test,v 1.1 2007/04/24 17:27:52 drh Exp $

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


# Create a database.
#
do_test rdonly-1.1 {
  execsql {
    CREATE TABLE t1(x);
    INSERT INTO t1 VALUES(1);
    SELECT * FROM t1;
  }
} {1}

# Changes the write version from 1 to 2.  Verify that the database
# can be read but not written.
#
do_test rdonly-1.2 {
  db close
  hexio_get_int [hexio_read test.db 18 1]
} 1
do_test rdonly-1.3 {
  hexio_write test.db 18 02
  sqlite3 db test.db
  execsql {
    SELECT * FROM t1;
  }
} {1}
do_test rdonly-1.4 {
  catchsql {
    INSERT INTO t1 VALUES(2)
  }
} {1 {attempt to write a readonly database}}

# Change the write version back to 1.  Verify that the database
# is read-write again.
#
do_test rdonly-1.5 {
  db close
  hexio_write test.db 18 01
  sqlite3 db test.db
  catchsql {
    INSERT INTO t1 VALUES(2);
    SELECT * FROM t1;
  }
} {0 {1 2}}

finish_test