Index: src/btree.c
==================================================================
--- src/btree.c
+++ src/btree.c
@@ -7,11 +7,11 @@
 **    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:
@@ -1868,11 +1868,14 @@
   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;
@@ -2066,15 +2069,19 @@
 
   do {
     if( pBt->pPage1==0 ){
       rc = lockBtree(pBt);
     }
-  
+
     if( rc==SQLITE_OK && wrflag ){
-      rc = sqlite3PagerBegin(pBt->pPage1->pDbPage, wrflag>1);
-      if( rc==SQLITE_OK ){
-        rc = newDatabase(pBt);
+      if( pBt->readOnly ){
+        rc = SQLITE_READONLY;
+      }else{
+        rc = sqlite3PagerBegin(pBt->pPage1->pDbPage, wrflag>1);
+        if( rc==SQLITE_OK ){
+          rc = newDatabase(pBt);
+        }
       }
     }
   
     if( rc==SQLITE_OK ){
       if( wrflag ) pBt->inStmt = 0;

ADDED   test/rdonly.test
Index: test/rdonly.test
==================================================================
--- test/rdonly.test
+++ test/rdonly.test
@@ -0,0 +1,65 @@
+# 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