Subject: [PATCH]  Do not allow CREATE TABLE or CREATE VIEW of an object with a name
 that looks like a shadow table name.

diff --git a/src/build.c b/src/build.c
index 3412670..f273394 100644
--- a/src/build.c
+++ b/src/build.c
@@ -814,6 +814,22 @@ int sqlite3WritableSchema(sqlite3 *db){
   return (db->flags&(SQLITE_WriteSchema|SQLITE_Defensive))==SQLITE_WriteSchema;
 }
 
+/*
+** Return TRUE if shadow tables should be read-only in the current
+** context.
+*/
+int sqlite3ReadOnlyShadowTables(sqlite3 *db){
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( (db->flags & SQLITE_Defensive)!=0
+   && db->pVtabCtx==0
+   && db->nVdbeExec==0
+  ){
+    return 1;
+  }
+#endif
+  return 0;
+}
+
 /*
 ** This routine is used to check if the UTF-8 string zName is a legal
 ** unqualified name for a new schema object (table, index, view or
@@ -822,9 +838,10 @@ int sqlite3WritableSchema(sqlite3 *db){
 ** is reserved for internal use.
 */
 int sqlite3CheckObjectName(Parse *pParse, const char *zName){
-  if( !pParse->db->init.busy && pParse->nested==0 
+  if(( !pParse->db->init.busy && pParse->nested==0 
           && sqlite3WritableSchema(pParse->db)==0
-          && 0==sqlite3StrNICmp(zName, "sqlite_", 7) ){
+          && 0==sqlite3StrNICmp(zName, "sqlite_", 7) ) ||
+          (sqlite3ReadOnlyShadowTables(pParse->db) && sqlite3ShadowTableName(pParse->db, zName))){
     sqlite3ErrorMsg(pParse, "object name reserved for internal use: %s", zName);
     return SQLITE_ERROR;
   }
@@ -1929,7 +1946,7 @@ int sqlite3IsShadowTableOf(sqlite3 *db, Table *pTab, const char *zName){
 ** zName is temporarily modified while this routine is running, but is
 ** restored to its original value prior to this routine returning.
 */
-static int isShadowTableName(sqlite3 *db, char *zName){
+int sqlite3ShadowTableName(sqlite3 *db, const char *zName){
   char *zTail;                  /* Pointer to the last "_" in zName */
   Table *pTab;                  /* Table that zName is a shadow of */
 
@@ -1942,8 +1959,6 @@ static int isShadowTableName(sqlite3 *db, char *zName){
   if( !IsVirtual(pTab) ) return 0;
   return sqlite3IsShadowTableOf(db, pTab, zName);
 }
-#else
-# define isShadowTableName(x,y) 0
 #endif /* ifndef SQLITE_OMIT_VIRTUALTABLE */
 
 /*
@@ -1985,7 +2000,7 @@ void sqlite3EndTable(
   p = pParse->pNewTable;
   if( p==0 ) return;
 
-  if( pSelect==0 && isShadowTableName(db, p->zName) ){
+  if( pSelect==0 && sqlite3ShadowTableName(db, p->zName) ){
     p->tabFlags |= TF_Shadow;
   }
 
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 60b2ebd..e5ba8a0 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -4408,6 +4408,11 @@ void sqlite3AutoLoadExtensions(sqlite3*);
    );
 #  define sqlite3VtabInSync(db) ((db)->nVTrans>0 && (db)->aVTrans==0)
 #endif
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  int sqlite3ShadowTableName(sqlite3 *db, const char *zName);
+#else
+# define sqlite3ShadowTableName(A,B) 0
+#endif
 #ifndef SQLITE_OMIT_VIRTUALTABLE
   int sqlite3IsShadowTableOf(sqlite3*,Table*,const char*);
 #else
diff --git a/test/altertab.test b/test/altertab.test
index 891b081..0705abc 100644
--- a/test/altertab.test
+++ b/test/altertab.test
@@ -547,13 +547,29 @@ ifcapable fts3 {
   } {1 {table y1_segments may not be modified}}
 
   do_catchsql_test 16.20 {
-    ALTER TABLE y1_segments RENAME TO abc;
-  } {1 {table y1_segments may not be altered}}
-
-  do_catchsql_test 16.21 {
     DROP TABLE y1_segments;
   } {1 {table y1_segments may not be dropped}}
 
+  do_catchsql_test 16.20 {
+    ALTER TABLE y1_segments RENAME TO abc;
+  } {1 {table y1_segments may not be altered}}
+  sqlite3_db_config db DEFENSIVE 0
+  do_catchsql_test 16.22 {
+    ALTER TABLE y1_segments RENAME TO abc;
+  } {0 {}}
+  sqlite3_db_config db DEFENSIVE 1
+  do_catchsql_test 16.23 {
+    CREATE TABLE y1_segments AS SELECT * FROM abc;
+  } {1 {object name reserved for internal use: y1_segments}}
+  do_catchsql_test 16.24 {
+    CREATE VIEW y1_segments AS SELECT * FROM abc;
+  } {1 {object name reserved for internal use: y1_segments}}
+  sqlite3_db_config db DEFENSIVE 0
+  do_catchsql_test 16.25 {
+    ALTER TABLE abc RENAME TO y1_segments;
+  } {0 {}}
+  sqlite3_db_config db DEFENSIVE 1
+
   do_execsql_test 16.30 {
     ALTER TABLE y1 RENAME TO z1;
   }