Only allow shadow table to be written from within a recursive SQL call.

Omit the SQLITE_PREPARE_SHADOW flag.  Some tests are failing because the
tests depend on being able to write to shadow tables.

FossilOrigin-Name: d890c6582524677666e6f5b5817331dec332ade16b2f744cbb8a3c7dd9b63e21

4 files changed, 4 insertions, 16 deletions

diff --git a/src/delete.c b/src/delete.c
index c015eb43e..932520382 100644
--- a/src/delete.c
+++ b/src/delete.c
@@ -57,8 +57,9 @@ int sqlite3IsReadOnly(Parse *pParse, Table *pTab, int viewOk){
   **   2) It is a system table (i.e. sqlite_master), this call is not
   **      part of a nested parse and writable_schema pragma has not 
   **      been specified.
-  **   3) The table is a shadow table and the SQLITE_PREPARE_SHADOW flag
-  **      is omitted.
+  **   3) The table is a shadow table and the current sqlite3_prepare()
+  **      is for a top-level SQL statement, not a nested SQL statement
+  **      issued by a virtual table implementation.
   **
   ** In either case leave an error message in pParse and return non-zero.
   */
@@ -68,7 +69,7 @@ int sqlite3IsReadOnly(Parse *pParse, Table *pTab, int viewOk){
      && sqlite3WritableSchema(pParse->db)==0
      && pParse->nested==0)
    || ( (pTab->tabFlags & TF_Shadow)!=0
-     && pParse->writeShadow==0)
+     && pParse->db->nVdbeExec==0)
   ){
     sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName);
     return 1;
diff --git a/src/prepare.c b/src/prepare.c
index a6accbc7d..4d33f0b1e 100644
--- a/src/prepare.c
+++ b/src/prepare.c
@@ -545,9 +545,6 @@ static int sqlite3Prepare(
     sParse.disableLookaside++;
     db->lookaside.bDisable++;
   }
-  if( prepFlags & SQLITE_PREPARE_SHADOW ){
-    sParse.writeShadow = 1;
-  }
 
   /* Check to verify that it is possible to get a read lock on all
   ** database schemas.  The inability to get a read lock indicates that
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index 02963f454..88476836c 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -3642,19 +3642,10 @@ int sqlite3_limit(sqlite3*, int id, int newVal);
 ** normalize a SQL statement are unspecified and subject to change.
 ** At a minimum, literal values will be replaced with suitable
 ** placeholders.
-**
-** [[SQLITE_PREPARE_SHADOW]] ^(<dt>SQLITE_PREPARE_SHADOW</dt>
-** <dd>When the SQLITE_PREPARE_SHADOW flag is set, writes to shadow
-** tables are allowed.  Shadow tables are ordinary tables associated
-** with some virtual tables that serve as the storage for the virtual
-** table.  Shadow tables are normally read-only.  Virtual table
-** implementations use this flag so that they can write to their own
-** shadow tables.
 ** </dl>
 */
 #define SQLITE_PREPARE_PERSISTENT              0x01
 #define SQLITE_PREPARE_NORMALIZE               0x02
-#define SQLITE_PREPARE_SHADOW                  0x04
 
 /*
 ** CAPI3REF: Compiling An SQL Statement
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 77f101183..053ac01dc 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3086,7 +3086,6 @@ struct Parse {
   u8 eTriggerOp;       /* TK_UPDATE, TK_INSERT or TK_DELETE */
   u8 eOrconf;          /* Default ON CONFLICT policy for trigger steps */
   u8 disableTriggers;  /* True to disable triggers */
-  u8 writeShadow;      /* True if shadow tables are writable */
 
   /**************************************************************************
   ** Fields above must be initialized to zero.  The fields that follow,