Added untrusted PL/TclU (pltclu) language. Executes all procedures
authorJan Wieck <JanWieck@Yahoo.com>
Wed, 19 Jul 2000 11:53:02 +0000 (11:53 +0000)
committerJan Wieck <JanWieck@Yahoo.com>
Wed, 19 Jul 2000 11:53:02 +0000 (11:53 +0000)
in a non-safe interpreter, so with full OS access! Language is
restricted to be used by DB superusers.

Added "argisnull n" and "return_null" commands to gain full control
over NULL values from new FMGR capabilities.

Jan

src/bin/scripts/createlang.sh
src/pl/tcl/pltcl.c

index f2e7f60e12b6b9b82fe5b1bd637ac64775693d24..daace97a4492485b8a59811c6a7982bbd02b3610 100644 (file)
@@ -8,7 +8,7 @@
 #
 #
 # IDENTIFICATION
-#    $Header: /cvsroot/pgsql/src/bin/scripts/Attic/createlang.sh,v 1.12 2000/05/28 17:56:08 tgl Exp $
+#    $Header: /cvsroot/pgsql/src/bin/scripts/Attic/createlang.sh,v 1.13 2000/07/19 11:53:02 wieck Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -180,18 +180,29 @@ fi
 # ----------
 case "$langname" in
    plpgsql)
-                lancomp="PL/pgSQL"
+       lancomp="PL/pgSQL"
        trusted="TRUSTED "
        handler="plpgsql_call_handler"
-                ;;
+       object="plpgsql"
+       ;;
    pltcl)
        lancomp="PL/Tcl"
        trusted="TRUSTED "
-       handler="pltcl_call_handler";;
+       handler="pltcl_call_handler"
+       object="pltcl"
+       ;;
+   pltclu)
+       lancomp="PL/Tcl (untrusted)"
+       trusted=""
+       handler="pltclu_call_handler"
+       object="pltcl"
+       ;;
    plperl)
        lancomp="PL/Perl"
        trusted="TRUSTED "
-       handler="plperl_call_handler";;
+       handler="plperl_call_handler"
+       object="plperl"
+       ;;
    *)
        echo "$CMDNAME: unsupported language '$langname'"
        echo "Supported languages are 'plpgsql', 'pltcl', and 'plperl'."
@@ -204,7 +215,7 @@ esac
 # Check that the shared object for the call handler is installed
 # in PGLIB
 # ----------
-if [ ! -f $PGLIB/${langname}__DLSUFFIX__ ]; then
+if [ ! -f $PGLIB/${object}__DLSUFFIX__ ]; then
    echo "$CMDNAME: cannot find the file $PGLIB/${langname}__DLSUFFIX__"
         echo ""
    echo "This file contains the call handler for $lancomp. By default,"
@@ -244,7 +255,7 @@ fi
 # ----------
 # Create the call handler and the language
 # ----------
-$PSQL "CREATE FUNCTION $handler () RETURNS OPAQUE AS '$PGLIB/${langname}__DLSUFFIX__' LANGUAGE 'newC'"
+$PSQL "CREATE FUNCTION $handler () RETURNS OPAQUE AS '$PGLIB/${object}__DLSUFFIX__' LANGUAGE 'newC'"
 if [ $? -ne 0 ]; then
    echo "$CMDNAME: language installation failed"
    exit 1
index 6bdeec9be81cfe14c9490a69e9dbb798b420fe1b..0c2ec992b7b6a0ebc309bdce396f1e13bee6e16c 100644 (file)
@@ -1,6 +1,6 @@
 /**********************************************************************
  * pltcl.c     - PostgreSQL support for Tcl as
- *           procedural language (PL)
+ *               procedural language (PL)
  *
  *   This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -31,7 +31,7 @@
  *   ENHANCEMENTS, OR MODIFICATIONS.
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/pl/tcl/pltcl.c,v 1.27 2000/07/05 23:12:03 tgl Exp $
+ *   $Header: /cvsroot/pgsql/src/pl/tcl/pltcl.c,v 1.28 2000/07/19 11:53:02 wieck Exp $
  *
  **********************************************************************/
 
@@ -54,6 +54,7 @@
 #include "tcop/tcopprot.h"
 #include "utils/syscache.h"
 #include "catalog/pg_proc.h"
+#include "catalog/pg_language.h"
 #include "catalog/pg_type.h"
 
 
@@ -63,6 +64,7 @@
 typedef struct pltcl_proc_desc
 {
    char       *proname;
+   bool        lanpltrusted;
    FmgrInfo    result_in_func;
    Oid         result_in_elem;
    int         nargs;
@@ -96,22 +98,26 @@ static int  pltcl_firstcall = 1;
 static int pltcl_call_level = 0;
 static int pltcl_restart_in_progress = 0;
 static Tcl_Interp *pltcl_hold_interp = NULL;
+static Tcl_Interp *pltcl_norm_interp = NULL;
 static Tcl_Interp *pltcl_safe_interp = NULL;
 static Tcl_HashTable *pltcl_proc_hash = NULL;
-static Tcl_HashTable *pltcl_query_hash = NULL;
+static Tcl_HashTable *pltcl_norm_query_hash = NULL;
+static Tcl_HashTable *pltcl_safe_query_hash = NULL;
+static FunctionCallInfo pltcl_actual_fcinfo = NULL;
 
 /**********************************************************************
  * Forward declarations
  **********************************************************************/
 static void pltcl_init_all(void);
-static void pltcl_init_safe_interp(void);
+static void pltcl_init_interp(Tcl_Interp *interp);
 
 #ifdef PLTCL_UNKNOWN_SUPPORT
-static void pltcl_init_load_unknown(void);
+static void pltcl_init_load_unknown(Tcl_Interp *interp);
 
 #endif  /* PLTCL_UNKNOWN_SUPPORT */
 
 Datum pltcl_call_handler(PG_FUNCTION_ARGS);
+Datum pltclu_call_handler(PG_FUNCTION_ARGS);
 
 static Datum pltcl_func_handler(PG_FUNCTION_ARGS);
 
@@ -121,6 +127,10 @@ static int pltcl_elog(ClientData cdata, Tcl_Interp *interp,
           int argc, char *argv[]);
 static int pltcl_quote(ClientData cdata, Tcl_Interp *interp,
            int argc, char *argv[]);
+static int pltcl_argisnull(ClientData cdata, Tcl_Interp *interp,
+           int argc, char *argv[]);
+static int pltcl_returnnull(ClientData cdata, Tcl_Interp *interp,
+           int argc, char *argv[]);
 
 static int pltcl_SPI_exec(ClientData cdata, Tcl_Interp *interp,
               int argc, char *argv[]);
@@ -155,64 +165,40 @@ pltcl_init_all(void)
     * Create the dummy hold interpreter to prevent close of
     * stdout and stderr on DeleteInterp
     ************************************************************/
-   if (pltcl_hold_interp == NULL)
-   {
-       if ((pltcl_hold_interp = Tcl_CreateInterp()) == NULL)
-       {
-           elog(ERROR, "pltcl: internal error - cannot create 'hold' "
-                "interpreter");
-       }
-   }
-
-   /************************************************************
-    * Destroy the existing safe interpreter
-    ************************************************************/
-   if (pltcl_safe_interp != NULL)
+   if ((pltcl_hold_interp = Tcl_CreateInterp()) == NULL)
    {
-       Tcl_DeleteInterp(pltcl_safe_interp);
-       pltcl_safe_interp = NULL;
+       elog(ERROR, "pltcl: internal error - cannot create 'hold' "
+            "interpreter");
    }
 
    /************************************************************
-    * Free the proc hash table
+    * Create the two interpreters
     ************************************************************/
-   if (pltcl_proc_hash != NULL)
+   if ((pltcl_norm_interp =
+        Tcl_CreateSlave(pltcl_hold_interp, "norm", 0)) == NULL)
    {
-       hashent = Tcl_FirstHashEntry(pltcl_proc_hash, &hashsearch);
-       while (hashent != NULL)
-       {
-           prodesc = (pltcl_proc_desc *) Tcl_GetHashValue(hashent);
-           free(prodesc->proname);
-           free(prodesc);
-           hashent = Tcl_NextHashEntry(&hashsearch);
-       }
-       Tcl_DeleteHashTable(pltcl_proc_hash);
-       free(pltcl_proc_hash);
-       pltcl_proc_hash = NULL;
+       elog(ERROR,
+            "pltcl: internal error - cannot create 'normal' interpreter");
    }
+   pltcl_init_interp(pltcl_norm_interp);
 
-   /************************************************************
-    * Free the prepared query hash table
-    ************************************************************/
-   if (pltcl_query_hash != NULL)
+   if ((pltcl_safe_interp =
+        Tcl_CreateSlave(pltcl_hold_interp, "safe", 1)) == NULL)
    {
-       hashent = Tcl_FirstHashEntry(pltcl_query_hash, &hashsearch);
-       while (hashent != NULL)
-       {
-           querydesc = (pltcl_query_desc *) Tcl_GetHashValue(hashent);
-           free(querydesc->argtypes);
-           free(querydesc);
-           hashent = Tcl_NextHashEntry(&hashsearch);
-       }
-       Tcl_DeleteHashTable(pltcl_query_hash);
-       free(pltcl_query_hash);
-       pltcl_query_hash = NULL;
+       elog(ERROR,
+            "pltcl: internal error - cannot create 'safe' interpreter");
    }
+   pltcl_init_interp(pltcl_safe_interp);
 
    /************************************************************
-    * Now recreate a new safe interpreter
+    * Initialize the proc and query hash tables
     ************************************************************/
-   pltcl_init_safe_interp();
+   pltcl_proc_hash = (Tcl_HashTable *) malloc(sizeof(Tcl_HashTable));
+   pltcl_norm_query_hash = (Tcl_HashTable *) malloc(sizeof(Tcl_HashTable));
+   pltcl_safe_query_hash = (Tcl_HashTable *) malloc(sizeof(Tcl_HashTable));
+   Tcl_InitHashTable(pltcl_proc_hash, TCL_STRING_KEYS);
+   Tcl_InitHashTable(pltcl_norm_query_hash, TCL_STRING_KEYS);
+   Tcl_InitHashTable(pltcl_safe_query_hash, TCL_STRING_KEYS);
 
    pltcl_firstcall = 0;
    return;
@@ -220,52 +206,28 @@ pltcl_init_all(void)
 
 
 /**********************************************************************
- * pltcl_init_safe_interp() - Create the safe Tcl interpreter
+ * pltcl_init_interp() - initialize a Tcl interpreter
  **********************************************************************/
 static void
-pltcl_init_safe_interp(void)
+pltcl_init_interp(Tcl_Interp *interp)
 {
    /************************************************************
-    * Create the interpreter as a safe slave of the hold interp.
-    ************************************************************/
-   if ((pltcl_safe_interp =
-        Tcl_CreateSlave(pltcl_hold_interp, "safe", 1)) == NULL)
-   {
-       elog(ERROR,
-            "pltcl: internal error - cannot create 'safe' interpreter");
-   }
-
-   /************************************************************
-    * Enable debugging output from the Tcl bytecode compiler
-    * To see the trace, the interpreter must be created unsafe
-    * USE ONLY FOR DEBUGGING!!!
-    ************************************************************/
-
-   /*
-    * Tcl_SetVar(pltcl_safe_interp, "tcl_traceCompile", "1", 0);
-    */
-
-   /************************************************************
-    * Initialize the proc and query hash tables
-    ************************************************************/
-   pltcl_proc_hash = (Tcl_HashTable *) malloc(sizeof(Tcl_HashTable));
-   pltcl_query_hash = (Tcl_HashTable *) malloc(sizeof(Tcl_HashTable));
-   Tcl_InitHashTable(pltcl_proc_hash, TCL_STRING_KEYS);
-   Tcl_InitHashTable(pltcl_query_hash, TCL_STRING_KEYS);
-
-   /************************************************************
-    * Install the commands for SPI support in the safe interpreter
+    * Install the commands for SPI support in the interpreter
     ************************************************************/
-   Tcl_CreateCommand(pltcl_safe_interp, "elog",
+   Tcl_CreateCommand(interp, "elog",
                      pltcl_elog, NULL, NULL);
-   Tcl_CreateCommand(pltcl_safe_interp, "quote",
+   Tcl_CreateCommand(interp, "quote",
                      pltcl_quote, NULL, NULL);
+   Tcl_CreateCommand(interp, "argisnull",
+                     pltcl_argisnull, NULL, NULL);
+   Tcl_CreateCommand(interp, "return_null",
+                     pltcl_returnnull, NULL, NULL);
 
-   Tcl_CreateCommand(pltcl_safe_interp, "spi_exec",
+   Tcl_CreateCommand(interp, "spi_exec",
                      pltcl_SPI_exec, NULL, NULL);
-   Tcl_CreateCommand(pltcl_safe_interp, "spi_prepare",
+   Tcl_CreateCommand(interp, "spi_prepare",
                      pltcl_SPI_prepare, NULL, NULL);
-   Tcl_CreateCommand(pltcl_safe_interp, "spi_execp",
+   Tcl_CreateCommand(interp, "spi_execp",
                      pltcl_SPI_execp, NULL, NULL);
 
 #ifdef PLTCL_UNKNOWN_SUPPORT
@@ -273,10 +235,10 @@ pltcl_init_safe_interp(void)
     * Try to load the unknown procedure from pltcl_modules
     ************************************************************/
    if (SPI_connect() != SPI_OK_CONNECT)
-       elog(ERROR, "pltcl_init_safe_interp(): SPI_connect failed");
-   pltcl_init_load_unknown();
+       elog(ERROR, "pltcl_init_interp(): SPI_connect failed");
+   pltcl_init_load_unknown(interp);
    if (SPI_finish() != SPI_OK_FINISH)
-       elog(ERROR, "pltcl_init_safe_interp(): SPI_finish failed");
+       elog(ERROR, "pltcl_init_interp(): SPI_finish failed");
 #endif  /* PLTCL_UNKNOWN_SUPPORT */
 }
 
@@ -349,7 +311,7 @@ pltcl_init_load_unknown(void)
            pfree(part);
        }
    }
-   tcl_rc = Tcl_GlobalEval(pltcl_safe_interp, Tcl_DStringValue(&unknown_src));
+   tcl_rc = Tcl_GlobalEval(interp, Tcl_DStringValue(&unknown_src));
    Tcl_DStringFree(&unknown_src);
 }
 
@@ -369,6 +331,7 @@ Datum
 pltcl_call_handler(PG_FUNCTION_ARGS)
 {
    Datum       retval;
+   FunctionCallInfo save_fcinfo;
 
    /************************************************************
     * Initialize interpreters on first call
@@ -390,22 +353,38 @@ pltcl_call_handler(PG_FUNCTION_ARGS)
     * Determine if called as function or trigger and
     * call appropriate subhandler
     ************************************************************/
+   save_fcinfo = pltcl_actual_fcinfo;
+
    if (CALLED_AS_TRIGGER(fcinfo))
+   {
+       pltcl_actual_fcinfo = NULL;
        retval = PointerGetDatum(pltcl_trigger_handler(fcinfo));
-   else
+   } else {
+       pltcl_actual_fcinfo = fcinfo;
        retval = pltcl_func_handler(fcinfo);
+   }
+
+   pltcl_actual_fcinfo = save_fcinfo;
 
    pltcl_call_level--;
 
    return retval;
 }
 
+/* keep non-static */
+Datum
+pltclu_call_handler(PG_FUNCTION_ARGS)
+{
+   return pltcl_call_handler(fcinfo);
+}
+
 /**********************************************************************
  * pltcl_func_handler()        - Handler for regular function calls
  **********************************************************************/
 static Datum
 pltcl_func_handler(PG_FUNCTION_ARGS)
 {
+   Tcl_Interp *interp;
    int         i;
    char        internal_proname[512];
    Tcl_HashEntry *hashent;
@@ -436,15 +415,17 @@ pltcl_func_handler(PG_FUNCTION_ARGS)
         *
         * Then we load the procedure into the safe interpreter.
         ************************************************************/
-       HeapTuple   procTup;
-       HeapTuple   typeTup;
-       Form_pg_proc procStruct;
-       Form_pg_type typeStruct;
-       Tcl_DString proc_internal_def;
-       Tcl_DString proc_internal_body;
-       char        proc_internal_args[4096];
-       char       *proc_source;
-       char        buf[512];
+       HeapTuple       procTup;
+       HeapTuple       langTup;
+       HeapTuple       typeTup;
+       Form_pg_proc    procStruct;
+       Form_pg_language langStruct;
+       Form_pg_type    typeStruct;
+       Tcl_DString     proc_internal_def;
+       Tcl_DString     proc_internal_body;
+       char            proc_internal_args[4096];
+       char           *proc_source;
+       char            buf[512];
 
        /************************************************************
         * Allocate a new procedure description block
@@ -468,6 +449,27 @@ pltcl_func_handler(PG_FUNCTION_ARGS)
        }
        procStruct = (Form_pg_proc) GETSTRUCT(procTup);
 
+       /************************************************************
+        * Lookup the pg_language tuple by Oid
+        ************************************************************/
+       langTup = SearchSysCacheTuple(LANGOID,
+                                     ObjectIdGetDatum(procStruct->prolang),
+                                     0, 0, 0);
+       if (!HeapTupleIsValid(langTup))
+       {
+           free(prodesc->proname);
+           free(prodesc);
+           elog(ERROR, "pltcl: cache lookup for language %u failed",
+                procStruct->prolang);
+       }
+       langStruct = (Form_pg_language) GETSTRUCT(langTup);
+
+       prodesc->lanpltrusted = langStruct->lanpltrusted;
+       if (prodesc->lanpltrusted)
+           interp = pltcl_safe_interp;
+       else
+           interp = pltcl_norm_interp;
+
        /************************************************************
         * Get the required information for input conversion of the
         * return value.
@@ -570,9 +572,9 @@ pltcl_func_handler(PG_FUNCTION_ARGS)
        Tcl_DStringFree(&proc_internal_body);
 
        /************************************************************
-        * Create the procedure in the safe interpreter
+        * Create the procedure in the interpreter
         ************************************************************/
-       tcl_rc = Tcl_GlobalEval(pltcl_safe_interp,
+       tcl_rc = Tcl_GlobalEval(interp,
                                Tcl_DStringValue(&proc_internal_def));
        Tcl_DStringFree(&proc_internal_def);
        if (tcl_rc != TCL_OK)
@@ -580,7 +582,7 @@ pltcl_func_handler(PG_FUNCTION_ARGS)
            free(prodesc->proname);
            free(prodesc);
            elog(ERROR, "pltcl: cannot create internal procedure %s - %s",
-                internal_proname, pltcl_safe_interp->result);
+                internal_proname, interp->result);
        }
 
        /************************************************************
@@ -596,6 +598,11 @@ pltcl_func_handler(PG_FUNCTION_ARGS)
         * Found the proc description block in the hashtable
         ************************************************************/
        prodesc = (pltcl_proc_desc *) Tcl_GetHashValue(hashent);
+
+       if (prodesc->lanpltrusted)
+           interp = pltcl_safe_interp;
+       else
+           interp = pltcl_norm_interp;
    }
 
    /************************************************************
@@ -671,7 +678,7 @@ pltcl_func_handler(PG_FUNCTION_ARGS)
    /************************************************************
     * Call the Tcl function
     ************************************************************/
-   tcl_rc = Tcl_GlobalEval(pltcl_safe_interp, Tcl_DStringValue(&tcl_cmd));
+   tcl_rc = Tcl_GlobalEval(interp, Tcl_DStringValue(&tcl_cmd));
    Tcl_DStringFree(&tcl_cmd);
 
    /************************************************************
@@ -687,7 +694,7 @@ pltcl_func_handler(PG_FUNCTION_ARGS)
            pltcl_restart_in_progress = 1;
            if (--pltcl_call_level == 0)
                pltcl_restart_in_progress = 0;
-           elog(ERROR, "pltcl: %s", pltcl_safe_interp->result);
+           elog(ERROR, "pltcl: %s", interp->result);
        }
        if (--pltcl_call_level == 0)
            pltcl_restart_in_progress = 0;
@@ -720,7 +727,7 @@ pltcl_func_handler(PG_FUNCTION_ARGS)
        elog(ERROR, "pltcl: SPI_finish() failed");
 
    retval = FunctionCall3(&prodesc->result_in_func,
-                          PointerGetDatum(pltcl_safe_interp->result),
+                          PointerGetDatum(interp->result),
                           ObjectIdGetDatum(prodesc->result_in_elem),
                           Int32GetDatum(-1));
 
@@ -735,6 +742,7 @@ pltcl_func_handler(PG_FUNCTION_ARGS)
 static HeapTuple
 pltcl_trigger_handler(PG_FUNCTION_ARGS)
 {
+   Tcl_Interp *interp;
    TriggerData *trigdata = (TriggerData *) fcinfo->context;
    char        internal_proname[512];
    char       *stroid;
@@ -776,7 +784,9 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS)
        Tcl_DString proc_internal_def;
        Tcl_DString proc_internal_body;
        HeapTuple   procTup;
+       HeapTuple   langTup;
        Form_pg_proc procStruct;
+       Form_pg_language langStruct;
        char       *proc_source;
 
        /************************************************************
@@ -802,6 +812,27 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS)
        }
        procStruct = (Form_pg_proc) GETSTRUCT(procTup);
 
+       /************************************************************
+        * Lookup the pg_language tuple by Oid
+        ************************************************************/
+       langTup = SearchSysCacheTuple(LANGOID,
+                                     ObjectIdGetDatum(procStruct->prolang),
+                                     0, 0, 0);
+       if (!HeapTupleIsValid(langTup))
+       {
+           free(prodesc->proname);
+           free(prodesc);
+           elog(ERROR, "pltcl: cache lookup for language %u failed",
+                procStruct->prolang);
+       }
+       langStruct = (Form_pg_language) GETSTRUCT(langTup);
+
+       prodesc->lanpltrusted = langStruct->lanpltrusted;
+       if (prodesc->lanpltrusted)
+           interp = pltcl_safe_interp;
+       else
+           interp = pltcl_norm_interp;
+
        /************************************************************
         * Create the tcl command to define the internal
         * procedure
@@ -846,9 +877,9 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS)
        Tcl_DStringFree(&proc_internal_body);
 
        /************************************************************
-        * Create the procedure in the safe interpreter
+        * Create the procedure in the interpreter
         ************************************************************/
-       tcl_rc = Tcl_GlobalEval(pltcl_safe_interp,
+       tcl_rc = Tcl_GlobalEval(interp,
                                Tcl_DStringValue(&proc_internal_def));
        Tcl_DStringFree(&proc_internal_def);
        if (tcl_rc != TCL_OK)
@@ -856,7 +887,7 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS)
            free(prodesc->proname);
            free(prodesc);
            elog(ERROR, "pltcl: cannot create internal procedure %s - %s",
-                internal_proname, pltcl_safe_interp->result);
+                internal_proname, interp->result);
        }
 
        /************************************************************
@@ -872,13 +903,18 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS)
         * Found the proc description block in the hashtable
         ************************************************************/
        prodesc = (pltcl_proc_desc *) Tcl_GetHashValue(hashent);
+
+       if (prodesc->lanpltrusted)
+           interp = pltcl_safe_interp;
+       else
+           interp = pltcl_norm_interp;
    }
 
    tupdesc = trigdata->tg_relation->rd_att;
 
    /************************************************************
     * Create the tcl command to call the internal
-    * proc in the safe interpreter
+    * proc in the interpreter
     ************************************************************/
    Tcl_DStringInit(&tcl_cmd);
    Tcl_DStringInit(&tcl_trigtup);
@@ -998,7 +1034,7 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS)
    /************************************************************
     * Call the Tcl function
     ************************************************************/
-   tcl_rc = Tcl_GlobalEval(pltcl_safe_interp, Tcl_DStringValue(&tcl_cmd));
+   tcl_rc = Tcl_GlobalEval(interp, Tcl_DStringValue(&tcl_cmd));
    Tcl_DStringFree(&tcl_cmd);
 
    /************************************************************
@@ -1014,7 +1050,7 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS)
            pltcl_restart_in_progress = 1;
            if (--pltcl_call_level == 0)
                pltcl_restart_in_progress = 0;
-           elog(ERROR, "pltcl: %s", pltcl_safe_interp->result);
+           elog(ERROR, "pltcl: %s", interp->result);
        }
        if (--pltcl_call_level == 0)
            pltcl_restart_in_progress = 0;
@@ -1037,9 +1073,9 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS)
    if (SPI_finish() != SPI_OK_FINISH)
        elog(ERROR, "pltcl: SPI_finish() failed");
 
-   if (strcmp(pltcl_safe_interp->result, "OK") == 0)
+   if (strcmp(interp->result, "OK") == 0)
        return rettup;
-   if (strcmp(pltcl_safe_interp->result, "SKIP") == 0)
+   if (strcmp(interp->result, "SKIP") == 0)
    {
        return (HeapTuple) NULL;;
    }
@@ -1048,11 +1084,11 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS)
     * Convert the result value from the safe interpreter
     * and setup structures for SPI_modifytuple();
     ************************************************************/
-   if (Tcl_SplitList(pltcl_safe_interp, pltcl_safe_interp->result,
+   if (Tcl_SplitList(interp, interp->result,
                      &ret_numvals, &ret_values) != TCL_OK)
    {
        elog(NOTICE, "pltcl: cannot split return value from trigger");
-       elog(ERROR, "pltcl: %s", pltcl_safe_interp->result);
+       elog(ERROR, "pltcl: %s", interp->result);
    }
 
    if (ret_numvals % 2 != 0)
@@ -1275,6 +1311,91 @@ pltcl_quote(ClientData cdata, Tcl_Interp *interp,
 }
 
 
+/**********************************************************************
+ * pltcl_argisnull()   - determine if a specific argument is NULL
+ **********************************************************************/
+static int
+pltcl_argisnull(ClientData cdata, Tcl_Interp *interp,
+           int argc, char *argv[])
+{
+   int     argno;
+   FunctionCallInfo fcinfo = pltcl_actual_fcinfo;
+
+   /************************************************************
+    * Check call syntax
+    ************************************************************/
+   if (argc != 2)
+   {
+       Tcl_SetResult(interp, "syntax error - 'argisnull argno'", TCL_VOLATILE);
+       return TCL_ERROR;
+   }
+
+   /************************************************************
+    * Get the argument number
+    ************************************************************/
+   if (Tcl_GetInt(interp, argv[1], &argno) != TCL_OK)
+       return TCL_ERROR;
+
+   /************************************************************
+    * Check that we're called as a normal function
+    ************************************************************/
+   if (fcinfo == NULL)
+   {
+       Tcl_SetResult(interp, "argisnull cannot be used in triggers", 
+               TCL_VOLATILE);
+       return TCL_ERROR;
+   }
+
+   /************************************************************
+    * Check that the argno is valid
+    ************************************************************/
+   argno--;
+   if (argno < 0 || argno >= fcinfo->nargs)
+   {
+       Tcl_SetResult(interp, "argno out of range", TCL_VOLATILE);
+       return TCL_ERROR;
+   }
+
+   /************************************************************
+    * Get the requested NULL state
+    ************************************************************/
+   if (PG_ARGISNULL(argno))
+       Tcl_SetResult(interp, "1", TCL_VOLATILE);
+   else
+       Tcl_SetResult(interp, "0", TCL_VOLATILE);
+
+   return TCL_OK;
+}
+
+
+/**********************************************************************
+ * pltcl_returnnull()  - Cause a NULL return from a function
+ **********************************************************************/
+static int
+pltcl_returnnull(ClientData cdata, Tcl_Interp *interp,
+           int argc, char *argv[])
+{
+   int     argno;
+   FunctionCallInfo fcinfo = pltcl_actual_fcinfo;
+
+   /************************************************************
+    * Check call syntax
+    ************************************************************/
+   if (argc != 1)
+   {
+       Tcl_SetResult(interp, "syntax error - 'return_null'", TCL_VOLATILE);
+       return TCL_ERROR;
+   }
+
+   /************************************************************
+    * Set the NULL return flag and cause Tcl to return from the
+    * procedure.
+    ************************************************************/
+   fcinfo->isnull = true;
+   return TCL_RETURN;
+}
+
+
 /**********************************************************************
  * pltcl_SPI_exec()        - The builtin SPI_exec command
  *               for the safe interpreter
@@ -1524,6 +1645,7 @@ pltcl_SPI_prepare(ClientData cdata, Tcl_Interp *interp,
    Tcl_HashEntry *hashent;
    int         hashnew;
    sigjmp_buf  save_restart;
+   Tcl_HashTable *query_hash;
 
    /************************************************************
     * Don't do anything if we are already in restart mode
@@ -1680,8 +1802,13 @@ pltcl_SPI_prepare(ClientData cdata, Tcl_Interp *interp,
     * Insert a hashtable entry for the plan and return
     * the key to the caller
     ************************************************************/
+   if (interp == pltcl_norm_interp)
+       query_hash = pltcl_norm_query_hash;
+   else
+       query_hash = pltcl_safe_query_hash;
+
    memcpy(&Warn_restart, &save_restart, sizeof(Warn_restart));
-   hashent = Tcl_CreateHashEntry(pltcl_query_hash, qdesc->qname, &hashnew);
+   hashent = Tcl_CreateHashEntry(query_hash, qdesc->qname, &hashnew);
    Tcl_SetHashValue(hashent, (ClientData) qdesc);
 
    Tcl_SetResult(interp, qdesc->qname, TCL_VOLATILE);
@@ -1713,6 +1840,7 @@ pltcl_SPI_execp(ClientData cdata, Tcl_Interp *interp,
    HeapTuple  *volatile tuples = NULL;
    volatile TupleDesc tupdesc = NULL;
    sigjmp_buf  save_restart;
+   Tcl_HashTable *query_hash;
 
    char       *usage = "syntax error - 'SPI_execp "
    "?-nulls string? ?-count n? "
@@ -1786,7 +1914,12 @@ pltcl_SPI_execp(ClientData cdata, Tcl_Interp *interp,
    /************************************************************
     * Get the prepared plan descriptor by its key
     ************************************************************/
-   hashent = Tcl_FindHashEntry(pltcl_query_hash, argv[i++]);
+   if (interp == pltcl_norm_interp)
+       query_hash = pltcl_norm_query_hash;
+   else
+       query_hash = pltcl_safe_query_hash;
+
+   hashent = Tcl_FindHashEntry(query_hash, argv[i++]);
    if (hashent == NULL)
    {
        Tcl_AppendResult(interp, "invalid queryid '", argv[--i], "'", NULL);