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Sourcecode: firebird1.5 version File versions

exe.cpp

/*
 *    PROGRAM:    JRD Access Method
 *    MODULE:           exe.c
 *    DESCRIPTION:      Statement execution
 *
 * The contents of this file are subject to the Interbase Public
 * License Version 1.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy
 * of the License at http://www.Inprise.com/IPL.html
 *
 * Software distributed under the License is distributed on an
 * "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express
 * or implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code was created by Inprise Corporation
 * and its predecessors. Portions created by Inprise Corporation are
 * Copyright (C) Inprise Corporation.
 *
 * All Rights Reserved.
 * Contributor(s): ______________________________________.
 *
 * 2001.6.21 Claudio Valderrama: Allow inserting strings into blob fields.
 * 2001.6.28 Claudio Valderrama: Move code to cleanup_rpb() as directed
 * by Ann Harrison and cleanup of new record in store() routine.
 * 2001.10.11 Claudio Valderrama: Fix SF Bug #436462: From now, we only
 * count real store, modify and delete operations either in an external
 * file or in a table. Counting on a view caused up to three operations
 * being reported instead of one.
 * 2001.12.03 Claudio Valderrama: new visit to the same issue: views need
 * to count virtual operations, not real I/O on the underlying tables.
 * 2002.09.28 Dmitry Yemanov: Reworked internal_info stuff, enhanced
 *                            exception handling in SPs/triggers,
 *                            implemented ROWS_AFFECTED system variable
 *
 * 2002.10.21 Nickolay Samofatov: Added support for explicit pessimistic locks 
 * 2002.10.28 Sean Leyne - Code cleanup, removed obsolete "MPEXL" port
 * 2002.10.28 Sean Leyne - Code cleanup, removed obsolete "DecOSF" port
 * 2002.10.29 Nickolay Samofatov: Added support for savepoints
 *
 * 2002.10.30 Sean Leyne - Removed support for obsolete "PC_PLATFORM" define
 *
 */

#include "firebird.h"
#if TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# if HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  include <time.h>
# endif
#endif

#include "../jrd/common.h"
#include "../jrd/ibsetjmp.h"
#include <string.h>
#include "../jrd/jrd.h"
#include "../jrd/req.h"
#include "../jrd/val.h"
#include "../jrd/exe.h"
#include "../jrd/tra.h"
#include "gen/codes.h"
#include "../jrd/ods.h"
#include "../jrd/btr.h"
#include "../jrd/rse.h"
#include "../jrd/lck.h"
#include "../jrd/intl.h"
#include "../jrd/rng.h"
#include "../jrd/sbm.h"
#include "../jrd/blb.h"
#include "../jrd/blr.h"
#include "../jrd/all_proto.h"
#include "../jrd/bookmark.h"
#include "../jrd/blb_proto.h"
#include "../jrd/btr_proto.h"
#include "../jrd/cmp_proto.h"
#include "../jrd/dfw_proto.h"
#include "../jrd/dpm_proto.h"
#include "../jrd/err_proto.h"
#include "../jrd/evl_proto.h"
#include "../jrd/exe_proto.h"
#include "../jrd/ext_proto.h"
#include "../jrd/gds_proto.h"
#include "../jrd/idx_proto.h"
#include "../jrd/jrd_proto.h"

#include "../jrd/lck_proto.h"
#include "../jrd/met_proto.h"
#include "../jrd/mov_proto.h"
#include "../jrd/opt_proto.h"
#include "../jrd/par_proto.h"
#include "../jrd/rlck_proto.h"
#include "../jrd/rse_proto.h"
#include "../jrd/rng_proto.h"
#include "../jrd/thd_proto.h"
#include "../jrd/tra_proto.h"
#include "../jrd/vio_proto.h"
#include "../jrd/isc_s_proto.h"

#include "../jrd/ExecuteStatement.h"
#include "../dsql/dsql_proto.h"
#include "../jrd/rpb_chain.h"

extern "C" {


#ifdef SHLIB_DEFS
#undef send
#endif


static void assign_xcp_message(TDBB, STR *, const TEXT *);
static void cleanup_rpb(TDBB, RPB *);
static JRD_NOD erase(TDBB, JRD_NOD, SSHORT);
static void execute_looper(TDBB, JRD_REQ, JRD_TRA, ENUM jrd_req::req_s);
static void exec_sql(TDBB, JRD_REQ, DSC *);
static void execute_procedure(TDBB, JRD_NOD);
static JRD_REQ execute_triggers(TDBB, TRIG_VEC *, REC, REC, ENUM jrd_req::req_ta);
static JRD_NOD looper(TDBB, JRD_REQ, JRD_NOD);
static JRD_NOD modify(TDBB, JRD_NOD, SSHORT);
static JRD_NOD receive_msg(TDBB, JRD_NOD);
static void release_blobs(TDBB, JRD_REQ);
static void release_proc_save_points(JRD_REQ);
#ifdef SCROLLABLE_CURSORS
static JRD_NOD seek_rse(TDBB, JRD_REQ, JRD_NOD);
static void seek_rsb(TDBB, JRD_REQ, RSB, USHORT, SLONG);
#endif
static JRD_NOD selct(TDBB, JRD_NOD);
static JRD_NOD send_msg(TDBB, JRD_NOD);
static void set_error(TDBB, XCP, JRD_NOD);
static JRD_NOD stall(TDBB, JRD_NOD);
static JRD_NOD store(TDBB, JRD_NOD, SSHORT);
static BOOLEAN test_and_fixup_error(TDBB, const XCP, JRD_REQ);
static void trigger_failure(TDBB, JRD_REQ);
static void validate(TDBB, JRD_NOD);
inline void PreModifyEraseTriggers(TDBB, trig_vec**, SSHORT, RPB*, REC, jrd_req::req_ta);

#ifdef PC_ENGINE
static BOOLEAN check_crack(RSB, USHORT);
static JRD_NOD find(TDBB, JRD_NOD);
static JRD_NOD find_dbkey(TDBB, JRD_NOD);
static LCK implicit_record_lock(JRD_TRA, RPB *);
static JRD_NOD release_bookmark(TDBB, JRD_NOD);
static JRD_NOD set_bookmark(TDBB, JRD_NOD);
static JRD_NOD set_index(TDBB, JRD_NOD);
static JRD_NOD stream(TDBB, JRD_NOD);
#endif

#if defined(DEBUG_GDS_ALLOC) && defined(PROD_BUILD)
static SLONG memory_debug = 1;
static SLONG memory_count = 0;
#endif /* DEBUG_GDS_ALLOC */

/* macro definitions */

#define NULL_STRING     "*** null ***"

#if (defined SUPERSERVER) && (defined WIN_NT || defined SOLARIS_MT)
#define MAX_CLONES      750
#endif

#if defined (HP10) && defined (SUPERSERVER)
#define MAX_CLONES      110
#endif

#ifndef MAX_CLONES
#define MAX_CLONES      1000
#endif

#define ALL_TRIGS 0
#define PRE_TRIG  1
#define POST_TRIG 2

/* this constant defines how many records are locked
   before we check whether record locking has been
   turned off for a given relation; if we set the 
   constant to a low number, we will do too much 
   locking in the case where record locking is always
   turned on; too high and we will do too much record
   locking in the case where someone is only occasionally
   locking a record */

#define RECORD_LOCK_CHECK_INTERVAL  10


#ifdef PC_ENGINE
// TMN: RAII class for LCK. Unlocks the LCK on destruction.
class LCK_RAII_wrapper
{
      LCK_RAII_wrapper() : l(0) {}
      ~LCK_RAII_wrapper() {
            if (l) {
                  RLCK_unlock_record_implicit(l, 0);
            }
      }
      void assign(LCK lock) { l = lck; }

      LCK l;

private:
      LCK_RAII_wrapper(const LCK_RAII_wrapper&);      // no impl.
      void operator=(const LCK_RAII_wrapper&);  // no impl.
};
#endif


void EXE_assignment(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    E X E _ a s s i g n m e n t
 *
 **************************************
 *
 * Functional description
 *    Perform an assignment
 *
 **************************************/

      DSC temp;

      DEV_BLKCHK(node, type_nod);

      SET_TDBB(tdbb);
      JRD_REQ request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

/* Get descriptors of receiving and sending fields/parameters, variables, etc. */

      DSC* missing = NULL;
      if (node->nod_arg[e_asgn_missing]) {
            missing = EVL_expr(tdbb, node->nod_arg[e_asgn_missing]);
      }

      JRD_NOD to = node->nod_arg[e_asgn_to];
      DSC* to_desc = EVL_assign_to(tdbb, to);

      request->req_flags &= ~req_null;

      DSC* from_desc = EVL_expr(tdbb, node->nod_arg[e_asgn_from]);

      SSHORT null = (request->req_flags & req_null) ? -1 : 0;

      if (!null && missing && MOV_compare(missing, from_desc) == 0) {
            null = -1;
      }

/* If the value is non-missing, move/convert it.  Otherwise fill the
   field with appropriate nulls. */

      if (!null)
      {
            /* if necessary and appropriate, use the indicator variable */

            if (to->nod_type == nod_argument && to->nod_arg[e_arg_indicator])
            {
                  DSC* indicator    = EVL_assign_to(tdbb, to->nod_arg[e_arg_indicator]);
                  temp.dsc_dtype    = dtype_short;
                  temp.dsc_length   = sizeof(SSHORT);
                  temp.dsc_scale    = 0;
                  temp.dsc_sub_type = 0;

                  SSHORT len;

                  if ((from_desc->dsc_dtype <= dtype_varying) &&
                        (to_desc->dsc_dtype <= dtype_varying) &&
                        (TEXT_LEN(from_desc) > TEXT_LEN(to_desc)))
                  {
                        len = TEXT_LEN(from_desc);
                  } else {
                        len = 0;
                  }

                  temp.dsc_address = (UCHAR *) & len;
                  MOV_move(&temp, indicator);

                  if (len) {
                        temp = *from_desc;
                        temp.dsc_length = TEXT_LEN(to_desc);
                        if (temp.dsc_dtype == dtype_cstring) {
                              temp.dsc_length += 1;
                        } else if (temp.dsc_dtype == dtype_varying) {
                              temp.dsc_length += 2;
                        }
                        from_desc = &temp;
                  }
            }

#ifndef VMS
            if (DTYPE_IS_BLOB(to_desc->dsc_dtype))
#else
            if (DTYPE_IS_BLOB(to_desc->dsc_dtype)
                  && to_desc->dsc_dtype != dtype_d_float)
#endif
            {
                  /* CVC: This is a case that has hurt me for years and I'm going to solve it.
                              It should be possible to copy a string to a blob, even if the charset is
                              lost as a result of this experimental implementation. */
                  if (from_desc->dsc_dtype <= dtype_varying)
                        BLB_move_from_string(tdbb, from_desc, to_desc, to);
                  else 
                        BLB_move(tdbb, from_desc, to_desc, to);
            }

            else if (!DSC_EQUIV(from_desc, to_desc))
                  MOV_move(from_desc, to_desc);

            else if (from_desc->dsc_dtype == dtype_short)
                  *((SSHORT *) to_desc->dsc_address) =
                        *((SSHORT *) from_desc->dsc_address);

            else if (from_desc->dsc_dtype == dtype_long)
                  *((SLONG *) to_desc->dsc_address) =
                        *((SLONG *) from_desc->dsc_address);

            else if (from_desc->dsc_dtype == dtype_int64)
                  *((SINT64 *) to_desc->dsc_address) =
                        *((SINT64 *) from_desc->dsc_address);

            else if (((U_IPTR) from_desc->dsc_address & (FB_ALIGNMENT - 1)) ||
                         ((U_IPTR) to_desc->dsc_address & (FB_ALIGNMENT - 1)))
                  MOVE_FAST(from_desc->dsc_address, to_desc->dsc_address,
                                from_desc->dsc_length);

            else
                  MOVE_FASTER(from_desc->dsc_address, to_desc->dsc_address,
                                    from_desc->dsc_length);
            to_desc->dsc_flags &= ~DSC_null;
      }
      else if (node->nod_arg[e_asgn_missing2] &&
                   (missing = EVL_expr(tdbb, node->nod_arg[e_asgn_missing2])))
      {
            MOV_move(missing, to_desc);
            to_desc->dsc_flags |= DSC_null;
      }
      else
      {
            UCHAR *p;
            USHORT l;

            l = to_desc->dsc_length;
            p = to_desc->dsc_address;
            switch (to_desc->dsc_dtype) {
            case dtype_text:
                  /* YYY - not necessarily the right thing to do */
                  /* for text formats that don't have trailing spaces */
                  if (l) {
                        do {
                              *p++ = ' ';
                        } while (--l);
                  }
                  break;

            case dtype_cstring:
                  *p = 0;
                  break;

            case dtype_varying:
                  *(SSHORT *) p = 0;
                  break;

            default:
                  do
                        *p++ = 0;
                  while (--l);
                  break;
            }
            to_desc->dsc_flags |= DSC_null;
      }

/* Handle the null flag as appropriate for fields and message arguments. */

      if (to->nod_type == nod_field)
      {
            SSHORT id = (USHORT) (IPTR) to->nod_arg[e_fld_id];
            REC record = request->req_rpb[(int) to->nod_arg[e_fld_stream]].rpb_record;
            if (null) {
                  SET_NULL(record, id);
            } else {
                  CLEAR_NULL(record, id);
            }
      }
      else if (to->nod_type == nod_argument && to->nod_arg[e_arg_flag])
      {
            to_desc = EVL_assign_to(tdbb, to->nod_arg[e_arg_flag]);

            /* If the null flag is a string with an effective length of one,
               then -1 will not fit.  Therefore, store 1 instead. */

            if (null &&
                  to_desc->dsc_dtype <= dtype_varying &&
                  to_desc->dsc_length <=
                  ((to_desc->dsc_dtype == dtype_text) ? 1 :
                  ((to_desc->dsc_dtype == dtype_cstring) ? 2 :
                                                                              3)))
            {
                  null = 1;
            }

            temp.dsc_dtype = dtype_short;
            temp.dsc_length = sizeof(SSHORT);
            temp.dsc_scale = 0;
            temp.dsc_sub_type = 0;
            temp.dsc_address = (UCHAR *) & null;
            MOV_move(&temp, to_desc);
            if (null && to->nod_arg[e_arg_indicator]) {
                  to_desc = EVL_assign_to(tdbb, to->nod_arg[e_arg_indicator]);
                  MOV_move(&temp, to_desc);
            }
      }

      request->req_operation = jrd_req::req_return;
}


#ifdef PC_ENGINE
BOOLEAN EXE_crack(TDBB tdbb, RSB rsb, USHORT flags)
{
/**************************************
 *
 *    E X E _ c r a c k
 *
 **************************************
 *
 * Functional description
 *    Check whether stream is on a crack, BOF
 *    or EOF, according to the flags passed.
 *
 **************************************/
      JRD_REQ request;
      RPB *rpb;
      IRSB impure;


      DEV_BLKCHK(rsb, type_rsb);

      SET_TDBB(tdbb);
      request = tdbb->tdbb_request;

/* correct boolean rsbs to point to the "real" rsb */

      if (rsb->rsb_type == rsb_boolean)
            rsb = rsb->rsb_next;
      impure = (IRSB) ((UCHAR *) request + rsb->rsb_impure);

/* if any of the passed flags are set, return TRUE */

      if (impure->irsb_flags & flags)
            return TRUE;
      else
            return FALSE;
}
#endif


JRD_REQ EXE_find_request(TDBB tdbb, JRD_REQ request, BOOLEAN validate)
{
/**************************************
 *
 *    E X E _ f i n d _ r e q u e s t
 *
 **************************************
 *
 * Functional description
 *    Find an inactive incarnation of a trigger request.  If necessary,
 *    clone it.
 *
 **************************************/
#ifdef ANY_THREADING
      DBB dbb;
#endif
      JRD_REQ clone, next;
      USHORT n, clones, count;
      VEC vector;

      DEV_BLKCHK(request, type_req);

      SET_TDBB(tdbb);
#ifdef ANY_THREADING
      dbb = tdbb->tdbb_database;
#endif

/* I found a core file from my test runs that came from a NULL request -
 * but have no idea what test was running.  Let's bugcheck so we can
 * figure it out
 */
      if (!request)
            BUGCHECK /* REQUEST */ (167); /* msg 167 invalid SEND request */

      THD_MUTEX_LOCK(dbb->dbb_mutexes + DBB_MUTX_clone);
      clone = NULL;
      count = 0;
      if (!(request->req_flags & req_in_use))
            clone = request;
      else {
            if (request->req_attachment == tdbb->tdbb_attachment)
                  count++;

            /* Request exists and is in use.  Search clones for one in use by
               this attachment. If not found, return first inactive request. */

            clones = (vector =
                          request->req_sub_requests) ? (vector->count() - 1) : 0;

            for (n = 1; n <= clones; n++) {
                  next = CMP_clone_request(tdbb, request, n, validate);
                  if (next->req_attachment == tdbb->tdbb_attachment) {
                        if (!(next->req_flags & req_in_use)) {
                              clone = next;
                              break;
                        }
                        else
                              count++;
                  }
                  else if (!(next->req_flags & req_in_use) && !clone)
                        clone = next;
            }

            if (count > MAX_CLONES) {
                  THD_MUTEX_UNLOCK(dbb->dbb_mutexes + DBB_MUTX_clone);
                  ERR_post(gds_req_max_clones_exceeded, 0);
            }
            if (!clone)
                  clone = CMP_clone_request(tdbb, request, n, validate);
      }
      clone->req_attachment = tdbb->tdbb_attachment;
      clone->req_flags |= req_in_use;
      THD_MUTEX_UNLOCK(dbb->dbb_mutexes + DBB_MUTX_clone);
      return clone;
}


#ifdef PC_ENGINE
void EXE_mark_crack(TDBB tdbb, RSB rsb, USHORT flag)
{
/**************************************
 *
 *    E X E _ m a r k _ c r a c k
 *
 **************************************
 *
 * Functional description
 *    Mark a stream as being at a crack,
 *    plus report the fact in the status
 *    vector.
 *
 **************************************/

      SET_TDBB(tdbb);
      DEV_BLKCHK(rsb, type_rsb);

/* correct boolean rsbs to point to the "real" rsb */

      if (rsb->rsb_type == rsb_boolean)
            rsb = rsb->rsb_next;

      RSE_MARK_CRACK(tdbb, rsb, flag);

      if (flag == irsb_eof)
            ERR_warning(gds_stream_eof, 0);
      else if (flag == irsb_bof)
            ERR_warning(gds_stream_bof, 0);
      else if (flag & irsb_crack)
            ERR_warning(gds_stream_crack, 0);
}
#endif


void EXE_receive(TDBB         tdbb,
                         JRD_REQ          request,
                         USHORT           msg,
                         USHORT           length,
                         UCHAR*           buffer)
{
/**************************************
 *
 *    E X E _ r e c e i v e
 *
 **************************************
 *
 * Functional description
 *    Move a message from JRD to the host program.  This corresponds to
 *    a JRD BLR/JRD_NOD send.
 *
 **************************************/
      JRD_NOD message;
      FMT format;
      JRD_TRA transaction;
      SAV save_sav_point;

      SET_TDBB(tdbb);

      DEV_BLKCHK(request, type_req);

      transaction = request->req_transaction;

      if (!(request->req_flags & req_active)) {
            ERR_post(gds_req_sync, 0);
      }

      if (request->req_flags & req_proc_fetch)
      {
            /* request->req_proc_sav_point stores all the request savepoints.
               When going to continue execution put request save point list
               into transaction->tra_save_point so that it is used in looper.
               When we come back to EXE_receive() restore
               transaction->tra_save_point and merge all work done under
               stored procedure savepoints into the current transaction
               savepoint, which is the savepoint for fetch. */

            save_sav_point = transaction->tra_save_point;
            transaction->tra_save_point = request->req_proc_sav_point;
            request->req_proc_sav_point = save_sav_point;

            if (!transaction->tra_save_point) {
                  VIO_start_save_point(tdbb, transaction);
            }
      }
      
      try
      {

      if (request->req_message->nod_type == nod_stall
#ifdef SCROLLABLE_CURSORS
            || request->req_flags & req_fetch_required
#endif
            )
            execute_looper(tdbb, request, transaction, jrd_req::req_sync);

      if (!(request->req_flags & req_active) ||
            request->req_operation != jrd_req::req_send)
      {
            ERR_post(gds_req_sync, 0);
      }

      message = request->req_message;
      format = (FMT) message->nod_arg[e_msg_format];

      if (msg != (USHORT) (IPTR) message->nod_arg[e_msg_number])
            ERR_post(gds_req_sync, 0);

      if (length != format->fmt_length)
            ERR_post(gds_port_len,
                         gds_arg_number, (SLONG) length,
                         gds_arg_number, (SLONG) format->fmt_length, 0);

      if ((U_IPTR) buffer & (FB_ALIGNMENT - 1))
            MOVE_FAST((SCHAR *) request + message->nod_impure, buffer, length);
      else
            MOVE_FASTER((SCHAR *) request + message->nod_impure, buffer, length);

      execute_looper(tdbb, request, transaction, jrd_req::req_proceed);

      }     //try
      catch (const std::exception&)
      {
            if (request->req_flags & req_proc_fetch)
            {
                  save_sav_point = transaction->tra_save_point;
                  transaction->tra_save_point = request->req_proc_sav_point;
                  request->req_proc_sav_point = save_sav_point;
                  release_proc_save_points(request);
                  Firebird::status_exception::raise(-1);
            }
            throw;
      }

      if (request->req_flags & req_proc_fetch) {
            save_sav_point = transaction->tra_save_point;
            transaction->tra_save_point = request->req_proc_sav_point;
            request->req_proc_sav_point = save_sav_point;
            VIO_merge_proc_sav_points(tdbb, transaction,
                                                  &request->req_proc_sav_point);
      }

}


#ifdef SCROLLABLE_CURSORS
void EXE_seek(TDBB tdbb, JRD_REQ request, USHORT direction, ULONG offset)
{
/**************************************
 *
 *      E X E _ s e e k
 *
 **************************************
 *
 * Functional description
 *    Seek a given request in a particular direction 
 *    for offset records. 
 *
 **************************************/
      RSB rsb;
      SLONG i;

      SET_TDBB(tdbb);
      DEV_BLKCHK(request, type_req);

/* loop through all RSEs in the request, 
   and describe the rsb tree for that rsb;
   go backwards because items were popped
   off the stack backwards */

/* find the top-level rsb in the request and seek it */

      for (SLONG i = request->req_fors.getCount() - 1; i >= 0; i--) {
            RSB rsb = request->req_fors[i];
            if (rsb) {
                  seek_rsb(tdbb, request, rsb, direction, offset);
                  break;
            }
      }
}
#endif


void EXE_send(TDBB            tdbb,
                    JRD_REQ         request,
                    USHORT    msg,
                    USHORT    length,
                    UCHAR*    buffer)
{
/**************************************
 *
 *    E X E _ s e n d
 *
 **************************************
 *
 * Functional description
 *    Send a message from the host program to the engine.  
 *    This corresponds to a blr_receive or blr_select statement.
 *
 **************************************/
      JRD_NOD node, message, *ptr, *end;
      FMT format;
      JRD_TRA transaction;
#ifdef SCROLLABLE_CURSORS
      USHORT save_operation;
      JRD_NOD save_next = NULL, save_message;
#endif

      SET_TDBB(tdbb);
      DEV_BLKCHK(request, type_req);

      if (!(request->req_flags & req_active))
            ERR_post(gds_req_sync, 0);

#ifdef SCROLLABLE_CURSORS
/* look for an asynchronous send message--if such 
   a message was defined, we allow the user to send 
   us a message at any time during request execution */

      if ((message = request->req_async_message) &&
            (node = message->nod_arg[e_send_message]) &&
            (msg == (USHORT) (IPTR) node->nod_arg[e_msg_number])) {
            /* save the current state of the request so we can go 
               back to what was interrupted */

            save_operation = request->req_operation;
            save_message = request->req_message;
            save_next = request->req_next;

            request->req_operation = req_receive;
            request->req_message = node;
            request->req_next = message->nod_arg[e_send_statement];

            /* indicate that we are processing an asynchronous message */

            request->req_flags |= req_async_processing;
      }
      else {
#endif
            if (request->req_operation != jrd_req::req_receive)
                  ERR_post(gds_req_sync, 0);
            node = request->req_message;
#ifdef SCROLLABLE_CURSORS
      }
#endif

      transaction = request->req_transaction;

      if (node->nod_type == nod_message)
            message = node;
      else if (node->nod_type == nod_select)
            for (ptr = node->nod_arg, end = ptr + node->nod_count; ptr < end;
                   ptr++) {
                  message = (*ptr)->nod_arg[e_send_message];
                  if ((USHORT) (IPTR) message->nod_arg[e_msg_number] == msg) {
                        request->req_next = *ptr;
                        break;
                  }
            }
      else
            BUGCHECK(167);                /* msg 167 invalid SEND request */

      format = (FMT) message->nod_arg[e_msg_format];

      if (msg != (USHORT) (IPTR) message->nod_arg[e_msg_number])
            ERR_post(gds_req_sync, 0);

      if (length != format->fmt_length)
            ERR_post(gds_port_len,
                         gds_arg_number, (SLONG) length,
                         gds_arg_number, (SLONG) format->fmt_length, 0);

      if ((U_IPTR) buffer & (FB_ALIGNMENT - 1))
            MOVE_FAST(buffer, (SCHAR *) request + message->nod_impure, length);
      else
            MOVE_FASTER(buffer, (SCHAR *) request + message->nod_impure, length);

      execute_looper(tdbb, request, transaction, jrd_req::req_proceed);

#ifdef SCROLLABLE_CURSORS
      if (save_next) {
            /* if the message was sent asynchronously, restore all the 
               previous values so that whatever we were trying to do when 
               the message came in is what we do next */

            request->req_operation = save_operation;
            request->req_message = save_message;
            request->req_next = save_next;
      }
#endif
}


void EXE_start(TDBB tdbb, JRD_REQ request, JRD_TRA transaction)
{
/**************************************
 *
 *    E X E _ s t a r t
 *
 **************************************
 *
 * Functional description
 *    Start an execution running.
 *
 **************************************/
      DBB dbb;

      SET_TDBB(tdbb);
      dbb = tdbb->tdbb_database;

      BLKCHK(request, type_req);
      BLKCHK(transaction, type_tra);

      if (request->req_flags & req_active)
            ERR_post(gds_req_sync, gds_arg_gds, gds_reqinuse, 0);

      if (transaction->tra_flags & TRA_prepared)
            ERR_post(gds_req_no_trans, 0);

/* Post resources to transaction block.  In particular, the interest locks
   on relations/indices are copied to the transaction, which is very
   important for (short-lived) dynamically compiled requests.  This will
   provide transaction stability by preventing a relation from being
   dropped after it has been referenced from an active transaction. */

      TRA_post_resources(tdbb, transaction, request->req_resources);

      request->req_transaction = transaction;
      request->req_flags &= REQ_FLAGS_INIT_MASK;
      request->req_flags |= req_active;
      request->req_flags &= ~req_reserved;
      request->req_operation = jrd_req::req_evaluate;

/* set up to count records affected by request */

      request->req_flags |= req_count_records;
      request->req_records_selected = 0;
      request->req_records_updated = 0;
      request->req_records_inserted = 0;
      request->req_records_deleted = 0;

/* CVC: set up to count virtual operations on SQL views. */

      request->req_view_flags = 0;
      request->req_top_view_store = NULL;
      request->req_top_view_modify = NULL;
      request->req_top_view_erase = NULL;

      // Store request start time for timestamp work
      if (!request->req_timestamp) {
            request->req_timestamp = time(NULL);
      }

      // Set all invariants to not computed.
      jrd_nod **ptr, **end;
      for (ptr = request->req_invariants.begin(),
            end = request->req_invariants.end(); ptr < end;
            ++ptr)
      {
            VLU impure = (VLU) ((SCHAR *) request + (*ptr)->nod_impure);
            impure->vlu_flags = 0;
      }

      // Start a save point if not in middle of one
      if (transaction && (transaction != dbb->dbb_sys_trans)) {
            VIO_start_save_point(tdbb, transaction);
      }

#ifdef WIN_NT
      START_CHECK_FOR_EXCEPTIONS(NULL);
#endif
      // TODO:
      // 1. Try to fix the problem with MSVC C++ runtime library, making
      // even C++ exceptions that are implemented in terms of Win32 SEH
      // getting catched by the SEH handler below.
      // 2. Check if it really is correct that only Win32 catches CPU
      // exceptions (such as SEH) here. Shouldn't any platform capable
      // of handling signals use this stuff?
      // (see jrd/ibsetjmp.h for implementation of these macros)

      looper(tdbb, request, request->req_top_node);

#ifdef WIN_NT
      END_CHECK_FOR_EXCEPTIONS(NULL);
#endif

      // If any requested modify/delete/insert ops have completed, forget them

      if (transaction &&
          (transaction != dbb->dbb_sys_trans) &&
          transaction->tra_save_point &&
          !(transaction->tra_save_point->sav_flags & SAV_user) &&
          !transaction->tra_save_point->sav_verb_count)
      {
            // Forget about any undo for this verb

            VIO_verb_cleanup(tdbb, transaction);
      }
}


void EXE_unwind(TDBB tdbb, JRD_REQ request)
{
/**************************************
 *
 *    E X E _ u n w i n d
 *
 **************************************
 *
 * Functional description
 *    Unwind a request, maybe active, maybe not.  This is particlarly
 *    simple since nothing really needs to be done.
 *
 **************************************/
      DEV_BLKCHK(request, type_req);

      SET_TDBB(tdbb);

      if (request->req_flags & req_active) {
            if (request->req_fors.getCount()) {
                  JrdMemoryPool *old_pool = tdbb->tdbb_default;
                  tdbb->tdbb_default = request->req_pool;
                  JRD_REQ old_request = tdbb->tdbb_request;
                  tdbb->tdbb_request = request;
                  JRD_TRA old_transaction = tdbb->tdbb_transaction;
                  tdbb->tdbb_transaction = request->req_transaction;

                  Rsb **ptr, **end;
                  for (ptr = request->req_fors.begin(), end =
                         request->req_fors.end(); ptr < end; ptr++)
                  {
                        if (*ptr)
                              RSE_close(tdbb, *ptr);
                  }

                  tdbb->tdbb_default = old_pool;
                  tdbb->tdbb_request = old_request;
                  tdbb->tdbb_transaction = old_transaction;
            }
            release_blobs(tdbb, request);
      }

      if (request->req_proc_sav_point && (request->req_flags & req_proc_fetch))
            release_proc_save_points(request);

      request->req_flags &= ~(req_active | req_proc_fetch | req_reserved);
      request->req_flags |= req_abort | req_stall;
      request->req_timestamp = 0;

}


void assign_xcp_message(TDBB tdbb, STR *xcp_msg, const TEXT *msg)
{
/**************************************
 *
 *    a s s i g n _ x c p _ m e s s a g e
 *
 **************************************
 *
 * Functional description
 *    Copy an exception message into XCP structure.
 *
 **************************************/
      SET_TDBB(tdbb);

      if (msg)
      {
            USHORT len = strlen(msg);
            *xcp_msg = FB_NEW_RPT(*tdbb->tdbb_default, len + 1) str();
            (*xcp_msg)->str_length = len;
            memcpy((*xcp_msg)->str_data, msg, len + 1);
      }
}


/* CVC: Moved to its own routine, originally in store(). */
static void cleanup_rpb(TDBB tdbb, RPB *rpb)
{
/**************************************
 *
 *    c l e a n u p _ r p b
 *
 **************************************
 *
 * Functional description
 *    Perform cleaning of rpb, zeroing unassigned fields and
 * the impure tail of varying fields that we don't want to carry
 * when the RLE algorithm is applied.
 *
 **************************************/
      DSC *desc = 0;
      SSHORT n;
      USHORT length;
      REC record = rpb->rpb_record;
      FMT format = record->rec_format;
      UCHAR *p;

      SET_TDBB(tdbb); /* Is it necessary? */

/*
    Starting from the format, walk through its
    array of descriptors.  If the descriptor has
    no address, its a computed field and we shouldn't
    try to fix it.  Get a pointer to the actual data
    and see if that field is null by indexing into
    the null flags between the record header and the
    record data.
*/

      for (n = 0; n < format->fmt_count; n++)
      {
            desc = &format->fmt_desc[n];
            if (!desc->dsc_address)
                  continue;
            p = record->rec_data + (SLONG) desc->dsc_address;
            if (TEST_NULL(record, n))
            {
                  if (length = desc->dsc_length)
                        do *p++ = 0; while (--length);
            }
            else if (desc->dsc_dtype == dtype_varying)
            {
                  VARY *vary;
                  
                  vary = reinterpret_cast<VARY*>(p);
                  if ((length = desc->dsc_length - sizeof(USHORT)) > vary->vary_length)
                  {
                        p = reinterpret_cast<UCHAR*>(vary->vary_string + vary->vary_length);
                        length -= vary->vary_length;
                        do *p++ = 0; while (--length);
                  }
            }
      }
}

inline void PreModifyEraseTriggers(TDBB tdbb, 
                                                   trig_vec** trigs, 
                                                   SSHORT which_trig, 
                                                   RPB *rpb, 
                                                   REC rec,
                                                   jrd_req::req_ta op)
{
/******************************************************
 *
 *    P r e M o d i f y E r a s e T r i g g e r s
 *
 ******************************************************
 *
 * Functional description
 *    Perform operation's pre-triggers, 
 *  storing active rpb in chain.
 *
 ******************************************************/
      if (! tdbb->tdbb_transaction->tra_rpblist) {
            tdbb->tdbb_transaction->tra_rpblist = 
                  FB_NEW(*tdbb->tdbb_transaction->tra_pool) 
                        traRpbList(*tdbb->tdbb_transaction->tra_pool);
      }
      const int rpblevel = tdbb->tdbb_transaction->tra_rpblist->PushRpb(rpb);
      JRD_REQ trigger = NULL;
      if ((*trigs) && (which_trig != POST_TRIG)) {
            trigger = execute_triggers(tdbb, trigs, rpb->rpb_record, rec, op);
      }
      tdbb->tdbb_transaction->tra_rpblist->PopRpb(rpb, rpblevel);
      if (trigger) {
            trigger_failure(tdbb, trigger);
      }
}

static JRD_NOD erase(TDBB tdbb, JRD_NOD node, SSHORT which_trig)
{
/**************************************
 *
 *    e r a s e
 *
 **************************************
 *
 * Functional description
 *    Perform erase operation.
 *
 **************************************/
      DBB dbb;
      JRD_REQ request, trigger;
      RPB *rpb;
      JRD_REL relation;
      REC record;
      FMT format;
      JRD_TRA transaction;
#ifdef PC_ENGINE
      RSB rsb = NULL;
      IRSB impure;
#endif

      SET_TDBB(tdbb);
      dbb = tdbb->tdbb_database;
      BLKCHK(node, type_nod);

      request = tdbb->tdbb_request;
      transaction = request->req_transaction;
      rpb = &request->req_rpb[(int) node->nod_arg[e_erase_stream]];
      relation = rpb->rpb_relation;

#ifdef PC_ENGINE
/* for navigational streams, retrieve the rsb */

      if (node->nod_arg[e_erase_rsb]) {
            rsb = *(RSB *) node->nod_arg[e_erase_rsb];
            impure = (IRSB) ((UCHAR *) request + rsb->rsb_impure);
      }
#endif

      switch (request->req_operation) {
      case jrd_req::req_evaluate:
            if (!node->nod_arg[e_erase_statement])
                  break;
            format = MET_current(tdbb, rpb->rpb_relation);
            record = VIO_record(tdbb, rpb, format, tdbb->tdbb_default);
            rpb->rpb_address = record->rec_data;
            rpb->rpb_length = format->fmt_length;
            rpb->rpb_format_number = format->fmt_version;
            return node->nod_arg[e_erase_statement];

      case jrd_req::req_return:
            break;

      default:
            return node->nod_parent;
      }

#ifdef PC_ENGINE
/* if we are on a crack in a navigational stream, erase 
   is not a valid operation */

      if (rsb && EXE_crack(tdbb, rsb, irsb_bof | irsb_eof | irsb_crack)) {
            EXE_mark_crack(tdbb, rsb, impure->irsb_flags);
            request->req_operation = jrd_req::req_return;
            return node->nod_parent;
      }
#endif

      request->req_operation = jrd_req::req_return;
      RLCK_reserve_relation(tdbb, transaction, relation, TRUE, TRUE);

/* If the stream was sorted, the various fields in the rpb are
   probably junk.  Just to make sure that everything is cool,
   refetch and release the record. */

      if (rpb->rpb_stream_flags & RPB_s_refetch) {
            SLONG tid_fetch;

            tid_fetch = rpb->rpb_transaction;
            if ((!DPM_get(tdbb, rpb, LCK_read)) ||
                  (!VIO_chase_record_version(tdbb,
                                                         rpb,
                                                         NULL,
                                                         transaction,
                                                         reinterpret_cast <
                                                         blk *
                                                         >(tdbb->tdbb_default),FALSE)))
                        ERR_post(gds_deadlock, gds_arg_gds, gds_update_conflict, 0);
            VIO_data(tdbb, rpb,
                         reinterpret_cast < blk * >(tdbb->tdbb_request->req_pool));

            /* If record is present, and the transaction is read committed,
             * make sure the record has not been updated.  Also, punt after
             * VIO_data () call which will release the page.
             */

            if ((transaction->tra_flags & TRA_read_committed) &&
                  (tid_fetch != rpb->rpb_transaction))
                        ERR_post(gds_deadlock, gds_arg_gds, gds_update_conflict, 0);

            rpb->rpb_stream_flags &= ~RPB_s_refetch;
      }

#ifdef PC_ENGINE
/* set up to do record locking; in case of a consistency
   mode transaction, we already have an exclusive lock on
   the table, so don't bother */

      try {

      LCK_RAII_wrapper implicit_lock;

      if (!(transaction->tra_flags & TRA_degree3))
      {
            /* check whether record locking is turned on */

            LCK record_locking = RLCK_record_locking(relation);
            if (record_locking->lck_physical != LCK_PR)
            {
                  /* get an implicit lock on the record */

                  implicit_lock.assign(implicit_record_lock(transaction, rpb));

                  /* set up to catch any errors so that we can 
                     release the implicit lock */
            }
      }
#endif

      if (transaction != dbb->dbb_sys_trans)
            ++transaction->tra_save_point->sav_verb_count;

/* Handle pre-operation trigger */
      PreModifyEraseTriggers(tdbb, &relation->rel_pre_erase,
                        which_trig, rpb, 0, jrd_req::req_trigger_delete);

      if (relation->rel_file)
            EXT_erase(rpb, reinterpret_cast < int *>(transaction));
      else if (!relation->rel_view_rse)
            VIO_erase(tdbb, rpb, transaction);
            
/* Handle post operation trigger */

      if (relation->rel_post_erase &&
            which_trig != PRE_TRIG &&
            (trigger = execute_triggers(tdbb, &relation->rel_post_erase,
                                                      rpb->rpb_record, 0,
                                                      jrd_req::req_trigger_delete)))
      {
            VIO_bump_count(tdbb, DBB_delete_count, relation, true);
            trigger_failure(tdbb, trigger);
      }

/* call IDX_erase (which checks constraints) after all post erase triggers 
   have fired. This is required for cascading referential integrity, which 
   can be implemented as post_erase triggers */

      if (!relation->rel_file & !relation->rel_view_rse)
      {
            JRD_REL bad_relation;
            USHORT bad_index;

            IDX_E error_code =
                  IDX_erase(tdbb, rpb, transaction, &bad_relation, &bad_index);

            if (error_code) {
                  VIO_bump_count(tdbb, DBB_delete_count, relation, true);
                  ERR_duplicate_error(error_code, bad_relation, bad_index);
            }
      }

      /* CVC: Increment the counter only if we called VIO/EXT_erase() and
                  we were successful. */
      if (!(request->req_view_flags & req_first_erase_return)) {
            request->req_view_flags |= req_first_erase_return;
            if (relation->rel_view_rse) {
                  request->req_top_view_erase = relation;
            }
      }
      if (relation == request->req_top_view_erase) {
            if (which_trig == ALL_TRIGS || which_trig == POST_TRIG) {
                  request->req_records_deleted++;
                  request->req_records_affected++;
            }
      }
      else if (relation->rel_file || !relation->rel_view_rse) {
            request->req_records_deleted++;
            request->req_records_affected++;
      }

      if (transaction != dbb->dbb_sys_trans) {
            --transaction->tra_save_point->sav_verb_count;
      }

#ifdef PC_ENGINE

      }     // try
      catch (const std::exception&) {
            Firebird::status_exception::raise(-1);
      }

/* if the stream is navigational, it is now positioned on a crack */

      if (rsb) {
            RSE_MARK_CRACK(tdbb, rsb, irsb_crack);
      }
#endif

      return node->nod_parent;
}


static void execute_looper(
                                       TDBB tdbb,
                                       JRD_REQ request,
                                       JRD_TRA transaction, ENUM jrd_req::req_s next_state)
{
/**************************************
 *
 *    e x e c u t e _ l o o p e r
 *
 **************************************
 *
 * Functional description
 *    Wrapper around looper. This will execute
 *    looper with the save point mechanism.
 *
 **************************************/
      DBB dbb;

      DEV_BLKCHK(request, type_req);

      SET_TDBB(tdbb);
      dbb = tdbb->tdbb_database;

/* Start a save point */

      if (!(request->req_flags & req_proc_fetch) && request->req_transaction)
            if (transaction && (transaction != dbb->dbb_sys_trans))
                  VIO_start_save_point(tdbb, transaction);

      request->req_flags &= ~req_stall;
      request->req_operation = next_state;

      looper(tdbb, request, request->req_next);

/* If any requested modify/delete/insert ops have completed, forget them */

      if (!(request->req_flags & req_proc_fetch) && request->req_transaction)
            if (transaction && (transaction != dbb->dbb_sys_trans) &&
                  transaction->tra_save_point &&
                  !transaction->tra_save_point->sav_verb_count) {
                  /* Forget about any undo for this verb */

                  VIO_verb_cleanup(tdbb, transaction);
            }
}


static void exec_sql(TDBB tdbb, JRD_REQ request, DSC* dsc)
{
/**************************************
 *
 *    e x e c _ s q l
 *
 **************************************
 *
 * Functional description
 *    Execute a string as SQL operator.
 *
 **************************************/

      SET_TDBB(tdbb);
      if (tdbb->tdbb_transaction->tra_callback_count >= MAX_CALLBACKS) {
            ERR_post(isc_exec_sql_max_call_exceeded, 0);
      }

      AutoPtr<str> SqlStatementText(ExecuteStatement::
            getString(tdbb->tdbb_transaction->tra_pool, dsc, request));

      ISC_STATUS_ARRAY local;
      memset(local, 0, sizeof(local));
      ISC_STATUS* status = local;

      tdbb->tdbb_transaction->tra_callback_count++;
      callback_execute_immediate(status,
                           tdbb->tdbb_attachment, tdbb->tdbb_transaction,
                           reinterpret_cast<TEXT *>(SqlStatementText->str_data), 
                           SqlStatementText->str_length);
      tdbb->tdbb_transaction->tra_callback_count--;

      if (status[1]) {
            memcpy(tdbb->tdbb_status_vector, status, sizeof(local));
            ERR_punt();
      }
}


static void execute_procedure(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    e x e c u t e _ p r o c e d u r e
 *
 **************************************
 *
 * Functional description
 *    Execute a stored procedure.  Begin by
 *    assigning the input parameters.  End
 *    by assigning the output parameters.
 *
 **************************************/
      JRD_REQ request, proc_request;
      JRD_NOD in_message, out_message, temp;
      FMT format;
      USHORT in_msg_length, out_msg_length;
      SCHAR *in_msg, *out_msg;
      JRD_PRC procedure;
      STR temp_buffer = NULL;
      SLONG save_point_number;
      JRD_TRA transaction;
      JrdMemoryPool *old_pool;

      SET_TDBB(tdbb);
      BLKCHK(node, type_nod);

      request = tdbb->tdbb_request;

      if ( (temp = node->nod_arg[e_esp_inputs]) ) {
            JRD_NOD *ptr, *end;

            for (ptr = temp->nod_arg, end = ptr + temp->nod_count; ptr < end;
                   ptr++)
                  EXE_assignment(tdbb, *ptr);
      }

      if ( (in_message = node->nod_arg[e_esp_in_msg]) ) {
            format = (FMT) in_message->nod_arg[e_msg_format];
            in_msg_length = format->fmt_length;
            in_msg = (SCHAR *) request + in_message->nod_impure;
      }
      if ( (out_message = node->nod_arg[e_esp_out_msg]) ) {
            format = (FMT) out_message->nod_arg[e_msg_format];
            out_msg_length = format->fmt_length;
            out_msg = (SCHAR *) request + out_message->nod_impure;
      }

      procedure = (JRD_PRC) node->nod_arg[e_esp_procedure];
      proc_request = EXE_find_request(tdbb, procedure->prc_request, FALSE);

      if (!out_message) {
            format = (FMT) procedure->prc_output_msg->nod_arg[e_msg_format];
            out_msg_length = format->fmt_length;
            temp_buffer =
                  FB_NEW_RPT(*tdbb->tdbb_default, out_msg_length + DOUBLE_ALIGN - 1) str();
            out_msg =
                  (SCHAR *) FB_ALIGN((U_IPTR) temp_buffer->str_data, DOUBLE_ALIGN);
      }

/* Save the old pool */

      old_pool = tdbb->tdbb_default;
      tdbb->tdbb_default = proc_request->req_pool;

/* Catch errors so we can unwind cleanly */

      try {

      transaction = request->req_transaction;
      save_point_number = transaction->tra_save_point->sav_number;

      proc_request->req_timestamp = request->req_timestamp;
      EXE_start(tdbb, proc_request, transaction);
      if (in_message)
            EXE_send(tdbb, proc_request, 0, in_msg_length,
                         reinterpret_cast < UCHAR * >(in_msg));

      EXE_receive(tdbb, proc_request, 1, out_msg_length,
                        reinterpret_cast < UCHAR * >(out_msg));

/* Clean up all savepoints started during execution of the
   procedure */

      if (transaction != tdbb->tdbb_database->dbb_sys_trans) {
            SAV save_point;

            for (save_point = transaction->tra_save_point;
                   save_point && save_point_number < save_point->sav_number;
                   save_point = transaction->tra_save_point)
                  VIO_verb_cleanup(tdbb, transaction);
      }

      }     // try
      catch (const std::exception&) {
            tdbb->tdbb_default = old_pool;
            tdbb->tdbb_request = request;
            EXE_unwind(tdbb, proc_request);
            proc_request->req_attachment = NULL;
            proc_request->req_flags &= ~(req_in_use | req_proc_fetch);
            proc_request->req_timestamp = 0;
            delete temp_buffer;
            Firebird::status_exception::raise(-1);
      }

      tdbb->tdbb_default = old_pool;
      EXE_unwind(tdbb, proc_request);
      tdbb->tdbb_request = request;

      temp = node->nod_arg[e_esp_outputs];
      if (temp) {
            JRD_NOD *ptr, *end;

            for (ptr = temp->nod_arg, end = ptr + temp->nod_count; ptr < end;
                   ptr++)
                  EXE_assignment(tdbb, *ptr);
      }

      delete temp_buffer;
      proc_request->req_attachment = NULL;
      proc_request->req_flags &= ~(req_in_use | req_proc_fetch);
      proc_request->req_timestamp = 0;
}


static JRD_REQ execute_triggers(TDBB tdbb,
                                                TRIG_VEC* triggers,
                                                REC old_rec,
                                                REC new_rec,
                                                ENUM jrd_req::req_ta trigger_action)
{
/**************************************
 *
 *    e x e c u t e _ t r i g g e r s
 *
 **************************************
 *
 * Functional description
 *    Execute group of triggers.  Return pointer to failing trigger
 *    if any blow up.
 *
 **************************************/

      volatile JRD_REQ trigger = NULL;

      //DEV_BLKCHK(*triggers, type_vec);
      DEV_BLKCHK(old_rec, type_rec);
      DEV_BLKCHK(new_rec, type_rec);

      if (!*triggers) {
            return NULL;
      }

      SET_TDBB(tdbb);

      JRD_TRA transaction = tdbb->tdbb_request->req_transaction;
      TRIG_VEC vector = *triggers;
      JRD_REQ result = NULL;

      try
      {
            for (trig_vec::iterator ptr = vector->begin(); ptr != vector->end(); ++ptr)
            {
                  ptr->compile(tdbb);
                  trigger = EXE_find_request(tdbb, ptr->request, FALSE);
                  trigger->req_rpb[0].rpb_record = old_rec;
                  trigger->req_rpb[1].rpb_record = new_rec;
                  trigger->req_timestamp = tdbb->tdbb_request->req_timestamp;
                  trigger->req_trigger_action = trigger_action;
                  EXE_start(tdbb, trigger, transaction);
                  trigger->req_attachment = NULL;
                  trigger->req_flags &= ~req_in_use;
                  trigger->req_timestamp = 0;
                  if (trigger->req_operation == jrd_req::req_unwind) {
                        result = trigger;
                        break;
                  }
                  trigger = (JRD_REQ)NULL_PTR;
            }

            if (vector != *triggers) {
                  MET_release_triggers(tdbb, &vector);
            }

            return result;

      }
      catch (const std::exception&)
      {
            if (vector != *triggers) {
                  MET_release_triggers(tdbb, &vector);
            }
            if (!trigger) {
              throw; // trigger probally fails to compile
              //Firebird::status_exception::raise(-1);
            }
            return trigger;
      }
}


#ifdef PC_ENGINE
static JRD_NOD find(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    f i n d
 *
 **************************************
 *
 * Functional description
 *    Find the given key value in a stream.
 *    Assume that the stream is open.
 *
 **************************************/

      SET_TDBB(tdbb);
      JRD_REQ request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

      if (request->req_operation == jrd_req::req_evaluate)
      {
            RSB rsb = *((RSB *) node->nod_arg[e_find_rsb]);

            USHORT operator_ =
                  (USHORT) MOV_get_long(EVL_expr(     tdbb,
                                                                  node->nod_arg
                                                                  [e_find_operator]),
                                                      0);
            if (operator_ != blr_eql &&
                  operator_ != blr_leq &&
                  operator_ != blr_lss &&
                  operator_ != blr_geq &&
                  operator_ != blr_gtr)
            {
                  ERR_post(gds_invalid_operator, 0);
            }

            USHORT direction = (USHORT) MOV_get_long(EVL_expr(tdbb,
                                                                           node->nod_arg
                                                                           [e_find_direction]),
                                                                           0);
            if (direction != blr_backward &&
                  direction != blr_forward &&
                  direction != blr_backward_starting &&
                  direction != blr_forward_starting)
            {
                  ERR_post(gds_invalid_direction, 0);
            }

            /* try to find the record; the position is defined to be on a crack 
               regardless of whether we are at BOF or EOF; also be sure to perpetuate
               the forced crack (bug #7024) */

            if (!RSE_find_record(   tdbb,
                                                rsb,
                                                operator_,
                                                direction,
                                                node->nod_arg[e_find_args]))
            {
                  if (EXE_crack(tdbb, rsb, irsb_bof | irsb_eof | irsb_crack))
                  {
                        if (EXE_crack(tdbb, rsb, irsb_forced_crack)) {
                              EXE_mark_crack(tdbb, rsb, irsb_crack | irsb_forced_crack);
                        } else if (EXE_crack(tdbb, rsb, irsb_bof)) {
                              EXE_mark_crack(tdbb, rsb, irsb_bof);
                        } else if (EXE_crack(tdbb, rsb, irsb_eof)) {
                              EXE_mark_crack(tdbb, rsb, irsb_eof);
                        } else {
                              EXE_mark_crack(tdbb, rsb, irsb_crack);
                        }
                  }
            }
            request->req_operation = jrd_req::req_return;
      }

      return node->nod_parent;
}
#endif


#ifdef PC_ENGINE
static JRD_NOD find_dbkey(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    f i n d _ d b k e y
 *
 **************************************
 *
 * Functional description
 *    Find the given dbkey in a navigational stream,
 *    resetting the position of the stream to that record.
 *
 **************************************/

      SET_TDBB(tdbb);
      JRD_REQ request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

      if (request->req_operation == jrd_req::req_evaluate)
      {
            RSB rsb = *((RSB *) node->nod_arg[e_find_dbkey_rsb]);

            if (!RSE_find_dbkey(tdbb,
                                          rsb,
                                          node->nod_arg[e_find_dbkey_dbkey],
                                          node->nod_arg[e_find_dbkey_version]))
            {
                    EXE_mark_crack(tdbb, rsb, irsb_crack);
            }

            request->req_operation = jrd_req::req_return;
      }

      return node->nod_parent;
}
#endif



#ifdef PC_ENGINE
static LCK implicit_record_lock(JRD_TRA transaction, RPB * rpb)
{
/**************************************
 *
 *    i m p l i c i t _ r e c o r d _ l o c k
 *
 **************************************
 *
 * Functional description
 *    An update to a record is being attempted and
 *    record locking has been initiated.  Take out
 *    an implicit record lock to prevent updating
 *    a record that someone has explicitly locked.
 *
 **************************************/

      TDBB tdbb = GET_THREAD_DATA;

      DEV_BLKCHK(transaction, type_tra);

      JRD_REL relation = rpb->rpb_relation;
      LCK record_locking = relation->rel_record_locking;

/* occasionally we should check whether we really still need to 
   do record locking; this is defined as RECORD_LOCK_CHECK_INTERVAL--
   if we can get a PR on the record locking lock there is no need
   to do implicit locking anymore */

      if ((record_locking->lck_physical == LCK_none) &&
            !(relation->rel_lock_total % RECORD_LOCK_CHECK_INTERVAL) &&
            LCK_lock_non_blocking(tdbb, record_locking, LCK_PR, FALSE))
      {
            return NULL;
      }

      LCK lock = RLCK_lock_record_implicit(transaction, rpb, LCK_SW, 0, 0);
      if (!lock) {
            ERR_post(gds_record_lock, 0);
      }

      return lock;
}
#endif


static JRD_NOD looper(TDBB tdbb, JRD_REQ request, JRD_NOD in_node)
{
/**************************************
 *
 *    l o o p e r
 *
 **************************************
 *
 * Functional description
 *    Cycle thru request execution tree.  Return next node for
 *    execution on stall or request complete.
 *
 **************************************/

      STA impure;
      SSHORT which_erase_trig = 0;
      SSHORT which_sto_trig   = 0;
      SSHORT which_mod_trig   = 0;
      volatile JRD_NOD top_node = 0;
      volatile JRD_NOD prev_node;
      JRD_TRA transaction;

/* If an error happens during the backout of a savepoint, then the transaction
   must be marked 'dead' because that is the only way to clean up after a
   failed backout.  The easiest way to do this is to kill the application
   by calling bugcheck.
   To facilitate catching errors during VIO_verb_cleanup, the following
   define is used. */
#define VERB_CLEANUP                                                    \
      try {                                                                   \
          VIO_verb_cleanup (tdbb, transaction);             \
    }                                                                         \
      catch (const std::exception&) {                                         \
            if (dbb->dbb_flags & DBB_bugcheck) {                        \
                  Firebird::status_exception::raise(tdbb->tdbb_status_vector[1]);   \
            }                                                                                               \
      BUGCHECK (290); /* msg 290 error during savepoint backout */      \
      }

      if (!(transaction = request->req_transaction)) {
            ERR_post(gds_req_no_trans, 0);
      }

      SET_TDBB(tdbb);
      DBB dbb = tdbb->tdbb_database;
      BLKCHK(in_node, type_nod);

      // Save the old pool and request to restore on exit

      JrdMemoryPool* old_pool = tdbb->tdbb_default;
      tdbb->tdbb_default = request->req_pool;

      JRD_REQ old_request = tdbb->tdbb_request;
      tdbb->tdbb_request = request;
      tdbb->tdbb_transaction = transaction;

      SLONG save_point_number = (transaction->tra_save_point) ?
            transaction->tra_save_point->sav_number : 0;

      volatile JRD_NOD node = in_node;

      // Catch errors so we can unwind cleanly

      bool error_pending = false;
      bool catch_disabled = false;

      // Execute stuff until we drop

      request->req_records_affected = 0;

      while (node && !(request->req_flags & req_stall))
      {
      try {

#ifdef SUPERSERVER

            if (request->req_operation == jrd_req::req_evaluate &&
                  (--tdbb->tdbb_quantum < 0) && !tdbb->tdbb_inhibit)
                  (void) JRD_reschedule(tdbb, 0, TRUE);

#endif

#if defined(DEBUG_GDS_ALLOC) && FALSE
            int node_type = node->nod_type;
#endif

            switch (node->nod_type) {
            case nod_asn_list:
                  if (request->req_operation == jrd_req::req_evaluate) {
                        volatile JRD_NOD *ptr, *end;

                        for (ptr = node->nod_arg, end = ptr + node->nod_count;
                               ptr < end; ptr++)
                              EXE_assignment(tdbb, *ptr);
                        request->req_operation = jrd_req::req_return;
                  }
                  node = node->nod_parent;
                  break;

            case nod_assignment:
                  if (request->req_operation == jrd_req::req_evaluate)
                        EXE_assignment(tdbb, node);
                  node = node->nod_parent;
                  break;

            case nod_dcl_variable:
                  {
                        VLU variable;

                        variable = (VLU) ((SCHAR *) request + node->nod_impure);
                        variable->vlu_desc = *(DSC *) (node->nod_arg + e_dcl_desc);
                        variable->vlu_desc.dsc_flags = 0;
                        variable->vlu_desc.dsc_address =
                              (UCHAR *) & variable->vlu_misc;
                        if (variable->vlu_desc.dsc_dtype <= dtype_varying
                              && !variable->vlu_string) {
                              variable->vlu_string =
                                    FB_NEW_RPT(*tdbb->tdbb_default,
                                                        variable->vlu_desc.dsc_length) str();
                              variable->vlu_string->str_length =
                                    variable->vlu_desc.dsc_length;
                              variable->vlu_desc.dsc_address =
                                    variable->vlu_string->str_data;
                        }
                        request->req_operation = jrd_req::req_return;
                        node = node->nod_parent;
                  }
                  break;

            case nod_erase:
                  if ((request->req_operation == jrd_req::req_return) &&
                        (node->nod_arg[e_erase_sub_erase]))
                  {
                        if (!top_node) {
                              top_node = node;
                              which_erase_trig = PRE_TRIG;
                        }
                        prev_node = node;
                        node = erase(tdbb, node, which_erase_trig);
                        if (which_erase_trig == PRE_TRIG) {
                              node = prev_node->nod_arg[e_erase_sub_erase];
                              node->nod_parent = prev_node;
                        }
                        if (top_node == prev_node && which_erase_trig == POST_TRIG) {
                              top_node = NULL;
                              which_erase_trig = ALL_TRIGS;
                        }
                        else
                              request->req_operation = jrd_req::req_evaluate;
                  }
                  else {
                        prev_node = node;
                        node = erase(tdbb, node, ALL_TRIGS);
                        if (!(prev_node->nod_arg[e_erase_sub_erase]) &&
                              which_erase_trig == PRE_TRIG)
                        {
                              which_erase_trig = POST_TRIG;
                        }
                  }
                  break;
            
            case nod_exec_proc:
                  if (request->req_operation == jrd_req::req_unwind) {
                        node = node->nod_parent;
                        break;
                  }
                  execute_procedure(tdbb, node);
                  node = node->nod_parent;
                  request->req_operation = jrd_req::req_return;
                  break;

            case nod_for:
                  switch (request->req_operation) {
                  case jrd_req::req_evaluate:
                        request->req_records_affected = 0;
                        RSE_open(tdbb, (RSB) node->nod_arg[e_for_rsb]);
                  case jrd_req::req_return:
                        if (node->nod_arg[e_for_stall]) {
                              node = node->nod_arg[e_for_stall];
                              break;
                        }
                  case jrd_req::req_sync:
                        if (RSE_get_record(tdbb, (RSB) node->nod_arg[e_for_rsb],
#ifdef SCROLLABLE_CURSORS
                                                   RSE_get_next))
#else
                                                   RSE_get_forward))
#endif
                        {
                              node = node->nod_arg[e_for_statement];
                              request->req_operation = jrd_req::req_evaluate;
                              break;
                        }
                        request->req_operation = jrd_req::req_return;
                  default:
                        RSE_close(tdbb, (RSB) node->nod_arg[e_for_rsb]);
                        node = node->nod_parent;
                  }
                  break;

            case nod_abort:
                  switch (request->req_operation) {
                  case jrd_req::req_evaluate:
                        {
                        XCP xcp_node = reinterpret_cast<XCP>(node->nod_arg[e_xcp_desc]);
                        if (xcp_node)
                        {
                              /* XCP is defined,
                                 so throw an exception */
                              set_error(tdbb, xcp_node, node->nod_arg[e_xcp_msg]);
                        }
                        else if (request->req_last_xcp.xcp_type != 0)
                        {
                              /* XCP is undefined, but there was a known exception before,
                                 so re-initiate it */
                              struct xcp last_error;
                              last_error.xcp_count = 1;
                              last_error.xcp_rpt[0].xcp_type = request->req_last_xcp.xcp_type;
                              last_error.xcp_rpt[0].xcp_code = request->req_last_xcp.xcp_code;
                              last_error.xcp_rpt[0].xcp_msg = request->req_last_xcp.xcp_msg;
                              request->req_last_xcp.xcp_type = 0;
                              request->req_last_xcp.xcp_msg = 0;
                              set_error(tdbb, &last_error, node->nod_arg[e_xcp_msg]);
                        }
                        else
                        {
                              /* XCP is undefined and there weren't any exceptions before,
                                 so just do nothing */
                              request->req_operation = jrd_req::req_return;
                        }
                        }

                  default:
                        node = node->nod_parent;
                  }
                  break;

            case nod_user_savepoint:
                  switch (request->req_operation) {
                  case jrd_req::req_evaluate:
                        if (transaction != dbb->dbb_sys_trans) {

                              UCHAR operation = (UCHAR) (IPTR) node->nod_arg[e_sav_operation];
                              TEXT * node_savepoint_name = (TEXT*) node->nod_arg[e_sav_name]; 

                              // Skip the savepoint created by EXE_start
                              SAV savepoint = transaction->tra_save_point->sav_next;
                              SAV previous = transaction->tra_save_point;

                              // Find savepoint
                              bool found = false;
                              while (true) {
                                    if (!savepoint || !(savepoint->sav_flags & SAV_user))
                                          break;

                                    if (!strcmp(node_savepoint_name, savepoint->sav_name)) {
                                          found = true;
                                          break;
                                    }

                                    previous = savepoint;
                                    savepoint = savepoint->sav_next;
                              }
                              if (!found && operation != blr_savepoint_set) {
                                    ERR_post(gds_invalid_savepoint,
                                          gds_arg_string, ERR_cstring(node_savepoint_name), 0);
                              }

                              if (operation == blr_savepoint_set) {

                                    // Release the savepoint
                                    if (found) {
                                          previous->sav_next = savepoint->sav_next;
                                          SAV current = transaction->tra_save_point;
                                          transaction->tra_save_point = savepoint;
                                          VERB_CLEANUP;
                                          transaction->tra_save_point = current;
                                    }

                                    // Use the savepoint created by EXE_start
                                    transaction->tra_save_point->sav_flags |= SAV_user;
                                    strcpy(transaction->tra_save_point->sav_name, node_savepoint_name);
                              }
                              else if (operation == blr_savepoint_release_single) {

                                    // Release the savepoint
                                    previous->sav_next = savepoint->sav_next;
                                    SAV current = transaction->tra_save_point;
                                    transaction->tra_save_point = savepoint;
                                    VERB_CLEANUP;
                                    transaction->tra_save_point = current;
                              }
                              else if (operation == blr_savepoint_release) {
                                    SLONG sav_number = savepoint->sav_number;

                                    // Release the savepoint and all subsequent ones
                                    while (transaction->tra_save_point &&
                                          transaction->tra_save_point->sav_number >= sav_number) 
                                    {
                                          VERB_CLEANUP;
                                    }

                                    // Restore the savepoint initially created by EXE_start
                                    VIO_start_save_point(tdbb, transaction);
                              }
                              else if (operation == blr_savepoint_undo) {
                                    SLONG sav_number = savepoint->sav_number;

                                    // Undo the savepoint
                                    while (transaction->tra_save_point &&
                                          transaction->tra_save_point->sav_number >= sav_number) 
                                    {
                                          transaction->tra_save_point->sav_verb_count++;
                                          VERB_CLEANUP;
                                    }

                                    // Now set the savepoint again to allow to return to it later
                                    VIO_start_save_point(tdbb, transaction);
                                    transaction->tra_save_point->sav_flags |= SAV_user;
                                    strcpy(transaction->tra_save_point->sav_name, node_savepoint_name);
                              }
                              else {
                                    BUGCHECK(232);
                              }
                        }
                  default:
                        node = node->nod_parent;
                        request->req_operation = jrd_req::req_return;
                  }
                  break;

            case nod_start_savepoint:
                  switch (request->req_operation) {
                  case jrd_req::req_evaluate:
                        /* Start a save point */

                        if (transaction != dbb->dbb_sys_trans)
                              VIO_start_save_point(tdbb, transaction);

                  default:
                        node = node->nod_parent;
                        request->req_operation = jrd_req::req_return;
                  }
                  break;

            case nod_end_savepoint:
                  switch (request->req_operation) {
                  case jrd_req::req_evaluate:
                  case jrd_req::req_unwind:
                        /* If any requested modify/delete/insert
                           ops have completed, forget them */
                        if (transaction != dbb->dbb_sys_trans) {
                              /* If an error is still pending when the savepoint is 
                                 supposed to end, then the application didn't handle the
                                 error and the savepoint should be undone. */
                              if (error_pending) {
                                    ++transaction->tra_save_point->sav_verb_count;
                              }
                              VERB_CLEANUP;
                        }

                  default:
                        node = node->nod_parent;
                        request->req_operation = jrd_req::req_return;
                  }
                  break;

            case nod_handler:
                  switch (request->req_operation) {
                  case jrd_req::req_evaluate:
                        node = node->nod_arg[0];
                        break;

                  case jrd_req::req_unwind:
                        if (!request->req_label)
                              request->req_operation = jrd_req::req_return;

                  default:
                        node = node->nod_parent;
                  }
                  break;

            case nod_block:
                  switch (request->req_operation) {
                        SLONG count;
                        SAV save_point;

                  case jrd_req::req_evaluate:
                        if (transaction != dbb->dbb_sys_trans) {
                              VIO_start_save_point(tdbb, transaction);
                              save_point = transaction->tra_save_point;
                              count = save_point->sav_number;
                              MOVE_FAST(&count,
                                            (SCHAR *) request + node->nod_impure,
                                            sizeof(SLONG));
                        }
                        node = node->nod_arg[e_blk_action];
                        break;

                  case jrd_req::req_unwind:
                        {
                              volatile JRD_NOD *ptr, *end;

                              if (request->req_flags & req_leave)
                              {
                                    // Although the req_operation is set to req_unwind,
                                    // it's not an error case if req_leave bit is set.
                                    // req_leave bit indicates that we hit an EXIT or
                                    // BREAK/LEAVE statement in the SP/trigger code.
                                    // Do not perform the error handling stuff.
                                    if (transaction != dbb->dbb_sys_trans) {
                                          MOVE_FAST((SCHAR *) request + node->nod_impure,
                                                        &count, sizeof(SLONG));
                                          for (save_point = transaction->tra_save_point;
                                                 save_point && count <= save_point->sav_number;
                                                 save_point = transaction->tra_save_point)
                                                VERB_CLEANUP;
                                    }
                                    node = node->nod_parent;
                                    break;
                              }
                              if (transaction != dbb->dbb_sys_trans)
                              {
                                    MOVE_FAST((SCHAR *) request + node->nod_impure,
                                                  &count, sizeof(SLONG));
                                    /* Since there occurred an error (req_unwind), undo all savepoints
                                       up to, but not including, the savepoint of this block.  The
                                       savepoint of this block will be dealt with below. */
                                    for (save_point = transaction->tra_save_point;
                                           save_point && count < save_point->sav_number;
                                           save_point = transaction->tra_save_point) {
                                          ++transaction->tra_save_point->sav_verb_count;
                                          VERB_CLEANUP;
                                    }
                              }

                              volatile JRD_NOD handlers = node->nod_arg[e_blk_handlers];
                              if (handlers)
                              {
                                    ULONG prev_req_error_handler;

                                    node = node->nod_parent;
                                    for (ptr = handlers->nod_arg,
                                           end = ptr + handlers->nod_count; ptr < end;
                                           ptr++)
                                    {
                                          const XCP xcp_node =
                                                reinterpret_cast<XCP>((*ptr)->nod_arg[e_err_conditions]);
                                          if (test_and_fixup_error(tdbb, xcp_node, request))
                                          {
                                                request->req_operation = jrd_req::req_evaluate;
                                                node = (*ptr)->nod_arg[e_err_action];
                                                error_pending = false;
                                                catch_disabled = true;

                                                /* On entering looper old_request etc. are saved.
                                                   On recursive calling we will loose the actual old
                                                   request for that invocation of looper. Avoid this. */

                                                tdbb->tdbb_default = old_pool;
                                                tdbb->tdbb_request = old_request;

                                                /* Save the previous state of req_error_handler
                                                   bit. We need to restore it later. This is
                                                   necessary if the error handler is deeply 
                                                   nested. */

                                                prev_req_error_handler =
                                                      request->req_flags & req_error_handler;
                                                request->req_flags |= req_error_handler;
                                                node = looper(tdbb, request, node);
                                                request->req_flags &= ~(req_error_handler);
                                                request->req_flags |= prev_req_error_handler;

                                                /* Note: Previously the above call
                                                   "node = looper (tdbb, request, node);"
                                                   never returned back till the node tree
                                                   was executed completely. Now that the looper
                                                   has changed its behaviour such that it
                                                   returns back after handling error. This 
                                                   makes it necessary that the jmpbuf be reset
                                                   so that looper can proceede with the 
                                                   preocessing of execution tree. If this is
                                                   not done then anymore errors will take the
                                                   engine out of looper there by abruptly
                                                   terminating the processing. */

                                                catch_disabled = false;
                                                tdbb->tdbb_default = request->req_pool;
                                                tdbb->tdbb_request = request;

                                                /* The error is dealt with by the application, cleanup
                                                   this block's savepoint. */

                                                if (transaction != dbb->dbb_sys_trans)
                                                {
                                                      for (save_point = transaction->tra_save_point;
                                                             save_point &&
                                                                   count <= save_point->sav_number;
                                                             save_point = transaction->tra_save_point)
                                                      {
                                                            VERB_CLEANUP;
                                                      }
                                                }
                                          }
                                    }
                              }
                              else
                              {
                                    node = node->nod_parent;
                              }

                              /* If the application didn't have an error handler, then
                                 the error will still be pending.  Undo the block by
                                 using its savepoint. */

                              if (error_pending && transaction != dbb->dbb_sys_trans) {
                                    ++transaction->tra_save_point->sav_verb_count;
                                    VERB_CLEANUP;
                              }
                        }
                        break;

                  case jrd_req::req_return:
                        if (transaction != dbb->dbb_sys_trans) {
                              MOVE_FAST((SCHAR *) request + node->nod_impure,
                                            &count, sizeof(SLONG));
                              for (save_point = transaction->tra_save_point;
                                     save_point && count <= save_point->sav_number;
                                     save_point = transaction->tra_save_point)
                                    VERB_CLEANUP;
                        }
                  default:
                        node = node->nod_parent;
                  }
                  break;

            case nod_error_handler:
                  if (request->req_flags & req_error_handler && !error_pending) {
                        return node;
                  }
                  node = node->nod_parent;
                  node = node->nod_parent;
                  if (request->req_operation == jrd_req::req_unwind)
                        node = node->nod_parent;
                  request->req_last_xcp.xcp_type = 0;
                  break;

            case nod_label:
                  switch (request->req_operation) {
                  case jrd_req::req_evaluate:
                        node = node->nod_arg[e_lbl_statement];
                        break;

                  case jrd_req::req_unwind:
                        if ((request->req_label == (USHORT) (IPTR) node->nod_arg[e_lbl_label]) &&
                                    (request->req_flags & (req_leave | req_error_handler))) {
                              request->req_flags &= ~req_leave;
                              request->req_operation = jrd_req::req_return;
                        }

                  default:
                        node = node->nod_parent;
                  }
                  break;

            case nod_leave:
                  request->req_flags |= req_leave;
                  request->req_operation = jrd_req::req_unwind;
                  request->req_label = (USHORT) (IPTR) node->nod_arg[0];
                  node = node->nod_parent;
                  break;

            case nod_list:
                  impure = (STA) ((SCHAR *) request + node->nod_impure);
                  switch (request->req_operation) {
                  case jrd_req::req_evaluate:
                        impure->sta_state = 0;
                  case jrd_req::req_return:
                  case jrd_req::req_sync:
                        if (impure->sta_state < node->nod_count) {
                              request->req_operation = jrd_req::req_evaluate;
                              node = node->nod_arg[impure->sta_state++];
                              break;
                        }
                        request->req_operation = jrd_req::req_return;
                  default:
                        node = node->nod_parent;
                  }
                  break;

            case nod_loop:
                  switch (request->req_operation) {
                  case jrd_req::req_evaluate:
                  case jrd_req::req_return:
                        node = node->nod_arg[0];
                        request->req_operation = jrd_req::req_evaluate;
                        break;

                  default:
                        node = node->nod_parent;
                  }
                  break;

            case nod_if:
                  if (request->req_operation == jrd_req::req_evaluate)
                        if (EVL_boolean(tdbb, node->nod_arg[e_if_boolean])) {
                              node = node->nod_arg[e_if_true];
                              request->req_operation = jrd_req::req_evaluate;
                              break;
                        }
                        else if (node->nod_arg[e_if_false]) {
                              node = node->nod_arg[e_if_false];
                              request->req_operation = jrd_req::req_evaluate;
                              break;
                        }
                        else
                              request->req_operation = jrd_req::req_return;
                  node = node->nod_parent;
                  break;

            case nod_modify:
                  impure = (STA) ((SCHAR *) request + node->nod_impure);
                  if ((request->req_operation == jrd_req::req_return) &&
                        (!impure->sta_state) && (node->nod_arg[e_mod_sub_mod])) {
                        if (!top_node) {
                              top_node = node;
                              which_mod_trig = PRE_TRIG;
                        }
                        prev_node = node;
                        node = modify(tdbb, node, which_mod_trig);
                        if (which_mod_trig == PRE_TRIG) {
                              node = prev_node->nod_arg[e_mod_sub_mod];
                              node->nod_parent = prev_node;
                        }
                        if (top_node == prev_node && which_mod_trig == POST_TRIG) {
                              top_node = NULL;
                              which_mod_trig = ALL_TRIGS;
                        }
                        else {
                              request->req_operation = jrd_req::req_evaluate;
                        }
                  }
                  else {
                        prev_node = node;
                        node = modify(tdbb, node, ALL_TRIGS);
                        if (!(prev_node->nod_arg[e_mod_sub_mod]) &&
                              which_mod_trig == PRE_TRIG)
                        {
                              which_mod_trig = POST_TRIG;
                        }
                  }

                  break;

            case nod_nop:
                  request->req_operation = jrd_req::req_return;
                  node = node->nod_parent;
                  break;

            case nod_receive:
                  node = receive_msg(tdbb, node);
                  break;

            case nod_exec_sql:
                  if (request->req_operation == jrd_req::req_unwind) {
                        node = node->nod_parent;
                        break;
                  }
                  exec_sql(tdbb, request, EVL_expr(tdbb, node->nod_arg[0]));
                  if (request->req_operation == jrd_req::req_evaluate)
                        request->req_operation = jrd_req::req_return;
                  node = node->nod_parent;
                  break;

            case nod_exec_into: 
                  {
                  class ExecuteStatement * impure = 
                        (class ExecuteStatement *) 
                              ((SCHAR *) request + node->nod_impure);
                  switch (request->req_operation) {
                  case jrd_req::req_evaluate:
                        impure->Open(tdbb, node->nod_arg[0], node->nod_count - 2, 
                                    node->nod_arg[1] ? false : true);
                  case jrd_req::req_return:
                  case jrd_req::req_sync:
                        if (impure->Fetch(tdbb, &node->nod_arg[2])) {
                              request->req_operation = jrd_req::req_evaluate;
                              node = node->nod_arg[1];
                              break;
                        }
                        request->req_operation = jrd_req::req_return;
                  default:
                        // if have active opened request - close it
                        impure->Close(tdbb);
                        node = node->nod_parent;
                  }
                  }
                  break;

            case nod_post:
                  {
                  DFW work = DFW_post_work(transaction, dfw_post_event,
                                                       EVL_expr(tdbb, node->nod_arg[0]), 0);
                  if (node->nod_arg[1])
                        DFW_post_work_arg(transaction, work,
                                                  EVL_expr(tdbb, node->nod_arg[1]), 0);
                  }

                  /* for an autocommit transaction, events can be posted
                   * without any updates */

                  if (transaction->tra_flags & TRA_autocommit)
                        transaction->tra_flags |= TRA_perform_autocommit;
            case nod_message:
                  if (request->req_operation == jrd_req::req_evaluate)
                        request->req_operation = jrd_req::req_return;
                  node = node->nod_parent;
                  break;

            case nod_stall:
                  node = stall(tdbb, node);
                  break;

            case nod_select:
                  node = selct(tdbb, node);
                  break;

            case nod_send:
                  node = send_msg(tdbb, node);
                  break;

            case nod_store:
                  impure = (STA) ((SCHAR *) request + node->nod_impure);
                  if ((request->req_operation == jrd_req::req_return) &&
                        (!impure->sta_state) && (node->nod_arg[e_sto_sub_store])) {
                        if (!top_node) {
                              top_node = node;
                              which_sto_trig = PRE_TRIG;
                        }
                        prev_node = node;
                        node = store(tdbb, node, which_sto_trig);
                        if (which_sto_trig == PRE_TRIG) {
                              node = prev_node->nod_arg[e_sto_sub_store];
                              node->nod_parent = prev_node;
                        }
                        if (top_node == prev_node && which_sto_trig == POST_TRIG) {
                              top_node = NULL;
                              which_sto_trig = ALL_TRIGS;
                        }
                        else
                              request->req_operation = jrd_req::req_evaluate;
                  }
                  else {
                        prev_node = node;
                        node = store(tdbb, node, ALL_TRIGS);
                        if (!(prev_node->nod_arg[e_sto_sub_store]) &&
                              which_sto_trig == PRE_TRIG)
                              which_sto_trig = POST_TRIG;
                  }

                  break;

#ifdef SCROLLABLE_CURSORS
            case nod_seek:
                  node = seek_rse(tdbb, request, node);
                  break;
#endif

#ifdef PC_ENGINE
            case nod_stream:
                  node = stream(tdbb, node);
                  break;

            case nod_find:
                  node = find(tdbb, node);
                  break;

            case nod_find_dbkey:
            case nod_find_dbkey_version:
                  node = find_dbkey(tdbb, node);
                  break;

            case nod_set_index:
                  node = set_index(tdbb, node);
                  break;

            case nod_set_bookmark:
                  node = set_bookmark(tdbb, node);
                  break;

            case nod_release_bookmark:
                  node = release_bookmark(tdbb, node);
                  break;

            case nod_end_range:
                  node = RNG_end(node);
                  break;

            case nod_delete_range:
                  node = RNG_delete(node);
                  break;

            case nod_delete_ranges:
                  if (request->req_operation == jrd_req::req_evaluate) {
                        RNG_delete_ranges(request);
                        request->req_operation = jrd_req::req_return;
                  }
                  node = node->nod_parent;
                  break;

            case nod_range_relation:
                  node = RNG_add_relation(node);
                  break;

            case nod_release_lock:
                  if (request->req_operation == jrd_req::req_evaluate) {
                        DSC *desc;

                        desc = EVL_expr(tdbb, node->nod_arg[e_rellock_lock]);
#if SIZEOF_VOID_P != 8
                        RLCK_release_lock(*(LCK *) desc->dsc_address);
#else
                        {
                              ATT attachment;
                              LCK lock;
                              ULONG slot;
                              VEC vector;

                              attachment = tdbb->tdbb_attachment;

                              lock = NULL;
                              slot = *(ULONG *) desc->dsc_address;
                              if ((vector = attachment->att_lck_quick_ref) &&
                                    slot < vector->vec_count)
                                          lock = (LCK) vector->vec_object[slot];
                              RLCK_release_lock(lock);
                              vector->vec_object[slot] = NULL;
                        }
#endif
                        request->req_operation = jrd_req::req_return;
                  }
                  node = node->nod_parent;
                  break;

            case nod_release_locks:
                  if (request->req_operation == jrd_req::req_evaluate) {
                        RLCK_release_locks(request->req_attachment);
                        request->req_operation = jrd_req::req_return;
                  }
                  node = node->nod_parent;
                  break;

            case nod_force_crack:
                  if (request->req_operation == jrd_req::req_evaluate) {
                        RSE_MARK_CRACK(tdbb, *(RSB *) node->nod_arg[1],
                                             irsb_crack | irsb_forced_crack);
                        request->req_operation = jrd_req::req_return;
                  }
                  node = node->nod_parent;
                  break;

            case nod_reset_stream:
                  if (request->req_operation == jrd_req::req_evaluate) {
                        RSE_reset_position(tdbb,
                                                   *(RSB *) node->nod_arg[e_reset_from_rsb],
                                                   request->req_rpb +
                                                   (USHORT) (IPTR) node->nod_arg[e_reset_to_stream]);
                        request->req_operation = jrd_req::req_return;
                  }
                  node = node->nod_parent;
                  break;
#endif

            case nod_set_generator:
                  if (request->req_operation == jrd_req::req_evaluate) {
                        DSC *desc;

                        desc = EVL_expr(tdbb, node->nod_arg[e_gen_value]);
                        (void) DPM_gen_id(tdbb, (SLONG) node->nod_arg[e_gen_id], 1,
                                                  MOV_get_int64(desc, 0));
                        request->req_operation = jrd_req::req_return;
                  }
                  node = node->nod_parent;
                  break;

            case nod_set_generator2:
                  if (request->req_operation == jrd_req::req_evaluate) {
                        DSC *desc;

                        desc = EVL_expr(tdbb, node->nod_arg[e_gen_value]);
                        (void) DPM_gen_id(tdbb, (SLONG) node->nod_arg[e_gen_id], 1,
                                                  MOV_get_int64(desc, 0));
                        request->req_operation = jrd_req::req_return;
                  }
                  node = node->nod_parent;
                  break;

            default:
                  BUGCHECK(168);          /* msg 168 looper: action not yet implemented */
            }

//#if defined(DEBUG_GDS_ALLOC) && defined(PROD_BUILD)
//          memory_count++;
//          if ((memory_count % memory_debug) == 0) {
//                ALL_check_memory();
//          }
//#endif
      }     // try
      catch (const std::exception&) {
            // If we already have a handled error, and took another, simply
            // pass the buck.
            if (catch_disabled) {
                  Firebird::status_exception::raise(tdbb->tdbb_status_vector[1]);
            }

            /* If the database is already bug-checked, then get out. */
            if (dbb->dbb_flags & DBB_bugcheck) {
                  Firebird::status_exception::raise(tdbb->tdbb_status_vector[1]);
            }

            /* Since an error happened, the current savepoint needs to be undone. */            
            if (transaction != dbb->dbb_sys_trans) {
                  ++transaction->tra_save_point->sav_verb_count;
                  VERB_CLEANUP;
            }

            error_pending = true;
            request->req_operation = jrd_req::req_unwind;
            request->req_label = 0;
      }
      } // while()

/* if there is no node, assume we have finished processing the 
   request unless we are in the middle of processing an asynchronous message */

      if (!node
#ifdef SCROLLABLE_CURSORS
            && !(request->req_flags & req_async_processing)
#endif
            )
      {
            request->req_flags &= ~(req_active | req_reserved);
            request->req_timestamp = 0;
            release_blobs(tdbb, request);
      }

      request->req_next = node;
      tdbb->tdbb_default = old_pool;
      tdbb->tdbb_transaction = (tdbb->tdbb_request = old_request) ?
            old_request->req_transaction : NULL;

      // in the case of a pending error condition (one which did not
      // result in a exception to the top of looper), we need to
      // delete the last savepoint
      
      if (error_pending) {
            if (transaction != dbb->dbb_sys_trans) {
                  SAV save_point;

                  for (save_point = transaction->tra_save_point; ((save_point)
                                                                                          &&
                                                                                          (save_point_number
                                                                                           <= save_point->
                                                                                           sav_number));
                         save_point = transaction->tra_save_point) {
                        ++transaction->tra_save_point->sav_verb_count;
                        VERB_CLEANUP;
                  }
            }

            ERR_punt();
      }

      // if the request was aborted, assume that we have already
      // longjmp'ed to the top of looper, and therefore that the
      // last savepoint has already been deleted

      if (request->req_flags & req_abort) {
            ERR_post(gds_req_sync, 0);
      }

      return node;
}


static JRD_NOD modify(TDBB tdbb, JRD_NOD node, SSHORT which_trig)
{
/**************************************
 *
 *    m o d i f y
 *
 **************************************
 *
 * Functional description
 *    Execute a MODIFY statement.
 *
 **************************************/
      DBB dbb;
      JRD_REQ request, trigger;
      STA impure;
      FMT org_format, new_format;
      SSHORT org_stream, new_stream;
      REC org_record, new_record;
      RPB *org_rpb, *new_rpb;
      JRD_REL relation;
      JRD_TRA transaction;
#ifdef PC_ENGINE
      RSB rsb = NULL;
      LCK record_locking;
      IRSB irsb;
#endif

      SET_TDBB(tdbb);
      dbb = tdbb->tdbb_database;
      BLKCHK(node, type_nod);

      request = tdbb->tdbb_request;
      transaction = request->req_transaction;
      impure = (STA) ((SCHAR *) request + node->nod_impure);

      org_stream = (USHORT) (IPTR) node->nod_arg[e_mod_org_stream];
      org_rpb = &request->req_rpb[org_stream];
      relation = org_rpb->rpb_relation;

      new_stream = (USHORT) (IPTR) node->nod_arg[e_mod_new_stream];
      new_rpb = &request->req_rpb[new_stream];

#ifdef PC_ENGINE
/* for navigational streams, retrieve the rsb */

      if (node->nod_arg[e_mod_rsb]) {
            rsb = *(RSB *) node->nod_arg[e_mod_rsb];
            irsb = (IRSB) ((UCHAR *) request + rsb->rsb_impure);
      }

/* if we are on a crack in a navigational stream, modify is an illegal operation */

      if (rsb && EXE_crack(tdbb, rsb, irsb_bof | irsb_eof | irsb_crack)) {
            EXE_mark_crack(tdbb, rsb, irsb->irsb_flags);
            request->req_operation = jrd_req::req_return;
            return node->nod_parent;
      }
#endif

/* If the stream was sorted, the various fields in the rpb are
   probably junk.  Just to make sure that everything is cool,
   refetch and release the record. */

      if (org_rpb->rpb_stream_flags & RPB_s_refetch) {
            SLONG tid_fetch;

            tid_fetch = org_rpb->rpb_transaction;
            if ((!DPM_get(tdbb, org_rpb, LCK_read)) ||
                  (!VIO_chase_record_version(tdbb,
                                                         org_rpb,
                                                         NULL,
                                                         transaction,
                                                         reinterpret_cast<BLK>(tdbb->tdbb_default),FALSE)))
            {
                        ERR_post(gds_deadlock, gds_arg_gds, gds_update_conflict, 0);
            }
            VIO_data(tdbb, org_rpb,
                         reinterpret_cast<BLK>(tdbb->tdbb_request->req_pool));

            /* If record is present, and the transaction is read committed,
             * make sure the record has not been updated.  Also, punt after
             * VIO_data () call which will release the page.
             */

            if ((transaction->tra_flags & TRA_read_committed) &&
                  (tid_fetch != org_rpb->rpb_transaction))
            {
                        ERR_post(gds_deadlock, gds_arg_gds, gds_update_conflict, 0);
            }

            org_rpb->rpb_stream_flags &= ~RPB_s_refetch;
      }

      switch (request->req_operation) {
      case jrd_req::req_evaluate:
            break;

      case jrd_req::req_return:
            if (impure->sta_state) {
                  impure->sta_state = 0;
                  org_record = org_rpb->rpb_record;
                  new_record = new_rpb->rpb_record;
                  MOVE_FASTER(new_record->rec_data, org_record->rec_data,
                                    new_record->rec_length);
                  request->req_operation = jrd_req::req_evaluate;
                  return node->nod_arg[e_mod_statement];
            }

            /* CVC: This call made here to clear the record in each NULL field and
                        varchar field whose tail may contain garbage. */
            cleanup_rpb(tdbb, new_rpb);

#ifdef PC_ENGINE
            /* check to see if record locking has been initiated in this database;
               if so then lock the record for shared write so that normal processing
               will be able to read or write the record but not when an explicit
               lock has been taken out */

            try
            {

            LCK_RAII_wrapper implicit_lock;

            if (!(transaction->tra_flags & TRA_degree3))
            {
                  record_locking = RLCK_record_locking(relation);
                  if (record_locking->lck_physical != LCK_PR)
                  {
                        implicit_lock.assign(implicit_record_lock(transaction, org_rpb));
                  }
            }
#endif

            if (transaction != dbb->dbb_sys_trans)
                  ++transaction->tra_save_point->sav_verb_count;

            PreModifyEraseTriggers(tdbb, &relation->rel_pre_modify,
                        which_trig, org_rpb, new_rpb->rpb_record, 
                        jrd_req::req_trigger_update);

            if (node->nod_arg[e_mod_validate]) {
                  validate(tdbb, node->nod_arg[e_mod_validate]);
            }

            if (relation->rel_file)
            {
                  EXT_modify(org_rpb, new_rpb,
                                 reinterpret_cast<int*>(transaction));
            }
            else if (!relation->rel_view_rse)
            {
                  USHORT bad_index;
                  JRD_REL bad_relation;

                  VIO_modify(tdbb, org_rpb, new_rpb, transaction);

                  IDX_E error_code = IDX_modify(tdbb,
                                                              org_rpb,
                                                              new_rpb,
                                                              transaction,
                                                              &bad_relation,
                                                              &bad_index);
                  if (error_code) {
                        VIO_bump_count(tdbb, DBB_update_count, bad_relation, true);
                        ERR_duplicate_error(error_code, bad_relation, bad_index);
                  }
            }

            if (relation->rel_post_modify &&
                  which_trig != PRE_TRIG &&
                  (trigger = execute_triggers(tdbb, &relation->rel_post_modify,
                                                            org_rpb->rpb_record,
                                                            new_rpb->rpb_record,
                                                            jrd_req::req_trigger_update)))
            {
                  VIO_bump_count(tdbb, DBB_update_count, relation, true);
                  trigger_failure(tdbb, trigger);
            }

            /* now call IDX_modify_check_constrints after all post modify triggers 
               have fired.  This is required for cascading referential integrity, 
               which can be implemented as post_erase triggers */

            if (!relation->rel_file && !relation->rel_view_rse)
            {
                  USHORT bad_index;
                  JRD_REL bad_relation;

                  IDX_E error_code = IDX_modify_check_constraints(tdbb,
                                                                                          org_rpb,
                                                                                          new_rpb,
                                                                                          transaction,
                                                                                          &bad_relation,
                                                                                          &bad_index);
                  if (error_code) {
                        VIO_bump_count(tdbb, DBB_update_count, relation, true);
                        ERR_duplicate_error(error_code, bad_relation, bad_index);
                  }
            }

            if (transaction != dbb->dbb_sys_trans) {
                  --transaction->tra_save_point->sav_verb_count;
            }

#ifdef PC_ENGINE

            }     // try
            catch (const std::exception&) {
                  Firebird::status_exception::raise(-1);
            }

            /* if the stream is navigational, we must position the stream on the new 
               record version, but first set the record number  */

            new_rpb->rpb_number = org_rpb->rpb_number;
            if (rsb) {
                  RSE_reset_position(tdbb, rsb, new_rpb);
            }
#endif

            /* CVC: Increment the counter only if we called VIO/EXT_modify() and
                        we were successful. */
            if (!(request->req_view_flags & req_first_modify_return)) {
                  request->req_view_flags |= req_first_modify_return;
                  if (relation->rel_view_rse) {
                        request->req_top_view_modify = relation;
                  }
            }
            if (relation == request->req_top_view_modify) {
                  if (which_trig == ALL_TRIGS || which_trig == POST_TRIG) {
                        request->req_records_updated++;
                        request->req_records_affected++;
                  }
            }
            else if (relation->rel_file || !relation->rel_view_rse) {
                  request->req_records_updated++;
                  request->req_records_affected++;
            }

            if (which_trig != PRE_TRIG) {
                  org_record = org_rpb->rpb_record;
                  org_rpb->rpb_record = new_rpb->rpb_record;
                  new_rpb->rpb_record = org_record;
            }

      default:
            return node->nod_parent;
      }

      impure->sta_state = 0;
      RLCK_reserve_relation(tdbb, transaction, relation, TRUE, TRUE);

/* Fall thru on evaluate to set up for modify before executing sub-statement.
   This involves finding the appropriate format, making sure a record block
   exists for the stream and is big enough, and copying fields from the
   original record to the new record. */

      new_format = MET_current(tdbb, new_rpb->rpb_relation);
      new_record = VIO_record(tdbb, new_rpb, new_format, tdbb->tdbb_default);
      new_rpb->rpb_address = new_record->rec_data;
      new_rpb->rpb_length = new_format->fmt_length;
      new_rpb->rpb_format_number = new_format->fmt_version;

      if (!(org_record = org_rpb->rpb_record)) {
            org_record =
                  VIO_record(tdbb, org_rpb, new_format, tdbb->tdbb_default);
            org_format = org_record->rec_format;
            org_rpb->rpb_address = org_record->rec_data;
            org_rpb->rpb_length = org_format->fmt_length;
            org_rpb->rpb_format_number = org_format->fmt_version;
      }
      else
            org_format = org_record->rec_format;

/* Copy the original record to the new record.  If the format hasn't changed,
   this is a simple move.  If the format has changed, each field must be
   fetched and moved separately, remembering to set the missing flag. */

      if (new_format->fmt_version == org_format->fmt_version)
            MOVE_FASTER(org_record->rec_data, new_rpb->rpb_address,
                              new_rpb->rpb_length);
      else {
            SSHORT i;
            DSC org_desc, new_desc;

            for (i = 0; i < new_format->fmt_count; i++) {
                  /* In order to "map a null to a default" value (in EVL_field()), 
                   * the relation block is referenced. 
                   * Reference: Bug 10116, 10424 
                   */
                  CLEAR_NULL(new_record, i);
                  if (EVL_field(new_rpb->rpb_relation, new_record, i, &new_desc)) {
                        if (EVL_field
                              (org_rpb->rpb_relation, org_record, i,
                               &org_desc)) MOV_move(&org_desc, &new_desc);
                        else {
                              SET_NULL(new_record, i);
                              if (new_desc.dsc_dtype) {
                                    UCHAR *p;
                                    USHORT n;

                                    p = new_desc.dsc_address;
                                    n = new_desc.dsc_length;
                                    do
                                          *p++ = 0;
                                    while (--n);
                              }
                        }                       /* if (org_record) */
                  }                             /* if (new_record) */
            }                                   /* for (fmt_count) */
      }

      if (node->nod_arg[e_mod_map_view]) {
            impure->sta_state = 1;
            return node->nod_arg[e_mod_map_view];
      }

      return node->nod_arg[e_mod_statement];
}

static JRD_NOD receive_msg(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    r e c e i v e _ m s g
 *
 **************************************
 *
 * Functional description
 *    Execute a RECEIVE statement.  This can be entered either
 *    with "req_evaluate" (ordinary receive statement) or
 *    "req_proceed" (select statement).  In the latter case,
 *    the statement isn't every formalled evaluated.
 *
 **************************************/
      JRD_REQ request;

      SET_TDBB(tdbb);
      request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

      switch (request->req_operation) {
      case jrd_req::req_evaluate:
            request->req_operation = jrd_req::req_receive;
            request->req_message = node->nod_arg[e_send_message];
            request->req_flags |= req_stall;
            return node;

      case jrd_req::req_proceed:
            request->req_operation = jrd_req::req_evaluate;
            return (node->nod_arg[e_send_statement]);

      default:
            return (node->nod_parent);
      }
}


static void release_blobs(TDBB tdbb, JRD_REQ request)
{
/**************************************
 *
 *    r e l e a s e _ b l o b s
 *
 **************************************
 *
 * Functional description
 *    Release temporary blobs assigned by this request.
 *
 **************************************/
      JRD_TRA transaction;
      BLB *blob;
      ARR *array;

      SET_TDBB(tdbb);
      DEV_BLKCHK(request, type_req);

      if ( (transaction = request->req_transaction) ) {
            DEV_BLKCHK(transaction, type_tra);

            /* Release blobs assigned by this request */

            for (blob = &transaction->tra_blobs; *blob;) {
                  DEV_BLKCHK(*blob, type_blb);
                  if ((*blob)->blb_request == request)
                        BLB_cancel(tdbb, *blob);
                  else
                        blob = &(*blob)->blb_next;
            }

            /* Release arrays assigned by this request */

            for (array = &transaction->tra_arrays; *array;) {
                  DEV_BLKCHK(*array, type_arr);
                  if ((*array)->arr_request == request)
                        BLB_release_array(*array);
                  else
                        array = &(*array)->arr_next;
            }
      }
}


#ifdef PC_ENGINE
static JRD_NOD release_bookmark(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    r e l e a s e _ b o o k m a r k
 *
 **************************************
 *
 * Functional description
 *    Deallocate the passed bookmark.
 *
 **************************************/
      JRD_REQ request;

      SET_TDBB(tdbb);
      request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

      if (request->req_operation == jrd_req::req_evaluate) {
            BKM_release(node->nod_arg[e_relmark_id]);
            request->req_operation = jrd_req::req_return;
      }

      return node->nod_parent;
}
#endif


static void release_proc_save_points(JRD_REQ request)
{
/**************************************
 *
 *    r e l e a s e _ p r o c _ s a v e _ p o i n t s
 *
 **************************************
 *
 * Functional description
 *    Release temporary blobs assigned by this request.
 *
 **************************************/
      JRD_TRA transaction;
      SAV sav_point, temp_sav_point;

/* Release savepoints assigned by this request */

      if ((transaction = request->req_transaction) &&
            (sav_point = request->req_proc_sav_point)) {
            for (temp_sav_point = sav_point; temp_sav_point->sav_next;
                   temp_sav_point = temp_sav_point->sav_next);
            temp_sav_point->sav_next = transaction->tra_save_free;
            transaction->tra_save_free = sav_point;
      }
      request->req_proc_sav_point = NULL;
}


#ifdef SCROLLABLE_CURSORS
static JRD_NOD seek_rse(TDBB tdbb, JRD_REQ request, JRD_NOD node)
{
/**************************************
 *
 *      s e e k _ r s e
 *
 **************************************
 *
 * Functional description
 *    Execute a nod_seek, which specifies 
 *    a direction and offset in which to 
 *    scroll a record selection expression.
 *
 **************************************/
      USHORT direction;
      SLONG offset;
      RSE rse;

      SET_TDBB(tdbb);
      DEV_BLKCHK(node, type_nod);

      if (request->req_operation == jrd_req::req_proceed) {
            /* get input arguments */

            direction = MOV_get_long(EVL_expr(tdbb,
                                                              node->nod_arg[e_seek_direction]),
                                                 0);
            offset =
                  MOV_get_long(EVL_expr(tdbb, node->nod_arg[e_seek_offset]), 0);

            rse = (RSE) node->nod_arg[e_seek_rse];

            seek_rsb(tdbb, request, rse->rse_rsb, direction, offset);

            request->req_operation = jrd_req::req_return;
      }

      return node->nod_parent;
}
#endif


#ifdef SCROLLABLE_CURSORS
static void seek_rsb(
                               TDBB tdbb,
                               JRD_REQ request, RSB rsb, USHORT direction, SLONG offset)
{
/**************************************
 *
 *      s e e k _ r s b
 *
 **************************************
 *
 * Functional description
 *    Allow scrolling through a stream as defined 
 *    by the input rsb.  Handles cracks, refresh 
 *    ranges, and multiple seeking.  Uses RSE_get_record ()
 *    to do the actual work.
 *
 **************************************/
      USHORT crack_flag = 0;
      IRSB impure;
      IRSB next_impure;

      SET_TDBB(tdbb);
      DEV_BLKCHK(rsb, type_rsb);
      impure = (IRSB) ((UCHAR *) request + rsb->rsb_impure);

/* look past any boolean to the actual stream */

      if (rsb->rsb_type == rsb_boolean) {
            seek_rsb(tdbb, request, rsb->rsb_next, direction, offset);

            /* set the backwards flag */

            next_impure = (IRSB) ((UCHAR *) request + rsb->rsb_next->rsb_impure);

            if (next_impure->irsb_flags & irsb_last_backwards)
                  impure->irsb_flags |= irsb_last_backwards;
            else
                  impure->irsb_flags &= ~irsb_last_backwards;
            return;
      }

/* do simple boundary checking for bof and eof */

      switch (direction) {
      case blr_forward:
            if (impure->irsb_flags & irsb_eof)
                  ERR_post(isc_stream_eof, 0);
            break;

      case blr_backward:
            if (impure->irsb_flags & irsb_bof)
                  ERR_post(isc_stream_bof, 0);
            break;

      case blr_bof_forward:
      case blr_eof_backward:
            break;

      default:
            BUGCHECK(232);
      }

/* the actual offset to seek may be one less because the next time 
   through the blr_for loop we will seek one record--flag the fact 
   that a fetch is required on this stream in case it doesn't happen 
   (for example when GPRE generates BLR which does not stall prior to 
   the blr_for, as DSQL does) */

      if (offset > 0)
            switch (direction) {
            case blr_forward:
            case blr_bof_forward:
                  if (!(impure->irsb_flags & irsb_last_backwards)) {
                        offset--;
                        if (!(impure->irsb_flags & irsb_bof))
                              request->req_flags |= req_fetch_required;
                  }
                  break;

            case blr_backward:
            case blr_eof_backward:
                  if (impure->irsb_flags & irsb_last_backwards) {
                        offset--;
                        if (!(impure->irsb_flags & irsb_eof))
                              request->req_flags |= req_fetch_required;
                  }
                  break;
            }

/* now do the actual seek */

      switch (direction) {
      case blr_forward:             /* go forward from the current location */

#ifdef PC_ENGINE
            if ((offset == 1) && request->req_begin_ranges)
                  impure->irsb_flags |= irsb_refresh;
#endif

            /* the rsb_backwards flag is used to indicate the direction to seek in; 
               this is sticky in the sense that after the user has seek'ed in the 
               backward direction, the next retrieval from a blr_for loop will also 
               be in the backward direction--this allows us to continue scrolling 
               without constantly sending messages to the engine */

            impure->irsb_flags &= ~irsb_last_backwards;

            while (offset) {
                  offset--;
                  if (!(RSE_get_record(tdbb, rsb, RSE_get_next)))
                        break;
            }
            break;

      case blr_backward:                  /* go backward from the current location */

#ifdef PC_ENGINE
            if ((offset == 1) && request->req_begin_ranges)
                  impure->irsb_flags |= irsb_refresh;
#endif

            impure->irsb_flags |= irsb_last_backwards;

            while (offset) {
                  offset--;
                  if (!(RSE_get_record(tdbb, rsb, RSE_get_next)))
                        break;
            }
            break;

      case blr_bof_forward:         /* go forward from the beginning of the stream */

            RSE_close(tdbb, rsb);
            RSE_open(tdbb, rsb);

            impure->irsb_flags &= ~irsb_last_backwards;

            while (offset) {
                  offset--;
                  if (!(RSE_get_record(tdbb, rsb, RSE_get_next)))
                        break;
            }
            break;

      case blr_eof_backward:        /* go backward from the end of the stream */

            RSE_close(tdbb, rsb);
            RSE_open(tdbb, rsb);

            /* if this is a stream type which uses bof and eof flags, 
               reverse the sense of bof and eof in this case */

            if (impure->irsb_flags & irsb_bof) {
                  impure->irsb_flags &= ~irsb_bof;
                  impure->irsb_flags |= irsb_eof;
            }

            impure->irsb_flags |= irsb_last_backwards;

            while (offset) {
                  offset--;
                  if (!(RSE_get_record(tdbb, rsb, RSE_get_next)))
                        break;
            }
            break;

      default:
            BUGCHECK(232);
      }

#ifdef PC_ENGINE
      impure->irsb_flags &= ~irsb_refresh;
#endif
}
#endif


static JRD_NOD selct(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    s e l e c t
 *
 **************************************
 *
 * Functional description
 *    Execute a SELECT statement.  This is more than a little
 *    obscure.  We first set up the SELECT statement as the
 *    "message" and stall on receive (waiting for user send).
 *    EXE_send will then loop thru the sub-statements of select
 *    looking for the appropriate RECEIVE statement.  When (or if)
 *    it finds it, it will set it up the next statement to be
 *    executed.  The RECEIVE, then, will be entered with the
 *    operation "req_proceed."
 *
 **************************************/
      JRD_REQ request;

      SET_TDBB(tdbb);
      request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

      switch (request->req_operation) {
      case jrd_req::req_evaluate:
            request->req_message = node;
            request->req_operation = jrd_req::req_receive;
            request->req_flags |= req_stall;
            return node;

      default:
            return node->nod_parent;
      }
}



static JRD_NOD send_msg(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    s e n d _ m s g
 *
 **************************************
 *
 * Functional description
 *    Execute a SEND statement.
 *
 **************************************/
      JRD_REQ request;

      SET_TDBB(tdbb);
      request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

      switch (request->req_operation) {
      case jrd_req::req_evaluate:
            return (node->nod_arg[e_send_statement]);

      case jrd_req::req_return:
            request->req_operation = jrd_req::req_send;
            request->req_message = node->nod_arg[e_send_message];
            request->req_flags |= req_stall;
            return node;

      case jrd_req::req_proceed:
            request->req_operation = jrd_req::req_return;
            return node->nod_parent;

      default:
            return (node->nod_parent);
      }
}


#ifdef PC_ENGINE
static JRD_NOD set_bookmark(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    s e t _ b o o k m a r k
 *
 **************************************
 *
 * Functional description
 *    Set a stream to the location of the
 *    specified bookmark.
 *
 **************************************/
      JRD_REQ request;
      BKM bookmark;
      USHORT stream;
      RPB *rpb;
      RSB rsb;
      IRSB impure;


      SET_TDBB(tdbb);
      request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

      if (request->req_operation == jrd_req::req_evaluate) {
            bookmark = BKM_lookup(node->nod_arg[e_setmark_id]);
            stream = (USHORT) (IPTR) node->nod_arg[e_setmark_stream];
            rpb = &request->req_rpb[stream];
            rsb = *((RSB *) node->nod_arg[e_setmark_rsb]);
            impure = (IRSB) ((UCHAR *) request + rsb->rsb_impure);

            /* check if the bookmark was at beginning or end of file 
               and flag the rsb accordingly */

            RSE_MARK_CRACK(tdbb, rsb, 0);
            if (bookmark->bkm_flags & bkm_bof)
                  RSE_MARK_CRACK(tdbb, rsb, irsb_bof);
            else if (bookmark->bkm_flags & bkm_eof)
                  RSE_MARK_CRACK(tdbb, rsb, irsb_eof);
            else if (bookmark->bkm_flags & bkm_crack) {
                  RSE_MARK_CRACK(tdbb, rsb, irsb_crack);
                  if (bookmark->bkm_flags & bkm_forced_crack)
                        RSE_MARK_CRACK(tdbb, rsb, irsb_forced_crack);
            }

            if (!RSE_set_bookmark(tdbb, rsb, rpb, bookmark))
                  EXE_mark_crack(tdbb, rsb,
                                       impure->irsb_flags & (irsb_crack | irsb_eof |
                                                                         irsb_bof));

            request->req_operation = jrd_req::req_return;
      }

      return node->nod_parent;
}
#endif


static void set_error(TDBB tdbb, XCP condition, JRD_NOD node)
{
/**************************************
 *
 *    s e t _ e r r o r
 *
 **************************************
 *
 * Functional description
 *    Set status vector according to specified error condition
 *    and jump to handle error accordingly.
 *
 **************************************/
      JRD_REQ request;
      TEXT name[32], relation_name[32], *s, *r;
      TEXT message[XCP_MESSAGE_LENGTH + 1], temp[XCP_MESSAGE_LENGTH + 1];
      USHORT length = 0;
      
      SET_TDBB(tdbb);

      request = tdbb->tdbb_request;

      if (condition->xcp_rpt[0].xcp_msg)
      {
            /* pick up message from already initiated exception */
            length = MIN(condition->xcp_rpt[0].xcp_msg->str_length, sizeof(message) - 1);
            memcpy(message, condition->xcp_rpt[0].xcp_msg->str_data, length);
            delete condition->xcp_rpt[0].xcp_msg;
            condition->xcp_rpt[0].xcp_msg = 0;
      }
      else if (node)
      {
            const char* string = 0;
            /* evaluate exception message and convert it to string */
            DSC *desc = EVL_expr(tdbb, node);
            if (desc && !(request->req_flags & req_null))
            {
                  length = MOV_make_string(desc,
                                                       ttype_none,
                                                       &string,
                                                       reinterpret_cast<VARY*>(temp),
                                                       sizeof(temp));
                  length = MIN(length, sizeof(message) - 1);

                  /* dimitr: or should we throw an error here, i.e.
                                 replace the above assignment with the following lines:

                  if (length > sizeof(message) - 1)
                        ERR_post(gds_imp_exc, gds_arg_gds, gds_blktoobig, 0);
                  */

                  memcpy(message, string, length);
            }
            else
            {
                  length = 0;
            }
      }
      message[length] = 0;

      switch (condition->xcp_rpt[0].xcp_type) {
      case xcp_sql_code:
            ERR_post(gds_sqlerr,
                         gds_arg_number, (SLONG) condition->xcp_rpt[0].xcp_code, 0);

      case xcp_gds_code:
            if (condition->xcp_rpt[0].xcp_code == gds_check_constraint) {
                  MET_lookup_cnstrt_for_trigger(tdbb, name, relation_name,
                                                              request->req_trg_name);
                  // const CAST
                  s = (name[0]) ? name : (TEXT*)"";
                  r = (relation_name[0]) ? relation_name : (TEXT*)"";
                  ERR_post(condition->xcp_rpt[0].xcp_code,
                               gds_arg_string, ERR_cstring(s),
                               gds_arg_string, ERR_cstring(r), 0);
            }
            else
                  ERR_post(condition->xcp_rpt[0].xcp_code, 0);

      case xcp_xcp_code:
            MET_lookup_exception(tdbb, condition->xcp_rpt[0].xcp_code,
                                           name, temp);
            if (message[0])
                  s = message;
            else if (temp[0])
                  s = temp;
            else if (name[0])
                  s = name;
            else
                  s = NULL;
            if (s)
                  ERR_post(gds_except,
                               gds_arg_number, (SLONG) condition->xcp_rpt[0].xcp_code,
                               gds_arg_gds, gds_random, gds_arg_string, ERR_cstring(s),
                               0);
            else
                  ERR_post(gds_except, gds_arg_number,
                               (SLONG) condition->xcp_rpt[0].xcp_code, 0);
      }
}


#ifdef PC_ENGINE
static JRD_NOD set_index(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    s e t _ i n d e x
 *
 **************************************
 *
 * Functional description
 *    Execute a SET INDEX statement.
 *
 **************************************/
      JRD_REQ request;
      USHORT stream, id;
      RPB *rpb;
      JRD_REL relation;
      IDX idx;

      SET_TDBB(tdbb);
      request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

      if (request->req_operation == jrd_req::req_evaluate) {
            stream = (USHORT) (IPTR) node->nod_arg[e_index_stream];

            rpb = &request->req_rpb[stream];
            relation = rpb->rpb_relation;

            /* if id is non-zero, get the index definition;
               otherwise it indicates revert to natural order */

            id = MOV_get_long(EVL_expr(tdbb, node->nod_arg[e_index_index]), 0);
            if (id && BTR_lookup(tdbb, relation, id - 1, &idx))
                  ERR_post(gds_indexnotdefined, gds_arg_string, relation->rel_name,
                               gds_arg_number, (SLONG) id, 0);

            /* generate a new rsb in place of the old */

            RSE_close(tdbb, *(RSB *) node->nod_arg[e_index_rsb]);
            OPT_set_index(tdbb, request, (RSB *) node->nod_arg[e_index_rsb],
                                relation, id ? &idx : (IDX *) 0);
            RSE_open(tdbb, *(RSB *) node->nod_arg[e_index_rsb]);

            request->req_operation = jrd_req::req_return;
      }

      return node->nod_parent;
}
#endif


static JRD_NOD stall(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    s t a l l 
 *
 **************************************
 *
 * Functional description
 *    Execute a stall statement.
 *    This is like a blr_receive, except that there is no
 *    need for a gds__send () from the user (i.e. EXE_send () in the engine).
 *    A gds__receive () will unblock the user.
 *
 **************************************/
      JRD_REQ request;

      SET_TDBB(tdbb);
      request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

      switch (request->req_operation) {
      case jrd_req::req_sync:
            return node->nod_parent;

      case jrd_req::req_proceed:
            request->req_operation = jrd_req::req_return;
            return node->nod_parent;

      default:
            request->req_message = node;
            request->req_operation = jrd_req::req_return;
            request->req_flags |= req_stall;
            return node;
      }
}


static JRD_NOD store(TDBB tdbb, JRD_NOD node, SSHORT which_trig)
{
/**************************************
 *
 *    s t o r e
 *
 **************************************
 *
 * Functional description
 *    Execute a STORE statement.
 *
 **************************************/

      JRD_REQ trigger;
      FMT format;
      SSHORT n;
      REC record;
      UCHAR *p;

      SET_TDBB(tdbb);
      DBB dbb = tdbb->tdbb_database;
      BLKCHK(node, type_nod);

      JRD_REQ    request     = tdbb->tdbb_request;
      JRD_TRA    transaction = request->req_transaction;
      STA    impure      = (STA) ((SCHAR *) request + node->nod_impure);
      SSHORT stream      = (USHORT) (IPTR) node->nod_arg[e_sto_relation]->nod_arg[e_rel_stream];
      RPB*   rpb         = &request->req_rpb[stream];
      JRD_REL    relation    = rpb->rpb_relation;

      switch (request->req_operation) {
      case jrd_req::req_evaluate:
            impure->sta_state = 0;
            RLCK_reserve_relation(tdbb, transaction, relation, TRUE, TRUE);
            break;

      case jrd_req::req_return:
            if (impure->sta_state)
                  return node->nod_parent;
            record = rpb->rpb_record;
            format = record->rec_format;

            if (transaction != dbb->dbb_sys_trans)
                  ++transaction->tra_save_point->sav_verb_count;

            if (relation->rel_pre_store &&
                  (which_trig != POST_TRIG) &&
                  (trigger = execute_triggers(tdbb, &relation->rel_pre_store,
                                                            0, record, jrd_req::req_trigger_insert)))
            {
                  trigger_failure(tdbb, trigger);
            }

            if (node->nod_arg[e_sto_validate]) {
                  validate(tdbb, node->nod_arg[e_sto_validate]);
            }

            /* For optimum on-disk record compression, zero all unassigned
               fields. In addition, zero the tail of assigned varying fields
               so that previous remnants don't defeat compression efficiency. */

            /* CVC: The code that was here was moved to its own routine: cleanup_rpb()
                        and replaced by the call shown above. */

            cleanup_rpb(tdbb, rpb);

            if (relation->rel_file) {
                  EXT_store(rpb, reinterpret_cast < int *>(transaction));
            }
            else if (!relation->rel_view_rse)
            {
                  USHORT bad_index;
                  JRD_REL bad_relation;

                  VIO_store(tdbb, rpb, transaction);
                  IDX_E error_code = IDX_store(tdbb,
                                                             rpb,
                                                             transaction,
                                                             &bad_relation,
                                                             &bad_index);
                  if (error_code) {
                        VIO_bump_count(tdbb, DBB_insert_count, bad_relation, true);
                        ERR_duplicate_error(error_code, bad_relation, bad_index);
                  }
            }

            if (relation->rel_post_store &&
                  (which_trig != PRE_TRIG) &&
                  (trigger = execute_triggers(tdbb, &relation->rel_post_store,
                                                            0, record, jrd_req::req_trigger_insert)))
            {
                  VIO_bump_count(tdbb, DBB_insert_count, relation, true);
                  trigger_failure(tdbb, trigger);
            }

            /* CVC: Increment the counter only if we called VIO/EXT_store() and
                        we were successful. */
            if (!(request->req_view_flags & req_first_store_return)) {
                  request->req_view_flags |= req_first_store_return;
                  if (relation->rel_view_rse) {
                        request->req_top_view_store = relation;
                  }
            }
            if (relation == request->req_top_view_store) {
                  if (which_trig == ALL_TRIGS || which_trig == POST_TRIG) {
                        request->req_records_inserted++;
                        request->req_records_affected++;
                  }
            }
            else if (relation->rel_file || !relation->rel_view_rse) {
                  request->req_records_inserted++;
                  request->req_records_affected++;
            }

            if (transaction != dbb->dbb_sys_trans) {
                  --transaction->tra_save_point->sav_verb_count;
            }

            if (node->nod_arg[e_sto_statement2]) {
                  impure->sta_state = 1;
                  request->req_operation = jrd_req::req_evaluate;
                  return node->nod_arg[e_sto_statement2];
            }

      default:
            return node->nod_parent;
      }

/* Fall thru on evaluate to set up for store before executing sub-statement.
   This involves finding the appropriate format, making sure a record block
   exists for the stream and is big enough, and initialize all null flags
   to "missing." */

      format = MET_current(tdbb, relation);
      record = VIO_record(tdbb, rpb, format, tdbb->tdbb_default);

      rpb->rpb_address = record->rec_data;
      rpb->rpb_length = format->fmt_length;
      rpb->rpb_format_number = format->fmt_version;

      /* CVC: This small block added by Ann Harrison to
                  start with a clean empty buffer and so avoid getting
                  new record buffer with misleading information. Fixes
                  bug with incorrect blob sharing during insertion in
                  a stored procedure. */

      p = record->rec_data;
      {
            UCHAR *data_end = p + rpb->rpb_length;
            while (p < data_end)
                  *p++ = 0;
      }

/* Initialize all fields to missing */

      p = record->rec_data;
      n = (format->fmt_count + 7) >> 3;
      if (n) {
            do {
                  *p++ = 0xff;
            } while (--n);
      }

      return node->nod_arg[e_sto_statement];
}


#ifdef PC_ENGINE
static JRD_NOD stream(TDBB tdbb, JRD_NOD node)
{
/**************************************
 *
 *    s t r e a m
 *
 **************************************
 *
 * Functional description
 *    Execute a STREAM statement.
 *
 **************************************/
      JRD_REQ request;
      RSB rsb;

      SET_TDBB(tdbb);
      request = tdbb->tdbb_request;
      BLKCHK(node, type_nod);

      rsb = ((RSE) node)->rse_rsb;

      switch (request->req_operation) {
      case jrd_req::req_evaluate:
            RSE_open(tdbb, rsb);
            request->req_operation = jrd_req::req_return;

      case jrd_req::req_return:
            node = node->nod_parent;
            break;

      default:
            RSE_close(tdbb, rsb);
            node = node->nod_parent;
      }

      return node;
}
#endif


static BOOLEAN test_and_fixup_error(TDBB tdbb, XCP conditions, JRD_REQ request)
{
/**************************************
 *
 *    t e s t _ a n d _ f i x u p _ e r r o r
 *
 **************************************
 *
 * Functional description
 *    Test for match of current state with list of error conditions.
 *  Fix type and code of the exception.
 *
 **************************************/
      SSHORT i, sqlcode;
      ISC_STATUS *status_vector;

      SET_TDBB(tdbb);
      status_vector = tdbb->tdbb_status_vector;
      sqlcode = gds__sqlcode(status_vector);

      const SLONG XCP_SQLCODE = -836;

      delete request->req_last_xcp.xcp_msg;
      request->req_last_xcp.xcp_msg = 0;

      for (i = 0; i < conditions->xcp_count; i++)
      {
            switch (conditions->xcp_rpt[i].xcp_type)
            {
            case xcp_sql_code:
                  if (sqlcode == conditions->xcp_rpt[i].xcp_code)
                  {
                        if ((sqlcode != XCP_SQLCODE) || (status_vector[1] != gds_except))
                        {
                              request->req_last_xcp.xcp_type = xcp_sql_code;
                              request->req_last_xcp.xcp_code = sqlcode;
                        }
                        else
                        {
                              request->req_last_xcp.xcp_type = xcp_xcp_code;
                              request->req_last_xcp.xcp_code = status_vector[3];
                        }              
                        status_vector[0] = 0;
                        status_vector[1] = 0;
                        return TRUE;
                  }
                  break;

            case xcp_gds_code:
                  if (status_vector[1] == conditions->xcp_rpt[i].xcp_code)
                  {
                        if ((sqlcode != XCP_SQLCODE) || (status_vector[1] != gds_except))
                        {
                              request->req_last_xcp.xcp_type = xcp_gds_code;
                              request->req_last_xcp.xcp_code = status_vector[1];
                        }
                        else
                        {
                              request->req_last_xcp.xcp_type = xcp_xcp_code;
                              request->req_last_xcp.xcp_code = status_vector[3];
                        }              
                        status_vector[0] = 0;
                        status_vector[1] = 0;
                        return TRUE;
                  }
                  break;

            case xcp_xcp_code:
                  if ((status_vector[1] == gds_except) &&
                        (status_vector[3] == conditions->xcp_rpt[i].xcp_code))
                  {
                        request->req_last_xcp.xcp_type = xcp_xcp_code;
                        request->req_last_xcp.xcp_code = status_vector[3];
                        TEXT *msg = reinterpret_cast<TEXT*>(status_vector[7]);
                        assign_xcp_message(tdbb, &request->req_last_xcp.xcp_msg, msg);
                        status_vector[0] = 0;
                        status_vector[1] = 0;
                        return TRUE;
                  }
                  break;

            case xcp_default:
                  if (sqlcode && (sqlcode != XCP_SQLCODE))
                  {
                        request->req_last_xcp.xcp_type = xcp_sql_code;
                        request->req_last_xcp.xcp_code = sqlcode;
                  }
                  else if (status_vector[1] != gds_except) 
                  {
                        request->req_last_xcp.xcp_type = xcp_gds_code;
                        request->req_last_xcp.xcp_code = status_vector[1];
                  }
                  else
                  {
                        request->req_last_xcp.xcp_type = xcp_xcp_code;
                        request->req_last_xcp.xcp_code = status_vector[3];
                        TEXT *msg = reinterpret_cast<TEXT*>(status_vector[7]);
                        assign_xcp_message(tdbb, &request->req_last_xcp.xcp_msg, msg);
                  }
                  status_vector[0] = 0;
                  status_vector[1] = 0;
                  return TRUE;
            }
    }

      return FALSE;
}


static void trigger_failure(TDBB tdbb, JRD_REQ trigger)
{
/**************************************
 *
 *    t r i g g e r _ f a i l u r e
 *
 **************************************
 *
 * Functional description
 *    Trigger failed, report error.
 *
 **************************************/

      SET_TDBB(tdbb);
      EXE_unwind(tdbb, trigger);

      trigger->req_attachment = NULL;
      trigger->req_flags &= ~req_in_use;
      trigger->req_timestamp = 0;

      if (trigger->req_flags & req_leave)
      {
            trigger->req_flags &= ~req_leave;
            const TEXT* msg;
            if (trigger->req_trg_name &&
                  (msg = MET_trigger_msg(tdbb,
                                                      trigger->req_trg_name,
                                                      trigger->req_label)))
            {
                  if (trigger->req_flags & req_sys_trigger)
                  {
                        ISC_STATUS code = PAR_symbol_to_gdscode(msg);
                        if (code)
                        {
                              ERR_post(gds_integ_fail,
                                           gds_arg_number, (SLONG) trigger->req_label,
                                           gds_arg_gds, code, 0);
                        }
                  }
                  ERR_post(gds_integ_fail,
                               gds_arg_number, (SLONG) trigger->req_label,
                               gds_arg_gds, gds_random, gds_arg_string, msg, 0);
            }
            else
            {
                  ERR_post(gds_integ_fail, gds_arg_number,
                               (SLONG) trigger->req_label, 0);
            }
      }
      else
      {
            ERR_punt();
      }
}


static void validate(TDBB tdbb, JRD_NOD list)
{
/**************************************
 *
 *    v a l i d a t e
 *
 **************************************
 *
 * Functional description
 *    Execute a list of validation expressions.
 *
 **************************************/

      SET_TDBB(tdbb);
      BLKCHK(list, type_nod);

      JRD_NOD *ptr1, *ptr2;

      for (ptr1 = list->nod_arg, ptr2 = ptr1 + list->nod_count;
             ptr1 < ptr2; ptr1++)
      {
            if (!EVL_boolean(tdbb, (*ptr1)->nod_arg[e_val_boolean]))
            {
                  /* Validation error -- report result */

                  JRD_NOD node;
                  VEC vector;
                  JRD_REL relation;
                  JRD_REQ request;
                  JRD_FLD field;
                  const char* value;
                  TEXT temp[128];
                  const TEXT* name = NULL;
                  USHORT length, stream, id;

                  node = (*ptr1)->nod_arg[e_val_value];
                  request = tdbb->tdbb_request;
                  length = MOV_make_string(EVL_expr(tdbb, node),
                                                       ttype_dynamic,
                                                       &value,
                                                       reinterpret_cast<VARY*>(temp),
                                                       sizeof(temp));

                  if (request->req_flags & req_null ||
                        request->req_flags & req_clone_data_from_default_clause)
                  {
                        value = "*** null ***";
                  }
                  else if (!length)
                  {
                        value = "";
                  }
                  else
                  {
                        value = ERR_string(value, length);
                  }

                  if (node->nod_type == nod_field)
                  {
                        stream = (USHORT) (IPTR) node->nod_arg[e_fld_stream];
                        id = (USHORT) (IPTR) node->nod_arg[e_fld_id];
                        relation = request->req_rpb[stream].rpb_relation;

                        if ((vector = relation->rel_fields) &&
                              id < vector->count() &&
                              (field = (JRD_FLD) (*vector)[id]))
                        {
                              name = field->fld_name;
                        }
                  }

                  if (!name)
                  {
                        name = "*** unknown ***";
                  }

                  ERR_post(gds_not_valid, gds_arg_string, name,
                               gds_arg_string, value, 0);
            }
      }
}

} // extern "C"

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