104 lines
3 KiB
C
104 lines
3 KiB
C
/*-
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* DBSQL - A SQL database engine.
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*
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* Copyright (C) 2007 The DBSQL Group, Inc. - All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* $Id: safety.c 7 2007-02-03 13:34:17Z gburd $
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*/
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#include "dbsql_config.h"
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#include "dbsql_int.h"
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/*
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* __safety_on --
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* Change the sqlite.magic from DBSQL_STATUS_OPEN to DBSQL_STATUS_BUSY.
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* Return an error (non-zero) if the magic was not DBSQL_STATUS_OPEN
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* when this routine is called.
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*
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* !!! TODO race condition
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* This routine is a attempt to detect if two threads use the
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* same DBSQL* pointer at the same time. There is a race
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* condition so it is possible that the error is not detected.
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* But usually the problem will be seen. The result will be an
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* error which can be used to debug the application that is
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* using the library incorrectly.
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*
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* [#202sl]: If db->magic is not a valid open value, take care not
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* to modify the db structure at all. It could be that db is a stale
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* pointer. In other words, it could be that there has been a prior
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* call to DBSQL->close(db) and db has been deallocated. And we do
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* not want to write into deallocated memory.
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*
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* PUBLIC: int __safety_on __P((DBSQL *));
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*/
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int
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__safety_on(dbp)
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DBSQL *dbp;
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{
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if (dbp->magic == DBSQL_STATUS_OPEN) {
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dbp->magic = DBSQL_STATUS_BUSY;
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return 0;
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} else if (dbp->magic == DBSQL_STATUS_BUSY ||
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dbp->magic == DBSQL_STATUS_ERROR ||
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dbp->want_to_close) {
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dbp->magic = DBSQL_STATUS_ERROR;
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dbp->flags |= DBSQL_Interrupt;
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}
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return 1;
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}
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/*
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* __safety_off --
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* Change the magic from DBSQL_STATUS_BUSY to DBSQL_STATUS_OPEN.
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* Return an error (non-zero) if the magic was not DBSQL_STATUS_BUSY
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* when this routine is called.
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*
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* PUBLIC: int __safety_off __P((DBSQL *));
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*/
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int
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__safety_off(dbp)
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DBSQL *dbp;
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{
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if (dbp->magic == DBSQL_STATUS_BUSY) {
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dbp->magic = DBSQL_STATUS_OPEN;
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return 0;
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} else if (dbp->magic == DBSQL_STATUS_OPEN ||
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dbp->magic == DBSQL_STATUS_ERROR ||
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dbp->want_to_close) {
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dbp->magic = DBSQL_STATUS_ERROR;
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dbp->flags |= DBSQL_Interrupt;
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}
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return 1;
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}
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/*
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* __safety_check --
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* Check to make sure we are not currently executing an DBSQL->exec().
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* If we are currently in an DBSQL->exec(), return true and set
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* dbsql_t.magic to DBSQL_STATUS_ERROR. This will cause a complete
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* shutdown of the database. This routine is used to try to detect
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* when API routines are called at the wrong time or in the wrong
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* sequence.
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*
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* PUBLIC: int __safety_check __P((DBSQL *));
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*/
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int
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__safety_check(dbp)
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DBSQL *dbp;
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{
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if (dbp->pVdbe != 0) {
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dbp->magic = DBSQL_STATUS_ERROR;
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return 1;
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}
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return 0;
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}
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