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+/* vmstk.c - the arithmetic stack of a virtual machine.
+ *
+ * Module begun 2008-02-21 by Rainer Gerhards
+ *
+ * Copyright 2008 Rainer Gerhards and Adiscon GmbH.
+ *
+ * This file is part of rsyslog.
+ *
+ * Rsyslog is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Rsyslog is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Rsyslog. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * A copy of the GPL can be found in the file "COPYING" in this distribution.
+ */
+
+#include "config.h"
+#include <stdlib.h>
+#include <assert.h>
+
+#include "rsyslog.h"
+#include "obj.h"
+#include "vmstk.h"
+
+/* static data */
+DEFobjStaticHelpers
+DEFobjCurrIf(var)
+
+
+/* Standard-Constructor
+ */
+BEGINobjConstruct(vmstk) /* be sure to specify the object type also in END macro! */
+ENDobjConstruct(vmstk)
+
+
+/* ConstructionFinalizer
+ * rgerhards, 2008-01-09
+ */
+static rsRetVal
+vmstkConstructFinalize(vmstk_t __attribute__((unused)) *pThis)
+{
+ DEFiRet;
+ ISOBJ_TYPE_assert(pThis, vmstk);
+ RETiRet;
+}
+
+
+/* destructor for the vmstk object */
+BEGINobjDestruct(vmstk) /* be sure to specify the object type also in END and CODESTART macros! */
+CODESTARTobjDestruct(vmstk)
+ENDobjDestruct(vmstk)
+
+
+/* debugprint for the vmstk object */
+BEGINobjDebugPrint(vmstk) /* be sure to specify the object type also in END and CODESTART macros! */
+CODESTARTobjDebugPrint(vmstk)
+ dbgoprint((obj_t*) pThis, "stack contents:\n");
+ENDobjDebugPrint(vmstk)
+
+
+/* push a value on the stack. The provided pVar is now owned
+ * by the stack. If the user intends to continue use it, it
+ * must be duplicated.
+ */
+static rsRetVal
+push(vmstk_t *pThis, var_t *pVar)
+{
+ DEFiRet;
+
+ ISOBJ_TYPE_assert(pThis, vmstk);
+ ISOBJ_TYPE_assert(pVar, var);
+
+ if(pThis->iStkPtr >= VMSTK_SIZE)
+ ABORT_FINALIZE(RS_RET_OUT_OF_STACKSPACE);
+
+ pThis->vStk[pThis->iStkPtr++] = pVar;
+
+finalize_it:
+ RETiRet;
+}
+
+
+/* pop a value from the stack
+ * IMPORTANT: the stack pointer always points to the NEXT FREE entry. So in
+ * order to pop, we must access the element one below the stack pointer.
+ * The user is responsible for destructing the ppVar returned.
+ */
+static rsRetVal
+pop(vmstk_t *pThis, var_t **ppVar)
+{
+ DEFiRet;
+
+ ISOBJ_TYPE_assert(pThis, vmstk);
+ ASSERT(ppVar != NULL);
+
+ if(pThis->iStkPtr == 0)
+ ABORT_FINALIZE(RS_RET_STACK_EMPTY);
+
+ *ppVar = pThis->vStk[--pThis->iStkPtr];
+
+finalize_it:
+ RETiRet;
+}
+
+
+/* pop a boolean value from the stack
+ * The user is responsible for destructing the ppVar returned.
+ */
+static rsRetVal
+popBool(vmstk_t *pThis, var_t **ppVar)
+{
+ DEFiRet;
+
+ /* assertions are done in pop(), we do not duplicate here */
+ CHKiRet(pop(pThis, ppVar));
+ CHKiRet(var.ConvToBool(*ppVar));
+
+finalize_it:
+ RETiRet;
+}
+
+
+/* pop a number value from the stack
+ * The user is responsible for destructing the ppVar returned.
+ */
+static rsRetVal
+popNumber(vmstk_t *pThis, var_t **ppVar)
+{
+ DEFiRet;
+
+ /* assertions are done in pop(), we do not duplicate here */
+ CHKiRet(pop(pThis, ppVar));
+ CHKiRet(var.ConvToNumber(*ppVar));
+
+finalize_it:
+ RETiRet;
+}
+
+
+/* pop a number value from the stack
+ * The user is responsible for destructing the ppVar returned.
+ */
+static rsRetVal
+popString(vmstk_t *pThis, var_t **ppVar)
+{
+ DEFiRet;
+
+ /* assertions are done in pop(), we do not duplicate here */
+ CHKiRet(pop(pThis, ppVar));
+ CHKiRet(var.ConvToString(*ppVar));
+
+finalize_it:
+ RETiRet;
+}
+
+
+/* pop two variables for a common operation, e.g. a compare. When this
+ * functions returns, both variables have the same type, but the type
+ * is not set to anything specific.
+ * The user is responsible for destructing the ppVar's returned.
+ * A quick note on the name: it means pop 2 variable for a common
+ * opertion - just in case you wonder (I don't really like the name,
+ * but I didn't come up with a better one...).
+ * rgerhards, 2008-02-25
+ */
+static rsRetVal
+pop2CommOp(vmstk_t *pThis, var_t **ppVar1, var_t **ppVar2)
+{
+ DEFiRet;
+
+ /* assertions are done in pop(), we do not duplicate here */
+ /* operand two must be popped first, because it is at the top of stack */
+ CHKiRet(pop(pThis, ppVar2));
+ CHKiRet(pop(pThis, ppVar1));
+ CHKiRet(var.ConvForOperation(*ppVar1, *ppVar2));
+
+finalize_it:
+ RETiRet;
+}
+
+
+/* queryInterface function
+ * rgerhards, 2008-02-21
+ */
+BEGINobjQueryInterface(vmstk)
+CODESTARTobjQueryInterface(vmstk)
+ if(pIf->ifVersion != vmstkCURR_IF_VERSION) { /* check for current version, increment on each change */
+ ABORT_FINALIZE(RS_RET_INTERFACE_NOT_SUPPORTED);
+ }
+
+ /* ok, we have the right interface, so let's fill it
+ * Please note that we may also do some backwards-compatibility
+ * work here (if we can support an older interface version - that,
+ * of course, also affects the "if" above).
+ */
+ pIf->Construct = vmstkConstruct;
+ pIf->ConstructFinalize = vmstkConstructFinalize;
+ pIf->Destruct = vmstkDestruct;
+ pIf->DebugPrint = vmstkDebugPrint;
+ pIf->Push = push;
+ pIf->Pop = pop;
+ pIf->PopBool = popBool;
+ pIf->PopNumber = popNumber;
+ pIf->PopString = popString;
+ pIf->Pop2CommOp = pop2CommOp;
+
+finalize_it:
+ENDobjQueryInterface(vmstk)
+
+
+/* Initialize the vmstk class. Must be called as the very first method
+ * before anything else is called inside this class.
+ * rgerhards, 2008-02-19
+ */
+BEGINObjClassInit(vmstk, 1, OBJ_IS_CORE_MODULE) /* class, version */
+ /* request objects we use */
+ CHKiRet(objUse(var, CORE_COMPONENT));
+
+ /* set our own handlers */
+ OBJSetMethodHandler(objMethod_DEBUGPRINT, vmstkDebugPrint);
+ OBJSetMethodHandler(objMethod_CONSTRUCTION_FINALIZER, vmstkConstructFinalize);
+ENDObjClassInit(vmstk)
+
+/* vi:set ai:
+ */