From d3da6ba716d94ec684186a89a52fb90636db89ee Mon Sep 17 00:00:00 2001
From: Rainer Gerhards <rgerhards@adiscon.com>
Date: Fri, 22 Feb 2008 09:51:34 +0000
Subject: completed initial vmstk implementation

---
 rsyslog.h |  2 ++
 vmstk.c   | 17 ++++++++++++++++-
 vmstk.h   |  5 +++++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/rsyslog.h b/rsyslog.h
index 8b8ada8d..2d31bd14 100644
--- a/rsyslog.h
+++ b/rsyslog.h
@@ -128,6 +128,8 @@ enum rsRetVal_				/** return value. All methods return this if not specified oth
 	RS_RET_INVALID_OCTAL_DIGIT = -2052, /**< invalid octal digit during parsing */
 	RS_RET_INVALID_HEX_DIGIT = -2053, /**< invalid hex digit during parsing */
 	RS_RET_INTERFACE_NOT_SUPPORTED = -2054, /**< interface not supported */
+	RS_RET_OUT_OF_STACKSPACE = -2055, /**< a stack data structure is exhausted and can not be grown */
+	RS_RET_STACK_EMPTY = -2056, /**< a pop was requested on a stack, but the stack was already empty */
 	RS_RET_OK_DELETE_LISTENTRY = 1,	/**< operation successful, but callee requested the deletion of an entry (special state) */
 	RS_RET_TERMINATE_NOW = 2,	/**< operation successful, function is requested to terminate (mostly used with threads) */
 	RS_RET_NO_RUN = 3,		/**< operation successful, but function does not like to be executed */
diff --git a/vmstk.c b/vmstk.c
index 1db7b8fa..6944b6f9 100644
--- a/vmstk.c
+++ b/vmstk.c
@@ -66,7 +66,9 @@ CODESTARTobjDebugPrint(vmstk)
 ENDobjDebugPrint(vmstk)
 
 
-/* push a value on the stack
+/* 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)
@@ -76,11 +78,18 @@ push(vmstk_t *pThis, var_t *pVar)
 	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
+ * The user is responsible for destructing the ppVar returned.
  */
 static rsRetVal
 pop(vmstk_t *pThis, var_t **ppVar)
@@ -90,6 +99,12 @@ pop(vmstk_t *pThis, var_t **ppVar)
 	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;
 }
 
diff --git a/vmstk.h b/vmstk.h
index 4e81f5a0..30bb9009 100644
--- a/vmstk.h
+++ b/vmstk.h
@@ -22,9 +22,14 @@
 #ifndef INCLUDED_VMSTK_H
 #define INCLUDED_VMSTK_H
 
+/* The max size of the stack - TODO: make configurable */
+#define VMSTK_SIZE 256
+
 /* the vmstk object */
 typedef struct vmstk_s {
 	BEGINobjInstance;	/* Data to implement generic object - MUST be the first data element! */
+	var_t *vStk[VMSTK_SIZE];/* the actual stack */
+	int iStkPtr;		/* stack pointer, points to next free location, grows from 0 --> topend */
 } vmstk_t;
 
 
-- 
cgit