* generic/tclBasic.c:

	* generic/tclInt.h:
	* unix/tclUnixInit.c:
	* unix/tclUnixPort.h:
	* win/tclWin32Dll.c: modify the stack checking algorithm to
	recheck in case of failure. The working assumptions are now that
	(a) a thread's stack is never moved, and (b) a thread's stack can
	grow but not shrink. Port to windows - could be more efficient,
	but is already cheaper than it was.

2 files changed, 25 insertions, 27 deletions

diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index 09ec05d..2684986 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -14,7 +14,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclBasic.c,v 1.272 2007/11/10 03:40:17 das Exp $
+ * RCS: @(#) $Id: tclBasic.c,v 1.273 2007/11/10 16:08:09 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -334,33 +334,20 @@ static const OpCmdInfo mathOpCmds[] = {
 		{0},			NULL }
 };
 
-#ifdef TCL_NO_STACK_CHECK
-#define CheckStackSpace(interp, localIntPtr) 1
-#else /* stack check enabled */
-#ifdef _TCLUNIXPORT
-/*
- * A unix system: cache the stack check parameters.
- */
-
+#ifndef TCL_NO_STACK_CHECK
 static int stackGrowsDown = 1;
 
 #define GetCStackParams(iPtr) \
-    stackGrowsDown = TclpGetCStackParams(&(iPtr)->stackBound)
+    stackGrowsDown = TclpGetCStackParams(&((iPtr)->stackBoundPtr))
 
 #define CheckStackSpace(iPtr, localIntPtr) \
     (stackGrowsDown \
-        ? ((localIntPtr) > (iPtr)->stackBound)	\
-	: ((localIntPtr) < (iPtr)->stackBound)	\
+	    ? ((localIntPtr) > *((iPtr)->stackBoundPtr))	\
+	    : ((localIntPtr) < *((iPtr)->stackBoundPtr))	\
     )
-#else /* not unix */
-/*
- * FIXME: can we do something similar for other platforms, especially windows? 
- */
-
-#define GetCStackParams(iPtr)
-#define CheckStackSpace(interp, localIntPtr) \
-    TclpCheckStackSpace()
-#endif
+#else /* stack check disabled: make them noops */
+#define CheckStackSpace(interp, localIntPtr) 1
+#define GetCStackParams(iPtr) 
 #endif
 
 
@@ -3420,7 +3407,7 @@ int
 TclInterpReady(
     Tcl_Interp *interp)
 {
-    int localInt; /* used for checking the stack */
+    int localInt, stackOverflow; /* used for checking the stack */
     register Interp *iPtr = (Interp *) interp;
 
     /*
@@ -3448,8 +3435,17 @@ TclInterpReady(
      * probably because of an infinite loop somewhere.
      */
 
-    if (((iPtr->numLevels) > iPtr->maxNestingDepth)
-	    || (CheckStackSpace(iPtr, &localInt) == 0)) {
+    stackOverflow = !CheckStackSpace(iPtr, &localInt); 
+    if (stackOverflow) {
+	/*
+	 * Update the stack params in case the thread's stack was grown.
+	 */
+
+	GetCStackParams(iPtr);
+	stackOverflow = !CheckStackSpace(iPtr, &localInt); 
+    }
+    
+    if (stackOverflow || ((iPtr->numLevels) > iPtr->maxNestingDepth)) {
 	Tcl_AppendResult(interp,
 		"too many nested evaluations (infinite loop?)", NULL);
 	return TCL_ERROR;
diff --git a/generic/tclInt.h b/generic/tclInt.h
index af62562..1dc744c 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -13,7 +13,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclInt.h,v 1.338 2007/11/09 21:35:18 msofer Exp $
+ * RCS: @(#) $Id: tclInt.h,v 1.339 2007/11/10 16:08:10 msofer Exp $
  */
 
 #ifndef _TCLINT
@@ -1855,7 +1855,7 @@ typedef struct Interp {
 				    * tclObj.c and tclThreadAlloc.c */ 
     int        *asyncReadyPtr;     /* Pointer to the asyncReady indicator for
 				    * this interp's thread; see tclAsync.c */
-    int        *stackBound;        /* Pointer to the limit stack address
+    int        **stackBoundPtr;    /* Pointer to the limit stack address
 				    * allowable for invoking a new command
 				    * without "risking" a C-stack overflow;
 				    * see TclpCheckStackSpace in the
@@ -2501,8 +2501,10 @@ MODULE_SCOPE void	TclParseInit(Tcl_Interp *interp, CONST char *string,
 MODULE_SCOPE int	TclParseAllWhiteSpace(CONST char *src, int numBytes);
 MODULE_SCOPE int	TclProcessReturn(Tcl_Interp *interp,
 			    int code, int level, Tcl_Obj *returnOpts);
+#ifndef TCL_NO_STACK_CHECK
+MODULE_SCOPE int        TclpGetCStackParams(int ***stackBound);
+#endif
 MODULE_SCOPE int	TclpObjLstat(Tcl_Obj *pathPtr, Tcl_StatBuf *buf);
-MODULE_SCOPE int	TclpCheckStackSpace(void);
 MODULE_SCOPE Tcl_Obj *	TclpTempFileName(void);
 MODULE_SCOPE Tcl_Obj *	TclNewFSPathObj(Tcl_Obj *dirPtr, CONST char *addStrRep,
 			    int len);