* generic/tclBasic.c:

	* generic/tclInt.h:
	* unix/tclUnixInit.c:
	* win/tclWin32Dll.c: restore simpler behaviour for stack checking,
	not adaptive to stack size changes after a thread is
	launched. Consensus is that "nobody does that", and so it is not
	worth the cost.

5 files changed, 70 insertions, 56 deletions

diff --git a/ChangeLog b/ChangeLog
index e7eb651..065efec 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2007-11-10  Miguel Sofer  <msofer@users.sf.net>
+
+	* generic/tclBasic.c:
+	* generic/tclInt.h:
+	* unix/tclUnixInit.c:
+	* win/tclWin32Dll.c: restore simpler behaviour for stack checking,
+	not adaptive to stack size changes after a thread is
+	launched. Consensus is that "nobody does that", and so it is not
+	worth the cost.
+
 2007-11-10  Kevin Kenny  <kennykb@acm.org>
 
 	* win/tclWin32Dll.c: Rewrote the Windows stack checking algorithm
diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index 2684986..53cd4fd 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 1.273 2007/11/10 16:08:09 msofer Exp $
+ * RCS: @(#) $Id: tclBasic.c,v 1.274 2007/11/10 19:01:34 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -338,15 +338,15 @@ static const OpCmdInfo mathOpCmds[] = {
 static int stackGrowsDown = 1;
 
 #define GetCStackParams(iPtr) \
-    stackGrowsDown = TclpGetCStackParams(&((iPtr)->stackBoundPtr))
+    stackGrowsDown = TclpGetCStackParams(&((iPtr)->stackBound))
 
-#define CheckStackSpace(iPtr, localIntPtr) \
+#define StackOverflow(iPtr, localIntPtr) \
     (stackGrowsDown \
-	    ? ((localIntPtr) > *((iPtr)->stackBoundPtr))	\
-	    : ((localIntPtr) < *((iPtr)->stackBoundPtr))	\
+	    ? ((localIntPtr) < (iPtr)->stackBound) \
+	    : ((localIntPtr) > (iPtr)->stackBound) \
     )
 #else /* stack check disabled: make them noops */
-#define CheckStackSpace(interp, localIntPtr) 1
+#define StackOverflow(interp, localIntPtr) 0
 #define GetCStackParams(iPtr) 
 #endif
 
@@ -3407,7 +3407,7 @@ int
 TclInterpReady(
     Tcl_Interp *interp)
 {
-    int localInt, stackOverflow; /* used for checking the stack */
+    int localInt; /* used for checking the stack */
     register Interp *iPtr = (Interp *) interp;
 
     /*
@@ -3435,17 +3435,8 @@ TclInterpReady(
      * probably because of an infinite loop somewhere.
      */
 
-    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)) {
+    if (((iPtr->numLevels) > iPtr->maxNestingDepth)
+	    || StackOverflow(iPtr, &localInt)) {
 	Tcl_AppendResult(interp,
 		"too many nested evaluations (infinite loop?)", NULL);
 	return TCL_ERROR;
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 1dc744c..6a72767 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 1.339 2007/11/10 16:08:10 msofer Exp $
+ * RCS: @(#) $Id: tclInt.h,v 1.340 2007/11/10 19:01:35 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        **stackBoundPtr;    /* Pointer to the limit stack address
+    int        *stackBound;        /* Pointer to the limit stack address
 				    * allowable for invoking a new command
 				    * without "risking" a C-stack overflow;
 				    * see TclpCheckStackSpace in the
@@ -2502,7 +2502,7 @@ 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);
+MODULE_SCOPE int        TclpGetCStackParams(int **stackBoundPtr);
 #endif
 MODULE_SCOPE int	TclpObjLstat(Tcl_Obj *pathPtr, Tcl_StatBuf *buf);
 MODULE_SCOPE Tcl_Obj *	TclpTempFileName(void);
diff --git a/unix/tclUnixInit.c b/unix/tclUnixInit.c
index 4ae061c..86edc38 100644
--- a/unix/tclUnixInit.c
+++ b/unix/tclUnixInit.c
@@ -7,7 +7,7 @@
  * Copyright (c) 1999 by Scriptics Corporation.
  * All rights reserved.
  *
- * RCS: @(#) $Id: tclUnixInit.c,v 1.75 2007/11/10 16:08:10 msofer Exp $
+ * RCS: @(#) $Id: tclUnixInit.c,v 1.76 2007/11/10 19:01:35 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -78,7 +78,6 @@
 typedef struct ThreadSpecificData {
     int *outerVarPtr;		/* The "outermost" stack frame pointer for
 				 * this thread. */
-    int stackDetermineResult;	/* What happened when we did that? */
     int *stackBound;            /* The current stack boundary */
 } ThreadSpecificData;
 static Tcl_ThreadDataKey dataKey;
@@ -1028,21 +1027,21 @@ TclpFindVariable(
 #ifndef TCL_NO_STACK_CHECK
 int
 TclpGetCStackParams(
-    int ***stackBoundPtr)
+    int **stackBoundPtr)
 {
-    int localVar;
-    size_t stackSize;		/* The size of the current stack. */
+    int result = TCL_OK;
+    size_t stackSize = 0;	/* The size of the current stack. */
     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
 				/* Most variables are actually in a
 				 * thread-specific data block to minimise the
 				 * impact on the stack. */
-	
+    
     if (stackGrowsDown == -1) {
 	/*
 	 * Not initialised!
 	 */
 
-	stackGrowsDown = StackGrowsDown(&localVar);
+	stackGrowsDown = StackGrowsDown(&result);
     }
 
     /*
@@ -1051,37 +1050,47 @@ TclpGetCStackParams(
      */
 
     if (tsdPtr->outerVarPtr == NULL) {
-	tsdPtr->outerVarPtr = &localVar;
-	tsdPtr->stackDetermineResult = GetStackSize(&stackSize);
+	tsdPtr->outerVarPtr = &result;
+	result = GetStackSize(&stackSize);
+	if (result != TCL_OK) {
+	    /* Can't check, assume it always succeeds */
+	    stackGrowsDown = 1;
+	    tsdPtr->stackBound = NULL;
+	    goto done;
+	}
     }
 
-    if ((stackGrowsDown && (&localVar < tsdPtr->stackBound))
-	    || (!stackGrowsDown && (&localVar > tsdPtr->stackBound))) {
-	/*
-	 * Stack failure - if we didn't already blow up, we are within the
-	 * safety area. Recheck with the OS in case the stack was grown.
-	 */
+    if (stackSize || (stackGrowsDown && (&result < tsdPtr->stackBound))
+		|| (!stackGrowsDown && (&result > tsdPtr->stackBound))) {
+	    /*
+	     * Either the thread's first pass or stack failure: set the params
+	     */
 
-	tsdPtr->stackDetermineResult = GetStackSize(&stackSize);
-    }
+	if (!stackSize) {
+	    /*
+	     * Stack failure: if we didn't already blow up, we are within the
+	     * safety area. Recheck with the OS in case the stack was grown. 
+	     */
+	    result = GetStackSize(&stackSize);
+	    if (result != TCL_OK) {
+		/* Can't check, assume it always succeeds */
+		stackGrowsDown = 1;
+		tsdPtr->stackBound = NULL;
+		goto done;
+	    }
+	}
 
-    if (tsdPtr->stackDetermineResult != TCL_OK) {
-	switch (tsdPtr->stackDetermineResult) {
-	    case TCL_BREAK:
-		STACK_DEBUG(("skipping stack checks with failure\n"));
-	    case TCL_CONTINUE:
-		STACK_DEBUG(("skipping stack checks with success\n"));
+	if (stackGrowsDown) {
+	    tsdPtr->stackBound = (int *) ((char *)tsdPtr->outerVarPtr -
+		    stackSize);
+	} else {
+	    tsdPtr->stackBound = (int *) ((char *)tsdPtr->outerVarPtr +
+		    stackSize);
 	}
-	stackGrowsDown = 1;
-	tsdPtr->stackBound = NULL;
-    } else if (stackGrowsDown) {
-	tsdPtr->stackBound = (int *) ((char *)tsdPtr->outerVarPtr -
-		stackSize);
-    } else {
-	tsdPtr->stackBound = (int *) ((char *)tsdPtr->outerVarPtr +
-		stackSize);
     }
-    *stackBoundPtr = &(tsdPtr->stackBound);
+
+    done:
+    *stackBoundPtr = tsdPtr->stackBound;
     return stackGrowsDown;
 }
 
@@ -1132,6 +1141,7 @@ GetStackSize(
 	/*
 	 * Some kind of confirmed error?!
 	 */
+	STACK_DEBUG(("skipping stack checks with failure\n"));
 	return TCL_BREAK;
     }
     if (rawStackSize > 0) {
@@ -1149,12 +1159,14 @@ GetStackSize(
 	/*
 	 * getrlimit() failed, just fail the whole thing.
 	 */
+	STACK_DEBUG(("skipping stack checks with failure: getrlimit failed\n"));
 	return TCL_BREAK;
     }
     if (rLimit.rlim_cur == RLIM_INFINITY) {
 	/*
 	 * Limit is "infinite"; there is no stack limit.
 	 */
+	STACK_DEBUG(("skipping stack checks with success: infinite limit\n"));
 	return TCL_CONTINUE;
     }
     rawStackSize = rLimit.rlim_cur;
@@ -1169,6 +1181,7 @@ GetStackSize(
   finalSanityCheck:
 #endif
     if (rawStackSize <= 0) {
+	STACK_DEBUG(("skipping stack checks with success\n"));
 	return TCL_CONTINUE;
     }
 
diff --git a/win/tclWin32Dll.c b/win/tclWin32Dll.c
index 0ad344e..e7d20f5 100644
--- a/win/tclWin32Dll.c
+++ b/win/tclWin32Dll.c
@@ -10,7 +10,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclWin32Dll.c,v 1.51 2007/11/10 17:40:35 kennykb Exp $
+ * RCS: @(#) $Id: tclWin32Dll.c,v 1.52 2007/11/10 19:01:35 msofer Exp $
  */
 
 #include "tclWinInt.h"
@@ -544,7 +544,7 @@ TclWinNoBackslash(
 #ifndef TCL_NO_STACK_CHECK
 int
 TclpGetCStackParams(
-    int ***stackBoundPtr)
+    int **stackBoundPtr)
 {
     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
     SYSTEM_INFO si;		/* The system information, used to
@@ -592,7 +592,7 @@ TclpGetCStackParams(
 			+ TCL_WIN_STACK_THRESHOLD);
 	}
     }
-    *stackBoundPtr = &(tsdPtr->stackBound);
+    *stackBoundPtr = tsdPtr->stackBound;
     return 1;
 }
 #endif