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authorMiguel Sofer <miguel.sofer@gmail.com>2007-11-10 16:08:08 (GMT)
committerMiguel Sofer <miguel.sofer@gmail.com>2007-11-10 16:08:08 (GMT)
commit0e7fa3edd23cef23c43109db2656ccc52978c99b (patch)
treea9e86cd8a43c61ca632591c69b5c3b042f0219ca /win/tclWin32Dll.c
parent9f42d64486d78ab2ab370e552ded7578ed2966c6 (diff)
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* 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.
Diffstat (limited to 'win/tclWin32Dll.c')
-rw-r--r--win/tclWin32Dll.c96
1 files changed, 90 insertions, 6 deletions
diff --git a/win/tclWin32Dll.c b/win/tclWin32Dll.c
index c196705..8ffb697 100644
--- a/win/tclWin32Dll.c
+++ b/win/tclWin32Dll.c
@@ -10,11 +10,22 @@
* 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 1.48 2005/11/04 00:06:50 dkf Exp $
+ * RCS: @(#) $Id: tclWin32Dll.c,v 1.49 2007/11/10 16:08:10 msofer Exp $
*/
#include "tclWinInt.h"
+#ifndef TCL_NO_STACK_CHECK
+/*
+ * The following functions implement stack depth checking
+ */
+typedef struct ThreadSpecificData {
+ int *stackBound; /* The current stack boundary */
+} ThreadSpecificData;
+static Tcl_ThreadDataKey dataKey;
+static int * CheckStackSpace(void)
+#endif /* TCL_NO_STACK_CHECK */
+
/*
* The following data structures are used when loading the thunking library
* for execing child processes under Win32s.
@@ -511,16 +522,18 @@ TclWinNoBackslash(
return path;
}
+#ifndef TCL_NO_STACK_CHECK
/*
*----------------------------------------------------------------------
*
- * TclpCheckStackSpace --
+ * CheckStackSpace --
*
* Detect if we are about to blow the stack. Called before an evaluation
* can happen when nesting depth is checked.
*
* Results:
- * 1 if there is enough stack space to continue; 0 if not.
+ * A pointer to the deepest safe stack location that was determined, or
+ * NULL if we are about to blow the stack.
*
* Side effects:
* None.
@@ -528,8 +541,8 @@ TclWinNoBackslash(
*----------------------------------------------------------------------
*/
-int
-TclpCheckStackSpace(void)
+static int *
+CheckStackSpace(void)
{
#ifdef HAVE_NO_SEH
@@ -633,8 +646,79 @@ TclpCheckStackSpace(void)
} __except (EXCEPTION_EXECUTE_HANDLER) {}
#endif /* HAVE_NO_SEH */
- return retval;
+ if (retval) {
+ return (int *) ((char *)&retval - TCL_WIN_STACK_THRESHOLD);
+ } else {
+ return NULL;
+ }
}
+#endif
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpGetStackParams --
+ *
+ * Determine the stack params for the current thread: in which
+ * direction does the stack grow, and what is the stack lower (resp.
+ * upper) bound for safe invocation of a new command? This is used to
+ * cache the values needed for an efficient computation of
+ * TclpCheckStackSpace() when the interp is known.
+ *
+ * Results:
+ * Returns 1 if the stack grows down, in which case a stack lower bound
+ * is stored at stackBoundPtr. If the stack grows up, 0 is returned and
+ * an upper bound is stored at stackBoundPtr. If a bound cannot be
+ * determined NULL is stored at stackBoundPtr.
+ *
+ *----------------------------------------------------------------------
+ */
+
+#ifndef TCL_NO_STACK_CHECK
+int
+TclpGetCStackParams(
+ int ***stackBoundPtr)
+{
+ int localVar, *stackBound;
+ ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
+ /* Most variables are actually in a
+ * thread-specific data block to minimise the
+ * impact on the stack. */
+
+ if (!tsdPtr->stackBound || (&localVar < tsdPtr->stackBound)) {
+ /*
+ * First time through in this thread or apparent stack failure. If we
+ * didn't already blow up, we are within the safety area. Recheck with
+ * the OS to get a new estimate.
+ */
+
+ stackBound = CheckStackSpace();
+ if (!stackBound) {
+ /*
+ * We are really blowing the stack! Do not update the estimate we
+ * already had, just return.
+ */
+
+ if (!tsdPtr->stackBound) {
+ /*
+ * ??? First time around: this thread was born with a stack
+ * smaller than TCL_WIN_STACK_THRESHOLD. What do we do now?
+ * Initialise to something that will always fail? Choose for
+ * instance 1K ints above the current depth.
+ */
+
+ tsdPtr->stackBound = (&localVar + 1024);
+ }
+ } else {
+ tsdPtr->stackBound = stackBound;
+ }
+ }
+
+ *stackBoundPtr = &(tsdPtr->stackBound);
+ return 1;
+}
+#endif
+
/*
*---------------------------------------------------------------------------