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authorvasiljevic <zv@archiware.com>2008-04-26 11:53:23 (GMT)
committervasiljevic <zv@archiware.com>2008-04-26 11:53:23 (GMT)
commit99a92c56e27cbad54bae820d66f83a04065da5e6 (patch)
tree1963ab9b3bc532cce9da723f3d9c758bb1f5bca6 /generic
parent73658e4d1b3f4b4ffc846c711a9d55c64d16b61b (diff)
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generic/tclAsync.c: Tcl_AsyncDelete(): panic if attempt
to locate handler token fails. Happens when some other thread attempts to delete somebody else's token.
Diffstat (limited to 'generic')
-rw-r--r--generic/tclAsync.c44
1 files changed, 26 insertions, 18 deletions
diff --git a/generic/tclAsync.c b/generic/tclAsync.c
index c088ce5..2fd4347 100644
--- a/generic/tclAsync.c
+++ b/generic/tclAsync.c
@@ -11,7 +11,7 @@
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
- * RCS: @(#) $Id: tclAsync.c,v 1.13 2007/12/13 15:23:14 dgp Exp $
+ * RCS: @(#) $Id: tclAsync.c,v 1.14 2008/04/26 11:53:24 vasiljevic Exp $
*/
#include "tclInt.h"
@@ -259,6 +259,13 @@ Tcl_AsyncInvoke(
* Side effects:
* The state associated with the handler is deleted.
*
+ * Failure to locate the handler in current thread private list
+ * of async handlers will result in panic; exception: the list
+ * is already empty (potential trouble?).
+ * Consequently, threads should create and delete handlers
+ * themselves. I.e. a handler created by one should not be
+ * deleted by some other thread.
+ *
*----------------------------------------------------------------------
*/
@@ -268,31 +275,32 @@ Tcl_AsyncDelete(
{
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
AsyncHandler *asyncPtr = (AsyncHandler *) async;
- AsyncHandler *prevPtr;
+ AsyncHandler *prevPtr, *thisPtr;
/*
- * Conservatively check the existence of the linked list of
- * registered handlers, as we may come at this point even
- * when the TSD's for the current thread have been already
- * garbage-collected.
+ * If we come to this point when TSD's for the current
+ * thread have already been garbage-collected, we are
+ * in the _serious_ trouble. OTOH, we tolerate calling
+ * with already cleaned-up handler list (should we?).
*/
Tcl_MutexLock(&tsdPtr->asyncMutex);
- if (tsdPtr->firstHandler != NULL ) {
- if (tsdPtr->firstHandler == asyncPtr) {
+ if (tsdPtr->firstHandler != NULL) {
+ prevPtr = thisPtr = tsdPtr->firstHandler;
+ while (thisPtr != NULL && thisPtr != asyncPtr) {
+ prevPtr = thisPtr;
+ thisPtr = thisPtr->nextPtr;
+ }
+ if (thisPtr == NULL) {
+ panic("Tcl_AsyncDelete: cannot find async handler");
+ }
+ if (asyncPtr == tsdPtr->firstHandler) {
tsdPtr->firstHandler = asyncPtr->nextPtr;
- if (tsdPtr->firstHandler == NULL) {
- tsdPtr->lastHandler = NULL;
- }
} else {
- prevPtr = tsdPtr->firstHandler;
- while (prevPtr->nextPtr != asyncPtr) {
- prevPtr = prevPtr->nextPtr;
- }
prevPtr->nextPtr = asyncPtr->nextPtr;
- if (tsdPtr->lastHandler == asyncPtr) {
- tsdPtr->lastHandler = prevPtr;
- }
+ }
+ if (asyncPtr == tsdPtr->lastHandler) {
+ tsdPtr->lastHandler = prevPtr;
}
}
Tcl_MutexUnlock(&tsdPtr->asyncMutex);