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authorvasiljevic <zv@archiware.com>2008-04-27 08:05:36 (GMT)
committervasiljevic <zv@archiware.com>2008-04-27 08:05:36 (GMT)
commit1fbfeae31be33fc423d361863f7cdbf1035167fe (patch)
treec8f5579f5d883bc5d06c2e3797eddc243761a8fa /generic
parente56b4f5bbf2cf2a602730b664a8ad82cb816ca87 (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.c43
1 files changed, 29 insertions, 14 deletions
diff --git a/generic/tclAsync.c b/generic/tclAsync.c
index c088ce5..dcde29e 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 1.13.2.1 2008/04/27 08:05:39 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.
+ *
*----------------------------------------------------------------------
*/
@@ -268,7 +275,14 @@ Tcl_AsyncDelete(
{
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
AsyncHandler *asyncPtr = (AsyncHandler *) async;
- AsyncHandler *prevPtr;
+ AsyncHandler *prevPtr, *thisPtr;
+
+ /*
+ * 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?).
+ */
/*
* Conservatively check the existence of the linked list of
@@ -278,21 +292,22 @@ Tcl_AsyncDelete(
*/
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);