xnu-1699.24.23.tar.gz

[apple/xnu.git] / iokit / Kernel / IODataQueue.cpp

diff --git a/iokit/Kernel/IODataQueue.cpp b/iokit/Kernel/IODataQueue.cpp
index b98060e75a6f523c5a5d62b306e23bd3d4042004..1001ebeff0a88353eeace68baecf001f5ba84aa4 100644 (file)
--- a/iokit/Kernel/IODataQueue.cpp
+++ b/iokit/Kernel/IODataQueue.cpp
@@ -1,23 +1,29 @@
 /*
  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
  *
- * @APPLE_LICENSE_HEADER_START@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
- * The contents of this file constitute Original Code as defined in and
- * are subject to the Apple Public Source License Version 1.1 (the
- * "License").  You may not use this file except in compliance with the
- * License.  Please obtain a copy of the License at
- * http://www.apple.com/publicsource and read it before using this file.
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
  * 
- * This Original Code and all software distributed under the License are
- * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
- * License for the specific language governing rights and limitations
- * under the License.
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
  * 
- * @APPLE_LICENSE_HEADER_END@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 
 #include <IOKit/IODataQueue.h>
@@ -76,9 +82,9 @@ Boolean IODataQueue::initWithCapacity(UInt32 size)
         return false;
     }
 
-    dataQueue->queueSize = size;
-    dataQueue->head = 0;
-    dataQueue->tail = 0;
+    dataQueue->queueSize    = size;
+    dataQueue->head         = 0;
+    dataQueue->tail         = 0;
 
     return true;
 }
@@ -105,24 +111,39 @@ Boolean IODataQueue::enqueue(void * data, UInt32 dataSize)
     const UInt32       tail      = dataQueue->tail;
     const UInt32       entrySize = dataSize + DATA_QUEUE_ENTRY_HEADER_SIZE;
     IODataQueueEntry * entry;
-    
+
     if ( tail >= head )
     {
-        if ( (tail + entrySize) < dataQueue->queueSize )
+        // Is there enough room at the end for the entry?
+        if ( (tail + entrySize) <= dataQueue->queueSize )
         {
             entry = (IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail);
 
             entry->size = dataSize;
             memcpy(&entry->data, data, dataSize);
+
+            // The tail can be out of bound when the size of the new entry
+            // exactly matches the available space at the end of the queue.
+            // The tail can range from 0 to dataQueue->queueSize inclusive.
+
             dataQueue->tail += entrySize;
         }
-        else if ( head > entrySize )
+        else if ( head > entrySize )   // Is there enough room at the beginning?
         {
             // Wrap around to the beginning, but do not allow the tail to catch
             // up to the head.
 
             dataQueue->queue->size = dataSize;
-            ((IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail))->size = dataSize;
+
+            // We need to make sure that there is enough room to set the size before
+            // doing this. The user client checks for this and will look for the size
+            // at the beginning if there isn't room for it at the end.
+
+            if ( ( dataQueue->queueSize - tail ) >= DATA_QUEUE_ENTRY_HEADER_SIZE )
+            {
+                ((IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail))->size = dataSize;
+            }
+
             memcpy(&dataQueue->queue->data, data, dataSize);
             dataQueue->tail = entrySize;
         }
@@ -187,8 +208,8 @@ void IODataQueue::sendDataAvailableNotification()
     mach_msg_header_t *        msgh;
 
     msgh = (mach_msg_header_t *)notifyMsg;
-    if (msgh) {
-        kr = mach_msg_send_from_kernel(msgh, msgh->msgh_size);
+    if (msgh && msgh->msgh_remote_port) {
+        kr = mach_msg_send_from_kernel_proper(msgh, msgh->msgh_size);
         switch(kr) {
             case MACH_SEND_TIMED_OUT:  // Notification already sent
             case MACH_MSG_SUCCESS: