From 49a9c50ea8b7cbe92684a707f985792b06d17f1e Mon Sep 17 00:00:00 2001
From: Joerg Bornemann <joerg.bornemann@digia.com>
Date: Sat, 29 Sep 2012 18:37:56 +0200
Subject: [PATCH] QWindowsPipeReader: use CancelIoEx on Windows >= Vista

This cancels only the I/O operation of the reader and not all
operations on the handle.

Change-Id: Ie442199534cf45e58bb2e053da9fecee961a460e
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
---
 src/corelib/io/qwindowspipereader.cpp | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/corelib/io/qwindowspipereader.cpp b/src/corelib/io/qwindowspipereader.cpp
index 8a06a7ba21..cca6e80810 100644
--- a/src/corelib/io/qwindowspipereader.cpp
+++ b/src/corelib/io/qwindowspipereader.cpp
@@ -64,10 +64,25 @@ QWindowsPipeReader::QWindowsPipeReader(QObject *parent)
     connect(dataReadNotifier, &QWinOverlappedIoNotifier::notified, this, &QWindowsPipeReader::notified);
 }
 
+static void qt_cancelIo(HANDLE handle, OVERLAPPED *overlapped)
+{
+    typedef BOOL (WINAPI *PtrCancelIoEx)(HANDLE, LPOVERLAPPED);
+    static PtrCancelIoEx ptrCancelIoEx = 0;
+    if (!ptrCancelIoEx) {
+        HMODULE kernel32 = GetModuleHandleA("kernel32");
+        if (kernel32)
+            ptrCancelIoEx = PtrCancelIoEx(GetProcAddress(kernel32, "CancelIoEx"));
+    }
+    if (ptrCancelIoEx)
+        ptrCancelIoEx(handle, overlapped);
+    else
+        CancelIo(handle);
+}
+
 QWindowsPipeReader::~QWindowsPipeReader()
 {
     if (readSequenceStarted) {
-        CancelIo(handle);
+        qt_cancelIo(handle, &overlapped);
         dataReadNotifier->waitForNotified(-1, &overlapped);
     }
 }