QWindowsPipeWriter: ensure validity of the write buffer

QWindowsPipeWriter uses asynchronous API to perform writing. Once a cycle
has been started, the write buffer must remain valid until the write
operation is completed.

To avoid data corruption and possibly undefined behavior, this patch
makes QWindowsPipeWriter::write() take a QByteArray, which it keeps alive
for the duration of the write cycle.

Autotest-by: Thomas Hartmann
Task-number: QTBUG-52401
Change-Id: Ia35faee735c4e684267daa1f6bd689512b670cd2
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

1 files changed, 2 insertions, 21 deletions

diff --git a/src/corelib/io/qprocess.cpp b/src/corelib/io/qprocess.cpp
index 68f7157ad2..502628489d 100644
--- a/src/corelib/io/qprocess.cpp
+++ b/src/corelib/io/qprocess.cpp
@@ -1051,7 +1051,6 @@ bool QProcessPrivate::_q_canReadStandardError()
 */
 bool QProcessPrivate::_q_canWrite()
 {
-    Q_Q(QProcess);
     if (stdinChannel.notifier)
         stdinChannel.notifier->setEnabled(false);
 
@@ -1062,31 +1061,13 @@ bool QProcessPrivate::_q_canWrite()
         return false;
     }
 
-    qint64 written = writeToStdin(stdinChannel.buffer.readPointer(),
-                                      stdinChannel.buffer.nextDataBlockSize());
-    if (written < 0) {
-        closeChannel(&stdinChannel);
-        setErrorAndEmit(QProcess::WriteError);
-        return false;
-    }
+    const bool writeSucceeded = writeToStdin();
 
-#if defined QPROCESS_DEBUG
-    qDebug("QProcessPrivate::canWrite(), wrote %d bytes to the process input", int(written));
-#endif
-
-    if (written != 0) {
-        stdinChannel.buffer.free(written);
-        if (!emittedBytesWritten) {
-            emittedBytesWritten = true;
-            emit q->bytesWritten(written);
-            emittedBytesWritten = false;
-        }
-    }
     if (stdinChannel.notifier && !stdinChannel.buffer.isEmpty())
         stdinChannel.notifier->setEnabled(true);
     if (stdinChannel.buffer.isEmpty() && stdinChannel.closed)
         closeWriteChannel();
-    return true;
+    return writeSucceeded;
 }
 
 /*!