Debugger: Introduce a pty based channel to inferiors

This is experimental for now and requires QTC_USE_PTY=1
in the environment to be used.

Change-Id: I460ce7b9283467d481e903f731f4243b7e5ec094
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@theqtcompany.com>
Reviewed-by: hjk <hjk@theqtcompany.com>

src/plugins/debugger/terminal.cpp

@@ -0,0 +1,169 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://www.qt.io/licensing.  For further information
+** use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file.  Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+
+#include "terminal.h"
+
+#include <QDebug>
+#include <QIODevice>
+#include <QSocketNotifier>
+
+#include <utils/qtcassert.h>
+
+#ifdef Q_OS_UNIX
+#   define DEBUGGER_USE_TERMINAL
+#endif
+
+#ifdef DEBUGGER_USE_TERMINAL
+#   include <errno.h>
+#   include <fcntl.h>
+#   include <stdlib.h>
+#   include <string.h>
+#   include <unistd.h>
+#   include <sys/ioctl.h>
+#   include <sys/stat.h>
+#endif
+
+namespace Debugger {
+namespace Internal {
+
+static QString currentError()
+{
+    int err = errno;
+    return QString::fromLatin1(strerror(err));
+}
+
+Terminal::Terminal(QObject *parent)
+   : QObject(parent), m_isUsable(false), m_masterFd(-1), m_masterReader(0)
+{
+}
+
+void Terminal::setup()
+{
+#ifdef DEBUGGER_USE_TERMINAL
+    if (!qEnvironmentVariableIsSet("QTC_USE_PTY"))
+        return;
+
+    m_masterFd = ::open("/dev/ptmx", O_RDWR);
+    if (m_masterFd < 0) {
+        error(tr("Terminal: Cannot open /dev/ptmx: %1").arg(currentError()));
+        return;
+    }
+
+    const char *sName = ptsname(m_masterFd);
+    if (!sName) {
+        error(tr("Terminal: ptsname failed: %1").arg(currentError()));
+        return;
+    }
+    m_slaveName = sName;
+
+    struct stat s;
+    int r = ::stat(m_slaveName.constData(), &s);
+    if (r != 0) {
+        error(tr("Terminal: Error: %1").arg(currentError()));
+        return;
+    }
+    if (!S_ISCHR(s.st_mode)) {
+        error(tr("Terminal: Slave is no character device"));
+        return;
+    }
+
+    m_masterReader = new QSocketNotifier(m_masterFd, QSocketNotifier::Read, this);
+    connect(m_masterReader, &QSocketNotifier::activated,
+            this, &Terminal::onSlaveReaderActivated);
+
+    r = grantpt(m_masterFd);
+    if (r != 0) {
+        error(tr("Terminal: grantpt failed: %1").arg(currentError()));
+        return;
+    }
+
+    r = unlockpt(m_masterFd);
+    if (r != 0) {
+        error(tr("Terminal: unlock failed: %1").arg(currentError()));
+        return;
+    }
+
+    m_isUsable = true;
+#endif
+}
+
+bool Terminal::isUsable() const
+{
+    return m_isUsable;
+}
+
+int Terminal::write(const QByteArray &msg)
+{
+#ifdef DEBUGGER_USE_TERMINAL
+    return ::write(m_masterFd, msg.constData(), msg.size());
+#else
+    Q_UNUSED(msg);
+    return -1;
+#endif
+}
+
+bool Terminal::sendInterrupt()
+{
+#ifdef DEBUGGER_USE_TERMINAL
+    if (!m_isUsable)
+        return false;
+    ssize_t written = ::write(m_masterFd, "\003", 1);
+    return written == 1;
+#else
+    return false;
+#endif
+}
+
+void Terminal::onSlaveReaderActivated(int fd)
+{
+#ifdef DEBUGGER_USE_TERMINAL
+    ssize_t available = 0;
+    int ret = ::ioctl(fd, FIONREAD, (char *) &available);
+    if (ret != 0)
+        return;
+
+    QByteArray buffer(available, Qt::Uninitialized);
+    ssize_t got = ::read(fd, buffer.data(), available);
+    int err = errno;
+    if (got < 0) {
+        error(tr("Terminal: Read failed: %1").arg(QString::fromLatin1(strerror(err))));
+        return;
+    }
+    buffer.resize(got);
+    if (got >= 0)
+        stdOutReady(QString::fromUtf8(buffer));
+#else
+    Q_UNUSED(fd);
+#endif
+}
+
+} // namespace Internal
+} // namespace Debugger
+