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kwin/main_x11.cpp
Martin Gräßlin fbab204968 [effects] Add a screenshot dbus method which takes a file descriptor 
Summary:
The idea behind this mode is to support applications like spectacle
(see T4458). The calling application passes a file descriptor (created
through e.g. a pipe) and the screenshot effect writes the captured image
into that fd.

The advantage over the existing variant which writes to a file in the
/tmp directory is that this is peer-to-peer between the requesting
application and KWin. No other application can get to that image.

The change also includes setting SIGPIPE to ignore. It showed that when
the reading side already cancelled the read prior to KWin writing out
the image we get a SIGPIPE which results in application termination,
which is not what we want in case of a Wayland compositor. The sigpipe
can be ignored as Qt (and libpng) handles that error just fine at
runtime.

Reviewers: #kwin, #plasma_on_wayland

Subscribers: plasma-devel, kwin

Tags: #plasma_on_wayland, #kwin

Differential Revision: https://phabricator.kde.org/D3412
2016-11-22 07:17:57 +01:00

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/********************************************************************
KWin - the KDE window manager
This file is part of the KDE project.
Copyright (C) 1999, 2000 Matthias Ettrich <ettrich@kde.org>
Copyright (C) 2003 Lubos Lunak <l.lunak@kde.org>
Copyright (C) 2014 Martin Gräßlin <mgraesslin@kde.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*********************************************************************/
#include "main_x11.h"
#include <config-kwin.h>
// kwin
#include "platform.h"
#include "sm.h"
#include "workspace.h"
#include "xcbutils.h"
// KDE
#include <KConfigGroup>
#include <KCrash>
#include <KLocalizedString>
#include <KPluginLoader>
#include <KPluginMetaData>
// Qt
#include <qplatformdefs.h>
#include <QComboBox>
#include <QCommandLineParser>
#include <QDialog>
#include <QDialogButtonBox>
#include <QFile>
#include <QLabel>
#include <QPushButton>
#include <QVBoxLayout>
#include <QX11Info>
// system
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif // HAVE_UNISTD_H
#include <iostream>
Q_LOGGING_CATEGORY(KWIN_CORE, "kwin_core", QtCriticalMsg)
namespace KWin
{
static void sighandler(int)
{
QApplication::exit();
}
class AlternativeWMDialog : public QDialog
{
public:
AlternativeWMDialog()
: QDialog() {
QWidget* mainWidget = new QWidget(this);
QVBoxLayout* layout = new QVBoxLayout(mainWidget);
QString text = i18n(
"KWin is unstable.\n"
"It seems to have crashed several times in a row.\n"
"You can select another window manager to run:");
QLabel* textLabel = new QLabel(text, mainWidget);
layout->addWidget(textLabel);
wmList = new QComboBox(mainWidget);
wmList->setEditable(true);
layout->addWidget(wmList);
addWM(QStringLiteral("metacity"));
addWM(QStringLiteral("openbox"));
addWM(QStringLiteral("fvwm2"));
addWM(QStringLiteral(KWIN_INTERNAL_NAME_X11));
QVBoxLayout *mainLayout = new QVBoxLayout(this);
mainLayout->addWidget(mainWidget);
QDialogButtonBox *buttons = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel, this);
buttons->button(QDialogButtonBox::Ok)->setDefault(true);
connect(buttons, &QDialogButtonBox::accepted, this, &QDialog::accept);
connect(buttons, &QDialogButtonBox::rejected, this, &QDialog::reject);
mainLayout->addWidget(buttons);
raise();
}
void addWM(const QString& wm) {
// TODO: Check if WM is installed
if (!QStandardPaths::findExecutable(wm).isEmpty())
wmList->addItem(wm);
}
QString selectedWM() const {
return wmList->currentText();
}
private:
QComboBox* wmList;
};
//************************************
// KWinSelectionOwner
//************************************
KWinSelectionOwner::KWinSelectionOwner(int screen_P)
: KSelectionOwner(make_selection_atom(screen_P), screen_P)
{
}
xcb_atom_t KWinSelectionOwner::make_selection_atom(int screen_P)
{
if (screen_P < 0)
screen_P = QX11Info::appScreen();
QByteArray screen(QByteArrayLiteral("WM_S"));
screen.append(QByteArray::number(screen_P));
ScopedCPointer<xcb_intern_atom_reply_t> atom(xcb_intern_atom_reply(
connection(),
xcb_intern_atom_unchecked(connection(), false, screen.length(), screen.constData()),
nullptr));
if (atom.isNull()) {
return XCB_ATOM_NONE;
}
return atom->atom;
}
void KWinSelectionOwner::getAtoms()
{
KSelectionOwner::getAtoms();
if (xa_version == XCB_ATOM_NONE) {
const QByteArray name(QByteArrayLiteral("VERSION"));
ScopedCPointer<xcb_intern_atom_reply_t> atom(xcb_intern_atom_reply(
connection(),
xcb_intern_atom_unchecked(connection(), false, name.length(), name.constData()),
nullptr));
if (!atom.isNull()) {
xa_version = atom->atom;
}
}
}
void KWinSelectionOwner::replyTargets(xcb_atom_t property_P, xcb_window_t requestor_P)
{
KSelectionOwner::replyTargets(property_P, requestor_P);
xcb_atom_t atoms[ 1 ] = { xa_version };
// PropModeAppend !
xcb_change_property(connection(), XCB_PROP_MODE_APPEND, requestor_P,
property_P, XCB_ATOM_ATOM, 32, 1, atoms);
}
bool KWinSelectionOwner::genericReply(xcb_atom_t target_P, xcb_atom_t property_P, xcb_window_t requestor_P)
{
if (target_P == xa_version) {
int32_t version[] = { 2, 0 };
xcb_change_property(connection(), XCB_PROP_MODE_REPLACE, requestor_P,
property_P, XCB_ATOM_INTEGER, 32, 2, version);
} else
return KSelectionOwner::genericReply(target_P, property_P, requestor_P);
return true;
}
xcb_atom_t KWinSelectionOwner::xa_version = XCB_ATOM_NONE;
//************************************
// ApplicationX11
//************************************
ApplicationX11::ApplicationX11(int &argc, char **argv)
: Application(OperationModeX11, argc, argv)
, owner()
, m_replace(false)
{
setX11Connection(QX11Info::connection());
setX11RootWindow(QX11Info::appRootWindow());
}
ApplicationX11::~ApplicationX11()
{
destroyCompositor();
destroyWorkspace();
if (!owner.isNull() && owner->ownerWindow() != XCB_WINDOW_NONE) // If there was no --replace (no new WM)
Xcb::setInputFocus(XCB_INPUT_FOCUS_POINTER_ROOT);
}
void ApplicationX11::setReplace(bool replace)
{
m_replace = replace;
}
void ApplicationX11::lostSelection()
{
sendPostedEvents();
destroyCompositor();
destroyWorkspace();
// Remove windowmanager privileges
Xcb::selectInput(rootWindow(), XCB_EVENT_MASK_PROPERTY_CHANGE);
quit();
}
void ApplicationX11::performStartup()
{
crashChecking();
if (Application::x11ScreenNumber() == -1) {
Application::setX11ScreenNumber(QX11Info::appScreen());
}
// QSessionManager for some reason triggers a very early commitDataRequest
// and updates the key - before we create the workspace and load the session
// data -> store and pass to the workspace constructor
m_originalSessionKey = sessionKey();
owner.reset(new KWinSelectionOwner(Application::x11ScreenNumber()));
connect(owner.data(), &KSelectionOwner::failedToClaimOwnership, []{
fputs(i18n("kwin: unable to claim manager selection, another wm running? (try using --replace)\n").toLocal8Bit().constData(), stderr);
::exit(1);
});
connect(owner.data(), SIGNAL(lostOwnership()), SLOT(lostSelection()));
connect(owner.data(), &KSelectionOwner::claimedOwnership, [this]{
setupEventFilters();
// first load options - done internally by a different thread
createOptions();
// Check whether another windowmanager is running
const uint32_t maskValues[] = {XCB_EVENT_MASK_SUBSTRUCTURE_REDIRECT};
ScopedCPointer<xcb_generic_error_t> redirectCheck(xcb_request_check(connection(),
xcb_change_window_attributes_checked(connection(),
rootWindow(),
XCB_CW_EVENT_MASK,
maskValues)));
if (!redirectCheck.isNull()) {
fputs(i18n("kwin: another window manager is running (try using --replace)\n").toLocal8Bit().constData(), stderr);
if (!wasCrash()) // if this is a crash-restart, DrKonqi may have stopped the process w/o killing the connection
::exit(1);
}
createInput();
connect(platform(), &Platform::screensQueried, this,
[this] {
createWorkspace();
Xcb::sync(); // Trigger possible errors, there's still a chance to abort
notifyKSplash();
}
);
connect(platform(), &Platform::initFailed, this,
[] () {
std::cerr << "FATAL ERROR: backend failed to initialize, exiting now" << std::endl;
::exit(1);
}
);
platform()->init();
});
// we need to do an XSync here, otherwise the QPA might crash us later on
Xcb::sync();
owner->claim(m_replace || wasCrash(), true);
createAtoms();
}
bool ApplicationX11::notify(QObject* o, QEvent* e)
{
if (Workspace::self()->workspaceEvent(e))
return true;
return QApplication::notify(o, e);
}
void ApplicationX11::setupCrashHandler()
{
KCrash::setEmergencySaveFunction(ApplicationX11::crashHandler);
}
void ApplicationX11::crashChecking()
{
setupCrashHandler();
if (crashes >= 4) {
// Something has gone seriously wrong
AlternativeWMDialog dialog;
QString cmd = QStringLiteral(KWIN_INTERNAL_NAME_X11);
if (dialog.exec() == QDialog::Accepted)
cmd = dialog.selectedWM();
else
::exit(1);
if (cmd.length() > 500) {
qCDebug(KWIN_CORE) << "Command is too long, truncating";
cmd = cmd.left(500);
}
qCDebug(KWIN_CORE) << "Starting" << cmd << "and exiting";
char buf[1024];
sprintf(buf, "%s &", cmd.toAscii().data());
system(buf);
::exit(1);
}
if (crashes >= 2) {
// Disable compositing if we have had too many crashes
qCDebug(KWIN_CORE) << "Too many crashes recently, disabling compositing";
KConfigGroup compgroup(KSharedConfig::openConfig(), "Compositing");
compgroup.writeEntry("Enabled", false);
}
// Reset crashes count if we stay up for more that 15 seconds
QTimer::singleShot(15 * 1000, this, SLOT(resetCrashesCount()));
}
void ApplicationX11::crashHandler(int signal)
{
crashes++;
fprintf(stderr, "Application::crashHandler() called with signal %d; recent crashes: %d\n", signal, crashes);
char cmd[1024];
sprintf(cmd, "%s --crashes %d &",
QFile::encodeName(QCoreApplication::applicationFilePath()).constData(), crashes);
sleep(1);
system(cmd);
}
} // namespace
extern "C"
KWIN_EXPORT int kdemain(int argc, char * argv[])
{
KWin::Application::setupMalloc();
KWin::Application::setupLocalizedString();
int primaryScreen = 0;
xcb_connection_t *c = xcb_connect(nullptr, &primaryScreen);
if (!c || xcb_connection_has_error(c)) {
fprintf(stderr, "%s: FATAL ERROR while trying to open display %s\n",
argv[0], qgetenv("DISPLAY").constData());
exit(1);
}
const int number_of_screens = xcb_setup_roots_length(xcb_get_setup(c));
xcb_disconnect(c);
c = nullptr;
// multi head
auto isMultiHead = []() -> bool {
QByteArray multiHead = qgetenv("KDE_MULTIHEAD");
if (!multiHead.isEmpty()) {
return (multiHead.toLower() == "true");
}
return true;
};
if (number_of_screens != 1 && isMultiHead()) {
KWin::Application::setX11MultiHead(true);
KWin::Application::setX11ScreenNumber(primaryScreen);
int pos; // Temporarily needed to reconstruct DISPLAY var if multi-head
QByteArray display_name = qgetenv("DISPLAY");
if ((pos = display_name.lastIndexOf('.')) != -1)
display_name.remove(pos, 10); // 10 is enough to be sure we removed ".s"
QString envir;
for (int i = 0; i < number_of_screens; i++) {
// If execution doesn't pass by here, then kwin
// acts exactly as previously
if (i != KWin::Application::x11ScreenNumber() && fork() == 0) {
KWin::Application::setX11ScreenNumber(i);
QByteArray dBusSuffix = qgetenv("KWIN_DBUS_SERVICE_SUFFIX");
if (!dBusSuffix.isNull()) {
dBusSuffix.append(".");
}
dBusSuffix.append(QByteArrayLiteral("head-")).append(QByteArray::number(i));
qputenv("KWIN_DBUS_SERVICE_SUFFIX", dBusSuffix);
// Break here because we are the child process, we don't
// want to fork() anymore
break;
}
}
// In the next statement, display_name shouldn't contain a screen
// number. If it had it, it was removed at the "pos" check
envir.sprintf("DISPLAY=%s.%d", display_name.data(), KWin::Application::x11ScreenNumber());
if (putenv(strdup(envir.toAscii().constData()))) {
fprintf(stderr, "%s: WARNING: unable to set DISPLAY environment variable\n", argv[0]);
perror("putenv()");
}
}
if (signal(SIGTERM, KWin::sighandler) == SIG_IGN)
signal(SIGTERM, SIG_IGN);
if (signal(SIGINT, KWin::sighandler) == SIG_IGN)
signal(SIGINT, SIG_IGN);
if (signal(SIGHUP, KWin::sighandler) == SIG_IGN)
signal(SIGHUP, SIG_IGN);
signal(SIGPIPE, SIG_IGN);
// Disable the glib event loop integration, since it seems to be responsible
// for several bug reports about high CPU usage (bug #239963)
setenv("QT_NO_GLIB", "1", true);
// enforce xcb plugin, unfortunately command line switch has precedence
setenv("QT_QPA_PLATFORM", "xcb", true);
qunsetenv("QT_DEVICE_PIXEL_RATIO");
#if (QT_VERSION >= QT_VERSION_CHECK(5, 6, 0))
QCoreApplication::setAttribute(Qt::AA_DisableHighDpiScaling);
#endif
KWin::ApplicationX11 a(argc, argv);
a.setupTranslator();
KWin::Application::createAboutData();
QCommandLineOption replaceOption(QStringLiteral("replace"), i18n("Replace already-running ICCCM2.0-compliant window manager"));
QCommandLineParser parser;
a.setupCommandLine(&parser);
parser.addOption(replaceOption);
#ifdef KWIN_BUILD_ACTIVITIES
QCommandLineOption noActivitiesOption(QStringLiteral("no-kactivities"),
i18n("Disable KActivities integration."));
parser.addOption(noActivitiesOption);
#endif
parser.process(a);
a.processCommandLine(&parser);
a.setReplace(parser.isSet(replaceOption));
#ifdef KWIN_BUILD_ACTIVITIES
if (parser.isSet(noActivitiesOption)) {
a.setUseKActivities(false);
}
#endif
// perform sanity checks
if (a.platformName().toLower() != QStringLiteral("xcb")) {
fprintf(stderr, "%s: FATAL ERROR expecting platform xcb but got platform %s\n",
argv[0], qPrintable(a.platformName()));
exit(1);
}
if (!QX11Info::display()) {
fprintf(stderr, "%s: FATAL ERROR KWin requires Xlib support in the xcb plugin. Do not configure Qt with -no-xcb-xlib\n",
argv[0]);
exit(1);
}
// find and load the X11 platform plugin
const auto plugins = KPluginLoader::findPluginsById(QStringLiteral("org.kde.kwin.platforms"),
QStringLiteral("KWinX11Platform"));
if (plugins.isEmpty()) {
std::cerr << "FATAL ERROR: KWin could not find the KWinX11Platform plugin" << std::endl;
return 1;
}
a.initPlatform(plugins.first());
if (!a.platform()) {
std::cerr << "FATAL ERROR: could not instantiate the platform plugin" << std::endl;
return 1;
}
a.start();
KWin::SessionSaveDoneHelper helper;
Q_UNUSED(helper); // The sessionsavedonehelper opens a side channel to the smserver,
// listens for events and talks to it, so it needs to be created.
return a.exec();
}
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