CrashHandler: Add "Attach and Debug" button.

This will launch a new instance of Qt Creator attaching to the crashed
instance.

The 'Restart' functionality is now represented as a check box since it
would be confusing to have one button that restarts the app and quits
the crash handler and another one that starts a debugger but keeps the
crash handler open (which is necessary, otherwise the crashed app will
quit).

Change-Id: Id88f418ff73ab7bc72b05753ce2b61bbef8f30cf
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>

src/tools/qtcreatorcrashhandler/backtracecollector.cpp

@@ -78,6 +78,16 @@ void BacktraceCollector::run(Q_PID pid)
     );
 }
 
+bool BacktraceCollector::isRunning() const
+{
+    return d->debugger.state() == QProcess::Running;
+}
+
+void BacktraceCollector::kill()
+{
+    d->debugger.kill();
+}
+
 void BacktraceCollector::onDebuggerFinished(int exitCode, QProcess::ExitStatus /*exitStatus*/)
 {
     if (d->errorOccurred) {

src/tools/qtcreatorcrashhandler/backtracecollector.h

@@ -43,6 +43,8 @@ public:
     ~BacktraceCollector();
 
     void run(Q_PID pid);
+    bool isRunning() const;
+    void kill();
 
 signals:
     void error(const QString &errorMessage);

src/tools/qtcreatorcrashhandler/crashhandler.cpp

@@ -33,13 +33,17 @@
 #include "backtracecollector.h"
 #include "utils.h"
 
+#include <utils/environment.h>
+
 #include <QApplication>
 #include <QDebug>
 #include <QDesktopServices>
+#include <QDir>
 #include <QFile>
 #include <QRegExp>
 #include <QTextStream>
 #include <QUrl>
+#include <QVector>
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -48,9 +52,11 @@
 #include <unistd.h>
 
 #include <sys/types.h>
+#include <sys/wait.h>
 
 static const char FileDistroInformation[] = "/etc/lsb-release";
 static const char FileKernelVersion[] = "/proc/version";
+static const char QtCreatorExecutable[] = "qtcreator";
 
 static QString collectLinuxDistributionInfo()
 {
@@ -62,33 +68,40 @@ static QString collectKernelVersionInfo()
     return QString::fromLatin1(fileContents(QLatin1String(FileKernelVersion)));
 }
 
+// Convience class for interacting with exec() family of functions.
+class CExecList : public QVector<char *>
+{
+public:
+    CExecList(const QStringList &list)
+    {
+        foreach (const QString &item, list)
+            append(qstrdup(item.toLatin1().data()));
+        append(0);
+    }
+
+    ~CExecList()
+    {
+        for (int i = 0; i < size(); ++i)
+            delete[] value(i);
+    }
+};
+
 class CrashHandlerPrivate
 {
 public:
     CrashHandlerPrivate(pid_t pid, CrashHandler *crashHandler)
-        : pid(pid), dialog(crashHandler), argv(0), envp(0) {}
+        : pid(pid),
+          creatorInPath(Utils::Environment::systemEnvironment().searchInPath(QtCreatorExecutable)),
+          dialog(crashHandler) {}
 
-    ~CrashHandlerPrivate()
-    {
-        if (argv) {
-            for (int i = 0; argv[i]; ++i)
-                delete[] argv[i];
-        }
-        if (envp) {
-            for (int i = 0; envp[i]; ++i)
-                delete[] envp[i];
-        }
-        free(argv);
-        free(envp);
-    }
+    const pid_t pid;
+    const QString creatorInPath; // Backup debugger.
 
-    pid_t pid;
     BacktraceCollector backtraceCollector;
     CrashHandlerDialog dialog;
 
-    // For restarting the process.
-    char **argv;
-    char **envp;
+    QStringList restartAppCommandLine;
+    QStringList restartAppEnvironment;
 };
 
 CrashHandler::CrashHandler(pid_t pid, QObject *parent)
@@ -100,10 +113,14 @@ CrashHandler::CrashHandler(pid_t pid, QObject *parent)
 
     d->dialog.appendDebugInfo(collectKernelVersionInfo());
     d->dialog.appendDebugInfo(collectLinuxDistributionInfo());
-    d->dialog.show();
 
-    if (!collectRestartAppData()) // If we can't restart the app properly, ...
-        d->dialog.disableRestartAppButton();
+    if (!collectRestartAppData()) {
+        d->dialog.disableRestartAppCheckBox();
+        if (d->creatorInPath.isEmpty())
+            d->dialog.disableDebugAppButton();
+    }
+
+    d->dialog.show();
 }
 
 CrashHandler::~CrashHandler()
@@ -130,8 +147,7 @@ void CrashHandler::onError(const QString &errorMessage)
 void CrashHandler::onBacktraceChunk(const QString &chunk)
 {
     d->dialog.appendDebugInfo(chunk);
-    QTextStream out(stdout);
-    out << chunk;
+    QTextStream(stdout) << chunk;
 }
 
 void CrashHandler::onBacktraceFinished(const QString &backtrace)
@@ -164,54 +180,40 @@ bool CrashHandler::collectRestartAppData()
 {
     const QString procDir = QString::fromLatin1("/proc/%1").arg(d->pid);
 
-    // Construct d->argv.
+    // Get command line.
     // man 5 proc: /proc/[pid]/cmdline
     // The command-line arguments appear in this file as a set of strings separated by
     // null bytes ('\0'), with a further null byte after the last string.
     const QString procCmdFileName = procDir + QLatin1String("/cmdline");
-    QList<QByteArray> cmdEntries = fileContents(procCmdFileName).split('\0');
-    if (cmdEntries.size() < 2) {
+    QList<QByteArray> commandLine = fileContents(procCmdFileName).split('\0');
+    if (commandLine.size() < 2) {
         qWarning("%s: Unexpected format in file '%s'.\n", Q_FUNC_INFO, qPrintable(procCmdFileName));
         return false;
     }
-    cmdEntries.removeLast();
-    char * const executable = qstrdup(qPrintable(cmdEntries.takeFirst()));
-    d->argv = (char **) malloc(sizeof(char*) * (cmdEntries.size() + 2));
-    if (d->argv == 0)
-        qFatal("%s: malloc() failed.\n", Q_FUNC_INFO);
-    d->argv[0] = executable;
-    int i;
-    for (i = 1; i <= cmdEntries.size(); ++i)
-        d->argv[i] = qstrdup(cmdEntries.at(i-1));
-    d->argv[i] = 0;
+    commandLine.removeLast();
+    foreach (const QByteArray &item, commandLine)
+        d->restartAppCommandLine.append(QString::fromLatin1(item));
 
-    // Construct d->envp.
+    // Get environment.
     // man 5 proc: /proc/[pid]/environ
-    // The entries are separated by null bytes ('\0'), and there may be a null  byte at the end.
+    // The entries are separated by null bytes ('\0'), and there may be a null byte at the end.
     const QString procEnvFileName = procDir + QLatin1String("/environ");
-    QList<QByteArray> envEntries = fileContents(procEnvFileName).split('\0');
-    if (envEntries.isEmpty()) {
+    QList<QByteArray> environment = fileContents(procEnvFileName).split('\0');
+    if (environment.isEmpty()) {
         qWarning("%s: Unexpected format in file '%s'.\n", Q_FUNC_INFO, qPrintable(procEnvFileName));
         return false;
     }
-    if (envEntries.last().isEmpty())
-        envEntries.removeLast();
-    d->envp = (char **) malloc(sizeof(char*) * (envEntries.size() + 1));
-    if (d->envp == 0)
-        qFatal("%s: malloc() failed.\n", Q_FUNC_INFO);
-    for (i = 0; i < envEntries.size(); ++i)
-        d->envp[i] = qstrdup(envEntries.at(i));
-    d->envp[i] = 0;
+    if (environment.last().isEmpty())
+        environment.removeLast();
+    foreach (const QByteArray &item, environment)
+        d->restartAppEnvironment.append(QString::fromLatin1(item));
 
     return true;
 }
 
-void CrashHandler::restartApplication()
+void CrashHandler::runCommand(QStringList commandLine, QStringList environment, WaitMode waitMode)
 {
     // TODO: If QTBUG-2284 is resolved, use QProcess::startDetached() here.
-    // Close the crash handler and start the process again with same environment and
-    // command line arguments.
-    //
     // We can't use QProcess::startDetached because of bug
     //
     //      QTBUG-2284
@@ -224,15 +226,19 @@ void CrashHandler::restartApplication()
     case -1: // error
         qFatal("%s: fork() failed.", Q_FUNC_INFO);
         break;
-    case 0: // child
-        qDebug("Restarting Qt Creator with\n");
-        for (int i = 0; d->argv[i]; ++i)
-            qDebug("   %s", d->argv[i]);
-        qDebug("\nand environment\n");
-        for (int i = 0; d->envp[i]; ++i)
-            qDebug("   %s", d->envp[i]);
+    case 0: { // child
+        CExecList argv(commandLine);
+        CExecList envp(environment);
+        qDebug("Running\n");
+        for (int i = 0; argv[i]; ++i)
+            qDebug("   %s", argv[i]);
+        if (!environment.isEmpty()) {
+            qDebug("\nwith environment:\n");
+            for (int i = 0; envp[i]; ++i)
+                qDebug("   %s", envp[i]);
+        }
 
-        // The standards pipes must be open, otherwise the restarted Qt Creator will
+        // The standards pipes must be open, otherwise the application will
         // receive a SIGPIPE as soon as these are used.
         if (freopen("/dev/null", "r", stdin) == 0)
             qFatal("%s: freopen() failed for stdin: %s.\n", Q_FUNC_INFO, strerror(errno));
@@ -241,10 +247,68 @@ void CrashHandler::restartApplication()
         if (freopen("/dev/null", "w", stderr) == 0)
             qFatal("%s: freopen() failed for stderr: %s.\n.", Q_FUNC_INFO, strerror(errno));
 
-        execve(d->argv[0], d->argv, d->envp);
+        if (environment.isEmpty())
+            execv(argv[0], argv.data());
+        else
+            execve(argv[0], argv.data(), envp.data());
         _exit(EXIT_FAILURE);
-    default: // parent
-        qApp->quit();
+    } default: // parent
+        if (waitMode == WaitForExit) {
+            while (true) {
+                int status;
+                if (waitpid(pid, &status, 0) == -1) {
+                    if (errno == EINTR) // Signal handler of QProcess for SIGCHLD was triggered.
+                        continue;
+                    perror("waitpid() failed unexpectedly");
+                }
+                if (WIFEXITED(status)) {
+                    qDebug("Child exited with exit code %d.", WEXITSTATUS(status));
+                    break;
+                } else if (WIFSIGNALED(status)) {
+                    qDebug("Child terminated by signal %d.", WTERMSIG(status));
+                    break;
+                }
+            }
+        }
         break;
     }
 }
+
+void CrashHandler::restartApplication()
+{
+    runCommand(d->restartAppCommandLine, d->restartAppEnvironment, DontWaitForExit);
+}
+
+void CrashHandler::debugApplication()
+{
+    // User requested to debug the app while our debugger is running.
+    if (d->backtraceCollector.isRunning()) {
+        if (!d->dialog.runDebuggerWhileBacktraceNotFinished())
+            return;
+        if (d->backtraceCollector.isRunning()) {
+            d->backtraceCollector.disconnect();
+            d->backtraceCollector.kill();
+            d->dialog.setToFinalState();
+            d->dialog.appendDebugInfo(tr("\n\nCollecting backtrace aborted by user."));
+            QCoreApplication::processEvents(); // Show the last appended output immediately.
+        }
+    }
+
+    // Prepare command.
+    QString executable = d->creatorInPath;
+    if (!d->restartAppCommandLine.isEmpty())
+        executable = d->restartAppCommandLine.at(0);
+    const QStringList commandLine = QStringList()
+            << executable
+            << QLatin1String("-debug")
+            << QString::number(d->pid);
+
+    QStringList environment;
+    if (!d->restartAppEnvironment.isEmpty())
+        environment = d->restartAppEnvironment;
+
+    // The UI is blocked/frozen anyway, so hide the dialog while debugging.
+    d->dialog.hide();
+    runCommand(commandLine, environment, WaitForExit);
+    d->dialog.show();
+}

src/tools/qtcreatorcrashhandler/crashhandler.h

@@ -55,10 +55,14 @@ public slots:
 
     void openBugTracker();
     void restartApplication();
+    void debugApplication();
 
 private:
     bool collectRestartAppData();
 
+    enum WaitMode { WaitForExit, DontWaitForExit };
+    static void runCommand(QStringList commandLine, QStringList environment, WaitMode waitMode);
+
     CrashHandlerPrivate *d;
 };
 

src/tools/qtcreatorcrashhandler/crashhandlerdialog.cpp

@@ -34,9 +34,15 @@
 #include "utils.h"
 
 #include <app/app_version.h>
+#include <utils/checkablemessagebox.h>
 
 #include <QClipboard>
 #include <QIcon>
+#include <QSettings>
+
+static const char SettingsApplication[] = "QtCreator";
+static const char SettingsKeySkipWarningAbortingBacktrace[]
+    = "CrashHandler/SkipWarningAbortingBacktrace";
 
 CrashHandlerDialog::CrashHandlerDialog(CrashHandler *handler, QWidget *parent) :
     QDialog(parent),
@@ -59,8 +65,8 @@ CrashHandlerDialog::CrashHandlerDialog(CrashHandler *handler, QWidget *parent) :
 
     connect(m_ui->copyToClipBoardButton, SIGNAL(clicked()), this, SLOT(copyToClipboardClicked()));
     connect(m_ui->reportBugButton, SIGNAL(clicked()), m_crashHandler, SLOT(openBugTracker()));
-    connect(m_ui->restartAppButton, SIGNAL(clicked()), m_crashHandler, SLOT(restartApplication()));
-    connect(m_ui->closeButton, SIGNAL(clicked()), qApp, SLOT(quit()));
+    connect(m_ui->debugAppButton, SIGNAL(clicked()), m_crashHandler, SLOT(debugApplication()));
+    connect(m_ui->closeButton, SIGNAL(clicked()), this, SLOT(close()));
 
     setApplicationInfo();
 }
@@ -70,6 +76,34 @@ CrashHandlerDialog::~CrashHandlerDialog()
     delete m_ui;
 }
 
+bool CrashHandlerDialog::runDebuggerWhileBacktraceNotFinished()
+{
+    // Check settings.
+    QSettings settings(QSettings::IniFormat, QSettings::UserScope,
+        QLatin1String(Core::Constants::IDE_SETTINGSVARIANT_STR),
+        QLatin1String(SettingsApplication));
+    if (settings.value(QLatin1String(SettingsKeySkipWarningAbortingBacktrace), false).toBool())
+        return true;
+
+    // Ask user.
+    const QString title = tr("Run Debugger And Abort Collecting Backtrace?");
+    const QString message = tr(
+        "<html><head/><body>"
+          "<p><b>Run the debugger and abort collecting backtrace?</b></p>"
+          "<p>You have requested to run the debugger while collecting the backtrace was not "
+          "finished.</p>"
+        "</body></html>");
+    const QString checkBoxText = tr("Do not &ask again.");
+    bool checkBoxSetting = false;
+    const QDialogButtonBox::StandardButton button = Utils::CheckableMessageBox::question(this,
+        title, message, checkBoxText, &checkBoxSetting,
+        QDialogButtonBox::Yes|QDialogButtonBox::No, QDialogButtonBox::No);
+    if (checkBoxSetting)
+        settings.setValue(QLatin1String(SettingsKeySkipWarningAbortingBacktrace), checkBoxSetting);
+
+    return button == QDialogButtonBox::Yes;
+}
+
 void CrashHandlerDialog::setToFinalState()
 {
     m_ui->progressBar->hide();
@@ -77,9 +111,14 @@ void CrashHandlerDialog::setToFinalState()
     m_ui->reportBugButton->setEnabled(true);
 }
 
-void CrashHandlerDialog::disableRestartAppButton()
+void CrashHandlerDialog::disableRestartAppCheckBox()
 {
-    m_ui->restartAppButton->setDisabled(true);
+    m_ui->restartAppCheckBox->setDisabled(true);
+}
+
+void CrashHandlerDialog::disableDebugAppButton()
+{
+    m_ui->debugAppButton->setDisabled(true);
 }
 
 void CrashHandlerDialog::setApplicationInfo()
@@ -130,3 +169,10 @@ void CrashHandlerDialog::copyToClipboardClicked()
 {
     QApplication::clipboard()->setText(m_ui->debugInfoEdit->toPlainText());
 }
+
+void CrashHandlerDialog::close()
+{
+    if (m_ui->restartAppCheckBox->isEnabled() && m_ui->restartAppCheckBox->isChecked())
+        m_crashHandler->restartApplication();
+    qApp->quit();
+}

src/tools/qtcreatorcrashhandler/crashhandlerdialog.h

@@ -50,14 +50,17 @@ public:
     ~CrashHandlerDialog();
 
 public:
-    void disableRestartAppButton();
     void setApplicationInfo();
-    void setToFinalState();
     void appendDebugInfo(const QString &chunk);
     void selectLineWithContents(const QString &text);
+    void setToFinalState();
+    void disableRestartAppCheckBox();
+    void disableDebugAppButton();
+    bool runDebuggerWhileBacktraceNotFinished();
 
 private slots:
     void copyToClipboardClicked();
+    void close();
 
 private:
     CrashHandler *m_crashHandler;

src/tools/qtcreatorcrashhandler/crashhandlerdialog.ui

@@ -12,7 +12,7 @@
   </property>
   <property name="minimumSize">
    <size>
-    <width>400</width>
+    <width>500</width>
     <height>300</height>
    </size>
   </property>
@@ -64,6 +64,16 @@
    <item>
     <widget class="QTextEdit" name="debugInfoEdit"/>
    </item>
+   <item alignment="Qt::AlignRight">
+    <widget class="QCheckBox" name="restartAppCheckBox">
+     <property name="text">
+      <string>&amp;Restart Qt Creator on close</string>
+     </property>
+     <property name="checked">
+      <bool>true</bool>
+     </property>
+    </widget>
+   </item>
    <item>
     <layout class="QHBoxLayout" name="horizontalLayout">
      <item>
@@ -71,6 +81,9 @@
        <property name="enabled">
         <bool>false</bool>
        </property>
+       <property name="toolTip">
+        <string>Copy the whole contents to clipboard.</string>
+       </property>
        <property name="text">
         <string>C&amp;opy to clipboard</string>
        </property>
@@ -81,6 +94,9 @@
        <property name="enabled">
         <bool>false</bool>
        </property>
+       <property name="toolTip">
+        <string>Open the bug tracker web site.</string>
+       </property>
        <property name="text">
         <string>Report this &amp;bug</string>
        </property>
@@ -100,14 +116,23 @@
       </spacer>
      </item>
      <item>
-      <widget class="QPushButton" name="restartAppButton">
+      <widget class="QPushButton" name="debugAppButton">
+       <property name="enabled">
+        <bool>true</bool>
+       </property>
+       <property name="toolTip">
+        <string>Debug the application with a new instance of Qt Creator. During debugging the crash handler will be hidden.</string>
+       </property>
        <property name="text">
-        <string>&amp;Restart Qt Creator</string>
+        <string>Attach and &amp;Debug</string>
        </property>
       </widget>
      </item>
      <item>
       <widget class="QPushButton" name="closeButton">
+       <property name="toolTip">
+        <string>Quit the handler and the crashed application.</string>
+       </property>
        <property name="text">
         <string>&amp;Close</string>
        </property>

src/tools/qtcreatorcrashhandler/qtcreatorcrashhandler.pro

@@ -11,13 +11,18 @@ SOURCES += \
     backtracecollector.cpp \
     crashhandlerdialog.cpp \
     crashhandler.cpp \
-    utils.cpp
+    utils.cpp \
+    ../../libs/utils/checkablemessagebox.cpp \
+    ../../libs/utils/environment.cpp
+
 
 HEADERS += \
     backtracecollector.h \
     crashhandlerdialog.h \
     crashhandler.h \
-    utils.h
+    utils.h \
+    ../../libs/utils/checkablemessagebox.h \
+    ../../libs/utils/environment.h
 
 FORMS += \
     crashhandlerdialog.ui

src/tools/qtcreatorcrashhandler/qtcreatorcrashhandler.qbs

@@ -6,7 +6,8 @@ QtcTool {
     condition: qbs.targetOS == "linux" && qbs.buildVariant == "debug"
 
     cpp.includePaths: [
-        buildDirectory
+        buildDirectory,
+        "../../libs"
     ]
 
     Depends { name: "cpp" }
@@ -14,6 +15,10 @@ QtcTool {
     Depends { name: "app_version_header" }
 
     files: [
+        "../../libs/utils/checkablemessagebox.cpp",
+        "../../libs/utils/checkablemessagebox.h",
+        "../../libs/utils/environment.cpp",
+        "../../libs/utils/environment.h",
         "backtracecollector.cpp",
         "backtracecollector.h",
         "crashhandler.cpp",
@@ -23,6 +28,6 @@ QtcTool {
         "crashhandlerdialog.ui",
         "main.cpp",
         "utils.cpp",
-        "utils.h",
+        "utils.h"
     ]
 }