Display error dialog when started after segfault

qutebrowser/app.py

@@ -31,6 +31,7 @@ import sys
 import types
 import logging
 import subprocess
+import faulthandler
 import configparser
 from bdb import BdbQuit
 from functools import partial
@@ -54,7 +55,7 @@ from qutebrowser.network.networkmanager import NetworkManager
 from qutebrowser.config.config import ConfigManager
 from qutebrowser.keyinput.modeman import ModeManager
 from qutebrowser.widgets.mainwindow import MainWindow
-from qutebrowser.widgets.crash import ExceptionCrashDialog
+from qutebrowser.widgets.crash import ExceptionCrashDialog, FatalCrashDialog
 from qutebrowser.keyinput.modeparsers import NormalKeyParser, HintKeyParser
 from qutebrowser.keyinput.keyparser import PassthroughKeyParser
 from qutebrowser.commands.managers import CommandManager, SearchManager
@@ -94,6 +95,8 @@ class QuteBrowser(QApplication):
         _shutting_down: True if we're currently shutting down.
         _quit_status: The current quitting status.
         _opened_urls: List of opened URLs.
+        _crashdlg: The crash dialog currently open.
+        _crashlogfile: A file handler to the fatal crash logfile.
     """
 
     # This also holds all our globals, so we're a bit over the top here.
@@ -110,6 +113,8 @@ class QuteBrowser(QApplication):
         self._opened_urls = []
         self._shutting_down = False
         self._keyparsers = None
+        self._crashdlg = None
+        self._crashlogfile = None
         self.messagebridge = None
         self.stateconfig = None
         self.modeman = None
@@ -123,6 +128,7 @@ class QuteBrowser(QApplication):
         self._init_misc()
         actute_warning()
         self._init_config()
+        self._handle_segfault()
         self._init_modes()
         websettings.init()
         proxy.init()
@@ -145,6 +151,9 @@ class QuteBrowser(QApplication):
         timer = QTimer.singleShot(0, self._process_init_args)
         self._timers.append(timer)
 
+        if self._crashdlg is not None:
+            self._crashdlg.raise_()
+
     def _parse_args(self):
         """Parse command line options.
 
@@ -238,6 +247,26 @@ class QuteBrowser(QApplication):
         self.setApplicationVersion(qutebrowser.__version__)
         self.messagebridge = MessageBridge()
 
+    def _handle_segfault(self):
+        """Handle a segfault from a previous run."""
+        logname = os.path.join(get_standard_dir(QStandardPaths.DataLocation),
+                               'crash.log')
+        # First check if an old logfile exists.
+        if os.path.exists(logname):
+            with open(logname, 'r') as f:
+                data = f.read()
+            # Just in case FatalCrashDialog crashes... -.-
+            os.remove(logname)
+            if data:
+                self._crashdlg = FatalCrashDialog(data)
+                self._crashdlg.show()
+        # Start a new logfile and redirect faulthandler to it
+        self._crashlogfile = open(logname, 'w')  # This also truncates.
+        faulthandler.enable(self._crashlogfile)
+        if hasattr(faulthandler, 'register') and hasattr(signal, 'SIGUSR1'):
+            # If available, we also want a traceback on SIGUSR1.
+            faulthandler.register(signal.SIGUSR1)  # pylint: disable=no-member
+
     def _init_cmds(self):
         """Initialisation of the qutebrowser commands.
 
@@ -427,8 +456,8 @@ class QuteBrowser(QApplication):
         except TypeError:
             logging.exception("Preventing shutdown failed.")
         QApplication.closeAllWindows()
-        dlg = ExceptionCrashDialog(pages, history, exc)
+        self._crashdlg = ExceptionCrashDialog(pages, history, exc)
-        ret = dlg.exec_()
+        ret = self._crashdlg.exec_()
         if ret == QDialog.Accepted:  # restore
             self.restart(shutdown=False, pages=pages)
         # We might risk a segfault here, but that's better than continuing to

qutebrowser/utils/earlyinit.py

@@ -39,9 +39,9 @@ def init_faulthandler():
         # If we'd enable faulthandler in that case, we just get a weird
         # exception, so we don't enable faulthandler if we have no stdout.
         #
-        # FIXME at the point we have our config/data dirs, we probably should
+        # Later when we have our data dir available we re-enable faulthandler
-        # re-enable faulthandler to write to a file. Then we can also display
+        # to write to a file so we can display a crash to the user at the next
-        # crashes to the user at the next start.
+        # start.
         return
     faulthandler.enable()
     if hasattr(faulthandler, 'register') and hasattr(signal, 'SIGUSR1'):

qutebrowser/widgets/crash.py

@@ -176,29 +176,64 @@ class ExceptionCrashDialog(_CrashDialog):
         self._btn_quit = QPushButton()
         self._btn_quit.setText("Quit")
         self._btn_quit.clicked.connect(self.reject)
+        self._hbox.addWidget(self._btn_quit)
         self._btn_pastebin = QPushButton()
         self._btn_pastebin.setText("Pastebin")
         self._btn_pastebin.clicked.connect(self.pastebin)
-        self._hbox.addWidget(self._btn_quit)
+        self._hbox.addWidget(self._btn_pastebin)
         if self._pages:
             self._btn_restore = QPushButton()
             self._btn_restore.setText("Restore tabs")
             self._btn_restore.clicked.connect(self.accept)
             self._btn_restore.setDefault(True)
             self._hbox.addWidget(self._btn_restore)
-        self._hbox.addWidget(self._btn_pastebin)
 
     def _gather_crash_info(self):
-        """Gather crash information to display.
-
-        Args:
-            pages: A list of the open pages (URLs as strings)
-            cmdhist: A list with the command history (as strings)
-            exc: An exception tuple (type, value, traceback)
-        """
         super()._gather_crash_info()
         self._crash_info += [
             ("Exception", ''.join(traceback.format_exception(*self._exc))),
             ("Open Pages", '\n'.join(self._pages)),
             ("Command history", '\n'.join(self._cmdhist)),
         ]
+
+
+class FatalCrashDialog(_CrashDialog):
+
+    """Dialog which gets shown when a fatal error occured.
+
+    Attributes:
+        _log: The log text to display.
+        _btn_ok: The OK button.
+        _btn_pastebin: The pastebin button.
+    """
+
+    def __init__(self, log):
+        self._log = log
+        self._btn_ok = None
+        self._btn_pastebin = None
+        super().__init__()
+
+    def _init_text(self):
+        super()._init_text()
+        text = ("qutebrowser was restarted after a fatal crash.<br/>"
+                "Please click on 'pastebin' or send the data below to "
+                "<a href='mailto:crash@qutebrowser.org'>"
+                "crash@qutebrowser.org</a>.<br/><br/>")
+        self._lbl.setText(text)
+
+    def _init_buttons(self):
+        super()._init_buttons()
+        self._btn_ok = QPushButton()
+        self._btn_ok.setText("OK")
+        self._btn_ok.clicked.connect(self.accept)
+        self._hbox.addWidget(self._btn_ok)
+        self._btn_pastebin = QPushButton()
+        self._btn_pastebin.setText("Pastebin")
+        self._btn_pastebin.clicked.connect(self.pastebin)
+        self._hbox.addWidget(self._btn_pastebin)
+
+    def _gather_crash_info(self):
+        super()._gather_crash_info()
+        self._crash_info += [
+            ("Fault log", self._log),
+        ]