Merge pull request #1800 from phw/PICARD-1718-crash-handler

PICARD-1718: crash handler

picard/__init__.py

@@ -88,3 +88,50 @@ api_versions = [
 ]
 
 api_versions_tuple = [Version.from_string(v) for v in api_versions]
+
+
+def crash_handler():
+    """Implements minimal handling of an exception crashing the application.
+    This function tries to log the exception to a log file and display
+    a minimal crash dialog to the user.
+    This function is supposed to be called from inside an except blog.
+    """
+    # First try to get traceback information and write it to a log file
+    # with minimum chance to fail.
+    import sys
+    from tempfile import NamedTemporaryFile
+    import traceback
+    trace = traceback.format_exc()
+    logfile = None
+    try:
+        with NamedTemporaryFile(suffix='.log', prefix='picard-crash-', delete=False) as f:
+            f.write(trace.encode(errors="replace"))
+            logfile = f.name
+    except:  # noqa: E722,F722 # pylint: disable=bare-except
+        print("Failed writing log file {0}".format(logfile), file=sys.stderr)
+        logfile = None
+
+    # Display the crash information to the user as a dialog. This requires
+    # importing Qt5 and has some potential to fail if things are broken.
+    from PyQt5.QtCore import QCoreApplication, Qt, QUrl
+    from PyQt5.QtWidgets import QApplication, QMessageBox
+    app = QCoreApplication.instance()
+    if not app:
+        app = QApplication(sys.argv)
+    msgbox = QMessageBox()
+    msgbox.setIcon(QMessageBox.Critical)
+    msgbox.setWindowTitle("Picard terminated unexpectedly")
+    msgbox.setTextFormat(Qt.RichText)
+    msgbox.setText(
+        'An unexpected error has caused Picard to crash. '
+        'Please report this issue on the <a href="https://tickets.metabrainz.org/projects/PICARD">MusicBrainz bug tracker</a>.')
+    if logfile:
+        logfile_url = QUrl.fromLocalFile(logfile)
+        msgbox.setInformativeText(
+            'A logfile has been written to <a href="{0}">{1}</a>.'
+            .format(logfile_url.url(), logfile))
+    msgbox.setDetailedText(trace)
+    msgbox.setStandardButtons(QMessageBox.Close)
+    msgbox.setDefaultButton(QMessageBox.Close)
+    msgbox.exec_()
+    app.quit()

scripts/picard.in

@@ -1,3 +1,11 @@
 #!/usr/bin/env python3
-from picard.tagger import main
-main('%(localedir)s', %(autoupdate)s)
+
+try:
+    from picard.tagger import main
+    main('%(localedir)s', %(autoupdate)s)
+except SystemExit:
+    raise  # Just continue with a normal application exit
+except:  # noqa: E722,F722 # pylint: disable=bare-except
+    from picard import crash_handler
+    crash_handler()
+    raise

tagger.py.in

@@ -15,5 +15,12 @@ else:
 if sys.platform == 'win32':
     os.environ['PATH'] = basedir + ';' + os.environ['PATH']
 
-from picard.tagger import main
-main(os.path.join(basedir, 'locale'), %(autoupdate)s)
+try:
+    from picard.tagger import main
+    main(os.path.join(basedir, 'locale'), %(autoupdate)s)
+except SystemExit:
+    raise  # Just continue with a normal application exit
+except:  # noqa: E722,F722 # pylint: disable=bare-except
+    from picard import crash_handler
+    crash_handler()
+    raise