Fix update dialog crashing the app when the WebView backend is unusable

On Linux (wxGTK), wx.html2.WebView is backed by WebKitGTK. In the AppImage the bundled Ubuntu build of WebKitGTK fails to spawn its helper processes on other distributions, which aborts the whole application a few seconds after startup (issue #2740). On distributions without webkit2gtk-4.0, even importing wx.html2 fails, which breaks startup from source as well.

Never use the WebView on wxGTK and fall back to a plain text release notes widget there. On other platforms guard the WebView creation and fall back to plain text when no backend is available. Also guard ShowUpdateBox so a dialog failure can no longer take down startup, default empty release notes bodies to an empty string and put the release tag in the dialog title instead of a literal '{}'.

Behavior on Windows and macOS is unchanged.

Author: tadeasf

gui/mainFrame.py

@@ -242,8 +242,16 @@ def getCommandForFit(self, fitID) -> wx.CommandProcessor:
         return Fit.getCommandProcessor(fitID)
 
     def ShowUpdateBox(self, release, version):
-        with UpdateDialog(self, release, version) as dlg:
-            dlg.ShowModal()
+        # This runs right after startup, so any failure here must not be able
+        # to take the whole application down with it
+        try:
+            with UpdateDialog(self, release, version) as dlg:
+                dlg.ShowModal()
+        except (KeyboardInterrupt, SystemExit):
+            raise
+        except Exception as e:
+            pyfalog.error("Caught exception while showing the update notification dialog")
+            pyfalog.error(e)
 
     def LoadPreviousOpenFits(self):
         sFit = Fit.getInstance()

gui/updateDialog.py

@@ -21,12 +21,14 @@
 import wx
 # noinspection PyPackageRequirements
 import dateutil.parser
+from logbook import Logger
 from service.settings import UpdateSettings as svc_UpdateSettings
-import wx.html2
 import webbrowser
 import re
 import markdown2
 
+pyfalog = Logger(__name__)
+
 _t = wx.GetTranslation
 
 # HTML template. We link to a bootstrap cdn for quick and easy css, and include some additional teaks.
@@ -51,8 +53,8 @@ class UpdateDialog(wx.Dialog):
 
     def __init__(self, parent, release, version):
         super().__init__(
-            parent, id=wx.ID_ANY, title="pyfa {}" + _t("Update Available"), pos=wx.DefaultPosition,
-            size=wx.Size(550, 450), style=wx.DEFAULT_DIALOG_STYLE)
+            parent, id=wx.ID_ANY, title="pyfa {} - {}".format(release['tag_name'], _t("Update Available")),
+            pos=wx.DefaultPosition, size=wx.Size(550, 450), style=wx.DEFAULT_DIALOG_STYLE)
 
         self.UpdateSettings = svc_UpdateSettings.getInstance()
         self.releaseInfo = release
@@ -61,42 +63,22 @@ def __init__(self, parent, release, version):
         mainSizer = wx.BoxSizer(wx.VERTICAL)
 
         releaseDate = dateutil.parser.parse(self.releaseInfo['published_at'])
+        releaseNotes = self.releaseInfo.get('body') or ''
         notesSizer = wx.BoxSizer(wx.HORIZONTAL)
-        self.browser = wx.html2.WebView.New(self)
-        self.browser.Bind(wx.html2.EVT_WEBVIEW_NEWWINDOW, self.OnNewWindow)
-
-        link_patterns = [
-            (re.compile(r"#(\d+)", re.I), r"https://github.com/pyfa-org/Pyfa/issues/\1"),
-            (re.compile(r"@(\w+)", re.I), r"https://github.com/\1")
-        ]
-
-        markdowner = markdown2.Markdown(
-            extras=['cuddled-lists', 'fenced-code-blocks', 'target-blank-links', 'toc', 'link-patterns'],
-            link_patterns=link_patterns)
-
-        release_markup = markdowner.convert(self.releaseInfo['body'])
-
-        # run the text through markup again, this time with the hashing pattern. This is required due to bugs in markdown2:
-        # https://github.com/trentm/python-markdown2/issues/287
-        link_patterns = [
-            (re.compile("([0-9a-f]{6,40})", re.I), r"https://github.com/pyfa-org/Pyfa/commit/\1"),
-        ]
 
-        markdowner = markdown2.Markdown(
-            extras=['cuddled-lists', 'fenced-code-blocks', 'target-blank-links', 'toc', 'link-patterns'],
-            link_patterns=link_patterns)
-
-        # The space here is required, again, due to bug. Again, see https://github.com/trentm/python-markdown2/issues/287
-        release_markup = markdowner.convert(' ' + release_markup)
-
-        self.browser.SetPage(html_tmpl.format(
-            self.releaseInfo['tag_name'],
-            releaseDate.strftime('%B %d, %Y'),
-            "<p class='text-danger'><b>This is a pre-release, be prepared for unstable features</b></p>" if version.is_prerelease else "",
-            release_markup
-        ), "")
-
-        notesSizer.Add(self.browser, 1, wx.EXPAND | wx.LEFT | wx.RIGHT | wx.TOP, 5)
+        self.browser = self.createNotesBrowser(releaseDate, releaseNotes, version)
+        if self.browser is None:
+            header = "pyfa {} ({})".format(self.releaseInfo['tag_name'], releaseDate.strftime('%B %d, %Y'))
+            lines = [header, '=' * len(header), '']
+            if version.is_prerelease:
+                lines += [_t("This is a pre-release, be prepared for unstable features"), '']
+            lines.append(releaseNotes)
+            self.notesText = wx.TextCtrl(
+                self, wx.ID_ANY, '\n'.join(lines), wx.DefaultPosition, wx.DefaultSize,
+                wx.TE_MULTILINE | wx.TE_READONLY | wx.TE_WORDWRAP)
+            notesSizer.Add(self.notesText, 1, wx.EXPAND | wx.LEFT | wx.RIGHT | wx.TOP, 5)
+        else:
+            notesSizer.Add(self.browser, 1, wx.EXPAND | wx.LEFT | wx.RIGHT | wx.TOP, 5)
         mainSizer.Add(notesSizer, 1, wx.EXPAND, 5)
 
         self.supressCheckbox = wx.CheckBox(self, wx.ID_ANY, _t("Don't remind me again for this release"),
@@ -131,6 +113,86 @@ def __init__(self, parent, release, version):
 
         self.Centre(wx.BOTH)
 
+    @staticmethod
+    def webViewAvailable():
+        """
+        On wxGTK the wx.html2.WebView widget is backed by WebKitGTK, which cannot
+        be instantiated reliably on every Linux setup. In particular, the AppImage
+        bundles an Ubuntu build of WebKitGTK that fails to spawn its helper
+        processes on other distributions, aborting the whole application
+        (see https://github.com/pyfa-org/Pyfa/issues/2740). Never use the WebView
+        there; on other platforms make sure a backend can be loaded at all.
+        """
+        if 'wxGTK' in wx.PlatformInfo:
+            return False
+        try:
+            from wx import html2
+            return html2.WebView.IsBackendAvailable(html2.WebViewBackendDefault)
+        except (KeyboardInterrupt, SystemExit):
+            raise
+        except Exception as e:
+            pyfalog.warning("Could not check WebView backend availability: {}", e)
+            return False
+
+    def createNotesBrowser(self, releaseDate, releaseNotes, version):
+        """
+        Build the WebView displaying the release notes. Returns None when the
+        WebView cannot be used, so the caller can fall back to plain text.
+        """
+        if not self.webViewAvailable():
+            return None
+
+        from wx import html2
+        try:
+            browser = html2.WebView.New(self)
+        except (KeyboardInterrupt, SystemExit):
+            raise
+        except Exception as e:
+            pyfalog.warning("Could not create WebView for the update dialog: {}", e)
+            return None
+
+        browser.Bind(html2.EVT_WEBVIEW_NEWWINDOW, self.OnNewWindow)
+
+        link_patterns = [
+            (re.compile(r"#(\d+)", re.I), r"https://github.com/pyfa-org/Pyfa/issues/\1"),
+            (re.compile(r"@(\w+)", re.I), r"https://github.com/\1")
+        ]
+
+        markdowner = markdown2.Markdown(
+            extras=['cuddled-lists', 'fenced-code-blocks', 'target-blank-links', 'toc', 'link-patterns'],
+            link_patterns=link_patterns)
+
+        release_markup = markdowner.convert(releaseNotes)
+
+        # run the text through markup again, this time with the hashing pattern. This is required due to bugs in markdown2:
+        # https://github.com/trentm/python-markdown2/issues/287
+        link_patterns = [
+            (re.compile("([0-9a-f]{6,40})", re.I), r"https://github.com/pyfa-org/Pyfa/commit/\1"),
+        ]
+
+        markdowner = markdown2.Markdown(
+            extras=['cuddled-lists', 'fenced-code-blocks', 'target-blank-links', 'toc', 'link-patterns'],
+            link_patterns=link_patterns)
+
+        # The space here is required, again, due to bug. Again, see https://github.com/trentm/python-markdown2/issues/287
+        release_markup = markdowner.convert(' ' + release_markup)
+
+        try:
+            browser.SetPage(html_tmpl.format(
+                self.releaseInfo['tag_name'],
+                releaseDate.strftime('%B %d, %Y'),
+                "<p class='text-danger'><b>This is a pre-release, be prepared for unstable features</b></p>" if version.is_prerelease else "",
+                release_markup
+            ), "")
+        except (KeyboardInterrupt, SystemExit):
+            raise
+        except Exception as e:
+            pyfalog.warning("Could not load release notes into WebView: {}", e)
+            browser.Destroy()
+            return None
+
+        return browser
+
     def OnClose(self, e):
         self.Close()