Move early init code to own file

qutebrowser/app.py

@@ -18,38 +18,15 @@
 """Initialization of qutebrowser and application-wide things."""
 
 ### Things we want to do before normal imports ###
+import qutebrowser.utils.earlyinit as earlyinit
+earlyinit.check_python_version()
+earlyinit.init_faulthandler()
+earlyinit.fix_harfbuzz()
+earlyinit.check_pyqt_core()
+earlyinit.check_pyqt_webkit()
 
-import sys
-
-# Print a nice traceback on segfault -- only available on Python 3.3+, but if
-# it's unavailable, it doesn't matter much.
-try:
-    import faulthandler  # pylint: disable=import-error
-except ImportError:
-    pass
-else:
-    if sys.__stdout__ is not None:
-        # When run with pythonw.exe, sys.__stdout__ can be None:
-        # https://docs.python.org/3/library/sys.html#sys.__stdout__
-        # If we'd enable faulthandler in that case, we just get a weird
-        # exception, so we don't enable faulthandler in that case.
-        #
-        # FIXME at the point we have our config/data dirs, we probably should
-        # re-enable faulthandler to write to a file. Then we can also display
-        # crashes to the user at the next start.
-        faulthandler.enable()
-
-# See https://bugreports.qt-project.org/browse/QTBUG-36099
-# We need to do this before importing PyQt
-import qutebrowser.utils.harfbuzz as harfbuzz
-harfbuzz.fix()
-
-# Check if everything we should be able to import is there
-import qutebrowser.utils.dependencies as dependencies
-dependencies.check()
-
-# Early imports done, normal imports following now.
 import os
+import sys
 import logging
 import subprocess
 import configparser

qutebrowser/utils/earlyinit.py

@@ -1,5 +1,3 @@
-# Copyright 2014 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
-#
 # This file is part of qutebrowser.
 #
 # qutebrowser is free software: you can redistribute it and/or modify
@@ -15,21 +13,66 @@
 # You should have received a copy of the GNU General Public License
 # along with qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
 
-"""Check if everything needed for qutebrowser is there.
+"""Things which need to be done really early (e.g. before importing Qt)."""
-
-In a separate file because this needs to be done early before any imports.
-"""
 
+import os
 import sys
 
 
-def check():
+def check_python_version():
-    """Check if all dependencies are met."""
+    """Check if correct python version is run."""
     if sys.hexversion < 0x03030000:
         print("Fatal error: At least Python 3.3 is required to run "
               "qutebrowser, but {} is installed!".format(
                   '.'.join(map(str, sys.version_info[:3]))))
         sys.exit(1)
+
+
+def init_faulthandler():
+    """Enable faulthandler module if available.
+
+    This print a nice traceback on segfauls. It's only available on Python
+    3.3+, but if it's unavailable, it doesn't matter much (we just ignore
+    that).
+    """
+
+    try:
+        import faulthandler  # pylint: disable=import-error
+    except ImportError:
+        return
+    if sys.__stdout__ is not None:
+        # When run with pythonw.exe, sys.__stdout__ can be None:
+        # https://docs.python.org/3/library/sys.html#sys.__stdout__
+        # If we'd enable faulthandler in that case, we just get a weird
+        # exception, so we don't enable faulthandler in that case.
+        #
+        # FIXME at the point we have our config/data dirs, we probably should
+        # re-enable faulthandler to write to a file. Then we can also display
+        # crashes to the user at the next start.
+        return
+    faulthandler.enable()
+    if hasattr(faulthandler, 'register'):
+        # If available, we also want a traceback on SIGUSR1.
+        from signal import SIGUSR1
+        faulthandler.register(SIGUSR1)
+
+
+def fix_harfbuzz():
+    """Fix harfbuzz issues.
+
+    This switches to an older (but more stable) harfbuzz font rendering engine
+    instead of using the system wide one.
+
+    This fixes crashes on various sites.
+    See https://bugreports.qt-project.org/browse/QTBUG-36099
+    """
+    if sys.platform.startswith('linux'):
+        # Switch to old but stable font rendering engine
+        os.environ['QT_HARFBUZZ'] = 'old'
+
+
+def check_pyqt_core():
+    """Check if PyQt core is installed."""
     import textwrap
     try:
         import PyQt5.QtCore  # pylint: disable=unused-variable
@@ -59,12 +102,17 @@ def check():
             print()
             traceback.print_exc()
         sys.exit(1)
+
+
+def check_pyqt_webkit():
+    """Check if PyQt WebKit is installed."""
     # At this point we can rely on QtCore being available, so we can display an
     # error dialog
     try:
         import PyQt5.QtWebKit
     except ImportError:
         from PyQt5.QtWidgets import QApplication, QMessageBox
+        import textwrap
         app = QApplication(sys.argv)
         msgbox = QMessageBox(QMessageBox.Critical, "qutebrowser: Fatal error!",
                              textwrap.dedent("""

qutebrowser/utils/harfbuzz.py

@@ -1,39 +0,0 @@
-# Copyright 2014 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
-#
-# This file is part of qutebrowser.
-#
-# qutebrowser 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 3 of the License, or
-# (at your option) any later version.
-#
-# qutebrowser 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 qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
-
-"""Fixer to set QT_HARFBUZZ variable.
-
-In its own file so it doesn't include any Qt stuff, because if it did, it
-wouldn't work.
-"""
-
-import os
-import sys
-
-
-def fix():
-    """Fix harfbuzz issues.
-
-    This switches to an older (but more stable) harfbuzz font rendering engine
-    instead of using the system wide one.
-
-    This fixes crashes on various sites.
-    See https://bugreports.qt-project.org/browse/QTBUG-36099
-    """
-    if sys.platform.startswith('linux'):
-        # Switch to old but stable font rendering engine
-        os.environ['QT_HARFBUZZ'] = 'old'