Catch installation errors and display them.

Fixes #193

dangerzone/gui/main_window.py

@@ -20,15 +20,15 @@
         from PySide6.QtWidgets import QTextEdit
     except ImportError:
         from PySide2 import QtCore, QtGui, QtSvg, QtWidgets
-        from PySide2.QtWidgets import QAction, QTextEdit
         from PySide2.QtCore import Qt
+        from PySide2.QtWidgets import QAction, QTextEdit
 
 from .. import errors
 from ..document import SAFE_EXTENSION, Document
 from ..isolation_provider.container import Container, NoContainerTechException
 from ..isolation_provider.dummy import Dummy
 from ..isolation_provider.qubes import Qubes, is_qubes_native_conversion
-from ..util import get_resource_path, get_subprocess_startupinfo, get_version
+from ..util import get_resource_path, get_subprocess_startupinfo, get_version, format_exception
 from .logic import Alert, CollapsibleBox, DangerzoneGui, UpdateDialog
 from .updater import UpdateReport
 
@@ -388,15 +388,24 @@ def closeEvent(self, e: QtGui.QCloseEvent) -> None:
 
 
 class InstallContainerThread(QtCore.QThread):
-    finished = QtCore.Signal()
+    finished = QtCore.Signal(str)
 
     def __init__(self, dangerzone: DangerzoneGui) -> None:
         super(InstallContainerThread, self).__init__()
         self.dangerzone = dangerzone
 
     def run(self) -> None:
-        self.dangerzone.isolation_provider.install()
-        self.finished.emit()
+        error = None
+        try:
+            installed = self.dangerzone.isolation_provider.install()
+        except Exception as e:
+            log.error("Container installation problem")
+            error = format_exception(e)
+        else:
+            if not installed:
+                error = "The image cannot be found. This can be caused by a faulty container image."
+        finally:
+            self.finished.emit(error)
 
 
 class WaitingWidget(QtWidgets.QWidget):
@@ -438,7 +447,6 @@ class WaitingWidgetContainer(WaitingWidget):
     #
     # Linux states
     # - "install_container"
-    finished = QtCore.Signal()
 
     def __init__(self, dangerzone: DangerzoneGui) -> None:
         super(WaitingWidgetContainer, self).__init__()
@@ -509,48 +517,64 @@ def check_state(self) -> None:
         # Update the state
         self.state_change(state, error)
 
+    def show_error(self, msg: str, details: Optional[str] = None) -> None:
+        self.label.setText(msg)
+        show_traceback = details is not None
+        if show_traceback:
+            self.traceback.set_content(details)
+        self.traceback.setVisible(show_traceback)
+        self.buttons.show()
+
+    def show_message(self, msg: str) -> None:
+        self.label.setText(msg)
+        self.traceback.setVisible(False)
+        self.buttons.hide()
+
+    def installation_finished(self, error:Optional[str] = None):
+        if error:
+            msg = (
+                "During installation of the dangerzone image, <br>"
+                "the following error occured:"
+            )
+            self.show_error(msg, error)
+        else:
+            self.finished.emit()
+
     def state_change(self, state: str, error: Optional[str] = None) -> None:
         if state == "not_installed":
             if platform.system() == "Linux":
-                self.label.setText(
+                self.show_error(
                     "<strong>Dangerzone requires Podman</strong><br><br>"
                     "Install it and retry."
                 )
             else:
-                self.label.setText(
+                self.show_error(
                     "<strong>Dangerzone requires Docker Desktop</strong><br><br>"
                     "<a href='https://www.docker.com/products/docker-desktop'>Download Docker Desktop</a>"
                     ", install it, and open it."
                 )
-            self.buttons.show()
+
         elif state == "not_running":
             if platform.system() == "Linux":
                 # "not_running" here means that the `podman image ls` command failed.
                 message = (
                     "<strong>Dangerzone requires Podman</strong><br><br>"
                     "Podman is installed but cannot run properly. See errors below"
                 )
-                if error:
-                    self.traceback.set_content(error)
-
-                self.label.setText(message)
-
             else:
-                self.label.setText(
+                message = (
                     "<strong>Dangerzone requires Docker Desktop</strong><br><br>"
                     "Docker is installed but isn't running.<br><br>"
                     "Open Docker and make sure it's running in the background."
                 )
-            self.buttons.show()
+            self.show_error(message, error)
         else:
-            self.label.setText(
+            self.show_message(
                 "Installing the Dangerzone container image.<br><br>"
                 "This might take a few minutes..."
             )
-            self.buttons.hide()
-            self.traceback.setVisible(False)
             self.install_container_t = InstallContainerThread(self.dangerzone)
-            self.install_container_t.finished.connect(self.finished)
+            self.install_container_t.finished.connect(self.installation_finished)
             self.install_container_t.start()
 
 

dangerzone/isolation_provider/container.py

@@ -160,7 +160,7 @@ def install() -> bool:
             startupinfo=get_subprocess_startupinfo(),
         )
 
-        chunk_size = 10240
+        chunk_size = 4 << 20
         compressed_container_path = get_resource_path("container.tar.gz")
         with gzip.open(compressed_container_path) as f:
             while True:
@@ -170,19 +170,20 @@ def install() -> bool:
                         p.stdin.write(chunk)
                 else:
                     break
-        p.communicate()
+        _, err = p.communicate()
+        if p.returncode < 0:
+            raise RuntimeError(f"Could not install container image: {err}")
 
-        if not Container.is_container_installed():
-            log.error("Failed to install the container image")
+        if not Container.is_container_installed(raise_on_error=True):
             return False
 
         log.info("Container image installed")
         return True
 
     @staticmethod
-    def is_container_installed() -> bool:
+    def is_container_installed(raise_on_error: bool = False) -> bool:
         """
-        See if the podman container is installed. Linux only.
+        See if the container is installed.
         """
         # Get the image id
         with open(get_resource_path("image-id.txt")) as f:
@@ -209,6 +210,11 @@ def is_container_installed() -> bool:
         elif found_image_id == "":
             pass
         else:
+            msg =  (f"{Container.CONTAINER_NAME} images found, but IDs do not match."
+                     f"Found: {found_image_id}, Expected: {','.join(expected_image_ids)}")
+            if raise_on_error:
+                raise RuntimeError(msg)
+            log.info(msg)
             log.info("Deleting old dangerzone container image")
 
             try:

dangerzone/util.py

@@ -4,6 +4,7 @@
 import sys
 import unicodedata
 from typing import Optional
+import traceback
 
 import appdirs
 
@@ -97,3 +98,14 @@ def is_safe(chr: str) -> bool:
         else:
             sanitized_str += "�"
     return sanitized_str
+
+
+def format_exception(e):
+    # The signature of traceback.format_exception has changed in python 3.10
+    if sys.version_info < (3, 10):
+        output = traceback.format_exception(*sys.exc_info())
+    else:
+        output = traceback.format_exception(e)
+
+    return "".join(output)
+