Merge ~rodsmith/checkbox-support:fix-disk-support-stack-trace into checkbox-support:master

[Rod Smith]

Fix bug if device file does not exist in disk_support.py

The get_partition_data(file) function in disk_support.py could result in a stack trace if the specified file variable pointed to a non-existent file, as seems to happen on some system configurations (per bug #1889533). This MR fixes that problem, and also addresses some minor stylistic issues identified by kissiel in https://code.launchpad.net/~rodsmith/checkbox-support/+git/checkbox-support/+merge/385587.

[Maciej Kisielewski (kissiel)]

Great stuff. Thanks for the quick fix!

review: Approve

diff --git a/checkbox_support/disk_support.py b/checkbox_support/disk_support.py
index 2915b10..09d8525 100644
--- a/checkbox_support/disk_support.py
+++ b/checkbox_support/disk_support.py
@@ -1,7 +1,3 @@
-#!/usr/bin/env python3
-
-# Disk information/support features
-#
 # Copyright (C) 2020 Canonical Ltd.
 #
 # Authors:
@@ -25,14 +21,14 @@ Support functions related to disk devices for Checkbox.
 
 
 from subprocess import (
-    check_output,
-    PIPE,
-    STDOUT,
+    CalledProcessError,
+    check_output
 )
 import logging
 import os
 import shlex
 import stat
+import sys
 import uuid
 
 
@@ -50,9 +46,12 @@ def get_partition_data(file):
     # Get filesystem type....
     part_data['fs_type'] = ""
     command = "blkid /dev/{} -o export".format(file)
-    local_results = check_output(shlex.split(command)).split()
+    try:
+        local_results = check_output(shlex.split(command)).split()
+    except CalledProcessError:
+        local_results = []
     for result in local_results:
-        result_str = result.decode(encoding="utf-8", errors="ignore")
+        result_str = result.decode(sys.stdout.encoding, errors="ignore")
         if "TYPE" in result_str:
             part_data['fs_type'] = result_str.split("=")[1]
     return part_data