Revive pylint support, and a first batch for fixes for problems found

.github/workflows/main.yml

@@ -0,0 +1,33 @@
+name: Unit tests
+
+on: [push, pull_request]
+
+jobs:
+  test_py2:
+    runs-on: ubuntu-20.04
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - name: Set up Python 2.7
+        uses: actions/setup-python@v2
+        with:
+          python-version: '2.7'
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install pylint diff_cover
+
+      - name: Pylint
+        run: |
+          pylint --version
+          pylint --exit-zero xcp/ tests/ setup.py
+          pylint --exit-zero --msg-template="{path}:{line}: [{msg_id}({symbol}), {obj}] {msg}" xcp/ tests/ setup.py > pylint.txt
+          diff-quality --violations=pylint --html-report pylint-diff.html pylint.txt
+
+      - uses: actions/upload-artifact@v3
+        with:
+          name: Pylint diff
+          path: pylint-diff.html

.gitignore

@@ -3,9 +3,3 @@
 
 # Emacs backup files
 *~
-
-# 'xcp' symlink for test harness
-/tests/xcp
-
-# 'xcp' symlink for pylint
-/xcp

run-pylint.sh

@@ -1,9 +1,7 @@
 #!/bin/bash
 
-test -r xcp || ln -sf . xcp
-
-if [[ -z $1 ]]; then
-    pylint --rcfile=pylint.rc *.py net
+if [ $# = 0 ]; then
+    pylint *.py xcp
 else
-    pylint --rcfile=pylint.rc $1
+    pylint "$@"
 fi

xcp/accessor.py

@@ -115,7 +115,7 @@ def openAddress(self, addr):
             return False
         except Exception as e:
             self.lastError = 500
-            return false
+            return False
         return file
 
 class MountingAccessor(FilesystemAccessor):

xcp/cpiofile.py

@@ -519,6 +519,10 @@ def seek(self, pos):
             self.init()
         self.read(pos - self.pos)
 
+    def init(self):
+        # implemented by subclasses
+        raise NotImplementedError()
+
     def tell(self):
         return self.pos
 
@@ -1154,7 +1158,7 @@ def xzopen(cls, name, mode="r", fileobj=None, compresslevel=6):
         if fileobj is not None:
             fileobj = _XZProxy(fileobj, mode)
         else:
-            fileobj = lzma.LZMAFile(name, mode, options={'level': compresslevel, dict_size: 20 })
+            fileobj = lzma.LZMAFile(name, mode, options={'level': compresslevel, 'dict_size': 20 })
 
         try:
             t = cls.cpioopen(name, mode, fileobj)