Squish: Test handling of read only files

Change-Id: I459fdaed7338f5343b760da47e9652baf78986f0
Reviewed-by: Robert Loehning <robert.loehning@digia.com>

tests/system/shared/fs_utils.py

@@ -0,0 +1,33 @@
+import stat
+
+# this function modifies all (regular) files inside the given dirPath to have specified permissions
+# ATTENTION: it won't process the directory recursively
+def changeFilePermissions(dirPath, readPerm, writePerm, excludeFileNames=None):
+    permission = 0
+    if readPerm:
+        permission |= stat.S_IREAD
+    if writePerm:
+        permission |= stat.S_IWRITE
+    if excludeFileNames == None:
+        excludeFileNames = []
+    elif isinstance(excludeFileNames, (str, unicode)):
+        excludeFileNames = [excludeFileNames]
+    if not isinstance(excludeFileNames, (tuple, list)):
+        test.warning("File names to exclude must be of type str, unicode, list, tuple or None - "
+                     "ignoring parameter this time.")
+        excludeFileNames = []
+    if not os.path.isdir(dirPath):
+        test.warning("Could not find directory '%s'." % dirPath)
+        return False
+    filePaths = [os.path.join(dirPath, fileName) for fileName in os.listdir(dirPath)
+                 if fileName not in excludeFileNames]
+    for filePath in filter(os.path.isfile, filePaths):
+        os.chmod(filePath, permission)
+    return True
+
+def isWritable(pathToFile):
+    if os.path.exists(pathToFile):
+        return os.access(pathToFile, os.W_OK)
+    else:
+        test.warning("Path to check for writability does not exist.")
+        return False