Fix for issue #89(Improve savestate error handling)

command_callbacks.py

@@ -1743,10 +1743,14 @@ def savestate_filename(input_dict, environment_dict):
      input_dict = input_dict[command_key]['children']
      command_key = input_dict.keys()[0]
 
-
+  if not environment_dict['currentkeyname']:
+    raise seash_exceptions.UserError("Specify the key name by first typing 'as [username]'.")
+
   # expand ~
   fileandpath = os.path.expanduser(command_key) 
-
+
+  if not os.access(fileandpath, os.W_OK):
+    raise seash_exceptions.UserError("Permission denied: " + fileandpath)
   try:
     seash_helper.savestate(fileandpath, environment_dict['handleinfo'], 
                            environment_dict['host'], environment_dict['port'], 

tests/ut_seash_savestate_nicermessageone.py

@@ -0,0 +1,20 @@
+"""
+This unit test is to test error messages when using savestate before 
+having loaded at least a pubkey, and work as that identity.
+"""
+
+import seash
+import sys
+import os
+import seash_exceptions
+
+#pragma out Specify the key name by first typing 'as [username]'.
+
+command_list = [ 
+  'savestate NO_KEYS_LOADED',
+]
+
+try:
+  seash.command_loop(command_list)
+except seash_exceptions.UserError, e:
+  print str(e)

tests/ut_seash_savestate_nicermessagetwo.py

@@ -0,0 +1,27 @@
+"""
+This unit test is to test error messages when using savestate to 
+a write-protected file.   
+"""
+
+import seash
+import sys
+import os
+import seash_exceptions
+
+#pragma out Permission denied: write_protected_file
+
+open('write_protected_file', 'w+').close()
+os.chmod('write_protected_file', 0444) 
+
+command_list = [
+  'loadkeys guest0', 
+  'as guest0', 
+  'savestate write_protected_file',
+]
+
+try:
+  seash.command_loop(command_list)
+except seash_exceptions.UserError, e:
+  print str(e)
+
+os.remove('write_protected_file')