most of the implementation for the config handler done

lib/launcher/python/cfghandler.py

@@ -0,0 +1,125 @@
+import json, os, errno
+
+# self-explanatory
+default_config = {}
+
+# This will contain the current configuration after loading the file and
+# combining it with the default configuration. All changes will be done here
+config = None
+
+# The file to work with
+config_file_path = None
+
+################################################################################
+# file interaction
+################################################################################
+
+# set the config file to use
+def set_file_path(file_path):
+    global config_file_path
+    # error handling
+    if os.path.exists(file_path):
+        if os.path.isdir(file_path):
+            raise IOError(errno.EISDIR, "Is a directory", file_path)
+        if os.access(file_path, os.R_OK) and os.access(file_path, os.W_OK):
+            pass
+        else:
+            raise IOError(errno.EACCES, "Read AND write permissions required", file_path)
+    else:
+        config_file = open(file_path, "w")
+        config_file.write("{}")
+        config_file.close()
+    # actually setting the file path
+    config_file_path = file_path
+
+# loads the json file at file_path and updates the default configuration with it
+# overwrites any existing configuration adjustments
+# TODO: handle None as file name (raise an exception)
+def load():
+    global config_file_path
+    global config
+    global default_config
+    # read the config file
+    config_file = open(config_file_path,"r")
+    config_string = config_file.read()
+    config_file.close()
+    # combine with default config
+    config = default_config.copy()
+    config.update(json.loads(config_string))
+
+
+# stores the current configuration to the file at file_path
+# TODO: handle None (raise an exception)
+def store():
+    global config
+    global config_file_path
+    if not config is None:
+        config_file = open(config_file_path, "w")
+        config_file.write(json.dumps(config))
+        config_file.close()
+
+################################################################################
+# default config / config setup
+# These functions should be used BEFORE loading the config file
+################################################################################
+
+#defines a new option group in the default config
+# TODO: handle existing groups (raise an exception)
+def define_group(group):
+    global default_config
+    default_config.update({group : {}})
+
+# defines a new option in the default config
+# TODO: handle existing options (raise an exception)
+def define_option(group, name, default_value):
+    global default_config
+    default_config[group].update({name : default_value})
+
+# self-explanatory
+def clear_definitions():
+    global default_config
+    default_config = {}
+
+################################################################################
+# adjust an existing configuration for new needs
+################################################################################
+
+# remove the given option from the configuration and return the value to allow
+# for conversion if desired
+# TODO: implement
+def remove_option(group, name):
+    pass
+
+# move the value of an option to another place
+# TODO: implement
+def rename_option(old_group, old_name, new_group, new_name):
+    pass
+
+# remove an entire group from the configuration, never to be seen again
+# TODO: implement
+def remove_group(group):
+    pass
+
+# self-explanatory
+# TODO: implement
+def rename_group(old_group, new_group):
+    pass
+
+################################################################################
+# config interaction
+################################################################################
+
+# get the value of the given option
+def fetch(group, name):
+    global config
+    if config is None:
+        load()
+    return config[group][name]
+
+# set the value of a config option
+def set(group, name, value):
+    global config
+    if config is None:
+        load()
+    config[group][name] = value
+