utils.py: run_command runs in an en_US environment by default

This requirement started in a fixed Gingerbase bug (kimchi-project#18) that
reported lscpu problems when running in a French environment.
The output was being translated to french and breaking the
parsing made by the backend.

This is such a powder keg for all the plug-ins that I believe
this patch is justified. Instead of forcing en_US language
by using subprocess.Popen and setting the env, this is how
run_command will behave now:

- A new optional attribute, env_vars, was added. As the name
suggests, it allows the setup of the environment variables
to run the command.

- If env_vars is not set, run_command will copy the current
environment variables and set the language to the default
(en_US) by setting LC_ALL='C' variable. As of now, this is
the case of all the existing run_command calls in the code
for all WoK plug-ins. No behavior change will happen.

- If env_vars is set, but the LC_ALL var isn't, run_command
will set it to 'C' and force the default language.

- If env_vars is set and LC_ALL is also set, run_command
will not touch it and will run with env_vars as is. This
allows the caller to set the language at will.

Signed-off-by: Daniel Henrique Barboza <[email protected]>

Author: danielhb

Diff for: src/wok/utils.py

@@ -1,7 +1,7 @@
 #
 # Project Wok
 #
-# Copyright IBM, Corp. 2013-2015
+# Copyright IBM, Corp. 2013-2016
 #
 # Code derived from Project Kimchi
 #
@@ -136,7 +136,8 @@ def import_module(module_name, class_name=''):
     return __import__(module_name, globals(), locals(), [class_name])
 
 
-def run_command(cmd, timeout=None, silent=False, tee=None):
+def run_command(cmd, timeout=None, silent=False, tee=None,
+                env_vars=None):
     """
     cmd is a sequence of command arguments.
     timeout is a float number in seconds.
@@ -184,9 +185,15 @@ def tee_log(msg=None, log_file=None):
     timer = None
     timeout_flag = [False]
 
+    if env_vars is None:
+        env_vars = os.environ.copy()
+        env_vars['LC_ALL'] = 'C'
+    elif env_vars.get('LC_ALL') is None:
+        env_vars['LC_ALL'] = 'C'
+
     try:
         proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
-                                stderr=subprocess.PIPE)
+                                stderr=subprocess.PIPE, env=env_vars)
         if timeout is not None:
             timer = Timer(timeout, kill_proc, [proc, timeout_flag])
             timer.setDaemon(True)