From be700472331354c454fa2792eec30c1b5ade9939 Mon Sep 17 00:00:00 2001
From: Ivan Kravets <me@ikravets.com>
Date: Mon, 25 May 2015 23:26:35 +0300
Subject: [PATCH] Improve running project from other directory (not CWD)

---
 platformio/commands/run.py         |  8 ++------
 platformio/ide/projectgenerator.py | 18 +++++++++---------
 platformio/util.py                 | 12 ++++++++++++
 3 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/platformio/commands/run.py b/platformio/commands/run.py
index b61544ba..5b27d1c6 100644
--- a/platformio/commands/run.py
+++ b/platformio/commands/run.py
@@ -2,7 +2,7 @@
 # See LICENSE for details.
 
 from datetime import datetime
-from os import chdir, getcwd
+from os import getcwd
 from os.path import getmtime, isdir, join
 from shutil import rmtree
 from time import time
@@ -28,9 +28,7 @@ from platformio.platforms.base import PlatformFactory
 @click.pass_context
 def cli(ctx, environment, target, upload_port,  # pylint: disable=R0913,R0914
         project_dir, verbose):
-    initial_cwd = getcwd()
-    chdir(project_dir)
-    try:
+    with util.cd(project_dir):
         config = util.get_project_config()
 
         if not config.sections():
@@ -74,8 +72,6 @@ def cli(ctx, environment, target, upload_port,  # pylint: disable=R0913,R0914
 
         if not all(results):
             raise exception.ReturnErrorCode()
-    finally:
-        chdir(initial_cwd)
 
 
 class EnvironmentProcessor(object):
diff --git a/platformio/ide/projectgenerator.py b/platformio/ide/projectgenerator.py
index fda18e9e..ef3d2c51 100644
--- a/platformio/ide/projectgenerator.py
+++ b/platformio/ide/projectgenerator.py
@@ -26,16 +26,16 @@ class ProjectGenerator(object):
         return [d for d in listdir(tpls_dir)
                 if isdir(join(tpls_dir, d))]
 
-    @staticmethod
-    def get_project_env():
+    def get_project_env(self):
         data = {}
-        config = util.get_project_config()
-        for section in config.sections():
-            if not section.startswith("env:"):
-                continue
-            data['env_name'] = section[4:]
-            for k, v in config.items(section):
-                data[k] = v
+        with util.cd(self.project_dir):
+            config = util.get_project_config()
+            for section in config.sections():
+                if not section.startswith("env:"):
+                    continue
+                data['env_name'] = section[4:]
+                for k, v in config.items(section):
+                    data[k] = v
         return data
 
     @util.memoized
diff --git a/platformio/util.py b/platformio/util.py
index 6477df7e..a5d36c66 100644
--- a/platformio/util.py
+++ b/platformio/util.py
@@ -55,6 +55,18 @@ class AsyncPipe(Thread):
         self.join()
 
 
+class cd:
+    def __init__(self, new_path):
+        self.new_path = new_path
+        self.prev_path = os.getcwd()
+
+    def __enter__(self):
+        os.chdir(self.new_path)
+
+    def __exit__(self, etype, value, traceback):
+        os.chdir(self.prev_path)
+
+
 class memoized(object):
     '''
     Decorator. Caches a function's return value each time it is called.