Merge pull request #99 from jbenden/resource-warnings

Fix subprocess.Popen handle leakage

spline/components/bash.py

@@ -16,6 +16,7 @@
 # WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 # pylint: disable=too-many-instance-attributes
+import contextlib
 import sys
 import os
 import shlex
@@ -28,6 +29,18 @@
 from spline.tools.event import Event
 
 
+@contextlib.contextmanager
+def managed_process(process):
+    """Wrapper for subprocess.Popen to work across various Python versions, when using the with syntax."""
+    try:
+        yield process
+    finally:
+        for stream in [process.stdout, process.stdin, process.stderr]:
+            if stream:
+                stream.close()
+        process.wait()
+
+
 class Bash(object):
     """Wrapper for Bash execution."""
 
@@ -134,23 +147,24 @@ def render_bash_options(self):
     def process_script(self, filename):
         """Running the Bash code."""
         try:
-            process = subprocess.Popen(shlex.split("bash %s" % filename),
-                                       stdout=self.stdout, stderr=self.stderr,
-                                       shell=self.shell, env=self.env)  # nosec
-            for line in iter(process.stdout.readline, ' '):
-                if not line:
-                    break
-                yield line[0:-1].decode('utf-8')
-            process.wait()
-            self.exit_code = process.returncode
-            self.success = (process.returncode == 0)
-            if not self.config.internal:
-                if process.returncode == 0:
-                    self.logger.info("Exit code has been %d", process.returncode)
-                else:
-                    self.logger.error("Exit code has been %d", process.returncode)
+            with managed_process(subprocess.Popen(shlex.split("bash %s" % filename),
+                                                  stdout=self.stdout, stderr=self.stderr,
+                                                  shell=self.shell, env=self.env)) as process:  # nosec
+                for line in iter(process.stdout.readline, ' '):
+                    if not line:
+                        break
+                    yield line[0:-1].decode('utf-8')
+                process.wait()
+                self.exit_code = process.returncode
+                self.success = (process.returncode == 0)
+                if not self.config.internal:
+                    if process.returncode == 0:
+                        self.logger.info("Exit code has been %d", process.returncode)
+                    else:
+                        self.logger.error("Exit code has been %d", process.returncode)
         except OSError as exception:
             self.exit_code = 1
+            self.success = False
             yield str(exception)
 
     def process_file(self, filename):