From b5ae0bdca36cd24637cba756663a78a38bc97cfd Mon Sep 17 00:00:00 2001
From: Dan Streetman <ddstreet@canonical.com>
Date: Mon, 11 Feb 2019 14:30:01 -0500
Subject: [PATCH] simplify subprocess usage

---
 submittodebian         | 19 ++++++++-----------
 ubuntu-iso             | 10 +++++-----
 ubuntutools/builder.py |  8 +++-----
 3 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/submittodebian b/submittodebian
index 86fa45f..2599ff4 100755
--- a/submittodebian
+++ b/submittodebian
@@ -27,7 +27,9 @@ import os
 import re
 import shutil
 import sys
-from subprocess import call, check_call, Popen, PIPE
+
+from subprocess import call, check_call, run, Popen, PIPE, DEVNULL
+
 from tempfile import mkdtemp
 
 from debian.changelog import Changelog
@@ -85,9 +87,8 @@ def gen_debdiff(tmpdir, changelog):
 
     debdiff = os.path.join(tmpdir, '%s_%s.debdiff' % (pkg, newver))
 
-    devnull = open('/dev/null', 'w')
     diff_cmd = ['bzr', 'diff', '-r', 'tag:' + str(oldver)]
-    if call(diff_cmd, stdout=devnull, stderr=devnull) == 1:
+    if call(diff_cmd, stdout=DEVNULL, stderr=DEVNULL) == 1:
         print("Extracting bzr diff between %s and %s" % (oldver, newver))
     else:
         if oldver.epoch is not None:
@@ -104,14 +105,10 @@ def gen_debdiff(tmpdir, changelog):
         print("Generating debdiff between %s and %s" % (oldver, newver))
         diff_cmd = ['debdiff', olddsc, newdsc]
 
-    diff = Popen(diff_cmd, stdout=PIPE)
-    debdiff_f = open(debdiff, 'w')
-    filterdiff = Popen(['filterdiff', '-x', '*changelog*'],
-                       stdin=diff.stdout, stdout=debdiff_f)
-    diff.stdout.close()
-    filterdiff.wait()
-    debdiff_f.close()
-    devnull.close()
+    with Popen(diff_cmd, stdout=PIPE, encoding='utf-8') as diff:
+        with open(debdiff, 'w', encoding='utf-8') as debdiff_f:
+            run(['filterdiff', '-x', '*changelog*'],
+                stdin=diff.stdout, stdout=debdiff_f, encoding='utf-8')
 
     return debdiff
 
diff --git a/ubuntu-iso b/ubuntu-iso
index dc52bac..fd56a66 100755
--- a/ubuntu-iso
+++ b/ubuntu-iso
@@ -27,15 +27,15 @@ import sys
 
 def extract(iso, path):
     command = ['isoinfo', '-R', '-i', iso, '-x', path]
-    pipe = subprocess.Popen(command, stdout=subprocess.PIPE,
-                            stderr=subprocess.PIPE, encoding='utf-8')
-    stdout, stderr = pipe.communicate()
+    pipe = subprocess.run(command, encoding='utf-8',
+                          stdout=subprocess.PIPE,
+                          stderr=subprocess.PIPE)
 
     if pipe.returncode != 0:
-        sys.stderr.write(stderr)
+        sys.stderr.write(pipe.stderr)
         sys.exit(pipe.returncode)
 
-    return stdout
+    return pipe.stdout
 
 
 def main():
diff --git a/ubuntutools/builder.py b/ubuntutools/builder.py
index 4c201d9..8ab478f 100644
--- a/ubuntutools/builder.py
+++ b/ubuntutools/builder.py
@@ -34,8 +34,7 @@ class Builder(object):
     def __init__(self, name):
         self.name = name
         cmd = ["dpkg-architecture", "-qDEB_BUILD_ARCH_CPU"]
-        self.architecture = subprocess.check_output(
-            cmd, encoding='utf-8').strip()
+        self.architecture = subprocess.check_output(cmd, encoding='utf-8').strip()
 
     def _build_failure(self, returncode, dsc_file):
         if returncode != 0:
@@ -124,9 +123,8 @@ class Sbuild(Builder):
     def update(self, dist):
         cmd = ["schroot", "--list"]
         Logger.command(cmd)
-        process = subprocess.Popen(
-            cmd, stdout=subprocess.PIPE, encoding='utf-8')
-        chroots, _ = process.communicate()[0].strip().split()
+        process = subprocess.run(cmd, stdout=subprocess.PIPE, encoding='utf-8')
+        chroots, _ = process.stdout.strip().split()
         if process.returncode != 0:
             return process.returncode