Remove need for shell wrap complexity

client/update_grub.py

@@ -4,7 +4,7 @@ import os
 import re
 import string
 import subprocess
-import sys
+import tempfile
 
 
 class GrubUpdater(object):
@@ -30,23 +30,26 @@ class GrubUpdater(object):
     return match.group('volume_id').decode('ascii')
 
   def Update(self):
-    current = os.readlink(os.path.join(self._image_dir, 'current'))
+    grub_dir = os.path.join(self._boot_dir, 'grub')
 
-    sys.stdout.write("""
+    with tempfile.NamedTemporaryFile(dir=grub_dir, delete=False) as fh:
+      current = os.readlink(os.path.join(self._image_dir, 'current'))
+
+      fh.write("""
 set timeout=5
 set default=%(default_image_filename)s
 """ % {
-      'default_image_filename': os.path.basename(current),
-    })
+        'default_image_filename': os.path.basename(current),
+      })
 
-    files = []
-    for filename in os.listdir(self._image_dir):
-      if not filename.endswith('.iso'):
-        continue
-      files.append(filename)
+      files = []
+      for filename in os.listdir(self._image_dir):
+        if not filename.endswith('.iso'):
+          continue
+        files.append(filename)
 
-    for i, filename in enumerate(sorted(files, reverse=True)):
-      sys.stdout.write("""
+      for i, filename in enumerate(sorted(files, reverse=True)):
+        fh.write("""
 menuentry "%(image_filename)s (%(volume_id)s)" --hotkey=%(hotkey)s {
   search --no-floppy --file --set=root %(image_path)s/%(image_filename)s
   iso_path="%(image_path)s/%(image_filename)s"
@@ -56,8 +59,11 @@ menuentry "%(image_filename)s (%(volume_id)s)" --hotkey=%(hotkey)s {
   configfile /boot/grub/loopback.cfg
 }
 """ % {
-        'image_filename': filename,
-        'image_path': self._image_path,
-        'hotkey': self._HOTKEYS[i],
-        'volume_id': self._GetVolumeID(os.path.join(self._image_dir, filename)),
-      })
+          'image_filename': filename,
+          'image_path': self._image_path,
+          'hotkey': self._HOTKEYS[i],
+          'volume_id': self._GetVolumeID(os.path.join(self._image_dir, filename)),
+        })
+
+      fh.flush()
+      os.rename(fh.name, os.path.join(grub_dir, 'grub.cfg'))