New run shell implementation for DeviceUtils

build/android/pylib/cmd_helper.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """A wrapper for subprocess to make calling shell commands easier."""
 
 import logging
 import os
 import pipes
 import select
 import signal
+import string
 import StringIO
 import subprocess
 import time
 
 # fcntl is not available on Windows.
 try:
   import fcntl
 except ImportError:
   fcntl = None
 
+_SafeShellChars = frozenset(string.ascii_letters + string.digits + '@%_-+=:,./')
+
+quote = pipes.quote

[jbudorick, 2014/10/17 09:04:52]

I don't think I like this. Let callers use pipes.quote.

+
+def dquote(s):

[jbudorick, 2014/10/17 09:04:53]

While I understand that you're mimicking pipes.quote, I don't think I like
breaking our style guide here by starting with a lower-case letter.

[perezju, 2014/10/17 11:17:09]

Done.

+  """Return an escaped version of the string using double quotes.
+
+  A sibling to pipes.quote that uses double rather than single quotes.
+  Meant to be used to quote strings which may contain unsafe characters (e.g.
+  spaces), while retaining some shell features such as variable interpolation.
+
+  The set of characters that retain their special meaning may depend on the
+  shell implementation. It usually includes: '$', '`', '\', '!', '*', and '@'.
+  """
+  if not s:

[jbudorick, 2014/10/17 09:04:52]

Also, this function should have some unit tests.

[perezju, 2014/10/17 11:17:09]

Done.

+    return '""'
+  if all(c in _SafeShellChars for c in s):
+    return s
+  else:
+    return '"' + s.replace('"', '\\"') + '"'
+
 
 def Popen(args, stdout=None, stderr=None, shell=None, cwd=None, env=None):
   return subprocess.Popen(
       args=args, cwd=cwd, stdout=stdout, stderr=stderr,
       shell=shell, close_fds=True, env=env,
       preexec_fn=lambda: signal.signal(signal.SIGPIPE, signal.SIG_DFL))
 
 
 def Call(args, stdout=None, stderr=None, shell=None, cwd=None, env=None):
   pipe = Popen(args, stdout=stdout, stderr=stderr, shell=shell, cwd=cwd,
@@ skipping 49 matching lines @@
   Returns:
     The 2-tuple (exit code, output).
   """
   if isinstance(args, basestring):
     args_repr = args
     if not shell:
       raise Exception('string args must be run with shell=True')
   elif shell:
     raise Exception('array args must be run with shell=False')
   else:
-    args_repr = ' '.join(map(pipes.quote, args))
+    args_repr = ' '.join(map(quote, args))
 
   s = '[host]'
   if cwd:
     s += ':' + cwd
   s += '> ' + args_repr
   logging.info(s)
   pipe = Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                shell=shell, cwd=cwd)
   stdout, stderr = pipe.communicate()
 
@@ skipping 56 matching lines @@
         break
   finally:
     try:
       # Make sure the process doesn't stick around if we fail with an
       # exception.
       process.kill()
     except OSError:
       pass
     process.wait()
   return process.returncode, output.getvalue()