Reland of 'New run shell implementation for DeviceUtils'

build/android/pylib/cmd_helper.py

Index: build/android/pylib/cmd_helper.py
diff --git a/build/android/pylib/cmd_helper.py b/build/android/pylib/cmd_helper.py
index aba00be735368e9e931e321b14bef1d46ad1fbf3..ab9105411c784b31a9d2e72e4b91648689035057 100644
--- a/build/android/pylib/cmd_helper.py
+++ b/build/android/pylib/cmd_helper.py
@@ -9,6 +9,7 @@ import os
 import pipes
 import select
 import signal
+import string
 import StringIO
 import subprocess
 import time
@@ -19,6 +20,52 @@ try:
 except ImportError:
   fcntl = None
 
+_SafeShellChars = frozenset(string.ascii_letters + string.digits + '@%_-+=:,./')
+
+def SingleQuote(s):
+  """Return an shell-escaped version of the string using single quotes.
+
+  Reliably quote a string which may contain unsafe characters (e.g. space,
+  quote, or other special characters such as '$').
+
+  The returned value can be used in a shell command line as one token that gets
+  to be interpreted literally.
+
+  Args:
+    s: The string to quote.
+
+  Return:
+    The string quoted using single quotes.
+  """
+  return pipes.quote(s)
+
+def DoubleQuote(s):
+  """Return an shell-escaped version of the string using double quotes.
+
+  Reliably quote a string which may contain unsafe characters (e.g. space
+  or quote characters), while retaining some shell features such as variable
+  interpolation.
+
+  The returned value can be used in a shell command line as one token that gets
+  to be further interpreted by the shell.
+
+  The set of characters that retain their special meaning may depend on the
+  shell implementation. This set usually includes: '$', '`', '\', '!', '*',
+  and '@'.
+
+  Args:
+    s: The string to quote.
+
+  Return:
+    The string quoted using double quotes.
+  """
+  if not s:
+    return '""'
+  elif 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(
@@ -88,7 +135,7 @@ def GetCmdStatusAndOutput(args, cwd=None, shell=False):
   elif shell:
     raise Exception('array args must be run with shell=False')
   else:
-    args_repr = ' '.join(map(pipes.quote, args))
+    args_repr = ' '.join(map(SingleQuote, args))
 
   s = '[host]'
   if cwd: