Revert of Migrate DeviceUtils.ReadFile to adb_wrapper

build/android/pylib/device/device_utils.py

 # Copyright 2014 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.
 
 """Provides a variety of device interactions based on adb.
 
 Eventually, this will be based on adb_wrapper.
 """
 # pylint: disable=W0613
 
@@ skipping 38 matching lines @@
     _DEFAULT_TIMEOUT, _DEFAULT_RETRIES)
 def RestartServer():
   """Restarts the adb server.
 
   Raises:
     CommandFailedError if we fail to kill or restart the server.
   """
   pylib.android_commands.AndroidCommands().RestartAdbServer()
 
 
-def _JoinLines(lines):
-  # makes sure that the last line is also terminated, and is more memory
-  # efficient than first appending an end-line to each line and then joining
-  # all of them together.
-  return ''.join(s for line in lines for s in (line, '\n'))
-
-
 class DeviceUtils(object):
 
   _VALID_SHELL_VARIABLE = re.compile('^[a-zA-Z_][a-zA-Z0-9_]*$')
 
   def __init__(self, device, default_timeout=_DEFAULT_TIMEOUT,
                default_retries=_DEFAULT_RETRIES):
     """DeviceUtils constructor.
 
     Args:
       device: Either a device serial, an existing AdbWrapper instance, or an
@@ skipping 781 matching lines @@
       CommandFailedError on failure.
       CommandTimeoutError on timeout.
     """
     try:
       self.old_interface.PullFileFromDevice(device_path, host_path)
     except AssertionError as e:
       raise device_errors.CommandFailedError(
           str(e), str(self)), None, sys.exc_info()[2]
 
   @decorators.WithTimeoutAndRetriesFromInstance()
-  def ReadFile(self, device_path, as_root=False,
-               timeout=None, retries=None):
+  def ReadFile(self, device_path, as_root=False, timeout=None, retries=None):
     """Reads the contents of a file from the device.
 
     Args:
       device_path: A string containing the absolute path of the file to read
                    from the device.
       as_root: A boolean indicating whether the read should be executed with
                root privileges.
       timeout: timeout in seconds
       retries: number of retries
 
     Returns:
-      The contents of |device_path| as a string. Contents are intepreted using
-      universal newlines, so the caller will see them encoded as '\n'. Also,
-      all lines will be terminated.
+      The contents of the file at |device_path| as a list of lines.
 
     Raises:
-      AdbCommandFailedError if the file can't be read.
+      CommandFailedError if the file can't be read.
       CommandTimeoutError on timeout.
       DeviceUnreachableError on missing device.
     """
-    return _JoinLines(self.RunShellCommand(
-        ['cat', device_path], as_root=as_root, check_return=True))
+    # TODO(jbudorick) Evaluate whether we want to return a list of lines after
+    # the implementation switch, and if file not found should raise exception.
+    if as_root:
+      if not self.old_interface.CanAccessProtectedFileContents():
+        raise device_errors.CommandFailedError(
+          'Cannot read from %s with root privileges.' % device_path)
+      return self.old_interface.GetProtectedFileContents(device_path)
+    else:
+      return self.old_interface.GetFileContents(device_path)
 
   @decorators.WithTimeoutAndRetriesFromInstance()
   def WriteFile(self, device_path, contents, as_root=False, force_push=False,
                 timeout=None, retries=None):
     """Writes |contents| to a file on the device.
 
     Args:
       device_path: A string containing the absolute path to the file to write
           on the device.
       contents: A string containing the data to write to the device.
@@ skipping 263 matching lines @@
     Returns:
       A Parallelizer operating over |devices|.
     """
     if not devices or len(devices) == 0:
       devices = pylib.android_commands.GetAttachedDevices()
     parallelizer_type = (parallelizer.Parallelizer if async
                          else parallelizer.SyncParallelizer)
     return parallelizer_type([
         d if isinstance(d, DeviceUtils) else DeviceUtils(d)
         for d in devices])