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# 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.
import logging
import pylib.android_commands
import pylib.device.device_utils
class FlagChanger(object):
"""Changes the flags Chrome runs with.
There are two different use cases for this file:
* Flags are permanently set by calling Set().
* Flags can be temporarily set for a particular set of unit tests. These
tests should call Restore() to revert the flags to their original state
once the tests have completed.
"""
def __init__(self, device, cmdline_file):
"""Initializes the FlagChanger and records the original arguments.
Args:
device: A DeviceUtils instance.
cmdline_file: Path to the command line file on the device.
"""
# TODO(jbudorick) Remove once telemetry switches over.
if isinstance(device, pylib.android_commands.AndroidCommands):
device = pylib.device.device_utils.DeviceUtils(device)
self._device = device
self._cmdline_file = cmdline_file
# Save the original flags.
self._orig_line = self._device.old_interface.GetFileContents(
self._cmdline_file)
if self._orig_line:
self._orig_line = self._orig_line[0].strip()
# Parse out the flags into a list to facilitate adding and removing flags.
self._current_flags = self._TokenizeFlags(self._orig_line)
def Get(self):
"""Returns list of current flags."""
return self._current_flags
def Set(self, flags):
"""Replaces all flags on the current command line with the flags given.
Args:
flags: A list of flags to set, eg. ['--single-process'].
"""
if flags:
assert flags[0] != 'chrome'
self._current_flags = flags
self._UpdateCommandLineFile()
def AddFlags(self, flags):
"""Appends flags to the command line if they aren't already there.
Args:
flags: A list of flags to add on, eg. ['--single-process'].
"""
if flags:
assert flags[0] != 'chrome'
# Avoid appending flags that are already present.
for flag in flags:
if flag not in self._current_flags:
self._current_flags.append(flag)
self._UpdateCommandLineFile()
def RemoveFlags(self, flags):
"""Removes flags from the command line, if they exist.
Args:
flags: A list of flags to remove, eg. ['--single-process']. Note that we
expect a complete match when removing flags; if you want to remove
a switch with a value, you must use the exact string used to add
it in the first place.
"""
if flags:
assert flags[0] != 'chrome'
for flag in flags:
if flag in self._current_flags:
self._current_flags.remove(flag)
self._UpdateCommandLineFile()
def Restore(self):
"""Restores the flags to their original state."""
self._current_flags = self._TokenizeFlags(self._orig_line)
self._UpdateCommandLineFile()
def _UpdateCommandLineFile(self):
"""Writes out the command line to the file, or removes it if empty."""
logging.info('Current flags: %s', self._current_flags)
# Root is not required to write to /data/local/tmp/.
use_root = '/data/local/tmp/' not in self._cmdline_file
if self._current_flags:
# The first command line argument doesn't matter as we are not actually
# launching the chrome executable using this command line.
cmd_line = ' '.join(['_'] + self._current_flags)
if use_root:
self._device.old_interface.SetProtectedFileContents(
self._cmdline_file, cmd_line)
file_contents = self._device.old_interface.GetProtectedFileContents(
self._cmdline_file)
else:
self._device.old_interface.SetFileContents(self._cmdline_file, cmd_line)
file_contents = self._device.old_interface.GetFileContents(
self._cmdline_file)
assert len(file_contents) == 1 and file_contents[0] == cmd_line, (
'Failed to set the command line file at %s' % self._cmdline_file)
else:
self._device.RunShellCommand('rm ' + self._cmdline_file, root=use_root)
assert (
not self._device.old_interface.FileExistsOnDevice(
self._cmdline_file)), (
'Failed to remove the command line file at %s' % self._cmdline_file)
@staticmethod
def _TokenizeFlags(line):
"""Changes the string containing the command line into a list of flags.
Follows similar logic to CommandLine.java::tokenizeQuotedArguments:
* Flags are split using whitespace, unless the whitespace is within a
pair of quotation marks.
* Unlike the Java version, we keep the quotation marks around switch
values since we need them to re-create the file when new flags are
appended.
Args:
line: A string containing the entire command line. The first token is
assumed to be the program name.
"""
if not line:
return []
tokenized_flags = []
current_flag = ""
within_quotations = False
# Move through the string character by character and build up each flag
# along the way.
for c in line.strip():
if c is '"':
if len(current_flag) > 0 and current_flag[-1] == '\\':
# Last char was a backslash; pop it, and treat this " as a literal.
current_flag = current_flag[0:-1] + '"'
else:
within_quotations = not within_quotations
current_flag += c
elif not within_quotations and (c is ' ' or c is '\t'):
if current_flag is not "":
tokenized_flags.append(current_flag)
current_flag = ""
else:
current_flag += c
# Tack on the last flag.
if not current_flag:
if within_quotations:
logging.warn('Unterminated quoted argument: ' + line)
else:
tokenized_flags.append(current_flag)
# Return everything but the program name.
return tokenized_flags[1:]
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