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1 # Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
2 # Use of this source code is governed by a BSD-style license that can be | |
3 # found in the LICENSE file. | |
4 | |
5 import logging | |
6 | |
7 import pylib.android_commands | |
8 import pylib.device.device_utils | |
9 | |
10 from pylib.device import device_errors | |
11 | |
12 | |
13 class FlagChanger(object): | |
14 """Changes the flags Chrome runs with. | |
15 | |
16 There are two different use cases for this file: | |
17 * Flags are permanently set by calling Set(). | |
18 * Flags can be temporarily set for a particular set of unit tests. These | |
19 tests should call Restore() to revert the flags to their original state | |
20 once the tests have completed. | |
21 """ | |
22 | |
23 def __init__(self, device, cmdline_file): | |
24 """Initializes the FlagChanger and records the original arguments. | |
25 | |
26 Args: | |
27 device: A DeviceUtils instance. | |
28 cmdline_file: Path to the command line file on the device. | |
29 """ | |
30 # TODO(jbudorick) Remove once telemetry switches over. | |
31 if isinstance(device, pylib.android_commands.AndroidCommands): | |
32 device = pylib.device.device_utils.DeviceUtils(device) | |
33 self._device = device | |
34 self._cmdline_file = cmdline_file | |
35 | |
36 # Save the original flags. | |
37 try: | |
38 self._orig_line = self._device.ReadFile(self._cmdline_file).strip() | |
39 except device_errors.CommandFailedError: | |
40 self._orig_line = '' | |
41 | |
42 # Parse out the flags into a list to facilitate adding and removing flags. | |
43 self._current_flags = self._TokenizeFlags(self._orig_line) | |
44 | |
45 def Get(self): | |
46 """Returns list of current flags.""" | |
47 return self._current_flags | |
48 | |
49 def Set(self, flags): | |
50 """Replaces all flags on the current command line with the flags given. | |
51 | |
52 Args: | |
53 flags: A list of flags to set, eg. ['--single-process']. | |
54 """ | |
55 if flags: | |
56 assert flags[0] != 'chrome' | |
57 | |
58 self._current_flags = flags | |
59 self._UpdateCommandLineFile() | |
60 | |
61 def AddFlags(self, flags): | |
62 """Appends flags to the command line if they aren't already there. | |
63 | |
64 Args: | |
65 flags: A list of flags to add on, eg. ['--single-process']. | |
66 """ | |
67 if flags: | |
68 assert flags[0] != 'chrome' | |
69 | |
70 # Avoid appending flags that are already present. | |
71 for flag in flags: | |
72 if flag not in self._current_flags: | |
73 self._current_flags.append(flag) | |
74 self._UpdateCommandLineFile() | |
75 | |
76 def RemoveFlags(self, flags): | |
77 """Removes flags from the command line, if they exist. | |
78 | |
79 Args: | |
80 flags: A list of flags to remove, eg. ['--single-process']. Note that we | |
81 expect a complete match when removing flags; if you want to remove | |
82 a switch with a value, you must use the exact string used to add | |
83 it in the first place. | |
84 """ | |
85 if flags: | |
86 assert flags[0] != 'chrome' | |
87 | |
88 for flag in flags: | |
89 if flag in self._current_flags: | |
90 self._current_flags.remove(flag) | |
91 self._UpdateCommandLineFile() | |
92 | |
93 def Restore(self): | |
94 """Restores the flags to their original state.""" | |
95 self._current_flags = self._TokenizeFlags(self._orig_line) | |
96 self._UpdateCommandLineFile() | |
97 | |
98 def _UpdateCommandLineFile(self): | |
99 """Writes out the command line to the file, or removes it if empty.""" | |
100 logging.info('Current flags: %s', self._current_flags) | |
101 # Root is not required to write to /data/local/tmp/. | |
102 use_root = '/data/local/tmp/' not in self._cmdline_file | |
103 if self._current_flags: | |
104 # The first command line argument doesn't matter as we are not actually | |
105 # launching the chrome executable using this command line. | |
106 cmd_line = ' '.join(['_'] + self._current_flags) | |
107 self._device.WriteFile( | |
108 self._cmdline_file, cmd_line, as_root=use_root) | |
109 file_contents = self._device.ReadFile( | |
110 self._cmdline_file, as_root=use_root).rstrip() | |
111 assert file_contents == cmd_line, ( | |
112 'Failed to set the command line file at %s' % self._cmdline_file) | |
113 else: | |
114 self._device.RunShellCommand('rm ' + self._cmdline_file, | |
115 as_root=use_root) | |
116 assert not self._device.FileExists(self._cmdline_file), ( | |
117 'Failed to remove the command line file at %s' % self._cmdline_file) | |
118 | |
119 @staticmethod | |
120 def _TokenizeFlags(line): | |
121 """Changes the string containing the command line into a list of flags. | |
122 | |
123 Follows similar logic to CommandLine.java::tokenizeQuotedArguments: | |
124 * Flags are split using whitespace, unless the whitespace is within a | |
125 pair of quotation marks. | |
126 * Unlike the Java version, we keep the quotation marks around switch | |
127 values since we need them to re-create the file when new flags are | |
128 appended. | |
129 | |
130 Args: | |
131 line: A string containing the entire command line. The first token is | |
132 assumed to be the program name. | |
133 """ | |
134 if not line: | |
135 return [] | |
136 | |
137 tokenized_flags = [] | |
138 current_flag = "" | |
139 within_quotations = False | |
140 | |
141 # Move through the string character by character and build up each flag | |
142 # along the way. | |
143 for c in line.strip(): | |
144 if c is '"': | |
145 if len(current_flag) > 0 and current_flag[-1] == '\\': | |
146 # Last char was a backslash; pop it, and treat this " as a literal. | |
147 current_flag = current_flag[0:-1] + '"' | |
148 else: | |
149 within_quotations = not within_quotations | |
150 current_flag += c | |
151 elif not within_quotations and (c is ' ' or c is '\t'): | |
152 if current_flag is not "": | |
153 tokenized_flags.append(current_flag) | |
154 current_flag = "" | |
155 else: | |
156 current_flag += c | |
157 | |
158 # Tack on the last flag. | |
159 if not current_flag: | |
160 if within_quotations: | |
161 logging.warn('Unterminated quoted argument: ' + line) | |
162 else: | |
163 tokenized_flags.append(current_flag) | |
164 | |
165 # Return everything but the program name. | |
166 return tokenized_flags[1:] | |
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