1# Copyright 2013 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"""Top-level presubmit script for Chromium media component.
6
7See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
8for more details about the presubmit API built into gcl.
9"""
10
11def _FilterFile(affected_file):
12  """Return true if the file could contain code requiring a presubmit check."""
13  return affected_file.LocalPath().endswith(
14      ('.h', '.cc', '.cpp', '.cxx', '.mm'))
15
16
17def _CheckForUseOfWrongClock(input_api, output_api):
18  """Make sure new lines of media code don't use a clock susceptible to skew."""
19
20  # Regular expression that should detect any explicit references to the
21  # base::Time type (or base::Clock/DefaultClock), whether in using decls,
22  # typedefs, or to call static methods.
23  base_time_type_pattern = r'(^|\W)base::(Time|Clock|DefaultClock)(\W|$)'
24
25  # Regular expression that should detect references to the base::Time class
26  # members, such as a call to base::Time::Now.
27  base_time_member_pattern = r'(^|\W)(Time|Clock|DefaultClock)::'
28
29  # Regular expression to detect "using base::Time" declarations.  We want to
30  # prevent these from triggerring a warning.  For example, it's perfectly
31  # reasonable for code to be written like this:
32  #
33  #   using base::Time;
34  #   ...
35  #   int64 foo_us = foo_s * Time::kMicrosecondsPerSecond;
36  using_base_time_decl_pattern = r'^\s*using\s+(::)?base::Time\s*;'
37
38  # Regular expression to detect references to the kXXX constants in the
39  # base::Time class.  We want to prevent these from triggerring a warning.
40  base_time_konstant_pattern = r'(^|\W)Time::k\w+'
41
42  problem_re = input_api.re.compile(
43      r'(' + base_time_type_pattern + r')|(' + base_time_member_pattern + r')')
44  exception_re = input_api.re.compile(
45      r'(' + using_base_time_decl_pattern + r')|(' +
46      base_time_konstant_pattern + r')')
47  problems = []
48  for f in input_api.AffectedSourceFiles(_FilterFile):
49    for line_number, line in f.ChangedContents():
50      if problem_re.search(line):
51        if not exception_re.search(line):
52          problems.append(
53              '  %s:%d\n    %s' % (f.LocalPath(), line_number, line.strip()))
54
55  if problems:
56    return [output_api.PresubmitPromptOrNotify(
57        'You added one or more references to the base::Time class and/or one\n'
58        'of its member functions (or base::Clock/DefaultClock). In media\n'
59        'code, it is rarely correct to use a clock susceptible to time skew!\n'
60        'Instead, could you use base::TimeTicks to track the passage of\n'
61        'real-world time?\n\n' +
62        '\n'.join(problems))]
63  else:
64    return []
65
66
67def _CheckForMessageLoopProxy(input_api, output_api):
68  """Make sure media code only uses MessageLoopProxy for accessing the current
69  loop."""
70
71  message_loop_proxy_re = input_api.re.compile(
72      r'\bMessageLoopProxy(?!::current\(\))')
73
74  problems = []
75  for f in input_api.AffectedSourceFiles(_FilterFile):
76    for line_number, line in f.ChangedContents():
77      if message_loop_proxy_re.search(line):
78        problems.append('%s:%d' % (f.LocalPath(), line_number))
79
80  if problems:
81    return [output_api.PresubmitError(
82      'MessageLoopProxy should only be used for accessing the current loop.\n'
83      'Use the TaskRunner interfaces instead as they are more explicit about\n'
84      'the run-time characteristics. In most cases, SingleThreadTaskRunner\n'
85      'is a drop-in replacement for MessageLoopProxy.', problems)]
86
87  return []
88
89
90def _CheckForHistogramOffByOne(input_api, output_api):
91  """Make sure histogram enum maxes are used properly"""
92
93  # A general-purpose chunk of regex to match whitespace and/or comments
94  # that may be interspersed with the code we're interested in:
95  comment = r'/\*.*?\*/|//[^\n]*'
96  whitespace = r'(?:[\n\t ]|(?:' + comment + r'))*'
97
98  # The name is assumed to be a literal string.
99  histogram_name = r'"[^"]*"'
100
101  # This can be an arbitrary expression, so just ensure it isn't a ; to prevent
102  # matching past the end of this statement.
103  histogram_value = r'[^;]*'
104
105  # In parens so we can retrieve it for further checks.
106  histogram_max = r'([^;,]*)'
107
108  # This should match a uma histogram enumeration macro expression.
109  uma_macro_re = input_api.re.compile(
110      r'\bUMA_HISTOGRAM_ENUMERATION\(' + whitespace + histogram_name + r',' +
111      whitespace + histogram_value + r',' + whitespace + histogram_max +
112      whitespace + r'\)' + whitespace + r';(?:' + whitespace +
113      r'\/\/ (PRESUBMIT_IGNORE_UMA_MAX))?')
114
115  uma_max_re = input_api.re.compile(r'.*(?:Max|MAX).* \+ 1')
116
117  problems = []
118
119  for f in input_api.AffectedSourceFiles(_FilterFile):
120    contents = input_api.ReadFile(f)
121
122    # We want to match across lines, but still report a line number, so we keep
123    # track of the line we're on as we search through the file.
124    line_number = 1
125
126    # We search the entire file, then check if any violations are in the changed
127    # areas, this is inefficient, but simple. A UMA_HISTOGRAM_ENUMERATION call
128    # will often span multiple lines, so finding a match looking just at the
129    # deltas line-by-line won't catch problems.
130    match = uma_macro_re.search(contents)
131    while match:
132      line_number += contents.count('\n', 0, match.start())
133      max_arg = match.group(1) # The third argument.
134
135      if (not uma_max_re.match(max_arg) and match.group(2) !=
136          'PRESUBMIT_IGNORE_UMA_MAX'):
137        uma_range = range(match.start(), match.end() + 1)
138        # Check if any part of the match is in the changed lines:
139        for num, line in f.ChangedContents():
140          if line_number <= num <= line_number + match.group().count('\n'):
141            problems.append('%s:%d' % (f, line_number))
142            break
143
144      # Strip off the file contents up to the end of the match and update the
145      # line number.
146      contents = contents[match.end():]
147      line_number += match.group().count('\n')
148      match = uma_macro_re.search(contents)
149
150  if problems:
151    return [output_api.PresubmitError(
152      'UMA_HISTOGRAM_ENUMERATION reports in src/media/ are expected to adhere\n'
153      'to the following guidelines:\n'
154      ' - The max value (3rd argument) should be an enum value equal to the\n'
155      '   last valid value, e.g. FOO_MAX = LAST_VALID_FOO.\n'
156      ' - 1 must be added to that max value.\n'
157      'Contact rileya@chromium.org if you have questions.' , problems)]
158
159  return []
160
161
162def _CheckChange(input_api, output_api):
163  results = []
164  results.extend(_CheckForUseOfWrongClock(input_api, output_api))
165  results.extend(_CheckForMessageLoopProxy(input_api, output_api))
166  results.extend(_CheckForHistogramOffByOne(input_api, output_api))
167  return results
168
169
170def CheckChangeOnUpload(input_api, output_api):
171  return _CheckChange(input_api, output_api)
172
173
174def CheckChangeOnCommit(input_api, output_api):
175  return _CheckChange(input_api, output_api)
176