PRESUBMIT.py

# 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.

"""Top-level presubmit script for Chromium.

See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
for more details about the presubmit API built into gcl.
"""


import re
import subprocess
import sys


_EXCLUDED_PATHS = (
    r"^breakpad[\\\/].*",
    r"^native_client_sdk[\\\/]src[\\\/]build_tools[\\\/]make_rules.py",
    r"^native_client_sdk[\\\/]src[\\\/]build_tools[\\\/]make_simple.py",
    r"^native_client_sdk[\\\/]src[\\\/]tools[\\\/].*.mk",
    r"^net[\\\/]tools[\\\/]spdyshark[\\\/].*",
    r"^skia[\\\/].*",
    r"^v8[\\\/].*",
    r".*MakeFile$",
    r".+_autogen\.h$",
    r".+[\\\/]pnacl_shim\.c$",
)

# Fragment of a regular expression that matches C++ and Objective-C++
# implementation files.
_IMPLEMENTATION_EXTENSIONS = r'\.(cc|cpp|cxx|mm)$'

# Regular expression that matches code only used for test binaries
# (best effort).
_TEST_CODE_EXCLUDED_PATHS = (
    r'.*[/\\](fake_|test_|mock_).+%s' % _IMPLEMENTATION_EXTENSIONS,
    r'.+_test_(base|support|util)%s' % _IMPLEMENTATION_EXTENSIONS,
    r'.+_(api|browser|perf|pixel|unit|ui)?test(_[a-z]+)?%s' %
        _IMPLEMENTATION_EXTENSIONS,
    r'.+profile_sync_service_harness%s' % _IMPLEMENTATION_EXTENSIONS,
    r'.*[/\\](test|tool(s)?)[/\\].*',
    # content_shell is used for running layout tests.
    r'content[/\\]shell[/\\].*',
    # At request of folks maintaining this folder.
    r'chrome[/\\]browser[/\\]automation[/\\].*',
)

_TEST_ONLY_WARNING = (
    'You might be calling functions intended only for testing from\n'
    'production code.  It is OK to ignore this warning if you know what\n'
    'you are doing, as the heuristics used to detect the situation are\n'
    'not perfect.  The commit queue will not block on this warning.\n'
    'Email joi@chromium.org if you have questions.')


_INCLUDE_ORDER_WARNING = (
    'Your #include order seems to be broken. Send mail to\n'
    'marja@chromium.org if this is not the case.')


_BANNED_OBJC_FUNCTIONS = (
    (
      'addTrackingRect:',
      (
       'The use of -[NSView addTrackingRect:owner:userData:assumeInside:] is'
       'prohibited. Please use CrTrackingArea instead.',
       'http://dev.chromium.org/developers/coding-style/cocoa-dos-and-donts',
      ),
      False,
    ),
    (
      'NSTrackingArea',
      (
       'The use of NSTrackingAreas is prohibited. Please use CrTrackingArea',
       'instead.',
       'http://dev.chromium.org/developers/coding-style/cocoa-dos-and-donts',
      ),
      False,
    ),
    (
      'convertPointFromBase:',
      (
       'The use of -[NSView convertPointFromBase:] is almost certainly wrong.',
       'Please use |convertPoint:(point) fromView:nil| instead.',
       'http://dev.chromium.org/developers/coding-style/cocoa-dos-and-donts',
      ),
      True,
    ),
    (
      'convertPointToBase:',
      (
       'The use of -[NSView convertPointToBase:] is almost certainly wrong.',
       'Please use |convertPoint:(point) toView:nil| instead.',
       'http://dev.chromium.org/developers/coding-style/cocoa-dos-and-donts',
      ),
      True,
    ),
    (
      'convertRectFromBase:',
      (
       'The use of -[NSView convertRectFromBase:] is almost certainly wrong.',
       'Please use |convertRect:(point) fromView:nil| instead.',
       'http://dev.chromium.org/developers/coding-style/cocoa-dos-and-donts',
      ),
      True,
    ),
    (
      'convertRectToBase:',
      (
       'The use of -[NSView convertRectToBase:] is almost certainly wrong.',
       'Please use |convertRect:(point) toView:nil| instead.',
       'http://dev.chromium.org/developers/coding-style/cocoa-dos-and-donts',
      ),
      True,
    ),
    (
      'convertSizeFromBase:',
      (
       'The use of -[NSView convertSizeFromBase:] is almost certainly wrong.',
       'Please use |convertSize:(point) fromView:nil| instead.',
       'http://dev.chromium.org/developers/coding-style/cocoa-dos-and-donts',
      ),
      True,
    ),
    (
      'convertSizeToBase:',
      (
       'The use of -[NSView convertSizeToBase:] is almost certainly wrong.',
       'Please use |convertSize:(point) toView:nil| instead.',
       'http://dev.chromium.org/developers/coding-style/cocoa-dos-and-donts',
      ),
      True,
    ),
)


_BANNED_CPP_FUNCTIONS = (
    # Make sure that gtest's FRIEND_TEST() macro is not used; the
    # FRIEND_TEST_ALL_PREFIXES() macro from base/gtest_prod_util.h should be
    # used instead since that allows for FLAKY_ and DISABLED_ prefixes.
    (
      'FRIEND_TEST(',
      (
       'Chromium code should not use gtest\'s FRIEND_TEST() macro. Include',
       'base/gtest_prod_util.h and use FRIEND_TEST_ALL_PREFIXES() instead.',
      ),
      False,
      (),
    ),
    (
      'ScopedAllowIO',
      (
       'New code should not use ScopedAllowIO. Post a task to the blocking',
       'pool or the FILE thread instead.',
      ),
      True,
      (
        r"^content[\\\/]shell[\\\/]shell_browser_main\.cc$",
        r"^net[\\\/]disk_cache[\\\/]cache_util\.cc$",
      ),
    ),
)


_VALID_OS_MACROS = (
    # Please keep sorted.
    'OS_ANDROID',
    'OS_BSD',
    'OS_CAT',       # For testing.
    'OS_CHROMEOS',
    'OS_FREEBSD',
    'OS_IOS',
    'OS_LINUX',
    'OS_MACOSX',
    'OS_NACL',
    'OS_OPENBSD',
    'OS_POSIX',
    'OS_SOLARIS',
    'OS_WIN',
)


def _CheckNoProductionCodeUsingTestOnlyFunctions(input_api, output_api):
  """Attempts to prevent use of functions intended only for testing in
  non-testing code. For now this is just a best-effort implementation
  that ignores header files and may have some false positives. A
  better implementation would probably need a proper C++ parser.
  """
  # We only scan .cc files and the like, as the declaration of
  # for-testing functions in header files are hard to distinguish from
  # calls to such functions without a proper C++ parser.
  file_inclusion_pattern = r'.+%s' % _IMPLEMENTATION_EXTENSIONS

  base_function_pattern = r'ForTest(ing)?|for_test(ing)?'
  inclusion_pattern = input_api.re.compile(r'(%s)\s*\(' % base_function_pattern)
  exclusion_pattern = input_api.re.compile(
    r'::[A-Za-z0-9_]+(%s)|(%s)[^;]+\{' % (
      base_function_pattern, base_function_pattern))

  def FilterFile(affected_file):
    black_list = (_EXCLUDED_PATHS +
                  _TEST_CODE_EXCLUDED_PATHS +
                  input_api.DEFAULT_BLACK_LIST)
    return input_api.FilterSourceFile(
      affected_file,
      white_list=(file_inclusion_pattern, ),
      black_list=black_list)

  problems = []
  for f in input_api.AffectedSourceFiles(FilterFile):
    local_path = f.LocalPath()
    lines = input_api.ReadFile(f).splitlines()
    line_number = 0
    for line in lines:
      if (inclusion_pattern.search(line) and
          not exclusion_pattern.search(line)):
        problems.append(
          '%s:%d\n    %s' % (local_path, line_number, line.strip()))
      line_number += 1

  if problems:
    return [output_api.PresubmitPromptOrNotify(_TEST_ONLY_WARNING, problems)]
  else:
    return []


def _CheckNoIOStreamInHeaders(input_api, output_api):
  """Checks to make sure no .h files include <iostream>."""
  files = []
  pattern = input_api.re.compile(r'^#include\s*<iostream>',
                                 input_api.re.MULTILINE)
  for f in input_api.AffectedSourceFiles(input_api.FilterSourceFile):
    if not f.LocalPath().endswith('.h'):
      continue
    contents = input_api.ReadFile(f)
    if pattern.search(contents):
      files.append(f)

  if len(files):
    return [ output_api.PresubmitError(
        'Do not #include <iostream> in header files, since it inserts static '
        'initialization into every file including the header. Instead, '
        '#include <ostream>. See http://crbug.com/94794',
        files) ]
  return []


def _CheckNoUNIT_TESTInSourceFiles(input_api, output_api):
  """Checks to make sure no source files use UNIT_TEST"""
  problems = []
  for f in input_api.AffectedFiles():
    if (not f.LocalPath().endswith(('.cc', '.mm'))):
      continue

    for line_num, line in f.ChangedContents():
      if 'UNIT_TEST' in line:
        problems.append('    %s:%d' % (f.LocalPath(), line_num))

  if not problems:
    return []
  return [output_api.PresubmitPromptWarning('UNIT_TEST is only for headers.\n' +
      '\n'.join(problems))]


def _CheckNoNewWStrings(input_api, output_api):
  """Checks to make sure we don't introduce use of wstrings."""
  problems = []
  for f in input_api.AffectedFiles():
    if (not f.LocalPath().endswith(('.cc', '.h')) or
        f.LocalPath().endswith('test.cc')):
      continue

    allowWString = False
    for line_num, line in f.ChangedContents():
      if 'presubmit: allow wstring' in line:
        allowWString = True
      elif not allowWString and 'wstring' in line:
        problems.append('    %s:%d' % (f.LocalPath(), line_num))
        allowWString = False
      else:
        allowWString = False

  if not problems:
    return []
  return [output_api.PresubmitPromptWarning('New code should not use wstrings.'
      '  If you are calling a cross-platform API that accepts a wstring, '
      'fix the API.\n' +
      '\n'.join(problems))]


def _CheckNoDEPSGIT(input_api, output_api):
  """Make sure .DEPS.git is never modified manually."""
  if any(f.LocalPath().endswith('.DEPS.git') for f in
      input_api.AffectedFiles()):
    return [output_api.PresubmitError(
      'Never commit changes to .DEPS.git. This file is maintained by an\n'
      'automated system based on what\'s in DEPS and your changes will be\n'
      'overwritten.\n'
      'See http://code.google.com/p/chromium/wiki/UsingNewGit#Rolling_DEPS\n'
      'for more information')]
  return []


def _CheckNoBannedFunctions(input_api, output_api):
  """Make sure that banned functions are not used."""
  warnings = []
  errors = []

  file_filter = lambda f: f.LocalPath().endswith(('.mm', '.m', '.h'))
  for f in input_api.AffectedFiles(file_filter=file_filter):
    for line_num, line in f.ChangedContents():
      for func_name, message, error in _BANNED_OBJC_FUNCTIONS:
        if func_name in line:
          problems = warnings;
          if error:
            problems = errors;
          problems.append('    %s:%d:' % (f.LocalPath(), line_num))
          for message_line in message:
            problems.append('      %s' % message_line)

  file_filter = lambda f: f.LocalPath().endswith(('.cc', '.mm', '.h'))
  for f in input_api.AffectedFiles(file_filter=file_filter):
    for line_num, line in f.ChangedContents():
      for func_name, message, error, excluded_paths in _BANNED_CPP_FUNCTIONS:
        def IsBlacklisted(affected_file, blacklist):
          local_path = affected_file.LocalPath()
          for item in blacklist:
            if input_api.re.match(item, local_path):
              return True
          return False
        if IsBlacklisted(f, excluded_paths):
          continue
        if func_name in line:
          problems = warnings;
          if error:
            problems = errors;
          problems.append('    %s:%d:' % (f.LocalPath(), line_num))
          for message_line in message:
            problems.append('      %s' % message_line)

  result = []
  if (warnings):
    result.append(output_api.PresubmitPromptWarning(
        'Banned functions were used.\n' + '\n'.join(warnings)))
  if (errors):
    result.append(output_api.PresubmitError(
        'Banned functions were used.\n' + '\n'.join(errors)))
  return result


def _CheckNoPragmaOnce(input_api, output_api):
  """Make sure that banned functions are not used."""
  files = []
  pattern = input_api.re.compile(r'^#pragma\s+once',
                                 input_api.re.MULTILINE)
  for f in input_api.AffectedSourceFiles(input_api.FilterSourceFile):
    if not f.LocalPath().endswith('.h'):
      continue
    contents = input_api.ReadFile(f)
    if pattern.search(contents):
      files.append(f)

  if files:
    return [output_api.PresubmitError(
        'Do not use #pragma once in header files.\n'
        'See http://www.chromium.org/developers/coding-style#TOC-File-headers',
        files)]
  return []


def _CheckNoTrinaryTrueFalse(input_api, output_api):
  """Checks to make sure we don't introduce use of foo ? true : false."""
  problems = []
  pattern = input_api.re.compile(r'\?\s*(true|false)\s*:\s*(true|false)')
  for f in input_api.AffectedFiles():
    if not f.LocalPath().endswith(('.cc', '.h', '.inl', '.m', '.mm')):
      continue

    for line_num, line in f.ChangedContents():
      if pattern.match(line):
        problems.append('    %s:%d' % (f.LocalPath(), line_num))

  if not problems:
    return []
  return [output_api.PresubmitPromptWarning(
      'Please consider avoiding the "? true : false" pattern if possible.\n' +
      '\n'.join(problems))]


def _CheckUnwantedDependencies(input_api, output_api):
  """Runs checkdeps on #include statements added in this
  change. Breaking - rules is an error, breaking ! rules is a
  warning.
  """
  # We need to wait until we have an input_api object and use this
  # roundabout construct to import checkdeps because this file is
  # eval-ed and thus doesn't have __file__.
  original_sys_path = sys.path
  try:
    sys.path = sys.path + [input_api.os_path.join(
        input_api.PresubmitLocalPath(), 'tools', 'checkdeps')]
    import checkdeps
    from cpp_checker import CppChecker
    from rules import Rule
  finally:
    # Restore sys.path to what it was before.
    sys.path = original_sys_path

  added_includes = []
  for f in input_api.AffectedFiles():
    if not CppChecker.IsCppFile(f.LocalPath()):
      continue

    changed_lines = [line for line_num, line in f.ChangedContents()]
    added_includes.append([f.LocalPath(), changed_lines])

  deps_checker = checkdeps.DepsChecker(input_api.PresubmitLocalPath())

  error_descriptions = []
  warning_descriptions = []
  for path, rule_type, rule_description in deps_checker.CheckAddedCppIncludes(
      added_includes):
    description_with_path = '%s\n    %s' % (path, rule_description)
    if rule_type == Rule.DISALLOW:
      error_descriptions.append(description_with_path)
    else:
      warning_descriptions.append(description_with_path)

  results = []
  if error_descriptions:
    results.append(output_api.PresubmitError(
        'You added one or more #includes that violate checkdeps rules.',
        error_descriptions))
  if warning_descriptions:
    results.append(output_api.PresubmitPromptOrNotify(
        'You added one or more #includes of files that are temporarily\n'
        'allowed but being removed. Can you avoid introducing the\n'
        '#include? See relevant DEPS file(s) for details and contacts.',
        warning_descriptions))
  return results


def _CheckFilePermissions(input_api, output_api):
  """Check that all files have their permissions properly set."""
  args = [sys.executable, 'tools/checkperms/checkperms.py', '--root',
          input_api.change.RepositoryRoot()]
  for f in input_api.AffectedFiles():
    args += ['--file', f.LocalPath()]
  errors = []
  (errors, stderrdata) = subprocess.Popen(args).communicate()

  results = []
  if errors:
    results.append(output_api.PresubmitError('checkperms.py failed.',
                                             errors))
  return results


def _CheckNoAuraWindowPropertyHInHeaders(input_api, output_api):
  """Makes sure we don't include ui/aura/window_property.h
  in header files.
  """
  pattern = input_api.re.compile(r'^#include\s*"ui/aura/window_property.h"')
  errors = []
  for f in input_api.AffectedFiles():
    if not f.LocalPath().endswith('.h'):
      continue
    for line_num, line in f.ChangedContents():
      if pattern.match(line):
        errors.append('    %s:%d' % (f.LocalPath(), line_num))

  results = []
  if errors:
    results.append(output_api.PresubmitError(
      'Header files should not include ui/aura/window_property.h', errors))
  return results


def _CheckIncludeOrderForScope(scope, input_api, file_path, changed_linenums):
  """Checks that the lines in scope occur in the right order.

  1. C system files in alphabetical order
  2. C++ system files in alphabetical order
  3. Project's .h files
  """

  c_system_include_pattern = input_api.re.compile(r'\s*#include <.*\.h>')
  cpp_system_include_pattern = input_api.re.compile(r'\s*#include <.*>')
  custom_include_pattern = input_api.re.compile(r'\s*#include ".*')

  C_SYSTEM_INCLUDES, CPP_SYSTEM_INCLUDES, CUSTOM_INCLUDES = range(3)

  state = C_SYSTEM_INCLUDES

  previous_line = ''
  previous_line_num = 0
  problem_linenums = []
  for line_num, line in scope:
    if c_system_include_pattern.match(line):
      if state != C_SYSTEM_INCLUDES:
        problem_linenums.append((line_num, previous_line_num))
      elif previous_line and previous_line > line:
        problem_linenums.append((line_num, previous_line_num))
    elif cpp_system_include_pattern.match(line):
      if state == C_SYSTEM_INCLUDES:
        state = CPP_SYSTEM_INCLUDES
      elif state == CUSTOM_INCLUDES:
        problem_linenums.append((line_num, previous_line_num))
      elif previous_line and previous_line > line:
        problem_linenums.append((line_num, previous_line_num))
    elif custom_include_pattern.match(line):
      if state != CUSTOM_INCLUDES:
        state = CUSTOM_INCLUDES
      elif previous_line and previous_line > line:
        problem_linenums.append((line_num, previous_line_num))
    else:
      problem_linenums.append(line_num)
    previous_line = line
    previous_line_num = line_num

  warnings = []
  for (line_num, previous_line_num) in problem_linenums:
    if line_num in changed_linenums or previous_line_num in changed_linenums:
      warnings.append('    %s:%d' % (file_path, line_num))
  return warnings


def _CheckIncludeOrderInFile(input_api, f, changed_linenums):
  """Checks the #include order for the given file f."""

  system_include_pattern = input_api.re.compile(r'\s*#include \<.*')
  # Exclude #include <.../...> includes from the check; e.g., <sys/...> includes
  # often need to appear in a specific order.
  excluded_include_pattern = input_api.re.compile(r'\s*#include \<.*/.*')
  custom_include_pattern = input_api.re.compile(r'\s*#include "(?P<FILE>.*)"')
  if_pattern = input_api.re.compile(
      r'\s*#\s*(if|elif|else|endif|define|undef).*')
  # Some files need specialized order of includes; exclude such files from this
  # check.
  uncheckable_includes_pattern = input_api.re.compile(
      r'\s*#include '
      '("ipc/.*macros\.h"|<windows\.h>|".*gl.*autogen.h")\s*')

  contents = f.NewContents()
  warnings = []
  line_num = 0

  # Handle the special first include. If the first include file is
  # some/path/file.h, the corresponding including file can be some/path/file.cc,
  # some/other/path/file.cc, some/path/file_platform.cc, some/path/file-suffix.h
  # etc. It's also possible that no special first include exists.
  for line in contents:
    line_num += 1
    if system_include_pattern.match(line):
      # No special first include -> process the line again along with normal
      # includes.
      line_num -= 1
      break
    match = custom_include_pattern.match(line)
    if match:
      match_dict = match.groupdict()
      header_basename = input_api.os_path.basename(
          match_dict['FILE']).replace('.h', '')
      if header_basename not in input_api.os_path.basename(f.LocalPath()):
        # No special first include -> process the line again along with normal
        # includes.
        line_num -= 1
      break

  # Split into scopes: Each region between #if and #endif is its own scope.
  scopes = []
  current_scope = []
  for line in contents[line_num:]:
    line_num += 1
    if uncheckable_includes_pattern.match(line):
      return []
    if if_pattern.match(line):
      scopes.append(current_scope)
      current_scope = []
    elif ((system_include_pattern.match(line) or
           custom_include_pattern.match(line)) and
          not excluded_include_pattern.match(line)):
      current_scope.append((line_num, line))
  scopes.append(current_scope)

  for scope in scopes:
    warnings.extend(_CheckIncludeOrderForScope(scope, input_api, f.LocalPath(),
                                               changed_linenums))
  return warnings


def _CheckIncludeOrder(input_api, output_api):
  """Checks that the #include order is correct.

  1. The corresponding header for source files.
  2. C system files in alphabetical order
  3. C++ system files in alphabetical order
  4. Project's .h files in alphabetical order

  Each region separated by #if, #elif, #else, #endif, #define and #undef follows
  these rules separately.
  """

  warnings = []
  for f in input_api.AffectedFiles():
    if f.LocalPath().endswith(('.cc', '.h')):
      changed_linenums = set(line_num for line_num, _ in f.ChangedContents())
      warnings.extend(_CheckIncludeOrderInFile(input_api, f, changed_linenums))

  results = []
  if warnings:
    results.append(output_api.PresubmitPromptOrNotify(_INCLUDE_ORDER_WARNING,
                                                      warnings))
  return results


def _CheckForVersionControlConflictsInFile(input_api, f):
  pattern = input_api.re.compile('^(?:<<<<<<<|>>>>>>>) |^=======$')
  errors = []
  for line_num, line in f.ChangedContents():
    if pattern.match(line):
      errors.append('    %s:%d %s' % (f.LocalPath(), line_num, line))
  return errors


def _CheckForVersionControlConflicts(input_api, output_api):
  """Usually this is not intentional and will cause a compile failure."""
  errors = []
  for f in input_api.AffectedFiles():
    errors.extend(_CheckForVersionControlConflictsInFile(input_api, f))

  results = []
  if errors:
    results.append(output_api.PresubmitError(
      'Version control conflict markers found, please resolve.', errors))
  return results


def _CheckHardcodedGoogleHostsInLowerLayers(input_api, output_api):
  def FilterFile(affected_file):
    """Filter function for use with input_api.AffectedSourceFiles,
    below.  This filters out everything except non-test files from
    top-level directories that generally speaking should not hard-code
    service URLs (e.g. src/android_webview/, src/content/ and others).
    """
    return input_api.FilterSourceFile(
      affected_file,
      white_list=(r'^(android_webview|base|content|net)[\\\/].*', ),
      black_list=(_EXCLUDED_PATHS +
                  _TEST_CODE_EXCLUDED_PATHS +
                  input_api.DEFAULT_BLACK_LIST))

  pattern = input_api.re.compile('"[^"]*google\.com[^"]*"')
  problems = []  # items are (filename, line_number, line)
  for f in input_api.AffectedSourceFiles(FilterFile):
    for line_num, line in f.ChangedContents():
      if pattern.search(line):
        problems.append((f.LocalPath(), line_num, line))

  if problems:
    return [output_api.PresubmitPromptOrNotify(
        'Most layers below src/chrome/ should not hardcode service URLs.\n'
        'Are you sure this is correct? (Contact: joi@chromium.org)',
        ['  %s:%d:  %s' % (
            problem[0], problem[1], problem[2]) for problem in problems])]
  else:
    return []


def _CheckNoAbbreviationInPngFileName(input_api, output_api):
  """Makes sure there are no abbreviations in the name of PNG files.
  """
  pattern = input_api.re.compile(r'.*_[a-z]_.*\.png$|.*_[a-z]\.png$')
  errors = []
  for f in input_api.AffectedFiles(include_deletes=False):
    if pattern.match(f.LocalPath()):
      errors.append('    %s' % f.LocalPath())

  results = []
  if errors:
    results.append(output_api.PresubmitError(
        'The name of PNG files should not have abbreviations. \n'
        'Use _hover.png, _center.png, instead of _h.png, _c.png.\n'
        'Contact oshima@chromium.org if you have questions.', errors))
  return results


def _CheckAddedDepsHaveTargetApprovals(input_api, output_api):
  """When a dependency prefixed with + is added to a DEPS file, we
  want to make sure that the change is reviewed by an OWNER of the
  target file or directory, to avoid layering violations from being
  introduced. This check verifies that this happens.
  """
  changed_lines = set()
  for f in input_api.AffectedFiles():
    filename = input_api.os_path.basename(f.LocalPath())
    if filename == 'DEPS':
      changed_lines |= set(line.strip()
                           for line_num, line
                           in f.ChangedContents())
  if not changed_lines:
    return []

  virtual_depended_on_files = set()
  # This pattern grabs the path without basename in the first
  # parentheses, and the basename (if present) in the second. It
  # relies on the simple heuristic that if there is a basename it will
  # be a header file ending in ".h".
  pattern = input_api.re.compile(
      r"""['"]\+([^'"]+?)(/[a-zA-Z0-9_]+\.h)?['"].*""")
  for changed_line in changed_lines:
    m = pattern.match(changed_line)
    if m:
      virtual_depended_on_files.add('%s/DEPS' % m.group(1))

  if not virtual_depended_on_files:
    return []

  if input_api.is_committing:
    if input_api.tbr:
      return [output_api.PresubmitNotifyResult(
          '--tbr was specified, skipping OWNERS check for DEPS additions')]
    if not input_api.change.issue:
      return [output_api.PresubmitError(
          "DEPS approval by OWNERS check failed: this change has "
          "no Rietveld issue number, so we can't check it for approvals.")]
    output = output_api.PresubmitError
  else:
    output = output_api.PresubmitNotifyResult

  owners_db = input_api.owners_db
  owner_email, reviewers = input_api.canned_checks._RietveldOwnerAndReviewers(
      input_api,
      owners_db.email_regexp,
      approval_needed=input_api.is_committing)

  owner_email = owner_email or input_api.change.author_email

  reviewers_plus_owner = set([owner_email]).union(reviewers)
  missing_files = owners_db.files_not_covered_by(virtual_depended_on_files,
                                                 reviewers_plus_owner)
  unapproved_dependencies = ["'+%s'," % path[:-len('/DEPS')]
                             for path in missing_files]

  if unapproved_dependencies:
    output_list = [
      output('Missing LGTM from OWNERS of directories added to DEPS:\n    %s' %
             '\n    '.join(sorted(unapproved_dependencies)))]
    if not input_api.is_committing:
      suggested_owners = owners_db.reviewers_for(missing_files, owner_email)
      output_list.append(output(
          'Suggested missing target path OWNERS:\n    %s' %
          '\n    '.join(suggested_owners or [])))
    return output_list

  return []


def _CommonChecks(input_api, output_api):
  """Checks common to both upload and commit."""
  results = []
  results.extend(input_api.canned_checks.PanProjectChecks(
      input_api, output_api, excluded_paths=_EXCLUDED_PATHS))
  results.extend(_CheckAuthorizedAuthor(input_api, output_api))
  results.extend(
    _CheckNoProductionCodeUsingTestOnlyFunctions(input_api, output_api))
  results.extend(_CheckNoIOStreamInHeaders(input_api, output_api))
  results.extend(_CheckNoUNIT_TESTInSourceFiles(input_api, output_api))
  results.extend(_CheckNoNewWStrings(input_api, output_api))
  results.extend(_CheckNoDEPSGIT(input_api, output_api))
  results.extend(_CheckNoBannedFunctions(input_api, output_api))
  results.extend(_CheckNoPragmaOnce(input_api, output_api))
  results.extend(_CheckNoTrinaryTrueFalse(input_api, output_api))
  results.extend(_CheckUnwantedDependencies(input_api, output_api))
  results.extend(_CheckFilePermissions(input_api, output_api))
  results.extend(_CheckNoAuraWindowPropertyHInHeaders(input_api, output_api))
  results.extend(_CheckIncludeOrder(input_api, output_api))
  results.extend(_CheckForVersionControlConflicts(input_api, output_api))
  results.extend(_CheckPatchFiles(input_api, output_api))
  results.extend(_CheckHardcodedGoogleHostsInLowerLayers(input_api, output_api))
  results.extend(_CheckNoAbbreviationInPngFileName(input_api, output_api))
  results.extend(_CheckForInvalidOSMacros(input_api, output_api))
  results.extend(_CheckAddedDepsHaveTargetApprovals(input_api, output_api))

  if any('PRESUBMIT.py' == f.LocalPath() for f in input_api.AffectedFiles()):
    results.extend(input_api.canned_checks.RunUnitTestsInDirectory(
        input_api, output_api,
        input_api.PresubmitLocalPath(),
        whitelist=[r'^PRESUBMIT_test\.py$']))
  return results


def _CheckSubversionConfig(input_api, output_api):
  """Verifies the subversion config file is correctly setup.

  Checks that autoprops are enabled, returns an error otherwise.
  """
  join = input_api.os_path.join
  if input_api.platform == 'win32':
    appdata = input_api.environ.get('APPDATA', '')
    if not appdata:
      return [output_api.PresubmitError('%APPDATA% is not configured.')]
    path = join(appdata, 'Subversion', 'config')
  else:
    home = input_api.environ.get('HOME', '')
    if not home:
      return [output_api.PresubmitError('$HOME is not configured.')]
    path = join(home, '.subversion', 'config')

  error_msg = (
      'Please look at http://dev.chromium.org/developers/coding-style to\n'
      'configure your subversion configuration file. This enables automatic\n'
      'properties to simplify the project maintenance.\n'
      'Pro-tip: just download and install\n'
      'http://src.chromium.org/viewvc/chrome/trunk/tools/build/slave/config\n')

  try:
    lines = open(path, 'r').read().splitlines()
    # Make sure auto-props is enabled and check for 2 Chromium standard
    # auto-prop.
    if (not '*.cc = svn:eol-style=LF' in lines or
        not '*.pdf = svn:mime-type=application/pdf' in lines or
        not 'enable-auto-props = yes' in lines):
      return [
          output_api.PresubmitNotifyResult(
              'It looks like you have not configured your subversion config '
              'file or it is not up-to-date.\n' + error_msg)
      ]
  except (OSError, IOError):
    return [
        output_api.PresubmitNotifyResult(
            'Can\'t find your subversion config file.\n' + error_msg)
    ]
  return []


def _CheckAuthorizedAuthor(input_api, output_api):
  """For non-googler/chromites committers, verify the author's email address is
  in AUTHORS.
  """
  # TODO(maruel): Add it to input_api?
  import fnmatch

  author = input_api.change.author_email
  if not author:
    input_api.logging.info('No author, skipping AUTHOR check')
    return []
  authors_path = input_api.os_path.join(
      input_api.PresubmitLocalPath(), 'AUTHORS')
  valid_authors = (
      input_api.re.match(r'[^#]+\s+\<(.+?)\>\s*$', line)
      for line in open(authors_path))
  valid_authors = [item.group(1).lower() for item in valid_authors if item]
  if not any(fnmatch.fnmatch(author.lower(), valid) for valid in valid_authors):
    input_api.logging.info('Valid authors are %s', ', '.join(valid_authors))
    return [output_api.PresubmitPromptWarning(
        ('%s is not in AUTHORS file. If you are a new contributor, please visit'
        '\n'
        'http://www.chromium.org/developers/contributing-code and read the '
        '"Legal" section\n'
        'If you are a chromite, verify the contributor signed the CLA.') %
        author)]
  return []


def _CheckPatchFiles(input_api, output_api):
  problems = [f.LocalPath() for f in input_api.AffectedFiles()
      if f.LocalPath().endswith(('.orig', '.rej'))]
  if problems:
    return [output_api.PresubmitError(
        "Don't commit .rej and .orig files.", problems)]
  else:
    return []


def _DidYouMeanOSMacro(bad_macro):
  try:
    return {'A': 'OS_ANDROID',
            'B': 'OS_BSD',
            'C': 'OS_CHROMEOS',
            'F': 'OS_FREEBSD',
            'L': 'OS_LINUX',
            'M': 'OS_MACOSX',
            'N': 'OS_NACL',
            'O': 'OS_OPENBSD',
            'P': 'OS_POSIX',
            'S': 'OS_SOLARIS',
            'W': 'OS_WIN'}[bad_macro[3].upper()]
  except KeyError:
    return ''


def _CheckForInvalidOSMacrosInFile(input_api, f):
  """Check for sensible looking, totally invalid OS macros."""
  preprocessor_statement = input_api.re.compile(r'^\s*#')
  os_macro = input_api.re.compile(r'defined\((OS_[^)]+)\)')
  results = []
  for lnum, line in f.ChangedContents():
    if preprocessor_statement.search(line):
      for match in os_macro.finditer(line):
        if not match.group(1) in _VALID_OS_MACROS:
          good = _DidYouMeanOSMacro(match.group(1))
          did_you_mean = ' (did you mean %s?)' % good if good else ''
          results.append('    %s:%d %s%s' % (f.LocalPath(),
                                             lnum,
                                             match.group(1),
                                             did_you_mean))
  return results


def _CheckForInvalidOSMacros(input_api, output_api):
  """Check all affected files for invalid OS macros."""
  bad_macros = []
  for f in input_api.AffectedFiles():
    if not f.LocalPath().endswith(('.py', '.js', '.html', '.css')):
      bad_macros.extend(_CheckForInvalidOSMacrosInFile(input_api, f))

  if not bad_macros:
    return []

  return [output_api.PresubmitError(
      'Possibly invalid OS macro[s] found. Please fix your code\n'
      'or add your macro to src/PRESUBMIT.py.', bad_macros)]


def CheckChangeOnUpload(input_api, output_api):
  results = []
  results.extend(_CommonChecks(input_api, output_api))
  return results


def CheckChangeOnCommit(input_api, output_api):
  results = []
  results.extend(_CommonChecks(input_api, output_api))
  # TODO(thestig) temporarily disabled, doesn't work in third_party/
  #results.extend(input_api.canned_checks.CheckSvnModifiedDirectories(
  #    input_api, output_api, sources))
  # Make sure the tree is 'open'.
  results.extend(input_api.canned_checks.CheckTreeIsOpen(
      input_api,
      output_api,
      json_url='http://chromium-status.appspot.com/current?format=json'))
  results.extend(input_api.canned_checks.CheckRietveldTryJobExecution(input_api,
      output_api, 'http://codereview.chromium.org',
      ('win_rel', 'linux_rel', 'mac_rel, win:compile'),
      'tryserver@chromium.org'))

  results.extend(input_api.canned_checks.CheckChangeHasBugField(
      input_api, output_api))
  results.extend(input_api.canned_checks.CheckChangeHasDescription(
      input_api, output_api))
  results.extend(_CheckSubversionConfig(input_api, output_api))
  return results


def GetPreferredTrySlaves(project, change):
  files = change.LocalPaths()

  if not files or all(re.search(r'[\\/]OWNERS$', f) for f in files):
    return []

  if all(re.search('\.(m|mm)$|(^|[/_])mac[/_.]', f) for f in files):
    return ['mac_rel', 'mac_asan', 'mac:compile']
  if all(re.search('(^|[/_])win[/_.]', f) for f in files):
    return ['win_rel', 'win7_aura', 'win:compile']
  if all(re.search('(^|[/_])android[/_.]', f) for f in files):
    return ['android_dbg', 'android_clang_dbg']
  if all(re.search('^native_client_sdk', f) for f in files):
    return ['linux_nacl_sdk', 'win_nacl_sdk', 'mac_nacl_sdk']
  if all(re.search('[/_]ios[/_.]', f) for f in files):
    return ['ios_rel_device', 'ios_dbg_simulator']

  trybots = [
      'android_clang_dbg',
      'android_dbg',
      'ios_dbg_simulator',
      'ios_rel_device',
      'linux_asan',
      'linux_aura',
      'linux_chromeos',
      'linux_clang:compile',
      'linux_rel',
      'mac_asan',
      'mac_rel',
      'mac:compile',
      'win7_aura',
      'win_rel',
      'win:compile',
  ]

  # Match things like path/aura/file.cc and path/file_aura.cc.
  # Same for chromeos.
  if any(re.search('[/_](aura|chromeos)', f) for f in files):
    trybots += ['linux_chromeos_clang:compile', 'linux_chromeos_asan']

  return trybots