PRESUBMIT.py - platform/external/skia - Gitiles

 # Copyright (c) 2013 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 Skia.

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

 import collections
 import csv
 import fnmatch
 import os
 import re
 import subprocess
 import sys
 import traceback


 REVERT_CL_SUBJECT_PREFIX = 'Revert '

 # Please add the complete email address here (and not just 'xyz@' or 'xyz').
 PUBLIC_API_OWNERS = (
     'mtklein@google.com',
     'reed@chromium.org',
     'reed@google.com',
     'bsalomon@chromium.org',
     'bsalomon@google.com',
     'djsollen@chromium.org',
     'djsollen@google.com',
     'hcm@chromium.org',
     'hcm@google.com',
 )

 AUTHORS_FILE_NAME = 'AUTHORS'
 RELEASE_NOTES_FILE_NAME = 'RELEASE_NOTES.txt'

 DOCS_PREVIEW_URL = 'https://skia.org/?cl={issue}'
 GOLD_TRYBOT_URL = 'https://gold.skia.org/search?issue='

 SERVICE_ACCOUNT_SUFFIX = [
     '@%s.iam.gserviceaccount.com' % project for project in [
         'skia-buildbots.google.com', 'skia-swarming-bots', 'skia-public',
         'skia-corp.google.com', 'chops-service-accounts']]


 def _CheckChangeHasEol(input_api, output_api, source_file_filter=None):
   """Checks that files end with at least one \n (LF)."""
   eof_files = []
   for f in input_api.AffectedSourceFiles(source_file_filter):
     contents = input_api.ReadFile(f, 'rb')
     # Check that the file ends in at least one newline character.
     if len(contents) > 1 and contents[-1:] != '\n':
       eof_files.append(f.LocalPath())

   if eof_files:
     return [output_api.PresubmitPromptWarning(
       'These files should end in a newline character:',
       items=eof_files)]
   return []


 def _JsonChecks(input_api, output_api):
   """Run checks on any modified json files."""
   failing_files = []
   for affected_file in input_api.AffectedFiles(None):
     affected_file_path = affected_file.LocalPath()
     is_json = affected_file_path.endswith('.json')
     is_metadata = (affected_file_path.startswith('site/') and
                    affected_file_path.endswith('/METADATA'))
     if is_json or is_metadata:
       try:
         input_api.json.load(open(affected_file_path, 'r'))
       except ValueError:
         failing_files.append(affected_file_path)

   results = []
   if failing_files:
     results.append(
         output_api.PresubmitError(
             'The following files contain invalid json:\n%s\n\n' %
                 '\n'.join(failing_files)))
   return results


 def _IfDefChecks(input_api, output_api):
   """Ensures if/ifdef are not before includes. See skbug/3362 for details."""
   comment_block_start_pattern = re.compile('^\s*\/\*.*$')
   comment_block_middle_pattern = re.compile('^\s+\*.*')
   comment_block_end_pattern = re.compile('^\s+\*\/.*$')
   single_line_comment_pattern = re.compile('^\s*//.*$')
   def is_comment(line):
     return (comment_block_start_pattern.match(line) or
             comment_block_middle_pattern.match(line) or
             comment_block_end_pattern.match(line) or
             single_line_comment_pattern.match(line))

   empty_line_pattern = re.compile('^\s*$')
   def is_empty_line(line):
     return empty_line_pattern.match(line)

   failing_files = []
   for affected_file in input_api.AffectedSourceFiles(None):
     affected_file_path = affected_file.LocalPath()
     if affected_file_path.endswith('.cpp') or affected_file_path.endswith('.h'):
       f = open(affected_file_path)
       for line in f.xreadlines():
         if is_comment(line) or is_empty_line(line):
           continue
         # The below will be the first real line after comments and newlines.
         if line.startswith('#if 0 '):
           pass
         elif line.startswith('#if ') or line.startswith('#ifdef '):
           failing_files.append(affected_file_path)
         break

   results = []
   if failing_files:
     results.append(
         output_api.PresubmitError(
             'The following files have #if or #ifdef before includes:\n%s\n\n'
             'See https://bug.skia.org/3362 for why this should be fixed.' %
                 '\n'.join(failing_files)))
   return results


 def _CopyrightChecks(input_api, output_api, source_file_filter=None):
   results = []
   year_pattern = r'\d{4}'
   year_range_pattern = r'%s(-%s)?' % (year_pattern, year_pattern)
   years_pattern = r'%s(,%s)*,?' % (year_range_pattern, year_range_pattern)
   copyright_pattern = (
       r'Copyright (\([cC]\) )?%s \w+' % years_pattern)

   for affected_file in input_api.AffectedSourceFiles(source_file_filter):
     if 'third_party' in affected_file.LocalPath():
       continue
     contents = input_api.ReadFile(affected_file, 'rb')
     if not re.search(copyright_pattern, contents):
       results.append(output_api.PresubmitError(
           '%s is missing a correct copyright header.' % affected_file))
   return results


 def _InfraTests(input_api, output_api):
   """Run the infra tests."""
   results = []
   if not any(f.LocalPath().startswith('infra')
              for f in input_api.AffectedFiles()):
     return results

   cmd = ['python', os.path.join('infra', 'bots', 'infra_tests.py')]
   try:
     subprocess.check_output(cmd)
   except subprocess.CalledProcessError as e:
     results.append(output_api.PresubmitError(
         '`%s` failed:\n%s' % (' '.join(cmd), e.output)))
   return results


 def _CheckGNFormatted(input_api, output_api):
   """Make sure any .gn files we're changing have been formatted."""
   files = []
   for f in input_api.AffectedFiles():
     if (f.LocalPath().endswith('.gn') or
         f.LocalPath().endswith('.gni')):
       files.append(f)
   if not files:
     return []

   cmd = ['python', os.path.join('bin', 'fetch-gn')]
   try:
     subprocess.check_output(cmd)
   except subprocess.CalledProcessError as e:
     return [output_api.PresubmitError(
         '`%s` failed:\n%s' % (' '.join(cmd), e.output))]

   results = []
   for f in files:
     gn = 'gn.exe' if 'win32' in sys.platform else 'gn'
     gn = os.path.join(input_api.PresubmitLocalPath(), 'bin', gn)
     cmd = [gn, 'format', '--dry-run', f.LocalPath()]
     try:
       subprocess.check_output(cmd)
     except subprocess.CalledProcessError:
       fix = 'bin/gn format ' + f.LocalPath()
       results.append(output_api.PresubmitError(
           '`%s` failed, try\n\t%s' % (' '.join(cmd), fix)))
   return results

 def _CheckIncludesFormatted(input_api, output_api):
   """Make sure #includes in files we're changing have been formatted."""
   files = [str(f) for f in input_api.AffectedFiles() if f.Action() != 'D']
   cmd = ['python',
          'tools/rewrite_includes.py',
          '--dry-run'] + files
   if 0 != subprocess.call(cmd):
     return [output_api.PresubmitError('`%s` failed' % ' '.join(cmd))]
   return []

 def _CheckCompileIsolate(input_api, output_api):
   """Ensure that gen_compile_isolate.py does not change compile.isolate."""
   # Only run the check if files were added or removed.
   results = []
   script = os.path.join('infra', 'bots', 'gen_compile_isolate.py')
   isolate = os.path.join('infra', 'bots', 'compile.isolated')
   for f in input_api.AffectedFiles():
     if f.Action() in ('A', 'D', 'R'):
       break
     if f.LocalPath() in (script, isolate):
       break
   else:
     return results

   cmd = ['python', script, 'test']
   try:
     subprocess.check_output(cmd, stderr=subprocess.STDOUT)
   except subprocess.CalledProcessError as e:
     results.append(output_api.PresubmitError(e.output))
   return results


 class _WarningsAsErrors():
   def __init__(self, output_api):
     self.output_api = output_api
     self.old_warning = None
   def __enter__(self):
     self.old_warning = self.output_api.PresubmitPromptWarning
     self.output_api.PresubmitPromptWarning = self.output_api.PresubmitError
     return self.output_api
   def __exit__(self, ex_type, ex_value, ex_traceback):
     self.output_api.PresubmitPromptWarning = self.old_warning


 def _CheckDEPSValid(input_api, output_api):
   """Ensure that DEPS contains valid entries."""
   results = []
   script = os.path.join('infra', 'bots', 'check_deps.py')
   relevant_files = ('DEPS', script)
   for f in input_api.AffectedFiles():
     if f.LocalPath() in relevant_files:
       break
   else:
     return results
   cmd = ['python', script]
   try:
     subprocess.check_output(cmd, stderr=subprocess.STDOUT)
   except subprocess.CalledProcessError as e:
     results.append(output_api.PresubmitError(e.output))
   return results


 def _CommonChecks(input_api, output_api):
   """Presubmit checks common to upload and commit."""
   results = []
   sources = lambda x: (x.LocalPath().endswith('.h') or
                        x.LocalPath().endswith('.py') or
                        x.LocalPath().endswith('.sh') or
                        x.LocalPath().endswith('.m') or
                        x.LocalPath().endswith('.mm') or
                        x.LocalPath().endswith('.go') or
                        x.LocalPath().endswith('.c') or
                        x.LocalPath().endswith('.cc') or
                        x.LocalPath().endswith('.cpp'))
   results.extend(_CheckChangeHasEol(
       input_api, output_api, source_file_filter=sources))
   with _WarningsAsErrors(output_api):
     results.extend(input_api.canned_checks.CheckChangeHasNoCR(
         input_api, output_api, source_file_filter=sources))
     results.extend(input_api.canned_checks.CheckChangeHasNoStrayWhitespace(
         input_api, output_api, source_file_filter=sources))
   results.extend(_JsonChecks(input_api, output_api))
   results.extend(_IfDefChecks(input_api, output_api))
   results.extend(_CopyrightChecks(input_api, output_api,
                                   source_file_filter=sources))
   results.extend(_CheckCompileIsolate(input_api, output_api))
   results.extend(_CheckDEPSValid(input_api, output_api))
   results.extend(_CheckIncludesFormatted(input_api, output_api))
   return results


 def CheckChangeOnUpload(input_api, output_api):
   """Presubmit checks for the change on upload.

   The following are the presubmit checks:
   * Check change has one and only one EOL.
   """
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   # Run on upload, not commit, since the presubmit bot apparently doesn't have
   # coverage or Go installed.
   results.extend(_InfraTests(input_api, output_api))

   results.extend(_CheckGNFormatted(input_api, output_api))
   results.extend(_CheckReleaseNotesForPublicAPI(input_api, output_api))
   return results


 class CodeReview(object):
   """Abstracts which codereview tool is used for the specified issue."""

   def __init__(self, input_api):
     self._issue = input_api.change.issue
     self._gerrit = input_api.gerrit

   def GetOwnerEmail(self):
     return self._gerrit.GetChangeOwner(self._issue)

   def GetSubject(self):
     return self._gerrit.GetChangeInfo(self._issue)['subject']

   def GetDescription(self):
     return self._gerrit.GetChangeDescription(self._issue)

   def GetReviewers(self):
     code_review_label = (
         self._gerrit.GetChangeInfo(self._issue)['labels']['Code-Review'])
     return [r['email'] for r in code_review_label.get('all', [])]

   def GetApprovers(self):
     approvers = []
     code_review_label = (
         self._gerrit.GetChangeInfo(self._issue)['labels']['Code-Review'])
     for m in code_review_label.get('all', []):
       if m.get("value") == 1:
         approvers.append(m["email"])
     return approvers


 def _CheckOwnerIsInAuthorsFile(input_api, output_api):
   results = []
   if input_api.change.issue:
     cr = CodeReview(input_api)

     owner_email = cr.GetOwnerEmail()

     # Service accounts don't need to be in AUTHORS.
     for suffix in SERVICE_ACCOUNT_SUFFIX:
       if owner_email.endswith(suffix):
         return results

     try:
       authors_content = ''
       for line in open(AUTHORS_FILE_NAME):
         if not line.startswith('#'):
           authors_content += line
       email_fnmatches = re.findall('<(.*)>', authors_content)
       for email_fnmatch in email_fnmatches:
         if fnmatch.fnmatch(owner_email, email_fnmatch):
           # Found a match, the user is in the AUTHORS file break out of the loop
           break
       else:
         results.append(
           output_api.PresubmitError(
             'The email %s is not in Skia\'s AUTHORS file.\n'
             'Issue owner, this CL must include an addition to the Skia AUTHORS '
             'file.'
             % owner_email))
     except IOError:
       # Do not fail if authors file cannot be found.
       traceback.print_exc()
       input_api.logging.error('AUTHORS file not found!')

   return results


 def _CheckReleaseNotesForPublicAPI(input_api, output_api):
   """Checks to see if release notes file is updated with public API changes."""
   results = []
   public_api_changed = False
   release_file_changed = False
   for affected_file in input_api.AffectedFiles():
     affected_file_path = affected_file.LocalPath()
     file_path, file_ext = os.path.splitext(affected_file_path)
     # We only care about files that end in .h and are under the top-level
     # include dir, but not include/private.
     if (file_ext == '.h' and
         file_path.split(os.path.sep)[0] == 'include' and
         'private' not in file_path):
       public_api_changed = True
     elif affected_file_path == RELEASE_NOTES_FILE_NAME:
       release_file_changed = True

   if public_api_changed and not release_file_changed:
     results.append(output_api.PresubmitPromptWarning(
         'If this change affects a client API, please add a summary line '
         'to the %s file.' % RELEASE_NOTES_FILE_NAME))
   return results


 def _CheckLGTMsForPublicAPI(input_api, output_api):
   """Check LGTMs for public API changes.

   For public API files make sure there is an LGTM from the list of owners in
   PUBLIC_API_OWNERS.
   """
   results = []
   requires_owner_check = False
   for affected_file in input_api.AffectedFiles():
     affected_file_path = affected_file.LocalPath()
     file_path, file_ext = os.path.splitext(affected_file_path)
     # We only care about files that end in .h and are under the top-level
     # include dir, but not include/private.
     if (file_ext == '.h' and
         'include' == file_path.split(os.path.sep)[0] and
         'private' not in file_path):
       requires_owner_check = True

   if not requires_owner_check:
     return results

   lgtm_from_owner = False
   if input_api.change.issue:
     cr = CodeReview(input_api)

     if re.match(REVERT_CL_SUBJECT_PREFIX, cr.GetSubject(), re.I):
       # It is a revert CL, ignore the public api owners check.
       return results

     if input_api.gerrit:
       for reviewer in cr.GetReviewers():
         if reviewer in PUBLIC_API_OWNERS:
           # If an owner is specified as an reviewer in Gerrit then ignore the
           # public api owners check.
           return results
     else:
       match = re.search(r'^TBR=(.*)$', cr.GetDescription(), re.M)
       if match:
         tbr_section = match.group(1).strip().split(' ')[0]
         tbr_entries = tbr_section.split(',')
         for owner in PUBLIC_API_OWNERS:
           if owner in tbr_entries or owner.split('@')[0] in tbr_entries:
             # If an owner is specified in the TBR= line then ignore the public
             # api owners check.
             return results

     if cr.GetOwnerEmail() in PUBLIC_API_OWNERS:
       # An owner created the CL that is an automatic LGTM.
       lgtm_from_owner = True

     for approver in cr.GetApprovers():
       if approver in PUBLIC_API_OWNERS:
         # Found an lgtm in a message from an owner.
         lgtm_from_owner = True
         break

   if not lgtm_from_owner:
     results.append(
         output_api.PresubmitError(
             "If this CL adds to or changes Skia's public API, you need an LGTM "
             "from any of %s.  If this CL only removes from or doesn't change "
             "Skia's public API, please add a short note to the CL saying so. "
             "Add one of the owners as a reviewer to your CL as well as to the "
             "TBR= line.  If you don't know if this CL affects Skia's public "
             "API, treat it like it does." % str(PUBLIC_API_OWNERS)))
   return results


 def PostUploadHook(gerrit, change, output_api):
   """git cl upload will call this hook after the issue is created/modified.

   This hook does the following:
   * Adds a link to preview docs changes if there are any docs changes in the CL.
   * Adds 'No-Try: true' if the CL contains only docs changes.
   """
   if not change.issue:
     return []

   # Skip PostUploadHooks for all auto-commit service account bots. New
   # patchsets (caused due to PostUploadHooks) invalidates the CQ+2 vote from
   # the "--use-commit-queue" flag to "git cl upload".
   for suffix in SERVICE_ACCOUNT_SUFFIX:
     if change.author_email.endswith(suffix):
       return []

   results = []
   at_least_one_docs_change = False
   all_docs_changes = True
   for affected_file in change.AffectedFiles():
     affected_file_path = affected_file.LocalPath()
     file_path, _ = os.path.splitext(affected_file_path)
     if 'site' == file_path.split(os.path.sep)[0]:
       at_least_one_docs_change = True
     else:
       all_docs_changes = False
     if at_least_one_docs_change and not all_docs_changes:
       break

   footers = change.GitFootersFromDescription()
   description_changed = False

   # If the change includes only doc changes then add No-Try: true in the
   # CL's description if it does not exist yet.
   if all_docs_changes and 'true' not in footers.get('No-Try', []):
     description_changed = True
     change.AddDescriptionFooter('No-Try', 'true')
     results.append(
         output_api.PresubmitNotifyResult(
             'This change has only doc changes. Automatically added '
             '\'No-Try: true\' to the CL\'s description'))

   # If there is at least one docs change then add preview link in the CL's
   # description if it does not already exist there.
   docs_preview_link = DOCS_PREVIEW_URL.format(issue=change.issue)
   if (at_least_one_docs_change
       and docs_preview_link not in footers.get('Docs-Preview', [])):
     # Automatically add a link to where the docs can be previewed.
     description_changed = True
     change.AddDescriptionFooter('Docs-Preview', docs_preview_link)
     results.append(
         output_api.PresubmitNotifyResult(
             'Automatically added a link to preview the docs changes to the '
             'CL\'s description'))

   # If the description has changed update it.
   if description_changed:
     gerrit.UpdateDescription(
         change.FullDescriptionText(), change.issue)

   return results


 def CheckChangeOnCommit(input_api, output_api):
   """Presubmit checks for the change on commit.

   The following are the presubmit checks:
   * Check change has one and only one EOL.
   * Ensures that the Skia tree is open in
     http://skia-tree-status.appspot.com/. Shows a warning if it is in 'Caution'
     state and an error if it is in 'Closed' state.
   """
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(_CheckLGTMsForPublicAPI(input_api, output_api))
   results.extend(_CheckOwnerIsInAuthorsFile(input_api, output_api))
   # Checks for the presence of 'DO NOT''SUBMIT' in CL description and in
   # content of files.
   results.extend(
       input_api.canned_checks.CheckDoNotSubmit(input_api, output_api))
   return results
	# Copyright (c) 2013 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 Skia.

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

	import collections
	import csv
	import fnmatch
	import os
	import re
	import subprocess
	import sys
	import traceback


	REVERT_CL_SUBJECT_PREFIX = 'Revert '

	# Please add the complete email address here (and not just 'xyz@' or 'xyz').
	PUBLIC_API_OWNERS = (
	'mtklein@google.com',
	'reed@chromium.org',
	'reed@google.com',
	'bsalomon@chromium.org',
	'bsalomon@google.com',
	'djsollen@chromium.org',
	'djsollen@google.com',
	'hcm@chromium.org',
	'hcm@google.com',
	)

	AUTHORS_FILE_NAME = 'AUTHORS'
	RELEASE_NOTES_FILE_NAME = 'RELEASE_NOTES.txt'

	DOCS_PREVIEW_URL = 'https://skia.org/?cl={issue}'
	GOLD_TRYBOT_URL = 'https://gold.skia.org/search?issue='

	SERVICE_ACCOUNT_SUFFIX = [
	'@%s.iam.gserviceaccount.com' % project for project in [
	'skia-buildbots.google.com', 'skia-swarming-bots', 'skia-public',
	'skia-corp.google.com', 'chops-service-accounts']]


	def _CheckChangeHasEol(input_api, output_api, source_file_filter=None):
	"""Checks that files end with at least one \n (LF)."""
	eof_files = []
	for f in input_api.AffectedSourceFiles(source_file_filter):
	contents = input_api.ReadFile(f, 'rb')
	# Check that the file ends in at least one newline character.
	if len(contents) > 1 and contents[-1:] != '\n':
	eof_files.append(f.LocalPath())

	if eof_files:
	return [output_api.PresubmitPromptWarning(
	'These files should end in a newline character:',
	items=eof_files)]
	return []


	def _JsonChecks(input_api, output_api):
	"""Run checks on any modified json files."""
	failing_files = []
	for affected_file in input_api.AffectedFiles(None):
	affected_file_path = affected_file.LocalPath()
	is_json = affected_file_path.endswith('.json')
	is_metadata = (affected_file_path.startswith('site/') and
	affected_file_path.endswith('/METADATA'))
	if is_json or is_metadata:
	try:
	input_api.json.load(open(affected_file_path, 'r'))
	except ValueError:
	failing_files.append(affected_file_path)

	results = []
	if failing_files:
	results.append(
	output_api.PresubmitError(
	'The following files contain invalid json:\n%s\n\n' %
	'\n'.join(failing_files)))
	return results


	def _IfDefChecks(input_api, output_api):
	"""Ensures if/ifdef are not before includes. See skbug/3362 for details."""
	comment_block_start_pattern = re.compile('^\s\/\.*$')
	comment_block_middle_pattern = re.compile('^\s+\.')
	comment_block_end_pattern = re.compile('^\s+\\/.$')
	single_line_comment_pattern = re.compile('^\s//.$')
	def is_comment(line):
	return (comment_block_start_pattern.match(line) or
	comment_block_middle_pattern.match(line) or
	comment_block_end_pattern.match(line) or
	single_line_comment_pattern.match(line))

	empty_line_pattern = re.compile('^\s*$')
	def is_empty_line(line):
	return empty_line_pattern.match(line)

	failing_files = []
	for affected_file in input_api.AffectedSourceFiles(None):
	affected_file_path = affected_file.LocalPath()
	if affected_file_path.endswith('.cpp') or affected_file_path.endswith('.h'):
	f = open(affected_file_path)
	for line in f.xreadlines():
	if is_comment(line) or is_empty_line(line):
	continue
	# The below will be the first real line after comments and newlines.
	if line.startswith('#if 0 '):
	pass
	elif line.startswith('#if ') or line.startswith('#ifdef '):
	failing_files.append(affected_file_path)
	break

	results = []
	if failing_files:
	results.append(
	output_api.PresubmitError(
	'The following files have #if or #ifdef before includes:\n%s\n\n'
	'See https://bug.skia.org/3362 for why this should be fixed.' %
	'\n'.join(failing_files)))
	return results


	def _CopyrightChecks(input_api, output_api, source_file_filter=None):
	results = []
	year_pattern = r'\d{4}'
	year_range_pattern = r'%s(-%s)?' % (year_pattern, year_pattern)
	years_pattern = r'%s(,%s)*,?' % (year_range_pattern, year_range_pattern)
	copyright_pattern = (
	r'Copyright (\([cC]\) )?%s \w+' % years_pattern)

	for affected_file in input_api.AffectedSourceFiles(source_file_filter):
	if 'third_party' in affected_file.LocalPath():
	continue
	contents = input_api.ReadFile(affected_file, 'rb')
	if not re.search(copyright_pattern, contents):
	results.append(output_api.PresubmitError(
	'%s is missing a correct copyright header.' % affected_file))
	return results


	def _InfraTests(input_api, output_api):
	"""Run the infra tests."""
	results = []
	if not any(f.LocalPath().startswith('infra')
	for f in input_api.AffectedFiles()):
	return results

	cmd = ['python', os.path.join('infra', 'bots', 'infra_tests.py')]
	try:
	subprocess.check_output(cmd)
	except subprocess.CalledProcessError as e:
	results.append(output_api.PresubmitError(
	'`%s` failed:\n%s' % (' '.join(cmd), e.output)))
	return results


	def _CheckGNFormatted(input_api, output_api):
	"""Make sure any .gn files we're changing have been formatted."""
	files = []
	for f in input_api.AffectedFiles():
	if (f.LocalPath().endswith('.gn') or
	f.LocalPath().endswith('.gni')):
	files.append(f)
	if not files:
	return []

	cmd = ['python', os.path.join('bin', 'fetch-gn')]
	try:
	subprocess.check_output(cmd)
	except subprocess.CalledProcessError as e:
	return [output_api.PresubmitError(
	'`%s` failed:\n%s' % (' '.join(cmd), e.output))]

	results = []
	for f in files:
	gn = 'gn.exe' if 'win32' in sys.platform else 'gn'
	gn = os.path.join(input_api.PresubmitLocalPath(), 'bin', gn)
	cmd = [gn, 'format', '--dry-run', f.LocalPath()]
	try:
	subprocess.check_output(cmd)
	except subprocess.CalledProcessError:
	fix = 'bin/gn format ' + f.LocalPath()
	results.append(output_api.PresubmitError(
	'`%s` failed, try\n\t%s' % (' '.join(cmd), fix)))
	return results

	def _CheckIncludesFormatted(input_api, output_api):
	"""Make sure #includes in files we're changing have been formatted."""
	files = [str(f) for f in input_api.AffectedFiles() if f.Action() != 'D']
	cmd = ['python',
	'tools/rewrite_includes.py',
	'--dry-run'] + files
	if 0 != subprocess.call(cmd):
	return [output_api.PresubmitError('`%s` failed' % ' '.join(cmd))]
	return []

	def _CheckCompileIsolate(input_api, output_api):
	"""Ensure that gen_compile_isolate.py does not change compile.isolate."""
	# Only run the check if files were added or removed.
	results = []
	script = os.path.join('infra', 'bots', 'gen_compile_isolate.py')
	isolate = os.path.join('infra', 'bots', 'compile.isolated')
	for f in input_api.AffectedFiles():
	if f.Action() in ('A', 'D', 'R'):
	break
	if f.LocalPath() in (script, isolate):
	break
	else:
	return results

	cmd = ['python', script, 'test']
	try:
	subprocess.check_output(cmd, stderr=subprocess.STDOUT)
	except subprocess.CalledProcessError as e:
	results.append(output_api.PresubmitError(e.output))
	return results


	class _WarningsAsErrors():
	def __init__(self, output_api):
	self.output_api = output_api
	self.old_warning = None
	def __enter__(self):
	self.old_warning = self.output_api.PresubmitPromptWarning
	self.output_api.PresubmitPromptWarning = self.output_api.PresubmitError
	return self.output_api
	def __exit__(self, ex_type, ex_value, ex_traceback):
	self.output_api.PresubmitPromptWarning = self.old_warning


	def _CheckDEPSValid(input_api, output_api):
	"""Ensure that DEPS contains valid entries."""
	results = []
	script = os.path.join('infra', 'bots', 'check_deps.py')
	relevant_files = ('DEPS', script)
	for f in input_api.AffectedFiles():
	if f.LocalPath() in relevant_files:
	break
	else:
	return results
	cmd = ['python', script]
	try:
	subprocess.check_output(cmd, stderr=subprocess.STDOUT)
	except subprocess.CalledProcessError as e:
	results.append(output_api.PresubmitError(e.output))
	return results


	def _CommonChecks(input_api, output_api):
	"""Presubmit checks common to upload and commit."""
	results = []
	sources = lambda x: (x.LocalPath().endswith('.h') or
	x.LocalPath().endswith('.py') or
	x.LocalPath().endswith('.sh') or
	x.LocalPath().endswith('.m') or
	x.LocalPath().endswith('.mm') or
	x.LocalPath().endswith('.go') or
	x.LocalPath().endswith('.c') or
	x.LocalPath().endswith('.cc') or
	x.LocalPath().endswith('.cpp'))
	results.extend(_CheckChangeHasEol(
	input_api, output_api, source_file_filter=sources))
	with _WarningsAsErrors(output_api):
	results.extend(input_api.canned_checks.CheckChangeHasNoCR(
	input_api, output_api, source_file_filter=sources))
	results.extend(input_api.canned_checks.CheckChangeHasNoStrayWhitespace(
	input_api, output_api, source_file_filter=sources))
	results.extend(_JsonChecks(input_api, output_api))
	results.extend(_IfDefChecks(input_api, output_api))
	results.extend(_CopyrightChecks(input_api, output_api,
	source_file_filter=sources))
	results.extend(_CheckCompileIsolate(input_api, output_api))
	results.extend(_CheckDEPSValid(input_api, output_api))
	results.extend(_CheckIncludesFormatted(input_api, output_api))
	return results


	def CheckChangeOnUpload(input_api, output_api):
	"""Presubmit checks for the change on upload.

	The following are the presubmit checks:
	* Check change has one and only one EOL.
	"""
	results = []
	results.extend(_CommonChecks(input_api, output_api))
	# Run on upload, not commit, since the presubmit bot apparently doesn't have
	# coverage or Go installed.
	results.extend(_InfraTests(input_api, output_api))

	results.extend(_CheckGNFormatted(input_api, output_api))
	results.extend(_CheckReleaseNotesForPublicAPI(input_api, output_api))
	return results


	class CodeReview(object):
	"""Abstracts which codereview tool is used for the specified issue."""

	def __init__(self, input_api):
	self._issue = input_api.change.issue
	self._gerrit = input_api.gerrit

	def GetOwnerEmail(self):
	return self._gerrit.GetChangeOwner(self._issue)

	def GetSubject(self):
	return self._gerrit.GetChangeInfo(self._issue)['subject']

	def GetDescription(self):
	return self._gerrit.GetChangeDescription(self._issue)

	def GetReviewers(self):
	code_review_label = (
	self._gerrit.GetChangeInfo(self._issue)['labels']['Code-Review'])
	return [r['email'] for r in code_review_label.get('all', [])]

	def GetApprovers(self):
	approvers = []
	code_review_label = (
	self._gerrit.GetChangeInfo(self._issue)['labels']['Code-Review'])
	for m in code_review_label.get('all', []):
	if m.get("value") == 1:
	approvers.append(m["email"])
	return approvers


	def _CheckOwnerIsInAuthorsFile(input_api, output_api):
	results = []
	if input_api.change.issue:
	cr = CodeReview(input_api)

	owner_email = cr.GetOwnerEmail()

	# Service accounts don't need to be in AUTHORS.
	for suffix in SERVICE_ACCOUNT_SUFFIX:
	if owner_email.endswith(suffix):
	return results

	try:
	authors_content = ''
	for line in open(AUTHORS_FILE_NAME):
	if not line.startswith('#'):
	authors_content += line
	email_fnmatches = re.findall('<(.*)>', authors_content)
	for email_fnmatch in email_fnmatches:
	if fnmatch.fnmatch(owner_email, email_fnmatch):
	# Found a match, the user is in the AUTHORS file break out of the loop
	break
	else:
	results.append(
	output_api.PresubmitError(
	'The email %s is not in Skia\'s AUTHORS file.\n'
	'Issue owner, this CL must include an addition to the Skia AUTHORS '
	'file.'
	% owner_email))
	except IOError:
	# Do not fail if authors file cannot be found.
	traceback.print_exc()
	input_api.logging.error('AUTHORS file not found!')

	return results


	def _CheckReleaseNotesForPublicAPI(input_api, output_api):
	"""Checks to see if release notes file is updated with public API changes."""
	results = []
	public_api_changed = False
	release_file_changed = False
	for affected_file in input_api.AffectedFiles():
	affected_file_path = affected_file.LocalPath()
	file_path, file_ext = os.path.splitext(affected_file_path)
	# We only care about files that end in .h and are under the top-level
	# include dir, but not include/private.
	if (file_ext == '.h' and
	file_path.split(os.path.sep)[0] == 'include' and
	'private' not in file_path):
	public_api_changed = True
	elif affected_file_path == RELEASE_NOTES_FILE_NAME:
	release_file_changed = True

	if public_api_changed and not release_file_changed:
	results.append(output_api.PresubmitPromptWarning(
	'If this change affects a client API, please add a summary line '
	'to the %s file.' % RELEASE_NOTES_FILE_NAME))
	return results



	def _CheckLGTMsForPublicAPI(input_api, output_api):
	"""Check LGTMs for public API changes.

	For public API files make sure there is an LGTM from the list of owners in
	PUBLIC_API_OWNERS.
	"""
	results = []
	requires_owner_check = False
	for affected_file in input_api.AffectedFiles():
	affected_file_path = affected_file.LocalPath()
	file_path, file_ext = os.path.splitext(affected_file_path)
	# We only care about files that end in .h and are under the top-level
	# include dir, but not include/private.
	if (file_ext == '.h' and
	'include' == file_path.split(os.path.sep)[0] and
	'private' not in file_path):
	requires_owner_check = True

	if not requires_owner_check:
	return results

	lgtm_from_owner = False
	if input_api.change.issue:
	cr = CodeReview(input_api)

	if re.match(REVERT_CL_SUBJECT_PREFIX, cr.GetSubject(), re.I):
	# It is a revert CL, ignore the public api owners check.
	return results

	if input_api.gerrit:
	for reviewer in cr.GetReviewers():
	if reviewer in PUBLIC_API_OWNERS:
	# If an owner is specified as an reviewer in Gerrit then ignore the
	# public api owners check.
	return results
	else:
	match = re.search(r'^TBR=(.*)$', cr.GetDescription(), re.M)
	if match:
	tbr_section = match.group(1).strip().split(' ')[0]
	tbr_entries = tbr_section.split(',')
	for owner in PUBLIC_API_OWNERS:
	if owner in tbr_entries or owner.split('@')[0] in tbr_entries:
	# If an owner is specified in the TBR= line then ignore the public
	# api owners check.
	return results

	if cr.GetOwnerEmail() in PUBLIC_API_OWNERS:
	# An owner created the CL that is an automatic LGTM.
	lgtm_from_owner = True

	for approver in cr.GetApprovers():
	if approver in PUBLIC_API_OWNERS:
	# Found an lgtm in a message from an owner.
	lgtm_from_owner = True
	break

	if not lgtm_from_owner:
	results.append(
	output_api.PresubmitError(
	"If this CL adds to or changes Skia's public API, you need an LGTM "
	"from any of %s. If this CL only removes from or doesn't change "
	"Skia's public API, please add a short note to the CL saying so. "
	"Add one of the owners as a reviewer to your CL as well as to the "
	"TBR= line. If you don't know if this CL affects Skia's public "
	"API, treat it like it does." % str(PUBLIC_API_OWNERS)))
	return results


	def PostUploadHook(gerrit, change, output_api):
	"""git cl upload will call this hook after the issue is created/modified.

	This hook does the following:
	* Adds a link to preview docs changes if there are any docs changes in the CL.
	* Adds 'No-Try: true' if the CL contains only docs changes.
	"""
	if not change.issue:
	return []

	# Skip PostUploadHooks for all auto-commit service account bots. New
	# patchsets (caused due to PostUploadHooks) invalidates the CQ+2 vote from
	# the "--use-commit-queue" flag to "git cl upload".
	for suffix in SERVICE_ACCOUNT_SUFFIX:
	if change.author_email.endswith(suffix):
	return []

	results = []
	at_least_one_docs_change = False
	all_docs_changes = True
	for affected_file in change.AffectedFiles():
	affected_file_path = affected_file.LocalPath()
	file_path, _ = os.path.splitext(affected_file_path)
	if 'site' == file_path.split(os.path.sep)[0]:
	at_least_one_docs_change = True
	else:
	all_docs_changes = False
	if at_least_one_docs_change and not all_docs_changes:
	break

	footers = change.GitFootersFromDescription()
	description_changed = False

	# If the change includes only doc changes then add No-Try: true in the
	# CL's description if it does not exist yet.
	if all_docs_changes and 'true' not in footers.get('No-Try', []):
	description_changed = True
	change.AddDescriptionFooter('No-Try', 'true')
	results.append(
	output_api.PresubmitNotifyResult(
	'This change has only doc changes. Automatically added '
	'\'No-Try: true\' to the CL\'s description'))

	# If there is at least one docs change then add preview link in the CL's
	# description if it does not already exist there.
	docs_preview_link = DOCS_PREVIEW_URL.format(issue=change.issue)
	if (at_least_one_docs_change
	and docs_preview_link not in footers.get('Docs-Preview', [])):
	# Automatically add a link to where the docs can be previewed.
	description_changed = True
	change.AddDescriptionFooter('Docs-Preview', docs_preview_link)
	results.append(
	output_api.PresubmitNotifyResult(
	'Automatically added a link to preview the docs changes to the '
	'CL\'s description'))

	# If the description has changed update it.
	if description_changed:
	gerrit.UpdateDescription(
	change.FullDescriptionText(), change.issue)

	return results


	def CheckChangeOnCommit(input_api, output_api):
	"""Presubmit checks for the change on commit.

	The following are the presubmit checks:
	* Check change has one and only one EOL.
	* Ensures that the Skia tree is open in
	http://skia-tree-status.appspot.com/. Shows a warning if it is in 'Caution'
	state and an error if it is in 'Closed' state.
	"""
	results = []
	results.extend(_CommonChecks(input_api, output_api))
	results.extend(_CheckLGTMsForPublicAPI(input_api, output_api))
	results.extend(_CheckOwnerIsInAuthorsFile(input_api, output_api))
	# Checks for the presence of 'DO NOT''SUBMIT' in CL description and in
	# content of files.
	results.extend(
	input_api.canned_checks.CheckDoNotSubmit(input_api, output_api))
	return results