# Copyright 2016 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import argparse
import copy
from datetime import datetime
from functools import partial
import json
import os
import posixpath
import re
import sys
from code_util import Code
import json_parse
# The template for the header file of the generated FeatureProvider.
HEADER_FILE_TEMPLATE = """
// Copyright %(year)s The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// GENERATED FROM THE FEATURES FILE:
// %(source_files)s
// by tools/json_schema_compiler.
// DO NOT EDIT.
#ifndef %(header_guard)s
#define %(header_guard)s
namespace extensions {
class FeatureProvider;
void %(method_name)s(FeatureProvider* provider);
} // namespace extensions
#endif // %(header_guard)s
"""
# The beginning of the .cc file for the generated FeatureProvider.
CC_FILE_BEGIN = """
// Copyright %(year)s The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// GENERATED FROM THE FEATURES FILE:
// %(source_files)s
// by tools/json_schema_compiler.
// DO NOT EDIT.
#include "%(header_file_path)s"
#include "extensions/common/features/complex_feature.h"
#include "extensions/common/features/feature_provider.h"
#include "extensions/common/features/manifest_feature.h"
#include "extensions/common/features/permission_feature.h"
#include "extensions/common/mojom/context_type.mojom.h"
#include "extensions/common/mojom/feature_session_type.mojom.h"
#include "printing/buildflags/buildflags.h"
namespace extensions {
void %(method_name)s(FeatureProvider* provider) {
"""
# The end of the .cc file for the generated FeatureProvider.
CC_FILE_END = """
}
} // namespace extensions
"""
def ToPosixPath(path):
"""Returns |path| with separator converted to POSIX style.
This is needed to generate C++ #include paths.
"""
return path.replace(os.path.sep, posixpath.sep)
# Returns true if the list 'l' only contains strings that are a hex-encoded SHA1
# hashes.
def ListContainsOnlySha1Hashes(l):
return len(list(filter(lambda s: not re.match("^[A-F0-9]{40}$", s), l))) == 0
# A "grammar" for what is and isn't allowed in the features.json files. This
# grammar has to list all possible keys and the requirements for each. The
# format of each entry is:
# 'key': {
# allowed_type_1: optional_properties,
# allowed_type_2: optional_properties,
# }
# |allowed_types| are the types of values that can be used for a given key. The
# possible values are list, str, bool, and int.
# |optional_properties| provide more restrictions on the given type. The options
# are:
# 'subtype': Only applicable for lists. If provided, this enforces that each
# entry in the list is of the specified type.
# 'enum_map': A map of strings to C++ enums. When the compiler sees the given
# enum string, it will replace it with the C++ version in the
# compiled code. For instance, if a feature specifies
# 'channel': 'stable', the generated C++ will assign
# version_info::Channel::STABLE to channel. The keys in this map
# also serve as a list all of possible values.
# 'allow_all': Only applicable for lists. If present, this will check for
# a value of "all" for a list value, and will replace it with
# the collection of all possible values. For instance, if a
# feature specifies 'contexts': 'all', the generated C++ will
# assign the list of mojom::ContextType::kPrivilegedExtension,
# mojom::ContextType::kPrivilegedWebPage et al for contexts. If
# not specified, defaults to false.
# 'allow_empty': Only applicable for lists. Whether an empty list is a valid
# value. If omitted, empty lists are prohibited.
# 'validators': A list of (function, str) pairs with a function to run on the
# value for a feature. Validators allow for more flexible or
# one-off style validation than just what's in the grammar (such
# as validating the content of a string). The validator function
# should return True if the value is valid, and False otherwise.
# If the value is invalid, the specified error will be added for
# that key.
# 'values': A list of all possible allowed values for a given key.
# 'shared': Boolean that, if set, ensures that only one of the associated
# features has the feature property set. Used primarily for complex
# features - for simple features, there is always at most one feature
# setting an option.
# If a type definition does not have any restrictions (beyond the type itself),
# an empty definition ({}) is used.
FEATURE_GRAMMAR = ({
'alias': {
str: {},
'shared': True
},
'allowlist': {
list: {
'subtype':
str,
'validators':
[(ListContainsOnlySha1Hashes,
'list should only have hex-encoded SHA1 hashes of extension ids')]
}
},
'blocklist': {
list: {
'subtype':
str,
'validators':
[(ListContainsOnlySha1Hashes,
'list should only have hex-encoded SHA1 hashes of extension ids')]
}
},
'channel': {
str: {
'enum_map': {
'trunk': 'version_info::Channel::UNKNOWN',
'canary': 'version_info::Channel::CANARY',
'dev': 'version_info::Channel::DEV',
'beta': 'version_info::Channel::BETA',
'stable': 'version_info::Channel::STABLE',
}
}
},
'command_line_switch': {
str: {}
},
'component_extensions_auto_granted': {
bool: {}
},
'contexts': {
list: {
'enum_map': {
'privileged_extension':
'mojom::ContextType::kPrivilegedExtension',
'privileged_web_page':
'mojom::ContextType::kPrivilegedWebPage',
'content_script':
'mojom::ContextType::kContentScript',
'lock_screen_extension':
'mojom::ContextType::kLockscreenExtension',
'offscreen_extension':
'mojom::ContextType::kOffscreenExtension',
'user_script':
'mojom::ContextType::kUserScript',
'web_page':
'mojom::ContextType::kWebPage',
'webui':
'mojom::ContextType::kWebUi',
'webui_untrusted':
'mojom::ContextType::kUntrustedWebUi',
'unprivileged_extension':
'mojom::ContextType::kUnprivilegedExtension',
},
'allow_all': True,
'allow_empty': True
},
},
'default_parent': {
bool: {
'values': [True]
}
},
'dependencies': {
list: {
# We allow an empty list of dependencies for child features that
# want to override their parents' dependency set.
'allow_empty': True,
'subtype': str
}
},
'developer_mode_only': {
bool: {}
},
'disallow_for_service_workers': {
bool: {}
},
'extension_types': {
list: {
'enum_map': {
'extension':
'Manifest::TYPE_EXTENSION',
'hosted_app':
'Manifest::TYPE_HOSTED_APP',
'legacy_packaged_app':
'Manifest::TYPE_LEGACY_PACKAGED_APP',
'platform_app':
'Manifest::TYPE_PLATFORM_APP',
'shared_module':
'Manifest::TYPE_SHARED_MODULE',
'theme':
'Manifest::TYPE_THEME',
'login_screen_extension':
'Manifest::TYPE_LOGIN_SCREEN_EXTENSION',
'chromeos_system_extension':
'Manifest::TYPE_CHROMEOS_SYSTEM_EXTENSION',
},
'allow_all': True
},
},
'feature_flag': {
str: {}
},
'location': {
str: {
'enum_map': {
'component': 'SimpleFeature::COMPONENT_LOCATION',
'external_component':
'SimpleFeature::EXTERNAL_COMPONENT_LOCATION',
'policy': 'SimpleFeature::POLICY_LOCATION',
'unpacked': 'SimpleFeature::UNPACKED_LOCATION',
}
}
},
'internal': {
bool: {
'values': [True]
}
},
'matches': {
list: {
'subtype': str
}
},
'max_manifest_version': {
int: {
'values': [1, 2]
}
},
'min_manifest_version': {
int: {
'values': [2, 3]
}
},
'requires_delegated_availability_check': {
bool: {
'values': [True]
}
},
'noparent': {
bool: {
'values': [True]
}
},
'platforms': {
list: {
'enum_map': {
'chromeos': 'Feature::CHROMEOS_PLATFORM',
'fuchsia': 'Feature::FUCHSIA_PLATFORM',
'lacros': 'Feature::LACROS_PLATFORM',
'linux': 'Feature::LINUX_PLATFORM',
'mac': 'Feature::MACOSX_PLATFORM',
'win': 'Feature::WIN_PLATFORM',
}
}
},
'required_buildflags': {
list: {
'values': ['use_cups']
}
},
'session_types': {
list: {
'enum_map': {
'regular':
'mojom::FeatureSessionType::kRegular',
'kiosk':
'mojom::FeatureSessionType::kKiosk',
'kiosk.autolaunched':
'mojom::FeatureSessionType::kAutolaunchedKiosk',
}
}
},
'source': {
str: {},
'shared': True
},
})
FEATURE_TYPES = [
'APIFeature', 'BehaviorFeature', 'ManifestFeature', 'PermissionFeature'
]
def HasProperty(property_name, value):
return property_name in value
def HasAtLeastOneProperty(property_names, value):
return any([HasProperty(name, value) for name in property_names])
def DoesNotHaveAllProperties(property_names, value):
return not all([HasProperty(name, value) for name in property_names])
def DoesNotHaveProperty(property_name, value):
return property_name not in value
def DoesNotHavePropertyInComplexFeature(property_name, feature, all_features):
if type(feature) is ComplexFeature:
for child_feature in feature.feature_list:
if child_feature.GetValue(property_name):
return False
return True
def IsEmptyContextsAllowed(feature, all_features):
# An alias feature wouldn't have the 'contexts' feature value.
if feature.GetValue('source'):
return True
if type(feature) is ComplexFeature:
for child_feature in feature.feature_list:
if not IsEmptyContextsAllowed(child_feature, all_features):
return False
return True
contexts = feature.GetValue('contexts')
assert contexts, 'contexts must have been specified for the APIFeature'
allowlisted_empty_context_namespaces = [
'manifestTypes',
'extensionsManifestTypes',
'empty_contexts' # Only added for testing.
]
return (contexts != '{}'
or feature.name in allowlisted_empty_context_namespaces)
def IsFeatureCrossReference(property_name, reverse_property_name, feature,
all_features):
""" Verifies that |property_name| on |feature| references a feature that
references |feature| back using |reverse_property_name| property.
|property_name| and |reverse_property_name| are expected to have string
values.
"""
value = feature.GetValue(property_name)
if not value:
return True
# String property values will be wrapped in "", strip those.
value_regex = re.compile('^"(.+)"$')
parsed_value = value_regex.match(value)
assert parsed_value, (
'IsFeatureCrossReference should only be used on unicode properties')
referenced_feature = all_features.get(parsed_value.group(1))
if not referenced_feature:
return False
reverse_reference_value = referenced_feature.GetValue(reverse_property_name)
if not reverse_reference_value:
return False
# Don't validate reverse reference value for child features - chances are that
# the value was inherited from a feature parent, in which case it won't match
# current feature name.
if feature.has_parent:
return True
return reverse_reference_value == ('"%s"' % feature.name)
# Verifies that a feature with an allowlist is not available to hosted apps,
# returning true on success.
def DoesNotHaveAllowlistForHostedApps(value):
if not 'allowlist' in value:
return True
# Hack Alert: |value| here has the code for the generated C++ feature. Since
# we're looking at the individual values, we do a bit of yucky back-parsing
# to get a better look at the feature. This would be cleaner if we were
# operating on the JSON feature itself, but we currently never generate a
# JSON-based feature object that has all the values inherited from its
# parents. Since this is the only scenario we need this type of validation,
# doing it in a slightly ugly way isn't too bad. If we need more of these,
# we should find a smoother way to do it (e.g. first generate JSON-based
# features with inherited properties, do any necessary validation, then
# generate the C++ code strings).
# The feature did not specify extension types; this is fine for e.g.
# API features (which would typically rely on a permission feature, which
# is required to specify types).
if not 'extension_types' in value:
return True
types = value['extension_types']
# |types| looks like "{Manifest::TYPE_1, Manifest::TYPE_2}", so just looking
# for the "TYPE_HOSTED_APP substring is sufficient.
if 'TYPE_HOSTED_APP' not in types:
return True
# Helper to convert our C++ string array like "{\"aaa\", \"bbb\"}" (which is
# what the allowlist looks like) to a python list of strings.
def cpp_list_to_list(cpp_list):
assert type(cpp_list) is str
assert cpp_list[0] == '{'
assert cpp_list[-1] == '}'
new_list = json.loads('[%s]' % cpp_list[1:-1])
assert type(new_list) is list
return new_list
# Exceptions (see the feature files).
# DO NOT ADD MORE.
HOSTED_APP_EXCEPTIONS = [
'B44D08FD98F1523ED5837D78D0A606EA9D6206E5',
]
allowlist = cpp_list_to_list(value['allowlist'])
for entry in allowlist:
if entry not in HOSTED_APP_EXCEPTIONS:
return False
return True
SIMPLE_FEATURE_CPP_CLASSES = ({
'APIFeature': 'SimpleFeature',
'ManifestFeature': 'ManifestFeature',
'PermissionFeature': 'PermissionFeature',
'BehaviorFeature': 'SimpleFeature',
})
VALIDATION = ({
'all': [
(partial(HasAtLeastOneProperty, ['channel', 'dependencies']),
'Features must specify either a channel or dependencies'),
(DoesNotHaveAllowlistForHostedApps,
'Hosted apps are not allowed to use restricted features'),
],
'APIFeature':
[(partial(HasProperty,
'contexts'), 'APIFeatures must specify the contexts property'),
(partial(DoesNotHaveAllProperties, ['alias', 'source']),
'Features cannot specify both alias and source.')],
'ManifestFeature': [
(partial(HasProperty, 'extension_types'),
'ManifestFeatures must specify at least one extension type'),
(partial(DoesNotHaveProperty,
'contexts'), 'ManifestFeatures do not support contexts.'),
(partial(DoesNotHaveProperty,
'alias'), 'ManifestFeatures do not support alias.'),
(partial(DoesNotHaveProperty,
'source'), 'ManifestFeatures do not support source.'),
# The `required_buildflags` field is intended to be used to toggle the
# availability of certain APIs; if we support this for feature types
# other than APIFeature, we may emit warnings that are visible to
# developers which is not desirable.
(partial(DoesNotHaveProperty, 'required_buildflags'),
'ManifestFeatures do not support required_buildflags.'),
],
'BehaviorFeature': [
(partial(DoesNotHaveProperty,
'alias'), 'BehaviorFeatures do not support alias.'),
(partial(DoesNotHaveProperty,
'source'), 'BehaviorFeatures do not support source.'),
# The `required_buildflags` field is intended to be used to toggle the
# availability of certain APIs; if we support this for feature types
# other than APIFeature, we may emit warnings that are visible to
# developers which is not desirable.
(partial(DoesNotHaveProperty, 'required_buildflags'),
'BehaviorFeatures do not support required_buildflags.'),
],
'PermissionFeature': [
(partial(HasProperty, 'extension_types'),
'PermissionFeatures must specify at least one extension type'),
(partial(DoesNotHaveProperty,
'contexts'), 'PermissionFeatures do not support contexts.'),
(partial(DoesNotHaveProperty,
'alias'), 'PermissionFeatures do not support alias.'),
(partial(DoesNotHaveProperty,
'source'), 'PermissionFeatures do not support source.'),
# The `required_buildflags` field is intended to be used to toggle the
# availability of certain APIs; if we support this for feature types
# other than APIFeature, we may emit warnings that are visible to
# developers which is not desirable.
(partial(DoesNotHaveProperty, 'required_buildflags'),
'PermissionFeatures do not support required_buildflags.'),
],
})
FINAL_VALIDATION = ({
'all': [
# A complex feature requires at least one child entry at all times; with
# `required_buildflags` it becomes harder to guarantee that this holds
# for every potential combination of the provided flags.
(partial(DoesNotHavePropertyInComplexFeature, 'required_buildflags'),
'required_buildflags cannot be nested in a ComplexFeature'),
],
'APIFeature':
[(partial(IsFeatureCrossReference, 'alias', 'source'),
'A feature alias property should reference a feature whose source '
'property references it back.'),
(partial(IsFeatureCrossReference, 'source', 'alias'),
'A feature source property should reference a feature whose alias '
'property references it back.'),
(IsEmptyContextsAllowed,
'An empty contexts list is not allowed for this feature.')],
'ManifestFeature': [],
'BehaviorFeature': [],
'PermissionFeature': []
})
# These keys can not be set on a feature and are hence ignored.
IGNORED_KEYS = ['default_parent', 'required_buildflags']
# By default, if an error is encountered, assert to stop the compilation. This
# can be disabled for testing.
ENABLE_ASSERTIONS = True
def GetCodeForFeatureValues(feature_values):
""" Gets the Code object for setting feature values for this object. """
c = Code()
for key in sorted(feature_values.keys()):
if key in IGNORED_KEYS:
continue
c.Append('feature->set_%s(%s);' % (key, feature_values[key]))
return c
class Feature(object):
"""A representation of a single simple feature that can handle all parsing,
validation, and code generation.
"""
def __init__(self, name):
self.name = name
self.has_parent = False
self.errors = []
self.feature_values = {}
self.shared_values = {}
def AddError(self, error):
"""Adds an error to the feature. If ENABLE_ASSERTIONS is active, this will
also assert to stop the compilation process (since errors should never be
found in production).
"""
self.errors.append(error)
if ENABLE_ASSERTIONS:
assert False, error
def _AddKeyError(self, key, error):
"""Adds an error relating to a particular key in the feature.
"""
self.AddError('Error parsing feature "%s" at key "%s": %s' %
(self.name, key, error))
def _GetCheckedValue(self, key, expected_type, expected_values, enum_map,
value):
"""Returns a string to be used in the generated C++ code for a given key's
python value, or None if the value is invalid. For example, if the python
value is True, this returns 'true', for a string foo, this returns "foo",
and for an enum, this looks up the C++ definition in the enum map.
key: The key being parsed.
expected_type: The expected type for this value, or None if any type is
allowed.
expected_values: The list of allowed values for this value, or None if any
value is allowed.
enum_map: The map from python value -> cpp value for all allowed values,
or None if no special mapping should be made.
value: The value to check.
"""
valid = True
if expected_values and value not in expected_values:
self._AddKeyError(key, 'Illegal value: "%s"' % value)
valid = False
t = type(value)
if expected_type and t is not expected_type:
self._AddKeyError(key, 'Illegal value: "%s"' % value)
valid = False
if not valid:
return None
if enum_map:
return enum_map[value]
if t is str:
if key == 'required_buildflags':
return value
return '"%s"' % str(value)
if t is int:
return str(value)
if t is bool:
return 'true' if value else 'false'
assert False, 'Unsupported type: %s' % value
def _ParseKey(self, key, value, shared_values, grammar):
"""Parses the specific key according to the grammar rule for that key if it
is present in the json value.
key: The key to parse.
value: The full value for this feature.
shared_values: Set of shared vfalues associated with this feature.
grammar: The rule for the specific key.
"""
if key not in value:
return
v = value[key]
is_all = False
if v == 'all' and list in grammar and 'allow_all' in grammar[list]:
assert grammar[list]['allow_all'], '`allow_all` only supports `True`.'
v = []
is_all = True
if 'shared' in grammar and key in shared_values:
self._AddKeyError(key, 'Key can be set at most once per feature.')
return
value_type = type(v)
if value_type not in grammar:
self._AddKeyError(key, 'Illegal value: "%s"' % v)
return
if value_type is list and not is_all and len(v) == 0:
if 'allow_empty' in grammar[list]:
assert grammar[list]['allow_empty'], \
'`allow_empty` only supports `True`.'
else:
self._AddKeyError(key, 'List must specify at least one element.')
return
expected = grammar[value_type]
expected_values = None
enum_map = None
if 'values' in expected:
expected_values = expected['values']
elif 'enum_map' in expected:
enum_map = expected['enum_map']
expected_values = list(enum_map)
if is_all:
v = copy.deepcopy(expected_values)
expected_type = None
if value_type is list and 'subtype' in expected:
expected_type = expected['subtype']
cpp_value = None
# If this value is a list, iterate over each entry and validate. Otherwise,
# validate the single value.
if value_type is list:
cpp_value = []
for sub_value in v:
cpp_sub_value = self._GetCheckedValue(key, expected_type,
expected_values, enum_map,
sub_value)
if cpp_sub_value:
cpp_value.append(cpp_sub_value)
if key != 'required_buildflags':
cpp_value = '{' + ','.join(cpp_value) + '}'
else:
cpp_value = self._GetCheckedValue(key, expected_type, expected_values,
enum_map, v)
if 'validators' in expected:
validators = expected['validators']
for validator, error in validators:
if not validator(v):
self._AddKeyError(key, error)
if cpp_value:
if 'shared' in grammar:
shared_values[key] = cpp_value
else:
self.feature_values[key] = cpp_value
elif key in self.feature_values:
# If the key is empty and this feature inherited a value from its parent,
# remove the inherited value.
del self.feature_values[key]
def SetParent(self, parent):
"""Sets the parent of this feature, and inherits all properties from that
parent.
"""
assert not self.feature_values, 'Parents must be set before parsing'
self.feature_values = copy.deepcopy(parent.feature_values)
self.has_parent = True
def SetSharedValues(self, values):
self.shared_values = values
def Parse(self, parsed_json, shared_values):
"""Parses the feature from the given json value."""
for key in parsed_json.keys():
if key not in FEATURE_GRAMMAR:
self._AddKeyError(key, 'Unrecognized key')
for key, key_grammar in FEATURE_GRAMMAR.items():
self._ParseKey(key, parsed_json, shared_values, key_grammar)
def Validate(self, feature_type, shared_values):
feature_values = self.feature_values.copy()
feature_values.update(shared_values)
for validator, error in (VALIDATION[feature_type] + VALIDATION['all']):
if not validator(feature_values):
self.AddError(error)
def GetCode(self, feature_type):
"""Returns the Code object for generating this feature."""
c = Code()
cpp_feature_class = SIMPLE_FEATURE_CPP_CLASSES[feature_type]
c.Append('%s* feature = new %s();' % (cpp_feature_class, cpp_feature_class))
c.Append('feature->set_name("%s");' % self.name)
c.Concat(GetCodeForFeatureValues(self.GetAllFeatureValues()))
return c
def AsParent(self):
""" Returns the feature values that should be inherited by children features
when this feature is set as parent.
"""
return self
def GetValue(self, key):
""" Gets feature value for the specified key """
value = self.feature_values.get(key)
return value if value else self.shared_values.get(key)
def GetAllFeatureValues(self):
""" Gets all values set for this feature. """
values = self.feature_values.copy()
values.update(self.shared_values)
return values
def GetErrors(self):
return self.errors
class ComplexFeature(Feature):
""" Complex feature - feature that is comprised of list of features.
Overall complex feature is available if any of contained
feature is available.
"""
def __init__(self, name):
Feature.__init__(self, name)
self.feature_list = []
def GetCode(self, feature_type):
c = Code()
c.Append('std::vector<Feature*> features;')
for f in self.feature_list:
# Sanity check that components of complex features have no shared values
# set.
assert not f.shared_values
c.Sblock('{')
c.Concat(f.GetCode(feature_type))
c.Append('features.push_back(feature);')
c.Eblock('}')
c.Append('ComplexFeature* feature(new ComplexFeature(&features));')
c.Append('feature->set_name("%s");' % self.name)
c.Concat(GetCodeForFeatureValues(self.shared_values))
return c
def AsParent(self):
parent = None
for p in self.feature_list:
if 'default_parent' in p.feature_values:
parent = p
break
assert parent, 'No default parent found for %s' % self.name
return parent
def GetErrors(self):
errors = copy.copy(self.errors)
for feature in self.feature_list:
errors.extend(feature.GetErrors())
return errors
class FeatureCompiler(object):
"""A compiler to load, parse, and generate C++ code for a number of
features.json files."""
def __init__(self, chrome_root, source_files, feature_type, method_name,
out_root, gen_dir_relpath, out_base_filename):
# See __main__'s ArgumentParser for documentation on these properties.
self._chrome_root = chrome_root
self._source_files = source_files
self._feature_type = feature_type
self._method_name = method_name
self._out_root = out_root
self._out_base_filename = out_base_filename
self._gen_dir_relpath = gen_dir_relpath
# The json value for the feature files.
self._json = {}
# The parsed features.
self._features = {}
def Load(self):
"""Loads and parses the source from each input file and puts the result in
self._json."""
for f in self._source_files:
abs_source_file = os.path.join(self._chrome_root, f)
try:
with open(abs_source_file, 'r') as f:
f_json = json_parse.Parse(f.read())
except:
print('FAILED: Exception encountered while loading "%s"' %
abs_source_file)
raise
dupes = set(f_json) & set(self._json)
assert not dupes, 'Duplicate keys found: %s' % list(dupes)
self._json.update(f_json)
def _FindParent(self, feature_name, feature_value):
"""Checks to see if a feature has a parent. If it does, returns the
parent."""
no_parent = False
if type(feature_value) is list:
no_parent_values = ['noparent' in v for v in feature_value]
no_parent = all(no_parent_values)
assert no_parent or not any(no_parent_values), (
'"%s:" All child features must contain the same noparent value' %
feature_name)
else:
no_parent = 'noparent' in feature_value
sep = feature_name.rfind('.')
if sep == -1 or no_parent:
return None
parent_name = feature_name[:sep]
while sep != -1 and parent_name not in self._features:
# This recursion allows for a feature to have a parent that isn't a direct
# ancestor. For instance, we could have feature 'alpha', and feature
# 'alpha.child.child', where 'alpha.child.child' inherits from 'alpha'.
# TODO(devlin): Is this useful? Or logical?
sep = feature_name.rfind('.', 0, sep)
parent_name = feature_name[:sep]
if sep == -1:
# TODO(devlin): It'd be kind of nice to be able to assert that the
# deduced parent name is in our features, but some dotted features don't
# have parents and also don't have noparent, e.g. system.cpu. We should
# probably just noparent them so that we can assert this.
# raise KeyError('Could not find parent "%s" for feature "%s".' %
# (parent_name, feature_name))
return None
return self._features[parent_name].AsParent()
def _CompileFeature(self, feature_name, feature_value):
"""Parses a single feature."""
if 'nocompile' in feature_value:
assert feature_value['nocompile'], (
'nocompile should only be true; otherwise omit this key.')
return
def parse_and_validate(name, value, parent, shared_values):
try:
feature = Feature(name)
if parent:
feature.SetParent(parent)
feature.Parse(value, shared_values)
feature.Validate(self._feature_type, shared_values)
return feature
except:
print('Failure to parse feature "%s"' % feature_name)
raise
parent = self._FindParent(feature_name, feature_value)
shared_values = {}
# Handle complex features, which are lists of simple features.
if type(feature_value) is list:
assert len(feature_value) > 1, (
'Error parsing feature "%s": A complex feature ' % feature_name +
'definition is only needed when there are multiple objects ' +
'specifying different groups of properties for feature ' +
'availability. You can reduce it down to a single object on the ' +
'feature key instead of a list.')
feature = ComplexFeature(feature_name)
# This doesn't handle nested complex features. I think that's probably for
# the best.
for v in feature_value:
feature.feature_list.append(
parse_and_validate(feature_name, v, parent, shared_values))
self._features[feature_name] = feature
else:
self._features[feature_name] = parse_and_validate(feature_name,
feature_value, parent,
shared_values)
# Apply parent shared values at the end to enable child features to
# override parent shared value - if parent shared values are added to
# shared value set before a child feature is parsed, the child feature
# overriding shared values set by its parent would cause an error due to
# shared values being set twice.
final_shared_values = copy.deepcopy(parent.shared_values) if parent else {}
final_shared_values.update(shared_values)
self._features[feature_name].SetSharedValues(final_shared_values)
def _FinalValidation(self):
validators = FINAL_VALIDATION['all'] + FINAL_VALIDATION[self._feature_type]
for name, feature in self._features.items():
for validator, error in validators:
if not validator(feature, self._features):
feature.AddError(error)
def Compile(self):
"""Parses all features after loading the input files."""
# Iterate over in sorted order so that parents come first.
for k in sorted(self._json.keys()):
self._CompileFeature(k, self._json[k])
self._FinalValidation()
def Render(self):
"""Returns the Code object for the body of the .cc file, which handles the
initialization of all features."""
c = Code()
c.Sblock()
for k in sorted(self._features.keys()):
c.Sblock('{')
feature = self._features[k]
required_buildflags = feature.GetValue('required_buildflags')
if required_buildflags:
formatted_buildflags = [
'BUILDFLAG(%s)' % format(flag.upper())
for flag in required_buildflags
]
c.Append('#if %s' % format(' && '.join(formatted_buildflags)))
c.Concat(feature.GetCode(self._feature_type))
c.Append('provider->AddFeature("%s", feature);' % k)
if required_buildflags:
c.Append('#endif')
c.Eblock('}')
c.Eblock()
return c
def Write(self):
"""Writes the output."""
header_file = self._out_base_filename + '.h'
cc_file = self._out_base_filename + '.cc'
include_file_root = self._out_root[len(self._gen_dir_relpath) + 1:]
header_file_path = '%s/%s' % (include_file_root, header_file)
cc_file_path = '%s/%s' % (include_file_root, cc_file)
substitutions = ({
'header_file_path':
header_file_path,
'header_guard':
(header_file_path.replace('/', '_').replace('.', '_').upper()),
'method_name':
self._method_name,
'source_files':
str([ToPosixPath(f) for f in self._source_files]),
'year':
str(datetime.now().year)
})
if not os.path.exists(self._out_root):
os.makedirs(self._out_root)
# Write the .h file.
with open(os.path.join(self._out_root, header_file), 'w') as f:
header_file = Code()
header_file.Append(HEADER_FILE_TEMPLATE)
header_file.Substitute(substitutions)
f.write(header_file.Render().strip())
# Write the .cc file.
with open(os.path.join(self._out_root, cc_file), 'w') as f:
cc_file = Code()
cc_file.Append(CC_FILE_BEGIN)
cc_file.Substitute(substitutions)
cc_file.Concat(self.Render())
cc_end = Code()
cc_end.Append(CC_FILE_END)
cc_end.Substitute(substitutions)
cc_file.Concat(cc_end)
f.write(cc_file.Render().strip())
if __name__ == '__main__':
parser = argparse.ArgumentParser(description='Compile json feature files')
parser.add_argument('chrome_root',
type=str,
help='The root directory of the chrome checkout')
parser.add_argument(
'feature_type',
type=str,
help='The name of the class to use in feature generation ' +
'(e.g. APIFeature, PermissionFeature)')
parser.add_argument('method_name',
type=str,
help='The name of the method to populate the provider')
parser.add_argument('out_root',
type=str,
help='The root directory to generate the C++ files into')
parser.add_argument(
'gen_dir_relpath',
default='gen',
help='Path of the '
'gen directory relative to the out/. If running in the default '
'toolchain, the path is gen, otherwise $toolchain_name/gen')
parser.add_argument(
'out_base_filename',
type=str,
help='The base filename for the C++ files (.h and .cc will be appended)')
parser.add_argument('source_files',
type=str,
nargs='+',
help='The source features.json files')
args = parser.parse_args()
if args.feature_type not in FEATURE_TYPES:
raise NameError('Unknown feature type: %s' % args.feature_type)
c = FeatureCompiler(args.chrome_root, args.source_files, args.feature_type,
args.method_name, args.out_root, args.gen_dir_relpath,
args.out_base_filename)
c.Load()
c.Compile()
c.Write()
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