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# Copyright (C) 2019 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# A collection of utilities for extracting build rule information from GN
# projects.
from __future__ import print_function
import collections
import errno
import filecmp
import json
import os
import re
import shutil
import subprocess
import sys
from compat import iteritems
BUILDFLAGS_TARGET = '//gn:gen_buildflags'
GEN_VERSION_TARGET = '//src/base:version_gen_h'
TARGET_TOOLCHAIN = '//gn/standalone/toolchain:gcc_like_host'
HOST_TOOLCHAIN = '//gn/standalone/toolchain:gcc_like_host'
LINKER_UNIT_TYPES = ('executable', 'shared_library', 'static_library')
# TODO(primiano): investigate these, they require further componentization.
ODR_VIOLATION_IGNORE_TARGETS = {
'//test/cts:perfetto_cts_deps',
'//:perfetto_integrationtests',
}
def _check_command_output(cmd, cwd):
try:
output = subprocess.check_output(cmd, stderr=subprocess.STDOUT, cwd=cwd)
except subprocess.CalledProcessError as e:
print(
'Command "{}" failed in {}:'.format(' '.join(cmd), cwd),
file=sys.stderr)
print(e.output.decode(), file=sys.stderr)
sys.exit(1)
else:
return output.decode()
def repo_root():
"""Returns an absolute path to the repository root."""
return os.path.join(
os.path.realpath(os.path.dirname(__file__)), os.path.pardir)
def _tool_path(name):
wrapper = os.path.abspath(
os.path.join(repo_root(), 'tools', 'run_buildtools_binary.py'))
return ['python3', wrapper, name]
def prepare_out_directory(gn_args, name, root=repo_root()):
"""Creates the JSON build description by running GN.
Returns (path, desc) where |path| is the location of the output directory
and |desc| is the JSON build description.
"""
out = os.path.join(root, 'out', name)
try:
os.makedirs(out)
except OSError as e:
if e.errno != errno.EEXIST:
raise
_check_command_output(
_tool_path('gn') + ['gen', out, '--args=%s' % gn_args], cwd=repo_root())
return out
def load_build_description(out):
"""Creates the JSON build description by running GN."""
desc = _check_command_output(
_tool_path('gn') +
['desc', out, '--format=json', '--all-toolchains', '//*'],
cwd=repo_root())
return json.loads(desc)
def create_build_description(gn_args, root=repo_root()):
"""Prepares a GN out directory and loads the build description from it.
The temporary out directory is automatically deleted.
"""
out = prepare_out_directory(gn_args, 'tmp.gn_utils', root=root)
try:
return load_build_description(out)
finally:
shutil.rmtree(out)
def build_targets(out, targets, quiet=False):
"""Runs ninja to build a list of GN targets in the given out directory.
Compiling these targets is required so that we can include any generated
source files in the amalgamated result.
"""
targets = [t.replace('//', '') for t in targets]
with open(os.devnull, 'w') as devnull:
stdout = devnull if quiet else None
cmd = _tool_path('ninja') + targets
subprocess.check_call(cmd, cwd=os.path.abspath(out), stdout=stdout)
def compute_source_dependencies(out):
"""For each source file, computes a set of headers it depends on."""
ninja_deps = _check_command_output(
_tool_path('ninja') + ['-t', 'deps'], cwd=out)
deps = {}
current_source = None
for line in ninja_deps.split('\n'):
filename = os.path.relpath(os.path.join(out, line.strip()), repo_root())
if not line or line[0] != ' ':
current_source = None
continue
elif not current_source:
# We're assuming the source file is always listed before the
# headers.
assert os.path.splitext(line)[1] in ['.c', '.cc', '.cpp', '.S']
current_source = filename
deps[current_source] = []
else:
assert current_source
deps[current_source].append(filename)
return deps
def label_to_path(label):
"""Turn a GN output label (e.g., //some_dir/file.cc) into a path."""
assert label.startswith('//')
return label[2:]
def label_without_toolchain(label):
"""Strips the toolchain from a GN label.
Return a GN label (e.g //buildtools:protobuf(//gn/standalone/toolchain:
gcc_like_host) without the parenthesised toolchain part.
"""
return label.split('(')[0]
def label_to_target_name_with_path(label):
"""
Turn a GN label into a target name involving the full path.
e.g., //src/perfetto:tests -> src_perfetto_tests
"""
name = re.sub(r'^//:?', '', label)
name = re.sub(r'[^a-zA-Z0-9_]', '_', name)
return name
def gen_buildflags(gn_args, target_file):
"""Generates the perfetto_build_flags.h for the given config.
target_file: the path, relative to the repo root, where the generated
buildflag header will be copied into.
"""
tmp_out = prepare_out_directory(gn_args, 'tmp.gen_buildflags')
build_targets(tmp_out, [BUILDFLAGS_TARGET], quiet=True)
src = os.path.join(tmp_out, 'gen', 'build_config', 'perfetto_build_flags.h')
shutil.copy(src, os.path.join(repo_root(), target_file))
shutil.rmtree(tmp_out)
def check_or_commit_generated_files(tmp_files, check):
"""Checks that gen files are unchanged or renames them to the final location
Takes in input a list of 'xxx.swp' files that have been written.
If check == False, it renames xxx.swp -> xxx.
If check == True, it just checks that the contents of 'xxx.swp' == 'xxx'.
Returns 0 if no diff was detected, 1 otherwise (to be used as exit code).
"""
res = 0
for tmp_file in tmp_files:
assert (tmp_file.endswith('.swp'))
target_file = os.path.relpath(tmp_file[:-4])
if check:
if not filecmp.cmp(tmp_file, target_file):
sys.stderr.write('%s needs to be regenerated\n' % target_file)
res = 1
os.unlink(tmp_file)
else:
os.rename(tmp_file, target_file)
return res
class ODRChecker(object):
"""Detects ODR violations in linker units
When we turn GN source sets into Soong & Bazel file groups, there is the risk
to create ODR violations by including the same file group into different
linker unit (this is because other build systems don't have a concept
equivalent to GN's source_set). This class navigates the transitive
dependencies (mostly static libraries) of a target and detects if multiple
paths end up including the same file group. This is to avoid situations like:
traced.exe -> base(file group)
traced.exe -> libperfetto(static lib) -> base(file group)
"""
def __init__(self, gn, target_name):
self.gn = gn
self.root = gn.get_target(target_name)
self.source_sets = collections.defaultdict(set)
self.deps_visited = set()
self.source_set_hdr_only = {}
self._visit(target_name)
num_violations = 0
if target_name in ODR_VIOLATION_IGNORE_TARGETS:
return
for sset, paths in self.source_sets.items():
if self.is_header_only(sset):
continue
if len(paths) != 1:
num_violations += 1
print(
'ODR violation in target %s, multiple paths include %s:\n %s' %
(target_name, sset, '\n '.join(paths)),
file=sys.stderr)
if num_violations > 0:
raise Exception('%d ODR violations detected. Build generation aborted' %
num_violations)
def _visit(self, target_name, parent_path=''):
target = self.gn.get_target(target_name)
path = ((parent_path + ' > ') if parent_path else '') + target_name
if not target:
raise Exception('Cannot find target %s' % target_name)
for ssdep in target.source_set_deps:
name_and_path = '%s (via %s)' % (target_name, path)
self.source_sets[ssdep].add(name_and_path)
deps = set(target.deps).union(
target.transitive_proto_deps) - self.deps_visited
for dep_name in deps:
dep = self.gn.get_target(dep_name)
if dep.type == 'executable':
continue # Execs are strong boundaries and don't cause ODR violations.
# static_library dependencies should reset the path. It doesn't matter if
# we get to a source file via:
# source_set1 > static_lib > source.cc OR
# source_set1 > source_set2 > static_lib > source.cc
# This is NOT an ODR violation because source.cc is linked from the same
# static library
next_parent_path = path if dep.type != 'static_library' else ''
self.deps_visited.add(dep_name)
self._visit(dep_name, next_parent_path)
def is_header_only(self, source_set_name):
cached = self.source_set_hdr_only.get(source_set_name)
if cached is not None:
return cached
target = self.gn.get_target(source_set_name)
if target.type != 'source_set':
raise TypeError('%s is not a source_set' % source_set_name)
res = all(src.endswith('.h') for src in target.sources)
self.source_set_hdr_only[source_set_name] = res
return res
class GnParser(object):
"""A parser with some cleverness for GN json desc files
The main goals of this parser are:
1) Deal with the fact that other build systems don't have an equivalent
notion to GN's source_set. Conversely to Bazel's and Soong's filegroups,
GN source_sets expect that dependencies, cflags and other source_set
properties propagate up to the linker unit (static_library, executable or
shared_library). This parser simulates the same behavior: when a
source_set is encountered, some of its variables (cflags and such) are
copied up to the dependent targets. This is to allow gen_xxx to create
one filegroup for each source_set and then squash all the other flags
onto the linker unit.
2) Detect and special-case protobuf targets, figuring out the protoc-plugin
being used.
"""
class Target(object):
"""Reperesents A GN target.
Maked properties are propagated up the dependency chain when a
source_set dependency is encountered.
"""
def __init__(self, name, type):
self.name = name # e.g. //src/ipc:ipc
VALID_TYPES = ('static_library', 'shared_library', 'executable', 'group',
'action', 'source_set', 'proto_library')
assert (type in VALID_TYPES)
self.type = type
self.testonly = False
self.toolchain = None
# These are valid only for type == proto_library.
# This is typically: 'proto', 'protozero', 'ipc'.
self.proto_plugin = None
self.proto_paths = set()
self.proto_exports = set()
self.sources = set()
# TODO(primiano): consider whether the public section should be part of
# bubbled-up sources.
self.public_headers = set() # 'public'
# These are valid only for type == 'action'
self.inputs = set()
self.outputs = set()
self.script = None
self.args = []
# These variables are propagated up when encountering a dependency
# on a source_set target.
self.cflags = set()
self.defines = set()
self.deps = set()
self.libs = set()
self.include_dirs = set()
self.ldflags = set()
self.source_set_deps = set() # Transitive set of source_set deps.
self.proto_deps = set()
self.transitive_proto_deps = set()
# Deps on //gn:xxx have this flag set to True. These dependencies
# are special because they pull third_party code from buildtools/.
# We don't want to keep recursing into //buildtools in generators,
# this flag is used to stop the recursion and create an empty
# placeholder target once we hit //gn:protoc or similar.
self.is_third_party_dep_ = False
def __lt__(self, other):
if isinstance(other, self.__class__):
return self.name < other.name
raise TypeError(
'\'<\' not supported between instances of \'%s\' and \'%s\'' %
(type(self).__name__, type(other).__name__))
def __repr__(self):
return json.dumps({
k: (list(sorted(v)) if isinstance(v, set) else v)
for (k, v) in iteritems(self.__dict__)
},
indent=4,
sort_keys=True)
def update(self, other):
for key in ('cflags', 'defines', 'deps', 'include_dirs', 'ldflags',
'source_set_deps', 'proto_deps', 'transitive_proto_deps',
'libs', 'proto_paths'):
self.__dict__[key].update(other.__dict__.get(key, []))
def __init__(self, gn_desc):
self.gn_desc_ = gn_desc
self.all_targets = {}
self.linker_units = {} # Executables, shared or static libraries.
self.source_sets = {}
self.actions = {}
self.proto_libs = {}
def get_target(self, gn_target_name):
"""Returns a Target object from the fully qualified GN target name.
It bubbles up variables from source_set dependencies as described in the
class-level comments.
"""
target = self.all_targets.get(gn_target_name)
if target is not None:
return target # Target already processed.
desc = self.gn_desc_[gn_target_name]
target = GnParser.Target(gn_target_name, desc['type'])
target.testonly = desc.get('testonly', False)
target.toolchain = desc.get('toolchain', None)
self.all_targets[gn_target_name] = target
# We should never have GN targets directly depend on buidtools. They
# should hop via //gn:xxx, so we can give generators an opportunity to
# override them.
assert (not gn_target_name.startswith('//buildtools'))
# Don't descend further into third_party targets. Genrators are supposed
# to either ignore them or route to other externally-provided targets.
if gn_target_name.startswith('//gn'):
target.is_third_party_dep_ = True
return target
proto_target_type, proto_desc = self.get_proto_target_type(target)
if proto_target_type is not None:
self.proto_libs[target.name] = target
target.type = 'proto_library'
target.proto_plugin = proto_target_type
target.proto_paths.update(self.get_proto_paths(proto_desc))
target.proto_exports.update(self.get_proto_exports(proto_desc))
target.sources.update(proto_desc.get('sources', []))
assert (all(x.endswith('.proto') for x in target.sources))
elif target.type == 'source_set':
self.source_sets[gn_target_name] = target
target.sources.update(desc.get('sources', []))
elif target.type in LINKER_UNIT_TYPES:
self.linker_units[gn_target_name] = target
target.sources.update(desc.get('sources', []))
elif target.type == 'action':
self.actions[gn_target_name] = target
target.inputs.update(desc.get('inputs', []))
target.sources.update(desc.get('sources', []))
outs = [re.sub('^//out/.+?/gen/', '', x) for x in desc['outputs']]
target.outputs.update(outs)
target.script = desc['script']
# Args are typically relative to the root build dir (../../xxx)
# because root build dir is typically out/xxx/).
target.args = [re.sub('^../../', '//', x) for x in desc['args']]
# Default for 'public' is //* - all headers in 'sources' are public.
# TODO(primiano): if a 'public' section is specified (even if empty), then
# the rest of 'sources' is considered inaccessible by gn. Consider
# emulating that, so that generated build files don't end up with overly
# accessible headers.
public_headers = [x for x in desc.get('public', []) if x != '*']
target.public_headers.update(public_headers)
target.cflags.update(desc.get('cflags', []) + desc.get('cflags_cc', []))
target.libs.update(desc.get('libs', []))
target.ldflags.update(desc.get('ldflags', []))
target.defines.update(desc.get('defines', []))
target.include_dirs.update(desc.get('include_dirs', []))
# Recurse in dependencies.
for dep_name in desc.get('deps', []):
dep = self.get_target(dep_name)
if dep.is_third_party_dep_:
target.deps.add(dep_name)
elif dep.type == 'proto_library':
target.proto_deps.add(dep_name)
target.transitive_proto_deps.add(dep_name)
target.proto_paths.update(dep.proto_paths)
target.transitive_proto_deps.update(dep.transitive_proto_deps)
elif dep.type == 'source_set':
target.source_set_deps.add(dep_name)
target.update(dep) # Bubble up source set's cflags/ldflags etc.
elif dep.type == 'group':
target.update(dep) # Bubble up groups's cflags/ldflags etc.
elif dep.type == 'action':
if proto_target_type is None:
target.deps.add(dep_name)
elif dep.type in LINKER_UNIT_TYPES:
target.deps.add(dep_name)
return target
def get_proto_exports(self, proto_desc):
# exports in metadata will be available for source_set targets.
metadata = proto_desc.get('metadata', {})
return metadata.get('exports', [])
def get_proto_paths(self, proto_desc):
# import_dirs in metadata will be available for source_set targets.
metadata = proto_desc.get('metadata', {})
return metadata.get('import_dirs', [])
def get_proto_target_type(self, target):
""" Checks if the target is a proto library and return the plugin.
Returns:
(None, None): if the target is not a proto library.
(plugin, proto_desc) where |plugin| is 'proto' in the default (lite)
case or 'protozero' or 'ipc' or 'descriptor'; |proto_desc| is the GN
json desc of the target with the .proto sources (_gen target for
non-descriptor types or the target itself for descriptor type).
"""
parts = target.name.split('(', 1)
name = parts[0]
toolchain = '(' + parts[1] if len(parts) > 1 else ''
# Descriptor targets don't have a _gen target; instead we look for the
# characteristic flag in the args of the target itself.
desc = self.gn_desc_.get(target.name)
if '--descriptor_set_out' in desc.get('args', []):
return 'descriptor', desc
# Source set proto targets have a non-empty proto_library_sources in the
# metadata of the description.
metadata = desc.get('metadata', {})
if 'proto_library_sources' in metadata:
return 'source_set', desc
# In all other cases, we want to look at the _gen target as that has the
# important information.
gen_desc = self.gn_desc_.get('%s_gen%s' % (name, toolchain))
if gen_desc is None or gen_desc['type'] != 'action':
return None, None
args = gen_desc.get('args', [])
if '/protoc' not in args[0]:
return None, None
plugin = 'proto'
for arg in (arg for arg in args if arg.startswith('--plugin=')):
# |arg| at this point looks like:
# --plugin=protoc-gen-plugin=gcc_like_host/protozero_plugin
# or
# --plugin=protoc-gen-plugin=protozero_plugin
plugin = arg.split('=')[-1].split('/')[-1].replace('_plugin', '')
return plugin, gen_desc