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# 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.
"""A database of OWNERS files.
OWNERS files indicate who is allowed to approve changes in a specific directory
(or who is allowed to make changes without needing approval of another OWNER).
Note that all changes must still be reviewed by someone familiar with the code,
so you may need approval from both an OWNER and a reviewer in many cases.
The syntax of the OWNERS file is, roughly:
lines := (\s* line? \s* "\n")*
line := directive
| "per-file" \s+ glob \s* "=" \s* directive
| comment
directive := "set noparent"
| "file:" glob
| email_address
| "*"
glob := [a-zA-Z0-9_-*?]+
comment := "#" [^"\n"]*
Email addresses must follow the short form (exact syntax given
in BASIC_EMAIL_REGEXP, below). Filename globs follow the simple unix
shell conventions, and relative and absolute paths are not allowed (i.e.,
globs only refer to the files in the current directory).
If a user's email is one of the email_addresses in the file, the user is
considered an "OWNER" for all files in the directory.
If the "per-file" directive is used, the line only applies to files in that
directory that match the filename glob specified.
If the "set noparent" directive used, then only entries in this OWNERS file
apply to files in this directory; if the "set noparent" directive is not
used, then entries in OWNERS files in enclosing (upper) directories also
apply (up until a "set noparent is encountered").
If "per-file glob=set noparent" is used, then global directives are ignored
for the glob, and only the "per-file" owners are used for files matching that
If the "file:" directive is used, the referred to OWNERS file will be parsed and
considered when determining the valid set of OWNERS. If the filename starts with
"//" it is relative to the root of the repository, otherwise it is relative to
the current file
Examples for all of these combinations can be found in tests/
import collections
import fnmatch
import random
import re
# If this is present by itself on a line, this means that everyone can review.
# Recognizes 'X@Y' email addresses. Very simplistic.
BASIC_EMAIL_REGEXP = r'^[\w\-\+\%\.]+\@[\w\-\+\%\.]+$'
# Key for global comments per email address. Should be unlikely to be a
# pathname.
def _assert_is_collection(obj):
assert not isinstance(obj, basestring)
# Module 'collections' has no 'Iterable' member
# pylint: disable=no-member
if hasattr(collections, 'Iterable') and hasattr(collections, 'Sized'):
assert (isinstance(obj, collections.Iterable) and
isinstance(obj, collections.Sized))
class SyntaxErrorInOwnersFile(Exception):
def __init__(self, path, lineno, msg):
super(SyntaxErrorInOwnersFile, self).__init__((path, lineno, msg))
self.path = path
self.lineno = lineno
self.msg = msg
def __str__(self):
return '%s:%d syntax error: %s' % (self.path, self.lineno, self.msg)
class Database(object):
"""A database of OWNERS files for a repository.
This class allows you to find a suggested set of reviewers for a list
of changed files, and see if a list of changed files is covered by a
list of reviewers."""
def __init__(self, root, fopen, os_path):
root: the path to the root of the Repository
open: function callback to open a text file for reading
os_path: module/object callback with fields for 'abspath', 'dirname',
'exists', 'join', and 'relpath'
self.root = root
self.fopen = fopen
self.os_path = os_path
# Pick a default email regexp to use; callers can override as desired.
self.email_regexp = re.compile(BASIC_EMAIL_REGEXP)
# Replacement contents for the given files. Maps the file name of an
# OWNERS file (relative to root) to an iterator returning the replacement
# file contents.
self.override_files = {}
# Mapping of owners to the paths or globs they own.
self._owners_to_paths = {EVERYONE: set()}
# Mapping of paths to authorized owners.
self._paths_to_owners = {}
# Mapping reviewers to the preceding comment per file in the OWNERS files.
self.comments = {}
# Cache of compiled regexes for _fnmatch()
self._fnmatch_cache = {}
# Set of paths that stop us from looking above them for owners.
# (This is implicitly true for the root directory).
self._stop_looking = set([''])
# Set of files which have already been read.
self.read_files = set()
# Set of files which were included from other files. Files are processed
# differently depending on whether they are regular owners files or
# being included from another file.
self._included_files = {}
# File with global status lines for owners.
self._status_file = None
def reviewers_for(self, files, author):
"""Returns a suggested set of reviewers that will cover the files.
files is a sequence of paths relative to (and under) self.root.
If author is nonempty, we ensure it is not included in the set returned
in order avoid suggesting the author as a reviewer for their own changes."""
suggested_owners = self._covering_set_of_owners_for(files, author)
if EVERYONE in suggested_owners:
if len(suggested_owners) > 1:
suggested_owners = set(['<anyone>'])
return suggested_owners
def files_not_covered_by(self, files, reviewers):
"""Returns the files not owned by one of the reviewers.
files is a sequence of paths relative to (and under) self.root.
reviewers is a sequence of strings matching self.email_regexp.
return set(f for f in files if not self._is_obj_covered_by(f, reviewers))
def _check_paths(self, files):
def _is_under(f, pfx):
return self.os_path.abspath(self.os_path.join(pfx, f)).startswith(pfx)
assert all(not self.os_path.isabs(f) and
_is_under(f, self.os_path.abspath(self.root)) for f in files)
def _check_reviewers(self, reviewers):
assert all(self.email_regexp.match(r) for r in reviewers), reviewers
def _is_obj_covered_by(self, objname, reviewers):
reviewers = list(reviewers) + [EVERYONE]
while True:
for reviewer in reviewers:
for owned_pattern in self._owners_to_paths.get(reviewer, set()):
if fnmatch.fnmatch(objname, owned_pattern):
return True
if self._should_stop_looking(objname):
objname = self.os_path.dirname(objname)
return False
def enclosing_dir_with_owners(self, objname):
"""Returns the innermost enclosing directory that has an OWNERS file."""
dirpath = objname
while not self._owners_for(dirpath):
if self._should_stop_looking(dirpath):
dirpath = self.os_path.dirname(dirpath)
return dirpath
def load_data_needed_for(self, files):
for f in files:
dirpath = self.os_path.dirname(f)
while not self._owners_for(dirpath):
self._read_owners(self.os_path.join(dirpath, 'OWNERS'))
if self._should_stop_looking(dirpath):
dirpath = self.os_path.dirname(dirpath)
def _should_stop_looking(self, objname):
return any(self._fnmatch(objname, stop_looking)
for stop_looking in self._stop_looking)
def _owners_for(self, objname):
obj_owners = set()
for owned_path, path_owners in self._paths_to_owners.iteritems():
if self._fnmatch(objname, owned_path):
obj_owners |= path_owners
return obj_owners
def _read_owners(self, path):
owners_path = self.os_path.join(self.root, path)
if not (self.os_path.exists(owners_path) or (path in self.override_files)):
if owners_path in self.read_files:
is_toplevel = path == 'OWNERS'
comment = []
dirpath = self.os_path.dirname(path)
in_comment = False
# We treat the beginning of the file as an blank line.
previous_line_was_blank = True
reset_comment_after_use = False
lineno = 0
if path in self.override_files:
file_iter = self.override_files[path]
file_iter = self.fopen(owners_path)
for line in file_iter:
lineno += 1
line = line.strip()
if line.startswith('#'):
if is_toplevel:
m = re.match('#\s*OWNERS_STATUS\s+=\s+(.+)$', line)
if m:
self._status_file =
if not in_comment:
comment = []
reset_comment_after_use = not previous_line_was_blank
in_comment = True
in_comment = False
if line == '':
comment = []
previous_line_was_blank = True
previous_line_was_blank = False
if line == 'set noparent':
m = re.match('per-file (.+)=(.+)', line)
if m:
glob_string =
directive =
full_glob_string = self.os_path.join(self.root, dirpath, glob_string)
if '/' in glob_string or '\\' in glob_string:
raise SyntaxErrorInOwnersFile(owners_path, lineno,
'per-file globs cannot span directories or use escapes: "%s"' %
relative_glob_string = self.os_path.relpath(full_glob_string, self.root)
self._add_entry(relative_glob_string, directive, owners_path,
lineno, '\n'.join(comment))
if reset_comment_after_use:
comment = []
if line.startswith('set '):
raise SyntaxErrorInOwnersFile(owners_path, lineno,
'unknown option: "%s"' % line[4:].strip())
self._add_entry(dirpath, line, owners_path, lineno,
' '.join(comment))
if reset_comment_after_use:
comment = []
def _read_global_comments(self):
if not self._status_file:
if not 'OWNERS' in self.read_files:
if not self._status_file:
owners_status_path = self.os_path.join(self.root, self._status_file)
if not self.os_path.exists(owners_status_path):
raise IOError('Could not find global status file "%s"' %
if owners_status_path in self.read_files:
lineno = 0
for line in self.fopen(owners_status_path):
lineno += 1
line = line.strip()
if line.startswith('#'):
if line == '':
m = re.match('(.+?):(.+)', line)
if m:
owner =
comment =
if not self.email_regexp.match(owner):
raise SyntaxErrorInOwnersFile(owners_status_path, lineno,
'invalid email address: "%s"' % owner)
self.comments.setdefault(owner, {})
self.comments[owner][GLOBAL_STATUS] = comment
raise SyntaxErrorInOwnersFile(owners_status_path, lineno,
'cannot parse status entry: "%s"' % line.strip())
def _add_entry(self, owned_paths, directive, owners_path, lineno, comment):
if directive == 'set noparent':
elif directive.startswith('file:'):
include_file = self._resolve_include(directive[5:], owners_path)
if not include_file:
raise SyntaxErrorInOwnersFile(owners_path, lineno,
('%s does not refer to an existing file.' % directive[5:]))
included_owners = self._read_just_the_owners(include_file)
for owner in included_owners:
self._owners_to_paths.setdefault(owner, set()).add(owned_paths)
self._paths_to_owners.setdefault(owned_paths, set()).add(owner)
elif self.email_regexp.match(directive) or directive == EVERYONE:
if comment:
self.comments.setdefault(directive, {})
self.comments[directive][owned_paths] = comment
self._owners_to_paths.setdefault(directive, set()).add(owned_paths)
self._paths_to_owners.setdefault(owned_paths, set()).add(directive)
raise SyntaxErrorInOwnersFile(owners_path, lineno,
('"%s" is not a "set noparent", file include, "*", '
'or an email address.' % (directive,)))
def _resolve_include(self, path, start):
if path.startswith('//'):
include_path = path[2:]
assert start.startswith(self.root)
start = self.os_path.dirname(self.os_path.relpath(start, self.root))
include_path = self.os_path.join(start, path)
if include_path in self.override_files:
return include_path
owners_path = self.os_path.join(self.root, include_path)
if not self.os_path.exists(owners_path):
return None
return include_path
def _read_just_the_owners(self, include_file):
if include_file in self._included_files:
return self._included_files[include_file]
owners = set()
self._included_files[include_file] = owners
lineno = 0
if include_file in self.override_files:
file_iter = self.override_files[include_file]
file_iter = self.fopen(self.os_path.join(self.root, include_file))
for line in file_iter:
lineno += 1
line = line.strip()
if (line.startswith('#') or line == '' or
line.startswith('set noparent') or
if self.email_regexp.match(line) or line == EVERYONE:
if line.startswith('file:'):
sub_include_file = self._resolve_include(line[5:], include_file)
sub_owners = self._read_just_the_owners(sub_include_file)
raise SyntaxErrorInOwnersFile(include_file, lineno,
('"%s" is not a "set noparent", file include, "*", '
'or an email address.' % (line,)))
return owners
def _covering_set_of_owners_for(self, files, author):
dirs_remaining = set(self.enclosing_dir_with_owners(f) for f in files)
all_possible_owners = self.all_possible_owners(dirs_remaining, author)
suggested_owners = set()
while dirs_remaining and all_possible_owners:
owner = self.lowest_cost_owner(all_possible_owners, dirs_remaining)
dirs_to_remove = set(el[0] for el in all_possible_owners[owner])
dirs_remaining -= dirs_to_remove
# Now that we've used `owner` and covered all their dirs, remove them
# from consideration.
del all_possible_owners[owner]
for o, dirs in all_possible_owners.items():
new_dirs = [(d, dist) for (d, dist) in dirs if d not in dirs_to_remove]
if not new_dirs:
del all_possible_owners[o]
all_possible_owners[o] = new_dirs
return suggested_owners
def all_possible_owners(self, dirs, author):
"""Returns a dict of {potential owner: (dir, distance)} mappings.
A distance of 1 is the lowest/closest possible distance (which makes the
subsequent math easier).
all_possible_owners = {}
for current_dir in dirs:
dirname = current_dir
distance = 1
while True:
for owner in self._owners_for(dirname):
if author and owner == author:
all_possible_owners.setdefault(owner, [])
# If the same person is in multiple OWNERS files above a given
# directory, only count the closest one.
if not any(current_dir == el[0] for el in all_possible_owners[owner]):
all_possible_owners[owner].append((current_dir, distance))
if self._should_stop_looking(dirname):
dirname = self.os_path.dirname(dirname)
distance += 1
return all_possible_owners
def _fnmatch(self, filename, pattern):
"""Same as fnmatch.fnmatch(), but interally caches the compiled regexes."""
matcher = self._fnmatch_cache.get(pattern)
if matcher is None:
matcher = re.compile(fnmatch.translate(pattern)).match
self._fnmatch_cache[pattern] = matcher
return matcher(filename)
def total_costs_by_owner(all_possible_owners, dirs):
# We want to minimize both the number of reviewers and the distance
# from the files/dirs needing reviews. The "pow(X, 1.75)" below is
# an arbitrarily-selected scaling factor that seems to work well - it
# will select one reviewer in the parent directory over three reviewers
# in subdirs, but not one reviewer over just two.
result = {}
for owner in all_possible_owners:
total_distance = 0
num_directories_owned = 0
for dirname, distance in all_possible_owners[owner]:
if dirname in dirs:
total_distance += distance
num_directories_owned += 1
if num_directories_owned:
result[owner] = (total_distance /
pow(num_directories_owned, 1.75))
return result
def lowest_cost_owner(all_possible_owners, dirs):
total_costs_by_owner = Database.total_costs_by_owner(all_possible_owners,
# Return the lowest cost owner. In the case of a tie, pick one randomly.
lowest_cost = min(total_costs_by_owner.itervalues())
lowest_cost_owners = filter(
lambda owner: total_costs_by_owner[owner] == lowest_cost,
return random.Random().choice(lowest_cost_owners)