1#!/usr/bin/env python3 2# Copyright 2018 The Chromium Authors 3# Use of this source code is governed by a BSD-style license that can be 4# found in the LICENSE file. 5"""Returns a timestamp that approximates the build date. 6 7build_type impacts the timestamp generated, both relative to the date of the 8last recent commit: 9- default: the build date is set to the most recent first Sunday of a month at 10 5:00am. The reason is that it is a time where invalidating the build cache 11 shouldn't have major repercussions (due to lower load). 12- official: the build date is set to the time of the most recent commit. 13Either way, it is guaranteed to be in the past and always in UTC. 14""" 15 16# The requirements for the timestamp: 17# (1) for the purposes of continuous integration, longer duration 18# between cache invalidation is better, but >=1mo is preferable. 19# (2) for security purposes, timebombs would ideally be as close to 20# the actual time of the build as possible. It must be in the past. 21# (3) HSTS certificate pinning is valid for 70 days. To make CI builds enforce 22# HTST pinning, <=1mo is preferable. 23# 24# On Windows, the timestamp is also written in the PE/COFF file header of 25# executables of dlls. That timestamp and the executable's file size are 26# the only two pieces of information that identify a given executable on 27# the symbol server, so rarely changing timestamps can cause conflicts there 28# as well. We only upload symbols for official builds to the symbol server. 29 30 31import argparse 32import calendar 33import datetime 34import doctest 35import os 36import sys 37 38 39THIS_DIR = os.path.abspath(os.path.dirname(__file__)) 40 41 42def GetFirstSundayOfMonth(year, month): 43 """Returns the first sunday of the given month of the given year. 44 45 >>> GetFirstSundayOfMonth(2016, 2) 46 7 47 >>> GetFirstSundayOfMonth(2016, 3) 48 6 49 >>> GetFirstSundayOfMonth(2000, 1) 50 2 51 """ 52 weeks = calendar.Calendar().monthdays2calendar(year, month) 53 # Return the first day in the first week that is a Sunday. 54 return [date_day[0] for date_day in weeks[0] if date_day[1] == 6][0] 55 56 57def GetUnofficialBuildDate(build_date): 58 """Gets the approximate build date given the specific build type. 59 60 >>> GetUnofficialBuildDate(datetime.datetime(2016, 2, 6, 1, 2, 3)) 61 datetime.datetime(2016, 1, 3, 5, 0) 62 >>> GetUnofficialBuildDate(datetime.datetime(2016, 2, 7, 5)) 63 datetime.datetime(2016, 2, 7, 5, 0) 64 >>> GetUnofficialBuildDate(datetime.datetime(2016, 2, 8, 5)) 65 datetime.datetime(2016, 2, 7, 5, 0) 66 """ 67 68 if build_date.hour < 5: 69 # The time is locked at 5:00 am in UTC to cause the build cache 70 # invalidation to not happen exactly at midnight. Use the same calculation 71 # as the day before. 72 # See //base/build_time.cc. 73 build_date = build_date - datetime.timedelta(days=1) 74 build_date = datetime.datetime(build_date.year, build_date.month, 75 build_date.day, 5, 0, 0) 76 77 day = build_date.day 78 month = build_date.month 79 year = build_date.year 80 first_sunday = GetFirstSundayOfMonth(year, month) 81 # If our build is after the first Sunday, we've already refreshed our build 82 # cache on a quiet day, so just use that day. 83 # Otherwise, take the first Sunday of the previous month. 84 if day >= first_sunday: 85 day = first_sunday 86 else: 87 month -= 1 88 if month == 0: 89 month = 12 90 year -= 1 91 day = GetFirstSundayOfMonth(year, month) 92 return datetime.datetime( 93 year, month, day, build_date.hour, build_date.minute, build_date.second) 94 95 96def main(): 97 if doctest.testmod()[0]: 98 return 1 99 argument_parser = argparse.ArgumentParser() 100 argument_parser.add_argument( 101 'build_type', help='The type of build', choices=('official', 'default')) 102 args = argument_parser.parse_args() 103 104 # The mtime of the revision in build/util/LASTCHANGE is stored in a file 105 # next to it. Read it, to get a deterministic time close to "now". 106 # That date is then modified as described at the top of the file so that 107 # it changes less frequently than with every commit. 108 # This intentionally always uses build/util/LASTCHANGE's commit time even if 109 # use_dummy_lastchange is set. 110 lastchange_file = os.path.join(THIS_DIR, 'util', 'LASTCHANGE.committime') 111 last_commit_timestamp = int(open(lastchange_file).read()) 112 build_date = datetime.datetime.fromtimestamp(last_commit_timestamp, 113 datetime.timezone.utc) 114 115 # For official builds we want full fidelity time stamps because official 116 # builds are typically added to symbol servers and Windows symbol servers 117 # use the link timestamp as the prime differentiator, but for unofficial 118 # builds we do lots of quantization to avoid churn. 119 offset = 0 120 if args.build_type == 'official': 121 if os.name == 'nt': 122 version_path = os.path.join(THIS_DIR, os.pardir, 'chrome', 'VERSION') 123 with open(version_path) as f: 124 patch_line = f.readlines()[3].strip() 125 # Use the patch number as an offset to the build date so that multiple 126 # versions with different patch numbers built from the same source code 127 # will get different build_date values. This is critical for Windows 128 # symbol servers, to avoid collisions. 129 assert patch_line.startswith('PATCH=') 130 offset = int(patch_line[6:]) 131 else: 132 build_date = GetUnofficialBuildDate(build_date) 133 print(offset + int(calendar.timegm(build_date.utctimetuple()))) 134 return 0 135 136 137if __name__ == '__main__': 138 sys.exit(main()) 139