diff options
Diffstat (limited to 'poky/meta/lib/oe/reproducible.py')
-rw-r--r-- | poky/meta/lib/oe/reproducible.py | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/poky/meta/lib/oe/reproducible.py b/poky/meta/lib/oe/reproducible.py index 204b9bd734..4fb99d963c 100644 --- a/poky/meta/lib/oe/reproducible.py +++ b/poky/meta/lib/oe/reproducible.py @@ -5,6 +5,57 @@ import os import subprocess import bb +# For reproducible builds, this code sets the default SOURCE_DATE_EPOCH in each +# component's build environment. The format is number of seconds since the +# system epoch. +# +# Upstream components (generally) respect this environment variable, +# using it in place of the "current" date and time. +# See https://reproducible-builds.org/specs/source-date-epoch/ +# +# The default value of SOURCE_DATE_EPOCH comes from the function +# get_source_date_epoch_value which reads from the SDE_FILE, or if the file +# is not available will use the fallback of SOURCE_DATE_EPOCH_FALLBACK. +# +# The SDE_FILE is normally constructed from the function +# create_source_date_epoch_stamp which is typically added as a postfuncs to +# the do_unpack task. If a recipe does NOT have do_unpack, it should be added +# to a task that runs after the source is available and before the +# do_deploy_source_date_epoch task is executed. +# +# If a recipe wishes to override the default behavior it should set it's own +# SOURCE_DATE_EPOCH or override the do_deploy_source_date_epoch_stamp task +# with recipe-specific functionality to write the appropriate +# SOURCE_DATE_EPOCH into the SDE_FILE. +# +# SOURCE_DATE_EPOCH is intended to be a reproducible value. This value should +# be reproducible for anyone who builds the same revision from the same +# sources. +# +# There are 4 ways the create_source_date_epoch_stamp function determines what +# becomes SOURCE_DATE_EPOCH: +# +# 1. Use the value from __source_date_epoch.txt file if this file exists. +# This file was most likely created in the previous build by one of the +# following methods 2,3,4. +# Alternatively, it can be provided by a recipe via SRC_URI. +# +# If the file does not exist: +# +# 2. If there is a git checkout, use the last git commit timestamp. +# Git does not preserve file timestamps on checkout. +# +# 3. Use the mtime of "known" files such as NEWS, CHANGLELOG, ... +# This works for well-kept repositories distributed via tarball. +# +# 4. Use the modification time of the youngest file in the source tree, if +# there is one. +# This will be the newest file from the distribution tarball, if any. +# +# 5. Fall back to a fixed timestamp (SOURCE_DATE_EPOCH_FALLBACK). +# +# Once the value is determined, it is stored in the recipe's SDE_FILE. + def get_source_date_epoch_from_known_files(d, sourcedir): source_date_epoch = None newest_file = None @@ -106,3 +157,36 @@ def get_source_date_epoch(d, sourcedir): fixed_source_date_epoch(d) # Last resort ) +def epochfile_read(epochfile, d): + cached, efile = d.getVar('__CACHED_SOURCE_DATE_EPOCH') or (None, None) + if cached and efile == epochfile: + return cached + + if cached and epochfile != efile: + bb.debug(1, "Epoch file changed from %s to %s" % (efile, epochfile)) + + source_date_epoch = int(d.getVar('SOURCE_DATE_EPOCH_FALLBACK')) + try: + with open(epochfile, 'r') as f: + s = f.read() + try: + source_date_epoch = int(s) + except ValueError: + bb.warn("SOURCE_DATE_EPOCH value '%s' is invalid. Reverting to SOURCE_DATE_EPOCH_FALLBACK" % s) + source_date_epoch = int(d.getVar('SOURCE_DATE_EPOCH_FALLBACK')) + bb.debug(1, "SOURCE_DATE_EPOCH: %d" % source_date_epoch) + except FileNotFoundError: + bb.debug(1, "Cannot find %s. SOURCE_DATE_EPOCH will default to %d" % (epochfile, source_date_epoch)) + + d.setVar('__CACHED_SOURCE_DATE_EPOCH', (str(source_date_epoch), epochfile)) + return str(source_date_epoch) + +def epochfile_write(source_date_epoch, epochfile, d): + + bb.debug(1, "SOURCE_DATE_EPOCH: %d" % source_date_epoch) + bb.utils.mkdirhier(os.path.dirname(epochfile)) + + tmp_file = "%s.new" % epochfile + with open(tmp_file, 'w') as f: + f.write(str(source_date_epoch)) + os.rename(tmp_file, epochfile) |