1 files changed, 34 insertions, 19 deletions

diff --git a/meta/classes/reproducible_build.bbclass b/meta/classes/reproducible_build.bbclass
index b44053d076..2b402b9966 100644
--- a/meta/classes/reproducible_build.bbclass
+++ b/meta/classes/reproducible_build.bbclass
@@ -1,17 +1,38 @@
 # reproducible_build.bbclass
 #
-# Sets SOURCE_DATE_EPOCH in each component's build environment.
+# 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/
 #
-# After sources are unpacked but before they are patched, we set a reproducible value for SOURCE_DATE_EPOCH.
-# This value should be reproducible for anyone who builds the same revision from the same sources.
+# 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 (or set to 0) 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 we determine SOURCE_DATE_EPOCH:
+# 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.
+#    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:
@@ -22,20 +43,16 @@
 # 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.
+# 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.
+# 5. Fall back to a fixed timestamp (SOURCE_DATE_EPOCH_FALLBACK).
 #
-# Once the value of SOURCE_DATE_EPOCH is determined, it is stored in the recipe's SDE_FILE.
-# If none of these mechanisms are suitable, replace the do_deploy_source_date_epoch task
-# with recipe-specific functionality to write the appropriate SOURCE_DATE_EPOCH into the SDE_FILE.
-#
-# If this file is found by other tasks, the value is exported in the SOURCE_DATE_EPOCH variable.
-# SOURCE_DATE_EPOCH is set for all tasks that might use it (do_configure, do_compile, do_package, ...)
+# Once the value is determined, it is stored in the recipe's SDE_FILE.
 
 BUILD_REPRODUCIBLE_BINARIES ??= '1'
-inherit ${@oe.utils.ifelse(d.getVar('BUILD_REPRODUCIBLE_BINARIES') == '1', 'reproducible_build_simple', '')}
+inherit reproducible_build_simple
 
 SDE_DIR = "${WORKDIR}/source-date-epoch"
 SDE_FILE = "${SDE_DIR}/__source_date_epoch.txt"
@@ -89,6 +106,9 @@ python create_source_date_epoch_stamp() {
     os.rename(tmp_file, epochfile)
 }
 
+# Generate the stamp after do_unpack runs
+do_unpack[postfuncs] += "create_source_date_epoch_stamp"
+
 def get_source_date_epoch_value(d):
     epochfile = d.getVar('SDE_FILE')
     cached, efile = d.getVar('__CACHED_SOURCE_DATE_EPOCH') or (None, None)
@@ -116,8 +136,3 @@ def get_source_date_epoch_value(d):
 
 export SOURCE_DATE_EPOCH ?= "${@get_source_date_epoch_value(d)}"
 BB_HASHBASE_WHITELIST += "SOURCE_DATE_EPOCH"
-
-python () {
-    if d.getVar('BUILD_REPRODUCIBLE_BINARIES') == '1':
-        d.appendVarFlag("do_unpack", "postfuncs", " create_source_date_epoch_stamp")
-}