Refactor Android.bp build modules for readability
When we compile sepolicy files into a cil file, we first gather all
sepolicy files to create a conf file, and then convert the conf file to
a cil file with checkpolicy. The problem is that checkpolicy is
sensitive to the input order; the conf file should contain statements in
a specific order: classes, initial_sid, access vectors, macros, mls,
etc.
This restriction has made Android.bp migration difficult, and we had to
create a magical module called "se_build_files" to correctly include
source files in the designated order. It works, but significant
readability problem has happened. For example, when we write
":se_build_files{.system_ext_public}", how can we easily figure out that
the tag actually includes plat public + system_ext public + reqd mask,
without taking a look at the build system code?
This change refactors the se_build_files module and se_policy_conf
module, so we can easily see the desginated files for each module, just
like we did in the Android.mk. se_policy_conf module now stably sorts
source files in an order which will make checkpolicy happy.
se_build_files module is also refactored, so one tag can represent
exactly one set of policy files, rather than doing magical works behind
the scene. For example, system_ext public policy module is changed from:
se_policy_conf {
name: "system_ext_pub_policy.conf",
// se_build_files automatically adds plat public and reqd mask
srcs: [":se_build_files{.system_ext_public}"],
}
to:
se_policy_conf {
name: "system_ext_pub_policy.conf",
// se_policy_conf automatically sorts the input files
srcs: [
":se_build_files{.plat_public}",
":se_build_files{.system_ext_public}",
":se_build_files{.reqd_mask}",
],
}
Bug: 209933272
Test: build and diff before/after
Change-Id: I97a76ed910645c1607d913fd646c27e87af0afd3
3 files changed