From d0273411d1fa18ee0b39fd3e622c9e07e110c48d Mon Sep 17 00:00:00 2001
From: "J. Avila" <elavila@google.com>
Date: Tue, 4 May 2021 20:12:14 +0000
Subject: [PATCH] build_slider: Inform the user of aosp diffs if BUILD_KERNEL
 unset

If BUILD_KERNEL is not set, it defaults to 0; i.e. it uses prebuilts. If
the user, however, has changes in aosp/, they may not be aware that
their changes didn't build. Add a check at the end to inform them and
recommend explicitly setting BUILD_KERNEL if they're making any changes
to the aosp/ directory.

Bug: 184667897
Signed-off-by: J. Avila <elavila@google.com>
Change-Id: I2d9ca9283c34e6296007bb1b7eae26cc06b7a672
---
 build_slider.sh | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/build_slider.sh b/build_slider.sh
index cfd49d4598f5..33a197476774 100755
--- a/build_slider.sh
+++ b/build_slider.sh
@@ -50,10 +50,12 @@ GKI_PREBUILTS_DIR=$(readlink -m "prebuilts/boot-artifacts/kernel/")
 DEFAULT_CONFIG="private/gs-google/build.config.slider"
 DEVICE_KERNEL_BUILD_CONFIG=${DEVICE_KERNEL_BUILD_CONFIG:-${DEFAULT_CONFIG}}
 TRIM_NONLISTED_KMI=${TRIM_NONLISTED_KMI:-1}
+CHECK_DIRTY_AOSP=0
 if [ -z "${BUILD_KERNEL}" ]; then
   if [ "${EXPERIMENTAL_BUILD}" != "0" -o -n "${GKI_DEFCONFIG_FRAGMENT}" ]; then
     BUILD_KERNEL=1
   else
+    CHECK_DIRTY_AOSP=1
     BUILD_KERNEL=0
   fi
 fi
@@ -115,3 +117,26 @@ else
   copy_gki_prebuilts
 fi
 build_pixel
+
+# If BUILD_KERNEL is not explicitly set, be sure that there are no aosp/
+# changes not present in the prebuilt.
+if [ "${CHECK_DIRTY_AOSP}" != "0" ]; then
+  PREBUILTS_SHA=$(strings ${GKI_PREBUILTS_DIR}/vmlinux |
+		      grep "Linux version 5.10" |
+		      sed -n "s/^.*-g\([0-9a-f]\{12\}\)-.*/\1/p")
+  pushd aosp/ > /dev/null
+    # The AOSP sha can sometimes be longer than 12 characters; fix its length.
+    AOSP_SHA=$(git log -1 --abbrev=12 --pretty="format:%h")
+    if [ "${PREBUILTS_SHA}" != "${AOSP_SHA}" -o -n \
+         "$(git --no-optional-locks status -uno --porcelain ||
+            git diff-index --name-only HEAD)" ]; then
+      echo "WARNING: There are aosp/ changes which are not in the prebuilts."
+      echo "  Because you did not specify BUILD_KERNEL=0 or 1, $0"
+      echo "  defaulted to building with the prebuilts. Please be aware that"
+      echo "  your changes to aosp/ will not be present in the final images. If"
+      echo "  you have made changes to aosp/, it is recommended to explicitly"
+      echo "  set BUILD_KERNEL=0 if you wish to use the prebuilts, or to 1 if"
+      echo "  you wish to build any local changes you may have."
+    fi
+  popd > /dev/null
+fi