add build_abi.sh to create ABI dumps from build.sh builds

Add build_abi.sh as a wrapper script to build with build.sh and create
an ABI dump using abi/dump_abi.

Bug: 111449103
Change-Id: Iea773cf2ed6f3fdc577a99f42284992e0a871d25
Signed-off-by: Matthias Maennich <maennich@google.com>

2 files changed, 68 insertions, 0 deletions

diff --git a/abi/README.md b/abi/README.md
index 23541b7..55cefcb 100644
--- a/abi/README.md
+++ b/abi/README.md
@@ -28,6 +28,14 @@ there is only one option: 'libabigail' (default). A sample invocation looks as
 follows:
   $ dump_abi --linux-tree path/to/out --out-file /path/to/abidump.out
 
+To ensure a consistent environment and stable toolchain, a wrapper script is
+provided at the topmost directory of this project: `build_abi.sh`. It builds
+the kernel using `build.sh` and therefore accepts the same environment
+variables to customize the build, such as BUILD_CONFIG, CC and the various
+SKIP_* variables to speed up incremental builds. Following a successful build,
+`build_abi.sh` will create an ABI dump in the DIST_DIR of the build. A sample
+invocation from the top of the repo tree looks as follows:
+  $ BUILD_CONFIG=path/to/build.config build/build_abi.sh
 
 Comparing ABI dumps
 -------------------
diff --git a/build_abi.sh b/build_abi.sh
new file mode 100755
index 0000000..12d125e
--- /dev/null
+++ b/build_abi.sh
@@ -0,0 +1,60 @@
+#!/bin/bash
+
+# Copyright (C) 2019 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Usage:
+#   build/build_abi.sh
+#
+# The following environment variables are considered during execution:
+#
+#   ABI_OUT_TAG
+#     Customize the output file name for the abi dump. If undefined, the tag is
+#     derived from `git describe`.
+
+export ROOT_DIR=$(readlink -f $(dirname $0)/..)
+
+set -e
+set -a
+
+source "${ROOT_DIR}/build/envsetup.sh"
+
+# inject CONFIG_DEBUG_INFO=y
+export POST_DEFCONFIG_CMDS="${POST_DEFCONFIG_CMDS} : && update_config_for_abi_dump"
+function update_config_for_abi_dump() {
+    ${KERNEL_DIR}/scripts/config --file ${OUT_DIR}/.config \
+         -e CONFIG_DEBUG_INFO
+    (cd ${OUT_DIR} && \
+     make O=${OUT_DIR} $archsubarch CROSS_COMPILE=${CROSS_COMPILE} olddefconfig)
+}
+
+# delegate the actual build to build.sh
+${ROOT_DIR}/build/build.sh $*
+
+echo "========================================================"
+echo " Creating ABI dump"
+
+# create abi dump
+COMMON_OUT_DIR=$(readlink -m ${OUT_DIR:-${ROOT_DIR}/out/${BRANCH}})
+id=${ABI_OUT_TAG:-$(git -C $KERNEL_DIR describe --dirty --always)}
+abi_out_file=abi-${id}.out
+${ROOT_DIR}/build/abi/dump_abi                \
+    --linux-tree $OUT_DIR                     \
+    --out-file ${DIST_DIR}/${abi_out_file}
+
+ln -sf ${abi_out_file} ${DIST_DIR}/abi.out
+
+echo "========================================================"
+echo " ABI dump has been created at ${DIST_DIR}/${abi_out_file}"
+