build_abi: add options to help maintaining the abi.xml

Add the options
  -u | --update         Update the abi.xml in the source directory
  -n | --nodiff         Do not generate a ABI report with abidiff
  -r | --print-report   Print ABI report in case of differences

This allows the following example usages (besides others):

  - Update the ABI and print the reported differences
    That is useful to take the report for the commit message when
    updating the abi.xml.
     $ build/build_abi.sh -r -u

  - Update the ABI and ignore any difference
    If you are not interested in the report or any existing difference,
    but just want to update the abi.xml.
     $ build/build_abi.sh -u -n

Change-Id: Ifc97b7043da6e93b90e670bab2f89796aff655ac
Signed-off-by: Matthias Maennich <maennich@google.com>

2 files changed, 80 insertions, 14 deletions

diff --git a/abi/README.md b/abi/README.md
index b8002e0..967eb2a 100644
--- a/abi/README.md
+++ b/abi/README.md
@@ -54,3 +54,12 @@ follows:
 
 The report created is tool specific, but generally lists ABI changes detected
 that affect the Kernel's module interface.
+
+Updating ABI dumps
+------------------
+To update the ABI dump, `build_abi.sh` can be invoked with the `--update` flag.
+It will update the corresponding abi.xml file that is defined via the
+build.config. It might be useful to invoke the script also with
+`--print-report` to print the differences the update cleans up. That
+information is useful in the commit message when updating the abi.xml in the
+source control.
diff --git a/build_abi.sh b/build_abi.sh
index b5c7566..b3c1b46 100755
--- a/build_abi.sh
+++ b/build_abi.sh
@@ -25,6 +25,47 @@
 
 export ROOT_DIR=$(readlink -f $(dirname $0)/..)
 
+function show_help {
+    echo "USAGE: $0 [-u|--update] [-n|--nodiff]"
+    echo
+    echo "  -u | --update         Update the abi.xml in the source directory"
+    echo "  -n | --nodiff         Do not generate a ABI report with abidiff"
+    echo "  -r | --print-report   Print ABI report in case of differences"
+}
+
+UPDATE=0
+DIFF=1
+PRINT_REPORT=0
+
+ARGS=()
+for i in "$@"
+do
+case $i in
+    -u|--update)
+    UPDATE=1
+    shift # past argument=value
+    ;;
+    -n|--nodiff)
+    DIFF=0
+    shift # past argument=value
+    ;;
+    -r|--print-report)
+    PRINT_REPORT=1
+    shift # past argument=value
+    ;;
+    -h|--help)
+    show_help
+    exit 0
+    ;;
+    *)
+    ARGS+=("$1")
+    shift
+    ;;
+esac
+done
+
+set -- "${ARGS[@]}"
+
 set -e
 set -a
 
@@ -85,20 +126,36 @@ ln -sf ${abi_out_file} ${DIST_DIR}/abi.xml
 echo "========================================================"
 echo " ABI dump has been created at ${DIST_DIR}/${abi_out_file}"
 
+rc=0
 if [ -n "$ABI_DEFINITION" ]; then
-    echo "========================================================"
-    echo " Comparing ABI against expected definition ($ABI_DEFINITION)"
-    abi_report=${DIST_DIR}/abi.report
-    set +e
-    ${ROOT_DIR}/build/abi/diff_abi --baseline $KERNEL_DIR/$ABI_DEFINITION \
-                                   --new      ${DIST_DIR}/${abi_out_file} \
-                                   --report   ${abi_report}
-    rc=$?
-    set -e
-    echo "========================================================"
-    echo " ABI report has been created at ${abi_report}"
-    if [ $rc -ne 0 ] ; then
-        echo " ABI DIFFERENCES HAVE BEEN DETECTED! (RC=$rc)"
-        exit $rc
+    if [ $DIFF -eq 1 ]; then
+        echo "========================================================"
+        echo " Comparing ABI against expected definition ($ABI_DEFINITION)"
+        abi_report=${DIST_DIR}/abi.report
+        set +e
+        ${ROOT_DIR}/build/abi/diff_abi --baseline $KERNEL_DIR/$ABI_DEFINITION \
+                                       --new      ${DIST_DIR}/${abi_out_file} \
+                                       --report   ${abi_report}
+        rc=$?
+        set -e
+        echo "========================================================"
+        echo " ABI report has been created at ${abi_report}"
+
+        if [ $rc -ne 0 ]; then
+            echo " ABI DIFFERENCES HAVE BEEN DETECTED! (RC=$rc)"
+        fi
+
+        if [ $PRINT_REPORT -eq 1 ] && [ $rc -ne 0 ] ; then
+            echo "========================================================"
+            cat ${abi_report}
+        fi
+    fi
+    if [ $UPDATE -eq 1 ] ; then
+        echo "========================================================"
+        echo " Updating expected ABI definition ($ABI_DEFINITION)"
+        cp -v ${DIST_DIR}/${abi_out_file} $KERNEL_DIR/$ABI_DEFINITION
     fi
 fi
+
+exit $rc
+