Add a merge-with-upstream script to toolchain-utils

Android wants to pull toolchain-utils more often. In order to make this
easier, let's have a script to do it.

BUG=None
TEST=The CL linked in the patch. Tried a few fun tricks to cover the
conditional logic, too.

Change-Id: If8de867b3711bf33309db7c64dc5b67e51e36423
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/1841586
Reviewed-by: Stephen Hines <srhines@google.com>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>

1 files changed, 82 insertions, 0 deletions

diff --git a/android_merge_from_upstream.sh b/android_merge_from_upstream.sh
new file mode 100755
index 00000000..cf07d4bf
--- /dev/null
+++ b/android_merge_from_upstream.sh
@@ -0,0 +1,82 @@
+#!/bin/bash -eu
+# Copyright 2019 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+#
+# This is a script crafted to make our Android friends' lives easier: when run
+# on their copy of toolchain-utils, this script will do all of the necessary
+# merging/branch creation/etc. to make keeping things up-to-date trivial.
+#
+# For example,
+# https://android-review.googlesource.com/c/platform/external/toolchain-utils/+/1132504/1
+
+local_branch_name="merge_with_upstream"
+local_upstream="aosp/master"
+remote="aosp"
+remote_branch="${remote}/upstream-mirror-master"
+
+my_dir="$(dirname "$(readlink -m "$0")")"
+cd "${my_dir}"
+
+ensure_head_is_upstream_master() {
+  local current_rev master_rev
+  current_rev="$(git rev-parse HEAD)"
+  master_rev="$(git rev-parse ${local_upstream})"
+  if [[ "${current_rev}" != "${master_rev}" ]]; then
+    echo "Please checkout ${local_upstream} and rerun this" >&2
+    exit
+  fi
+}
+
+ensure_no_local_branch_present() {
+  if ! git rev-parse "${local_branch_name}" >& /dev/null; then
+    return 0
+  fi
+
+  echo -n "${local_branch_name} is a valid branch already. Delete? [y/N] " >&2
+
+  local line
+  read -r line
+  if [[ "${line}" != y* && "${line}" != Y* ]]; then
+    echo "Aborted" >&2
+    exit 1
+  fi
+
+  # If we're *on* that branch, deleting it is difficult.
+  local current_branch
+  current_branch="$(git branch --show-current)"
+  if [[ "${current_branch}" == "${local_branch_name}" ]]; then
+    local rev
+    rev="$(git rev-parse HEAD)"
+    # This is fine, since we assume HEAD == upstream-mirror-master anyway
+    # (e.g., the existing branch was pointless.)
+    git checkout "${rev}"
+  fi
+  git branch -D "${local_branch_name}"
+}
+
+get_merge_commit_list() {
+  local merge_base
+  merge_base="$(git merge-base HEAD ${remote_branch})"
+  git log --oneline "${merge_base}..${remote_branch}"
+}
+
+ensure_head_is_upstream_master
+ensure_no_local_branch_present
+
+echo "Ensuring repository is up-to-date..."
+git fetch "${remote}"
+repo start "${local_branch_name}"
+
+commit_list="$(get_merge_commit_list)"
+num_commits="$(wc -l <<< "${commit_list}")"
+commit_message="Merging ${num_commits} commit(s) from Chromium's toolchain-utils
+
+Merged commit digest:
+$(sed 's/^/  /' <<< "${commit_list}")
+"
+
+git merge "${remote_branch}" -m "${commit_message}"
+echo 'NOTE: When you try to `repo upload`, repo might show a scary warning'
+echo 'about the number of changes are being uploaded. That should be fine,'
+echo 'since repo will only create CLs for commits not known to our remote.'