[PATCH] Add scripts/backport-support.sh

[fweimer at redhat dot com (Florian Weimer)]

This script is intended for maintaining the stable branches and
distribution backports.

2017-02-09  Florian Weimer  <fweimer@redhat.com>

	* scripts/backport-support.sh (latest_commit): New file.

diff --git a/scripts/backport-support.sh b/scripts/backport-support.sh
new file mode 100644
index 0000000..2ece7ce
--- /dev/null
+++ b/scripts/backport-support.sh
@@ -0,0 +1,110 @@
+#!/bin/bash
+# Create a patch which backports the support/ subdirectory.
+# Copyright (C) 2017 Free Software Foundation, Inc.
+# This file is part of the GNU C Library.
+
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+
+# The GNU C Library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <http://www.gnu.org/licenses/>.
+
+# This script does not backport the Makefile tweaks outside the
+# support/ directory (which need to be backported separately), or the
+# changes to test-skeleton.c (which should not be backported).
+
+set -e
+
+export LC_ALL=C
+export GIT_CONFIG=/dev/null
+export GTT_CONFIG_NOSYSTEM=0
+export GIT_PAGER=
+
+usage () {
+    cat >&2 <<EOF
+usage: $0 {patch|commit}
+EOF
+    exit 1
+}
+
+if test $# -ne 1 ; then
+    usage
+fi
+
+command="$1"
+
+case "$command" in
+    patch|commit)
+    ;;
+    *)
+	usage
+	;;
+esac
+
+# The upstream branch to work on.
+branch=origin/master
+
+# The commit which added the support/ directory.
+initial_commit=c23de0aacbeaa7a091609b35764bed931475a16d
+
+# We backport the support directory and this script.  Directories need
+# to end in a /.
+patch_targets="support/ scripts/backport-support.sh"
+
+latest_commit="$(git log --max-count=1 --pretty=format:%H "$branch" -- \
+  $patch_targets)"
+
+# Simplify the branch name somewhat for reporting.
+branch_name="$(echo "$branch" | sed s,^origin/,,)"
+
+command_patch () {
+    cat <<EOF
+This patch creates the contents of the support/ directory up to this
+upstream commit on the $branch_name branch:
+
+EOF
+    git log --max-count=1 "$latest_commit"
+    echo
+    git diff "$initial_commit"^.."$latest_commit" $patch_targets
+    echo "# Before applying the patch, run this command:" >&2
+    echo "# rm -rf $patch_targets" >&2
+}
+
+command_commit () {
+    git status --porcelain | while read line ; do
+	echo "error: working copy is not clean, cannot commit" >&2
+	exit 1
+    done
+    for path in $patch_targets; do
+	echo "# Processing $path" >&2
+	case "$path" in
+	    [a-zA-Z0-9]*/)
+		# Directory.
+		git rm --cached --ignore-unmatch -r "$path"
+		rm -rf "$path"
+		git read-tree --prefix="$path" "$latest_commit":"$path"
+		git checkout "$path"
+		;;
+	    *)
+		# File.
+		git show "$latest_commit":"$path" > "$path"
+		git add "$path"
+	esac
+    done
+    git commit -m "Synchronize support/ infrastructure with $branch_name
+
+This commit updates the support/ subdirectory to
+commit $latest_commit
+on the $branch_name branch.
+"
+}
+
+command_$command