Merge remote-tracking branch 'autothing/mod-write-ifchanged'

2 files changed, 26 insertions, 0 deletions

diff --git a/build-aux/Makefile.once.head/00-write-ifchanged.mk b/build-aux/Makefile.once.head/00-write-ifchanged.mk
new file mode 100644
index 0000000..79ef1c4
--- /dev/null
+++ b/build-aux/Makefile.once.head/00-write-ifchanged.mk
@@ -0,0 +1 @@
+WRITE_IFCHANGED = $(topsrcdir)/build-aux/write-ifchanged
diff --git a/build-aux/write-ifchanged b/build-aux/write-ifchanged
new file mode 100755
index 0000000..185ceb0
--- /dev/null
+++ b/build-aux/write-ifchanged
@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+# Copyright (C) 2015  Luke Shumaker
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+outfile=$1
+tmpfile="$(dirname "$outfile")/.tmp${outfile##*/}"
+
+cat > "$tmpfile" || exit $?
+if cmp -s "$tmpfile" "$outfile"; then
+        rm -f "$tmpfile" || :
+else
+        mv -f "$tmpfile" "$outfile"
+fi