+# If each line in $STR is not already on a line by itself in $FILE, insert it,
+# sorting the new contents of the file and replacing $FILE with the result.
+insert_sorted_if_absent() {
+ file=$1
+ str=$2
+ test -f $file || touch $file
+ echo "$str" | sort -u - $file | cmp -s - $file \
+ || echo "$str" | sort -u - $file -o $file \
+ || exit 1
+}
+
+# Adjust $PATTERN for $VC_IGNORE_FILE and insert it with
+# insert_sorted_if_absent.
+insert_vc_ignore() {
+ vc_ignore_file="$1"
+ case $vc_ignore_file in
+ *.gitignore)
+ # A .gitignore entry that does not start with `/' applies recursively to
+ # subdirectories, so prepend `/' to every .gitignore entry.
+ pattern=`echo "$2" | sed s,^,/,`;;
+ *)
+ pattern="$2";;
+ esac
+ insert_sorted_if_absent "$vc_ignore_file" "$pattern"
+}
+
+# Die if there is no AC_CONFIG_AUX_DIR($build_aux) line in configure.ac.
+found_aux_dir=no
+grep '^[ ]*AC_CONFIG_AUX_DIR(\['"$build_aux"'\])' configure.ac \
+ >/dev/null && found_aux_dir=yes
+grep '^[ ]*AC_CONFIG_AUX_DIR('"$build_aux"')' configure.ac \
+ >/dev/null && found_aux_dir=yes
+if test $found_aux_dir = no; then
+ echo "$0: expected line not found in configure.ac. Add the following:" >&2
+ echo " AC_CONFIG_AUX_DIR([$build_aux])" >&2
+ exit 1
+fi
+
+# If $build_aux doesn't exist, create it now, otherwise some bits
+# below will malfunction. If creating it, also mark it as ignored.
+if test ! -d $build_aux; then
+ mkdir $build_aux
+ for dot_ig in x $vc_ignore; do
+ test $dot_ig = x && continue
+ insert_vc_ignore $dot_ig $build_aux
+ done
+fi
+
+echo "$0: Bootstrapping from checked-out $package sources..."