codespell: change file names, add possibility to write changes

Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>

codespell_changed_files.sh

@@ -0,0 +1,26 @@
+# Copyright 2017 Kaspar Schleiser <kaspar@schleiser.de>
+# Copyright 2014 Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de>
+# Copyright 2014 Hinnerk van Bruinehsen <h.v.bruinehsen@fu-berlin.de>
+# Copyright 2020 Jonathan Demeyer <jona.dem@gmail.com>
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+changed_files() {
+    : ${FILEREGEX:='\.([CcHh])$'}
+    : ${EXCLUDE:=''}
+    : ${DIFFFILTER:='ACMR'}
+
+    DIFFFILTER="--diff-filter=${DIFFFILTER}"
+
+    # select either all or only touched-in-branch files, filter through FILEREGEX
+    if [ -z "${BASE_BRANCH}" ]; then
+        FILES="$(git ls-tree -r --full-tree --name-only HEAD | grep -E ${FILEREGEX})"
+    else
+        FILES="$(git diff ${DIFFFILTER} --name-only ${BASE_BRANCH} | grep -E ${FILEREGEX})"
+    fi
+
+    # filter out negatives
+    echo "${FILES}" | grep -v -E ${EXCLUDE}
+}