devtools: add new SPDX license compliance checker

Simple script to look for drivers and scripts that
are missing requires SPDX header.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

MAINTAINERS

@@ -91,6 +91,7 @@ F: devtools/check-maintainers.sh
 F: devtools/check-forbidden-tokens.awk
 F: devtools/check-git-log.sh
 F: devtools/check-includes.sh
+F: devtools/check-spdx-tag.sh
 F: devtools/check-symbol-maps.sh
 F: devtools/checkpatches.sh
 F: devtools/get-maintainer.sh

devtools/check-spdx-tag.sh

@@ -0,0 +1,70 @@
+#! /bin/sh
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright 2020 Microsoft Corporation
+#
+# Produce a list of files with incorrect license tags
+
+errors=0
+warnings=0
+quiet=false
+verbose=false
+
+print_usage () {
+    echo "usage: $(basename $0) [-q] [-v]"
+    exit 1
+}
+
+check_spdx() {
+    if  $verbose;  then
+	echo "Files without SPDX License"
+	echo "--------------------------"
+    fi
+    git grep -L SPDX-License-Identifier -- \
+	':^.git*' ':^.ci/*' ':^.travis.yml' \
+	':^README' ':^MAINTAINERS' ':^VERSION' ':^ABI_VERSION' \
+	':^*/Kbuild' ':^*/README' \
+	':^license/' ':^config/' ':^buildtools/' \
+	':^*.cocci' ':^*.abignore' \
+	':^*.def' ':^*.map' ':^*.ini' ':^*.data' ':^*.cfg' ':^*.txt' \
+	':^*.svg' ':^*.png'\
+	> $tmpfile
+
+    errors=$(wc -l < $tmpfile)
+    $quiet || cat $tmpfile
+}
+
+check_boilerplate() {
+    if $verbose ; then
+	echo
+	echo "Files with redundant license text"
+	echo "---------------------------------"
+    fi
+
+    git grep -l Redistribution -- \
+	':^license/' ':^/devtools/check-spdx-tag.sh' > $tmpfile
+
+    warnings=$(wc -l <$tmpfile)
+    $quiet || cat $tmpfile
+}
+
+while getopts qvh ARG ; do
+	case $ARG in
+		q ) quiet=true ;;
+		v ) verbose=true ;;
+		h ) print_usage ; exit 0 ;;
+		? ) print_usage ; exit 1 ;;
+	esac
+done
+shift $(($OPTIND - 1))
+
+tmpfile=$(mktemp -t dpdk.checkspdx.XXXXXX)
+trap 'rm -f -- "$tmpfile"' INT TERM HUP EXIT
+
+check_spdx
+$quiet || echo
+
+check_boilerplate
+
+$quiet || echo
+echo "total: $errors errors, $warnings warnings"
+exit $errors

doc/guides/contributing/coding_style.rst

@@ -54,8 +54,13 @@ To document a public API, a doxygen-like format must be used: refer to :ref:`dox
 License Header
 ~~~~~~~~~~~~~~
 
-Each file should begin with a special comment containing the appropriate copyright and license for the file.
-Generally this is the BSD License, except for code for Linux Kernel modules.
+Each file must begin with a special comment containing the
+`Software Package Data Exchange (SPDX) License Identfier <https://spdx.org/using-spdx-license-identifier>`_.
+
+Generally this is the BSD License, except for code granted special exceptions.
+The SPDX licences identifier is sufficient, a file should not contain
+an additional text version of the license (boilerplate).
+
 After any copyright header, a blank line should be left before any other contents, e.g. include statements in a C file.
 
 C Preprocessor Directives