4 files changed, 103 insertions, 0 deletions
diff --git a/build-aux/get-dscname b/build-aux/get-dscname
new file mode 100755
index 0000000..c8b3681
--- /dev/null
+++ b/build-aux/get-dscname
@@ -0,0 +1,12 @@
+#!/bin/sh
+# build-aux/get-dscname - Get a file's self-described filename
+#
+# Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+if [ $# -ne 1 ]; then
+	echo "$0: expected exactly 1 argument"
+	exit 2
+fi
+
+sed -n '1,3{ /^\#!/d; /^<!--$/d; /-\*- .* -\*-/d; s,[/*\# ]*,,; s/ - .*//;p; q; }' -- "$1"
diff --git a/build-aux/lint-generic b/build-aux/lint-generic
new file mode 100755
index 0000000..c02dc34
--- /dev/null
+++ b/build-aux/lint-generic
@@ -0,0 +1,54 @@
+#!/bin/sh
+# build-aux/lint-generic - Non-language-specific lint checks
+#
+# Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+RED=$(tput setaf 1)
+RESET=$(tput sgr0)
+
+err() {
+	printf "${RED}%s${RESET}: %s\n" "$1" "$2" >&2
+	r=1
+}
+
+r=0
+for filename in "$@"; do
+	if ! { [ -f "$filename" ] && ! [ -h "$filename" ]; }; then
+		# Ignore non-files
+		continue
+	fi
+
+	# File header ##########################################################
+
+	shebang="$(sed -n '1{/^#!/{/^#!\/hint\//q; p;};}' "$filename")"
+	if [ -x "$filename" ] && [ -z "$shebang" ]; then
+		err "$filename" 'is executable but does not have a shebang'
+	elif [ -n "$shebang" ] && ! [ -x "$filename" ]; then
+		err "$filename" 'has a shebang but is executable'
+	fi
+
+	if ! grep -E -q 'Copyright \(C\) 202[4-9]((-|, )202[5-9])*  Luke T. Shumaker' "$filename"; then
+		err "$filename" 'is missing a copyright statement'
+	fi
+	if ! grep -q ' SPDX-License-Identifier[:] ' "$filename"; then
+		err "$filename" 'is missing an SPDX-License-Identifier'
+	fi
+
+	dscname_act=$(./build-aux/get-dscname "$filename")
+	dscname_exp=$(echo "$filename" | sed \
+		-e 's,.*/config/,,' \
+		-e 's,.*/config\.h$,config.h,' \
+		-e 's,.*include/,,' \
+		-e 's/\.wip$//')
+	if [ "$dscname_act" != "$dscname_exp" ] && [ "cmd/$dscname_act" != "$dscname_exp" ]; then
+		err "$filename" "self-identifies as $dscname_act (expected $dscname_exp)"
+	fi
+
+	# File body ############################################################
+
+	if grep -n --color=auto "$(printf '\\S\t')" "$filename"; then
+		err "$filename" 'uses tabs for alignment'
+	fi
+done
+exit $r
diff --git a/build-aux/lint-h b/build-aux/lint-h
new file mode 100755
index 0000000..26ac13d
--- /dev/null
+++ b/build-aux/lint-h
@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+# build-aux/lint-h - Lint checks for C header files
+#
+# Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+RED=$(tput setaf 1)
+RESET=$(tput sgr0)
+
+err() {
+	printf "${RED}%s${RESET}: %s\n" "$1" "$2" >&2
+	r=1
+}
+
+r=0
+for filename in "$@"; do
+	dscname=$(./build-aux/get-dscname "$filename")
+	guard=${dscname//'/'/'_'}
+	guard=${guard//'.'/'_'}
+	guard="_${guard^^}_"
+	if ! { grep -Fxq "#ifndef ${guard}"      "$filename" &&
+	       grep -Fxq "#define ${guard}"      "$filename" &&
+	       grep -Fxq "#endif /* ${guard} */" "$filename"; }; then
+		err "$filename" "does not have ${guard} guard"
+	fi
+done
+exit $r
diff --git a/build-aux/lint-unknown b/build-aux/lint-unknown
new file mode 100755
index 0000000..3c2e91b
--- /dev/null
+++ b/build-aux/lint-unknown
@@ -0,0 +1,10 @@
+#!/bin/sh
+# build-aux/lint-unknown - Lint checks for unknown files
+#
+# Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+RED=$(tput setaf 1)
+RESET=$(tput sgr0)
+
+printf "${RED}%s${RESET}: cannot lint unknown file type\n" "$@" >&2