[PATCH] install-qa-check.d: Add a QA check for installing xattrs

Warn the developers if ebuilds install files with xattrs to ${ED}.
The xattrs may or may not be preserved when installing the package,
making them unreliable on one hand, and somewhat suprising in other
cases (e.g. when they unintentionally leak from developer's system).

This is the first step towards restoring PMS compliance and *not*
preserving extended metadata.

Signed-off-by: Michał Górny <[email protected]>
---
 bin/install-qa-check.d/95xattr | 54 ++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 bin/install-qa-check.d/95xattr

diff --git a/bin/install-qa-check.d/95xattr b/bin/install-qa-check.d/95xattr
new file mode 100644
index 000000000..07d8042a8
--- /dev/null
+++ b/bin/install-qa-check.d/95xattr
@@ -0,0 +1,54 @@
+# Check for xattrs.
+
+xattr_check() {
+	type -P getfattr >/dev/null || return
+
+	pushd "${ED}" >/dev/null || die
+	local x file= keys
+	local -A data=()
+	while read -r x; do
+		case ${x} in
+			"# file: "*)
+				file=${x#*: }
+				file=/${file#.}
+				;;
+			btrfs.*)
+				# ignore btrfs xattrs, they're implicit fs metadata
+				;;
+			security.capability)
+				# don't report caps if we have fcaps.eclass inherited
+				if ! has fcaps ${INHERITED}; then
+					data[${file}]+=" ${x}"
+				fi
+				;;
+			?*)
+				data[${file}]+=" ${x}"
+				;;
+		esac
+	done < <(getfattr -R -h -m - . 2>/dev/null)
+	popd >/dev/null || die
+
+	if [[ ${data[@]} ]]; then
+		eqawarn "One or more files in \${ED} include extended attributes."
+		eqawarn
+
+		for file in "${!data[@]}"; do
+			keys=( ${data[${file}]} )
+			for x in "${keys[@]}"; do
+				eqatag xattr "key=${x}" "${file}"
+			done
+			eqawarn "  ${file} (${keys[*]})"
+		done
+
+		eqawarn
+		eqawarn "It is impossible to reliably guarantee that the extended attributes"
+		eqawarn "will be reliably preserved while merging.  Please ensure that any"
+		eqawarn "extended metadata necessary is applied in pkg_postinst() phase,"
+		eqawarn "and that the implementation includes a fallback if necessary."
+	fi
+}
+
+xattr_check
+: # guarantee successful exit
+
+# vim:ft=sh
-- 
2.33.0