scripts: add build_step logging functions

Signed-off-by: Niels de Vos <ndevos@redhat.com>

scripts/build_step.inc.sh

@@ -0,0 +1,33 @@
+#!/bin/sh
+
+# variables used for logging build steps, use build_step() and
+# build_step_done() for setting or clearing them.
+BUILD_STEP_FILE="$(mktemp)"
+BUILD_STEP_PID=''
+BUILD_STEP_DELAY='1m'
+
+build_step_log() {
+	echo "$(date) -- ${*}"
+}
+
+# start a build step, and log every
+build_step() {
+	echo "${*}" > "${BUILD_STEP_FILE}"
+	build_step_log "starting: $(cat "${BUILD_STEP_FILE}")"
+	[ -n "${BUILD_STEP_PID}" ] && return
+	while sleep "${BUILD_STEP_DELAY}"
+	do
+		build_step_log "running: $(cat "${BUILD_STEP_FILE}")"
+	done & BUILD_STEP_PID=${!}
+}
+
+# clean up the logging of build steps
+build_steps_cleanup() {
+	[ -n "${BUILD_STEP_PID}" ] && kill "${BUILD_STEP_PID}"
+	rm -f "${BUILD_STEP_FILE}"
+	BUILD_STEP_PID=''
+}
+
+# automatically stop build step logging and cleanup temporary file
+trap build_steps_cleanup EXIT
+