[Buildroot] [PATCH v2 1/5] package/kmod: add modules-load init script

[unixmania at gmail.com]

From: Carlos Santos <unixmania at gmail.com>

Use some scripting to mimic the systemd "modules-load" and the OpenRC
"modules" services (load kernel modules based on static configuration).

The configuration files should simply contain a list of kernel module
names to load, separated by newlines. Empty lines and lines whose first
non-whitespace character is # or ; are ignored.

The configuration directory list and file format is the same as the one
described in modules-load.d(5). Files are loaded in the following order:

  /etc/modules-load.d/*.conf
  /run/modules-load.d/*.conf
  /usr/lib/modules-load.d/*.conf

This roughly mimics the logic used by systemd but the files are not
sorted by their filename in lexicographic order as systemd does.

Notice that OpenRC uses /etc/modules-load.d/*.conf, only, and does not
ignore lines beginning with ';'.

The file redirections do the following:

- stdout is redirected to syslog with facility.level "kern.info"
- stderr is redirected to syslog with facility.level "kern.err"
- file dscriptor 4 is used to pass the result to the "start" function.

Signed-off-by: Carlos Santos <unixmania at gmail.com>
---
CC: "Yann E. MORIN" <yann.morin.1998 at free.fr>
---
Changes v1->v2:
- Redirect output to syslog only if /usr/bin/logger exists, as made in
  package/procps-ng/S02sysctl.
- Use the MODULES_LOAD_ARGS variable, optionally set in
  /etc/default/modules-load.
- Rename S02modules-load to S11modules-load to ensure that it runs after
  S10mdev and S10udev, which both are going to trigger cold-plug events
  that may in turn trigger module loading, as observed by Yann E. MORIN.
- Prevent the installation of S11modules-load with openrc, which already
  provides the /etc/init.d/modules script.
- Reorganize the comments in S11modules-load.
---
 package/kmod/S11modules-load | 115 +++++++++++++++++++++++++++++++++++
 package/kmod/kmod.mk         |  10 +++
 2 files changed, 125 insertions(+)
 create mode 100644 package/kmod/S11modules-load

diff --git a/package/kmod/S11modules-load b/package/kmod/S11modules-load
new file mode 100644
index 0000000000..9010230e23
--- /dev/null
+++ b/package/kmod/S11modules-load
@@ -0,0 +1,115 @@
+#!/bin/sh
+#
+# Use some scripting to mimic the systemd "modules-load" and the OpenRC
+# "modules" services (load kernel modules based on static configuration).
+#
+# The configuration files should simply contain a list of kernel module
+# names to load, separated by newlines. Empty lines and lines whose first
+# non-whitespace character is # or ; are ignored.
+#
+# The configuration directory list and file format is the same as the one
+# described in modules-load.d(5). Files are loaded in the following order:
+#
+#   /etc/modules-load.d/*.conf
+#   /run/modules-load.d/*.conf
+#   /usr/lib/modules-load.d/*.conf
+#
+# This roughly mimics the logic used by systemd but the files are not sorted
+# by their filename in lexicographic order as systemd does.
+#
+# Notice that OpenRC uses /etc/modules-load.d/*.conf, only, and does not
+# ignore lines beginning with ';'.
+#
+
+PROGRAM="modules-load"
+
+MODULES_LOAD_ARGS=""
+
+# Add "-q" to MODULES_LOAD_ARGS to disable error messages.
+# shellcheck source=/dev/null
+[ -r "/etc/default/$PROGRAM" ] && . "/etc/default/$PROGRAM"
+
+# Files are read from directories in the MODULES_SOURCES list, in the given
+# order. A file may be used more than once, since there can be multiple
+# symlinks to it. No attempt is made to prevent this.
+MODULES_SOURCES="/etc/modules-load.d/ /run/modules-load.d/ /usr/lib/modules-load.d/"
+
+# If the logger utility is available all messages are sent to syslog, except
+# for the final status. The file redirections do the following:
+#
+# - stdout is redirected to syslog with facility.level "kern.info"
+# - stderr is redirected to syslog with facility.level "kern.err"
+# - file dscriptor 4 is used to pass the result to the "start" function.
+#
+run_logger() {
+	# shellcheck disable=SC2086 # we need the word splitting
+	find $MODULES_SOURCES -maxdepth 1 -name '*.conf' -print0 2> /dev/null | \
+	xargs -0 -r -n 1 readlink -f | {
+		prog_status="OK"
+		while :; do
+			read -r file || {
+				echo "$prog_status" >&4
+				break
+			}
+			echo "* Applying $file ..."
+			while :; do
+				read -r mod || break
+				case "$mod" in
+					''|'#'*|';'*) ;;
+					*) /sbin/modprobe $MODULES_LOAD_ARGS "$mod" || prog_status="FAIL"
+				esac
+			done < "$file"
+		done 2>&1 >&3 | /usr/bin/logger -t "$PROGRAM" -p kern.err
+	} 3>&1 | /usr/bin/logger -t "$PROGRAM" -p kern.info
+}
+
+# If logger is not available all messages are sent to stdout/stderr.
+run_std() {
+	# shellcheck disable=SC2086 # we need the word splitting
+	find $MODULES_SOURCES -maxdepth 1 -name '*.conf' -print0 2> /dev/null | \
+	xargs -0 -r -n 1 readlink -f | {
+		prog_status="OK"
+		while :; do
+			read -r file || {
+				echo "$prog_status" >&4
+				break
+			}
+			echo "* Applying $file ..."
+			while :; do
+				read -r mod || break
+				case "$mod" in
+					''|'#'*|';'*) ;;
+					*) /sbin/modprobe $MODULES_LOAD_ARGS "$mod" || prog_status="FAIL"
+				esac
+			done < "$file"
+		done
+	}
+}
+
+if [ -x /usr/bin/logger ]; then
+	run_program="run_logger"
+else
+	run_program="run_std"
+fi
+
+start() {
+	printf '%s %s: ' "$1" "$PROGRAM"
+	status=$("$run_program" 4>&1)
+	echo "$status"
+	if [ "$status" = "OK" ]; then
+		return 0
+	fi
+	return 1
+}
+
+case "$1" in
+	start)
+		start "Running";;
+	restart|reload)
+		start "Rerunning";;
+	stop)
+		:;;
+	*)
+		echo "Usage: $0 {start|stop|restart|reload}"
+		exit 1
+esac
diff --git a/package/kmod/kmod.mk b/package/kmod/kmod.mk
index e2dfea5c7b..9b6735e2d0 100644
--- a/package/kmod/kmod.mk
+++ b/package/kmod/kmod.mk
@@ -60,6 +60,16 @@ else
 KMOD_BIN_PATH = ../usr/bin/kmod
 endif
 
+# Avoid installing S11modules-load, since openrc provides /etc/init.d/modules.
+define KMOD_INSTALL_INIT_OPENRC
+	@:
+endef
+
+define KMOD_INSTALL_INIT_SYSV
+	$(INSTALL) -m 0755 -D package/kmod/S11modules-load \
+		$(TARGET_DIR)/etc/init.d/S11modules-load
+endef
+
 define KMOD_INSTALL_TOOLS
 	for i in depmod insmod lsmod modinfo modprobe rmmod; do \
 		ln -sf $(KMOD_BIN_PATH) $(TARGET_DIR)/sbin/$$i; \
-- 
2.18.2