main/swclock-offset: new package (MR 2191)

Some devices have a working but non-writable real-time clock (RTC).
This package contains two shell scripts: One writes the offset between
'hwclock' and 'swclock' to a file at shutdown, another one reads the
offset from the file at boot and sets the 'swclock'. This way the system
time in userspace is kept in present time.

[ci:skip-build] already built successfully in CI

.gitlab-ci/shellcheck.sh

@@ -15,6 +15,7 @@ fi
 
 # Shell: shellcheck
 sh_files="
+	./main/mdss-fb-init-hack/mdss-fb-init-hack.sh
 	./main/postmarketos-base/rootfs-usr-lib-firmwareload.sh
 	./main/postmarketos-mkinitfs/init.sh.in
 	./main/postmarketos-mkinitfs/init_functions.sh
@@ -23,7 +24,8 @@ sh_files="
 	./main/postmarketos-mkinitfs/mkinitfs_test.sh
 	./main/postmarketos-mkinitfs-hook-debug-shell/20-debug-shell.sh
 	./main/postmarketos-update-kernel/update-kernel.sh
-	./main/mdss-fb-init-hack/mdss-fb-init-hack.sh
+	./main/swclock-offset/swclock-offset-boot.sh
+	./main/swclock-offset/swclock-offset-shutdown.sh
 
 	$(find . -path './main/postmarketos-ui-*/*.sh')
 	$(find . -path './main/postmarketos-ui-*/*.pre-install')

main/swclock-offset/APKBUILD

@@ -0,0 +1,31 @@
+# Maintainer: Jakob Hauser <jahau@rocketmail.com>
+pkgname=swclock-offset
+pkgver=0.1
+pkgrel=0
+pkgdesc="Keep system time at an offset to a non-writable RTC"
+url="https://gitlab.com/postmarketOS/pmaports"
+arch="noarch"
+license="GPL-3.0-or-later"
+install="$pkgname.post-deinstall"
+subpackages="$pkgname-openrc"
+source="$pkgname-boot.initd $pkgname-shutdown.initd $pkgname-boot.sh $pkgname-shutdown.sh"
+options="!check" # No tests
+
+package() {
+	install -Dm755 "$srcdir/$pkgname-boot.initd" "$pkgdir/etc/init.d/$pkgname-boot"
+	install -Dm755 "$srcdir/$pkgname-shutdown.initd" "$pkgdir/etc/init.d/$pkgname-shutdown"
+	install -Dm755 "$srcdir/$pkgname-boot.sh" "$pkgdir/sbin/$pkgname-boot"
+	install -Dm755 "$srcdir/$pkgname-shutdown.sh" "$pkgdir/sbin/$pkgname-shutdown"
+}
+
+openrc() {
+	install="$subpkgname.post-install $subpkgname.pre-deinstall"
+	default_openrc
+}
+
+sha512sums="
+777dff161dcae742d1bfb7acbf413a319c9e623292a315ccd8cf5f3f0df9258d54d3e9891bdff741a6146ab285bc5a27c7921bc93902b4a2006104666a835ecd  swclock-offset-boot.initd
+a834fe9f721a4797f5675361fe07b500f93a2082753ed0a0fd583ccfd49738acfe04fb526e2936f3ce270053d151c7080a6a5356246fb816638e72992c6f77db  swclock-offset-shutdown.initd
+288373bef5d7e5a64d118396491b424fb9cd38bfb3e7c422762c4c1441894617e59140035cd824846880c159fe3b9f6f8ceaddd552014e53b4e0ab05da7931dc  swclock-offset-boot.sh
+49f2ac3b4f41904097d1b5e903b810abd3da005972fffc14bd34d3c25aaa9b92d293a10bfa4348e160060670ed19d50e06ac6c9b8ebe663e56bf30e36c28edf9  swclock-offset-shutdown.sh
+"

main/swclock-offset/swclock-offset-boot.initd

@@ -0,0 +1,23 @@
+#!/sbin/openrc-run
+
+# To avoid time inconsistency at filesystems check, the system time
+# shall be set before "fsck".
+
+description="Setting the system time according to an offset file."
+
+depend()
+{
+	before fsck
+}
+
+start()
+{
+	ebegin "Setting system time"
+	/sbin/swclock-offset-boot
+	eend $?
+}
+
+stop()
+{
+	return 0
+}

main/swclock-offset/swclock-offset-boot.sh

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+# This shell scripts reads the offset from the file and sets the 'swclock'.
+#
+# To keep the offset calculation simple, the epoch timestamp is used.
+#
+# The RTC is read from the sysfs node.
+#
+# To set the system time, command "date" is used. The "@" sign marks an
+# epoch time format. As the "date" command offers no quiet option, the
+# output is written to the null device.
+
+rtc_sys_node="/sys/class/rtc/rtc0/since_epoch"
+offset_file="/var/cache/swclock-offset/offset-storage"
+
+# check presence of rtc sys node
+if [ ! -f $rtc_sys_node ]; then
+  exit 1
+fi
+
+# check presence of offset file
+if [ ! -f $offset_file ]; then
+  exit 2
+fi
+
+# calculate system time
+hwclock_epoch=$(cat $rtc_sys_node)
+offset_epoch=$(cat $offset_file)
+swclock_epoch=$((hwclock_epoch + offset_epoch))
+
+# set system time, dump output
+date --utc --set=@$swclock_epoch > /dev/null

main/swclock-offset/swclock-offset-openrc.post-install

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+# The service "osclock" is a dummy service simply providing "clock".
+# This avoids other services that need "clock" to call the service
+# "hwclock".
+#
+# The service "swclock-offset-boot" needs to run after the sysfs has
+# been mounted. As the sysfs is mounted in runlevel sysinit, assigning
+# the service to runlevel boot is enough to keep the order.
+
+# replace service hwclock by osclock
+rc-update -q del hwclock boot
+rc-update -q add osclock boot
+
+# assign swclock-offset services to runlevels
+rc-update -q add swclock-offset-boot boot
+rc-update -q add swclock-offset-shutdown shutdown

main/swclock-offset/swclock-offset-openrc.pre-deinstall

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+# This script restores the original state.
+
+# remove swclock-offset services
+rc-update -q del swclock-offset-boot boot
+rc-update -q del swclock-offset-shutdown shutdown
+
+# replace service osclock by hwclock
+rc-update -q del osclock boot
+rc-update -q add hwclock boot

main/swclock-offset/swclock-offset-shutdown.initd

@@ -0,0 +1,29 @@
+#!/sbin/openrc-run
+
+# A dedicated shutdown service is used to write the offset file instead
+# of using the stop function of the swclock-offset service at boot. This
+# approach is more fail-safe on different installation/deinstallation
+# situations.
+#
+# Because the shutdown services are performed late within the shutdown
+# runlevel, dependencies are needed to execute the script before
+# processes are killed and filesystems are remounted read-only.
+
+description="Writing the offset between system time and RTC to a file."
+
+depend()
+{
+	before killprocs mount-ro
+}
+
+start()
+{
+	ebegin "Saving swclock-offset"
+	/sbin/swclock-offset-shutdown
+	eend $?
+}
+
+stop()
+{
+	return 0
+}

main/swclock-offset/swclock-offset-shutdown.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+# This shell scripts writes the offset between 'hwclock' and 'swclock'
+# to a file.
+#
+# To keep the offset calculation simple, the epoch timestamp is used.
+#
+# The system time is read by command "date". The RTC is read from the
+# sysfs node.
+
+rtc_sys_node="/sys/class/rtc/rtc0/since_epoch"
+offset_directory="/var/cache/swclock-offset"
+
+# check presence of rtc sys node
+if [ ! -f $rtc_sys_node ]; then
+  exit 1
+fi
+
+# check presence of offset directory
+if [ ! -d $offset_directory ]; then
+  mkdir -p $offset_directory
+fi
+
+# calculate offset
+swclock_epoch=$(date --utc +%s)
+hwclock_epoch=$(cat $rtc_sys_node)
+offset_epoch=$((swclock_epoch - hwclock_epoch))
+
+# write offset file
+echo $offset_epoch > $offset_directory/offset-storage

main/swclock-offset/swclock-offset.post-deinstall

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+# remove offset file and directory
+offset_file="/var/cache/swclock-offset/offset-storage"
+offset_directory="/var/cache/swclock-offset"
+
+if [ -f $offset_file ]; then
+  rm $offset_file
+fi
+
+if [ -d $offset_directory ]; then
+  rmdir $offset_directory
+fi