files: rootfs-postcommands: move helper commands to script

OverlayFS systemd helper unit might require more pre-processing
commands. It gets more complicated to embed them in a unit file, because
systemd shell subset is limited and might require additional escaping.
Move the command to a separate script, thus simplifying systemd unit.

(From OE-Core rev: 86a457016e7f3fc7acacf86cd87f5d8d882132dd)

Signed-off-by: Vyacheslav Yurkov <v.yurkov@precitec.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/rootfs-postcommands.bbclass

@@ -39,7 +39,7 @@ ROOTFS_POSTPROCESS_COMMAND += '${@bb.utils.contains("DISTRO_FEATURES", "systemd"
 
 ROOTFS_POSTPROCESS_COMMAND += 'empty_var_volatile;'
 
-ROOTFS_POSTPROCESS_COMMAND += '${@bb.utils.contains("DISTRO_FEATURES", "overlayfs", "overlayfs_qa_check;", "", d)}'
+ROOTFS_POSTPROCESS_COMMAND += '${@bb.utils.contains("DISTRO_FEATURES", "overlayfs", "overlayfs_qa_check; overlayfs_postprocess;", "", d)}'
 
 inherit image-artifact-names
 
@@ -422,3 +422,14 @@ python overlayfs_qa_check() {
     if not allUnitExist:
         bb.fatal('Not all mount paths and units are installed in the image')
 }
+
+python overlayfs_postprocess() {
+    import shutil
+
+    # install helper script
+    helperScriptName = "overlayfs-create-dirs.sh"
+    helperScriptSource = oe.path.join(d.getVar("COREBASE"), "meta/files", helperScriptName)
+    helperScriptDest = oe.path.join(d.getVar("IMAGE_ROOTFS"), "/usr/sbin/", helperScriptName)
+    shutil.copyfile(helperScriptSource, helperScriptDest)
+    os.chmod(helperScriptDest, 0o755)
+}

meta/files/overlayfs-create-dirs.service.in

@@ -6,8 +6,7 @@ DefaultDependencies=no
 
 [Service]
 Type=oneshot
-ExecStart=mkdir -p {DATA_MOUNT_POINT}/upper{LOWERDIR}
-ExecStart=mkdir -p {DATA_MOUNT_POINT}/workdir{LOWERDIR}
+ExecStart=/usr/sbin/overlayfs-create-dirs.sh {LOWERDIR} {DATA_MOUNT_POINT}
 RemainAfterExit=true
 StandardOutput=journal
 

meta/files/overlayfs-create-dirs.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+# This script is intended to be used sorely by overlayfs-create-dirs.service
+# Usage: overlayfs-create-dirs.sh <LOWERDIR> <DATA_MOUNT_POINT>
+
+lowerdir=$1
+datamountpoint=$2
+mkdir -p ${datamountpoint}/upper${lowerdir}
+mkdir -p ${datamountpoint}/workdir${lowerdir}