lib/oe: add generic functions for overlayfs

(From OE-Core rev: 53f0af20f94399335c8a5a6b7001994e332b69a6)

Signed-off-by: Vyacheslav Yurkov <uvv.mail@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oe/overlayfs.py

@@ -0,0 +1,43 @@
+#
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# This file contains common functions for overlayfs and its QA check
+
+# this function is based on https://github.com/systemd/systemd/blob/main/src/basic/unit-name.c
+def escapeSystemdUnitName(path):
+    escapeMap = {
+        '/': '-',
+        '-': "\\x2d",
+        '\\': "\\x5d"
+    }
+    return "".join([escapeMap.get(c, c) for c in path.strip('/')])
+
+def strForBash(s):
+    return s.replace('\\', '\\\\')
+
+def mountUnitName(unit):
+    return escapeSystemdUnitName(unit) + '.mount'
+
+def helperUnitName(unit):
+    return escapeSystemdUnitName(unit) + '-create-upper-dir.service'
+
+def unitFileList(d):
+    fileList = []
+    overlayMountPoints = d.getVarFlags("OVERLAYFS_MOUNT_POINT")
+
+    if not overlayMountPoints:
+        bb.fatal("A recipe uses overlayfs class but there is no OVERLAYFS_MOUNT_POINT set in your MACHINE configuration")
+
+    # check that we have required mount points set first
+    requiredMountPoints = d.getVarFlags('OVERLAYFS_WRITABLE_PATHS')
+    for mountPoint in requiredMountPoints:
+        if mountPoint not in overlayMountPoints:
+            bb.fatal("Missing required mount point for OVERLAYFS_MOUNT_POINT[%s] in your MACHINE configuration" % mountPoint)
+
+    for mountPoint in overlayMountPoints:
+        for path in d.getVarFlag('OVERLAYFS_WRITABLE_PATHS', mountPoint).split():
+            fileList.append(mountUnitName(path))
+            fileList.append(helperUnitName(path))
+
+    return fileList
+