1 files changed, 30 insertions, 0 deletions

diff --git a/meta/classes-recipe/fs-uuid.bbclass b/meta/classes-recipe/fs-uuid.bbclass
new file mode 100644
index 0000000000..a9e7eb8c67
--- /dev/null
+++ b/meta/classes-recipe/fs-uuid.bbclass
@@ -0,0 +1,30 @@
+#
+# Copyright OpenEmbedded Contributors
+#
+# SPDX-License-Identifier: MIT
+#
+
+# Extract UUID from ${ROOTFS}, which must have been built
+# by the time that this function gets called. Only works
+# on ext file systems and depends on tune2fs.
+def get_rootfs_uuid(d):
+    import subprocess
+    rootfs = d.getVar('ROOTFS')
+    output = subprocess.check_output(['tune2fs', '-l', rootfs])
+    for line in output.split('\n'):
+        if line.startswith('Filesystem UUID:'):
+            uuid = line.split()[-1]
+            bb.note('UUID of %s: %s' % (rootfs, uuid))
+            return uuid
+    bb.fatal('Could not determine filesystem UUID of %s' % rootfs)
+
+# Replace the special <<uuid-of-rootfs>> inside a string (like the
+# root= APPEND string in a syslinux.cfg or systemd-boot entry) with the
+# actual UUID of the rootfs. Does nothing if the special string
+# is not used.
+def replace_rootfs_uuid(d, string):
+    UUID_PLACEHOLDER = '<<uuid-of-rootfs>>'
+    if UUID_PLACEHOLDER in string:
+        uuid = get_rootfs_uuid(d)
+        string = string.replace(UUID_PLACEHOLDER, uuid)
+    return string