storage: only associate OsProber results with existing partitions

If os-prober reports that Ubuntu is installed on sda4 (e.g., partition 4 of disk sda), then we should make that info available in the API. However, if we remove sda4 and then create another partition with number 4, we should not assume that it contains anything of value. refs LP: #2091172 Signed-off-by: Olivier Gayot <olivier.gayot@canonical.com>
canonical · Jan 16, 2025 · 7c0037c · 7c0037c
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diff --git a/subiquity/models/filesystem.py b/subiquity/models/filesystem.py
@@ -998,6 +998,11 @@ def ok_for_lvm_vg(self):
 
     @property
     def os(self):
+        if not self.preserve:
+            # Only associate the OS information with existing partitions.
+            # If /dev/sda4 was deleted and a new partition on sda with number 4
+            # is created, we should not pretend it contains anything of value.
+            return None
         os_data = self._m._probe_data.get("os", {}).get(self._path())
         if not os_data:
             return None

diff --git a/subiquity/models/tests/test_filesystem.py b/subiquity/models/tests/test_filesystem.py
@@ -1609,6 +1609,25 @@ def test_os(self):
         self.assertIsNone(p1.os.subpath)
         self.assertIsNone(p2.os)
 
+    def test_os__recreated_partition(self):
+        m = make_model(storage_version=2)
+        d = make_disk(m, ptable="gpt")
+
+        # We do not mark the partition preserved, which means we either
+        # formatted the disk or deleted / recreated the partition.
+        p = make_partition(m, d)
+
+        os_info = {
+            "label": "Ubuntu",
+            "long": "Ubuntu 22.04.1 LTS",
+            "type": "linux",
+            "version": "22.04.1",
+        }
+
+        m._probe_data["os"] = {p._path(): os_info}
+
+        self.assertIsNone(p.os)
+
 
 class TestCanmount(SubiTestCase):
     @parameterized.expand(