The drive wizard never offers an EFI system partition (#833)

On a Debian install the onboarding wizard offered the EFI system partition
(unlabeled vfat at /boot/efi) as the primary WROLPi drive; choosing it would
mount the boot partition over /media/wrolpi.  Candidates were filtered by
the "EFI" label only, and the Debian installer leaves the ESP unlabeled.

/boot/efi is now an excluded mountpoint, and partitions with the EFI system
partition type (GPT GUID or MBR 0xef, from lsblk PARTTYPE) are excluded even
when unmounted, e.g. on a second internal disk.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

controller/lib/disks.py

@@ -48,6 +48,7 @@ class BlockDevice:
     uuid: Optional[str]
     model: Optional[str]
     is_wrolpi_drive: bool = False
+    parttype: Optional[str] = None  # GPT type GUID, or MBR type like "0xef".
 
 
 def get_block_devices() -> list[BlockDevice]:
@@ -60,7 +61,7 @@ def get_block_devices() -> list[BlockDevice]:
     if is_docker_mode():
         return []
 
-    cmd = ["lsblk", "-J", "-o", "NAME,PATH,SIZE,TYPE,FSTYPE,MOUNTPOINT,LABEL,UUID,MODEL"]
+    cmd = ["lsblk", "-J", "-o", "NAME,PATH,SIZE,TYPE,FSTYPE,MOUNTPOINT,LABEL,UUID,MODEL,PARTTYPE"]
 
     try:
         result = subprocess.run(cmd, capture_output=True, text=True, timeout=10)
@@ -83,6 +84,7 @@ def get_block_devices() -> list[BlockDevice]:
                     label=dev.get("label"),
                     uuid=dev.get("uuid"),
                     model=dev.get("model") or parent_model,
+                    parttype=dev.get("parttype"),
                 ))
             # Process children (partitions)
             for child in dev.get("children", []):

controller/lib/onboarding.py

@@ -36,11 +36,15 @@ logger = logging.getLogger(__name__)
 TEMP_MOUNT_PATH = "/media/wrolpi_temp_onboarding"
 
 # System mountpoints that should never be candidates
-EXCLUDED_MOUNTPOINTS = {"/", "/boot", "/boot/firmware"}
+EXCLUDED_MOUNTPOINTS = {"/", "/boot", "/boot/efi", "/boot/firmware"}
 
 # Partition labels that should never be candidates (case-insensitive)
 EXCLUDED_LABELS = {"efi", "efi system partition"}
 
+# EFI system partition types (GPT GUID, MBR id); these partitions are often
+# unlabeled, so the label check alone misses them.
+EFI_PARTTYPES = {"c12a7328-f81f-11d2-ba4b-00a0c93ec93b", "0xef"}
+
 
 def get_onboarding_candidates() -> list[dict]:
     """
@@ -65,6 +69,8 @@ def get_onboarding_candidates() -> list[dict]:
         # Skip EFI system partitions
         if d.label and d.label.lower() in EXCLUDED_LABELS:
             continue
+        if d.parttype and d.parttype.lower() in EFI_PARTTYPES:
+            continue
         candidates.append({
             "path": d.path,
             "name": d.name,

controller/test/test_disks.py

@@ -98,6 +98,22 @@ class TestGetBlockDevices:
                 assert result[0].fstype == "ext4"
                 assert result[0].model == "Samsung SSD"
 
+    def test_reads_partition_type(self):
+        """The partition type identifies an EFI system partition whatever its label or mount."""
+        lsblk_output = json.dumps({"blockdevices": [{
+            "name": "sda", "path": "/dev/sda", "size": "500G", "type": "disk", "children": [{
+                "name": "sda1", "path": "/dev/sda1", "size": "512M", "type": "part", "fstype": "vfat",
+                "parttype": "c12a7328-f81f-11d2-ba4b-00a0c93ec93b",
+            }],
+        }]})
+        with mock.patch("controller.lib.disks.is_docker_mode", return_value=False):
+            with mock.patch("subprocess.run") as mock_run:
+                mock_run.return_value = mock.Mock(returncode=0, stdout=lsblk_output)
+                result = get_block_devices()
+
+        assert "PARTTYPE" in mock_run.call_args.args[0][-1].split(",")
+        assert result[0].parttype == "c12a7328-f81f-11d2-ba4b-00a0c93ec93b"
+
     def test_filters_unsupported_filesystems(self):
         """Should only return devices with supported filesystems."""
         lsblk_output = json.dumps({

controller/test/test_onboarding.py

@@ -151,6 +151,48 @@ class TestGetOnboardingCandidates:
 
         assert len(candidates) == 0
 
+    def test_excludes_unlabeled_efi_at_boot_efi(self, mock_docker_mode):
+        """The Debian installer's EFI partition has no label and is mounted at /boot/efi; offering it as the
+        library drive would mount the boot partition over /media/wrolpi."""
+        from controller.lib.disks import BlockDevice
+
+        devices = [
+            BlockDevice(
+                name="nvme0n1p1", path="/dev/nvme0n1p1", size="976M", fstype="vfat",
+                mountpoint="/boot/efi", label=None, uuid="D019-F19C", model="QEMU NVMe Ctrl",
+            ),
+        ]
+        with mock.patch("controller.lib.onboarding.get_block_devices", return_value=devices):
+            candidates = get_onboarding_candidates()
+
+        assert candidates == []
+
+    @pytest.mark.parametrize("parttype", [
+        "c12a7328-f81f-11d2-ba4b-00a0c93ec93b",  # GPT EFI System Partition.
+        "C12A7328-F81F-11D2-BA4B-00A0C93EC93B",
+        "0xef",  # MBR EFI System Partition.
+    ])
+    def test_excludes_unmounted_efi_by_partition_type(self, mock_docker_mode, parttype):
+        """An unmounted, unlabeled EFI partition (e.g. on a second internal disk) is excluded by its type,
+        while an ordinary vfat USB drive is still offered."""
+        from controller.lib.disks import BlockDevice
+
+        devices = [
+            BlockDevice(
+                name="sdb1", path="/dev/sdb1", size="100M", fstype="vfat",
+                mountpoint=None, label=None, uuid="AAAA-BBBB", model="Old Disk", parttype=parttype,
+            ),
+            BlockDevice(
+                name="sdc1", path="/dev/sdc1", size="64G", fstype="vfat",
+                mountpoint=None, label="USB", uuid="CCCC-DDDD", model="Flash",
+                parttype="ebd0a0a2-b9e5-4433-87c0-68b6b72699c7",  # GPT Microsoft basic data.
+            ),
+        ]
+        with mock.patch("controller.lib.onboarding.get_block_devices", return_value=devices):
+            candidates = get_onboarding_candidates()
+
+        assert [c["path"] for c in candidates] == ["/dev/sdc1"]
+
     def test_excludes_temp_onboarding_mount(self, mock_docker_mode):
         """Drives mounted at the temp onboarding path should be excluded."""
         from controller.lib.disks import BlockDevice