[elbe-devel] [PATCH v2 3/8] elbepack: imgutils: add mount helper

[Thomas Weißschuh]

This helper will automatically clean up mounts via the context manager
protocol.
It will replace open-coded calls to mount(8).

Signed-off-by: Thomas Weißschuh <thomas.weissschuh at linutronix.de>
---
 elbepack/imgutils.py | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/elbepack/imgutils.py b/elbepack/imgutils.py
index e74b46bc41f3..d2ea2b669848 100644
--- a/elbepack/imgutils.py
+++ b/elbepack/imgutils.py
@@ -3,6 +3,7 @@
 # SPDX-FileCopyrightText: 2024 Linutronix GmbH
 
 import contextlib
+import subprocess
 
 from elbepack.shellhelper import do, get_command_out
 
@@ -17,3 +18,44 @@ def losetup(dev, extra_args=[]):
         yield loopdev
     finally:
         do(f'losetup --detach {loopdev}', check=False)
+
+
+class _Mount:
+    # This is not using contextlib.contextmanager as it will be pass to our
+    # RPCAPTCache which uses the pickle serialization.
+    # The generator by contextlib.contextmanager is not compatible with pickle.
+    def __init__(self, device, target, *, bind=False, type=None, options=None, log_output=True):
+        self.log_output = log_output
+        self.target = target
+
+        cmd = ['mount']
+        if bind:
+            cmd.append('--bind')
+
+        if options is not None:
+            cmd.extend(['-o', ','.join(options)])
+
+        if type is not None:
+            cmd.extend(['-t', type])
+
+        if device is None:
+            device = 'none'
+
+        cmd.extend([device, target])
+
+        self.cmd = cmd
+
+    def _run_cmd(self, cmd, *args, **kwargs):
+        if self.log_output:
+            do(cmd, *args, **kwargs)
+        else:
+            subprocess.run(cmd, *args, **kwargs)
+
+    def __enter__(self):
+        self._run_cmd(self.cmd)
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self._run_cmd(['umount', self.target], check=False)
+
+
+mount = _Mount

-- 
2.45.0