remoteloop: make LoopClient.device a context manager

assemblers/org.osbuild.qemu

@@ -9,6 +9,7 @@ import subprocess
 import sys
 import osbuild.remoteloop as remoteloop
 
+
 @contextlib.contextmanager
 def mount(source, dest, *options):
     os.makedirs(dest, 0o755, True)
@@ -18,14 +19,6 @@ def mount(source, dest, *options):
     finally:
         subprocess.run(["umount", "-R", dest], check=True)
 
-@contextlib.contextmanager
-def loop_device(loop_client, image, size, offset=0):
-    devname = loop_client.create_device(image, offset=offset, sizelimit=size)
-    path = f"/dev/{devname}"
-    try:
-        yield path
-    finally:
-        os.unlink(path)
 
 def main(tree, output_dir, options, loop_client):
     fmt = options["format"]
@@ -101,7 +94,7 @@ def main(tree, output_dir, options, loop_client):
                     f"{int(partition_size / 1024)}k"], input="y", encoding='utf-8', check=True)
 
     # Copy the tree into the target image
-    with loop_device(loop_client, image, partition_size, partition_offset) as loop, \
+    with loop_client.device(image, partition_offset, partition_size) as loop, \
         mount(loop, mountpoint):
         subprocess.run(["cp", "-a", f"{tree}/.", mountpoint], check=True)
 

osbuild/remoteloop.py

@@ -1,5 +1,6 @@
 import array
 import asyncio
+import contextlib
 import errno
 import json
 import os
@@ -112,7 +113,8 @@ class LoopClient:
     def __init__(self, sock):
         self.sock = sock
 
-    def create_device(self, filename, offset=None, sizelimit=None):
+    @contextlib.contextmanager
+    def device(self, filename, offset=None, sizelimit=None):
         req = {}
         fds = array.array("i")
         fd = os.open(filename, os.O_RDWR | os.O_DIRECT)
@@ -133,5 +135,8 @@ class LoopClient:
         os.close(fd)
 
         ret = json.loads(self.sock.recv(1024))
-
-        return ret["devname"]
+        path = os.path.join("/dev", ret["devname"])
+        try:
+            yield path
+        finally:
+            os.unlink(path)