mounts: use the options object for mountopts

This modification will allow a user to ask to mount the system as read
only for instance. Which would be super useful for image-info who is
progressively using more of OSbuild internals to mount partitions.

test/run/test_mount.py

@@ -0,0 +1,122 @@
+#!/usr/bin/python3
+
+#
+# Runtime Tests for Device Host Services
+#
+
+import errno
+import json
+import os
+import subprocess
+import sys
+import tempfile
+from contextlib import contextmanager
+
+import pytest
+
+from osbuild import devices, host, meta, mounts
+
+from ..test import TestBase
+
+
+@pytest.fixture(name="tmpdir")
+def tmpdir_fixture():
+    with tempfile.TemporaryDirectory(prefix="test-devices-") as tmp:
+        yield tmp
+
+
+@contextmanager
+def make_arguments(opts):
+    os.mkdir("/run/osbuild/api")
+    with open("/run/osbuild/api/arguments", "w", encoding="utf-8") as f:
+        json.dump(opts, f)
+    try:
+        yield
+    finally:
+        os.remove("/run/osbuild/api/arguments")
+        os.rmdir("/run/osbuild/api")
+
+
+@contextmanager
+def make_dev_tmpfs(tmpdir):
+    dev_path = os.path.join(tmpdir, "dev")
+    os.makedirs(dev_path)
+    subprocess.run(["mount", "-t", "tmpfs", "-o", "nosuid", "none", dev_path], check=True)
+    yield dev_path
+    subprocess.run(["umount", "--lazy", dev_path], check=True)
+
+
+@pytest.mark.skipif(not TestBase.can_bind_mount(), reason="root only")
+def test_mount_ro(tmpdir):
+    index = meta.Index(os.curdir)
+
+    # create a file to contain an image
+    tree = os.path.join(tmpdir, "tree")
+    os.makedirs(tree)
+    size = 1024 * 1024
+    file = os.path.join(tree, "image.img")
+    with open(file, "wb") as f:
+        f.truncate(size)
+
+    # Create an FS in the image
+    mkfsopts = {
+        "devices": {
+            "device": {
+                "path": file
+            }
+        },
+        "options": {
+            "label": "TEST",
+            "uuid": "FEEDFACE-CAFE-4004-FEED-C0DEC0FFEE11"
+        }
+    }
+    with make_arguments(mkfsopts):
+        subprocess.run(
+            [os.path.join(os.curdir, "stages",  "org.osbuild.mkfs.ext4")],
+            check=True,
+            stdout=sys.stdout,
+            stderr=sys.stderr)
+
+    with tempfile.TemporaryDirectory() as mountpoint:
+        with host.ServiceManager() as mgr:
+            with make_dev_tmpfs(tmpdir) as devpath:
+                # Device manager to open the loopback device
+                devmgr = devices.DeviceManager(mgr, devpath, tree)
+                # get a Device for the loopback
+                dev = devices.Device(
+                    "loop",
+                    index.get_module_info(
+                        "Device",
+                        "org.osbuild.loopback"
+                    ),
+                    None,
+                    {
+                        "filename": "image.img",
+                        "start": 0,
+                        "size": size // 512  # size is in sectors / blocks
+                    }
+                )
+                # open the device and get its loopback path
+                lpath = os.path.join(
+                    devpath,
+                    devmgr.open(dev)["path"]
+                )
+                # mount the loopback
+                mounts.MountManager(
+                    devmgr,
+                    mountpoint
+                ).mount(
+                    mounts.Mount(
+                        lpath,
+                        index.get_module_info("Mount", "org.osbuild.ext4"),
+                        dev,
+                        "/",
+                        {"readonly": True}
+                    )
+                )
+
+                # try to write in it, and failure to do so is a success
+                with pytest.raises(OSError) as err:
+                    with open(os.path.join(mountpoint, "test"), "w", encoding="utf-8") as f:
+                        f.write("should not work")
+                assert err.value.errno == errno.EROFS  # Check that FS is read only