Moved some of the mounting logic here. Also introduced a context manager which will help unmount.

1 files changed, 51 insertions, 0 deletions

diff --git a/cloudinit/mounting.py b/cloudinit/mounting.py
new file mode 100644
index 00000000..b72f729a
--- /dev/null
+++ b/cloudinit/mounting.py
@@ -0,0 +1,51 @@
+import contextlib
+
+from cloudinit import util
+
+
+class MountFailedError(Exception):
+    pass
+
+
+@contextlib.contextmanager
+def unmounter(umount):
+    try:
+        yield umount
+    finally:
+        if umount:
+            sh.subp(["umount", '-l', umount])
+
+
+def mount_callback_umount(device, callback, data=None):
+    """
+    mount the device, call method 'callback' passing the directory
+    in which it was mounted, then unmount.  Return whatever 'callback'
+    returned.  If data != None, also pass data to callback.
+    """
+
+    # go through mounts to see if it was already mounted
+    mounts = sh.load_file("/proc/mounts").splitlines()
+    mounted = {}
+    for mpline in mounts:
+        (dev, mp, fstype, _opts, _freq, _passno) = mpline.split()
+        mp = mp.replace("\\040", " ")
+        mounted[dev] = (dev, fstype, mp, False)
+
+    with util.tempdir() as tmpd:
+        umount = False
+        if device in mounted:
+            mountpoint = "%s/" % mounted[device][2]
+        else:
+            try:
+                mountcmd = ["mount", "-o", "ro", device, tmpd]
+                util.subp(mountcmd)
+                umount = tmpd
+            except IOError as exc:
+                raise MountFailedError("%s" % (exc))
+            mountpoint = "%s/" % tmpd
+        with unmounter(umount):
+            if data is None:
+                ret = callback(mountpoint)
+            else:
+                ret = callback(mountpoint, data)
+            return ret