[SoaS] [PATCH 1/5] Support Live image mounting in fs.py

[Frederick Grose]

[Patch 1/5]
Author: Frederick Grose <fgrose at sugarlabs.org>
Date:   Thu Apr 14 09:29:14 2011 -0400

   Support Live image mounting.

   Provide DiskMount with mount options, DeviceMapperSnapshot with a
    device attribute, and a new LiveImageMount class.

diff --git a/imgcreate/fs.py b/imgcreate/fs.py
index d5307a2..0871182 100644
--- a/imgcreate/fs.py
+++ b/imgcreate/fs.py
@@ -324,7 +324,6 @@ class LoopbackDisk(Disk):
         self.device = None


-
class SparseLoopbackDisk(LoopbackDisk):
     """A Disk backed by a sparse file via the loop module."""
    def __init__(self, lofile, size):
@@ -377,11 +376,12 @@ class Mount:

class DiskMount(Mount):
     """A Mount object that handles mounting of a Disk."""
-    def __init__(self, disk, mountdir, fstype = None, rmmountdir = True):
+    def __init__(self, disk, mountdir, fstype=None, rmmountdir=True,
ops=None):
        Mount.__init__(self, mountdir)

        self.disk = disk
        self.fstype = fstype
+        self.ops = ops
        self.rmmountdir = rmmountdir

        self.mounted = False
@@ -435,6 +435,8 @@ class DiskMount(Mount):
         args = [ "/bin/mount", self.disk.device, self.mountdir ]
        if self.fstype:
             args.extend(["-t", self.fstype])
+        if self.ops:
+            args.extend(['-o', self.ops])

        rc = call(args)
         if rc != 0:
@@ -530,6 +532,7 @@ class ExtDiskMount(DiskMount):
         self.__resize_filesystem(size)
        return minsize

+
class DeviceMapperSnapshot(object):
     def __init__(self, imgloop, cowloop):
        self.imgloop = imgloop
@@ -541,6 +544,7 @@ class DeviceMapperSnapshot(object):
    def get_path(self):
         if self.__name is None:
            return None
+        return self.device
        return os.path.join("/dev/mapper", self.__name)
     path = property(get_path)

@@ -569,6 +573,7 @@ class DeviceMapperSnapshot(object):
                                 string.join(args, " "))

        self.__created = True
+        self.device = os.path.join('/dev/mapper', self.__name)

     def remove(self, ignore_errors = False):
        if not self.__created:
@@ -610,6 +615,89 @@ class DeviceMapperSnapshot(object):
        except ValueError:
             raise SnapshotError("Failed to parse dmsetup status: " + out)

+
+class LiveImageMount(object):
+    """A class for mounting a LiveOS image installed with an active
overlay."""
+
+    def __init__(self, disk, mountdir, overlay, tmpdir='/tmp'):
+        self.disk = disk
+        self.mountdir = mountdir
+        self.overlay = overlay
+        self.tmpdir = tmpdir
+        self.__created = False
+        self.squashmnt = None
+        self.homemnt = None
+        self.mntlive = None
+
+    def __create(self):
+        if self.__created:
+            return
+        self.liveosdevmnt = DiskMount(self.disk,
+                                   os.path.join(self.tmpdir, 'device'))
+        self.liveosdevmnt.mount()
+        liveosdir = os.path.join(self.liveosdevmnt.mountdir, 'LiveOS')
+        sqfs_img = os.path.join(liveosdir, 'squashfs.img')
+        if os.path.exists(sqfs_img):
+            self.squashloop = LoopbackDisk(sqfs_img, None)
+            self.squashmnt = DiskMount(self.squashloop,
+                                       os.path.join(self.tmpdir, 'squash'))
+            self.squashmnt.mount()
+            rootfs_img = os.path.join(self.squashmnt.mountdir,
+                                      'LiveOS', 'ext3fs.img')
+        else:
+            rootfs_img = os.path.join(liveosdir, 'ext3fs.img')
+            if not os.path.exists(rootfs_img):
+                raise SnapshotError("Failed to find a LiveOS root image.")
+        self.imgloop = LoopbackDisk(rootfs_img, None)
+        self.overlay = os.path.join(liveosdir, self.overlay)
+        self.cowloop = LoopbackDisk(self.overlay, None)
+        home_img = os.path.join(liveosdir, 'home.img')
+        self.dm_liveimage = DeviceMapperSnapshot(self.imgloop,
self.cowloop)
+        self.dm_livemount = DiskMount(self.dm_liveimage, self.mountdir)
+        if os.path.exists(home_img):
+            homedir = os.path.join(self.mountdir, 'home')
+            self.homemnt = LoopbackMount(home_img, homedir)
+        self.__created = True
+
+    def mount(self):
+        try:
+            self.__create()
+            if not self.liveosdevmnt.mounted:
+                self.liveosdevmnt.mount()
+            if not self.squashmnt.mounted:
+                self.squashmnt.mount()
+            self.dm_livemount.mount()
+            if self.homemnt:
+                self.homemnt.mount()
+            mntlivedir = os.path.join(self.mountdir, 'mnt', 'live')
+            if not os.path.exists(mntlivedir):
+                os.makedirs(mntlivedir)
+            self.mntlive = BindChrootMount(self.liveosdevmnt.mountdir,
+                                           '', mntlivedir)
+            self.mntlive.mount()
+        except MountError, e:
+            raise SnapshotError("Failed to mount %s : %s" % (self.disk, e))
+            self.cleanup()
+
+    def unmount(self):
+        if self.mntlive:
+            self.mntlive.unmount()
+        if self.homemnt:
+            self.homemnt.unmount()
+        self.dm_livemount.unmount()
+        self.liveosdevmnt.unmount()
+
+    def cleanup(self):
+        self.unmount()
+        if self.homemnt:
+            self.homemnt.cleanup()
+        self.dm_liveimage.remove()
+        if self.squashmnt:
+            self.squashmnt.cleanup()
+        self.liveosdevmnt.cleanup()
+        self.__created = False
+
+
def create_image_minimizer(path, image, compress_type, target_size = None,
                            tmpdir = "/tmp"):
    """
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