Support mounting freebsd ufs filesystems
[snf-image-creator] / image_creator / disk.py
index b220dff..b4311f8 100644 (file)
-#!/usr/bin/env python
+# Copyright 2012 GRNET S.A. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or
+# without modification, are permitted provided that the following
+# conditions are met:
+#
+#   1. Redistributions of source code must retain the above
+#      copyright notice, this list of conditions and the following
+#      disclaimer.
+#
+#   2. Redistributions in binary form must reproduce the above
+#      copyright notice, this list of conditions and the following
+#      disclaimer in the documentation and/or other materials
+#      provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
+# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+# The views and conclusions contained in the software and
+# documentation are those of the authors and should not be
+# interpreted as representing official policies, either expressed
+# or implied, of GRNET S.A.
+
+from image_creator.util import get_command
+from image_creator.util import try_fail_repeat
+from image_creator.util import free_space
+from image_creator.util import FatalError
+from image_creator.bundle_volume import BundleVolume
+from image_creator.image import Image
 
-import losetup
 import stat
 import os
 import tempfile
 import uuid
-import re
-import sys
-import guestfs
+import shutil
 
-from pbs import dmsetup
-from pbs import blockdev
-from pbs import dd
+dd = get_command('dd')
+dmsetup = get_command('dmsetup')
+losetup = get_command('losetup')
+blockdev = get_command('blockdev')
+
+
+TMP_CANDIDATES = ['/var/tmp', os.path.expanduser('~'), '/mnt']
 
-class DiskError(Exception): pass
 
 class Disk(object):
+    """This class represents a hard disk hosting an Operating System
 
-    def __init__(self, source):
+    A Disk instance never alters the source media it is created from.
+    Any change is done on a snapshot created by the device-mapper of
+    the Linux kernel.
+    """
+
+    def __init__(self, source, output, tmp=None):
+        """Create a new Disk instance out of a source media. The source
+        media can be an image file, a block device or a directory.
+        """
         self._cleanup_jobs = []
-        self._devices = []
+        self._images = []
         self.source = source
+        self.out = output
+        self.meta = {}
+        self.tmp = tempfile.mkdtemp(prefix='.snf_image_creator.',
+                                    dir=self._get_tmp_dir(tmp))
+
+        self._add_cleanup(shutil.rmtree, self.tmp)
+
+    def _get_tmp_dir(self, default=None):
+        """Check tmp directory candidates and return the one with the most
+        available space.
+        """
+        if default is not None:
+            return default
+
+        space = map(free_space, TMP_CANDIDATES)
+
+        max_idx = 0
+        max_val = space[0]
+        for i, val in zip(range(len(space)), space):
+            if val > max_val:
+                max_val = val
+                max_idx = i
+
+        # Return the candidate path with more available space
+        return TMP_CANDIDATES[max_idx]
 
     def _add_cleanup(self, job, *args):
+        """Add a new job in the cleanup list"""
         self._cleanup_jobs.append((job, args))
 
     def _losetup(self, fname):
-        loop = losetup.find_unused_loop_device()
-        loop.mount(fname)
-        self._add_cleanup(loop.unmount)
-        return loop.device
+        """Setup a loop device and add it to the cleanup list. The loop device
+        will be detached when cleanup is called.
+        """
+        loop = losetup('-f', '--show', fname)
+        loop = loop.strip()  # remove the new-line char
+        self._add_cleanup(try_fail_repeat, losetup, '-d', loop)
+        return loop
 
     def _dir_to_disk(self):
-        raise NotImplementedError
+        """Create a disk out of a directory"""
+        if self.source == '/':
+            bundle = BundleVolume(self.out, self.meta)
+            image = '%s/%s.diskdump' % (self.tmp, uuid.uuid4().hex)
+
+            def check_unlink(path):
+                if os.path.exists(path):
+                    os.unlink(path)
+
+            self._add_cleanup(check_unlink, image)
+            bundle.create_image(image)
+            return self._losetup(image)
+        raise FatalError("Using a directory as media source is supported")
 
     def cleanup(self):
-        while len(self._devices):
-            device = self._devices.pop()
-            device.destroy()
-            
-        while len(self._cleanup_jobs):
-            job, args = self._cleanup_jobs.pop()
-            job(*args)
-
-    def get_device(self):
+        """Cleanup internal data. This needs to be called before the
+        program ends.
+        """
+        try:
+            while len(self._images):
+                image = self._images.pop()
+                image.destroy()
+        finally:
+            # Make sure those are executed even if one of the device.destroy
+            # methods throws exeptions.
+            while len(self._cleanup_jobs):
+                job, args = self._cleanup_jobs.pop()
+                job(*args)
+
+    def snapshot(self):
+        """Creates a snapshot of the original source media of the Disk
+        instance.
+        """
+
+        self.out.output("Examining source media `%s' ..." % self.source, False)
         sourcedev = self.source
         mode = os.stat(self.source).st_mode
         if stat.S_ISDIR(mode):
-            return self._losetup(self._dir_to_disk())
+            self.out.success('looks like a directory')
+            return self._dir_to_disk()
         elif stat.S_ISREG(mode):
+            self.out.success('looks like an image file')
             sourcedev = self._losetup(self.source)
         elif not stat.S_ISBLK(mode):
-            raise ValueError("Value for self.source is invalid")
+            raise FatalError("Invalid media source. Only block devices, "
+                             "regular files and directories are supported.")
+        else:
+            self.out.success('looks like a block device')
 
         # Take a snapshot and return it to the user
-        size = blockdev('--getsize', sourcedev)
-        cowfd, cow = tempfile.mkstemp()
+        self.out.output("Snapshotting media source...", False)
+        size = blockdev('--getsz', sourcedev)
+        cowfd, cow = tempfile.mkstemp(dir=self.tmp)
+        os.close(cowfd)
         self._add_cleanup(os.unlink, cow)
-        # Create 1G cow file
-        dd('if=/dev/null', 'of=%s' % cow, 'bs=1k' ,'seek=%d' % (1024*1024))
+        # Create cow sparse file
+        dd('if=/dev/null', 'of=%s' % cow, 'bs=512', 'seek=%d' % int(size))
         cowdev = self._losetup(cow)
 
         snapshot = uuid.uuid4().hex
         tablefd, table = tempfile.mkstemp()
         try:
-            os.write(tablefd, "0 %d snapshot %s %s n 8" % \
-                                        (int(size), sourcedev, cowdev))
+            os.write(tablefd, "0 %d snapshot %s %s n 8" %
+                              (int(size), sourcedev, cowdev))
             dmsetup('create', snapshot, table)
-            self._add_cleanup(dmsetup, 'remove', snapshot)
+            self._add_cleanup(try_fail_repeat, dmsetup, 'remove', snapshot)
+
         finally:
             os.unlink(table)
-
-        new_device = DiskDevice("/dev/mapper/%s" % snapshot)
-        self._devices.append(new_device)
-        return new_device
-
-    def destroy_device(self, device):
-        self._devices.remove(device)
-        device.destroy()
-
-class DiskDevice(object):
-
-    def __init__(self, device, bootable = True):
-        self.device = device
-        self.bootable = bootable
-
-        self.g = guestfs.GuestFS()
-
-        self.g.set_trace(1)
-
-        self.g.add_drive_opts(device, readonly = 0)
-        self.g.launch()
-        roots = self.g.inspect_os()
-        if len(roots) == 0:
-            raise DiskError("No operating system found")
-        if len(roots) > 1:
-            raise DiskError("Multiple operating systems found")
-
-        self.root = roots[0]
-        self.ostype = self.g.inspect_get_type(self.root)
-        self.distro = self.g.inspect_get_distro(self.root)
-    
-    def destroy(self):
-        self.g.umount_all()
-        self.g.sync()
-        # Close the guestfs handler
-        self.g.close()
-        del self.g
-    
-    def mount(self):
-        mps = self.g.inspect_get_mountpoints(self.root)
-        # Sort the keys to mount the fs in a correct order.
-        # / should be mounted befor /boot, etc
-        def compare (a, b):
-            if len(a[0]) > len(b[0]): return 1
-            elif len(a[0]) == len(b[0]): return 0
-            else: return -1
-        mps.sort(compare)
-        for mp, dev in mps:
-            try:
-                self.g.mount(dev, mp)
-            except RuntimeError as msg:
-                print "%s (ignored)" % msg
+        self.out.success('done')
+        return "/dev/mapper/%s" % snapshot
+
+    def get_image(self, media):
+        """Returns a newly created Image instance."""
+
+        image = Image(media, self.out)
+        self._images.append(image)
+        image.enable()
+        return image
+
+    def destroy_image(self, image):
+        """Destroys an Image instance previously created by get_image method.
+        """
+        self._images.remove(image)
+        image.destroy()
 
 # vim: set sta sts=4 shiftwidth=4 sw=4 et ai :