morphlib: move filesystem stuff out of builder

The system images will later need to be read, so useful commands
want to be shared

1 files changed, 70 insertions, 0 deletions

diff --git a/morphlib/fsutils.py b/morphlib/fsutils.py
new file mode 100644
index 00000000..081ce0e8
--- /dev/null
+++ b/morphlib/fsutils.py
@@ -0,0 +1,70 @@
+# Copyright (C) 2012  Codethink Limited
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+
+def create_image(ex, image_name, size):
+    # FIXME a pure python implementation may be better
+    self.ex.runv(['dd', 'if=/dev/zero', 'of=' + image_name, 'bs=1',
+                      'seek=%d' % size, 'count=0'])
+
+def partition_image(ex, image_name):
+    # FIXME make this more flexible with partitioning options
+    ex.runv(['sfdisk', image_name], feed_stdin='1,,83,*\n')
+
+def install_mbr(ex, image_name):
+    for path in ['/usr/lib/extlinux/mbr.bin',
+                 '/usr/share/syslinux/mbr.bin']:
+        if os.path.exists(path):
+            self.ex.runv(['dd', 'if=' + path, 'of=' + image_name,
+                          'conv=notrunc'])
+            break
+
+def setup_device_mapping(ex, image_name):
+    out = ex.runv(['sfdisk', '-d', image_name])
+    for line in out.splitlines():
+        words = line.split()
+        if (len(words) >= 4 and 
+            words[2] == 'start=' and 
+            words[3] != '0,'):
+            n = int(words[3][:-1]) # skip trailing comma
+            start = n * 512
+            break
+    
+    ex.runv(['losetup', '-o', str(start), '-f', image_name])
+    
+    out = ex.runv(['losetup', '-j', image_name])
+    line = out.strip()
+    i = line.find(':')
+    return line[:i]
+
+def create_fs(ex, partition):
+    # FIXME: the hardcoded size of 4GB is icky but the default broke
+    # when we used mkfs -t ext4
+    ex.runv(['mkfs', '-t', 'btrfs', '-L', 'baserock',
+                  '-b', '4294967296', partition])
+
+def mount(ex, partition, mount_point):
+    os.mkdir(mount_point)
+    self.ex.runv(['mount', partition, mount_point])
+
+def unmount(ex, mount_point):
+    ex.runv(['umount', mount_point])
+
+def undo_device_mapping(ex, image_name)
+    out = ex.runv(['losetup', '-j', image_name])
+    for line in out.splitlines():
+        i = line.find(':')
+        device = line[:i]
+        ex.runv(['losetup', '-d', device])