utils: rewrite ogExtendFs

Drop subprocess call to bash function ogExtendFs. Use a native python
solution with subprocess calls to the required underlying tools.

Use get_filesystem_type to get the present filesystem from a partition
and call the corresponding filesystem grow function.

Filesystem specific functions are declared "_extend_{filesystem}" and
should not be imported elsewhere.

Each filesystem specific function wraps a subprocess call to the
required underlying program:

- NTFS filesystems: "ntfsresize -f [partition]"
- ext4 filesystems: "resize2fs -f [partition]"

Set NTFS related subprocess stdin to 'y' because human input cannot be
unset with other ntfsresize parameters.

src/utils/fs.py

@@ -101,14 +101,21 @@ def ogReduceFs(disk, part):
 
 def ogExtendFs(disk, part):
     """
-    Bash function 'ogExtendFs' wrapper
+    Grow filesystem of a partition. Supports ext4 and ntfs partitions.
+    Unsupported filesystem or invalid paths don't raise an exception,
+    instead this method logs a warning message and does nothing.
     """
-    subprocess.run(f'ogMount {disk} {part}',
-                   shell=True)
-    proc = subprocess.run(f'ogExtendFs {disk} {part}',
-                          shell=True)
-    if proc.returncode != 0:
-        logging.warn(f'ogExtendFs exited with non zero code: {proc.returncode}')
+    partdev = get_partition_device(disk, part)
+    fstype = get_filesystem_type(partdev)
+
+    umount(partdev)
+    if fstype == 'ext4':
+        _extend_resize2fs(partdev)
+    elif fstype == 'ntfs':
+        _extend_ntfsresize(partdev)
+    else:
+        logging.warn(f'Unable to grow filesystem at {partdev}. '
+                     f'Unsupported filesystem "{fstype}".')
 
 
 def mkfs(fs, disk, partition, label=None):
@@ -220,3 +227,17 @@ def _reduce_ntfsresize(partdev):
         cmd_resize = shlex.split(f'ntfsresize -fs {new_size:.0f} {partdev}')
         with open('/tmp/command.log', 'ab', 0) as logfile:
             subprocess.run(cmd_resize, input='y', stderr=STDOUT, encoding='utf-8')
+
+
+def _extend_resize2fs(partdev):
+    cmd_resize2fs = shlex.split(f'resize2fs -f {partdev}')
+    proc = subprocess.run(cmd_resize2fs)
+    if proc.returncode != 0:
+        raise RuntimeError(f'Error growing ext4 filesystem at {partdev}')
+
+
+def _extend_ntfsresize(partdev):
+    cmd_ntfsresize = shlex.split(f'ntfsresize -f {partdev}')
+    proc = subprocess.run(cmd_resize2fs, input='y')
+    if proc.returncode != 0:
+        raise RuntimeError(f'Error growing ntfs filesystem at {partdev}')