[bmap-tools] [PATCH 02/14] bmaptool: cleanups
dedekind1 at gmail.com
Thu Sep 19 06:35:15 EDT 2013
From: Artem Bityutskiy <artem.bityutskiy at intel.com>
This function improves the commentaries and renames several functions. The
renames are about removing the 'copy_command_' prefix from function names,
because it is not very readable and we do not use it consistently anyway.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy at intel.com>
bmaptool | 43 ++++++++++++++++++++++++++-----------------
1 file changed, 26 insertions(+), 17 deletions(-)
diff --git a/bmaptool b/bmaptool
index 95380e8..6f3534a 100755
@@ -59,10 +59,18 @@ import traceback
from bmaptools import BmapCreate, BmapCopy, BmapHelpers, TransRead
-def copy_command_open_blkdev(path, log):
+def open_block_device(path, log):
- Open a block device specified by 'path' in exclusive mode. Returns opened
- file object.
+ This is a helper function for 'open_files()' which is called if the
+ destination file of the "copy" command is a block device. We handle block
+ devices a little bit different to regular files. Namely, we are trying to
+ make sure that we do not write to a mounted block device, otherwise the
+ user could corrupt, say, the root file system by a mistake. This is
+ achieved by opening the block device in exclusive mode, which guarantees
+ that we are the only users of the block device.
+ This function opens a block device specified by 'path' in exclusive mode.
+ Returns opened file object.
@@ -98,18 +106,21 @@ def copy_command_open_blkdev(path, log):
def find_and_open_bmap(args, log):
- This function opens the bmap file and returns the corresponding file object
- as the bmap file path.
+ This is a helper function for 'open_files()' which discovers and opens the
+ bmap file, then returns the corresponding file object and the bmap file
If the user specified the bmap file explicitely, we just open the provided
- path. Otherwise, we try to find the bmap file at the same place where the
- image file is located. We search for a file with the same path and
- basename, but with a ".bmap" extension. Since the image may contain more
- than one extension (e.g., image.raw.bz2), we try to remove them one-by-one.
+ path. Otherwise, we try to discover the bmap file at the same place where
+ the image file is located. We search for a file with the same path and
+ basename, but with a ".bmap" extension.
Additionally, this function makes sure that the returned file object
corresponds to a local file, not a remote file. We do this by creating a
- temporary local copy of the bmap file, if needed.
+ temporary local copy of the bmap file. The reason is that further on we may
+ need to check the GPG signature of the file, which requires it to be a
+ local file. On top of that, the BmapCopy class requires the bmap file to be
+ memory-mappable ('mmap()').
@@ -141,8 +152,6 @@ def find_and_open_bmap(args, log):
if not bmap_obj.is_compressed and not bmap_obj.is_url:
return (bmap_obj, bmap_path)
- # Current implementation of BmapCopy requires a local file for block map,
- # because it memory-maps it ('mmap()').
# Create a temporary file for the bmap
tmp_obj = tempfile.TemporaryFile("w+")
@@ -157,10 +166,10 @@ def find_and_open_bmap(args, log):
return (tmp_obj, bmap_path)
-def copy_command_open_all(args, log):
+def open_files(args, log):
- Open the image/bmap/destination files for the "copy" command. Returns a
- tuple of 5 elements:
+ This is a helper function for 'copy_command()' which the image, bmap, and
+ the destination files. Returns a tuple of 5 elements:
1 file-like object for the image
2 file object for the destination file
3 file-like object for the bmap
@@ -204,7 +213,7 @@ def copy_command_open_all(args, log):
dest_is_blkdev = stat.S_ISBLK(os.fstat(dest_obj.fileno()).st_mode)
- dest_obj = copy_command_open_blkdev(args.dest, log)
+ dest_obj = open_block_device(args.dest, log)
return (image_obj, dest_obj, bmap_obj, bmap_path, image_obj.size,
@@ -213,7 +222,7 @@ def copy_command_open_all(args, log):
def copy_command(args, log):
"""Copy an image to a block device or a regular file using bmap."""
image_obj, dest_obj, bmap_obj, bmap_path, image_size, dest_is_blkdev = \
- copy_command_open_all(args, log)
+ open_files(args, log)
dest_str = "block device '%s'" % args.dest
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