diff options
Diffstat (limited to 'morphlib/fsutils.py')
| -rw-r--r-- | morphlib/fsutils.py | 82 |
1 files changed, 74 insertions, 8 deletions
diff --git a/morphlib/fsutils.py b/morphlib/fsutils.py index 9786e387..84884be8 100644 --- a/morphlib/fsutils.py +++ b/morphlib/fsutils.py @@ -1,4 +1,4 @@ -# Copyright (C) 2012 Codethink Limited +# Copyright (C) 2012-2013 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 @@ -17,18 +17,18 @@ import os import re -def create_image(runcmd, image_name, size): +def create_image(runcmd, image_name, size): # pragma: no cover # FIXME a pure python implementation may be better runcmd(['dd', 'if=/dev/zero', 'of=' + image_name, 'bs=1', 'seek=%d' % size, 'count=0']) -def partition_image(runcmd, image_name): +def partition_image(runcmd, image_name): # pragma: no cover # FIXME make this more flexible with partitioning options runcmd(['sfdisk', image_name], feed_stdin='1,,83,*\n') -def setup_device_mapping(runcmd, image_name): +def setup_device_mapping(runcmd, image_name): # pragma: no cover findstart = re.compile(r"start=\s+(\d+),") out = runcmd(['sfdisk', '-d', image_name]) for line in out.splitlines(): @@ -43,23 +43,89 @@ def setup_device_mapping(runcmd, image_name): return device.strip() -def create_fs(runcmd, partition): +def create_fs(runcmd, partition): # pragma: no cover runcmd(['mkfs.btrfs', '-L', 'baserock', partition]) -def mount(runcmd, partition, mount_point): +def mount(runcmd, partition, mount_point): # pragma: no cover if not os.path.exists(mount_point): os.mkdir(mount_point) runcmd(['mount', partition, mount_point]) -def unmount(runcmd, mount_point): +def unmount(runcmd, mount_point): # pragma: no cover runcmd(['umount', mount_point]) -def undo_device_mapping(runcmd, image_name): +def undo_device_mapping(runcmd, image_name): # pragma: no cover out = runcmd(['losetup', '-j', image_name]) for line in out.splitlines(): i = line.find(':') device = line[:i] runcmd(['losetup', '-d', device]) + + +def invert_paths(tree_walker, paths): + '''List paths from `tree_walker` that are not in `paths`. + + Given a traversal of a tree and a set of paths separated by os.sep, + return the files and directories that are not part of the set of + paths, culling directories that do not need to be recursed into, + if the traversal supports this. + + `tree_walker` is expected to follow similar behaviour to `os.walk()`. + + This function will remove directores from the ones listed, to avoid + traversing into these subdirectories, if it doesn't need to. + + As such, if a directory is returned, it is implied that its contents + are also not in the set of paths. + + If the tree walker does not support culling the traversal this way, + such as `os.walk(root, topdown=False)`, then the contents will also + be returned. + + The purpose for this is to list the directories that can be made + read-only, such that it would leave everything in paths writable. + + Each path in `paths` is expected to begin with the same path as + yielded by the tree walker. + + ''' + + def is_subpath(prefix, path): + prefix_components = prefix.split(os.sep) + path_components = path.split(os.sep) + return path_components[:len(prefix_components)] == prefix_components + + for dirpath, dirnames, filenames in tree_walker: + + dn_copy = list(dirnames) + for subdir in dn_copy: + subdirpath = os.path.join(dirpath, subdir) + for p in paths: + # Subdir is an exact match for a given path + # Don't recurse into it, so remove from list + # Also don't yield it as we're inverting + if subdirpath == p: + dirnames.remove(subdir) + break + # This directory is a parent directory of one + # of our paths, recurse into it, but don't yield it + elif is_subpath(subdirpath, p): + break + else: + dirnames.remove(subdir) + yield subdirpath + + for filename in filenames: + fullpath = os.path.join(dirpath, filename) + for p in paths: + # The file path is a child of one of the paths + # or is equal. Don't yield because either it is + # one of the specified paths, or is a file in a + # directory specified by a path + if is_subpath(p, fullpath): + break + else: + yield fullpath |