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from collections import OrderedDict
import os.path
from ._path import AbsPath
# oct-unescape certain characters as they are in /proc/mountinfo
# see seq_path[_root]() in linux source
def _oct_unescape(b):
trans = {
br'\040' : b' ', br'\011' : b'\t',
br'\012' : b'\n', br'\0134' : b'\\',
}
for src, dst in trans.items():
b = b.replace(src, dst)
return b
class NotAbsRoot(Exception):
# This exception is raised for mount entries whose root is not
# a valid absolute path (this happens e.g. for persistent namespaces bound
# to a file). Such entries are skipped from MountInfo
pass
class _MountEntry:
index = None
"index of this entry in mountinfo"
mount_id = None
"mount ID, bytes"
parent_id = None
"parent ID, bytes"
devnum = None
"device number, int"
root = None
"root of the mount, AbsPath"
mount_point = None
"path where the fs is mounted, AbsPath"
mount_opts = None
"mount options bytes"
opt_fields = None
"optional fields, list of bytes"
fstype = None
"filesystem type, bytes or None"
source = None
"mount source, bytes or None"
super_opts = None
"superblock options, bytes or None"
raw_entry = None
"raw mountinfo line, bytes"
parent = None
"parent mountinfo entry, None if it does not exit"
def __init__(self, index, line):
self.index = index
self.raw_entry = line
items = line.split()
if len(items) < 6:
raise ValueError('Not enough items in a mountinfo line', line)
mount_id, parent_id, devnum, root, mount_point, mount_opts = items[:6]
self.mount_id = mount_id
self.parent_id = parent_id
major, minor = map(int, devnum.split(b':'))
# see Documentation/admin-guide/devices.txt in linux source
if major < 0 or major > 511 or minor < 0 or minor > 255:
raise ValueError('Invalid device number', devnum)
self.devnum = (major << 8) + minor
root = _oct_unescape(root)
if len(root) < 1 or not root.startswith(b'/'):
raise NotAbsRoot()
self.root = AbsPath(root)
self.mount_point = AbsPath(_oct_unescape(mount_point))
self.mount_opts = mount_opts
remainder = items[6:]
opt_fields = []
while len(remainder) > 0 and remainder[0] != b'-':
opt_fields.append(remainder.pop(0))
self.opt_fields = opt_fields
if len(remainder) > 0:
sep = remainder.pop(0)
if sep != b'-':
raise ValueError('Expected separator "-", got', sep)
if len(remainder) > 0:
self.fstype = remainder.pop(0)
if len(remainder) > 0:
self.source = _oct_unescape(remainder.pop(0))
if len(remainder) > 0:
self.super_opts = remainder.pop(0)
def __repr__(self):
return self.raw_entry.decode('ascii', errors = 'backslashreplace')
def __str__(self):
return '({major}:{minor}){src}{root}->{mp}'.format(
major = self.devnum >> 8, minor = self.devnum & 255,
src = ("{%s}" % self.source) if self.source else "",
root = "[%s]" % self.root, mp = self.mount_point)
class MountInfo:
"""
A wrapper around the contents of the Linux /proc/<pid>/mountinfo file.
"""
mounts = None
"OrderedDict of 'mount ID' -> _MountEntry"
def __init__(self, data):
mounts = OrderedDict()
for i, line in enumerate(data.splitlines()):
try:
e = _MountEntry(i, line)
except NotAbsRoot:
pass
if e.mount_id in mounts:
raise ValueError('Duplicate mount ID: %s' % str(e.mount_id))
mounts[e.mount_id] = e
self.mounts = mounts
for e in mounts.values():
try:
e.parent = mounts[e.parent_id]
except KeyError:
pass
def __str__(self):
return '%s(%d entries)' % (self.__class__.__name__, len(self.mounts))
def mountpoint_for_path(self, path):
"""
Find the mount entry which contains path.
"""
for mount in reversed(self.mounts.values()):
if path in mount.mount_point:
return mount
raise LookupError('No mountpoint for', path)
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