adding some mtree parsing stuff we need for overlays
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#!/usr/bin/env python3
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import argparse
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import copy
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import datetime
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import os
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import pathlib
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import re
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# Parse BSD mtree spec files.
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# On arch, BSD mtree is ported in the AUR as nmtree.
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# TODO: add a generator class as well?
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# TODO: add a checking function as well?
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class MTreeParse(object):
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def __init__(self, spec):
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if not isinstance(spec, (str, bytes)):
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raise ValueError('spec must be a raw string of the spec or a bytes object of the string')
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if isinstance(spec, bytes):
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try:
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spec = spec.decode('utf-8')
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except UnicodeDecodeError:
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raise ValueError('spec must be a utf-8 encoded set of bytes if using byte mode')
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self._strptime_fmt = '%a %b %d %H:%M:%S %Y'
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self.orig_spec = copy.deepcopy(spec) # For referencing in case someone wanted to write it out.
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# We NOW need to handle the escaped linebreaking it does.
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self._specdata = re.sub('\\\\\s+', '', spec).splitlines()
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self._get_header()
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self.spec = {'header': self.header,
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'paths': {}}
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# Template for an item.
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# Default keywords are:
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# flags, gid, link, mode, nlink, size, time, type, uid
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self._tplitem = {
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'type': None, # ('block', 'char', 'dir', 'fifo', 'file', 'link', 'socket')
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# checksum of file (if it's a file) (int)
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# On all *nix platforms, the cksum(1) utility (which is what the mtree spec uses) follows
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# the POSIX standard CRC (which is NOT CRC-1/CRC-16 nor CRC32!):
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# http://pubs.opengroup.org/onlinepubs/009695299/utilities/cksum.html
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# For a python implementation,
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# https://stackoverflow.com/questions/6835381/python-equivalent-of-unix-cksum-function
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# See also crcmod (in PyPi).
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'cksum': None,
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# "The device number to use for block or char file types." Should be converted to a tuple of one
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# of the following:
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# - (format(str), major(int), minor(int))
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# - (format(str), major(int), unit(str?), subunit(str?)) (only used on bsdos formats)
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# - (number(int?), ) ("opaque" number)
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# Valid formats are, per man page of mtree:
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# native, 386bsd, 4bsd, bsdos, freebsd, hpux, isc, linux, netbsd, osf1, sco, solaris, sunos,
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# svr3, svr4, ultrix
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'device': None,
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# File flags as symbolic name. BSD-specific thing? TODO: testing on BSD system
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'flags': [],
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'ignore': False, # An mtree-internal flag to ignore hierarchy under this item
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'gid': None, # The group ID (int)
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'gname': None, # The group name (str)
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'link': None, # The link target/source, if a link.
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# The MD5 checksum digest (str? hex?). "md5digest" is a synonym for this, so it's consolidated in
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# as the same keyword.
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'md5': None,
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# The mode (in octal) (we convert it to a python-native int for os.chmod/stat, etc.)
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# May also be a symbolic value; TODO: map symbolic to octal/int.
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'mode': None,
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'nlink': None, # Number of hard links for this item.
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'optional': False, # This item may or may not be present in the compared directory for checking.
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'rmd160': None, # The RMD-160 checksum of the file. "rmd160digest" is a synonym.
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'sha1': None, # The SHA-1 sum. "sha1digest" is a synonym.
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'sha256': None, # SHA-2 256-bit checksum; "sha256digest" is a synonym.
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'sha384': None, # SHA-2 384-bit checksum; "sha384digest" is a synonym.
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'sha512': None, # SHA-2 512-bit checksum; "sha512digest" is a synonym.
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'size': None, # Size of the file in bytes (int).
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'tags': [], # mtree-internal tags (comma-separated in the mtree spec).
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'time': None, # Time the file was last modified (in Epoch fmt as float).
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'uid': None, # File owner UID (int)
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'uname': None # File owner username (str)
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# And lastly, "children" is where the children files/directories go. We don't include it in the template;
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# it's added programmatically.
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# 'children': {}
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}
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# Global aspects are handled by "/set" directives.
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# They are restored by an "/unset". Since they're global and stateful, they're handled as a class attribute.
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self.settings = copy.deepcopy(self._tplitem)
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self._parse_items()
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del(self.settings, self._tplitem, self._strptime_fmt)
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def _get_header(self):
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self.header = {}
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_headre = re.compile('^#\s+(user|machine|tree|date):\s')
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_cmtre = re.compile('^\s*#\s*')
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_blklnre = re.compile('^\s*$')
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for idx, line in enumerate(self._specdata):
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if _headre.search(line): # We found a header item.
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l = [i.lstrip() for i in _cmtre.sub('', line).split(':', 1)]
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header = l[0]
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val = (l[1] if l[1] is not '(null)' else None)
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if header == 'date':
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val = datetime.datetime.strptime(val, self._strptime_fmt)
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elif header == 'tree':
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val = pathlib.PosixPath(val)
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self.header[header] = val
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elif _blklnre.search(line):
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break # We've reached the end of the header. Otherwise...
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else: # We definitely shouldn't be here, but this means the spec doesn't even have a header.
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break
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return()
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def _parse_items(self):
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# A pattern (compiled for performance) to match commands.
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_stngsre = re.compile('^/(un)?set\s')
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# Per the man page:
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# "Empty lines and lines whose first non-whitespace character is a hash mark (‘#’) are ignored."
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_ignre = re.compile('^(\s*(#.*)?)?$')
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# The following regex is used to quickly and efficiently check for a synonymized hash name.
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_hashre = re.compile('^(md5|rmd160|sha1|sha256|sha384|sha512)(digest)?$')
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# The following regex is to test if we need to traverse upwards in the path.
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_parentre = re.compile('^\.{,2}/?$')
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# _curpath = self.header['tree']
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_curpath = pathlib.PosixPath('/')
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_types = ('block', 'char', 'dir', 'fifo', 'file', 'link', 'socket')
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# This parses keywords. Used by both item specs and /set.
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def _kwparse(kwline):
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out = {}
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for i in kwline:
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l = i.split('=', 1)
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if len(l) < 2:
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l.append(None)
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k, v = l
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if v == 'none':
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v = None
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# These are represented as octals.
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if k in ('mode', ):
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# TODO: handle symbolic references too (e.g. rwxrwxrwx)
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if v.isdigit():
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v = int(v, 8) # Convert from the octal. This can then be used directly with os.chmod etc.
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# These are represented as ints
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elif k in ('uid', 'gid', 'cksum', 'nlink'):
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if v.isdigit():
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v = int(v)
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# These are booleans (represented as True by their presence).
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elif k in ('ignore', 'optional'):
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v = True
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# These are lists (comma-separated).
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elif k in ('flags', 'tags'):
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if v:
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v = [i.strip() for i in v.split(',')]
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# The following are synonyms.
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elif _hashre.search(k):
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k = _hashre.sub('\g<1>', k)
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elif k == 'time':
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v = datetime.datetime.fromtimestamp(float(v))
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elif k == 'type':
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if v not in _types:
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raise ValueError('{0} not one of: {1}'.format(v, ', '.join(_types)))
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out[k] = v
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return(out)
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def _unset_parse(unsetline):
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out = {}
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for i in unsetline:
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out[i] = self._tplitem[i]
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return(out)
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# The Business-End (TM)
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for idx, line in enumerate(self._specdata):
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_fname = copy.deepcopy(_curpath)
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# Skip these lines
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if _ignre.search(line):
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continue
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l = line.split()
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if _parentre.search(line):
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_curpath = _curpath.parent
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elif not _stngsre.search(line):
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# So it's an item, not a command.
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_itemsettings = copy.deepcopy(self.settings)
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_itemsettings.update(_kwparse(l[1:]))
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if _itemsettings['type'] == 'dir':
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# SOMEONE PLEASE let me know if there's a cleaner way to do this.
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_curpath = pathlib.PosixPath(os.path.normpath(_curpath.joinpath(l[0])))
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_fname = _curpath
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else:
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_fname = pathlib.PosixPath(os.path.normpath(_curpath.joinpath(l[0])))
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self.spec['paths'][_fname] = _itemsettings
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else:
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# It's a command. We can safely split on whitespace since the man page specifies the
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# values are not to contain whitespace.
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# /set
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if l[0] == '/set':
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del(l[0])
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self.settings.update(_kwparse(l))
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# /unset
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else:
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self.settings.update(_unset_parse(l))
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continue
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return()
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def parseArgs():
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args = argparse.ArgumentParser(description = 'An mtree parser')
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# TODO: support stdin piping
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args.add_argument('specfile',
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help = 'The path to the spec file to parse')
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return(args)
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# Allow to be run as a CLI utility as well.
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def main():
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args = vars(parseArgs().parse_args())
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import os
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with open(os.path.abspath(os.path.expanduser(args['specfile']))) as f:
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mt = MTreeParse(f.read())
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with open('/tmp/newspec', 'w') as f:
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f.write('\n'.join(mt._specdata))
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import pprint
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import inspect
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del(mt.orig_spec)
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del(mt._specdata)
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import shutil
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pprint.pprint(inspect.getmembers(mt), width = shutil.get_terminal_size()[0])
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if __name__ == '__main__':
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main()
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@ -0,0 +1,8 @@
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This directory contains example files/data that you may see referenced in documentation/code.
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- mtree.spec
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This file is an example mtree spec sheet that one may use for an overlay. It was generated by the command "mtree -c -K all -p /home/bts".
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If you're on Arch, a port of mtree can be found in the AUR under the package name "nmtree" (it's maintained by the same author as BDisk!).
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If you're on Debian or Ubuntu (or forks thereof), you can find it in the "freebsd-buildutils" package. (The executable is called "fmtree").
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If you're on Gentoo, it's in sys-apps/mtree.
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If you're on RHEL/CentOS, the "extras" repository has gomtree, which (although written in Go) should be able to produce mtree spec files (but this is unknown for certain).
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