hgext/lfs/pointer.py

global: replace most uses of RevlogError with StorageError (API)

When catching errors in storage, we should be catching
StorageError instead of RevlogError. When throwing errors related
to storage, we shouldn't be using RevlogError unless we know
the error stemmed from revlogs. And we only reliably know that
if we're in revlog.py or are inheriting from a type defined in
revlog.py.

Differential Revision: https://phab.mercurial-scm.org/D4655

# pointer.py - Git-LFS pointer serialization
#
# Copyright 2017 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import re

from mercurial.i18n import _

from mercurial import (
    error,
    pycompat,
)
from mercurial.utils import (
    stringutil,
)

class InvalidPointer(error.StorageError):
    pass

class gitlfspointer(dict):
    VERSION = 'https://git-lfs.github.com/spec/v1'

    def __init__(self, *args, **kwargs):
        self['version'] = self.VERSION
        super(gitlfspointer, self).__init__(*args)
        self.update(pycompat.byteskwargs(kwargs))

    @classmethod
    def deserialize(cls, text):
        try:
            return cls(l.split(' ', 1) for l in text.splitlines()).validate()
        except ValueError: # l.split returns 1 item instead of 2
            raise InvalidPointer(_('cannot parse git-lfs text: %s')
                                 % stringutil.pprint(text))

    def serialize(self):
        sortkeyfunc = lambda x: (x[0] != 'version', x)
        items = sorted(self.validate().iteritems(), key=sortkeyfunc)
        return ''.join('%s %s\n' % (k, v) for k, v in items)

    def oid(self):
        return self['oid'].split(':')[-1]

    def size(self):
        return int(self['size'])

    # regular expressions used by _validate
    # see https://github.com/git-lfs/git-lfs/blob/master/docs/spec.md
    _keyre = re.compile(br'\A[a-z0-9.-]+\Z')
    _valuere = re.compile(br'\A[^\n]*\Z')
    _requiredre = {
        'size': re.compile(br'\A[0-9]+\Z'),
        'oid': re.compile(br'\Asha256:[0-9a-f]{64}\Z'),
        'version': re.compile(br'\A%s\Z' % stringutil.reescape(VERSION)),
    }

    def validate(self):
        """raise InvalidPointer on error. return self if there is no error"""
        requiredcount = 0
        for k, v in self.iteritems():
            if k in self._requiredre:
                if not self._requiredre[k].match(v):
                    raise InvalidPointer(
                        _('unexpected lfs pointer value: %s=%s')
                        % (k, stringutil.pprint(v)))
                requiredcount += 1
            elif not self._keyre.match(k):
                raise InvalidPointer(_('unexpected lfs pointer key: %s') % k)
            if not self._valuere.match(v):
                raise InvalidPointer(_('unexpected lfs pointer value: %s=%s')
                                     % (k, stringutil.pprint(v)))
        if len(self._requiredre) != requiredcount:
            miss = sorted(set(self._requiredre.keys()).difference(self.keys()))
            raise InvalidPointer(_('missing lfs pointer keys: %s')
                                 % ', '.join(miss))
        return self

deserialize = gitlfspointer.deserialize