Mercurial > hg
view mercurial/pathutil.py @ 47799:3fffb48539ee stable
rust-nodemap: falling back to C impl as mitigation
This is a mitigation for https://bz.mercurial-scm.org/show_bug.cgi?id=6554
We see sometimes almost all data except the most recent revisions
removed from the persistent nodemap, but we don't know how to
reproduce yet.
This has sadly repercussions beyond just needing to reconstruct the
persistent nodemap: for instance, this automatically filters out
all bookmarks pointing to revisions that the nodemap cannot resolve.
If such filtering happens in a transaction, the update of the
bookmarks file that happens at the end of transaction loses all
bookmarks that have been affected. There may be similar consequences
for other data.
So this is a data loss, something that we have to prevent as soon as
possible.
As a mitigation measure, we will now fallback to the C implementation
in case nodemap lookups failed. This will add some latency, e.g., in
discovery, yet less than disabling the persistent nodemap entirely.
We considered implementing the fallback directly on the Python
side, but `revlog.get_rev()` is not systematically used, there are
also several direct calls to the index method (`self.index.rev()` for
a `revlog` instance). It is therefore more direct to implement the
mitigation in the rust-cpython wrapper.
Differential Revision: https://phab.mercurial-scm.org/D11238
author | Georges Racinet <georges.racinet@octobus.net> |
---|---|
date | Sun, 01 Aug 2021 14:39:38 +0200 |
parents | a9f38b144096 |
children | e02f9af7aed1 |
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from __future__ import absolute_import import contextlib import errno import os import posixpath import stat from .i18n import _ from . import ( encoding, error, policy, pycompat, util, ) if pycompat.TYPE_CHECKING: from typing import ( Any, Callable, Iterator, Optional, ) rustdirs = policy.importrust('dirstate', 'Dirs') parsers = policy.importmod('parsers') def _lowerclean(s): # type: (bytes) -> bytes return encoding.hfsignoreclean(s.lower()) class pathauditor(object): """ensure that a filesystem path contains no banned components. the following properties of a path are checked: - ends with a directory separator - under top-level .hg - starts at the root of a windows drive - contains ".." More check are also done about the file system states: - traverses a symlink (e.g. a/symlink_here/b) - inside a nested repository (a callback can be used to approve some nested repositories, e.g., subrepositories) The file system checks are only done when 'realfs' is set to True (the default). They should be disable then we are auditing path for operation on stored history. If 'cached' is set to True, audited paths and sub-directories are cached. Be careful to not keep the cache of unmanaged directories for long because audited paths may be replaced with symlinks. """ def __init__(self, root, callback=None, realfs=True, cached=False): self.audited = set() self.auditeddir = set() self.root = root self._realfs = realfs self._cached = cached self.callback = callback if os.path.lexists(root) and not util.fscasesensitive(root): self.normcase = util.normcase else: self.normcase = lambda x: x def __call__(self, path, mode=None): # type: (bytes, Optional[Any]) -> None """Check the relative path. path may contain a pattern (e.g. foodir/**.txt)""" path = util.localpath(path) normpath = self.normcase(path) if normpath in self.audited: return # AIX ignores "/" at end of path, others raise EISDIR. if util.endswithsep(path): raise error.Abort(_(b"path ends in directory separator: %s") % path) parts = util.splitpath(path) if ( os.path.splitdrive(path)[0] or _lowerclean(parts[0]) in (b'.hg', b'.hg.', b'') or pycompat.ospardir in parts ): raise error.Abort(_(b"path contains illegal component: %s") % path) # Windows shortname aliases for p in parts: if b"~" in p: first, last = p.split(b"~", 1) if last.isdigit() and first.upper() in [b"HG", b"HG8B6C"]: raise error.Abort( _(b"path contains illegal component: %s") % path ) if b'.hg' in _lowerclean(path): lparts = [_lowerclean(p) for p in parts] for p in b'.hg', b'.hg.': if p in lparts[1:]: pos = lparts.index(p) base = os.path.join(*parts[:pos]) raise error.Abort( _(b"path '%s' is inside nested repo %r") % (path, pycompat.bytestr(base)) ) normparts = util.splitpath(normpath) assert len(parts) == len(normparts) parts.pop() normparts.pop() # It's important that we check the path parts starting from the root. # We don't want to add "foo/bar/baz" to auditeddir before checking if # there's a "foo/.hg" directory. This also means we won't accidentally # traverse a symlink into some other filesystem (which is potentially # expensive to access). for i in range(len(parts)): prefix = pycompat.ossep.join(parts[: i + 1]) normprefix = pycompat.ossep.join(normparts[: i + 1]) if normprefix in self.auditeddir: continue if self._realfs: self._checkfs(prefix, path) if self._cached: self.auditeddir.add(normprefix) if self._cached: self.audited.add(normpath) def _checkfs(self, prefix, path): # type: (bytes, bytes) -> None """raise exception if a file system backed check fails""" curpath = os.path.join(self.root, prefix) try: st = os.lstat(curpath) except OSError as err: # EINVAL can be raised as invalid path syntax under win32. # They must be ignored for patterns can be checked too. if err.errno not in (errno.ENOENT, errno.ENOTDIR, errno.EINVAL): raise else: if stat.S_ISLNK(st.st_mode): msg = _(b'path %r traverses symbolic link %r') % ( pycompat.bytestr(path), pycompat.bytestr(prefix), ) raise error.Abort(msg) elif stat.S_ISDIR(st.st_mode) and os.path.isdir( os.path.join(curpath, b'.hg') ): if not self.callback or not self.callback(curpath): msg = _(b"path '%s' is inside nested repo %r") raise error.Abort(msg % (path, pycompat.bytestr(prefix))) def check(self, path): # type: (bytes) -> bool try: self(path) return True except (OSError, error.Abort): return False @contextlib.contextmanager def cached(self): if self._cached: yield else: try: self._cached = True yield finally: self.audited.clear() self.auditeddir.clear() self._cached = False def canonpath(root, cwd, myname, auditor=None): # type: (bytes, bytes, bytes, Optional[pathauditor]) -> bytes """return the canonical path of myname, given cwd and root >>> def check(root, cwd, myname): ... a = pathauditor(root, realfs=False) ... try: ... return canonpath(root, cwd, myname, a) ... except error.Abort: ... return 'aborted' >>> def unixonly(root, cwd, myname, expected='aborted'): ... if pycompat.iswindows: ... return expected ... return check(root, cwd, myname) >>> def winonly(root, cwd, myname, expected='aborted'): ... if not pycompat.iswindows: ... return expected ... return check(root, cwd, myname) >>> winonly(b'd:\\\\repo', b'c:\\\\dir', b'filename') 'aborted' >>> winonly(b'c:\\\\repo', b'c:\\\\dir', b'filename') 'aborted' >>> winonly(b'c:\\\\repo', b'c:\\\\', b'filename') 'aborted' >>> winonly(b'c:\\\\repo', b'c:\\\\', b'repo\\\\filename', ... b'filename') 'filename' >>> winonly(b'c:\\\\repo', b'c:\\\\repo', b'filename', b'filename') 'filename' >>> winonly(b'c:\\\\repo', b'c:\\\\repo\\\\subdir', b'filename', ... b'subdir/filename') 'subdir/filename' >>> unixonly(b'/repo', b'/dir', b'filename') 'aborted' >>> unixonly(b'/repo', b'/', b'filename') 'aborted' >>> unixonly(b'/repo', b'/', b'repo/filename', b'filename') 'filename' >>> unixonly(b'/repo', b'/repo', b'filename', b'filename') 'filename' >>> unixonly(b'/repo', b'/repo/subdir', b'filename', b'subdir/filename') 'subdir/filename' """ if util.endswithsep(root): rootsep = root else: rootsep = root + pycompat.ossep name = myname if not os.path.isabs(name): name = os.path.join(root, cwd, name) name = os.path.normpath(name) if auditor is None: auditor = pathauditor(root) if name != rootsep and name.startswith(rootsep): name = name[len(rootsep) :] auditor(name) return util.pconvert(name) elif name == root: return b'' else: # Determine whether `name' is in the hierarchy at or beneath `root', # by iterating name=dirname(name) until that causes no change (can't # check name == '/', because that doesn't work on windows). The list # `rel' holds the reversed list of components making up the relative # file name we want. rel = [] while True: try: s = util.samefile(name, root) except OSError: s = False if s: if not rel: # name was actually the same as root (maybe a symlink) return b'' rel.reverse() name = os.path.join(*rel) auditor(name) return util.pconvert(name) dirname, basename = util.split(name) rel.append(basename) if dirname == name: break name = dirname # A common mistake is to use -R, but specify a file relative to the repo # instead of cwd. Detect that case, and provide a hint to the user. hint = None try: if cwd != root: canonpath(root, root, myname, auditor) relpath = util.pathto(root, cwd, b'') if relpath.endswith(pycompat.ossep): relpath = relpath[:-1] hint = _(b"consider using '--cwd %s'") % relpath except error.Abort: pass raise error.Abort( _(b"%s not under root '%s'") % (myname, root), hint=hint ) def normasprefix(path): # type: (bytes) -> bytes """normalize the specified path as path prefix Returned value can be used safely for "p.startswith(prefix)", "p[len(prefix):]", and so on. For efficiency, this expects "path" argument to be already normalized by "os.path.normpath", "os.path.realpath", and so on. See also issue3033 for detail about need of this function. >>> normasprefix(b'/foo/bar').replace(pycompat.ossep, b'/') '/foo/bar/' >>> normasprefix(b'/').replace(pycompat.ossep, b'/') '/' """ d, p = os.path.splitdrive(path) if len(p) != len(pycompat.ossep): return path + pycompat.ossep else: return path def finddirs(path): # type: (bytes) -> Iterator[bytes] pos = path.rfind(b'/') while pos != -1: yield path[:pos] pos = path.rfind(b'/', 0, pos) yield b'' class dirs(object): '''a multiset of directory names from a set of file paths''' def __init__(self, map, skip=None): """ a dict map indicates a dirstate while a list indicates a manifest """ self._dirs = {} addpath = self.addpath if isinstance(map, dict) and skip is not None: for f, s in pycompat.iteritems(map): if s.state != skip: addpath(f) elif skip is not None: raise error.ProgrammingError( b"skip character is only supported with a dict source" ) else: for f in map: addpath(f) def addpath(self, path): # type: (bytes) -> None dirs = self._dirs for base in finddirs(path): if base.endswith(b'/'): raise ValueError( "found invalid consecutive slashes in path: %r" % base ) if base in dirs: dirs[base] += 1 return dirs[base] = 1 def delpath(self, path): # type: (bytes) -> None dirs = self._dirs for base in finddirs(path): if dirs[base] > 1: dirs[base] -= 1 return del dirs[base] def __iter__(self): return iter(self._dirs) def __contains__(self, d): # type: (bytes) -> bool return d in self._dirs if util.safehasattr(parsers, 'dirs'): dirs = parsers.dirs if rustdirs is not None: dirs = rustdirs # forward two methods from posixpath that do what we need, but we'd # rather not let our internals know that we're thinking in posix terms # - instead we'll let them be oblivious. join = posixpath.join dirname = posixpath.dirname # type: Callable[[bytes], bytes]