Mercurial > hg
view mercurial/filesetlang.py @ 49000:dd6b67d5c256 stable
rust: fix unsound `OwningDirstateMap`
As per the previous patch, `OwningDirstateMap` is unsound. Self-referential
structs are difficult to implement correctly in Rust since the compiler is
free to move structs around as much as it wants to. They are also very rarely
needed in practice, so the state-of-the-art on how they should be done within
the Rust rules is still a bit new.
The crate `ouroboros` is an attempt at providing a safe way (in the Rust sense)
of declaring self-referential structs. It is getting a lot attention and was
improved very quickly when soundness issues were found in the past: rather than
relying on our own (limited) review circle, we might as well use the de-facto
common crate to fix this problem. This will give us a much better chance of
finding issues should any new ones be discovered as well as the benefit of
fewer `unsafe` APIs of our own.
I was starting to think about how I would present a safe API to the old struct
but soon realized that the callback-based approach was already done in
`ouroboros`, along with a lot more care towards refusing incorrect structs.
In short: we don't return a mutable reference to the `DirstateMap` anymore, we
expect users of its API to pass a `FnOnce` that takes the map as an argument.
This allows our `OwningDirstateMap` to control the input and output lifetimes
of the code that modifies it to prevent such issues.
Changing to `ouroboros` meant changing every API with it, but it is relatively
low churn in the end. It correctly identified the example buggy modification of
`copy_map_insert` outlined in the previous patch as violating the borrow rules.
Differential Revision: https://phab.mercurial-scm.org/D12429
author | Raphaël Gomès <rgomes@octobus.net> |
---|---|
date | Tue, 05 Apr 2022 10:55:28 +0200 |
parents | d4ba4d51f85f |
children | 6000f5b25c9b |
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# filesetlang.py - parser, tokenizer and utility for file set language # # Copyright 2010 Olivia Mackall <olivia@selenic.com> # # 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 from .i18n import _ from .pycompat import getattr from . import ( error, parser, pycompat, ) # common weight constants for static optimization # (see registrar.filesetpredicate for details) WEIGHT_CHECK_FILENAME = 0.5 WEIGHT_READ_CONTENTS = 30 WEIGHT_STATUS = 10 WEIGHT_STATUS_THOROUGH = 50 elements = { # token-type: binding-strength, primary, prefix, infix, suffix b"(": (20, None, (b"group", 1, b")"), (b"func", 1, b")"), None), b":": (15, None, None, (b"kindpat", 15), None), b"-": (5, None, (b"negate", 19), (b"minus", 5), None), b"not": (10, None, (b"not", 10), None, None), b"!": (10, None, (b"not", 10), None, None), b"and": (5, None, None, (b"and", 5), None), b"&": (5, None, None, (b"and", 5), None), b"or": (4, None, None, (b"or", 4), None), b"|": (4, None, None, (b"or", 4), None), b"+": (4, None, None, (b"or", 4), None), b",": (2, None, None, (b"list", 2), None), b")": (0, None, None, None, None), b"symbol": (0, b"symbol", None, None, None), b"string": (0, b"string", None, None, None), b"end": (0, None, None, None, None), } keywords = {b'and', b'or', b'not'} symbols = {} globchars = b".*{}[]?/\\_" def tokenize(program): pos, l = 0, len(program) program = pycompat.bytestr(program) while pos < l: c = program[pos] if c.isspace(): # skip inter-token whitespace pass elif c in b"(),-:|&+!": # handle simple operators yield (c, None, pos) elif ( c in b'"\'' or c == b'r' and program[pos : pos + 2] in (b"r'", b'r"') ): # handle quoted strings if c == b'r': pos += 1 c = program[pos] decode = lambda x: x else: decode = parser.unescapestr pos += 1 s = pos while pos < l: # find closing quote d = program[pos] if d == b'\\': # skip over escaped characters pos += 2 continue if d == c: yield (b'string', decode(program[s:pos]), s) break pos += 1 else: raise error.ParseError(_(b"unterminated string"), s) elif c.isalnum() or c in globchars or ord(c) > 127: # gather up a symbol/keyword s = pos pos += 1 while pos < l: # find end of symbol d = program[pos] if not (d.isalnum() or d in globchars or ord(d) > 127): break pos += 1 sym = program[s:pos] if sym in keywords: # operator keywords yield (sym, None, s) else: yield (b'symbol', sym, s) pos -= 1 else: raise error.ParseError(_(b"syntax error"), pos) pos += 1 yield (b'end', None, pos) def parse(expr): p = parser.parser(elements) tree, pos = p.parse(tokenize(expr)) if pos != len(expr): raise error.ParseError(_(b"invalid token"), pos) return parser.simplifyinfixops(tree, {b'list', b'or'}) def getsymbol(x): if x and x[0] == b'symbol': return x[1] raise error.ParseError(_(b'not a symbol')) def getstring(x, err): if x and (x[0] == b'string' or x[0] == b'symbol'): return x[1] raise error.ParseError(err) def getkindpat(x, y, allkinds, err): kind = getsymbol(x) pat = getstring(y, err) if kind not in allkinds: raise error.ParseError(_(b"invalid pattern kind: %s") % kind) return b'%s:%s' % (kind, pat) def getpattern(x, allkinds, err): if x and x[0] == b'kindpat': return getkindpat(x[1], x[2], allkinds, err) return getstring(x, err) def getlist(x): if not x: return [] if x[0] == b'list': return list(x[1:]) return [x] def getargs(x, min, max, err): l = getlist(x) if len(l) < min or len(l) > max: raise error.ParseError(err) return l def _analyze(x): if x is None: return x op = x[0] if op in {b'string', b'symbol'}: return x if op == b'kindpat': getsymbol(x[1]) # kind must be a symbol t = _analyze(x[2]) return (op, x[1], t) if op == b'group': return _analyze(x[1]) if op == b'negate': raise error.ParseError(_(b"can't use negate operator in this context")) if op == b'not': t = _analyze(x[1]) return (op, t) if op == b'and': ta = _analyze(x[1]) tb = _analyze(x[2]) return (op, ta, tb) if op == b'minus': return _analyze((b'and', x[1], (b'not', x[2]))) if op in {b'list', b'or'}: ts = tuple(_analyze(y) for y in x[1:]) return (op,) + ts if op == b'func': getsymbol(x[1]) # function name must be a symbol ta = _analyze(x[2]) return (op, x[1], ta) raise error.ProgrammingError(b'invalid operator %r' % op) def _insertstatushints(x): """Insert hint nodes where status should be calculated (first path) This works in bottom-up way, summing up status names and inserting hint nodes at 'and' and 'or' as needed. Thus redundant hint nodes may be left. Returns (status-names, new-tree) at the given subtree, where status-names is a sum of status names referenced in the given subtree. """ if x is None: return (), x op = x[0] if op in {b'string', b'symbol', b'kindpat'}: return (), x if op == b'not': h, t = _insertstatushints(x[1]) return h, (op, t) if op == b'and': ha, ta = _insertstatushints(x[1]) hb, tb = _insertstatushints(x[2]) hr = ha + hb if ha and hb: return hr, (b'withstatus', (op, ta, tb), (b'string', b' '.join(hr))) return hr, (op, ta, tb) if op == b'or': hs, ts = zip(*(_insertstatushints(y) for y in x[1:])) hr = sum(hs, ()) if sum(bool(h) for h in hs) > 1: return hr, (b'withstatus', (op,) + ts, (b'string', b' '.join(hr))) return hr, (op,) + ts if op == b'list': hs, ts = zip(*(_insertstatushints(y) for y in x[1:])) return sum(hs, ()), (op,) + ts if op == b'func': f = getsymbol(x[1]) # don't propagate 'ha' crossing a function boundary ha, ta = _insertstatushints(x[2]) if getattr(symbols.get(f), '_callstatus', False): return (f,), (b'withstatus', (op, x[1], ta), (b'string', f)) return (), (op, x[1], ta) raise error.ProgrammingError(b'invalid operator %r' % op) def _mergestatushints(x, instatus): """Remove redundant status hint nodes (second path) This is the top-down path to eliminate inner hint nodes. """ if x is None: return x op = x[0] if op == b'withstatus': if instatus: # drop redundant hint node return _mergestatushints(x[1], instatus) t = _mergestatushints(x[1], instatus=True) return (op, t, x[2]) if op in {b'string', b'symbol', b'kindpat'}: return x if op == b'not': t = _mergestatushints(x[1], instatus) return (op, t) if op == b'and': ta = _mergestatushints(x[1], instatus) tb = _mergestatushints(x[2], instatus) return (op, ta, tb) if op in {b'list', b'or'}: ts = tuple(_mergestatushints(y, instatus) for y in x[1:]) return (op,) + ts if op == b'func': # don't propagate 'instatus' crossing a function boundary ta = _mergestatushints(x[2], instatus=False) return (op, x[1], ta) raise error.ProgrammingError(b'invalid operator %r' % op) def analyze(x): """Transform raw parsed tree to evaluatable tree which can be fed to optimize() or getmatch() All pseudo operations should be mapped to real operations or functions defined in methods or symbols table respectively. """ t = _analyze(x) _h, t = _insertstatushints(t) return _mergestatushints(t, instatus=False) def _optimizeandops(op, ta, tb): if tb is not None and tb[0] == b'not': return (b'minus', ta, tb[1]) return (op, ta, tb) def _optimizeunion(xs): # collect string patterns so they can be compiled into a single regexp ws, ts, ss = [], [], [] for x in xs: w, t = _optimize(x) if t is not None and t[0] in {b'string', b'symbol', b'kindpat'}: ss.append(t) continue ws.append(w) ts.append(t) if ss: ws.append(WEIGHT_CHECK_FILENAME) ts.append((b'patterns',) + tuple(ss)) return ws, ts def _optimize(x): if x is None: return 0, x op = x[0] if op == b'withstatus': w, t = _optimize(x[1]) return w, (op, t, x[2]) if op in {b'string', b'symbol'}: return WEIGHT_CHECK_FILENAME, x if op == b'kindpat': w, t = _optimize(x[2]) return w, (op, x[1], t) if op == b'not': w, t = _optimize(x[1]) return w, (op, t) if op == b'and': wa, ta = _optimize(x[1]) wb, tb = _optimize(x[2]) if wa <= wb: return wa, _optimizeandops(op, ta, tb) else: return wb, _optimizeandops(op, tb, ta) if op == b'or': ws, ts = _optimizeunion(x[1:]) if len(ts) == 1: return ws[0], ts[0] # 'or' operation is fully optimized out ts = tuple( it[1] for it in sorted(enumerate(ts), key=lambda it: ws[it[0]]) ) return max(ws), (op,) + ts if op == b'list': ws, ts = zip(*(_optimize(y) for y in x[1:])) return sum(ws), (op,) + ts if op == b'func': f = getsymbol(x[1]) w = getattr(symbols.get(f), '_weight', 1) wa, ta = _optimize(x[2]) return w + wa, (op, x[1], ta) raise error.ProgrammingError(b'invalid operator %r' % op) def optimize(x): """Reorder/rewrite evaluatable tree for optimization All pseudo operations should be transformed beforehand. """ _w, t = _optimize(x) return t def prettyformat(tree): return parser.prettyformat(tree, (b'string', b'symbol'))