/usr/share/acl2-6.3/books/serialize/unsound-read.lisp is in acl2-books-source 6.3-5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 | ; Serializing ACL2 Objects
; Copyright (C) 2009-2012 Centaur Technology
;
; Contact:
; Centaur Technology Formal Verification Group
; 7600-C N. Capital of Texas Highway, Suite 300, Austin, TX 78731, USA.
; http://www.centtech.com/
;
; This program is free software; you can redistribute it and/or modify it under
; the terms of the GNU General Public License as published by the Free Software
; Foundation; either version 2 of the License, or (at your option) any later
; version. This program is distributed in the hope that it will be useful but
; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
; FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
; more details. You should have received a copy of the GNU General Public
; License along with this program; if not, write to the Free Software
; Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA.
;
; Original author: Jared Davis <jared@centtech.com>
(in-package "ACL2")
(include-book "tools/include-raw" :dir :system)
; (depends-on "unsound-read-raw.lsp")
(defdoc unsound-read
":Doc-Section Serialize
Unsound alternative to ~ilc[serialize-read]~/
The ~c[unsound-read] command is like ~ilc[serialize-read] except that it does
not take ~ilc[state]. This means it works even in ordinary ~il[defconst]
events, which avoids the performance penalty of using ~ilc[make-event] to read
files; see ~ilc[serialize-in-books].
As its name suggests, ~c[unsound-read] is not sound and it can easily be used
to prove ~c[nil]; see below. Because of this, we don't build it into ACL2; to
use it you must first include the ~c[serialize/unsound-read] book, e.g.,
~bv[]
(include-book \"serialize/unsound-read\" :dir :system :ttags (:unsound-read))
~ev[]
and accept the ~c[:unsound-read] trust tag.
General form:
~bv[]
(unsound-read filename
[:hons-mode {:always, :never, :smart}]
[:verbose {t, nil}])
-->
obj
~ev[]
The arguments are as in ~ilc[serialize-read].
~/
EXPLANATION OF UNSOUNDNESS.
The logical problem with ~c[unsound-read] is that, since it is a function, it
is expected to satisfy the functional equality axiom schema, namely,
~bv[]
(equal (unsound-read-fn filename hons-mode verbosep)
(unsound-read-fn filename hons-mode verbosep))
~ev[]
But we can violate this property by modifying the file system between calls of
~c[unsound-read]. For instance, here is a proof of nil that is carried out in
~c[serialize/serialize-tests.lisp] by exploiting this fact.
~bv[]
(local
(encapsulate
()
;; Write NIL to test.sao
(make-event
(let ((state (serialize-write \"test.sao\" nil)))
(value '(value-triple :invisible))))
;; Prove that test.sao contains NIL.
(defthm lemma-1
(equal (unsound-read \"test.sao\") nil)
:rule-classes nil)
;; Write T to test.sao
(make-event
(let ((state (serialize-write \"test.sao\" t)))
(value '(value-triple :invisible))))
;; Prove that test.sao contains T.
(defthm lemma-2
(equal (unsound-read \"test.sao\") t)
:rule-classes nil)
;; Arrive at our contradiction.
(defthm qed
nil
:rule-classes nil
:hints((\"Goal\"
:use ((:instance lemma-1)
(:instance lemma-2))
:in-theory (disable (unsound-read-fn)))))))
~ev[]
In short, if you want to use ~c[unsound-read] soundly, then you need to make
sure the files you are reading aren't changing out from under you.")
(defttag :unsound-read)
; We use this stub in the logical definition, so that you can't
; directly reason about the value of unsound-read.
(defstub unsound-read-fn-logical-def (filename honsp verbosep)
t)
(defun unsound-read-fn (filename hons-mode verbosep)
(declare (xargs :guard (and (stringp filename)
(member-eq hons-mode '(:always :never :smart))
(booleanp verbosep))))
(prog2$
(er hard? 'unsound-read-fn "Raw-lisp definition not installed??")
(unsound-read-fn-logical-def filename hons-mode verbosep)))
(defmacro unsound-read (filename &key
(hons-mode ':smart)
verbosep)
`(unsound-read-fn ,filename ,hons-mode ,verbosep))
(include-raw "unsound-read-raw.lsp")
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