From 4177c2380fcd92bca07c97993c21ffd230408eca Mon Sep 17 00:00:00 2001
From: Pierre-Marie Pédrot
Date: Wed, 5 Mar 2014 20:32:10 +0100
Subject: Adding a canary library. This canary is imperfect. It allows
 serialization (hopefully), and forbids generic equality. Still, it allows
 generic hash.

---
 checker/check.mllib   |  1 +
 dev/printers.mllib    |  1 +
 grammar/grammar.mllib |  1 +
 lib/canary.ml         | 26 ++++++++++++++++++++++++++
 lib/canary.mli        | 25 +++++++++++++++++++++++++
 lib/clib.mllib        |  1 +
 6 files changed, 55 insertions(+)
 create mode 100644 lib/canary.ml
 create mode 100644 lib/canary.mli

diff --git a/checker/check.mllib b/checker/check.mllib
index 80c7ac7e67..bb2146f38e 100644
--- a/checker/check.mllib
+++ b/checker/check.mllib
@@ -1,6 +1,7 @@
 Coq_config
 
 Hook
+Canary
 Hashset
 Hashcons
 CSet
diff --git a/dev/printers.mllib b/dev/printers.mllib
index 71c88bc21b..1dfca34354 100644
--- a/dev/printers.mllib
+++ b/dev/printers.mllib
@@ -1,6 +1,7 @@
 Coq_config
 
 Hook
+Canary
 Hashset
 Hashcons
 CSet
diff --git a/grammar/grammar.mllib b/grammar/grammar.mllib
index c2f39deed1..338d44fbf9 100644
--- a/grammar/grammar.mllib
+++ b/grammar/grammar.mllib
@@ -1,6 +1,7 @@
 Coq_config
 
 Hook
+Canary
 Hashset
 Hashcons
 CSet
diff --git a/lib/canary.ml b/lib/canary.ml
new file mode 100644
index 0000000000..f27890c160
--- /dev/null
+++ b/lib/canary.ml
@@ -0,0 +1,26 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2012     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+type t = Obj.t
+
+let obj = Obj.new_block Obj.closure_tag 0
+  (** This is an empty closure block. In the current implementation, it is
+      sufficient to allow marshalling but forbid equality. Sadly still allows
+      hash. *)
+  (** FIXME : use custom blocks somehow. *)
+
+module type Obj = sig type t end
+
+module Make(M : Obj) =
+struct
+  type canary = t
+  type t = (canary * M.t)
+
+  let prj (_, x) = x
+  let inj x = (obj, x)
+end
diff --git a/lib/canary.mli b/lib/canary.mli
new file mode 100644
index 0000000000..fd65cb84c9
--- /dev/null
+++ b/lib/canary.mli
@@ -0,0 +1,25 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2012     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+type t
+(** Type of canaries. Canaries are used to ensure that an object does not use
+    generic operations. *)
+
+val obj : t
+(** Canary. In the current implementation, this object is marshallable,
+    forbids generic comparison but still allows generic hashes. *)
+
+module type Obj = sig type t end
+
+module Make(M : Obj) :
+sig
+  type t
+  val prj : t -> M.t
+  val inj : M.t -> t
+end
+(** Adds a canary to any type. *)
diff --git a/lib/clib.mllib b/lib/clib.mllib
index 2547ed2297..1dc540b9aa 100644
--- a/lib/clib.mllib
+++ b/lib/clib.mllib
@@ -1,5 +1,6 @@
 Coq_config
 
+Canary
 Hook
 Hashset
 Hashcons
-- 
cgit v1.2.3