This repository has been archived by the owner. It is now read-only.
Permalink
Browse files

Add functions to get UUIDs of different qualities.

Signed-off-by: Magnus Therning <magnus.therning@citrix.com>
  • Loading branch information...
Magnus Therning
Magnus Therning committed Oct 12, 2010
1 parent bd8bf98 commit 98cb4e90e39f171b1cc9948d4b46140a886707d5
Showing with 35 additions and 7 deletions.
  1. 0 autogen.sh
  2. +32 −7 uuid/uuid.ml
  3. +3 −0 uuid/uuid.mli
View
0 autogen.sh 100644 → 100755
No changes.
View
@@ -30,12 +30,34 @@ let string_of_cookie s = s
let cookie_of_string s = s
-(* FIXME: using /dev/random is too slow but using /dev/urandom is too
- deterministic. *)
-let dev_random = "/dev/urandom"
+let dev_random = "/dev/random"
+let dev_urandom = "/dev/urandom"
-let read_random n =
- let ic = open_in_bin dev_random in
+let rnd_array n =
+ let fstbyte i = 0xff land i in
+ let sndbyte i = fstbyte (i lsr 8) in
+ let thdbyte i = sndbyte (i lsr 8) in
+ let rec rnd_list n acc = match n with
+ | 0 -> acc
+ | 1 ->
+ let b = fstbyte (Random.bits ()) in
+ b :: acc
+ | 2 ->
+ let r = Random.bits () in
+ let b1 = fstbyte r in
+ let b2 = sndbyte r in
+ b1 :: b2 :: acc
+ | n ->
+ let r = Random.bits () in
+ let b1 = fstbyte r in
+ let b2 = sndbyte r in
+ let b3 = thdbyte r in
+ rnd_list (n - 3) (b1 :: b2 :: b3 :: acc)
+ in
+ Array.of_list (rnd_list n [])
+
+let read_array dev n =
+ let ic = open_in_bin dev in
try
let result = Array.init n (fun _ -> input_byte ic) in
close_in ic;
@@ -50,10 +72,13 @@ let uuid_of_int_array uuid =
uuid.(6) uuid.(7) uuid.(8) uuid.(9) uuid.(10) uuid.(11)
uuid.(12) uuid.(13) uuid.(14) uuid.(15)
-let make_uuid() = uuid_of_int_array (read_random 16)
+let make_uuid_prng () = uuid_of_int_array (rnd_array 16)
+let make_uuid_urnd () = uuid_of_int_array (read_array dev_urandom 16)
+let make_uuid_rnd () = uuid_of_int_array (read_array dev_random 16)
+let make_uuid = make_uuid_urnd
let make_cookie() =
- let bytes = Array.to_list (read_random 64) in
+ let bytes = Array.to_list (read_array dev_urandom 64) in
String.concat "" (List.map (Printf.sprintf "%1x") bytes)
let int_array_of_uuid s =
View
@@ -27,6 +27,9 @@ type 'a t
(** Create a fresh UUID *)
val make_uuid : unit -> 'a t
+val make_uuid_prng : unit -> 'a t
+val make_uuid_urnd : unit -> 'a t
+val make_uuid_rnd : unit -> 'a t
(** Create a UUID from a string. *)
val of_string : string -> 'a t

0 comments on commit 98cb4e9

Please sign in to comment.