[Tapctl.of_device x] now will throw an exception if [x] is not a device; or if [x...

Signed-off-by: David Scott <dave.scott@eu.citrix.com>

diff --git a/tapctl/tapctl.ml b/tapctl/tapctl.ml
index c54e51f1d5c00954a8c951361e1eef46b4d84202..8cba5267b97568d2b9c53d1eee1a4ef0a1a7d5df 100644 (file)
--- a/tapctl/tapctl.ml
+++ b/tapctl/tapctl.ml
@@ -332,8 +332,24 @@ let is_active ctx t =
                | [(tapdev,state,Some _ )] -> true
                | _ -> false
 
+(* We need to be able to check that a given device's major number corresponds to the right driver *)
+let read_proc_devices () : (int * string) list = 
+       let parse_line x = match List.filter (fun x -> x <> "") (String.split ' ' x) with
+       | [x; y] -> (try Some (int_of_string x, y) with _ -> None)
+       | _ -> None in
+       List.concat (List.map Opt.to_list ( Unixext.file_lines_fold (fun acc x -> parse_line x :: acc) [] "/proc/devices") )
+
+let driver_of_major major = List.assoc major (read_proc_devices ())
+
+exception Not_blktap
+exception Not_a_device
+
 let of_device ctx path =
-       let minor = (Unix.stat path).Unix.st_rdev mod 256 in
+       let stat = Unix.stat path in
+       if stat.Unix.st_kind <> Unix.S_BLK then raise Not_a_device;
+       let major = stat.Unix.st_rdev / 256 in
+       let minor = stat.Unix.st_rdev mod 256 in
+       if driver_of_major major <> "tapdev" then raise Not_blktap;
        match List.filter (fun (tapdev, _, _) -> tapdev.minor = minor) (list ctx) with
                | [ t ] -> t
                | _ -> raise Not_found

diff --git a/tapctl/tapctl.mli b/tapctl/tapctl.mli
index 4c8e9224bd02af6fec4c0fce843a275897949b7d..8cd47e4a8d51898b14d48cf4d8bd3f3c6a2ece9d 100644 (file)
--- a/tapctl/tapctl.mli
+++ b/tapctl/tapctl.mli
@@ -33,5 +33,11 @@ val list : ?t:tapdev -> context -> t list
 val is_paused : context -> tapdev -> bool
 val is_active : context -> tapdev -> bool
 
+(** Thrown by [of_device x] when [x] is a device not owned by blktap *)
+exception Not_blktap
+
+(** Thrown by [of_device x] when [x] is not a device *)
+exception Not_a_device
+
 (** Given a path to a device, return the corresponding tap information *)
 val of_device : context -> string -> t