Merge pull request #3541 from rjbou/lock

Locked state and signals, avoid

src/core/opamSystem.ml

@@ -859,12 +859,18 @@ let rec flock_update
            Unix.(lockf fd F_ULOCK 0);
          Unix.lockf fd (unix_lock_op ~dontblock:true flag) 0
        with Unix.Unix_error (Unix.EAGAIN,_,_) ->
-         if dontblock then raise Locked;
+         if dontblock then
+           OpamConsole.error_and_exit `Locked
+             "Another process has locked %s and non blocking mode enabled"
+             file;
          OpamConsole.formatted_msg
            "Another process has locked %s, waiting (%s to abort)... "
            file (if Sys.win32 then "CTRL+C" else "C-c");
-         (try Unix.lockf fd (unix_lock_op ~dontblock:false flag) 0;
-          with Sys.Break as e -> OpamConsole.msg "\n"; raise e);
+         let rec lock_w_ignore_sig () =
+           try Unix.lockf fd (unix_lock_op ~dontblock:false flag) 0;
+           with Sys.Break as e -> (OpamConsole.msg "\n"; raise e)
+              | Unix.Unix_error (Unix.EINTR,_,_) -> lock_w_ignore_sig ()
+         in lock_w_ignore_sig ();
          OpamConsole.msg "lock acquired.\n");
     lock.kind <- (flag :> lock_flag)
   | _ -> assert false