io.backend.unix: make timeouts work on stdin once Doug fixes alarms

basis/io/backend/unix/unix.factor

@@ -144,7 +144,7 @@ M: stdin dispose*
         tri
     ] with-destructors ;
 
-: wait-for-stdin ( stdin -- n )
+: wait-for-stdin ( stdin -- size )
     [ control>> CHAR: X over io:stream-write1 io:stream-flush ]
     [ size>> ssize_t heap-size swap io:stream-read *int ]
     bi ;
@@ -160,7 +160,12 @@ M: stdin dispose*
     ] if ;
 
 M: stdin refill
-    [ buffer>> ] [ dup wait-for-stdin ] bi* refill-stdin f ;
+    '[
+        buffer>> _ dup wait-for-stdin refill-stdin f
+    ] with-timeout ;
+
+M: stdin cancel-operation
+    [ size>> ] [ control>> ] bi [ cancel-operation ] bi@ ;
 
 : control-write-fd ( -- fd ) &: control_write *uint ;