clean up stream-seek with some suggestions from slava

basis/io/backend/unix/unix.factor

@@ -46,14 +46,14 @@ M: fd cancel-operation ( fd -- )
         2bi
     ] if ;
 
-M: unix (stream-seek) ( n seek-type stream -- )
+M: unix seek-handle ( n seek-type handle -- )
     swap {
         { io:seek-absolute [ SEEK_SET ] }
         { io:seek-relative [ SEEK_CUR ] }
         { io:seek-end [ SEEK_END ] }
         [ io:bad-seek-type ]
     } case
-    [ handle>> fd>> swap ] dip lseek io-error ;
+    [ fd>> swap ] dip lseek io-error ;
 
 SYMBOL: +retry+ ! just try the operation again without blocking
 SYMBOL: +input+

basis/io/backend/windows/nt/nt.factor

@@ -87,11 +87,11 @@ ERROR: invalid-file-size n ;
 : handle>file-size ( handle -- n )
     0 <ulonglong> [ GetFileSizeEx win32-error=0/f ] keep *ulonglong ;
 
-M: winnt (stream-seek) ( n seek-type stream -- )
+M: winnt seek-handle ( n seek-type handle -- )
     swap {
-        { seek-absolute [ handle>> (>>ptr) ] }
-        { seek-relative [ handle>> [ + ] change-ptr drop ] }
-        { seek-end [ handle>> [ handle>> handle>file-size + ] keep (>>ptr) ] }
+        { seek-absolute [ (>>ptr) ] }
+        { seek-relative [ [ + ] change-ptr drop ] }
+        { seek-end [ [ handle>> handle>file-size + ] keep (>>ptr) ] }
         [ bad-seek-type ]
     } case ;
 

basis/io/buffers/buffers.factor

@@ -21,9 +21,6 @@ M: buffer dispose* ptr>> free ;
 : buffer-reset ( n buffer -- )
     swap >>fill 0 >>pos drop ;
 
-: buffer-reset-hard ( buffer -- )
-    0 >>fill 0 >>pos drop ;
-
 : buffer-capacity ( buffer -- n )
     [ size>> ] [ fill>> ] bi - ; inline
 

basis/io/ports/ports.factor

@@ -120,12 +120,17 @@ M: output-port stream-write
 
 HOOK: (wait-to-write) io-backend ( port -- )
 
-HOOK: (stream-seek) os ( n seek-type stream -- )
+HOOK: seek-handle os ( n seek-type handle -- )
 
-M: port stream-seek ( n seek-type stream -- )
-    dup check-disposed
-    [ buffer>> buffer-reset-hard 2drop ] [ (stream-seek) ] 3bi ;
+M: input-port stream-seek ( n seek-type stream -- )
+    [ check-disposed ]
+    [ buffer>> 0 swap buffer-reset ]
+    [ handle>> seek-handle ] tri ;
 
+M: output-port stream-seek ( n seek-type stream -- )
+    [ check-disposed ]
+    [ stream-flush ]
+    [ handle>> seek-handle ] tri ;
 
 GENERIC: shutdown ( handle -- )