xnu-1699.32.7.tar.gz

[apple/xnu.git] / bsd / kern / tty.c

diff --git a/bsd/kern/tty.c b/bsd/kern/tty.c
index a03e1f43716ca35cc80f5ced1c2f3b625e6491dd..b97eb780e36ea557e667a64c90a19e204a4ad06d 100644 (file)
--- a/bsd/kern/tty.c
+++ b/bsd/kern/tty.c
@@ -1498,6 +1498,8 @@ out:
 int
 ttyselect(struct tty *tp, int rw, void *wql, proc_t p)
 {
+       int retval = 0;
+
        if (tp == NULL)
                return (ENXIO);
 
@@ -1505,20 +1507,32 @@ ttyselect(struct tty *tp, int rw, void *wql, proc_t p)
 
        switch (rw) {
        case FREAD:
-               if (ttnread(tp) > 0 || ISSET(tp->t_state, TS_ZOMBIE))
+               if (ISSET(tp->t_state, TS_ZOMBIE)) {
                        return(1);
+               }
+
+               retval = ttnread(tp);
+               if (retval > 0) {
+                       break;
+               }
+
                selrecord(p, &tp->t_rsel, wql);
                break;
        case FWRITE:
-               if ((tp->t_outq.c_cc <= tp->t_lowat &&
-                    ISSET(tp->t_state, TS_CONNECTED))
-                   || ISSET(tp->t_state, TS_ZOMBIE)) {
-                       return (1);
+               if (ISSET(tp->t_state, TS_ZOMBIE)) {
+                       return(1);
                }
+
+               if ((tp->t_outq.c_cc <= tp->t_lowat) &&
+                               ISSET(tp->t_state, TS_CONNECTED)) {
+                       retval = tp->t_hiwat - tp->t_outq.c_cc;
+                       break;
+               }
+
                selrecord(p, &tp->t_wsel, wql);
                break;
        }
-       return (0);
+       return retval;
 }
 
 
@@ -3022,6 +3036,8 @@ ttymalloc(void)
                /* output queue doesn't need quoting */
                clalloc(&tp->t_outq, TTYCLSIZE, 0);
                lck_mtx_init(&tp->t_lock, tty_lck_grp, tty_lck_attr);
+               klist_init(&tp->t_rsel.si_note);
+               klist_init(&tp->t_wsel.si_note);
        }
        return(tp);
 }
@@ -3038,6 +3054,12 @@ ttyfree(struct tty *tp)
 {
        TTY_LOCK_NOTOWNED(tp);  /* debug assert */
 
+#if DEBUG
+       if (!(SLIST_EMPTY(&tp->t_rsel.si_note) && SLIST_EMPTY(&tp->t_wsel.si_note))) {
+               panic("knotes hooked into a tty when the tty is freed.\n");
+       }
+#endif /* DEBUG */
+
        clfree(&tp->t_rawq);
        clfree(&tp->t_canq);
        clfree(&tp->t_outq);