Properly shutdown pipe writer when reader closes

sys/char/pipe.c

@@ -108,9 +108,7 @@ static ssize_t pipe_vnode_read(struct ofile *of, void *buf, size_t count) {
 
 static void pipe_vnode_close(struct ofile *of) {
     _assert(of && of->file.priv_data);
-    if (of->flags & OF_WRITABLE) {
-        ring_signal(of->file.priv_data, RING_SIGNAL_EOF);
-    }
+    ring_signal(of->file.priv_data, RING_SIGNAL_EOF);
     // TODO: this
     //kfree(((struct ring *) of->file.priv_data)->base);
     //kfree(of->file.priv_data);

sys/char/ring.c

@@ -96,12 +96,18 @@ int ring_putc(struct thread *ctx, struct ring *ring, char c, int wait) {
     if (wait) {
         int res;
         while (!ring_writable(ring)) {
+            if (ring->flags & RING_SIGNAL_EOF) {
+                return -EPIPE;
+            }
             if ((res = thread_wait_io(ctx, &ring->writer_wait)) != 0) {
                 _assert(res == -EINTR);
                 return res;
             }
         }
     }
+    if (ring->flags & RING_SIGNAL_EOF) {
+        return -EPIPE;
+    }
 
     ring->base[ring->wr] = c;
     ring_advance_write(ring);
@@ -122,6 +128,7 @@ int ring_write(struct thread *ctx, struct ring *ring, const void *buf, size_t le
 void ring_signal(struct ring *r, int s) {
     r->flags |= s;
     thread_notify_io(&r->wait);
+    thread_notify_io(&r->writer_wait);
 }
 
 int ring_init(struct ring *r, size_t cap) {