io: fix duplex read on last bytes of closed pipe.

[ccan] / ccan / io / io.c

diff --git a/ccan/io/io.c b/ccan/io/io.c
index cc2b1afa3b27720adff4e3aa0b0c1d4fd4a393a3..7eea9c35442cbbcb4386b430929195d1454b49a0 100644 (file)
--- a/ccan/io/io.c
+++ b/ccan/io/io.c
@@ -363,14 +363,20 @@ void io_wake(const void *wait)
        backend_wake(wait);
 }
 
-/* Returns false if this has been freed. */
-static bool do_plan(struct io_conn *conn, struct io_plan *plan)
+/* Returns false if this should not be touched (eg. freed). */
+static bool do_plan(struct io_conn *conn, struct io_plan *plan,
+                   bool idle_on_epipe)
 {
        /* We shouldn't have polled for this event if this wasn't true! */
        assert(plan->status == IO_POLLING);
 
        switch (plan->io(conn->fd.fd, &plan->arg)) {
        case -1:
+               if (errno == EPIPE && idle_on_epipe) {
+                       plan->status = IO_UNSET;
+                       backend_new_plan(conn);
+                       return false;
+               }
                io_close(conn);
                return false;
        case 0:
@@ -386,11 +392,15 @@ static bool do_plan(struct io_conn *conn, struct io_plan *plan)
 void io_ready(struct io_conn *conn, int pollflags)
 {
        if (pollflags & POLLIN)
-               if (!do_plan(conn, &conn->plan[IO_IN]))
+               if (!do_plan(conn, &conn->plan[IO_IN], false))
                        return;
 
        if (pollflags & POLLOUT)
-               do_plan(conn, &conn->plan[IO_OUT]);
+               /* If we're writing to a closed pipe, we need to wait for
+                * read to fail if we're duplex: we want to drain it! */
+               do_plan(conn, &conn->plan[IO_OUT],
+                       (conn->plan[IO_IN].status == IO_POLLING
+                        || conn->plan[IO_IN].status == IO_ALWAYS));
 }
 
 void io_do_always(struct io_conn *conn)