io: add io_fd_block() helper.

[ccan] / ccan / io / io.c

diff --git a/ccan/io/io.c b/ccan/io/io.c
index 68b95e82467194f13e87302e907cda5020fe37db..cc2b1afa3b27720adff4e3aa0b0c1d4fd4a393a3 100644 (file)
--- a/ccan/io/io.c
+++ b/ccan/io/io.c
@@ -72,16 +72,19 @@ static bool next_plan(struct io_conn *conn, struct io_plan *plan)
        return true;
 }
 
-static void set_blocking(int fd, bool block)
+bool io_fd_block(int fd, bool block)
 {
        int flags = fcntl(fd, F_GETFL);
 
+       if (flags == -1)
+               return false;
+
        if (block)
                flags &= ~O_NONBLOCK;
        else
                flags |= O_NONBLOCK;
 
-       fcntl(fd, F_SETFL, flags);
+       return fcntl(fd, F_SETFL, flags) != -1;
 }
 
 struct io_conn *io_new_conn_(const tal_t *ctx, int fd,
@@ -103,7 +106,7 @@ struct io_conn *io_new_conn_(const tal_t *ctx, int fd,
                return tal_free(conn);
 
        /* Keep our I/O async. */
-       set_blocking(fd, false);
+       io_fd_block(fd, false);
 
        /* We start with out doing nothing, and in doing our init. */
        conn->plan[IO_OUT].status = IO_UNSET;
@@ -392,12 +395,25 @@ void io_ready(struct io_conn *conn, int pollflags)
 
 void io_do_always(struct io_conn *conn)
 {
+       /* There's a corner case where the in next_plan wakes up the
+        * out, placing it in IO_ALWAYS and we end up processing it immediately,
+        * only to leave it in the always list.
+        *
+        * Yet we can't just process one, in case they are both supposed
+        * to be done, so grab state beforehand.
+        */
+       bool always_out = (conn->plan[IO_OUT].status == IO_ALWAYS);
+
        if (conn->plan[IO_IN].status == IO_ALWAYS)
                if (!next_plan(conn, &conn->plan[IO_IN]))
                        return;
 
-       if (conn->plan[IO_OUT].status == IO_ALWAYS)
+       if (always_out) {
+               /* You can't *unalways* a conn (except by freeing, in which
+                * case next_plan() returned false */
+               assert(conn->plan[IO_OUT].status == IO_ALWAYS);
                next_plan(conn, &conn->plan[IO_OUT]);
+       }
 }
 
 void io_do_wakeup(struct io_conn *conn, enum io_direction dir)
@@ -423,7 +439,7 @@ struct io_plan *io_close_cb(struct io_conn *conn, void *next_arg)
 
 struct io_plan *io_close_taken_fd(struct io_conn *conn)
 {
-       set_blocking(conn->fd.fd, true);
+       io_fd_block(conn->fd.fd, true);
 
        cleanup_conn_without_close(conn);
        return io_close(conn);
@@ -483,3 +499,37 @@ struct io_plan *io_set_plan(struct io_conn *conn, enum io_direction dir,
 
        return plan;
 }
+
+bool io_flush_sync(struct io_conn *conn)
+{
+       struct io_plan *plan = &conn->plan[IO_OUT];
+       bool ok;
+
+       /* Not writing?  Nothing to do. */
+       if (plan->status != IO_POLLING)
+               return true;
+
+       /* Synchronous please. */
+       io_fd_block(io_conn_fd(conn), true);
+
+again:
+       switch (plan->io(conn->fd.fd, &plan->arg)) {
+       case -1:
+               ok = false;
+               break;
+       /* Incomplete, try again. */
+       case 0:
+               goto again;
+       case 1:
+               ok = true;
+               /* In case they come back. */
+               set_always(conn, IO_OUT, plan->next, plan->next_arg);
+               break;
+       default:
+               /* IO should only return -1, 0 or 1 */
+               abort();
+       }
+
+       io_fd_block(io_conn_fd(conn), false);
+       return ok;
+}