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 12b2489023d94077d5562db876ab9004caae3dd4..7eea9c35442cbbcb4386b430929195d1454b49a0 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;
@@ -360,14 +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:
@@ -383,11 +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)
@@ -436,7 +449,7 @@ 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);
@@ -507,7 +520,7 @@ bool io_flush_sync(struct io_conn *conn)
                return true;
 
        /* Synchronous please. */
-       set_blocking(io_conn_fd(conn), true);
+       io_fd_block(io_conn_fd(conn), true);
 
 again:
        switch (plan->io(conn->fd.fd, &plan->arg)) {
@@ -527,6 +540,6 @@ again:
                abort();
        }
 
-       set_blocking(io_conn_fd(conn), false);
+       io_fd_block(io_conn_fd(conn), false);
        return ok;
 }