Add xcb_send_fd API

This uses sendmsg to transmit file descriptors from the application to
the X server

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-By: Uli Schlachter <psychon@znc.in>

1 files changed, 28 insertions, 3 deletions

diff --git a/src/xcb_conn.c b/src/xcb_conn.c
index 7dd25d3..c06c7cb 100644
--- a/src/xcb_conn.c
+++ b/src/xcb_conn.c
@@ -214,9 +214,34 @@ static int write_vec(xcb_connection_t *c, struct iovec **vector, int *count)
     if (n > IOV_MAX)
 	n = IOV_MAX;
 
-    n = writev(c->fd, *vector, n);
-    if(n < 0 && errno == EAGAIN)
-        return 1;
+#if HAVE_SENDMSG
+    if (c->out.out_fd.nfd) {
+        struct msghdr msg = {
+            .msg_name = NULL,
+            .msg_namelen = 0,
+            .msg_iov = *vector,
+            .msg_iovlen = n,
+            .msg_control = &c->out.out_fd,
+            .msg_controllen = sizeof (struct cmsghdr) + c->out.out_fd.nfd * sizeof (int),
+        };
+        int i;
+        c->out.out_fd.cmsghdr.cmsg_len = msg.msg_controllen;
+        c->out.out_fd.cmsghdr.cmsg_level = SOL_SOCKET;
+        c->out.out_fd.cmsghdr.cmsg_type = SCM_RIGHTS;
+        n = sendmsg(c->fd, &msg, 0);
+        if(n < 0 && errno == EAGAIN)
+            return 1;
+        for (i = 0; i < c->out.out_fd.nfd; i++)
+            close(c->out.out_fd.fd[i]);
+        c->out.out_fd.nfd = 0;
+    } else
+#endif
+    {
+        n = writev(c->fd, *vector, n);
+        if(n < 0 && errno == EAGAIN)
+            return 1;
+    }
+
 #endif /* _WIN32 */    
 
     if(n <= 0)