[Xcb] [PATCH libxcb v2 1/4] xcb_send_fd(): Always close fds

[Uli Schlachter]

The API docs for xcb_send_fd() says "After this function returns, the file
descriptor given is owned by xcb and will be closed eventually".

Let the implementation live up to its documentation.

(This also does sneak in some preparatory functions for follow-up commits and
thus does things in a more complicated way than really necessary.)

Signed-off-by: Uli Schlachter <psychon at znc.in>
---
 src/xcb_out.c | 43 +++++++++++++++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 10 deletions(-)

diff --git a/src/xcb_out.c b/src/xcb_out.c
index 8cc5be8..51d911f 100644
--- a/src/xcb_out.c
+++ b/src/xcb_out.c
@@ -177,6 +177,33 @@ uint32_t xcb_get_maximum_request_length(xcb_connection_t *c)
     return c->out.maximum_request_length.value;
 }
 
+static void close_fds(unsigned int num_fds, int *fds)
+{
+    for (unsigned int index = 0; index < num_fds; index++)
+        close(fds[index]);
+}
+
+static void send_fds(xcb_connection_t *c, unsigned int num_fds, int *fds)
+{
+#if HAVE_SENDMSG
+    while (num_fds > 0) {
+        /* FIXME: This will busy-loop when XCB_MAX_PASS_FD fds are sent at once */
+        while (c->out.out_fd.nfd == XCB_MAX_PASS_FD) {
+            _xcb_out_flush_to(c, c->out.request);
+            if (c->has_error)
+                break;
+        }
+        if (!c->has_error)
+            c->out.out_fd.fd[c->out.out_fd.nfd++] = fds[0];
+
+        fds++;
+        num_fds--;
+    }
+#else
+    close_fds(num_fds, fds);
+#endif
+}
+
 uint64_t xcb_send_request64(xcb_connection_t *c, int flags, struct iovec *vector, const xcb_protocol_request_t *req)
 {
     uint64_t request;
@@ -295,19 +322,15 @@ unsigned int xcb_send_request(xcb_connection_t *c, int flags, struct iovec *vect
 void
 xcb_send_fd(xcb_connection_t *c, int fd)
 {
-#if HAVE_SENDMSG
-    if (c->has_error)
+    int fds[1] = { fd };
+
+    if (c->has_error) {
+        close(fd);
         return;
-    pthread_mutex_lock(&c->iolock);
-    while (c->out.out_fd.nfd == XCB_MAX_PASS_FD) {
-        _xcb_out_flush_to(c, c->out.request);
-        if (c->has_error)
-            break;
     }
-    if (!c->has_error)
-        c->out.out_fd.fd[c->out.out_fd.nfd++] = fd;
+    pthread_mutex_lock(&c->iolock);
+    send_fds(c, 1, &fds[0]);
     pthread_mutex_unlock(&c->iolock);
-#endif
 }
 
 int xcb_take_socket(xcb_connection_t *c, void (*return_socket)(void *closure), void *closure, int flags, uint64_t *sent)
-- 
2.1.4