[PATCH v3] server: Add an API to get the socket fd for a client

[Sung-Jin Park]

This adds an API to get the socket fd for a client.
The client socket fd can be used for a wayland compositor to validate a request
from a client.
For instance, this will be helpful in some linux distributions, in which SELinux
or SMACK is enabled. In those environments, each file (including socket) will have
each security context in its inode as xattr member variable. A wayland compositor
can validate a client request by getting socket fd of the client and by checking
the security context associated with the socket fd.

Signed-off-by: Sung-Jin Park <input.hacker at gmail.com>
---
 src/wayland-server-core.h |  3 +++
 src/wayland-server.c      | 15 +++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/src/wayland-server-core.h b/src/wayland-server-core.h
index 1700cd3..e8e1e9c 100644
--- a/src/wayland-server-core.h
+++ b/src/wayland-server-core.h
@@ -182,6 +182,9 @@ void
 wl_client_get_credentials(struct wl_client *client,
 			  pid_t *pid, uid_t *uid, gid_t *gid);
 
+int
+wl_client_get_fd(struct wl_client *client);
+
 void
 wl_client_add_destroy_listener(struct wl_client *client,
 			       struct wl_listener *listener);
diff --git a/src/wayland-server.c b/src/wayland-server.c
index 2158c08..a6fbdcb 100644
--- a/src/wayland-server.c
+++ b/src/wayland-server.c
@@ -491,6 +491,21 @@ wl_client_get_credentials(struct wl_client *client,
 		*gid = client->ucred.gid;
 }
 
+/** Get the file descriptor for the client
+ *
+ * \param client The display object
+ * \return The file descriptor to use for the connection
+ *
+ * This function returns the file descriptor for the given client.
+ *
+ * \memberof wl_client
+ */
+WL_EXPORT int
+wl_client_get_fd(struct wl_client *client)
+{
+	return client->connection->fd;
+}
+
 /** Look up an object in the client name space
  *
  * \param client The client object
-- 
1.9.1