kdbus.h, message: prepare for synchronous operations (ABI break)

diff --git a/kdbus.h b/kdbus.h
index 357212709b8a3b45e6b4a0829f963356f91e7968..fe0bb48728b163a22c957d9e7223e9ef21750b03 100644 (file)
--- a/kdbus.h
+++ b/kdbus.h
@@ -330,12 +330,23 @@ struct kdbus_item {
  *                                     cookie identifies the message and the
  *                                     respective reply carries the cookie
  *                                     in cookie_reply
+ * @KDBUS_MSG_FLAGS_SYNC_REPLY:                Wait for destination connection to
+ *                                     reply to this message. The
+ *                                     KDBUS_CMD_MSG_SEND ioctl() will block
+ *                                     until the reply is received, and
+ *                                     offset_reply in struct kdbus_msg will
+ *                                     yield the offset in the sender's pool
+ *                                     where the reply can be found.
+ *                                     This flag is only valid if
+ *                                     @KDBUS_MSG_FLAGS_EXPECT_REPLY is set as
+ *                                     well.
  * @KDBUS_MSG_FLAGS_NO_AUTO_START:     Do not start a service, if the addressed
  *                                     name is not currently active
  */
 enum kdbus_msg_flags {
        KDBUS_MSG_FLAGS_EXPECT_REPLY    = 1 << 0,
-       KDBUS_MSG_FLAGS_NO_AUTO_START   = 1 << 1,
+       KDBUS_MSG_FLAGS_SYNC_REPLY      = 1 << 1,
+       KDBUS_MSG_FLAGS_NO_AUTO_START   = 1 << 2,
 };
 
 /**
@@ -365,6 +376,9 @@ enum kdbus_payload_type {
  * @cookie_reply:      A reply to the requesting message with the same
  *                     cookie. The requesting connection can match its
  *                     request and the reply with this value
+ * @offset_reply:      If KDBUS_MSG_FLAGS_WAIT_FOR_REPLY, this field will
+ *                     contain the offset in the sender's pool where the
+ *                     reply is stored.
  * @items:             A list of kdbus_items containing the message payload
  */
 struct kdbus_msg {
@@ -378,6 +392,7 @@ struct kdbus_msg {
        union {
                __u64 timeout_ns;
                __u64 cookie_reply;
+               __u64 offset_reply;
        };
        struct kdbus_item items[0];
 } __attribute__((aligned(8)));

diff --git a/message.c b/message.c
index b36199f982ae36464b469b63e2dd43d82f281c70..3a65ba0c3e97c5bb7affeecba6a97438357304ee 100644 (file)
--- a/message.c
+++ b/message.c
@@ -280,6 +280,16 @@ int kdbus_kmsg_new_from_user(struct kdbus_conn *conn,
                goto exit_free;
        }
 
+       /*
+        * KDBUS_MSG_FLAGS_EXPECT_REPLY is only valid together with
+        * KDBUS_MSG_FLAGS_WAIT_FOR_REPLY
+        */
+       if ((m->msg.flags & KDBUS_MSG_FLAGS_SYNC_REPLY) &&
+           !((m->msg.flags & KDBUS_MSG_FLAGS_EXPECT_REPLY))) {
+               ret = -EINVAL;
+               goto exit_free;
+       }
+
        ret = kdbus_msg_scan_items(conn, m);
        if (ret < 0)
                goto exit_free;