introduce transport reply() handler (#313)

Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Thanos Makatos <thanos.makatos@nutanix.com>

3 files changed, 24 insertions, 10 deletions

diff --git a/lib/libvfio-user.c b/lib/libvfio-user.c
index e25787d..3192fd8 100644
--- a/lib/libvfio-user.c
+++ b/lib/libvfio-user.c
@@ -928,20 +928,17 @@ process_request(vfu_ctx_t *vfu_ctx)
         ret = 0;
     }
 
-    if (!(hdr.flags.no_reply)) {
-        // FIXME: SPEC: should the reply include the command? I'd say yes?
-        ret = tran_sock_send_iovec(vfu_ctx->conn_fd, hdr.msg_id, true, 0,
-                                   iovecs, nr_iovecs, fds_out, nr_fds_out,
-                                   -ret);
-        if (unlikely(ret < 0)) {
-            vfu_log(vfu_ctx, LOG_ERR, "failed to complete command: %s",
-                    strerror(-ret));
-        }
-    } else {
+    if (hdr.flags.no_reply) {
         /*
          * A failed client request is not a failure of process_request() itself.
          */
         ret = 0;
+    } else {
+        ret = vfu_ctx->trans->reply(vfu_ctx, hdr.msg_id, iovecs, nr_iovecs,
+                                    fds_out, nr_fds_out, -ret);
+        if (unlikely(ret < 0)) {
+            vfu_log(vfu_ctx, LOG_ERR, "failed to reply: %s", strerror(-ret));
+        }
     }
 
     if (iovecs != NULL) {
diff --git a/lib/private.h b/lib/private.h
index d1176ff..829bc3a 100644
--- a/lib/private.h
+++ b/lib/private.h
@@ -57,6 +57,10 @@ struct transport_ops {
     int (*get_request)(vfu_ctx_t *vfu_ctx, struct vfio_user_header *hdr,
                        int *fds, size_t *nr_fds);
 
+    int (*reply)(vfu_ctx_t *vfu_ctx, uint16_t msg_id,
+                 struct iovec *iovecs, size_t nr_iovecs,
+                 int *fds, int count, int err);
+
     int (*send_msg)(vfu_ctx_t *vfu_ctx, uint16_t msg_id,
                     enum vfio_user_command cmd,
                     void *send_data, size_t send_len,
diff --git a/lib/tran_sock.c b/lib/tran_sock.c
index f8838de..311f480 100644
--- a/lib/tran_sock.c
+++ b/lib/tran_sock.c
@@ -174,6 +174,8 @@ tran_sock_send_iovec(int sock, uint16_t msg_id, bool is_reply,
 
     return 0;
 }
+UNIT_TEST_SYMBOL(tran_sock_send_iovec);
+#define tran_sock_send_iovec __wrap_tran_sock_send_iovec
 
 int
 tran_sock_send(int sock, uint16_t msg_id, bool is_reply,
@@ -711,6 +713,16 @@ tran_sock_get_request(vfu_ctx_t *vfu_ctx, struct vfio_user_header *hdr,
 }
 
 static int
+tran_sock_reply(vfu_ctx_t *vfu_ctx, uint16_t msg_id,
+                struct iovec *iovecs, size_t nr_iovecs,
+                int *fds, int count, int err)
+{
+    // FIXME: SPEC: should the reply include the command? I'd say yes?
+    return tran_sock_send_iovec(vfu_ctx->conn_fd, msg_id, true, 0,
+                                iovecs, nr_iovecs, fds, count, err);
+}
+
+static int
 tran_sock_send_msg(vfu_ctx_t *vfu_ctx, uint16_t msg_id,
               enum vfio_user_command cmd,
               void *send_data, size_t send_len,
@@ -743,6 +755,7 @@ struct transport_ops tran_sock_ops = {
     .init = tran_sock_init,
     .attach = tran_sock_attach,
     .get_request = tran_sock_get_request,
+    .reply = tran_sock_reply,
     .send_msg = tran_sock_send_msg,
     .detach = tran_sock_detach,
     .fini = tran_sock_fini