1 files changed, 19 insertions, 4 deletions

diff --git a/blockdev.c b/blockdev.c
index 48315e8..48bd9a3 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1871,14 +1871,17 @@ static void block_job_cb(void *opaque, int ret)
     bdrv_put_ref_bh_schedule(bs);
 }
 
-void qmp_block_stream(const char *device, bool has_base,
-                      const char *base, bool has_speed, int64_t speed,
+void qmp_block_stream(const char *device,
+                      bool has_base, const char *base,
+                      bool has_backing_file, const char *backing_file,
+                      bool has_speed, int64_t speed,
                       bool has_on_error, BlockdevOnError on_error,
                       Error **errp)
 {
     BlockDriverState *bs;
     BlockDriverState *base_bs = NULL;
     Error *local_err = NULL;
+    const char *base_name = NULL;
 
     if (!has_on_error) {
         on_error = BLOCKDEV_ON_ERROR_REPORT;
@@ -1894,15 +1897,27 @@ void qmp_block_stream(const char *device, bool has_base,
         return;
     }
 
-    if (base) {
+    if (has_base) {
         base_bs = bdrv_find_backing_image(bs, base);
         if (base_bs == NULL) {
             error_set(errp, QERR_BASE_NOT_FOUND, base);
             return;
         }
+        base_name = base;
     }
 
-    stream_start(bs, base_bs, base, has_speed ? speed : 0,
+    /* if we are streaming the entire chain, the result will have no backing
+     * file, and specifying one is therefore an error */
+    if (base_bs == NULL && has_backing_file) {
+        error_setg(errp, "backing file specified, but streaming the "
+                         "entire chain");
+        return;
+    }
+
+    /* backing_file string overrides base bs filename */
+    base_name = has_backing_file ? backing_file : base_name;
+
+    stream_start(bs, base_bs, base_name, has_speed ? speed : 0,
                  on_error, block_job_cb, bs, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);