block: Always pass driver name through options QDict

The "driver" entry in the options QDict is now only missing if we're
opening an image with format probing.

We also catch cases now where both the drv argument and a "driver"
option is specified, e.g. by specifying -drive format=qcow2,driver=raw

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/block.c b/block.c
index 0d97fde..0aa444e 100644
--- a/block.c
+++ b/block.c
@@ -1037,14 +1037,13 @@
  * filename/flags pair to option QDict entries.
  */
 static int bdrv_fill_options(QDict **options, const char **pfilename, int flags,
-                             Error **errp)
+                             BlockDriver *drv, Error **errp)
 {
     const char *filename = *pfilename;
     const char *drvname;
     bool protocol = flags & BDRV_O_PROTOCOL;
     bool parse_filename = false;
     Error *local_err = NULL;
-    BlockDriver *drv;
 
     /* Parse json: pseudo-protocol */
     if (filename && g_str_has_prefix(filename, "json:")) {
@@ -1061,12 +1060,8 @@
         *pfilename = filename = NULL;
     }
 
-    if (!protocol) {
-        return 0;
-    }
-
     /* Fetch the file name from the options QDict if necessary */
-    if (filename) {
+    if (protocol && filename) {
         if (!qdict_haskey(*options, "filename")) {
             qdict_put(*options, "filename", qstring_from_str(filename));
             parse_filename = true;
@@ -1081,30 +1076,41 @@
     filename = qdict_get_try_str(*options, "filename");
     drvname = qdict_get_try_str(*options, "driver");
 
-    if (!drvname) {
-        if (filename) {
-            drv = bdrv_find_protocol(filename, parse_filename);
-            if (!drv) {
-                error_setg(errp, "Unknown protocol");
+    if (drv) {
+        if (drvname) {
+            error_setg(errp, "Driver specified twice");
+            return -EINVAL;
+        }
+        drvname = drv->format_name;
+        qdict_put(*options, "driver", qstring_from_str(drvname));
+    } else {
+        if (!drvname && protocol) {
+            if (filename) {
+                drv = bdrv_find_protocol(filename, parse_filename);
+                if (!drv) {
+                    error_setg(errp, "Unknown protocol");
+                    return -EINVAL;
+                }
+
+                drvname = drv->format_name;
+                qdict_put(*options, "driver", qstring_from_str(drvname));
+            } else {
+                error_setg(errp, "Must specify either driver or file");
                 return -EINVAL;
             }
-
-            drvname = drv->format_name;
-            qdict_put(*options, "driver", qstring_from_str(drvname));
-        } else {
-            error_setg(errp, "Must specify either driver or file");
-            return -EINVAL;
+        } else if (drvname) {
+            drv = bdrv_find_format(drvname);
+            if (!drv) {
+                error_setg(errp, "Unknown driver '%s'", drvname);
+                return -ENOENT;
+            }
         }
     }
 
-    drv = bdrv_find_format(drvname);
-    if (!drv) {
-        error_setg(errp, "Unknown driver '%s'", drvname);
-        return -ENOENT;
-    }
+    assert(drv || !protocol);
 
     /* Driver-specific filename parsing */
-    if (drv->bdrv_parse_filename && parse_filename) {
+    if (drv && drv->bdrv_parse_filename && parse_filename) {
         drv->bdrv_parse_filename(filename, *options, &local_err);
         if (local_err) {
             error_propagate(errp, local_err);
@@ -1438,7 +1444,7 @@
         options = qdict_new();
     }
 
-    ret = bdrv_fill_options(&options, &filename, flags, &local_err);
+    ret = bdrv_fill_options(&options, &filename, flags, drv, &local_err);
     if (local_err) {
         goto fail;
     }
@@ -1478,7 +1484,10 @@
     }
 
     /* Find the right image format driver */
+    drv = NULL;
     drvname = qdict_get_try_str(options, "driver");
+    assert(drvname || !(flags & BDRV_O_PROTOCOL));
+
     if (drvname) {
         drv = bdrv_find_format(drvname);
         qdict_del(options, "driver");
@@ -1487,19 +1496,14 @@
             ret = -EINVAL;
             goto fail;
         }
-    }
-
-    if (!drv) {
-        if (file) {
-            ret = find_image_format(file, filename, &drv, &local_err);
-        } else {
-            error_setg(errp, "Must specify either driver or file");
-            ret = -EINVAL;
+    } else if (file) {
+        ret = find_image_format(file, filename, &drv, &local_err);
+        if (ret < 0) {
             goto fail;
         }
-    }
-
-    if (!drv) {
+    } else {
+        error_setg(errp, "Must specify either driver or file");
+        ret = -EINVAL;
         goto fail;
     }
 
diff --git a/tests/qemu-iotests/051 b/tests/qemu-iotests/051
index c4af131..30a712f 100755
--- a/tests/qemu-iotests/051
+++ b/tests/qemu-iotests/051
@@ -92,6 +92,7 @@
 
 run_qemu -drive file="$TEST_IMG",format=foo
 run_qemu -drive file="$TEST_IMG",driver=foo
+run_qemu -drive file="$TEST_IMG",driver=raw,format=qcow2
 
 echo
 echo === Overriding backing file ===
diff --git a/tests/qemu-iotests/051.out b/tests/qemu-iotests/051.out
index 31e329e..94c7107 100644
--- a/tests/qemu-iotests/051.out
+++ b/tests/qemu-iotests/051.out
@@ -38,7 +38,10 @@
 QEMU_PROG: -drive file=TEST_DIR/t.qcow2,format=foo: 'foo' invalid format
 
 Testing: -drive file=TEST_DIR/t.qcow2,driver=foo
-QEMU_PROG: -drive file=TEST_DIR/t.qcow2,driver=foo: could not open disk image TEST_DIR/t.qcow2: Invalid driver: 'foo'
+QEMU_PROG: -drive file=TEST_DIR/t.qcow2,driver=foo: could not open disk image TEST_DIR/t.qcow2: Unknown driver 'foo'
+
+Testing: -drive file=TEST_DIR/t.qcow2,driver=raw,format=qcow2
+QEMU_PROG: -drive file=TEST_DIR/t.qcow2,driver=raw,format=qcow2: could not open disk image TEST_DIR/t.qcow2: Driver specified twice
 
 
 === Overriding backing file ===