qemu-option: Add qemu_opts_absorb_qdict()

This adds a function that adds all entries of a QDict to a QemuOpts if
the keys are known, and leaves only the rest in the QDict.

This way a single QDict of -drive options can be processed in multiple
places (generic block layer, block driver, backing file block driver,
etc.), where each part picks the options it knows. If at the end of the
process the QDict isn't empty, the user specified an invalid option.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

include/qemu/option.h

@@ -149,6 +149,7 @@ void qemu_opts_set_defaults(QemuOptsList *list, const char *params,
 QemuOpts *qemu_opts_from_qdict(QemuOptsList *list, const QDict *qdict,
                                Error **errp);
 QDict *qemu_opts_to_qdict(QemuOpts *opts, QDict *qdict);
+void qemu_opts_absorb_qdict(QemuOpts *opts, QDict *qdict, Error **errp);
 
 typedef int (*qemu_opts_loopfunc)(QemuOpts *opts, void *opaque);
 int qemu_opts_print(QemuOpts *opts, void *dummy);

util/qemu-option.c

@@ -1066,6 +1066,40 @@ QemuOpts *qemu_opts_from_qdict(QemuOptsList *list, const QDict *qdict,
     return opts;
 }
 
+/*
+ * Adds all QDict entries to the QemuOpts that can be added and removes them
+ * from the QDict. When this function returns, the QDict contains only those
+ * entries that couldn't be added to the QemuOpts.
+ */
+void qemu_opts_absorb_qdict(QemuOpts *opts, QDict *qdict, Error **errp)
+{
+    const QDictEntry *entry, *next;
+
+    entry = qdict_first(qdict);
+
+    while (entry != NULL) {
+        Error *local_err = NULL;
+        OptsFromQDictState state = {
+            .errp = &local_err,
+            .opts = opts,
+        };
+
+        next = qdict_next(qdict, entry);
+
+        if (find_desc_by_name(opts->list->desc, entry->key)) {
+            qemu_opts_from_qdict_1(entry->key, entry->value, &state);
+            if (error_is_set(&local_err)) {
+                error_propagate(errp, local_err);
+                return;
+            } else {
+                qdict_del(qdict, entry->key);
+            }
+        }
+
+        entry = next;
+    }
+}
+
 /*
  * Convert from QemuOpts to QDict.
  * The QDict values are of type QString.