util: Add qemu_opts_to_qdict_filtered()

This allows, given a QemuOpts for a QemuOptsList that was merged from
multiple QemuOptsList, to only consider those options that exist in one
specific list. Block drivers need this to separate format-layer create
options from protocol-level options.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

include/qemu/option.h

@@ -124,6 +124,8 @@ void qemu_opts_set_defaults(QemuOptsList *list, const char *params,
                             int permit_abbrev);
 QemuOpts *qemu_opts_from_qdict(QemuOptsList *list, const QDict *qdict,
                                Error **errp);
+QDict *qemu_opts_to_qdict_filtered(QemuOpts *opts, QDict *qdict,
+                                   QemuOptsList *list, bool del);
 QDict *qemu_opts_to_qdict(QemuOpts *opts, QDict *qdict);
 void qemu_opts_absorb_qdict(QemuOpts *opts, QDict *qdict, Error **errp);
 

util/qemu-option.c

@@ -1007,14 +1007,23 @@ void qemu_opts_absorb_qdict(QemuOpts *opts, QDict *qdict, Error **errp)
 }
 
 /*
- * Convert from QemuOpts to QDict.
- * The QDict values are of type QString.
+ * Convert from QemuOpts to QDict. The QDict values are of type QString.
+ *
+ * If @list is given, only add those options to the QDict that are contained in
+ * the list. If @del is true, any options added to the QDict are removed from
+ * the QemuOpts, otherwise they remain there.
+ *
+ * If two options in @opts have the same name, they are processed in order
+ * so that the last one wins (consistent with the reverse iteration in
+ * qemu_opt_find()), but all of them are deleted if @del is true.
+ *
  * TODO We'll want to use types appropriate for opt->desc->type, but
  * this is enough for now.
  */
-QDict *qemu_opts_to_qdict(QemuOpts *opts, QDict *qdict)
+QDict *qemu_opts_to_qdict_filtered(QemuOpts *opts, QDict *qdict,
+                                   QemuOptsList *list, bool del)
 {
-    QemuOpt *opt;
+    QemuOpt *opt, *next;
 
     if (!qdict) {
         qdict = qdict_new();
@@ -1022,12 +1031,35 @@ QDict *qemu_opts_to_qdict(QemuOpts *opts, QDict *qdict)
     if (opts->id) {
         qdict_put_str(qdict, "id", opts->id);
     }
-    QTAILQ_FOREACH(opt, &opts->head, next) {
+    QTAILQ_FOREACH_SAFE(opt, &opts->head, next, next) {
+        if (list) {
+            QemuOptDesc *desc;
+            bool found = false;
+            for (desc = list->desc; desc->name; desc++) {
+                if (!strcmp(desc->name, opt->name)) {
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) {
+                continue;
+            }
+        }
         qdict_put_str(qdict, opt->name, opt->str);
+        if (del) {
+            qemu_opt_del(opt);
+        }
     }
     return qdict;
 }
 
+/* Copy all options in a QemuOpts to the given QDict. See
+ * qemu_opts_to_qdict_filtered() for details. */
+QDict *qemu_opts_to_qdict(QemuOpts *opts, QDict *qdict)
+{
+    return qemu_opts_to_qdict_filtered(opts, qdict, NULL, false);
+}
+
 /* Validate parsed opts against descriptions where no
  * descriptions were provided in the QemuOptsList.
  */