vl: plumb keyval-based options into -readconfig

Let -readconfig support parsing command line options into QDict or
QemuOpts.  This will be used to add back support for objects in
-readconfig.

Cc: Markus Armbruster <armbru@redhat.com>
Cc: qemu-stable@nongnu.org
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210524105752.3318299-3-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/block/qdict.h

@@ -20,8 +20,6 @@ void qdict_join(QDict *dest, QDict *src, bool overwrite);
 void qdict_extract_subqdict(QDict *src, QDict **dst, const char *start);
 void qdict_array_split(QDict *src, QList **dst);
 int qdict_array_entries(QDict *src, const char *subqdict);
-QObject *qdict_crumple(const QDict *src, Error **errp);
-void qdict_flatten(QDict *qdict);
 
 typedef struct QDictRenames {
     const char *from;

include/qapi/qmp/qdict.h

@@ -64,4 +64,7 @@ const char *qdict_get_try_str(const QDict *qdict, const char *key);
 
 QDict *qdict_clone_shallow(const QDict *src);
 
+QObject *qdict_crumple(const QDict *src, Error **errp);
+void qdict_flatten(QDict *qdict);
+
 #endif /* QDICT_H */

softmmu/vl.c

@@ -121,6 +121,7 @@
 #include "qapi/qapi-commands-misc.h"
 #include "qapi/qapi-visit-qom.h"
 #include "qapi/qapi-commands-ui.h"
+#include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qerror.h"
 #include "sysemu/iothread.h"
 #include "qemu/guest-random.h"
@@ -2127,13 +2128,53 @@ static int global_init_func(void *opaque, QemuOpts *opts, Error **errp)
     return 0;
 }
 
+/*
+ * Return whether configuration group @group is stored in QemuOpts, or
+ * recorded as one or more QDicts by qemu_record_config_group.
+ */
+static bool is_qemuopts_group(const char *group)
+{
+    return true;
+}
+
+static void qemu_record_config_group(const char *group, QDict *dict,
+                                     bool from_json, Error **errp)
+{
+    abort();
+}
+
+/*
+ * Parse non-QemuOpts config file groups, pass the rest to
+ * qemu_config_do_parse.
+ */
+static void qemu_parse_config_group(const char *group, QDict *qdict,
+                                    void *opaque, Error **errp)
+{
+    QObject *crumpled;
+    if (is_qemuopts_group(group)) {
+        qemu_config_do_parse(group, qdict, opaque, errp);
+        return;
+    }
+
+    crumpled = qdict_crumple(qdict, errp);
+    if (!crumpled) {
+        return;
+    }
+    if (qobject_type(crumpled) != QTYPE_QDICT) {
+        assert(qobject_type(crumpled) == QTYPE_QLIST);
+        error_setg(errp, "Lists cannot be at top level of a configuration section");
+        return;
+    }
+    qemu_record_config_group(group, qobject_to(QDict, crumpled), false, errp);
+}
+
 static void qemu_read_default_config_file(Error **errp)
 {
     ERRP_GUARD();
     int ret;
     g_autofree char *file = get_relocated_path(CONFIG_QEMU_CONFDIR "/qemu.conf");
 
-    ret = qemu_read_config_file(file, qemu_config_do_parse, errp);
+    ret = qemu_read_config_file(file, qemu_parse_config_group, errp);
     if (ret < 0) {
         if (ret == -ENOENT) {
             error_free(*errp);
@@ -2142,9 +2183,8 @@ static void qemu_read_default_config_file(Error **errp)
     }
 }
 
-static int qemu_set_option(const char *str)
+static void qemu_set_option(const char *str, Error **errp)
 {
-    Error *local_err = NULL;
     char group[64], id[64], arg[64];
     QemuOptsList *list;
     QemuOpts *opts;
@@ -2152,27 +2192,23 @@ static int qemu_set_option(const char *str)
 
     rc = sscanf(str, "%63[^.].%63[^.].%63[^=]%n", group, id, arg, &offset);
     if (rc < 3 || str[offset] != '=') {
-        error_report("can't parse: \"%s\"", str);
-        return -1;
+        error_setg(errp, "can't parse: \"%s\"", str);
+        return;
     }
 
-    list = qemu_find_opts(group);
-    if (list == NULL) {
-        return -1;
+    if (!is_qemuopts_group(group)) {
+        error_setg(errp, "-set is not supported with %s", group);
+    } else {
+        list = qemu_find_opts_err(group, errp);
+        if (list) {
+            opts = qemu_opts_find(list, id);
+            if (!opts) {
+                error_setg(errp, "there is no %s \"%s\" defined", group, id);
+                return;
+            }
+            qemu_opt_set(opts, arg, str + offset + 1, errp);
+        }
     }
-
-    opts = qemu_opts_find(list, id);
-    if (!opts) {
-        error_report("there is no %s \"%s\" defined",
-                     list->name, id);
-        return -1;
-    }
-
-    if (!qemu_opt_set(opts, arg, str + offset + 1, &local_err)) {
-        error_report_err(local_err);
-        return -1;
-    }
-    return 0;
 }
 
 static void user_register_global_props(void)
@@ -2766,8 +2802,7 @@ void qemu_init(int argc, char **argv, char **envp)
                 }
                 break;
             case QEMU_OPTION_set:
-                if (qemu_set_option(optarg) != 0)
-                    exit(1);
+                qemu_set_option(optarg, &error_fatal);
                 break;
             case QEMU_OPTION_global:
                 if (qemu_global_option(optarg) != 0)
@@ -3399,7 +3434,7 @@ void qemu_init(int argc, char **argv, char **envp)
                 qemu_plugin_opt_parse(optarg, &plugin_list);
                 break;
             case QEMU_OPTION_readconfig:
-                qemu_read_config_file(optarg, qemu_config_do_parse, &error_fatal);
+                qemu_read_config_file(optarg, qemu_parse_config_group, &error_fatal);
                 break;
             case QEMU_OPTION_spice:
                 olist = qemu_find_opts_err("spice", NULL);