QMP: New argument checker (first part)

Current QMP's argument checker is more complex than it should be
and has (at least) one serious bug: it ignores unknown arguments.

To solve both problems we introduce a new argument checker. It's
added on top of the existing one, so that there are no regressions
during the transition.

This commit introduces the first part of the new checker, which
is run by qmp_check_client_args() and does the following:

  1. Check if all mandatory arguments were provided
  2. Set flags for argument validation

In order to do that, we transform the args_type string (from
qemu-montor.hx) into a qdict and iterate over it.

Next commit adds the new checker's second part: type checking and
invalid argument detection.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

1 files changed, 106 insertions, 0 deletions

diff --git a/monitor.c b/monitor.c
index 568bfb2f95..222622b772 100644
--- a/monitor.c
+++ b/monitor.c
@@ -177,6 +177,9 @@ static inline void mon_print_count_init(Monitor *mon) { }
 static inline int mon_print_count_get(const Monitor *mon) { return 0; }
 #endif /* CONFIG_DEBUG_MONITOR */
 
+/* QMP checker flags */
+#define QMP_ACCEPT_UNKNOWNS 1
+
 static QLIST_HEAD(mon_list, Monitor) mon_list;
 
 static const mon_cmd_t mon_cmds[];
@@ -4147,6 +4150,104 @@ static int invalid_qmp_mode(const Monitor *mon, const char *cmd_name)
     return (qmp_cmd_mode(mon) ? is_cap : !is_cap);
 }
 
+/*
+ * - Check if the client has passed all mandatory args
+ * - Set special flags for argument validation
+ */
+static int check_mandatory_args(const QDict *cmd_args,
+                                const QDict *client_args, int *flags)
+{
+    const QDictEntry *ent;
+
+    for (ent = qdict_first(cmd_args); ent; ent = qdict_next(cmd_args, ent)) {
+        const char *cmd_arg_name = qdict_entry_key(ent);
+        QString *type = qobject_to_qstring(qdict_entry_value(ent));
+        assert(type != NULL);
+
+        if (qstring_get_str(type)[0] == 'O') {
+            assert((*flags & QMP_ACCEPT_UNKNOWNS) == 0);
+            *flags |= QMP_ACCEPT_UNKNOWNS;
+        } else if (qstring_get_str(type)[0] != '-' &&
+                   qstring_get_str(type)[1] != '?' &&
+                   !qdict_haskey(client_args, cmd_arg_name)) {
+            qerror_report(QERR_MISSING_PARAMETER, cmd_arg_name);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+static QDict *qdict_from_args_type(const char *args_type)
+{
+    int i;
+    QDict *qdict;
+    QString *key, *type, *cur_qs;
+
+    assert(args_type != NULL);
+
+    qdict = qdict_new();
+
+    if (args_type == NULL || args_type[0] == '\0') {
+        /* no args, empty qdict */
+        goto out;
+    }
+
+    key = qstring_new();
+    type = qstring_new();
+
+    cur_qs = key;
+
+    for (i = 0;; i++) {
+        switch (args_type[i]) {
+            case ',':
+            case '\0':
+                qdict_put(qdict, qstring_get_str(key), type);
+                QDECREF(key);
+                if (args_type[i] == '\0') {
+                    goto out;
+                }
+                type = qstring_new(); /* qdict has ref */
+                cur_qs = key = qstring_new();
+                break;
+            case ':':
+                cur_qs = type;
+                break;
+            default:
+                qstring_append_chr(cur_qs, args_type[i]);
+                break;
+        }
+    }
+
+out:
+    return qdict;
+}
+
+/*
+ * Client argument checking rules:
+ *
+ * 1. Client must provide all mandatory arguments
+ */
+static int qmp_check_client_args(const mon_cmd_t *cmd, QDict *client_args)
+{
+    int flags, err;
+    QDict *cmd_args;
+
+    cmd_args = qdict_from_args_type(cmd->args_type);
+
+    flags = 0;
+    err = check_mandatory_args(cmd_args, client_args, &flags);
+    if (err) {
+        goto out;
+    }
+
+    /* TODO: Check client args type */
+
+out:
+    QDECREF(cmd_args);
+    return err;
+}
+
 static void handle_qmp_command(JSONMessageParser *parser, QList *tokens)
 {
     int err;
@@ -4222,6 +4323,11 @@ static void handle_qmp_command(JSONMessageParser *parser, QList *tokens)
 
     QDECREF(input);
 
+    err = qmp_check_client_args(cmd, args);
+    if (err < 0) {
+        goto err_out;
+    }
+
     err = monitor_check_qmp_args(cmd, args);
     if (err < 0) {
         goto err_out;