[Qemu-devel] [PATCH for-2.9 v3] qapi: add explicit null to string input and output visitors

[Greg Kurz <groug@kaod.org>]

This may be used for deprecated object properties that are kept for
backwards compatibility.

Signed-off-by: Greg Kurz <groug@kaod.org>
---
v3: - input visitor to error out if !siv->string

v2: - input visitor to reject non-empty strings
---
 qapi/string-input-visitor.c  |   11 +++++++++++
 qapi/string-output-visitor.c |   14 ++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index 8dfa5612522b..7a4efe32e346 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -314,6 +314,16 @@ static void parse_type_number(Visitor *v, const char *name, double *obj,
     *obj = val;
 }
 
+static void parse_type_null(Visitor *v, const char *name, Error **errp)
+{
+    StringInputVisitor *siv = to_siv(v);
+
+    if (!siv->string || siv->string[0]) {
+        error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
+                   "null");
+    }
+}
+
 static void parse_optional(Visitor *v, const char *name, bool *present)
 {
     StringInputVisitor *siv = to_siv(v);
@@ -348,6 +358,7 @@ Visitor *string_input_visitor_new(const char *str)
     v->visitor.type_bool = parse_type_bool;
     v->visitor.type_str = parse_type_str;
     v->visitor.type_number = parse_type_number;
+    v->visitor.type_null = parse_type_null;
     v->visitor.start_list = start_list;
     v->visitor.next_list = next_list;
     v->visitor.end_list = end_list;
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 94ac8211d144..5ec5352ca87c 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -266,6 +266,19 @@ static void print_type_number(Visitor *v, const char *name, double *obj,
     string_output_set(sov, g_strdup_printf("%f", *obj));
 }
 
+static void print_type_null(Visitor *v, const char *name, Error **errp)
+{
+    StringOutputVisitor *sov = to_sov(v);
+    char *out;
+
+    if (sov->human) {
+        out = g_strdup("<null>");
+    } else {
+        out = g_strdup("");
+    }
+    string_output_set(sov, out);
+}
+
 static void
 start_list(Visitor *v, const char *name, GenericList **list, size_t size,
            Error **errp)
@@ -351,6 +364,7 @@ Visitor *string_output_visitor_new(bool human, char **result)
     v->visitor.type_bool = print_type_bool;
     v->visitor.type_str = print_type_str;
     v->visitor.type_number = print_type_number;
+    v->visitor.type_null = print_type_null;
     v->visitor.start_list = start_list;
     v->visitor.next_list = next_list;
     v->visitor.end_list = end_list;