From: 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>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 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 c089491..63ae115 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -326,6 +326,16 @@ 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 string_input_free(Visitor *v)
 {
     StringInputVisitor *siv = to_siv(v);
@@ -349,6 +359,7 @@ 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.check_list = check_list;
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 94ac821..5ec5352 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;
-- 
2.9.3

On Thu, 27 Apr 2017 17:28:40 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> From: 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>
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  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 c089491..63ae115 100644
> --- a/qapi/string-input-visitor.c
> +++ b/qapi/string-input-visitor.c
> @@ -326,6 +326,16 @@ 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");

I had boldly copied the error_setg() line from qobject_input_type_null(), but
I guess the 3rd argument ("null") isn't really appropriate to describe the
expected input in this case.

What about something like below ?

+        error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
+                   "empty string");

> +    }
> +}
> +
>  static void string_input_free(Visitor *v)
>  {
>      StringInputVisitor *siv = to_siv(v);
> @@ -349,6 +359,7 @@ 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.check_list = check_list;
> diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
> index 94ac821..5ec5352 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;