[Qemu-devel] [PATCH] qmp: expose list of supported character device backends

[Qemu-devel] [PATCH] qmp: expose list of supported character device backends

[Martin Kletzander]

Introduce 'query-chardev-backends' QMP command which lists all
supported character device backends.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
---
 qapi-schema.json | 22 ++++++++++++++++++++++
 qemu-char.c      | 19 +++++++++++++++++++
 qmp-commands.hx  | 41 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+)

diff --git a/qapi-schema.json b/qapi-schema.json
index 05ced9d..ac1061f 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -437,6 +437,28 @@
 { 'command': 'query-chardev', 'returns': ['ChardevInfo'] }

 ##
+# @ChardevBackendInfo:
+#
+# Information about a character device backend
+#
+# @name: The backend name
+#
+# Since: 1.8.0
+##
+{ 'type': 'ChardevBackendInfo', 'data': {'name': 'str'} }
+
+##
+# @query-chardev-backends:
+#
+# Returns information about character device backends.
+#
+# Returns: a list of @ChardevBackendInfo
+#
+# Since: 1.8.0
+##
+{ 'command': 'query-chardev-backends', 'returns': ['ChardevBackendInfo'] }
+
+##
 # @DataFormat:
 #
 # An enumeration of data format.
diff --git a/qemu-char.c b/qemu-char.c
index 30c5a6a..c88f1c4 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -3432,6 +3432,25 @@ ChardevInfoList *qmp_query_chardev(Error **errp)
     return chr_list;
 }

+ChardevBackendInfoList *qmp_query_chardev_backends(Error **errp)
+{
+    ChardevBackendInfoList *backend_list = NULL;
+    CharDriver *c = NULL;
+    GSList *i = NULL;
+
+    for (i = backends; i; i = i->next) {
+        ChardevBackendInfoList *info = g_malloc0(sizeof(*info));
+        c = i->data;
+        info->value = g_malloc0(sizeof(*info->value));
+        info->value->name = g_strdup(c->name);
+
+        info->next = backend_list;
+        backend_list = info;
+    }
+
+    return backend_list;
+}
+
 CharDriverState *qemu_chr_find(const char *name)
 {
     CharDriverState *chr;
diff --git a/qmp-commands.hx b/qmp-commands.hx
index cce6b81..c38964d 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1924,6 +1924,47 @@ EQMP
     },

 SQMP
+query-chardev-backends
+-------------
+
+List available character device backends.
+
+Each backend is represented by a json-object, the returned value is a json-array
+of all backends.
+
+Each json-object contains:
+
+- "name": backend name (json-string)
+
+Example:
+
+-> { "execute": "query-chardev-backends" }
+<- {
+      "return":[
+         {
+            "name":"udp",
+         },
+         {
+            "name":"tcp",
+         },
+         {
+            "name":"unix",
+         },
+         {
+            "name":"spiceport",
+         }
+      ]
+   }
+
+EQMP
+
+    {
+        .name       = "query-chardev-backends",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_query_chardev_backends,
+    },
+
+SQMP
 query-block
 -----------

-- 
1.8.5.3

Re: [Qemu-devel] [PATCH] qmp: expose list of supported character device backends

[Eric Blake]

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On 01/31/2014 03:35 AM, Martin Kletzander wrote:
> Introduce 'query-chardev-backends' QMP command which lists all
> supported character device backends.
> 
> Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
> ---
>  qapi-schema.json | 22 ++++++++++++++++++++++
>  qemu-char.c      | 19 +++++++++++++++++++
>  qmp-commands.hx  | 41 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 82 insertions(+)
> 
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 05ced9d..ac1061f 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -437,6 +437,28 @@
>  { 'command': 'query-chardev', 'returns': ['ChardevInfo'] }
> 
>  ##
> +# @ChardevBackendInfo:
> +#
> +# Information about a character device backend
> +#
> +# @name: The backend name
> +#
> +# Since: 1.8.0

2.0 will be the next release.

> +##
> +{ 'type': 'ChardevBackendInfo', 'data': {'name': 'str'} }
> +
> +##
> +# @query-chardev-backends:
> +#
> +# Returns information about character device backends.
> +#
> +# Returns: a list of @ChardevBackendInfo
> +#
> +# Since: 1.8.0

Again, 2.0.


> +
> +-> { "execute": "query-chardev-backends" }
> +<- {
> +      "return":[
> +         {
> +            "name":"udp",
> +         },

This is somewhat complex, but allows us the option of future addition of
other items to return in addition to the name, if it proves useful
(returning a straight array of strings instead of an array of structs
prevents such future expansion).  So I think you made the right choice.

With the fixes to the version number:

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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