[Qemu-devel] [PATCH] monitor: introduce query-config-schema command

[Amos Kong <akong@redhat.com>]

Libvirt has no way to probe if an option or property is supported,
This patch introdues a new qmp command to query configuration schema
information. hmp command isn't added because it's not needed.

V2: fix jaso schema and comments (Eric)

Signed-off-by: Amos Kong <akong@redhat.com>
CC: Osier Yang <jyang@redhat.com>
CC: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Amos Kong <akong@redhat.com>
---
 qapi-schema.json   | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qmp-commands.hx    | 43 ++++++++++++++++++++++++++++++++++++
 util/qemu-config.c | 51 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 158 insertions(+)

diff --git a/qapi-schema.json b/qapi-schema.json
index 751d3c2..55aee4a 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3505,3 +3505,67 @@
     '*asl_compiler_rev':  'uint32',
     '*file':              'str',
     '*data':              'str' }}
+
+##
+# @ConfigParamType:
+#
+# JSON representation of values of QEMUOptionParType, may grow in future
+#
+# @flag: If no value is given, the flag is set to 1. Otherwise the value must
+#        be "on" (set to 1) or "off" (set to 0)
+#
+# @number: Simple number
+#
+# @size: The value is converted to an integer. Suffixes for kilobytes etc
+#
+# @string: Character string
+#
+# Since 1.5
+##
+{ 'enum': 'ConfigParamType',
+  'data': [ 'flag', 'number', 'size', 'string' ] }
+
+##
+# @ConfigParamInfo:
+#
+# JSON representation of QEMUOptionParameter, may grow in future
+#
+# @name: parameter name
+#
+# @type: parameter type
+#
+# @help is optional if no text was present
+#
+# Since 1.5
+##
+{ 'type': 'ConfigParamInfo',
+  'data': { 'name': 'str', 'type': 'ConfigParamType', '*help':'str' } }
+
+##
+# @ConfigSchemaInfo:
+#
+# Each command line option, and its list of parameters
+#
+# @option: option name
+#
+# @params: a list of parameters of one option
+#
+# Since 1.5
+##
+{ 'type': 'ConfigSchemaInfo',
+  'data': { 'option':'str', 'params': ['ConfigParamInfo'] } }
+
+##
+# @query-config-schema:
+#
+# Query configuration schema information
+#
+# @option: #optional option name
+#
+# Returns: list of @ConfigSchemaInfo for all options (or for the given
+#          @option).  Returns an error if a given @option doesn't exist.
+#
+# Since 1.5
+##
+{'command': 'query-config-schema', 'data': {'*option': 'str'},
+ 'returns': ['ConfigSchemaInfo']}
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 4d65422..19415e4 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -2414,6 +2414,49 @@ EQMP
         .args_type  = "",
         .mhandler.cmd_new = qmp_marshal_input_query_uuid,
     },
+SQMP
+query-config-schema
+------------
+
+Show configuration schema.
+
+Return list of configuration schema of all options (or for the given option),
+return an error if given option doesn't exist.
+
+- "option": option name
+- "params": parameters infomation list of one option
+- "name": parameter name
+- "type": parameter type
+- "help": parameter help message
+
+Example:
+
+-> {"execute": "query-config-schema", "arguments" : {"option": "option-rom"}}
+<- {
+    "return": [
+        {
+            "params": [
+                {
+                    "name": "romfile",
+                    "type": "flag"
+                },
+                {
+                    "name": "bootindex",
+                    "type": "size"
+                }
+            ],
+            "option": "option-rom"
+        }
+    ]
+  }
+
+EQMP
+
+    {
+        .name       = "query-config-schema",
+        .args_type  = "option:s?",
+        .mhandler.cmd_new = qmp_marshal_input_query_config_schema,
+    },
 
 SQMP
 query-migrate
diff --git a/util/qemu-config.c b/util/qemu-config.c
index 01ca890..6d93642 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -5,6 +5,7 @@
 #include "qapi/qmp/qerror.h"
 #include "hw/qdev.h"
 #include "qapi/error.h"
+#include "qmp-commands.h"
 
 static QemuOptsList *vm_config_groups[32];
 
@@ -37,6 +38,56 @@ QemuOptsList *qemu_find_opts(const char *group)
     return ret;
 }
 
+ConfigSchemaInfoList *qmp_query_config_schema(bool has_option,
+                                              const char *option, Error **errp)
+{
+    ConfigSchemaInfoList *conf_list = NULL, *conf_entry;
+    ConfigSchemaInfo *schema_info;
+    ConfigParamInfoList *param_list = NULL, *param_entry;
+    ConfigParamInfo *param_info;
+    int entries, i, j;
+
+    entries = ARRAY_SIZE(vm_config_groups);
+
+    for (i = 0; i < entries; i++) {
+        if (vm_config_groups[i] != NULL &&
+            (!has_option || !strcmp(option, vm_config_groups[i]->name))) {
+            schema_info = g_malloc0(sizeof(*schema_info));
+            schema_info->option = g_strdup(vm_config_groups[i]->name);
+            param_list = NULL;
+
+            for (j = 0; vm_config_groups[i]->desc[j].name != NULL; j++) {
+                param_info =  g_malloc0(sizeof(*param_info));
+                param_info->name = g_strdup(vm_config_groups[i]->desc[j].name);
+                param_info->type = vm_config_groups[i]->desc[j].type;
+
+                if (vm_config_groups[i]->desc[j].help) {
+                    param_info->has_help = true;
+                    param_info->help = g_strdup(
+                    vm_config_groups[i]->desc[j].help);
+                }
+
+                param_entry = g_malloc0(sizeof(*param_entry));
+                param_entry->value = param_info;
+                param_entry->next = param_list;
+                param_list = param_entry;
+            }
+
+            schema_info->params = param_list;
+            conf_entry = g_malloc0(sizeof(*conf_entry));
+            conf_entry->value = schema_info;
+            conf_entry->next = conf_list;
+            conf_list = conf_entry;
+        }
+    }
+
+    if (conf_list == NULL) {
+        error_set(errp, QERR_INVALID_OPTION_GROUP, option);
+    }
+
+    return conf_list;
+}
+
 QemuOptsList *qemu_find_opts_err(const char *group, Error **errp)
 {
     return find_list(vm_config_groups, group, errp);
-- 
1.8.1.4