monitor: introduce query-command-line-options

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

Signed-off-by: Amos Kong <akong@redhat.com>
CC: Luiz Capitulino <lcapitulino@redhat.com>
CC: Osier Yang <jyang@redhat.com>
CC: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

qapi-schema.json

@@ -3505,3 +3505,69 @@
     '*asl_compiler_rev':  'uint32',
     '*file':              'str',
     '*data':              'str' }}
+
+##
+# @CommandLineParameterType:
+#
+# Possible types for an option parameter.
+#
+# @string: accepts a character string
+#
+# @boolean: accepts "on" or "off"
+#
+# @number: accepts a number
+#
+# @size: accepts a number followed by an optional suffix (K)ilo,
+#        (M)ega, (G)iga, (T)era
+#
+# Since 1.5
+##
+{ 'enum': 'CommandLineParameterType',
+  'data': ['string', 'boolean', 'number', 'size'] }
+
+##
+# @CommandLineParameterInfo:
+#
+# Details about a single parameter of a command line option.
+#
+# @name: parameter name
+#
+# @type: parameter @CommandLineParameterType
+#
+# @help: #optional human readable text string, not suitable for parsing.
+#
+# Since 1.5
+##
+{ 'type': 'CommandLineParameterInfo',
+  'data': { 'name': 'str',
+            'type': 'CommandLineParameterType',
+            '*help': 'str' } }
+
+##
+# @CommandLineOptionInfo:
+#
+# Details about a command line option, including its list of parameter details
+#
+# @option: option name
+#
+# @parameters: an array of @CommandLineParameterInfo
+#
+# Since 1.5
+##
+{ 'type': 'CommandLineOptionInfo',
+  'data': { 'option': 'str', 'parameters': ['CommandLineParameterInfo'] } }
+
+##
+# @query-command-line-options:
+#
+# Query command line option schema.
+#
+# @option: #optional option name
+#
+# Returns: list of @CommandLineOptionInfo for all options (or for the given
+#          @option).  Returns an error if the given @option doesn't exist.
+#
+# Since 1.5
+##
+{'command': 'query-command-line-options', 'data': { '*option': 'str' },
+ 'returns': ['CommandLineOptionInfo'] }

qmp-commands.hx

@@ -2415,6 +2415,53 @@ EQMP
         .mhandler.cmd_new = qmp_marshal_input_query_uuid,
     },
 
+SQMP
+query-command-line-options
+--------------------------
+
+Show command line option schema.
+
+Return a json-array of command line option schema for all options (or for
+the given option), returning an error if the given option doesn't exist.
+
+Each array entry contains the following:
+
+- "option": option name (json-string)
+- "parameters": a json-array describes all parameters of the option:
+    - "name": parameter name (json-string)
+    - "type": parameter type (one of 'string', 'boolean', 'number',
+              or 'size')
+    - "help": human readable description of the parameter
+              (json-string, optional)
+
+Example:
+
+-> { "execute": "query-command-line-options", "arguments": { "option": "option-rom" } }
+<- { "return": [
+        {
+            "parameters": [
+                {
+                    "name": "romfile",
+                    "type": "string"
+                },
+                {
+                    "name": "bootindex",
+                    "type": "number"
+                }
+            ],
+            "option": "option-rom"
+        }
+     ]
+   }
+
+EQMP
+
+    {
+        .name       = "query-command-line-options",
+        .args_type  = "option:s?",
+        .mhandler.cmd_new = qmp_marshal_input_query_command_line_options,
+    },
+
 SQMP
 query-migrate
 -------------

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 +38,72 @@ QemuOptsList *qemu_find_opts(const char *group)
     return ret;
 }
 
+static CommandLineParameterInfoList *query_option_descs(const QemuOptDesc *desc)
+{
+    CommandLineParameterInfoList *param_list = NULL, *entry;
+    CommandLineParameterInfo *info;
+    int i;
+
+    for (i = 0; desc[i].name != NULL; i++) {
+        info = g_malloc0(sizeof(*info));
+        info->name = g_strdup(desc[i].name);
+
+        switch (desc[i].type) {
+        case QEMU_OPT_STRING:
+            info->type = COMMAND_LINE_PARAMETER_TYPE_STRING;
+            break;
+        case QEMU_OPT_BOOL:
+            info->type = COMMAND_LINE_PARAMETER_TYPE_BOOLEAN;
+            break;
+        case QEMU_OPT_NUMBER:
+            info->type = COMMAND_LINE_PARAMETER_TYPE_NUMBER;
+            break;
+        case QEMU_OPT_SIZE:
+            info->type = COMMAND_LINE_PARAMETER_TYPE_SIZE;
+            break;
+        }
+
+        if (desc[i].help) {
+            info->has_help = true;
+            info->help = g_strdup(desc[i].help);
+        }
+
+        entry = g_malloc0(sizeof(*entry));
+        entry->value = info;
+        entry->next = param_list;
+        param_list = entry;
+    }
+
+    return param_list;
+}
+
+CommandLineOptionInfoList *qmp_query_command_line_options(bool has_option,
+                                                          const char *option,
+                                                          Error **errp)
+{
+    CommandLineOptionInfoList *conf_list = NULL, *entry;
+    CommandLineOptionInfo *info;
+    int i;
+
+    for (i = 0; vm_config_groups[i] != NULL; i++) {
+        if (!has_option || !strcmp(option, vm_config_groups[i]->name)) {
+            info = g_malloc0(sizeof(*info));
+            info->option = g_strdup(vm_config_groups[i]->name);
+            info->parameters = query_option_descs(vm_config_groups[i]->desc);
+            entry = g_malloc0(sizeof(*entry));
+            entry->value = info;
+            entry->next = conf_list;
+            conf_list = entry;
+        }
+    }
+
+    if (conf_list == NULL) {
+        error_setg(errp, "invalid option name: %s", option);
+    }
+
+    return conf_list;
+}
+
 QemuOptsList *qemu_find_opts_err(const char *group, Error **errp)
 {
     return find_list(vm_config_groups, group, errp);