qapi/qmp-dispatch.c

   1 /*
   2  * Core Definitions for QAPI/QMP Dispatch
   3  *
   4  * Copyright IBM, Corp. 2011
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
  10  * See the COPYING.LIB file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu/osdep.h"
  15
  16 #include "block/aio.h"
  17 #include "qapi/compat-policy.h"
  18 #include "qapi/error.h"
  19 #include "qapi/qmp/dispatch.h"
  20 #include "qapi/qmp/qdict.h"
  21 #include "qapi/qmp/qjson.h"
  22 #include "qapi/qobject-input-visitor.h"
  23 #include "qapi/qobject-output-visitor.h"
  24 #include "sysemu/runstate.h"
  25 #include "qapi/qmp/qbool.h"
  26 #include "qemu/coroutine.h"
  27 #include "qemu/main-loop.h"
  28
  29 CompatPolicy compat_policy;
  30
  31 Visitor *qobject_input_visitor_new_qmp(QObject *obj)
  32 {
  33     Visitor *v = qobject_input_visitor_new(obj);
  34
  35     qobject_input_visitor_set_policy(v, compat_policy.deprecated_input);
  36     return v;
  37 }
  38
  39 Visitor *qobject_output_visitor_new_qmp(QObject **result)
  40 {
  41     Visitor *v = qobject_output_visitor_new(result);
  42
  43     qobject_output_visitor_set_policy(v, compat_policy.deprecated_output);
  44     return v;
  45 }
  46
  47 static QDict *qmp_dispatch_check_obj(QDict *dict, bool allow_oob,
  48                                      Error **errp)
  49 {
  50     const char *exec_key = NULL;
  51     const QDictEntry *ent;
  52     const char *arg_name;
  53     const QObject *arg_obj;
  54
  55     for (ent = qdict_first(dict); ent;
  56          ent = qdict_next(dict, ent)) {
  57         arg_name = qdict_entry_key(ent);
  58         arg_obj = qdict_entry_value(ent);
  59
  60         if (!strcmp(arg_name, "execute")
  61             || (!strcmp(arg_name, "exec-oob") && allow_oob)) {
  62             if (qobject_type(arg_obj) != QTYPE_QSTRING) {
  63                 error_setg(errp, "QMP input member '%s' must be a string",
  64                            arg_name);
  65                 return NULL;
  66             }
  67             if (exec_key) {
  68                 error_setg(errp, "QMP input member '%s' clashes with '%s'",
  69                            arg_name, exec_key);
  70                 return NULL;
  71             }
  72             exec_key = arg_name;
  73         } else if (!strcmp(arg_name, "arguments")) {
  74             if (qobject_type(arg_obj) != QTYPE_QDICT) {
  75                 error_setg(errp,
  76                            "QMP input member 'arguments' must be an object");
  77                 return NULL;
  78             }
  79         } else if (!strcmp(arg_name, "id")) {
  80             continue;
  81         } else {
  82             error_setg(errp, "QMP input member '%s' is unexpected",
  83                        arg_name);
  84             return NULL;
  85         }
  86     }
  87
  88     if (!exec_key) {
  89         error_setg(errp, "QMP input lacks member 'execute'");
  90         return NULL;
  91     }
  92
  93     return dict;
  94 }
  95
  96 QDict *qmp_error_response(Error *err)
  97 {
  98     QDict *rsp;
  99
 100     rsp = qdict_from_jsonf_nofail("{ 'error': { 'class': %s, 'desc': %s } }",
 101                                   QapiErrorClass_str(error_get_class(err)),
 102                                   error_get_pretty(err));
 103     error_free(err);
 104     return rsp;
 105 }
 106
 107 /*
 108  * Does @qdict look like a command to be run out-of-band?
 109  */
 110 bool qmp_is_oob(const QDict *dict)
 111 {
 112     return qdict_haskey(dict, "exec-oob")
 113         && !qdict_haskey(dict, "execute");
 114 }
 115
 116 typedef struct QmpDispatchBH {
 117     const QmpCommand *cmd;
 118     Monitor *cur_mon;
 119     QDict *args;
 120     QObject **ret;
 121     Error **errp;
 122     Coroutine *co;
 123 } QmpDispatchBH;
 124
 125 static void do_qmp_dispatch_bh(void *opaque)
 126 {
 127     QmpDispatchBH *data = opaque;
 128
 129     assert(monitor_cur() == NULL);
 130     monitor_set_cur(qemu_coroutine_self(), data->cur_mon);
 131     data->cmd->fn(data->args, data->ret, data->errp);
 132     monitor_set_cur(qemu_coroutine_self(), NULL);
 133     aio_co_wake(data->co);
 134 }
 135
 136 /*
 137  * Runs outside of coroutine context for OOB commands, but in coroutine
 138  * context for everything else.
 139  */
 140 QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
 141                     bool allow_oob, Monitor *cur_mon)
 142 {
 143     Error *err = NULL;
 144     bool oob;
 145     const char *command;
 146     QDict *args;
 147     const QmpCommand *cmd;
 148     QDict *dict;
 149     QObject *id;
 150     QObject *ret = NULL;
 151     QDict *rsp = NULL;
 152
 153     dict = qobject_to(QDict, request);
 154     if (!dict) {
 155         id = NULL;
 156         error_setg(&err, "QMP input must be a JSON object");
 157         goto out;
 158     }
 159
 160     id = qdict_get(dict, "id");
 161
 162     if (!qmp_dispatch_check_obj(dict, allow_oob, &err)) {
 163         goto out;
 164     }
 165
 166     command = qdict_get_try_str(dict, "execute");
 167     oob = false;
 168     if (!command) {
 169         assert(allow_oob);
 170         command = qdict_get_str(dict, "exec-oob");
 171         oob = true;
 172     }
 173     cmd = qmp_find_command(cmds, command);
 174     if (cmd == NULL) {
 175         error_set(&err, ERROR_CLASS_COMMAND_NOT_FOUND,
 176                   "The command %s has not been found", command);
 177         goto out;
 178     }
 179     if (cmd->options & QCO_DEPRECATED) {
 180         switch (compat_policy.deprecated_input) {
 181         case COMPAT_POLICY_INPUT_ACCEPT:
 182             break;
 183         case COMPAT_POLICY_INPUT_REJECT:
 184             error_set(&err, ERROR_CLASS_COMMAND_NOT_FOUND,
 185                       "Deprecated command %s disabled by policy",
 186                       command);
 187             goto out;
 188         case COMPAT_POLICY_INPUT_CRASH:
 189         default:
 190             abort();
 191         }
 192     }
 193     if (!cmd->enabled) {
 194         error_set(&err, ERROR_CLASS_COMMAND_NOT_FOUND,
 195                   "Command %s has been disabled%s%s",
 196                   command,
 197                   cmd->disable_reason ? ": " : "",
 198                   cmd->disable_reason ?: "");
 199         goto out;
 200     }
 201     if (oob && !(cmd->options & QCO_ALLOW_OOB)) {
 202         error_setg(&err, "The command %s does not support OOB",
 203                    command);
 204         goto out;
 205     }
 206
 207     if (!qmp_command_available(cmd, &err)) {
 208         goto out;
 209     }
 210
 211     if (!qdict_haskey(dict, "arguments")) {
 212         args = qdict_new();
 213     } else {
 214         args = qdict_get_qdict(dict, "arguments");
 215         qobject_ref(args);
 216     }
 217
 218     assert(!(oob && qemu_in_coroutine()));
 219     assert(monitor_cur() == NULL);
 220     if (!!(cmd->options & QCO_COROUTINE) == qemu_in_coroutine()) {
 221         monitor_set_cur(qemu_coroutine_self(), cur_mon);
 222         cmd->fn(args, &ret, &err);
 223         monitor_set_cur(qemu_coroutine_self(), NULL);
 224     } else {
 225        /*
 226         * Actual context doesn't match the one the command needs.
 227         *
 228         * Case 1: we are in coroutine context, but command does not
 229         * have QCO_COROUTINE.  We need to drop out of coroutine
 230         * context for executing it.
 231         *
 232         * Case 2: we are outside coroutine context, but command has
 233         * QCO_COROUTINE.  Can't actually happen, because we get here
 234         * outside coroutine context only when executing a command
 235         * out of band, and OOB commands never have QCO_COROUTINE.
 236         */
 237         assert(!oob && qemu_in_coroutine() && !(cmd->options & QCO_COROUTINE));
 238
 239         QmpDispatchBH data = {
 240             .cur_mon    = cur_mon,
 241             .cmd        = cmd,
 242             .args       = args,
 243             .ret        = &ret,
 244             .errp       = &err,
 245             .co         = qemu_coroutine_self(),
 246         };
 247         aio_bh_schedule_oneshot(qemu_get_aio_context(), do_qmp_dispatch_bh,
 248                                 &data);
 249         qemu_coroutine_yield();
 250     }
 251     qobject_unref(args);
 252     if (err) {
 253         /* or assert(!ret) after reviewing all handlers: */
 254         qobject_unref(ret);
 255         goto out;
 256     }
 257
 258     if (cmd->options & QCO_NO_SUCCESS_RESP) {
 259         g_assert(!ret);
 260         return NULL;
 261     } else if (!ret) {
 262         /*
 263          * When the command's schema has no 'returns', cmd->fn()
 264          * leaves @ret null.  The QMP spec calls for an empty object
 265          * then; supply it.
 266          */
 267         ret = QOBJECT(qdict_new());
 268     }
 269
 270     rsp = qdict_new();
 271     qdict_put_obj(rsp, "return", ret);
 272
 273 out:
 274     if (err) {
 275         assert(!rsp);
 276         rsp = qmp_error_response(err);
 277     }
 278
 279     assert(rsp);
 280
 281     if (id) {
 282         qdict_put_obj(rsp, "id", qobject_ref(id));
 283     }
 284
 285     return rsp;
 286 }