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/error.h"
  18 #include "qapi/qmp/dispatch.h"
  19 #include "qapi/qmp/qdict.h"
  20 #include "qapi/qmp/qjson.h"
  21 #include "sysemu/runstate.h"
  22 #include "qapi/qmp/qbool.h"
  23 #include "qemu/coroutine.h"
  24 #include "qemu/main-loop.h"
  25
  26 static QDict *qmp_dispatch_check_obj(QDict *dict, bool allow_oob,
  27                                      Error **errp)
  28 {
  29     const char *exec_key = NULL;
  30     const QDictEntry *ent;
  31     const char *arg_name;
  32     const QObject *arg_obj;
  33
  34     for (ent = qdict_first(dict); ent;
  35          ent = qdict_next(dict, ent)) {
  36         arg_name = qdict_entry_key(ent);
  37         arg_obj = qdict_entry_value(ent);
  38
  39         if (!strcmp(arg_name, "execute")
  40             || (!strcmp(arg_name, "exec-oob") && allow_oob)) {
  41             if (qobject_type(arg_obj) != QTYPE_QSTRING) {
  42                 error_setg(errp, "QMP input member '%s' must be a string",
  43                            arg_name);
  44                 return NULL;
  45             }
  46             if (exec_key) {
  47                 error_setg(errp, "QMP input member '%s' clashes with '%s'",
  48                            arg_name, exec_key);
  49                 return NULL;
  50             }
  51             exec_key = arg_name;
  52         } else if (!strcmp(arg_name, "arguments")) {
  53             if (qobject_type(arg_obj) != QTYPE_QDICT) {
  54                 error_setg(errp,
  55                            "QMP input member 'arguments' must be an object");
  56                 return NULL;
  57             }
  58         } else if (!strcmp(arg_name, "id")) {
  59             continue;
  60         } else {
  61             error_setg(errp, "QMP input member '%s' is unexpected",
  62                        arg_name);
  63             return NULL;
  64         }
  65     }
  66
  67     if (!exec_key) {
  68         error_setg(errp, "QMP input lacks member 'execute'");
  69         return NULL;
  70     }
  71
  72     return dict;
  73 }
  74
  75 QDict *qmp_error_response(Error *err)
  76 {
  77     QDict *rsp;
  78
  79     rsp = qdict_from_jsonf_nofail("{ 'error': { 'class': %s, 'desc': %s } }",
  80                                   QapiErrorClass_str(error_get_class(err)),
  81                                   error_get_pretty(err));
  82     error_free(err);
  83     return rsp;
  84 }
  85
  86 /*
  87  * Does @qdict look like a command to be run out-of-band?
  88  */
  89 bool qmp_is_oob(const QDict *dict)
  90 {
  91     return qdict_haskey(dict, "exec-oob")
  92         && !qdict_haskey(dict, "execute");
  93 }
  94
  95 typedef struct QmpDispatchBH {
  96     const QmpCommand *cmd;
  97     Monitor *cur_mon;
  98     QDict *args;
  99     QObject **ret;
 100     Error **errp;
 101     Coroutine *co;
 102 } QmpDispatchBH;
 103
 104 static void do_qmp_dispatch_bh(void *opaque)
 105 {
 106     QmpDispatchBH *data = opaque;
 107
 108     assert(monitor_cur() == NULL);
 109     monitor_set_cur(qemu_coroutine_self(), data->cur_mon);
 110     data->cmd->fn(data->args, data->ret, data->errp);
 111     monitor_set_cur(qemu_coroutine_self(), NULL);
 112     aio_co_wake(data->co);
 113 }
 114
 115 /*
 116  * Runs outside of coroutine context for OOB commands, but in coroutine
 117  * context for everything else.
 118  */
 119 QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
 120                     bool allow_oob, Monitor *cur_mon)
 121 {
 122     Error *err = NULL;
 123     bool oob;
 124     const char *command;
 125     QDict *args;
 126     const QmpCommand *cmd;
 127     QDict *dict;
 128     QObject *id;
 129     QObject *ret = NULL;
 130     QDict *rsp = NULL;
 131
 132     dict = qobject_to(QDict, request);
 133     if (!dict) {
 134         id = NULL;
 135         error_setg(&err, "QMP input must be a JSON object");
 136         goto out;
 137     }
 138
 139     id = qdict_get(dict, "id");
 140
 141     if (!qmp_dispatch_check_obj(dict, allow_oob, &err)) {
 142         goto out;
 143     }
 144
 145     command = qdict_get_try_str(dict, "execute");
 146     oob = false;
 147     if (!command) {
 148         assert(allow_oob);
 149         command = qdict_get_str(dict, "exec-oob");
 150         oob = true;
 151     }
 152     cmd = qmp_find_command(cmds, command);
 153     if (cmd == NULL) {
 154         error_set(&err, ERROR_CLASS_COMMAND_NOT_FOUND,
 155                   "The command %s has not been found", command);
 156         goto out;
 157     }
 158     if (!cmd->enabled) {
 159         error_set(&err, ERROR_CLASS_COMMAND_NOT_FOUND,
 160                   "The command %s has been disabled for this instance",
 161                   command);
 162         goto out;
 163     }
 164     if (oob && !(cmd->options & QCO_ALLOW_OOB)) {
 165         error_setg(&err, "The command %s does not support OOB",
 166                    command);
 167         goto out;
 168     }
 169
 170     if (!qmp_command_available(cmd, &err)) {
 171         goto out;
 172     }
 173
 174     if (!qdict_haskey(dict, "arguments")) {
 175         args = qdict_new();
 176     } else {
 177         args = qdict_get_qdict(dict, "arguments");
 178         qobject_ref(args);
 179     }
 180
 181     assert(!(oob && qemu_in_coroutine()));
 182     assert(monitor_cur() == NULL);
 183     if (!!(cmd->options & QCO_COROUTINE) == qemu_in_coroutine()) {
 184         monitor_set_cur(qemu_coroutine_self(), cur_mon);
 185         cmd->fn(args, &ret, &err);
 186         monitor_set_cur(qemu_coroutine_self(), NULL);
 187     } else {
 188        /*
 189         * Actual context doesn't match the one the command needs.
 190         *
 191         * Case 1: we are in coroutine context, but command does not
 192         * have QCO_COROUTINE.  We need to drop out of coroutine
 193         * context for executing it.
 194         *
 195         * Case 2: we are outside coroutine context, but command has
 196         * QCO_COROUTINE.  Can't actually happen, because we get here
 197         * outside coroutine context only when executing a command
 198         * out of band, and OOB commands never have QCO_COROUTINE.
 199         */
 200         assert(!oob && qemu_in_coroutine() && !(cmd->options & QCO_COROUTINE));
 201
 202         QmpDispatchBH data = {
 203             .cur_mon    = cur_mon,
 204             .cmd        = cmd,
 205             .args       = args,
 206             .ret        = &ret,
 207             .errp       = &err,
 208             .co         = qemu_coroutine_self(),
 209         };
 210         aio_bh_schedule_oneshot(qemu_get_aio_context(), do_qmp_dispatch_bh,
 211                                 &data);
 212         qemu_coroutine_yield();
 213     }
 214     qobject_unref(args);
 215     if (err) {
 216         /* or assert(!ret) after reviewing all handlers: */
 217         qobject_unref(ret);
 218         goto out;
 219     }
 220
 221     if (cmd->options & QCO_NO_SUCCESS_RESP) {
 222         g_assert(!ret);
 223         return NULL;
 224     } else if (!ret) {
 225         /*
 226          * When the command's schema has no 'returns', cmd->fn()
 227          * leaves @ret null.  The QMP spec calls for an empty object
 228          * then; supply it.
 229          */
 230         ret = QOBJECT(qdict_new());
 231     }
 232
 233     rsp = qdict_new();
 234     qdict_put_obj(rsp, "return", ret);
 235
 236 out:
 237     if (err) {
 238         assert(!rsp);
 239         rsp = qmp_error_response(err);
 240     }
 241
 242     assert(rsp);
 243
 244     if (id) {
 245         qdict_put_obj(rsp, "id", qobject_ref(id));
 246     }
 247
 248     return rsp;
 249 }