| 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 "qemu/aio.h" |
| 17 | #include "qemu/aio-wait.h" |
| 18 | #include "qapi/compat-policy.h" |
| 19 | #include "qapi/error.h" |
| 20 | #include "qapi/qmp-registry.h" |
| 21 | #include "qobject/qdict.h" |
| 22 | #include "qobject/qjson.h" |
| 23 | #include "qapi/qobject-input-visitor.h" |
| 24 | #include "qapi/qobject-output-visitor.h" |
| 25 | #include "qobject/qbool.h" |
| 26 | #include "qemu/coroutine.h" |
| 27 | #include "qemu/main-loop.h" |
| 28 | #include "monitor/monitor.h" |
| 29 | |
| 30 | Visitor *qobject_input_visitor_new_qmp(QObject *obj) |
| 31 | { |
| 32 | Visitor *v = qobject_input_visitor_new(obj); |
| 33 | |
| 34 | visit_set_policy(v, &compat_policy); |
| 35 | return v; |
| 36 | } |
| 37 | |
| 38 | Visitor *qobject_output_visitor_new_qmp(QObject **result) |
| 39 | { |
| 40 | Visitor *v = qobject_output_visitor_new(result); |
| 41 | |
| 42 | visit_set_policy(v, &compat_policy); |
| 43 | return v; |
| 44 | } |
| 45 | |
| 46 | static QDict *qmp_dispatch_check_obj(QDict *dict, bool allow_oob, |
| 47 | Error **errp) |
| 48 | { |
| 49 | const char *exec_key = NULL; |
| 50 | const QDictEntry *ent; |
| 51 | const char *arg_name; |
| 52 | const QObject *arg_obj; |
| 53 | |
| 54 | for (ent = qdict_first(dict); ent; |
| 55 | ent = qdict_next(dict, ent)) { |
| 56 | arg_name = qdict_entry_key(ent); |
| 57 | arg_obj = qdict_entry_value(ent); |
| 58 | |
| 59 | if (!strcmp(arg_name, "execute") |
| 60 | || (!strcmp(arg_name, "exec-oob") && allow_oob)) { |
| 61 | if (qobject_type(arg_obj) != QTYPE_QSTRING) { |
| 62 | error_setg(errp, "QMP input member '%s' must be a string", |
| 63 | arg_name); |
| 64 | return NULL; |
| 65 | } |
| 66 | if (exec_key) { |
| 67 | error_setg(errp, "QMP input member '%s' clashes with '%s'", |
| 68 | arg_name, exec_key); |
| 69 | return NULL; |
| 70 | } |
| 71 | exec_key = arg_name; |
| 72 | } else if (!strcmp(arg_name, "arguments")) { |
| 73 | if (qobject_type(arg_obj) != QTYPE_QDICT) { |
| 74 | error_setg(errp, |
| 75 | "QMP input member 'arguments' must be an object"); |
| 76 | return NULL; |
| 77 | } |
| 78 | } else if (!strcmp(arg_name, "id")) { |
| 79 | continue; |
| 80 | } else { |
| 81 | error_setg(errp, "QMP input member '%s' is unexpected", |
| 82 | arg_name); |
| 83 | return NULL; |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | if (!exec_key) { |
| 88 | error_setg(errp, "QMP input lacks member 'execute'"); |
| 89 | return NULL; |
| 90 | } |
| 91 | |
| 92 | return dict; |
| 93 | } |
| 94 | |
| 95 | QDict *qmp_error_response(Error *err) |
| 96 | { |
| 97 | QDict *rsp; |
| 98 | |
| 99 | rsp = qdict_from_jsonf_nofail("{ 'error': { 'class': %s, 'desc': %s } }", |
| 100 | QapiErrorClass_str(error_get_class(err)), |
| 101 | error_get_pretty(err)); |
| 102 | error_free(err); |
| 103 | return rsp; |
| 104 | } |
| 105 | |
| 106 | /* |
| 107 | * Does @qdict look like a command to be run out-of-band? |
| 108 | */ |
| 109 | bool qmp_is_oob(const QDict *dict) |
| 110 | { |
| 111 | return qdict_haskey(dict, "exec-oob") |
| 112 | && !qdict_haskey(dict, "execute"); |
| 113 | } |
| 114 | |
| 115 | typedef struct QmpDispatchBH { |
| 116 | const QmpCommand *cmd; |
| 117 | Monitor *cur_mon; |
| 118 | QDict *args; |
| 119 | QObject **ret; |
| 120 | Error **errp; |
| 121 | Coroutine *co; |
| 122 | } QmpDispatchBH; |
| 123 | |
| 124 | static void do_qmp_dispatch_bh(void *opaque) |
| 125 | { |
| 126 | QmpDispatchBH *data = opaque; |
| 127 | |
| 128 | assert(monitor_cur() == NULL); |
| 129 | monitor_set_cur(qemu_coroutine_self(), data->cur_mon); |
| 130 | data->cmd->fn(data->args, data->ret, data->errp); |
| 131 | monitor_set_cur(qemu_coroutine_self(), NULL); |
| 132 | aio_co_wake(data->co); |
| 133 | |
| 134 | /* |
| 135 | * If the QMP dispatcher coroutine is waiting to be scheduled |
| 136 | * in iohandler_ctx, we must kick the main loop. This ensures |
| 137 | * that AIO_WAIT_WHILE_UNLOCKED() in monitor_cleanup() doesn't |
| 138 | * block indefinitely waiting for an event in qemu_aio_context, |
| 139 | * but actually gets the chance to poll iohandler_ctx and resume |
| 140 | * the coroutine. |
| 141 | */ |
| 142 | aio_wait_kick(); |
| 143 | } |
| 144 | |
| 145 | /* |
| 146 | * Runs outside of coroutine context for OOB commands, but in coroutine |
| 147 | * context for everything else. |
| 148 | */ |
| 149 | QDict *coroutine_mixed_fn qmp_dispatch(const QmpCommandList *cmds, QObject *request, |
| 150 | bool allow_oob, Monitor *cur_mon) |
| 151 | { |
| 152 | Error *err = NULL; |
| 153 | bool oob; |
| 154 | const char *command; |
| 155 | QDict *args; |
| 156 | const QmpCommand *cmd; |
| 157 | QDict *dict; |
| 158 | QObject *id; |
| 159 | QObject *ret = NULL; |
| 160 | QDict *rsp = NULL; |
| 161 | |
| 162 | dict = qobject_to(QDict, request); |
| 163 | if (!dict) { |
| 164 | id = NULL; |
| 165 | error_setg(&err, "QMP input must be a JSON object"); |
| 166 | goto out; |
| 167 | } |
| 168 | |
| 169 | id = qdict_get(dict, "id"); |
| 170 | |
| 171 | if (!qmp_dispatch_check_obj(dict, allow_oob, &err)) { |
| 172 | goto out; |
| 173 | } |
| 174 | |
| 175 | command = qdict_get_try_str(dict, "execute"); |
| 176 | oob = false; |
| 177 | if (!command) { |
| 178 | assert(allow_oob); |
| 179 | command = qdict_get_str(dict, "exec-oob"); |
| 180 | oob = true; |
| 181 | } |
| 182 | cmd = qmp_find_command(cmds, command); |
| 183 | if (cmd == NULL) { |
| 184 | error_set(&err, ERROR_CLASS_COMMAND_NOT_FOUND, |
| 185 | "The command %s has not been found", command); |
| 186 | goto out; |
| 187 | } |
| 188 | if (!compat_policy_input_ok(cmd->features, &compat_policy, |
| 189 | ERROR_CLASS_COMMAND_NOT_FOUND, |
| 190 | "command", command, &err)) { |
| 191 | goto out; |
| 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 | if (qemu_in_coroutine()) { |
| 222 | /* |
| 223 | * Move the coroutine from iohandler_ctx to qemu_aio_context for |
| 224 | * executing the command handler so that it can make progress if it |
| 225 | * involves an AIO_WAIT_WHILE(). |
| 226 | */ |
| 227 | aio_co_schedule(qemu_get_aio_context(), qemu_coroutine_self()); |
| 228 | qemu_coroutine_yield(); |
| 229 | } |
| 230 | |
| 231 | monitor_set_cur(qemu_coroutine_self(), cur_mon); |
| 232 | cmd->fn(args, &ret, &err); |
| 233 | monitor_set_cur(qemu_coroutine_self(), NULL); |
| 234 | |
| 235 | if (qemu_in_coroutine()) { |
| 236 | /* |
| 237 | * Yield and reschedule so the main loop stays responsive. |
| 238 | * |
| 239 | * Move back to iohandler_ctx so that nested event loops for |
| 240 | * qemu_aio_context don't start new monitor commands. |
| 241 | */ |
| 242 | aio_co_schedule(iohandler_get_aio_context(), |
| 243 | qemu_coroutine_self()); |
| 244 | qemu_coroutine_yield(); |
| 245 | } |
| 246 | } else { |
| 247 | /* |
| 248 | * Actual context doesn't match the one the command needs. |
| 249 | * |
| 250 | * Case 1: we are in coroutine context, but command does not |
| 251 | * have QCO_COROUTINE. We need to drop out of coroutine |
| 252 | * context for executing it. |
| 253 | * |
| 254 | * Case 2: we are outside coroutine context, but command has |
| 255 | * QCO_COROUTINE. Can't actually happen, because we get here |
| 256 | * outside coroutine context only when executing a command |
| 257 | * out of band, and OOB commands never have QCO_COROUTINE. |
| 258 | */ |
| 259 | assert(!oob && qemu_in_coroutine() && !(cmd->options & QCO_COROUTINE)); |
| 260 | |
| 261 | QmpDispatchBH data = { |
| 262 | .cur_mon = cur_mon, |
| 263 | .cmd = cmd, |
| 264 | .args = args, |
| 265 | .ret = &ret, |
| 266 | .errp = &err, |
| 267 | .co = qemu_coroutine_self(), |
| 268 | }; |
| 269 | aio_bh_schedule_oneshot(iohandler_get_aio_context(), do_qmp_dispatch_bh, |
| 270 | &data); |
| 271 | qemu_coroutine_yield(); |
| 272 | } |
| 273 | qobject_unref(args); |
| 274 | if (err) { |
| 275 | /* or assert(!ret) after reviewing all handlers: */ |
| 276 | qobject_unref(ret); |
| 277 | goto out; |
| 278 | } |
| 279 | |
| 280 | if (cmd->options & QCO_NO_SUCCESS_RESP) { |
| 281 | g_assert(!ret); |
| 282 | return NULL; |
| 283 | } else if (!ret) { |
| 284 | /* |
| 285 | * When the command's schema has no 'returns', cmd->fn() |
| 286 | * leaves @ret null. The QMP spec calls for an empty object |
| 287 | * then; supply it. |
| 288 | */ |
| 289 | ret = QOBJECT(qdict_new()); |
| 290 | } |
| 291 | |
| 292 | rsp = qdict_new(); |
| 293 | qdict_put_obj(rsp, "return", ret); |
| 294 | |
| 295 | out: |
| 296 | if (err) { |
| 297 | assert(!rsp); |
| 298 | rsp = qmp_error_response(err); |
| 299 | } |
| 300 | |
| 301 | assert(rsp); |
| 302 | |
| 303 | if (id) { |
| 304 | qdict_put_obj(rsp, "id", qobject_ref(id)); |
| 305 | } |
| 306 | |
| 307 | return rsp; |
| 308 | } |