src/libelogind/sd-bus/bus-convenience.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright 2013 Lennart Poettering
   4 ***/
   5
   6 #include "bus-internal.h"
   7 #include "bus-message.h"
   8 #include "bus-signature.h"
   9 #include "bus-type.h"
  10 #include "bus-util.h"
  11 #include "string-util.h"
  12
  13 _public_ int sd_bus_emit_signal(
  14                 sd_bus *bus,
  15                 const char *path,
  16                 const char *interface,
  17                 const char *member,
  18                 const char *types, ...) {
  19
  20         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  21         int r;
  22
  23         assert_return(bus, -EINVAL);
  24         assert_return(bus = bus_resolve(bus), -ENOPKG);
  25         assert_return(!bus_pid_changed(bus), -ECHILD);
  26
  27         if (!BUS_IS_OPEN(bus->state))
  28                 return -ENOTCONN;
  29
  30         r = sd_bus_message_new_signal(bus, &m, path, interface, member);
  31         if (r < 0)
  32                 return r;
  33
  34         if (!isempty(types)) {
  35                 va_list ap;
  36
  37                 va_start(ap, types);
  38                 r = sd_bus_message_appendv(m, types, ap);
  39                 va_end(ap);
  40                 if (r < 0)
  41                         return r;
  42         }
  43
  44         return sd_bus_send(bus, m, NULL);
  45 }
  46
  47 _public_ int sd_bus_call_method_async(
  48                 sd_bus *bus,
  49                 sd_bus_slot **slot,
  50                 const char *destination,
  51                 const char *path,
  52                 const char *interface,
  53                 const char *member,
  54                 sd_bus_message_handler_t callback,
  55                 void *userdata,
  56                 const char *types, ...) {
  57
  58         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  59         int r;
  60
  61         assert_return(bus, -EINVAL);
  62         assert_return(bus = bus_resolve(bus), -ENOPKG);
  63         assert_return(!bus_pid_changed(bus), -ECHILD);
  64
  65         if (!BUS_IS_OPEN(bus->state))
  66                 return -ENOTCONN;
  67
  68         r = sd_bus_message_new_method_call(bus, &m, destination, path, interface, member);
  69         if (r < 0)
  70                 return r;
  71
  72         if (!isempty(types)) {
  73                 va_list ap;
  74
  75                 va_start(ap, types);
  76                 r = sd_bus_message_appendv(m, types, ap);
  77                 va_end(ap);
  78                 if (r < 0)
  79                         return r;
  80         }
  81
  82         return sd_bus_call_async(bus, slot, m, callback, userdata, 0);
  83 }
  84
  85 _public_ int sd_bus_call_method(
  86                 sd_bus *bus,
  87                 const char *destination,
  88                 const char *path,
  89                 const char *interface,
  90                 const char *member,
  91                 sd_bus_error *error,
  92                 sd_bus_message **reply,
  93                 const char *types, ...) {
  94
  95         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  96         int r;
  97
  98         bus_assert_return(bus, -EINVAL, error);
  99         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 100
 101         if (!BUS_IS_OPEN(bus->state)) {
 102                 r = -ENOTCONN;
 103                 goto fail;
 104         }
 105
 106         r = sd_bus_message_new_method_call(bus, &m, destination, path, interface, member);
 107         if (r < 0)
 108                 goto fail;
 109
 110         if (!isempty(types)) {
 111                 va_list ap;
 112
 113                 va_start(ap, types);
 114                 r = sd_bus_message_appendv(m, types, ap);
 115                 va_end(ap);
 116                 if (r < 0)
 117                         goto fail;
 118         }
 119
 120         return sd_bus_call(bus, m, 0, error, reply);
 121
 122 fail:
 123         return sd_bus_error_set_errno(error, r);
 124 }
 125
 126 _public_ int sd_bus_reply_method_return(
 127                 sd_bus_message *call,
 128                 const char *types, ...) {
 129
 130         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
 131         int r;
 132
 133         assert_return(call, -EINVAL);
 134         assert_return(call->sealed, -EPERM);
 135         assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
 136         assert_return(call->bus, -EINVAL);
 137         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 138
 139         if (!BUS_IS_OPEN(call->bus->state))
 140                 return -ENOTCONN;
 141
 142         if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
 143                 return 0;
 144
 145         r = sd_bus_message_new_method_return(call, &m);
 146         if (r < 0)
 147                 return r;
 148
 149         if (!isempty(types)) {
 150                 va_list ap;
 151
 152                 va_start(ap, types);
 153                 r = sd_bus_message_appendv(m, types, ap);
 154                 va_end(ap);
 155                 if (r < 0)
 156                         return r;
 157         }
 158
 159         return sd_bus_send(call->bus, m, NULL);
 160 }
 161
 162 _public_ int sd_bus_reply_method_error(
 163                 sd_bus_message *call,
 164                 const sd_bus_error *e) {
 165
 166         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
 167         int r;
 168
 169         assert_return(call, -EINVAL);
 170         assert_return(call->sealed, -EPERM);
 171         assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
 172         assert_return(sd_bus_error_is_set(e), -EINVAL);
 173         assert_return(call->bus, -EINVAL);
 174         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 175
 176         if (!BUS_IS_OPEN(call->bus->state))
 177                 return -ENOTCONN;
 178
 179         if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
 180                 return 0;
 181
 182         r = sd_bus_message_new_method_error(call, &m, e);
 183         if (r < 0)
 184                 return r;
 185
 186         return sd_bus_send(call->bus, m, NULL);
 187 }
 188
 189 _public_ int sd_bus_reply_method_errorf(
 190                 sd_bus_message *call,
 191                 const char *name,
 192                 const char *format,
 193                 ...) {
 194
 195         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 196         va_list ap;
 197
 198         assert_return(call, -EINVAL);
 199         assert_return(call->sealed, -EPERM);
 200         assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
 201         assert_return(call->bus, -EINVAL);
 202         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 203
 204         if (!BUS_IS_OPEN(call->bus->state))
 205                 return -ENOTCONN;
 206
 207         if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
 208                 return 0;
 209
 210         va_start(ap, format);
 211         bus_error_setfv(&error, name, format, ap);
 212         va_end(ap);
 213
 214         return sd_bus_reply_method_error(call, &error);
 215 }
 216
 217 _public_ int sd_bus_reply_method_errno(
 218                 sd_bus_message *call,
 219                 int error,
 220                 const sd_bus_error *p) {
 221
 222         _cleanup_(sd_bus_error_free) sd_bus_error berror = SD_BUS_ERROR_NULL;
 223
 224         assert_return(call, -EINVAL);
 225         assert_return(call->sealed, -EPERM);
 226         assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
 227         assert_return(call->bus, -EINVAL);
 228         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 229
 230         if (!BUS_IS_OPEN(call->bus->state))
 231                 return -ENOTCONN;
 232
 233         if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
 234                 return 0;
 235
 236         if (sd_bus_error_is_set(p))
 237                 return sd_bus_reply_method_error(call, p);
 238
 239         sd_bus_error_set_errno(&berror, error);
 240
 241         return sd_bus_reply_method_error(call, &berror);
 242 }
 243
 244 _public_ int sd_bus_reply_method_errnof(
 245                 sd_bus_message *call,
 246                 int error,
 247                 const char *format,
 248                 ...) {
 249
 250         _cleanup_(sd_bus_error_free) sd_bus_error berror = SD_BUS_ERROR_NULL;
 251         va_list ap;
 252
 253         assert_return(call, -EINVAL);
 254         assert_return(call->sealed, -EPERM);
 255         assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
 256         assert_return(call->bus, -EINVAL);
 257         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 258
 259         if (!BUS_IS_OPEN(call->bus->state))
 260                 return -ENOTCONN;
 261
 262         if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
 263                 return 0;
 264
 265         va_start(ap, format);
 266         sd_bus_error_set_errnofv(&berror, error, format, ap);
 267         va_end(ap);
 268
 269         return sd_bus_reply_method_error(call, &berror);
 270 }
 271
 272 _public_ int sd_bus_get_property(
 273                 sd_bus *bus,
 274                 const char *destination,
 275                 const char *path,
 276                 const char *interface,
 277                 const char *member,
 278                 sd_bus_error *error,
 279                 sd_bus_message **reply,
 280                 const char *type) {
 281
 282         sd_bus_message *rep = NULL;
 283         int r;
 284
 285         bus_assert_return(bus, -EINVAL, error);
 286         bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
 287         bus_assert_return(member_name_is_valid(member), -EINVAL, error);
 288         bus_assert_return(reply, -EINVAL, error);
 289         bus_assert_return(signature_is_single(type, false), -EINVAL, error);
 290         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 291
 292         if (!BUS_IS_OPEN(bus->state)) {
 293                 r = -ENOTCONN;
 294                 goto fail;
 295         }
 296
 297         r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &rep, "ss", strempty(interface), member);
 298         if (r < 0)
 299                 return r;
 300
 301         r = sd_bus_message_enter_container(rep, 'v', type);
 302         if (r < 0) {
 303                 sd_bus_message_unref(rep);
 304                 goto fail;
 305         }
 306
 307         *reply = rep;
 308         return 0;
 309
 310 fail:
 311         return sd_bus_error_set_errno(error, r);
 312 }
 313
 314 _public_ int sd_bus_get_property_trivial(
 315                 sd_bus *bus,
 316                 const char *destination,
 317                 const char *path,
 318                 const char *interface,
 319                 const char *member,
 320                 sd_bus_error *error,
 321                 char type, void *ptr) {
 322
 323         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
 324         int r;
 325
 326         bus_assert_return(bus, -EINVAL, error);
 327         bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
 328         bus_assert_return(member_name_is_valid(member), -EINVAL, error);
 329         bus_assert_return(bus_type_is_trivial(type), -EINVAL, error);
 330         bus_assert_return(ptr, -EINVAL, error);
 331         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 332
 333         if (!BUS_IS_OPEN(bus->state)) {
 334                 r = -ENOTCONN;
 335                 goto fail;
 336         }
 337
 338         r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &reply, "ss", strempty(interface), member);
 339         if (r < 0)
 340                 return r;
 341
 342         r = sd_bus_message_enter_container(reply, 'v', CHAR_TO_STR(type));
 343         if (r < 0)
 344                 goto fail;
 345
 346         r = sd_bus_message_read_basic(reply, type, ptr);
 347         if (r < 0)
 348                 goto fail;
 349
 350         return 0;
 351
 352 fail:
 353         return sd_bus_error_set_errno(error, r);
 354 }
 355
 356 _public_ int sd_bus_get_property_string(
 357                 sd_bus *bus,
 358                 const char *destination,
 359                 const char *path,
 360                 const char *interface,
 361                 const char *member,
 362                 sd_bus_error *error,
 363                 char **ret) {
 364
 365         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
 366         const char *s;
 367         char *n;
 368         int r;
 369
 370         bus_assert_return(bus, -EINVAL, error);
 371         bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
 372         bus_assert_return(member_name_is_valid(member), -EINVAL, error);
 373         bus_assert_return(ret, -EINVAL, error);
 374         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 375
 376         if (!BUS_IS_OPEN(bus->state)) {
 377                 r = -ENOTCONN;
 378                 goto fail;
 379         }
 380
 381         r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &reply, "ss", strempty(interface), member);
 382         if (r < 0)
 383                 return r;
 384
 385         r = sd_bus_message_enter_container(reply, 'v', "s");
 386         if (r < 0)
 387                 goto fail;
 388
 389         r = sd_bus_message_read_basic(reply, 's', &s);
 390         if (r < 0)
 391                 goto fail;
 392
 393         n = strdup(s);
 394         if (!n) {
 395                 r = -ENOMEM;
 396                 goto fail;
 397         }
 398
 399         *ret = n;
 400         return 0;
 401
 402 fail:
 403         return sd_bus_error_set_errno(error, r);
 404 }
 405
 406 _public_ int sd_bus_get_property_strv(
 407                 sd_bus *bus,
 408                 const char *destination,
 409                 const char *path,
 410                 const char *interface,
 411                 const char *member,
 412                 sd_bus_error *error,
 413                 char ***ret) {
 414
 415         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
 416         int r;
 417
 418         bus_assert_return(bus, -EINVAL, error);
 419         bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
 420         bus_assert_return(member_name_is_valid(member), -EINVAL, error);
 421         bus_assert_return(ret, -EINVAL, error);
 422         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 423
 424         if (!BUS_IS_OPEN(bus->state)) {
 425                 r = -ENOTCONN;
 426                 goto fail;
 427         }
 428
 429         r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &reply, "ss", strempty(interface), member);
 430         if (r < 0)
 431                 return r;
 432
 433         r = sd_bus_message_enter_container(reply, 'v', NULL);
 434         if (r < 0)
 435                 goto fail;
 436
 437         r = sd_bus_message_read_strv(reply, ret);
 438         if (r < 0)
 439                 goto fail;
 440
 441         return 0;
 442
 443 fail:
 444         return sd_bus_error_set_errno(error, r);
 445 }
 446
 447 _public_ int sd_bus_set_property(
 448                 sd_bus *bus,
 449                 const char *destination,
 450                 const char *path,
 451                 const char *interface,
 452                 const char *member,
 453                 sd_bus_error *error,
 454                 const char *type, ...) {
 455
 456         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
 457         va_list ap;
 458         int r;
 459
 460         bus_assert_return(bus, -EINVAL, error);
 461         bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
 462         bus_assert_return(member_name_is_valid(member), -EINVAL, error);
 463         bus_assert_return(signature_is_single(type, false), -EINVAL, error);
 464         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 465
 466         if (!BUS_IS_OPEN(bus->state)) {
 467                 r = -ENOTCONN;
 468                 goto fail;
 469         }
 470
 471         r = sd_bus_message_new_method_call(bus, &m, destination, path, "org.freedesktop.DBus.Properties", "Set");
 472         if (r < 0)
 473                 goto fail;
 474
 475         r = sd_bus_message_append(m, "ss", strempty(interface), member);
 476         if (r < 0)
 477                 goto fail;
 478
 479         r = sd_bus_message_open_container(m, 'v', type);
 480         if (r < 0)
 481                 goto fail;
 482
 483         va_start(ap, type);
 484         r = sd_bus_message_appendv(m, type, ap);
 485         va_end(ap);
 486         if (r < 0)
 487                 goto fail;
 488
 489         r = sd_bus_message_close_container(m);
 490         if (r < 0)
 491                 goto fail;
 492
 493         return sd_bus_call(bus, m, 0, error, NULL);
 494
 495 fail:
 496         return sd_bus_error_set_errno(error, r);
 497 }
 498
 499 _public_ int sd_bus_query_sender_creds(sd_bus_message *call, uint64_t mask, sd_bus_creds **creds) {
 500         sd_bus_creds *c;
 501
 502         assert_return(call, -EINVAL);
 503         assert_return(call->sealed, -EPERM);
 504         assert_return(call->bus, -EINVAL);
 505         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 506
 507         if (!BUS_IS_OPEN(call->bus->state))
 508                 return -ENOTCONN;
 509
 510         c = sd_bus_message_get_creds(call);
 511
 512         /* All data we need? */
 513         if (c && (mask & ~c->mask) == 0) {
 514                 *creds = sd_bus_creds_ref(c);
 515                 return 0;
 516         }
 517
 518         /* No data passed? Or not enough data passed to retrieve the missing bits? */
 519         if (!c || !(c->mask & SD_BUS_CREDS_PID)) {
 520                 /* We couldn't read anything from the call, let's try
 521                  * to get it from the sender or peer. */
 522
 523                 if (call->sender)
 524                         /* There's a sender, but the creds are missing. */
 525                         return sd_bus_get_name_creds(call->bus, call->sender, mask, creds);
 526                 else
 527                         /* There's no sender. For direct connections
 528                          * the credentials of the AF_UNIX peer matter,
 529                          * which may be queried via sd_bus_get_owner_creds(). */
 530                         return sd_bus_get_owner_creds(call->bus, mask, creds);
 531         }
 532
 533         return bus_creds_extend_by_pid(c, mask, creds);
 534 }
 535
 536 _public_ int sd_bus_query_sender_privilege(sd_bus_message *call, int capability) {
 537         _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
 538         uid_t our_uid;
 539         bool know_caps = false;
 540         int r;
 541
 542         assert_return(call, -EINVAL);
 543         assert_return(call->sealed, -EPERM);
 544         assert_return(call->bus, -EINVAL);
 545         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 546
 547         if (!BUS_IS_OPEN(call->bus->state))
 548                 return -ENOTCONN;
 549
 550         if (capability >= 0) {
 551
 552                 r = sd_bus_query_sender_creds(call, SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID|SD_BUS_CREDS_EFFECTIVE_CAPS, &creds);
 553                 if (r < 0)
 554                         return r;
 555
 556                 /* We cannot use augmented caps for authorization,
 557                  * since then data is acquired raceful from
 558                  * /proc. This can never actually happen, but let's
 559                  * better be safe than sorry, and do an extra check
 560                  * here. */
 561                 assert_return((sd_bus_creds_get_augmented_mask(creds) & SD_BUS_CREDS_EFFECTIVE_CAPS) == 0, -EPERM);
 562
 563                 r = sd_bus_creds_has_effective_cap(creds, capability);
 564                 if (r > 0)
 565                         return 1;
 566                 if (r == 0)
 567                         know_caps = true;
 568         } else {
 569                 r = sd_bus_query_sender_creds(call, SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID, &creds);
 570                 if (r < 0)
 571                         return r;
 572         }
 573
 574         /* Now, check the UID, but only if the capability check wasn't
 575          * sufficient */
 576         our_uid = getuid();
 577         if (our_uid != 0 || !know_caps || capability < 0) {
 578                 uid_t sender_uid;
 579
 580                 /* We cannot use augmented uid/euid for authorization,
 581                  * since then data is acquired raceful from
 582                  * /proc. This can never actually happen, but let's
 583                  * better be safe than sorry, and do an extra check
 584                  * here. */
 585                 assert_return((sd_bus_creds_get_augmented_mask(creds) & (SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID)) == 0, -EPERM);
 586
 587                 /* Try to use the EUID, if we have it. */
 588                 r = sd_bus_creds_get_euid(creds, &sender_uid);
 589                 if (r < 0)
 590                         r = sd_bus_creds_get_uid(creds, &sender_uid);
 591
 592                 if (r >= 0) {
 593                         /* Sender has same UID as us, then let's grant access */
 594                         if (sender_uid == our_uid)
 595                                 return 1;
 596
 597                         /* Sender is root, we are not root. */
 598                         if (our_uid != 0 && sender_uid == 0)
 599                                 return 1;
 600                 }
 601         }
 602
 603         return 0;
 604 }
 605
 606 #define make_expression(sender, path, interface, member)        \
 607         strjoina(                                               \
 608                 "type='signal'",                                \
 609                 sender ? ",sender='" : "",                      \
 610                 sender ?: "",                                   \
 611                 sender ? "'" : "",                              \
 612                 path ? ",path='" : "",                          \
 613                 path ?: "",                                     \
 614                 path ? "'" : "",                                \
 615                 interface ? ",interface='" : "",                \
 616                 interface ?: "",                                \
 617                 interface ? "'" : "",                           \
 618                 member ? ",member='" : "",                      \
 619                 member ?: "",                                   \
 620                 member ? "'" : ""                               \
 621         )
 622
 623 _public_ int sd_bus_match_signal(
 624                 sd_bus *bus,
 625                 sd_bus_slot **ret,
 626                 const char *sender,
 627                 const char *path,
 628                 const char *interface,
 629                 const char *member,
 630                 sd_bus_message_handler_t callback,
 631                 void *userdata) {
 632
 633         const char *expression;
 634
 635         assert_return(bus, -EINVAL);
 636         assert_return(bus = bus_resolve(bus), -ENOPKG);
 637         assert_return(!bus_pid_changed(bus), -ECHILD);
 638         assert_return(!sender || service_name_is_valid(sender), -EINVAL);
 639         assert_return(!path || object_path_is_valid(path), -EINVAL);
 640         assert_return(!interface || interface_name_is_valid(interface), -EINVAL);
 641         assert_return(!member || member_name_is_valid(member), -EINVAL);
 642
 643         expression = make_expression(sender, path, interface, member);
 644
 645         return sd_bus_add_match(bus, ret, expression, callback, userdata);
 646 }
 647
 648 _public_ int sd_bus_match_signal_async(
 649                 sd_bus *bus,
 650                 sd_bus_slot **ret,
 651                 const char *sender,
 652                 const char *path,
 653                 const char *interface,
 654                 const char *member,
 655                 sd_bus_message_handler_t callback,
 656                 sd_bus_message_handler_t install_callback,
 657                 void *userdata) {
 658
 659         const char *expression;
 660
 661         assert_return(bus, -EINVAL);
 662         assert_return(bus = bus_resolve(bus), -ENOPKG);
 663         assert_return(!bus_pid_changed(bus), -ECHILD);
 664         assert_return(!sender || service_name_is_valid(sender), -EINVAL);
 665         assert_return(!path || object_path_is_valid(path), -EINVAL);
 666         assert_return(!interface || interface_name_is_valid(interface), -EINVAL);
 667         assert_return(!member || member_name_is_valid(member), -EINVAL);
 668
 669         expression = make_expression(sender, path, interface, member);
 670
 671         return sd_bus_add_match_async(bus, ret, expression, callback, install_callback, userdata);
 672 }