lib/async_req/async_sock.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    async socket syscalls
   4    Copyright (C) Volker Lendecke 2008
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "includes.h"
  21 #include "lib/talloc/talloc.h"
  22 #include "lib/tevent/tevent.h"
  23 #include "lib/async_req/async_req.h"
  24 #include "lib/async_req/async_sock.h"
  25 #include "lib/util/tevent_unix.h"
  26 #include <fcntl.h>
  27
  28 #ifndef TALLOC_FREE
  29 #define TALLOC_FREE(ctx) do { talloc_free(ctx); ctx=NULL; } while(0)
  30 #endif
  31
  32 /**
  33  * Discriminator for async_syscall_state
  34  */
  35 enum async_syscall_type {
  36         ASYNC_SYSCALL_SEND,
  37         ASYNC_SYSCALL_RECV,
  38         ASYNC_SYSCALL_RECVALL,
  39         ASYNC_SYSCALL_CONNECT
  40 };
  41
  42 /**
  43  * Holder for syscall arguments and the result
  44  */
  45
  46 struct async_syscall_state {
  47         enum async_syscall_type syscall_type;
  48         struct tevent_fd *fde;
  49
  50         union {
  51                 struct param_send {
  52                         int fd;
  53                         const void *buffer;
  54                         size_t length;
  55                         int flags;
  56                 } param_send;
  57                 struct param_recv {
  58                         int fd;
  59                         void *buffer;
  60                         size_t length;
  61                         int flags;
  62                 } param_recv;
  63                 struct param_recvall {
  64                         int fd;
  65                         void *buffer;
  66                         size_t length;
  67                         int flags;
  68                         size_t received;
  69                 } param_recvall;
  70                 struct param_connect {
  71                         /**
  72                          * connect needs to be done on a nonblocking
  73                          * socket. Keep the old flags around
  74                          */
  75                         long old_sockflags;
  76                         int fd;
  77                         const struct sockaddr *address;
  78                         socklen_t address_len;
  79                 } param_connect;
  80         } param;
  81
  82         union {
  83                 ssize_t result_ssize_t;
  84                 size_t result_size_t;
  85                 int result_int;
  86         } result;
  87         int sys_errno;
  88 };
  89
  90 /**
  91  * @brief Map async_req states to unix-style errnos
  92  * @param[in]  req      The async req to get the state from
  93  * @param[out] err      Pointer to take the unix-style errno
  94  *
  95  * @return true if the async_req is in an error state, false otherwise
  96  */
  97
  98 bool async_req_is_errno(struct async_req *req, int *err)
  99 {
 100         enum async_req_state state;
 101         uint64_t error;
 102
 103         if (!async_req_is_error(req, &state, &error)) {
 104                 return false;
 105         }
 106
 107         switch (state) {
 108         case ASYNC_REQ_USER_ERROR:
 109                 *err = (int)error;
 110                 break;
 111         case ASYNC_REQ_TIMED_OUT:
 112 #ifdef ETIMEDOUT
 113                 *err = ETIMEDOUT;
 114 #else
 115                 *err = EAGAIN;
 116 #endif
 117                 break;
 118         case ASYNC_REQ_NO_MEMORY:
 119                 *err = ENOMEM;
 120                 break;
 121         default:
 122                 *err = EIO;
 123                 break;
 124         }
 125         return true;
 126 }
 127
 128 int async_req_simple_recv_errno(struct async_req *req)
 129 {
 130         int err;
 131
 132         if (async_req_is_errno(req, &err)) {
 133                 return err;
 134         }
 135
 136         return 0;
 137 }
 138
 139 /**
 140  * @brief Create a new async syscall req
 141  * @param[in] mem_ctx   The memory context to hang the result off
 142  * @param[in] ev        The event context to work from
 143  * @param[in] type      Which syscall will this be
 144  * @param[in] pstate    Where to put the newly created private_data state
 145  * @retval The new request
 146  *
 147  * This is a helper function to prepare a new struct async_req with an
 148  * associated struct async_syscall_state. The async_syscall_state will be put
 149  * into the async_req as private_data.
 150  */
 151
 152 static struct async_req *async_syscall_new(TALLOC_CTX *mem_ctx,
 153                                            struct tevent_context *ev,
 154                                            enum async_syscall_type type,
 155                                            struct async_syscall_state **pstate)
 156 {
 157         struct async_req *result;
 158         struct async_syscall_state *state;
 159
 160         if (!async_req_setup(mem_ctx, &result, &state,
 161                              struct async_syscall_state)) {
 162                 return NULL;
 163         }
 164         state->syscall_type = type;
 165
 166         result->private_data = state;
 167
 168         *pstate = state;
 169
 170         return result;
 171 }
 172
 173 /**
 174  * @brief Create a new async syscall req based on a fd
 175  * @param[in] mem_ctx   The memory context to hang the result off
 176  * @param[in] ev        The event context to work from
 177  * @param[in] type      Which syscall will this be
 178  * @param[in] fd        The file descriptor we work on
 179  * @param[in] fde_flags TEVENT_FD_READ/WRITE -- what are we interested in?
 180  * @param[in] fde_cb    The callback function for the file descriptor event
 181  * @param[in] pstate    Where to put the newly created private_data state
 182  * @retval The new request
 183  *
 184  * This is a helper function to prepare a new struct async_req with an
 185  * associated struct async_syscall_state and an associated file descriptor
 186  * event.
 187  */
 188
 189 static struct async_req *async_fde_syscall_new(
 190         TALLOC_CTX *mem_ctx,
 191         struct tevent_context *ev,
 192         enum async_syscall_type type,
 193         int fd,
 194         uint16_t fde_flags,
 195         void (*fde_cb)(struct tevent_context *ev,
 196                        struct tevent_fd *fde, uint16_t flags,
 197                        void *priv),
 198         struct async_syscall_state **pstate)
 199 {
 200         struct async_req *result;
 201         struct async_syscall_state *state;
 202
 203         result = async_syscall_new(mem_ctx, ev, type, &state);
 204         if (result == NULL) {
 205                 return NULL;
 206         }
 207
 208         state->fde = tevent_add_fd(ev, state, fd, fde_flags, fde_cb, result);
 209         if (state->fde == NULL) {
 210                 TALLOC_FREE(result);
 211                 return NULL;
 212         }
 213         *pstate = state;
 214         return result;
 215 }
 216
 217 /**
 218  * Retrieve a ssize_t typed result from an async syscall
 219  * @param[in] req       The syscall that has just finished
 220  * @param[out] perrno   Where to put the syscall's errno
 221  * @retval The return value from the asynchronously called syscall
 222  */
 223
 224 ssize_t async_syscall_result_ssize_t(struct async_req *req, int *perrno)
 225 {
 226         struct async_syscall_state *state = talloc_get_type_abort(
 227                 req->private_data, struct async_syscall_state);
 228
 229         *perrno = state->sys_errno;
 230         return state->result.result_ssize_t;
 231 }
 232
 233 /**
 234  * Retrieve a size_t typed result from an async syscall
 235  * @param[in] req       The syscall that has just finished
 236  * @param[out] perrno   Where to put the syscall's errno
 237  * @retval The return value from the asynchronously called syscall
 238  */
 239
 240 size_t async_syscall_result_size_t(struct async_req *req, int *perrno)
 241 {
 242         struct async_syscall_state *state = talloc_get_type_abort(
 243                 req->private_data, struct async_syscall_state);
 244
 245         *perrno = state->sys_errno;
 246         return state->result.result_size_t;
 247 }
 248
 249 /**
 250  * Retrieve a int typed result from an async syscall
 251  * @param[in] req       The syscall that has just finished
 252  * @param[out] perrno   Where to put the syscall's errno
 253  * @retval The return value from the asynchronously called syscall
 254  */
 255
 256 int async_syscall_result_int(struct async_req *req, int *perrno)
 257 {
 258         struct async_syscall_state *state = talloc_get_type_abort(
 259                 req->private_data, struct async_syscall_state);
 260
 261         *perrno = state->sys_errno;
 262         return state->result.result_int;
 263 }
 264
 265 /**
 266  * fde event handler for the "send" syscall
 267  * @param[in] ev        The event context that sent us here
 268  * @param[in] fde       The file descriptor event associated with the send
 269  * @param[in] flags     Can only be TEVENT_FD_WRITE here
 270  * @param[in] priv      private data, "struct async_req *" in this case
 271  */
 272
 273 static void async_send_callback(struct tevent_context *ev,
 274                                 struct tevent_fd *fde, uint16_t flags,
 275                                 void *priv)
 276 {
 277         struct async_req *req = talloc_get_type_abort(
 278                 priv, struct async_req);
 279         struct async_syscall_state *state = talloc_get_type_abort(
 280                 req->private_data, struct async_syscall_state);
 281         struct param_send *p = &state->param.param_send;
 282
 283         if (state->syscall_type != ASYNC_SYSCALL_SEND) {
 284                 async_req_error(req, EIO);
 285                 return;
 286         }
 287
 288         state->result.result_ssize_t = send(p->fd, p->buffer, p->length,
 289                                             p->flags);
 290         state->sys_errno = errno;
 291
 292         TALLOC_FREE(state->fde);
 293
 294         async_req_done(req);
 295 }
 296
 297 /**
 298  * Async version of send(2)
 299  * @param[in] mem_ctx   The memory context to hang the result off
 300  * @param[in] ev        The event context to work from
 301  * @param[in] fd        The socket to send to
 302  * @param[in] buffer    The buffer to send
 303  * @param[in] length    How many bytes to send
 304  * @param[in] flags     flags passed to send(2)
 305  *
 306  * This function is a direct counterpart of send(2)
 307  */
 308
 309 struct async_req *async_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 310                              int fd, const void *buffer, size_t length,
 311                              int flags)
 312 {
 313         struct async_req *result;
 314         struct async_syscall_state *state;
 315
 316         result = async_fde_syscall_new(
 317                 mem_ctx, ev, ASYNC_SYSCALL_SEND,
 318                 fd, TEVENT_FD_WRITE, async_send_callback,
 319                 &state);
 320         if (result == NULL) {
 321                 return NULL;
 322         }
 323
 324         state->param.param_send.fd = fd;
 325         state->param.param_send.buffer = buffer;
 326         state->param.param_send.length = length;
 327         state->param.param_send.flags = flags;
 328
 329         return result;
 330 }
 331
 332 /**
 333  * fde event handler for the "recv" syscall
 334  * @param[in] ev        The event context that sent us here
 335  * @param[in] fde       The file descriptor event associated with the recv
 336  * @param[in] flags     Can only be TEVENT_FD_READ here
 337  * @param[in] priv      private data, "struct async_req *" in this case
 338  */
 339
 340 static void async_recv_callback(struct tevent_context *ev,
 341                                 struct tevent_fd *fde, uint16_t flags,
 342                                 void *priv)
 343 {
 344         struct async_req *req = talloc_get_type_abort(
 345                 priv, struct async_req);
 346         struct async_syscall_state *state = talloc_get_type_abort(
 347                 req->private_data, struct async_syscall_state);
 348         struct param_recv *p = &state->param.param_recv;
 349
 350         if (state->syscall_type != ASYNC_SYSCALL_RECV) {
 351                 async_req_error(req, EIO);
 352                 return;
 353         }
 354
 355         state->result.result_ssize_t = recv(p->fd, p->buffer, p->length,
 356                                             p->flags);
 357         state->sys_errno = errno;
 358
 359         TALLOC_FREE(state->fde);
 360
 361         async_req_done(req);
 362 }
 363
 364 /**
 365  * Async version of recv(2)
 366  * @param[in] mem_ctx   The memory context to hang the result off
 367  * @param[in] ev        The event context to work from
 368  * @param[in] fd        The socket to recv from
 369  * @param[in] buffer    The buffer to recv into
 370  * @param[in] length    How many bytes to recv
 371  * @param[in] flags     flags passed to recv(2)
 372  *
 373  * This function is a direct counterpart of recv(2)
 374  */
 375
 376 struct async_req *async_recv(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 377                              int fd, void *buffer, size_t length,
 378                              int flags)
 379 {
 380         struct async_req *result;
 381         struct async_syscall_state *state;
 382
 383         result = async_fde_syscall_new(
 384                 mem_ctx, ev, ASYNC_SYSCALL_RECV,
 385                 fd, TEVENT_FD_READ, async_recv_callback,
 386                 &state);
 387
 388         if (result == NULL) {
 389                 return NULL;
 390         }
 391
 392         state->param.param_recv.fd = fd;
 393         state->param.param_recv.buffer = buffer;
 394         state->param.param_recv.length = length;
 395         state->param.param_recv.flags = flags;
 396
 397         return result;
 398 }
 399
 400 /**
 401  * fde event handler for the "recvall" syscall group
 402  * @param[in] ev        The event context that sent us here
 403  * @param[in] fde       The file descriptor event associated with the recv
 404  * @param[in] flags     Can only be TEVENT_FD_READ here
 405  * @param[in] priv      private data, "struct async_req *" in this case
 406  */
 407
 408 static void async_recvall_callback(struct tevent_context *ev,
 409                                    struct tevent_fd *fde, uint16_t flags,
 410                                    void *priv)
 411 {
 412         struct async_req *req = talloc_get_type_abort(
 413                 priv, struct async_req);
 414         struct async_syscall_state *state = talloc_get_type_abort(
 415                 req->private_data, struct async_syscall_state);
 416         struct param_recvall *p = &state->param.param_recvall;
 417
 418         if (state->syscall_type != ASYNC_SYSCALL_RECVALL) {
 419                 async_req_error(req, EIO);
 420                 return;
 421         }
 422
 423         state->result.result_ssize_t = recv(p->fd,
 424                                             (char *)p->buffer + p->received,
 425                                             p->length - p->received, p->flags);
 426         state->sys_errno = errno;
 427
 428         if (state->result.result_ssize_t == -1) {
 429                 async_req_error(req, state->sys_errno);
 430                 return;
 431         }
 432
 433         if (state->result.result_ssize_t == 0) {
 434                 async_req_error(req, EIO);
 435                 return;
 436         }
 437
 438         p->received += state->result.result_ssize_t;
 439         if (p->received > p->length) {
 440                 async_req_error(req, EIO);
 441                 return;
 442         }
 443
 444         if (p->received == p->length) {
 445                 TALLOC_FREE(state->fde);
 446                 async_req_done(req);
 447         }
 448 }
 449
 450 /**
 451  * Receive a specified number of bytes from a socket
 452  * @param[in] mem_ctx   The memory context to hang the result off
 453  * @param[in] ev        The event context to work from
 454  * @param[in] fd        The socket to recv from
 455  * @param[in] buffer    The buffer to recv into
 456  * @param[in] length    How many bytes to recv
 457  * @param[in] flags     flags passed to recv(2)
 458  *
 459  * async_recvall will call recv(2) until "length" bytes are received
 460  */
 461
 462 struct async_req *recvall_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 463                                int fd, void *buffer, size_t length,
 464                                int flags)
 465 {
 466         struct async_req *result;
 467         struct async_syscall_state *state;
 468
 469         result = async_fde_syscall_new(
 470                 mem_ctx, ev, ASYNC_SYSCALL_RECVALL,
 471                 fd, TEVENT_FD_READ, async_recvall_callback,
 472                 &state);
 473         if (result == NULL) {
 474                 return NULL;
 475         }
 476
 477         state->param.param_recvall.fd = fd;
 478         state->param.param_recvall.buffer = buffer;
 479         state->param.param_recvall.length = length;
 480         state->param.param_recvall.flags = flags;
 481         state->param.param_recvall.received = 0;
 482
 483         return result;
 484 }
 485
 486 ssize_t recvall_recv(struct async_req *req, int *perr)
 487 {
 488         struct async_syscall_state *state = talloc_get_type_abort(
 489                 req->private_data, struct async_syscall_state);
 490         int err;
 491
 492         err = async_req_simple_recv_errno(req);
 493
 494         if (err != 0) {
 495                 *perr = err;
 496                 return -1;
 497         }
 498
 499         return state->result.result_ssize_t;
 500 }
 501
 502 struct async_connect_state {
 503         int fd;
 504         int result;
 505         int sys_errno;
 506         long old_sockflags;
 507 };
 508
 509 static void async_connect_connected(struct tevent_context *ev,
 510                                     struct tevent_fd *fde, uint16_t flags,
 511                                     void *priv);
 512
 513 /**
 514  * @brief async version of connect(2)
 515  * @param[in] mem_ctx   The memory context to hang the result off
 516  * @param[in] ev        The event context to work from
 517  * @param[in] fd        The socket to recv from
 518  * @param[in] address   Where to connect?
 519  * @param[in] address_len Length of *address
 520  * @retval The async request
 521  *
 522  * This function sets the socket into non-blocking state to be able to call
 523  * connect in an async state. This will be reset when the request is finished.
 524  */
 525
 526 struct tevent_req *async_connect_send(TALLOC_CTX *mem_ctx,
 527                                       struct tevent_context *ev,
 528                                       int fd, const struct sockaddr *address,
 529                                       socklen_t address_len)
 530 {
 531         struct tevent_req *result;
 532         struct async_connect_state *state;
 533         struct tevent_fd *fde;
 534
 535         result = tevent_req_create(
 536                 mem_ctx, &state, struct async_connect_state);
 537         if (result == NULL) {
 538                 return NULL;
 539         }
 540
 541         /**
 542          * We have to set the socket to nonblocking for async connect(2). Keep
 543          * the old sockflags around.
 544          */
 545
 546         state->fd = fd;
 547         state->sys_errno = 0;
 548
 549         state->old_sockflags = fcntl(fd, F_GETFL, 0);
 550         if (state->old_sockflags == -1) {
 551                 goto post_errno;
 552         }
 553
 554         set_blocking(fd, false);
 555
 556         state->result = connect(fd, address, address_len);
 557         if (state->result == 0) {
 558                 errno = 0;
 559                 goto post_errno;
 560         }
 561
 562         /**
 563          * A number of error messages show that something good is progressing
 564          * and that we have to wait for readability.
 565          *
 566          * If none of them are present, bail out.
 567          */
 568
 569         if (!(errno == EINPROGRESS || errno == EALREADY ||
 570 #ifdef EISCONN
 571               errno == EISCONN ||
 572 #endif
 573               errno == EAGAIN || errno == EINTR)) {
 574                 goto post_errno;
 575         }
 576
 577         fde = tevent_add_fd(ev, state, fd, TEVENT_FD_READ | TEVENT_FD_WRITE,
 578                            async_connect_connected, result);
 579         if (fde == NULL) {
 580                 errno = ENOMEM;
 581                 goto post_errno;
 582         }
 583         return result;
 584
 585  post_errno:
 586         state->sys_errno = errno;
 587         fcntl(fd, F_SETFL, state->old_sockflags);
 588         if (state->sys_errno == 0) {
 589                 tevent_req_done(result);
 590         } else {
 591                 tevent_req_error(result, state->sys_errno);
 592         }
 593         return tevent_req_post(result, ev);
 594 }
 595
 596 /**
 597  * fde event handler for connect(2)
 598  * @param[in] ev        The event context that sent us here
 599  * @param[in] fde       The file descriptor event associated with the connect
 600  * @param[in] flags     Indicate read/writeability of the socket
 601  * @param[in] priv      private data, "struct async_req *" in this case
 602  */
 603
 604 static void async_connect_connected(struct tevent_context *ev,
 605                                     struct tevent_fd *fde, uint16_t flags,
 606                                     void *priv)
 607 {
 608         struct tevent_req *req = talloc_get_type_abort(
 609                 priv, struct tevent_req);
 610         struct async_connect_state *state = talloc_get_type_abort(
 611                 req->private_state, struct async_connect_state);
 612
 613         TALLOC_FREE(fde);
 614
 615         /*
 616          * Stevens, Network Programming says that if there's a
 617          * successful connect, the socket is only writable. Upon an
 618          * error, it's both readable and writable.
 619          */
 620         if ((flags & (TEVENT_FD_READ|TEVENT_FD_WRITE))
 621             == (TEVENT_FD_READ|TEVENT_FD_WRITE)) {
 622                 int sockerr;
 623                 socklen_t err_len = sizeof(sockerr);
 624
 625                 if (getsockopt(state->fd, SOL_SOCKET, SO_ERROR,
 626                                (void *)&sockerr, &err_len) == 0) {
 627                         errno = sockerr;
 628                 }
 629
 630                 state->sys_errno = errno;
 631
 632                 DEBUG(10, ("connect returned %s\n", strerror(errno)));
 633
 634                 fcntl(state->fd, F_SETFL, state->old_sockflags);
 635                 tevent_req_error(req, state->sys_errno);
 636                 return;
 637         }
 638
 639         state->sys_errno = 0;
 640         tevent_req_done(req);
 641 }
 642
 643 int async_connect_recv(struct tevent_req *req, int *perrno)
 644 {
 645         struct async_connect_state *state = talloc_get_type_abort(
 646                 req->private_state, struct async_connect_state);
 647         int err;
 648
 649         fcntl(state->fd, F_SETFL, state->old_sockflags);
 650
 651         if (tevent_req_is_unix_error(req, &err)) {
 652                 *perrno = err;
 653                 return -1;
 654         }
 655
 656         if (state->sys_errno == 0) {
 657                 return 0;
 658         }
 659
 660         *perrno = state->sys_errno;
 661         return -1;
 662 }
 663
 664 struct writev_state {
 665         struct tevent_context *ev;
 666         int fd;
 667         struct iovec *iov;
 668         int count;
 669         size_t total_size;
 670 };
 671
 672 static void writev_handler(struct tevent_context *ev, struct tevent_fd *fde,
 673                            uint16_t flags, void *private_data);
 674
 675 struct tevent_req *writev_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 676                                int fd, struct iovec *iov, int count)
 677 {
 678         struct tevent_req *result;
 679         struct writev_state *state;
 680         struct tevent_fd *fde;
 681
 682         result = tevent_req_create(mem_ctx, &state, struct writev_state);
 683         if (result == NULL) {
 684                 return NULL;
 685         }
 686         state->ev = ev;
 687         state->fd = fd;
 688         state->total_size = 0;
 689         state->count = count;
 690         state->iov = (struct iovec *)talloc_memdup(
 691                 state, iov, sizeof(struct iovec) * count);
 692         if (state->iov == NULL) {
 693                 goto fail;
 694         }
 695
 696         fde = tevent_add_fd(ev, state, fd, TEVENT_FD_WRITE, writev_handler,
 697                             result);
 698         if (fde == NULL) {
 699                 goto fail;
 700         }
 701         return result;
 702
 703  fail:
 704         TALLOC_FREE(result);
 705         return NULL;
 706 }
 707
 708 static void writev_handler(struct tevent_context *ev, struct tevent_fd *fde,
 709                            uint16_t flags, void *private_data)
 710 {
 711         struct tevent_req *req = talloc_get_type_abort(
 712                 private_data, struct tevent_req);
 713         struct writev_state *state = talloc_get_type_abort(
 714                 req->private_state, struct writev_state);
 715         size_t to_write, written;
 716         int i;
 717
 718         to_write = 0;
 719
 720         for (i=0; i<state->count; i++) {
 721                 to_write += state->iov[i].iov_len;
 722         }
 723
 724         written = sys_writev(state->fd, state->iov, state->count);
 725         if (written == -1) {
 726                 tevent_req_error(req, errno);
 727                 return;
 728         }
 729         if (written == 0) {
 730                 tevent_req_error(req, EOF);
 731                 return;
 732         }
 733         state->total_size += written;
 734
 735         if (written == to_write) {
 736                 tevent_req_done(req);
 737                 return;
 738         }
 739
 740         /*
 741          * We've written less than we were asked to, drop stuff from
 742          * state->iov.
 743          */
 744
 745         while (written > 0) {
 746                 if (written < state->iov[0].iov_len) {
 747                         state->iov[0].iov_base =
 748                                 (char *)state->iov[0].iov_base + written;
 749                         state->iov[0].iov_len -= written;
 750                         break;
 751                 }
 752                 written = state->iov[0].iov_len;
 753                 state->iov += 1;
 754                 state->count -= 1;
 755         }
 756 }
 757
 758 ssize_t writev_recv(struct tevent_req *req, int *perrno)
 759 {
 760         struct writev_state *state = talloc_get_type_abort(
 761                 req->private_state, struct writev_state);
 762
 763         if (tevent_req_is_unix_error(req, perrno)) {
 764                 return -1;
 765         }
 766         return state->total_size;
 767 }