io.c

   1 /* -*- c-file-style: "linux" -*-
   2  *
   3  * Copyright (C) 1996-2001 by Andrew Tridgell
   4  * Copyright (C) Paul Mackerras 1996
   5  * Copyright (C) 2001, 2002 by Martin Pool <mbp@samba.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 /**
  23  * @file io.c
  24  *
  25  * Socket and pipe I/O utilities used in rsync.
  26  *
  27  * rsync provides its own multiplexing system, which is used to send
  28  * stderr and stdout over a single socket.  We need this because
  29  * stdout normally carries the binary data stream, and stderr all our
  30  * error messages.
  31  *
  32  * For historical reasons this is off during the start of the
  33  * connection, but it's switched on quite early using
  34  * io_start_multiplex_out() and io_start_multiplex_in().
  35  **/
  36
  37 #include "rsync.h"
  38
  39 /** If no timeout is specified then use a 60 second select timeout */
  40 #define SELECT_TIMEOUT 60
  41
  42 extern int bwlimit;
  43 extern size_t bwlimit_writemax;
  44 extern int io_timeout;
  45 extern int allowed_lull;
  46 extern int am_server;
  47 extern int am_daemon;
  48 extern int am_sender;
  49 extern int am_generator;
  50 extern int eol_nulls;
  51 extern int read_batch;
  52 extern int csum_length;
  53 extern int checksum_seed;
  54 extern int protocol_version;
  55 extern int remove_sent_files;
  56 extern int preserve_hard_links;
  57 extern char *filesfrom_host;
  58 extern struct stats stats;
  59 extern struct file_list *the_file_list;
  60
  61 const char phase_unknown[] = "unknown";
  62 int ignore_timeout = 0;
  63 int batch_fd = -1;
  64 int batch_gen_fd = -1;
  65
  66 /**
  67  * The connection might be dropped at some point; perhaps because the
  68  * remote instance crashed.  Just giving the offset on the stream is
  69  * not very helpful.  So instead we try to make io_phase_name point to
  70  * something useful.
  71  *
  72  * For buffered/multiplexed I/O these names will be somewhat
  73  * approximate; perhaps for ease of support we would rather make the
  74  * buffer always flush when a single application-level I/O finishes.
  75  *
  76  * @todo Perhaps we want some simple stack functionality, but there's
  77  * no need to overdo it.
  78  **/
  79 const char *io_write_phase = phase_unknown;
  80 const char *io_read_phase = phase_unknown;
  81
  82 /* Ignore an EOF error if non-zero. See whine_about_eof(). */
  83 int kluge_around_eof = 0;
  84
  85 int msg_fd_in = -1;
  86 int msg_fd_out = -1;
  87 int sock_f_in = -1;
  88 int sock_f_out = -1;
  89
  90 static int io_multiplexing_out;
  91 static int io_multiplexing_in;
  92 static time_t last_io_in;
  93 static time_t last_io_out;
  94 static int no_flush;
  95
  96 static int write_batch_monitor_in = -1;
  97 static int write_batch_monitor_out = -1;
  98
  99 static int io_filesfrom_f_in = -1;
 100 static int io_filesfrom_f_out = -1;
 101 static char io_filesfrom_buf[2048];
 102 static char *io_filesfrom_bp;
 103 static char io_filesfrom_lastchar;
 104 static int io_filesfrom_buflen;
 105 static int defer_forwarding_messages = 0;
 106 static int select_timeout = SELECT_TIMEOUT;
 107 static int active_filecnt = 0;
 108 static OFF_T active_bytecnt = 0;
 109
 110 static void read_loop(int fd, char *buf, size_t len);
 111
 112 struct flist_ndx_item {
 113         struct flist_ndx_item *next;
 114         int ndx;
 115 };
 116
 117 struct flist_ndx_list {
 118         struct flist_ndx_item *head, *tail;
 119 };
 120
 121 static struct flist_ndx_list redo_list, hlink_list;
 122
 123 struct msg_list_item {
 124         struct msg_list_item *next;
 125         int len;
 126         char buf[1];
 127 };
 128
 129 struct msg_list {
 130         struct msg_list_item *head, *tail;
 131 };
 132
 133 static struct msg_list msg2genr, msg2sndr;
 134
 135 static void flist_ndx_push(struct flist_ndx_list *lp, int ndx)
 136 {
 137         struct flist_ndx_item *item;
 138
 139         if (!(item = new(struct flist_ndx_item)))
 140                 out_of_memory("flist_ndx_push");
 141         item->next = NULL;
 142         item->ndx = ndx;
 143         if (lp->tail)
 144                 lp->tail->next = item;
 145         else
 146                 lp->head = item;
 147         lp->tail = item;
 148 }
 149
 150 static int flist_ndx_pop(struct flist_ndx_list *lp)
 151 {
 152         struct flist_ndx_item *next;
 153         int ndx;
 154
 155         if (!lp->head)
 156                 return -1;
 157
 158         ndx = lp->head->ndx;
 159         next = lp->head->next;
 160         free(lp->head);
 161         lp->head = next;
 162         if (!next)
 163                 lp->tail = NULL;
 164
 165         return ndx;
 166 }
 167
 168 static void check_timeout(void)
 169 {
 170         time_t t;
 171
 172         if (!io_timeout || ignore_timeout)
 173                 return;
 174
 175         if (!last_io_in) {
 176                 last_io_in = time(NULL);
 177                 return;
 178         }
 179
 180         t = time(NULL);
 181
 182         if (t - last_io_in >= io_timeout) {
 183                 if (!am_server && !am_daemon) {
 184                         rprintf(FERROR, "io timeout after %d seconds -- exiting\n",
 185                                 (int)(t-last_io_in));
 186                 }
 187                 exit_cleanup(RERR_TIMEOUT);
 188         }
 189 }
 190
 191 /* Note the fds used for the main socket (which might really be a pipe
 192  * for a local transfer, but we can ignore that). */
 193 void io_set_sock_fds(int f_in, int f_out)
 194 {
 195         sock_f_in = f_in;
 196         sock_f_out = f_out;
 197 }
 198
 199 void set_io_timeout(int secs)
 200 {
 201         io_timeout = secs;
 202
 203         if (!io_timeout || io_timeout > SELECT_TIMEOUT)
 204                 select_timeout = SELECT_TIMEOUT;
 205         else
 206                 select_timeout = io_timeout;
 207
 208         allowed_lull = read_batch ? 0 : (io_timeout + 1) / 2;
 209 }
 210
 211 /* Setup the fd used to receive MSG_* messages.  Only needed during the
 212  * early stages of being a local sender (up through the sending of the
 213  * file list) or when we're the generator (to fetch the messages from
 214  * the receiver). */
 215 void set_msg_fd_in(int fd)
 216 {
 217         msg_fd_in = fd;
 218 }
 219
 220 /* Setup the fd used to send our MSG_* messages.  Only needed when
 221  * we're the receiver (to send our messages to the generator). */
 222 void set_msg_fd_out(int fd)
 223 {
 224         msg_fd_out = fd;
 225         set_nonblocking(msg_fd_out);
 226 }
 227
 228 /* Add a message to the pending MSG_* list. */
 229 static void msg_list_add(struct msg_list *lst, int code, char *buf, int len)
 230 {
 231         struct msg_list_item *m;
 232         int sz = len + 4 + sizeof m[0] - 1;
 233
 234         if (!(m = (struct msg_list_item *)new_array(char, sz)))
 235                 out_of_memory("msg_list_add");
 236         m->next = NULL;
 237         m->len = len + 4;
 238         SIVAL(m->buf, 0, ((code+MPLEX_BASE)<<24) | len);
 239         memcpy(m->buf + 4, buf, len);
 240         if (lst->tail)
 241                 lst->tail->next = m;
 242         else
 243                 lst->head = m;
 244         lst->tail = m;
 245 }
 246
 247 /* Read a message from the MSG_* fd and handle it.  This is called either
 248  * during the early stages of being a local sender (up through the sending
 249  * of the file list) or when we're the generator (to fetch the messages
 250  * from the receiver). */
 251 static void read_msg_fd(void)
 252 {
 253         char buf[2048];
 254         size_t n;
 255         int fd = msg_fd_in;
 256         int tag, len;
 257
 258         /* Temporarily disable msg_fd_in.  This is needed to avoid looping back
 259          * to this routine from writefd_unbuffered(). */
 260         msg_fd_in = -1;
 261
 262         read_loop(fd, buf, 4);
 263         tag = IVAL(buf, 0);
 264
 265         len = tag & 0xFFFFFF;
 266         tag = (tag >> 24) - MPLEX_BASE;
 267
 268         switch (tag) {
 269         case MSG_DONE:
 270                 if (len != 0 || !am_generator) {
 271                         rprintf(FERROR, "invalid message %d:%d\n", tag, len);
 272                         exit_cleanup(RERR_STREAMIO);
 273                 }
 274                 flist_ndx_push(&redo_list, -1);
 275                 break;
 276         case MSG_REDO:
 277                 if (len != 4 || !am_generator) {
 278                         rprintf(FERROR, "invalid message %d:%d\n", tag, len);
 279                         exit_cleanup(RERR_STREAMIO);
 280                 }
 281                 read_loop(fd, buf, 4);
 282                 if (remove_sent_files)
 283                         decrement_active_files(IVAL(buf,0));
 284                 flist_ndx_push(&redo_list, IVAL(buf,0));
 285                 break;
 286         case MSG_DELETED:
 287                 if (len >= (int)sizeof buf || !am_generator) {
 288                         rprintf(FERROR, "invalid message %d:%d\n", tag, len);
 289                         exit_cleanup(RERR_STREAMIO);
 290                 }
 291                 read_loop(fd, buf, len);
 292                 if (defer_forwarding_messages)
 293                         msg_list_add(&msg2sndr, MSG_DELETED, buf, len);
 294                 else
 295                         io_multiplex_write(MSG_DELETED, buf, len);
 296                 break;
 297         case MSG_SUCCESS:
 298                 if (len != 4 || !am_generator) {
 299                         rprintf(FERROR, "invalid message %d:%d\n", tag, len);
 300                         exit_cleanup(RERR_STREAMIO);
 301                 }
 302                 read_loop(fd, buf, len);
 303                 if (remove_sent_files) {
 304                         decrement_active_files(IVAL(buf,0));
 305                         if (defer_forwarding_messages)
 306                                 msg_list_add(&msg2sndr, MSG_SUCCESS, buf, len);
 307                         else
 308                                 io_multiplex_write(MSG_SUCCESS, buf, len);
 309                 }
 310                 if (preserve_hard_links)
 311                         flist_ndx_push(&hlink_list, IVAL(buf,0));
 312                 break;
 313         case MSG_SOCKERR:
 314                 if (!am_generator) {
 315                         rprintf(FERROR, "invalid message %d:%d\n", tag, len);
 316                         exit_cleanup(RERR_STREAMIO);
 317                 }
 318                 close_multiplexing_out();
 319                 /* FALL THROUGH */
 320         case MSG_INFO:
 321         case MSG_ERROR:
 322         case MSG_LOG:
 323                 while (len) {
 324                         n = len;
 325                         if (n >= sizeof buf)
 326                                 n = sizeof buf - 1;
 327                         read_loop(fd, buf, n);
 328                         if (am_generator && am_server && defer_forwarding_messages)
 329                                 msg_list_add(&msg2sndr, tag, buf, n);
 330                         else
 331                                 rwrite((enum logcode)tag, buf, n);
 332                         len -= n;
 333                 }
 334                 break;
 335         default:
 336                 rprintf(FERROR, "unknown message %d:%d\n", tag, len);
 337                 exit_cleanup(RERR_STREAMIO);
 338         }
 339
 340         msg_fd_in = fd;
 341 }
 342
 343 /* This is used by the generator to limit how many file transfers can
 344  * be active at once when --remove-sent-files is specified.  Without
 345  * this, sender-side deletions were mostly happening at the end. */
 346 void increment_active_files(int ndx, int itemizing, enum logcode code)
 347 {
 348         /* TODO: tune these limits? */
 349         while (active_filecnt >= (active_bytecnt >= 128*1024 ? 10 : 50)) {
 350                 if (hlink_list.head)
 351                         check_for_finished_hlinks(itemizing, code);
 352                 read_msg_fd();
 353         }
 354
 355         active_filecnt++;
 356         active_bytecnt += the_file_list->files[ndx]->length;
 357 }
 358
 359 void decrement_active_files(int ndx)
 360 {
 361         active_filecnt--;
 362         active_bytecnt -= the_file_list->files[ndx]->length;
 363 }
 364
 365 /* Try to push messages off the list onto the wire.  If we leave with more
 366  * to do, return 0.  On error, return -1.  If everything flushed, return 1.
 367  * This is only active in the receiver. */
 368 static int msg2genr_flush(int flush_it_all)
 369 {
 370         static int written = 0;
 371         struct timeval tv;
 372         fd_set fds;
 373
 374         if (msg_fd_out < 0)
 375                 return -1;
 376
 377         while (msg2genr.head) {
 378                 struct msg_list_item *m = msg2genr.head;
 379                 int n = write(msg_fd_out, m->buf + written, m->len - written);
 380                 if (n < 0) {
 381                         if (errno == EINTR)
 382                                 continue;
 383                         if (errno != EWOULDBLOCK && errno != EAGAIN)
 384                                 return -1;
 385                         if (!flush_it_all)
 386                                 return 0;
 387                         FD_ZERO(&fds);
 388                         FD_SET(msg_fd_out, &fds);
 389                         tv.tv_sec = select_timeout;
 390                         tv.tv_usec = 0;
 391                         if (!select(msg_fd_out+1, NULL, &fds, NULL, &tv))
 392                                 check_timeout();
 393                 } else if ((written += n) == m->len) {
 394                         msg2genr.head = m->next;
 395                         if (!msg2genr.head)
 396                                 msg2genr.tail = NULL;
 397                         free(m);
 398                         written = 0;
 399                 }
 400         }
 401         return 1;
 402 }
 403
 404 void send_msg(enum msgcode code, char *buf, int len)
 405 {
 406         if (msg_fd_out < 0) {
 407                 io_multiplex_write(code, buf, len);
 408                 return;
 409         }
 410         msg_list_add(&msg2genr, code, buf, len);
 411         msg2genr_flush(NORMAL_FLUSH);
 412 }
 413
 414 int get_redo_num(int itemizing, enum logcode code)
 415 {
 416         while (1) {
 417                 if (hlink_list.head)
 418                         check_for_finished_hlinks(itemizing, code);
 419                 if (redo_list.head)
 420                         break;
 421                 read_msg_fd();
 422         }
 423
 424         return flist_ndx_pop(&redo_list);
 425 }
 426
 427 int get_hlink_num(void)
 428 {
 429         return flist_ndx_pop(&hlink_list);
 430 }
 431
 432 /**
 433  * When we're the receiver and we have a local --files-from list of names
 434  * that needs to be sent over the socket to the sender, we have to do two
 435  * things at the same time: send the sender a list of what files we're
 436  * processing and read the incoming file+info list from the sender.  We do
 437  * this by augmenting the read_timeout() function to copy this data.  It
 438  * uses the io_filesfrom_buf to read a block of data from f_in (when it is
 439  * ready, since it might be a pipe) and then blast it out f_out (when it
 440  * is ready to receive more data).
 441  */
 442 void io_set_filesfrom_fds(int f_in, int f_out)
 443 {
 444         io_filesfrom_f_in = f_in;
 445         io_filesfrom_f_out = f_out;
 446         io_filesfrom_bp = io_filesfrom_buf;
 447         io_filesfrom_lastchar = '\0';
 448         io_filesfrom_buflen = 0;
 449 }
 450
 451 /* It's almost always an error to get an EOF when we're trying to read from the
 452  * network, because the protocol is (for the most part) self-terminating.
 453  *
 454  * There is one case for the receiver when it is at the end of the transfer
 455  * (hanging around reading any keep-alive packets that might come its way): if
 456  * the sender dies before the generator's kill-signal comes through, we can end
 457  * up here needing to loop until the kill-signal arrives.  In this situation,
 458  * kluge_around_eof will be < 0.
 459  *
 460  * There is another case for older protocol versions (< 24) where the module
 461  * listing was not terminated, so we must ignore an EOF error in that case and
 462  * exit.  In this situation, kluge_around_eof will be > 0. */
 463 static void whine_about_eof(int fd)
 464 {
 465         if (kluge_around_eof && fd == sock_f_in) {
 466                 int i;
 467                 if (kluge_around_eof > 0)
 468                         exit_cleanup(0);
 469                 /* If we're still here after 10 seconds, exit with an error. */
 470                 for (i = 10*1000/20; i--; )
 471                         msleep(20);
 472         }
 473
 474         rprintf(FERROR, RSYNC_NAME ": connection unexpectedly closed "
 475                 "(%.0f bytes received so far) [%s]\n",
 476                 (double)stats.total_read, who_am_i());
 477
 478         exit_cleanup(RERR_STREAMIO);
 479 }
 480
 481 /**
 482  * Read from a socket with I/O timeout. return the number of bytes
 483  * read. If no bytes can be read then exit, never return a number <= 0.
 484  *
 485  * TODO: If the remote shell connection fails, then current versions
 486  * actually report an "unexpected EOF" error here.  Since it's a
 487  * fairly common mistake to try to use rsh when ssh is required, we
 488  * should trap that: if we fail to read any data at all, we should
 489  * give a better explanation.  We can tell whether the connection has
 490  * started by looking e.g. at whether the remote version is known yet.
 491  */
 492 static int read_timeout(int fd, char *buf, size_t len)
 493 {
 494         int n, cnt = 0;
 495
 496         io_flush(NORMAL_FLUSH);
 497
 498         while (cnt == 0) {
 499                 /* until we manage to read *something* */
 500                 fd_set r_fds, w_fds;
 501                 struct timeval tv;
 502                 int maxfd = fd;
 503                 int count;
 504
 505                 FD_ZERO(&r_fds);
 506                 FD_ZERO(&w_fds);
 507                 FD_SET(fd, &r_fds);
 508                 if (msg2genr.head) {
 509                         FD_SET(msg_fd_out, &w_fds);
 510                         if (msg_fd_out > maxfd)
 511                                 maxfd = msg_fd_out;
 512                 }
 513                 if (io_filesfrom_f_out >= 0) {
 514                         int new_fd;
 515                         if (io_filesfrom_buflen == 0) {
 516                                 if (io_filesfrom_f_in >= 0) {
 517                                         FD_SET(io_filesfrom_f_in, &r_fds);
 518                                         new_fd = io_filesfrom_f_in;
 519                                 } else {
 520                                         io_filesfrom_f_out = -1;
 521                                         new_fd = -1;
 522                                 }
 523                         } else {
 524                                 FD_SET(io_filesfrom_f_out, &w_fds);
 525                                 new_fd = io_filesfrom_f_out;
 526                         }
 527                         if (new_fd > maxfd)
 528                                 maxfd = new_fd;
 529                 }
 530
 531                 tv.tv_sec = select_timeout;
 532                 tv.tv_usec = 0;
 533
 534                 errno = 0;
 535
 536                 count = select(maxfd + 1, &r_fds, &w_fds, NULL, &tv);
 537
 538                 if (count <= 0) {
 539                         if (errno == EBADF)
 540                                 exit_cleanup(RERR_SOCKETIO);
 541                         check_timeout();
 542                         continue;
 543                 }
 544
 545                 if (msg2genr.head && FD_ISSET(msg_fd_out, &w_fds))
 546                         msg2genr_flush(NORMAL_FLUSH);
 547
 548                 if (io_filesfrom_f_out >= 0) {
 549                         if (io_filesfrom_buflen) {
 550                                 if (FD_ISSET(io_filesfrom_f_out, &w_fds)) {
 551                                         int l = write(io_filesfrom_f_out,
 552                                                       io_filesfrom_bp,
 553                                                       io_filesfrom_buflen);
 554                                         if (l > 0) {
 555                                                 if (!(io_filesfrom_buflen -= l))
 556                                                         io_filesfrom_bp = io_filesfrom_buf;
 557                                                 else
 558                                                         io_filesfrom_bp += l;
 559                                         } else {
 560                                                 /* XXX should we complain? */
 561                                                 io_filesfrom_f_out = -1;
 562                                         }
 563                                 }
 564                         } else if (io_filesfrom_f_in >= 0) {
 565                                 if (FD_ISSET(io_filesfrom_f_in, &r_fds)) {
 566                                         int l = read(io_filesfrom_f_in,
 567                                                      io_filesfrom_buf,
 568                                                      sizeof io_filesfrom_buf);
 569                                         if (l <= 0) {
 570                                                 /* Send end-of-file marker */
 571                                                 io_filesfrom_buf[0] = '\0';
 572                                                 io_filesfrom_buf[1] = '\0';
 573                                                 io_filesfrom_buflen = io_filesfrom_lastchar? 2 : 1;
 574                                                 io_filesfrom_f_in = -1;
 575                                         } else {
 576                                                 if (!eol_nulls) {
 577                                                         char *s = io_filesfrom_buf + l;
 578                                                         /* Transform CR and/or LF into '\0' */
 579                                                         while (s-- > io_filesfrom_buf) {
 580                                                                 if (*s == '\n' || *s == '\r')
 581                                                                         *s = '\0';
 582                                                         }
 583                                                 }
 584                                                 if (!io_filesfrom_lastchar) {
 585                                                         /* Last buf ended with a '\0', so don't
 586                                                          * let this buf start with one. */
 587                                                         while (l && !*io_filesfrom_bp)
 588                                                                 io_filesfrom_bp++, l--;
 589                                                 }
 590                                                 if (!l)
 591                                                         io_filesfrom_bp = io_filesfrom_buf;
 592                                                 else {
 593                                                         char *f = io_filesfrom_bp;
 594                                                         char *t = f;
 595                                                         char *eob = f + l;
 596                                                         /* Eliminate any multi-'\0' runs. */
 597                                                         while (f != eob) {
 598                                                                 if (!(*t++ = *f++)) {
 599                                                                         while (f != eob && !*f)
 600                                                                                 f++, l--;
 601                                                                 }
 602                                                         }
 603                                                         io_filesfrom_lastchar = f[-1];
 604                                                 }
 605                                                 io_filesfrom_buflen = l;
 606                                         }
 607                                 }
 608                         }
 609                 }
 610
 611                 if (!FD_ISSET(fd, &r_fds))
 612                         continue;
 613
 614                 n = read(fd, buf, len);
 615
 616                 if (n <= 0) {
 617                         if (n == 0)
 618                                 whine_about_eof(fd); /* Doesn't return. */
 619                         if (errno == EINTR || errno == EWOULDBLOCK
 620                             || errno == EAGAIN)
 621                                 continue;
 622
 623                         /* Don't write errors on a dead socket. */
 624                         if (fd == sock_f_in) {
 625                                 close_multiplexing_out();
 626                                 rsyserr(FSOCKERR, errno, "read error");
 627                         } else
 628                                 rsyserr(FERROR, errno, "read error");
 629                         exit_cleanup(RERR_STREAMIO);
 630                 }
 631
 632                 buf += n;
 633                 len -= n;
 634                 cnt += n;
 635
 636                 if (fd == sock_f_in && io_timeout)
 637                         last_io_in = time(NULL);
 638         }
 639
 640         return cnt;
 641 }
 642
 643 /**
 644  * Read a line into the "fname" buffer (which must be at least MAXPATHLEN
 645  * characters long).
 646  */
 647 int read_filesfrom_line(int fd, char *fname)
 648 {
 649         char ch, *s, *eob = fname + MAXPATHLEN - 1;
 650         int cnt;
 651         int reading_remotely = filesfrom_host != NULL;
 652         int nulls = eol_nulls || reading_remotely;
 653
 654   start:
 655         s = fname;
 656         while (1) {
 657                 cnt = read(fd, &ch, 1);
 658                 if (cnt < 0 && (errno == EWOULDBLOCK
 659                   || errno == EINTR || errno == EAGAIN)) {
 660                         struct timeval tv;
 661                         fd_set fds;
 662                         FD_ZERO(&fds);
 663                         FD_SET(fd, &fds);
 664                         tv.tv_sec = select_timeout;
 665                         tv.tv_usec = 0;
 666                         if (!select(fd+1, &fds, NULL, NULL, &tv))
 667                                 check_timeout();
 668                         continue;
 669                 }
 670                 if (cnt != 1)
 671                         break;
 672                 if (nulls? !ch : (ch == '\r' || ch == '\n')) {
 673                         /* Skip empty lines if reading locally. */
 674                         if (!reading_remotely && s == fname)
 675                                 continue;
 676                         break;
 677                 }
 678                 if (s < eob)
 679                         *s++ = ch;
 680         }
 681         *s = '\0';
 682
 683         /* Dump comments. */
 684         if (*fname == '#' || *fname == ';')
 685                 goto start;
 686
 687         return s - fname;
 688 }
 689
 690 static char *iobuf_out;
 691 static int iobuf_out_cnt;
 692
 693 void io_start_buffering_out(void)
 694 {
 695         if (iobuf_out)
 696                 return;
 697         if (!(iobuf_out = new_array(char, IO_BUFFER_SIZE)))
 698                 out_of_memory("io_start_buffering_out");
 699         iobuf_out_cnt = 0;
 700 }
 701
 702 static char *iobuf_in;
 703 static size_t iobuf_in_siz;
 704
 705 void io_start_buffering_in(void)
 706 {
 707         if (iobuf_in)
 708                 return;
 709         iobuf_in_siz = 2 * IO_BUFFER_SIZE;
 710         if (!(iobuf_in = new_array(char, iobuf_in_siz)))
 711                 out_of_memory("io_start_buffering_in");
 712 }
 713
 714 void io_end_buffering(void)
 715 {
 716         io_flush(NORMAL_FLUSH);
 717         if (!io_multiplexing_out) {
 718                 free(iobuf_out);
 719                 iobuf_out = NULL;
 720         }
 721 }
 722
 723 void maybe_flush_socket(void)
 724 {
 725         if (iobuf_out && iobuf_out_cnt && time(NULL) - last_io_out >= 5)
 726                 io_flush(NORMAL_FLUSH);
 727 }
 728
 729 void maybe_send_keepalive(void)
 730 {
 731         if (time(NULL) - last_io_out >= allowed_lull) {
 732                 if (!iobuf_out || !iobuf_out_cnt) {
 733                         if (protocol_version < 29)
 734                                 return; /* there's nothing we can do */
 735                         write_int(sock_f_out, the_file_list->count);
 736                         write_shortint(sock_f_out, ITEM_IS_NEW);
 737                 }
 738                 if (iobuf_out)
 739                         io_flush(NORMAL_FLUSH);
 740         }
 741 }
 742
 743 /**
 744  * Continue trying to read len bytes - don't return until len has been
 745  * read.
 746  **/
 747 static void read_loop(int fd, char *buf, size_t len)
 748 {
 749         while (len) {
 750                 int n = read_timeout(fd, buf, len);
 751
 752                 buf += n;
 753                 len -= n;
 754         }
 755 }
 756
 757 /**
 758  * Read from the file descriptor handling multiplexing - return number
 759  * of bytes read.
 760  *
 761  * Never returns <= 0.
 762  */
 763 static int readfd_unbuffered(int fd, char *buf, size_t len)
 764 {
 765         static size_t remaining;
 766         static size_t iobuf_in_ndx;
 767         size_t msg_bytes;
 768         int tag, cnt = 0;
 769         char line[BIGPATHBUFLEN];
 770
 771         if (!iobuf_in || fd != sock_f_in)
 772                 return read_timeout(fd, buf, len);
 773
 774         if (!io_multiplexing_in && remaining == 0) {
 775                 remaining = read_timeout(fd, iobuf_in, iobuf_in_siz);
 776                 iobuf_in_ndx = 0;
 777         }
 778
 779         while (cnt == 0) {
 780                 if (remaining) {
 781                         len = MIN(len, remaining);
 782                         memcpy(buf, iobuf_in + iobuf_in_ndx, len);
 783                         iobuf_in_ndx += len;
 784                         remaining -= len;
 785                         cnt = len;
 786                         break;
 787                 }
 788
 789                 read_loop(fd, line, 4);
 790                 tag = IVAL(line, 0);
 791
 792                 msg_bytes = tag & 0xFFFFFF;
 793                 tag = (tag >> 24) - MPLEX_BASE;
 794
 795                 switch (tag) {
 796                 case MSG_DATA:
 797                         if (msg_bytes > iobuf_in_siz) {
 798                                 if (!(iobuf_in = realloc_array(iobuf_in, char,
 799                                                                msg_bytes)))
 800                                         out_of_memory("readfd_unbuffered");
 801                                 iobuf_in_siz = msg_bytes;
 802                         }
 803                         read_loop(fd, iobuf_in, msg_bytes);
 804                         remaining = msg_bytes;
 805                         iobuf_in_ndx = 0;
 806                         break;
 807                 case MSG_DELETED:
 808                         if (msg_bytes >= sizeof line)
 809                                 goto overflow;
 810                         read_loop(fd, line, msg_bytes);
 811                         /* A directory name was sent with the trailing null */
 812                         if (msg_bytes > 0 && !line[msg_bytes-1])
 813                                 log_delete(line, S_IFDIR);
 814                         else {
 815                                 line[msg_bytes] = '\0';
 816                                 log_delete(line, S_IFREG);
 817                         }
 818                         break;
 819                 case MSG_SUCCESS:
 820                         if (msg_bytes != 4) {
 821                                 rprintf(FERROR, "invalid multi-message %d:%ld [%s]\n",
 822                                         tag, (long)msg_bytes, who_am_i());
 823                                 exit_cleanup(RERR_STREAMIO);
 824                         }
 825                         read_loop(fd, line, msg_bytes);
 826                         successful_send(IVAL(line, 0));
 827                         break;
 828                 case MSG_INFO:
 829                 case MSG_ERROR:
 830                         if (msg_bytes >= sizeof line) {
 831                             overflow:
 832                                 rprintf(FERROR,
 833                                         "multiplexing overflow %d:%ld [%s]\n",
 834                                         tag, (long)msg_bytes, who_am_i());
 835                                 exit_cleanup(RERR_STREAMIO);
 836                         }
 837                         read_loop(fd, line, msg_bytes);
 838                         rwrite((enum logcode)tag, line, msg_bytes);
 839                         break;
 840                 default:
 841                         rprintf(FERROR, "unexpected tag %d [%s]\n",
 842                                 tag, who_am_i());
 843                         exit_cleanup(RERR_STREAMIO);
 844                 }
 845         }
 846
 847         if (remaining == 0)
 848                 io_flush(NORMAL_FLUSH);
 849
 850         return cnt;
 851 }
 852
 853 /**
 854  * Do a buffered read from @p fd.  Don't return until all @p n bytes
 855  * have been read.  If all @p n can't be read then exit with an
 856  * error.
 857  **/
 858 static void readfd(int fd, char *buffer, size_t N)
 859 {
 860         int  cnt;
 861         size_t total = 0;
 862
 863         while (total < N) {
 864                 cnt = readfd_unbuffered(fd, buffer + total, N-total);
 865                 total += cnt;
 866         }
 867
 868         if (fd == write_batch_monitor_in) {
 869                 if ((size_t)write(batch_fd, buffer, total) != total)
 870                         exit_cleanup(RERR_FILEIO);
 871         }
 872
 873         if (fd == sock_f_in)
 874                 stats.total_read += total;
 875 }
 876
 877 int read_shortint(int f)
 878 {
 879         uchar b[2];
 880         readfd(f, (char *)b, 2);
 881         return (b[1] << 8) + b[0];
 882 }
 883
 884 int32 read_int(int f)
 885 {
 886         char b[4];
 887         int32 num;
 888
 889         readfd(f,b,4);
 890         num = IVAL(b,0);
 891         if (num == (int32)0xffffffff)
 892                 return -1;
 893         return num;
 894 }
 895
 896 int64 read_longint(int f)
 897 {
 898         int64 num;
 899         char b[8];
 900         num = read_int(f);
 901
 902         if ((int32)num != (int32)0xffffffff)
 903                 return num;
 904
 905 #if SIZEOF_INT64 < 8
 906         rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
 907         exit_cleanup(RERR_UNSUPPORTED);
 908 #else
 909         readfd(f,b,8);
 910         num = IVAL(b,0) | (((int64)IVAL(b,4))<<32);
 911 #endif
 912
 913         return num;
 914 }
 915
 916 void read_buf(int f,char *buf,size_t len)
 917 {
 918         readfd(f,buf,len);
 919 }
 920
 921 void read_sbuf(int f,char *buf,size_t len)
 922 {
 923         readfd(f, buf, len);
 924         buf[len] = '\0';
 925 }
 926
 927 uchar read_byte(int f)
 928 {
 929         uchar c;
 930         readfd(f, (char *)&c, 1);
 931         return c;
 932 }
 933
 934 int read_vstring(int f, char *buf, int bufsize)
 935 {
 936         int len = read_byte(f);
 937
 938         if (len & 0x80)
 939                 len = (len & ~0x80) * 0x100 + read_byte(f);
 940
 941         if (len >= bufsize) {
 942                 rprintf(FERROR, "over-long vstring received (%d > %d)\n",
 943                         len, bufsize - 1);
 944                 return -1;
 945         }
 946
 947         if (len)
 948                 readfd(f, buf, len);
 949         buf[len] = '\0';
 950         return len;
 951 }
 952
 953 /* Populate a sum_struct with values from the socket.  This is
 954  * called by both the sender and the receiver. */
 955 void read_sum_head(int f, struct sum_struct *sum)
 956 {
 957         sum->count = read_int(f);
 958         if (sum->count < 0) {
 959                 rprintf(FERROR, "Invalid checksum count %ld [%s]\n",
 960                         (long)sum->count, who_am_i());
 961                 exit_cleanup(RERR_PROTOCOL);
 962         }
 963         sum->blength = read_int(f);
 964         if (sum->blength < 0 || sum->blength > MAX_BLOCK_SIZE) {
 965                 rprintf(FERROR, "Invalid block length %ld [%s]\n",
 966                         (long)sum->blength, who_am_i());
 967                 exit_cleanup(RERR_PROTOCOL);
 968         }
 969         sum->s2length = protocol_version < 27 ? csum_length : (int)read_int(f);
 970         if (sum->s2length < 0 || sum->s2length > MD4_SUM_LENGTH) {
 971                 rprintf(FERROR, "Invalid checksum length %d [%s]\n",
 972                         sum->s2length, who_am_i());
 973                 exit_cleanup(RERR_PROTOCOL);
 974         }
 975         sum->remainder = read_int(f);
 976         if (sum->remainder < 0 || sum->remainder > sum->blength) {
 977                 rprintf(FERROR, "Invalid remainder length %ld [%s]\n",
 978                         (long)sum->remainder, who_am_i());
 979                 exit_cleanup(RERR_PROTOCOL);
 980         }
 981 }
 982
 983 /* Send the values from a sum_struct over the socket.  Set sum to
 984  * NULL if there are no checksums to send.  This is called by both
 985  * the generator and the sender. */
 986 void write_sum_head(int f, struct sum_struct *sum)
 987 {
 988         static struct sum_struct null_sum;
 989
 990         if (sum == NULL)
 991                 sum = &null_sum;
 992
 993         write_int(f, sum->count);
 994         write_int(f, sum->blength);
 995         if (protocol_version >= 27)
 996                 write_int(f, sum->s2length);
 997         write_int(f, sum->remainder);
 998 }
 999
1000 /**
1001  * Sleep after writing to limit I/O bandwidth usage.
1002  *
1003  * @todo Rather than sleeping after each write, it might be better to
1004  * use some kind of averaging.  The current algorithm seems to always
1005  * use a bit less bandwidth than specified, because it doesn't make up
1006  * for slow periods.  But arguably this is a feature.  In addition, we
1007  * ought to take the time used to write the data into account.
1008  *
1009  * During some phases of big transfers (file FOO is uptodate) this is
1010  * called with a small bytes_written every time.  As the kernel has to
1011  * round small waits up to guarantee that we actually wait at least the
1012  * requested number of microseconds, this can become grossly inaccurate.
1013  * We therefore keep track of the bytes we've written over time and only
1014  * sleep when the accumulated delay is at least 1 tenth of a second.
1015  **/
1016 static void sleep_for_bwlimit(int bytes_written)
1017 {
1018         static struct timeval prior_tv;
1019         static long total_written = 0;
1020         struct timeval tv, start_tv;
1021         long elapsed_usec, sleep_usec;
1022
1023 #define ONE_SEC 1000000L /* # of microseconds in a second */
1024
1025         if (!bwlimit_writemax)
1026                 return;
1027
1028         total_written += bytes_written;
1029
1030         gettimeofday(&start_tv, NULL);
1031         if (prior_tv.tv_sec) {
1032                 elapsed_usec = (start_tv.tv_sec - prior_tv.tv_sec) * ONE_SEC
1033                              + (start_tv.tv_usec - prior_tv.tv_usec);
1034                 total_written -= elapsed_usec * bwlimit / (ONE_SEC/1024);
1035                 if (total_written < 0)
1036                         total_written = 0;
1037         }
1038
1039         sleep_usec = total_written * (ONE_SEC/1024) / bwlimit;
1040         if (sleep_usec < ONE_SEC / 10) {
1041                 prior_tv = start_tv;
1042                 return;
1043         }
1044
1045         tv.tv_sec  = sleep_usec / ONE_SEC;
1046         tv.tv_usec = sleep_usec % ONE_SEC;
1047         select(0, NULL, NULL, NULL, &tv);
1048
1049         gettimeofday(&prior_tv, NULL);
1050         elapsed_usec = (prior_tv.tv_sec - start_tv.tv_sec) * ONE_SEC
1051                      + (prior_tv.tv_usec - start_tv.tv_usec);
1052         total_written = (sleep_usec - elapsed_usec) * bwlimit / (ONE_SEC/1024);
1053 }
1054
1055 /* Write len bytes to the file descriptor fd, looping as necessary to get
1056  * the job done and also (in certain circumstances) reading any data on
1057  * msg_fd_in to avoid deadlock.
1058  *
1059  * This function underlies the multiplexing system.  The body of the
1060  * application never calls this function directly. */
1061 static void writefd_unbuffered(int fd,char *buf,size_t len)
1062 {
1063         size_t n, total = 0;
1064         fd_set w_fds, r_fds;
1065         int maxfd, count, cnt, using_r_fds;
1066         struct timeval tv;
1067
1068         no_flush++;
1069
1070         while (total < len) {
1071                 FD_ZERO(&w_fds);
1072                 FD_SET(fd,&w_fds);
1073                 maxfd = fd;
1074
1075                 if (msg_fd_in >= 0) {
1076                         FD_ZERO(&r_fds);
1077                         FD_SET(msg_fd_in,&r_fds);
1078                         if (msg_fd_in > maxfd)
1079                                 maxfd = msg_fd_in;
1080                         using_r_fds = 1;
1081                 } else
1082                         using_r_fds = 0;
1083
1084                 tv.tv_sec = select_timeout;
1085                 tv.tv_usec = 0;
1086
1087                 errno = 0;
1088                 count = select(maxfd + 1, using_r_fds ? &r_fds : NULL,
1089                                &w_fds, NULL, &tv);
1090
1091                 if (count <= 0) {
1092                         if (count < 0 && errno == EBADF)
1093                                 exit_cleanup(RERR_SOCKETIO);
1094                         check_timeout();
1095                         continue;
1096                 }
1097
1098                 if (using_r_fds && FD_ISSET(msg_fd_in, &r_fds))
1099                         read_msg_fd();
1100
1101                 if (!FD_ISSET(fd, &w_fds))
1102                         continue;
1103
1104                 if (msg2sndr.head && !defer_forwarding_messages) {
1105                         struct msg_list_item *m = msg2sndr.head;
1106                         int code = *((uchar*)m->buf+3) - MPLEX_BASE;
1107                         if (!(msg2sndr.head = m->next))
1108                                 msg2sndr.tail = NULL;
1109                         defer_forwarding_messages = 1;
1110                         io_multiplex_write(code, m->buf+4, m->len-4);
1111                         defer_forwarding_messages = 0;
1112                         free(m);
1113                         continue;
1114                 }
1115
1116                 n = len - total;
1117                 if (bwlimit_writemax && n > bwlimit_writemax)
1118                         n = bwlimit_writemax;
1119                 cnt = write(fd, buf + total, n);
1120
1121                 if (cnt <= 0) {
1122                         if (cnt < 0) {
1123                                 if (errno == EINTR)
1124                                         continue;
1125                                 if (errno == EWOULDBLOCK || errno == EAGAIN) {
1126                                         msleep(1);
1127                                         continue;
1128                                 }
1129                         }
1130
1131                         /* Don't try to write errors back across the stream. */
1132                         if (fd == sock_f_out)
1133                                 close_multiplexing_out();
1134                         rsyserr(FERROR, errno,
1135                                 "writefd_unbuffered failed to write %ld bytes: phase \"%s\" [%s]",
1136                                 (long)len, io_write_phase, who_am_i());
1137                         /* If the other side is sending us error messages, try
1138                          * to grab any messages they sent before they died. */
1139                         while (fd == sock_f_out && io_multiplexing_in) {
1140                                 set_io_timeout(30);
1141                                 ignore_timeout = 0;
1142                                 readfd_unbuffered(sock_f_in, io_filesfrom_buf,
1143                                                   sizeof io_filesfrom_buf);
1144                         }
1145                         exit_cleanup(RERR_STREAMIO);
1146                 }
1147
1148                 total += cnt;
1149                 defer_forwarding_messages = 1;
1150
1151                 if (fd == sock_f_out) {
1152                         if (io_timeout || am_generator)
1153                                 last_io_out = time(NULL);
1154                         sleep_for_bwlimit(cnt);
1155                 }
1156         }
1157         defer_forwarding_messages = 0;
1158
1159         no_flush--;
1160 }
1161
1162 /**
1163  * Write an message to a multiplexed stream. If this fails then rsync
1164  * exits.
1165  **/
1166 static void mplex_write(enum msgcode code, char *buf, size_t len)
1167 {
1168         char buffer[1024];
1169         size_t n = len;
1170
1171         SIVAL(buffer, 0, ((MPLEX_BASE + (int)code)<<24) + len);
1172
1173         if (n > sizeof buffer - 4)
1174                 n = 0;
1175         else
1176                 memcpy(buffer + 4, buf, n);
1177
1178         writefd_unbuffered(sock_f_out, buffer, n+4);
1179
1180         len -= n;
1181         buf += n;
1182
1183         if (len)
1184                 writefd_unbuffered(sock_f_out, buf, len);
1185 }
1186
1187 void io_flush(int flush_it_all)
1188 {
1189         msg2genr_flush(flush_it_all);
1190
1191         if (!iobuf_out_cnt || no_flush)
1192                 return;
1193
1194         if (io_multiplexing_out)
1195                 mplex_write(MSG_DATA, iobuf_out, iobuf_out_cnt);
1196         else
1197                 writefd_unbuffered(sock_f_out, iobuf_out, iobuf_out_cnt);
1198         iobuf_out_cnt = 0;
1199 }
1200
1201 static void writefd(int fd,char *buf,size_t len)
1202 {
1203         if (fd == msg_fd_out) {
1204                 rprintf(FERROR, "Internal error: wrong write used in receiver.\n");
1205                 exit_cleanup(RERR_PROTOCOL);
1206         }
1207
1208         if (fd == sock_f_out)
1209                 stats.total_written += len;
1210
1211         if (fd == write_batch_monitor_out) {
1212                 if ((size_t)write(batch_fd, buf, len) != len)
1213                         exit_cleanup(RERR_FILEIO);
1214         }
1215
1216         if (!iobuf_out || fd != sock_f_out) {
1217                 writefd_unbuffered(fd, buf, len);
1218                 return;
1219         }
1220
1221         while (len) {
1222                 int n = MIN((int)len, IO_BUFFER_SIZE - iobuf_out_cnt);
1223                 if (n > 0) {
1224                         memcpy(iobuf_out+iobuf_out_cnt, buf, n);
1225                         buf += n;
1226                         len -= n;
1227                         iobuf_out_cnt += n;
1228                 }
1229
1230                 if (iobuf_out_cnt == IO_BUFFER_SIZE)
1231                         io_flush(NORMAL_FLUSH);
1232         }
1233 }
1234
1235 void write_shortint(int f, int x)
1236 {
1237         uchar b[2];
1238         b[0] = x;
1239         b[1] = x >> 8;
1240         writefd(f, (char *)b, 2);
1241 }
1242
1243 void write_int(int f,int32 x)
1244 {
1245         char b[4];
1246         SIVAL(b,0,x);
1247         writefd(f,b,4);
1248 }
1249
1250 void write_int_named(int f, int32 x, const char *phase)
1251 {
1252         io_write_phase = phase;
1253         write_int(f, x);
1254         io_write_phase = phase_unknown;
1255 }
1256
1257 /*
1258  * Note: int64 may actually be a 32-bit type if ./configure couldn't find any
1259  * 64-bit types on this platform.
1260  */
1261 void write_longint(int f, int64 x)
1262 {
1263         char b[8];
1264
1265         if (x <= 0x7FFFFFFF) {
1266                 write_int(f, (int)x);
1267                 return;
1268         }
1269
1270 #if SIZEOF_INT64 < 8
1271         rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
1272         exit_cleanup(RERR_UNSUPPORTED);
1273 #else
1274         write_int(f, (int32)0xFFFFFFFF);
1275         SIVAL(b,0,(x&0xFFFFFFFF));
1276         SIVAL(b,4,((x>>32)&0xFFFFFFFF));
1277
1278         writefd(f,b,8);
1279 #endif
1280 }
1281
1282 void write_buf(int f,char *buf,size_t len)
1283 {
1284         writefd(f,buf,len);
1285 }
1286
1287 /** Write a string to the connection */
1288 void write_sbuf(int f, char *buf)
1289 {
1290         writefd(f, buf, strlen(buf));
1291 }
1292
1293 void write_byte(int f, uchar c)
1294 {
1295         writefd(f, (char *)&c, 1);
1296 }
1297
1298 void write_vstring(int f, char *str, int len)
1299 {
1300         uchar lenbuf[3], *lb = lenbuf;
1301
1302         if (len > 0x7F) {
1303                 if (len > 0x7FFF) {
1304                         rprintf(FERROR,
1305                                 "attempting to send over-long vstring (%d > %d)\n",
1306                                 len, 0x7FFF);
1307                         exit_cleanup(RERR_PROTOCOL);
1308                 }
1309                 *lb++ = len / 0x100 + 0x80;
1310         }
1311         *lb = len;
1312
1313         writefd(f, (char*)lenbuf, lb - lenbuf + 1);
1314         if (len)
1315                 writefd(f, str, len);
1316 }
1317
1318 /**
1319  * Read a line of up to @p maxlen characters into @p buf (not counting
1320  * the trailing null).  Strips the (required) trailing newline and all
1321  * carriage returns.
1322  *
1323  * @return 1 for success; 0 for I/O error or truncation.
1324  **/
1325 int read_line(int f, char *buf, size_t maxlen)
1326 {
1327         while (maxlen) {
1328                 buf[0] = 0;
1329                 read_buf(f, buf, 1);
1330                 if (buf[0] == 0)
1331                         return 0;
1332                 if (buf[0] == '\n')
1333                         break;
1334                 if (buf[0] != '\r') {
1335                         buf++;
1336                         maxlen--;
1337                 }
1338         }
1339         *buf = '\0';
1340         return maxlen > 0;
1341 }
1342
1343 void io_printf(int fd, const char *format, ...)
1344 {
1345         va_list ap;
1346         char buf[BIGPATHBUFLEN];
1347         int len;
1348
1349         va_start(ap, format);
1350         len = vsnprintf(buf, sizeof buf, format, ap);
1351         va_end(ap);
1352
1353         if (len < 0)
1354                 exit_cleanup(RERR_STREAMIO);
1355
1356         if (len > (int)sizeof buf) {
1357                 rprintf(FERROR, "io_printf() was too long for the buffer.\n");
1358                 exit_cleanup(RERR_STREAMIO);
1359         }
1360
1361         write_sbuf(fd, buf);
1362 }
1363
1364 /** Setup for multiplexing a MSG_* stream with the data stream. */
1365 void io_start_multiplex_out(void)
1366 {
1367         io_flush(NORMAL_FLUSH);
1368         io_start_buffering_out();
1369         io_multiplexing_out = 1;
1370 }
1371
1372 /** Setup for multiplexing a MSG_* stream with the data stream. */
1373 void io_start_multiplex_in(void)
1374 {
1375         io_flush(NORMAL_FLUSH);
1376         io_start_buffering_in();
1377         io_multiplexing_in = 1;
1378 }
1379
1380 /** Write an message to the multiplexed data stream. */
1381 int io_multiplex_write(enum msgcode code, char *buf, size_t len)
1382 {
1383         if (!io_multiplexing_out)
1384                 return 0;
1385
1386         io_flush(NORMAL_FLUSH);
1387         stats.total_written += (len+4);
1388         mplex_write(code, buf, len);
1389         return 1;
1390 }
1391
1392 void close_multiplexing_in(void)
1393 {
1394         io_multiplexing_in = 0;
1395 }
1396
1397 /** Stop output multiplexing. */
1398 void close_multiplexing_out(void)
1399 {
1400         io_multiplexing_out = 0;
1401 }
1402
1403 void start_write_batch(int fd)
1404 {
1405         write_stream_flags(batch_fd);
1406
1407         /* Some communication has already taken place, but we don't
1408          * enable batch writing until here so that we can write a
1409          * canonical record of the communication even though the
1410          * actual communication so far depends on whether a daemon
1411          * is involved. */
1412         write_int(batch_fd, protocol_version);
1413         write_int(batch_fd, checksum_seed);
1414
1415         if (am_sender)
1416                 write_batch_monitor_out = fd;
1417         else
1418                 write_batch_monitor_in = fd;
1419 }
1420
1421 void stop_write_batch(void)
1422 {
1423         write_batch_monitor_out = -1;
1424         write_batch_monitor_in = -1;
1425 }