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 /* Ignore an EOF error if non-zero. See whine_about_eof(). */
  67 int kluge_around_eof = 0;
  68
  69 int msg_fd_in = -1;
  70 int msg_fd_out = -1;
  71 int sock_f_in = -1;
  72 int sock_f_out = -1;
  73
  74 static int io_multiplexing_out;
  75 static int io_multiplexing_in;
  76 static time_t last_io_in;
  77 static time_t last_io_out;
  78 static int no_flush;
  79
  80 static int write_batch_monitor_in = -1;
  81 static int write_batch_monitor_out = -1;
  82
  83 static int io_filesfrom_f_in = -1;
  84 static int io_filesfrom_f_out = -1;
  85 static char io_filesfrom_buf[2048];
  86 static char *io_filesfrom_bp;
  87 static char io_filesfrom_lastchar;
  88 static int io_filesfrom_buflen;
  89 static int defer_forwarding_messages = 0;
  90 static int select_timeout = SELECT_TIMEOUT;
  91 static int active_filecnt = 0;
  92 static OFF_T active_bytecnt = 0;
  93
  94 static void read_loop(int fd, char *buf, size_t len);
  95
  96 struct flist_ndx_item {
  97         struct flist_ndx_item *next;
  98         int ndx;
  99 };
 100
 101 struct flist_ndx_list {
 102         struct flist_ndx_item *head, *tail;
 103 };
 104
 105 static struct flist_ndx_list redo_list, hlink_list;
 106
 107 struct msg_list_item {
 108         struct msg_list_item *next;
 109         int len;
 110         char buf[1];
 111 };
 112
 113 struct msg_list {
 114         struct msg_list_item *head, *tail;
 115 };
 116
 117 static struct msg_list msg2genr, msg2sndr;
 118
 119 static void flist_ndx_push(struct flist_ndx_list *lp, int ndx)
 120 {
 121         struct flist_ndx_item *item;
 122
 123         if (!(item = new(struct flist_ndx_item)))
 124                 out_of_memory("flist_ndx_push");
 125         item->next = NULL;
 126         item->ndx = ndx;
 127         if (lp->tail)
 128                 lp->tail->next = item;
 129         else
 130                 lp->head = item;
 131         lp->tail = item;
 132 }
 133
 134 static int flist_ndx_pop(struct flist_ndx_list *lp)
 135 {
 136         struct flist_ndx_item *next;
 137         int ndx;
 138
 139         if (!lp->head)
 140                 return -1;
 141
 142         ndx = lp->head->ndx;
 143         next = lp->head->next;
 144         free(lp->head);
 145         lp->head = next;
 146         if (!next)
 147                 lp->tail = NULL;
 148
 149         return ndx;
 150 }
 151
 152 static void check_timeout(void)
 153 {
 154         time_t t;
 155
 156         if (!io_timeout || ignore_timeout)
 157                 return;
 158
 159         if (!last_io_in) {
 160                 last_io_in = time(NULL);
 161                 return;
 162         }
 163
 164         t = time(NULL);
 165
 166         if (t - last_io_in >= io_timeout) {
 167                 if (!am_server && !am_daemon) {
 168                         rprintf(FERROR, "io timeout after %d seconds -- exiting\n",
 169                                 (int)(t-last_io_in));
 170                 }
 171                 exit_cleanup(RERR_TIMEOUT);
 172         }
 173 }
 174
 175 /* Note the fds used for the main socket (which might really be a pipe
 176  * for a local transfer, but we can ignore that). */
 177 void io_set_sock_fds(int f_in, int f_out)
 178 {
 179         sock_f_in = f_in;
 180         sock_f_out = f_out;
 181 }
 182
 183 void set_io_timeout(int secs)
 184 {
 185         io_timeout = secs;
 186
 187         if (!io_timeout || io_timeout > SELECT_TIMEOUT)
 188                 select_timeout = SELECT_TIMEOUT;
 189         else
 190                 select_timeout = io_timeout;
 191
 192         allowed_lull = read_batch ? 0 : (io_timeout + 1) / 2;
 193 }
 194
 195 /* Setup the fd used to receive MSG_* messages.  Only needed during the
 196  * early stages of being a local sender (up through the sending of the
 197  * file list) or when we're the generator (to fetch the messages from
 198  * the receiver). */
 199 void set_msg_fd_in(int fd)
 200 {
 201         msg_fd_in = fd;
 202 }
 203
 204 /* Setup the fd used to send our MSG_* messages.  Only needed when
 205  * we're the receiver (to send our messages to the generator). */
 206 void set_msg_fd_out(int fd)
 207 {
 208         msg_fd_out = fd;
 209         set_nonblocking(msg_fd_out);
 210 }
 211
 212 /* Add a message to the pending MSG_* list. */
 213 static void msg_list_add(struct msg_list *lst, int code, char *buf, int len)
 214 {
 215         struct msg_list_item *m;
 216         int sz = len + 4 + sizeof m[0] - 1;
 217
 218         if (!(m = (struct msg_list_item *)new_array(char, sz)))
 219                 out_of_memory("msg_list_add");
 220         m->next = NULL;
 221         m->len = len + 4;
 222         SIVAL(m->buf, 0, ((code+MPLEX_BASE)<<24) | len);
 223         memcpy(m->buf + 4, buf, len);
 224         if (lst->tail)
 225                 lst->tail->next = m;
 226         else
 227                 lst->head = m;
 228         lst->tail = m;
 229 }
 230
 231 /* Read a message from the MSG_* fd and handle it.  This is called either
 232  * during the early stages of being a local sender (up through the sending
 233  * of the file list) or when we're the generator (to fetch the messages
 234  * from the receiver). */
 235 static void read_msg_fd(void)
 236 {
 237         char buf[2048];
 238         size_t n;
 239         int fd = msg_fd_in;
 240         int tag, len;
 241
 242         /* Temporarily disable msg_fd_in.  This is needed to avoid looping back
 243          * to this routine from writefd_unbuffered(). */
 244         msg_fd_in = -1;
 245
 246         read_loop(fd, buf, 4);
 247         tag = IVAL(buf, 0);
 248
 249         len = tag & 0xFFFFFF;
 250         tag = (tag >> 24) - MPLEX_BASE;
 251
 252         switch (tag) {
 253         case MSG_DONE:
 254                 if (len != 0 || !am_generator) {
 255                         rprintf(FERROR, "invalid message %d:%d\n", tag, len);
 256                         exit_cleanup(RERR_STREAMIO);
 257                 }
 258                 flist_ndx_push(&redo_list, -1);
 259                 break;
 260         case MSG_REDO:
 261                 if (len != 4 || !am_generator) {
 262                         rprintf(FERROR, "invalid message %d:%d\n", tag, len);
 263                         exit_cleanup(RERR_STREAMIO);
 264                 }
 265                 read_loop(fd, buf, 4);
 266                 if (remove_sent_files)
 267                         decrement_active_files(IVAL(buf,0));
 268                 flist_ndx_push(&redo_list, IVAL(buf,0));
 269                 break;
 270         case MSG_DELETED:
 271                 if (len >= (int)sizeof buf || !am_generator) {
 272                         rprintf(FERROR, "invalid message %d:%d\n", tag, len);
 273                         exit_cleanup(RERR_STREAMIO);
 274                 }
 275                 read_loop(fd, buf, len);
 276                 if (defer_forwarding_messages)
 277                         msg_list_add(&msg2sndr, MSG_DELETED, buf, len);
 278                 else
 279                         io_multiplex_write(MSG_DELETED, buf, len);
 280                 break;
 281         case MSG_SUCCESS:
 282                 if (len != 4 || !am_generator) {
 283                         rprintf(FERROR, "invalid message %d:%d\n", tag, len);
 284                         exit_cleanup(RERR_STREAMIO);
 285                 }
 286                 read_loop(fd, buf, len);
 287                 if (remove_sent_files) {
 288                         decrement_active_files(IVAL(buf,0));
 289                         if (defer_forwarding_messages)
 290                                 msg_list_add(&msg2sndr, MSG_SUCCESS, buf, len);
 291                         else
 292                                 io_multiplex_write(MSG_SUCCESS, buf, len);
 293                 }
 294                 if (preserve_hard_links)
 295                         flist_ndx_push(&hlink_list, IVAL(buf,0));
 296                 break;
 297         case MSG_SOCKERR:
 298                 if (!am_generator) {
 299                         rprintf(FERROR, "invalid message %d:%d\n", tag, len);
 300                         exit_cleanup(RERR_STREAMIO);
 301                 }
 302                 close_multiplexing_out();
 303                 /* FALL THROUGH */
 304         case MSG_INFO:
 305         case MSG_ERROR:
 306         case MSG_LOG:
 307                 while (len) {
 308                         n = len;
 309                         if (n >= sizeof buf)
 310                                 n = sizeof buf - 1;
 311                         read_loop(fd, buf, n);
 312                         if (am_generator && am_server && defer_forwarding_messages)
 313                                 msg_list_add(&msg2sndr, tag, buf, n);
 314                         else
 315                                 rwrite((enum logcode)tag, buf, n);
 316                         len -= n;
 317                 }
 318                 break;
 319         default:
 320                 rprintf(FERROR, "unknown message %d:%d [%s]\n",
 321                         tag, len, who_am_i());
 322                 exit_cleanup(RERR_STREAMIO);
 323         }
 324
 325         msg_fd_in = fd;
 326 }
 327
 328 /* This is used by the generator to limit how many file transfers can
 329  * be active at once when --remove-sent-files is specified.  Without
 330  * this, sender-side deletions were mostly happening at the end. */
 331 void increment_active_files(int ndx, int itemizing, enum logcode code)
 332 {
 333         /* TODO: tune these limits? */
 334         while (active_filecnt >= (active_bytecnt >= 128*1024 ? 10 : 50)) {
 335                 if (hlink_list.head)
 336                         check_for_finished_hlinks(itemizing, code);
 337                 read_msg_fd();
 338         }
 339
 340         active_filecnt++;
 341         active_bytecnt += the_file_list->files[ndx]->length;
 342 }
 343
 344 void decrement_active_files(int ndx)
 345 {
 346         active_filecnt--;
 347         active_bytecnt -= the_file_list->files[ndx]->length;
 348 }
 349
 350 /* Try to push messages off the list onto the wire.  If we leave with more
 351  * to do, return 0.  On error, return -1.  If everything flushed, return 1.
 352  * This is only active in the receiver. */
 353 static int msg2genr_flush(int flush_it_all)
 354 {
 355         static int written = 0;
 356         struct timeval tv;
 357         fd_set fds;
 358
 359         if (msg_fd_out < 0)
 360                 return -1;
 361
 362         while (msg2genr.head) {
 363                 struct msg_list_item *m = msg2genr.head;
 364                 int n = write(msg_fd_out, m->buf + written, m->len - written);
 365                 if (n < 0) {
 366                         if (errno == EINTR)
 367                                 continue;
 368                         if (errno != EWOULDBLOCK && errno != EAGAIN)
 369                                 return -1;
 370                         if (!flush_it_all)
 371                                 return 0;
 372                         FD_ZERO(&fds);
 373                         FD_SET(msg_fd_out, &fds);
 374                         tv.tv_sec = select_timeout;
 375                         tv.tv_usec = 0;
 376                         if (!select(msg_fd_out+1, NULL, &fds, NULL, &tv))
 377                                 check_timeout();
 378                 } else if ((written += n) == m->len) {
 379                         msg2genr.head = m->next;
 380                         if (!msg2genr.head)
 381                                 msg2genr.tail = NULL;
 382                         free(m);
 383                         written = 0;
 384                 }
 385         }
 386         return 1;
 387 }
 388
 389 void send_msg(enum msgcode code, char *buf, int len)
 390 {
 391         if (msg_fd_out < 0) {
 392                 io_multiplex_write(code, buf, len);
 393                 return;
 394         }
 395         msg_list_add(&msg2genr, code, buf, len);
 396         msg2genr_flush(NORMAL_FLUSH);
 397 }
 398
 399 int get_redo_num(int itemizing, enum logcode code)
 400 {
 401         while (1) {
 402                 if (hlink_list.head)
 403                         check_for_finished_hlinks(itemizing, code);
 404                 if (redo_list.head)
 405                         break;
 406                 read_msg_fd();
 407         }
 408
 409         return flist_ndx_pop(&redo_list);
 410 }
 411
 412 int get_hlink_num(void)
 413 {
 414         return flist_ndx_pop(&hlink_list);
 415 }
 416
 417 /**
 418  * When we're the receiver and we have a local --files-from list of names
 419  * that needs to be sent over the socket to the sender, we have to do two
 420  * things at the same time: send the sender a list of what files we're
 421  * processing and read the incoming file+info list from the sender.  We do
 422  * this by augmenting the read_timeout() function to copy this data.  It
 423  * uses the io_filesfrom_buf to read a block of data from f_in (when it is
 424  * ready, since it might be a pipe) and then blast it out f_out (when it
 425  * is ready to receive more data).
 426  */
 427 void io_set_filesfrom_fds(int f_in, int f_out)
 428 {
 429         io_filesfrom_f_in = f_in;
 430         io_filesfrom_f_out = f_out;
 431         io_filesfrom_bp = io_filesfrom_buf;
 432         io_filesfrom_lastchar = '\0';
 433         io_filesfrom_buflen = 0;
 434 }
 435
 436 /* It's almost always an error to get an EOF when we're trying to read from the
 437  * network, because the protocol is (for the most part) self-terminating.
 438  *
 439  * There is one case for the receiver when it is at the end of the transfer
 440  * (hanging around reading any keep-alive packets that might come its way): if
 441  * the sender dies before the generator's kill-signal comes through, we can end
 442  * up here needing to loop until the kill-signal arrives.  In this situation,
 443  * kluge_around_eof will be < 0.
 444  *
 445  * There is another case for older protocol versions (< 24) where the module
 446  * listing was not terminated, so we must ignore an EOF error in that case and
 447  * exit.  In this situation, kluge_around_eof will be > 0. */
 448 static void whine_about_eof(int fd)
 449 {
 450         if (kluge_around_eof && fd == sock_f_in) {
 451                 int i;
 452                 if (kluge_around_eof > 0)
 453                         exit_cleanup(0);
 454                 /* If we're still here after 10 seconds, exit with an error. */
 455                 for (i = 10*1000/20; i--; )
 456                         msleep(20);
 457         }
 458
 459         rprintf(FERROR, RSYNC_NAME ": connection unexpectedly closed "
 460                 "(%.0f bytes received so far) [%s]\n",
 461                 (double)stats.total_read, who_am_i());
 462
 463         exit_cleanup(RERR_STREAMIO);
 464 }
 465
 466 /**
 467  * Read from a socket with I/O timeout. return the number of bytes
 468  * read. If no bytes can be read then exit, never return a number <= 0.
 469  *
 470  * TODO: If the remote shell connection fails, then current versions
 471  * actually report an "unexpected EOF" error here.  Since it's a
 472  * fairly common mistake to try to use rsh when ssh is required, we
 473  * should trap that: if we fail to read any data at all, we should
 474  * give a better explanation.  We can tell whether the connection has
 475  * started by looking e.g. at whether the remote version is known yet.
 476  */
 477 static int read_timeout(int fd, char *buf, size_t len)
 478 {
 479         int n, cnt = 0;
 480
 481         io_flush(NORMAL_FLUSH);
 482
 483         while (cnt == 0) {
 484                 /* until we manage to read *something* */
 485                 fd_set r_fds, w_fds;
 486                 struct timeval tv;
 487                 int maxfd = fd;
 488                 int count;
 489
 490                 FD_ZERO(&r_fds);
 491                 FD_ZERO(&w_fds);
 492                 FD_SET(fd, &r_fds);
 493                 if (msg2genr.head) {
 494                         FD_SET(msg_fd_out, &w_fds);
 495                         if (msg_fd_out > maxfd)
 496                                 maxfd = msg_fd_out;
 497                 }
 498                 if (io_filesfrom_f_out >= 0) {
 499                         int new_fd;
 500                         if (io_filesfrom_buflen == 0) {
 501                                 if (io_filesfrom_f_in >= 0) {
 502                                         FD_SET(io_filesfrom_f_in, &r_fds);
 503                                         new_fd = io_filesfrom_f_in;
 504                                 } else {
 505                                         io_filesfrom_f_out = -1;
 506                                         new_fd = -1;
 507                                 }
 508                         } else {
 509                                 FD_SET(io_filesfrom_f_out, &w_fds);
 510                                 new_fd = io_filesfrom_f_out;
 511                         }
 512                         if (new_fd > maxfd)
 513                                 maxfd = new_fd;
 514                 }
 515
 516                 tv.tv_sec = select_timeout;
 517                 tv.tv_usec = 0;
 518
 519                 errno = 0;
 520
 521                 count = select(maxfd + 1, &r_fds, &w_fds, NULL, &tv);
 522
 523                 if (count <= 0) {
 524                         if (errno == EBADF)
 525                                 exit_cleanup(RERR_SOCKETIO);
 526                         check_timeout();
 527                         continue;
 528                 }
 529
 530                 if (msg2genr.head && FD_ISSET(msg_fd_out, &w_fds))
 531                         msg2genr_flush(NORMAL_FLUSH);
 532
 533                 if (io_filesfrom_f_out >= 0) {
 534                         if (io_filesfrom_buflen) {
 535                                 if (FD_ISSET(io_filesfrom_f_out, &w_fds)) {
 536                                         int l = write(io_filesfrom_f_out,
 537                                                       io_filesfrom_bp,
 538                                                       io_filesfrom_buflen);
 539                                         if (l > 0) {
 540                                                 if (!(io_filesfrom_buflen -= l))
 541                                                         io_filesfrom_bp = io_filesfrom_buf;
 542                                                 else
 543                                                         io_filesfrom_bp += l;
 544                                         } else {
 545                                                 /* XXX should we complain? */
 546                                                 io_filesfrom_f_out = -1;
 547                                         }
 548                                 }
 549                         } else if (io_filesfrom_f_in >= 0) {
 550                                 if (FD_ISSET(io_filesfrom_f_in, &r_fds)) {
 551                                         int l = read(io_filesfrom_f_in,
 552                                                      io_filesfrom_buf,
 553                                                      sizeof io_filesfrom_buf);
 554                                         if (l <= 0) {
 555                                                 /* Send end-of-file marker */
 556                                                 io_filesfrom_buf[0] = '\0';
 557                                                 io_filesfrom_buf[1] = '\0';
 558                                                 io_filesfrom_buflen = io_filesfrom_lastchar? 2 : 1;
 559                                                 io_filesfrom_f_in = -1;
 560                                         } else {
 561                                                 if (!eol_nulls) {
 562                                                         char *s = io_filesfrom_buf + l;
 563                                                         /* Transform CR and/or LF into '\0' */
 564                                                         while (s-- > io_filesfrom_buf) {
 565                                                                 if (*s == '\n' || *s == '\r')
 566                                                                         *s = '\0';
 567                                                         }
 568                                                 }
 569                                                 if (!io_filesfrom_lastchar) {
 570                                                         /* Last buf ended with a '\0', so don't
 571                                                          * let this buf start with one. */
 572                                                         while (l && !*io_filesfrom_bp)
 573                                                                 io_filesfrom_bp++, l--;
 574                                                 }
 575                                                 if (!l)
 576                                                         io_filesfrom_bp = io_filesfrom_buf;
 577                                                 else {
 578                                                         char *f = io_filesfrom_bp;
 579                                                         char *t = f;
 580                                                         char *eob = f + l;
 581                                                         /* Eliminate any multi-'\0' runs. */
 582                                                         while (f != eob) {
 583                                                                 if (!(*t++ = *f++)) {
 584                                                                         while (f != eob && !*f)
 585                                                                                 f++, l--;
 586                                                                 }
 587                                                         }
 588                                                         io_filesfrom_lastchar = f[-1];
 589                                                 }
 590                                                 io_filesfrom_buflen = l;
 591                                         }
 592                                 }
 593                         }
 594                 }
 595
 596                 if (!FD_ISSET(fd, &r_fds))
 597                         continue;
 598
 599                 n = read(fd, buf, len);
 600
 601                 if (n <= 0) {
 602                         if (n == 0)
 603                                 whine_about_eof(fd); /* Doesn't return. */
 604                         if (errno == EINTR || errno == EWOULDBLOCK
 605                             || errno == EAGAIN)
 606                                 continue;
 607
 608                         /* Don't write errors on a dead socket. */
 609                         if (fd == sock_f_in) {
 610                                 close_multiplexing_out();
 611                                 rsyserr(FSOCKERR, errno, "read error");
 612                         } else
 613                                 rsyserr(FERROR, errno, "read error");
 614                         exit_cleanup(RERR_STREAMIO);
 615                 }
 616
 617                 buf += n;
 618                 len -= n;
 619                 cnt += n;
 620
 621                 if (fd == sock_f_in && io_timeout)
 622                         last_io_in = time(NULL);
 623         }
 624
 625         return cnt;
 626 }
 627
 628 /**
 629  * Read a line into the "fname" buffer (which must be at least MAXPATHLEN
 630  * characters long).
 631  */
 632 int read_filesfrom_line(int fd, char *fname)
 633 {
 634         char ch, *s, *eob = fname + MAXPATHLEN - 1;
 635         int cnt;
 636         int reading_remotely = filesfrom_host != NULL;
 637         int nulls = eol_nulls || reading_remotely;
 638
 639   start:
 640         s = fname;
 641         while (1) {
 642                 cnt = read(fd, &ch, 1);
 643                 if (cnt < 0 && (errno == EWOULDBLOCK
 644                   || errno == EINTR || errno == EAGAIN)) {
 645                         struct timeval tv;
 646                         fd_set fds;
 647                         FD_ZERO(&fds);
 648                         FD_SET(fd, &fds);
 649                         tv.tv_sec = select_timeout;
 650                         tv.tv_usec = 0;
 651                         if (!select(fd+1, &fds, NULL, NULL, &tv))
 652                                 check_timeout();
 653                         continue;
 654                 }
 655                 if (cnt != 1)
 656                         break;
 657                 if (nulls? !ch : (ch == '\r' || ch == '\n')) {
 658                         /* Skip empty lines if reading locally. */
 659                         if (!reading_remotely && s == fname)
 660                                 continue;
 661                         break;
 662                 }
 663                 if (s < eob)
 664                         *s++ = ch;
 665         }
 666         *s = '\0';
 667
 668         /* Dump comments. */
 669         if (*fname == '#' || *fname == ';')
 670                 goto start;
 671
 672         return s - fname;
 673 }
 674
 675 static char *iobuf_out;
 676 static int iobuf_out_cnt;
 677
 678 void io_start_buffering_out(void)
 679 {
 680         if (iobuf_out)
 681                 return;
 682         if (!(iobuf_out = new_array(char, IO_BUFFER_SIZE)))
 683                 out_of_memory("io_start_buffering_out");
 684         iobuf_out_cnt = 0;
 685 }
 686
 687 static char *iobuf_in;
 688 static size_t iobuf_in_siz;
 689
 690 void io_start_buffering_in(void)
 691 {
 692         if (iobuf_in)
 693                 return;
 694         iobuf_in_siz = 2 * IO_BUFFER_SIZE;
 695         if (!(iobuf_in = new_array(char, iobuf_in_siz)))
 696                 out_of_memory("io_start_buffering_in");
 697 }
 698
 699 void io_end_buffering(void)
 700 {
 701         io_flush(NORMAL_FLUSH);
 702         if (!io_multiplexing_out) {
 703                 free(iobuf_out);
 704                 iobuf_out = NULL;
 705         }
 706 }
 707
 708 void maybe_flush_socket(void)
 709 {
 710         if (iobuf_out && iobuf_out_cnt && time(NULL) - last_io_out >= 5)
 711                 io_flush(NORMAL_FLUSH);
 712 }
 713
 714 void maybe_send_keepalive(void)
 715 {
 716         if (time(NULL) - last_io_out >= allowed_lull) {
 717                 if (!iobuf_out || !iobuf_out_cnt) {
 718                         if (protocol_version < 29)
 719                                 return; /* there's nothing we can do */
 720                         write_int(sock_f_out, the_file_list->count);
 721                         write_shortint(sock_f_out, ITEM_IS_NEW);
 722                 }
 723                 if (iobuf_out)
 724                         io_flush(NORMAL_FLUSH);
 725         }
 726 }
 727
 728 /**
 729  * Continue trying to read len bytes - don't return until len has been
 730  * read.
 731  **/
 732 static void read_loop(int fd, char *buf, size_t len)
 733 {
 734         while (len) {
 735                 int n = read_timeout(fd, buf, len);
 736
 737                 buf += n;
 738                 len -= n;
 739         }
 740 }
 741
 742 /**
 743  * Read from the file descriptor handling multiplexing - return number
 744  * of bytes read.
 745  *
 746  * Never returns <= 0.
 747  */
 748 static int readfd_unbuffered(int fd, char *buf, size_t len)
 749 {
 750         static size_t remaining;
 751         static size_t iobuf_in_ndx;
 752         size_t msg_bytes;
 753         int tag, cnt = 0;
 754         char line[BIGPATHBUFLEN];
 755
 756         if (!iobuf_in || fd != sock_f_in)
 757                 return read_timeout(fd, buf, len);
 758
 759         if (!io_multiplexing_in && remaining == 0) {
 760                 remaining = read_timeout(fd, iobuf_in, iobuf_in_siz);
 761                 iobuf_in_ndx = 0;
 762         }
 763
 764         while (cnt == 0) {
 765                 if (remaining) {
 766                         len = MIN(len, remaining);
 767                         memcpy(buf, iobuf_in + iobuf_in_ndx, len);
 768                         iobuf_in_ndx += len;
 769                         remaining -= len;
 770                         cnt = len;
 771                         break;
 772                 }
 773
 774                 read_loop(fd, line, 4);
 775                 tag = IVAL(line, 0);
 776
 777                 msg_bytes = tag & 0xFFFFFF;
 778                 tag = (tag >> 24) - MPLEX_BASE;
 779
 780                 switch (tag) {
 781                 case MSG_DATA:
 782                         if (msg_bytes > iobuf_in_siz) {
 783                                 if (!(iobuf_in = realloc_array(iobuf_in, char,
 784                                                                msg_bytes)))
 785                                         out_of_memory("readfd_unbuffered");
 786                                 iobuf_in_siz = msg_bytes;
 787                         }
 788                         read_loop(fd, iobuf_in, msg_bytes);
 789                         remaining = msg_bytes;
 790                         iobuf_in_ndx = 0;
 791                         break;
 792                 case MSG_DELETED:
 793                         if (msg_bytes >= sizeof line)
 794                                 goto overflow;
 795                         read_loop(fd, line, msg_bytes);
 796                         /* A directory name was sent with the trailing null */
 797                         if (msg_bytes > 0 && !line[msg_bytes-1])
 798                                 log_delete(line, S_IFDIR);
 799                         else {
 800                                 line[msg_bytes] = '\0';
 801                                 log_delete(line, S_IFREG);
 802                         }
 803                         break;
 804                 case MSG_SUCCESS:
 805                         if (msg_bytes != 4) {
 806                                 rprintf(FERROR, "invalid multi-message %d:%ld [%s]\n",
 807                                         tag, (long)msg_bytes, who_am_i());
 808                                 exit_cleanup(RERR_STREAMIO);
 809                         }
 810                         read_loop(fd, line, msg_bytes);
 811                         successful_send(IVAL(line, 0));
 812                         break;
 813                 case MSG_INFO:
 814                 case MSG_ERROR:
 815                         if (msg_bytes >= sizeof line) {
 816                             overflow:
 817                                 rprintf(FERROR,
 818                                         "multiplexing overflow %d:%ld [%s]\n",
 819                                         tag, (long)msg_bytes, who_am_i());
 820                                 exit_cleanup(RERR_STREAMIO);
 821                         }
 822                         read_loop(fd, line, msg_bytes);
 823                         rwrite((enum logcode)tag, line, msg_bytes);
 824                         break;
 825                 default:
 826                         rprintf(FERROR, "unexpected tag %d [%s]\n",
 827                                 tag, who_am_i());
 828                         exit_cleanup(RERR_STREAMIO);
 829                 }
 830         }
 831
 832         if (remaining == 0)
 833                 io_flush(NORMAL_FLUSH);
 834
 835         return cnt;
 836 }
 837
 838 /**
 839  * Do a buffered read from @p fd.  Don't return until all @p n bytes
 840  * have been read.  If all @p n can't be read then exit with an
 841  * error.
 842  **/
 843 static void readfd(int fd, char *buffer, size_t N)
 844 {
 845         int  cnt;
 846         size_t total = 0;
 847
 848         while (total < N) {
 849                 cnt = readfd_unbuffered(fd, buffer + total, N-total);
 850                 total += cnt;
 851         }
 852
 853         if (fd == write_batch_monitor_in) {
 854                 if ((size_t)write(batch_fd, buffer, total) != total)
 855                         exit_cleanup(RERR_FILEIO);
 856         }
 857
 858         if (fd == sock_f_in)
 859                 stats.total_read += total;
 860 }
 861
 862 int read_shortint(int f)
 863 {
 864         uchar b[2];
 865         readfd(f, (char *)b, 2);
 866         return (b[1] << 8) + b[0];
 867 }
 868
 869 int32 read_int(int f)
 870 {
 871         char b[4];
 872         int32 num;
 873
 874         readfd(f,b,4);
 875         num = IVAL(b,0);
 876         if (num == (int32)0xffffffff)
 877                 return -1;
 878         return num;
 879 }
 880
 881 int64 read_longint(int f)
 882 {
 883         int64 num;
 884         char b[8];
 885         num = read_int(f);
 886
 887         if ((int32)num != (int32)0xffffffff)
 888                 return num;
 889
 890 #if SIZEOF_INT64 < 8
 891         rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
 892         exit_cleanup(RERR_UNSUPPORTED);
 893 #else
 894         readfd(f,b,8);
 895         num = IVAL(b,0) | (((int64)IVAL(b,4))<<32);
 896 #endif
 897
 898         return num;
 899 }
 900
 901 void read_buf(int f,char *buf,size_t len)
 902 {
 903         readfd(f,buf,len);
 904 }
 905
 906 void read_sbuf(int f,char *buf,size_t len)
 907 {
 908         readfd(f, buf, len);
 909         buf[len] = '\0';
 910 }
 911
 912 uchar read_byte(int f)
 913 {
 914         uchar c;
 915         readfd(f, (char *)&c, 1);
 916         return c;
 917 }
 918
 919 int read_vstring(int f, char *buf, int bufsize)
 920 {
 921         int len = read_byte(f);
 922
 923         if (len & 0x80)
 924                 len = (len & ~0x80) * 0x100 + read_byte(f);
 925
 926         if (len >= bufsize) {
 927                 rprintf(FERROR, "over-long vstring received (%d > %d)\n",
 928                         len, bufsize - 1);
 929                 return -1;
 930         }
 931
 932         if (len)
 933                 readfd(f, buf, len);
 934         buf[len] = '\0';
 935         return len;
 936 }
 937
 938 /* Populate a sum_struct with values from the socket.  This is
 939  * called by both the sender and the receiver. */
 940 void read_sum_head(int f, struct sum_struct *sum)
 941 {
 942         sum->count = read_int(f);
 943         if (sum->count < 0) {
 944                 rprintf(FERROR, "Invalid checksum count %ld [%s]\n",
 945                         (long)sum->count, who_am_i());
 946                 exit_cleanup(RERR_PROTOCOL);
 947         }
 948         sum->blength = read_int(f);
 949         if (sum->blength < 0 || sum->blength > MAX_BLOCK_SIZE) {
 950                 rprintf(FERROR, "Invalid block length %ld [%s]\n",
 951                         (long)sum->blength, who_am_i());
 952                 exit_cleanup(RERR_PROTOCOL);
 953         }
 954         sum->s2length = protocol_version < 27 ? csum_length : (int)read_int(f);
 955         if (sum->s2length < 0 || sum->s2length > MD4_SUM_LENGTH) {
 956                 rprintf(FERROR, "Invalid checksum length %d [%s]\n",
 957                         sum->s2length, who_am_i());
 958                 exit_cleanup(RERR_PROTOCOL);
 959         }
 960         sum->remainder = read_int(f);
 961         if (sum->remainder < 0 || sum->remainder > sum->blength) {
 962                 rprintf(FERROR, "Invalid remainder length %ld [%s]\n",
 963                         (long)sum->remainder, who_am_i());
 964                 exit_cleanup(RERR_PROTOCOL);
 965         }
 966 }
 967
 968 /* Send the values from a sum_struct over the socket.  Set sum to
 969  * NULL if there are no checksums to send.  This is called by both
 970  * the generator and the sender. */
 971 void write_sum_head(int f, struct sum_struct *sum)
 972 {
 973         static struct sum_struct null_sum;
 974
 975         if (sum == NULL)
 976                 sum = &null_sum;
 977
 978         write_int(f, sum->count);
 979         write_int(f, sum->blength);
 980         if (protocol_version >= 27)
 981                 write_int(f, sum->s2length);
 982         write_int(f, sum->remainder);
 983 }
 984
 985 /**
 986  * Sleep after writing to limit I/O bandwidth usage.
 987  *
 988  * @todo Rather than sleeping after each write, it might be better to
 989  * use some kind of averaging.  The current algorithm seems to always
 990  * use a bit less bandwidth than specified, because it doesn't make up
 991  * for slow periods.  But arguably this is a feature.  In addition, we
 992  * ought to take the time used to write the data into account.
 993  *
 994  * During some phases of big transfers (file FOO is uptodate) this is
 995  * called with a small bytes_written every time.  As the kernel has to
 996  * round small waits up to guarantee that we actually wait at least the
 997  * requested number of microseconds, this can become grossly inaccurate.
 998  * We therefore keep track of the bytes we've written over time and only
 999  * sleep when the accumulated delay is at least 1 tenth of a second.
1000  **/
1001 static void sleep_for_bwlimit(int bytes_written)
1002 {
1003         static struct timeval prior_tv;
1004         static long total_written = 0;
1005         struct timeval tv, start_tv;
1006         long elapsed_usec, sleep_usec;
1007
1008 #define ONE_SEC 1000000L /* # of microseconds in a second */
1009
1010         if (!bwlimit_writemax)
1011                 return;
1012
1013         total_written += bytes_written;
1014
1015         gettimeofday(&start_tv, NULL);
1016         if (prior_tv.tv_sec) {
1017                 elapsed_usec = (start_tv.tv_sec - prior_tv.tv_sec) * ONE_SEC
1018                              + (start_tv.tv_usec - prior_tv.tv_usec);
1019                 total_written -= elapsed_usec * bwlimit / (ONE_SEC/1024);
1020                 if (total_written < 0)
1021                         total_written = 0;
1022         }
1023
1024         sleep_usec = total_written * (ONE_SEC/1024) / bwlimit;
1025         if (sleep_usec < ONE_SEC / 10) {
1026                 prior_tv = start_tv;
1027                 return;
1028         }
1029
1030         tv.tv_sec  = sleep_usec / ONE_SEC;
1031         tv.tv_usec = sleep_usec % ONE_SEC;
1032         select(0, NULL, NULL, NULL, &tv);
1033
1034         gettimeofday(&prior_tv, NULL);
1035         elapsed_usec = (prior_tv.tv_sec - start_tv.tv_sec) * ONE_SEC
1036                      + (prior_tv.tv_usec - start_tv.tv_usec);
1037         total_written = (sleep_usec - elapsed_usec) * bwlimit / (ONE_SEC/1024);
1038 }
1039
1040 /* Write len bytes to the file descriptor fd, looping as necessary to get
1041  * the job done and also (in certain circumstances) reading any data on
1042  * msg_fd_in to avoid deadlock.
1043  *
1044  * This function underlies the multiplexing system.  The body of the
1045  * application never calls this function directly. */
1046 static void writefd_unbuffered(int fd,char *buf,size_t len)
1047 {
1048         size_t n, total = 0;
1049         fd_set w_fds, r_fds;
1050         int maxfd, count, cnt, using_r_fds;
1051         int defer_save = defer_forwarding_messages;
1052         struct timeval tv;
1053
1054         no_flush++;
1055
1056         while (total < len) {
1057                 FD_ZERO(&w_fds);
1058                 FD_SET(fd,&w_fds);
1059                 maxfd = fd;
1060
1061                 if (msg_fd_in >= 0) {
1062                         FD_ZERO(&r_fds);
1063                         FD_SET(msg_fd_in,&r_fds);
1064                         if (msg_fd_in > maxfd)
1065                                 maxfd = msg_fd_in;
1066                         using_r_fds = 1;
1067                 } else
1068                         using_r_fds = 0;
1069
1070                 tv.tv_sec = select_timeout;
1071                 tv.tv_usec = 0;
1072
1073                 errno = 0;
1074                 count = select(maxfd + 1, using_r_fds ? &r_fds : NULL,
1075                                &w_fds, NULL, &tv);
1076
1077                 if (count <= 0) {
1078                         if (count < 0 && errno == EBADF)
1079                                 exit_cleanup(RERR_SOCKETIO);
1080                         check_timeout();
1081                         continue;
1082                 }
1083
1084                 if (using_r_fds && FD_ISSET(msg_fd_in, &r_fds))
1085                         read_msg_fd();
1086
1087                 if (!FD_ISSET(fd, &w_fds))
1088                         continue;
1089
1090                 n = len - total;
1091                 if (bwlimit_writemax && n > bwlimit_writemax)
1092                         n = bwlimit_writemax;
1093                 cnt = write(fd, buf + total, n);
1094
1095                 if (cnt <= 0) {
1096                         if (cnt < 0) {
1097                                 if (errno == EINTR)
1098                                         continue;
1099                                 if (errno == EWOULDBLOCK || errno == EAGAIN) {
1100                                         msleep(1);
1101                                         continue;
1102                                 }
1103                         }
1104
1105                         /* Don't try to write errors back across the stream. */
1106                         if (fd == sock_f_out)
1107                                 close_multiplexing_out();
1108                         rsyserr(FERROR, errno,
1109                                 "writefd_unbuffered failed to write %ld bytes [%s]",
1110                                 (long)len, who_am_i());
1111                         /* If the other side is sending us error messages, try
1112                          * to grab any messages they sent before they died. */
1113                         while (fd == sock_f_out && io_multiplexing_in) {
1114                                 set_io_timeout(30);
1115                                 ignore_timeout = 0;
1116                                 readfd_unbuffered(sock_f_in, io_filesfrom_buf,
1117                                                   sizeof io_filesfrom_buf);
1118                         }
1119                         exit_cleanup(RERR_STREAMIO);
1120                 }
1121
1122                 total += cnt;
1123                 defer_forwarding_messages = 1;
1124
1125                 if (fd == sock_f_out) {
1126                         if (io_timeout || am_generator)
1127                                 last_io_out = time(NULL);
1128                         sleep_for_bwlimit(cnt);
1129                 }
1130         }
1131
1132         defer_forwarding_messages = defer_save;
1133         no_flush--;
1134 }
1135
1136 static void msg2sndr_flush(void)
1137 {
1138         if (defer_forwarding_messages)
1139                 return;
1140
1141         while (msg2sndr.head && io_multiplexing_out) {
1142                 struct msg_list_item *m = msg2sndr.head;
1143                 if (!(msg2sndr.head = m->next))
1144                         msg2sndr.tail = NULL;
1145                 stats.total_written += m->len;
1146                 defer_forwarding_messages = 1;
1147                 writefd_unbuffered(sock_f_out, m->buf, m->len);
1148                 defer_forwarding_messages = 0;
1149                 free(m);
1150         }
1151 }
1152
1153 /**
1154  * Write an message to a multiplexed stream. If this fails then rsync
1155  * exits.
1156  **/
1157 static void mplex_write(enum msgcode code, char *buf, size_t len)
1158 {
1159         char buffer[1024];
1160         size_t n = len;
1161
1162         SIVAL(buffer, 0, ((MPLEX_BASE + (int)code)<<24) + len);
1163
1164         if (n > sizeof buffer - 4)
1165                 n = 0;
1166         else
1167                 memcpy(buffer + 4, buf, n);
1168
1169         writefd_unbuffered(sock_f_out, buffer, n+4);
1170
1171         len -= n;
1172         buf += n;
1173
1174         if (len) {
1175                 defer_forwarding_messages = 1;
1176                 writefd_unbuffered(sock_f_out, buf, len);
1177                 defer_forwarding_messages = 0;
1178                 msg2sndr_flush();
1179         }
1180 }
1181
1182 void io_flush(int flush_it_all)
1183 {
1184         msg2genr_flush(flush_it_all);
1185         msg2sndr_flush();
1186
1187         if (!iobuf_out_cnt || no_flush)
1188                 return;
1189
1190         if (io_multiplexing_out)
1191                 mplex_write(MSG_DATA, iobuf_out, iobuf_out_cnt);
1192         else
1193                 writefd_unbuffered(sock_f_out, iobuf_out, iobuf_out_cnt);
1194         iobuf_out_cnt = 0;
1195 }
1196
1197 static void writefd(int fd,char *buf,size_t len)
1198 {
1199         if (fd == msg_fd_out) {
1200                 rprintf(FERROR, "Internal error: wrong write used in receiver.\n");
1201                 exit_cleanup(RERR_PROTOCOL);
1202         }
1203
1204         if (fd == sock_f_out)
1205                 stats.total_written += len;
1206
1207         if (fd == write_batch_monitor_out) {
1208                 if ((size_t)write(batch_fd, buf, len) != len)
1209                         exit_cleanup(RERR_FILEIO);
1210         }
1211
1212         if (!iobuf_out || fd != sock_f_out) {
1213                 writefd_unbuffered(fd, buf, len);
1214                 return;
1215         }
1216
1217         while (len) {
1218                 int n = MIN((int)len, IO_BUFFER_SIZE - iobuf_out_cnt);
1219                 if (n > 0) {
1220                         memcpy(iobuf_out+iobuf_out_cnt, buf, n);
1221                         buf += n;
1222                         len -= n;
1223                         iobuf_out_cnt += n;
1224                 }
1225
1226                 if (iobuf_out_cnt == IO_BUFFER_SIZE)
1227                         io_flush(NORMAL_FLUSH);
1228         }
1229 }
1230
1231 void write_shortint(int f, int x)
1232 {
1233         uchar b[2];
1234         b[0] = x;
1235         b[1] = x >> 8;
1236         writefd(f, (char *)b, 2);
1237 }
1238
1239 void write_int(int f,int32 x)
1240 {
1241         char b[4];
1242         SIVAL(b,0,x);
1243         writefd(f,b,4);
1244 }
1245
1246 /*
1247  * Note: int64 may actually be a 32-bit type if ./configure couldn't find any
1248  * 64-bit types on this platform.
1249  */
1250 void write_longint(int f, int64 x)
1251 {
1252         char b[8];
1253
1254         if (x <= 0x7FFFFFFF) {
1255                 write_int(f, (int)x);
1256                 return;
1257         }
1258
1259 #if SIZEOF_INT64 < 8
1260         rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
1261         exit_cleanup(RERR_UNSUPPORTED);
1262 #else
1263         write_int(f, (int32)0xFFFFFFFF);
1264         SIVAL(b,0,(x&0xFFFFFFFF));
1265         SIVAL(b,4,((x>>32)&0xFFFFFFFF));
1266
1267         writefd(f,b,8);
1268 #endif
1269 }
1270
1271 void write_buf(int f,char *buf,size_t len)
1272 {
1273         writefd(f,buf,len);
1274 }
1275
1276 /** Write a string to the connection */
1277 void write_sbuf(int f, char *buf)
1278 {
1279         writefd(f, buf, strlen(buf));
1280 }
1281
1282 void write_byte(int f, uchar c)
1283 {
1284         writefd(f, (char *)&c, 1);
1285 }
1286
1287 void write_vstring(int f, char *str, int len)
1288 {
1289         uchar lenbuf[3], *lb = lenbuf;
1290
1291         if (len > 0x7F) {
1292                 if (len > 0x7FFF) {
1293                         rprintf(FERROR,
1294                                 "attempting to send over-long vstring (%d > %d)\n",
1295                                 len, 0x7FFF);
1296                         exit_cleanup(RERR_PROTOCOL);
1297                 }
1298                 *lb++ = len / 0x100 + 0x80;
1299         }
1300         *lb = len;
1301
1302         writefd(f, (char*)lenbuf, lb - lenbuf + 1);
1303         if (len)
1304                 writefd(f, str, len);
1305 }
1306
1307 /**
1308  * Read a line of up to @p maxlen characters into @p buf (not counting
1309  * the trailing null).  Strips the (required) trailing newline and all
1310  * carriage returns.
1311  *
1312  * @return 1 for success; 0 for I/O error or truncation.
1313  **/
1314 int read_line(int f, char *buf, size_t maxlen)
1315 {
1316         while (maxlen) {
1317                 buf[0] = 0;
1318                 read_buf(f, buf, 1);
1319                 if (buf[0] == 0)
1320                         return 0;
1321                 if (buf[0] == '\n')
1322                         break;
1323                 if (buf[0] != '\r') {
1324                         buf++;
1325                         maxlen--;
1326                 }
1327         }
1328         *buf = '\0';
1329         return maxlen > 0;
1330 }
1331
1332 void io_printf(int fd, const char *format, ...)
1333 {
1334         va_list ap;
1335         char buf[BIGPATHBUFLEN];
1336         int len;
1337
1338         va_start(ap, format);
1339         len = vsnprintf(buf, sizeof buf, format, ap);
1340         va_end(ap);
1341
1342         if (len < 0)
1343                 exit_cleanup(RERR_STREAMIO);
1344
1345         if (len > (int)sizeof buf) {
1346                 rprintf(FERROR, "io_printf() was too long for the buffer.\n");
1347                 exit_cleanup(RERR_STREAMIO);
1348         }
1349
1350         write_sbuf(fd, buf);
1351 }
1352
1353 /** Setup for multiplexing a MSG_* stream with the data stream. */
1354 void io_start_multiplex_out(void)
1355 {
1356         io_flush(NORMAL_FLUSH);
1357         io_start_buffering_out();
1358         io_multiplexing_out = 1;
1359 }
1360
1361 /** Setup for multiplexing a MSG_* stream with the data stream. */
1362 void io_start_multiplex_in(void)
1363 {
1364         io_flush(NORMAL_FLUSH);
1365         io_start_buffering_in();
1366         io_multiplexing_in = 1;
1367 }
1368
1369 /** Write an message to the multiplexed data stream. */
1370 int io_multiplex_write(enum msgcode code, char *buf, size_t len)
1371 {
1372         if (!io_multiplexing_out)
1373                 return 0;
1374
1375         io_flush(NORMAL_FLUSH);
1376         stats.total_written += (len+4);
1377         mplex_write(code, buf, len);
1378         return 1;
1379 }
1380
1381 void close_multiplexing_in(void)
1382 {
1383         io_multiplexing_in = 0;
1384 }
1385
1386 /** Stop output multiplexing. */
1387 void close_multiplexing_out(void)
1388 {
1389         io_multiplexing_out = 0;
1390 }
1391
1392 void start_write_batch(int fd)
1393 {
1394         write_stream_flags(batch_fd);
1395
1396         /* Some communication has already taken place, but we don't
1397          * enable batch writing until here so that we can write a
1398          * canonical record of the communication even though the
1399          * actual communication so far depends on whether a daemon
1400          * is involved. */
1401         write_int(batch_fd, protocol_version);
1402         write_int(batch_fd, checksum_seed);
1403
1404         if (am_sender)
1405                 write_batch_monitor_out = fd;
1406         else
1407                 write_batch_monitor_in = fd;
1408 }
1409
1410 void stop_write_batch(void)
1411 {
1412         write_batch_monitor_out = -1;
1413         write_batch_monitor_in = -1;
1414 }