X-Git-Url: http://git.samba.org/samba.git/?p=rsync.git;a=blobdiff_plain;f=io.c;h=fdaa71345ae07166087d8302de3a9f7a5b206b8d;hp=bf7f3d90bd839baa4529a48d85aac4c7e6112dc8;hb=c4d1b2983d9bc73c107f203a1331a4014d74405a;hpb=3309507dd3fc581254aa642509ee0671f5b79883

diff --git a/io.c b/io.c
index bf7f3d90..fdaa7134 100644
--- a/io.c
+++ b/io.c
@@ -1,19 +1,19 @@
 /* -*- c-file-style: "linux" -*-
- * 
- * Copyright (C) 1996-2001 by Andrew Tridgell 
+ *
+ * Copyright (C) 1996-2001 by Andrew Tridgell
  * Copyright (C) Paul Mackerras 1996
  * Copyright (C) 2001, 2002 by Martin Pool <mbp@samba.org>
- * 
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
- * 
+ *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
@@ -22,7 +22,7 @@
 /**
  * @file io.c
  *
- * Socket and pipe IO utilities used in rsync.
+ * Socket and pipe I/O utilities used in rsync.
  *
  * rsync provides its own multiplexing system, which is used to send
  * stderr and stdout over a single socket.  We need this because
@@ -39,20 +39,30 @@
 /** If no timeout is specified then use a 60 second select timeout */
 #define SELECT_TIMEOUT 60
 
-static int io_multiplexing_out;
-static int io_multiplexing_in;
-static int multiplex_in_fd = -1;
-static int multiplex_out_fd = -1;
-static time_t last_io;
-static int no_flush;
-
 extern int bwlimit;
+extern size_t bwlimit_writemax;
 extern int verbose;
 extern int io_timeout;
+extern int allowed_lull;
+extern int am_server;
+extern int am_daemon;
+extern int am_sender;
+extern int am_generator;
+extern int eol_nulls;
+extern int csum_length;
+extern int checksum_seed;
+extern int protocol_version;
+extern int remove_sent_files;
+extern int preserve_hard_links;
+extern char *filesfrom_host;
 extern struct stats stats;
-
+extern struct file_list *the_file_list;
 
 const char phase_unknown[] = "unknown";
+int select_timeout = SELECT_TIMEOUT;
+int ignore_timeout = 0;
+int batch_fd = -1;
+int batch_gen_fd = -1;
 
 /**
  * The connection might be dropped at some point; perhaps because the
@@ -60,9 +70,9 @@ const char phase_unknown[] = "unknown";
  * not very helpful.  So instead we try to make io_phase_name point to
  * something useful.
  *
- * For buffered/multiplexed IO these names will be somewhat
+ * For buffered/multiplexed I/O these names will be somewhat
  * approximate; perhaps for ease of support we would rather make the
- * buffer always flush when a single application-level IO finishes.
+ * buffer always flush when a single application-level I/O finishes.
  *
  * @todo Perhaps we want some simple stack functionality, but there's
  * no need to overdo it.
@@ -70,29 +80,91 @@ const char phase_unknown[] = "unknown";
 const char *io_write_phase = phase_unknown;
 const char *io_read_phase = phase_unknown;
 
-/** Ignore EOF errors while reading a module listing if the remote
-    version is 24 or less. */
-int kludge_around_eof = False;
+/* Ignore an EOF error if non-zero. See whine_about_eof(). */
+int kluge_around_eof = 0;
+
+int msg_fd_in = -1;
+int msg_fd_out = -1;
+int sock_f_in = -1;
+int sock_f_out = -1;
+
+static int io_multiplexing_out;
+static int io_multiplexing_in;
+static time_t last_io;
+static int no_flush;
 
+static int write_batch_monitor_in = -1;
+static int write_batch_monitor_out = -1;
 
-static int io_error_fd = -1;
 static int io_filesfrom_f_in = -1;
 static int io_filesfrom_f_out = -1;
 static char io_filesfrom_buf[2048];
 static char *io_filesfrom_bp;
 static char io_filesfrom_lastchar;
 static int io_filesfrom_buflen;
+static size_t contiguous_write_len = 0;
 
 static void read_loop(int fd, char *buf, size_t len);
 
+struct flist_ndx_item {
+	struct flist_ndx_item *next;
+	int ndx;
+};
+
+struct flist_ndx_list {
+	struct flist_ndx_item *head, *tail;
+};
+
+static struct flist_ndx_list redo_list, hlink_list;
+
+struct msg_list {
+	struct msg_list *next;
+	char *buf;
+	int len;
+};
+
+static struct msg_list *msg_list_head;
+static struct msg_list *msg_list_tail;
+
+static void flist_ndx_push(struct flist_ndx_list *lp, int ndx)
+{
+	struct flist_ndx_item *item;
+
+	if (!(item = new(struct flist_ndx_item)))
+		out_of_memory("flist_ndx_push");
+	item->next = NULL;
+	item->ndx = ndx;
+	if (lp->tail)
+		lp->tail->next = item;
+	else
+		lp->head = item;
+	lp->tail = item;
+}
+
+static int flist_ndx_pop(struct flist_ndx_list *lp)
+{
+	struct flist_ndx_item *next;
+	int ndx;
+
+	if (!lp->head)
+		return -1;
+
+	ndx = lp->head->ndx;
+	next = lp->head->next;
+	free(lp->head);
+	lp->head = next;
+	if (!next)
+		lp->tail = NULL;
+
+	return ndx;
+}
+
 static void check_timeout(void)
 {
-	extern int am_server, am_daemon;
 	time_t t;
 
-	err_list_push();
-
-	if (!io_timeout) return;
+	if (!io_timeout || ignore_timeout)
+		return;
 
 	if (!last_io) {
 		last_io = time(NULL);
@@ -101,50 +173,202 @@ static void check_timeout(void)
 
 	t = time(NULL);
 
-	if (last_io && io_timeout && (t-last_io) >= io_timeout) {
+	if (t - last_io >= io_timeout) {
 		if (!am_server && !am_daemon) {
-			rprintf(FERROR,"io timeout after %d seconds - exiting\n", 
+			rprintf(FERROR, "io timeout after %d seconds -- exiting\n",
 				(int)(t-last_io));
 		}
 		exit_cleanup(RERR_TIMEOUT);
 	}
 }
 
-/** Setup the fd used to propagate errors */
-void io_set_error_fd(int fd)
+/* Note the fds used for the main socket (which might really be a pipe
+ * for a local transfer, but we can ignore that). */
+void io_set_sock_fds(int f_in, int f_out)
 {
-	io_error_fd = fd;
+	sock_f_in = f_in;
+	sock_f_out = f_out;
 }
 
-/** Read some data from the error fd and write it to the write log code */
-static void read_error_fd(void)
+/* Setup the fd used to receive MSG_* messages.  Only needed during the
+ * early stages of being a local sender (up through the sending of the
+ * file list) or when we're the generator (to fetch the messages from
+ * the receiver). */
+void set_msg_fd_in(int fd)
 {
-	char buf[200];
+	msg_fd_in = fd;
+}
+
+/* Setup the fd used to send our MSG_* messages.  Only needed when
+ * we're the receiver (to send our messages to the generator). */
+void set_msg_fd_out(int fd)
+{
+	msg_fd_out = fd;
+	set_nonblocking(msg_fd_out);
+}
+
+/* Add a message to the pending MSG_* list. */
+static void msg_list_add(int code, char *buf, int len)
+{
+	struct msg_list *ml;
+
+	if (!(ml = new(struct msg_list)))
+		out_of_memory("msg_list_add");
+	ml->next = NULL;
+	if (!(ml->buf = new_array(char, len+4)))
+		out_of_memory("msg_list_add");
+	SIVAL(ml->buf, 0, ((code+MPLEX_BASE)<<24) | len);
+	memcpy(ml->buf+4, buf, len);
+	ml->len = len+4;
+	if (msg_list_tail)
+		msg_list_tail->next = ml;
+	else
+		msg_list_head = ml;
+	msg_list_tail = ml;
+}
+
+void send_msg(enum msgcode code, char *buf, int len)
+{
+	if (msg_fd_out < 0) {
+		io_multiplex_write(code, buf, len);
+		return;
+	}
+	msg_list_add(code, buf, len);
+	msg_list_push(NORMAL_FLUSH);
+}
+
+/* Read a message from the MSG_* fd and handle it.  This is called either
+ * during the early stages of being a local sender (up through the sending
+ * of the file list) or when we're the generator (to fetch the messages
+ * from the receiver). */
+static void read_msg_fd(void)
+{
+	char buf[2048];
 	size_t n;
-	int fd = io_error_fd;
+	int fd = msg_fd_in;
 	int tag, len;
 
-	/* io_error_fd is temporarily disabled -- is this meant to
-	 * prevent indefinite recursion? */
-	io_error_fd = -1;
+	/* Temporarily disable msg_fd_in.  This is needed to avoid looping back
+	 * to this routine from writefd_unbuffered(). */
+	msg_fd_in = -1;
 
 	read_loop(fd, buf, 4);
 	tag = IVAL(buf, 0);
 
 	len = tag & 0xFFFFFF;
-	tag = tag >> 24;
-	tag -= MPLEX_BASE;
+	tag = (tag >> 24) - MPLEX_BASE;
 
-	while (len) {
-		n = len;
-		if (n > (sizeof buf - 1))
-			n = sizeof buf - 1;
-		read_loop(fd, buf, n);
-		rwrite((enum logcode)tag, buf, n);
-		len -= n;
+	switch (tag) {
+	case MSG_DONE:
+		if (len != 0 || !am_generator) {
+			rprintf(FERROR, "invalid message %d:%d\n", tag, len);
+			exit_cleanup(RERR_STREAMIO);
+		}
+		flist_ndx_push(&redo_list, -1);
+		break;
+	case MSG_REDO:
+		if (len != 4 || !am_generator) {
+			rprintf(FERROR, "invalid message %d:%d\n", tag, len);
+			exit_cleanup(RERR_STREAMIO);
+		}
+		read_loop(fd, buf, 4);
+		flist_ndx_push(&redo_list, IVAL(buf,0));
+		break;
+	case MSG_DELETED:
+		if (len >= (int)sizeof buf || !am_generator) {
+			rprintf(FERROR, "invalid message %d:%d\n", tag, len);
+			exit_cleanup(RERR_STREAMIO);
+		}
+		read_loop(fd, buf, len);
+		io_multiplex_write(MSG_DELETED, buf, len);
+		break;
+	case MSG_SUCCESS:
+		if (len != 4 || !am_generator) {
+			rprintf(FERROR, "invalid message %d:%d\n", tag, len);
+			exit_cleanup(RERR_STREAMIO);
+		}
+		read_loop(fd, buf, len);
+		if (remove_sent_files)
+			io_multiplex_write(MSG_SUCCESS, buf, len);
+		if (preserve_hard_links)
+			flist_ndx_push(&hlink_list, IVAL(buf,0));
+		break;
+	case MSG_INFO:
+	case MSG_ERROR:
+	case MSG_LOG:
+		while (len) {
+			n = len;
+			if (n >= sizeof buf)
+				n = sizeof buf - 1;
+			read_loop(fd, buf, n);
+			rwrite((enum logcode)tag, buf, n);
+			len -= n;
+		}
+		break;
+	default:
+		rprintf(FERROR, "unknown message %d:%d\n", tag, len);
+		exit_cleanup(RERR_STREAMIO);
+	}
+
+	msg_fd_in = fd;
+}
+
+/* Try to push messages off the list onto the wire.  If we leave with more
+ * to do, return 0.  On error, return -1.  If everything flushed, return 1.
+ * This is only active in the receiver. */
+int msg_list_push(int flush_it_all)
+{
+	static int written = 0;
+	struct timeval tv;
+	fd_set fds;
+
+	if (msg_fd_out < 0)
+		return -1;
+
+	while (msg_list_head) {
+		struct msg_list *ml = msg_list_head;
+		int n = write(msg_fd_out, ml->buf + written, ml->len - written);
+		if (n < 0) {
+			if (errno == EINTR)
+				continue;
+			if (errno != EWOULDBLOCK && errno != EAGAIN)
+				return -1;
+			if (!flush_it_all)
+				return 0;
+			FD_ZERO(&fds);
+			FD_SET(msg_fd_out, &fds);
+			tv.tv_sec = select_timeout;
+			tv.tv_usec = 0;
+			if (!select(msg_fd_out+1, NULL, &fds, NULL, &tv))
+				check_timeout();
+		} else if ((written += n) == ml->len) {
+			free(ml->buf);
+			msg_list_head = ml->next;
+			if (!msg_list_head)
+				msg_list_tail = NULL;
+			free(ml);
+			written = 0;
+		}
 	}
+	return 1;
+}
 
-	io_error_fd = fd;
+int get_redo_num(int itemizing, enum logcode code)
+{
+	while (1) {
+		if (hlink_list.head)
+			check_for_finished_hlinks(itemizing, code);
+		if (redo_list.head)
+			break;
+		read_msg_fd();
+	}
+
+	return flist_ndx_pop(&redo_list);
+}
+
+int get_hlink_num(void)
+{
+	return flist_ndx_pop(&hlink_list);
 }
 
 /**
@@ -166,44 +390,39 @@ void io_set_filesfrom_fds(int f_in, int f_out)
 	io_filesfrom_buflen = 0;
 }
 
-/**
- * It's almost always an error to get an EOF when we're trying to read
- * from the network, because the protocol is self-terminating.
+/* It's almost always an error to get an EOF when we're trying to read from the
+ * network, because the protocol is (for the most part) self-terminating.
  *
- * However, there is one unfortunate cases where it is not, which is
- * rsync <2.4.6 sending a list of modules on a server, since the list
- * is terminated by closing the socket. So, for the section of the
- * program where that is a problem (start_socket_client),
- * kludge_around_eof is True and we just exit.
- */
-static void whine_about_eof(void)
+ * There is one case for the receiver when it is at the end of the transfer
+ * (hanging around reading any keep-alive packets that might come its way): if
+ * the sender dies before the generator's kill-signal comes through, we can end
+ * up here needing to loop until the kill-signal arrives.  In this situation,
+ * kluge_around_eof will be < 0.
+ *
+ * There is another case for older protocol versions (< 24) where the module
+ * listing was not terminated, so we must ignore an EOF error in that case and
+ * exit.  In this situation, kluge_around_eof will be > 0. */
+static void whine_about_eof(int fd)
 {
-	if (kludge_around_eof)
-		exit_cleanup(0);
-	else {
-		rprintf(FERROR,
-			"%s: connection unexpectedly closed "
-			"(%.0f bytes read so far)\n",
-			RSYNC_NAME, (double)stats.total_read);
-
-		exit_cleanup(RERR_STREAMIO);
+	if (kluge_around_eof && fd == sock_f_in) {
+		int i;
+		if (kluge_around_eof > 0)
+			exit_cleanup(0);
+		/* If we're still here after 10 seconds, exit with an error. */
+		for (i = 10*1000/20; i--; )
+			msleep(20);
 	}
-}
 
+	rprintf(FERROR, RSYNC_NAME ": connection unexpectedly closed "
+		"(%.0f bytes received so far) [%s]\n",
+		(double)stats.total_read, who_am_i());
 
-static void die_from_readerr(int err)
-{
-	/* this prevents us trying to write errors on a dead socket */
-	io_multiplexing_close();
-
-	rprintf(FERROR, "%s: read error: %s\n",
-		RSYNC_NAME, strerror(err));
 	exit_cleanup(RERR_STREAMIO);
 }
 
 
 /**
- * Read from a socket with IO timeout. return the number of bytes
+ * Read from a socket with I/O timeout. return the number of bytes
  * read. If no bytes can be read then exit, never return a number <= 0.
  *
  * TODO: If the remote shell connection fails, then current versions
@@ -215,22 +434,24 @@ static void die_from_readerr(int err)
  */
 static int read_timeout(int fd, char *buf, size_t len)
 {
-	int n, ret=0;
+	int n, ret = 0;
 
-	io_flush();
+	io_flush(NORMAL_FLUSH);
 
 	while (ret == 0) {
 		/* until we manage to read *something* */
 		fd_set r_fds, w_fds;
 		struct timeval tv;
-		int fd_count = fd+1;
+		int maxfd = fd;
 		int count;
 
 		FD_ZERO(&r_fds);
+		FD_ZERO(&w_fds);
 		FD_SET(fd, &r_fds);
-		if (io_error_fd >= 0) {
-			FD_SET(io_error_fd, &r_fds);
-			if (io_error_fd >= fd_count) fd_count = io_error_fd+1;
+		if (msg_list_head) {
+			FD_SET(msg_fd_out, &w_fds);
+			if (msg_fd_out > maxfd)
+				maxfd = msg_fd_out;
 		}
 		if (io_filesfrom_f_out >= 0) {
 			int new_fd;
@@ -243,36 +464,29 @@ static int read_timeout(int fd, char *buf, size_t len)
 					new_fd = -1;
 				}
 			} else {
-				FD_ZERO(&w_fds);
 				FD_SET(io_filesfrom_f_out, &w_fds);
 				new_fd = io_filesfrom_f_out;
 			}
-			if (new_fd >= fd_count) fd_count = new_fd+1;
+			if (new_fd > maxfd)
+				maxfd = new_fd;
 		}
 
-		tv.tv_sec = io_timeout?io_timeout:SELECT_TIMEOUT;
+		tv.tv_sec = select_timeout;
 		tv.tv_usec = 0;
 
 		errno = 0;
 
-		count = select(fd_count, &r_fds,
-			       io_filesfrom_buflen? &w_fds : NULL,
-			       NULL, &tv);
-
-		if (count == 0) {
-			check_timeout();
-		}
+		count = select(maxfd + 1, &r_fds, &w_fds, NULL, &tv);
 
 		if (count <= 0) {
-			if (errno == EBADF) {
+			if (errno == EBADF)
 				exit_cleanup(RERR_SOCKETIO);
-			}
+			check_timeout();
 			continue;
 		}
 
-		if (io_error_fd >= 0 && FD_ISSET(io_error_fd, &r_fds)) {
-			read_error_fd();
-		}
+		if (msg_list_head && FD_ISSET(msg_fd_out, &w_fds))
+			msg_list_push(NORMAL_FLUSH);
 
 		if (io_filesfrom_f_out >= 0) {
 			if (io_filesfrom_buflen) {
@@ -302,7 +516,6 @@ static int read_timeout(int fd, char *buf, size_t len)
 						io_filesfrom_buflen = io_filesfrom_lastchar? 2 : 1;
 						io_filesfrom_f_in = -1;
 					} else {
-						extern int eol_nulls;
 						if (!eol_nulls) {
 							char *s = io_filesfrom_buf + l;
 							/* Transform CR and/or LF into '\0' */
@@ -338,26 +551,31 @@ static int read_timeout(int fd, char *buf, size_t len)
 			}
 		}
 
-		if (!FD_ISSET(fd, &r_fds)) continue;
+		if (!FD_ISSET(fd, &r_fds))
+			continue;
 
 		n = read(fd, buf, len);
 
-		if (n > 0) {
-			buf += n;
-			len -= n;
-			ret += n;
-			if (io_timeout)
-				last_io = time(NULL);
-			continue;
-		} else if (n == 0) {
-			whine_about_eof();
-			return -1; /* doesn't return */
-		} else if (n < 0) {
-			if (errno == EINTR || errno == EWOULDBLOCK ||
-			    errno == EAGAIN) 
+		if (n <= 0) {
+			if (n == 0)
+				whine_about_eof(fd); /* Doesn't return. */
+			if (errno == EINTR || errno == EWOULDBLOCK
+			    || errno == EAGAIN)
 				continue;
-			die_from_readerr(errno);
+
+			/* Don't write errors on a dead socket. */
+			if (fd == sock_f_in)
+				close_multiplexing_out();
+			rsyserr(FERROR, errno, "read error");
+			exit_cleanup(RERR_STREAMIO);
 		}
+
+		buf += n;
+		len -= n;
+		ret += n;
+
+		if (fd == sock_f_in && (io_timeout || am_generator))
+			last_io = time(NULL);
 	}
 
 	return ret;
@@ -371,10 +589,7 @@ int read_filesfrom_line(int fd, char *fname)
 {
 	char ch, *s, *eob = fname + MAXPATHLEN - 1;
 	int cnt;
-	extern int io_timeout;
-	extern int eol_nulls;
-	extern char *remote_filesfrom_file;
-	int reading_remotely = remote_filesfrom_file != NULL;
+	int reading_remotely = filesfrom_host != NULL;
 	int nulls = eol_nulls || reading_remotely;
 
   start:
@@ -387,7 +602,7 @@ int read_filesfrom_line(int fd, char *fname)
 			fd_set fds;
 			FD_ZERO(&fds);
 			FD_SET(fd, &fds);
-			tv.tv_sec = io_timeout? io_timeout : SELECT_TIMEOUT;
+			tv.tv_sec = select_timeout;
 			tv.tv_usec = 0;
 			if (!select(fd+1, &fds, NULL, NULL, &tv))
 				check_timeout();
@@ -414,6 +629,64 @@ int read_filesfrom_line(int fd, char *fname)
 }
 
 
+static char *iobuf_out;
+static int iobuf_out_cnt;
+
+void io_start_buffering_out(void)
+{
+	if (iobuf_out)
+		return;
+	if (!(iobuf_out = new_array(char, IO_BUFFER_SIZE)))
+		out_of_memory("io_start_buffering_out");
+	iobuf_out_cnt = 0;
+}
+
+
+static char *iobuf_in;
+static size_t iobuf_in_siz;
+
+void io_start_buffering_in(void)
+{
+	if (iobuf_in)
+		return;
+	iobuf_in_siz = 2 * IO_BUFFER_SIZE;
+	if (!(iobuf_in = new_array(char, iobuf_in_siz)))
+		out_of_memory("io_start_buffering_in");
+}
+
+
+void io_end_buffering(void)
+{
+	io_flush(NORMAL_FLUSH);
+	if (!io_multiplexing_out) {
+		free(iobuf_out);
+		iobuf_out = NULL;
+	}
+}
+
+
+void maybe_flush_socket(void)
+{
+	if (iobuf_out && iobuf_out_cnt && time(NULL) - last_io >= 5)
+		io_flush(NORMAL_FLUSH);
+}
+
+
+void maybe_send_keepalive(void)
+{
+	if (time(NULL) - last_io >= allowed_lull) {
+		if (!iobuf_out || !iobuf_out_cnt) {
+			if (protocol_version < 29)
+				return; /* there's nothing we can do */
+			write_int(sock_f_out, the_file_list->count);
+			write_shortint(sock_f_out, ITEM_IS_NEW);
+		}
+		if (iobuf_out)
+			io_flush(NORMAL_FLUSH);
+	}
+}
+
+
 /**
  * Continue trying to read len bytes - don't return until len has been
  * read.
@@ -432,36 +705,33 @@ static void read_loop(int fd, char *buf, size_t len)
 /**
  * Read from the file descriptor handling multiplexing - return number
  * of bytes read.
- * 
- * Never returns <= 0. 
+ *
+ * Never returns <= 0.
  */
-static int read_unbuffered(int fd, char *buf, size_t len)
+static int readfd_unbuffered(int fd, char *buf, size_t len)
 {
 	static size_t remaining;
+	static size_t iobuf_in_ndx;
 	int tag, ret = 0;
-	char line[1024];
-	static char *buffer;
-	static size_t bufferIdx = 0;
-	static size_t bufferSz;
+#if MAXPATHLEN < 4096
+	char line[4096+1024];
+#else
+	char line[MAXPATHLEN+1024];
+#endif
 
-	if (fd != multiplex_in_fd)
+	if (!iobuf_in || fd != sock_f_in)
 		return read_timeout(fd, buf, len);
 
 	if (!io_multiplexing_in && remaining == 0) {
-		if (!buffer) {
-			bufferSz = 2 * IO_BUFFER_SIZE;
-			buffer   = new_array(char, bufferSz);
-			if (!buffer) out_of_memory("read_unbuffered");
-		}
-		remaining = read_timeout(fd, buffer, bufferSz);
-		bufferIdx = 0;
+		remaining = read_timeout(fd, iobuf_in, iobuf_in_siz);
+		iobuf_in_ndx = 0;
 	}
 
 	while (ret == 0) {
 		if (remaining) {
 			len = MIN(len, remaining);
-			memcpy(buf, buffer + bufferIdx, len);
-			bufferIdx += len;
+			memcpy(buf, iobuf_in + iobuf_in_ndx, len);
+			iobuf_in_ndx += len;
 			remaining -= len;
 			ret = len;
 			break;
@@ -471,41 +741,65 @@ static int read_unbuffered(int fd, char *buf, size_t len)
 		tag = IVAL(line, 0);
 
 		remaining = tag & 0xFFFFFF;
-		tag = tag >> 24;
-
-		if (tag == MPLEX_BASE) {
-			if (!buffer || remaining > bufferSz) {
-				buffer = realloc_array(buffer, char, remaining);
-				if (!buffer) out_of_memory("read_unbuffered");
-				bufferSz = remaining;
+		tag = (tag >> 24) - MPLEX_BASE;
+
+		switch (tag) {
+		case MSG_DATA:
+			if (remaining > iobuf_in_siz) {
+				if (!(iobuf_in = realloc_array(iobuf_in, char,
+							       remaining)))
+					out_of_memory("readfd_unbuffered");
+				iobuf_in_siz = remaining;
 			}
-			read_loop(fd, buffer, remaining);
-			bufferIdx = 0;
-			continue;
-		}
-
-		tag -= MPLEX_BASE;
-
-		if (tag != FERROR && tag != FINFO) {
-			rprintf(FERROR, "unexpected tag %d\n", tag);
-			exit_cleanup(RERR_STREAMIO);
-		}
-
-		if (remaining > sizeof line - 1) {
-			rprintf(FERROR, "multiplexing overflow %ld\n\n",
-				(long)remaining);
+			read_loop(fd, iobuf_in, remaining);
+			iobuf_in_ndx = 0;
+			break;
+		case MSG_DELETED:
+			if (remaining >= sizeof line) {
+				rprintf(FERROR, "invalid multi-message %d:%ld\n",
+					tag, (long)remaining);
+				exit_cleanup(RERR_STREAMIO);
+			}
+			read_loop(fd, line, remaining);
+			line[remaining] = '\0';
+			/* A directory name was sent with the trailing null */
+			if (remaining > 0 && !line[remaining-1])
+				log_delete(line, S_IFDIR);
+			else
+				log_delete(line, S_IFREG);
+			remaining = 0;
+			break;
+		case MSG_SUCCESS:
+			if (remaining != 4) {
+				rprintf(FERROR, "invalid multi-message %d:%ld [%s]\n",
+					tag, (long)remaining, who_am_i());
+				exit_cleanup(RERR_STREAMIO);
+			}
+			read_loop(fd, line, remaining);
+			successful_send(IVAL(line, 0));
+			remaining = 0;
+			break;
+		case MSG_INFO:
+		case MSG_ERROR:
+			if (remaining >= sizeof line) {
+				rprintf(FERROR,
+					"multiplexing overflow %d:%ld [%s]\n",
+					tag, (long)remaining, who_am_i());
+				exit_cleanup(RERR_STREAMIO);
+			}
+			read_loop(fd, line, remaining);
+			rwrite((enum logcode)tag, line, remaining);
+			remaining = 0;
+			break;
+		default:
+			rprintf(FERROR, "unexpected tag %d [%s]\n",
+				tag, who_am_i());
 			exit_cleanup(RERR_STREAMIO);
 		}
-
-		read_loop(fd, line, remaining);
-		line[remaining] = 0;
-
-		rprintf((enum logcode) tag, "%s", line);
-		remaining = 0;
 	}
 
 	if (remaining == 0)
-		io_flush();
+		io_flush(NORMAL_FLUSH);
 
 	return ret;
 }
@@ -520,14 +814,28 @@ static int read_unbuffered(int fd, char *buf, size_t len)
 static void readfd(int fd, char *buffer, size_t N)
 {
 	int  ret;
-	size_t total=0;  
+	size_t total = 0;
 
 	while (total < N) {
-		ret = read_unbuffered(fd, buffer + total, N-total);
+		ret = readfd_unbuffered(fd, buffer + total, N-total);
 		total += ret;
 	}
 
-	stats.total_read += total;
+	if (fd == write_batch_monitor_in) {
+		if ((size_t)write(batch_fd, buffer, total) != total)
+			exit_cleanup(RERR_FILEIO);
+	}
+
+	if (fd == sock_f_in)
+		stats.total_read += total;
+}
+
+
+int read_shortint(int f)
+{
+	uchar b[2];
+	readfd(f, (char *)b, 2);
+	return (b[1] << 8) + b[0];
 }
 
 
@@ -538,7 +846,8 @@ int32 read_int(int f)
 
 	readfd(f,b,4);
 	ret = IVAL(b,0);
-	if (ret == (int32)0xffffffff) return -1;
+	if (ret == (int32)0xffffffff)
+		return -1;
 	return ret;
 }
 
@@ -548,12 +857,11 @@ int64 read_longint(int f)
 	char b[8];
 	ret = read_int(f);
 
-	if ((int32)ret != (int32)0xffffffff) {
+	if ((int32)ret != (int32)0xffffffff)
 		return ret;
-	}
 
-#ifdef NO_INT64
-	rprintf(FERROR,"Integer overflow - attempted 64 bit offset\n");
+#if SIZEOF_INT64 < 8
+	rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
 	exit_cleanup(RERR_UNSUPPORTED);
 #else
 	readfd(f,b,8);
@@ -570,17 +878,78 @@ void read_buf(int f,char *buf,size_t len)
 
 void read_sbuf(int f,char *buf,size_t len)
 {
-	read_buf(f,buf,len);
-	buf[len] = 0;
+	readfd(f, buf, len);
+	buf[len] = '\0';
 }
 
-unsigned char read_byte(int f)
+uchar read_byte(int f)
 {
-	unsigned char c;
-	read_buf(f, (char *)&c, 1);
+	uchar c;
+	readfd(f, (char *)&c, 1);
 	return c;
 }
 
+int read_vstring(int f, char *buf, int bufsize)
+{
+	int len = read_byte(f);
+
+	if (len & 0x80)
+		len = (len & ~0x80) * 0x100 + read_byte(f);
+
+	if (len >= bufsize) {
+		rprintf(FERROR, "over-long vstring received (%d > %d)\n",
+			len, bufsize - 1);
+		return -1;
+	}
+
+	if (len)
+		readfd(f, buf, len);
+	buf[len] = '\0';
+	return len;
+}
+
+/* Populate a sum_struct with values from the socket.  This is
+ * called by both the sender and the receiver. */
+void read_sum_head(int f, struct sum_struct *sum)
+{
+	sum->count = read_int(f);
+	sum->blength = read_int(f);
+	if (sum->blength < 0 || sum->blength > MAX_BLOCK_SIZE) {
+		rprintf(FERROR, "Invalid block length %ld [%s]\n",
+			(long)sum->blength, who_am_i());
+		exit_cleanup(RERR_PROTOCOL);
+	}
+	sum->s2length = protocol_version < 27 ? csum_length : (int)read_int(f);
+	if (sum->s2length < 0 || sum->s2length > MD4_SUM_LENGTH) {
+		rprintf(FERROR, "Invalid checksum length %d [%s]\n",
+			sum->s2length, who_am_i());
+		exit_cleanup(RERR_PROTOCOL);
+	}
+	sum->remainder = read_int(f);
+	if (sum->remainder < 0 || sum->remainder > sum->blength) {
+		rprintf(FERROR, "Invalid remainder length %ld [%s]\n",
+			(long)sum->remainder, who_am_i());
+		exit_cleanup(RERR_PROTOCOL);
+	}
+}
+
+/* Send the values from a sum_struct over the socket.  Set sum to
+ * NULL if there are no checksums to send.  This is called by both
+ * the generator and the sender. */
+void write_sum_head(int f, struct sum_struct *sum)
+{
+	static struct sum_struct null_sum;
+
+	if (sum == NULL)
+		sum = &null_sum;
+
+	write_int(f, sum->count);
+	write_int(f, sum->blength);
+	if (protocol_version >= 27)
+		write_int(f, sum->s2length);
+	write_int(f, sum->remainder);
+}
+
 
 /**
  * Sleep after writing to limit I/O bandwidth usage.
@@ -590,84 +959,114 @@ unsigned char read_byte(int f)
  * use a bit less bandwidth than specified, because it doesn't make up
  * for slow periods.  But arguably this is a feature.  In addition, we
  * ought to take the time used to write the data into account.
+ *
+ * During some phases of big transfers (file FOO is uptodate) this is
+ * called with a small bytes_written every time.  As the kernel has to
+ * round small waits up to guarantee that we actually wait at least the
+ * requested number of microseconds, this can become grossly inaccurate.
+ * We therefore keep track of the bytes we've written over time and only
+ * sleep when the accumulated delay is at least 1 tenth of a second.
  **/
 static void sleep_for_bwlimit(int bytes_written)
 {
-	struct timeval tv;
+	static struct timeval prior_tv;
+	static long total_written = 0; 
+	struct timeval tv, start_tv;
+	long elapsed_usec, sleep_usec;
+
+#define ONE_SEC	1000000L /* # of microseconds in a second */
 
 	if (!bwlimit)
 		return;
 
-	assert(bytes_written > 0);
-	assert(bwlimit > 0);
+	total_written += bytes_written; 
+
+	gettimeofday(&start_tv, NULL);
+	if (prior_tv.tv_sec) {
+		elapsed_usec = (start_tv.tv_sec - prior_tv.tv_sec) * ONE_SEC
+			     + (start_tv.tv_usec - prior_tv.tv_usec);
+		total_written -= elapsed_usec * bwlimit / (ONE_SEC/1024);
+		if (total_written < 0)
+			total_written = 0;
+	}
 
-	tv.tv_usec = bytes_written * 1000 / bwlimit;
-	tv.tv_sec  = tv.tv_usec / 1000000;
-	tv.tv_usec = tv.tv_usec % 1000000;
+	sleep_usec = total_written * (ONE_SEC/1024) / bwlimit;
+	if (sleep_usec < ONE_SEC / 10) {
+		prior_tv = start_tv;
+		return;
+	}
 
+	tv.tv_sec  = sleep_usec / ONE_SEC;
+	tv.tv_usec = sleep_usec % ONE_SEC;
 	select(0, NULL, NULL, NULL, &tv);
+
+	gettimeofday(&prior_tv, NULL);
+	elapsed_usec = (prior_tv.tv_sec - start_tv.tv_sec) * ONE_SEC
+		     + (prior_tv.tv_usec - start_tv.tv_usec);
+	total_written = (sleep_usec - elapsed_usec) * bwlimit / (ONE_SEC/1024);
 }
 
 
-/**
- * Write len bytes to the file descriptor @p fd.
+/* Write len bytes to the file descriptor fd, looping as necessary to get
+ * the job done and also (in certain circumstnces) reading any data on
+ * msg_fd_in to avoid deadlock.
  *
  * This function underlies the multiplexing system.  The body of the
- * application never calls this function directly.
- **/
+ * application never calls this function directly. */
 static void writefd_unbuffered(int fd,char *buf,size_t len)
 {
-	size_t total = 0;
+	size_t n, total = 0;
 	fd_set w_fds, r_fds;
-	int fd_count, count;
+	int maxfd, count, ret, using_r_fds;
 	struct timeval tv;
 
-	err_list_push();
-
 	no_flush++;
 
 	while (total < len) {
 		FD_ZERO(&w_fds);
 		FD_SET(fd,&w_fds);
-		fd_count = fd;
+		maxfd = fd;
 
-		if (io_error_fd >= 0) {
+		if (msg_fd_in >= 0 && len-total >= contiguous_write_len) {
 			FD_ZERO(&r_fds);
-			FD_SET(io_error_fd,&r_fds);
-			if (io_error_fd > fd_count) 
-				fd_count = io_error_fd;
+			FD_SET(msg_fd_in,&r_fds);
+			if (msg_fd_in > maxfd)
+				maxfd = msg_fd_in;
+			using_r_fds = 1;
+		} else
+			using_r_fds = 0;
+		if (fd != sock_f_out && iobuf_out_cnt && no_flush == 1) {
+			FD_SET(sock_f_out, &w_fds);
+			if (sock_f_out > maxfd)
+				maxfd = sock_f_out;
 		}
 
-		tv.tv_sec = io_timeout?io_timeout:SELECT_TIMEOUT;
+		tv.tv_sec = select_timeout;
 		tv.tv_usec = 0;
 
 		errno = 0;
-
-		count = select(fd_count+1,
-			       io_error_fd >= 0?&r_fds:NULL,
-			       &w_fds,NULL,
-			       &tv);
-
-		if (count == 0) {
-			check_timeout();
-		}
+		count = select(maxfd + 1, using_r_fds ? &r_fds : NULL,
+			       &w_fds, NULL, &tv);
 
 		if (count <= 0) {
-			if (errno == EBADF) {
+			if (count < 0 && errno == EBADF)
 				exit_cleanup(RERR_SOCKETIO);
-			}
+			check_timeout();
 			continue;
 		}
 
-		if (io_error_fd >= 0 && FD_ISSET(io_error_fd, &r_fds)) {
-			read_error_fd();
-		}
+		if (using_r_fds && FD_ISSET(msg_fd_in, &r_fds))
+			read_msg_fd();
+
+		if (!FD_ISSET(fd, &w_fds))
+			continue;
 
-		if (FD_ISSET(fd, &w_fds)) {
-			int ret;
-			size_t n = len-total;
-			ret = write(fd,buf+total,n);
+		n = len - total;
+		if (bwlimit && n > bwlimit_writemax)
+			n = bwlimit_writemax;
+		ret = write(fd, buf + total, n);
 
+		if (ret <= 0) {
 			if (ret < 0) {
 				if (errno == EINTR)
 					continue;
@@ -677,23 +1076,29 @@ static void writefd_unbuffered(int fd,char *buf,size_t len)
 				}
 			}
 
-			if (ret <= 0) {
-				/* Don't try to write errors back
-				 * across the stream */
-				io_multiplexing_close();
-				rprintf(FERROR, RSYNC_NAME
-					": writefd_unbuffered failed to write %ld bytes: phase \"%s\": %s\n",
-					(long) len, io_write_phase, 
-					strerror(errno));
-				exit_cleanup(RERR_STREAMIO);
+			/* Don't try to write errors back across the stream. */
+			if (fd == sock_f_out)
+				close_multiplexing_out();
+			rsyserr(FERROR, errno,
+				"writefd_unbuffered failed to write %ld bytes: phase \"%s\" [%s]",
+				(long)len, io_write_phase, who_am_i());
+			/* If the other side is sending us error messages, try
+			 * to grab any messages they sent before they died. */
+			while (fd == sock_f_out && io_multiplexing_in) {
+				io_timeout = select_timeout = 30;
+				ignore_timeout = 0;
+				readfd_unbuffered(sock_f_in, io_filesfrom_buf,
+						  sizeof io_filesfrom_buf);
 			}
+			exit_cleanup(RERR_STREAMIO);
+		}
 
-			sleep_for_bwlimit(ret);
- 
-			total += ret;
+		total += ret;
 
-			if (io_timeout)
+		if (fd == sock_f_out) {
+			if (io_timeout || am_generator)
 				last_io = time(NULL);
+			sleep_for_bwlimit(ret);
 		}
 	}
 
@@ -701,101 +1106,100 @@ static void writefd_unbuffered(int fd,char *buf,size_t len)
 }
 
 
-static char *io_buffer;
-static int io_buffer_count;
-
-void io_start_buffering_out(int fd)
-{
-	if (io_buffer) return;
-	multiplex_out_fd = fd;
-	io_buffer = new_array(char, IO_BUFFER_SIZE);
-	if (!io_buffer) out_of_memory("writefd");
-	io_buffer_count = 0;
-}
-
-void io_start_buffering_in(int fd)
-{
-	multiplex_in_fd = fd;
-}
-
 /**
  * Write an message to a multiplexed stream. If this fails then rsync
  * exits.
  **/
-static void mplex_write(int fd, enum logcode code, char *buf, size_t len)
+static void mplex_write(enum msgcode code, char *buf, size_t len)
 {
 	char buffer[4096];
 	size_t n = len;
 
 	SIVAL(buffer, 0, ((MPLEX_BASE + (int)code)<<24) + len);
 
-	if (n > (sizeof buffer - 4)) {
+	/* When the generator reads messages from the msg_fd_in pipe, it can
+	 * cause output to occur down the socket.  Setting contiguous_write_len
+	 * prevents the reading of msg_fd_in once we actually start to write
+	 * this sequence of data (though we might read it before the start). */
+	if (am_generator && msg_fd_in >= 0)
+		contiguous_write_len = len + 4;
+
+	if (n > sizeof buffer - 4)
 		n = sizeof buffer - 4;
-	}
 
 	memcpy(&buffer[4], buf, n);
-	writefd_unbuffered(fd, buffer, n+4);
+	writefd_unbuffered(sock_f_out, buffer, n+4);
 
 	len -= n;
 	buf += n;
 
-	if (len) {
-		writefd_unbuffered(fd, buf, len);
-	}
+	if (len)
+		writefd_unbuffered(sock_f_out, buf, len);
+
+	if (am_generator && msg_fd_in >= 0)
+		contiguous_write_len = 0;
 }
 
 
-void io_flush(void)
+void io_flush(int flush_it_all)
 {
-	int fd = multiplex_out_fd;
-
-	err_list_push();
+	msg_list_push(flush_it_all);
 
-	if (!io_buffer_count || no_flush) return;
+	if (!iobuf_out_cnt || no_flush)
+		return;
 
-	if (io_multiplexing_out) {
-		mplex_write(fd, FNONE, io_buffer, io_buffer_count);
-	} else {
-		writefd_unbuffered(fd, io_buffer, io_buffer_count);
-	}
-	io_buffer_count = 0;
+	if (io_multiplexing_out)
+		mplex_write(MSG_DATA, iobuf_out, iobuf_out_cnt);
+	else
+		writefd_unbuffered(sock_f_out, iobuf_out, iobuf_out_cnt);
+	iobuf_out_cnt = 0;
 }
 
 
-void io_end_buffering(void)
+static void writefd(int fd,char *buf,size_t len)
 {
-	io_flush();
-	if (!io_multiplexing_out) {
-		free(io_buffer);
-		io_buffer = NULL;
+	if (fd == msg_fd_out) {
+		rprintf(FERROR, "Internal error: wrong write used in receiver.\n");
+		exit_cleanup(RERR_PROTOCOL);
 	}
-}
 
-static void writefd(int fd,char *buf,size_t len)
-{
-	stats.total_written += len;
+	if (fd == sock_f_out)
+		stats.total_written += len;
 
-	err_list_push();
+	if (fd == write_batch_monitor_out) {
+		if ((size_t)write(batch_fd, buf, len) != len)
+			exit_cleanup(RERR_FILEIO);
+	}
 
-	if (!io_buffer || fd != multiplex_out_fd) {
+	if (!iobuf_out || fd != sock_f_out) {
 		writefd_unbuffered(fd, buf, len);
 		return;
 	}
 
 	while (len) {
-		int n = MIN((int) len, IO_BUFFER_SIZE-io_buffer_count);
+		int n = MIN((int)len, IO_BUFFER_SIZE - iobuf_out_cnt);
 		if (n > 0) {
-			memcpy(io_buffer+io_buffer_count, buf, n);
+			memcpy(iobuf_out+iobuf_out_cnt, buf, n);
 			buf += n;
 			len -= n;
-			io_buffer_count += n;
+			iobuf_out_cnt += n;
 		}
 
-		if (io_buffer_count == IO_BUFFER_SIZE) io_flush();
+		if (iobuf_out_cnt == IO_BUFFER_SIZE)
+			io_flush(NORMAL_FLUSH);
 	}
 }
 
 
+void write_shortint(int f, int x)
+{
+	uchar b[2];
+	b[0] = x;
+	b[1] = x >> 8;
+	writefd(f, (char *)b, 2);
+}
+
+
 void write_int(int f,int32 x)
 {
 	char b[4];
@@ -825,8 +1229,8 @@ void write_longint(int f, int64 x)
 		return;
 	}
 
-#ifdef NO_INT64
-	rprintf(FERROR,"Integer overflow - attempted 64 bit offset\n");
+#if SIZEOF_INT64 < 8
+	rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
 	exit_cleanup(RERR_UNSUPPORTED);
 #else
 	write_int(f, (int32)0xFFFFFFFF);
@@ -843,24 +1247,43 @@ void write_buf(int f,char *buf,size_t len)
 }
 
 /** Write a string to the connection */
-static void write_sbuf(int f,char *buf)
+void write_sbuf(int f, char *buf)
 {
-	write_buf(f, buf, strlen(buf));
+	writefd(f, buf, strlen(buf));
 }
 
-
-void write_byte(int f,unsigned char c)
+void write_byte(int f, uchar c)
 {
-	write_buf(f,(char *)&c,1);
+	writefd(f, (char *)&c, 1);
 }
 
+void write_vstring(int f, char *str, int len)
+{
+	uchar lenbuf[3], *lb = lenbuf;
+
+	if (len > 0x7F) {
+		if (len > 0x7FFF) {
+			rprintf(FERROR,
+				"attempting to send over-long vstring (%d > %d)\n",
+				len, 0x7FFF);
+			exit_cleanup(RERR_PROTOCOL);
+		}
+		*lb++ = len / 0x100 + 0x80;
+	}
+	*lb = len;
+
+	writefd(f, (char*)lenbuf, lb - lenbuf + 1);
+	if (len)
+		writefd(f, str, len);
+}
 
 
 /**
- * Read a line of up to @p maxlen characters into @p buf.  Does not
- * contain a trailing newline or carriage return.
+ * Read a line of up to @p maxlen characters into @p buf (not counting
+ * the trailing null).  Strips the (required) trailing newline and all
+ * carriage returns.
  *
- * @return 1 for success; 0 for io error or truncation.
+ * @return 1 for success; 0 for I/O error or truncation.
  **/
 int read_line(int f, char *buf, size_t maxlen)
 {
@@ -869,27 +1292,21 @@ int read_line(int f, char *buf, size_t maxlen)
 		read_buf(f, buf, 1);
 		if (buf[0] == 0)
 			return 0;
-		if (buf[0] == '\n') {
-			buf[0] = 0;
+		if (buf[0] == '\n')
 			break;
-		}
 		if (buf[0] != '\r') {
 			buf++;
 			maxlen--;
 		}
 	}
-	if (maxlen == 0) {
-		*buf = 0;
-		return 0;
-	}
-
-	return 1;
+	*buf = '\0';
+	return maxlen > 0;
 }
 
 
 void io_printf(int fd, const char *format, ...)
 {
-	va_list ap;  
+	va_list ap;
 	char buf[1024];
 	int len;
 
@@ -897,43 +1314,72 @@ void io_printf(int fd, const char *format, ...)
 	len = vsnprintf(buf, sizeof buf, format, ap);
 	va_end(ap);
 
-	if (len < 0) exit_cleanup(RERR_STREAMIO);
+	if (len < 0)
+		exit_cleanup(RERR_STREAMIO);
 
 	write_sbuf(fd, buf);
 }
 
 
-/** Setup for multiplexing an error stream with the data stream */
-void io_start_multiplex_out(int fd)
+/** Setup for multiplexing a MSG_* stream with the data stream. */
+void io_start_multiplex_out(void)
 {
-	multiplex_out_fd = fd;
-	io_flush();
-	io_start_buffering_out(fd);
+	io_flush(NORMAL_FLUSH);
+	io_start_buffering_out();
 	io_multiplexing_out = 1;
 }
 
-/** Setup for multiplexing an error stream with the data stream */
-void io_start_multiplex_in(int fd)
+/** Setup for multiplexing a MSG_* stream with the data stream. */
+void io_start_multiplex_in(void)
 {
-	multiplex_in_fd = fd;
-	io_flush();
+	io_flush(NORMAL_FLUSH);
+	io_start_buffering_in();
 	io_multiplexing_in = 1;
 }
 
-/** Write an message to the multiplexed error stream */
-int io_multiplex_write(enum logcode code, char *buf, size_t len)
+/** Write an message to the multiplexed data stream. */
+int io_multiplex_write(enum msgcode code, char *buf, size_t len)
 {
-	if (!io_multiplexing_out) return 0;
+	if (!io_multiplexing_out)
+		return 0;
 
-	io_flush();
+	io_flush(NORMAL_FLUSH);
 	stats.total_written += (len+4);
-	mplex_write(multiplex_out_fd, code, buf, len);
+	mplex_write(code, buf, len);
 	return 1;
 }
 
-/** Stop output multiplexing */
-void io_multiplexing_close(void)
+void close_multiplexing_in(void)
+{
+	io_multiplexing_in = 0;
+}
+
+/** Stop output multiplexing. */
+void close_multiplexing_out(void)
 {
 	io_multiplexing_out = 0;
 }
 
+void start_write_batch(int fd)
+{
+	write_stream_flags(batch_fd);
+
+	/* Some communication has already taken place, but we don't
+	 * enable batch writing until here so that we can write a
+	 * canonical record of the communication even though the
+	 * actual communication so far depends on whether a daemon
+	 * is involved. */
+	write_int(batch_fd, protocol_version);
+	write_int(batch_fd, checksum_seed);
+
+	if (am_sender)
+		write_batch_monitor_out = fd;
+	else
+		write_batch_monitor_in = fd;
+}
+
+void stop_write_batch(void)
+{
+	write_batch_monitor_out = -1;
+	write_batch_monitor_in = -1;
+}