X-Git-Url: https://mattmccutchen.net/rsync/rsync.git/blobdiff_plain/6fe25398d613689411548ea48c09fa8615009abb..5dd14f0c3388f69932d521915e039e32b9e6d970:/io.c

diff --git a/io.c b/io.c
index 45d91eed..ed556b15 100644
--- a/io.c
+++ b/io.c
@@ -1,159 +1,639 @@
-/* -*- c-file-style: "linux" -*-
-   
-   Copyright (C) 1996-2001 by Andrew Tridgell 
-   Copyright (C) Paul Mackerras 1996
-   Copyright (C) 2001 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.
-*/
-
 /*
-  socket and pipe IO utilities used in rsync 
+ * Socket and pipe I/O utilities used in rsync.
+ *
+ * Copyright (C) 1996-2001 Andrew Tridgell
+ * Copyright (C) 1996 Paul Mackerras
+ * Copyright (C) 2001, 2002 Martin Pool <mbp@samba.org>
+ * Copyright (C) 2003-2008 Wayne Davison
+ *
+ * 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 3 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, visit the http://fsf.org website.
+ */
+
+/* Rsync provides its own multiplexing system, which is used to send
+ * stderr and stdout over a single socket.
+ *
+ * For historical reasons this is off during the start of the
+ * connection, but it's switched on quite early using
+ * io_start_multiplex_out() and io_start_multiplex_in(). */
 
-  tridge, June 1996
-  */
 #include "rsync.h"
+#include "ifuncs.h"
+#include "inums.h"
 
-/* if no timeout is specified then use a 60 second select timeout */
+/** If no timeout is specified then use a 60 second select timeout */
 #define SELECT_TIMEOUT 60
 
+extern int bwlimit;
+extern size_t bwlimit_writemax;
+extern int io_timeout;
+extern int am_server;
+extern int am_daemon;
+extern int am_sender;
+extern int am_generator;
+extern int inc_recurse;
+extern int io_error;
+extern int eol_nulls;
+extern int flist_eof;
+extern int list_only;
+extern int read_batch;
+extern int protect_args;
+extern int checksum_seed;
+extern int protocol_version;
+extern int remove_source_files;
+extern int preserve_hard_links;
+extern struct stats stats;
+extern struct file_list *cur_flist;
+#ifdef ICONV_OPTION
+extern int filesfrom_convert;
+extern iconv_t ic_send, ic_recv;
+#endif
+
+int csum_length = SHORT_SUM_LENGTH; /* initial value */
+int allowed_lull = 0;
+int ignore_timeout = 0;
+int batch_fd = -1;
+int msgdone_cnt = 0;
+
+/* 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 iobuf_f_in = -1;
+static char *iobuf_in;
+static size_t iobuf_in_siz;
+static size_t iobuf_in_ndx;
+static size_t iobuf_in_remaining;
+
+static int iobuf_f_out = -1;
+static char *iobuf_out;
+static int iobuf_out_cnt;
+
+int flist_forward_from = -1;
+
 static int io_multiplexing_out;
 static int io_multiplexing_in;
-static int multiplex_in_fd;
-static int multiplex_out_fd;
-static time_t last_io;
+static time_t last_io_in;
+static time_t last_io_out;
 static int no_flush;
 
-extern int bwlimit;
-extern int verbose;
-extern int io_timeout;
-extern struct stats stats;
+static int write_batch_monitor_in = -1;
+static int write_batch_monitor_out = -1;
+
+static int io_filesfrom_f_in = -1;
+static int io_filesfrom_f_out = -1;
+static xbuf ff_buf = EMPTY_XBUF;
+static char ff_lastchar;
+#ifdef ICONV_OPTION
+static xbuf iconv_buf = EMPTY_XBUF;
+#endif
+static int defer_forwarding_messages = 0, keep_defer_forwarding = 0;
+static int select_timeout = SELECT_TIMEOUT;
+static int active_filecnt = 0;
+static OFF_T active_bytecnt = 0;
+static int first_message = 1;
+
+static char int_byte_extra[64] = {
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* (00 - 3F)/4 */
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* (40 - 7F)/4 */
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* (80 - BF)/4 */
+	2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 5, 6, /* (C0 - FF)/4 */
+};
+
+#define REMOTE_OPTION_ERROR "rsync: on remote machine: -"
+#define REMOTE_OPTION_ERROR2 ": unknown option"
+
+enum festatus { FES_SUCCESS, FES_REDO, FES_NO_SEND };
 
+static void readfd(int fd, char *buffer, size_t N);
+static void writefd(int fd, const char *buf, size_t len);
+static void writefd_unbuffered(int fd, const char *buf, size_t len);
+static void mplex_write(int fd, enum msgcode code, const char *buf, size_t len, int convert);
 
-/** Ignore EOF errors while reading a module listing if the remote
-    version is 24 or less. */
-int kludge_around_eof = False;
+struct flist_ndx_item {
+	struct flist_ndx_item *next;
+	int ndx;
+};
 
+struct flist_ndx_list {
+	struct flist_ndx_item *head, *tail;
+};
 
-static int io_error_fd = -1;
+static struct flist_ndx_list redo_list, hlink_list;
 
-static void read_loop(int fd, char *buf, size_t len);
+struct msg_list_item {
+	struct msg_list_item *next;
+	char convert;
+	char buf[1];
+};
+
+struct msg_list {
+	struct msg_list_item *head, *tail;
+};
+
+static struct msg_list msg_queue;
+
+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 got_flist_entry_status(enum festatus status, const char *buf)
+{
+	int ndx = IVAL(buf, 0);
+	struct file_list *flist = flist_for_ndx(ndx, "got_flist_entry_status");
+
+	if (remove_source_files) {
+		active_filecnt--;
+		active_bytecnt -= F_LENGTH(flist->files[ndx - flist->ndx_start]);
+	}
+
+	if (inc_recurse)
+		flist->in_progress--;
+
+	switch (status) {
+	case FES_SUCCESS:
+		if (remove_source_files)
+			send_msg(MSG_SUCCESS, buf, 4, 0);
+		if (preserve_hard_links) {
+			struct file_struct *file = flist->files[ndx - flist->ndx_start];
+			if (F_IS_HLINKED(file)) {
+				flist_ndx_push(&hlink_list, ndx);
+				flist->in_progress++;
+			}
+		}
+		break;
+	case FES_REDO:
+		if (inc_recurse)
+			flist->to_redo++;
+		flist_ndx_push(&redo_list, ndx);
+		break;
+	case FES_NO_SEND:
+		break;
+	}
+}
 
 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);
+	if (!last_io_in) {
+		last_io_in = time(NULL);
 		return;
 	}
 
 	t = time(NULL);
 
-	if (last_io && io_timeout && (t-last_io) >= io_timeout) {
+	if (t - last_io_in >= io_timeout) {
 		if (!am_server && !am_daemon) {
-			rprintf(FERROR,"io timeout after %d seconds - exiting\n", 
-				(int)(t-last_io));
+			rprintf(FERROR, "io timeout after %d seconds -- exiting\n",
+				(int)(t-last_io_in));
 		}
 		exit_cleanup(RERR_TIMEOUT);
 	}
 }
 
-/* setup the fd used to propogate 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)
+{
+	sock_f_in = f_in;
+	sock_f_out = f_out;
+}
+
+void set_io_timeout(int secs)
+{
+	io_timeout = secs;
+
+	if (!io_timeout || io_timeout > SELECT_TIMEOUT)
+		select_timeout = SELECT_TIMEOUT;
+	else
+		select_timeout = io_timeout;
+
+	allowed_lull = read_batch ? 0 : (io_timeout + 1) / 2;
+}
+
+/* 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)
+{
+	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(struct msg_list *lst, int code, const char *buf, int len, int convert)
+{
+	struct msg_list_item *m;
+	int sz = len + 4 + sizeof m[0] - 1;
+
+	if (!(m = (struct msg_list_item *)new_array(char, sz)))
+		out_of_memory("msg_list_add");
+	m->next = NULL;
+	m->convert = convert;
+	SIVAL(m->buf, 0, ((code+MPLEX_BASE)<<24) | len);
+	memcpy(m->buf + 4, buf, len);
+	if (lst->tail)
+		lst->tail->next = m;
+	else
+		lst->head = m;
+	lst->tail = m;
+}
+
+static inline int flush_a_msg(int fd)
+{
+	struct msg_list_item *m = msg_queue.head;
+	int len = IVAL(m->buf, 0) & 0xFFFFFF;
+	int tag = *((uchar*)m->buf+3) - MPLEX_BASE;
+
+	if (!(msg_queue.head = m->next))
+		msg_queue.tail = NULL;
+
+	defer_forwarding_messages++;
+	mplex_write(fd, tag, m->buf + 4, len, m->convert);
+	defer_forwarding_messages--;
+
+	free(m);
+
+	return len;
+}
+
+static void msg_flush(void)
+{
+	if (am_generator) {
+		while (msg_queue.head && io_multiplexing_out)
+			stats.total_written += flush_a_msg(sock_f_out) + 4;
+	} else {
+		while (msg_queue.head)
+			(void)flush_a_msg(msg_fd_out);
+	}
+}
+
+static void check_for_d_option_error(const char *msg)
 {
-	io_error_fd = fd;
+	static char rsync263_opts[] = "BCDHIKLPRSTWabceghlnopqrtuvxz";
+	char *colon;
+	int saw_d = 0;
+
+	if (*msg != 'r'
+	 || strncmp(msg, REMOTE_OPTION_ERROR, sizeof REMOTE_OPTION_ERROR - 1) != 0)
+		return;
+
+	msg += sizeof REMOTE_OPTION_ERROR - 1;
+	if (*msg == '-' || (colon = strchr(msg, ':')) == NULL
+	 || strncmp(colon, REMOTE_OPTION_ERROR2, sizeof REMOTE_OPTION_ERROR2 - 1) != 0)
+		return;
+
+	for ( ; *msg != ':'; msg++) {
+		if (*msg == 'd')
+			saw_d = 1;
+		else if (*msg == 'e')
+			break;
+		else if (strchr(rsync263_opts, *msg) == NULL)
+			return;
+	}
+
+	if (saw_d) {
+		rprintf(FWARNING,
+		    "*** Try using \"--old-d\" if remote rsync is <= 2.6.3 ***\n");
+	}
 }
 
-/* read some data from the error fd and write it to the write log code */
-static void read_error_fd(void)
+/* 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[200];
-	int n;
-	int fd = io_error_fd;
+	char buf[2048];
+	size_t n;
+	struct file_list *flist;
+	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(). */
+	no_flush++;
+	msg_fd_in = -1;
+	defer_forwarding_messages++;
 
-	read_loop(fd, buf, 4);
+	readfd(fd, buf, 4);
 	tag = IVAL(buf, 0);
 
 	len = tag & 0xFFFFFF;
-	tag = tag >> 24;
-	tag -= 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;
+	tag = (tag >> 24) - MPLEX_BASE;
+
+	switch (tag) {
+	case MSG_DONE:
+		if (len < 0 || len > 1 || !am_generator) {
+		  invalid_msg:
+			rprintf(FERROR, "invalid message %d:%d [%s%s]\n",
+				tag, len, who_am_i(),
+				inc_recurse ? "/inc" : "");
+			exit_cleanup(RERR_STREAMIO);
+		}
+		if (len) {
+			readfd(fd, buf, len);
+			stats.total_read = read_varlong(fd, 3);
+		}
+		msgdone_cnt++;
+		break;
+	case MSG_REDO:
+		if (len != 4 || !am_generator)
+			goto invalid_msg;
+		readfd(fd, buf, 4);
+		got_flist_entry_status(FES_REDO, buf);
+		break;
+	case MSG_FLIST:
+		if (len != 4 || !am_generator || !inc_recurse)
+			goto invalid_msg;
+		readfd(fd, buf, 4);
+		/* Read extra file list from receiver. */
+		assert(iobuf_in != NULL);
+		assert(iobuf_f_in == fd);
+		if (DEBUG_GTE(FLIST, 2)) {
+			rprintf(FINFO, "[%s] receiving flist for dir %d\n",
+				who_am_i(), IVAL(buf,0));
+		}
+		flist = recv_file_list(fd);
+		flist->parent_ndx = IVAL(buf,0);
+#ifdef SUPPORT_HARD_LINKS
+		if (preserve_hard_links)
+			match_hard_links(flist);
+#endif
+		break;
+	case MSG_FLIST_EOF:
+		if (len != 0 || !am_generator || !inc_recurse)
+			goto invalid_msg;
+		flist_eof = 1;
+		break;
+	case MSG_IO_ERROR:
+		if (len != 4)
+			goto invalid_msg;
+		readfd(fd, buf, len);
+		io_error |= IVAL(buf, 0);
+		break;
+	case MSG_DELETED:
+		if (len >= (int)sizeof buf || !am_generator)
+			goto invalid_msg;
+		readfd(fd, buf, len);
+		send_msg(MSG_DELETED, buf, len, 1);
+		break;
+	case MSG_SUCCESS:
+		if (len != 4 || !am_generator)
+			goto invalid_msg;
+		readfd(fd, buf, 4);
+		got_flist_entry_status(FES_SUCCESS, buf);
+		break;
+	case MSG_NO_SEND:
+		if (len != 4 || !am_generator)
+			goto invalid_msg;
+		readfd(fd, buf, 4);
+		got_flist_entry_status(FES_NO_SEND, buf);
+		break;
+	case MSG_ERROR_SOCKET:
+	case MSG_ERROR_UTF8:
+	case MSG_CLIENT:
+		if (!am_generator)
+			goto invalid_msg;
+		if (tag == MSG_ERROR_SOCKET)
+			io_end_multiplex_out();
+		/* FALL THROUGH */
+	case MSG_INFO:
+	case MSG_ERROR:
+	case MSG_ERROR_XFER:
+	case MSG_WARNING:
+	case MSG_LOG:
+		while (len) {
+			n = len;
+			if (n >= sizeof buf)
+				n = sizeof buf - 1;
+			readfd(fd, buf, n);
+			rwrite((enum logcode)tag, buf, n, !am_generator);
+			len -= n;
+		}
+		break;
+	default:
+		rprintf(FERROR, "unknown message %d:%d [%s]\n",
+			tag, len, who_am_i());
+		exit_cleanup(RERR_STREAMIO);
 	}
 
-	io_error_fd = fd;
+	no_flush--;
+	msg_fd_in = fd;
+	if (!--defer_forwarding_messages && !no_flush)
+		msg_flush();
 }
 
+/* This is used by the generator to limit how many file transfers can
+ * be active at once when --remove-source-files is specified.  Without
+ * this, sender-side deletions were mostly happening at the end. */
+void increment_active_files(int ndx, int itemizing, enum logcode code)
+{
+	/* TODO: tune these limits? */
+	while (active_filecnt >= (active_bytecnt >= 128*1024 ? 10 : 50)) {
+		check_for_finished_files(itemizing, code, 0);
+		if (iobuf_out_cnt)
+			io_flush(NORMAL_FLUSH);
+		else
+			read_msg_fd();
+	}
+
+	active_filecnt++;
+	active_bytecnt += F_LENGTH(cur_flist->files[ndx - cur_flist->ndx_start]);
+}
 
-static void whine_about_eof (void)
+/* Write an message to a multiplexed stream. If this fails, rsync exits. */
+static void mplex_write(int fd, enum msgcode code, const char *buf, size_t len, int convert)
 {
-	/**
-	   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.
-	   
-	   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.
-	*/
+	char buffer[BIGPATHBUFLEN]; /* Oversized for use by iconv code. */
+	size_t n = len;
+
+#ifdef ICONV_OPTION
+	/* We need to convert buf before doing anything else so that we
+	 * can include the (converted) byte length in the message header. */
+	if (convert && ic_send != (iconv_t)-1) {
+		xbuf outbuf, inbuf;
+
+		INIT_XBUF(outbuf, buffer + 4, 0, sizeof buffer - 4);
+		INIT_XBUF(inbuf, (char*)buf, len, (size_t)-1);
+
+		iconvbufs(ic_send, &inbuf, &outbuf,
+			  ICB_INCLUDE_BAD | ICB_INCLUDE_INCOMPLETE);
+		if (inbuf.len > 0) {
+			rprintf(FERROR, "overflowed conversion buffer in mplex_write");
+			exit_cleanup(RERR_UNSUPPORTED);
+		}
 
-	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);
+		n = len = outbuf.len;
+	} else
+#endif
+	if (n > 1024 - 4) /* BIGPATHBUFLEN can handle 1024 bytes */
+		n = 0;    /* We'd rather do 2 writes than too much memcpy(). */
+	else
+		memcpy(buffer + 4, buf, n);
+
+	SIVAL(buffer, 0, ((MPLEX_BASE + (int)code)<<24) + len);
+
+	keep_defer_forwarding++; /* defer_forwarding_messages++ on return */
+	writefd_unbuffered(fd, buffer, n+4);
+	keep_defer_forwarding--;
+
+	if (len > n)
+		writefd_unbuffered(fd, buf+n, len-n);
+
+	if (!--defer_forwarding_messages && !no_flush)
+		msg_flush();
+}
+
+int send_msg(enum msgcode code, const char *buf, int len, int convert)
+{
+	if (msg_fd_out < 0) {
+		if (!defer_forwarding_messages)
+			return io_multiplex_write(code, buf, len, convert);
+		if (!io_multiplexing_out)
+			return 0;
+		msg_list_add(&msg_queue, code, buf, len, convert);
+		return 1;
 	}
+	if (flist_forward_from >= 0)
+		msg_list_add(&msg_queue, code, buf, len, convert);
+	else
+		mplex_write(msg_fd_out, code, buf, len, convert);
+	return 1;
 }
 
+void send_msg_int(enum msgcode code, int num)
+{
+	char numbuf[4];
+	SIVAL(numbuf, 0, num);
+	send_msg(code, numbuf, 4, 0);
+}
 
-static void die_from_readerr (int err)
+void wait_for_receiver(void)
 {
-	/* 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);
+	if (io_flush(FULL_FLUSH))
+		return;
+	read_msg_fd();
+}
+
+int get_redo_num(void)
+{
+	return flist_ndx_pop(&redo_list);
 }
 
+int get_hlink_num(void)
+{
+	return flist_ndx_pop(&hlink_list);
+}
+
+/**
+ * When we're the receiver and we have a local --files-from list of names
+ * that needs to be sent over the socket to the sender, we have to do two
+ * things at the same time: send the sender a list of what files we're
+ * processing and read the incoming file+info list from the sender.  We do
+ * this by augmenting the read_timeout() function to copy this data.  It
+ * uses ff_buf to read a block of data from f_in (when it is ready, since
+ * it might be a pipe) and then blast it out f_out (when it is ready to
+ * receive more data).
+ */
+void io_set_filesfrom_fds(int f_in, int f_out)
+{
+	io_filesfrom_f_in = f_in;
+	io_filesfrom_f_out = f_out;
+	alloc_xbuf(&ff_buf, 2048);
+#ifdef ICONV_OPTION
+	if (protect_args)
+		alloc_xbuf(&iconv_buf, 1024);
+#endif
+}
+
+/* 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.
+ *
+ * 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 (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 "
+		"(%s bytes received so far) [%s]\n",
+		big_num(stats.total_read), who_am_i());
+
+	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
@@ -163,80 +643,376 @@ static void die_from_readerr (int err)
  * give a better explanation.  We can tell whether the connection has
  * started by looking e.g. at whether the remote version is known yet.
  */
-static int read_timeout (int fd, char *buf, size_t len)
+static int read_timeout(int fd, char *buf, size_t len)
 {
-	int n, ret=0;
+	int n, cnt = 0;
 
-	io_flush();
+	io_flush(FULL_FLUSH);
 
-	while (ret == 0) {
+	while (cnt == 0) {
 		/* until we manage to read *something* */
-		fd_set fds;
+		fd_set r_fds, w_fds;
 		struct timeval tv;
-		int fd_count = fd+1;
+		int maxfd = fd;
 		int count;
 
-		FD_ZERO(&fds);
-		FD_SET(fd, &fds);
-		if (io_error_fd != -1) {
-			FD_SET(io_error_fd, &fds);
-			if (io_error_fd > fd) fd_count = io_error_fd+1;
+		FD_ZERO(&r_fds);
+		FD_ZERO(&w_fds);
+		FD_SET(fd, &r_fds);
+		if (io_filesfrom_f_out >= 0) {
+			int new_fd;
+			if (ff_buf.len == 0) {
+				if (io_filesfrom_f_in >= 0) {
+					FD_SET(io_filesfrom_f_in, &r_fds);
+					new_fd = io_filesfrom_f_in;
+				} else {
+					io_filesfrom_f_out = -1;
+					new_fd = -1;
+				}
+			} else {
+				FD_SET(io_filesfrom_f_out, &w_fds);
+				new_fd = io_filesfrom_f_out;
+			}
+			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, &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) {
+				defer_forwarding_messages = 0;
 				exit_cleanup(RERR_SOCKETIO);
 			}
+			check_timeout();
 			continue;
 		}
 
-		if (io_error_fd != -1 && FD_ISSET(io_error_fd, &fds)) {
-			read_error_fd();
+		if (io_filesfrom_f_out >= 0) {
+			if (ff_buf.len) {
+				if (FD_ISSET(io_filesfrom_f_out, &w_fds)) {
+					int l = write(io_filesfrom_f_out,
+						      ff_buf.buf + ff_buf.pos,
+						      ff_buf.len);
+					if (l > 0) {
+						if (!(ff_buf.len -= l))
+							ff_buf.pos = 0;
+						else
+							ff_buf.pos += l;
+					} else if (errno != EINTR) {
+						/* XXX should we complain? */
+						io_filesfrom_f_out = -1;
+					}
+				}
+			} else if (io_filesfrom_f_in >= 0) {
+				if (FD_ISSET(io_filesfrom_f_in, &r_fds)) {
+#ifdef ICONV_OPTION
+					xbuf *ibuf = filesfrom_convert ? &iconv_buf : &ff_buf;
+#else
+					xbuf *ibuf = &ff_buf;
+#endif
+					int l = read(io_filesfrom_f_in, ibuf->buf, ibuf->size);
+					if (l <= 0) {
+						if (l == 0 || errno != EINTR) {
+							/* Send end-of-file marker */
+							memcpy(ff_buf.buf, "\0\0", 2);
+							ff_buf.len = ff_lastchar? 2 : 1;
+							ff_buf.pos = 0;
+							io_filesfrom_f_in = -1;
+						}
+					} else {
+#ifdef ICONV_OPTION
+						if (filesfrom_convert) {
+							iconv_buf.pos = 0;
+							iconv_buf.len = l;
+							iconvbufs(ic_send, &iconv_buf, &ff_buf,
+							    ICB_EXPAND_OUT|ICB_INCLUDE_BAD|ICB_INCLUDE_INCOMPLETE);
+							l = ff_buf.len;
+						}
+#endif
+						if (!eol_nulls) {
+							char *s = ff_buf.buf + l;
+							/* Transform CR and/or LF into '\0' */
+							while (s-- > ff_buf.buf) {
+								if (*s == '\n' || *s == '\r')
+									*s = '\0';
+							}
+						}
+						if (!ff_lastchar) {
+							/* Last buf ended with a '\0', so don't
+							 * let this buf start with one. */
+							while (l && ff_buf.buf[ff_buf.pos] == '\0')
+								ff_buf.pos++, l--;
+						}
+						if (!l)
+							ff_buf.pos = 0;
+						else {
+							char *f = ff_buf.buf + ff_buf.pos;
+							char *t = f;
+							char *eob = f + l;
+							/* Eliminate any multi-'\0' runs. */
+							while (f != eob) {
+								if (!(*t++ = *f++)) {
+									while (f != eob && !*f)
+										f++, l--;
+								}
+							}
+							ff_lastchar = f[-1];
+						}
+						ff_buf.len = l;
+					}
+				}
+			}
 		}
 
-		if (!FD_ISSET(fd, &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);
+		if (n <= 0) {
+			if (n == 0)
+				whine_about_eof(fd); /* Doesn't return. */
+			if (errno == EINTR || errno == EWOULDBLOCK
+			    || errno == EAGAIN)
+				continue;
+
+			/* Don't write errors on a dead socket. */
+			if (fd == sock_f_in) {
+				io_end_multiplex_out();
+				rsyserr(FERROR_SOCKET, errno, "read error");
+			} else
+				rsyserr(FERROR, errno, "read error");
+			exit_cleanup(RERR_STREAMIO);
+		}
+
+		buf += n;
+		len -= n;
+		cnt += n;
+
+		if (fd == sock_f_in && io_timeout)
+			last_io_in = time(NULL);
+	}
+
+	return cnt;
+}
+
+/* Read a line into the "buf" buffer. */
+int read_line(int fd, char *buf, size_t bufsiz, int flags)
+{
+	char ch, *s, *eob;
+	int cnt;
+
+#ifdef ICONV_OPTION
+	if (flags & RL_CONVERT && iconv_buf.size < bufsiz)
+		realloc_xbuf(&iconv_buf, bufsiz + 1024);
+#endif
+
+  start:
+#ifdef ICONV_OPTION
+	s = flags & RL_CONVERT ? iconv_buf.buf : buf;
+#else
+	s = buf;
+#endif
+	eob = s + bufsiz - 1;
+	while (1) {
+		cnt = read(fd, &ch, 1);
+		if (cnt < 0 && (errno == EWOULDBLOCK
+		  || errno == EINTR || errno == EAGAIN)) {
+			struct timeval tv;
+			fd_set r_fds, e_fds;
+			FD_ZERO(&r_fds);
+			FD_SET(fd, &r_fds);
+			FD_ZERO(&e_fds);
+			FD_SET(fd, &e_fds);
+			tv.tv_sec = select_timeout;
+			tv.tv_usec = 0;
+			if (!select(fd+1, &r_fds, NULL, &e_fds, &tv))
+				check_timeout();
+			/*if (FD_ISSET(fd, &e_fds))
+				rprintf(FINFO, "select exception on fd %d\n", fd); */
 			continue;
-		} else if (n == 0) {
-			whine_about_eof ();
-			return -1; /* doesn't return */
-		} else if (n == -1) {
-			if (errno == EINTR || errno == EWOULDBLOCK ||
-			    errno == EAGAIN) 
+		}
+		if (cnt != 1)
+			break;
+		if (flags & RL_EOL_NULLS ? ch == '\0' : (ch == '\r' || ch == '\n')) {
+			/* Skip empty lines if dumping comments. */
+			if (flags & RL_DUMP_COMMENTS && s == buf)
 				continue;
+			break;
+		}
+		if (s < eob)
+			*s++ = ch;
+	}
+	*s = '\0';
+
+	if (flags & RL_DUMP_COMMENTS && (*buf == '#' || *buf == ';'))
+		goto start;
+
+#ifdef ICONV_OPTION
+	if (flags & RL_CONVERT) {
+		xbuf outbuf;
+		INIT_XBUF(outbuf, buf, 0, bufsiz);
+		iconv_buf.pos = 0;
+		iconv_buf.len = s - iconv_buf.buf;
+		iconvbufs(ic_recv, &iconv_buf, &outbuf,
+			  ICB_INCLUDE_BAD | ICB_INCLUDE_INCOMPLETE);
+		outbuf.buf[outbuf.len] = '\0';
+		return outbuf.len;
+	}
+#endif
+
+	return s - buf;
+}
+
+void read_args(int f_in, char *mod_name, char *buf, size_t bufsiz, int rl_nulls,
+	       char ***argv_p, int *argc_p, char **request_p)
+{
+	int maxargs = MAX_ARGS;
+	int dot_pos = 0;
+	int argc = 0;
+	char **argv, *p;
+	int rl_flags = (rl_nulls ? RL_EOL_NULLS : 0);
+
+#ifdef ICONV_OPTION
+	rl_flags |= (protect_args && ic_recv != (iconv_t)-1 ? RL_CONVERT : 0);
+#endif
+
+	if (!(argv = new_array(char *, maxargs)))
+		out_of_memory("read_args");
+	if (mod_name && !protect_args)
+		argv[argc++] = "rsyncd";
+
+	while (1) {
+		if (read_line(f_in, buf, bufsiz, rl_flags) == 0)
+			break;
+
+		if (argc == maxargs-1) {
+			maxargs += MAX_ARGS;
+			if (!(argv = realloc_array(argv, char *, maxargs)))
+				out_of_memory("read_args");
+		}
+
+		if (dot_pos) {
+			if (request_p) {
+				*request_p = strdup(buf);
+				request_p = NULL;
+			}
+			if (mod_name)
+				glob_expand_module(mod_name, buf, &argv, &argc, &maxargs);
 			else
-				die_from_readerr (errno);
+				glob_expand(buf, &argv, &argc, &maxargs);
+		} else {
+			if (!(p = strdup(buf)))
+				out_of_memory("read_args");
+			argv[argc++] = p;
+			if (*p == '.' && p[1] == '\0')
+				dot_pos = argc;
 		}
 	}
+	argv[argc] = NULL;
+
+	glob_expand(NULL, NULL, NULL, NULL);
 
-	return ret;
+	*argc_p = argc;
+	*argv_p = argv;
+}
+
+int io_start_buffering_out(int f_out)
+{
+	if (iobuf_out) {
+		assert(f_out == iobuf_f_out);
+		return 0;
+	}
+	if (!(iobuf_out = new_array(char, IO_BUFFER_SIZE)))
+		out_of_memory("io_start_buffering_out");
+	iobuf_out_cnt = 0;
+	iobuf_f_out = f_out;
+	return 1;
+}
+
+int io_start_buffering_in(int f_in)
+{
+	if (iobuf_in) {
+		assert(f_in == iobuf_f_in);
+		return 0;
+	}
+	iobuf_in_siz = 2 * IO_BUFFER_SIZE;
+	if (!(iobuf_in = new_array(char, iobuf_in_siz)))
+		out_of_memory("io_start_buffering_in");
+	iobuf_f_in = f_in;
+	return 1;
 }
 
+void io_end_buffering_in(void)
+{
+	if (!iobuf_in)
+		return;
+	free(iobuf_in);
+	iobuf_in = NULL;
+	iobuf_in_ndx = 0;
+	iobuf_in_remaining = 0;
+	iobuf_f_in = -1;
+}
 
+void io_end_buffering_out(void)
+{
+	if (!iobuf_out)
+		return;
+	io_flush(FULL_FLUSH);
+	free(iobuf_out);
+	iobuf_out = NULL;
+	iobuf_f_out = -1;
+}
 
+void maybe_flush_socket(int important)
+{
+	if (iobuf_out && iobuf_out_cnt
+	 && (important || time(NULL) - last_io_out >= 5))
+		io_flush(NORMAL_FLUSH);
+}
 
-/*! Continue trying to read len bytes - don't return until len has
-  been read.   */
-static void read_loop (int fd, char *buf, size_t len)
+void maybe_send_keepalive(void)
+{
+	if (time(NULL) - last_io_out >= allowed_lull) {
+		if (!iobuf_out || !iobuf_out_cnt) {
+			if (protocol_version < 29)
+				return; /* there's nothing we can do */
+			if (protocol_version >= 30)
+				send_msg(MSG_NOOP, "", 0, 0);
+			else {
+				write_int(sock_f_out, cur_flist->used);
+				write_shortint(sock_f_out, ITEM_IS_NEW);
+			}
+		}
+		if (iobuf_out)
+			io_flush(NORMAL_FLUSH);
+	}
+}
+
+void start_flist_forward(int f_in)
+{
+	assert(iobuf_out != NULL);
+	assert(iobuf_f_out == msg_fd_out);
+	flist_forward_from = f_in;
+}
+
+void stop_flist_forward()
+{
+	flist_forward_from = -1;
+	io_flush(FULL_FLUSH);
+}
+
+/**
+ * Continue trying to read len bytes - don't return until len has been
+ * read.
+ **/
+static void read_loop(int fd, char *buf, size_t len)
 {
 	while (len) {
 		int n = read_timeout(fd, buf, len);
@@ -246,327 +1022,661 @@ 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;
-	int tag, ret = 0;
-	char line[1024];
+	size_t msg_bytes;
+	int tag, cnt = 0;
+	char line[BIGPATHBUFLEN];
 
-	if (!io_multiplexing_in || fd != multiplex_in_fd)
+	if (!iobuf_in || fd != iobuf_f_in)
 		return read_timeout(fd, buf, len);
 
-	while (ret == 0) {
-		if (remaining) {
-			len = MIN(len, remaining);
-			read_loop(fd, buf, len);
-			remaining -= len;
-			ret = len;
-			continue;
+	if (!io_multiplexing_in && iobuf_in_remaining == 0) {
+		iobuf_in_remaining = read_timeout(fd, iobuf_in, iobuf_in_siz);
+		iobuf_in_ndx = 0;
+	}
+
+	while (cnt == 0) {
+		if (iobuf_in_remaining) {
+			len = MIN(len, iobuf_in_remaining);
+			memcpy(buf, iobuf_in + iobuf_in_ndx, len);
+			iobuf_in_ndx += len;
+			iobuf_in_remaining -= len;
+			cnt = len;
+			break;
 		}
 
 		read_loop(fd, line, 4);
 		tag = IVAL(line, 0);
 
-		remaining = tag & 0xFFFFFF;
-		tag = tag >> 24;
+		msg_bytes = tag & 0xFFFFFF;
+		tag = (tag >> 24) - MPLEX_BASE;
 
-		if (tag == MPLEX_BASE)
-			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 %d\n\n",
-				remaining);
+		switch (tag) {
+		case MSG_DATA:
+			if (msg_bytes > iobuf_in_siz) {
+				if (!(iobuf_in = realloc_array(iobuf_in, char,
+							       msg_bytes)))
+					out_of_memory("readfd_unbuffered");
+				iobuf_in_siz = msg_bytes;
+			}
+			read_loop(fd, iobuf_in, msg_bytes);
+			iobuf_in_remaining = msg_bytes;
+			iobuf_in_ndx = 0;
+			break;
+		case MSG_NOOP:
+			if (am_sender)
+				maybe_send_keepalive();
+			break;
+		case MSG_IO_ERROR:
+			if (msg_bytes != 4)
+				goto invalid_msg;
+			read_loop(fd, line, msg_bytes);
+			send_msg_int(MSG_IO_ERROR, IVAL(line, 0));
+			io_error |= IVAL(line, 0);
+			break;
+		case MSG_DELETED:
+			if (msg_bytes >= sizeof line)
+				goto overflow;
+#ifdef ICONV_OPTION
+			if (ic_recv != (iconv_t)-1) {
+				xbuf outbuf, inbuf;
+				char ibuf[512];
+				int add_null = 0;
+
+				INIT_CONST_XBUF(outbuf, line);
+				INIT_XBUF(inbuf, ibuf, 0, (size_t)-1);
+
+				while (msg_bytes) {
+					inbuf.len = msg_bytes > sizeof ibuf
+						  ? sizeof ibuf : msg_bytes;
+					read_loop(fd, inbuf.buf, inbuf.len);
+					if (!(msg_bytes -= inbuf.len)
+					 && !ibuf[inbuf.len-1])
+						inbuf.len--, add_null = 1;
+					if (iconvbufs(ic_send, &inbuf, &outbuf,
+					    ICB_INCLUDE_BAD | ICB_INCLUDE_INCOMPLETE) < 0)
+						goto overflow;
+				}
+				if (add_null) {
+					if (outbuf.len == outbuf.size)
+						goto overflow;
+					outbuf.buf[outbuf.len++] = '\0';
+				}
+				msg_bytes = outbuf.len;
+			} else
+#endif
+				read_loop(fd, line, msg_bytes);
+			/* A directory name was sent with the trailing null */
+			if (msg_bytes > 0 && !line[msg_bytes-1])
+				log_delete(line, S_IFDIR);
+			else {
+				line[msg_bytes] = '\0';
+				log_delete(line, S_IFREG);
+			}
+			break;
+		case MSG_SUCCESS:
+			if (msg_bytes != 4) {
+			  invalid_msg:
+				rprintf(FERROR, "invalid multi-message %d:%ld [%s]\n",
+					tag, (long)msg_bytes, who_am_i());
+				exit_cleanup(RERR_STREAMIO);
+			}
+			read_loop(fd, line, msg_bytes);
+			successful_send(IVAL(line, 0));
+			break;
+		case MSG_NO_SEND:
+			if (msg_bytes != 4)
+				goto invalid_msg;
+			read_loop(fd, line, msg_bytes);
+			send_msg_int(MSG_NO_SEND, IVAL(line, 0));
+			break;
+		case MSG_INFO:
+		case MSG_ERROR:
+		case MSG_ERROR_XFER:
+		case MSG_WARNING:
+			if (msg_bytes >= sizeof line) {
+			    overflow:
+				rprintf(FERROR,
+					"multiplexing overflow %d:%ld [%s]\n",
+					tag, (long)msg_bytes, who_am_i());
+				exit_cleanup(RERR_STREAMIO);
+			}
+			read_loop(fd, line, msg_bytes);
+			rwrite((enum logcode)tag, line, msg_bytes, 1);
+			if (first_message) {
+				if (list_only && !am_sender && tag == 1) {
+					line[msg_bytes] = '\0';
+					check_for_d_option_error(line);
+				}
+				first_message = 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;
 	}
 
-	return ret;
-}
-
+	if (iobuf_in_remaining == 0)
+		io_flush(NORMAL_FLUSH);
 
+	return cnt;
+}
 
-/* do a buffered read from fd. don't return until all N bytes
-   have been read. If all N can't be read then exit with an error */
-static void readfd (int fd, char *buffer, size_t N)
+/* Do a buffered read from fd.  Don't return until all N bytes have
+ * been read.  If all N can't be read then exit with an error. */
+static void readfd(int fd, char *buffer, size_t N)
 {
-	int  ret;
-	int total=0;  
-	
+	int  cnt;
+	size_t total = 0;
+
 	while (total < N) {
-		io_flush();
+		cnt = readfd_unbuffered(fd, buffer + total, N-total);
+		total += cnt;
+	}
 
-		ret = read_unbuffered (fd, buffer + total, N-total);
-		total += ret;
+	if (fd == write_batch_monitor_in) {
+		if ((size_t)write(batch_fd, buffer, total) != total)
+			exit_cleanup(RERR_FILEIO);
 	}
 
-	stats.total_read += total;
+	if (fd == flist_forward_from)
+		writefd(iobuf_f_out, buffer, total);
+
+	if (fd == sock_f_in)
+		stats.total_read += total;
 }
 
+unsigned short read_shortint(int f)
+{
+	char b[2];
+	readfd(f, b, 2);
+	return (UVAL(b, 1) << 8) + UVAL(b, 0);
+}
 
 int32 read_int(int f)
 {
 	char b[4];
-	int32 ret;
+	int32 num;
 
-	readfd(f,b,4);
-	ret = IVAL(b,0);
-	if (ret == (int32)0xffffffff) return -1;
-	return ret;
+	readfd(f, b, 4);
+	num = IVAL(b, 0);
+#if SIZEOF_INT32 > 4
+	if (num & (int32)0x80000000)
+		num |= ~(int32)0xffffffff;
+#endif
+	return num;
+}
+
+int32 read_varint(int f)
+{
+	union {
+	    char b[5];
+	    int32 x;
+	} u;
+	uchar ch;
+	int extra;
+
+	u.x = 0;
+	readfd(f, (char*)&ch, 1);
+	extra = int_byte_extra[ch / 4];
+	if (extra) {
+		uchar bit = ((uchar)1<<(8-extra));
+		if (extra >= (int)sizeof u.b) {
+			rprintf(FERROR, "Overflow in read_varint()\n");
+			exit_cleanup(RERR_STREAMIO);
+		}
+		readfd(f, u.b, extra);
+		u.b[extra] = ch & (bit-1);
+	} else
+		u.b[0] = ch;
+#if CAREFUL_ALIGNMENT
+	u.x = IVAL(u.b,0);
+#endif
+#if SIZEOF_INT32 > 4
+	if (u.x & (int32)0x80000000)
+		u.x |= ~(int32)0xffffffff;
+#endif
+	return u.x;
+}
+
+int64 read_varlong(int f, uchar min_bytes)
+{
+	union {
+	    char b[9];
+	    int64 x;
+	} u;
+	char b2[8];
+	int extra;
+
+#if SIZEOF_INT64 < 8
+	memset(u.b, 0, 8);
+#else
+	u.x = 0;
+#endif
+	readfd(f, b2, min_bytes);
+	memcpy(u.b, b2+1, min_bytes-1);
+	extra = int_byte_extra[CVAL(b2, 0) / 4];
+	if (extra) {
+		uchar bit = ((uchar)1<<(8-extra));
+		if (min_bytes + extra > (int)sizeof u.b) {
+			rprintf(FERROR, "Overflow in read_varlong()\n");
+			exit_cleanup(RERR_STREAMIO);
+		}
+		readfd(f, u.b + min_bytes - 1, extra);
+		u.b[min_bytes + extra - 1] = CVAL(b2, 0) & (bit-1);
+#if SIZEOF_INT64 < 8
+		if (min_bytes + extra > 5 || u.b[4] || CVAL(u.b,3) & 0x80) {
+			rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
+			exit_cleanup(RERR_UNSUPPORTED);
+		}
+#endif
+	} else
+		u.b[min_bytes + extra - 1] = CVAL(b2, 0);
+#if SIZEOF_INT64 < 8
+	u.x = IVAL(u.b,0);
+#elif CAREFUL_ALIGNMENT
+	u.x = IVAL(u.b,0) | (((int64)IVAL(u.b,4))<<32);
+#endif
+	return u.x;
 }
 
 int64 read_longint(int f)
 {
-	extern int remote_version;
-	int64 ret;
-	char b[8];
-	ret = read_int(f);
+#if SIZEOF_INT64 >= 8
+	char b[9];
+#endif
+	int32 num = read_int(f);
 
-	if ((int32)ret != (int32)0xffffffff) {
-		return ret;
-	}
+	if (num != (int32)0xffffffff)
+		return num;
 
-#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
-	if (remote_version >= 16) {
-		readfd(f,b,8);
-		ret = IVAL(b,0) | (((int64)IVAL(b,4))<<32);
-	}
+	readfd(f, b, 8);
+	return IVAL(b,0) | (((int64)IVAL(b,4))<<32);
 #endif
-
-	return ret;
 }
 
-void read_buf(int f,char *buf,size_t len)
+void read_buf(int f, char *buf, size_t len)
 {
 	readfd(f,buf,len);
 }
 
-void read_sbuf(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;
 }
 
-/* write len bytes to fd */
-static void writefd_unbuffered(int fd,char *buf,size_t len)
+int read_vstring(int f, char *buf, int bufsize)
 {
-	int total = 0;
-	fd_set w_fds, r_fds;
-	int fd_count, count;
-	struct timeval tv;
+	int len = read_byte(f);
 
-	err_list_push();
+	if (len & 0x80)
+		len = (len & ~0x80) * 0x100 + read_byte(f);
 
-	no_flush++;
+	if (len >= bufsize) {
+		rprintf(FERROR, "over-long vstring received (%d > %d)\n",
+			len, bufsize - 1);
+		return -1;
+	}
 
-	while (total < len) {
-		FD_ZERO(&w_fds);
-		FD_ZERO(&r_fds);
-		FD_SET(fd,&w_fds);
-		fd_count = fd;
+	if (len)
+		readfd(f, buf, len);
+	buf[len] = '\0';
+	return len;
+}
 
-		if (io_error_fd != -1) {
-			FD_SET(io_error_fd,&r_fds);
-			if (io_error_fd > fd_count) 
-				fd_count = io_error_fd;
-		}
+/* 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)
+{
+	int32 max_blength = protocol_version < 30 ? OLD_MAX_BLOCK_SIZE : MAX_BLOCK_SIZE;
+	sum->count = read_int(f);
+	if (sum->count < 0) {
+		rprintf(FERROR, "Invalid checksum count %ld [%s]\n",
+			(long)sum->count, who_am_i());
+		exit_cleanup(RERR_PROTOCOL);
+	}
+	sum->blength = read_int(f);
+	if (sum->blength < 0 || sum->blength > max_blength) {
+		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 > MAX_DIGEST_LEN) {
+		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);
+	}
+}
 
-		tv.tv_sec = io_timeout?io_timeout:SELECT_TIMEOUT;
-		tv.tv_usec = 0;
+/* 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;
 
-		errno = 0;
+	if (sum == NULL)
+		sum = &null_sum;
 
-		count = select(fd_count+1,
-			       io_error_fd != -1?&r_fds:NULL,
-			       &w_fds,NULL,
-			       &tv);
+	write_int(f, sum->count);
+	write_int(f, sum->blength);
+	if (protocol_version >= 27)
+		write_int(f, sum->s2length);
+	write_int(f, sum->remainder);
+}
 
-		if (count == 0) {
-			check_timeout();
-		}
+/**
+ * Sleep after writing to limit I/O bandwidth usage.
+ *
+ * @todo Rather than sleeping after each write, it might be better to
+ * use some kind of averaging.  The current algorithm seems to always
+ * 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)
+{
+	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_writemax)
+		return;
+
+	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;
+	}
+
+	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 fd, looping as necessary to get
+ * the job done and also (in certain circumstances) 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. */
+static void writefd_unbuffered(int fd, const char *buf, size_t len)
+{
+	size_t n, total = 0;
+	fd_set w_fds, r_fds, e_fds;
+	int maxfd, count, cnt, using_r_fds;
+	int defer_inc = 0;
+	struct timeval tv;
+
+	if (no_flush++)
+		defer_forwarding_messages++, defer_inc++;
+
+	while (total < len) {
+		FD_ZERO(&w_fds);
+		FD_SET(fd, &w_fds);
+		FD_ZERO(&e_fds);
+		FD_SET(fd, &e_fds);
+		maxfd = fd;
+
+		if (msg_fd_in >= 0) {
+			FD_ZERO(&r_fds);
+			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;
+
+		tv.tv_sec = select_timeout;
+		tv.tv_usec = 0;
+
+		errno = 0;
+		count = select(maxfd + 1, using_r_fds ? &r_fds : NULL,
+			       &w_fds, &e_fds, &tv);
 
 		if (count <= 0) {
-			if (errno == EBADF) {
+			if (count < 0 && errno == EBADF)
 				exit_cleanup(RERR_SOCKETIO);
-			}
+			check_timeout();
 			continue;
 		}
 
-		if (io_error_fd != -1 && FD_ISSET(io_error_fd, &r_fds)) {
-			read_error_fd();
-		}
+		/*if (FD_ISSET(fd, &e_fds))
+			rprintf(FINFO, "select exception on fd %d\n", fd); */
 
-		if (FD_ISSET(fd, &w_fds)) {
-			int ret, n = len-total;
-			ret = write(fd,buf+total,n);
+		if (using_r_fds && FD_ISSET(msg_fd_in, &r_fds))
+			read_msg_fd();
 
-			if (ret == -1 && errno == EINTR) {
-				continue;
-			}
+		if (!FD_ISSET(fd, &w_fds))
+			continue;
 
-			if (ret == -1 && 
-			    (errno == EWOULDBLOCK || errno == EAGAIN)) {
-				msleep(1);
-				continue;
+		n = len - total;
+		if (bwlimit_writemax && n > bwlimit_writemax)
+			n = bwlimit_writemax;
+		cnt = write(fd, buf + total, n);
+
+		if (cnt <= 0) {
+			if (cnt < 0) {
+				if (errno == EINTR)
+					continue;
+				if (errno == EWOULDBLOCK || errno == EAGAIN) {
+					msleep(1);
+					continue;
+				}
 			}
 
-			if (ret <= 0) {
-				rprintf(FERROR,
-					"error writing %d unbuffered bytes"
-					" - exiting: %s\n", len,
-					strerror(errno));
+			/* Don't try to write errors back across the stream. */
+			if (fd == sock_f_out)
+				io_end_multiplex_out();
+			/* Don't try to write errors down a failing msg pipe. */
+			if (am_server && fd == msg_fd_out)
 				exit_cleanup(RERR_STREAMIO);
+			rsyserr(FERROR, errno,
+				"writefd_unbuffered failed to write %ld bytes [%s]",
+				(long)len, who_am_i());
+			/* If the other side is sending us error messages, try
+			 * to grab any messages they sent before they died. */
+			while (!am_server && fd == sock_f_out && io_multiplexing_in) {
+				char buf[1024];
+				set_io_timeout(30);
+				ignore_timeout = 0;
+				readfd_unbuffered(sock_f_in, buf, sizeof buf);
 			}
+			exit_cleanup(RERR_STREAMIO);
+		}
+
+		total += cnt;
+		defer_forwarding_messages++, defer_inc++;
 
-			/* Sleep after writing to limit I/O bandwidth */
-			if (bwlimit)
-			{
-			    tv.tv_sec = 0;
-			    tv.tv_usec = ret * 1000 / bwlimit;
-			    while (tv.tv_usec > 1000000)
-			    {
-				tv.tv_sec++;
-				tv.tv_usec -= 1000000;
-			    }
-			    select(0, NULL, NULL, NULL, &tv);
- 			}
- 
-			total += ret;
-
-			if (io_timeout)
-				last_io = time(NULL);
+		if (fd == sock_f_out) {
+			if (io_timeout || am_generator)
+				last_io_out = time(NULL);
+			sleep_for_bwlimit(cnt);
 		}
 	}
 
 	no_flush--;
+	if (keep_defer_forwarding)
+		defer_inc--;
+	if (!(defer_forwarding_messages -= defer_inc) && !no_flush)
+		msg_flush();
 }
 
-
-static char *io_buffer;
-static int io_buffer_count;
-
-void io_start_buffering(int fd)
-{
-	if (io_buffer) return;
-	multiplex_out_fd = fd;
-	io_buffer = (char *)malloc(IO_BUFFER_SIZE);
-	if (!io_buffer) out_of_memory("writefd");
-	io_buffer_count = 0;
-}
-
-/* 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)
+int io_flush(int flush_it_all)
 {
-	char buffer[4096];
-	int n = len;
+	int flushed_something = 0;
 
-	SIVAL(buffer, 0, ((MPLEX_BASE + (int)code)<<24) + len);
+	if (no_flush)
+		return 0;
 
-	if (n > (sizeof(buffer)-4)) {
-		n = sizeof(buffer)-4;
+	if (iobuf_out_cnt) {
+		if (io_multiplexing_out)
+			mplex_write(sock_f_out, MSG_DATA, iobuf_out, iobuf_out_cnt, 0);
+		else
+			writefd_unbuffered(iobuf_f_out, iobuf_out, iobuf_out_cnt);
+		iobuf_out_cnt = 0;
+		flushed_something = 1;
 	}
 
-	memcpy(&buffer[4], buf, n);
-	writefd_unbuffered(fd, buffer, n+4);
-
-	len -= n;
-	buf += n;
-
-	if (len) {
-		writefd_unbuffered(fd, buf, len);
+	if (flush_it_all && !defer_forwarding_messages && msg_queue.head) {
+		msg_flush();
+		flushed_something = 1;
 	}
-}
-
-
-void io_flush(void)
-{
-	int fd = multiplex_out_fd;
 
-	err_list_push();
-
-	if (!io_buffer_count || 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;
+	return flushed_something;
 }
 
-
-/* XXX: fd is ignored, which seems a little strange. */
-void io_end_buffering(int fd)
+static void writefd(int fd, const char *buf, size_t len)
 {
-	io_flush();
-	if (!io_multiplexing_out) {
-		free(io_buffer);
-		io_buffer = NULL;
-	}
-}
+	if (fd == sock_f_out)
+		stats.total_written += len;
 
-static void writefd(int fd,char *buf,size_t len)
-{
-	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 != iobuf_f_out) {
 		writefd_unbuffered(fd, buf, len);
 		return;
 	}
 
 	while (len) {
-		int n = MIN(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, unsigned short x)
+{
+	char b[2];
+	b[0] = (char)x;
+	b[1] = (char)(x >> 8);
+	writefd(f, b, 2);
+}
 
-void write_int(int f,int32 x)
+void write_int(int f, int32 x)
 {
 	char b[4];
-	SIVAL(b,0,x);
-	writefd(f,b,4);
+	SIVAL(b, 0, x);
+	writefd(f, b, 4);
 }
 
+void write_varint(int f, int32 x)
+{
+	char b[5];
+	uchar bit;
+	int cnt = 4;
+
+	SIVAL(b, 1, x);
+
+	while (cnt > 1 && b[cnt] == 0)
+		cnt--;
+	bit = ((uchar)1<<(7-cnt+1));
+	if (CVAL(b, cnt) >= bit) {
+		cnt++;
+		*b = ~(bit-1);
+	} else if (cnt > 1)
+		*b = b[cnt] | ~(bit*2-1);
+	else
+		*b = b[cnt];
+
+	writefd(f, b, cnt);
+}
+
+void write_varlong(int f, int64 x, uchar min_bytes)
+{
+	char b[9];
+	uchar bit;
+	int cnt = 8;
+
+	SIVAL(b, 1, x);
+#if SIZEOF_INT64 >= 8
+	SIVAL(b, 5, x >> 32);
+#else
+	if (x <= 0x7FFFFFFF && x >= 0)
+		memset(b + 5, 0, 4);
+	else {
+		rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
+		exit_cleanup(RERR_UNSUPPORTED);
+	}
+#endif
+
+	while (cnt > min_bytes && b[cnt] == 0)
+		cnt--;
+	bit = ((uchar)1<<(7-cnt+min_bytes));
+	if (CVAL(b, cnt) >= bit) {
+		cnt++;
+		*b = ~(bit-1);
+	} else if (cnt > min_bytes)
+		*b = b[cnt] | ~(bit*2-1);
+	else
+		*b = b[cnt];
+
+	writefd(f, b, cnt);
+}
 
 /*
  * Note: int64 may actually be a 32-bit type if ./configure couldn't find any
@@ -574,111 +1684,245 @@ void write_int(int f,int32 x)
  */
 void write_longint(int f, int64 x)
 {
-	extern int remote_version;
-	char b[8];
+	char b[12], * const s = b+4;
 
-	if (remote_version < 16 || x <= 0x7FFFFFFF) {
-		write_int(f, (int)x);
+	SIVAL(s, 0, x);
+	if (x <= 0x7FFFFFFF && x >= 0) {
+		writefd(f, s, 4);
 		return;
 	}
 
-	write_int(f, (int32)0xFFFFFFFF);
-	SIVAL(b,0,(x&0xFFFFFFFF));
-	SIVAL(b,4,((x>>32)&0xFFFFFFFF));
-
-	writefd(f,b,8);
+#if SIZEOF_INT64 < 8
+	rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
+	exit_cleanup(RERR_UNSUPPORTED);
+#else
+	memset(b, 0xFF, 4);
+	SIVAL(s, 4, x >> 32);
+	writefd(f, b, 12);
+#endif
 }
 
-void write_buf(int f,char *buf,size_t len)
+void write_buf(int f, const char *buf, size_t len)
 {
 	writefd(f,buf,len);
 }
 
-/* write a string to the connection */
-static void write_sbuf(int f,char *buf)
+/** Write a string to the connection */
+void write_sbuf(int f, const char *buf)
 {
-	write_buf(f, buf, strlen(buf));
+	writefd(f, buf, strlen(buf));
 }
 
+void write_byte(int f, uchar c)
+{
+	writefd(f, (char *)&c, 1);
+}
 
-void write_byte(int f,unsigned char c)
+void write_vstring(int f, const char *str, int len)
 {
-	write_buf(f,(char *)&c,1);
+	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);
 }
 
+/* Send a file-list index using a byte-reduction method. */
+void write_ndx(int f, int32 ndx)
+{
+	static int32 prev_positive = -1, prev_negative = 1;
+	int32 diff, cnt = 0;
+	char b[6];
 
+	if (protocol_version < 30 || read_batch) {
+		write_int(f, ndx);
+		return;
+	}
 
-int read_line(int f, char *buf, size_t maxlen)
+	/* Send NDX_DONE as a single-byte 0 with no side effects.  Send
+	 * negative nums as a positive after sending a leading 0xFF. */
+	if (ndx >= 0) {
+		diff = ndx - prev_positive;
+		prev_positive = ndx;
+	} else if (ndx == NDX_DONE) {
+		*b = 0;
+		writefd(f, b, 1);
+		return;
+	} else {
+		b[cnt++] = (char)0xFF;
+		ndx = -ndx;
+		diff = ndx - prev_negative;
+		prev_negative = ndx;
+	}
+
+	/* A diff of 1 - 253 is sent as a one-byte diff; a diff of 254 - 32767
+	 * or 0 is sent as a 0xFE + a two-byte diff; otherwise we send 0xFE
+	 * & all 4 bytes of the (non-negative) num with the high-bit set. */
+	if (diff < 0xFE && diff > 0)
+		b[cnt++] = (char)diff;
+	else if (diff < 0 || diff > 0x7FFF) {
+		b[cnt++] = (char)0xFE;
+		b[cnt++] = (char)((ndx >> 24) | 0x80);
+		b[cnt++] = (char)ndx;
+		b[cnt++] = (char)(ndx >> 8);
+		b[cnt++] = (char)(ndx >> 16);
+	} else {
+		b[cnt++] = (char)0xFE;
+		b[cnt++] = (char)(diff >> 8);
+		b[cnt++] = (char)diff;
+	}
+	writefd(f, b, cnt);
+}
+
+/* Receive a file-list index using a byte-reduction method. */
+int32 read_ndx(int f)
 {
-	while (maxlen) {
+	static int32 prev_positive = -1, prev_negative = 1;
+	int32 *prev_ptr, num;
+	char b[4];
+
+	if (protocol_version < 30)
+		return read_int(f);
+
+	readfd(f, b, 1);
+	if (CVAL(b, 0) == 0xFF) {
+		readfd(f, b, 1);
+		prev_ptr = &prev_negative;
+	} else if (CVAL(b, 0) == 0)
+		return NDX_DONE;
+	else
+		prev_ptr = &prev_positive;
+	if (CVAL(b, 0) == 0xFE) {
+		readfd(f, b, 2);
+		if (CVAL(b, 0) & 0x80) {
+			b[3] = CVAL(b, 0) & ~0x80;
+			b[0] = b[1];
+			readfd(f, b+1, 2);
+			num = IVAL(b, 0);
+		} else
+			num = (UVAL(b,0)<<8) + UVAL(b,1) + *prev_ptr;
+	} else
+		num = UVAL(b, 0) + *prev_ptr;
+	*prev_ptr = num;
+	if (prev_ptr == &prev_negative)
+		num = -num;
+	return num;
+}
+
+/* Read a line of up to bufsiz-1 characters into buf.  Strips
+ * the (required) trailing newline and all carriage returns.
+ * Returns 1 for success; 0 for I/O error or truncation. */
+int read_line_old(int f, char *buf, size_t bufsiz)
+{
+	bufsiz--; /* leave room for the null */
+	while (bufsiz > 0) {
 		buf[0] = 0;
 		read_buf(f, buf, 1);
-		if (buf[0] == 0) return 0;
-		if (buf[0] == '\n') {
-			buf[0] = 0;
+		if (buf[0] == 0)
+			return 0;
+		if (buf[0] == '\n')
 			break;
-		}
 		if (buf[0] != '\r') {
 			buf++;
-			maxlen--;
+			bufsiz--;
 		}
 	}
-	if (maxlen == 0) {
-		*buf = 0;
-		return 0;
-	}
-
-	return 1;
+	*buf = '\0';
+	return bufsiz > 0;
 }
 
-
 void io_printf(int fd, const char *format, ...)
 {
-	va_list ap;  
-	char buf[1024];
+	va_list ap;
+	char buf[BIGPATHBUFLEN];
 	int len;
-	
+
 	va_start(ap, format);
-	len = vsnprintf(buf, sizeof(buf), format, ap);
+	len = vsnprintf(buf, sizeof buf, format, ap);
 	va_end(ap);
 
-	if (len < 0) exit_cleanup(RERR_STREAMIO);
+	if (len < 0)
+		exit_cleanup(RERR_STREAMIO);
+
+	if (len > (int)sizeof buf) {
+		rprintf(FERROR, "io_printf() was too long for the buffer.\n");
+		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(fd);
+	io_flush(NORMAL_FLUSH);
+	io_start_buffering_out(sock_f_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(sock_f_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, const char *buf, size_t len, int convert)
 {
-	if (!io_multiplexing_out) return 0;
-
-	io_flush();
+	if (!io_multiplexing_out)
+		return 0;
+	io_flush(NORMAL_FLUSH);
 	stats.total_written += (len+4);
-	mplex_write(multiplex_out_fd, code, buf, len);
+	mplex_write(sock_f_out, code, buf, len, convert);
 	return 1;
 }
 
-/* stop output multiplexing */
-void io_multiplexing_close(void)
+void io_end_multiplex_in(void)
+{
+	io_multiplexing_in = 0;
+	io_end_buffering_in();
+}
+
+/** Stop output multiplexing. */
+void io_end_multiplex_out(void)
 {
 	io_multiplexing_out = 0;
+	io_end_buffering_out();
+}
+
+void start_write_batch(int 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);
+	if (protocol_version >= 30)
+		write_byte(batch_fd, inc_recurse);
+	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;
+}