Adding upstream version 3.2.7.upstream/3.2.7

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2460 insertions, 0 deletions

diff --git a/io.c b/io.c
new file mode 100644
index 0000000..a99ac0e
--- /dev/null
+++ b/io.c
@@ -0,0 +1,2460 @@
+/*
+ * 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) 2003-2022 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(). */
+
+#include "rsync.h"
+#include "ifuncs.h"
+#include "inums.h"
+
+/** 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_sender;
+extern int am_receiver;
+extern int am_generator;
+extern int local_server;
+extern int msgs2stderr;
+extern int inc_recurse;
+extern int io_error;
+extern int batch_fd;
+extern int eol_nulls;
+extern int flist_eof;
+extern int file_total;
+extern int file_old_total;
+extern int list_only;
+extern int read_batch;
+extern int compat_flags;
+extern int protect_args;
+extern int checksum_seed;
+extern int daemon_connection;
+extern int protocol_version;
+extern int remove_source_files;
+extern int preserve_hard_links;
+extern BOOL extra_flist_sending_enabled;
+extern BOOL flush_ok_after_signal;
+extern struct stats stats;
+extern time_t stop_at_utime;
+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 msgdone_cnt = 0;
+int forward_flist_data = 0;
+BOOL flist_receiving_enabled = False;
+
+/* Ignore an EOF error if non-zero. See whine_about_eof(). */
+int kluge_around_eof = 0;
+int got_kill_signal = -1; /* is set to 0 only after multiplexed I/O starts */
+
+int sock_f_in = -1;
+int sock_f_out = -1;
+
+int64 total_data_read = 0;
+int64 total_data_written = 0;
+
+char num_dev_ino_buf[4 + 8 + 8];
+
+static struct {
+	xbuf in, out, msg;
+	int in_fd;
+	int out_fd; /* Both "out" and "msg" go to this fd. */
+	int in_multiplexed;
+	unsigned out_empty_len;
+	size_t raw_data_header_pos;      /* in the out xbuf */
+	size_t raw_flushing_ends_before; /* in the out xbuf */
+	size_t raw_input_ends_before;    /* in the in xbuf */
+} iobuf = { .in_fd = -1, .out_fd = -1 };
+
+static time_t last_io_in;
+static time_t last_io_out;
+
+static int write_batch_monitor_in = -1;
+static int write_batch_monitor_out = -1;
+
+static int ff_forward_fd = -1;
+static int ff_reenable_multiplex = -1;
+static char ff_lastchar = '\0';
+static xbuf ff_xb = EMPTY_XBUF;
+#ifdef ICONV_OPTION
+static xbuf iconv_buf = EMPTY_XBUF;
+#endif
+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 */
+};
+
+/* Our I/O buffers are sized with no bits on in the lowest byte of the "size"
+ * (indeed, our rounding of sizes in 1024-byte units assures more than this).
+ * This allows the code that is storing bytes near the physical end of a
+ * circular buffer to temporarily reduce the buffer's size (in order to make
+ * some storing idioms easier), while also making it simple to restore the
+ * buffer's actual size when the buffer's "pos" wraps around to the start (we
+ * just round the buffer's size up again). */
+
+#define IOBUF_WAS_REDUCED(siz) ((siz) & 0xFF)
+#define IOBUF_RESTORE_SIZE(siz) (((siz) | 0xFF) + 1)
+
+#define IN_MULTIPLEXED (iobuf.in_multiplexed != 0)
+#define IN_MULTIPLEXED_AND_READY (iobuf.in_multiplexed > 0)
+#define OUT_MULTIPLEXED (iobuf.out_empty_len != 0)
+
+#define PIO_NEED_INPUT (1<<0) /* The *_NEED_* flags are mutually exclusive. */
+#define PIO_NEED_OUTROOM (1<<1)
+#define PIO_NEED_MSGROOM (1<<2)
+
+#define PIO_CONSUME_INPUT (1<<4) /* Must becombined with PIO_NEED_INPUT. */
+
+#define PIO_INPUT_AND_CONSUME (PIO_NEED_INPUT | PIO_CONSUME_INPUT)
+#define PIO_NEED_FLAGS (PIO_NEED_INPUT | PIO_NEED_OUTROOM | PIO_NEED_MSGROOM)
+
+#define REMOTE_OPTION_ERROR "rsync: on remote machine: -"
+#define REMOTE_OPTION_ERROR2 ": unknown option"
+
+#define FILESFROM_BUFLEN 2048
+
+enum festatus { FES_SUCCESS, FES_REDO, FES_NO_SEND };
+
+static flist_ndx_list redo_list, hlink_list;
+
+static void read_a_msg(void);
+static void drain_multiplex_messages(void);
+static void sleep_for_bwlimit(int bytes_written);
+
+static void check_timeout(BOOL allow_keepalive, int keepalive_flags)
+{
+	time_t t, chk;
+
+	/* On the receiving side, the generator is now the one that decides
+	 * when a timeout has occurred.  When it is sifting through a lot of
+	 * files looking for work, it will be sending keep-alive messages to
+	 * the sender, and even though the receiver won't be sending/receiving
+	 * anything (not even keep-alive messages), the successful writes to
+	 * the sender will keep things going.  If the receiver is actively
+	 * receiving data, it will ensure that the generator knows that it is
+	 * not idle by sending the generator keep-alive messages (since the
+	 * generator might be blocked trying to send checksums, it needs to
+	 * know that the receiver is active).  Thus, as long as one or the
+	 * other is successfully doing work, the generator will not timeout. */
+	if (!io_timeout)
+		return;
+
+	t = time(NULL);
+
+	if (allow_keepalive) {
+		/* This may put data into iobuf.msg w/o flushing. */
+		maybe_send_keepalive(t, keepalive_flags);
+	}
+
+	if (!last_io_in)
+		last_io_in = t;
+
+	if (am_receiver)
+		return;
+
+	chk = MAX(last_io_out, last_io_in);
+	if (t - chk >= io_timeout) {
+		if (am_server)
+			msgs2stderr = 1;
+		rprintf(FERROR, "[%s] io timeout after %d seconds -- exiting\n",
+			who_am_i(), (int)(t-chk));
+		exit_cleanup(RERR_TIMEOUT);
+	}
+}
+
+/* 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 NORETURN void whine_about_eof(BOOL allow_kluge)
+{
+	if (kluge_around_eof && allow_kluge) {
+		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);
+}
+
+/* Do a safe read, handling any needed looping and error handling.
+ * Returns the count of the bytes read, which will only be different
+ * from "len" if we encountered an EOF.  This routine is not used on
+ * the socket except very early in the transfer. */
+static size_t safe_read(int fd, char *buf, size_t len)
+{
+	size_t got = 0;
+
+	assert(fd != iobuf.in_fd);
+
+	while (1) {
+		struct timeval tv;
+		fd_set r_fds, e_fds;
+		int cnt;
+
+		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;
+
+		cnt = select(fd+1, &r_fds, NULL, &e_fds, &tv);
+		if (cnt <= 0) {
+			if (cnt < 0 && errno == EBADF) {
+				rsyserr(FERROR, errno, "safe_read select failed");
+				exit_cleanup(RERR_FILEIO);
+			}
+			check_timeout(1, MSK_ALLOW_FLUSH);
+			continue;
+		}
+
+		/*if (FD_ISSET(fd, &e_fds))
+			rprintf(FINFO, "select exception on fd %d\n", fd); */
+
+		if (FD_ISSET(fd, &r_fds)) {
+			ssize_t n = read(fd, buf + got, len - got);
+			if (DEBUG_GTE(IO, 2)) {
+				rprintf(FINFO, "[%s] safe_read(%d)=%" SIZE_T_FMT_MOD "d\n",
+					who_am_i(), fd, (SIZE_T_FMT_CAST)n);
+			}
+			if (n == 0)
+				break;
+			if (n < 0) {
+				if (errno == EINTR)
+					continue;
+				rsyserr(FERROR, errno, "safe_read failed to read %" SIZE_T_FMT_MOD "d bytes",
+					(SIZE_T_FMT_CAST)len);
+				exit_cleanup(RERR_STREAMIO);
+			}
+			if ((got += (size_t)n) == len)
+				break;
+		}
+	}
+
+	return got;
+}
+
+static const char *what_fd_is(int fd)
+{
+	static char buf[20];
+
+	if (fd == sock_f_out)
+		return "socket";
+	else if (fd == iobuf.out_fd)
+		return "message fd";
+	else if (fd == batch_fd)
+		return "batch file";
+	else {
+		snprintf(buf, sizeof buf, "fd %d", fd);
+		return buf;
+	}
+}
+
+/* Do a safe write, handling any needed looping and error handling.
+ * Returns only if everything was successfully written.  This routine
+ * is not used on the socket except very early in the transfer. */
+static void safe_write(int fd, const char *buf, size_t len)
+{
+	ssize_t n;
+
+	assert(fd != iobuf.out_fd);
+
+	n = write(fd, buf, len);
+	if ((size_t)n == len)
+		return;
+	if (n < 0) {
+		if (errno != EINTR && errno != EWOULDBLOCK && errno != EAGAIN) {
+		  write_failed:
+			rsyserr(FERROR, errno,
+				"safe_write failed to write %" SIZE_T_FMT_MOD "d bytes to %s",
+				(SIZE_T_FMT_CAST)len, what_fd_is(fd));
+			exit_cleanup(RERR_STREAMIO);
+		}
+	} else {
+		buf += n;
+		len -= n;
+	}
+
+	while (len) {
+		struct timeval tv;
+		fd_set w_fds;
+		int cnt;
+
+		FD_ZERO(&w_fds);
+		FD_SET(fd, &w_fds);
+		tv.tv_sec = select_timeout;
+		tv.tv_usec = 0;
+
+		cnt = select(fd + 1, NULL, &w_fds, NULL, &tv);
+		if (cnt <= 0) {
+			if (cnt < 0 && errno == EBADF) {
+				rsyserr(FERROR, errno, "safe_write select failed on %s", what_fd_is(fd));
+				exit_cleanup(RERR_FILEIO);
+			}
+			if (io_timeout)
+				maybe_send_keepalive(time(NULL), MSK_ALLOW_FLUSH);
+			continue;
+		}
+
+		if (FD_ISSET(fd, &w_fds)) {
+			n = write(fd, buf, len);
+			if (n < 0) {
+				if (errno == EINTR)
+					continue;
+				goto write_failed;
+			}
+			buf += n;
+			len -= n;
+		}
+	}
+}
+
+/* This is only called when files-from data is known to be available.  We read
+ * a chunk of data and put it into the output buffer. */
+static void forward_filesfrom_data(void)
+{
+	ssize_t len;
+
+	len = read(ff_forward_fd, ff_xb.buf + ff_xb.len, ff_xb.size - ff_xb.len);
+	if (len <= 0) {
+		if (len == 0 || errno != EINTR) {
+			/* Send end-of-file marker */
+			ff_forward_fd = -1;
+			write_buf(iobuf.out_fd, "\0\0", ff_lastchar ? 2 : 1);
+			free_xbuf(&ff_xb);
+			if (ff_reenable_multiplex >= 0)
+				io_start_multiplex_out(ff_reenable_multiplex);
+			free_implied_include_partial_string();
+		}
+		return;
+	}
+
+	if (DEBUG_GTE(IO, 2)) {
+		rprintf(FINFO, "[%s] files-from read=%" SIZE_T_FMT_MOD "d\n",
+			who_am_i(), (SIZE_T_FMT_CAST)len);
+	}
+
+#ifdef ICONV_OPTION
+	len += ff_xb.len;
+#endif
+
+	if (!eol_nulls) {
+		char *s = ff_xb.buf + len;
+		/* Transform CR and/or LF into '\0' */
+		while (s-- > ff_xb.buf) {
+			if (*s == '\n' || *s == '\r')
+				*s = '\0';
+		}
+	}
+
+	if (ff_lastchar)
+		ff_xb.pos = 0;
+	else {
+		char *s = ff_xb.buf;
+		/* Last buf ended with a '\0', so don't let this buf start with one. */
+		while (len && *s == '\0')
+			s++, len--;
+		ff_xb.pos = s - ff_xb.buf;
+	}
+
+#ifdef ICONV_OPTION
+	if (filesfrom_convert && len) {
+		char *sob = ff_xb.buf + ff_xb.pos, *s = sob;
+		char *eob = sob + len;
+		int flags = ICB_INCLUDE_BAD | ICB_INCLUDE_INCOMPLETE | ICB_CIRCULAR_OUT;
+		if (ff_lastchar == '\0')
+			flags |= ICB_INIT;
+		/* Convert/send each null-terminated string separately, skipping empties. */
+		while (s != eob) {
+			if (*s++ == '\0') {
+				ff_xb.len = s - sob - 1;
+				add_implied_include(sob, 0);
+				if (iconvbufs(ic_send, &ff_xb, &iobuf.out, flags) < 0)
+					exit_cleanup(RERR_PROTOCOL); /* impossible? */
+				write_buf(iobuf.out_fd, s-1, 1); /* Send the '\0'. */
+				while (s != eob && *s == '\0')
+					s++;
+				sob = s;
+				ff_xb.pos = sob - ff_xb.buf;
+				flags |= ICB_INIT;
+			}
+		}
+
+		if ((ff_xb.len = s - sob) == 0)
+			ff_lastchar = '\0';
+		else {
+			/* Handle a partial string specially, saving any incomplete chars. */
+			implied_include_partial_string(sob, s);
+			flags &= ~ICB_INCLUDE_INCOMPLETE;
+			if (iconvbufs(ic_send, &ff_xb, &iobuf.out, flags) < 0) {
+				if (errno == E2BIG)
+					exit_cleanup(RERR_PROTOCOL); /* impossible? */
+				if (ff_xb.pos)
+					memmove(ff_xb.buf, ff_xb.buf + ff_xb.pos, ff_xb.len);
+			}
+			ff_lastchar = 'x'; /* Anything non-zero. */
+		}
+	} else
+#endif
+
+	if (len) {
+		char *f = ff_xb.buf + ff_xb.pos;
+		char *t = ff_xb.buf;
+		char *eob = f + len;
+		char *cur = t;
+		/* Eliminate any multi-'\0' runs. */
+		while (f != eob) {
+			if (!(*t++ = *f++)) {
+				add_implied_include(cur, 0);
+				cur = t;
+				while (f != eob && *f == '\0')
+					f++;
+			}
+		}
+		implied_include_partial_string(cur, t);
+		ff_lastchar = f[-1];
+		if ((len = t - ff_xb.buf) != 0) {
+			/* This will not circle back to perform_io() because we only get
+			 * called when there is plenty of room in the output buffer. */
+			write_buf(iobuf.out_fd, ff_xb.buf, len);
+		}
+	}
+}
+
+void reduce_iobuf_size(xbuf *out, size_t new_size)
+{
+	if (new_size < out->size) {
+		/* Avoid weird buffer interactions by only outputting this to stderr. */
+		if (msgs2stderr == 1 && DEBUG_GTE(IO, 4)) {
+			const char *name = out == &iobuf.out ? "iobuf.out"
+					 : out == &iobuf.msg ? "iobuf.msg"
+					 : NULL;
+			if (name) {
+				rprintf(FINFO, "[%s] reduced size of %s (-%d)\n",
+					who_am_i(), name, (int)(out->size - new_size));
+			}
+		}
+		out->size = new_size;
+	}
+}
+
+void restore_iobuf_size(xbuf *out)
+{
+	if (IOBUF_WAS_REDUCED(out->size)) {
+		size_t new_size = IOBUF_RESTORE_SIZE(out->size);
+		/* Avoid weird buffer interactions by only outputting this to stderr. */
+		if (msgs2stderr == 1 && DEBUG_GTE(IO, 4)) {
+			const char *name = out == &iobuf.out ? "iobuf.out"
+					 : out == &iobuf.msg ? "iobuf.msg"
+					 : NULL;
+			if (name) {
+				rprintf(FINFO, "[%s] restored size of %s (+%d)\n",
+					who_am_i(), name, (int)(new_size - out->size));
+			}
+		}
+		out->size = new_size;
+	}
+}
+
+static void handle_kill_signal(BOOL flush_ok)
+{
+	got_kill_signal = -1;
+	flush_ok_after_signal = flush_ok;
+	exit_cleanup(RERR_SIGNAL);
+}
+
+/* Perform buffered input and/or output until specified conditions are met.
+ * When given a "needed" read or write request, this returns without doing any
+ * I/O if the needed input bytes or write space is already available.  Once I/O
+ * is needed, this will try to do whatever reading and/or writing is currently
+ * possible, up to the maximum buffer allowances, no matter if this is a read
+ * or write request.  However, the I/O stops as soon as the required input
+ * bytes or output space is available.  If this is not a read request, the
+ * routine may also do some advantageous reading of messages from a multiplexed
+ * input source (which ensures that we don't jam up with everyone in their
+ * "need to write" code and nobody reading the accumulated data that would make
+ * writing possible).
+ *
+ * The iobuf.in, .out and .msg buffers are all circular.  Callers need to be
+ * aware that some data copies will need to be split when the bytes wrap around
+ * from the end to the start.  In order to help make writing into the output
+ * buffers easier for some operations (such as the use of SIVAL() into the
+ * buffer) a buffer may be temporarily shortened by a small amount, but the
+ * original size will be automatically restored when the .pos wraps to the
+ * start.  See also the 3 raw_* iobuf vars that are used in the handling of
+ * MSG_DATA bytes as they are read-from/written-into the buffers.
+ *
+ * When writing, we flush data in the following priority order:
+ *
+ * 1. Finish writing any in-progress MSG_DATA sequence from iobuf.out.
+ *
+ * 2. Write out all the messages from the message buf (if iobuf.msg is active).
+ *    Yes, this means that a PIO_NEED_OUTROOM call will completely flush any
+ *    messages before getting to the iobuf.out flushing (except for rule 1).
+ *
+ * 3. Write out the raw data from iobuf.out, possibly filling in the multiplexed
+ *    MSG_DATA header that was pre-allocated (when output is multiplexed).
+ *
+ * TODO:  items for possible future work:
+ *
+ *    - Make this routine able to read the generator-to-receiver batch flow?
+ *
+ * Unlike the old routines that this replaces, it is OK to read ahead as far as
+ * we can because the read_a_msg() routine now reads its bytes out of the input
+ * buffer.  In the old days, only raw data was in the input buffer, and any
+ * unused raw data in the buf would prevent the reading of socket data. */
+static char *perform_io(size_t needed, int flags)
+{
+	fd_set r_fds, e_fds, w_fds;
+	struct timeval tv;
+	int cnt, max_fd;
+	size_t empty_buf_len = 0;
+	xbuf *out;
+	char *data;
+
+	if (iobuf.in.len == 0 && iobuf.in.pos != 0) {
+		if (iobuf.raw_input_ends_before)
+			iobuf.raw_input_ends_before -= iobuf.in.pos;
+		iobuf.in.pos = 0;
+	}
+
+	switch (flags & PIO_NEED_FLAGS) {
+	case PIO_NEED_INPUT:
+		/* We never resize the circular input buffer. */
+		if (iobuf.in.size < needed) {
+			rprintf(FERROR, "need to read %" SIZE_T_FMT_MOD "d bytes,"
+					" iobuf.in.buf is only %" SIZE_T_FMT_MOD "d bytes.\n",
+				(SIZE_T_FMT_CAST)needed, (SIZE_T_FMT_CAST)iobuf.in.size);
+			exit_cleanup(RERR_PROTOCOL);
+		}
+
+		if (msgs2stderr == 1 && DEBUG_GTE(IO, 3)) {
+			rprintf(FINFO, "[%s] perform_io(%" SIZE_T_FMT_MOD "d, %sinput)\n",
+				who_am_i(), (SIZE_T_FMT_CAST)needed, flags & PIO_CONSUME_INPUT ? "consume&" : "");
+		}
+		break;
+
+	case PIO_NEED_OUTROOM:
+		/* We never resize the circular output buffer. */
+		if (iobuf.out.size - iobuf.out_empty_len < needed) {
+			fprintf(stderr, "need to write %" SIZE_T_FMT_MOD "d bytes,"
+					" iobuf.out.buf is only %" SIZE_T_FMT_MOD "d bytes.\n",
+				(SIZE_T_FMT_CAST)needed, (SIZE_T_FMT_CAST)(iobuf.out.size - iobuf.out_empty_len));
+			exit_cleanup(RERR_PROTOCOL);
+		}
+
+		if (msgs2stderr == 1 && DEBUG_GTE(IO, 3)) {
+			rprintf(FINFO, "[%s] perform_io(%" SIZE_T_FMT_MOD "d,"
+				       " outroom) needs to flush %" SIZE_T_FMT_MOD "d\n",
+				who_am_i(), (SIZE_T_FMT_CAST)needed,
+				iobuf.out.len + needed > iobuf.out.size
+				? (SIZE_T_FMT_CAST)(iobuf.out.len + needed - iobuf.out.size) : (SIZE_T_FMT_CAST)0);
+		}
+		break;
+
+	case PIO_NEED_MSGROOM:
+		/* We never resize the circular message buffer. */
+		if (iobuf.msg.size < needed) {
+			fprintf(stderr, "need to write %" SIZE_T_FMT_MOD "d bytes,"
+					" iobuf.msg.buf is only %" SIZE_T_FMT_MOD "d bytes.\n",
+				(SIZE_T_FMT_CAST)needed, (SIZE_T_FMT_CAST)iobuf.msg.size);
+			exit_cleanup(RERR_PROTOCOL);
+		}
+
+		if (msgs2stderr == 1 && DEBUG_GTE(IO, 3)) {
+			rprintf(FINFO, "[%s] perform_io(%" SIZE_T_FMT_MOD "d,"
+				       " msgroom) needs to flush %" SIZE_T_FMT_MOD "d\n",
+				who_am_i(), (SIZE_T_FMT_CAST)needed,
+				iobuf.msg.len + needed > iobuf.msg.size
+				? (SIZE_T_FMT_CAST)(iobuf.msg.len + needed - iobuf.msg.size) : (SIZE_T_FMT_CAST)0);
+		}
+		break;
+
+	case 0:
+		if (msgs2stderr == 1 && DEBUG_GTE(IO, 3)) {
+			rprintf(FINFO, "[%s] perform_io(%" SIZE_T_FMT_MOD "d, %d)\n",
+				who_am_i(), (SIZE_T_FMT_CAST)needed, flags);
+		}
+		break;
+
+	default:
+		exit_cleanup(RERR_UNSUPPORTED);
+	}
+
+	while (1) {
+		switch (flags & PIO_NEED_FLAGS) {
+		case PIO_NEED_INPUT:
+			if (iobuf.in.len >= needed)
+				goto double_break;
+			break;
+		case PIO_NEED_OUTROOM:
+			/* Note that iobuf.out_empty_len doesn't factor into this check
+			 * because iobuf.out.len already holds any needed header len. */
+			if (iobuf.out.len + needed <= iobuf.out.size)
+				goto double_break;
+			break;
+		case PIO_NEED_MSGROOM:
+			if (iobuf.msg.len + needed <= iobuf.msg.size)
+				goto double_break;
+			break;
+		}
+
+		max_fd = -1;
+
+		FD_ZERO(&r_fds);
+		FD_ZERO(&e_fds);
+		if (iobuf.in_fd >= 0 && iobuf.in.size - iobuf.in.len) {
+			if (!read_batch || batch_fd >= 0) {
+				FD_SET(iobuf.in_fd, &r_fds);
+				FD_SET(iobuf.in_fd, &e_fds);
+			}
+			if (iobuf.in_fd > max_fd)
+				max_fd = iobuf.in_fd;
+		}
+
+		/* Only do more filesfrom processing if there is enough room in the out buffer. */
+		if (ff_forward_fd >= 0 && iobuf.out.size - iobuf.out.len > FILESFROM_BUFLEN*2) {
+			FD_SET(ff_forward_fd, &r_fds);
+			if (ff_forward_fd > max_fd)
+				max_fd = ff_forward_fd;
+		}
+
+		FD_ZERO(&w_fds);
+		if (iobuf.out_fd >= 0) {
+			if (iobuf.raw_flushing_ends_before
+			 || (!iobuf.msg.len && iobuf.out.len > iobuf.out_empty_len && !(flags & PIO_NEED_MSGROOM))) {
+				if (OUT_MULTIPLEXED && !iobuf.raw_flushing_ends_before) {
+					/* The iobuf.raw_flushing_ends_before value can point off the end
+					 * of the iobuf.out buffer for a while, for easier subtracting. */
+					iobuf.raw_flushing_ends_before = iobuf.out.pos + iobuf.out.len;
+
+					SIVAL(iobuf.out.buf + iobuf.raw_data_header_pos, 0,
+					      ((MPLEX_BASE + (int)MSG_DATA)<<24) + iobuf.out.len - 4);
+
+					if (msgs2stderr == 1 && DEBUG_GTE(IO, 1)) {
+						rprintf(FINFO, "[%s] send_msg(%d, %" SIZE_T_FMT_MOD "d)\n",
+							who_am_i(), (int)MSG_DATA, (SIZE_T_FMT_CAST)iobuf.out.len - 4);
+					}
+
+					/* reserve room for the next MSG_DATA header */
+					iobuf.raw_data_header_pos = iobuf.raw_flushing_ends_before;
+					if (iobuf.raw_data_header_pos >= iobuf.out.size)
+						iobuf.raw_data_header_pos -= iobuf.out.size;
+					else if (iobuf.raw_data_header_pos + 4 > iobuf.out.size) {
+						/* The 4-byte header won't fit at the end of the buffer,
+						 * so we'll temporarily reduce the output buffer's size
+						 * and put the header at the start of the buffer. */
+						reduce_iobuf_size(&iobuf.out, iobuf.raw_data_header_pos);
+						iobuf.raw_data_header_pos = 0;
+					}
+					/* Yes, it is possible for this to make len > size for a while. */
+					iobuf.out.len += 4;
+				}
+
+				empty_buf_len = iobuf.out_empty_len;
+				out = &iobuf.out;
+			} else if (iobuf.msg.len) {
+				empty_buf_len = 0;
+				out = &iobuf.msg;
+			} else
+				out = NULL;
+			if (out) {
+				FD_SET(iobuf.out_fd, &w_fds);
+				if (iobuf.out_fd > max_fd)
+					max_fd = iobuf.out_fd;
+			}
+		} else
+			out = NULL;
+
+		if (max_fd < 0) {
+			switch (flags & PIO_NEED_FLAGS) {
+			case PIO_NEED_INPUT:
+				iobuf.in.len = 0;
+				if (kluge_around_eof == 2)
+					exit_cleanup(0);
+				if (iobuf.in_fd == -2)
+					whine_about_eof(True);
+				rprintf(FERROR, "error in perform_io: no fd for input.\n");
+				exit_cleanup(RERR_PROTOCOL);
+			case PIO_NEED_OUTROOM:
+			case PIO_NEED_MSGROOM:
+				msgs2stderr = 1;
+				drain_multiplex_messages();
+				if (iobuf.out_fd == -2)
+					whine_about_eof(True);
+				rprintf(FERROR, "error in perform_io: no fd for output.\n");
+				exit_cleanup(RERR_PROTOCOL);
+			default:
+				/* No stated needs, so I guess this is OK. */
+				break;
+			}
+			break;
+		}
+
+		if (got_kill_signal > 0)
+			handle_kill_signal(True);
+
+		if (extra_flist_sending_enabled) {
+			if (file_total - file_old_total < MAX_FILECNT_LOOKAHEAD && IN_MULTIPLEXED_AND_READY)
+				tv.tv_sec = 0;
+			else {
+				extra_flist_sending_enabled = False;
+				tv.tv_sec = select_timeout;
+			}
+		} else
+			tv.tv_sec = select_timeout;
+		tv.tv_usec = 0;
+
+		cnt = select(max_fd + 1, &r_fds, &w_fds, &e_fds, &tv);
+
+		if (cnt <= 0) {
+			if (cnt < 0 && errno == EBADF) {
+				msgs2stderr = 1;
+				exit_cleanup(RERR_SOCKETIO);
+			}
+			if (extra_flist_sending_enabled) {
+				extra_flist_sending_enabled = False;
+				send_extra_file_list(sock_f_out, -1);
+				extra_flist_sending_enabled = !flist_eof;
+			} else
+				check_timeout((flags & PIO_NEED_INPUT) != 0, 0);
+			FD_ZERO(&r_fds); /* Just in case... */
+			FD_ZERO(&w_fds);
+		}
+
+		if (iobuf.in_fd >= 0 && FD_ISSET(iobuf.in_fd, &r_fds)) {
+			size_t len, pos = iobuf.in.pos + iobuf.in.len;
+			ssize_t n;
+			if (pos >= iobuf.in.size) {
+				pos -= iobuf.in.size;
+				len = iobuf.in.size - iobuf.in.len;
+			} else
+				len = iobuf.in.size - pos;
+			if ((n = read(iobuf.in_fd, iobuf.in.buf + pos, len)) <= 0) {
+				if (n == 0) {
+					/* Signal that input has become invalid. */
+					if (!read_batch || batch_fd < 0 || am_generator)
+						iobuf.in_fd = -2;
+					batch_fd = -1;
+					continue;
+				}
+				if (errno == EINTR || errno == EWOULDBLOCK || errno == EAGAIN)
+					n = 0;
+				else {
+					/* Don't write errors on a dead socket. */
+					if (iobuf.in_fd == sock_f_in) {
+						if (am_sender)
+							msgs2stderr = 1;
+						rsyserr(FERROR_SOCKET, errno, "read error");
+					} else
+						rsyserr(FERROR, errno, "read error");
+					exit_cleanup(RERR_SOCKETIO);
+				}
+			}
+			if (msgs2stderr == 1 && DEBUG_GTE(IO, 2)) {
+				rprintf(FINFO, "[%s] recv=%" SIZE_T_FMT_MOD "d\n",
+					who_am_i(), (SIZE_T_FMT_CAST)n);
+			}
+
+			if (io_timeout) {
+				last_io_in = time(NULL);
+				if (io_timeout && flags & PIO_NEED_INPUT)
+					maybe_send_keepalive(last_io_in, 0);
+			}
+			stats.total_read += n;
+
+			iobuf.in.len += n;
+		}
+
+		if (stop_at_utime && time(NULL) >= stop_at_utime) {
+			rprintf(FERROR, "stopping at requested limit\n");
+			exit_cleanup(RERR_TIMEOUT);
+		}
+
+		if (out && FD_ISSET(iobuf.out_fd, &w_fds)) {
+			size_t len = iobuf.raw_flushing_ends_before ? iobuf.raw_flushing_ends_before - out->pos : out->len;
+			ssize_t n;
+
+			if (bwlimit_writemax && len > bwlimit_writemax)
+				len = bwlimit_writemax;
+
+			if (out->pos + len > out->size)
+				len = out->size - out->pos;
+			if ((n = write(iobuf.out_fd, out->buf + out->pos, len)) <= 0) {
+				if (errno == EINTR || errno == EWOULDBLOCK || errno == EAGAIN)
+					n = 0;
+				else {
+					/* Don't write errors on a dead socket. */
+					msgs2stderr = 1;
+					iobuf.out_fd = -2;
+					iobuf.out.len = iobuf.msg.len = iobuf.raw_flushing_ends_before = 0;
+					rsyserr(FERROR_SOCKET, errno, "write error");
+					drain_multiplex_messages();
+					exit_cleanup(RERR_SOCKETIO);
+				}
+			}
+			if (msgs2stderr == 1 && DEBUG_GTE(IO, 2)) {
+				rprintf(FINFO, "[%s] %s sent=%" SIZE_T_FMT_MOD "d\n",
+					who_am_i(), out == &iobuf.out ? "out" : "msg", (SIZE_T_FMT_CAST)n);
+			}
+
+			if (io_timeout)
+				last_io_out = time(NULL);
+			stats.total_written += n;
+
+			if (bwlimit_writemax)
+				sleep_for_bwlimit(n);
+
+			if ((out->pos += n) == out->size) {
+				if (iobuf.raw_flushing_ends_before)
+					iobuf.raw_flushing_ends_before -= out->size;
+				out->pos = 0;
+				restore_iobuf_size(out);
+			} else if (out->pos == iobuf.raw_flushing_ends_before)
+				iobuf.raw_flushing_ends_before = 0;
+			if ((out->len -= n) == empty_buf_len) {
+				out->pos = 0;
+				restore_iobuf_size(out);
+				if (empty_buf_len)
+					iobuf.raw_data_header_pos = 0;
+			}
+		}
+
+		if (got_kill_signal > 0)
+			handle_kill_signal(True);
+
+		/* We need to help prevent deadlock by doing what reading
+		 * we can whenever we are here trying to write. */
+		if (IN_MULTIPLEXED_AND_READY && !(flags & PIO_NEED_INPUT)) {
+			while (!iobuf.raw_input_ends_before && iobuf.in.len > 512)
+				read_a_msg();
+			if (flist_receiving_enabled && iobuf.in.len > 512)
+				wait_for_receiver(); /* generator only */
+		}
+
+		if (ff_forward_fd >= 0 && FD_ISSET(ff_forward_fd, &r_fds)) {
+			/* This can potentially flush all output and enable
+			 * multiplexed output, so keep this last in the loop
+			 * and be sure to not cache anything that would break
+			 * such a change. */
+			forward_filesfrom_data();
+		}
+	}
+  double_break:
+
+	if (got_kill_signal > 0)
+		handle_kill_signal(True);
+
+	data = iobuf.in.buf + iobuf.in.pos;
+
+	if (flags & PIO_CONSUME_INPUT) {
+		iobuf.in.len -= needed;
+		iobuf.in.pos += needed;
+		if (iobuf.in.pos == iobuf.raw_input_ends_before)
+			iobuf.raw_input_ends_before = 0;
+		if (iobuf.in.pos >= iobuf.in.size) {
+			iobuf.in.pos -= iobuf.in.size;
+			if (iobuf.raw_input_ends_before)
+				iobuf.raw_input_ends_before -= iobuf.in.size;
+		}
+	}
+
+	return data;
+}
+
+static void raw_read_buf(char *buf, size_t len)
+{
+	size_t pos = iobuf.in.pos;
+	char *data = perform_io(len, PIO_INPUT_AND_CONSUME);
+	if (iobuf.in.pos <= pos && len) {
+		size_t siz = len - iobuf.in.pos;
+		memcpy(buf, data, siz);
+		memcpy(buf + siz, iobuf.in.buf, iobuf.in.pos);
+	} else
+		memcpy(buf, data, len);
+}
+
+static int32 raw_read_int(void)
+{
+	char *data, buf[4];
+	if (iobuf.in.size - iobuf.in.pos >= 4)
+		data = perform_io(4, PIO_INPUT_AND_CONSUME);
+	else
+		raw_read_buf(data = buf, 4);
+	return IVAL(data, 0);
+}
+
+void noop_io_until_death(void)
+{
+	char buf[1024];
+
+	if (!iobuf.in.buf || !iobuf.out.buf || iobuf.in_fd < 0 || iobuf.out_fd < 0 || kluge_around_eof)
+		return;
+
+	/* If we're talking to a daemon over a socket, don't short-circuit this logic */
+	if (msgs2stderr && daemon_connection >= 0)
+		return;
+
+	kluge_around_eof = 2;
+	/* Setting an I/O timeout ensures that if something inexplicably weird
+	 * happens, we won't hang around forever. */
+	if (!io_timeout)
+		set_io_timeout(60);
+
+	while (1)
+		read_buf(iobuf.in_fd, buf, sizeof buf);
+}
+
+/* Buffer a message for the multiplexed output stream.  Is not used for (normal) MSG_DATA. */
+int send_msg(enum msgcode code, const char *buf, size_t len, int convert)
+{
+	char *hdr;
+	size_t needed, pos;
+	BOOL want_debug = DEBUG_GTE(IO, 1) && convert >= 0 && (msgs2stderr == 1 || code != MSG_INFO);
+
+	if (!OUT_MULTIPLEXED)
+		return 0;
+
+	if (want_debug) {
+		rprintf(FINFO, "[%s] send_msg(%d, %" SIZE_T_FMT_MOD "d)\n",
+			who_am_i(), (int)code, (SIZE_T_FMT_CAST)len);
+	}
+
+	/* When checking for enough free space for this message, we need to
+	 * make sure that there is space for the 4-byte header, plus we'll
+	 * assume that we may waste up to 3 bytes (if the header doesn't fit
+	 * at the physical end of the buffer). */
+#ifdef ICONV_OPTION
+	if (convert > 0 && ic_send == (iconv_t)-1)
+		convert = 0;
+	if (convert > 0) {
+		/* Ensuring double-size room leaves space for maximal conversion expansion. */
+		needed = len*2 + 4 + 3;
+	} else
+#endif
+		needed = len + 4 + 3;
+	if (iobuf.msg.len + needed > iobuf.msg.size) {
+		if (am_sender)
+			perform_io(needed, PIO_NEED_MSGROOM);
+		else { /* We sometimes allow the iobuf.msg size to increase to avoid a deadlock. */
+			size_t old_size = iobuf.msg.size;
+			restore_iobuf_size(&iobuf.msg);
+			realloc_xbuf(&iobuf.msg, iobuf.msg.size * 2);
+			if (iobuf.msg.pos + iobuf.msg.len > old_size)
+				memcpy(iobuf.msg.buf + old_size, iobuf.msg.buf, iobuf.msg.pos + iobuf.msg.len - old_size);
+		}
+	}
+
+	pos = iobuf.msg.pos + iobuf.msg.len; /* Must be set after any flushing. */
+	if (pos >= iobuf.msg.size)
+		pos -= iobuf.msg.size;
+	else if (pos + 4 > iobuf.msg.size) {
+		/* The 4-byte header won't fit at the end of the buffer,
+		 * so we'll temporarily reduce the message buffer's size
+		 * and put the header at the start of the buffer. */
+		reduce_iobuf_size(&iobuf.msg, pos);
+		pos = 0;
+	}
+	hdr = iobuf.msg.buf + pos;
+
+	iobuf.msg.len += 4; /* Allocate room for the coming header bytes. */
+
+#ifdef ICONV_OPTION
+	if (convert > 0) {
+		xbuf inbuf;
+
+		INIT_XBUF(inbuf, (char*)buf, len, (size_t)-1);
+
+		len = iobuf.msg.len;
+		iconvbufs(ic_send, &inbuf, &iobuf.msg,
+			  ICB_INCLUDE_BAD | ICB_INCLUDE_INCOMPLETE | ICB_CIRCULAR_OUT | ICB_INIT);
+		if (inbuf.len > 0) {
+			rprintf(FERROR, "overflowed iobuf.msg buffer in send_msg");
+			exit_cleanup(RERR_UNSUPPORTED);
+		}
+		len = iobuf.msg.len - len;
+	} else
+#endif
+	{
+		size_t siz;
+
+		if ((pos += 4) == iobuf.msg.size)
+			pos = 0;
+
+		/* Handle a split copy if we wrap around the end of the circular buffer. */
+		if (pos >= iobuf.msg.pos && (siz = iobuf.msg.size - pos) < len) {
+			memcpy(iobuf.msg.buf + pos, buf, siz);
+			memcpy(iobuf.msg.buf, buf + siz, len - siz);
+		} else
+			memcpy(iobuf.msg.buf + pos, buf, len);
+
+		iobuf.msg.len += len;
+	}
+
+	SIVAL(hdr, 0, ((MPLEX_BASE + (int)code)<<24) + len);
+
+	if (want_debug && convert > 0) {
+		rprintf(FINFO, "[%s] converted msg len=%" SIZE_T_FMT_MOD "d\n",
+			who_am_i(), (SIZE_T_FMT_CAST)len);
+	}
+
+	return 1;
+}
+
+void send_msg_int(enum msgcode code, int num)
+{
+	char numbuf[4];
+
+	if (DEBUG_GTE(IO, 1))
+		rprintf(FINFO, "[%s] send_msg_int(%d, %d)\n", who_am_i(), (int)code, num);
+
+	SIVAL(numbuf, 0, num);
+	send_msg(code, numbuf, 4, -1);
+}
+
+void send_msg_success(const char *fname, int num)
+{
+	if (local_server) {
+		STRUCT_STAT st;
+
+		if (DEBUG_GTE(IO, 1))
+			rprintf(FINFO, "[%s] send_msg_success(%d)\n", who_am_i(), num);
+
+		if (stat(fname, &st) < 0)
+			memset(&st, 0, sizeof (STRUCT_STAT));
+		SIVAL(num_dev_ino_buf, 0, num);
+		SIVAL64(num_dev_ino_buf, 4, st.st_dev);
+		SIVAL64(num_dev_ino_buf, 4+8, st.st_ino);
+		send_msg(MSG_SUCCESS, num_dev_ino_buf, sizeof num_dev_ino_buf, -1);
+	} else
+		send_msg_int(MSG_SUCCESS, num);
+}
+
+static void got_flist_entry_status(enum festatus status, int ndx)
+{
+	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) {
+			if (local_server)
+				send_msg(MSG_SUCCESS, num_dev_ino_buf, sizeof num_dev_ino_buf, -1);
+			else
+				send_msg_int(MSG_SUCCESS, ndx);
+		}
+		/* FALL THROUGH */
+	case FES_NO_SEND:
+#ifdef SUPPORT_HARD_LINKS
+		if (preserve_hard_links) {
+			struct file_struct *file = flist->files[ndx - flist->ndx_start];
+			if (F_IS_HLINKED(file)) {
+				if (status == FES_NO_SEND)
+					flist_ndx_push(&hlink_list, -2); /* indicates a failure follows */
+				flist_ndx_push(&hlink_list, ndx);
+				if (inc_recurse)
+					flist->in_progress++;
+			}
+		}
+#endif
+		break;
+	case FES_REDO:
+		if (read_batch) {
+			if (inc_recurse)
+				flist->in_progress++;
+			break;
+		}
+		if (inc_recurse)
+			flist->to_redo++;
+		flist_ndx_push(&redo_list, ndx);
+		break;
+	}
+}
+
+/* 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;
+	allowed_lull = (io_timeout + 1) / 2;
+
+	if (!io_timeout || allowed_lull > SELECT_TIMEOUT)
+		select_timeout = SELECT_TIMEOUT;
+	else
+		select_timeout = allowed_lull;
+
+	if (read_batch)
+		allowed_lull = 0;
+}
+
+static void check_for_d_option_error(const char *msg)
+{
+	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");
+	}
+}
+
+/* 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)
+{
+	while (1) {
+		/* TODO: tune these limits? */
+		int limit = active_bytecnt >= 128*1024 ? 10 : 50;
+		if (active_filecnt < limit)
+			break;
+		check_for_finished_files(itemizing, code, 0);
+		if (active_filecnt < limit)
+			break;
+		wait_for_receiver();
+	}
+
+	active_filecnt++;
+	active_bytecnt += F_LENGTH(cur_flist->files[ndx - cur_flist->ndx_start]);
+}
+
+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 making recv_file_list() call forward_filesfrom_data(), which
+ * will ensure that we forward data to the sender until we get some data
+ * for recv_file_list() to use. */
+void start_filesfrom_forwarding(int fd)
+{
+	if (protocol_version < 31 && OUT_MULTIPLEXED) {
+		/* Older protocols send the files-from data w/o packaging
+		 * it in multiplexed I/O packets, so temporarily switch
+		 * to buffered I/O to match this behavior. */
+		iobuf.msg.pos = iobuf.msg.len = 0; /* Be extra sure no messages go out. */
+		ff_reenable_multiplex = io_end_multiplex_out(MPLX_TO_BUFFERED);
+	}
+	ff_forward_fd = fd;
+
+	alloc_xbuf(&ff_xb, FILESFROM_BUFLEN);
+}
+
+/* Read a line into the "buf" buffer. */
+int read_line(int fd, char *buf, size_t bufsiz, int flags)
+{
+	char ch, *s, *eob;
+
+#ifdef ICONV_OPTION
+	if (flags & RL_CONVERT && iconv_buf.size < bufsiz)
+		realloc_xbuf(&iconv_buf, ROUND_UP_1024(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) {
+		/* We avoid read_byte() for files because files can return an EOF. */
+		if (fd == iobuf.in_fd)
+			ch = read_byte(fd);
+		else if (safe_read(fd, &ch, 1) == 0)
+			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 | ICB_INIT);
+		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, argc = 0, request_len = 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
+
+	argv = new_array(char *, maxargs);
+	if (mod_name && !protect_args)
+		argv[argc++] = "rsyncd";
+
+	if (request_p)
+		*request_p = NULL;
+
+	while (1) {
+		if (read_line(f_in, buf, bufsiz, rl_flags) == 0)
+			break;
+
+		if (argc == maxargs-1) {
+			maxargs += MAX_ARGS;
+			argv = realloc_array(argv, char *, maxargs);
+		}
+
+		if (dot_pos) {
+			if (request_p && request_len < 1024) {
+				int len = strlen(buf);
+				if (request_len)
+					request_p[0][request_len++] = ' ';
+				*request_p = realloc_array(*request_p, char, request_len + len + 1);
+				memcpy(*request_p + request_len, buf, len + 1);
+				request_len += len;
+			}
+			if (mod_name)
+				glob_expand_module(mod_name, buf, &argv, &argc, &maxargs);
+			else
+				glob_expand(buf, &argv, &argc, &maxargs);
+		} else {
+			p = strdup(buf);
+			argv[argc++] = p;
+			if (*p == '.' && p[1] == '\0')
+				dot_pos = argc;
+		}
+	}
+	argv[argc] = NULL;
+
+	glob_expand(NULL, NULL, NULL, NULL);
+
+	*argc_p = argc;
+	*argv_p = argv;
+}
+
+BOOL io_start_buffering_out(int f_out)
+{
+	if (msgs2stderr == 1 && DEBUG_GTE(IO, 2))
+		rprintf(FINFO, "[%s] io_start_buffering_out(%d)\n", who_am_i(), f_out);
+
+	if (iobuf.out.buf) {
+		if (iobuf.out_fd == -1)
+			iobuf.out_fd = f_out;
+		else
+			assert(f_out == iobuf.out_fd);
+		return False;
+	}
+
+	alloc_xbuf(&iobuf.out, ROUND_UP_1024(IO_BUFFER_SIZE * 2));
+	iobuf.out_fd = f_out;
+
+	return True;
+}
+
+BOOL io_start_buffering_in(int f_in)
+{
+	if (msgs2stderr == 1 && DEBUG_GTE(IO, 2))
+		rprintf(FINFO, "[%s] io_start_buffering_in(%d)\n", who_am_i(), f_in);
+
+	if (iobuf.in.buf) {
+		if (iobuf.in_fd == -1)
+			iobuf.in_fd = f_in;
+		else
+			assert(f_in == iobuf.in_fd);
+		return False;
+	}
+
+	alloc_xbuf(&iobuf.in, ROUND_UP_1024(IO_BUFFER_SIZE));
+	iobuf.in_fd = f_in;
+
+	return True;
+}
+
+void io_end_buffering_in(BOOL free_buffers)
+{
+	if (msgs2stderr == 1 && DEBUG_GTE(IO, 2)) {
+		rprintf(FINFO, "[%s] io_end_buffering_in(IOBUF_%s_BUFS)\n",
+			who_am_i(), free_buffers ? "FREE" : "KEEP");
+	}
+
+	if (free_buffers)
+		free_xbuf(&iobuf.in);
+	else
+		iobuf.in.pos = iobuf.in.len = 0;
+
+	iobuf.in_fd = -1;
+}
+
+void io_end_buffering_out(BOOL free_buffers)
+{
+	if (msgs2stderr == 1 && DEBUG_GTE(IO, 2)) {
+		rprintf(FINFO, "[%s] io_end_buffering_out(IOBUF_%s_BUFS)\n",
+			who_am_i(), free_buffers ? "FREE" : "KEEP");
+	}
+
+	io_flush(FULL_FLUSH);
+
+	if (free_buffers) {
+		free_xbuf(&iobuf.out);
+		free_xbuf(&iobuf.msg);
+	}
+
+	iobuf.out_fd = -1;
+}
+
+void maybe_flush_socket(int important)
+{
+	if (flist_eof && iobuf.out.buf && iobuf.out.len > iobuf.out_empty_len
+	 && (important || time(NULL) - last_io_out >= 5))
+		io_flush(NORMAL_FLUSH);
+}
+
+/* Older rsync versions used to send either a MSG_NOOP (protocol 30) or a
+ * raw-data-based keep-alive (protocol 29), both of which implied forwarding of
+ * the message through the sender.  Since the new timeout method does not need
+ * any forwarding, we just send an empty MSG_DATA message, which works with all
+ * rsync versions.  This avoids any message forwarding, and leaves the raw-data
+ * stream alone (since we can never be quite sure if that stream is in the
+ * right state for a keep-alive message). */
+void maybe_send_keepalive(time_t now, int flags)
+{
+	if (flags & MSK_ACTIVE_RECEIVER)
+		last_io_in = now; /* Fudge things when we're working hard on the files. */
+
+	/* Early in the transfer (before the receiver forks) the receiving side doesn't
+	 * care if it hasn't sent data in a while as long as it is receiving data (in
+	 * fact, a pre-3.1.0 rsync would die if we tried to send it a keep alive during
+	 * this time).  So, if we're an early-receiving proc, just return and let the
+	 * incoming data determine if we timeout. */
+	if (!am_sender && !am_receiver && !am_generator)
+		return;
+
+	if (now - last_io_out >= allowed_lull) {
+		/* The receiver is special:  it only sends keep-alive messages if it is
+		 * actively receiving data.  Otherwise, it lets the generator timeout. */
+		if (am_receiver && now - last_io_in >= io_timeout)
+			return;
+
+		if (!iobuf.msg.len && iobuf.out.len == iobuf.out_empty_len)
+			send_msg(MSG_DATA, "", 0, 0);
+		if (!(flags & MSK_ALLOW_FLUSH)) {
+			/* Let the caller worry about writing out the data. */
+		} else if (iobuf.msg.len)
+			perform_io(iobuf.msg.size - iobuf.msg.len + 1, PIO_NEED_MSGROOM);
+		else if (iobuf.out.len > iobuf.out_empty_len)
+			io_flush(NORMAL_FLUSH);
+	}
+}
+
+void start_flist_forward(int ndx)
+{
+	write_int(iobuf.out_fd, ndx);
+	forward_flist_data = 1;
+}
+
+void stop_flist_forward(void)
+{
+	forward_flist_data = 0;
+}
+
+/* Read a message from a multiplexed source. */
+static void read_a_msg(void)
+{
+	char data[BIGPATHBUFLEN];
+	int tag, val;
+	size_t msg_bytes;
+
+	/* This ensures that perform_io() does not try to do any message reading
+	 * until we've read all of the data for this message.  We should also
+	 * try to avoid calling things that will cause data to be written via
+	 * perform_io() prior to this being reset to 1. */
+	iobuf.in_multiplexed = -1;
+
+	tag = raw_read_int();
+
+	msg_bytes = tag & 0xFFFFFF;
+	tag = (tag >> 24) - MPLEX_BASE;
+
+	if (msgs2stderr == 1 && DEBUG_GTE(IO, 1)) {
+		rprintf(FINFO, "[%s] got msg=%d, len=%" SIZE_T_FMT_MOD "d\n",
+			who_am_i(), (int)tag, (SIZE_T_FMT_CAST)msg_bytes);
+	}
+
+	switch (tag) {
+	case MSG_DATA:
+		assert(iobuf.raw_input_ends_before == 0);
+		/* Though this does not yet read the data, we do mark where in
+		 * the buffer the msg data will end once it is read.  It is
+		 * possible that this points off the end of the buffer, in
+		 * which case the gradual reading of the input stream will
+		 * cause this value to wrap around and eventually become real. */
+		if (msg_bytes)
+			iobuf.raw_input_ends_before = iobuf.in.pos + msg_bytes;
+		iobuf.in_multiplexed = 1;
+		break;
+	case MSG_STATS:
+		if (msg_bytes != sizeof stats.total_read || !am_generator)
+			goto invalid_msg;
+		raw_read_buf((char*)&stats.total_read, sizeof stats.total_read);
+		iobuf.in_multiplexed = 1;
+		break;
+	case MSG_REDO:
+		if (msg_bytes != 4 || !am_generator)
+			goto invalid_msg;
+		val = raw_read_int();
+		iobuf.in_multiplexed = 1;
+		got_flist_entry_status(FES_REDO, val);
+		break;
+	case MSG_IO_ERROR:
+		if (msg_bytes != 4)
+			goto invalid_msg;
+		val = raw_read_int();
+		iobuf.in_multiplexed = 1;
+		io_error |= val;
+		if (am_receiver)
+			send_msg_int(MSG_IO_ERROR, val);
+		break;
+	case MSG_IO_TIMEOUT:
+		if (msg_bytes != 4 || am_server || am_generator)
+			goto invalid_msg;
+		val = raw_read_int();
+		iobuf.in_multiplexed = 1;
+		if (!io_timeout || io_timeout > val) {
+			if (INFO_GTE(MISC, 2))
+				rprintf(FINFO, "Setting --timeout=%d to match server\n", val);
+			set_io_timeout(val);
+		}
+		break;
+	case MSG_NOOP:
+		/* Support protocol-30 keep-alive method. */
+		if (msg_bytes != 0)
+			goto invalid_msg;
+		iobuf.in_multiplexed = 1;
+		if (am_sender)
+			maybe_send_keepalive(time(NULL), MSK_ALLOW_FLUSH);
+		break;
+	case MSG_DELETED:
+		if (msg_bytes >= sizeof data)
+			goto overflow;
+		if (am_generator) {
+			raw_read_buf(data, msg_bytes);
+			iobuf.in_multiplexed = 1;
+			send_msg(MSG_DELETED, data, msg_bytes, 1);
+			break;
+		}
+#ifdef ICONV_OPTION
+		if (ic_recv != (iconv_t)-1) {
+			xbuf outbuf, inbuf;
+			char ibuf[512];
+			int add_null = 0;
+			int flags = ICB_INCLUDE_BAD | ICB_INIT;
+
+			INIT_CONST_XBUF(outbuf, data);
+			INIT_XBUF(inbuf, ibuf, 0, (size_t)-1);
+
+			while (msg_bytes) {
+				size_t len = msg_bytes > sizeof ibuf - inbuf.len ? sizeof ibuf - inbuf.len : msg_bytes;
+				raw_read_buf(ibuf + inbuf.len, len);
+				inbuf.pos = 0;
+				inbuf.len += len;
+				if (!(msg_bytes -= len) && !ibuf[inbuf.len-1])
+					inbuf.len--, add_null = 1;
+				if (iconvbufs(ic_send, &inbuf, &outbuf, flags) < 0) {
+					if (errno == E2BIG)
+						goto overflow;
+					/* Buffer ended with an incomplete char, so move the
+					 * bytes to the start of the buffer and continue. */
+					memmove(ibuf, ibuf + inbuf.pos, inbuf.len);
+				}
+				flags &= ~ICB_INIT;
+			}
+			if (add_null) {
+				if (outbuf.len == outbuf.size)
+					goto overflow;
+				outbuf.buf[outbuf.len++] = '\0';
+			}
+			msg_bytes = outbuf.len;
+		} else
+#endif
+			raw_read_buf(data, msg_bytes);
+		iobuf.in_multiplexed = 1;
+		/* A directory name was sent with the trailing null */
+		if (msg_bytes > 0 && !data[msg_bytes-1])
+			log_delete(data, S_IFDIR);
+		else {
+			data[msg_bytes] = '\0';
+			log_delete(data, S_IFREG);
+		}
+		break;
+	case MSG_SUCCESS:
+		if (msg_bytes != (local_server ? 4+8+8 : 4)) {
+		  invalid_msg:
+			rprintf(FERROR, "invalid multi-message %d:%lu [%s%s]\n",
+				tag, (unsigned long)msg_bytes, who_am_i(),
+				inc_recurse ? "/inc" : "");
+			exit_cleanup(RERR_STREAMIO);
+		}
+		raw_read_buf(num_dev_ino_buf, msg_bytes);
+		val = IVAL(num_dev_ino_buf, 0);
+		iobuf.in_multiplexed = 1;
+		if (am_generator)
+			got_flist_entry_status(FES_SUCCESS, val);
+		else
+			successful_send(val);
+		break;
+	case MSG_NO_SEND:
+		if (msg_bytes != 4)
+			goto invalid_msg;
+		val = raw_read_int();
+		iobuf.in_multiplexed = 1;
+		if (am_generator)
+			got_flist_entry_status(FES_NO_SEND, val);
+		else
+			send_msg_int(MSG_NO_SEND, val);
+		break;
+	case MSG_ERROR_SOCKET:
+	case MSG_ERROR_UTF8:
+	case MSG_CLIENT:
+	case MSG_LOG:
+		if (!am_generator)
+			goto invalid_msg;
+		if (tag == MSG_ERROR_SOCKET)
+			msgs2stderr = 1;
+		/* FALL THROUGH */
+	case MSG_INFO:
+	case MSG_ERROR:
+	case MSG_ERROR_XFER:
+	case MSG_WARNING:
+		if (msg_bytes >= sizeof data) {
+		    overflow:
+			rprintf(FERROR,
+				"multiplexing overflow %d:%lu [%s%s]\n",
+				tag, (unsigned long)msg_bytes, who_am_i(),
+				inc_recurse ? "/inc" : "");
+			exit_cleanup(RERR_STREAMIO);
+		}
+		raw_read_buf(data, msg_bytes);
+		/* We don't set in_multiplexed value back to 1 before writing this message
+		 * because the write might loop back and read yet another message, over and
+		 * over again, while waiting for room to put the message in the msg buffer. */
+		rwrite((enum logcode)tag, data, msg_bytes, !am_generator);
+		iobuf.in_multiplexed = 1;
+		if (first_message) {
+			if (list_only && !am_sender && tag == 1 && msg_bytes < sizeof data) {
+				data[msg_bytes] = '\0';
+				check_for_d_option_error(data);
+			}
+			first_message = 0;
+		}
+		break;
+	case MSG_ERROR_EXIT:
+		if (msg_bytes == 4)
+			val = raw_read_int();
+		else if (msg_bytes == 0)
+			val = 0;
+		else
+			goto invalid_msg;
+		iobuf.in_multiplexed = 1;
+		if (DEBUG_GTE(EXIT, 3)) {
+			rprintf(FINFO, "[%s] got MSG_ERROR_EXIT with %" SIZE_T_FMT_MOD "d bytes\n",
+					who_am_i(), (SIZE_T_FMT_CAST)msg_bytes);
+		}
+		if (msg_bytes == 0) {
+			if (!am_sender && !am_generator) {
+				if (DEBUG_GTE(EXIT, 3)) {
+					rprintf(FINFO, "[%s] sending MSG_ERROR_EXIT (len 0)\n",
+						who_am_i());
+				}
+				send_msg(MSG_ERROR_EXIT, "", 0, 0);
+				io_flush(FULL_FLUSH);
+			}
+		} else if (protocol_version >= 31) {
+			if (am_generator || am_receiver) {
+				if (DEBUG_GTE(EXIT, 3)) {
+					rprintf(FINFO, "[%s] sending MSG_ERROR_EXIT with exit_code %d\n",
+						who_am_i(), val);
+				}
+				send_msg_int(MSG_ERROR_EXIT, val);
+			} else {
+				if (DEBUG_GTE(EXIT, 3)) {
+					rprintf(FINFO, "[%s] sending MSG_ERROR_EXIT (len 0)\n",
+						who_am_i());
+				}
+				send_msg(MSG_ERROR_EXIT, "", 0, 0);
+			}
+		}
+		/* Send a negative linenum so that we don't end up
+		 * with a duplicate exit message. */
+		_exit_cleanup(val, __FILE__, 0 - __LINE__);
+	default:
+		rprintf(FERROR, "unexpected tag %d [%s%s]\n",
+			tag, who_am_i(), inc_recurse ? "/inc" : "");
+		exit_cleanup(RERR_STREAMIO);
+	}
+
+	assert(iobuf.in_multiplexed > 0);
+}
+
+static void drain_multiplex_messages(void)
+{
+	while (IN_MULTIPLEXED_AND_READY && iobuf.in.len) {
+		if (iobuf.raw_input_ends_before) {
+			size_t raw_len = iobuf.raw_input_ends_before - iobuf.in.pos;
+			iobuf.raw_input_ends_before = 0;
+			if (raw_len >= iobuf.in.len) {
+				iobuf.in.len = 0;
+				break;
+			}
+			iobuf.in.len -= raw_len;
+			if ((iobuf.in.pos += raw_len) >= iobuf.in.size)
+				iobuf.in.pos -= iobuf.in.size;
+		}
+		read_a_msg();
+	}
+}
+
+void wait_for_receiver(void)
+{
+	if (!iobuf.raw_input_ends_before)
+		read_a_msg();
+
+	if (iobuf.raw_input_ends_before) {
+		int ndx = read_int(iobuf.in_fd);
+		if (ndx < 0) {
+			switch (ndx) {
+			case NDX_FLIST_EOF:
+				flist_eof = 1;
+				if (DEBUG_GTE(FLIST, 3))
+					rprintf(FINFO, "[%s] flist_eof=1\n", who_am_i());
+				break;
+			case NDX_DONE:
+				msgdone_cnt++;
+				break;
+			default:
+				exit_cleanup(RERR_STREAMIO);
+			}
+		} else {
+			struct file_list *flist;
+			flist_receiving_enabled = False;
+			if (DEBUG_GTE(FLIST, 2)) {
+				rprintf(FINFO, "[%s] receiving flist for dir %d\n",
+					who_am_i(), ndx);
+			}
+			flist = recv_file_list(iobuf.in_fd, ndx);
+			flist->parent_ndx = ndx;
+#ifdef SUPPORT_HARD_LINKS
+			if (preserve_hard_links)
+				match_hard_links(flist);
+#endif
+			flist_receiving_enabled = True;
+		}
+	}
+}
+
+unsigned short read_shortint(int f)
+{
+	char b[2];
+	read_buf(f, b, 2);
+	return (UVAL(b, 1) << 8) + UVAL(b, 0);
+}
+
+int32 read_int(int f)
+{
+	char b[4];
+	int32 num;
+
+	read_buf(f, b, 4);
+	num = IVAL(b, 0);
+#if SIZEOF_INT32 > 4
+	if (num & (int32)0x80000000)
+		num |= ~(int32)0xffffffff;
+#endif
+	return num;
+}
+
+uint32 read_uint(int f)
+{
+	char b[4];
+	read_buf(f, b, 4);
+	return IVAL(b, 0);
+}
+
+int32 read_varint(int f)
+{
+	union {
+		char b[5];
+		int32 x;
+	} u;
+	uchar ch;
+	int extra;
+
+	u.x = 0;
+	ch = read_byte(f);
+	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);
+		}
+		read_buf(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
+	read_buf(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);
+		}
+		read_buf(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 = IVAL64(u.b,0);
+#endif
+	return u.x;
+}
+
+int64 read_longint(int f)
+{
+#if SIZEOF_INT64 >= 8
+	char b[9];
+#endif
+	int32 num = read_int(f);
+
+	if (num != (int32)0xffffffff)
+		return num;
+
+#if SIZEOF_INT64 < 8
+	rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
+	exit_cleanup(RERR_UNSUPPORTED);
+#else
+	read_buf(f, b, 8);
+	return IVAL(b,0) | (((int64)IVAL(b,4))<<32);
+#endif
+}
+
+/* Debugging note: this will be named read_buf_() when using an external zlib. */
+void read_buf(int f, char *buf, size_t len)
+{
+	if (f != iobuf.in_fd) {
+		if (safe_read(f, buf, len) != len)
+			whine_about_eof(False); /* Doesn't return. */
+		goto batch_copy;
+	}
+
+	if (!IN_MULTIPLEXED) {
+		raw_read_buf(buf, len);
+		total_data_read += len;
+		if (forward_flist_data)
+			write_buf(iobuf.out_fd, buf, len);
+	  batch_copy:
+		if (f == write_batch_monitor_in)
+			safe_write(batch_fd, buf, len);
+		return;
+	}
+
+	while (1) {
+		size_t siz;
+
+		while (!iobuf.raw_input_ends_before)
+			read_a_msg();
+
+		siz = MIN(len, iobuf.raw_input_ends_before - iobuf.in.pos);
+		if (siz >= iobuf.in.size)
+			siz = iobuf.in.size;
+		raw_read_buf(buf, siz);
+		total_data_read += siz;
+
+		if (forward_flist_data)
+			write_buf(iobuf.out_fd, buf, siz);
+
+		if (f == write_batch_monitor_in)
+			safe_write(batch_fd, buf, siz);
+
+		if ((len -= siz) == 0)
+			break;
+		buf += siz;
+	}
+}
+
+void read_sbuf(int f, char *buf, size_t len)
+{
+	read_buf(f, buf, len);
+	buf[len] = '\0';
+}
+
+uchar read_byte(int f)
+{
+	uchar c;
+	read_buf(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)
+		read_buf(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)
+{
+	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);
+	}
+}
+
+/* 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.
+ *
+ * @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 */
+
+	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 -= (int64)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);
+}
+
+void io_flush(int flush_type)
+{
+	if (iobuf.out.len > iobuf.out_empty_len) {
+		if (flush_type == FULL_FLUSH)		/* flush everything in the output buffers */
+			perform_io(iobuf.out.size - iobuf.out_empty_len, PIO_NEED_OUTROOM);
+		else if (flush_type == NORMAL_FLUSH)	/* flush at least 1 byte */
+			perform_io(iobuf.out.size - iobuf.out.len + 1, PIO_NEED_OUTROOM);
+							/* MSG_FLUSH: flush iobuf.msg only */
+	}
+	if (iobuf.msg.len)
+		perform_io(iobuf.msg.size, PIO_NEED_MSGROOM);
+}
+
+void write_shortint(int f, unsigned short x)
+{
+	char b[2];
+	b[0] = (char)x;
+	b[1] = (char)(x >> 8);
+	write_buf(f, b, 2);
+}
+
+void write_int(int f, int32 x)
+{
+	char b[4];
+	SIVAL(b, 0, x);
+	write_buf(f, b, 4);
+}
+
+void write_varint(int f, int32 x)
+{
+	char b[5];
+	uchar bit;
+	int cnt;
+
+	SIVAL(b, 1, x);
+
+	for (cnt = 4; 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[1];
+
+	write_buf(f, b, cnt);
+}
+
+void write_varlong(int f, int64 x, uchar min_bytes)
+{
+	char b[9];
+	uchar bit;
+	int cnt = 8;
+
+#if SIZEOF_INT64 >= 8
+	SIVAL64(b, 1, x);
+#else
+	SIVAL(b, 1, x);
+	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];
+
+	write_buf(f, b, cnt);
+}
+
+/*
+ * Note: int64 may actually be a 32-bit type if ./configure couldn't find any
+ * 64-bit types on this platform.
+ */
+void write_longint(int f, int64 x)
+{
+	char b[12], * const s = b+4;
+
+	SIVAL(s, 0, x);
+	if (x <= 0x7FFFFFFF && x >= 0) {
+		write_buf(f, s, 4);
+		return;
+	}
+
+#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);
+	write_buf(f, b, 12);
+#endif
+}
+
+void write_bigbuf(int f, const char *buf, size_t len)
+{
+	size_t half_max = (iobuf.out.size - iobuf.out_empty_len) / 2;
+
+	while (len > half_max + 1024) {
+		write_buf(f, buf, half_max);
+		buf += half_max;
+		len -= half_max;
+	}
+
+	write_buf(f, buf, len);
+}
+
+void write_buf(int f, const char *buf, size_t len)
+{
+	size_t pos, siz;
+
+	if (f != iobuf.out_fd) {
+		safe_write(f, buf, len);
+		goto batch_copy;
+	}
+
+	if (iobuf.out.len + len > iobuf.out.size)
+		perform_io(len, PIO_NEED_OUTROOM);
+
+	pos = iobuf.out.pos + iobuf.out.len; /* Must be set after any flushing. */
+	if (pos >= iobuf.out.size)
+		pos -= iobuf.out.size;
+
+	/* Handle a split copy if we wrap around the end of the circular buffer. */
+	if (pos >= iobuf.out.pos && (siz = iobuf.out.size - pos) < len) {
+		memcpy(iobuf.out.buf + pos, buf, siz);
+		memcpy(iobuf.out.buf, buf + siz, len - siz);
+	} else
+		memcpy(iobuf.out.buf + pos, buf, len);
+
+	iobuf.out.len += len;
+	total_data_written += len;
+
+  batch_copy:
+	if (f == write_batch_monitor_out)
+		safe_write(batch_fd, buf, len);
+}
+
+/* Write a string to the connection */
+void write_sbuf(int f, const char *buf)
+{
+	write_buf(f, buf, strlen(buf));
+}
+
+void write_byte(int f, uchar c)
+{
+	write_buf(f, (char *)&c, 1);
+}
+
+void write_vstring(int f, const 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;
+
+	write_buf(f, (char*)lenbuf, lb - lenbuf + 1);
+	if (len)
+		write_buf(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;
+	}
+
+	/* 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;
+		write_buf(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;
+	}
+	write_buf(f, b, cnt);
+}
+
+/* Receive a file-list index using a byte-reduction method. */
+int32 read_ndx(int f)
+{
+	static int32 prev_positive = -1, prev_negative = 1;
+	int32 *prev_ptr, num;
+	char b[4];
+
+	if (protocol_version < 30)
+		return read_int(f);
+
+	read_buf(f, b, 1);
+	if (CVAL(b, 0) == 0xFF) {
+		read_buf(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) {
+		read_buf(f, b, 2);
+		if (CVAL(b, 0) & 0x80) {
+			b[3] = CVAL(b, 0) & ~0x80;
+			b[0] = b[1];
+			read_buf(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 fd, char *buf, size_t bufsiz, int eof_ok)
+{
+	assert(fd != iobuf.in_fd);
+	bufsiz--; /* leave room for the null */
+	while (bufsiz > 0) {
+		if (safe_read(fd, buf, 1) == 0) {
+			if (eof_ok)
+				break;
+			return 0;
+		}
+		if (*buf == '\0')
+			return 0;
+		if (*buf == '\n')
+			break;
+		if (*buf != '\r') {
+			buf++;
+			bufsiz--;
+		}
+	}
+	*buf = '\0';
+	return bufsiz > 0;
+}
+
+void io_printf(int fd, const char *format, ...)
+{
+	va_list ap;
+	char buf[BIGPATHBUFLEN];
+	int len;
+
+	va_start(ap, format);
+	len = vsnprintf(buf, sizeof buf, format, ap);
+	va_end(ap);
+
+	if (len < 0)
+		exit_cleanup(RERR_PROTOCOL);
+
+	if (len >= (int)sizeof buf) {
+		rprintf(FERROR, "io_printf() was too long for the buffer.\n");
+		exit_cleanup(RERR_PROTOCOL);
+	}
+
+	write_sbuf(fd, buf);
+}
+
+/* Setup for multiplexing a MSG_* stream with the data stream. */
+void io_start_multiplex_out(int fd)
+{
+	io_flush(FULL_FLUSH);
+
+	if (msgs2stderr == 1 && DEBUG_GTE(IO, 2))
+		rprintf(FINFO, "[%s] io_start_multiplex_out(%d)\n", who_am_i(), fd);
+
+	if (!iobuf.msg.buf)
+		alloc_xbuf(&iobuf.msg, ROUND_UP_1024(IO_BUFFER_SIZE));
+
+	iobuf.out_empty_len = 4; /* See also OUT_MULTIPLEXED */
+	io_start_buffering_out(fd);
+	got_kill_signal = 0;
+
+	iobuf.raw_data_header_pos = iobuf.out.pos + iobuf.out.len;
+	iobuf.out.len += 4;
+}
+
+/* Setup for multiplexing a MSG_* stream with the data stream. */
+void io_start_multiplex_in(int fd)
+{
+	if (msgs2stderr == 1 && DEBUG_GTE(IO, 2))
+		rprintf(FINFO, "[%s] io_start_multiplex_in(%d)\n", who_am_i(), fd);
+
+	iobuf.in_multiplexed = 1; /* See also IN_MULTIPLEXED */
+	io_start_buffering_in(fd);
+}
+
+int io_end_multiplex_in(int mode)
+{
+	int ret = iobuf.in_multiplexed ? iobuf.in_fd : -1;
+
+	if (msgs2stderr == 1 && DEBUG_GTE(IO, 2))
+		rprintf(FINFO, "[%s] io_end_multiplex_in(mode=%d)\n", who_am_i(), mode);
+
+	iobuf.in_multiplexed = 0;
+	if (mode == MPLX_SWITCHING)
+		iobuf.raw_input_ends_before = 0;
+	else
+		assert(iobuf.raw_input_ends_before == 0);
+	if (mode != MPLX_TO_BUFFERED)
+		io_end_buffering_in(mode);
+
+	return ret;
+}
+
+int io_end_multiplex_out(int mode)
+{
+	int ret = iobuf.out_empty_len ? iobuf.out_fd : -1;
+
+	if (msgs2stderr == 1 && DEBUG_GTE(IO, 2))
+		rprintf(FINFO, "[%s] io_end_multiplex_out(mode=%d)\n", who_am_i(), mode);
+
+	if (mode != MPLX_TO_BUFFERED)
+		io_end_buffering_out(mode);
+	else
+		io_flush(FULL_FLUSH);
+
+	iobuf.out.len = 0;
+	iobuf.out_empty_len = 0;
+	if (got_kill_signal > 0) /* Just in case... */
+		handle_kill_signal(False);
+	got_kill_signal = -1;
+
+	return ret;
+}
+
+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_varint(batch_fd, compat_flags);
+	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;
+}