X-Git-Url: https://mattmccutchen.net/rsync/rsync.git/blobdiff_plain/6c8507724b4c7f3e4eb93cecc1ff816c2d3714f1..4afab316073bed7dbd6215f788daf753e83c342e:/io.c

diff --git a/io.c b/io.c
index 55aac4a9..567065b9 100644
--- a/io.c
+++ b/io.c
@@ -41,7 +41,10 @@ extern int am_server;
 extern int am_daemon;
 extern int am_sender;
 extern int am_generator;
+extern int incremental;
+extern int io_error;
 extern int eol_nulls;
+extern int flist_eof;
 extern int read_batch;
 extern int csum_length;
 extern int checksum_seed;
@@ -50,12 +53,12 @@ extern int remove_source_files;
 extern int preserve_hard_links;
 extern char *filesfrom_host;
 extern struct stats stats;
-extern struct file_list *the_file_list;
+extern struct file_list *cur_flist, *first_flist;
 
 const char phase_unknown[] = "unknown";
 int ignore_timeout = 0;
 int batch_fd = -1;
-int batch_gen_fd = -1;
+int done_cnt = 0;
 
 /* Ignore an EOF error if non-zero. See whine_about_eof(). */
 int kluge_around_eof = 0;
@@ -65,6 +68,18 @@ 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 time_t last_io_in;
@@ -85,7 +100,19 @@ static int select_timeout = SELECT_TIMEOUT;
 static int active_filecnt = 0;
 static OFF_T active_bytecnt = 0;
 
-static void read_loop(int fd, char *buf, size_t len);
+static char int_byte_cnt[64] = {
+	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, /* (00 - 3F)/4 */
+	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, /* (40 - 7F)/4 */
+	4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, /* (80 - BF)/4 */
+	5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 8, 9, /* (C0 - FF)/4 */
+};
+
+static void msg2sndr_flush(void);
+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 decrement_active_files(int ndx);
+static void decrement_flist_in_progress(int ndx, int redo);
 
 struct flist_ndx_item {
 	struct flist_ndx_item *next;
@@ -204,7 +231,7 @@ void set_msg_fd_out(int fd)
 }
 
 /* Add a message to the pending MSG_* list. */
-static void msg_list_add(struct msg_list *lst, int code, char *buf, int len)
+static void msg_list_add(struct msg_list *lst, int code, const char *buf, int len)
 {
 	struct msg_list_item *m;
 	int sz = len + 4 + sizeof m[0] - 1;
@@ -230,14 +257,16 @@ static void read_msg_fd(void)
 {
 	char buf[2048];
 	size_t n;
+	struct file_list *flist;
 	int fd = msg_fd_in;
 	int tag, len;
 
 	/* Temporarily disable msg_fd_in.  This is needed to avoid looping back
 	 * to this routine from writefd_unbuffered(). */
 	msg_fd_in = -1;
+	defer_forwarding_messages++;
 
-	read_loop(fd, buf, 4);
+	readfd(fd, buf, 4);
 	tag = IVAL(buf, 0);
 
 	len = tag & 0xFFFFFF;
@@ -246,48 +275,71 @@ static void read_msg_fd(void)
 	switch (tag) {
 	case MSG_DONE:
 		if (len != 0 || !am_generator) {
-			rprintf(FERROR, "invalid message %d:%d\n", tag, len);
+		  invalid_msg:
+			rprintf(FERROR, "invalid message %d:%d [%s%s]\n",
+				tag, len, who_am_i(),
+				incremental ? "/incremental" : "");
 			exit_cleanup(RERR_STREAMIO);
 		}
-		flist_ndx_push(&redo_list, -1);
+		done_cnt++;
 		break;
 	case MSG_REDO:
-		if (len != 4 || !am_generator) {
-			rprintf(FERROR, "invalid message %d:%d\n", tag, len);
-			exit_cleanup(RERR_STREAMIO);
-		}
-		read_loop(fd, buf, 4);
+		if (len != 4 || !am_generator)
+			goto invalid_msg;
+		readfd(fd, buf, 4);
 		if (remove_source_files)
 			decrement_active_files(IVAL(buf,0));
 		flist_ndx_push(&redo_list, IVAL(buf,0));
+		if (incremental)
+			decrement_flist_in_progress(IVAL(buf,0), 1);
+		break;
+	case MSG_FLIST:
+		if (len != 4 || !am_generator || !incremental)
+			goto invalid_msg;
+		readfd(fd, buf, 4);
+		/* Read extra file list from receiver. */
+		assert(iobuf_in != NULL);
+		assert(iobuf_f_in == fd);
+		flist = recv_file_list(fd);
+		flist->parent_ndx = IVAL(buf,0);
+		break;
+	case MSG_FLIST_EOF:
+		if (len != 0 || !am_generator || !incremental)
+			goto invalid_msg;
+		flist_eof = 1;
 		break;
 	case MSG_DELETED:
-		if (len >= (int)sizeof buf || !am_generator) {
-			rprintf(FERROR, "invalid message %d:%d\n", tag, len);
-			exit_cleanup(RERR_STREAMIO);
-		}
-		read_loop(fd, buf, len);
+		if (len >= (int)sizeof buf || !am_generator)
+			goto invalid_msg;
+		readfd(fd, buf, len);
 		send_msg(MSG_DELETED, buf, len);
 		break;
 	case MSG_SUCCESS:
-		if (len != 4 || !am_generator) {
-			rprintf(FERROR, "invalid message %d:%d\n", tag, len);
-			exit_cleanup(RERR_STREAMIO);
-		}
-		read_loop(fd, buf, len);
+		if (len != 4 || !am_generator)
+			goto invalid_msg;
+		readfd(fd, buf, len);
 		if (remove_source_files) {
 			decrement_active_files(IVAL(buf,0));
 			send_msg(MSG_SUCCESS, buf, len);
 		}
 		if (preserve_hard_links)
 			flist_ndx_push(&hlink_list, IVAL(buf,0));
+		if (incremental)
+			decrement_flist_in_progress(IVAL(buf,0), 0);
+		break;
+	case MSG_NO_SEND:
+		if (len != 4 || !am_generator)
+			goto invalid_msg;
+		readfd(fd, buf, len);
+		if (incremental)
+			decrement_flist_in_progress(IVAL(buf,0), 0);
 		break;
 	case MSG_SOCKERR:
-		if (!am_generator) {
-			rprintf(FERROR, "invalid message %d:%d\n", tag, len);
-			exit_cleanup(RERR_STREAMIO);
-		}
-		close_multiplexing_out();
+	case MSG_CLIENT:
+		if (!am_generator)
+			goto invalid_msg;
+		if (tag == MSG_SOCKERR)
+			io_end_multiplex_out();
 		/* FALL THROUGH */
 	case MSG_INFO:
 	case MSG_ERROR:
@@ -296,8 +348,8 @@ static void read_msg_fd(void)
 			n = len;
 			if (n >= sizeof buf)
 				n = sizeof buf - 1;
-			read_loop(fd, buf, n);
-			rwrite(tag, buf, n);
+			readfd(fd, buf, n);
+			rwrite((enum logcode)tag, buf, n);
 			len -= n;
 		}
 		break;
@@ -307,7 +359,9 @@ static void read_msg_fd(void)
 		exit_cleanup(RERR_STREAMIO);
 	}
 
+	defer_forwarding_messages--;
 	msg_fd_in = fd;
+	msg2sndr_flush();
 }
 
 /* This is used by the generator to limit how many file transfers can
@@ -317,61 +371,77 @@ void increment_active_files(int ndx, int itemizing, enum logcode code)
 {
 	/* TODO: tune these limits? */
 	while (active_filecnt >= (active_bytecnt >= 128*1024 ? 10 : 50)) {
+#ifdef SUPPORT_HARD_LINKS
 		if (hlink_list.head)
 			check_for_finished_hlinks(itemizing, code);
+#endif
 		read_msg_fd();
 	}
 
 	active_filecnt++;
-	active_bytecnt += the_file_list->files[ndx]->length;
+	active_bytecnt += F_LENGTH(cur_flist->files[ndx]);
 }
 
-void decrement_active_files(int ndx)
+static void decrement_active_files(int ndx)
 {
+	struct file_list *flist = flist_for_ndx(ndx);
+	assert(flist != NULL);
 	active_filecnt--;
-	active_bytecnt -= the_file_list->files[ndx]->length;
+	active_bytecnt -= F_LENGTH(flist->files[ndx - flist->ndx_start]);
+}
+
+static void decrement_flist_in_progress(int ndx, int redo)
+{
+	struct file_list *flist = cur_flist ? cur_flist : first_flist;
+
+	while (ndx < flist->ndx_start) {
+		if (flist == first_flist) {
+		  invalid_ndx:
+			rprintf(FERROR,
+				"Invalid file index: %d (%d - %d) [%s]\n",
+				ndx, first_flist->ndx_start,
+				first_flist->prev->ndx_start + first_flist->prev->count - 1,
+				who_am_i());
+			exit_cleanup(RERR_PROTOCOL);
+		}
+		flist = flist->prev;
+	}
+	while (ndx >= flist->ndx_start + flist->count) {
+		if (!(flist = flist->next))
+			goto invalid_ndx;
+	}
+
+	flist->in_progress--;
+	if (redo)
+		flist->to_redo++;
 }
 
 /* Try to push messages off the list onto the wire.  If we leave with more
  * to do, return 0.  On error, return -1.  If everything flushed, return 1.
  * This is only active in the receiver. */
-static int msg2genr_flush(int flush_it_all)
+static int msg2genr_flush(void)
 {
-	static int written = 0;
-	struct timeval tv;
-	fd_set fds;
-
-	if (msg_fd_out < 0)
+	if (msg_fd_out < 0 || no_flush || flist_forward_from >= 0)
 		return -1;
 
+	no_flush++;
 	while (msg2genr.head) {
 		struct msg_list_item *m = msg2genr.head;
-		int n = write(msg_fd_out, m->buf + written, m->len - written);
-		if (n < 0) {
-			if (errno == EINTR)
-				continue;
-			if (errno != EWOULDBLOCK && errno != EAGAIN)
-				return -1;
-			if (!flush_it_all)
-				return 0;
-			FD_ZERO(&fds);
-			FD_SET(msg_fd_out, &fds);
-			tv.tv_sec = select_timeout;
-			tv.tv_usec = 0;
-			if (!select(msg_fd_out+1, NULL, &fds, NULL, &tv))
-				check_timeout();
-		} else if ((written += n) == m->len) {
-			msg2genr.head = m->next;
-			if (!msg2genr.head)
-				msg2genr.tail = NULL;
-			free(m);
-			written = 0;
-		}
+		writefd(msg_fd_out, m->buf, m->len);
+		msg2genr.head = m->next;
+		if (!msg2genr.head)
+			msg2genr.tail = NULL;
+		free(m);
+	}
+	if (iobuf_out_cnt) {
+		writefd_unbuffered(iobuf_f_out, iobuf_out, iobuf_out_cnt);
+		iobuf_out_cnt = 0;
 	}
+	no_flush--;
 	return 1;
 }
 
-int send_msg(enum msgcode code, char *buf, int len)
+int send_msg(enum msgcode code, const char *buf, int len)
 {
 	if (msg_fd_out < 0) {
 		if (!defer_forwarding_messages)
@@ -382,20 +452,24 @@ int send_msg(enum msgcode code, char *buf, int len)
 		return 1;
 	}
 	msg_list_add(&msg2genr, code, buf, len);
-	msg2genr_flush(NORMAL_FLUSH);
+	msg2genr_flush();
 	return 1;
 }
 
-int get_redo_num(int itemizing, enum logcode code)
+void send_msg_int(enum msgcode code, int num)
 {
-	while (1) {
-		if (hlink_list.head)
-			check_for_finished_hlinks(itemizing, code);
-		if (redo_list.head)
-			break;
-		read_msg_fd();
-	}
+	char numbuf[4];
+	SIVAL(numbuf, 0, num);
+	send_msg(code, numbuf, 4);
+}
 
+void wait_for_receiver(void)
+{
+	read_msg_fd();
+}
+
+int get_redo_num(void)
+{
 	return flist_ndx_pop(&redo_list);
 }
 
@@ -468,7 +542,7 @@ static int read_timeout(int fd, char *buf, size_t len)
 {
 	int n, cnt = 0;
 
-	io_flush(NORMAL_FLUSH);
+	io_flush(FULL_FLUSH);
 
 	while (cnt == 0) {
 		/* until we manage to read *something* */
@@ -518,7 +592,7 @@ static int read_timeout(int fd, char *buf, size_t len)
 		}
 
 		if (msg2genr.head && FD_ISSET(msg_fd_out, &w_fds))
-			msg2genr_flush(NORMAL_FLUSH);
+			msg2genr_flush();
 
 		if (io_filesfrom_f_out >= 0) {
 			if (io_filesfrom_buflen) {
@@ -597,7 +671,7 @@ static int read_timeout(int fd, char *buf, size_t len)
 
 			/* Don't write errors on a dead socket. */
 			if (fd == sock_f_in) {
-				close_multiplexing_out();
+				io_end_multiplex_out();
 				rsyserr(FSOCKERR, errno, "read error");
 			} else
 				rsyserr(FERROR, errno, "read error");
@@ -668,37 +742,51 @@ int read_filesfrom_line(int fd, char *fname)
 	return s - fname;
 }
 
-static char *iobuf_out;
-static int iobuf_out_cnt;
-
-void io_start_buffering_out(void)
+int io_start_buffering_out(int f_out)
 {
-	if (iobuf_out)
-		return;
+	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;
 }
 
-static char *iobuf_in;
-static size_t iobuf_in_siz;
-
-void io_start_buffering_in(void)
+int io_start_buffering_in(int f_in)
 {
-	if (iobuf_in)
-		return;
+	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(void)
+void io_end_buffering_in(void)
 {
-	io_flush(NORMAL_FLUSH);
-	if (!io_multiplexing_out) {
-		free(iobuf_out);
-		iobuf_out = NULL;
-	}
+	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(void)
@@ -713,14 +801,31 @@ void maybe_send_keepalive(void)
 		if (!iobuf_out || !iobuf_out_cnt) {
 			if (protocol_version < 29)
 				return; /* there's nothing we can do */
-			write_int(sock_f_out, the_file_list->count);
-			write_shortint(sock_f_out, ITEM_IS_NEW);
+			if (protocol_version >= 30)
+				send_msg(MSG_NOOP, "", 0);
+			else {
+				write_int(sock_f_out, cur_flist->count);
+				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.
@@ -743,26 +848,24 @@ static void read_loop(int fd, char *buf, size_t len)
  */
 static int readfd_unbuffered(int fd, char *buf, size_t len)
 {
-	static size_t remaining;
-	static size_t iobuf_in_ndx;
 	size_t msg_bytes;
 	int tag, cnt = 0;
 	char line[BIGPATHBUFLEN];
 
-	if (!iobuf_in || fd != sock_f_in)
+	if (!iobuf_in || fd != iobuf_f_in)
 		return read_timeout(fd, buf, len);
 
-	if (!io_multiplexing_in && remaining == 0) {
-		remaining = read_timeout(fd, iobuf_in, iobuf_in_siz);
+	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 (remaining) {
-			len = MIN(len, remaining);
+		if (iobuf_in_remaining) {
+			len = MIN(len, iobuf_in_remaining);
 			memcpy(buf, iobuf_in + iobuf_in_ndx, len);
 			iobuf_in_ndx += len;
-			remaining -= len;
+			iobuf_in_remaining -= len;
 			cnt = len;
 			break;
 		}
@@ -782,9 +885,19 @@ static int readfd_unbuffered(int fd, char *buf, size_t len)
 				iobuf_in_siz = msg_bytes;
 			}
 			read_loop(fd, iobuf_in, msg_bytes);
-			remaining = 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);
+			io_error |= IVAL(line, 0);
+			break;
 		case MSG_DELETED:
 			if (msg_bytes >= sizeof line)
 				goto overflow;
@@ -799,6 +912,7 @@ static int readfd_unbuffered(int fd, char *buf, size_t len)
 			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);
@@ -806,6 +920,12 @@ static int readfd_unbuffered(int fd, char *buf, size_t len)
 			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:
 			if (msg_bytes >= sizeof line) {
@@ -825,17 +945,14 @@ static int readfd_unbuffered(int fd, char *buf, size_t len)
 		}
 	}
 
-	if (remaining == 0)
+	if (iobuf_in_remaining == 0)
 		io_flush(NORMAL_FLUSH);
 
 	return cnt;
 }
 
-/**
- * Do a buffered read from @p fd.  Don't return until all @p n bytes
- * have been read.  If all @p n can't be read then exit with an
- * error.
- **/
+/* 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  cnt;
@@ -851,15 +968,18 @@ static void readfd(int fd, char *buffer, size_t N)
 			exit_cleanup(RERR_FILEIO);
 	}
 
+	if (fd == flist_forward_from)
+		writefd(iobuf_f_out, buffer, total);
+
 	if (fd == sock_f_in)
 		stats.total_read += total;
 }
 
-int read_shortint(int f)
+unsigned short read_shortint(int f)
 {
-	uchar b[2];
-	readfd(f, (char *)b, 2);
-	return (b[1] << 8) + b[0];
+	char b[2];
+	readfd(f, b, 2);
+	return (UVAL(b, 1) << 8) + UVAL(b, 0);
 }
 
 int32 read_int(int f)
@@ -867,39 +987,83 @@ int32 read_int(int f)
 	char b[4];
 	int32 num;
 
-	readfd(f,b,4);
-	num = IVAL(b,0);
-	if (num == (int32)0xffffffff)
-		return -1;
+	readfd(f, b, 4);
+	num = IVAL(b, 0);
+#if SIZEOF_INT32 > 4
+	if (num & (int32)0x80000000)
+		num |= ~(int32)0xffffffff;
+#endif
 	return num;
 }
 
 int64 read_longint(int f)
 {
 	int64 num;
-	char b[8];
-	num = read_int(f);
+	char b[9];
+
+	if (protocol_version < 30) {
+		num = read_int(f);
 
-	if ((int32)num != (int32)0xffffffff)
-		return num;
+		if ((int32)num != (int32)0xffffffff)
+			return num;
 
 #if SIZEOF_INT64 < 8
-	rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
-	exit_cleanup(RERR_UNSUPPORTED);
+		rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
+		exit_cleanup(RERR_UNSUPPORTED);
 #else
-	readfd(f,b,8);
-	num = IVAL(b,0) | (((int64)IVAL(b,4))<<32);
+		readfd(f, b, 8);
+		num = IVAL(b,0) | (((int64)IVAL(b,4))<<32);
+#endif
+	} else {
+		int cnt;
+		readfd(f, b, 3);
+		cnt = int_byte_cnt[CVAL(b, 0) / 4];
+#if SIZEOF_INT64 < 8
+		if (cnt > 5 || (cnt == 5 && (CVAL(b,0)&0x3F || CVAL(b,1)&0x80))) {
+			rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
+			exit_cleanup(RERR_UNSUPPORTED);
+		}
+#endif
+		if (cnt > 3)
+			readfd(f, b + 3, cnt - 3);
+		switch (cnt) {
+		case 3:
+			num = NVAL3(b, 0);
+			break;
+		case 4:
+			num = NVAL4(b, 0x80);
+			break;
+		case 5:
+			num = NVAL5(b, 0xC0);
+			break;
+#if SIZEOF_INT64 >= 8
+		case 6:
+			num = NVAL6(b, 0xE0);
+			break;
+		case 7:
+			num = NVAL7(b, 0xF0);
+			break;
+		case 8:
+			num = NVAL8(b, 0xF8);
+			break;
+		case 9:
+			num = NVAL8(b+1, 0);
+			break;
 #endif
+		default:
+			exit_cleanup(RERR_PROTOCOL); /* impossible... */
+		}
+	}
 
 	return num;
 }
 
-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)
 {
 	readfd(f, buf, len);
 	buf[len] = '\0';
@@ -1039,7 +1203,7 @@ static void sleep_for_bwlimit(int bytes_written)
  *
  * This function underlies the multiplexing system.  The body of the
  * application never calls this function directly. */
-static void writefd_unbuffered(int fd,char *buf,size_t len)
+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;
@@ -1107,7 +1271,7 @@ static void writefd_unbuffered(int fd,char *buf,size_t len)
 
 			/* Don't try to write errors back across the stream. */
 			if (fd == sock_f_out)
-				close_multiplexing_out();
+				io_end_multiplex_out();
 			rsyserr(FERROR, errno,
 				"writefd_unbuffered failed to write %ld bytes [%s]",
 				(long)len, who_am_i());
@@ -1157,7 +1321,7 @@ static void msg2sndr_flush(void)
  * Write an message to a multiplexed stream. If this fails then rsync
  * exits.
  **/
-static void mplex_write(enum msgcode code, char *buf, size_t len)
+static void mplex_write(enum msgcode code, const char *buf, size_t len)
 {
 	char buffer[1024];
 	size_t n = len;
@@ -1184,8 +1348,10 @@ static void mplex_write(enum msgcode code, char *buf, size_t len)
 
 void io_flush(int flush_it_all)
 {
-	msg2genr_flush(flush_it_all);
-	msg2sndr_flush();
+	if (flush_it_all) {
+		msg2genr_flush();
+		msg2sndr_flush();
+	}
 
 	if (!iobuf_out_cnt || no_flush)
 		return;
@@ -1193,17 +1359,12 @@ void io_flush(int flush_it_all)
 	if (io_multiplexing_out)
 		mplex_write(MSG_DATA, iobuf_out, iobuf_out_cnt);
 	else
-		writefd_unbuffered(sock_f_out, iobuf_out, iobuf_out_cnt);
+		writefd_unbuffered(iobuf_f_out, iobuf_out, iobuf_out_cnt);
 	iobuf_out_cnt = 0;
 }
 
-static void writefd(int fd,char *buf,size_t len)
+static void writefd(int fd, const char *buf, size_t len)
 {
-	if (fd == msg_fd_out) {
-		rprintf(FERROR, "Internal error: wrong write used in receiver.\n");
-		exit_cleanup(RERR_PROTOCOL);
-	}
-
 	if (fd == sock_f_out)
 		stats.total_written += len;
 
@@ -1212,7 +1373,7 @@ static void writefd(int fd,char *buf,size_t len)
 			exit_cleanup(RERR_FILEIO);
 	}
 
-	if (!iobuf_out || fd != sock_f_out) {
+	if (!iobuf_out || fd != iobuf_f_out) {
 		writefd_unbuffered(fd, buf, len);
 		return;
 	}
@@ -1231,19 +1392,19 @@ static void writefd(int fd,char *buf,size_t len)
 	}
 }
 
-void write_shortint(int f, int x)
+void write_shortint(int f, unsigned short x)
 {
-	uchar b[2];
-	b[0] = x;
-	b[1] = x >> 8;
-	writefd(f, (char *)b, 2);
+	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);
 }
 
 /*
@@ -1252,32 +1413,110 @@ void write_int(int f,int32 x)
  */
 void write_longint(int f, int64 x)
 {
-	char b[8];
+	char b[12];
 
-	if (x <= 0x7FFFFFFF) {
-		write_int(f, (int)x);
-		return;
+#if SIZEOF_INT64 < 8
+	if (x < 0 || x > 0x7FFFFFFF) {
+		rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
+		exit_cleanup(RERR_UNSUPPORTED);
 	}
+#endif
 
+	if (protocol_version < 30) {
+		char * const s = b+4;
+		SIVAL(s, 0, x);
 #if SIZEOF_INT64 < 8
-	rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
-	exit_cleanup(RERR_UNSUPPORTED);
+		writefd(f, s, 4);
 #else
-	write_int(f, (int32)0xFFFFFFFF);
-	SIVAL(b,0,(x&0xFFFFFFFF));
-	SIVAL(b,4,((x>>32)&0xFFFFFFFF));
+		if (x <= 0x7FFFFFFF && x >= 0) {
+			writefd(f, s, 4);
+			return;
+		}
 
-	writefd(f,b,8);
+		memset(b, 0xFF, 4);
+		SIVAL(s, 4, x >> 32);
+		writefd(f, b, 12);
+	} else if (x < 0) {
+		goto all_bits;
+#endif
+	} else if (x < ((int32)1<<(3*8-1))) {
+		b[0] = (char)(x >> 16);
+		b[1] = (char)(x >> 8);
+		b[2] = (char)x;
+		writefd(f, b, 3);
+	} else if (x < ((int64)1<<(4*8-2))) {
+		b[0] = (char)((x >> 24) | 0x80);
+		b[1] = (char)(x >> 16);
+		b[2] = (char)(x >> 8);
+		b[3] = (char)x;
+		writefd(f, b, 4);
+#if SIZEOF_INT64 < 8
+	} else {
+		b[0] = 0xC0;
+		b[1] = (char)(x >> 24);
+		b[2] = (char)(x >> 16);
+		b[3] = (char)(x >> 8);
+		b[4] = (char)x;
+		writefd(f, b, 5);
+	}
+#else
+	} else if (x < ((int64)1<<(5*8-3))) {
+		b[0] = (char)((x >> 32) | 0xC0);
+		b[1] = (char)(x >> 24);
+		b[2] = (char)(x >> 16);
+		b[3] = (char)(x >> 8);
+		b[4] = (char)x;
+		writefd(f, b, 5);
+	} else if (x < ((int64)1<<(6*8-4))) {
+		b[0] = (char)((x >> 40) | 0xE0);
+		b[1] = (char)(x >> 32);
+		b[2] = (char)(x >> 24);
+		b[3] = (char)(x >> 16);
+		b[4] = (char)(x >> 8);
+		b[5] = (char)x;
+		writefd(f, b, 6);
+	} else if (x < ((int64)1<<(7*8-5))) {
+		b[0] = (char)((x >> 48) | 0xF0);
+		b[1] = (char)(x >> 40);
+		b[2] = (char)(x >> 32);
+		b[3] = (char)(x >> 24);
+		b[4] = (char)(x >> 16);
+		b[5] = (char)(x >> 8);
+		b[6] = (char)x;
+		writefd(f, b, 7);
+	} else if (x < ((int64)1<<(8*8-6))) {
+		b[0] = (char)((x >> 56) | 0xF8);
+		b[1] = (char)(x >> 48);
+		b[2] = (char)(x >> 40);
+		b[3] = (char)(x >> 32);
+		b[4] = (char)(x >> 24);
+		b[5] = (char)(x >> 16);
+		b[6] = (char)(x >> 8);
+		b[7] = (char)x;
+		writefd(f, b, 8);
+	} else {
+	  all_bits:
+		b[0] = (char)0xFC;
+		b[1] = (char)(x >> 56);
+		b[2] = (char)(x >> 48);
+		b[3] = (char)(x >> 40);
+		b[4] = (char)(x >> 32);
+		b[5] = (char)(x >> 24);
+		b[6] = (char)(x >> 16);
+		b[7] = (char)(x >> 8);
+		b[8] = (char)x;
+		writefd(f, b, 9);
+	}
 #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 */
-void write_sbuf(int f, char *buf)
+void write_sbuf(int f, const char *buf)
 {
 	writefd(f, buf, strlen(buf));
 }
@@ -1287,7 +1526,7 @@ void write_byte(int f, uchar c)
 	writefd(f, (char *)&c, 1);
 }
 
-void write_vstring(int f, char *str, int len)
+void write_vstring(int f, const char *str, int len)
 {
 	uchar lenbuf[3], *lb = lenbuf;
 
@@ -1307,6 +1546,86 @@ void write_vstring(int f, char *str, int 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;
+	}
+
+	/* 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 >> 16);
+		b[cnt++] = (char)(ndx >> 8);
+		b[cnt++] = (char)ndx;
+	} 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)
+{
+	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) {
+			readfd(f, b+2, 2);
+			num = NVAL4(b, 0x80);
+		} else
+			num = NVAL2(b, 0) + *prev_ptr;
+	} else
+		num = CVAL(b, 0) + *prev_ptr;
+	*prev_ptr = num;
+	if (prev_ptr == &prev_negative)
+		num = -num;
+	return num;
+}
+
 /**
  * Read a line of up to @p maxlen characters into @p buf (not counting
  * the trailing null).  Strips the (required) trailing newline and all
@@ -1357,7 +1676,7 @@ void io_printf(int fd, const char *format, ...)
 void io_start_multiplex_out(void)
 {
 	io_flush(NORMAL_FLUSH);
-	io_start_buffering_out();
+	io_start_buffering_out(sock_f_out);
 	io_multiplexing_out = 1;
 }
 
@@ -1365,37 +1684,36 @@ void io_start_multiplex_out(void)
 void io_start_multiplex_in(void)
 {
 	io_flush(NORMAL_FLUSH);
-	io_start_buffering_in();
+	io_start_buffering_in(sock_f_in);
 	io_multiplexing_in = 1;
 }
 
 /** Write an message to the multiplexed data stream. */
-int io_multiplex_write(enum msgcode code, char *buf, size_t len)
+int io_multiplex_write(enum msgcode code, const char *buf, size_t len)
 {
 	if (!io_multiplexing_out)
 		return 0;
-
 	io_flush(NORMAL_FLUSH);
 	stats.total_written += (len+4);
 	mplex_write(code, buf, len);
 	return 1;
 }
 
-void close_multiplexing_in(void)
+void io_end_multiplex_in(void)
 {
 	io_multiplexing_in = 0;
+	io_end_buffering_in();
 }
 
 /** Stop output multiplexing. */
-void close_multiplexing_out(void)
+void io_end_multiplex_out(void)
 {
 	io_multiplexing_out = 0;
+	io_end_buffering_out();
 }
 
 void start_write_batch(int fd)
 {
-	write_stream_flags(batch_fd);
-
 	/* Some communication has already taken place, but we don't
 	 * enable batch writing until here so that we can write a
 	 * canonical record of the communication even though the