- Got rid of the checking of msg_fd_in in read_timeout() -- it was
[rsync/rsync.git] / io.c
diff --git a/io.c b/io.c
index 9f9c382..a53b347 100644 (file)
--- a/io.c
+++ b/io.c
 /** If no timeout is specified then use a 60 second select timeout */
 #define SELECT_TIMEOUT 60
 
-static int io_multiplexing_out;
-static int io_multiplexing_in;
-static int multiplex_in_fd = -1;
-static int multiplex_out_fd = -1;
-static time_t last_io;
-static int no_flush;
-
 extern int bwlimit;
 extern size_t bwlimit_writemax;
 extern int verbose;
@@ -53,15 +46,19 @@ extern int io_timeout;
 extern int am_server;
 extern int am_daemon;
 extern int am_sender;
+extern int am_generator;
 extern int eol_nulls;
+extern int csum_length;
 extern int checksum_seed;
 extern int protocol_version;
-extern char *remote_filesfrom_file;
+extern char *filesfrom_host;
 extern struct stats stats;
 
 const char phase_unknown[] = "unknown";
 int select_timeout = SELECT_TIMEOUT;
+int ignore_timeout = 0;
 int batch_fd = -1;
+int batch_gen_fd = -1;
 
 /**
  * The connection might be dropped at some point; perhaps because the
@@ -79,13 +76,19 @@ int batch_fd = -1;
 const char *io_write_phase = phase_unknown;
 const char *io_read_phase = phase_unknown;
 
-/** Ignore EOF errors while reading a module listing if the remote
-    version is 24 or less. */
-int kludge_around_eof = False;
+/* Ignore an EOF error if non-zero. See whine_about_eof(). */
+int kluge_around_eof = 0;
 
 int msg_fd_in = -1;
 int msg_fd_out = -1;
 
+static int io_multiplexing_out;
+static int io_multiplexing_in;
+static int sock_f_in = -1;
+static int sock_f_out = -1;
+static time_t last_io;
+static int no_flush;
+
 static int write_batch_monitor_in = -1;
 static int write_batch_monitor_out = -1;
 
@@ -95,6 +98,7 @@ static char io_filesfrom_buf[2048];
 static char *io_filesfrom_bp;
 static char io_filesfrom_lastchar;
 static int io_filesfrom_buflen;
+static size_t contiguous_write_len = 0;
 
 static void read_loop(int fd, char *buf, size_t len);
 
@@ -134,7 +138,7 @@ static void check_timeout(void)
 {
        time_t t;
 
-       if (!io_timeout)
+       if (!io_timeout || ignore_timeout)
                return;
 
        if (!last_io) {
@@ -144,26 +148,34 @@ static void check_timeout(void)
 
        t = time(NULL);
 
-       if (last_io && io_timeout && (t-last_io) >= io_timeout) {
+       if (t - last_io >= io_timeout) {
                if (!am_server && !am_daemon) {
-                       rprintf(FERROR, "io timeout after %d seconds - exiting\n",
+                       rprintf(FERROR, "io timeout after %d seconds -- exiting\n",
                                (int)(t-last_io));
                }
                exit_cleanup(RERR_TIMEOUT);
        }
 }
 
-/** Setup the fd used to receive MSG_* messages.  Only needed when
- * we're the generator because the sender and receiver both use the
- * multiplexed I/O setup. */
+/* 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;
+}
+
+/* Setup the fd used to receive MSG_* messages.  Only needed during the
+ * early stages of being a local sender (up through the sending of the
+ * file list) or when we're the generator (to fetch the messages from
+ * the receiver). */
 void set_msg_fd_in(int fd)
 {
        msg_fd_in = fd;
 }
 
-/** Setup the fd used to send our MSG_* messages.  Only needed when
- * we're the receiver because the generator and the sender both use
- * the multiplexed I/O setup. */
+/* Setup the fd used to send our MSG_* messages.  Only needed when
+ * we're the receiver (to send our messages to the generator). */
 void set_msg_fd_out(int fd)
 {
        msg_fd_out = fd;
@@ -192,12 +204,18 @@ static void msg_list_add(int code, char *buf, int len)
 
 void send_msg(enum msgcode code, char *buf, int len)
 {
+       if (msg_fd_out < 0) {
+               io_multiplex_write(code, buf, len);
+               return;
+       }
        msg_list_add(code, buf, len);
        msg_list_push(NORMAL_FLUSH);
 }
 
-/** Read a message from the MSG_* fd and dispatch it.  This is only
- * called by the generator. */
+/* Read a message from the MSG_* fd and handle it.  This is called either
+ * during the early stages of being a local sender (up through the sending
+ * of the file list) or when we're the generator (to fetch the messages
+ * from the receiver). */
 static void read_msg_fd(void)
 {
        char buf[2048];
@@ -206,7 +224,7 @@ static void read_msg_fd(void)
        int tag, len;
 
        /* Temporarily disable msg_fd_in.  This is needed to avoid looping back
-        * to this routine from read_timeout() and writefd_unbuffered(). */
+        * to this routine from writefd_unbuffered(). */
        msg_fd_in = -1;
 
        read_loop(fd, buf, 4);
@@ -217,20 +235,36 @@ static void read_msg_fd(void)
 
        switch (tag) {
        case MSG_DONE:
-               if (len != 0) {
+               if (len != 0 || !am_generator) {
                        rprintf(FERROR, "invalid message %d:%d\n", tag, len);
                        exit_cleanup(RERR_STREAMIO);
                }
                redo_list_add(-1);
                break;
        case MSG_REDO:
-               if (len != 4) {
+               if (len != 4 || !am_generator) {
                        rprintf(FERROR, "invalid message %d:%d\n", tag, len);
                        exit_cleanup(RERR_STREAMIO);
                }
                read_loop(fd, buf, 4);
                redo_list_add(IVAL(buf,0));
                break;
+       case MSG_DELETED:
+               if (len >= (int)sizeof buf || !am_generator) {
+                       rprintf(FERROR, "invalid message %d:%d\n", tag, len);
+                       exit_cleanup(RERR_STREAMIO);
+               }
+               read_loop(fd, buf, len);
+               io_multiplex_write(MSG_DELETED, buf, len);
+               break;
+       case MSG_SUCCESS:
+               if (len != 4 || !am_generator) {
+                       rprintf(FERROR, "invalid message %d:%d\n", tag, len);
+                       exit_cleanup(RERR_STREAMIO);
+               }
+               read_loop(fd, buf, len);
+               io_multiplex_write(MSG_SUCCESS, buf, len);
+               break;
        case MSG_INFO:
        case MSG_ERROR:
        case MSG_LOG:
@@ -328,35 +362,33 @@ void io_set_filesfrom_fds(int f_in, int f_out)
        io_filesfrom_buflen = 0;
 }
 
-/**
- * It's almost always an error to get an EOF when we're trying to read
- * from the network, because the protocol is self-terminating.
+/* It's almost always an error to get an EOF when we're trying to read from the
+ * network, because the protocol is (for the most part) self-terminating.
  *
- * However, there is one unfortunate cases where it is not, which is
- * rsync <2.4.6 sending a list of modules on a server, since the list
- * is terminated by closing the socket. So, for the section of the
- * program where that is a problem (start_socket_client),
- * kludge_around_eof is True and we just exit.
- */
-static void whine_about_eof(void)
+ * There is one case for the receiver when it is at the end of the transfer
+ * (hanging around reading any keep-alive packets that might come its way): if
+ * the sender dies before the generator's kill-signal comes through, we can end
+ * up here needing to loop until the kill-signal arrives.  In this situation,
+ * kluge_around_eof will be < 0.
+ *
+ * There is another case for older protocol versions (< 24) where the module
+ * listing was not terminated, so we must ignore an EOF error in that case and
+ * exit.  In this situation, kluge_around_eof will be > 0. */
+static void whine_about_eof(int fd)
 {
-       if (kludge_around_eof)
-               exit_cleanup(0);
+       if (kluge_around_eof && fd == sock_f_in) {
+               int i;
+               if (kluge_around_eof > 0)
+                       exit_cleanup(0);
+               /* If we're still here after 10 seconds, exit with an error. */
+               for (i = 10*1000/20; i--; )
+                       msleep(20);
+       }
 
        rprintf(FERROR, RSYNC_NAME ": connection unexpectedly closed "
-               "(%.0f bytes read so far)\n",
-               (double)stats.total_read);
-
-       exit_cleanup(RERR_STREAMIO);
-}
-
-
-static void die_from_readerr(int err)
-{
-       /* this prevents us trying to write errors on a dead socket */
-       io_multiplexing_close();
+               "(%.0f bytes received so far) [%s]\n",
+               (double)stats.total_read, who_am_i());
 
-       rsyserr(FERROR, err, "read error");
        exit_cleanup(RERR_STREAMIO);
 }
 
@@ -388,11 +420,7 @@ static int read_timeout(int fd, char *buf, size_t len)
                FD_ZERO(&r_fds);
                FD_ZERO(&w_fds);
                FD_SET(fd, &r_fds);
-               if (msg_fd_in >= 0) {
-                       FD_SET(msg_fd_in, &r_fds);
-                       if (msg_fd_in > maxfd)
-                               maxfd = msg_fd_in;
-               } else if (msg_list_head) {
+               if (msg_list_head) {
                        FD_SET(msg_fd_out, &w_fds);
                        if (msg_fd_out > maxfd)
                                maxfd = msg_fd_out;
@@ -429,9 +457,7 @@ static int read_timeout(int fd, char *buf, size_t len)
                        continue;
                }
 
-               if (msg_fd_in >= 0 && FD_ISSET(msg_fd_in, &r_fds))
-                       read_msg_fd();
-               else if (msg_list_head && FD_ISSET(msg_fd_out, &w_fds))
+               if (msg_list_head && FD_ISSET(msg_fd_out, &w_fds))
                        msg_list_push(NORMAL_FLUSH);
 
                if (io_filesfrom_f_out >= 0) {
@@ -504,17 +530,23 @@ static int read_timeout(int fd, char *buf, size_t len)
 
                if (n <= 0) {
                        if (n == 0)
-                               whine_about_eof(); /* Doesn't return. */
+                               whine_about_eof(fd); /* Doesn't return. */
                        if (errno == EINTR || errno == EWOULDBLOCK
                            || errno == EAGAIN)
                                continue;
-                       die_from_readerr(errno); /* Doesn't return. */
+
+                       /* Don't write errors on a dead socket. */
+                       if (fd == sock_f_in)
+                               close_multiplexing_out();
+                       rsyserr(FERROR, errno, "read error");
+                       exit_cleanup(RERR_STREAMIO);
                }
 
                buf += n;
                len -= n;
                ret += n;
-               if (io_timeout)
+
+               if (io_timeout && fd == sock_f_in)
                        last_io = time(NULL);
        }
 
@@ -529,7 +561,7 @@ int read_filesfrom_line(int fd, char *fname)
 {
        char ch, *s, *eob = fname + MAXPATHLEN - 1;
        int cnt;
-       int reading_remotely = remote_filesfrom_file != NULL;
+       int reading_remotely = filesfrom_host != NULL;
        int nulls = eol_nulls || reading_remotely;
 
   start:
@@ -569,6 +601,57 @@ int read_filesfrom_line(int fd, char *fname)
 }
 
 
+static char *iobuf_out;
+static int iobuf_out_cnt;
+
+void io_start_buffering_out(void)
+{
+       if (iobuf_out)
+               return;
+       if (!(iobuf_out = new_array(char, IO_BUFFER_SIZE)))
+               out_of_memory("io_start_buffering_out");
+       iobuf_out_cnt = 0;
+}
+
+
+static char *iobuf_in;
+static size_t iobuf_in_siz;
+
+void io_start_buffering_in(void)
+{
+       if (iobuf_in)
+               return;
+       iobuf_in_siz = 2 * IO_BUFFER_SIZE;
+       if (!(iobuf_in = new_array(char, iobuf_in_siz)))
+               out_of_memory("io_start_buffering_in");
+}
+
+
+void io_end_buffering(void)
+{
+       io_flush(NORMAL_FLUSH);
+       if (!io_multiplexing_out) {
+               free(iobuf_out);
+               iobuf_out = NULL;
+       }
+}
+
+
+void maybe_send_keepalive(int allowed_lull, int ndx)
+{
+       if (time(NULL) - last_io >= allowed_lull) {
+               if (!iobuf_out || !iobuf_out_cnt) {
+                       if (protocol_version < 29)
+                               return; /* there's nothing we can do */
+                       write_int(sock_f_out, ndx);
+                       write_shortint(sock_f_out, ITEM_IS_NEW);
+               }
+               if (iobuf_out)
+                       io_flush(NORMAL_FLUSH);
+       }
+}
+
+
 /**
  * Continue trying to read len bytes - don't return until len has been
  * read.
@@ -593,31 +676,23 @@ 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;
        int tag, ret = 0;
-       char line[1024];
-       static char *buffer;
-       static size_t bufferIdx = 0;
-       static size_t bufferSz;
+       char line[MAXPATHLEN+1];
 
-       if (fd != multiplex_in_fd)
+       if (!iobuf_in || fd != sock_f_in)
                return read_timeout(fd, buf, len);
 
        if (!io_multiplexing_in && remaining == 0) {
-               if (!buffer) {
-                       bufferSz = 2 * IO_BUFFER_SIZE;
-                       buffer   = new_array(char, bufferSz);
-                       if (!buffer)
-                               out_of_memory("readfd_unbuffered");
-               }
-               remaining = read_timeout(fd, buffer, bufferSz);
-               bufferIdx = 0;
+               remaining = read_timeout(fd, iobuf_in, iobuf_in_siz);
+               iobuf_in_ndx = 0;
        }
 
        while (ret == 0) {
                if (remaining) {
                        len = MIN(len, remaining);
-                       memcpy(buf, buffer + bufferIdx, len);
-                       bufferIdx += len;
+                       memcpy(buf, iobuf_in + iobuf_in_ndx, len);
+                       iobuf_in_ndx += len;
                        remaining -= len;
                        ret = len;
                        break;
@@ -631,20 +706,46 @@ static int readfd_unbuffered(int fd, char *buf, size_t len)
 
                switch (tag) {
                case MSG_DATA:
-                       if (!buffer || remaining > bufferSz) {
-                               buffer = realloc_array(buffer, char, remaining);
-                               if (!buffer)
+                       if (remaining > iobuf_in_siz) {
+                               if (!(iobuf_in = realloc_array(iobuf_in, char,
+                                                              remaining)))
                                        out_of_memory("readfd_unbuffered");
-                               bufferSz = remaining;
+                               iobuf_in_siz = remaining;
+                       }
+                       read_loop(fd, iobuf_in, remaining);
+                       iobuf_in_ndx = 0;
+                       break;
+               case MSG_DELETED:
+                       if (remaining >= sizeof line) {
+                               rprintf(FERROR, "invalid multi-message %d:%ld\n",
+                                       tag, (long)remaining);
+                               exit_cleanup(RERR_STREAMIO);
                        }
-                       read_loop(fd, buffer, remaining);
-                       bufferIdx = 0;
+                       read_loop(fd, line, remaining);
+                       line[remaining] = '\0';
+                       /* A directory name was sent with the trailing null */
+                       if (remaining > 0 && !line[remaining-1])
+                               log_delete(line, S_IFDIR);
+                       else
+                               log_delete(line, S_IFREG);
+                       remaining = 0;
+                       break;
+               case MSG_SUCCESS:
+                       if (remaining != 4) {
+                               rprintf(FERROR, "invalid multi-message %d:%ld\n",
+                                       tag, (long)remaining);
+                               exit_cleanup(RERR_STREAMIO);
+                       }
+                       read_loop(fd, line, remaining);
+                       successful_send(IVAL(line, 0));
+                       remaining = 0;
                        break;
                case MSG_INFO:
                case MSG_ERROR:
                        if (remaining >= sizeof line) {
-                               rprintf(FERROR, "multiplexing overflow %d:%ld\n\n",
-                                       tag, (long)remaining);
+                               rprintf(FERROR,
+                                       "[%s] multiplexing overflow %d:%ld\n\n",
+                                       who_am_i(), tag, (long)remaining);
                                exit_cleanup(RERR_STREAMIO);
                        }
                        read_loop(fd, line, remaining);
@@ -652,7 +753,8 @@ static int readfd_unbuffered(int fd, char *buf, size_t len)
                        remaining = 0;
                        break;
                default:
-                       rprintf(FERROR, "unexpected tag %d\n", tag);
+                       rprintf(FERROR, "[%s] unexpected tag %d\n",
+                               who_am_i(), tag);
                        exit_cleanup(RERR_STREAMIO);
                }
        }
@@ -684,8 +786,17 @@ static void readfd(int fd, char *buffer, size_t N)
                if ((size_t)write(batch_fd, buffer, total) != total)
                        exit_cleanup(RERR_FILEIO);
        }
-       
-       stats.total_read += total;
+
+       if (fd == sock_f_in)
+               stats.total_read += total;
+}
+
+
+int read_shortint(int f)
+{
+       uchar b[2];
+       readfd(f, (char *)b, 2);
+       return (b[1] << 8) + b[0];
 }
 
 
@@ -710,8 +821,8 @@ int64 read_longint(int f)
        if ((int32)ret != (int32)0xffffffff)
                return ret;
 
-#ifdef NO_INT64
-       rprintf(FERROR,"Integer overflow - attempted 64 bit offset\n");
+#if SIZEOF_INT64 < 8
+       rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
        exit_cleanup(RERR_UNSUPPORTED);
 #else
        readfd(f,b,8);
@@ -728,17 +839,59 @@ void read_buf(int f,char *buf,size_t len)
 
 void read_sbuf(int f,char *buf,size_t len)
 {
-       read_buf(f,buf,len);
-       buf[len] = 0;
+       readfd(f, buf, len);
+       buf[len] = '\0';
 }
 
-unsigned char read_byte(int f)
+uchar read_byte(int f)
 {
-       unsigned char c;
-       read_buf(f, (char *)&c, 1);
+       uchar c;
+       readfd(f, (char *)&c, 1);
        return c;
 }
 
+/* Populate a sum_struct with values from the socket.  This is
+ * called by both the sender and the receiver. */
+void read_sum_head(int f, struct sum_struct *sum)
+{
+       sum->count = read_int(f);
+       sum->blength = read_int(f);
+       if (sum->blength < 0 || sum->blength > MAX_BLOCK_SIZE) {
+               rprintf(FERROR, "[%s] Invalid block length %ld\n",
+                       who_am_i(), (long)sum->blength);
+               exit_cleanup(RERR_PROTOCOL);
+       }
+       sum->s2length = protocol_version < 27 ? csum_length : (int)read_int(f);
+       if (sum->s2length < 0 || sum->s2length > MD4_SUM_LENGTH) {
+               rprintf(FERROR, "[%s] Invalid checksum length %d\n",
+                       who_am_i(), sum->s2length);
+               exit_cleanup(RERR_PROTOCOL);
+       }
+       sum->remainder = read_int(f);
+       if (sum->remainder < 0 || sum->remainder > sum->blength) {
+               rprintf(FERROR, "[%s] Invalid remainder length %ld\n",
+                       who_am_i(), (long)sum->remainder);
+               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.
@@ -796,12 +949,12 @@ static void sleep_for_bwlimit(int bytes_written)
 }
 
 
-/**
- * Write len bytes to the file descriptor @p fd.
+/* Write len bytes to the file descriptor fd, looping as necessary to get
+ * the job done and also (in certain circumstnces) reading any data on
+ * msg_fd_in to avoid deadlock.
  *
  * This function underlies the multiplexing system.  The body of the
- * application never calls this function directly.
- **/
+ * application never calls this function directly. */
 static void writefd_unbuffered(int fd,char *buf,size_t len)
 {
        size_t n, total = 0;
@@ -809,11 +962,6 @@ static void writefd_unbuffered(int fd,char *buf,size_t len)
        int maxfd, count, ret;
        struct timeval tv;
 
-       if (fd == msg_fd_out) {
-               rprintf(FERROR, "Internal error: wrong write used in receiver.\n");
-               exit_cleanup(RERR_PROTOCOL);
-       }
-
        no_flush++;
 
        while (total < len) {
@@ -821,12 +969,17 @@ static void writefd_unbuffered(int fd,char *buf,size_t len)
                FD_SET(fd,&w_fds);
                maxfd = fd;
 
-               if (msg_fd_in >= 0) {
+               if (msg_fd_in >= 0 && len-total >= contiguous_write_len) {
                        FD_ZERO(&r_fds);
                        FD_SET(msg_fd_in,&r_fds);
                        if (msg_fd_in > maxfd)
                                maxfd = msg_fd_in;
                }
+               if (fd != sock_f_out && iobuf_out_cnt && no_flush == 1) {
+                       FD_SET(sock_f_out, &w_fds);
+                       if (sock_f_out > maxfd)
+                               maxfd = sock_f_out;
+               }
 
                tv.tv_sec = select_timeout;
                tv.tv_usec = 0;
@@ -845,8 +998,14 @@ static void writefd_unbuffered(int fd,char *buf,size_t len)
                if (msg_fd_in >= 0 && FD_ISSET(msg_fd_in, &r_fds))
                        read_msg_fd();
 
-               if (!FD_ISSET(fd, &w_fds))
+               if (!FD_ISSET(fd, &w_fds)) {
+                       if (fd != sock_f_out && iobuf_out_cnt) {
+                               no_flush--;
+                               io_flush(NORMAL_FLUSH);
+                               no_flush++;
+                       }
                        continue;
+               }
 
                n = len - total;
                if (bwlimit && n > bwlimit_writemax)
@@ -864,129 +1023,129 @@ static void writefd_unbuffered(int fd,char *buf,size_t len)
                        }
 
                        /* Don't try to write errors back across the stream. */
-                       io_multiplexing_close();
+                       if (fd == sock_f_out)
+                               close_multiplexing_out();
                        rsyserr(FERROR, errno,
-                               "writefd_unbuffered failed to write %ld bytes: phase \"%s\"",
-                               (long)len, io_write_phase);
+                               "writefd_unbuffered failed to write %ld bytes: phase \"%s\" [%s]",
+                               (long)len, io_write_phase, who_am_i());
+                       /* If the other side is sending us error messages, try
+                        * to grab any messages they sent before they died. */
+                       while (fd == sock_f_out && io_multiplexing_in) {
+                               io_timeout = select_timeout = 30;
+                               ignore_timeout = 0;
+                               readfd_unbuffered(sock_f_in, io_filesfrom_buf,
+                                                 sizeof io_filesfrom_buf);
+                       }
                        exit_cleanup(RERR_STREAMIO);
                }
 
-               sleep_for_bwlimit(ret);
-
                total += ret;
 
-               if (io_timeout)
-                       last_io = time(NULL);
+               if (fd == sock_f_out) {
+                       if (io_timeout)
+                               last_io = time(NULL);
+                       sleep_for_bwlimit(ret);
+               }
        }
 
        no_flush--;
 }
 
 
-static char *io_buffer;
-static int io_buffer_count;
-
-void io_start_buffering_out(int fd)
-{
-       if (io_buffer)
-               return;
-       multiplex_out_fd = fd;
-       io_buffer = new_array(char, IO_BUFFER_SIZE);
-       if (!io_buffer)
-               out_of_memory("writefd");
-       io_buffer_count = 0;
-}
-
-void io_start_buffering_in(int fd)
-{
-       multiplex_in_fd = fd;
-}
-
 /**
  * Write an message to a multiplexed stream. If this fails then rsync
  * exits.
  **/
-static void mplex_write(int fd, enum msgcode code, char *buf, size_t len)
+static void mplex_write(enum msgcode code, char *buf, size_t len)
 {
        char buffer[4096];
        size_t n = len;
 
        SIVAL(buffer, 0, ((MPLEX_BASE + (int)code)<<24) + len);
 
+       /* When the generator reads messages from the msg_fd_in pipe, it can
+        * cause output to occur down the socket.  Setting contiguous_write_len
+        * prevents the reading of msg_fd_in once we actually start to write
+        * this sequence of data (though we might read it before the start). */
+       if (am_generator && msg_fd_in >= 0)
+               contiguous_write_len = len + 4;
+
        if (n > sizeof buffer - 4)
                n = sizeof buffer - 4;
 
        memcpy(&buffer[4], buf, n);
-       writefd_unbuffered(fd, buffer, n+4);
+       writefd_unbuffered(sock_f_out, buffer, n+4);
 
        len -= n;
        buf += n;
 
        if (len)
-               writefd_unbuffered(fd, buf, len);
+               writefd_unbuffered(sock_f_out, buf, len);
+
+       if (am_generator && msg_fd_in >= 0)
+               contiguous_write_len = 0;
 }
 
 
 void io_flush(int flush_it_all)
 {
-       int fd = multiplex_out_fd;
-
        msg_list_push(flush_it_all);
 
-       if (!io_buffer_count || no_flush)
+       if (!iobuf_out_cnt || no_flush)
                return;
 
        if (io_multiplexing_out)
-               mplex_write(fd, MSG_DATA, io_buffer, io_buffer_count);
+               mplex_write(MSG_DATA, iobuf_out, iobuf_out_cnt);
        else
-               writefd_unbuffered(fd, io_buffer, io_buffer_count);
-       io_buffer_count = 0;
+               writefd_unbuffered(sock_f_out, iobuf_out, iobuf_out_cnt);
+       iobuf_out_cnt = 0;
 }
 
 
-void io_end_buffering(void)
-{
-       io_flush(NORMAL_FLUSH);
-       if (!io_multiplexing_out) {
-               free(io_buffer);
-               io_buffer = NULL;
-       }
-}
-
 static void writefd(int fd,char *buf,size_t len)
 {
-       stats.total_written += 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;
+
        if (fd == write_batch_monitor_out) {
                if ((size_t)write(batch_fd, buf, len) != len)
                        exit_cleanup(RERR_FILEIO);
        }
 
-       if (!io_buffer || fd != multiplex_out_fd) {
+       if (!iobuf_out || fd != sock_f_out) {
                writefd_unbuffered(fd, buf, len);
                return;
        }
 
        while (len) {
-               int n = MIN((int)len, IO_BUFFER_SIZE-io_buffer_count);
+               int n = MIN((int)len, IO_BUFFER_SIZE - iobuf_out_cnt);
                if (n > 0) {
-                       memcpy(io_buffer+io_buffer_count, buf, n);
+                       memcpy(iobuf_out+iobuf_out_cnt, buf, n);
                        buf += n;
                        len -= n;
-                       io_buffer_count += n;
+                       iobuf_out_cnt += n;
                }
 
-               if (io_buffer_count == IO_BUFFER_SIZE)
+               if (iobuf_out_cnt == IO_BUFFER_SIZE)
                        io_flush(NORMAL_FLUSH);
        }
 }
 
 
+void write_shortint(int f, int x)
+{
+       uchar b[2];
+       b[0] = x;
+       b[1] = x >> 8;
+       writefd(f, (char *)b, 2);
+}
+
+
 void write_int(int f,int32 x)
 {
        char b[4];
@@ -1016,8 +1175,8 @@ void write_longint(int f, int64 x)
                return;
        }
 
-#ifdef NO_INT64
-       rprintf(FERROR,"Integer overflow - attempted 64 bit offset\n");
+#if SIZEOF_INT64 < 8
+       rprintf(FERROR, "Integer overflow: attempted 64-bit offset\n");
        exit_cleanup(RERR_UNSUPPORTED);
 #else
        write_int(f, (int32)0xFFFFFFFF);
@@ -1034,19 +1193,17 @@ void write_buf(int f,char *buf,size_t len)
 }
 
 /** Write a string to the connection */
-static void write_sbuf(int f,char *buf)
+void write_sbuf(int f, char *buf)
 {
-       write_buf(f, buf, strlen(buf));
+       writefd(f, buf, strlen(buf));
 }
 
-
-void write_byte(int f,unsigned char c)
+void write_byte(int f, uchar c)
 {
-       write_buf(f,(char *)&c,1);
+       writefd(f, (char *)&c, 1);
 }
 
 
-
 /**
  * Read a line of up to @p maxlen characters into @p buf (not counting
  * the trailing null).  Strips the (required) trailing newline and all
@@ -1091,19 +1248,18 @@ void io_printf(int fd, const char *format, ...)
 
 
 /** Setup for multiplexing a MSG_* stream with the data stream. */
-void io_start_multiplex_out(int fd)
+void io_start_multiplex_out(void)
 {
-       multiplex_out_fd = fd;
        io_flush(NORMAL_FLUSH);
-       io_start_buffering_out(fd);
+       io_start_buffering_out();
        io_multiplexing_out = 1;
 }
 
 /** Setup for multiplexing a MSG_* stream with the data stream. */
-void io_start_multiplex_in(int fd)
+void io_start_multiplex_in(void)
 {
-       multiplex_in_fd = fd;
        io_flush(NORMAL_FLUSH);
+       io_start_buffering_in();
        io_multiplexing_in = 1;
 }
 
@@ -1115,18 +1271,25 @@ int io_multiplex_write(enum msgcode code, char *buf, size_t len)
 
        io_flush(NORMAL_FLUSH);
        stats.total_written += (len+4);
-       mplex_write(multiplex_out_fd, code, buf, len);
+       mplex_write(code, buf, len);
        return 1;
 }
 
+void close_multiplexing_in(void)
+{
+       io_multiplexing_in = 0;
+}
+
 /** Stop output multiplexing. */
-void io_multiplexing_close(void)
+void close_multiplexing_out(void)
 {
        io_multiplexing_out = 0;
 }
 
 void start_write_batch(int fd)
 {
+       write_stream_flags(batch_fd);
+
        /* Some communication has already taken place, but we don't
         * enable batch writing until here so that we can write a
         * canonical record of the communication even though the
@@ -1134,7 +1297,6 @@ void start_write_batch(int fd)
         * is involved. */
        write_int(batch_fd, protocol_version);
        write_int(batch_fd, checksum_seed);
-       stats.total_written -= sizeof (int) * 2;
 
        if (am_sender)
                write_batch_monitor_out = fd;