Change a variable name in read_a_msg().
[rsync/rsync.git] / io.c
diff --git a/io.c b/io.c
index b2b5e48..d0ddaf5 100644 (file)
--- a/io.c
+++ b/io.c
@@ -69,6 +69,7 @@ int ignore_timeout = 0;
 int batch_fd = -1;
 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;
@@ -76,6 +77,9 @@ int kluge_around_eof = 0;
 int sock_f_in = -1;
 int sock_f_out = -1;
 
+int64 total_data_read = 0;
+int64 total_data_written = 0;
+
 static struct {
        xbuf in, out, msg;
        int in_fd;
@@ -94,7 +98,8 @@ static int write_batch_monitor_in = -1;
 static int write_batch_monitor_out = -1;
 
 static int ff_forward_fd = -1;
-static char ff_lastchar;
+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;
@@ -111,6 +116,17 @@ static char int_byte_extra[64] = {
        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)
 #define OUT_MULTIPLEXED (iobuf.out_empty_len != 0)
 
@@ -132,6 +148,8 @@ 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(void)
@@ -169,9 +187,9 @@ static void check_timeout(void)
  * 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(int fd)
+static NORETURN void whine_about_eof(BOOL allow_kluge)
 {
-       if (kluge_around_eof && fd == sock_f_in) {
+       if (kluge_around_eof && allow_kluge) {
                int i;
                if (kluge_around_eof > 0)
                        exit_cleanup(0);
@@ -348,8 +366,8 @@ static void forward_filesfrom_data(void)
                        ff_forward_fd = -1;
                        write_buf(iobuf.out_fd, "\0\0", ff_lastchar ? 2 : 1);
                        free_xbuf(&ff_xb);
-                       if (protocol_version == 30)
-                               io_start_multiplex_out(iobuf.out_fd);
+                       if (ff_reenable_multiplex >= 0)
+                               io_start_multiplex_out(ff_reenable_multiplex);
                }
                return;
        }
@@ -438,6 +456,39 @@ static void forward_filesfrom_data(void)
        }
 }
 
+void reduce_iobuf_size(xbuf *out, size_t new_size)
+{
+       if (new_size < out->size) {
+               if (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);
+               if (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;
+       }
+}
+
 /* Perform buffered input and output until specified conditions are met.  When
  * given a "needed" read requirement, we'll return without doing any I/O if the
  * iobuf.in bytes are already available.  When reading, we'll read as many
@@ -451,10 +502,11 @@ static void forward_filesfrom_data(void)
  * The iobuf.out and iobuf.msg buffers are circular, so some writes into them
  * will need to be split when the data needs to wrap around to the start.  In
  * order to help make this easier for some operations (such as the use of
- * SIVAL() into the buffer) the buffers MUST have 4 bytes of overflow space at
- * the end that is not not counted in the "size".  The iobuf.in buffer is not
- * (currently) circular.  To facilitate the handling of MSG_DATA bytes as they
- * are read-from/written-into the buffers, see the three raw_* iobuf vars.
+ * SIVAL() into the buffer) a buffer may be temporarily shortened, but the
+ * original size will be automatically restored.  The iobuf.in buffer is also
+ * circular, so callers may need to split their reading of the data if it spans
+ * the end.  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:
  *
@@ -471,8 +523,6 @@ static void forward_filesfrom_data(void)
  *
  *    - Make this routine able to read the generator-to-receiver batch flow?
  *
- *    - Make the input buffer circular?
- *
  * 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
@@ -494,36 +544,17 @@ static char *perform_io(size_t needed, int flags)
 
        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 %ld bytes, iobuf.in.buf is only %ld bytes.\n",
+                               (long)needed, (long)iobuf.in.size);
+                       exit_cleanup(RERR_PROTOCOL);
+               }
+
                if (DEBUG_GTE(IO, 3)) {
                        rprintf(FINFO, "[%s] perform_io(%ld, %sinput)\n",
                                who_am_i(), (long)needed, flags & PIO_CONSUME_INPUT ? "consume&" : "");
                }
-
-               /* Make sure the input buffer is big enough to hold "needed" bytes.
-                * Also make sure it will fit in the free space at the end, or
-                * else we need to shift some bytes. */
-               if (needed && iobuf.in.size < needed) {
-                       if (!(iobuf.in.buf = realloc_array(iobuf.in.buf, char, needed)))
-                               out_of_memory("perform_io");
-                       if (DEBUG_GTE(IO, 4)) {
-                               rprintf(FINFO, "[%s] resized input buffer from %ld to %ld bytes.\n",
-                                       who_am_i(), (long)iobuf.in.size, (long)needed);
-                       }
-                       iobuf.in.size = needed;
-               }
-               if (iobuf.in.size - iobuf.in.pos < needed
-                || (iobuf.in.len < needed && iobuf.in.len < 1024
-                 && iobuf.in.size - (iobuf.in.pos + iobuf.in.len) < 1024)) {
-                       memmove(iobuf.in.buf, iobuf.in.buf + iobuf.in.pos, iobuf.in.len);
-                       if (DEBUG_GTE(IO, 4)) {
-                               rprintf(FINFO,
-                                       "[%s] moved %ld bytes from %ld to 0 in the input buffer (size=%ld, needed=%ld).\n",
-                                       who_am_i(), (long)iobuf.in.len, (long)iobuf.in.pos, (long)iobuf.in.size, (long)needed);
-                       }
-                       if (iobuf.raw_input_ends_before)
-                               iobuf.raw_input_ends_before -= iobuf.in.pos;
-                       iobuf.in.pos = 0;
-               }
                break;
 
        case PIO_NEED_OUTROOM:
@@ -537,8 +568,8 @@ static char *perform_io(size_t needed, int flags)
                if (DEBUG_GTE(IO, 3)) {
                        rprintf(FINFO, "[%s] perform_io(%ld, outroom) needs to flush %ld\n",
                                who_am_i(), (long)needed,
-                               iobuf.out.len > iobuf.out.size - needed
-                               ? (long)iobuf.out.len - (iobuf.out.size - needed) : 0L);
+                               iobuf.out.len + needed > iobuf.out.size
+                               ? (long)(iobuf.out.len + needed - iobuf.out.size) : 0L);
                }
                break;
 
@@ -553,8 +584,8 @@ static char *perform_io(size_t needed, int flags)
                if (DEBUG_GTE(IO, 3)) {
                        rprintf(FINFO, "[%s] perform_io(%ld, msgroom) needs to flush %ld\n",
                                who_am_i(), (long)needed,
-                               iobuf.out.len > iobuf.msg.size - needed
-                               ? (long)iobuf.out.len - (iobuf.msg.size - needed) : 0L);
+                               iobuf.msg.len + needed > iobuf.msg.size
+                               ? (long)(iobuf.msg.len + needed - iobuf.msg.size) : 0L);
                }
                break;
 
@@ -574,11 +605,13 @@ static char *perform_io(size_t needed, int flags)
                                goto double_break;
                        break;
                case PIO_NEED_OUTROOM:
-                       if (iobuf.out.len <= iobuf.out.size - needed)
+                       /* 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 <= iobuf.msg.size - needed)
+                       if (iobuf.msg.len + needed <= iobuf.msg.size)
                                goto double_break;
                        break;
                }
@@ -587,7 +620,7 @@ static char *perform_io(size_t needed, int flags)
 
                FD_ZERO(&r_fds);
                FD_ZERO(&e_fds);
-               if (iobuf.in_fd >= 0 && iobuf.in.size - (iobuf.in.pos + iobuf.in.len)) {
+               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);
@@ -608,22 +641,12 @@ static char *perform_io(size_t needed, int flags)
                        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) {
-                                       size_t val;
-
                                        /* 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 ((val = iobuf.out.size - iobuf.raw_data_header_pos) < 4) {
-                                               /* We used some of the overflow bytes, so move them. */
-                                               if (DEBUG_GTE(IO, 4)) {
-                                                       rprintf(FINFO, "[%s] wrap-bytes moved: %d (perform_io)\n",
-                                                               who_am_i(), (int)val);
-                                               }
-                                               memcpy(iobuf.out.buf, iobuf.out.buf + iobuf.out.size, 4 - val);
-                                       }
 
                                        if (DEBUG_GTE(IO, 1)) {
                                                rprintf(FINFO, "[%s] send_msg(%d, %ld)\n",
@@ -634,6 +657,14 @@ static char *perform_io(size_t needed, int flags)
                                        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;
                                }
 
@@ -655,11 +686,19 @@ static char *perform_io(size_t needed, int flags)
                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:
@@ -670,8 +709,7 @@ static char *perform_io(size_t needed, int flags)
                }
 
                if (extra_flist_sending_enabled) {
-                       if (file_total - file_old_total < MAX_FILECNT_LOOKAHEAD
-                        && file_total - file_old_total >= MIN_FILECNT_LOOKAHEAD)
+                       if (file_total - file_old_total < MAX_FILECNT_LOOKAHEAD)
                                tv.tv_sec = 0;
                        else {
                                extra_flist_sending_enabled = False;
@@ -699,13 +737,18 @@ static char *perform_io(size_t needed, int flags)
                }
 
                if (iobuf.in_fd >= 0 && FD_ISSET(iobuf.in_fd, &r_fds)) {
-                       size_t pos = iobuf.in.pos + iobuf.in.len;
-                       size_t len = iobuf.in.size - pos;
+                       size_t len, pos = iobuf.in.pos + iobuf.in.len;
                        int 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)
-                                               whine_about_eof(iobuf.in_fd); /* Doesn't return. */
+                                               iobuf.in_fd = -2;
                                        batch_fd = -1;
                                        continue;
                                }
@@ -719,7 +762,7 @@ static char *perform_io(size_t needed, int flags)
                                                rsyserr(FERROR_SOCKET, errno, "read error");
                                        } else
                                                rsyserr(FERROR, errno, "read error");
-                                       exit_cleanup(RERR_STREAMIO);
+                                       exit_cleanup(RERR_SOCKETIO);
                                }
                        }
                        if (msgs2stderr && DEBUG_GTE(IO, 2))
@@ -747,9 +790,11 @@ static char *perform_io(size_t needed, int flags)
                                else {
                                        /* Don't write errors on a dead socket. */
                                        msgs2stderr = 1;
-                                       out->len = iobuf.raw_flushing_ends_before = out->pos = 0;
-                                       rsyserr(FERROR_SOCKET, errno, "write error");
-                                       exit_cleanup(RERR_STREAMIO);
+                                       iobuf.out_fd = -2;
+                                       iobuf.out.len = iobuf.msg.len = iobuf.raw_flushing_ends_before = 0;
+                                       rsyserr(FERROR_SOCKET, errno, "[%s] write error", who_am_i());
+                                       drain_multiplex_messages();
+                                       exit_cleanup(RERR_SOCKETIO);
                                }
                        }
                        if (msgs2stderr && DEBUG_GTE(IO, 2)) {
@@ -768,16 +813,26 @@ static char *perform_io(size_t needed, int flags)
                                if (iobuf.raw_flushing_ends_before)
                                        iobuf.raw_flushing_ends_before -= out->size;
                                out->pos = 0;
-                       }
-                       if (out->pos == iobuf.raw_flushing_ends_before)
+                               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;
                        }
                }
 
+               /* We need to help prevent deadlock by doing what reading
+                * we can whenever we are here trying to write. */
+               if (IN_MULTIPLEXED && !(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
@@ -793,16 +848,59 @@ static char *perform_io(size_t needed, int flags)
        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];
+
+       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 never used for MSG_DATA. */
 int send_msg(enum msgcode code, const char *buf, size_t len, int convert)
 {
        char *hdr;
-       size_t pos;
+       size_t needed, pos;
        BOOL want_debug = DEBUG_GTE(IO, 1) && convert >= 0 && (msgs2stderr || code != MSG_INFO);
 
        if (!OUT_MULTIPLEXED)
@@ -811,24 +909,35 @@ int send_msg(enum msgcode code, const char *buf, size_t len, int convert)
        if (want_debug)
                rprintf(FINFO, "[%s] send_msg(%d, %ld)\n", who_am_i(), (int)code, (long)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 a potential conversion. */
-               if (iobuf.msg.len + len*2 + 4 > iobuf.msg.size)
-                       perform_io(len*2 + 4, PIO_NEED_MSGROOM);
+               /* Ensuring double-size room leaves space for maximal conversion expansion. */
+               needed = len*2 + 4 + 3;
        } else
 #endif
-       if (iobuf.msg.len + len + 4 > iobuf.msg.size)
-               perform_io(len + 4, PIO_NEED_MSGROOM);
+               needed = len + 4 + 3;
+       if (iobuf.msg.len + needed > iobuf.msg.size)
+               perform_io(needed, PIO_NEED_MSGROOM);
 
        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; /* Leave room for the coming header bytes. */
+       iobuf.msg.len += 4; /* Allocate room for the coming header bytes. */
 
 #ifdef ICONV_OPTION
        if (convert > 0) {
@@ -863,13 +972,6 @@ int send_msg(enum msgcode code, const char *buf, size_t len, int convert)
        }
 
        SIVAL(hdr, 0, ((MPLEX_BASE + (int)code)<<24) + len);
-       /* If the header used any overflow bytes, move them to the start. */
-       if ((pos = hdr+4 - iobuf.msg.buf) > iobuf.msg.size) {
-               size_t siz = pos - iobuf.msg.size;
-               if (DEBUG_GTE(IO, 4))
-                       rprintf(FINFO, "[%s] wrap-bytes moved: %d (send_msg)\n", who_am_i(), (int)siz);
-               memcpy(iobuf.msg.buf, hdr+4 - siz, siz);
-       }
 
        if (want_debug && convert > 0)
                rprintf(FINFO, "[%s] converted msg len=%ld\n", who_am_i(), (long)len);
@@ -1016,13 +1118,12 @@ int get_hlink_num(void)
  * for recv_file_list() to use. */
 void start_filesfrom_forwarding(int fd)
 {
-       if (protocol_version == 30) {
-               /* Older protocols send the files-from data w/o packaging it in
-                * multiplexed I/O packets, but protocol 30 messed up and did
-                * this after starting multiplexing.  We'll temporarily switch
+       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. */
-               io_end_multiplex_out(MPLX_TO_BUFFERED);
+               ff_reenable_multiplex = io_end_multiplex_out(MPLX_TO_BUFFERED);
        }
        ff_forward_fd = fd;
 
@@ -1135,36 +1236,26 @@ void read_args(int f_in, char *mod_name, char *buf, size_t bufsiz, int rl_nulls,
        *argv_p = argv;
 }
 
-int io_start_buffering_out(int f_out)
+BOOL io_start_buffering_out(int f_out)
 {
        if (msgs2stderr && DEBUG_GTE(IO, 2))
                rprintf(FINFO, "[%s] io_start_buffering_out(%d)\n", who_am_i(), f_out);
 
-       if (OUT_MULTIPLEXED && !iobuf.msg.buf) {
-               iobuf.msg.size = IO_BUFFER_SIZE - 4;
-               if (!(iobuf.msg.buf = new_array(char, iobuf.msg.size + 4)))
-                       out_of_memory("io_start_buffering_out");
-               iobuf.msg.pos = iobuf.msg.len = 0;
-       }
-
        if (iobuf.out.buf) {
                if (iobuf.out_fd == -1)
                        iobuf.out_fd = f_out;
-               assert(f_out == iobuf.out_fd);
-               return 0;
+               else
+                       assert(f_out == iobuf.out_fd);
+               return False;
        }
 
-       iobuf.out.size = IO_BUFFER_SIZE * 2 - 4;
-       /* The 4 overflow bytes makes some circular-buffer wrapping operations easier. */
-       if (!(iobuf.out.buf = new_array(char, iobuf.out.size + 4)))
-               out_of_memory("io_start_buffering_out");
-       iobuf.out.pos = iobuf.out.len = 0;
+       alloc_xbuf(&iobuf.out, ROUND_UP_1024(IO_BUFFER_SIZE * 2));
        iobuf.out_fd = f_out;
 
-       return 1;
+       return True;
 }
 
-int io_start_buffering_in(int f_in)
+BOOL io_start_buffering_in(int f_in)
 {
        if (msgs2stderr && DEBUG_GTE(IO, 2))
                rprintf(FINFO, "[%s] io_start_buffering_in(%d)\n", who_am_i(), f_in);
@@ -1172,19 +1263,15 @@ int io_start_buffering_in(int f_in)
        if (iobuf.in.buf) {
                if (iobuf.in_fd == -1)
                        iobuf.in_fd = f_in;
-               assert(f_in == iobuf.in_fd);
-               return 0;
+               else
+                       assert(f_in == iobuf.in_fd);
+               return False;
        }
 
-       iobuf.in.size = IO_BUFFER_SIZE;
-       if (!(iobuf.in.buf = new_array(char, iobuf.in.size)))
-               out_of_memory("io_start_buffering_in");
-
-       iobuf.in.pos = iobuf.in.len = 0;
-
+       alloc_xbuf(&iobuf.in, ROUND_UP_1024(IO_BUFFER_SIZE));
        iobuf.in_fd = f_in;
 
-       return 1;
+       return True;
 }
 
 void io_end_buffering_in(BOOL free_buffers)
@@ -1260,12 +1347,11 @@ void stop_flist_forward(void)
 /* Read a message from a multiplexed source. */
 static void read_a_msg(void)
 {
-       char *data, line[BIGPATHBUFLEN];
-       int tag;
+       char data[BIGPATHBUFLEN];
+       int tag, val;
        size_t msg_bytes;
 
-       data = perform_io(4, PIO_INPUT_AND_CONSUME);
-       tag = IVAL(data, 0);
+       tag = raw_read_int();
 
        msg_bytes = tag & 0xFFFFFF;
        tag = (tag >> 24) - MPLEX_BASE;
@@ -1286,33 +1372,41 @@ static void read_a_msg(void)
        case MSG_STATS:
                if (msg_bytes != sizeof stats.total_read || !am_generator)
                        goto invalid_msg;
-               data = perform_io(sizeof stats.total_read, PIO_INPUT_AND_CONSUME);
-               memcpy((char*)&stats.total_read, data, sizeof stats.total_read);
+               raw_read_buf((char*)&stats.total_read, sizeof stats.total_read);
                break;
        case MSG_REDO:
                if (msg_bytes != 4 || !am_generator)
                        goto invalid_msg;
-               data = perform_io(4, PIO_INPUT_AND_CONSUME);
-               got_flist_entry_status(FES_REDO, IVAL(data, 0));
+               got_flist_entry_status(FES_REDO, raw_read_int());
                break;
        case MSG_IO_ERROR:
                if (msg_bytes != 4 || am_sender)
                        goto invalid_msg;
-               data = perform_io(4, PIO_INPUT_AND_CONSUME);
-               io_error |= IVAL(data, 0);
+               val = raw_read_int();
+               io_error |= val;
                if (!am_generator)
-                       send_msg(MSG_IO_ERROR, data, 4, 0);
+                       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();
+               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:
                if (am_sender)
                        maybe_send_keepalive();
                break;
        case MSG_DELETED:
-               if (msg_bytes >= sizeof line)
+               if (msg_bytes >= sizeof data)
                        goto overflow;
                if (am_generator) {
-                       memcpy(line, perform_io(msg_bytes, PIO_INPUT_AND_CONSUME), msg_bytes);
-                       send_msg(MSG_DELETED, line, msg_bytes, 1);
+                       raw_read_buf(data, msg_bytes);
+                       send_msg(MSG_DELETED, data, msg_bytes, 1);
                        break;
                }
 #ifdef ICONV_OPTION
@@ -1322,12 +1416,12 @@ static void read_a_msg(void)
                        int add_null = 0;
                        int flags = ICB_INCLUDE_BAD | ICB_INIT;
 
-                       INIT_CONST_XBUF(outbuf, line);
+                       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;
-                               memcpy(ibuf + inbuf.len, perform_io(len, PIO_INPUT_AND_CONSUME), len);
+                               raw_read_buf(ibuf + inbuf.len, len);
                                inbuf.pos = 0;
                                inbuf.len += len;
                                if (!(msg_bytes -= len) && !ibuf[inbuf.len-1])
@@ -1349,13 +1443,13 @@ static void read_a_msg(void)
                        msg_bytes = outbuf.len;
                } else
 #endif
-                       memcpy(line, perform_io(msg_bytes, PIO_INPUT_AND_CONSUME), msg_bytes);
+                       raw_read_buf(data, msg_bytes);
                /* A directory name was sent with the trailing null */
-               if (msg_bytes > 0 && !line[msg_bytes-1])
-                       log_delete(line, S_IFDIR);
+               if (msg_bytes > 0 && !data[msg_bytes-1])
+                       log_delete(data, S_IFDIR);
                else {
-                       line[msg_bytes] = '\0';
-                       log_delete(line, S_IFREG);
+                       data[msg_bytes] = '\0';
+                       log_delete(data, S_IFREG);
                }
                break;
        case MSG_SUCCESS:
@@ -1366,20 +1460,20 @@ static void read_a_msg(void)
                                inc_recurse ? "/inc" : "");
                        exit_cleanup(RERR_STREAMIO);
                }
-               data = perform_io(4, PIO_INPUT_AND_CONSUME);
+               val = raw_read_int();
                if (am_generator)
-                       got_flist_entry_status(FES_SUCCESS, IVAL(data, 0));
+                       got_flist_entry_status(FES_SUCCESS, val);
                else
-                       successful_send(IVAL(data, 0));
+                       successful_send(val);
                break;
        case MSG_NO_SEND:
                if (msg_bytes != 4)
                        goto invalid_msg;
-               data = perform_io(4, PIO_INPUT_AND_CONSUME);
+               val = raw_read_int();
                if (am_generator)
-                       got_flist_entry_status(FES_NO_SEND, IVAL(data, 0));
+                       got_flist_entry_status(FES_NO_SEND, val);
                else
-                       send_msg(MSG_NO_SEND, data, 4, 0);
+                       send_msg_int(MSG_NO_SEND, val);
                break;
        case MSG_ERROR_SOCKET:
        case MSG_ERROR_UTF8:
@@ -1394,7 +1488,7 @@ static void read_a_msg(void)
        case MSG_ERROR:
        case MSG_ERROR_XFER:
        case MSG_WARNING:
-               if (msg_bytes >= sizeof line) {
+               if (msg_bytes >= sizeof data) {
                    overflow:
                        rprintf(FERROR,
                                "multiplexing overflow %d:%lu [%s%s]\n",
@@ -1402,16 +1496,51 @@ static void read_a_msg(void)
                                inc_recurse ? "/inc" : "");
                        exit_cleanup(RERR_STREAMIO);
                }
-               memcpy(line, perform_io(msg_bytes, PIO_INPUT_AND_CONSUME), msg_bytes);
-               rwrite((enum logcode)tag, line, msg_bytes, !am_generator);
+               raw_read_buf(data, msg_bytes);
+               rwrite((enum logcode)tag, data, msg_bytes, !am_generator);
                if (first_message) {
-                       if (list_only && !am_sender && tag == 1 && msg_bytes < sizeof line) {
-                               line[msg_bytes] = '\0';
-                               check_for_d_option_error(line);
+                       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 (DEBUG_GTE(EXIT, 3))
+                       rprintf(FINFO, "[%s] got MSG_ERROR_EXIT with %d bytes\n", who_am_i(), 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);
+                       }
+                       val = 0;
+               } else if (msg_bytes == 4) {
+                       val = raw_read_int();
+                       if (protocol_version >= 31) {
+                               if (am_generator) {
+                                       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);
+                               }
+                       }
+               } else
+                       goto invalid_msg;
+               /* 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" : "");
@@ -1419,6 +1548,24 @@ static void read_a_msg(void)
        }
 }
 
+static void drain_multiplex_messages(void)
+{
+       while (IN_MULTIPLEXED && 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)
@@ -1441,6 +1588,7 @@ void wait_for_receiver(void)
                        }
                } 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);
@@ -1451,6 +1599,7 @@ void wait_for_receiver(void)
                        if (preserve_hard_links)
                                match_hard_links(flist);
 #endif
+                       flist_receiving_enabled = True;
                }
        }
 }
@@ -1572,12 +1721,13 @@ 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(f); /* Doesn't return. */
+                       whine_about_eof(False); /* Doesn't return. */
                goto batch_copy;
        }
 
        if (!IN_MULTIPLEXED) {
-               memcpy(buf, perform_io(len, PIO_INPUT_AND_CONSUME), len);
+               raw_read_buf(buf, len);
+               total_data_read += len;
                if (forward_flist_data)
                        write_buf(iobuf.out_fd, buf, len);
          batch_copy:
@@ -1587,20 +1737,16 @@ void read_buf(int f, char *buf, size_t len)
        }
 
        while (1) {
-               char *data;
                size_t siz;
 
                while (!iobuf.raw_input_ends_before)
                        read_a_msg();
 
                siz = MIN(len, iobuf.raw_input_ends_before - iobuf.in.pos);
-               data = perform_io(siz, PIO_INPUT_AND_CONSUME);
-               if (iobuf.in.pos == iobuf.raw_input_ends_before)
-                       iobuf.raw_input_ends_before = 0;
-
-               /* The bytes at the "data" pointer will survive long
-                * enough to make a copy, but not past future I/O. */
-               memcpy(buf, data, siz);
+               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);
@@ -1858,7 +2004,7 @@ void write_buf(int f, const char *buf, size_t len)
                goto batch_copy;
        }
 
-       if (iobuf.out.size - iobuf.out.len < len)
+       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. */
@@ -1873,6 +2019,7 @@ void write_buf(int f, const char *buf, size_t len)
                memcpy(iobuf.out.buf + pos, buf, len);
 
        iobuf.out.len += len;
+       total_data_written += len;
 
   batch_copy:
        if (f == write_batch_monitor_out)
@@ -2026,11 +2173,11 @@ void io_printf(int fd, const char *format, ...)
        va_end(ap);
 
        if (len < 0)
-               exit_cleanup(RERR_STREAMIO);
+               exit_cleanup(RERR_PROTOCOL);
 
        if (len > (int)sizeof buf) {
                rprintf(FERROR, "io_printf() was too long for the buffer.\n");
-               exit_cleanup(RERR_STREAMIO);
+               exit_cleanup(RERR_PROTOCOL);
        }
 
        write_sbuf(fd, buf);
@@ -2044,6 +2191,9 @@ void io_start_multiplex_out(int fd)
        if (msgs2stderr && 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);
 
@@ -2061,8 +2211,10 @@ void io_start_multiplex_in(int fd)
        io_start_buffering_in(fd);
 }
 
-void io_end_multiplex_in(int mode)
+int io_end_multiplex_in(int mode)
 {
+       int ret = iobuf.in_multiplexed ? iobuf.in_fd : -1;
+
        if (msgs2stderr && DEBUG_GTE(IO, 2))
                rprintf(FINFO, "[%s] io_end_multiplex_in(mode=%d)\n", who_am_i(), mode);
 
@@ -2073,11 +2225,14 @@ void io_end_multiplex_in(int mode)
                assert(iobuf.raw_input_ends_before == 0);
        if (mode != MPLX_TO_BUFFERED)
                io_end_buffering_in(mode);
+
+       return ret;
 }
 
-/* Stop output multiplexing. */
-void io_end_multiplex_out(int mode)
+int io_end_multiplex_out(int mode)
 {
+       int ret = iobuf.out_empty_len ? iobuf.out_fd : -1;
+
        if (msgs2stderr && DEBUG_GTE(IO, 2))
                rprintf(FINFO, "[%s] io_end_multiplex_out(mode=%d)\n", who_am_i(), mode);
 
@@ -2088,6 +2243,8 @@ void io_end_multiplex_out(int mode)
 
        iobuf.out.len = 0;
        iobuf.out_empty_len = 0;
+
+       return ret;
 }
 
 void start_write_batch(int fd)