From d820ee9dbfbd12bc030e6576cc8eea6655cbffbb Mon Sep 17 00:00:00 2001
From: Mike Black W9MDB <mdblack98@yahoo.com>
Date: Wed, 24 Nov 2021 13:02:39 -0600
Subject: [PATCH] Add expected_len to read_string function for potential serial
 I/O speedup https://github.com/Hamlib/Hamlib/issues/850

---
 amplifiers/elecraft/kpa.c      |  8 +++---
 rigs/adat/adat.c               |  4 +--
 rigs/alinco/dx77.c             |  6 ++--
 rigs/alinco/dxsr8.c            |  4 +--
 rigs/aor/aor.c                 |  4 +--
 rigs/aor/ar3000.c              |  2 +-
 rigs/aor/ar3030.c              |  2 +-
 rigs/aor/sr2200.c              |  2 +-
 rigs/barrett/barrett.c         |  2 +-
 rigs/dorji/dra818.c            |  4 +--
 rigs/drake/drake.c             |  4 +--
 rigs/dummy/flrig.c             |  2 +-
 rigs/dummy/netampctl.c         |  6 ++--
 rigs/dummy/netrigctl.c         | 50 +++++++++++++++++-----------------
 rigs/dummy/netrotctl.c         | 14 +++++-----
 rigs/dummy/trxmanager.c        |  2 +-
 rigs/elad/elad.c               |  6 ++--
 rigs/icmarine/icmarine.c       |  2 +-
 rigs/icom/frame.c              |  2 +-
 rigs/jrc/jrc.c                 |  4 +--
 rigs/kachina/kachina.c         |  6 ++--
 rigs/kenwood/elecraft.c        |  2 +-
 rigs/kenwood/ic10.c            |  4 +--
 rigs/kenwood/kenwood.c         | 10 +++----
 rigs/kenwood/ts480.c           |  2 +-
 rigs/kenwood/xg3.c             |  8 +++---
 rigs/kit/rs_hfiq.c             |  8 +++---
 rigs/lowe/lowe.c               |  4 +--
 rigs/prm80/prm80.c             | 14 +++++-----
 rigs/racal/ra37xx.c            |  2 +-
 rigs/racal/racal.c             |  2 +-
 rigs/rft/rft.c                 |  2 +-
 rigs/rs/gp2000.c               |  2 +-
 rigs/rs/rs.c                   |  2 +-
 rigs/skanti/skanti.c           |  4 +--
 rigs/tentec/omnivii.c          |  4 +--
 rigs/tentec/orion.c            |  4 +--
 rigs/tentec/rx331.c            |  2 +-
 rigs/tentec/rx340.c            |  2 +-
 rigs/tentec/tentec.c           |  2 +-
 rigs/tentec/tt550.c            |  4 +--
 rigs/uniden/uniden.c           |  4 +--
 rigs/uniden/uniden_digital.c   |  2 +-
 rigs/yaesu/newcat.c            |  8 +++---
 rotators/celestron/celestron.c |  2 +-
 rotators/easycomm/easycomm.c   |  2 +-
 rotators/ether6/ether6.c       |  2 +-
 rotators/gs232a/gs232.c        |  2 +-
 rotators/gs232a/gs232a.c       |  2 +-
 rotators/gs232a/gs232b.c       |  2 +-
 rotators/ioptron/rot_ioptron.c |  2 +-
 rotators/m2/rc2800.c           |  4 +--
 rotators/meade/meade.c         |  2 +-
 rotators/prosistel/prosistel.c |  2 +-
 rotators/radant/radant.c       |  2 +-
 rotators/rotorez/rotorez.c     |  2 +-
 rotators/satel/satel.c         | 16 +++++------
 src/iofunc.c                   |  3 +-
 src/iofunc.h                   |  3 +-
 src/serial.c                   |  2 +-
 tests/ampctl_parse.c           |  2 +-
 tests/rigctl_parse.c           |  2 +-
 tests/rigctlcom.c              |  3 +-
 tests/rotctl_parse.c           |  2 +-
 64 files changed, 148 insertions(+), 145 deletions(-)

diff --git a/amplifiers/elecraft/kpa.c b/amplifiers/elecraft/kpa.c
index 8e0dd32cd..9e1672d7c 100644
--- a/amplifiers/elecraft/kpa.c
+++ b/amplifiers/elecraft/kpa.c
@@ -126,7 +126,7 @@ int kpa_transaction(AMP *amp, const char *cmd, char *response, int response_len)
 
         if (err != RIG_OK) { return err; }
 
-        len = read_string(&rs->ampport, response, response_len, ";", 1, 0);
+        len = read_string(&rs->ampport, response, response_len, ";", 1, 0, 1);
 
         if (len < 0) { return len; }
     }
@@ -140,7 +140,7 @@ int kpa_transaction(AMP *amp, const char *cmd, char *response, int response_len)
     if (response) // if response expected get it
     {
         response[0] = 0;
-        len = read_string(&rs->ampport, response, response_len, ";", 1, 0);
+        len = read_string(&rs->ampport, response, response_len, ";", 1, 0, 1);
 
         if (len < 0)
         {
@@ -166,7 +166,7 @@ int kpa_transaction(AMP *amp, const char *cmd, char *response, int response_len)
 
             if (err != RIG_OK) { return err; }
 
-            len = read_string(&rs->ampport, responsebuf, KPABUFSZ, ";", 1, 0);
+            len = read_string(&rs->ampport, responsebuf, KPABUFSZ, ";", 1, 0, 1);
 
             if (len < 0) { return len; }
         }
@@ -369,7 +369,7 @@ int kpa_get_level(AMP *amp, setting_t level, value_t *val)
         //
         do
         {
-            retval = read_string(&rs->ampport, responsebuf, sizeof(responsebuf), ";", 1, 0);
+            retval = read_string(&rs->ampport, responsebuf, sizeof(responsebuf), ";", 1, 0, 1);
 
             if (retval != RIG_OK) { return retval; }
 
diff --git a/rigs/adat/adat.c b/rigs/adat/adat.c
index 53dbae641..b38c4a846 100644
--- a/rigs/adat/adat.c
+++ b/rigs/adat/adat.c
@@ -1294,7 +1294,7 @@ int adat_receive(RIG  *pRig,
               "*** ADAT: %d %s (%s:%d): ENTRY. Params: pRig = %p\n",
               gFnLevel, __func__, __FILE__, __LINE__, pRig);
 
-    nRC = read_string(&pRigState->rigport, pcData, ADAT_RESPSZ, ADAT_EOL, 1, 0);
+    nRC = read_string(&pRigState->rigport, pcData, ADAT_RESPSZ, ADAT_EOL, 1, 0, 1);
 
     if (nRC > 0)
     {
@@ -3726,7 +3726,7 @@ DECLARE_PROBERIG_BACKEND(adat)
         nRC = write_block(port,
                           ADAT_CMD_DEF_STRING_GET_ID_CODE,
                           strlen(ADAT_CMD_DEF_STRING_GET_ID_CODE));
-        nRead = read_string(port, acBuf, ADAT_RESPSZ, ADAT_EOM, 1, 0);
+        nRead = read_string(port, acBuf, ADAT_RESPSZ, ADAT_EOM, 1, 0, 1);
         close(port->fd);
 
         if ((nRC != RIG_OK || nRead < 0))
diff --git a/rigs/alinco/dx77.c b/rigs/alinco/dx77.c
index 134e6eabc..d6f8234fc 100644
--- a/rigs/alinco/dx77.c
+++ b/rigs/alinco/dx77.c
@@ -321,7 +321,7 @@ int dx77_transaction(RIG *rig,
      * Transceiver sends an echo of cmd followed by a CR/LF
      * TODO: check whether cmd and echobuf match (optional)
      */
-    retval = read_string(&rs->rigport, echobuf, BUFSZ, LF, strlen(LF), 0);
+    retval = read_string(&rs->rigport, echobuf, BUFSZ, LF, strlen(LF), 0, 1);
 
     if (retval < 0)
     {
@@ -337,7 +337,7 @@ int dx77_transaction(RIG *rig,
     /* no data expected, check for OK returned */
     if (data == NULL)
     {
-        retval = read_string(&rs->rigport, echobuf, BUFSZ, LF, strlen(LF), 0);
+        retval = read_string(&rs->rigport, echobuf, BUFSZ, LF, strlen(LF), 0, 1);
 
         if (retval < 0)
         {
@@ -358,7 +358,7 @@ int dx77_transaction(RIG *rig,
         }
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, LF, strlen(LF), 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, LF, strlen(LF), 0, 1);
 
     if (retval < 0)
     {
diff --git a/rigs/alinco/dxsr8.c b/rigs/alinco/dxsr8.c
index 02f33b9d9..030bb7193 100644
--- a/rigs/alinco/dxsr8.c
+++ b/rigs/alinco/dxsr8.c
@@ -264,7 +264,7 @@ int dxsr8_transaction(RIG *rig,
      * Transceiver sends an echo of cmd followed by a CR/LF
      * TODO: check whether cmd and echobuf match (optional)
      */
-    retval = read_string(&rs->rigport, replybuf, BUFSZ, LF, strlen(LF), 0);
+    retval = read_string(&rs->rigport, replybuf, BUFSZ, LF, strlen(LF), 0, 1);
 
     if (retval < 0)
     {
@@ -272,7 +272,7 @@ int dxsr8_transaction(RIG *rig,
     }
 
 
-    retval = read_string(&rs->rigport, replybuf, BUFSZ, LF, strlen(LF), 0);
+    retval = read_string(&rs->rigport, replybuf, BUFSZ, LF, strlen(LF), 0, 1);
 
     if (retval < 0)
     {
diff --git a/rigs/aor/aor.c b/rigs/aor/aor.c
index 799816429..f6a3ca5ba 100644
--- a/rigs/aor/aor.c
+++ b/rigs/aor/aor.c
@@ -102,7 +102,7 @@ static int aor_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
     /*
      * Do wait for a reply
      */
-    retval = read_string(&rs->rigport, data, BUFSZ, EOM, strlen(EOM), 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, EOM, strlen(EOM), 0, 1);
 
     if (retval < 0)
     {
@@ -1428,7 +1428,7 @@ int aor_get_chan_all_cb(RIG *rig, vfo_t vfo, chan_cb_t chan_cb, rig_ptr_t arg)
             /*
              * get next line
              */
-            retval = read_string(&rig->state.rigport, chanbuf, BUFSZ, EOM, strlen(EOM), 0);
+            retval = read_string(&rig->state.rigport, chanbuf, BUFSZ, EOM, strlen(EOM), 0, 1);
 
             if (retval < 0)
             {
diff --git a/rigs/aor/ar3000.c b/rigs/aor/ar3000.c
index f5cb8cf02..4a52d2574 100644
--- a/rigs/aor/ar3000.c
+++ b/rigs/aor/ar3000.c
@@ -211,7 +211,7 @@ static int ar3k_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return RIG_OK;
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, EOM, strlen(EOM), 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, EOM, strlen(EOM), 0, 1);
 
     if (retval == -RIG_ETIMEOUT)
     {
diff --git a/rigs/aor/ar3030.c b/rigs/aor/ar3030.c
index 88a7c7d73..ad03b94cb 100644
--- a/rigs/aor/ar3030.c
+++ b/rigs/aor/ar3030.c
@@ -247,7 +247,7 @@ static int ar3030_transaction(RIG *rig, const char *cmd, int cmd_len,
         if (data)
         {
             /* expecting 0x0d0x0a on all commands so wait for the 0x0a */
-            retval = read_string(&rs->rigport, data, BUFSZ, "\x0a", 1, 0);
+            retval = read_string(&rs->rigport, data, BUFSZ, "\x0a", 1, 0, 1);
 
             if (retval == -RIG_ETIMEOUT)
             {
diff --git a/rigs/aor/sr2200.c b/rigs/aor/sr2200.c
index 72519b689..7cb051837 100644
--- a/rigs/aor/sr2200.c
+++ b/rigs/aor/sr2200.c
@@ -307,7 +307,7 @@ static int sr2200_transaction(RIG *rig, const char *cmd, int cmd_len,
     /*
      * Do wait for a reply
      */
-    retval = read_string(&rs->rigport, data, BUFSZ, EOM, strlen(EOM), 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, EOM, strlen(EOM), 0, 1);
 
     if (retval < 0)
     {
diff --git a/rigs/barrett/barrett.c b/rigs/barrett/barrett.c
index a266f0f8b..572e5f097 100644
--- a/rigs/barrett/barrett.c
+++ b/rigs/barrett/barrett.c
@@ -244,7 +244,7 @@ int barrett_transaction(RIG *rig, char *cmd, int expected, char **result)
     {
         // response format is 0x11,data...,0x0d,0x0a,0x13
         retval = read_string(&rs->rigport, priv->ret_data, sizeof(priv->ret_data),
-                             "\x11", 1, 0);
+                             "\x11", 1, 0, 1);
         rig_debug(RIG_DEBUG_VERBOSE, "%s: resultlen=%d\n", __func__,
                   (int)strlen(priv->ret_data));
 
diff --git a/rigs/dorji/dra818.c b/rigs/dorji/dra818.c
index 79d0ee783..851f325ee 100644
--- a/rigs/dorji/dra818.c
+++ b/rigs/dorji/dra818.c
@@ -60,7 +60,7 @@ struct dra818_priv
 static int dra818_response(RIG *rig, const char *expected)
 {
     char response[80];
-    int r = read_string(&rig->state.rigport, response, sizeof(response), "\n", 1, 0);
+    int r = read_string(&rig->state.rigport, response, sizeof(response), "\n", 1, 0, 1);
 
     if (r != strlen(expected))
     {
@@ -294,7 +294,7 @@ int dra818_get_dcd(RIG *rig, vfo_t vfo, dcd_t *dcd)
             (int)(priv->rx_freq / 1000000), (int)((priv->rx_freq % 1000000) / 100));
     write_block(&rig->state.rigport, cmd, strlen(cmd));
 
-    r = read_string(&rig->state.rigport, response, sizeof(response), "\n", 1, 0);
+    r = read_string(&rig->state.rigport, response, sizeof(response), "\n", 1, 0, 1);
 
     if (r != 5)
     {
diff --git a/rigs/drake/drake.c b/rigs/drake/drake.c
index 3cc2b0f0b..fad3265de 100644
--- a/rigs/drake/drake.c
+++ b/rigs/drake/drake.c
@@ -84,7 +84,7 @@ int drake_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return 0;
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, LF, 1, 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, LF, 1, 0, 1);
 
     if (retval == -RIG_ETIMEOUT)
     {
@@ -1252,7 +1252,7 @@ DECLARE_PROBERIG_BACKEND(drake)
     }
 
     retval = write_block(port, "ID" EOM, 3);
-    id_len = read_string(port, idbuf, BUFSZ, LF, 1, 0);
+    id_len = read_string(port, idbuf, BUFSZ, LF, 1, 0, 1);
 
     close(port->fd);
 
diff --git a/rigs/dummy/flrig.c b/rigs/dummy/flrig.c
index 534b41951..2a1563140 100644
--- a/rigs/dummy/flrig.c
+++ b/rigs/dummy/flrig.c
@@ -456,7 +456,7 @@ static int read_transaction(RIG *rig, char *xml, int xml_len)
         }
 
         int len = read_string(&rs->rigport, tmp_buf, sizeof(tmp_buf), delims,
-                              strlen(delims), 0);
+                              strlen(delims), 0, 1);
         rig_debug(RIG_DEBUG_TRACE, "%s: string='%s'\n", __func__, tmp_buf);
 
         // if our first response we should see the HTTP header
diff --git a/rigs/dummy/netampctl.c b/rigs/dummy/netampctl.c
index 5334b9543..91a872897 100644
--- a/rigs/dummy/netampctl.c
+++ b/rigs/dummy/netampctl.c
@@ -52,7 +52,7 @@ static int netampctl_transaction(AMP *amp, char *cmd, int len, char *buf)
         return ret;
     }
 
-    ret = read_string(&amp->state.ampport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+    ret = read_string(&amp->state.ampport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
 
     if (ret < 0)
     {
@@ -95,7 +95,7 @@ static int netampctl_open(AMP *amp)
         return -RIG_EPROTO;
     }
 
-    ret = read_string(&amp->state.ampport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+    ret = read_string(&amp->state.ampport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
 
     if (ret <= 0)
     {
@@ -104,7 +104,7 @@ static int netampctl_open(AMP *amp)
 
     do
     {
-        ret = read_string(&amp->state.ampport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+        ret = read_string(&amp->state.ampport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
 
         if (ret > 0)
         {
diff --git a/rigs/dummy/netrigctl.c b/rigs/dummy/netrigctl.c
index 8502f4311..7108b821f 100644
--- a/rigs/dummy/netrigctl.c
+++ b/rigs/dummy/netrigctl.c
@@ -79,7 +79,7 @@ static int netrigctl_transaction(RIG *rig, char *cmd, int len, char *buf)
         return ret;
     }
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret < 0)
     {
@@ -312,14 +312,14 @@ static int netrigctl_open(RIG *rig)
         return -RIG_EPROTO;
     }
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
         return (ret < 0) ? ret : -RIG_EPROTO;
     }
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -330,7 +330,7 @@ static int netrigctl_open(RIG *rig)
 
     for (i = 0; i < HAMLIB_FRQRANGESIZ; i++)
     {
-        ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+        ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
         if (ret <= 0)
         {
@@ -360,7 +360,7 @@ static int netrigctl_open(RIG *rig)
 
     for (i = 0; i < HAMLIB_FRQRANGESIZ; i++)
     {
-        ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+        ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
         if (ret <= 0)
         {
@@ -402,7 +402,7 @@ static int netrigctl_open(RIG *rig)
 
     for (i = 0; i < HAMLIB_TSLSTSIZ; i++)
     {
-        ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+        ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
         if (ret <= 0)
         {
@@ -426,7 +426,7 @@ static int netrigctl_open(RIG *rig)
 
     for (i = 0; i < HAMLIB_FLTLSTSIZ; i++)
     {
-        ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+        ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
         if (ret <= 0)
         {
@@ -453,7 +453,7 @@ static int netrigctl_open(RIG *rig)
     chan_t chan_list[HAMLIB_CHANLSTSIZ]; /*!< Channel list, zero ended */
 #endif
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -462,7 +462,7 @@ static int netrigctl_open(RIG *rig)
 
     rig->caps->max_rit = rs->max_rit = atol(buf);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -471,7 +471,7 @@ static int netrigctl_open(RIG *rig)
 
     rig->caps->max_xit = rs->max_xit = atol(buf);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -480,7 +480,7 @@ static int netrigctl_open(RIG *rig)
 
     rig->caps->max_ifshift = rs->max_ifshift = atol(buf);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -489,7 +489,7 @@ static int netrigctl_open(RIG *rig)
 
     rs->announces = atoi(buf);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -516,7 +516,7 @@ static int netrigctl_open(RIG *rig)
 
     rig->caps->preamp[ret] = rs->preamp[ret] = RIG_DBLST_END;
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -543,7 +543,7 @@ static int netrigctl_open(RIG *rig)
 
     rig->caps->attenuator[ret] = rs->attenuator[ret] = RIG_DBLST_END;
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -552,7 +552,7 @@ static int netrigctl_open(RIG *rig)
 
     rig->caps->has_get_func = rs->has_get_func = strtoll(buf, NULL, 0);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -561,7 +561,7 @@ static int netrigctl_open(RIG *rig)
 
     rig->caps->has_set_func = rs->has_set_func = strtoll(buf, NULL, 0);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -583,7 +583,7 @@ static int netrigctl_open(RIG *rig)
 
 #endif
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -592,7 +592,7 @@ static int netrigctl_open(RIG *rig)
 
     rig->caps->has_set_level = rs->has_set_level = strtoll(buf, NULL, 0);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -601,7 +601,7 @@ static int netrigctl_open(RIG *rig)
 
     rs->has_get_parm = strtoll(buf, NULL, 0);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -641,7 +641,7 @@ static int netrigctl_open(RIG *rig)
     do
     {
         char setting[32], value[1024];
-        ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+        ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
         strtok(buf, "\r\n"); // chop the EOL
 
         if (ret <= 0)
@@ -892,7 +892,7 @@ static int netrigctl_get_freq(RIG *rig, vfo_t vfo, freq_t *freq)
     CHKSCN1ARG(num_sscanf(buf, "%"SCNfreq, freq));
 
 #if 0 // implement set_freq VFO later if it can be detected
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -963,7 +963,7 @@ static int netrigctl_get_mode(RIG *rig, vfo_t vfo, rmode_t *mode,
 
     *mode = rig_parse_mode(buf);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -1576,7 +1576,7 @@ static int netrigctl_get_split_mode(RIG *rig, vfo_t vfo, rmode_t *tx_mode,
 
     *tx_mode = rig_parse_mode(buf);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -1642,7 +1642,7 @@ static int netrigctl_get_split_vfo(RIG *rig, vfo_t vfo, split_t *split,
 
     *split = atoi(buf);
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
@@ -2164,7 +2164,7 @@ static int netrigctl_get_ant(RIG *rig, vfo_t vfo, ant_t ant, value_t *option,
                   ret);
     }
 
-    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0);
+    ret = read_string(&rig->state.rigport, buf, BUF_MAX, "\n", 1, 0, 1);
 
     if (ret <= 0)
     {
diff --git a/rigs/dummy/netrotctl.c b/rigs/dummy/netrotctl.c
index deecdfe27..45883b421 100644
--- a/rigs/dummy/netrotctl.c
+++ b/rigs/dummy/netrotctl.c
@@ -57,7 +57,7 @@ static int netrotctl_transaction(ROT *rot, char *cmd, int len, char *buf)
         return ret;
     }
 
-    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
 
     if (ret < 0)
     {
@@ -100,14 +100,14 @@ static int netrotctl_open(ROT *rot)
         return -RIG_EPROTO;
     }
 
-    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
 
     if (ret <= 0)
     {
         return (ret < 0) ? ret : -RIG_EPROTO;
     }
 
-    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
 
     if (ret <= 0)
     {
@@ -116,7 +116,7 @@ static int netrotctl_open(ROT *rot)
 
     rs->min_az = atof(buf);
 
-    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
 
     if (ret <= 0)
     {
@@ -125,7 +125,7 @@ static int netrotctl_open(ROT *rot)
 
     rs->max_az = atof(buf);
 
-    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
 
     if (ret <= 0)
     {
@@ -134,7 +134,7 @@ static int netrotctl_open(ROT *rot)
 
     rs->min_el = atof(buf);
 
-    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
 
     if (ret <= 0)
     {
@@ -198,7 +198,7 @@ static int netrotctl_get_position(ROT *rot, azimuth_t *az, elevation_t *el)
 
     *az = atof(buf);
 
-    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
 
     if (ret <= 0)
     {
diff --git a/rigs/dummy/trxmanager.c b/rigs/dummy/trxmanager.c
index 5d5192d32..2476870ff 100644
--- a/rigs/dummy/trxmanager.c
+++ b/rigs/dummy/trxmanager.c
@@ -243,7 +243,7 @@ static int read_transaction(RIG *rig, char *response, int response_len)
     rig_debug(RIG_DEBUG_TRACE, "%s\n", __func__);
 
     len = read_string(&rs->rigport, response, response_len, delims,
-                      strlen(delims), 0);
+                      strlen(delims), 0, 1);
 
     if (len <= 0)
     {
diff --git a/rigs/elad/elad.c b/rigs/elad/elad.c
index 346c96909..aba415af5 100644
--- a/rigs/elad/elad.c
+++ b/rigs/elad/elad.c
@@ -253,7 +253,7 @@ transaction_read:
     /* allow one extra byte for terminator we don't return */
     len = min(datasize ? datasize + 1 : strlen(priv->verify_cmd) + 13,
               ELAD_MAX_BUF_LEN);
-    retval = read_string(&rs->rigport, buffer, len, cmdtrm, strlen(cmdtrm), 0);
+    retval = read_string(&rs->rigport, buffer, len, cmdtrm, strlen(cmdtrm), 0, 1);
 
     if (retval < 0)
     {
@@ -3739,7 +3739,7 @@ DECLARE_PROBERIG_BACKEND(elad)
         }
 
         retval = write_block(port, "ID;", 3);
-        id_len = read_string(port, idbuf, IDBUFSZ, ";\r", 2, 0);
+        id_len = read_string(port, idbuf, IDBUFSZ, ";\r", 2, 0, 1);
         close(port->fd);
 
         if (retval != RIG_OK || id_len < 0)
@@ -3800,7 +3800,7 @@ DECLARE_PROBERIG_BACKEND(elad)
         }
 
         retval = write_block(port, "K2;", 3);
-        id_len = read_string(port, idbuf, IDBUFSZ, ";\r", 2, 0);
+        id_len = read_string(port, idbuf, IDBUFSZ, ";\r", 2, 0, 1);
         close(port->fd);
 
         if (retval != RIG_OK)
diff --git a/rigs/icmarine/icmarine.c b/rigs/icmarine/icmarine.c
index 5fc194f47..5e99e681f 100644
--- a/rigs/icmarine/icmarine.c
+++ b/rigs/icmarine/icmarine.c
@@ -288,7 +288,7 @@ int icmarine_transaction(RIG *rig, const char *cmd, const char *param,
     /*
      * Transceiver sends an echo of cmd followed by a CR/LF
      */
-    retval = read_string(&rs->rigport, respbuf, BUFSZ, LF, strlen(LF), 0);
+    retval = read_string(&rs->rigport, respbuf, BUFSZ, LF, strlen(LF), 0, 1);
 
     if (retval < 0)
     {
diff --git a/rigs/icom/frame.c b/rigs/icom/frame.c
index 964277a13..a57f8fd76 100644
--- a/rigs/icom/frame.c
+++ b/rigs/icom/frame.c
@@ -490,7 +490,7 @@ int read_icom_frame(hamlib_port_t *p, unsigned char rxbuffer[],
     do
     {
         int i = read_string(p, rx_ptr, MAXFRAMELEN - read,
-                            icom_block_end, icom_block_end_length, 0);
+                            icom_block_end, icom_block_end_length, 0, 1);
 
         if (i < 0 && i != RIG_BUSBUSY) /* die on errors */
         {
diff --git a/rigs/jrc/jrc.c b/rigs/jrc/jrc.c
index 61e429f71..a02aa9c56 100644
--- a/rigs/jrc/jrc.c
+++ b/rigs/jrc/jrc.c
@@ -93,7 +93,7 @@ static int jrc_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return 0;
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, EOM, strlen(EOM), 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, EOM, strlen(EOM), 0, 1);
 
     Unhold_Decode(rig);
 
@@ -1632,7 +1632,7 @@ int jrc_decode_event(RIG *rig)
     //#define SETUP_STATUS_LEN 17
 
     //count = read_string(&rs->rigport, buf, SETUP_STATUS_LEN, "", 0);
-    count = read_string(&rs->rigport, buf, priv->info_len, "", 0, 0);
+    count = read_string(&rs->rigport, buf, priv->info_len, "", 0, 0, 1);
 
     if (count < 0)
     {
diff --git a/rigs/kachina/kachina.c b/rigs/kachina/kachina.c
index df1aecba0..138c26006 100644
--- a/rigs/kachina/kachina.c
+++ b/rigs/kachina/kachina.c
@@ -93,7 +93,7 @@ static int kachina_transaction(RIG *rig, unsigned char cmd1, unsigned char cmd2)
         return retval;
     }
 
-    count = read_string(&rs->rigport, (char *) buf4, 1, "", 0, 0);
+    count = read_string(&rs->rigport, (char *) buf4, 1, "", 0, 0, 1);
 
     if (count != 1)
     {
@@ -128,7 +128,7 @@ static int kachina_trans_n(RIG *rig, unsigned char cmd1, const char *data,
         return retval;
     }
 
-    count = read_string(&rs->rigport, (char *) buf, 1, "", 0, 0);
+    count = read_string(&rs->rigport, (char *) buf, 1, "", 0, 0, 1);
 
     if (count != 1)
     {
@@ -273,7 +273,7 @@ int kachina_get_level(RIG *rig, vfo_t vfo, setting_t level, value_t *val)
     rig_flush(&rig->state.rigport);
 
     count = read_string(&rig->state.rigport, (char *) buf, 31, rcv_signal_range,
-                        128, 0);
+                        128, 0, 1);
 
     if (count < 1)
     {
diff --git a/rigs/kenwood/elecraft.c b/rigs/kenwood/elecraft.c
index ad2a6e06c..016b4dec2 100644
--- a/rigs/kenwood/elecraft.c
+++ b/rigs/kenwood/elecraft.c
@@ -135,7 +135,7 @@ int elecraft_open(RIG *rig)
             return err;
         }
 
-        err = read_string(&rs->rigport, buf, sizeof(buf), ";", 1, 0);
+        err = read_string(&rs->rigport, buf, sizeof(buf), ";", 1, 0, 1);
 
         if (err < 0)
         {
diff --git a/rigs/kenwood/ic10.c b/rigs/kenwood/ic10.c
index c393e3f6a..7053249ae 100644
--- a/rigs/kenwood/ic10.c
+++ b/rigs/kenwood/ic10.c
@@ -110,7 +110,7 @@ transaction:
         }
 
         // this should be the ID response
-        retval = read_string(&rs->rigport, buffer, sizeof(buffer), ";", 1, 0);
+        retval = read_string(&rs->rigport, buffer, sizeof(buffer), ";", 1, 0, 1);
 
         // might be ?; too
         if (buffer[0] == '?' && retry_cmd++ < rs->rigport.retry)
@@ -129,7 +129,7 @@ transaction:
         return RIG_OK;
     }
 
-    retval = read_string(&rs->rigport, data, 50, ";", 1, 0);
+    retval = read_string(&rs->rigport, data, 50, ";", 1, 0, 1);
 
     if (retval == -RIG_ETIMEOUT)
     {
diff --git a/rigs/kenwood/kenwood.c b/rigs/kenwood/kenwood.c
index cd544b446..1000bffc8 100644
--- a/rigs/kenwood/kenwood.c
+++ b/rigs/kenwood/kenwood.c
@@ -369,7 +369,7 @@ transaction_read:
     /* allow room for most any response */
     len = min(datasize ? datasize + 1 : strlen(priv->verify_cmd) + 48,
               KENWOOD_MAX_BUF_LEN);
-    retval = read_string(&rs->rigport, buffer, len, cmdtrm_str, strlen(cmdtrm_str), 0);
+    retval = read_string(&rs->rigport, buffer, len, cmdtrm_str, strlen(cmdtrm_str), 0, 1);
     rig_debug(RIG_DEBUG_TRACE, "%s: read_string(len=%d)='%s'\n", __func__,
               (int)strlen(buffer), buffer);
 
@@ -2601,7 +2601,7 @@ static int kenwood_get_micgain_minmax(RIG *rig, int *micgain_now,
 
     if (retval != RIG_OK) { RETURNFUNC(retval); }
 
-    retval = read_string(&rs->rigport, levelbuf, sizeof(levelbuf), NULL, 0, 0);
+    retval = read_string(&rs->rigport, levelbuf, sizeof(levelbuf), NULL, 0, 0, 1);
 
     rig_debug(RIG_DEBUG_TRACE, "%s: retval=%d\n", __func__, retval);
 
@@ -2700,7 +2700,7 @@ static int kenwood_get_power_minmax(RIG *rig, int *power_now, int *power_min,
 
     if (retval != RIG_OK) { RETURNFUNC(retval); }
 
-    retval = read_string(&rs->rigport, levelbuf, sizeof(levelbuf), NULL, 0, 0);
+    retval = read_string(&rs->rigport, levelbuf, sizeof(levelbuf), NULL, 0, 0, 1);
 
     rig_debug(RIG_DEBUG_TRACE, "%s: retval=%d\n", __func__, retval);
 
@@ -5367,7 +5367,7 @@ DECLARE_PROBERIG_BACKEND(kenwood)
         }
 
         retval = write_block(port, "ID;", 3);
-        id_len = read_string(port, idbuf, IDBUFSZ, ";\r", 2, 0);
+        id_len = read_string(port, idbuf, IDBUFSZ, ";\r", 2, 0, 1);
         close(port->fd);
 
         if (retval != RIG_OK || id_len < 0)
@@ -5434,7 +5434,7 @@ DECLARE_PROBERIG_BACKEND(kenwood)
         }
 
         retval = write_block(port, "K2;", 3);
-        id_len = read_string(port, idbuf, IDBUFSZ, ";\r", 2, 0);
+        id_len = read_string(port, idbuf, IDBUFSZ, ";\r", 2, 0, 1);
         close(port->fd);
 
         if (retval != RIG_OK)
diff --git a/rigs/kenwood/ts480.c b/rigs/kenwood/ts480.c
index 190b72f03..029123ce7 100644
--- a/rigs/kenwood/ts480.c
+++ b/rigs/kenwood/ts480.c
@@ -442,7 +442,7 @@ static int ts480_read_meters(RIG *rig, int *swr, int *comp, int *alc)
 
     // TS-480 returns values for all meters at the same time, for example: RM10000;RM20000;RM30000;
 
-    retval = read_string(&rs->rigport, ackbuf, expected_len + 1, NULL, 0, 0);
+    retval = read_string(&rs->rigport, ackbuf, expected_len + 1, NULL, 0, 0, 1);
 
     rig_debug(RIG_DEBUG_TRACE, "%s: read_string retval=%d\n", __func__, retval);
 
diff --git a/rigs/kenwood/xg3.c b/rigs/kenwood/xg3.c
index 54b136344..1251378c0 100644
--- a/rigs/kenwood/xg3.c
+++ b/rigs/kenwood/xg3.c
@@ -285,7 +285,7 @@ int xg3_get_level(RIG *rig, vfo_t vfo, setting_t level, value_t *val)
             return retval;
         }
 
-        retval = read_string(&rs->rigport, replybuf, replysize, ";", 1, 0);
+        retval = read_string(&rs->rigport, replybuf, replysize, ";", 1, 0, 1);
 
         if (retval < 0)
         {
@@ -462,7 +462,7 @@ int xg3_get_freq(RIG *rig, vfo_t vfo, freq_t *freq)
         return retval;
     }
 
-    retval = read_string(&rs->rigport, freqbuf, freqsize, ";", 1, 0);
+    retval = read_string(&rs->rigport, freqbuf, freqsize, ";", 1, 0, 1);
 
     if (retval < 0)
     {
@@ -514,7 +514,7 @@ int xg3_get_powerstat(RIG *rig, powerstat_t *status)
     if (retval == RIG_OK)
     {
         char reply[32];
-        retval = read_string(&rs->rigport, reply, sizeof(reply), ";", 1, 0);
+        retval = read_string(&rs->rigport, reply, sizeof(reply), ";", 1, 0, 1);
         *status = RIG_POWER_ON;
         priv->powerstat = RIG_POWER_ON;
     }
@@ -578,7 +578,7 @@ int xg3_get_mem(RIG *rig, vfo_t vfo, int *ch)
         return retval;
     }
 
-    retval = read_string(&rs->rigport, reply, sizeof(reply), ";", 1, 0);
+    retval = read_string(&rs->rigport, reply, sizeof(reply), ";", 1, 0, 1);
 
     if (retval < 0)
     {
diff --git a/rigs/kit/rs_hfiq.c b/rigs/kit/rs_hfiq.c
index 92b1b59d5..3618cd0a4 100644
--- a/rigs/kit/rs_hfiq.c
+++ b/rigs/kit/rs_hfiq.c
@@ -102,7 +102,7 @@ static int rshfiq_open(RIG *rig)
             return retval;
         }
 
-        retval = read_string(&rig->state.rigport, versionstr, 20, stopset, 2, 0);
+        retval = read_string(&rig->state.rigport, versionstr, 20, stopset, 2, 0, 1);
     }
 
     if (retval <= 0)
@@ -191,7 +191,7 @@ static int rshfiq_get_freq(RIG *rig, vfo_t vfo, freq_t *freq)
         return retval;
     }
 
-    retval = read_string(&rig->state.rigport, cmdstr, 9, stopset, 2, 0);
+    retval = read_string(&rig->state.rigport, cmdstr, 9, stopset, 2, 0, 1);
 
     if (retval <= 0)
     {
@@ -276,7 +276,7 @@ static int rshfiq_get_level(RIG *rig, vfo_t vfo, setting_t level, value_t *val)
         stopset[0] = '\r';
         stopset[1] = '\n';
 
-        retval = read_string(&rig->state.rigport, cmdstr, 9, stopset, 2, 0);
+        retval = read_string(&rig->state.rigport, cmdstr, 9, stopset, 2, 0, 1);
 
         rig_debug(RIG_DEBUG_TRACE, "RIG_LEVEL_RFPOWER_METER reply=%s\n", cmdstr);
 
@@ -314,7 +314,7 @@ static int rshfiq_get_level(RIG *rig, vfo_t vfo, setting_t level, value_t *val)
         stopset[0] = '\r';
         stopset[1] = '\n';
 
-        retval = read_string(&rig->state.rigport, cmdstr, 9, stopset, 2, 0);
+        retval = read_string(&rig->state.rigport, cmdstr, 9, stopset, 2, 0, 1);
 
         rig_debug(RIG_DEBUG_TRACE, "RIG_LEVEL_TEMP_METER reply=%s\n", cmdstr);
 
diff --git a/rigs/lowe/lowe.c b/rigs/lowe/lowe.c
index ad561b1ab..a9d14478e 100644
--- a/rigs/lowe/lowe.c
+++ b/rigs/lowe/lowe.c
@@ -79,7 +79,7 @@ int lowe_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return 0;
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, CR, 1, 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, CR, 1, 0, 1);
 
     if (retval == -RIG_ETIMEOUT)
     {
@@ -342,7 +342,7 @@ DECLARE_PROBERIG_BACKEND(lowe)
     }
 
     retval = write_block(port, "TYP?" EOM, 4);
-    id_len = read_string(port, idbuf, BUFSZ, CR, 2, 0);
+    id_len = read_string(port, idbuf, BUFSZ, CR, 2, 0, 1);
 
     close(port->fd);
 
diff --git a/rigs/prm80/prm80.c b/rigs/prm80/prm80.c
index 6da02693e..5ba68be6d 100644
--- a/rigs/prm80/prm80.c
+++ b/rigs/prm80/prm80.c
@@ -170,7 +170,7 @@ static int read_prompt_and_send(hamlib_port_t *rigport,
 
     buflen = (data_len == NULL) ? sizeof(buf) : *data_len;
 
-    retval = read_string(rigport, data, buflen, delimiter, 1, 0);
+    retval = read_string(rigport, data, buflen, delimiter, 1, 0, 1);
 
     if (retval < 0)
     {
@@ -230,7 +230,7 @@ static int prm80_wait_for_prompt(hamlib_port_t *rigport)
     int retval;
 
     // Read up to the '>' prompt and discard content.
-    retval = read_string(rigport, buf, sizeof(buf), ">", 1, 0);
+    retval = read_string(rigport, buf, sizeof(buf), ">", 1, 0, 1);
 
     if (retval < 0)
     {
@@ -910,7 +910,7 @@ int prm80_set_channel(RIG *rig, vfo_t vfo, const channel_t *chan)
         if (ret == 3 && buf[2] == 'T')
         {
             // Read the question
-            ret = read_string(&rs->rigport, buf, sizeof(buf), "?", 1, 0);
+            ret = read_string(&rs->rigport, buf, sizeof(buf), "?", 1, 0, 1);
 
             if (ret < 0)
             {
@@ -1126,7 +1126,7 @@ static int prm80_get_rawstr_RAM(RIG *rig, value_t *val)
     }
 
     // Read CRLF
-    ret = read_string(&rs->rigport, buf, BUFSZ, "\n", 1, 0);
+    ret = read_string(&rs->rigport, buf, BUFSZ, "\n", 1, 0, 1);
 
     if (ret < 0)
     {
@@ -1142,7 +1142,7 @@ static int prm80_get_rawstr_RAM(RIG *rig, value_t *val)
 
     for (i = 0; i < (RSSI_HOLD_ADDR / 16) + 1; i++)
     {
-        ret = read_string(&rs->rigport, buf, BUFSZ, "\n", 1, 0);
+        ret = read_string(&rs->rigport, buf, BUFSZ, "\n", 1, 0, 1);
 
         if (ret < 0)
         {
@@ -1158,7 +1158,7 @@ static int prm80_get_rawstr_RAM(RIG *rig, value_t *val)
     // discard the remaining content of RAM print
     for (i = 0; i < (16 - RSSI_HOLD_ADDR / 16) - 1; i++)
     {
-        read_string(&rs->rigport, buf, BUFSZ, "\n", 1, 0);
+        read_string(&rs->rigport, buf, BUFSZ, "\n", 1, 0, 1);
     }
 
     prm80_wait_for_prompt(&rs->rigport);
@@ -1281,7 +1281,7 @@ const char *prm80_get_info(RIG *rig)
         return NULL;
     }
 
-    ret = read_string(&rs->rigport, s_buf, BUFSZ, ">", 1, 0);
+    ret = read_string(&rs->rigport, s_buf, BUFSZ, ">", 1, 0, 1);
 
     if (ret < 0)
     {
diff --git a/rigs/racal/ra37xx.c b/rigs/racal/ra37xx.c
index bee3c6e66..353ba2d5a 100644
--- a/rigs/racal/ra37xx.c
+++ b/rigs/racal/ra37xx.c
@@ -122,7 +122,7 @@ static int ra37xx_one_transaction(RIG *rig, const char *cmd, char *data,
 
     do
     {
-        retval = read_string(&rs->rigport, respbuf, BUFSZ, EOM, strlen(EOM), 0);
+        retval = read_string(&rs->rigport, respbuf, BUFSZ, EOM, strlen(EOM), 0, 1);
 
         if (retval < 0)
         {
diff --git a/rigs/racal/racal.c b/rigs/racal/racal.c
index dc6dad86b..cc3b5050b 100644
--- a/rigs/racal/racal.c
+++ b/rigs/racal/racal.c
@@ -100,7 +100,7 @@ static int racal_transaction(RIG *rig, const char *cmd, char *data,
         return retval;
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, EOM, strlen(EOM), 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, EOM, strlen(EOM), 0, 1);
 
     if (retval <= 0)
     {
diff --git a/rigs/rft/rft.c b/rigs/rft/rft.c
index 7b544b8fb..d5960f7e6 100644
--- a/rigs/rft/rft.c
+++ b/rigs/rft/rft.c
@@ -71,7 +71,7 @@ int rft_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return 0;
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, CR, 1, 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, CR, 1, 0, 1);
 
     if (retval == -RIG_ETIMEOUT)
     {
diff --git a/rigs/rs/gp2000.c b/rigs/rs/gp2000.c
index 6455fa0a9..d0c80c52e 100644
--- a/rigs/rs/gp2000.c
+++ b/rigs/rs/gp2000.c
@@ -89,7 +89,7 @@ gp2000_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return RIG_OK;
     }
 
-    retval = read_string(&rs->rigport, data, RESPSZ, CR, 1, 0);
+    retval = read_string(&rs->rigport, data, RESPSZ, CR, 1, 0, 1);
 
     if (retval < 0)
     {
diff --git a/rigs/rs/rs.c b/rigs/rs/rs.c
index bde748edb..b60056eb1 100644
--- a/rigs/rs/rs.c
+++ b/rigs/rs/rs.c
@@ -80,7 +80,7 @@ int rs_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return RIG_OK;
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, CR, 1, 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, CR, 1, 0, 1);
 
     if (retval < 0)
     {
diff --git a/rigs/skanti/skanti.c b/rigs/skanti/skanti.c
index 8ad178985..347900aef 100644
--- a/rigs/skanti/skanti.c
+++ b/rigs/skanti/skanti.c
@@ -88,7 +88,7 @@ static int skanti_transaction(RIG *rig, const char *cmd, int cmd_len,
         * Transceiver sends back ">"
         */
         char retbuf[BUFSZ + 1];
-        retval = read_string(&rs->rigport, retbuf, BUFSZ, PROMPT, strlen(PROMPT), 0);
+        retval = read_string(&rs->rigport, retbuf, BUFSZ, PROMPT, strlen(PROMPT), 0, 1);
 
         if (retval < 0)
         {
@@ -107,7 +107,7 @@ static int skanti_transaction(RIG *rig, const char *cmd, int cmd_len,
         }
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, LF, strlen(LF), 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, LF, strlen(LF), 0, 1);
 
     if (retval == -RIG_ETIMEOUT)
     {
diff --git a/rigs/tentec/omnivii.c b/rigs/tentec/omnivii.c
index 34192a637..3f5ff8d3e 100644
--- a/rigs/tentec/omnivii.c
+++ b/rigs/tentec/omnivii.c
@@ -288,7 +288,7 @@ static int tt588_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
 
             if (data)
             {
-                retval = read_string(&rs->rigport, data, (*data_len) + 1, term, strlen(term), 0);
+                retval = read_string(&rs->rigport, data, (*data_len) + 1, term, strlen(term), 0, 1);
 
                 if (retval != -RIG_ETIMEOUT)
                 {
@@ -310,7 +310,7 @@ static int tt588_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         write_block(&rs->rigport, "XX" EOM,
                     3); // we wont' worry about the response here
         retval = read_string(&rs->rigport, xxbuf, sizeof(xxbuf), "",
-                             0, 0); // this should timeout
+                             0, 0, 1); // this should timeout
 
         if (retval != RIG_OK)
         {
diff --git a/rigs/tentec/orion.c b/rigs/tentec/orion.c
index 823477bc4..b1aebe475 100644
--- a/rigs/tentec/orion.c
+++ b/rigs/tentec/orion.c
@@ -156,7 +156,7 @@ static int tt565_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
 #endif
         *data_len = data_len_init;  /* restore orig. buffer length */
         *data_len = read_string(&rs->rigport, data, *data_len,
-                                EOM, strlen(EOM), 0);
+                                EOM, strlen(EOM), 0, 1);
 
         if (!strncmp(data, "Z!", 2))     // command unrecognized??
         {
@@ -197,7 +197,7 @@ static int tt565_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
                           passcount, itry);
                 *data_len = data_len_init;  /* restore orig. buffer length */
                 read_string(&rs->rigport, data, *data_len,
-                            EOM, strlen(EOM), 0);      // purge the input stream...
+                            EOM, strlen(EOM), 0, 1);      // purge the input stream...
                 continue;                   // now go retry the full command
             }
         }
diff --git a/rigs/tentec/rx331.c b/rigs/tentec/rx331.c
index f9737100b..9e6e84b8d 100644
--- a/rigs/tentec/rx331.c
+++ b/rigs/tentec/rx331.c
@@ -269,7 +269,7 @@ static int rx331_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return RIG_OK;
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, EOM, 1, 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, EOM, 1, 0, 1);
 
     if (retval < 0)
     {
diff --git a/rigs/tentec/rx340.c b/rigs/tentec/rx340.c
index 8a8245a41..1edcf642a 100644
--- a/rigs/tentec/rx340.c
+++ b/rigs/tentec/rx340.c
@@ -219,7 +219,7 @@ static int rx340_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return RIG_OK;
     }
 
-    retval = read_string(&rs->rigport, data, BUFSZ, EOM, 1, 0);
+    retval = read_string(&rs->rigport, data, BUFSZ, EOM, 1, 0, 1);
 
     if (retval < 0)
     {
diff --git a/rigs/tentec/tentec.c b/rigs/tentec/tentec.c
index 2c022a952..00a4ee9f3 100644
--- a/rigs/tentec/tentec.c
+++ b/rigs/tentec/tentec.c
@@ -85,7 +85,7 @@ int tentec_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return 0;
     }
 
-    retval = read_string(&rs->rigport, data, *data_len, NULL, 0, 0);
+    retval = read_string(&rs->rigport, data, *data_len, NULL, 0, 0, 1);
 
     if (retval == -RIG_ETIMEOUT)
     {
diff --git a/rigs/tentec/tt550.c b/rigs/tentec/tt550.c
index 6fdea17ff..a7718da5f 100644
--- a/rigs/tentec/tt550.c
+++ b/rigs/tentec/tt550.c
@@ -103,7 +103,7 @@ tt550_transaction(RIG *rig, const char *cmd, int cmd_len, char *data,
         return 0;
     }
 
-    retval = read_string(&rs->rigport, data, *data_len, NULL, 0, 0);
+    retval = read_string(&rs->rigport, data, *data_len, NULL, 0, 0, 1);
 
     if (retval == -RIG_ETIMEOUT)
     {
@@ -1699,7 +1699,7 @@ tt550_decode_event(RIG *rig)
     priv = (struct tt550_priv_data *) rs->priv;
 
 
-    data_len = read_string(&rs->rigport, (char *) buf, MAXFRAMELEN, "\n\r", 2, 0);
+    data_len = read_string(&rs->rigport, (char *) buf, MAXFRAMELEN, "\n\r", 2, 0, 1);
 
 
     if (data_len == -RIG_ETIMEOUT)
diff --git a/rigs/uniden/uniden.c b/rigs/uniden/uniden.c
index c0399802d..16e0db003 100644
--- a/rigs/uniden/uniden.c
+++ b/rigs/uniden/uniden.c
@@ -156,7 +156,7 @@ transaction_write:
     }
 
     memset(data, 0, *datasize);
-    retval = read_string(&rs->rigport, data, *datasize, EOM, strlen(EOM), 0);
+    retval = read_string(&rs->rigport, data, *datasize, EOM, strlen(EOM), 0, 1);
 
     if (retval < 0)
     {
@@ -838,7 +838,7 @@ DECLARE_PROBERIG_BACKEND(uniden)
         }
 
         retval = write_block(port, "SI"EOM, 3);
-        id_len = read_string(port, idbuf, IDBUFSZ, EOM, 1, 0);
+        id_len = read_string(port, idbuf, IDBUFSZ, EOM, 1, 0, 1);
         close(port->fd);
 
         if (retval != RIG_OK || id_len < 0)
diff --git a/rigs/uniden/uniden_digital.c b/rigs/uniden/uniden_digital.c
index 8e2fe3761..1e91fa6f1 100644
--- a/rigs/uniden/uniden_digital.c
+++ b/rigs/uniden/uniden_digital.c
@@ -138,7 +138,7 @@ transaction_write:
     }
 
     memset(data, 0, *datasize);
-    retval = read_string(&rs->rigport, data, *datasize, EOM, strlen(EOM), 0);
+    retval = read_string(&rs->rigport, data, *datasize, EOM, strlen(EOM), 0, 1);
 
     if (retval < 0)
     {
diff --git a/rigs/yaesu/newcat.c b/rigs/yaesu/newcat.c
index 87090d94c..6a6f55e22 100644
--- a/rigs/yaesu/newcat.c
+++ b/rigs/yaesu/newcat.c
@@ -9851,7 +9851,7 @@ int newcat_get_cmd(RIG *rig)
 
         /* read the reply */
         if ((rc = read_string(&state->rigport, priv->ret_data, sizeof(priv->ret_data),
-                              &cat_term, sizeof(cat_term), 0)) <= 0)
+                              &cat_term, sizeof(cat_term), 0, 1)) <= 0)
         {
             continue;             /* usually a timeout - retry */
         }
@@ -10051,7 +10051,7 @@ int newcat_set_cmd_validate(RIG *rig)
         if (strlen(valcmd) == 0) { RETURNFUNC(RIG_OK); }
 
         bytes = read_string(&state->rigport, priv->ret_data, sizeof(priv->ret_data),
-                            &cat_term, sizeof(cat_term), 0);
+                            &cat_term, sizeof(cat_term), 0, 1);
 
         // FA and FB success is now verified in rig.c with a followup query
         // so no validation is needed
@@ -10179,7 +10179,7 @@ int newcat_set_cmd(RIG *rig)
 
         /* read the reply */
         if ((rc = read_string(&state->rigport, priv->ret_data, sizeof(priv->ret_data),
-                              &cat_term, sizeof(cat_term), 0)) <= 0)
+                              &cat_term, sizeof(cat_term), 0, 1)) <= 0)
         {
             continue;             /* usually a timeout - retry */
         }
@@ -10249,7 +10249,7 @@ int newcat_set_cmd(RIG *rig)
 
                 /* read/flush the verify command reply which should still be there */
                 if ((rc = read_string(&state->rigport, priv->ret_data, sizeof(priv->ret_data),
-                                      &cat_term, sizeof(cat_term), 0)) > 0)
+                                      &cat_term, sizeof(cat_term), 0, 1)) > 0)
                 {
                     rig_debug(RIG_DEBUG_TRACE, "%s: read count = %d, ret_data = %s\n",
                               __func__, rc, priv->ret_data);
diff --git a/rotators/celestron/celestron.c b/rotators/celestron/celestron.c
index 390006e7a..056c4ad51 100644
--- a/rotators/celestron/celestron.c
+++ b/rotators/celestron/celestron.c
@@ -92,7 +92,7 @@ transaction_write:
 
     /* the answer */
     memset(data, 0, data_len);
-    retval = read_string(&rs->rotport, data, data_len, ACK, strlen(ACK), 0);
+    retval = read_string(&rs->rotport, data, data_len, ACK, strlen(ACK), 0, 1);
 
     if (retval < 0)
     {
diff --git a/rotators/easycomm/easycomm.c b/rotators/easycomm/easycomm.c
index 8facdefd8..e524e69b3 100644
--- a/rotators/easycomm/easycomm.c
+++ b/rotators/easycomm/easycomm.c
@@ -79,7 +79,7 @@ easycomm_transaction(ROT *rot, const char *cmdstr, char *data, size_t data_len)
         return RIG_OK;    /* don't want a reply */
     }
 
-    retval = read_string(&rs->rotport, data, data_len, "\n", 1, 0);
+    retval = read_string(&rs->rotport, data, data_len, "\n", 1, 0, 1);
 
     if (retval < 0)
     {
diff --git a/rotators/ether6/ether6.c b/rotators/ether6/ether6.c
index 77583f462..93af20b7b 100644
--- a/rotators/ether6/ether6.c
+++ b/rotators/ether6/ether6.c
@@ -60,7 +60,7 @@ static int ether_transaction(ROT *rot, char *cmd, int len, char *buf)
         return ret;
     }
 
-    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0);
+    ret = read_string(&rot->state.rotport, buf, BUF_MAX, "\n", sizeof("\n"), 0, 1);
     rig_debug(RIG_DEBUG_VERBOSE, "function %s(2): ret=%d || receive=%s\n", __func__,
               ret, buf);
 
diff --git a/rotators/gs232a/gs232.c b/rotators/gs232a/gs232.c
index 8cd946ce3..88a486def 100644
--- a/rotators/gs232a/gs232.c
+++ b/rotators/gs232a/gs232.c
@@ -94,7 +94,7 @@ transaction_write:
 
     memset(data, 0, data_len);
     retval = read_string(&rs->rotport, data, data_len, REPLY_EOM,
-                         strlen(REPLY_EOM), 0);
+                         strlen(REPLY_EOM), 0, 1);
 
     if (retval < 0)
     {
diff --git a/rotators/gs232a/gs232a.c b/rotators/gs232a/gs232a.c
index 6def6bb32..783184007 100644
--- a/rotators/gs232a/gs232a.c
+++ b/rotators/gs232a/gs232a.c
@@ -104,7 +104,7 @@ transaction_write:
     {
         memset(data, 0, data_len);
         retval = read_string(&rs->rotport, data, data_len, REPLY_EOM,
-                             strlen(REPLY_EOM), 0);
+                             strlen(REPLY_EOM), 0, 1);
 
         if (strncmp(data, "\r\n", 2) == 0
                 || strchr(data, '>'))
diff --git a/rotators/gs232a/gs232b.c b/rotators/gs232a/gs232b.c
index 38002c88e..b8ecf6b7e 100644
--- a/rotators/gs232a/gs232b.c
+++ b/rotators/gs232a/gs232b.c
@@ -104,7 +104,7 @@ transaction_write:
 
     memset(data, 0, data_len);
     retval = read_string(&rs->rotport, data, data_len, REPLY_EOM,
-                         strlen(REPLY_EOM), 0);
+                         strlen(REPLY_EOM), 0, 1);
 
     if (strncmp(data, "\r\n", 2) == 0 || strchr(data, '>'))
     {
diff --git a/rotators/ioptron/rot_ioptron.c b/rotators/ioptron/rot_ioptron.c
index d28c3f0ba..12fa96f12 100644
--- a/rotators/ioptron/rot_ioptron.c
+++ b/rotators/ioptron/rot_ioptron.c
@@ -108,7 +108,7 @@ transaction_write:
 
     /** the answer */
     memset(data, 0, data_len);
-    retval = read_string(&rs->rotport, data, data_len, ACK, strlen(ACK), 0);
+    retval = read_string(&rs->rotport, data, data_len, ACK, strlen(ACK), 0, 1);
 
     if (retval < 0)
     {
diff --git a/rotators/m2/rc2800.c b/rotators/m2/rc2800.c
index 9f82705d9..ea39f8f49 100644
--- a/rotators/m2/rc2800.c
+++ b/rotators/m2/rc2800.c
@@ -204,13 +204,13 @@ transaction_write:
 
     /* then comes the answer */
     memset(data, 0, data_len);
-    retval = read_string(&rs->rotport, data, data_len, CR, strlen(CR), 0);
+    retval = read_string(&rs->rotport, data, data_len, CR, strlen(CR), 0, 1);
 
     // some models seem to echo -- so we'll check and read again if echoed
     if (cmdstr && strcmp(data, cmdstr) == 0)
     {
         memset(data, 0, data_len);
-        retval = read_string(&rs->rotport, data, data_len, CR, strlen(CR), 0);
+        retval = read_string(&rs->rotport, data, data_len, CR, strlen(CR), 0, 1);
     }
 
     if (retval < 0)
diff --git a/rotators/meade/meade.c b/rotators/meade/meade.c
index ab740b4f3..c05dc1c90 100644
--- a/rotators/meade/meade.c
+++ b/rotators/meade/meade.c
@@ -129,7 +129,7 @@ transaction:
         if (data != NULL)
         {
             return_value = read_string(&rs->rotport, data, expected_return_length + 1,
-                                       "\r\n", strlen("\r\n"), 0);
+                                       "\r\n", strlen("\r\n"), 0, 1);
 
             if (return_value > 0)
             {
diff --git a/rotators/prosistel/prosistel.c b/rotators/prosistel/prosistel.c
index 02bd414c6..74bbac099 100644
--- a/rotators/prosistel/prosistel.c
+++ b/rotators/prosistel/prosistel.c
@@ -98,7 +98,7 @@ transaction_write:
     }
 
     // Remember to check for STXA,G,R or STXA,?,XXX,R 10 bytes
-    retval = read_string(&rs->rotport, data, 20, CR, strlen(CR), 0);
+    retval = read_string(&rs->rotport, data, 20, CR, strlen(CR), 0, 1);
 
     if (retval < 0)
     {
diff --git a/rotators/radant/radant.c b/rotators/radant/radant.c
index ca7e4bc2d..c37ec48b2 100644
--- a/rotators/radant/radant.c
+++ b/rotators/radant/radant.c
@@ -79,7 +79,7 @@ radant_transaction(ROT *rot, const char *cmdstr, char *data, size_t data_len)
         return RIG_OK;    /* don't want a reply */
     }
 
-    retval = read_string(&rs->rotport, data, data_len, "\n", 1, 0);
+    retval = read_string(&rs->rotport, data, data_len, "\n", 1, 0, 1);
 
     if (retval < 0)
     {
diff --git a/rotators/rotorez/rotorez.c b/rotators/rotorez/rotorez.c
index 5de52b704..5666d920a 100644
--- a/rotators/rotorez/rotorez.c
+++ b/rotators/rotorez/rotorez.c
@@ -763,7 +763,7 @@ static int rt21_rot_get_position(ROT *rot, azimuth_t *azimuth,
 
     rs = &rot->state;
 
-    err = read_string(&rs->rotport, az, RT21_AZ_LEN + 1, ";", strlen(";"), 0);
+    err = read_string(&rs->rotport, az, RT21_AZ_LEN + 1, ";", strlen(";"), 0, 1);
 
     if (err < 0)    /* read_string returns negative on error. */
     {
diff --git a/rotators/satel/satel.c b/rotators/satel/satel.c
index fdd009050..d5231c960 100644
--- a/rotators/satel/satel.c
+++ b/rotators/satel/satel.c
@@ -137,7 +137,7 @@ static int satel_cmd(ROT *rot, char *cmd, int cmdlen, char *res, int reslen)
 
     if (reslen > 0 && res != NULL)
     {
-        ret = read_string(&rs->rotport, res, reslen, "\n", 1, 0);
+        ret = read_string(&rs->rotport, res, reslen, "\n", 1, 0, 1);
 
         if (ret < 0)
         {
@@ -163,7 +163,7 @@ static int satel_read_status(ROT *rot, satel_stat_t *stat)
 
 
     // read motion state
-    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0);
+    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0, 1);
 
     if (ret < 0)
     {
@@ -173,7 +173,7 @@ static int satel_read_status(ROT *rot, satel_stat_t *stat)
     stat->motion_enabled = strcmp(resbuf, "Motion ENABLED") == 0 ? true : false;
 
     // XXX skip mode
-    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0);
+    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0, 1);
 
     if (ret < 0)
     {
@@ -181,7 +181,7 @@ static int satel_read_status(ROT *rot, satel_stat_t *stat)
     }
 
     // XXX skip time
-    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0);
+    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0, 1);
 
     if (ret < 0)
     {
@@ -189,7 +189,7 @@ static int satel_read_status(ROT *rot, satel_stat_t *stat)
     }
 
     // read azimuth line
-    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0);
+    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0, 1);
 
     if (ret < 0)
     {
@@ -201,7 +201,7 @@ static int satel_read_status(ROT *rot, satel_stat_t *stat)
     stat->az = (int)strtof(p, NULL);
 
     // read elevation line
-    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0);
+    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0, 1);
 
     if (ret < 0)
     {
@@ -213,7 +213,7 @@ static int satel_read_status(ROT *rot, satel_stat_t *stat)
     stat->el = (int)strtof(p, NULL);
 
     // skip blank line
-    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0);
+    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0, 1);
 
     if (ret < 0)
     {
@@ -221,7 +221,7 @@ static int satel_read_status(ROT *rot, satel_stat_t *stat)
     }
 
     // XXX skip stored position count
-    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0);
+    ret = read_string(&rs->rotport, resbuf, BUF_SIZE, "\n", 1, 0, 1);
 
     if (ret < 0)
     {
diff --git a/src/iofunc.c b/src/iofunc.c
index 232bc3fb0..d4b6ebf35 100644
--- a/src/iofunc.c
+++ b/src/iofunc.c
@@ -672,7 +672,8 @@ int HAMLIB_API read_string(hamlib_port_t *p,
                            size_t rxmax,
                            const char *stopset,
                            int stopset_len,
-                           int flush_flag)
+                           int flush_flag,
+                           int expected_len)
 {
     fd_set rfds, efds;
     struct timeval tv, tv_timeout, start_time, end_time, elapsed_time;
diff --git a/src/iofunc.h b/src/iofunc.h
index 8055acfa8..02e5f503c 100644
--- a/src/iofunc.h
+++ b/src/iofunc.h
@@ -43,6 +43,7 @@ extern HAMLIB_EXPORT(int) read_string(hamlib_port_t *p,
                                       size_t rxmax,
                                       const char *stopset,
                                       int stopset_len,
-                                      int flush_flag);
+                                      int flush_flag,
+                                      int expected_len);
 
 #endif /* _IOFUNC_H */
diff --git a/src/serial.c b/src/serial.c
index 959b546a9..d9607d762 100644
--- a/src/serial.c
+++ b/src/serial.c
@@ -678,7 +678,7 @@ int HAMLIB_API serial_flush(hamlib_port_t *p)
         // we pass an empty stopset so read_string can determine
         // the appropriate stopset for async data
         char stopset[1];
-        len = read_string(p, (char*)buf, sizeof(buf)-1, stopset, 0, 1);
+        len = read_string(p, (char*)buf, sizeof(buf)-1, stopset, 0, 1, 1);
         if  (len > 0)
         {
             int i, binary=0;
diff --git a/tests/ampctl_parse.c b/tests/ampctl_parse.c
index db8d0c55e..f0052cf21 100644
--- a/tests/ampctl_parse.c
+++ b/tests/ampctl_parse.c
@@ -1957,7 +1957,7 @@ declare_proto_amp(send_cmd)
          * assumes CR or LF is end of line char
          * for all ascii protocols
          */
-        retval = read_string(&rs->ampport, buf, BUFSZ, eom_buf, strlen(eom_buf), 0);
+        retval = read_string(&rs->ampport, buf, BUFSZ, eom_buf, strlen(eom_buf), 0, 1);
 
         if (retval < 0)
         {
diff --git a/tests/rigctl_parse.c b/tests/rigctl_parse.c
index 24f53fd02..04f32d6f0 100644
--- a/tests/rigctl_parse.c
+++ b/tests/rigctl_parse.c
@@ -4959,7 +4959,7 @@ declare_proto_rig(send_cmd)
 
         /* Assumes CR or LF is end of line char for all ASCII protocols. */
         retval = read_string(&rs->rigport, (char *)buf, rxbytes, eom_buf,
-                             strlen(eom_buf), 0);
+                             strlen(eom_buf), 0, 1);
 
         if (retval < 0)
         {
diff --git a/tests/rigctlcom.c b/tests/rigctlcom.c
index 5a3a5119a..fdfff6c5f 100644
--- a/tests/rigctlcom.c
+++ b/tests/rigctlcom.c
@@ -626,7 +626,8 @@ int main(int argc, char *argv[])
                              sizeof(ts2000),
                              stop_set,
                              strlen(stop_set),
-                             0);
+                             0,
+                             1);
 
         rig_debug(RIG_DEBUG_TRACE, "%s: status=%d\n", __func__, status);
 
diff --git a/tests/rotctl_parse.c b/tests/rotctl_parse.c
index b9e5e3069..eff5c7c3c 100644
--- a/tests/rotctl_parse.c
+++ b/tests/rotctl_parse.c
@@ -2499,7 +2499,7 @@ declare_proto_rot(send_cmd)
          * assumes CR or LF is end of line char
          * for all ascii protocols
          */
-        retval = read_string(&rs->rotport, buf, BUFSZ, eom_buf, strlen(eom_buf), 0);
+        retval = read_string(&rs->rotport, buf, BUFSZ, eom_buf, strlen(eom_buf), 0, 1);
 
         if (retval < 0)
         {