Fixed compilation break on platforms without TIOCSRS485

The serial mode and rts flags are now initialized in new function.
Original patch provided by Jaime Alberto Silva
<jaime@sgautomatizacion.com>.

src/modbus-rtu-private.h

@@ -84,6 +84,8 @@ typedef struct _modbus_rtu {
 #endif
 #if HAVE_DECL_TIOCSRS485
     int serial_mode;
+#endif
+#if HAVE_DECL_TIOCM_RTS
     int rts;
 #endif
 } modbus_rtu_t;

src/modbus-rtu.c

@@ -31,8 +31,11 @@
 #include "modbus-rtu.h"
 #include "modbus-rtu-private.h"
 
-#if HAVE_DECL_TIOCSRS485
+#if HAVE_DECL_TIOCSRS485 || HAVE_DECL_TIOCM_RTS
 #include <sys/ioctl.h>
+#endif
+
+#if HAVE_DECL_TIOCSRS485
 #include <linux/serial.h>
 #endif
 
@@ -279,6 +282,7 @@ ssize_t _modbus_rtu_send(modbus_t *ctx, const uint8_t *req, int req_length)
     DWORD n_bytes = 0;
     return (WriteFile(ctx_rtu->w_ser.fd, req, req_length, &n_bytes, NULL)) ? n_bytes : -1;
 #else
+#if HAVE_DECL_TIOCM_RTS
     modbus_rtu_t *ctx_rtu = ctx->backend_data;
     if (ctx_rtu->rts != MODBUS_RTU_RTS_NONE) {
         ssize_t size;
@@ -297,9 +301,12 @@ ssize_t _modbus_rtu_send(modbus_t *ctx, const uint8_t *req, int req_length)
 
         return size;
     } else {
+#endif
         return write(ctx->s, req, req_length);
+#if HAVE_DECL_TIOCM_RTS
     }
 #endif
+#endif
 }
 
 ssize_t _modbus_rtu_recv(modbus_t *ctx, uint8_t *rsp, int rsp_length)
@@ -760,15 +767,6 @@ static int _modbus_rtu_connect(modbus_t *ctx)
     }
 #endif
 
-#if HAVE_DECL_TIOCSRS485
-    /* The RS232 mode has been set by default */
-    ctx_rtu->serial_mode = MODBUS_RTU_RS232;
-
-    /* The RTS use has been set by default */
-    ctx_rtu->rts = MODBUS_RTU_RTS_NONE;
-
-#endif
-
     return 0;
 }
 
@@ -830,8 +828,8 @@ int modbus_rtu_get_serial_mode(modbus_t *ctx) {
 
 int modbus_rtu_set_rts(modbus_t *ctx, int mode)
 {
-#if HAVE_DECL_TIOCM_RTS
     if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) {
+#if HAVE_DECL_TIOCM_RTS
         modbus_rtu_t *ctx_rtu = ctx->backend_data;
 
         if (mode == MODBUS_RTU_RTS_NONE || mode == MODBUS_RTU_RTS_UP ||
@@ -843,8 +841,14 @@ int modbus_rtu_set_rts(modbus_t *ctx, int mode)
 
             return 0;
         }
-    }
+#else
+        if (ctx->debug) {
+            fprintf(stderr, "This function isn't supported on your platform\n");
+        }
+        errno = ENOTSUP;
+        return -1;
 #endif
+    }
     /* Wrong backend or invalid mode specified */
     errno = EINVAL;
     return -1;
@@ -852,8 +856,16 @@ int modbus_rtu_set_rts(modbus_t *ctx, int mode)
 
 int modbus_rtu_get_rts(modbus_t *ctx) {
     if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) {
+#if HAVE_DECL_TIOCM_RTS
         modbus_rtu_t *ctx_rtu = ctx->backend_data;
         return ctx_rtu->rts;
+#else
+        if (ctx->debug) {
+            fprintf(stderr, "This function isn't supported on your platform\n");
+        }
+        errno = ENOTSUP;
+        return -1;
+#endif
     } else {
         errno = EINVAL;
         return -1;
@@ -1009,5 +1021,15 @@ modbus_t* modbus_new_rtu(const char *device,
     ctx_rtu->data_bit = data_bit;
     ctx_rtu->stop_bit = stop_bit;
 
+#if HAVE_DECL_TIOCSRS485
+    /* The RS232 mode has been set by default */
+    ctx_rtu->serial_mode = MODBUS_RTU_RS232;
+#endif
+
+#if HAVE_DECL_TIOCM_RTS
+    /* The RTS use has been set by default */
+    ctx_rtu->rts = MODBUS_RTU_RTS_NONE;
+#endif
+
     return ctx;
 }