From e2c9f5fd4f6e94effdec1938c3f2e37bdc604e84 Mon Sep 17 00:00:00 2001
From: Stéphane Raimbault <stephane.raimbault@gmail.com>
Date: Wed, 4 May 2011 00:14:12 +0200
Subject: [PATCH] Fix flush function of TCP backend on Windows

---
 src/modbus-tcp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/modbus-tcp.c b/src/modbus-tcp.c
index 1f5d453..01661e9 100644
--- a/src/modbus-tcp.c
+++ b/src/modbus-tcp.c
@@ -346,7 +346,10 @@ int _modbus_tcp_flush(modbus_t *ctx)
             return -1;
         }
 
-        rc = recv(ctx->s, devnull, MODBUS_TCP_MAX_ADU_LENGTH, 0);
+        if (rc == 1) {
+            /* There is data to flush */
+            rc = recv(ctx->s, devnull, MODBUS_TCP_MAX_ADU_LENGTH, 0);
+        }
 #endif
         if (ctx->debug && rc != -1) {
             printf("\n%d bytes flushed\n", rc);
--
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