From 005e5f2f72e85e41ca96ecb4b82c735a55a4c404 Mon Sep 17 00:00:00 2001
From: fbernon <fbernon>
Date: Mon, 26 Mar 2007 15:37:48 +0000
Subject: [PATCH] api_lib.c (from Dmitry Potapov) : patch for netconn_write(),
 fixes a possible race condition which cause to send some garbage. It is not a
 definitive solution, but the patch does solve the problem for most cases.

---
 CHANGELOG         |  5 +++++
 src/api/api_lib.c | 11 +++++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 57412a43..a88344c7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -78,6 +78,11 @@ HISTORY
 
   ++ Bug fixes:
 
+  2007-03-26 Frédéric Bernon (based on patch from Dmitry Potapov)
+  * api_lib.c: patch for netconn_write(), fixes a possible race condition which cause
+    to send some garbage. It is not a definitive solution, but the patch does solve
+    the problem for most cases.
+
   2007-03-22 Frédéric Bernon
   * api_msg.h, api_msg.c: Remove obsolete API_MSG_ACCEPT and do_accept (never used).
 
diff --git a/src/api/api_lib.c b/src/api/api_lib.c
index b18d919f..128ca288 100644
--- a/src/api/api_lib.c
+++ b/src/api/api_lib.c
@@ -589,7 +589,7 @@ err_t
 netconn_write(struct netconn *conn, const void *dataptr, u16_t size, u8_t copy)
 {
   struct api_msg msg;
-  u16_t len;
+  u16_t len, sndbuf;
   
   if (conn == NULL) {
     return ERR_VAL;
@@ -608,16 +608,15 @@ netconn_write(struct netconn *conn, const void *dataptr, u16_t size, u8_t copy)
     msg.msg.msg.w.copy = copy;
     
     if (conn->type == NETCONN_TCP) {
-      if (tcp_sndbuf(conn->pcb.tcp) == 0) {
+      while ((sndbuf = tcp_sndbuf(conn->pcb.tcp)) == 0) {
         sys_sem_wait(conn->sem);
         if (conn->err != ERR_OK) {
           goto ret;
         }
       }
-      if (size > tcp_sndbuf(conn->pcb.tcp)) {
-        /* We cannot send more than one send buffer's worth of data at a
-           time. */
-        len = tcp_sndbuf(conn->pcb.tcp);
+      if (size > sndbuf) {
+        /* We cannot send more than one send buffer's worth of data at a time. */
+        len = sndbuf;
       } else {
         len = size;
       }