Date: Tue, 19 Dec 2006 11:03:20 +0200
From: Tuomas Suutari <thsuut@utu.fi>
To: bluez-devel@lists.sourceforge.net
Message-id: <200612191103.20942.thsuut@utu.fi>
MIME-version: 1.0
Subject: [Bluez-devel] rfcomm_sock_sendmsg with len==0 (in Linux 2.6.18)
Reply-To: BlueZ development <bluez-devel@lists.sourceforge.net>
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Sender: bluez-devel-bounces@lists.sourceforge.net
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Hello.

I've made a buffer for socket connections to use with C++ iostreams. 
It's quite simple; just uses send and recv to fill and empty the buffer 
when needed.

It worked fine for a while, but yesterday some strange errors occured 
with it. After few hours of debugging I found that code responsible was 
using syscall send() to Bluetooth socket with buffer length set to 0. 
Problem was that I assumed it to return either -1 on error or 0 when 
success, but instead it returned positive values sometimes. 

Ok, it was stupid calling send() with len==0 anyway, but still (at least 
according to manual) send shouldn't return anything positive then. So I 
traced what kernel code is responsible and found it's 
rfcomm_sock_sendmsg() in net/bluetooth/rfcomm/sock.c. It returns 
uninitialized variable err, if called with len==0.

Simple fix is to initialize err to 0.

-- 
Tuomas Suutari | +358 50 3806983 | thsuut@utu.fi

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