Take a look:-------------------------
// Receive player’s name
result = SDLNet_TCP_Recv(me->Socket, me->Name, 16);
if (result < 0)
{
fprintf(stderr, “Couldn’t receive player’s name: %s.\r\nClosing
connection”, SDLNet_GetError());
SDLNet_TCP_Close(me->Socket);
return -1;
}
I used GDB to find out that, before that snippet, me->Socket is valid,
but after it’s null. I know I close the socket if result is less than 0,
but if the closing function executes then it must return -1 also, which
means the next part of that function shouldn’t execute…
This is in a different thread, but nothing happens on the other (main)
thread, it just sits and waits for someone to connect, so that can’t be
affecting the output of this thread function.
I bet that you have a buffer overrun here. The receive function does
definitely not modify the value of the first argument passed to it, because
it can’t. However, you are passing a related pointer (me->Name) to it, and if
that buffer is too small, it will happily overwrite anything related there.
Also, I wouldn’t hard-code the size 16 there, because it means that you have
to keep several places where this constant is used in sync. Use a constant
with a name, or maybe a macro, or use ‘sizeof me->Name’. Also don’t forget to
NUL-terminate the string.
UliOn Saturday 08 September 2007 04:55:20 L-28C wrote:
Ulrich Eckhardt wrote:
I bet that you have a buffer overrun here. The receive function does
definitely not modify the value of the first argument passed to it, because
it can’t. However, you are passing a related pointer (me->Name) to it, and if
that buffer is too small, it will happily overwrite anything related there.
Yes, I contemplated that possibility, but the buffer is 16 bytes…
Also, I wouldn’t hard-code the size 16 there, because it means that you have
to keep several places where this constant is used in sync. Use a constant
with a name, or maybe a macro, or use ‘sizeof me->Name’.
I’ll do that.
Any multithreading going on? Tossin it out there just in case…> ----- Original Message -----
From: sdl-bounces@lists.libsdl.org [mailto:sdl-bounces at lists.libsdl.org] On
Behalf Of L-28C
Sent: Sunday, September 09, 2007 4:36 PM
To: sdl at libsdl.org
Subject: Re: [SDL] SDLNet_TCP_Recv() returns… null socket?
Ulrich Eckhardt wrote:
I bet that you have a buffer overrun here. The receive function does
definitely not modify the value of the first argument passed to it,
because
it can’t. However, you are passing a related pointer (me->Name) to it, and
if
that buffer is too small, it will happily overwrite anything related
there.
Yes, I contemplated that possibility, but the buffer is 16 bytes…
Also, I wouldn’t hard-code the size 16 there, because it means that you
have
to keep several places where this constant is used in sync. Use a constant
with a name, or maybe a macro, or use ‘sizeof me->Name’.
I’ll do that.
I was just thinking that perhaps another thread was changing the value of
your variable.> ----- Original Message -----
From: sdl-bounces@lists.libsdl.org [mailto:sdl-bounces at lists.libsdl.org] On
Behalf Of Leo M. Cabrera
Sent: Tuesday, September 11, 2007 11:53 AM
To: A list for developers using the SDL library. (includes SDL-announce)
Subject: Re: [SDL] SDLNet_TCP_Recv() returns… null socket?
Alan Wolfe wrote:
Any multithreading going on? Tossin it out there just in case…
Uh… Yes? o_O
I fixed it, I can’t remember exactly how I did it (lol) but I doubt it
had anything to do with threads…
