Bluetooth on the EV3 - c

Question

Before I get started. Yes, I could use leJOS, ev3dev, or some others, but I'd like to do it this way because that is how I learn.
I am using the CodeSourcery arm-2009q1 arm toolchain. I fetched the required libraries (bluetooth) from here: https://github.com/mindboards/ev3sources.
I am uploading the programs to the brick by using this tool: https://github.com/c4ev3/ev3duder
I have also fetched the brick's shared libraries, but I can not get them to work properly and there is 0 documentation on how to write a c program for the ev3 using the shared libraries. If I could get that working I might be able to use the c_com module to handle bluetooth, but right now bluez and rfcomm in conjunction with: https://github.com/c4ev3/EV3-API for motor and sensor control seems to be my best bet.
Now, with that out of the way:
I'd like to run the EV3 as a bluetooth "server" meaning that I start a program on it and the program opens a socket, binds it, listens for a connection, and then accepts a single connection.
I am able to do open a socket, bind it to anything but channel 1 (I believe this might be the crux of my issue), I am able to listen. These all return 0 (OK) and everything is fine.
Then I try to accept a connection. That instantly returns -1 and sets the remote to address 00:00:00:00:00:00.
My code is pretty much the same as can be found here: https://people.csail.mit.edu/albert/bluez-intro/x502.html
Here it is:
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/rfcomm.h>
#include <ev3.h>
int main(int argc, char **argv)
{
InitEV3();
struct sockaddr_rc loc_addr = { 0 }, rem_addr = { 0 };
char buf[1024] = { 0 };
int sock, client, bytes_read;
socklen_t opt = sizeof(rem_addr);
sock = socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM);
loc_addr.rc_family = AF_BLUETOOTH;
loc_addr.rc_bdaddr = *BDADDR_ANY;
loc_addr.rc_channel = 2; // <-- Anything but 1. 1 seems to be taken
bind(sock, (struct sockaddr *)&loc_addr, sizeof(loc_addr));
listen(sock, 1);
// accept one connection <-- PROGRAM FAILS HERE AS accept() returns -1
client = accept(sock, (struct sockaddr *)&rem_addr, &opt);
// ---- All following code is irrelevant because accept fails ----
ba2str( &rem_addr.rc_bdaddr, buf );
fprintf(stderr, "accepted connection from %s\n", buf);
memset(buf, 0, sizeof(buf));
bytes_read = read(client, buf, sizeof(buf));
if( bytes_read > 0 )
printf("received [%s]\n", buf);
close(client);
close(sock);
FreeEV3();
return 0;
}
I am able to get the same code working on my pi. Even communication back and forth when the ev3api-specific functions are commented out. I just can't fathom why it won't work on the EV3.

Answer 1

I figured it out.
On my raspberry PI, the accept call worked as expected with no quirks. On the EV3 however, the accept call is non-blocking even if it has not been told to act like so.
The solution was to place the accept call in a loop until an incoming connection was in the queue.
while (errno == EAGAIN && ButtonIsUp(BTNEXIT) && client < 0)
client = accept(sock, (struct sockaddr*)&rem_addr, sizeof(rem_addr));
I'll upload the code to github. Contact me if you'd like to do something similar with the EV3.