I'm writing an application that is split into two parts for Mac OS X - a daemon and an agent. I'm using a standard unix socket to communicate between the daemon and the agents. That is, the socket is created with PF_UNIX and SOCK_STREAM.
When agents are created (whenever a user logs in), one of the first things it does is to connect to the socket. This seems to work perfectly for the first agent. However, when the second agent connects, the daemon experiences the following issue:
I'm using select() to check for data that can be read. The select() call succeeds, and indicates that there is data to be read. However, when i call recv() it returns with -1, and errno is set to 35, or "Resource temporarily unavailable".
Now, I would expect this for a non-blocking socket, but I have triple-checked - I never set the socket to be non-blocking.
As far as I can tell, this only happens when a second agent connects to the same unix socket. If I limit myself to one daemon and one agent then everything seems to work perfectly. What could be causing this odd behaviour?