Cannot bind an AF_UNIX socket with large filenames

[Sam Varshavchik <mrsam@xxxxxxxxxxxxxxx>]

It looks like the kernel -- at least 2.6.27.5 -- rejects with EINVAL a 
bind() of an AF_UNIX socket whose given size exceeds sizeof(struct 
sockaddr_un).

Even if I make arrangements for a larger structure to accomodate a path that 
exceeds sockaddr_un's 107 bytes + \0, and I specify the actual size of the 
structure, bind() fails for me.

I don't have the details, but I'm pretty sure other unixes accept domain 
sockets with larger filenames. There, the sockaddr_un structure exists for 
historical reasons, and you can pretty much roll your own.

This is perhaps worth mentioning in the description of EINVAL in unix(7).

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