[ECOS] accept() behaviour (out of file descriptors)

[Christoph Csebits <christoph dot csebits at frequentis dot com>]

hi,

i am a bit confused about how accept() works in eCos.

In eCos: accept() when called directly allocates a file descriptor
(with a new file pointer) and then blocks until a connection
was established.

When a client connects, a new socket is allocated and
somehow related to the previously allocated file descriptor
(and file pointer).

The socket is returned and when calling accept() again it
gets a new file descriptor and then blocks again.

Now let us assume there are no file descriptors available.
What happens is, that accept() does not block and returns
-1 (errno=EMFILE) immediately.

accept() "returns" EMFILE even though no client had connected.

Using accept() like below, results in an endless loop (busy waiting!)
(until a file descriptor is freed).

for (;;)
{
   int s;
   if ((s = accept(...)) < 0 )
   {
      perror("accept");
   }
   else
   {
      // handle connection
   }
}

In linux accept() does allocate a new file descriptor _only_after_
a connection has established. If a client connects and
no file descriptor is available the connection is aborted.
("Connection closed by foreign host.")
And accept() returns -1 (errno=EMFILE) and when called again
it blocks until the next client wants to connect.

I think this is the right way to handle such a situation.

What do you think about how accept() should behave?

Note that we implemented a linux-like accept() for eCos (only FreeBSD).
I can send a patch if someone is interested.

regards, Christoph
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