diff --git a/iocp-internal.h b/iocp-internal.h
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+++ b/iocp-internal.h
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+/*
+ * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _EVENT_IOCP_INTERNAL_H
+#define _EVENT_IOCP_INTERNAL_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct event_overlapped;
+struct event_iocp_port;
+struct evbuffer;
+typedef void (*iocp_callback)(struct event_overlapped *, ev_uintptr_t, ev_ssize_t, int success);
+
+/* This whole file is actually win32 only. We wrap the structures in a win32
+ * ifdef so that we can test-compile code that uses these interfaces on
+ * non-win32 platforms. */
+#ifdef WIN32
+
+/**
+   Internal use only.  Wraps an OVERLAPPED that we're using for libevent
+   functionality.  Whenever an event_iocp_port gets an event for a given
+   OVERLAPPED*, it upcasts the pointer to an event_overlapped, and calls the
+   iocp_callback function with the event_overlapped, the iocp key, and the
+   number of bytes transferred as arguments.
+ */
+struct event_overlapped {
+	OVERLAPPED overlapped;
+	iocp_callback cb;
+};
+
+/* Mingw's headers don't define LPFN_ACCEPTEX. */
+
+typedef BOOL (WINAPI *AcceptExPtr)(SOCKET, SOCKET, PVOID, DWORD, DWORD, DWORD, LPDWORD, LPOVERLAPPED);
+typedef BOOL (WINAPI *ConnectExPtr)(SOCKET, const struct sockaddr *, int, PVOID, DWORD, LPDWORD, LPOVERLAPPED);
+typedef void (WINAPI *GetAcceptExSockaddrsPtr)(PVOID, DWORD, DWORD, DWORD, LPSOCKADDR *, LPINT, LPSOCKADDR *, LPINT);
+
+/** Internal use only. Holds pointers to functions that only some versions of
+    Windows provide.
+ */
+struct win32_extension_fns {
+	AcceptExPtr AcceptEx;
+	ConnectExPtr ConnectEx;
+	GetAcceptExSockaddrsPtr GetAcceptExSockaddrs;
+};
+
+/**
+    Internal use only. Stores a Windows IO Completion port, along with
+    related data.
+ */
+struct event_iocp_port {
+	/** The port itself */
+	HANDLE port;
+	/* A lock to cover internal structures. */
+	CRITICAL_SECTION lock;
+	/** Number of threads ever open on the port. */
+	short n_threads;
+	/** True iff we're shutting down all the threads on this port */
+	short shutdown;
+	/** How often the threads on this port check for shutdown and other
+	 * conditions */
+	long ms;
+	/* The threads that are waiting for events. */
+	HANDLE *threads;
+	/** Number of threads currently open on this port. */
+	short n_live_threads;
+	/** A semaphore to signal when we are done shutting down. */
+	HANDLE *shutdownSemaphore;
+};
+
+const struct win32_extension_fns *event_get_win32_extension_fns(void);
+#else
+/* Dummy definition so we can test-compile more things on unix. */
+struct event_overlapped {
+	iocp_callback cb;
+};
+#endif
+
+/** Initialize the fields in an event_overlapped.
+
+    @param overlapped The struct event_overlapped to initialize
+    @param cb The callback that should be invoked once the IO operation has
+	finished.
+ */
+void event_overlapped_init(struct event_overlapped *, iocp_callback cb);
+
+/** Allocate and return a new evbuffer that supports overlapped IO on a given
+    socket.  The socket must be associated with an IO completion port using
+    event_iocp_port_associate.
+*/
+struct evbuffer *evbuffer_overlapped_new(evutil_socket_t fd);
+
+/** XXXX Document (nickm) */
+evutil_socket_t _evbuffer_overlapped_get_fd(struct evbuffer *buf);
+
+void _evbuffer_overlapped_set_fd(struct evbuffer *buf, evutil_socket_t fd);
+
+/** Start reading data onto the end of an overlapped evbuffer.
+
+    An evbuffer can only have one read pending at a time.  While the read
+    is in progress, no other data may be added to the end of the buffer.
+    The buffer must be created with event_overlapped_init().
+    evbuffer_commit_read() must be called in the completion callback.
+
+    @param buf The buffer to read onto
+    @param n The number of bytes to try to read.
+    @param ol Overlapped object with associated completion callback.
+    @return 0 on success, -1 on error.
+ */
+int evbuffer_launch_read(struct evbuffer *buf, size_t n, struct event_overlapped *ol);
+
+/** Start writing data from the start of an evbuffer.
+
+    An evbuffer can only have one write pending at a time.  While the write is
+    in progress, no other data may be removed from the front of the buffer.
+    The buffer must be created with event_overlapped_init().
+    evbuffer_commit_write() must be called in the completion callback.
+
+    @param buf The buffer to read onto
+    @param n The number of bytes to try to read.
+    @param ol Overlapped object with associated completion callback.
+    @return 0 on success, -1 on error.
+ */
+int evbuffer_launch_write(struct evbuffer *buf, ev_ssize_t n, struct event_overlapped *ol);
+
+/** XXX document */
+void evbuffer_commit_read(struct evbuffer *, ev_ssize_t);
+void evbuffer_commit_write(struct evbuffer *, ev_ssize_t);
+
+/** Create an IOCP, and launch its worker threads.  Internal use only.
+
+    This interface is unstable, and will change.
+ */
+struct event_iocp_port *event_iocp_port_launch(int n_cpus);
+
+/** Associate a file descriptor with an iocp, such that overlapped IO on the
+    fd will happen on one of the iocp's worker threads.
+*/
+int event_iocp_port_associate(struct event_iocp_port *port, evutil_socket_t fd,
+    ev_uintptr_t key);
+
+/** Tell all threads serving an iocp to stop.  Wait for up to waitMsec for all
+    the threads to finish whatever they're doing.  If waitMsec is -1, wait
+    as long as required.  If all the threads are done, free the port and return
+    0. Otherwise, return -1.  If you get a -1 return value, it is safe to call
+    this function again.
+*/
+int event_iocp_shutdown(struct event_iocp_port *port, long waitMsec);
+
+/* FIXME document. */
+int event_iocp_activate_overlapped(struct event_iocp_port *port,
+    struct event_overlapped *o,
+    ev_uintptr_t key, ev_uint32_t n_bytes);
+
+struct event_base;
+/* FIXME document. */
+struct event_iocp_port *event_base_get_iocp(struct event_base *base);
+
+/* FIXME document. */
+int event_base_start_iocp(struct event_base *base, int n_cpus);
+void event_base_stop_iocp(struct event_base *base);
+
+/* FIXME document. */
+struct bufferevent *bufferevent_async_new(struct event_base *base,
+    evutil_socket_t fd, int options);
+
+/* FIXME document. */
+void bufferevent_async_set_connected(struct bufferevent *bev);
+int bufferevent_async_can_connect(struct bufferevent *bev);
+int bufferevent_async_connect(struct bufferevent *bev, evutil_socket_t fd,
+	const struct sockaddr *sa, int socklen);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif