diff --git a/evbuffer-internal.h b/evbuffer-internal.h
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+/*
+ * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
+ * Copyright (c) 2007-2012 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 _EVBUFFER_INTERNAL_H_
+#define _EVBUFFER_INTERNAL_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "event2/event-config.h"
+#include "event2/util.h"
+#include "util-internal.h"
+#include "defer-internal.h"
+
+/* Experimental cb flag: "never deferred."  Implementation note:
+ * these callbacks may get an inaccurate view of n_del/n_added in their
+ * arguments. */
+#define EVBUFFER_CB_NODEFER 2
+
+#ifdef WIN32
+#include <winsock2.h>
+#endif
+#include <sys/queue.h>
+
+/* Minimum allocation for a chain.  We define this so that we're burning no
+ * more than 5% of each allocation on overhead.  It would be nice to lose even
+ * less space, though. */
+#if _EVENT_SIZEOF_VOID_P < 8
+#define MIN_BUFFER_SIZE	512
+#else
+#define MIN_BUFFER_SIZE	1024
+#endif
+
+/** A single evbuffer callback for an evbuffer. This function will be invoked
+ * when bytes are added to or removed from the evbuffer. */
+struct evbuffer_cb_entry {
+	/** Structures to implement a doubly-linked queue of callbacks */
+	TAILQ_ENTRY(evbuffer_cb_entry) next;
+	/** The callback function to invoke when this callback is called.
+	    If EVBUFFER_CB_OBSOLETE is set in flags, the cb_obsolete field is
+	    valid; otherwise, cb_func is valid. */
+	union {
+		evbuffer_cb_func cb_func;
+		evbuffer_cb cb_obsolete;
+	} cb;
+	/** Argument to pass to cb. */
+	void *cbarg;
+	/** Currently set flags on this callback. */
+	ev_uint32_t flags;
+};
+
+struct bufferevent;
+struct evbuffer_chain;
+struct evbuffer {
+	/** The first chain in this buffer's linked list of chains. */
+	struct evbuffer_chain *first;
+	/** The last chain in this buffer's linked list of chains. */
+	struct evbuffer_chain *last;
+
+	/** Pointer to the next pointer pointing at the 'last_with_data' chain.
+	 *
+	 * To unpack:
+	 *
+	 * The last_with_data chain is the last chain that has any data in it.
+	 * If all chains in the buffer are empty, it is the first chain.
+	 * If the buffer has no chains, it is NULL.
+	 *
+	 * The last_with_datap pointer points at _whatever 'next' pointer_
+	 * points at the last_with_datap chain.  If the last_with_data chain
+	 * is the first chain, or it is NULL, then the last_with_datap pointer
+	 * is &buf->first.
+	 */
+	struct evbuffer_chain **last_with_datap;
+
+	/** Total amount of bytes stored in all chains.*/
+	size_t total_len;
+
+	/** Number of bytes we have added to the buffer since we last tried to
+	 * invoke callbacks. */
+	size_t n_add_for_cb;
+	/** Number of bytes we have removed from the buffer since we last
+	 * tried to invoke callbacks. */
+	size_t n_del_for_cb;
+
+#ifndef _EVENT_DISABLE_THREAD_SUPPORT
+	/** A lock used to mediate access to this buffer. */
+	void *lock;
+#endif
+	/** True iff we should free the lock field when we free this
+	 * evbuffer. */
+	unsigned own_lock : 1;
+	/** True iff we should not allow changes to the front of the buffer
+	 * (drains or prepends). */
+	unsigned freeze_start : 1;
+	/** True iff we should not allow changes to the end of the buffer
+	 * (appends) */
+	unsigned freeze_end : 1;
+	/** True iff this evbuffer's callbacks are not invoked immediately
+	 * upon a change in the buffer, but instead are deferred to be invoked
+	 * from the event_base's loop.	Useful for preventing enormous stack
+	 * overflows when we have mutually recursive callbacks, and for
+	 * serializing callbacks in a single thread. */
+	unsigned deferred_cbs : 1;
+#ifdef WIN32
+	/** True iff this buffer is set up for overlapped IO. */
+	unsigned is_overlapped : 1;
+#endif
+	/** Zero or more EVBUFFER_FLAG_* bits */
+	ev_uint32_t flags;
+
+	/** Used to implement deferred callbacks. */
+	struct deferred_cb_queue *cb_queue;
+
+	/** A reference count on this evbuffer.	 When the reference count
+	 * reaches 0, the buffer is destroyed.	Manipulated with
+	 * evbuffer_incref and evbuffer_decref_and_unlock and
+	 * evbuffer_free. */
+	int refcnt;
+
+	/** A deferred_cb handle to make all of this buffer's callbacks
+	 * invoked from the event loop. */
+	struct deferred_cb deferred;
+
+	/** A doubly-linked-list of callback functions */
+	TAILQ_HEAD(evbuffer_cb_queue, evbuffer_cb_entry) callbacks;
+
+	/** The parent bufferevent object this evbuffer belongs to.
+	 * NULL if the evbuffer stands alone. */
+	struct bufferevent *parent;
+};
+
+#if _EVENT_SIZEOF_OFF_T < _EVENT_SIZEOF_SIZE_T
+typedef ev_ssize_t ev_misalign_t;
+#define EVBUFFER_CHAIN_MAX ((size_t)EV_SSIZE_MAX)
+#else
+typedef ev_off_t ev_misalign_t;
+#if _EVENT_SIZEOF_OFF_T > _EVENT_SIZEOF_SIZE_T
+#define EVBUFFER_CHAIN_MAX EV_SIZE_MAX
+#else
+#define EVBUFFER_CHAIN_MAX ((size_t)EV_SSIZE_MAX)
+#endif
+#endif
+
+/** A single item in an evbuffer. */
+struct evbuffer_chain {
+	/** points to next buffer in the chain */
+	struct evbuffer_chain *next;
+
+	/** total allocation available in the buffer field. */
+	size_t buffer_len;
+
+	/** unused space at the beginning of buffer or an offset into a
+	 * file for sendfile buffers. */
+	ev_misalign_t misalign;
+
+	/** Offset into buffer + misalign at which to start writing.
+	 * In other words, the total number of bytes actually stored
+	 * in buffer. */
+	size_t off;
+
+	/** Set if special handling is required for this chain */
+	unsigned flags;
+#define EVBUFFER_MMAP		0x0001	/**< memory in buffer is mmaped */
+#define EVBUFFER_SENDFILE	0x0002	/**< a chain used for sendfile */
+#define EVBUFFER_REFERENCE	0x0004	/**< a chain with a mem reference */
+#define EVBUFFER_IMMUTABLE	0x0008	/**< read-only chain */
+	/** a chain that mustn't be reallocated or freed, or have its contents
+	 * memmoved, until the chain is un-pinned. */
+#define EVBUFFER_MEM_PINNED_R	0x0010
+#define EVBUFFER_MEM_PINNED_W	0x0020
+#define EVBUFFER_MEM_PINNED_ANY (EVBUFFER_MEM_PINNED_R|EVBUFFER_MEM_PINNED_W)
+	/** a chain that should be freed, but can't be freed until it is
+	 * un-pinned. */
+#define EVBUFFER_DANGLING	0x0040
+
+	/** Usually points to the read-write memory belonging to this
+	 * buffer allocated as part of the evbuffer_chain allocation.
+	 * For mmap, this can be a read-only buffer and
+	 * EVBUFFER_IMMUTABLE will be set in flags.  For sendfile, it
+	 * may point to NULL.
+	 */
+	unsigned char *buffer;
+};
+
+/* this is currently used by both mmap and sendfile */
+/* TODO(niels): something strange needs to happen for Windows here, I am not
+ * sure what that is, but it needs to get looked into.
+ */
+struct evbuffer_chain_fd {
+	int fd;	/**< the fd associated with this chain */
+};
+
+/** callback for a reference buffer; lets us know what to do with it when
+ * we're done with it. */
+struct evbuffer_chain_reference {
+	evbuffer_ref_cleanup_cb cleanupfn;
+	void *extra;
+};
+
+#define EVBUFFER_CHAIN_SIZE sizeof(struct evbuffer_chain)
+/** Return a pointer to extra data allocated along with an evbuffer. */
+#define EVBUFFER_CHAIN_EXTRA(t, c) (t *)((struct evbuffer_chain *)(c) + 1)
+
+/** Assert that we are holding the lock on an evbuffer */
+#define ASSERT_EVBUFFER_LOCKED(buffer)			\
+	EVLOCK_ASSERT_LOCKED((buffer)->lock)
+
+#define EVBUFFER_LOCK(buffer)						\
+	do {								\
+		EVLOCK_LOCK((buffer)->lock, 0);				\
+	} while (0)
+#define EVBUFFER_UNLOCK(buffer)						\
+	do {								\
+		EVLOCK_UNLOCK((buffer)->lock, 0);			\
+	} while (0)
+#define EVBUFFER_LOCK2(buffer1, buffer2)				\
+	do {								\
+		EVLOCK_LOCK2((buffer1)->lock, (buffer2)->lock, 0, 0);	\
+	} while (0)
+#define EVBUFFER_UNLOCK2(buffer1, buffer2)				\
+	do {								\
+		EVLOCK_UNLOCK2((buffer1)->lock, (buffer2)->lock, 0, 0);	\
+	} while (0)
+
+/** Increase the reference count of buf by one. */
+void _evbuffer_incref(struct evbuffer *buf);
+/** Increase the reference count of buf by one and acquire the lock. */
+void _evbuffer_incref_and_lock(struct evbuffer *buf);
+/** Pin a single buffer chain using a given flag. A pinned chunk may not be
+ * moved or freed until it is unpinned. */
+void _evbuffer_chain_pin(struct evbuffer_chain *chain, unsigned flag);
+/** Unpin a single buffer chain using a given flag. */
+void _evbuffer_chain_unpin(struct evbuffer_chain *chain, unsigned flag);
+/** As evbuffer_free, but requires that we hold a lock on the buffer, and
+ * releases the lock before freeing it and the buffer. */
+void _evbuffer_decref_and_unlock(struct evbuffer *buffer);
+
+/** As evbuffer_expand, but does not guarantee that the newly allocated memory
+ * is contiguous.  Instead, it may be split across two or more chunks. */
+int _evbuffer_expand_fast(struct evbuffer *, size_t, int);
+
+/** Helper: prepares for a readv/WSARecv call by expanding the buffer to
+ * hold enough memory to read 'howmuch' bytes in possibly noncontiguous memory.
+ * Sets up the one or two iovecs in 'vecs' to point to the free memory and its
+ * extent, and *chainp to point to the first chain that we'll try to read into.
+ * Returns the number of vecs used.
+ */
+int _evbuffer_read_setup_vecs(struct evbuffer *buf, ev_ssize_t howmuch,
+    struct evbuffer_iovec *vecs, int n_vecs, struct evbuffer_chain ***chainp,
+    int exact);
+
+/* Helper macro: copies an evbuffer_iovec in ei to a win32 WSABUF in i. */
+#define WSABUF_FROM_EVBUFFER_IOV(i,ei) do {		\
+		(i)->buf = (ei)->iov_base;		\
+		(i)->len = (unsigned long)(ei)->iov_len;	\
+	} while (0)
+/* XXXX the cast above is safe for now, but not if we allow mmaps on win64.
+ * See note in buffer_iocp's launch_write function */
+
+/** Set the parent bufferevent object for buf to bev */
+void evbuffer_set_parent(struct evbuffer *buf, struct bufferevent *bev);
+
+void evbuffer_invoke_callbacks(struct evbuffer *buf);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _EVBUFFER_INTERNAL_H_ */