/*

 * 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_ */