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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;

 };

 /** 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_off_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_ */