283 lines
10 KiB
C
283 lines
10 KiB
C
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/* $NetBSD: evbuffer-internal.h,v 1.2 2013/04/11 16:56:41 christos Exp $ */
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/*
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* Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
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* Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _EVBUFFER_INTERNAL_H_
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#define _EVBUFFER_INTERNAL_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "event2/event-config.h"
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#include "event2/util.h"
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#include "util-internal.h"
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#include "defer-internal.h"
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/* Experimental cb flag: "never deferred." Implementation note:
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* these callbacks may get an inaccurate view of n_del/n_added in their
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* arguments. */
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#define EVBUFFER_CB_NODEFER 2
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#ifdef WIN32
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#include <winsock2.h>
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#endif
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#include <sys/queue.h>
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/* Minimum allocation for a chain. We define this so that we're burning no
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* more than 5% of each allocation on overhead. It would be nice to lose even
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* less space, though. */
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#if _EVENT_SIZEOF_VOID_P < 8
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#define MIN_BUFFER_SIZE 512
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#else
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#define MIN_BUFFER_SIZE 1024
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#endif
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/** A single evbuffer callback for an evbuffer. This function will be invoked
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* when bytes are added to or removed from the evbuffer. */
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struct evbuffer_cb_entry {
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/** Structures to implement a doubly-linked queue of callbacks */
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TAILQ_ENTRY(evbuffer_cb_entry) next;
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/** The callback function to invoke when this callback is called.
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If EVBUFFER_CB_OBSOLETE is set in flags, the cb_obsolete field is
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valid; otherwise, cb_func is valid. */
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union {
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evbuffer_cb_func cb_func;
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evbuffer_cb cb_obsolete;
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} cb;
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/** Argument to pass to cb. */
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void *cbarg;
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/** Currently set flags on this callback. */
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ev_uint32_t flags;
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};
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struct bufferevent;
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struct evbuffer_chain;
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struct evbuffer {
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/** The first chain in this buffer's linked list of chains. */
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struct evbuffer_chain *first;
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/** The last chain in this buffer's linked list of chains. */
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struct evbuffer_chain *last;
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/** Pointer to the next pointer pointing at the 'last_with_data' chain.
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*
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* To unpack:
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*
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* The last_with_data chain is the last chain that has any data in it.
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* If all chains in the buffer are empty, it is the first chain.
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* If the buffer has no chains, it is NULL.
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*
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* The last_with_datap pointer points at _whatever 'next' pointer_
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* points at the last_with_datap chain. If the last_with_data chain
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* is the first chain, or it is NULL, then the last_with_datap pointer
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* is &buf->first.
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*/
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struct evbuffer_chain **last_with_datap;
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/** Total amount of bytes stored in all chains.*/
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size_t total_len;
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/** Number of bytes we have added to the buffer since we last tried to
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* invoke callbacks. */
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size_t n_add_for_cb;
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/** Number of bytes we have removed from the buffer since we last
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* tried to invoke callbacks. */
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size_t n_del_for_cb;
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#ifndef _EVENT_DISABLE_THREAD_SUPPORT
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/** A lock used to mediate access to this buffer. */
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void *lock;
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#endif
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/** True iff we should free the lock field when we free this
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* evbuffer. */
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unsigned own_lock : 1;
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/** True iff we should not allow changes to the front of the buffer
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* (drains or prepends). */
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unsigned freeze_start : 1;
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/** True iff we should not allow changes to the end of the buffer
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* (appends) */
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unsigned freeze_end : 1;
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/** True iff this evbuffer's callbacks are not invoked immediately
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* upon a change in the buffer, but instead are deferred to be invoked
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* from the event_base's loop. Useful for preventing enormous stack
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* overflows when we have mutually recursive callbacks, and for
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* serializing callbacks in a single thread. */
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unsigned deferred_cbs : 1;
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#ifdef WIN32
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/** True iff this buffer is set up for overlapped IO. */
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unsigned is_overlapped : 1;
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#endif
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/** Zero or more EVBUFFER_FLAG_* bits */
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ev_uint32_t flags;
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/** Used to implement deferred callbacks. */
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struct deferred_cb_queue *cb_queue;
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/** A reference count on this evbuffer. When the reference count
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* reaches 0, the buffer is destroyed. Manipulated with
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* evbuffer_incref and evbuffer_decref_and_unlock and
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* evbuffer_free. */
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int refcnt;
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/** A deferred_cb handle to make all of this buffer's callbacks
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* invoked from the event loop. */
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struct deferred_cb deferred;
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/** A doubly-linked-list of callback functions */
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TAILQ_HEAD(evbuffer_cb_queue, evbuffer_cb_entry) callbacks;
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/** The parent bufferevent object this evbuffer belongs to.
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* NULL if the evbuffer stands alone. */
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struct bufferevent *parent;
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};
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/** A single item in an evbuffer. */
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struct evbuffer_chain {
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/** points to next buffer in the chain */
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struct evbuffer_chain *next;
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/** total allocation available in the buffer field. */
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size_t buffer_len;
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/** unused space at the beginning of buffer or an offset into a
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* file for sendfile buffers. */
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ev_off_t misalign;
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/** Offset into buffer + misalign at which to start writing.
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* In other words, the total number of bytes actually stored
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* in buffer. */
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size_t off;
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/** Set if special handling is required for this chain */
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unsigned flags;
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#define EVBUFFER_MMAP 0x0001 /**< memory in buffer is mmaped */
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#define EVBUFFER_SENDFILE 0x0002 /**< a chain used for sendfile */
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#define EVBUFFER_REFERENCE 0x0004 /**< a chain with a mem reference */
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#define EVBUFFER_IMMUTABLE 0x0008 /**< read-only chain */
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/** a chain that mustn't be reallocated or freed, or have its contents
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* memmoved, until the chain is un-pinned. */
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#define EVBUFFER_MEM_PINNED_R 0x0010
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#define EVBUFFER_MEM_PINNED_W 0x0020
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#define EVBUFFER_MEM_PINNED_ANY (EVBUFFER_MEM_PINNED_R|EVBUFFER_MEM_PINNED_W)
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/** a chain that should be freed, but can't be freed until it is
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* un-pinned. */
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#define EVBUFFER_DANGLING 0x0040
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/** Usually points to the read-write memory belonging to this
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* buffer allocated as part of the evbuffer_chain allocation.
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* For mmap, this can be a read-only buffer and
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* EVBUFFER_IMMUTABLE will be set in flags. For sendfile, it
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* may point to NULL.
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*/
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unsigned char *buffer;
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};
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/* this is currently used by both mmap and sendfile */
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/* TODO(niels): something strange needs to happen for Windows here, I am not
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* sure what that is, but it needs to get looked into.
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*/
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struct evbuffer_chain_fd {
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int fd; /**< the fd associated with this chain */
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};
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/** callback for a reference buffer; lets us know what to do with it when
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* we're done with it. */
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struct evbuffer_chain_reference {
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evbuffer_ref_cleanup_cb cleanupfn;
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void *extra;
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};
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#define EVBUFFER_CHAIN_SIZE sizeof(struct evbuffer_chain)
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/** Return a pointer to extra data allocated along with an evbuffer. */
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#define EVBUFFER_CHAIN_EXTRA(t, c) (t *)((struct evbuffer_chain *)(c) + 1)
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/** Assert that we are holding the lock on an evbuffer */
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#define ASSERT_EVBUFFER_LOCKED(buffer) \
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EVLOCK_ASSERT_LOCKED((buffer)->lock)
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#define EVBUFFER_LOCK(buffer) \
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do { \
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EVLOCK_LOCK((buffer)->lock, 0); \
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} while (/*CONSTCOND*/0)
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#define EVBUFFER_UNLOCK(buffer) \
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do { \
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EVLOCK_UNLOCK((buffer)->lock, 0); \
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} while (/*CONSTCOND*/0)
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#define EVBUFFER_LOCK2(buffer1, buffer2) \
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do { \
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EVLOCK_LOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \
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} while (/*CONSTCOND*/0)
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#define EVBUFFER_UNLOCK2(buffer1, buffer2) \
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do { \
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EVLOCK_UNLOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \
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} while (/*CONSTCOND*/0)
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/** Increase the reference count of buf by one. */
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void _evbuffer_incref(struct evbuffer *buf);
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/** Increase the reference count of buf by one and acquire the lock. */
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void _evbuffer_incref_and_lock(struct evbuffer *buf);
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/** Pin a single buffer chain using a given flag. A pinned chunk may not be
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* moved or freed until it is unpinned. */
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void _evbuffer_chain_pin(struct evbuffer_chain *chain, unsigned flag);
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/** Unpin a single buffer chain using a given flag. */
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void _evbuffer_chain_unpin(struct evbuffer_chain *chain, unsigned flag);
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/** As evbuffer_free, but requires that we hold a lock on the buffer, and
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* releases the lock before freeing it and the buffer. */
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void _evbuffer_decref_and_unlock(struct evbuffer *buffer);
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/** As evbuffer_expand, but does not guarantee that the newly allocated memory
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* is contiguous. Instead, it may be split across two or more chunks. */
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int _evbuffer_expand_fast(struct evbuffer *, size_t, int);
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/** Helper: prepares for a readv/WSARecv call by expanding the buffer to
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* hold enough memory to read 'howmuch' bytes in possibly noncontiguous memory.
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* Sets up the one or two iovecs in 'vecs' to point to the free memory and its
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* extent, and *chainp to point to the first chain that we'll try to read into.
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* Returns the number of vecs used.
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*/
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int _evbuffer_read_setup_vecs(struct evbuffer *buf, ev_ssize_t howmuch,
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struct evbuffer_iovec *vecs, int n_vecs, struct evbuffer_chain ***chainp,
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int exact);
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/* Helper macro: copies an evbuffer_iovec in ei to a win32 WSABUF in i. */
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#define WSABUF_FROM_EVBUFFER_IOV(i,ei) do { \
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(i)->buf = (ei)->iov_base; \
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(i)->len = (unsigned long)(ei)->iov_len; \
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} while (/*CONSTCOND*/0)
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/* XXXX the cast above is safe for now, but not if we allow mmaps on win64.
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* See note in buffer_iocp's launch_write function */
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/** Set the parent bufferevent object for buf to bev */
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void evbuffer_set_parent(struct evbuffer *buf, struct bufferevent *bev);
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void evbuffer_invoke_callbacks(struct evbuffer *buf);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _EVBUFFER_INTERNAL_H_ */
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