843 lines
30 KiB
C
843 lines
30 KiB
C
/* $NetBSD: buffer.h,v 1.1.1.1 2013/04/11 16:43:34 christos Exp $ */
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/*
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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 _EVENT2_BUFFER_H_
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#define _EVENT2_BUFFER_H_
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/** @file event2/buffer.h
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Functions for buffering data for network sending or receiving.
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An evbuffer can be used for preparing data before sending it to
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the network or conversely for reading data from the network.
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Evbuffers try to avoid memory copies as much as possible. As a
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result, evbuffers can be used to pass data around without actually
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incurring the overhead of copying the data.
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A new evbuffer can be allocated with evbuffer_new(), and can be
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freed with evbuffer_free(). Most users will be using evbuffers via
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the bufferevent interface. To access a bufferevent's evbuffers, use
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bufferevent_get_input() and bufferevent_get_output().
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There are several guidelines for using evbuffers.
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- if you already know how much data you are going to add as a result
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of calling evbuffer_add() multiple times, it makes sense to use
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evbuffer_expand() first to make sure that enough memory is allocated
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before hand.
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- evbuffer_add_buffer() adds the contents of one buffer to the other
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without incurring any unnecessary memory copies.
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- evbuffer_add() and evbuffer_add_buffer() do not mix very well:
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if you use them, you will wind up with fragmented memory in your
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buffer.
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- For high-performance code, you may want to avoid copying data into and out
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of buffers. You can skip the copy step by using
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evbuffer_reserve_space()/evbuffer_commit_space() when writing into a
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buffer, and evbuffer_peek() when reading.
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In Libevent 2.0 and later, evbuffers are represented using a linked
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list of memory chunks, with pointers to the first and last chunk in
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the chain.
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As the contents of an evbuffer can be stored in multiple different
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memory blocks, it cannot be accessed directly. Instead, evbuffer_pullup()
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can be used to force a specified number of bytes to be contiguous. This
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will cause memory reallocation and memory copies if the data is split
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across multiple blocks. It is more efficient, however, to use
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evbuffer_peek() if you don't require that the memory to be contiguous.
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*/
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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 <stdarg.h>
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#ifdef _EVENT_HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#ifdef _EVENT_HAVE_SYS_UIO_H
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#include <sys/uio.h>
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#endif
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#include <event2/util.h>
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/**
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An evbuffer is an opaque data type for efficiently buffering data to be
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sent or received on the network.
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@see event2/event.h for more information
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*/
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struct evbuffer
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#ifdef _EVENT_IN_DOXYGEN
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{}
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#endif
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;
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/**
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Pointer to a position within an evbuffer.
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Used when repeatedly searching through a buffer. Calling any function
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that modifies or re-packs the buffer contents may invalidate all
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evbuffer_ptrs for that buffer. Do not modify these values except with
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evbuffer_ptr_set.
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*/
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struct evbuffer_ptr {
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ev_ssize_t pos;
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/* Do not alter the values of fields. */
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struct {
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void *chain;
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size_t pos_in_chain;
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} _internal;
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};
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/** Describes a single extent of memory inside an evbuffer. Used for
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direct-access functions.
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@see evbuffer_reserve_space, evbuffer_commit_space, evbuffer_peek
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*/
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#ifdef _EVENT_HAVE_SYS_UIO_H
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#define evbuffer_iovec iovec
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/* Internal use -- defined only if we are using the native struct iovec */
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#define _EVBUFFER_IOVEC_IS_NATIVE
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#else
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struct evbuffer_iovec {
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/** The start of the extent of memory. */
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void *iov_base;
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/** The length of the extent of memory. */
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size_t iov_len;
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};
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#endif
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/**
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Allocate storage for a new evbuffer.
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@return a pointer to a newly allocated evbuffer struct, or NULL if an error
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occurred
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*/
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struct evbuffer *evbuffer_new(void);
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/**
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Deallocate storage for an evbuffer.
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@param buf pointer to the evbuffer to be freed
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*/
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void evbuffer_free(struct evbuffer *buf);
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/**
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Enable locking on an evbuffer so that it can safely be used by multiple
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threads at the same time.
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NOTE: when locking is enabled, the lock will be held when callbacks are
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invoked. This could result in deadlock if you aren't careful. Plan
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accordingly!
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@param buf An evbuffer to make lockable.
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@param lock A lock object, or NULL if we should allocate our own.
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@return 0 on success, -1 on failure.
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*/
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int evbuffer_enable_locking(struct evbuffer *buf, void *lock);
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/**
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Acquire the lock on an evbuffer. Has no effect if locking was not enabled
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with evbuffer_enable_locking.
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*/
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void evbuffer_lock(struct evbuffer *buf);
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/**
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Release the lock on an evbuffer. Has no effect if locking was not enabled
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with evbuffer_enable_locking.
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*/
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void evbuffer_unlock(struct evbuffer *buf);
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/** If this flag is set, then we will not use evbuffer_peek(),
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* evbuffer_remove(), evbuffer_remove_buffer(), and so on to read bytes
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* from this buffer: we'll only take bytes out of this buffer by
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* writing them to the network (as with evbuffer_write_atmost), by
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* removing them without observing them (as with evbuffer_drain),
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* or by copying them all out at once (as with evbuffer_add_buffer).
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*
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* Using this option allows the implementation to use sendfile-based
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* operations for evbuffer_add_file(); see that function for more
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* information.
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*
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* This flag is on by default for bufferevents that can take advantage
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* of it; you should never actually need to set it on a bufferevent's
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* output buffer.
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*/
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#define EVBUFFER_FLAG_DRAINS_TO_FD 1
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/** Change the flags that are set for an evbuffer by adding more.
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*
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* @param buffer the evbuffer that the callback is watching.
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* @param cb the callback whose status we want to change.
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* @param flags One or more EVBUFFER_FLAG_* options
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* @return 0 on success, -1 on failure.
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*/
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int evbuffer_set_flags(struct evbuffer *buf, ev_uint64_t flags);
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/** Change the flags that are set for an evbuffer by removing some.
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*
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* @param buffer the evbuffer that the callback is watching.
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* @param cb the callback whose status we want to change.
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* @param flags One or more EVBUFFER_FLAG_* options
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* @return 0 on success, -1 on failure.
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*/
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int evbuffer_clear_flags(struct evbuffer *buf, ev_uint64_t flags);
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/**
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Returns the total number of bytes stored in the evbuffer
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@param buf pointer to the evbuffer
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@return the number of bytes stored in the evbuffer
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*/
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size_t evbuffer_get_length(const struct evbuffer *buf);
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/**
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Returns the number of contiguous available bytes in the first buffer chain.
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This is useful when processing data that might be split into multiple
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chains, or that might all be in the first chain. Calls to
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evbuffer_pullup() that cause reallocation and copying of data can thus be
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avoided.
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@param buf pointer to the evbuffer
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@return 0 if no data is available, otherwise the number of available bytes
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in the first buffer chain.
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*/
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size_t evbuffer_get_contiguous_space(const struct evbuffer *buf);
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/**
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Expands the available space in an evbuffer.
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Expands the available space in the evbuffer to at least datlen, so that
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appending datlen additional bytes will not require any new allocations.
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@param buf the evbuffer to be expanded
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@param datlen the new minimum length requirement
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@return 0 if successful, or -1 if an error occurred
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*/
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int evbuffer_expand(struct evbuffer *buf, size_t datlen);
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/**
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Reserves space in the last chain or chains of an evbuffer.
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Makes space available in the last chain or chains of an evbuffer that can
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be arbitrarily written to by a user. The space does not become
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available for reading until it has been committed with
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evbuffer_commit_space().
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The space is made available as one or more extents, represented by
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an initial pointer and a length. You can force the memory to be
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available as only one extent. Allowing more extents, however, makes the
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function more efficient.
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Multiple subsequent calls to this function will make the same space
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available until evbuffer_commit_space() has been called.
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It is an error to do anything that moves around the buffer's internal
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memory structures before committing the space.
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NOTE: The code currently does not ever use more than two extents.
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This may change in future versions.
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@param buf the evbuffer in which to reserve space.
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@param size how much space to make available, at minimum. The
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total length of the extents may be greater than the requested
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length.
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@param vec an array of one or more evbuffer_iovec structures to
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hold pointers to the reserved extents of memory.
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@param n_vec The length of the vec array. Must be at least 1;
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2 is more efficient.
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@return the number of provided extents, or -1 on error.
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@see evbuffer_commit_space()
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*/
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int
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evbuffer_reserve_space(struct evbuffer *buf, ev_ssize_t size,
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struct evbuffer_iovec *vec, int n_vec);
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/**
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Commits previously reserved space.
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Commits some of the space previously reserved with
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evbuffer_reserve_space(). It then becomes available for reading.
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This function may return an error if the pointer in the extents do
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not match those returned from evbuffer_reserve_space, or if data
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has been added to the buffer since the space was reserved.
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If you want to commit less data than you got reserved space for,
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modify the iov_len pointer of the appropriate extent to a smaller
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value. Note that you may have received more space than you
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requested if it was available!
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@param buf the evbuffer in which to reserve space.
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@param vec one or two extents returned by evbuffer_reserve_space.
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@param n_vecs the number of extents.
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@return 0 on success, -1 on error
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@see evbuffer_reserve_space()
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*/
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int evbuffer_commit_space(struct evbuffer *buf,
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struct evbuffer_iovec *vec, int n_vecs);
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/**
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Append data to the end of an evbuffer.
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@param buf the evbuffer to be appended to
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@param data pointer to the beginning of the data buffer
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@param datlen the number of bytes to be copied from the data buffer
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@return 0 on success, -1 on failure.
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*/
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int evbuffer_add(struct evbuffer *buf, const void *data, size_t datlen);
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/**
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Read data from an evbuffer and drain the bytes read.
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If more bytes are requested than are available in the evbuffer, we
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only extract as many bytes as were available.
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@param buf the evbuffer to be read from
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@param data the destination buffer to store the result
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@param datlen the maximum size of the destination buffer
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@return the number of bytes read, or -1 if we can't drain the buffer.
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*/
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int evbuffer_remove(struct evbuffer *buf, void *data, size_t datlen);
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/**
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Read data from an evbuffer, and leave the buffer unchanged.
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If more bytes are requested than are available in the evbuffer, we
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only extract as many bytes as were available.
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@param buf the evbuffer to be read from
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@param data_out the destination buffer to store the result
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@param datlen the maximum size of the destination buffer
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@return the number of bytes read, or -1 if we can't drain the buffer.
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*/
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ev_ssize_t evbuffer_copyout(struct evbuffer *buf, void *data_out, size_t datlen);
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/**
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Read data from an evbuffer into another evbuffer, draining
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the bytes from the source buffer. This function avoids copy
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operations to the extent possible.
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If more bytes are requested than are available in src, the src
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buffer is drained completely.
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@param src the evbuffer to be read from
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@param dst the destination evbuffer to store the result into
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@param datlen the maximum numbers of bytes to transfer
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@return the number of bytes read
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*/
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int evbuffer_remove_buffer(struct evbuffer *src, struct evbuffer *dst,
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size_t datlen);
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/** Used to tell evbuffer_readln what kind of line-ending to look for.
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*/
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enum evbuffer_eol_style {
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/** Any sequence of CR and LF characters is acceptable as an
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* EOL.
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*
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* Note that this style can produce ambiguous results: the
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* sequence "CRLF" will be treated as a single EOL if it is
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* all in the buffer at once, but if you first read a CR from
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* the network and later read an LF from the network, it will
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* be treated as two EOLs.
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*/
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EVBUFFER_EOL_ANY,
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/** An EOL is an LF, optionally preceded by a CR. This style is
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* most useful for implementing text-based internet protocols. */
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EVBUFFER_EOL_CRLF,
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/** An EOL is a CR followed by an LF. */
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EVBUFFER_EOL_CRLF_STRICT,
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/** An EOL is a LF. */
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EVBUFFER_EOL_LF
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};
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/**
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* Read a single line from an evbuffer.
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*
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* Reads a line terminated by an EOL as determined by the evbuffer_eol_style
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* argument. Returns a newly allocated nul-terminated string; the caller must
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* free the returned value. The EOL is not included in the returned string.
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*
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* @param buffer the evbuffer to read from
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* @param n_read_out if non-NULL, points to a size_t that is set to the
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* number of characters in the returned string. This is useful for
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* strings that can contain NUL characters.
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* @param eol_style the style of line-ending to use.
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* @return pointer to a single line, or NULL if an error occurred
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*/
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char *evbuffer_readln(struct evbuffer *buffer, size_t *n_read_out,
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enum evbuffer_eol_style eol_style);
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/**
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Move all data from one evbuffer into another evbuffer.
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This is a destructive add. The data from one buffer moves into
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the other buffer. However, no unnecessary memory copies occur.
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@param outbuf the output buffer
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@param inbuf the input buffer
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@return 0 if successful, or -1 if an error occurred
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@see evbuffer_remove_buffer()
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*/
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int evbuffer_add_buffer(struct evbuffer *outbuf, struct evbuffer *inbuf);
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/**
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A cleanup function for a piece of memory added to an evbuffer by
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reference.
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@see evbuffer_add_reference()
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*/
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typedef void (*evbuffer_ref_cleanup_cb)(const void *data,
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size_t datalen, void *extra);
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/**
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Reference memory into an evbuffer without copying.
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The memory needs to remain valid until all the added data has been
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read. This function keeps just a reference to the memory without
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actually incurring the overhead of a copy.
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@param outbuf the output buffer
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@param data the memory to reference
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@param datlen how memory to reference
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@param cleanupfn callback to be invoked when the memory is no longer
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referenced by this evbuffer.
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@param cleanupfn_arg optional argument to the cleanup callback
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@return 0 if successful, or -1 if an error occurred
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*/
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int evbuffer_add_reference(struct evbuffer *outbuf,
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const void *data, size_t datlen,
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evbuffer_ref_cleanup_cb cleanupfn, void *cleanupfn_arg);
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/**
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Copy data from a file into the evbuffer for writing to a socket.
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This function avoids unnecessary data copies between userland and
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kernel. If sendfile is available and the EVBUFFER_FLAG_DRAINS_TO_FD
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flag is set, it uses those functions. Otherwise, it tries to use
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mmap (or CreateFileMapping on Windows).
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The function owns the resulting file descriptor and will close it
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when finished transferring data.
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The results of using evbuffer_remove() or evbuffer_pullup() on
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evbuffers whose data was added using this function are undefined.
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@param outbuf the output buffer
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@param fd the file descriptor
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@param offset the offset from which to read data
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@param length how much data to read
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@return 0 if successful, or -1 if an error occurred
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*/
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int evbuffer_add_file(struct evbuffer *outbuf, int fd, ev_off_t offset,
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ev_off_t length);
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/**
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Append a formatted string to the end of an evbuffer.
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The string is formated as printf.
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@param buf the evbuffer that will be appended to
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@param fmt a format string
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@param ... arguments that will be passed to printf(3)
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@return The number of bytes added if successful, or -1 if an error occurred.
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@see evutil_printf(), evbuffer_add_vprintf()
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*/
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int evbuffer_add_printf(struct evbuffer *buf, const char *fmt, ...)
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#ifdef __GNUC__
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__attribute__((format(printf, 2, 3)))
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#endif
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;
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/**
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Append a va_list formatted string to the end of an evbuffer.
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@param buf the evbuffer that will be appended to
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@param fmt a format string
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@param ap a varargs va_list argument array that will be passed to vprintf(3)
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@return The number of bytes added if successful, or -1 if an error occurred.
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*/
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int evbuffer_add_vprintf(struct evbuffer *buf, const char *fmt, va_list ap)
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#ifdef __GNUC__
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__attribute__((format(printf, 2, 0)))
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#endif
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;
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/**
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Remove a specified number of bytes data from the beginning of an evbuffer.
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@param buf the evbuffer to be drained
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@param len the number of bytes to drain from the beginning of the buffer
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@return 0 on success, -1 on failure.
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*/
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int evbuffer_drain(struct evbuffer *buf, size_t len);
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/**
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Write the contents of an evbuffer to a file descriptor.
|
|
|
|
The evbuffer will be drained after the bytes have been successfully written.
|
|
|
|
@param buffer the evbuffer to be written and drained
|
|
@param fd the file descriptor to be written to
|
|
@return the number of bytes written, or -1 if an error occurred
|
|
@see evbuffer_read()
|
|
*/
|
|
int evbuffer_write(struct evbuffer *buffer, evutil_socket_t fd);
|
|
|
|
/**
|
|
Write some of the contents of an evbuffer to a file descriptor.
|
|
|
|
The evbuffer will be drained after the bytes have been successfully written.
|
|
|
|
@param buffer the evbuffer to be written and drained
|
|
@param fd the file descriptor to be written to
|
|
@param howmuch the largest allowable number of bytes to write, or -1
|
|
to write as many bytes as we can.
|
|
@return the number of bytes written, or -1 if an error occurred
|
|
@see evbuffer_read()
|
|
*/
|
|
int evbuffer_write_atmost(struct evbuffer *buffer, evutil_socket_t fd,
|
|
ev_ssize_t howmuch);
|
|
|
|
/**
|
|
Read from a file descriptor and store the result in an evbuffer.
|
|
|
|
@param buffer the evbuffer to store the result
|
|
@param fd the file descriptor to read from
|
|
@param howmuch the number of bytes to be read
|
|
@return the number of bytes read, or -1 if an error occurred
|
|
@see evbuffer_write()
|
|
*/
|
|
int evbuffer_read(struct evbuffer *buffer, evutil_socket_t fd, int howmuch);
|
|
|
|
/**
|
|
Search for a string within an evbuffer.
|
|
|
|
@param buffer the evbuffer to be searched
|
|
@param what the string to be searched for
|
|
@param len the length of the search string
|
|
@param start NULL or a pointer to a valid struct evbuffer_ptr.
|
|
@return a struct evbuffer_ptr whose 'pos' field has the offset of the
|
|
first occurrence of the string in the buffer after 'start'. The 'pos'
|
|
field of the result is -1 if the string was not found.
|
|
*/
|
|
struct evbuffer_ptr evbuffer_search(struct evbuffer *buffer, const char *what, size_t len, const struct evbuffer_ptr *start);
|
|
|
|
/**
|
|
Search for a string within part of an evbuffer.
|
|
|
|
@param buffer the evbuffer to be searched
|
|
@param what the string to be searched for
|
|
@param len the length of the search string
|
|
@param start NULL or a pointer to a valid struct evbuffer_ptr that
|
|
indicates where we should start searching.
|
|
@param end NULL or a pointer to a valid struct evbuffer_ptr that
|
|
indicates where we should stop searching.
|
|
@return a struct evbuffer_ptr whose 'pos' field has the offset of the
|
|
first occurrence of the string in the buffer after 'start'. The 'pos'
|
|
field of the result is -1 if the string was not found.
|
|
*/
|
|
struct evbuffer_ptr evbuffer_search_range(struct evbuffer *buffer, const char *what, size_t len, const struct evbuffer_ptr *start, const struct evbuffer_ptr *end);
|
|
|
|
/**
|
|
Defines how to adjust an evbuffer_ptr by evbuffer_ptr_set()
|
|
|
|
@see evbuffer_ptr_set() */
|
|
enum evbuffer_ptr_how {
|
|
/** Sets the pointer to the position; can be called on with an
|
|
uninitialized evbuffer_ptr. */
|
|
EVBUFFER_PTR_SET,
|
|
/** Advances the pointer by adding to the current position. */
|
|
EVBUFFER_PTR_ADD
|
|
};
|
|
|
|
/**
|
|
Sets the search pointer in the buffer to position.
|
|
|
|
If evbuffer_ptr is not initialized. This function can only be called
|
|
with EVBUFFER_PTR_SET.
|
|
|
|
@param buffer the evbuffer to be search
|
|
@param ptr a pointer to a struct evbuffer_ptr
|
|
@param position the position at which to start the next search
|
|
@param how determines how the pointer should be manipulated.
|
|
@returns 0 on success or -1 otherwise
|
|
*/
|
|
int
|
|
evbuffer_ptr_set(struct evbuffer *buffer, struct evbuffer_ptr *ptr,
|
|
size_t position, enum evbuffer_ptr_how how);
|
|
|
|
/**
|
|
Search for an end-of-line string within an evbuffer.
|
|
|
|
@param buffer the evbuffer to be searched
|
|
@param start NULL or a pointer to a valid struct evbuffer_ptr to start
|
|
searching at.
|
|
@param eol_len_out If non-NULL, the pointed-to value will be set to
|
|
the length of the end-of-line string.
|
|
@param eol_style The kind of EOL to look for; see evbuffer_readln() for
|
|
more information
|
|
@return a struct evbuffer_ptr whose 'pos' field has the offset of the
|
|
first occurrence EOL in the buffer after 'start'. The 'pos'
|
|
field of the result is -1 if the string was not found.
|
|
*/
|
|
struct evbuffer_ptr evbuffer_search_eol(struct evbuffer *buffer,
|
|
struct evbuffer_ptr *start, size_t *eol_len_out,
|
|
enum evbuffer_eol_style eol_style);
|
|
|
|
/** Function to peek at data inside an evbuffer without removing it or
|
|
copying it out.
|
|
|
|
Pointers to the data are returned by filling the 'vec_out' array
|
|
with pointers to one or more extents of data inside the buffer.
|
|
|
|
The total data in the extents that you get back may be more than
|
|
you requested (if there is more data last extent than you asked
|
|
for), or less (if you do not provide enough evbuffer_iovecs, or if
|
|
the buffer does not have as much data as you asked to see).
|
|
|
|
@param buffer the evbuffer to peek into,
|
|
@param len the number of bytes to try to peek. If len is negative, we
|
|
will try to fill as much of vec_out as we can. If len is negative
|
|
and vec_out is not provided, we return the number of evbuffer_iovecs
|
|
that would be needed to get all the data in the buffer.
|
|
@param start_at an evbuffer_ptr indicating the point at which we
|
|
should start looking for data. NULL means, "At the start of the
|
|
buffer."
|
|
@param vec_out an array of evbuffer_iovec
|
|
@param n_vec the length of vec_out. If 0, we only count how many
|
|
extents would be necessary to point to the requested amount of
|
|
data.
|
|
@return The number of extents needed. This may be less than n_vec
|
|
if we didn't need all the evbuffer_iovecs we were given, or more
|
|
than n_vec if we would need more to return all the data that was
|
|
requested.
|
|
*/
|
|
int evbuffer_peek(struct evbuffer *buffer, ev_ssize_t len,
|
|
struct evbuffer_ptr *start_at,
|
|
struct evbuffer_iovec *vec_out, int n_vec);
|
|
|
|
|
|
/** Structure passed to an evbuffer_cb_func evbuffer callback
|
|
|
|
@see evbuffer_cb_func, evbuffer_add_cb()
|
|
*/
|
|
struct evbuffer_cb_info {
|
|
/** The number of bytes in this evbuffer when callbacks were last
|
|
* invoked. */
|
|
size_t orig_size;
|
|
/** The number of bytes added since callbacks were last invoked. */
|
|
size_t n_added;
|
|
/** The number of bytes removed since callbacks were last invoked. */
|
|
size_t n_deleted;
|
|
};
|
|
|
|
/** Type definition for a callback that is invoked whenever data is added or
|
|
removed from an evbuffer.
|
|
|
|
An evbuffer may have one or more callbacks set at a time. The order
|
|
in which they are executed is undefined.
|
|
|
|
A callback function may add more callbacks, or remove itself from the
|
|
list of callbacks, or add or remove data from the buffer. It may not
|
|
remove another callback from the list.
|
|
|
|
If a callback adds or removes data from the buffer or from another
|
|
buffer, this can cause a recursive invocation of your callback or
|
|
other callbacks. If you ask for an infinite loop, you might just get
|
|
one: watch out!
|
|
|
|
@param buffer the buffer whose size has changed
|
|
@param info a structure describing how the buffer changed.
|
|
@param arg a pointer to user data
|
|
*/
|
|
typedef void (*evbuffer_cb_func)(struct evbuffer *buffer, const struct evbuffer_cb_info *info, void *arg);
|
|
|
|
struct evbuffer_cb_entry;
|
|
/** Add a new callback to an evbuffer.
|
|
|
|
Subsequent calls to evbuffer_add_cb() add new callbacks. To remove this
|
|
callback, call evbuffer_remove_cb or evbuffer_remove_cb_entry.
|
|
|
|
@param buffer the evbuffer to be monitored
|
|
@param cb the callback function to invoke when the evbuffer is modified,
|
|
or NULL to remove all callbacks.
|
|
@param cbarg an argument to be provided to the callback function
|
|
@return a handle to the callback on success, or NULL on failure.
|
|
*/
|
|
struct evbuffer_cb_entry *evbuffer_add_cb(struct evbuffer *buffer, evbuffer_cb_func cb, void *cbarg);
|
|
|
|
/** Remove a callback from an evbuffer, given a handle returned from
|
|
evbuffer_add_cb.
|
|
|
|
Calling this function invalidates the handle.
|
|
|
|
@return 0 if a callback was removed, or -1 if no matching callback was
|
|
found.
|
|
*/
|
|
int evbuffer_remove_cb_entry(struct evbuffer *buffer,
|
|
struct evbuffer_cb_entry *ent);
|
|
|
|
/** Remove a callback from an evbuffer, given the function and argument
|
|
used to add it.
|
|
|
|
@return 0 if a callback was removed, or -1 if no matching callback was
|
|
found.
|
|
*/
|
|
int evbuffer_remove_cb(struct evbuffer *buffer, evbuffer_cb_func cb, void *cbarg);
|
|
|
|
/** If this flag is not set, then a callback is temporarily disabled, and
|
|
* should not be invoked.
|
|
*
|
|
* @see evbuffer_cb_set_flags(), evbuffer_cb_clear_flags()
|
|
*/
|
|
#define EVBUFFER_CB_ENABLED 1
|
|
|
|
/** Change the flags that are set for a callback on a buffer by adding more.
|
|
|
|
@param buffer the evbuffer that the callback is watching.
|
|
@param cb the callback whose status we want to change.
|
|
@param flags EVBUFFER_CB_ENABLED to re-enable the callback.
|
|
@return 0 on success, -1 on failure.
|
|
*/
|
|
int evbuffer_cb_set_flags(struct evbuffer *buffer,
|
|
struct evbuffer_cb_entry *cb, ev_uint32_t flags);
|
|
|
|
/** Change the flags that are set for a callback on a buffer by removing some
|
|
|
|
@param buffer the evbuffer that the callback is watching.
|
|
@param cb the callback whose status we want to change.
|
|
@param flags EVBUFFER_CB_ENABLED to disable the callback.
|
|
@return 0 on success, -1 on failure.
|
|
*/
|
|
int evbuffer_cb_clear_flags(struct evbuffer *buffer,
|
|
struct evbuffer_cb_entry *cb, ev_uint32_t flags);
|
|
|
|
#if 0
|
|
/** Postpone calling a given callback until unsuspend is called later.
|
|
|
|
This is different from disabling the callback, since the callback will get
|
|
invoked later if the buffer size changes between now and when we unsuspend
|
|
it.
|
|
|
|
@param the buffer that the callback is watching.
|
|
@param cb the callback we want to suspend.
|
|
*/
|
|
void evbuffer_cb_suspend(struct evbuffer *buffer, struct evbuffer_cb_entry *cb);
|
|
/** Stop postponing a callback that we postponed with evbuffer_cb_suspend.
|
|
|
|
If data was added to or removed from the buffer while the callback was
|
|
suspended, the callback will get called once now.
|
|
|
|
@param the buffer that the callback is watching.
|
|
@param cb the callback we want to stop suspending.
|
|
*/
|
|
void evbuffer_cb_unsuspend(struct evbuffer *buffer, struct evbuffer_cb_entry *cb);
|
|
#endif
|
|
|
|
/**
|
|
Makes the data at the begging of an evbuffer contiguous.
|
|
|
|
@param buf the evbuffer to make contiguous
|
|
@param size the number of bytes to make contiguous, or -1 to make the
|
|
entire buffer contiguous.
|
|
@return a pointer to the contiguous memory array
|
|
*/
|
|
|
|
unsigned char *evbuffer_pullup(struct evbuffer *buf, ev_ssize_t size);
|
|
|
|
/**
|
|
Prepends data to the beginning of the evbuffer
|
|
|
|
@param buf the evbuffer to which to prepend data
|
|
@param data a pointer to the memory to prepend
|
|
@param size the number of bytes to prepend
|
|
@return 0 if successful, or -1 otherwise
|
|
*/
|
|
|
|
int evbuffer_prepend(struct evbuffer *buf, const void *data, size_t size);
|
|
|
|
/**
|
|
Prepends all data from the src evbuffer to the beginning of the dst
|
|
evbuffer.
|
|
|
|
@param dst the evbuffer to which to prepend data
|
|
@param src the evbuffer to prepend; it will be emptied as a result
|
|
@return 0 if successful, or -1 otherwise
|
|
*/
|
|
int evbuffer_prepend_buffer(struct evbuffer *dst, struct evbuffer* src);
|
|
|
|
/**
|
|
Prevent calls that modify an evbuffer from succeeding. A buffer may
|
|
frozen at the front, at the back, or at both the front and the back.
|
|
|
|
If the front of a buffer is frozen, operations that drain data from
|
|
the front of the buffer, or that prepend data to the buffer, will
|
|
fail until it is unfrozen. If the back a buffer is frozen, operations
|
|
that append data from the buffer will fail until it is unfrozen.
|
|
|
|
@param buf The buffer to freeze
|
|
@param at_front If true, we freeze the front of the buffer. If false,
|
|
we freeze the back.
|
|
@return 0 on success, -1 on failure.
|
|
*/
|
|
int evbuffer_freeze(struct evbuffer *buf, int at_front);
|
|
/**
|
|
Re-enable calls that modify an evbuffer.
|
|
|
|
@param buf The buffer to un-freeze
|
|
@param at_front If true, we unfreeze the front of the buffer. If false,
|
|
we unfreeze the back.
|
|
@return 0 on success, -1 on failure.
|
|
*/
|
|
int evbuffer_unfreeze(struct evbuffer *buf, int at_front);
|
|
|
|
struct event_base;
|
|
/**
|
|
Force all the callbacks on an evbuffer to be run, not immediately after
|
|
the evbuffer is altered, but instead from inside the event loop.
|
|
|
|
This can be used to serialize all the callbacks to a single thread
|
|
of execution.
|
|
*/
|
|
int evbuffer_defer_callbacks(struct evbuffer *buffer, struct event_base *base);
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif /* _EVENT2_BUFFER_H_ */
|