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/*
API for reading packets using fixed and dynamic buffer
Copyright (C) Amitay Isaacs 2015
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __CTDB_PKT_READ_H__
#define __CTDB_PKT_READ_H__
#include <talloc.h>
#include <tevent.h>
/**
* @file pkt_read.h
*
* @brief Read a packet using fixed size buffer or allocated memory.
*
* CTDB communication uses lots of small packets. This abstraction avoids the
* need to allocate memory for small packets. Only if the received packet is
* larger than the fixed memory buffer, use talloc to allocate memory.
*/
/**
* @brief Start async computation to read a packet
*
* This returns a tevent request to read a packet from given fd. The fd
* should be nonblocking. Freeing this request will free all the memory
* associated with the request.
*
* @param[in] mem_ctx Talloc memory context
* @param[in] ev Tevent context
* @param[in] fd The non-blocking file/socket descriptor to read from
* @param[in] initial Initial amount of data to read
* @param[in] buf The static buffer to read data in
* @param[in] buflen The size of the static buffer
* @param[in] more The function to check if the bytes read forms a packet
* @param[in] private_data Private data to pass to more function
* @return new tevent request or NULL on failure
*/
struct tevent_req *pkt_read_send(TALLOC_CTX *mem_ctx,
struct tevent_context *ev,
int fd, size_t initial,
uint8_t *buf, size_t buflen,
ssize_t (*more)(uint8_t *buf,
size_t buflen,
void *private_data),
void *private_data);
/**
* @brief Function to actually read data from the socket
*
* This function should be called, when tevent fd event is triggered. This
* function has the syntax of tevent_fd_handler_t. The private_data for this
* function is the tevent request created by pkt_read_send function.
*
* @param[in] ev Tevent context
* @param[in] fde Tevent fd context
* @param[in] flags Tevent fd flags
* @param[in] req The active tevent request
*/
void pkt_read_handler(struct tevent_context *ev, struct tevent_fd *fde,
uint16_t flags, struct tevent_req *req);
/**
* @brief Retrieve a packet
*
* This function returns the pkt read from fd.
*
* @param[in] req Tevent request
* @param[in] mem_ctx Talloc memory context
* @param[out] pbuf The pointer to the buffer
* @param[out] free_buf Boolean to indicate that caller should free buffer
* @param[out] perrno errno in case of failure
* @return the size of the pkt, or -1 on failure
*
* If the pkt data is dynamically allocated, then it is moved under the
* specified talloc memory context and free_buf is set to true. It is the
* responsibility of the caller to the free the memory returned.
*
* If the pkt data is stored in the fixed buffer, then free_buf is set to false.
*/
ssize_t pkt_read_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
uint8_t **pbuf, bool *free_buf, int *perrno);
#endif /* __CTDB_PKT_READ_H__ */
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