osd-contiki/core/cfs/cfs-coffee.h
2016-04-29 08:07:27 +02:00

147 lines
5 KiB
C

/*
* Copyright (c) 2008, Swedish Institute of Computer Science
* All rights reserved.
*
* 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. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE OR CONTRIBUTORS 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.
*
* This file is part of the Contiki operating system.
*
*/
/**
* \addtogroup cfs
* @{
*/
#ifndef CFS_COFFEE_H
#define CFS_COFFEE_H
#include "cfs.h"
/**
* Instruct Coffee that the access pattern to this file is adapted to
* flash I/O semantics by design, and Coffee should therefore not
* invoke its own micro logs when file modifications occur.
*
* This semantical I/O setting is useful when implementing flash storage
* algorithms such as database indices on top of Coffee.
*
* \sa cfs_coffee_set_io_semantics()
*/
#define CFS_COFFEE_IO_FLASH_AWARE 0x1
/**
* Instruct Coffee not to attempt to extend the file upon a request
* to write past the reserved file size.
*
* A case when this is necessary is when the file has a firm size limit,
* and a safeguard is needed to protect against writes beyond this limit.
*
* \sa cfs_coffee_set_io_semantics()
*/
#define CFS_COFFEE_IO_FIRM_SIZE 0x2
/**
* Instruct Coffee to set unused bytes in the destination buffer to zero.
* Trailing zeros may cause a wrong file size, this option ensures that
* the corresponding bytes get set, so Coffee does not read unexpected data.
*
* \sa cfs_coffee_set_io_semantics()
*/
#define CFS_COFFEE_IO_ENSURE_READ_LENGTH 0x4
/**
* \file
* Header for the Coffee file system.
* \author
* Nicolas Tsiftes <nvt@sics.se>
*
* \name Functions called from application programs
* @{
*/
/**
* \brief Reserve space for a file.
* \param name The file name.
* \param size The initial size to be reserved for the file.
* \return 0 on success, -1 on failure.
*
* Coffee uses sequential page structures for files. The sequential
* structure can be reserved with a certain size. If a file has not
* been reserved when it is opened for the first time, it will be
* allocated with a default size.
*/
int cfs_coffee_reserve(const char *name, cfs_offset_t size);
/**
* \brief Configure the on-demand log file.
* \param file The file name.
* \param log_size The total log file size.
* \param log_entry_size The log entry size.
* \return 0 on success, -1 on failure.
*
* When file data is first modified, Coffee creates a micro log for the
* file. The micro log stores a table of modifications whose parameters --
* the log size and the log entry size -- can be modified through the
* cfs_coffee_configure_log function.
*/
int cfs_coffee_configure_log(const char *file, unsigned log_size,
unsigned log_entry_size);
/**
* \brief Set the I/O semantics for accessing a file.
*
* \param fd The file descriptor through which the file is accessed.
* \param flags A bit vector of flags.
*
* Coffee is used on a wide range of storage types, and the default
* I/O file semantics may not be optimal for the access pattern
* of a certain file. Hence, this function allows programmers to
* switch the I/O semantics on a file that is accessed through a
* particular file descriptor.
*
*/
int cfs_coffee_set_io_semantics(int fd, unsigned flags);
/**
* \brief Format the storage area assigned to Coffee.
* \return 0 on success, -1 on failure.
*
* Coffee formats the underlying storage by setting all bits to zero.
* Formatting must be done before using Coffee for the first time in
* a mote.
*
* Notice that the erased bits may be set to 1 on the physical storage
* when using flash memory. In this case, Coffee requires that the
* COFFEE_READ and COFFEE_WRITE functions used to access the flash memory
* invert all bits.
*/
int cfs_coffee_format(void);
/** @} */
/** @} */
#endif /* !COFFEE_H */