/*

 * Copyright (c) 2020 Red Hat, Inc.

 *

 * 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 2

 * 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, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA. 

 *

 * $Id: //eng/uds-releases/jasper/src/uds/bufferedReader.h#3 $

 */

#ifndef BUFFERED_READER_H

#define BUFFERED_READER_H 1

#include "common.h"

#ifdef __KERNEL__

struct dm_bufio_client;

struct ioFactory;

#else

struct ioRegion;

#endif

/**

 * The buffered reader allows efficient IO for IORegions, which may be

 * file- or block-based. The internal buffer always reads aligned data

 * from the underlying region.

 **/

typedef struct bufferedReader BufferedReader;

#ifdef __KERNEL__

/**

 * Make a new buffered reader.

 *

 * @param factory     The IOFactory creating the buffered reader.

 * @param client      The dm_bufio_client to read from.

 * @param blockLimit  The number of blocks that may be read.

 * @param readerPtr   The pointer to hold the newly allocated buffered reader

 *

 * @return UDS_SUCCESS or error code.

 **/

int makeBufferedReader(struct ioFactory        *factory,

                       struct dm_bufio_client  *client,

                       sector_t                 blockLimit,

                       BufferedReader         **readerPtr)

  __attribute__((warn_unused_result));

#else

/**

 * Make a new buffered reader.

 *

 * @param region     An IORegion to read from.

 * @param readerPtr  The pointer to hold the newly allocated buffered reader.

 *

 * @return UDS_SUCCESS or error code.

 **/

int makeBufferedReader(struct ioRegion *region, BufferedReader **readerPtr)

  __attribute__((warn_unused_result));

#endif

/**

 * Free a buffered reader.

 *

 * @param reader        The buffered reader

 **/

void freeBufferedReader(BufferedReader *reader);

/**

 * Retrieve data from a buffered reader, reading from the region when needed.

 *

 * @param reader        The buffered reader

 * @param data          The buffer to read data into

 * @param length        The length of the data to read

 *

 * @return UDS_SUCCESS or an error code.

 **/

int readFromBufferedReader(BufferedReader *reader, void *data, size_t length)

  __attribute__((warn_unused_result));

/**

 * Verify that the data currently in the buffer matches the required value.

 *

 * @param reader        The buffered reader.

 * @param value         The value that must match the buffer contents.

 * @param length        The length of the value that must match.

 *

 * @return UDS_SUCCESS or an error code, specifically UDS_CORRUPT_FILE

 *         if the required value fails to match.

 *

 * @note If the value matches, the matching contents are consumed. However,

 *       if the match fails, any buffer contents are left as is.

 **/

int verifyBufferedData(BufferedReader *reader,

                       const void     *value,

                       size_t          length)

  __attribute__((warn_unused_result));

#endif // BUFFERED_READER_H