/*

 * 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/vdo-releases/aluminum/src/c++/vdo/kernel/bioIterator.h#1 $

 */

#ifndef BIO_ITERATOR_H

#define BIO_ITERATOR_H

#include <linux/bio.h>

#include "bio.h"

#include "kernelTypes.h"

typedef struct {

  BIO              *bio;

#ifdef USE_BI_ITER

  struct bvec_iter  iter;

  // Needed so we can store the return value of bio_iter_iovec.

  struct bio_vec    temp;

#else

  int               index;

#endif

} BioIterator;

/**

 * Create an iterator over a bio's data.

 *

 * @param bio   The bio to iterate over

 *

 * @return An iterator over a bio

 **/

static BioIterator createBioIterator(BIO *bio)

{

  BioIterator iterator = {

    .bio   = bio,

#ifdef USE_BI_ITER

    .iter  = bio->bi_iter,

#else

    .index = bio->bi_idx,

#endif

  };

  return iterator;

}

/**

 * Get the next biovec from the iterator, or NULL if there are no more.

 *

 * @param iterator      The iterator from which to get data

 *

 * @return The next biovec from the iterator, or NULL.

 **/

static struct bio_vec *getNextBiovec(BioIterator *iterator)

{

  BIO *bio = iterator->bio;

#ifdef USE_BI_ITER

  if (iterator->iter.bi_size == 0) {

    return NULL;

  }

  iterator->temp = bio_iter_iovec(bio, iterator->iter);

  return &iterator->temp;

#else

  if (iterator->index >= bio->bi_vcnt) {

    return NULL;

  }

  return bio_iovec_idx(bio, iterator->index);

#endif

}

/**

 * Advance the iterator to the next biovec in the bio.

 *

 * @param [in,out] iterator     The iterator to advance

 **/

static void advanceBioIterator(BioIterator *iterator)

{

#ifdef USE_BI_ITER

  bio_advance_iter(iterator->bio, &iterator->iter, iterator->temp.bv_len);

#else

  iterator->index++;

#endif

}

#endif /* BIO_ITERATOR_H */