backends/flint/flint_io.h

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/* Copyright (C) 2006,2007,2008,2009 Olly Betts
 *
 * 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 St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#ifndef XAPIAN_INCLUDED_FLINT_IO_H
#define XAPIAN_INCLUDED_FLINT_IO_H

#include <sys/types.h>
#include "safefcntl.h"
#include "safeunistd.h"

inline bool flint_io_sync(int fd)
{
#ifdef F_FULLFSYNC
    /* Only supported on Mac OS X (at the time of writing at least).
     *
     * This call ensures that data has actually been written to disk, not just
     * to the drive's write cache, so it provides better protection from power
     * failures, etc.  It does take longer though.
     *
     * According to the sqlite sources, this shouldn't fail on a local FS so
     * a failure means that the file system doesn't support this operation and
     * therefore it's best to fallback to fdatasync()/fsync().
     */
    if (fcntl(fd, F_FULLFSYNC, 0) == 0)
        return true;
#endif

#if defined HAVE_FDATASYNC
    // If we have it, prefer fdatasync() over fsync() as the former avoids
    // updating the access time so is probably a little more efficient.
    return fdatasync(fd) == 0;
#elif defined HAVE_FSYNC
    return fsync(fd) == 0;
#elif defined __WIN32__
    return _commit(fd) == 0;
#else
# error Cannot implement flint_io_sync() without fdatasync(), fsync(), or _commit()
#endif
}

size_t flint_io_read(int fd, char * p, size_t n, size_t min);

void flint_io_write(int fd, const char * p, size_t n);

#endif

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