os_seek.c

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/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997, 1998, 1999, 2000
 *      Sleepycat Software.  All rights reserved.
 */

#include "config.h"

#ifndef lint
static const char revid[] = "$Id: os__seek_8c-source.html,v 1.1 2008/06/08 10:21:30 sebdiaz Exp $";
#endif /* not lint */

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#endif

#include "db_int.h"
#include "os_jump.h"

/*
 * CDB___os_seek --
 *      Seek to a page/byte offset in the file.
 *
 * PUBLIC: int CDB___os_seek __P((DB_ENV *,
 * PUBLIC:      DB_FH *, size_t, db_pgno_t, u_int32_t, int, DB_OS_SEEK));
 */
int
CDB___os_seek(dbenv, fhp, pgsize, pageno, relative, isrewind, db_whence)
        DB_ENV *dbenv;
        DB_FH *fhp;
        size_t pgsize;
        db_pgno_t pageno;
        u_int32_t relative;
        int isrewind;
        DB_OS_SEEK db_whence;
{
        off_t offset;
        int ret, whence;

        switch (db_whence) {
        case DB_OS_SEEK_CUR:
                whence = SEEK_CUR;
                break;
        case DB_OS_SEEK_END:
                whence = SEEK_END;
                break;
        case DB_OS_SEEK_SET:
                whence = SEEK_SET;
                break;
        default:
                return (EINVAL);
        }

        if (CDB___db_jump.j_seek != NULL)
                ret = CDB___db_jump.j_seek(fhp->fd,
                    pgsize, pageno, relative, isrewind, whence);
        else {
                offset = (off_t)pgsize * pageno + relative;
                if (isrewind)
                        offset = -offset;
                ret =
                    lseek(fhp->fd, offset, whence) == -1 ? CDB___os_get_errno() : 0;
        }

        if (ret != 0)
                CDB___db_err(dbenv, "seek: %lu %d %d: %s",
                    (u_long)pgsize * pageno + relative,
                    isrewind, db_whence, strerror(ret));

        return (ret);
}

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