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

#include "config.h"

#ifndef lint
static const char sccsid[] = "@(#)os_rw.c       10.11 (Sleepycat) 10/12/98";
#endif /* not lint */

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

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

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

/*
 * __os_io --
 *      Do an I/O.
 *
 * PUBLIC: int __os_io __P((DB_IO *, int, ssize_t *));
 */
int
__os_io(db_iop, op, niop)
        DB_IO *db_iop;
        int op;
        ssize_t *niop;
{
        int ret;

#ifdef HAVE_PREAD
        switch (op) {
        case DB_IO_READ:
                if (__db_jump.j_read != NULL)
                        goto slow;
                *niop = pread(db_iop->fd_io, db_iop->buf,
                    db_iop->bytes, (off_t)db_iop->pgno * db_iop->pagesize);
                break;
        case DB_IO_WRITE:
                if (__db_jump.j_write != NULL)
                        goto slow;
                *niop = pwrite(db_iop->fd_io, db_iop->buf,
                    db_iop->bytes, (off_t)db_iop->pgno * db_iop->pagesize);
                break;
        }
        if (*niop == db_iop->bytes)
                return (0);
slow:
#endif
        if (db_iop->mutexp != NULL)
                (void)__db_mutex_lock(db_iop->mutexp, db_iop->fd_lock);

        if ((ret = __os_seek(db_iop->fd_io,
            db_iop->pagesize, db_iop->pgno, 0, 0, SEEK_SET)) != 0)
                goto err;
        switch (op) {
        case DB_IO_READ:
                ret =
                    __os_read(db_iop->fd_io, db_iop->buf, db_iop->bytes, niop);
                break;
        case DB_IO_WRITE:
                ret =
                    __os_write(db_iop->fd_io, db_iop->buf, db_iop->bytes, niop);
                break;
        }

err:    if (db_iop->mutexp != NULL)
                (void)__db_mutex_unlock(db_iop->mutexp, db_iop->fd_lock);

        return (ret);

}

/*
 * __os_read --
 *      Read from a file handle.
 *
 * PUBLIC: int __os_read __P((int, void *, size_t, ssize_t *));
 */
int
__os_read(fd, addr, len, nrp)
        int fd;
        void *addr;
        size_t len;
        ssize_t *nrp;
{
        size_t offset;
        ssize_t nr;
        u_int8_t *taddr;

        for (taddr = addr,
            offset = 0; offset < len; taddr += nr, offset += nr) {
                if ((nr = __db_jump.j_read != NULL ?
                    __db_jump.j_read(fd, taddr, len - offset) :
                    read(fd, taddr, len - offset)) < 0)
                        return (errno);
                if (nr == 0)
                        break;
        }
        *nrp = taddr - (u_int8_t *)addr;
        return (0);
}

/*
 * __os_write --
 *      Write to a file handle.
 *
 * PUBLIC: int __os_write __P((int, void *, size_t, ssize_t *));
 */
int
__os_write(fd, addr, len, nwp)
        int fd;
        void *addr;
        size_t len;
        ssize_t *nwp;
{
        size_t offset;
        ssize_t nw;
        u_int8_t *taddr;

        for (taddr = addr,
            offset = 0; offset < len; taddr += nw, offset += nw)
                if ((nw = __db_jump.j_write != NULL ?
                    __db_jump.j_write(fd, taddr, len - offset) :
                    write(fd, taddr, len - offset)) < 0)
                        return (errno);
        *nwp = len;
        return (0);
}