db/os/os_rw.c

	os_rw.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*-
 * 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);
}