libast/disc/sfdcdio.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1985-2012 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                 Eclipse Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*          http://www.eclipse.org/org/documents/epl-v10.html           *
*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#include    "sfdchdr.h"

/*  Discipline to turn on direct IO capability.
**  This currently only works for XFS on SGI's.
**
**  Written by Kiem-Phong Vo, kpv@research.att.com, 03/18/1998.
*/

#ifndef FDIRECT
#undef F_DIOINFO
#endif

typedef struct _direct_s
{   Sfdisc_t    disc;   /* Sfio discipline  */
    int     cntl;   /* file control flags   */
#ifdef F_DIOINFO
    struct dioattr  dio;    /* direct IO params */
#endif
} Direct_t;

/* convert a pointer to an int */
#define P2I(p)  (Sfulong_t)((char*)(p) - (char*)0)

#if __STD_C
static ssize_t diordwr(Sfio_t* f, Void_t* buf, size_t n, Direct_t* di, int type)
#else
static ssize_t diordwr(f, buf, n, di, type)
Sfio_t*     f;
Void_t*     buf;
size_t      n;
Direct_t*   di;
int     type;
#endif
{
    size_t  rw, done;
    ssize_t rv;

    done = 0;   /* amount processed by direct IO */
    rv = 0;

#ifdef F_DIOINFO
    if((P2I(buf)%di->dio.d_mem) == 0 &&
       (f->here%di->dio.d_miniosz) == 0 && n >= di->dio.d_miniosz )
    {   /* direct IO ok, make sure we're in the right mode */
        if(!(di->cntl & FDIRECT) )
        {   di->cntl |= FDIRECT;
            (void)fcntl(f->file, F_SETFL, di->cntl);
        }

        for(rw = (n/di->dio.d_miniosz)*di->dio.d_miniosz;; )
        {   size_t  io;

            if((io = rw) > di->dio.d_maxiosz )
                io = di->dio.d_maxiosz;
            if(type == SF_READ)
                rv = read(f->file,buf,io);
            else    rv = write(f->file,buf,io);

            if(rv > 0)
            {   rw -= rv; done += rv;
                buf = (Void_t*)((char*)buf + rv);
            }

            if(rv < io || rw < di->dio.d_miniosz)
                break;
        }
    }

    if(done < n && (di->cntl & FDIRECT) )
    {   /* turn off directIO for remaining IO operation */
        di->cntl &= ~FDIRECT;
        (void)fcntl(f->file, F_SETFL, di->cntl);
    }
#endif /*F_DIOINFO*/

    if((rw = n-done) > 0 &&
       (rv = type == SF_READ ? read(f->file,buf,rw) : write(f->file,buf,rw)) > 0 )
        done += rv;

    return done ? done : rv;
}

#if __STD_C
static ssize_t dioread(Sfio_t* f, Void_t* buf, size_t n, Sfdisc_t* disc)
#else
static ssize_t dioread(f, buf, n, disc)
Sfio_t*     f;
Void_t*     buf;
size_t      n;
Sfdisc_t*   disc;
#endif
{
    return diordwr(f, buf, n, (Direct_t*)disc, SF_READ);
}

#if __STD_C
static ssize_t diowrite(Sfio_t* f, const Void_t* buf, size_t n, Sfdisc_t* disc)
#else
static ssize_t diowrite(f, buf, n, disc)
Sfio_t*     f;
Void_t*     buf;
size_t      n;
Sfdisc_t*   disc;
#endif
{
    return diordwr(f, (Void_t*)buf, n, (Direct_t*)disc, SF_WRITE);
}

#if __STD_C
static int dioexcept(Sfio_t* f, int type, Void_t* data, Sfdisc_t* disc)
#else
static int dioexcept(f,type,data,disc)
Sfio_t*     f;
int     type;
Void_t*     data;
Sfdisc_t*   disc;
#endif
{
    Direct_t*   di = (Direct_t*)disc;

    if(type == SF_FINAL || type == SF_DPOP)
    {
#ifdef F_DIOINFO
        if(di->cntl&FDIRECT)
        {   di->cntl &= ~FDIRECT;
            (void)fcntl(f->file,F_SETFL,di->cntl);
        }
#endif
        free(disc);
    }

    return 0;
}

#if __STD_C
int sfdcdio(Sfio_t* f, size_t bufsize)
#else
int sfdcdio(f, bufsize)
Sfio_t* f;
size_t  bufsize;
#endif
{
#ifndef F_DIOINFO
    return -1;
#else
    int     cntl;
    struct dioattr  dio;
    Void_t*     buf;
    Direct_t*   di;

    if(f->extent < 0 || (f->flags&SF_STRING))
        return -1;

    if((cntl = fcntl(f->file,F_GETFL,0)) < 0)
        return -1;

    if(!(cntl&FDIRECT) )
    {   cntl |= FDIRECT;
        if(fcntl(f->file,F_SETFL,cntl) < 0)
            return -1;
    }

    if(fcntl(f->file,F_DIOINFO,&dio) < 0)
        goto no_direct;

    if(bufsize > 0)
        bufsize = (bufsize/dio.d_miniosz)*dio.d_miniosz;
    if(bufsize <= 0)
        bufsize = dio.d_miniosz*64;
    if(bufsize > dio.d_maxiosz)
        bufsize = dio.d_maxiosz;

    if(!(di = (Direct_t*)malloc(sizeof(Direct_t))) )
        goto no_direct;

    if(!(buf = (Void_t*)memalign(dio.d_mem,bufsize)) )
    {   free(di);
        goto no_direct;
    }

    sfsetbuf(f,buf,bufsize);
    if(sfsetbuf(f,buf,0) == buf)
        sfset(f,SF_MALLOC,1);
    else
    {   free(buf);
        free(di);
        goto no_direct;
    }

    di->disc.readf = dioread;
    di->disc.writef = diowrite;
    di->disc.seekf = NIL(Sfseek_f);
    di->disc.exceptf = dioexcept;
    di->cntl = cntl;
    di->dio = dio;

    if(sfdisc(f,(Sfdisc_t*)di) != (Sfdisc_t*)di)
    {   free(di);
    no_direct:
        cntl &= ~FDIRECT;
        (void)fcntl(f->file,F_SETFL,cntl);
        return -1;
    }

    return 0;

#endif /*F_DIOINFO*/
}