/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2010 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* 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 "sfhdr.h"
/* Write with discipline.
**
** Written by Kiem-Phong Vo.
*/
/* hole preserving writes */
#if __STD_C
static ssize_t sfoutput(Sfio_t* f, char* buf, size_t n)
#else
static ssize_t sfoutput(f,buf,n)
Sfio_t* f;
char* buf;
size_t n;
#endif
{ reg char *sp, *wbuf, *endbuf;
reg ssize_t s, w, wr;
s = w = 0;
wbuf = buf;
endbuf = buf+n;
while(n > 0)
{ if((ssize_t)n < _Sfpage) /* no hole possible */
{ buf += n;
s = n = 0;
}
else while((ssize_t)n >= _Sfpage)
{ /* see if a hole of 0's starts here */
sp = buf+1;
if(buf[0] == 0 && buf[_Sfpage-1] == 0)
{ /* check byte at a time until int-aligned */
while(((ulong)sp)%sizeof(int))
{ if(*sp != 0)
goto chk_hole;
sp += 1;
}
/* check using int to speed up */
while(sp < endbuf)
{ if(*((int*)sp) != 0)
goto chk_hole;
sp += sizeof(int);
}
/* check the remaining bytes */
if(sp > endbuf)
{ sp -= sizeof(int);
while(sp < endbuf)
{ if(*sp != 0)
goto chk_hole;
sp += 1;
}
}
}
chk_hole:
if((s = sp-buf) >= _Sfpage) /* found a hole */
break;
/* skip a dirty page */
n -= _Sfpage;
buf += _Sfpage;
}
/* write out current dirty pages */
if(buf > wbuf)
{ if((ssize_t)n < _Sfpage)
{ buf = endbuf;
n = s = 0;
}
if((wr = syswritef(f->file,wbuf,buf-wbuf)) > 0)
{ w += wr;
f->bits &= ~SF_HOLE;
}
if(wr != (buf-wbuf))
break;
wbuf = buf;
}
/* seek to a rounded boundary within the hole */
if(s >= _Sfpage)
{ s = (s/_Sfpage)*_Sfpage;
if(SFSK(f,(Sfoff_t)s,SEEK_CUR,NIL(Sfdisc_t*)) < 0)
break;
w += s;
n -= s;
wbuf = (buf += s);
f->bits |= SF_HOLE;
if(n > 0)
{ /* next page must be dirty */
s = (ssize_t)n <= _Sfpage ? 1 : _Sfpage;
buf += s;
n -= s;
}
}
}
return w > 0 ? w : -1;
}
#if __STD_C
ssize_t sfwr(Sfio_t* f, const Void_t* buf, size_t n, Sfdisc_t* disc)
#else
ssize_t sfwr(f,buf,n,disc)
Sfio_t* f;
Void_t* buf;
size_t n;
Sfdisc_t* disc;
#endif
{
reg ssize_t w;
reg Sfdisc_t* dc;
reg int local, oerrno;
SFMTXDECL(f);
SFMTXENTER(f,(ssize_t)(-1));
GETLOCAL(f,local);
if(!local && !(f->bits&SF_DCDOWN)) /* an external user's call */
{ if(f->mode != SF_WRITE && _sfmode(f,SF_WRITE,0) < 0 )
SFMTXRETURN(f, (ssize_t)(-1));
if(f->next > f->data && SFSYNC(f) < 0 )
SFMTXRETURN(f, (ssize_t)(-1));
}
for(;;)
{ /* stream locked by sfsetfd() */
if(!(f->flags&SF_STRING) && f->file < 0)
SFMTXRETURN(f,(ssize_t)0);
/* clear current error states */
f->flags &= ~(SF_EOF|SF_ERROR);
dc = disc;
if(f->flags&SF_STRING) /* total required buffer */
w = n + (f->next - f->data);
else
{ /* warn that a write is about to happen */
SFDISC(f,dc,writef);
if(dc && dc->exceptf && (f->flags&SF_IOCHECK) )
{ reg int rv;
if(local)
SETLOCAL(f);
if((rv = _sfexcept(f,SF_WRITE,n,dc)) > 0)
n = rv;
else if(rv < 0)
{ f->flags |= SF_ERROR;
SFMTXRETURN(f, rv);
}
}
if(f->extent >= 0)
{ /* make sure we are at the right place to write */
if(f->flags&SF_APPENDWR)
{ if(f->here != f->extent || (f->flags&SF_SHARE))
{ f->here = SFSK(f,(Sfoff_t)0,SEEK_END,dc);
f->extent = f->here;
}
}
else if((f->flags&SF_SHARE) && !(f->flags&SF_PUBLIC))
f->here = SFSK(f,f->here,SEEK_SET,dc);
}
oerrno = errno;
errno = 0;
if(dc && dc->writef)
{ SFDCWR(f,buf,n,dc,w);
}
else if(SFISNULL(f))
w = n;
else if(f->flags&SF_WHOLE)
goto do_write;
else if((ssize_t)n >= _Sfpage &&
!(f->flags&(SF_SHARE|SF_APPENDWR)) &&
f->here == f->extent && (f->here%_Sfpage) == 0)
{ if((w = sfoutput(f,(char*)buf,n)) <= 0)
goto do_write;
}
else
{
do_write:
if((w = syswritef(f->file,buf,n)) > 0)
f->bits &= ~SF_HOLE;
}
if(errno == 0)
errno = oerrno;
if(w > 0)
{ if(!(f->bits&SF_DCDOWN) )
{ if((f->flags&(SF_APPENDWR|SF_PUBLIC)) && f->extent >= 0 )
f->here = SFSK(f,(Sfoff_t)0,SEEK_CUR,dc);
else f->here += w;
if(f->extent >= 0 && f->here > f->extent)
f->extent = f->here;
}
SFMTXRETURN(f, (ssize_t)w);
}
}
if(local)
SETLOCAL(f);
switch(_sfexcept(f,SF_WRITE,w,dc))
{
case SF_ECONT :
goto do_continue;
case SF_EDONE :
w = local ? 0 : w;
SFMTXRETURN(f, (ssize_t)w);
case SF_EDISC :
if(!local && !(f->flags&SF_STRING))
goto do_continue;
/* else fall thru */
case SF_ESTACK :
SFMTXRETURN(f, (ssize_t)(-1));
}
do_continue:
for(dc = f->disc; dc; dc = dc->disc)
if(dc == disc)
break;
disc = dc;
}
}