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/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2009 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"
/* Move data from one stream to another.
** This code is written so that it'll work even in the presence
** of stacking streams, pool, and discipline.
** If you must change it, be gentle.
**
** Written by Kiem-Phong Vo.
*/
#define MAX_SSIZE ((ssize_t)((~((size_t)0)) >> 1))
#if __STD_C
Sfoff_t sfmove(Sfio_t* fr, Sfio_t* fw, Sfoff_t n, reg int rc)
#else
Sfoff_t sfmove(fr,fw,n,rc)
Sfio_t* fr; /* moving data from this stream */
Sfio_t* fw; /* moving data to this stream */
Sfoff_t n; /* number of bytes/records to move. <0 for unbounded move */
reg int rc; /* record separator */
#endif
{
reg uchar *cp, *next;
reg ssize_t r, w;
reg uchar *endb;
reg int direct;
Sfoff_t n_move, sk, cur;
uchar *rbuf = NIL(uchar*);
ssize_t rsize = 0;
SFMTXDECL(fr);
SFMTXDECL2(fw);
SFMTXENTER(fr, (Sfoff_t)0);
if(fw)
SFMTXBEGIN2(fw, (Sfoff_t)0);
for(n_move = 0; n != 0; )
{
if(rc >= 0) /* moving records, let sfgetr() deal with record reading */
{ if(!(cp = (uchar*)sfgetr(fr,rc,0)) )
n = 0;
else
{ r = sfvalue(fr);
if(fw && (w = SFWRITE(fw, cp, r)) != r)
{ if(fr->extent >= 0 )
(void)SFSEEK(fr,(Sfoff_t)(-r),SEEK_CUR);
if(fw->extent >= 0 && w > 0)
(void)SFSEEK(fw,(Sfoff_t)(-w),SEEK_CUR);
n = 0;
}
else
{ n_move += 1;
if(n > 0)
n -= 1;
}
}
continue;
}
/* get the streams into the right mode */
if(fr->mode != SF_READ && _sfmode(fr,SF_READ,0) < 0)
break;
SFLOCK(fr,0);
/* flush the write buffer as necessary to make room */
if(fw)
{ if(fw->mode != SF_WRITE && _sfmode(fw,SF_WRITE,0) < 0 )
break;
SFLOCK(fw,0);
if(fw->next >= fw->endb ||
(fw->next > fw->data && fr->extent < 0 &&
(fw->extent < 0 || (fw->flags&SF_SHARE)) ) )
if(SFFLSBUF(fw,-1) < 0 )
break;
}
else if((cur = SFSEEK(fr, (Sfoff_t)0, SEEK_CUR)) >= 0 )
{ sk = n > 0 ? SFSEEK(fr, n, SEEK_CUR) : SFSEEK(fr, 0, SEEK_END);
if(sk > cur) /* safe to skip over data in current stream */
{ n_move += sk - cur;
if(n > 0)
n -= sk - cur;
continue;
}
/* else: stream unstacking may happen below */
}
/* about to move all, set map to a large amount */
if(n < 0 && (fr->bits&SF_MMAP) && !(fr->bits&SF_MVSIZE) )
{ SFMVSET(fr);
fr->bits |= SF_SEQUENTIAL; /* sequentially access data */
}
/* try reading a block of data */
direct = 0;
if((r = fr->endb - (next = fr->next)) <= 0)
{ /* amount of data remained to be read */
if((w = n > MAX_SSIZE ? MAX_SSIZE : (ssize_t)n) < 0)
{ if(fr->extent < 0)
w = fr->data == fr->tiny ? SF_GRAIN : fr->size;
else if((fr->extent-fr->here) > SF_NMAP*SF_PAGE)
w = SF_NMAP*SF_PAGE;
else w = (ssize_t)(fr->extent-fr->here);
}
/* use a decent buffer for data transfer but make sure
that if we overread, the left over can be retrieved
*/
if(!(fr->flags&SF_STRING) && !(fr->bits&SF_MMAP) &&
(n < 0 || fr->extent >= 0) )
{ reg ssize_t maxw = 4*(_Sfpage > 0 ? _Sfpage : SF_PAGE);
/* direct transfer to a seekable write stream */
if(fw && fw->extent >= 0 && w <= (fw->endb-fw->next) )
{ w = fw->endb - (next = fw->next);
direct = SF_WRITE;
}
else if(w > fr->size && maxw > fr->size)
{ /* making our own buffer */
if(w >= maxw)
w = maxw;
else w = ((w+fr->size-1)/fr->size)*fr->size;
if(rsize <= 0 && (rbuf = (uchar*)malloc(w)) )
rsize = w;
if(rbuf)
{ next = rbuf;
w = rsize;
direct = SF_STRING;
}
}
}
if(!direct)
{ /* make sure we don't read too far ahead */
if(n > 0 && fr->extent < 0 && (fr->flags&SF_SHARE) )
{ if((Sfoff_t)(r = fr->size) > n)
r = (ssize_t)n;
}
else r = -1;
if((r = SFFILBUF(fr,r)) <= 0)
break;
next = fr->next;
}
else
{ /* actual amount to be read */
if(n > 0 && n < w)
w = (ssize_t)n;
if((r = SFRD(fr,next,w,fr->disc)) > 0)
fr->next = fr->endb = fr->endr = fr->data;
else if(r == 0)
break; /* eof */
else goto again; /* popped stack */
}
}
/* compute the extent of data to be moved */
endb = next+r;
if(n > 0)
{ if(r > n)
r = (ssize_t)n;
n -= r;
}
n_move += r;
cp = next+r;
if(!direct)
fr->next += r;
else if((w = endb-cp) > 0)
{ /* move left-over to read stream */
if(w > fr->size)
w = fr->size;
memcpy((Void_t*)fr->data,(Void_t*)cp,w);
fr->endb = fr->data+w;
if((w = endb - (cp+w)) > 0)
(void)SFSK(fr,(Sfoff_t)(-w),SEEK_CUR,fr->disc);
}
if(fw)
{ if(direct == SF_WRITE)
fw->next += r;
else if(r <= (fw->endb-fw->next) )
{ memcpy((Void_t*)fw->next,(Void_t*)next,r);
fw->next += r;
}
else if((w = SFWRITE(fw,(Void_t*)next,r)) != r)
{ /* a write error happened */
if(w > 0)
{ r -= w;
n_move -= r;
}
if(fr->extent >= 0)
(void)SFSEEK(fr,(Sfoff_t)(-r),SEEK_CUR);
break;
}
}
again:
SFOPEN(fr,0);
if(fw)
SFOPEN(fw,0);
}
if(n < 0 && (fr->bits&SF_MMAP) && (fr->bits&SF_MVSIZE))
{ /* back to normal access mode */
SFMVUNSET(fr);
if((fr->bits&SF_SEQUENTIAL) && (fr->data))
SFMMSEQOFF(fr,fr->data,fr->endb-fr->data);
fr->bits &= ~SF_SEQUENTIAL;
}
if(rbuf)
free(rbuf);
if(fw)
{ SFOPEN(fw,0);
SFMTXEND2(fw);
}
SFOPEN(fr,0);
SFMTXRETURN(fr, n_move);
}
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