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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"
/* Read n bytes from a stream into a buffer
**
** Written by Kiem-Phong Vo.
*/
#if __STD_C
ssize_t sfread(Sfio_t* f, Void_t* buf, size_t n)
#else
ssize_t sfread(f,buf,n)
Sfio_t* f; /* read from this stream. */
Void_t* buf; /* buffer to read into */
size_t n; /* number of bytes to be read. */
#endif
{
reg uchar *s, *begs;
reg ssize_t r;
reg int local, justseek;
SFMTXDECL(f);
SFMTXENTER(f, (ssize_t)(-1));
GETLOCAL(f,local);
justseek = f->bits&SF_JUSTSEEK; f->bits &= ~SF_JUSTSEEK;
if(!buf)
SFMTXRETURN(f, (ssize_t)(n == 0 ? 0 : -1) );
/* release peek lock */
if(f->mode&SF_PEEK)
{ if(!(f->mode&SF_READ) )
SFMTXRETURN(f, (ssize_t)(-1));
if(f->mode&SF_GETR)
{ if(((uchar*)buf + f->val) != f->next &&
(!f->rsrv || f->rsrv->data != (uchar*)buf) )
SFMTXRETURN(f, (ssize_t)(-1));
f->mode &= ~SF_PEEK;
SFMTXRETURN(f, 0);
}
else
{ if((uchar*)buf != f->next)
SFMTXRETURN(f, (ssize_t)(-1));
f->mode &= ~SF_PEEK;
if(f->mode&SF_PKRD)
{ /* actually read the data now */
f->mode &= ~SF_PKRD;
if(n > 0)
n = (r = sysreadf(f->file,f->data,n)) < 0 ? 0 : r;
f->endb = f->data+n;
f->here += n;
}
f->next += n;
f->endr = f->endb;
SFMTXRETURN(f, n);
}
}
s = begs = (uchar*)buf;
for(;; f->mode &= ~SF_LOCK)
{ /* check stream mode */
if(SFMODE(f,local) != SF_READ && _sfmode(f,SF_READ,local) < 0)
{ n = s > begs ? s-begs : (size_t)(-1);
SFMTXRETURN(f, (ssize_t)n);
}
SFLOCK(f,local);
if((r = f->endb - f->next) > 0) /* has buffered data */
{ if(r > (ssize_t)n)
r = (ssize_t)n;
if(s != f->next)
memcpy(s, f->next, r);
f->next += r;
s += r;
n -= r;
}
if(n <= 0) /* all done */
break;
if(!(f->flags&SF_STRING) && !(f->bits&SF_MMAP) )
{ f->next = f->endb = f->data;
/* exact IO is desirable for these cases */
if(SFDIRECT(f,n) ||
((f->flags&SF_SHARE) && f->extent < 0) )
r = (ssize_t)n;
else if(justseek && n <= f->iosz && f->iosz <= f->size)
r = f->iosz; /* limit buffering */
else r = f->size; /* full buffering */
/* if read almost full size, then just do it direct */
if(r > (ssize_t)n && (r - r/8) <= (ssize_t)n)
r = (ssize_t)n;
/* read directly to user's buffer */
if(r == (ssize_t)n && (r = SFRD(f,s,r,f->disc)) >= 0)
{ s += r;
n -= r;
if(r == 0 || n == 0) /* eof or eob */
break;
}
else goto do_filbuf;
}
else
{ do_filbuf:
if(justseek)
f->bits |= SF_JUSTSEEK;
if(SFFILBUF(f,-1) <= 0)
break;
}
}
SFOPEN(f,local);
r = s-begs;
SFMTXRETURN(f, r);
}
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