/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2011 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 "sfhdr.h"
/* Safe access to the internal stream buffer.
** This function is obsolete. sfreserve() should be used.
**
** Written by Kiem-Phong Vo (06/27/90).
*/
#if _BLD_sfio && defined(__EXPORT__)
#define extern __EXPORT__
#endif
#if __STD_C
extern ssize_t sfpeek(reg Sfio_t* f, Void_t** bp, reg size_t size)
#else
extern ssize_t sfpeek(f,bp,size)
reg Sfio_t* f; /* file to peek */
Void_t** bp; /* start of data area */
reg size_t size; /* size of peek */
#endif
{ reg ssize_t n, sz;
reg int mode;
/* query for the extent of the remainder of the buffer */
if((sz = size) == 0 || !bp)
{ if(f->mode&SF_INIT)
(void)_sfmode(f,0,0);
if((f->flags&SF_RDWRSTR) == SF_RDWRSTR)
{ SFSTRSIZE(f);
n = (f->data+f->here) - f->next;
}
else n = f->endb - f->next;
if(!bp)
return n;
else if(n > 0) /* size == 0 */
{ *bp = (Void_t*)f->next;
return 0;
}
/* else fall down and fill buffer */
}
if(!(mode = f->flags&SF_READ) )
mode = SF_WRITE;
if((int)f->mode != mode && _sfmode(f,mode,0) < 0)
return -1;
*bp = sfreserve(f, sz <= 0 ? 0 : sz > f->size ? f->size : sz, 0);
if(*bp && sz >= 0)
return sz;
if((n = sfvalue(f)) > 0)
{ *bp = (Void_t*)f->next;
if(sz < 0)
{ f->mode |= SF_PEEK;
f->endr = f->endw = f->data;
}
else
{ if(sz > n)
sz = n;
f->next += sz;
}
}
return (sz >= 0 && n >= sz) ? sz : n;
}