/***********************************************************************
* *
* 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"
/* Push back one byte to a given SF_READ stream
**
** Written by Kiem-Phong Vo.
*/
#if __STD_C
static int _uexcept(Sfio_t* f, int type, Void_t* val, Sfdisc_t* disc)
#else
static int _uexcept(f,type,val,disc)
Sfio_t *f;
int type;
Void_t* val;
Sfdisc_t *disc;
#endif
{
NOTUSED(val);
/* hmm! This should never happen */
if(disc != _Sfudisc)
return -1;
/* close the unget stream */
if(type != SF_CLOSING)
(void)sfclose((*_Sfstack)(f,NIL(Sfio_t*)));
return 1;
}
#if __STD_C
int sfungetc(Sfio_t* f, int c)
#else
int sfungetc(f,c)
Sfio_t* f; /* push back one byte to this stream */
int c; /* the value to be pushed back */
#endif
{
reg Sfio_t* uf;
SFMTXDECL(f);
SFMTXENTER(f, -1);
if(c < 0 || (f->mode != SF_READ && _sfmode(f,SF_READ,0) < 0))
SFMTXRETURN(f, -1);
SFLOCK(f,0);
/* fast handling of the typical unget */
if(f->next > f->data && f->next[-1] == (uchar)c)
{ f->next -= 1;
goto done;
}
/* make a string stream for unget characters */
if(f->disc != _Sfudisc)
{ if(!(uf = sfnew(NIL(Sfio_t*),NIL(char*),(size_t)SF_UNBOUND,
-1,SF_STRING|SF_READ)))
{ c = -1;
goto done;
}
_Sfudisc->exceptf = _uexcept;
sfdisc(uf,_Sfudisc);
SFOPEN(f,0); (void)sfstack(f,uf); SFLOCK(f,0);
}
/* space for data */
if(f->next == f->data)
{ reg uchar* data;
if(f->size < 0)
f->size = 0;
if(!(data = (uchar*)malloc(f->size+16)))
{ c = -1;
goto done;
}
f->flags |= SF_MALLOC;
if(f->data)
memcpy((char*)(data+16),(char*)f->data,f->size);
f->size += 16;
f->data = data;
f->next = data+16;
f->endb = data+f->size;
}
*--f->next = (uchar)c;
done:
SFOPEN(f,0);
SFMTXRETURN(f, c);
}