1 files changed, 108 insertions, 0 deletions
diff --git a/src/lib/libast/sfio/sfungetc.c b/src/lib/libast/sfio/sfungetc.c
new file mode 100644
index 0000000..08ccc6d
--- /dev/null
+++ b/src/lib/libast/sfio/sfungetc.c
@@ -0,0 +1,108 @@
+/***********************************************************************
+*                                                                      *
+*               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);
+}