Imported Upstream version 93u+upstream

1 files changed, 115 insertions, 0 deletions

diff --git a/src/lib/libast/sfio/sfstack.c b/src/lib/libast/sfio/sfstack.c
new file mode 100644
index 0000000..bc2ab13
--- /dev/null
+++ b/src/lib/libast/sfio/sfstack.c
@@ -0,0 +1,115 @@
+/***********************************************************************
+*                                                                      *
+*               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/pop streams
+**
+**	Written by Kiem-Phong Vo.
+*/
+
+#define STKMTXLOCK(f1,f2) \
+	{ if(f1) SFMTXLOCK(f1); \
+	  if(f2) SFMTXLOCK(f2); \
+	}
+#define STKMTXRETURN(f1,f2,rv) \
+	{ if(f1) SFMTXUNLOCK(f1); \
+	  if(f2) SFMTXUNLOCK(f2); \
+	  return(rv); \
+	}
+
+#if __STD_C
+Sfio_t* sfstack(Sfio_t* f1, Sfio_t* f2)
+#else
+Sfio_t* sfstack(f1,f2)
+Sfio_t*	f1;	/* base of stack	*/
+Sfio_t*	f2;	/* top of stack	*/
+#endif
+{
+	reg int		n;
+	reg Sfio_t*	rf;
+	reg Sfrsrv_t*	rsrv;
+	reg Void_t*	mtx;
+
+	STKMTXLOCK(f1,f2);
+
+	if(f1 && (f1->mode&SF_RDWR) != f1->mode && _sfmode(f1,0,0) < 0)
+		STKMTXRETURN(f1,f2, NIL(Sfio_t*));
+	if(f2 && (f2->mode&SF_RDWR) != f2->mode && _sfmode(f2,0,0) < 0)
+		STKMTXRETURN(f1,f2, NIL(Sfio_t*));
+	if(!f1)
+		STKMTXRETURN(f1,f2, f2);
+
+	/* give access to other internal functions */
+	_Sfstack = sfstack;
+
+	if(f2 == SF_POPSTACK)
+	{	if(!(f2 = f1->push))
+			STKMTXRETURN(f1,f2, NIL(Sfio_t*));
+		f2->mode &= ~SF_PUSH;
+	}
+	else
+	{	if(f2->push)
+			STKMTXRETURN(f1,f2, NIL(Sfio_t*));
+		if(f1->pool && f1->pool != &_Sfpool && f1->pool != f2->pool &&
+		   f1 == f1->pool->sf[0])
+		{	/* get something else to pool front since f1 will be locked */
+			for(n = 1; n < f1->pool->n_sf; ++n)
+			{	if(SFFROZEN(f1->pool->sf[n]) )
+					continue;
+				(*_Sfpmove)(f1->pool->sf[n],0);
+				break;
+			}
+		}
+	}
+
+	if(f2->pool && f2->pool != &_Sfpool && f2 != f2->pool->sf[0])
+		(*_Sfpmove)(f2,0);
+
+	/* swap streams */
+	sfswap(f1,f2);
+
+	/* but the reserved buffer and mutex must remain the same */
+	rsrv = f1->rsrv; f1->rsrv = f2->rsrv; f2->rsrv = rsrv;
+	mtx = f1->mutex; f1->mutex = f2->mutex; f2->mutex = mtx;
+
+	SFLOCK(f1,0);
+	SFLOCK(f2,0);
+
+	if(f2->push != f2)
+	{	/* freeze the pushed stream */
+		f2->mode |= SF_PUSH;
+		f1->push = f2;
+		rf = f1;
+	}
+	else
+	{	/* unfreeze the just exposed stream */
+		f1->mode &= ~SF_PUSH;
+		f2->push = NIL(Sfio_t*);
+		rf = f2;
+	}
+
+	SFOPEN(f1,0);
+	SFOPEN(f2,0);
+
+	STKMTXRETURN(f1,f2, rf);
+}