Imported Upstream version 93u+upstream

1 files changed, 116 insertions, 0 deletions

diff --git a/src/lib/libast/sfio/sffilbuf.c b/src/lib/libast/sfio/sffilbuf.c
new file mode 100644
index 0000000..16d5e3a
--- /dev/null
+++ b/src/lib/libast/sfio/sffilbuf.c
@@ -0,0 +1,116 @@
+/***********************************************************************
+*                                                                      *
+*               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"
+
+/*	Fill the buffer of a stream with data.
+**	If n < 0, sffilbuf() attempts to fill the buffer if it's empty.
+**	If n == 0, if the buffer is not empty, just return the first byte;
+**		otherwise fill the buffer and return the first byte.
+**	If n > 0, even if the buffer is not empty, try a read to get as
+**		close to n as possible. n is reset to -1 if stack pops.
+**
+**	Written by Kiem-Phong Vo
+*/
+
+#if __STD_C
+int _sffilbuf(Sfio_t* f, reg int n)
+#else
+int _sffilbuf(f,n)
+Sfio_t*	f;	/* fill the read buffer of this stream */
+reg int	n;	/* see above */
+#endif
+{
+	reg ssize_t	r;
+	reg int		first, local, rcrv, rc, justseek;
+	SFMTXDECL(f); /* declare a local stream variable for multithreading */
+
+	SFMTXENTER(f,-1);
+
+	GETLOCAL(f,local);
+
+	/* any peek data must be preserved across stacked streams */
+	rcrv = f->mode&(SF_RC|SF_RV|SF_LOCK);
+	rc = f->getr;
+
+	justseek = f->bits&SF_JUSTSEEK; f->bits &= ~SF_JUSTSEEK;
+
+	for(first = 1;; first = 0, (f->mode &= ~SF_LOCK) )
+	{	/* check mode */
+		if(SFMODE(f,local) != SF_READ && _sfmode(f,SF_READ,local) < 0)
+			SFMTXRETURN(f,-1);
+		SFLOCK(f,local);
+
+		/* current extent of available data */
+		if((r = f->endb-f->next) > 0)
+		{	/* on first iteration, n is amount beyond current buffer;
+			   afterward, n is the exact amount requested */
+			if((first && n <= 0) || (!first && n <= r) ||
+			   (f->flags&SF_STRING))
+				break;
+
+			/* try shifting left to make room for new data */
+			if(!(f->bits&SF_MMAP) && f->next > f->data &&
+			   n > (f->size - (f->endb-f->data)) )
+			{	ssize_t	s = r;
+
+				/* try to maintain block alignment */
+				if(f->blksz > 0 && (f->here%f->blksz) == 0 )
+				{	s = ((r + f->blksz-1)/f->blksz)*f->blksz;
+					if(s+n > f->size)
+						s = r;
+				}
+
+				memmove(f->data, f->endb-s, s);
+				f->next = f->data + (s-r);
+				f->endb = f->data + s;
+			}
+		}
+		else if(!(f->flags&SF_STRING) && !(f->bits&SF_MMAP) )
+			f->next = f->endb = f->endr = f->data;
+
+		if(f->bits&SF_MMAP)
+			r = n > 0 ? n : f->size;
+		else if(!(f->flags&SF_STRING) )
+		{	r = f->size - (f->endb - f->data); /* available buffer */
+			if(n > 0)
+			{	if(r > n && f->extent < 0 && (f->flags&SF_SHARE) )
+					r = n;	/* read only as much as requested */
+				else if(justseek && n <= f->iosz && f->iosz <= f->size)
+					r = f->iosz;	/* limit buffer filling */
+			}
+		}
+
+		/* SFRD takes care of discipline read and stack popping */
+		f->mode |= rcrv;
+		f->getr = rc;
+		if((r = SFRD(f,f->endb,r,f->disc)) >= 0)
+		{	r = f->endb - f->next;
+			break;
+		}
+	}
+
+	SFOPEN(f,local);
+
+	rcrv = (n == 0) ? (r > 0 ? (int)(*f->next++) : EOF) : (int)r;
+
+	SFMTXRETURN(f,rcrv);
+}