Imported Upstream version 93u+upstream

1 files changed, 140 insertions, 0 deletions

diff --git a/src/lib/libast/sfio/sfread.c b/src/lib/libast/sfio/sfread.c
new file mode 100644
index 0000000..a3aed97
--- /dev/null
+++ b/src/lib/libast/sfio/sfread.c
@@ -0,0 +1,140 @@
+/***********************************************************************
+*                                                                      *
+*               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"
+
+/*	Read n bytes from a stream into a buffer
+**
+**	Written by Kiem-Phong Vo.
+*/
+
+#if __STD_C
+ssize_t sfread(Sfio_t* f, Void_t* buf, size_t n)
+#else
+ssize_t sfread(f,buf,n)
+Sfio_t*		f;	/* read from this stream. 	*/
+Void_t*		buf;	/* buffer to read into		*/
+size_t		n;	/* number of bytes to be read. 	*/
+#endif
+{
+	reg uchar	*s, *begs;
+	reg ssize_t	r;
+	reg int		local, justseek;
+	SFMTXDECL(f);
+
+	SFMTXENTER(f, (ssize_t)(-1));
+
+	GETLOCAL(f,local);
+	justseek = f->bits&SF_JUSTSEEK; f->bits &= ~SF_JUSTSEEK;
+
+	if(!buf)
+		SFMTXRETURN(f, (ssize_t)(n == 0 ? 0 : -1) );
+
+	/* release peek lock */
+	if(f->mode&SF_PEEK)
+	{	if(!(f->mode&SF_READ) )
+			SFMTXRETURN(f, (ssize_t)(-1));
+
+		if(f->mode&SF_GETR)
+		{	if(((uchar*)buf + f->val) != f->next &&
+			   (!f->rsrv || f->rsrv->data != (uchar*)buf) )
+				SFMTXRETURN(f, (ssize_t)(-1));
+			f->mode &= ~SF_PEEK;
+			SFMTXRETURN(f, 0);
+		}
+		else
+		{	if((uchar*)buf != f->next)
+				SFMTXRETURN(f, (ssize_t)(-1));
+			f->mode &= ~SF_PEEK;
+			if(f->mode&SF_PKRD)
+			{	/* actually read the data now */
+				f->mode &= ~SF_PKRD;
+				if(n > 0)
+					n = (r = sysreadf(f->file,f->data,n)) < 0 ? 0 : r;
+				f->endb = f->data+n;
+				f->here += n;
+			}
+			f->next += n;
+			f->endr = f->endb;
+			SFMTXRETURN(f, n);
+		}
+	}
+
+	s = begs = (uchar*)buf;
+	for(;; f->mode &= ~SF_LOCK)
+	{	/* check stream mode */
+		if(SFMODE(f,local) != SF_READ && _sfmode(f,SF_READ,local) < 0)
+		{	n = s > begs ? s-begs : (size_t)(-1);
+			SFMTXRETURN(f, (ssize_t)n);
+		}
+
+		SFLOCK(f,local);
+
+		if((r = f->endb - f->next) > 0) /* has buffered data */
+		{	if(r > (ssize_t)n)
+				r = (ssize_t)n;
+			if(s != f->next)
+				memcpy(s, f->next, r);
+			f->next += r;
+			s += r;
+			n -= r;
+		}
+
+		if(n <= 0)	/* all done */
+			break;
+
+		if(!(f->flags&SF_STRING) && !(f->bits&SF_MMAP) )
+		{	f->next = f->endb = f->data;
+
+			/* exact IO is desirable for these cases */
+			if(SFDIRECT(f,n) ||
+			   ((f->flags&SF_SHARE) && f->extent < 0) )
+				r = (ssize_t)n;
+			else if(justseek && n <= f->iosz && f->iosz <= f->size)
+				r = f->iosz;	/* limit buffering */
+			else	r = f->size;	/* full buffering */
+
+			/* if read almost full size, then just do it direct */
+			if(r > (ssize_t)n && (r - r/8) <= (ssize_t)n)
+				r = (ssize_t)n;
+
+			/* read directly to user's buffer */
+			if(r == (ssize_t)n && (r = SFRD(f,s,r,f->disc)) >= 0)
+			{	s += r;
+				n -= r;
+				if(r == 0 || n == 0) /* eof or eob */ 
+					break;
+			}
+			else	goto do_filbuf;
+		}
+		else
+		{ do_filbuf:
+			if(justseek)
+				f->bits |= SF_JUSTSEEK;
+			if(SFFILBUF(f,-1) <= 0)
+				break;
+		}
+	}
+
+	SFOPEN(f,local);
+	r = s-begs;
+	SFMTXRETURN(f, r);
+}